The heat balance in the Caron-Clevengerprocess of treating manganese silver ores

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Authors Mishler, Ralph Thomas

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The Heat Balance in the Caron - Clevenger

process of Treating Mangsmeae - Silver Ores.

DyRalph T. Mishier.

_____. _____ . _____. ____ . _____

Submitted in partial fulfillment of the

requirements for the degree of

Mining Engineer.

in the College of Mines and Engineering of the

University of Arizona.

1930.

E97?)7930~a/

THE HEAT BALAHCE IH THE CARQg-CLETSB&ER PROCESS OF TREATIBO

MASQA1ESE - SILVER ORES.

CHAPTER

1

23

4

5

6 n 8 9

101112

13

14

15

16

17

TABLE OF COHTEHTS.Page

Introduction

Ore

Heat lost to atmosphere

Con&uetiYitjr of Shell and. Lining

Transmission between Hot Gas and Ore, or Lining

Heat Transfer; Lining to Ore and Reverse

Radiation from Kiln Lining to Ore Surface

Gas Producers

Fuel Values

Fuel

Producer Gas

Heat Losses in Producers(a) Sensible Heat of Producer Gas(b) Ashesto) Evaporating Moisture(d) Convection and Radiation from Hot Shell

Steam.

Heat Balance of Producers

Gas Mains

Kiln

Cooling Zone of Kiln

3591113162426272831353535353759424445 47

76709

a.

CHAPTER ■ ” Page

18 Kiln Temperatures 51

IS Dimensions of Lined Portion of Kiln 68

20 Zones in Lined Portion of Kiln 54

21 Soaking Zone @6

. 22 Air Hain 6823 . Combustion Zone 66

24 Third Burner Division of Combustion Zone ?8

25 Second Burner Division of Combustion ZoneTS

26 PI ret Burner Division of Combustion Zone 78

27 . Evaporation Zone 81

28 Portion of Peed Zone Outside Dust Chaaberes

2t Last 1^- Feet at Feed End of, Feed Zone 90

30 General Heat Balances 93

Charts 95 - 104

List of Charts , 105

list of Tables 106 - 109

THE H EAT B A L M CIS H I THE OARGH- CXEV13I G SR P R O C E SS O F TR E A T H IG H /iIIG A H E S E ~ S IL V E R O R E S ._ _ _ _ _ _ _ _

CHAPTER 1 . IS T R O H J O T IO H ,

A description of the Caron-Clevenger process is

publised in Bulletin 226 of the Bureau of-Mines of the

Haltod States Government. The process is applicable for

treating oxidized silver ores in which the silver is

combined with the higher oxides of manganese in such a

manner that it oan-not be recovered by ordinary

hydrometallurgical methods. The object of the process

is to reduce the higher oxides of manganese. This frees

the silver and renders it amenable to subsequent

eyanidation. The process is essentially a reducing roast,

the ore being first heated to between 1000° and 1200° F,

and then cooled in a reducing atmosphere. The roast is

effected in a rotary kiln, of the kind commonly employed

in the cement industry. The ore, previously crushed to

1& inches, is admitted to the head end of the kiln.

Producer gas enters the discharge end through a suitable

seal. Air is introduced through burners situated along the

axis of the central third of the kiln, and is burned in

the atmosphere of gas. The third of the kiln nearest the

discharge end is left unlined to facilitate radiation. In

this section the ore is cooled in the gas atmosphere and is

t

4.

finally dlaohsrged through a solution seal. The

essential details of construction are illustrated on

Plate 8.

this article deals with the heat balance of

the process as applied to the ore of the El Eavor mine

(situated in Jalisco, Mexico). The calculations are based

on data collected during October and November of 1928

and on constants and formulas recorded in various hand

books on mechanics and metallurgy. British units of heat,

weight and measure are employed, unless otherwise stated.

Important multiplications are made with a Brunsviga; non

imp or tan t calculations are made by slide-rule.

t

5.

CHAP !PER 2 : O R E

The ore consists of the oxides of manganese and .

iron in a sill cions gangue, with minor quantities of

calcite and zincite. As delivered from the mine, the

ore contains 5$ moisture, including 0.6# water of

orystalization, which is expelled just above boiling

point. Steam dried ore has the following composition:

TABLE 1 : CHEMICAL AUALYSIS OF EL FAVOR ORE

Gold SilverHh as MhOg Ito as lower Cbcides Iron Calcium Zinc Silica 0. C02 Etc. by diffe

.07^ •

l

.05 Oz. per 19.47 " "

On the basis of the proceeding analysis, the per

centage of minerals in the ore is probably approximately

as follows:

TABLE 2 : HDfERAL COHSTITUEHTS OF EL FAVOR ORE

MINERALS

Pyrolusite (and PsilManganiteHausmaniteHematiteZinciteCalciteSilica

100.00

The Specific Gravity of the ore may be calculated

the proportions of minerals:

TAJ&B 3: SPECIFIC GRAVITY OF Eh FAVOR ORE.

u m E M M

Pyrolusite

PR0P0RTI01T.

.0058 X 4,8 % .028llanganite .0542 X 4.3 S .233Hausmanite .0470 X 4 8 5 * .228Hematite .0340 X 5.1 s .173Zincite .0114 X 5.56 3 .068Calcite .0680 X 2*71 3 .171Silica .7846 X 2.656 3 2.084

2*9ouThe *Iea01 , as determined by

was 2.995, which closely checks the proceeding calcula

tions. The weight per cubic foot would therefore be 187

Crushed to !•£ inches, the Specific Gravity of the ore (including voids) measures 1.25, or 78 lbs; per cubic

foot.

The Specific Heat of the ore may be calculated from

the specific heat of its constituents. Eichards

(Metallurgical Calculations, pages 123-142) gives the

specific heats of various minerals. For Hematite, Zincite,

and Silica, he gives the specific heat, complete with

corrections for temperature. For Pyrolusite, man-

ganite and caloite, he quotes specific heat values deter

mined by Kopp and Regnault, and shows a method for

approximating temperature corrections. On page 126, he

gives a method for calculating the specific heat of

metalic oxides (such as hausmanite) the specific heats

of shieh have not been determined. Following are the

specific heats of the various minerals, determined by

the above methods, together with specific heat of the

ore calculated therefrom: 1

TABLE 4 : SPECIFIC HE A 5 OF EL FAVOR ORE

' ' Specific HeatMineral Proportion Mineral ! ' tirePyrolusiteMsnganiteHausmaniteHematiteZinciteCaloiteSilica

f.0058 x (.iseot.ooomt;.0542 x [.1724+.000141t .0470 X (.1393+.000116t .0340 x (.14564..000376t .0114 x ( .12124..000063t .0630 x (.20004-.000167t .7846 X (.18334..000154t

= .00090+ .000^007,4t =.00934+.00000764t =.00655+.00000545t =.00495+,00001279t •.00138+.00000072t = .012604. .000010526 =.14382+.000120836

Total * Spe#. Gravity of Ore = C s .17954+.0001586ft(Eg.. 1)Between 400°$* and 900°F, the manganese minerales^

loose a part of their oxygen and are largely altered tomanganosite (HnO). The specific heat of the roasted

Jcalcines is therefore slightly different from that of

crude ore. By a method similar to that employed in

I

8.

Table 4, the specific heat of the roasted calcines may be

shorn to he: C = .1794 + .0001633t. (Eq,. 2)■ ■ t ■The factor ntn in equations 1 and 2 represents tem

perature centigrade.

In Table 5, the specific heat of the ore and cal

cines is calculated for various Parenheit temperatures.

TABLE 5 - • SPECIFIC HEAT OF ORE AHD GALOIIiE :

Temperature Temperature SPECIFIC_______ HEAT¥ C Ore Calcines

32 0 .1795 .1794.400 204 .2119 .2127900 482 .2581

The values calculated in Table 5 are plotted on

Plate 2. It will be noted that the two curves practi

cally coincide.

I

9.

CHAPTER 5 I

H5A.T LOST TO ATHOSPHERS FROM HOT SHELL

Two presentations of this subject are available, one

by Langmuir (Richard’s Met. Calc. P.213) and a second by

The Mellon Institute (Kents M. E. Handbook P. 633).

In Langmuir’s calculations the losses by radiation

and convection are segregated. Ho gives the convection

losses downwards and upwards, from horizontal and verti

cal surfaces; and also gives a factor (\/35+v in which

v is the velocity in centimeters per second ) by which

to multiply the convection loss when the air (or the hot

surface) is in movement. For radiation, Langmuir employs

Stefan’s formula: s B l.dlxMf12 (T* - fff; in which %

is the heat radiated in calories, E is the emissivity of

the radiating surface (.47 for sheet steel) and fg and %

are the absolute centigrade temperatures respectively of

the radiating surface and of its surroundings. In Table

6 the convection and radiation losses from stationary and

revolving surfaces are calculated from Langmuir’s

figures, y ; \ : :

Table 7 presents the results of experiments on con-

veetion and radiation, conducted by The Mellon Institute,

with minor corrections for movement as indicated by Lang

muir’s findings.

'i

10*

g A B L E 6C0HVE0TIQH AHD RADIATIOB ,LOSSES ER021 SHELL ________ ( LABGHUIR )___________________

Atmosphere Temperature 27°C or 80°F

M R ? _______ _ -J.9X0 g d? 49I0..671?..Stationary Vertical (Surfac 6; BfU l Radiation Per Hr. Per Sq., ( TOTML Ft. of Surface*Rerol. Kil (Ka. T, 2 ^BfU K r H Ft. of Surface,

664 98299 369' 877 1732

165 764 1641 2714

13143069

Per B^r. F 1.26 2.42 3.14 4.04 5.14U T 594.. 876'..117T

Con.(Rot.) 64 360 654 664 1266Baaiation 9 9 3 6 9 877 1732

TOtAI, 183 14M 1531Per Beg. F. 1.40 2.41 3.12 4.01 5.12

Hote: The factor, applied to the convection for the revo

lution of the kiln was 1.101.

T A B L E-7 :

HEAT LOSSES FROM FURHACR SHELL ( HELLOH IHSTITUTE )

Atmosphere Temperature 70° F.B. T. U. per Hour per Sq. Ft.

Per Beg. F (Stat. Vert. Surf, nfemp/lfcff. (Revolv. Kiln For Specified (Stat. Vert. Sur& Bmp/BlfC. (Hevolv. Kiln

% s a a305 936 2146 4019

The values shoun in Tables 18 and 19 are plotted on

Plate 4.

I

11.CHAPTER 4 :

coinxjcgmgY o f s h e l l a k d l i h i s g

The conductivity of steel at 64° F, as given by

various authorities, varies from 313 to 334 BTC per hour,

per degree F, per square foot of surface, per inch of depth.

The average may be taken as 323. Ho temperature correction

is available for steel. From analogy with corrected values

for oast and wrought iron, the corrected conductivity of

steel may be assumed to be fairly well represented by the

formula K (British units) = 327-.07t, (Eq. 3) in which "t"

is the temperature Fahrenheit. The eonduetivity of the

shell is so much greater than that of the lining that it

can be. disregarded in.most calculations.

The eonduetivity of fire-brick, for various tempera

tures and various classes is given by Boyd Dudley Jr., on

page 640 of Kents H. E* Handbook, The averages for birck made of fire clay are as follows:

T A B L E SCOIIPCCTIVITY OF FIRE BRICK :

Temperature ConductivityF (British Unite)

S.ff

9.10

The values recorded in Table 8 are plotted on Plate

8.

t

- 12 -

The conductivity of Siloed rotary-kiln-brick, for

various temperatures as given by the manufacturer, (The Cel-

ite Products Co#) is likewise plotted on Plate 5. At SI Sa-- ■.vor one fire brick in a circle of 26, is extended to the

shell, for the purpose of anchoring the lining against a

longitudinal angle iron riveted to the shell. To avoid more

complicated calculations, the conductivity of this fire brick is averaged with that of the insulating brick in the rest of the circle, and the averages are plotted on Plate 3.

t

CHAPTER 5: TBAH3MISSI0H BETWBEH HOT GAS AHB' ~~ ORE OR LIHIHG AHD REVERSE.

Considerable data is available on the transmission

of heat from hot gases to boiler tubes. Richards, Poele,

Rankino, Langmuir, Carrier and Bussey, Fessenden and Haney

and The Combustion Engineering Co. all present formulas

for the solution of this problem. Some present two or

more formulas for different conditions. Others give a

wide range of eoastante to be used for varying conditions.

Hone of the authorities claim that his formula is

generally applicable.

In the absence of concordant data on the subject,

all the formulas available have been solved for the

special conditions at 21 Favor. Formulas, developed for

steam boiler calculations, without correction for gas

velocity have been modified to include this factor by applying Langmuir's velocity formula.(See Chapter 3). Other formulas giving the heat transmitted from gas,

through metal to water, have been corrected for the

resistivity of the metal and water films. A large

volume of figures has been compiled in making these calculations, none of which are considered pertinent to this

article. The final results are shorn on Plate 5, the

heat transmitted per hour per square foot, per degree F

of temperature difference being plotted for varying gas

13.

14.

velocities occurring in the kiln. An inspection of Plate

5 will illustrate the lack of uniformity of the values

derived from different formulas. It is impossible to show

that any one of the formulas is more applicable to the case in hand than any of the others; so it was thought best

to tentatively accept the average of all the formulas, as

a general principle, and later correct this average to agree with actual results in the kiln. The average of the formu

las is plotted on Plate 5 under the name "Average”. A

complete calculation of heat transmission in the kiln, us

ing the "average” transmission values, showed that these

values were too low. A second calculation, with higher transmission values proved too high. A third set of cal

culations with transmission constants interplotted between the proceeding two sets proved satisfactory. The third

set of constants corresponds to the formulaj Kr.704-.627 BUT

per hour per square ft. per degree F temperature difference,

(Eq. 4) in which 7 is the gas velocity in feet per second.

The surface of the ore is inclined at an angle of

about 45°. According to tables submitted by Langmuir (Rich

ards Met. Calc, p.213) the transmission of heat to a sur

face in this position would be only 835^of the average

transmitted to the entire periphery of the gas passage. On the other hand, the ore surface is in constant cascading

I

movement as the kiln revolves. Both the movement of

the ore and the occasional exposure of the entire sur

face of ore particles to the action of hot gases would

increase the convection of heat from the hot gases to

the ore, thus offsetting the effect of the position of

the ore surfhoe.

Kent (page 60S) gives the conductivity of quartz

as 50 to 95 BTU per sq. ft., per inch, per degree F.

Since Favor ore contains 78^quartz- (Table 3) it is

safe to assume a conductivity of 30 for solid ore frag

ments. This is so much greater than the transmission

of heat from gas to solids that it can be safely dis

regarded.

Hough calculations show that the maximum tem

perature drop from the surface to the center of the

largest fragments is probably about 20° F.

15.

k

16.*CHAPTER 6 : HEAT TRAUSPER; LIHIUG TO ORE

_________M R REVERSE_________ ;__

About half the heat received by the ore is absorbed

directly from the hot gases. The other half is first ab

sorbed by the brick lining and later (as the lining re

volves beneath tho ore) is transferred to the ore by con

duction.

While the lining is in eon tact with the hot gases,

a temperature gradient is established in the brick, with the surface very hot and the underlying layers cooler and

eeeler. While the lining is in contact with the ore, a reversal of the heat flow occurs and the temperature

gradient is neutralized. This fact, together with the

relatively high conductivity of brick as regards ore,

greatly simplifies calculations, for it enables us to disregard the temperature gradient in the brick.

Another simplification of the calculations may be

aaeomplished by disregarding the cyclic heating and

cooling of the brick surface and assuming that the tem

perature of any given circle of the brick surface is

constant. This assumption introduces an error of about

4 ^ i n the calculated heat flow from the gas to the lin

ing, and an opposite and practically equal error in the

I

hoat flow from tho lining to tho oro. Sinco theao errors

are oomponsating, the temperature of tho lining ourfaoo

will be regarded aa constant, in so far as tho cyclic

changes of temperature aro oonoomod.

In calculating the heat transferred from lining

to ore, it la necessary to ta3:o into consideration tho

conductivity, specific .heat and density of the ore end

the time the oro Is in .contact with the lining.

Conductivity (K) of crushed oro must bo calcu

lated from known conductivities of similar products.

17.

Products Authority tomporaturo BTU Sys-_____________ ________________________ P tern K.

Soil, very dry & light Kent (low) 2.50Soil, very dry Liddell 2.50Quarts Sand Richards 64 - 208 1.74Sand . Kent 2.70Coarse Sand 58g Solids Hering 68 - 312 2.50Fine " 61fS » 68 - 312 2.52Ceaerete Cinder Liddell 2.35

Average (assumed for Crushed Ore) 106b 2.40

Ehe average solids in the above products is about

5 ^ . Crushed Favor ore is only 42^_solids. Since

oonduotivity is approzimatoly proportioned to tho per

centage of solids, it is probably safest to reduce the

average conductivity calculated above, by the factor

I ir-

18.

•4E/.52; .42/52x2,40= 1.94.

The conductivities of flre-hrick and Silocel in

sulating brick are well known. (See Plate 3). Both in

crease with the temperature. By interpolating a line for

crushed ore between those for fire and insulating brick on

Plate 3, the conductivity of crushed ore may be shown to

be represented by the formula; K= 1.9+.000675$ (BTTJ Sys

tem) in which $ is the temperature Fahrenheit. The

following conductivities of crushed ore are derived from

the above formula:

Temperature Eahr. 100° 425° 750°" Cent. 38° 218° 39#°

K (BTO System) 1.97 2.19 2.41K (o.g.s. System) .000680 .000755 .000830

SPECIFIC H5AT (C) of the crushed ore and calcine has al

ready been shown to be represented by the formula :

0 = .180+00016$ (Eg.. 1 and 2), (T being the temperature

Centigrade). Based on this formula, the following table

gives the specific heat of ore for various temperatures:

Temperature Eahr. 100 425 750 1000« Cent. 38 218 399 537

C 3 Specific Ht. .187 .217 .245 .265

I }

DSE3ITY (P) of the crushed ore is shewn by test to be

1.25 gm per eo, or 78 Lbs. per on. ft. Since the

specific gravity of the solid ore is 3.0, the crushed

ore is only 4 ^ solids.

Tim (t) is the time that the ore is in contact with

the brick lining. Since the ore covers .27 of the sur

face of the lining and the kiln makes a revolution in 106

seconds, t s-106z.27 = 28.6 sec. or .00795 hours. After

each heating interval the heated particles may be con -

sidered as being thoroughly mixed into the mass of crush

ed ore. There are 1 f .00795 9 126 heating intervals per

19.

Fourier (Met. & Chem. Handbook, Lidell, p. 150)

has shorn that the temperature gradient may be calculated

from the following expression:

(Ea. 4)

in which:

To is the temperature (Gent.) at which the surface is

maintained above that of main body of the ore.

% is the corresponding temperature, t seconds later, at a

distance of X cm. from the hot surface.

f

20.h may be oaloulated fro® the following relation;

" , ' - ■ .in which;

K is the cgs condnetivity of the body (.00068; 000755; and

00083 for the range of temperatures assumedj.

0 is the specific heat (.187; .217 and .245 for assumed

temperatures).

P is the specific gravity .of the body » 1.25

The value of Fourier’s integral corresponding to

various values of Xf2hVt~are tabulated on page 151 of

Liddell1 s Met. & Che®. Handbook, and are plotted on Plate

6 attached to this article.

Based on Fourier1 s series, the temperature gradients

of crushed ore, for various ore temperatures,'are calcu

lated in Table 9, the various layers of ore being con

sidered 0.1 centimeter thick.

TABLE 9 ; TEMPERATURE: GRADIENTS III ORE ;

Ore Temperature (?) 100 425 750", " (0) 38 218 399

K ( ogs ) .000680 .000755 .000830_C .187 .217 .246

.own. 1.25.00278 1.25.00271I r S h V S S X

.05391.733%

.05261.773%

.05201.800%

X(CH)1.733 X

Tsnp.iM.(Bate 6) 1.773X 1.8001

.05 .087 ,903 .089 .901 .090 .900

.15 .260 .711 .266 .708 .270 .703

.25 .434 .538 .443 .530 *450 .524

.35 .608 .387 .621 .577 •63 .368

.45 .780 .269 .798 ,260 .81, .881

.55 .953 .177 .976 .168 .99 .161

.65 1.13 .IS t 1.15 .102 1.17 .096

.75 1.30 .065 1.33 009 1,35 ,000

.85 1.47 . .038 1.50 .033 1.53 .080

.95 1.65 .019 1.68 .018 1.71 • .0151.05 1.82 .m o 1.86 iOOt 1.89 .0081.15 1,99 .005 2.04 i004 * 0 9 ,0001.25 2.16 .00* 2.22 .002 2.25 .0011.55 2.34 .o m 2.39 tom 2.43 .OOX

of S a 3.172 ■ 3.117

The total heat transnittei. from/bride to ore dar

ing one cycle, expressed in calories per sq.aare centime

ter of surface per degree difference in temperature, is

given by the following equation:

Q. ~$PCdx T (Equation 5): 1 i * • ' .

dx is the thickness of the layers (in centimeters) into

which the ore is considered divided (taken as 0.1 centi

meters in the proceeding calculations).

|jD is the summation of the temperature increments (cal

culated in Table 9).

28.

peotively of the ore.

. Solving Eg.* 5 for the three temperatures assumed in

Table 9: ,

TABLE 10. : HEAT TRAUSHITTED EROH LiniUG. TO ORE :

Temperature (P) of Ore 100° 425° 750®PCftx - . . .0233 .0271 .0306=3 T . .QsCal. per S&.Cm. per . De&C.Tem. DLff.. Per Cycle

3.235 0 . 1 # 3.117

,0754 .0859 .0953

% s B T B per S%.Pt. per D%. F Temp.Dlff.por Cycle•

'

.1752,

» 8.04% - .1540 .1946Qs»BTU per Sq>Ft. per Deg.

F. Temj.^Diff. per"

19.4 22,1 24.5

The values of Qg determined in Table 10 are plotted on

Plate 7. The transmission of heat from shell to ore and

reverse for the special conditions in the feed zone of

the kiln were similarly calcnlatod and plotted on Plate 7.

These - constants will serve as the basis for calculating

the flow of heat from lining or shell to ore and the re

verse.

Calculations of heat transfer in the kiln indicate

that the values of

f

23,

discrepancy. (See Chapter 10). Also lower values

of Q, would have reduced a discrepancy between the calculated and pyrometer temperatures in the seeenA

burner division of the combustion zone. (Captor 25).

Had the values of Q, been lowered it would have been

necessary to increase the factors for transmission

of heat between gas and solid {determined in Chapter 5) in order to secure a balance in the heat transfer

in the kiln. Since the gas-solid factors had already

been raised, it was thought best to leave the values

of Q. as calculated in order to split the error.

• j

CHAPTER 7 : RADIATION FROM KIIH LINIlf©“ TO ORE SURFACE.________

Radiation from the. expose* portion of the lining

to the upper surface of the ore plays an important part

in the heating of the ore, especially at high tempera

tures. This is independent of the heat transmitted by

convection from the hot gases to surface of the ore.

The arched shape of the radiating surface above

the ore eliminates the distance factor and renders ra

diation proportioned to the surface of the ore.

Richards (Met. Calc. P.214) presents the ffllovr-

ing adaptation of Stefan1s law:

24,

in which E is the emiasivity constant (probably about .65

for ore and fire brick) and Tg and Tj_ are the absolute

temperatures (centigrade) of the radiating and receiving

surfaces.

Transformed to British units, the formula becomes:

in which Tg and T^ are the absolute temperature (Eahr) •

Qr e 1.41 B Ia! - (a)‘ Cal, per Second per Sq.. Cm.

BTtT per Hour

.25

of the radiating and receiving surfaces.Equation 6 has been solved for various tempera

tures and temperature differences and the results have

been plotted on Plate 9.

1.

26.

CHAPTER 8 :

GAS PRODUCERS

The gas plant consists of three 6 ,z9,.-6n v/ater

se ale 4 gas-pro duo era. Two are lined with t^jfire "brick;

the third is lined with one course of Silooel insulation

and 9" of fire brisk. Air for the producers is supplied

by a positive blower, operating at two pounds pressure (which is reduced to cue half pound pressure at the

bottom of the producers.) Steam is provided by a small

auxilliary boiler. A sketch of the gas plant is shown

on Plate 8".'

!

CHAPTER 9 :

w e l warns

The following fhel values are figure4

Hetallurgioal Calculations:

from Riohards

TABLE 11 : PDEL VALUES

Per lb.'' Of

Per lb..Of

C to C02 c to c

CHAPTER 1 0 s F U E L

Coke and oak charcoal are used in the following proportions:

a E W 1 7 “Hr. % HR.

_________________ ASH__________ ;______________

Coke 144 18 25.92 ;Charcoal 161 10 16.10TOTAL 305 13.8 42.02

28.

The ashes from the producers contain 30$ combus

tible matter and 70$. ash.

Ashes per hour s 42 r .70 » 60 Pounds

Unbumed combustible matter per hour

= 60 42 s 18 Pounds

Unburned Combustible matter per hour (including, corresponding ash) % 18 f .862 » 20.88 Pounds

Fuel available for gas = 305-20.88. 284.12 Lbs.

per hour.

Proportion of fuel available for gas

= 284.12 ? 305 * .931541

HOIS: The weights of fuel shorn in Table 12 are 16$.

less than recorded consumption. Part of this discre

pancy may have been due to errors in estimating con

sumption, the amount used having been determined by

St.

•minting wheel borrow. However, at least a part of the ,

Sisorepanoy must be considered as due to underestimating

the various heat losses about producers and kiln. It was

thought best to start the calculations with the weight of

fuel which would yield an exact heat balance, so that the

calculations of transfer of heat might have some value.

T A B L E 1 3 .

COMPOSITION OF

Geh# coal •% $ Coke. TOTAL

Available • for gas Entering Lbs. per Hr Gas Lbe. -.931541 T

HgO 1.0 5.0 1.44 8.05 9.49 8.8403e 80.0 73.6 115.80 118.50 833.70 817.7031 817.7011Ash 18.0 10.0 85.98 16.10 48.08 39.14340 4.0 6.44 6.44 s . r o i0 % .8 .38 .88 .8981 .8836H 1.0 - .1 1.44 88 1.76 1.6395E 7.0 11.87 11.87 20.4»85

total. 100.0 100.0 144.00 161.00 305.00 884.1800 817.9847

Lee Ash 39.1434

Gaseous Constituents 244.9766

*0.

T A B L E

VALLE( OF TOIL

Lba«

BTtJ per Lb,

Carbon CH4 H 4

21493.552254.

#«61.76

Hour ;

Bering

'SX7T7CH.2981

1.6395

Calorific value of Fuel enter-- g " , iug Gas : • Entering Ashes

A

BTU Per HourTOTAL Catering

Gas3,407,346 3,174,002

6,878 6,40791.967 85.670

3,5oti,191 3,166,159"“'

5.266,159

Calorific Value Per Lb. of Fuel

s 3,506,191 r 305 = 11,496, B. ’ T. U.

CHAPTER 11 t PKOHJOER GAS

In the following oaloulatlona it is assumed, that all the moisture in the

31.

fuel Is evaporated and enters the gas as moisture, and that all the steam and

moisture entering the eombustion zone with the air of eombustion is disaasoeiat-

ed, and enters the gas as hydrogen and methane.

TABLE 15 ; PRODUCER GA3

Lbs* 0 Per Lbs. Gas

HourErom Requir— Fuel # d ! -

CO* 2.5 .12267 .003067 4.166 .011361# 57.8971 4 42,1070 8 .1 .08981 .000089 .121 1.6816 5.9991 - 4,317GO 30.5 •07807 .023811 32,345 .1386214 449.5157 + 256.866c h4 1.5 .04464 •060670 .910 .0068860 12.6467 .8981 - 24,697H 4 H

7.258.2

i00559 .07831

.000402•045576

.54661.918

7.5881860,4840

1,639510.4985

- 47.589

TOTAL 100.0 KTable .-Gas pe

.073615 100.000 .1568088 1389.7532 18.4358 4 222,370

S&l 13)» HenurLbs. Gas per Hour e Lbs. 0 entering gas per Hr. • Lbs. 0 per Pound of Gas

= 217.9847 r .1568088 = 1389.7558 Lbs. COgO, Eta. per Hour

nitrogen accompanying required Oxygen = 222.37 x 3.78 = 840.56 Zounds per Hour.

Hitrogen according to gas analysis = 860.42 - 10.50 = 849.92 Pounds per Hour. . . .

Discrepancy 9.36 " * *Air required s 222.37 4- 840.56 s 1062.93 15s. per Hr. \ Water n =(24.697 + 47.589)xl8rl6*81.3218 I2)S. ierHr.

COHSgITOMTS OF GAS IBS. PER HOUR

Fuel Air SteamDiscrepancy

1398.59

A study of gas pressure and size of ..openings indi-

oates that 40 pounds of gas per hour escapes through the

charging hoppers and poke holes. This leaves 1358.593®

15s. of moist gas going to the kiln.

244.98 1062.93

81.32 . . 9.36

!

33.

TA3IE 16; PROHICER G±S TO KIM.

Lbs. of Gras Lbs. Gas ToCubic Feet.(Standard Conditions) to Kiln.

PerLb.&b kto Per Hr.Gas Kent P/ 184. to K i m .

Formed Per Hour.

ByWeight.

m mPer Hear.

00® 57.8971 4.14 56.2412 .8.152 458.50 1.6816 .12 1.6335 11.209 18.3CO 449.5157 ##.14 436.6595 12.810 5593*6c h 4 12.6467 .91 12.2850 22.429 275.5H 4 7.5881. .54 *.3711 178.931 1318.9H 860.4240 61.52 835•8157 12,770 10673.4HgO 8.8403 . 63 8.5875 28.000 240.5

Total 1398.5935 100.00 .1368.5935 18378.7 ‘

VolvmQ per Hr. at 3100 Ft. Elevation and 32°

1.1265 x 18,5787 = 20,929 Cnbio Fset.

Volume per Lb. at 3100 Feet Elevation and 32°

20,929 7 1358.51 = 15.4049 Cubic Feet

Lbs. 0 to Kiln per Hr. = 1358.59 7 1398.59 x 217.9247=211.692

TA3IE 17 KIEL VALDES OF PROIXJCSR GAS.

Per Lb. of 00 Eto. (Tab. 11)

GO 4 3 % ...CH4 21493.5 H 52254.

449#12.64677.5881

12.2850 271,822 264,0487.3711 396,508 385,169

2634,512 2559,166

Wasted at Producers 75,346 BUT per Hr.

BTU per Lb. = 2,634,512 f 1398.59 = 1,883,69

BTO per CU. FT. (Std. Cond) 2,559,166 7 18579 = 138

34.

.gJL&.ftg..M

SPSOIHO HEA5J OP GASES

Gao B. T. U. per Hr., ________ P. '

C02§00 %

J3+ •OOOlStS t SI§S$.38 + .0002441

.1900SB: illh2 3*37 4 00034t 3.3700 3.9820llo .8405 + 0000238t .42 t 000206t ■ s , ' sAir .8338 4 00002313t #83i58 • 2764

are plotted on Plate

f A B L S 19

Spoolflo Heat of producer Gae .25769 .31638

Tho opoolflo heat of the producer gas, calculated in

Table 19, is plotted on Plate 2.

CHAPTER IS; HEAT LOSSES IB PR0BDCEE3

. (S) .SENSIBLE HEAT OF P R O W C E R GAS:

Gas per Hour = 1,398.59 lbs. (Table 15} .

Temperature of Gas leaving Producers H 5 0 ° F

, Specific heat at l/2( 1150^75)° or 612° •• 279

(Plate 2). , . , . . ' ,

Sensible heat loss with gas = 1398.59(1150-75).279 ,

s 419,472 1B. T. U. per Hour

Sensible heat in gas escaping at producers 40(1150-75) . 279■ " .

' = 11.997 B. T. H. per.HourSensible Heat In

Gas to Kiln s 407,475 B. T. H. per Hour

(b) ASHES'

Ashes per Hour - 60 lbs. (Chapter 10)

Specific Heat of Ashes r .2

Approximate temperature at hood »1500°F. Sensible heat with ashes 60(1500o-75°) .2=17,100 BTUBrHr.

lOTSs This heat is included under radia-

ation and formation of steam.Fuel in ashes* 1811)0• per Hr.(Chap.10} Calorific value of fuel in ashes (Table 14)

» 240,032 B.T.U. Per Hr.

(c) EVAPORATIHG HOI STORE

Moisture in fuel 8.84031te. Per a?.(TaKLel3)

75°F.

Altitude 3100 Ft. At this elevation the boiling

point is 206 F and the atmospheric pressure 13 Lbs* per

square inch. The latent heat of evaporation at this

pressure is 974 BIO per Lb. (Marks Handbook p. 332). To

heat the moisture from 75° to 206° F, 131 BTO per Lb. of

water is required. Heat required per pound of water

* 974 f 131 = 1105 BID. Total heat requiredsllOB x 8.8403 «

9.769 BTU per hour.

Since the sensible heat in the steam is included

with that of the producer gas, and the sensible heat of

the latter is taken above 75°F, it is necessary to correct

the total heat estimated above by subtracting the heat

theoretically required to beat steam from 75° to 2060.

9.769 - 8.8403 (206 « 75) .442 = 9257 BTU per hour.

tI

Sf.

(a) COHVECTIOK AITD RADIATION FROM EOT 3KELLS A B L E 80

RABIASIOIT FROM TJIIIIISULASEI? PRO SUPERS

For One Proquoor;

External Diameter 6 Ft*; External surface per ft. of height

2 67fs 18.85 Square Feet

Air temperature arouna Producers, 100°F.

EsEmal Ave. (PK)0 Factor ZONE A SacSuK- Temp, F 5femp. Hate 4___________ Height Sq» Ft* OfSbe31 mfT. m 2 m H

Ashes 1.5 28.3 250 150 320Combustion 2.0 37.7 372 272 - 810Gas 4.0 75.4 290 190 460Top SB. SCover 44.0 220 120 250Hopper

i w i120 20 20

Cooling mter 300 Lbs.* (125* - 75*) TOTAL Per Producer

For Two Producers

Radiation BTU per Hr*

905630537

11000164:

m m

T A B L E 21RADIATION FROM IESUIATED PRODUCERS*

A External Are. CPim Factor BxB Surface Tamp. F Taap. Plate 4 Radiati-

Height Sq. Ft. Of S M I Dif& PerAshes 1.5 28.3 180 80Combustion 2.0 37.7 210 n oGas 4.0 75.4 200 100Top 44.0 200 100Hopper 8.2

1 9 5 3120 20

Cooling Water: 150 Lbs!(1250-75°) TOTAL rm* insulated ProducerRadiation from the three Producers

(constants of Mellon Institute)

140 3962220 8294200 15080200 880020

553#9T7500

3 m % r

244682

•88

The use of Lan®nuir* s constants (Plate 4) indi *

cates a heat loss from the shells of 97,850 B.T.IT. per

hoar. . - ; ■ - • ' ' : . .

The final heat balance of the producers (Tables

82 and 23) indicate a heat loss of 207 ,961 B.T.TJ. per

hour, which agrees more closely with the loss figured

from the constants of Mellon Institute than those of

Lengeelr.. , ■ ’ . ■ - ' , ■'.

39.CHAPTER 13; S T E A M

Steam required = 81.3218 lbs. per Hr. (Chap. 11)

Sensible heat in ashes at hood (Chap. 12b) 17,100

B.T.U. per hour.

Radiation from ashes zone (Tables 20&21) 13,018

B.T.TJ* per hour. ,

Heat remaining in Ashes, available for

forming steam 4,082

B.T.TJ. per hour.

Heat required to vaporize water from 75°P to steam at 206°F

r 1105 BiT.TIi per lb. (Chap; 12o)

Heat required to superheat steam to 1500°? (Plate 2)

2 .59 x 1294 = 763 B.T.TJ. per lb.

Total Heat = 1105 + 763 =1868 B. T. TJ. per lb.

Approximate weight of steam derived from ashes

2 4,082 ~ 1868 = 2;1852 Pounds

The average moisture content of the air at Savor is

30$ of saturation. At 75°F and with an atmospheric

pressure of 13 lbs. per square inch, saturated air contains

2.1$ moisture (Kent p. 662 and 658).

Moisture content of air at Thvor* .30x2.1* .63$

Air required in producers = 1062.93 lbs. per Hr.

(Chester 11)«

Moisture in air* .0063x1063.93= 6.6965 lbs. per Hr.

a 72.4401 lbs. per Hour

Heat required to vaporize water in boiler

72.4401x1105 = 80,047 BID p.Htt

Heat required to superheat steam to 300°(Plate 2)

72,4401(300-206) .465 = 3,166 BTD p.Hn; • : 83,213 ” ” ”

Thirty pounds of fuel per Hr. consumed in boiler.

Calofific value of fuel (Table 14) = 30x11,496.12

less heat used in

making steam 83.213 * • * 9 •

Balance 5 261,671 9 " 9 Heat loss in

boiler and steam mains.

Efficiency or Boiler = 83,213^344,884 s 24.1^

The heat theoretically required to heat the steam

from 75° to its final temperature on entering the produ

cers is included with the sensible heat in the gas. This

heat may be computed as follows: (X&CfOE) SEES. HEATM S . F S B ' (HA2E2 ) IE STEAM

i S S :9,125

The net heat required for vaporization may be calculated as follows:

Total Sensible l e tHeat Heat Heat Of

Steam from Ash.." " Boiler 83.313 7335 75,878Q*t t &9h 5̂I2ST V8,1V0

Heat required to dle&eeoeiate the steam

= 5,806 B. T. U. per Lt. (Table 11)

Total heat recfuired to disassoelate steam

r 5,806 x 81.348 = 473,154 BTtJ Per Hr.

This heat appears as calorific value in the

producer gas; so need not be considered in ordinary

heat balances.

*4% -CHAPTER 14: HEAT BALAI-ICE OF PROIXJCERS

TABLE 22 : HEAT BALANCE; FUEL TO GAS

Calorific value of fuel to ProducersDR.

BTC Per Hr.

(Table 14) SV60S,1S1

Calorific value of fuel to boiler

(Chapter 13)

Heat loss in boiler and steam m i n s

(Chapter 13)

Vaporisation of Steam (Chapter 13)

Sensible heat in producer gas to Kiln

(Chapter 12a)

Sensible heat in producer gas wasted

at producers (Chapter 12a)

Calorific value of fuel in ashes

344,884

261,671

78,170

407,475

11,997

(Chapter 12b)Evaporating moisture in fuel (Chap. 12c)

Calorific value of gas lost about pro

ducers (Table 17)

Calorific value of gas to kiln (fafflolf)

Radiation from Producer Shells

240,032

9,257

75,346

2^59,166

(Balance) 207,961

3,851,076 3,851,075

45.

m s m 25. HSS.S! B i L M C S HI PR03UCERS.

5gU per Hr.

Formation of GOp , 57.897123,976.364=230.219 n n 00 449.5157x1,874.571*842.649" n OH4, 12.5486x2,505 = 30.953

1.1057801

Heat in ashes at water line less sensible heat of steam from thiseonroe. 2,292Sensible heat in steam from boiler {Chapter 13) 7,335Sensible heat in producer gas{Chapter 12a) 419,472Evaporating Moisture in fuel,{Chapter 12o) . 9,257Radiation from Producer (Balance) 207,961Bisasoociation of Steam (Capter 13) 472,154

1,111,156 1,111,156'

44.C M P M 15 :

m m m sTwo of the profeiecrs diaoharge through 2*6"z5*9"

cylinders and water sealed valves into a 10" gas main. The

latter is cons true ted of standard wrought iron pipe, 50 ft,

long, and transmits the gas from the water sealed valves to

the discharge end of the kiln.

The gas from the third producer reaches the kiln

through SO feet of eight inch pipe.

The gas leaves the producers at H 5 0 ° F (Chap.12a),

and enters the kiln at 600°F. The average specific heat

of the gas between 75° and 600° is .269 (Plate 2). The

weight of gas is 1358.59 Lbs. per hour (Table 16).

Sensible heat in gas leaving producers

(Chapter 12a) 407,475 BTtTperHr.

Sensible hoat in gas reaching

kiln = 1358.59(600-75).269 8 191.867 " « «

Heat Lost in Gas Mains = 215,608 » » »

4 5 ,

CHAPTER 16 : K I L H

Tho rotary kiln is 125 feet long by 7 feet diameter.

The first four feet at the feed end is occupied by spiral

flights for maintaining a high ore level in the kiln. The

next 96.feet is lined with six inches of siloed insulat

ing brick and six inches of fire brick. The diameter of

the kiln, inside the lining is approximately five feet. The

next 0&.feet, beyond the end of the lining, is occupied

by a spiral passageway for preheating the air used in

eo#baation; The remaining 21^ feet of the kiln is left

uglined to facilitate radiation. This section is ribbed

with ten 4 nx6n angles to reduce wear on the shell and

aid in absorbing heat from the calcines. Water sprays

play upon the exterior of this section to hasten the

cooling of the calcine#.

The air required for combustion is provided by an

electrically operated fan which revolves with the kiln.

The fan draws the air through the air preheater and dis

charges into a six inch air-main which extends along the

exterior of the kiln. The air-main, in turn, delivers

the preheated air through tubes extending through the

shell to burners situated along the axis of the kiln at

points 32, 42, 53, 64,,77£ and 88£ feet from the dis -

charge end of the kiln. See Plate 1 for further de

4 6 .

tails of conetmotion.

The slope of the kiln 1q s/8 inch per foot of

length. The speed of rotation is 2/3 R.P.M. or 90

seeonds per revolution. The kiln is stopped frequently

for short intervals, usually to permit the temperature

to increase. The average running time is 85$, so the

effective time per revolution is increased to 90 r .85

2 106 seconds.

The capacity of the kiln is 80 dry metric tons

per 24 hours, or 7349 pounds per hour. The ozygen ex

pelled from the manganese minerals during reduction

averages 57 lbs. per hour. (See Table 39); so the

weight of calcine discharged per hour is 7292 pounds.

The ore as received from the mine contains 5$.

moisture. Hoist ore » 7349 r .95 = 7735.79 Lbs. per

hour. Moisture in ore = 7735.79 - 7349 = 386.79 Lbs.

per hour.

QMPgER 17:

COOItJBG- zom OF KIMThe producer gas enters the kiln through a

labyrinth gas seal at the tie charge end of the kiln,

at a temperature of 600°P- The sensible heat in the gas

as it enters the kiln is 191,867 BTU per hour.(Chap. 15)

The producer gas travels through the cooling zone in the

opposite direction from the movement of the calcine, ab

sorbing a small amount of heat from the relatively hot

ore and loosing heat to the cool shell. The gas finally

leaves the cooling zone at a temperature of 390°F.

(Table 31) Sensible heat in gas entering kiln (Chap. 15)

S 191,867 BTU per hour. Staslhte heat to gas leaving zone ( Table 33)

- 112.071 «* n » .

79,796 ” ® n . Heat lost by gas in cooling zone.

The calcine entersthe cooling zone at a tempe

rature of 855°F mid leaves the kiln, through the water

seal, at a temperature of 450°.

Sensible heat in calcine entering cooling zones

= 7293(855-75).817 = 1,234,244 BTU Per Hr.

Sensible heat in calcine leaving Min

= 7298(450-75).199 z 544,166 » ” «

Heat lost ealoine IneotiLSng Zone * 690,078 n R *

47.

The air preheating device eonoists of an inner

shell 3£ feet long and $£ feet diameter, the space bet

ween the inner and outer shells being divided into

spiral passages by three inch angles wound as double

spirals about the inner shell, at six inch centers. Cool

air is suoked through a hole in the outer shell at one

end of the preheater, circulates through the spiral

passages and leaves the preheater through a six inch

extra-heavy pipe at the other end of the preheater. On

account of the position of one of the tire-and-roller

bearings of the kiln, it was necessary to carry the six

inoh air line through the interior of the kiln, for a

distance of six feet and finally take it through a

flange in the shell of the kiln on the other side of the bearing. Here the six inch pipe is connected to the

suction of a Ho.l Sturtovant Monogram, electrically-

operated ball-bearing blower, which is mounted on the out

side of the shell and receives its current from bus-bars

surrounding the kiln. The resistance of the air pre

heater and the piping has proven too great for the blower

and it has been found necessary to admit a certain amount

of cold air at the suction of the blower, in order to furnish sufficient air at the burners. The total air re

quired for combustion is estimated as 1443.53 lbs. per Hr.

(Cable 40). Che temperature at the blower suction is 305®\ .

Moisture accompanying air (Chapter 13)-=.0063x1443.53

. s 9.09 Pounds Per Hour

Heat absorbed by air in preheater s 1443.53(505-75). 239s 79,351 BCU Per Hour

* * ” moisture in air

= 9.09(305-75).450 S 941 ■ ” *

80,292 " " n

CABLE 24 : H5AC BALAHCE OF COOLUTC 20HS OF KlIM :

49.

Sensible heat in gas entering

B* T* v# fer Dr. — T r T -

Kiln (Chapter 15)

Seasible heat in calcine leaving

191,867

Kiln (Chapter 17)

Meat absorbed by air and moisture544,166

in preheater (Chapter 17)

Sensible heat in ealeine entering

80,292

zone (Cable 33)

Sensible heat in gas leaving

1,234,244

zone (Cable 33)

Balance (Chiefly absorbed by water212,071

sprays 689,582

1,426,111 1,426,111

50-

Water sprays play upon the top of the cooling zone

along its entire length, the water running down the sides

of the kiln and. entering a semicircular, trough at. the bottom. The kiln rotates in the water which collects in the trough. 33ms the shell is kept wet through the greater part of its revolution, little water escape# from the trough, most of it being evaporated. The heat

required to evaporate a pound of water at El Eavor is 1105 B.T.U. (Chapter 12c). Approximate.wei$it of cool

ing water evaporated = 689,582 f 1105 = 624 lbs. per

hour.

CHAPTER IB : KILE gSHPERAgDHBS

Thermocouples are situated opposite each burner,

protruding through the lining and six inch into the

interior of the kiln. The thermoouple leads extend along

the kiln to bus-bars encircling the center of the kiln.

Once every half hour, leads from a galvanometer are tem-

porarilly connected with each bus-bars, and the galvano

meter readings (registering temperature Fahrenheit) are ■ '

recorded in a log book. Following are the average tem

perature readings for the month of October, 1928.

TABLE 25 :

PLACE

Stack Gas Ho. 1 Burner Ho. 2 "Ho. 3 "Ho. 4 fHo. 6 "Calcine Discharge

PYROMETER READIHGS :

AYE. TEMP. FAHR.

a10291061975860450

The same agenM.es which effect the transmission of

heat to and from the briok lining apply equally to the

transfer of heat to and from the thermocouples, with the

exceptions (1) that the conductivity of heat through the

thermocouple tube and thermocouple easing is greater than

through the brick and insulation , and (2) that the

themooouple absorbes relatively more heat than the brick

because it protrudes into the interior of the kiln. These

two tendencies are opposite in effect and may be shorn te

be about eaual. So the thermocouples may be regarded as

registering the temperature of the inner surface of the

lining.

BIHEHSI0B3 OF LUTSB PORgXOl OF K I M

The calcine level is maintained approximately 10

inches below the axis of the kiln. Rise » 30n-10n = 20”

Rise f diameter = 2 0 • 60 = .3333. Cross section area of

ore (Kent P. 78) : .22886 z 5* = 5.72 Sq,. Ft. Area of &Bg .

passage above calcine = 2*5 ? T 5.721 = 13.914 Sq.. Ft.Let & * angle made by radii drawn from the axis of the

kiln to the contacts of calcine surface and lining *08. * fit * 1 0 4- 3 0 = .3 3 3 3 ; < # = 7 3 ° 3 2 ' ; * z M f 0 4 ' . M L . 0 6 7 ° Chora = 2 x 2 . 5 Bine 7 0 ° 3 2 » = 4 . 7 1 4 Feet.

Circumference = 5 7f = 15.708 Feet.

Calcine-Lining arc = 15.708x141.0674360= 6.155 Feet.

Gas-Lining * = 15.708^6.155 z 9.553 Feet.

Circumference through centers of brlckr 5.5 V z 17.279

* » " of insulation*6.5 ̂ = 20.420

Outside circumference of shell = 7.1 T - 22.305TABLE 26: TRAHSMISSIOH SURFACES PER FOOT OF LEHGTH

Surface Sq. Feet

53.

CHAP SEE 19 :

Gas - Calcine 4.71Calelne-Lining 6.15Gas-Lining 9.55Ave. Brick Area 17.28Ave. Insulation Area 20.42Shell 22.31

54.

ZOIES IU LIH5D PORT I OH OF KILH :

For purposos of caloulation, the lined portion of

the kiln is divided into senes in accord with structural

features of the kiln and the various metallurgical proc

esses taking place within the kiln.

TABES 27: ZDHE3 IH LIHEP PORglOH'OF KILN :

Zone ■ ......

CHAPTER 20: •

SoakingCombustion

3rd Flame Piv. 2nd "• rt 1st « »

Evaporation

Feed Zone

8n

'' m

end of Feeder

Outside Bust Chamber Inside "

*0.0M . O11.020.810.22.51.6

100^0

55.

Only two large burners and the small burner near

est to them, ( See Plate 1) are In use. Ho air is admitted

to the remaining small burners. In this section of the

kiln, between the air-preheater and the third burner

(counted from the feed end), the calcine simply soaks in

its .own heat, giving up a small amount of heat to the incoming producer gas and to the air surrounding the kiln.

The thermocouple temperature at the third burner is 1001°F,

at the fourth burner 975° and at the sixth burner (near the discharge end of the soaking zone) 860°. These may be

regarded as the temperatures of the inner surface of the

lining. (See Chapter 18).The temperatures of the brick surface, as determined

by the pyrometers, is plotted on Plate 10, and the average

temperature of the brick surface for the first and last

foot and the center 38 feet of the soaking zone was

determined by sealing from the chart . (Plate 10). The heat

less to the atmosphere for each of these divisions was then determined by the "reciprocal method". The reciprocal of eonduetivity x area f thickness in the ease of the brick

and insulation, and the reciprocal of external conduotlen

(Plate 4) x area in the case of the shell, were regarded as

"heat resis-

CHAPTER 2 1 : SOAKIHG ZONE.

tivity" and were added to determine the total heat

reaistanoe of the brick, insnlation and shell surface. The heat lost through the brick and insulation to the

atmosphere, was then determined by dividing the total

temperature difference (between brick surface and the

atmosphere) by the total resistivity, or the sum of the reciprocals. The temperature drop, through brick,

through insulation and at the shell surface, was then calculated by multiplying the heat lost, by each

reciprocal, and the temperature of each surface was

determined by successively subtracting each temperature

drop from the temperature of the brick surface. Since

the transmission constants depend upon the temperature

(see Plates 3 and 4), it was necessary to assume

temperatures for the first calculation and later carry through the whole calculation with temperatures determined in the first calculation. In these cal

culations the curvature of the lining was neglected

on account of the large diameter of the kiln. (See Kent p. 626 for mathematics of heat insulation).

56.

S A B L E 28t

LOSS SO ASMOSPHSHE IB HESS K)OS OF SOAICHIG ZOITS AT LISCH/iKSS M B .

Reciprocal method of calculation; Atmospheric Semp. 75° F.Temp. Brick Surface % 3240 F.

G m @ - Semp.tanta. Thick- Recip. Biff.

Are. { PI. Area ness Sac- of =Becip.

...600 ' 725

i# 188

57*

" InsuL 423 1.02 x 20.42 f 6 = 3.48 .2874 H ut. Shell 123 1.95 x 22.51 f = 43.50 .0230

•33S7

Rccip. Biff! Eac- #f Resip*

Heat lost to atmosphere « (824-75) f 3587 = 2,088 BUT per Hr.

: .A S .^ A S LOSS TO^ASHOSH^RE^IH OEHTRAL SS^FS.^OF SOAKgO^OHE.

toa®- Sliick-trot® Area noos

Ave. ( H (Ohh. m -Semu 3-4) 26) ches. tor. Factor xHeat. Temp.

Thru Brick 675 7.62 x 657 t 6 = 834 .00120 T O T §S8"" InsuL. 473 1.03 X 776 f 6 = 133 ;00752 690 818

Hoa Shell 128 2.02 x 848 f =1711 .00058 53 128.00935 555"Heat lost to atmosphere =(928-75}f.00930 = 91,720 BTU per Hr.

2ABLE 50

HEAT LOSS TO ATMOSPHERE IH LAST FOOT AT FEED HID OF SOAKIEGZ€EB. ■

6 m ® -Ave. tents Area

Thiek- Recip. Diff. ef Reoip.

„m ul ^Temp. pi3-4 (Tab. 27)Inches tor. Factor x H e a tSira Brick 946 W o x 17.28 f 6 "HtotiL. 510 1.03 X 20.42 f 6

From Shell 133 2.05 x 22.31

= 22.45 V0445 I l T = 3.51 .2849 753« 45.70 .0219 58

73513 939

886133

Heat lost to atmosphere =(1004-75)t .3513 = 2,644 BTH per Hr.

Hote: The calculated shell temperatures check cl

ly with thermometer readings.

T A B L E SO-A :

TOTAL HEAT LOSS FROII SHELL IB SOAKIBG ZQ1B

First Foot at Discharge End (Table 28) Central 38 Feet {Table 29)Last Foot at Feed End (Table 30)

2,08891,7202,644

T A B L E 31 :

TEMPERATURES, FIRST. FOOT AT DISCHARGE EHD OF ________________ SOAKIHG Z0IT3 : ■

Calcine 855Average

860Gas 890 400 410Brick Surface 822 824 827 (Plate 10)

Volume of Gas at 32° and 3100 Ft. Altitude

(Table 16) » 80,989 Cubic Feet Per Hour.

Cross section area of gas passage

(Chapter 19) s 13.914 Square Feet Gas velocity at 32° = 20,929r(13.914x3600)

= .4178 Ft. per Sec.

Gas velocity at 400°= .4178(400+460)f492

a .73 Feet per Sec.

Factor of transmission of heat from solid to gas

(Plate 5) = 1.15

59.BTU Per Hour

Transmission of heat, brick to gas, (Bibles 26-51)

* 9.55(824-400)1.15 = 4,657

Pins Loss to Atmosphere (Table 28) . s 2.088

Transmission & Radiation Calcine to brisk * 6,745

let ”T* s Average Calcine temperature

Transmission, calcine to brick (Table 26-Plate. 7)

= 6.15(T-824)25.51 '

Radiation n n • (Table 26-Plate 9)

= 4.71(T-824)10.2

Transmission pins Radiation « 203.7{ T-824) - S, 745| 5 s 857° 1

Pins transmission, calcine to gas (Table 26)

s 4.71(857-400)1.15 « 2,475Loss bjr Calcine 9,220

Drop in Calcine Temp.* 9220r(7292x.252) = 5°

transmission brick to gas 4,657

Transmission Calcine to gas 2,475

Total Gain by gas 7,152

Increase in gas Temperature = 7152r(1359x.27)r 20°.Initial, gas temp'. = 400-10* 390°; Final gas Temp. =400+10*410?

In the foregoing calculations the probable average

temperatures of gas and calcine were assumed, and the equa

tions wore solved for the temperatures. The new temperatures, together with the temperatures determined in the

heat "balance (I'able 35), were then employed In solving the

equations. SEhia proeess was repeated till oonsitent results

were eeeured. This method of approximation

- 4.71 (1018 - 964) 1.45 = 369

Lose i>y calcine 3SIVDrop in calcine temperature = 3567 7 (7292 x .269) = 2°

Initial calcine temperature = 1018 - 1 = 1017;

Final calcine temperature - 1018 + 1 - 1019

franaeieeion^riok to gas (determined above) 554" calcine to gae * n 369

Total gain by gaa 923

Tmmp. gain of gas * 923 7 (1359 x . 287) = 2° :

Initial temperature of gas a 964 - 1 = . 963;

Final gas temperature » 964 + 1 • t6§®

..3 .3:.

HKAT BALAHCE OF SOAKISG 20MK OF ZH,H.Bgg HSR EE.

Heat lose with hot calcine, 7292 ( 856 - 75) .217 1234244.I n gas leaving sene, 1359 ( 966-76) .273 520196.Loss from hot shell (Table 30A) 96452.Received with hot calcine . -

7292 603.9-76) .226 = 1548821Balance = Heat Received with hot gas 112071

l66 ( W 2 1660892

Initial gas Temp. = 75 4^12071 7(1359 x .262)}- 590.

HOTE: In the preceeding calculations, the calcine temperatures were taken from Tables 31 and 32; the final

gas temperature from Table 32, and the loss from the hot

shell from Table S0JL> The resultant initial gas temperature was when substituted in Table 31, and the equations

of Table 31 were re-aolved for calcine temperature. The

calculations were repeated till concordant results were

secured. Care was taken also that the temperature gra

dients of ealeine, gas and brick should be consistent

when plotted on Plate 10.

mi

CHAPgBR £2 : AIR KAIH.

Six inch pipe, 48 feet long,from blower to point mlA-

nay between the large burners, lined on outside with one inoh

of pulverised tuff.-$eapeimture of air 306° J? at blower and

250° at burners. Average temperature of air 277°. Average

temperature of surface of insulation 140°•

TABLE 34.

.4IR ,,0^ iiiC0MBp|^Q^|>̂

Air at blower 1443.63 (305-75).239 «per hour.

79351Moisture in air at blower

9.09 (305-75).450 = Air at burners 1443.53 (250-75).239 = Moisture in air at burners

9.09 (250-75)*445 =- Heat lost in air main (by difference)

M708

80292

mVolume of air at standard conditions

1443.63 x 12.39 = -

Volume of moisture at standard conditions

9.09 x 28.00 =

Cu. Ft. per Hr.

17885

- T B I #

Volume of moist air at 3100 ft. elevationand 32°F, 1.1265 x 18140 * 20,435 Cu.Ft.perHr.

* 5.68 " " " 3@0.

Cross-ssotion area of pipe interior = .2 Sq. Ft.Velocity of gas at 32° = 5.68 ? .2 = , 28.4 Ft. per See.

Heat loss per Sq. Ft. per degree temperature diff.

.70 f (.62 x 28.4) = 18.3 B. T. U. (Chapter 6)

64.Inner surffcee of pipe * 48 x 1.59 = 76 Sq,. Ft.

Average temperature of inner ourfaoe of pipe

= 277 - {l9,208 7 (?6 X 18.8)} * 263°.

The resistance of the metal of the pipe is so small that

it can he neglected.

Average area of insulation - (7.625 * 12) 48 = 96 Sq. Ft.

K (Conductivity factor for insulation)

* 19,208 t 96 (263 - 140) = 1.63 BTtJ per square foot, per

inch thiokneos, per degree temperature difference. This

is 60$ above the conductivity of S i l o e d and appears

reasonable.

Surface of the insulation - (8 .6 8 5 ^ 7 12) 48 = 108 Sq. Ft.

Transmission to atmosphere per Sq. Ft. = 19208 > 108 = 178.

BW per Hr. for a temperature difference #f 140 - 75 or66®. ; ■

TABLE 55.

RAPIATIOH COHSTAHTS.

HEAT LOST TO ATMOSPHERE FOR TEHPERATUHS PIFFERZHCE.

OF 65°.

Proceeding calculations 178 BTU per Hr. llellen Institute Constants,(corrected for revoL) (Plate 4) 140 " " "Langmuir Constants,(Corrected for revol.)(Elated) 50 " " "

As in all other oaloulations, the above determinations

conform more nearly to the Mellon Institute Constants than to those of Langmuir.

65,

CHAPQSR 33: • COMBUSglQn ZOHE

The oomhustion. zone extends from the center of the

.third flame to within 10.4 ft. of the spiral ore feeder.

In this zone, air (preheated to 350°F) is burned at the

axis of the kiln in the atmosphere of producer gas. Com-.

bastion takes place in three burners, spaced at 11 feet

intervals along the axis of kiln. Two of the burners

have nozzles 4&" in diameter and Fenturi tubes, six in

ches in diameter, at the constricted area. The third

burner has a inch nozzle and a 2£n Venturi tube.

Reduction of the manganese minerals takes place

mostly in the combustion zone. The manganese oxides,

MhOg, MhgOg ^ 0 and llUgO^, which occur in the ore, are

assumed to be reduced to HnO. The heats of formation

of all these minerals except HhgOg HgO are given in

Richards Metallurgical Calculations. That for Hn O2 3BgO may be caloulated by interpolation in the table

presented oh page 38 of the same book.

2 A n L 23 36•66

Heat Q£

Po inula t

Tyro .37 27.2 8,275 4,095 111,3843.41 250;6 8,000 3,600 902,160

K u o % r.fi m : i i ; %

1,653 2.075 LS73:775

BTTJ rqaulrea por Hoar

2 A. B L 23 ' .. Sf

Pyroluoito PnO, .502•436

87.2250.6

15.0109.5

*02ATj lioaatad rrodaot MnO

^Gen aot frooloolatea Prom £,txo cmalyale

lbs. C per 2!r.(?ablo 16)* 211.692jibs. 0 per Lb. gao

(Sable 38)■ ,07679.

67.

I&a. spent gas per hr.= Lts. C per Hr. in producer gas f

%bm C per lb. spent gas =211.6924.076792 = 2756.69

2 A B I E 39

3PEH2 GAS COminjED. POIJHIS PER HR.

C0o 741.55 56.24> 685.510 2 46*86 1.65 4 45.25 45.23GO 22.05 436.66 - 414.61 256.91c h4HH 1946.25

12.28 -T.1T -

835.82 ♦,

24.66

11:111110.41

53.774 27.63

66.51

TML 2756.69 1550.00 + 1406.69 390.24 685.31 93.96Oxygen accompanying Hitrogen -

= 1110.41X.3 535.12n from Hang, minerals 57.12

Calculated, Cable 37 68.70Discrepancy 11.58

T A B L E 40

COKSTITPBHTS 5HTERIHG SPENT GAS: P0TOID3 PER HOUR i

Air required per hour 1110.414333.12 =Producer gas per hearOxygen from manganese minerals

1443.531150.0057.12

2850.65Less steam produced 93*96

Pounds Dry Spent gas per HourMoisture in producer gasfTble. 16}

" " air of Comb.(Chap. 17)” produced in Comb.(Tble. 39)

8.599.09

93.96

2756.69

111.64Total moist gas leaving Comb. Zone 2868.33Moisture in Ore(Chapter 16) TOTAL gas leaving kiln

386.793265.12

1-4-1 AS..tl.i

CO 82.06 U 1946.23 .2406 .2833

5.50 468.07 661##

,305.871264 .46 .256

The speelfie heat val ues derived in Table 41 are

plotted on Plate 2.

Burners 1 and 2 have nossles 4 1/2" in diameter. .

Burner 3 has a nosale 1 1/2" In diameter.

The air pressure back of the nozslos is 3/4" of renter

Calorific value of gaa to kiln (Table 17} =

2,669.166 BTU por hour.

Sonsiblo heat in air of oombuation (Table 34) *

2,620,260_. Total heat added

at burnora.

V A-?8TAaiona M a n ia s .g g fHQr.UC1.3) AT VAHI003

Burner Diam. Cu. ft. per Min. Bo* Inch, 3" Pressure

3 ---- H i T * 667j c e n ^ K

t1

4.64.6

1390

* 0 f

47.8447.84

BTO per

113,1911263,6281255,528

100.00 2680,160

Burner ft5 4et38 yu».by ±c?yy#yu ♦ yjl JU5«>»'8 47,84 649.95 649,95 1372.21 1496 1 47.04

, S.H. due to Each at S.H, dueg of Qaaes 32Q p. _______

. jh * o d -

Bumor noor. Sron t .srrSis ti.70

2 30.29 69.71 .0781 ..1 100.00 .234

t

* #.234

#.334

$he values of apeolfio heat,- oaloulated In Table 44, are

ploted on Plate 2.

TABES 45. VOLUflE OF SPSHT OAS i

11)3. por Hr.(Tables C

_ K/p

CUBIC B3ET Std. Goad,

Per l b .Ft. Elev.

Cond,______ ac 1,1365GO#0 46.86 00 22.05 H 1946.23

8,16211.20912.81012.770

T 2;i43i— T57bm—

28.00"I4'.U275— W M m ... . .....

Producer Gao (Table 16) 13.675 15.405

Cross Geotion aroa of gas (Chapter 19) “ 13.9135 Sq., Ft.

VELOCITY OF GAS AT S2° M B 5100 IEET ALTITUDE::

T A B L E 4 6 :

Lbs. Gas: Per Hour.!Table 43

&gLn. OIZaxiQ 13U8.6Proa- ±18.68noer# Lbs.

tal# »*»V

per seeona =74(13.2135 33600)=

rsrrrThira Burner 1299.90 123.91 20025 1,695 21,720 .4335Seeona 0 649.95 1496.12 10012 20,467 30,479 .6083

Use d End Kiln2868133 * ™ “ 39*239 39*; 3255.12 51,437 51,437

Hote: Since a ouble feet of CO forms a Cu. Ft. of

COg sn4 CO is the predominating combustible in the producer

gas, the oxygen derived from the ore throughout the com

bustion a one v/ill have little effect upon the volume of

gas. Hence velocities calculated above apply throughout

each burner division.

T A B L E 4 7 .

HEAT GENERATED PER BOUHD OF QXYGEET DERIVED FROM 51AHGMESE

HBERALS. POUIJDS PER HR.

ProducerLbs. Corres-Gas Proper- ponding

Per Hour. tion Qm^m-Table 16 % Oxygen tible.

HO 436.66 9 5 . 7 . 9 5 7 1 . 6 7 5OKa 12.28, 2.7 .027 .007H * 7.37 1.6 .016 .002

PER POUUD. ---------wCombustible

(Table 11) 4,574' 21,495 82,884

456.51 100.0 1̂ )00 1.684 7,68(5

1

71.

M B 49.

EFFECT OF REDUCTION OF MHflAITgS3S KOTERAIiS OH HEAg, M B 01

YfflIGHT OF CIS AFP CALCIHS.

f* of BTU per 3 gas Hr. for

Burned Reduct.(Tab.43)(Taft. 86)

Lts. 0let Het Heatper Hr Comb. Generated IBS. Ttob. of Oxy. BTtJ per Hr FEE HR.

89) (Tab.47) (gable 48) ISSSUIWTS^

Start : • ....3d. Same fSna '3a. w 4.32 14475 3Start2d. FlameEnd2d. " 47.84 160386 27Start1st. FlameEnd’1st " 47.84 160286 27End Co#.Zone

90454 1359 7292

22740 22740 1424

1048868 1424 7295

204660 204660 2146

1048868 2146 7322

204660 204660 2868

2868 7349

1 0 0 . O o ^ 3 5 d 4 7 5 T 4 8 2 0 6 0 2 6 2 0 2 5 0

CHAPTER 24:

THIRD BURHER HIVISIQS OF OCMBU3TIOI 201E; 14 FT. L(MG.

T A B L E 5 0 .

LOSS m O H SHELL IH BDRHER DI7ISI0H OF COHBUSTIOH 20HE.

Temperature Inner brick surface 1020° (Tab. 51).

72.

Constants Thick- Are* Elates Area ness

Reoip. Temp.Diff. of Reoip. and.

s f - m -InsuL 518 1.03 x 285.9 f 6 = 49.1 .02037 767 W LShell 134 2.07 x 312.3 647 .00155 . #$ 134

Heat transmitted (1020-75) 4 .02506 = 37,709.

Heat in gas reaching 3- flame (Tab.33) .330,196 BTO pr.Hh

Heat produced at 3& flame (Table 49) 90,454 » " "

Weight of gas at 3& flame (Table 49) 1424 Lbs. per Hr.

S. H. 75° to 1146° = .276 (Plate 2)

Temperature of gas at 3& flame .

= 420,650 4 (1424 X .276) + 75 = 1146°.

T A B L E 5 1 !*m m m T v m ow li r a a m Division 'o f c o h b u s t i o h z o n e .

DISCHARGE EHD__________ AVE. FEED EUD

GAS 1146 (Calculated above) 1132 1117CALCHE 1019 (Table 32 1024 1028BRICK SORFACE 1015 1020 1024 (AoVlylOSO®)

I

V*.

Gas velocity (Table 46) » 4355 (1132 f 460)

i 492 = 1.41; Trans, factor (Plate 5) = 1.58

loss to atmosphere (Table 50) * (57,VO9. , - ■

less Trans. Gas to brict =

133.7 (1132 - 1020) 1.58 23,660

Trans, and radiation, calcine to brick 14,049

Temp, brick surface = 1024 - {14,049 ?

((86*1 z 26.63) + (65.9 z 15))}= 1020

Plus heat fer reducing manganese minerals

(Table 49) 14,475

28 52£. . . ^ 9wless Trans, gas to calcine *65.9(1152-1024)1^- 11,245 Balan ce = heat lost by calcine 17,279

Temp, drop in ealcine=17279t(7293 z .267)= 9° -

Trans, gas to brick 23,660

Plus Trass* gas to calcine 11,245

less heat generated by combustion of 0 from

manganese minerals (Table 49 ) 22,740

Sensible heat lost by gas 12,165

Ave* Temp, of gas = 1146 - } 12165 £

(1424 z .293 z 2)} = 1132°

Hote. The average temperatures were first approximated

and then repeatedly corrected in the above calculations until

concordant results were secured.

S A B L E 5 3.: . ' .” , . ■ .

HEAT BilLAHCE. SHIED BPEKBR DIVISI05, COMBUS-

TIOH ZQHE.

74*

‘ ' ■ - - f e ..Sensible heat in gas reaching 3rd

n a m e (Table 33) 330,196Heat produced in Division

(Table 42) 113,194Seneible heat in calcine discharged to soalcing zone (Table 33)Loss to atmosphere (Table 50)Reducing manganese minerals

(Table 49)Heat in gas leaving zone

420,650 - 12,165 Heat in calcine received

1548,821 + 17,279 1,566,100

Cr*

1,548,82137,709

14,475

408,485

2,009,490 2,009,490

Final tempera tore of calcine = 1,566,100 f (7295 x .225)

+ 7 5 = 10280 (Checks Table 51)

Final temperature of gas = 408,485 + (1424 x .275) f 75

= 11170 (checks Table 51)

CHAPTER 25.

75.

SKCOBD BURUKR DIYISIOB OP COIfflUSflO*_____________ 11 LOBG.____________

Heat in gas leaving third flame

division (Table 68) ,408,486

Heat of oombuBtlon second flame

(Table 49) 1,048,868

Total heat in second flame 1,45^,SW

Temp, of flame 1,457,353 a (8146 x.£98) +

75 2354

T A B L B 5 5 .

TBHPBBATURB (F) SBCOJTO BURHBR DIYISIOB OF C0HBU3TI0B ZOHB;.(From succeeding Calculations)

Discharge End. Average Feed End.Gas 8364 2165 1975Calcine 1028 968 876Brick Surf. 1066

Ga# velocity = .6083 (2165 > 460) f 492 * 3.24 : Trans. Fact.

(Plate 5) s' 2.71.

3 TO Per HR.Trans. Gas to Brick * 105.05 (2165-1065)2,71 313,164

Less loss to atmosphere (Table 54) 31,389

Trans, and Radiation, Brick to Calcine 281,765

Temp, of Brick Surf.=952 f (281765 f((67.65 x 26.06)

+ (51.81x14.2) > * 1065

Trans. Gas to Calcine - 51.81 (2165 - 952) 2.71 170,311552, WLess Heat required for reduction (Table 49) 160.286

Balance = Heat gained by Calcine 291,790

T

W e

Ave. Temp, of Calcine = 1028- {z91,790f(7309z.263x2)>

= 952

Trans, gas to brick • 313,154

Plus Trans, gas to Calcine 170.311

483,465

less heat generated by Combustion of 0 from

Hn Minerals (Table 49)

Balance * Sensible heat lost by gas

Ave. Temp, of Gas = 2354-{278,805f(2146z

.343*2)} = 2165

204.660

278,805

LOSS TO SEC0H3) BUEHER DIVISIOB OF COKBOSTIOH - ZOHE '

Avsxw Cons- Area RecifeJOf Temp. .Bri k factor Factor Biff.Insnl, 538 lIo4 * 225f6 = .39 02563 805 941Shell 136 2.09 * 246 * 514 00195 ^61 136

Heat lostr(1065-75)f03154« 31,389 BTC Per Hr.

Hote:. The calculated average temperature of the brick

surface (1065°, Table 53) is low when compared with the

thermocouple temperature (1138°, Table 25). Had a

larger proportion of the manganese minerals been consider

ed as reduced in this dividon, the calculated temperat

ure of the brick surface would have more nearly checked

with the thermocouple temperature. Also lower lining-

0

77.

calcine transmission factors would have had the same

e ffec t #

T A B L E 55 / :

HEAT 3ALA.HC E OF SECOBD BUBHER m VI SI OH OF COMBUSTION ZQHE

Sensible Heat in Gas reaching 2ndElaine (Table 52) 408,485

Produced and in air of Combustion(Table 42) 1,253,528

Sensible heat in calcine discharged (Table 52)

Loss to a tmosphere (Table 54)Reduction of Manganese Minerals

(Table 49)Sensible Heat in gas leaving divi

sion, 2457358-278805 Sens. Heat in calcine received,

1,566,100-291,790f 1.274.310

1*566,10031,389

160,286

2,936,323 2,936,323

Final Temp, of Calcine * 1,274,310t (7322x .218}+75

= 874 (Checks closely v/ith Table 55)

Final Temp, of gas r 1,178,548t (2146x.289)4-75 = 1975

(Checks with Table 53).

CHAPTER 26:FIRST BCHHER PIVISXOIf OP 'Demperature o f oro JJm e g

sraoH ZOHE, ao.e^Fi. ioBg0

SHTBr. Hr.

l b division

Sens. Heat in gas entering 1st Flame(ffiHe 55)

Plus Heat of Comlmstion (Table 49)

1,178,548.

Temp, of flame 2,227,416~(2868%.308)+75* 2597

" ° Calcine at beginning of Div.

(Table 53) 876

Heat in Calcine at beginning of Div.

(Table 55) 1,274,510

less Heat in calcine at feed end of

Div. = 7349(206-75).189 181.954» • ' >

Heat gained by ore in division 1,092,556

Plus heat consumed in reducing manganese

minerals (Table 49) 160,286

Plus loss from hot shell (Table 561 39.733

Total heat lost by gals in Division 1,292,375

Heat in H a m s 2,227,416

Plus Comb, of 0 from i&ng. mtoauls g

less Heat lost 1.292.375

Heat remaining in gas at end of Mv. 1,139,701

Temp, of gas at end of Div.=1,139,701f(2868x.277)+f5

= 1510

79.AVER* -gmP. OP GAS.

Avo. 2eop. o f b rlok Btirfaoo * B.

Lonath o f B lv lo io a « B. .

V o lo o ity o f (p x = .7G 32(2053H 00)^ 9n = 3 .99 ;7^ o .3? tL ct.-3 .18{:;i.4 )

870

7rano. qm to c a lc in e d .7 1 B (2063-541)3 .18 »23.G46B

(% . a)

" B ed ,, b rlo l: to O alO .*4.T O (B -Q Sl)6 .4 ^ -1 6 S3002>30.2

nV

80.m L E 56: LOSS TO AOSIOS] PIT. OF COMB.

Ave. Temp, of trick surfacelpreoeeding Calculations) % 0 ° __Atmospheric Temperature 7 5 ° _____________

A w . fl tor Ofrnc

Brick 714 7.19 X 359 r 6 = 4 3 0Insul. 394 1.02 x 425 f 6 = 72AShell 120 1.92 x 464 1 e 890

.00232

.01*00• »

9254845

680

760668120

Heat loot to atmosphoj

TABIB 57: HEAT BALANCE OF H R 3 T B0H1S5 BIV.OP COMB. ZOIE

. ‘ ! ' ■ BTU B r H h : BTXJ per Hr.

Heat in gas reaching 1st flame 1 ' ' ‘ (Table 55) 1,178,548Broa-oced and in air of Comb.

(Table 42) 1,253,528Heat in Calc, discharged

1 (Table 55) •loss to atmosphere(Table 56)Beduct. of Hang; Minerals (TSKL49)Sens. Heat in gas leaving Biv.

(Chap. 26)" " n ore entering Biv.

’ (Chapter 26) 181,954

1,274,310 39;735

160,286

1,139,701

2,614,030 2,614,030

n

81.

CHAPTER 37: EVAPORATION ZONE. XtEHGTH 10.2 FT.

g A B 1 E 5 8 .

BOSS TO ATMOSPHERE IN EVAPORATION ZCBB.

Temperature of inner brick surface (Table 59) = 562°;

Atmosphere 75®.

Am.Temp. Constant Area BalckFinal Column.

hrlok B # Insnl,. 208m # n . t7

Plates Tab.

&rr1.001.51

TXX

208# 8

f 6

Fac~. tor.

*“181 = 34.7» 344

Recip. Temp.Biff.of Recip.

H w t o r z Heat.$5------ 352"llflStiR-

02880 22200990 9903723"257

31997

Heat lost to atmosphere = (362-75) * .03723 •

Moisture in ore (Chapter 16) = 387 pounds per Hr.

Heat required to vaporize moisture at 206® to steam

at 206® (Chapter 120) = 974 BTU per Lb.

Moisture set free fust above boiling point (assumed

to be r/ater of crystalization) = .6 x 7736 = 46 lbs. per Hr.

In the absence of data on the heat required for breaking up

water of erystalization, it is assumed to be one half that

required for vaporization, or 487 BTU. per lb.

Heat required for breaking up water of crystaliza

tion = 46 X 487 = 22,402 BTU per Hr.

'V )

82.

T A B L E 6 9

TEMPERATURES IN EVAPORATION 2QBB (PROM SUCCEEDING CALCULA-

n m ) .

Dla charging end(Chapter 26)_____ Average Feed End._______________

Sai IBIS 1230 915Ore 206 206 m%Inner hriekSurface 868

Moisture evaporated in gone (following calculations)

526 lbs. per Hr.Total moisture in ore (Chap. 16) 387 lbs. per Hr.

Gas velocity at 32° with all water evaporated,(Table 46) 1.0268 Pt. per See.

Gas velocity at 32° with no

water evaporated (Table 46) .7832. M M

Increase in velocity in zone = .2436 x 326 7 387 =.5062.

Average velocity in zone (32°)= .7836 4 (.2052 7 2)=

.8862 Ft. per Sec. .

Average velocity at 1230°* .8862 (1230+460) f 492=

5.04 Ft. per see.Corresponding to a transmission factor of 2.6

(Plate 5)

BTU per VtHeat transferred gas to bricks 97.41

(1330-363)3.6 319,835

less heat lost to atmosphere.(Table 58) 7,709

Equals: heat transferred & radiated,briok to ore 318,136

Temperature of brick surface; 206 + 213.126

f {(62.73 x 20.3) * ( 48.042 x 1.9)} = 362°

Plus heat transferred gas to ore . = 48.042

( 1230 - 206 )2.6 127,907• u...1.. ..r:.,r..Equals heat transmitted to ore 340,033

less heat required for breaking up water of .

orystalization • 22,402

Equals, heat employed in vaporizing moisture 317,631

Moisture evaporated = 317,6314974 « 326 lbs.

per hovr* ; . . ... ' ■■.. ■ ■ ■ -

Heat transferred gas to brick (proceeding cal

culations) 219,835

Plus heat transferred gas to ore (Proceeding

calculations 127,907

Equals total heat transferred from gas 347,742

less sensible heat in vapor between 75° and

206 = 326 x 131 X .442 18,876

Equal s, heat lost by gas in the sons 328,866

Heat in gas at end of zonesi,1*9,701-328,866 = 810,835

Temperature of gas at end of zone

= {810,835 4 (2868 4 326).39}4 75 = 950°

83.

')

84.g A B 1 S 6 0 .

"BEL’S BAMHCE OF EVA20RA.TI0E ZOHE.

Sons, heat in gas reeeivea (fable 57) 1,139,701

Sens, heat in ore passed on to combustion zone (fable 571 ' 181,954

loss to atmosphere (fable 58) 7,7#Breaking up water of crystaliza-

tion 28,403Evaporating moisture 317,631Biff, between Sens, heat of steam

and moisture = 3 2 6 x 131 (1 - .442) 23,830Sensible heat in dry ore received 181,954

* * ” moisture in ore,received 326 x 131 42,706

Sensible heat in gas passed on to feed zone 810,835

1,564,361 1,364,361

Moisture which must be evaporated in feed zone

= 387 - 326 = 61 lbs. per hour,

fhis is relatively so small that probably it can

be evaporated before the ore reaches the boiling point.

]

CHAPTER 28:'

PORTIOB OF mZV ZOm OUTSIXE HJS5 CHAMBER; 2& Pg. LOH&

The fee a zone is four feet long and is eqtdppea with double spiral vanes, with two foot pitch, and with

a three foot opening at the feed end and am eighteen

inch opening at the discharge. Average, speed of ro

tation 106 seconds per revolution. ,

Revolutions of kiln per hour z 3600fl06 = 34

Dry weight of ore = '7349 lbs. per hour;. Dens

ity 78 lbs. per Cu. Ft. 7349t78* 94.3 Cu. Ft. per hr#

, Charge taken by each spiral per revolution. -V '

S 94iSr(34x2}= 1.38 Cu. Ft.

"Area"(Kent p. 77) = 1.38f7f = .0381.

Which corresponds to a R i s e ? Diam. of .078.

Rise : .07827 = .546 Ft. = 6.55 Inches

Which means that the average depth of ore in

the spirals is 6.55 inches.

Calculations of transmission of heat from hot

shell to ore, similar to those of Chapter 6, were made

for this depth of ore. The results were plotted on

Plate 7 and will serve as a basis for calculations of

heat in the feed zone*

With a rise of 6.55 inches, the chord scales 3.75 feet and the arc 4 feet. .

85.

\

86.In the first 2& feet at discharge end of feed zone $

Area of shell in contact with ore = 4x2.5= 10.Sg.Ft.

Area of vanes in contact with ore, inside

spirals s 5x1^8=6.90 « •

Area of vanes in contact with ore ad

jacent to lined portion (Chap 39) = 5.72" »

Total steel surface in contact v/ith Ore s 22.62 n n

Surface of vanes, including central open

ing in spirals r ‘ 192.4 # •1 • • • ; • , .

Vane surface adjacent to lined portion

Openings Diameter Diameter Squared

2.253.24

Sq.Ft. X 2 Y = 64*9

1.51.82.2

Area of vanes including openings ....

Double area of openings 64.9

Area of vanes in contact with ore ________

Area 0 n " " " gas 124.5

Plus area of dell in contact with

gas(7%4)2.5 45.0

Total steel-gas surface 169.5

length of shell exposed to atmosphere is taken as

3.5 Feet, to compensate for flow of heat along shell be-

87.

3.5 7/7.1 * 78 Sti* fwt.

Gas - Ore ourfaoo s 3.75 x 2.5 = 9.4 Sa. Ft.

Average area of central opening *.952 #-2.8 Sg.. Ft.# #

8 x 2 - 4.0 " "

V o l m e of BOlat gas at 32° tm4 3100 Ft. Bier.

(Table 46) = 51,437 Ou. Ft. pop Hr. * 14.3 Cu. Ft. pop 3oo.

" 807° » 2.1 (807 4 460) i 492 s 5.39 Ft.

Ion factor (So. 4) = .70 f (.62 x 5.59)

g A B L 8 6 1 .

a?EHE>KR\!PUEn;S HI FIRST g f Eg. AT DISGORGE EUS OF B E D 20HB.

Dlschnrgo Ena(fable 59) Average Food,Ena.

Or©!Shell

174 1414S8

Heat transmitted gas to steel

169.5 (807 - 438) 4.04

Less loss to atmosphere,

78 (438 - 75) 3.5

Equals transmission and radiation, steel

to calcine

Ave. Temp, of shell * 174 + 153,585

r f( 22.62 x 24.68)} f (9.4 z 2.2)} - 438

Plus transmission, gas to ore *

,9.4 (807 - 174) 4^04

Equals gain by ora, moisture and evaporati

Loss heat required to evaporate remaining

moisture (587 x 974) - 317,631 = 59,307

And heat required to heat moisture

from 141 to 206, = 387 (206 - 141 = 25,155

88.BfU PER HR.

252,684

99,099

153,585

24,039

84,462

Initial heat in ore at feed end of divi

sion = 181,954 - 93,162 = 88,792

Ore Temp, at feed end of division =

88,792 t (7349 x .184) f 75 = 141°

Heat transmitted, gas to steel (Proceeding

calculations) 252,684

Plus heat transmitted gas to ore (Proceeding

caloulations) 24,039

Equals total heat transmitted from gas 276,*23

V1

loao oensiblo boat b c t o c n 750 and 205°

of vapor evaporated,- 61 (206 - 75) .442 3,552

Enualo decroaoc of sensible heat in gas 275,191

Sensible heat in 33s leaving division

= 010,855 - 273,191 = 537,644

(3855 s .88 4 75° “ 664°

' S A B L E 6 2 .

HSAf BALA1ICE OF FIRST 2 l/2 Pf. Ag DISCmRGE EBP OF SEED ZQ1E.

Sens, heat in m o received (Sable 60) 810,855

on toto Evaporation Zone (Sable 60)

Sensible heat in dry Evaporation Zone (fable 60)

EvGpoi*ation of moisture not Evaporated $

61 x 131 (1 - .442)Sens* heat in colaturo received

with ore; 387 (141 - 75) -Sens, heat in dry ore received

1)

181,95499,099

59,307

heat in gu.g passed on ‘ - no)

88,792

h

= _ m 10038

133

123

*

«

e«

CHAPTER 29:

M S S li SEES Ag SEED EHS OF REED ZONE:

Area of shell in contact with ore 1.5z4 = 6 SQ,. FT.

n " vanes « *» « n 3x1.38= 4

Total ore - steel surface 10

Internal serf, of vanes, including central

opening = 3 r 3.52 = 116

less surface of esntral openings

a S ^ l i S 2

Internal surface of vanesn o ^ n of shell = 1.5? 7

tl

It

w

ft

n

#

it

ttless surface In contact with ore

Sotal internal gas-steel surface

External surface of shell

1.5?7.1 = 34 S%* Ft. 36 So. Ft.

External surface of End Plate

(3.52 - 1.5^>T = 32 Sq.. Ft. 32 " »

66 n n*br**-f*artba of this surface may be considered

as effective for transmission 50 SCI. FT.

Total effective gas - steel surface 173 " n

Gas-ore surf.* 1.5x3.75* 5.6 Sq. Ffc.

Ave. area of centralopening * 1.32^ - 5.3 " n

91.

Croao soe t l m area thru vane - 4 84. Ft.

9.3 n 0

Felooity of gas at 32° (Chapter 28) .

• 14.3 * * 9.3 - 1.54 Ft. per second.

Avoaugo temperature in thlo division *

(664 + 543) 7 8 = 603°

Velocity at 603° = 1 . 5 4 (603 + 460) A 492

loalon factor (Plato 5), 3.76,

2 A A , % . B , G 3 .BEUPERtOTRSS OF IASS lj IS. A5

cao ' J a & p - ^ 2 -Ore 141 105 WSteel 432

neat transferred, gas to ot vol, 173 (603-432)2.76

y m .

5.6 (603 - 108) 2.76 7.651

Equals heat lost by gas * I&at gained by oro & nolsturo 89,300

Heat actually gained by ore (Table 62) 88,.792

* " * " Uoioturo (Tab.62) 25.542 114.334

Disorepnncy 25,034

S m s . heat in gas at end of kH$i*537,644-114*334 423,210

Final gas Temp. » 423,310 f(3255z.278) + 75 * 543°

92.Hotc: Tho pyrometer readings of the stack gas

averaged 571° but these readings were taken a foot

inside the kiln, and hence were higher than the calculated

temperature.

transmission, steel to ore * Trans., gas to steel * 81,649

Avo, Steel temp. = 103 + 81,649 f {(10x24.1) f (5.6x28= 432°.

Hote: the calculations of heat transfer from gas

to ore, recorded on the proceeding pages, represent the

third complete set of calculations. In each of the

former sets the discrepancy at the end of the kiln was

so great that the transmission factors, plotted on Plate

5, were altered and the calculations repeated. O’he dis

crepancy in the last set of calculations is within the

probable error of reading the charts; so may be dis

regarded.

BEAT BAIAIICS OP LitSf lj Ff. AT FEED ESP OF PS5D ZQHE:

T A B L E 6 4 .

BTU PER HOUR.

Sensible heat in gas received (Table 62)Sensible heat in ore passed on (Table 62)Sensible heat in moisture passed on (Table 62) .Sensible heat in gas discharged to stank

537,644

537,644 537,644

95.CHAEfER 50; (SBESAIi HEA5? BteMGXS.

S A B L E 6 5 .

GEHERAL HEAS B A L M C E OF KX M .

B. T. U.

Seas. Heat in gas entering Kiln, (Sable 24) 191,867

Sensible Heat in calcine leaving kiln, (Sable 24)Heat absorbed by water sprays in cooling zone (Sable 24.) loss to atmosphere; Air Hain (Table 54)

i w a . - g s r 8 zone3rd. Burner Div.

(Table 50)2nd. Burner Div.

(Table 54)1st, Burner Div.

(Table 56)Evaporation Zone,(Table 58) feed Zone.(Table 62) 99,099Heat of Combustion (Table 17) 2,559,166.Reduo. of Hang. Minerals(Table 36)Breaking up water of Crystallnation (Table 60)Tsperizing moisture from & to 206°

= 387 x 974Biff, between sensible heat of water and steam