Sulfur Speciation in Mining Leachate using Ion Chromatography

Table of Contents

Introduction
Sample
Sample preparation
Columns
Solutions
Analysis
Parameters
Instrumentation
Results

Introduction

In the gold mining process, there is a tendency to switch from the cyanide leaching process to the thiosulfate leaching process due to the reduced toxicity of the thiosulfate leaching.

However, the thiosulfate leaching process is sensitive and demands more optimization of the leach reaction components to maximize gold recovery and reduce reagent loss. A Metrosep A Supp 5 - 250/4.0 column is used to separate tetrathionate, thiocyanate, thiosulfate, and sulfite with perchlorate as the eluent as most of the metal perchlorates are water-soluble, thereby avoiding metal precipitation within the IC system.

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Sample

Mining leachate

Sample preparation

Dilution 1:2 in ultrapure water, injection following filtration (0.45 μm).

Columns

. .
Metrosep A Supp 5 - 250/4.0 6.1006.530
Metrosep A Supp 4/5 - Guard/4.0 6.1006.500

Solutions

Eluent 10 mmol/L sodium perchlorate
1.0 mmol/L sodium hydroxide

Analysis

UV/VIS detection

Parameters

. .
Flow rate 0.7 mL/minute
Injection volume 20 μL
Pmax 15 MPa
Recording time 32 minutes
Column temperature 35 °C
Wavelength 215 nm

Instrumentation

940 Professional IC Vario ONE 2.940.1100
944 Professional UV/VIS Detector Vario 2.944.0010
858 Professional Sample Processor 2.858.0020

Results

Anions Concentration [mg/kg] RSD [%, n = 3]
1 Sulfite < 1 -
2 Thiosulfate 58.8 2.2
3 Thiocyanate 49.7 1.9
4 Tetrathionate 28.6 1.4

Masteel UK Ltd

This information has been sourced, reviewed and adapted from materials provided by Metrohm AG.

For more information on this source, please visit Metrohm AG.

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