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Sulphur & carbon analysis

Sulphur & carbon speciation

A wide variety of sulphur and carbon minerals and compounds are often found associated with ore deposits. These minerals can impact ore processing and how waste can be stored during mining. Identifying what minerals these elements are present in has important implications for ore and waste characterisation.

Carbono e enxofre

Sulphur Analysis

The dominant minerals that host sulphur are sulphides and sulphates. Distinguishing the proportion of each mineral type is often an important part of environmental and metallurgical characterisation of ore and waste rock. Sulphates do not produce acid during breakdown at surface conditions whereas sulphides are acid forming under the same conditions. Sulphides associated with ore can also impact the hydrometallurgical processing, such as where cyanide is used to leach gold and sulphide minerals compete to use reagents.

Methods available for sulphur analysis

A range of methods are offered to determine total sulphur, sulphur hosted in sulphide minerals and sulphur hosted in sulphate minerals.

Code Analytes Ranges Description
S-IR08 S (Total) 0.01%-50% Total sulphur by induction furnace/IR
S-GRA07 S (Elemental) 0.01%-100% Solvent leach with remaining elemental sulphur analysed by gravimetric finish.
S-GRA06a S (Sulphate) 0.01%-50% HCl (15%) leach of soluble sulphates, precipitation as barium sulphate and gravimetric finish.
Note: little to no dissolution of barite/celestite.
S-IR06a S (Sulphide) 0.01%-50% HCl (25%) leach to remove sulphates; induction furnace/IR. Note: little to no dissolution
of barite/celestite
S-GRA06 S (Sulphate) 0.01%-40% NaCO3 leach of sulphates, precipitation as barium sulphate and gravimetric finish.
S-IR07 S (Sulphide) 0.01%-50% NaCO3 leach of sulphates, induction furnace/IR.

Carbon Analysis

Identification of the minerals hosting carbon can be important for characterising the way rock will behave during processing or storage. Graphite and organic carbon can cause problems during cyanide based hydrometallurgical processing. Gold that is taken into solution during a cyanide digestion can adsorbed onto graphite and organic carbon in a process called preg-robbing.

Methods available for carbon analysis

ALS provides a wide range of methods to determine the total carbon, organic carbon, carbon in carbonate minerals, carbon in graphite, and carbon in non-carbonates.

Code Analytes Ranges Description
C-IR07 C (Total) 0.01%-50% Total carbon by induction furnace/IR.
C-IR06a C (Non-Carbonate) 0.01%-50% HCl (25%) leach at high temperature for 1 hour to expel carbonates as CO2,
residue analysed for C by induction furnace/IR.
C-GAS05 CO2 (Carbonate) 0.2%-50% HClO4 digestion and CO2 coulometer.
C-IR18 C (Graphite) 0.02%-50% HCl (50%) leach of carbonates, roasting to remove organic carbon, induction furnace/IR.
C-IR17 C (Non-Carbonate) 0.02%-100% Slow and repeated addition of HCl (50%) to decompose and evolve carbonates as CO2.
Residual carbon is then analysed by induction furnace/IR.
C-CAL15 C (Carbonate) 0.02%-100% Carbonate carbon calculated by difference. Requires C-IR07, C-IR17.

Sulphur & Carbon Packages

ALS offers a variety of economical packages to report both sulphur and carbon concentrations for the same sample.

Methods available

Several options for combined sulphur and carbon analysis are available. Two of these are listed in the methods table but please contact ALS for other method combination packages.

Code Analytes Ranges Description
ME-IR08 C (Total) and S (Total) 0.01%-50% Total carbon and sulphur by induction furnace/IR.
ME-IR06a C (Organic) and S (Sulphide)* 0.01%-50% Non-Carbonate carbon and sulphide sulphur by HCI (25%) leach to remove carbonates
and sulphates, induction furnace/IR.
*Sulphide sulphur may be overstated if BaSO4 or SrSO4 are present as they are insoluble with the HCl leach.

Downloads

pdf

ALS Cyanide Leach: What to consider Technical Note

Frequently asked questions

Related Topics

Gold Cyanidation

Gold preg-robbing analysis

If preg-robbing is suspected during gold analysis, specialised methods can determine the propensity for a sample to preg-rob in a cyanide leach.

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Isotope

Carbonate isotopes

Carbon and oxygen isotopes of carbonate minerals can provide a vectoring tool for carbonated host mineralisations where visible alteration is limited.

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ABA underlay

Acid base accounting

The concentration of carbon and sulphur are important parameters measured as part of acid base accounting packages.

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