The analysis of commodity elements’ grade in the actual feasible mineralogical phase can be the most important analytical information both for exploration and mining
When the mineralogical composition of the ore is complex and the commodity element exists in different mineralogical phases, it is extremely important to know the grades of the element in these different phases. This can be carried out by leaching samples with phase or mineral selective leaching agents and instrumental analysis of elements.
The leaching tests can be done using individual, phase selective leaches or so called sequential or diagnostic leaches. These methods can be applied both to characterisation of new ores and to problem solving for ores, where metallurgical problems are faced. If the methods are selected adequately, they will give direct information of metallurgical characteristics of the ores. Together with data from the mineralogy, leaching tests can be useful to specify the leaching and assaying methods to be applied both to exploration/grade control drilling and the subsequent metallurgical test program.
Cu and Ni in sulphide minerals
Particularly in defining the resources of disseminated low grade Ni-ores it is more meaningful to analyse recoverable (sulphidic) Ni-grades than total Ni-grades (including silicate–Ni) already in the exploration stage. This gives a better basis for economic analysis and metallurgical design of the ore processing. This assay can be done using unique sulphide selective leaches like ammonium citrate – hydrogen peroxide leach. Also Cu and Ni can be analysed in oxide-phase in weathered ores.
Free and refractory gold
The mode of occurrence of gold can also be complex. It can exist as metallic, free gold and in refractory form in sulphide-, telluride-, etc minerals. Using a cyanide leach to define the metallic gold and Fire assaying the leach tailing for refractory gold, these two different modes can be defined. More comprehensive information of gold in different mineralogical phases can be analysed using sequential (diagnostic) leaching techniques.
Other chemical speciation methods at Labtium:
- Speciation of carbonate/non-carbonate carbon
- Speciation of sulfidic/ sulphate sulphur
- Speciation of Fe2+ and Fe3+ (FeO/Fe2O3)
- Speciation of arsenite/arsenate
Labtium can develop also other speciation and diagnostic leaches tailored to client requirements.