wasmund ingles flotation

8/10/2019 Wasmund Ingles FLOTATION

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Flotation technology for coarse and fine particle re

Eric Bain Wasmund

Global Managing Director

Eriez Flotation Division

Vancouver, Canada


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Presentation

1. Identifying a universal challenge for froth flo

2. The case for splitting up the problem into tw

3. How to treat coarse particles.

4. How to treat fine particles.

5. Conclusions.


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0

20

40

60

80

100

1 10 100 1000

Particle Diameter (Microns)

Recovery(%)

Copper

Lead-Zinc

Coal

Phosphate

The result of conventional flotation

Most concentrators have flotation recoveries of 80-90


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Flotation: An interactive systemCHEMISTRY Mineral surfac

CollectorsModifying age

pH

ORE

Particl

Libera

Pulp dMACHINE

HydrodynamicsMixing

Bubble size

Air rate

Wash-water

Launders

The Flotation

Triangle


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Bubble + Particle Bubble-particle aggregate Recove

Simplified flotation process

Kinetics are strongly dependent on size for each step!Challenge: Highly energetic fluid environment is optimacollecting fine particles, and non-optimal for recovering particles

Conventional machines run under conditions that are a t

attachment transport to launder

detachment


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Conventional flotation

High amount of mechanical energy

required ~ kW/m3 Objectives:

1. Keep the pulp suspended (preventsanding).

2. Disperse the air.

3. Create the mixing for particle-bubbleinteractions.

4. Create low turbulence for frothrecovery

Pulp phase behaves like a CSTR (short

circuiting expected).


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Eriez approach Borrowed from the fertilizer beneficiation industry (ie phosp

potash).

Do a size separation first, and then process each stream witappropriate technology.

Coarse particles treated using Eriez HydroFloat fluidized becell.

Fine particles treated by Eriez columns.


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Effects of particle size can be

reduced by utilizing a split-

feed flotation approach.

Efficiency improves,

especially for coarse

material, with tighter size

ranges.

Other benefits include a

more efficient use of

reagents.

Feed Primary

Classifier

Conditioner

Conditioner

Reagents

Finas

Reagents

Lets focus on coarse particle flotation and applications


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Flotation in a fluidized bedFeed

Freeboard(low turbulence)

Fluidized bed

Fluidization manifold

(not shown)

Tails


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Particulate fluidization

Fluid properties will be modified because of the interactionof other particles in the bed, the hindered settlingregime

Particle is fluidized when the downward force of gravity (Fg) is

balanced by the upward drag force from fluidization water (Fd)

Heavy particles (large size and/or large SG) that have more

mass relative to their drag will sink relative to the bed

Lighter particles (small size and/or small SG) will riserelative to the bed

Bubble particle aggregates will have an effective SG that

allows them to be lifted out of the bed

Fluidiza


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Design features of the HydroFloat

Flow through the unit is counter-current which maxcontact time.

Fluidized bed behaves like a plug-flow reactor, shortof particles and bubbles is reduced.

Fluidized bed allows high and uniform particle concand optimized interaction between bubbles and pa

Hindered settling regime (ie modified viscosity, denmore residence time.

Less turbulence than a stirred tank, detachment mi


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Design considerations of the HydroFloat

Fine or low density feed particles can be pushed to the pwhich can lower grade. Experience suggests a feed size with top size class/fine size class ~ 5 : 1 depending on m

Fluidization water will lower the percent solids of the prScreens or cyclones required to de-water

Mechanical agitation (power) not required.


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Typical HydroFloat balance for a 4 m dia uFeed: 5000 tonne solids/day

% solids = 60-75 w/w%

p80 = 750 mm

Fluidization water: 5000 m3

/dayAir: 1000 m3/day

Tail: 4500 tonne solids/day

% solids =70-80 w/w%

p80 = 800 mm

Concentrate: 500 tonne solid

% solids = 5-20 w/w%

p80 = 650 mm

Water reports to product, underflow has high perce

De-watering

cone


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Evaluation of the HydroFloat on a coarse Spsystem*

Measured recovery by size class with HydroFloat lab-unbenchmarked against Denver test-cell

* Optimization of operating parameters for coarse Sphalerite flotation in the HydroFloat fseparator, Minerals Eng., 50-51, pp 99-105 (2013). See also Minerals Eng. 60, pp 51-59 (2


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HydroFloat commercialization

Successful applications have been developed for phosphate

New applications are being developed for copper and gold.

Opportunity exists to introduce into existing mineral processheet.


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Simplified conventional concentrator

Possibility to reduce circulating load.

Possibility to increase particle size from SAG (increase throughpu

Possibility to avoid losses of high SG ductile ore like free gold and

Ball Mill

SAG

Mill

HydroFloat

To fin

Feed


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Test-work done at larger Copper concenSouth America

Sample taken from mill cyclone underflow to evaluate perform

inch diameter lab unit.

To Rougher

Flotation


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Test set-up

Feed = 0.15 t/hr. fluidization water = 1.5 m3/hr.


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Results

HydroFloat recoveries of 70-90% on coarse feed

(ie cyclone underflow).


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Potential flow-sheet improvement

HydroFloat could treat part (or all?) of the ball mill cy

underflow.

Ball Mill

SAG

Mill

>1000 mm

HydroFloat

Feed


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Effects of particle size can be

reduced by utilizing a split-

feed flotation approach.

Efficiency improves,

especially for coarse

material, with tighter size

ranges.

Other benefits include a

more efficient use of

reagents.

Feed Primary

Classifier

Conditioner

Conditioner

Reagents

Reagents

Now lets focus on fine particle flotation and applications


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Fine particle flotation

Fine particle flotation normally benefits from

1. Smaller bubbles.

2. More energetic environment for collisions.

3. Wash water to reject fine gangue.

4. Pre-aeration Eriez has multiple technologies to achieve these

objectives.

ff f b bbl


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Rate constant k inversely proportional to bubblesize to third power!

Effect of bubble size

Ub

Db

2

2

3

b

p

cD

DP

PD

Jk

b

g

2

3

dac

PPPP 1

Small particles have less efficient collisions with large b

When floating fine particles, high energy collisions and

are beneficial.

Eff f h


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No Wash Water

Wash Water Addition

Effect of wash water

0

2

4

6

8

10

12

14

16

18

20

0 1 2 3

Number of Dilution Washe

FrothMineralMatter(%)

F

W

Dilutions

ofNumber

M ki ll b bbl th C T b


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Eriez CavTube

Contraction/ expansion nozzle Shatters sparged air into ~100

micron bubbles

As pressure drops, ~ 1 micron

bubbles are nucleated from theliquid phase onto ore particles

No internal parts in the flow

path. Reduced wear from flow

impingement.

Making smaller bubbles- the CavTube

Inlet

High P Low P

Plexiglass mo


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CavTube bubble size distribution with air a

*Mining Sci. & Tech, 20 (2010), pp1-19

0

20

40

60

80

100

0.01 0.1 1 10 100 1000

Bubble Diameter (micrometer)

C

m

u

a

v

C

v

(

0

2

4

6

8

10

P

a

o

D

t

y

(

Cumulative curve Frother ACumulative curve Frother BPopulation density Frother APopulation density Frother B

Note: for a typical application with Jg = 0.75 cm/sec, the nucleated bubbles are

total air volume added to cell

CavTube sparged column


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CavTube sparged column

Standard column with recirculating loop to recycle slurry

ring of CavTubes

CavTube can also be used to pre-aerate feed ahe


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Static Mixer

Tailings

Feed

Wash W

Sump

Mixer

Pressure

Gage

Cavitation

Tube

Cavitation Feed

Pretreatment

Collector

CavTube can also be used to pre aerate feed, ahe

flotation cell - lab test*

* Cavitation pre-treatment of a flotation feedstock for enhanced coal recove

al Coal Pre 2011

CavTube used for pre aeration in lab te


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CavTube used for pre-aeration in lab te

Pre-aerating the feed with CavTubes increases the flotat

constant so less residence time is required

* Cavitation pre-treatment of a flotation feedstock for enhanced coal recovery

Coal Pre 2011.

0

20

40

60

80

100

1 2 3 4 5

ComponentRecovery(%)

Flotation Time (min)

With Cavitation

Without Cavitation

With CavTube pre-aeration

Without CavTube pre-aeration


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Conclusions

1. There is a huge opportunity to improve theperformance of concentrators throughout the

2. Existing flotation technology considers a singapproach. It cannot be optimized for size dis

typically produced by primary grinding circui3. Eriez approach is to focus on technologies th

optimization of recovery by size.


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Gracias

wasmund ingles flotation

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