From rock to grades
Precious elements have exceptional properties e.g. density and their mode of occurrence can be challenging such as the “nugget effect” and refractory gold. All these items must be taken in consideration when selecting the best fit-for-purpose procedure for analysis of precious metals. Labtium has a broad and long expertise to help our clients in this task.
The selection of the analytical method depends also on the strategic phase of the project i.e. regional or targeted geochemical exploration, resource evaluation, grade control and hence the optimal concentration range for the analyses.
The methods used for geochemical exploration require in many cases a larger element suite with cost-effective price. The accuracy is not the most critical requirement for the analysis in comparison to e.g. sampling. In resource evaluation the geologist can focus on defining the grades of commodity elements, the requirements for precision and accuracy beeing more demanding, hence the analyses must be conducted by using more specific assay methods i.e. ore grade methods. Also when the geochemical methods have outlined higher concentrations of some elements and exceeding the recommended upper limits of used method, the analysis should be repeated with a more suitable assay method for these specific elements.
Normally the precision of geochemical analyses are in the range of 10 -20% and for assays <5%.
Labtium offers different pre-treatment and pre-concentration /separation methods for analyses of precious metals. These include aqua regia digestion, Fire Assay and cyanide leach combined with different methods of determination such as FAAS; GFAAS; ICP-MS; ICP-OES; gravimetry, each method having its own benefits and limitations.
In a project focusing on precious metals, additional data of other elements such as pathfinders, elements related to rock alteration etc. may be needed. A suitable set of elements can be selected from Labtium’s multi-element packages.
The set of elements may have to be complemented also with element-specific, individual method for elements or components which cannot be analysed by these analytical packages. These methods include sulphur-, carbon-, Hg- analyses, physical parameters like loss-on-ignition, specific gravity etc. (See Additional analyses).