Society of Mineral Analysts and the Canadian

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The Center for Advanced Mineral

and Metallurgical Processing

The Chemical Analysis of IndustrialAlkaline Sulfide HydrometallurgicalProcesses.

Corby G. Anderson, Ph.D.Director

Montana Tech of The University of Montana

1300 West Park Street • Butte, MT 59701 USA

Phone: 406-496-4794 Fax 406-496-4512

E-mail: [email protected]

“Providing“Providing“Providing

High QualityHigh QualityHigh QualityMetallurgicalMetallurgicalMetallurgical

Solutions toSolutions toSolutions to

IndustrialIndustrialIndustrialClientsClientsClients

World Wide”World Wide”World Wide”

___________________________________________________________________________________________________

Speakers Page Table of Contents



The Center for Advanced Mineral and

Metallurgical Processing

• A Process Engineering, Consulting, and Testing FacilityConducting Applied Projects With Industrial ClientsThroughout the World

• Providing Testing, Design, Consulting and FeasibilityStudies For:

Mineral Processing & Hydrometallurgical Applications •Precious Metal Recovery & Refining Technologies •Nickel/Cobalt Applications & Technologies •

Arsenic/Antimony Applications & Technologies • Pressure

Leaching Applications • Copper Leaching, SX, EWApplications & Technologies • Process Simulation andModeling • Pyrometallurgical Applications • X-Ray

Diffraction/Scanning Electron Microscopy • Resource

Recovery • Wastewater Remediation • Fire Assay • More •

CAM P



SMA-CMA Annual Conference

April 23-25, 2002 · Spokane Wa.

Fundamentals and App l icat ions

of F i re Assay Short Course2002 DATES:

AUGUST 18-23, 2002

CAMP – Mont ana TECHWWW.MTECH.EDU/CAMP

Host ed atFai r m ont Hot Spr ings Resor t



Alkaline Sulfur Chemistry

Kraft pulp and paper processing.Antimony hydrometallurgy.

Gold leaching and recovery. Hydroxide, Carbonate, Total Alkalinity.

Sulfide, Sulfite, Sulfate, Thiosulfate,Hydrosulfide, Polysulfides, Total Sulfur.





Kraft Alkaline Sulfide PulpProcess

Hydrolysis of lignins to alcohols andacids; some mercaptans formed.

Cooking liquor 12.5 % NaOH, Na2

S, and

Na2CO3

Recovery of ‘black liquor’ important.

Na2SO4 + 2C Na2S + 2 CO2

Na2CO3 + Ca(OH)2 – 2 NaOH + CaCO3





Na2S + Sb2S3 2NaSbS2

NaSbS2 + Na2S Na3SbS3

Alkaline Sulfide Antimony





Cathode: SbS3-3 + 3 e- SbO + 3 S-2


Anode: 2 OH- ½ O2 + H2O + 2e-

S-2 e- + oxidized sulfur species as

thiosulfate, polysulfide, sulfate, sulfite.



SMA CMA A l C f



Typical Sb AlkalineSulfide Flow Sheet

Alkaline Sulfide

Leach

Liquid

Solid

Separation

Alkaline Sulfide

Solution EW

Alkaline Sulfide

Solution Oxidation

Sb Metal

Antimonate



SMA CMA Annual Conference



4So + 6NaOH 2Na2S + Na2S2O3 + 3H2O

(X-1)So + Na2S Na

2S

X(where X= 2 to 5)

Na2SX + (X-1)Na3SbS3 (X-1)Na3SbS4 + Na2S







Alkaline Species Analysis

• ‘ABC’ titration method.

• From PPG and sulfide industry.

• pH based titration• 1 Normal HCl used.

• Determines, S-2, OH-, CO3-2 , total

alkalinity.







• 3 points titrated: A, B, C.

• C< (2*B) S-2, OH-, CO3-2 present.

•C > (2*B), HS-, S-2, CO3-2 present

•C > (2*B), A is absent, HS-, HCO3-1

CO3-2 present.

• Point C is total alkalinity.





f






• Specific sulfide titration method.

• From James River in pulp and

paper industry.• AgNO3 based titration

• 2 Ag+ + S-2 Ag2S

• Done with sulfide ISE inammoniacal medium.

• Can differentiate polysulfides from

sulfides unlike ‘ABC’ method.






• Thiosulfate and sulfite titration

method.

• From TAPPI and paper industry.• Iodine based titration

• Sulfide precipitated with Zn

• Oxidation with iodine followed byoxidation with hypoiodate.



A il 23 25 2002 S k W




• First titration in presence of excess

iodine with thiosulfate and Pt probe.

• Second titration in presence of 12Nhydroxide with iodine and Pt probe.

• Thiosulfate and sulfite calculated by

difference in titrations.



A il 23 25 2002 S k W




• Polysulfide determined by

thiosulfate and sulfite method.

• SO3

-2

+ S2

-2S2O3

-2

+ S

-2

• Thiosulfate and calculated by

difference in titrations before and after

sulfite treatment.



A il 23 25 2002 S k W




• Sulfate determined by Barium

chloride precipitation.

• Ba + SO4

-2BaSO4

• Sulfide, thiosulfate polysulfide

carbonate, hydroxide and sulfite

removed beforehand by boiling HClpretreatment and filtration.



April 23 25 2002 Spokane Wa




• Total sulfur analysis determined by

Barium chloride precipitation.

• Ba + SO4

-2BaSO4

• Sulfide, thiosulfate polysulfide and

sulfite oxidized to sulfate with

bromine.

• Carbonate and hydroxide removed

by HCL neutralization.



April 23 25 2002 · Spokane Wa





April 23-25 2002 · Spokane Wa




• Alkaline sulfide gold content

determined by direct fire assay of

solutions.• Weigh solution directly into assay

formulation.

• Carefully DRY fire assay chargebefore fusion.



April 23-25 2002 · Spokane Wa



Fundamental Electrochemical Studies

Chemical Engineering

Monash University – Melbourne Australia

Process Design

CAMPMontana Tech

Alkaline Sulfide Gold Leaching

April 23 25, 2002 Spokane Wa.




Sulfide Pressure Oxidation

Partial

2H+ + 1/2O2 + S-2 So + H2O

Complete

2O2 + S-2 SO4 -2







Nitrogen Species Catalyzed Leaching Fundamentals.

3 MeS (S)+ 2HNO3 (Aq)+ 3H2SO4 (Aq)

MeSO4 + 3So(S) + 2NO (G) + 4H2O

NaNO2 (Aq) + H+ HNO2 (Aq) + Na+

HNO2 (Aq) + H+ NO+(Aq) + H2O

2MeS (S) + 4NO+(Aq) 2Me+2

(Aq) + 2So + 4NO (G)

p , p





Relative Potentials of Hydrometallurgical Oxidizers.

E0h

Oxidant Redox Equation (pH = 0, H2 ref.)

Fe+3 Fe+3 + e- Fe+2 0.770 V

HNO3 NO3- + 4H+ +3e- NO(g) + 2H2O 0.957 V

HNO2 NO2- + 2H+ + e- NO(g) + H2O 1.202 V

O2 (g) O2 + 4H+

+ 4e-

2H2O 1.230 VCl2 (g) Cl2 (g) + 2e - 2 Cl- 1.358 V

NO+ NO+ + e- NO(g) 1.450 V

p , p






2NO (G) + O2 (G) < --> 2NO2 (G)

2NO2 (G) <--> 2NO2 (Aq)

2NO2 (Aq) + 2NO (Aq) + 4H+ <--> 4NO+(Aq) + 2H2O






2MeS (G) + 4H+ + O2 (G) 2Me+2(Aq) + 2So + 2H2O



Nitrogen Species CatalyzedPartial Sulfide Oxidation Leach Conditions.

Initial Free Sulfuric Acid = 50 g/

Reactor Working Pressure = 620 kPagSlurry Solids Content = 100 g/L

Solids Size = 80% minus 10 micron

Maximum Temperature = 125o CNitrogen Species Concentration = 2.0 g/L

Reaction Time = 30 minutes





Alkaline Sulfide RecoveryWith Partial NSC Sulfide Oxidation.

Au recovery = 93.3%





Alkaline Sulfide Solid Leaching

4So + 6 NaOH 2Na2S + Na2S2O3 + 3H2O

(X-1)So + Na2S Na2SX (where X= 2 to 5)





Alkaline Sulfide Gold Leaching

Auo + S5-2 AuS5- + e-

Auo + S2O3-2 AuS2O3- + e-

SMA-CMA Annual Conference April 23-25, 2002 · Spokane Wa.



• Electrowinning

• Cementation• Gaseous Precipitation

• Chemical Precipitation• Solvent Extraction

• Ion Exchange

Alkaline Sulfide Gold Recovery




Alkaline Sulfide Gold Leach Head Solution Assay.

Volume L Au Sb As Hg Sn

0.5 88.7 ppm 21.0 g/L 5.31 g/L 274 ppm 1.84 g/L




Alkaline Sulfide Gold Leach Head Final Assay.

Volume L Au Sb As Hg Sn

0.5 1.5 ppm 21.1 g/L5.21 g/L 274 ppm 1.89 g/L




Overall Gold Selectivity and Recovery.

Liquid Solid

Gold 1.7% 98.3%

Antimony 100.0% 0.0%

Arsenic 100.0% 0.0%

Tin 100.0% 0.0%

Mercury 100.0% 0.0%



• Pulp and Paper Manufacture• Glass Industry

• Ceramic Industry

• Detergents

• Feed Supplements

• Textile Dyes

• Bleaching

• Photography

Sodium Sulfate Uses




Sodium Sulfate Production

2 O2 + Na2S Na2SO4

3.5 O2 + 2 NaOH + Na2S2 2 Na2SO4 + H2O

8 O2 + 8 NaOH + Na2S5 5 Na2SO4 + 4 H2O)

2 NaOH + 2 O2 + Na2S2O3 2 Na2SO4 + H2O





SUMMARY

Alkaline sulfur chemistry is pertinent.

Kraft pulp and paper processing.

Antimony hydrometallurgy.

Gold leaching and recovery.





Fundamentals and App l icat ions

of F i re Assay Short Course2002 DATES:

AUGUST 18-23, 2002

CAMP – Mont ana TECHWWW.MTECH.EDU/CAMP

Host ed atFai r m ont Hot Spr ings Resor t

The Center for Advanced Mineral



and Metallurgical Processing

Corby G. Anderson, Ph.D.

Director

Montana Tech of The University of Montana

1300 West Park Street • Butte, MT 59701 USA

Phone: 406-496-4794

Fax: 406-496-4512

E-mail: [email protected]

“Providing“Providing“Providing

High QualityHigh QualityHigh Quality

MetallurgicalMetallurgicalMetallurgical

Solutions toSolutions toSolutions to

IndustrialIndustrialIndustrial

ClientsClientsClientsWorld Wide”World Wide”World Wide”

___________________________________________________________________________________________________

Society of Mineral Analysts and the Canadian

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