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3-1-1982

Evaluation of Dissolved Air Flotation for theTreatment of Mineral SlimesAlan Jospeh Melnyk

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Recommended CitationMelnyk, Alan Jospeh, "Evaluation of Dissolved Air Flotation for the Treatment of Mineral Slimes" (1982). Open Access Dissertationsand Theses. Paper 3646.

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Evaluation of Di~solved Air Flotation,

for the Treatment of Mineral Slimes

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B.Eng. (McMaster University)

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Submitted to the Faculty, of Graduate Studies

in Partial Fulfilment of,.t.he R~quirements.

. for the Degree

,Master of ",Ene;Jineer.ing

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McMaster University

March 1982

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MASTER OF ENGINEERING(Chemical Engineering)

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McMASTER UNIVERSITYHamilton, Ontario

TITLE: EVALUATION OF DISSOLVED AIR FLOTATION FOR THETREA~ENT OF MINERAL SLIMES

AUTHOR: ALAN JOSEPH MELNYK. ,B. El!g. (McMaster lJ!liversity)

SUPERVISOR: Professor D. W. Woods

NUMBER OF PAGES: xi. ,209

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ABSTRACT

The recovery. of Ba'S04 mineral slimes (-10' inicrons) from silicausing dispersed and dissolved air flotation, was studied. Experiments

were performed in a modified commercial batch flotation machine. The

influence of flotation vari~bles such as collecto~c~ncentration,

concentration of silica depressant, pH, aeration and mineral purity on

"-;-_ flotation parameters were also examined.

Experimental eyidence suggests that dissolved air flotation results

in ,enhanced BaS04 r,e.covery over that normally achieved using dispersed

air, flotation for a limited range of elCperimental conditions. This

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range is character;zed by poor BaS04 flotation conditions such as low pH

or' collector concentration;' The flotation of BaS04 was found to be'

.strongly influenced by variables which regulate the surface chemistry of

the mineral, such as collector concentration, pH, .,silica depressant and

ml'neral purity. It was also speculated that D1echanical transfer or.

gangue into' the froth may be a critical factor :tn the upgrading of\" barite ores.

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ACKNOWLEDGEMENTS

I would like to express my sincere thanks to Dr. D. R. Woods

for his encouragement and effort during the course of this study.

I would like to thank Dr. Muthuswarni for his, informative

discussions.

The technical assistance of Mr. L. Suggett, Mr. H. Behrnann

and Mr. L. Salemi is also ~eatly appreciat~d.

Financial assistance provided by, McMaster University and the

National Science and Engineering Research Council ~~ appreciated.

I would also like to extend my sincere thanks to Valerie and

Henry Meng, Mehrnet Carnurdan, Kevin Smith, Mark costin and the

many other graduate students who hav~ provided invaluable friendship

over' the last two years. ,

Most of all, I would like to express my gratitude and appreciation

to my wife, Janet for her help and comfort

. "A. J. Melnyk

Hamilton, March 1982

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TABLE OF CONTENTS

1 INTRODUCTIO~ 1

l,i Treatment Difficulties 3.

1.2 S~rvey of New Slime Treatment 5Techniques

1. 2.1 Piggy Back Flotation 5

1.2.2 Electrophoresis 6

1.2.3 Magnetic and Electrostatic S~paration 7

1.2.4 -L~quid-Liquid Extraction1.2.5 Selective Flocculation

2 DISSOLVED AIR FLOTATION

7

8

11

2.1 Mechanism and Factors Influencing 13Dissolved Air Flotation

2.1.1 Factor& Influencing the, Size and Rate 13of Precipitation of Air Bubbles

2.1.2 Factors Influen~ing the Attachment'of Precipitating Air to ~he MineralSurface

23

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2.1.3 Mineral Surface Activation byP~ecipitation of ~!ne Bubbles

3 EXPERIMENTAL APPROACH

2.2

3.1

3.2

Summary of a Pre~lous Investigation inDissolved Air'Flotation of MineralSlimes

f\ppar.atus

Experimen~al Procedure.

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47

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4 RESULTS AND DISCUSSION ' 5~.

4.1 Introd\lction 54' .

4.2 D.A.F. 54

4.3 Collector Concentration 63

4.4 Depressant 69

4.5 purity of'BaS04 73

4.6 pH 76

4.1 Aeration 83

4.8 Celestite Flotation 93

5 CONCLUSIONS 100

References,

lOG.

Nomenclature 11QI Al DEVELOPMENT OF E~UATION TO PREDICT VOLUME OF 114

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AIR PRECIPITATINGFROM SOLUTION

A2 EXPERIMENTAL DETAILS 117

A2.a Expe~imental Procedure 118

A2.a.l Mineral Preparation 118 .

A2.a.2 Pre-Flotation Procedure 119

A2.a.3 Flotation Procedure 120

A2.a.4 Analysis of Flotation Products 121,

A2.b Equipment Description 122

A3 EXPERIMENTAL RESULTS I29

M STATISTICAL ANALYSIS 167

A4.a Estimate of Variance 168

M.b Hypothesis Tests 169

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A4.b.l Randomized Block Test

A4.b.2 Hypothesis ~est for Comparing TwoPopulation Means

A4.b.3. Hypothesis Test for Comparison of -:'an Experimental,Value to an'Ex~ctedValue

Page

169

171

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M.c.l 2.' Factorial Design

A4.c.2 2' Fa'ctorial,. Design.

M'.c.3. Dete~ination of ~ignificant Effects'\

AS SAMPLE CALCULATION OF ~LOTATION RES,ULTS .(

ALc Factorial Desig~ Analysis '174

175

176

"176

1'95

AS.a Determination of Maximum Vo~ume of 196Dissolved Air AVailable for'Precipitation

AS.b Determination of Solid Weight to 196Slurry Volume Ratio

AS.c Determination of Weight % Nloated 1198

AS.a Determination of % BaS04 Recovered 199

AS.e Determination of the Upgrading Factor 200

AS.f Determination oft~e %"Separation 201Efficiency

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A6 PARTICLE SIZE DETERMINATION

, A6.a Procedure

'A6.b' Particle Size Distribution

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Table

'1 Klassen.'sFlotation

LIST OF TABLES

Title,

Comparative Results ofExperiments

Page

44

2

3

4

5

6

A2-l

M-l

M-3

M-4

M-5

Klassen's Size Analysis of FlotationProducts of Barite Slimes

Random Block Analysis of the qbservedDifferences between D.A.F. andDispersed Air .Flotation

Mineral solubiiity ,Data

Comparison of Klassen's Results andCurrent 'Experimental. Obse;vations forthe Flotation of Ba~e SlimesMagnitude of Effects of FlotationVariables Relative to:D.A.F.

Equipment Specification apd Suppliers

Individual and Pooled VarianceEstimates for Each Flota~ion Parameter

Observed Differences 'between D.A.F.and Dispersed Air Flotation

Calculated T Values for the Effectof Dissolved Air Concentration on

.. .Flotation.Parameter~

Calculated T Values for the 'Difference.

'between ~.A.F. and Dispersed AirFlotation

Calculated T Values for the Effect ofCollector Concentration on FlotationParameters

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61

71

96

99

123

180

181

182

183

184

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Table Title Page

A4-6' J Calculated T Values for'the Effect of lB5Depressant on Flotation Parameters

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A4-7 Calculated T Values for.Effects~oj lB6 ). Purity of BaS04 on Flotation ( .

Param~ters

I A4-B Calculated T Values for the Difference 187in Flotation Parameterll for theFlotation of gelestite and Barite fromSilica

,.

A4-9 Calculated Valu~s for the'Effect ofT lBB .)pH on Flotation Parameters

'A4-l0

A4-11

Calculated T,~alues for tpe Effect ofAeration (RPM) on F1otat1on Parameters

Calculatl:!d~T Values for the 'Differencebetween Klassen's Results and CurrentExperimental Observations for theFlotation of Barite Slimes

189

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190

E~fects of Collector Concentration,pepressant and D.A.F.

Effects of BaS04 Purity, Depressant\

and D.A.F. on Flotation Parameters

A4-12

A4-13

A4-14 Effects ofand D.A.F.

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Celes~ite Flotation, pHon'Flotation Parameters

191

192.,

193..

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A4-15

A6-1

Effects of Aeration and D.A.F. onFlotation Parameters'

Particle Size Distribution

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194

206

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LIST OF FIGURES

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Figure

1

2

3

Title

The-Various Aspects of the SlimesProblem with Particular Reference toFlotation

Effect of Frother Concentration onthe Precipltati~n of Gases fromSolution

Effect of Saturation of the Solutionand of Frother on the Average Sizeof Gas Bubbles Precipitating fromSolution

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14

16

4 Total Surface Area of GasPrecipitating from 1 L ofat Different Pressures

BubblesSolution

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19

5

6

7

8

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Volume of Gases Precipitating fromSolution at Different Pressures

Variation of Wl/W2 with Contact Apgle

Coalescence and Direct Attachment, . of a Bubble to a Solid Surface

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Activation of Flotation byPrecipitation of Gas Bubbles fromSolution

Flotation of a Mixture of Fluoriteand Quartz of Size less than 10 micron,

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with Different Additions of SodiumSilicate

Effect ofPUlp Density on theFlotation of a Mixture of Fluoriteand Quartz of a Size less than10 microns

ix

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2l~27

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37

39

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Figure Title

--Flotation of Barite and Quartzof a Size less than 10 microns withDifferent Add~tions of SodiumSilicate

Page

41

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Flotation Cell and Pressure Chamber

Batch Dissolved/Dispersed AirFlota~o~ Apparatus

Distribution of Differenes in Weight% Floated between D.A.F. and DispersedAir Flotation

49

50

56

15

16

Distribution of Differences in %BaS04 Recovery between D.A.F. andDispersed Air Flotation

Differences in Upgrading Factorbetween D.A.F. and Dispersed AirFlotation

57

58

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D.A.F.17

18

Distribution of Differences inSeparation Efficiency betweenand Dispersed Air Flotation

Effect of 'Collector Concentration onthe 'Weight % Floated

59

64

Effect of pH on % BaS04 Recovery

Effect of pH on the Upgr~ding Factor

Effect of Collector Concentration on, Separation EfficienfY

Effect of pH on weigh~ Floated

Concentration onEffect of Collector% BaS04 Recovery

81

79

80

66

67

65

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Effect on Collector Concen~rationthe Upgrading Factor i,

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24

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22

20

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CHAPTER 1 .

INTRODUCTION

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Mineral slimes ~s a derogatory term used to indicate the

nuisance characteristics of fine mineral' particles. An acceptable

g~neral definition describes slimes as "the fraction of 'ore that is

too fine to, be commercially exploited by the conventional' processes

developed for coarser size fractions" [1].

The. upper size limit used to define slimes varies, dependinll on

the ore being treated (i.e. an upper size limit of 3 ~m for

Cassiterite [2.3] to an' upper size limit of 50 ~m for fluorite'[4]

has' been observed) and actual treatment proces~ (i.e. upper sizelimi~s for gaiena have been. industrially observed to be between 7 ~m

[5] and 20 ~m [6]).Primary slimes are, those caused, by the weathering and

decomposition of certain rock components. Secondary slimes are

produced as a result of comminution of ore.ePresently many large ore bodies are not being exploi'ted since

the liberation size of the de!l!red mineral is below 30 ~m [7];

Furthermore. often conventional mineral processes reject slimes whichmay contain an appreciable mineral content because of treatment

difficulties.

However. with the continued exhaustion of natural reso,urces it

is important that problems in recovering slimes be resolved.

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McMaster UniversityDigitalCommons@McMaster3-1-1982

Evaluation of Dissolved Air Flotation for the Treatment of Mineral SlimesAlan Jospeh MelnykRecommended Citation