Laboratory Testing Services:
Metallurgical Laboratory Testing services are the primary source of data used to select and design a metallurgical process. The primary providers for these services are assay laboratories, metallurgical testing laboratories, and engineering firms. When starting with new samples, it is important to first determine if the sample is valuable. If the sample contains valuable material, then additional testing may be warranted.
There are many different tests that can help determine if a material can be processed economically including composition and mineralogy, comminution, load permeability and strength and stability, beneficiation, slurry rheology, and environmental testing.
Do I have a valuable material?
At the beginning of the project, it is important to determine if a material contains a value of interest (usually a metal or a mineral). Characterizing the value of the material early in the testing process can save time and money. An experienced prospector or geologist may be able to visibly identify important minerals in a sample with the naked eye. However, if the material is too fine in nature an assay, hand lens, or microscope might be required.
Once a valuable material has been identified, samples of the material are taken and assayed. If the samples contain significant concentrations of valuable metal(s), they may be selected for further testing. A material with significant concentrations of a metal(s) may not actually contain values that can be extracted, therefore, it is important to determine if a material can be processed economically.
Can my material be processed economically?
There are many factors that influence a material’s amenability to metallurgical processing such as metal prices, mineralogy, and location. These factors help a metallurgist select appropriate metallurgical tests. Often a basic metallurgical testing scope, that is specific to the target metal(s), will be proposed by the metallurgical lab or consultant. For example, if an ore contains gold and silver a common scope may include gravity, flotation, and cyanide bottle roll testing.
Once metallurgical tests have been completed, the data (often including recoveries and reagent consumptions) are used to determine the next course of action.
If a material is not amenable to processing, diagnostic testing or a different testing method may be considered. If a material is amenable to processing, the testing scope often expands and may lead to multiple testing programs with many different types of tests. Many of the common tests and their purposes are discussed in the sections below.
Composition and Mineralogy
The composition and mineralogy of a sample directly affect which processes can be used to extract the metal(s) of interest. For example, an oxide sample is often more amenable to leaching than a sulphide sample.
Composition of a sample is determined through assaying. Although assay programs vary they should include an assay of the target metal. For example, a gold testing program should include fire assays. Identifying the remaining elements contained in a sample is important as they also affect processing. For example, high concentrations of copper when considering cyanide leaching could increase cyanide consumptions significantly, resulting in higher costs. Assay labs often offer a multielement assay package that provides composition data for around 50 elements. Carbon and sulphur assays are also commonly recommended.
The mineralogy of a sample is often determined through an ore petrography study. If samples are particularly hard to process, a sample may require a more detailed study such as mineral liberation analysis (MLA) or QEMSCAN analysis. These processes are more expensive but provide quantitative information about many different mineralogical characteristics, including mineral identification and grain size.
