industrial preparation of granulated charge
TRANSCRIPT
PLANT EXPERIENC E
I N D U S T R I A L P R E P A R A T I O N OF G R A N U L A T E D
R . A . B o l d y r e v , L . G . G e r o i m e n k o v a , Y u . A . Z o r i n , E . M. M i n t s y u k , a n d V . I . P r i t u l a
CHARGE
UDC 666.1.022
Recently g r ea t attention is being paid to finding new effect ive methods of p repa r ing g lass cha rges . This is r e la ted , f i r s t of al l , with the intensif icat ion of g l a s smak ing p r o c e s s e s and necess i ty of ra i s ing the quality of g la s s . Bes ides , the use of nondusting g lass charges enables us to improve substant ial ly the con- ditions of working and to reduce substant ia l ly the pollution of surrounding environment .
Among the methods that e l iminate the disadvantages of usual loose charge , granulat ion and s in ter ing a re known, of which the f o r m e r has found the widest application.
P r e s s i n g (briquetting), rotat ion, and ext rus ion techniques a re the main methods of granulat ing loose m a t e r i a l s .
In the ext rus ion method the loose m a t e r i a l is t r a n s f o r m e d into the plas t ic s ta te by adding water . Then it is additionally mixed and loaded into a g ranu la to r , where it is compacted and finally comes out through drawholes under p r e s s u r e in the f o r m of granules of cyl indr ica l shape. The hardening of g ranu les , as in the rotat ion technique, is ensured by the fo rmat ion of var ious c r y s t a l hydrates f r o m the components p r e sen t in the m a t e r i a l i t se l f or , if such components a re absent , by b inders .
The advantages of this method a re the re la t ive s impl ic i ty of maintaining the condition of granule f o r m a - tion and poss ibi l i ty of obtaining the n e c e s s a r y f rac t ion without additional sor t ing . The following a re the dis- advantages of the method: compara t i ve ly complex equipment , substant ia l power consumption in the p r o c e s s , higher wearing of d ies , and mobile components of g ranula tors in working with m a t e r i a l s with ab ras ive p ro- pe r t i e s .
A setup was made at the Pol tav Glass Works for the ext rus ion granulat ion of glass charge . In May 1974 the col lect ive of medica l g lass l abora to ry of VNIImedpol imer jointly with the fac tory s t a r t ed developing the technological p roces s of making granulated charge by the extrusion method and m a s t e r i n g the technology of making neu t ra l a luminoboros i l ica te glass for medica l purposes under industr ia l conditions. Since June 1974 the exper imen ta l indust r ia l setup of extrusion p repara t ion of granulated charge has been supplying the charge uninterruptedly for one of the industr ia l furnaces of the Pol tav Factory . The composi t ion of g lass NS-1 , for which the technological conditions of p repa r Ing the granulated charge and making glass f r o m it have been es tab l i shed , is as follows: 73.0% SiO2, 4.0~c B203, 4.5% A1203, 1o0% MgO, 2.0% CaO, 7.0% K20, and 8.5~ Na20 by weight.
The charge composi t ion for g lass NS-1 pe r weighing cons is t s of 273.0 kg sand, 45.88 kg kaolin, 40.52 kg chalk, 16.12 kg dolomite , 12.48 kg potash, 31.8 kg boric acid, 5.92 kg soda n i t re , 10.44 kg sodium sulfate, and 54.44 kg soda.
The bas ic d i ag ram of the setup is given in Fig. 1.
A bin 1 is loaded with loose charge with 4% moi s tu re with the help of a t e l f e r - supp l i ed bucket which is filled d i rec t ly f r o m a mixer . A sc r ew feeder 2 located below bin 1 gives uni form feeding to a double ro l l e r m ixe r 6, in which the charge is mixed, mois tened , and wa rmed , while it is s imul taneously shifted towards the p r e s s opening. The charge and water in the m i x e r a re warmed by the heat of exhaust gases f r o m the d rye r . The exhaust gases pass through the outer shel l of the heat jacket 12 mounted around the mixe r body. The s a m e shel l contains a coil tube to heat up water that is supplied to the charge . The t e m p e r a t u r e of heat- ing is 90~176 The supply of water is control led with the help of a needle valve.
Pol tav Glass Works . Trans la ted f r o m Steklo i K e r a m i k a , No. 5, pp. 30 -31 , May, 1976o
IThismaterialisprot c t e d b y c o p y r i g h t r e g i s t e r e d i n t h . . . . . . f P I P u b l i s h i n g C o r p o r a t i o n 2 2 7 W e s t 1 7 t h S t r e e t , N e w Y o r k , N,Y. 10011. N o p a r t [ . . . . o f this publication may be reproduced stored in a retrieval system or transmitted in any form' or by any means electronic mechanical, photocopying, microfilming, recording or otherwise wi thout written permission o f the publisher. A copy o f this article is available from the publisher for $ 7. 50.
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Fig. 1
P
Fig. 2 Fig. i. Diagram of the setup for obtaining granulated charge. I)
Charge bin; 2) screw feeder; 3) water tank; 4) spraying device; 5) in-
termediate draw hole; 6) double paddle mixer; 7) feeding rollers; 8)
press; 9) final drawhole; i0) device for even distribution of wet gra-
nules on the conveyor belt of the dryer; 11) conveyor belt of the dryer; 12) heat jacket.
Fig. 2. Scheme of testing the strength of granules.
Before the inlet to press 8 a drawhole 5 is located with a hole diameter of i0 ram, with the help of which
the preliminary partial compaction of the plasticized mass of the charge is carried out. The final compaction is achieved in the press and also by cone-shaped drilling of holes in the final drawhole 9 of the press. At the
drawhole outlet the granulated charge is evenly distributed by special devices i0 along the width of the belt of
the conveyor of the dryer. The dried granules are loaded by bucket elevators and belt conveyors into receiv-
ing bins of furnace chargers.
The results of investigations revealed the following optimum conditions for obtaining granules taking into
account the possibilities of the available equipment:
Temperature of the charge in the mixer ............ 85~176
Moisture content of granules at the outlet
of the press drawhole ....................... 9-iI~
Temperature of granules at the outlet of the press drawhole ............................ 750-80~
Maximum temperature of the heat carrier ........... 700~176 Moisture content of granules after drying ........... 2-62
The output of the setup is limited by the dryer (length of the dryer 9 m) and at the time of mastering the
setup it was 1.7 tons/h (duration of drying 2.6 rain). Besides, the considerable wear of metal of the evaporat-
ing vane of the press and mixer paddles should be mentioned.
During the adjustment of the setup alternative drawholes ~4th hole diameters of i0 and 14 mm were
tried. The trials showed that in drying granules of 14-ram diameter the moisture is not uniformly removed from the thickness of material and bursting takes place and, consequently, the strength deteriorates. With
decrease in diameter of the drawhole the drying was more intense and bursting of nodules was not observed
with the exception of the occasional appearance of small longitudinal cracks. The granules coming out from the dryer continued to dry in air during their transportation to the bin of furnace chargers as well as in the bin.
The moisture content of granules taken from the pocket of the glassmaking furnace varied in the range of 1-3%.
The strength of wet nodules was low. However, in the course of drying it considerably increased. As there is no method to determine the strength of granules, a scheme of testing, as given in Fig. 2, was adopted
by us. In the experiments the load P, at which granules of l-cm length were broken, were determined.
In each batch 30 specimens were tested and the arithmetic mean of the breaking load was calculated from
the obtained results. It varied in the range of 205-265 N. The still-lowervalues were obtained, when the
drying temperatures were high, evidently causing the appearance of cracks and, consequently, a decrease in
strength. The maximum value of strength was 400 N while the minimum value was 160 N.
In the mixer and press at temperatures of the order of 85~176 that develop under the technological
conditions of the Poltav Factory sodium tetraborate (Na2B407" i0 H20) is mainly formed. In the course of
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drying it t r ans fo rms into tincalconite (Na2B407" 5 H20) and water is re leased, thus reducing the s trength of granules . In o rde r to avoid the re lease of water it is neces sa ry to ensure the direct formation of t incal- conite, for which the charge in the p res s has to be warmed up to 110~176
In spite of some disadvantages of the experimental industrial setup of the Poltav Factory, of which the imperfec t design of the d r y e r is the mos t significant one, the technological flow sheet of preparing" the g ra - nulated charge successful ly passed the experimental t r ia ls . As a resul t of the changeover to granulated charge , it was possible to avoid segregat ion during t ranspor ta t ion , to reduce the losses of charge and its con- stituents during movement f rom the mixers to furnace-feeding bins, to eliminate dusting in the shops and jamming of charge in feeding bins, in spite of their large capaci ty.
With the adoption of granulated charge the specific extract ion of molten glass in furnace No. 1 increased f rom 363 to 403.4 kg/(m2.day) and in furnace No. 2 f rom 384 to 496.5 kg/(m 2. day). The output rat io of accept- able wares increased to 0.9. The annual economic effect due to the introduction of granulated charge to the Poltav Factory is 44,600 rubles.
The positive results of adopting granulated charge for glassmaking provide an opportunity to set the task of modifying all glassmaking furnaces of this factory for feeding the charge prepared by the extrusion method as well as of introducing this method to other factories of the industry.
A U T O M A T E D C O N V E Y O R L I N E F O R A S S E M B L I N G
A N D S T I C K I N G M O S A I C C L A D D I N G M A D E F R O M
C A S T C E R A M I C T I L E S
V. P . S k v o r t s o v , P . A . B o b k o , N. B . K u r o l a p n i k , a n d V. G. B o r s h c h e v o i
UDC 666.3-413:621.867
Our plant is now using a conveyor line for the assembling and sticking on to paper of the cladding made f rom cas t ce ramic t i les . This line has been developed by the Technical Planning and Design Bureau of the Industrial Materials Tn~st of the Kiev City Executive Committee in conjunction with the Plant.
In 1971 the line came on s t r eam as a pilot installation.
The main purpose of this line was to eliminate the heavy manual operations involved in assembling the tiles into mosaic cladding and sticking them to the paper backing, thus increasing labor productivity and lighten- ing the work. At the present t ime the productivity of the line has reached 160-180 m 2 of cladding per shift (8 h). The line is manned by five men. Thus output pe r man-shi f t is 36 m 2 compared with only 11 m 2 for manual assembling.
The cladding is assembled f rom cast , glazed ceramic tiles measur ing 25 x 25 x 4 mm (State Standard 18623-73) . Figure 1 shows a schemat ic of the design. The width of the cladding is f rom 0.5 to 1.2 m and the length can be varied.
The layout of the line is shown in Fig. 1. The tiles are fed into the bucket of the elevating skip (1) which has a capacity of 0.5 m3; the tiles drop into the receiving bunker (2) and are then conveyed by the belt feed (3) to the fast conveyor (4). Above this conveyor there is a brush mechanism (5) which ar ranges the tiles in a single layer.
The tiles are fed from the fast conveyor on to the orienting grids (6) (three stages), turned with the glazed side uppermost, and arrive at the vibrating bench (7) which has side guiding walls. The tiles which miss the orientation drop into the container (8) from where they are returned to the receiving bunker.
Kiev Ceramic Plant. Transla ted f rom Steklo i Keramika, No. 5, pp. 31-32, May, 1976.
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I microfilming, recording or otherwise, wi thout written permission o f the publisher A copy o f this article is available from the publisher for $ Z50. _ _
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