Thiosulfate-copper-ammonia leaching of pure gold and pressure oxidized concentrate

Antti Porvali, Lotta Rintala, Jari Aromaa, Tommi Kaartinen, Olof Forsen, Mari Lundstrom

Research output: Contribution to journalArticleScientificpeer-review

2 Citations (Scopus)

Abstract

In this research cyanide-free leaching of pure gold and pressure oxidized refractory gold concentrate by thiosulfate-copper-ammonia solutions were examined. A quartz crystal microbalance (QCM) was used to study gold leaching as a factorial series where the best gold leaching rate (2.987 mg/(cm2·h)) was achieved with a solution consisting of 0.2 M (NH4)2S2O3, 1.2 M NH3, 0.01 M CuSO4 and 0.4 M Na2SO4. Temperature had the greatest effect on the gold leaching rate. An increase in thiosulfate concentration (0.1-0.2 M) increased gold dissolution. The combined effect of temperature and ammonia concentration had a statistically significant effect on the gold leaching rate at 0.1 M M2S2O3. Combination of applied potential and NH3:S2O3 ratio had a statistically significant effect on the gold leaching rate at 0.2 M M2S2O3. An increase in applied potential decreased the gold dissolution rate at low ammonia concentrations but increased it at high concentrations. A pressure oxidized gold concentrate was leached for 6 hours in the batch reactor leaching experiments. The effect of rotative velocity (1.26-1.56 m/s) and slurry density (10-30 wt%) was investigated at the following leaching parameters: 0.2 M Na2S2O3, 0.6 M NH3, 0.01 M CuSO4, 0.4 M Na2SO4. Lower slurry density (10 wt%) resulted in a higher Au leaching efficiency. An increase in the rotation rate did not have an effect on the final Au leaching recovery. The best Au leaching efficiency (89%) was achieved with 590 rpm mixing, 1.56 m/s rotative velocity and 10 wt% slurry density.
Original languageEnglish
Pages (from-to)1079-1091
Number of pages13
JournalPhysicochemical Problems of Mineral Processing
Volume53
Issue number2
DOIs
Publication statusPublished - 1 Jan 2017
MoE publication typeA1 Journal article-refereed

Fingerprint

Thiosulfates
thiosulfate
leaching
Ammonia
Gold
Leaching
Copper
ammonia
gold
copper
slurry
dissolving
Dissolution
dissolution
Quartz crystal microbalances
Cyanides
Batch reactors
cyanides
refractories
cyanide

Keywords

  • gold leaching
  • quartz crystal microbalance
  • thiosulfate

Cite this

Porvali, Antti ; Rintala, Lotta ; Aromaa, Jari ; Kaartinen, Tommi ; Forsen, Olof ; Lundstrom, Mari. / Thiosulfate-copper-ammonia leaching of pure gold and pressure oxidized concentrate. In: Physicochemical Problems of Mineral Processing. 2017 ; Vol. 53, No. 2. pp. 1079-1091.
@article{8d7173c2db184f10967e78f1a7bc1b6a,
title = "Thiosulfate-copper-ammonia leaching of pure gold and pressure oxidized concentrate",
abstract = "In this research cyanide-free leaching of pure gold and pressure oxidized refractory gold concentrate by thiosulfate-copper-ammonia solutions were examined. A quartz crystal microbalance (QCM) was used to study gold leaching as a factorial series where the best gold leaching rate (2.987 mg/(cm2·h)) was achieved with a solution consisting of 0.2 M (NH4)2S2O3, 1.2 M NH3, 0.01 M CuSO4 and 0.4 M Na2SO4. Temperature had the greatest effect on the gold leaching rate. An increase in thiosulfate concentration (0.1-0.2 M) increased gold dissolution. The combined effect of temperature and ammonia concentration had a statistically significant effect on the gold leaching rate at 0.1 M M2S2O3. Combination of applied potential and NH3:S2O3 ratio had a statistically significant effect on the gold leaching rate at 0.2 M M2S2O3. An increase in applied potential decreased the gold dissolution rate at low ammonia concentrations but increased it at high concentrations. A pressure oxidized gold concentrate was leached for 6 hours in the batch reactor leaching experiments. The effect of rotative velocity (1.26-1.56 m/s) and slurry density (10-30 wt{\%}) was investigated at the following leaching parameters: 0.2 M Na2S2O3, 0.6 M NH3, 0.01 M CuSO4, 0.4 M Na2SO4. Lower slurry density (10 wt{\%}) resulted in a higher Au leaching efficiency. An increase in the rotation rate did not have an effect on the final Au leaching recovery. The best Au leaching efficiency (89{\%}) was achieved with 590 rpm mixing, 1.56 m/s rotative velocity and 10 wt{\%} slurry density.",
keywords = "gold leaching, quartz crystal microbalance, thiosulfate",
author = "Antti Porvali and Lotta Rintala and Jari Aromaa and Tommi Kaartinen and Olof Forsen and Mari Lundstrom",
year = "2017",
month = "1",
day = "1",
doi = "10.5277/ppmp170231",
language = "English",
volume = "53",
pages = "1079--1091",
journal = "Physicochemical Problems of Mineral Processing",
issn = "1643-1049",
publisher = "Wroclaw University of Technology",
number = "2",

}

Thiosulfate-copper-ammonia leaching of pure gold and pressure oxidized concentrate. / Porvali, Antti; Rintala, Lotta; Aromaa, Jari; Kaartinen, Tommi; Forsen, Olof; Lundstrom, Mari.

In: Physicochemical Problems of Mineral Processing, Vol. 53, No. 2, 01.01.2017, p. 1079-1091.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Thiosulfate-copper-ammonia leaching of pure gold and pressure oxidized concentrate

AU - Porvali, Antti

AU - Rintala, Lotta

AU - Aromaa, Jari

AU - Kaartinen, Tommi

AU - Forsen, Olof

AU - Lundstrom, Mari

PY - 2017/1/1

Y1 - 2017/1/1

N2 - In this research cyanide-free leaching of pure gold and pressure oxidized refractory gold concentrate by thiosulfate-copper-ammonia solutions were examined. A quartz crystal microbalance (QCM) was used to study gold leaching as a factorial series where the best gold leaching rate (2.987 mg/(cm2·h)) was achieved with a solution consisting of 0.2 M (NH4)2S2O3, 1.2 M NH3, 0.01 M CuSO4 and 0.4 M Na2SO4. Temperature had the greatest effect on the gold leaching rate. An increase in thiosulfate concentration (0.1-0.2 M) increased gold dissolution. The combined effect of temperature and ammonia concentration had a statistically significant effect on the gold leaching rate at 0.1 M M2S2O3. Combination of applied potential and NH3:S2O3 ratio had a statistically significant effect on the gold leaching rate at 0.2 M M2S2O3. An increase in applied potential decreased the gold dissolution rate at low ammonia concentrations but increased it at high concentrations. A pressure oxidized gold concentrate was leached for 6 hours in the batch reactor leaching experiments. The effect of rotative velocity (1.26-1.56 m/s) and slurry density (10-30 wt%) was investigated at the following leaching parameters: 0.2 M Na2S2O3, 0.6 M NH3, 0.01 M CuSO4, 0.4 M Na2SO4. Lower slurry density (10 wt%) resulted in a higher Au leaching efficiency. An increase in the rotation rate did not have an effect on the final Au leaching recovery. The best Au leaching efficiency (89%) was achieved with 590 rpm mixing, 1.56 m/s rotative velocity and 10 wt% slurry density.

AB - In this research cyanide-free leaching of pure gold and pressure oxidized refractory gold concentrate by thiosulfate-copper-ammonia solutions were examined. A quartz crystal microbalance (QCM) was used to study gold leaching as a factorial series where the best gold leaching rate (2.987 mg/(cm2·h)) was achieved with a solution consisting of 0.2 M (NH4)2S2O3, 1.2 M NH3, 0.01 M CuSO4 and 0.4 M Na2SO4. Temperature had the greatest effect on the gold leaching rate. An increase in thiosulfate concentration (0.1-0.2 M) increased gold dissolution. The combined effect of temperature and ammonia concentration had a statistically significant effect on the gold leaching rate at 0.1 M M2S2O3. Combination of applied potential and NH3:S2O3 ratio had a statistically significant effect on the gold leaching rate at 0.2 M M2S2O3. An increase in applied potential decreased the gold dissolution rate at low ammonia concentrations but increased it at high concentrations. A pressure oxidized gold concentrate was leached for 6 hours in the batch reactor leaching experiments. The effect of rotative velocity (1.26-1.56 m/s) and slurry density (10-30 wt%) was investigated at the following leaching parameters: 0.2 M Na2S2O3, 0.6 M NH3, 0.01 M CuSO4, 0.4 M Na2SO4. Lower slurry density (10 wt%) resulted in a higher Au leaching efficiency. An increase in the rotation rate did not have an effect on the final Au leaching recovery. The best Au leaching efficiency (89%) was achieved with 590 rpm mixing, 1.56 m/s rotative velocity and 10 wt% slurry density.

KW - gold leaching

KW - quartz crystal microbalance

KW - thiosulfate

UR - http://www.scopus.com/inward/record.url?scp=85019761230&partnerID=8YFLogxK

U2 - 10.5277/ppmp170231

DO - 10.5277/ppmp170231

M3 - Article

VL - 53

SP - 1079

EP - 1091

JO - Physicochemical Problems of Mineral Processing

JF - Physicochemical Problems of Mineral Processing

SN - 1643-1049

IS - 2

ER -