Gold in Plant Tailings - Prevention and Recovery
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During 19 years as mineralogist in the mineralogical Laboratory of Anglovaal Limited the speaker was responsible, among other duties, for assisting metallurgical plants with recovery problems. He was able to assist plants that were recovering gold from Paleo placer deposits (Witwatersrand) and Greenstone domains (Barberton Mountain Land). This talk presents the seven most common causes encountered and solutions for most.
The outstanding characteristics of gold are chemical stability of the metal, high density and malleability. These characteristics are extensively employed in the recovery of gold.
Gold (like most other precious metals) has an exceptionably high value per unit mass. While most commodities can only be profitably mined at mass concentrations of parts per thousand or more, gold can be exploited at levels of parts per million.
The distribution of gold in the various types of ore body is extremely uneven and this uneven distribution must be kept in mind in the design of recovery processes.
What must also be kept in mind is that the sizes of the individual gold particles in any assay or metallurgical process sample will vary over a wide range.
The design of a gold recovery plant must be optimized for the characteristics of the ore that is to be fed to that plant.
Based on experience gained from deposits that are geologically similar to a new project "test mining" is sometimes preferred as a method of investigation. This method consists of feeding tens of tons through one or more test plants and comparing the amount of gold recovered to the gold assayed in the tailings.
Areas Covered in the Session:
Who Will Benefit:
- Relatively low expenditure on improved recovery will generally effect a disproportionately large improvement in profit
- The gold recovery process must be tailored to the ore type
- Mineralogical examination of the ore, the tailings, or both, can assist the finding of methods of improved recovery
- A well-equipped laboratory with sample preparation equipment, electron microprobe, scanning electron microscope and mineral upgrading equipment is required for this work
- Microscopic examination of polished sections, performed in isolation, is not always successful at solving a problem
- Diagnostic leaching is useful for problems such as high content of base metals in the ore or coating by iron-bearing compounds, but this method is not a cure-all
- A standard procedure is not a complete substitute for experience
- Incorrect sampling of tailings has been known to lead to underestimation of the gold being lost
- Gold recovery plant managers
- Managers of new gold projects
- Managers of exploration companies
- Students of metallurgy
Hannes Wagener, A registered Professional Natural Scientist with an M.Sc. degree in Geology obtained from the University of Natal, He is fellow of the Geological Society of South Africa, He is having a wide geological background, spanning exploration, mining, QAQC and laboratory investigations
He specializes in measuring, compiling and presenting data relevant to the upgrading and recovery of products of value from gold, copper, iron, manganese and fluorite ores also having sufficient knowledge of computer software to process data and present final reports, He has modelled recoveries of various categories of ore based on specific gravity data vs. jigging test data and subsequently applied the results to cores from the farm King to assist calculation of reserves. The results were incorporated into the BKM bankable feasibility study.