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Author: search.filters.author.Beaumont, ChristopherHas files: Yes

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    A geometallurgical strategy for improving ore quality and mineral processing efficiency at Kansanshi Mine in Zambia
    (2016) Beaumont, Christopher
    The Kansanshi mine is located in north-western Zambia. It is a copper and gold bearing, vein hosted, structurally controlled, ore deposit, which is exploited using conventional open pit mining methods. A series of highly complex mineralogical suites have formed through the interaction of the in-situ geological, weathering and oxidation processes. Some of these mineralogical suites are extremely difficult for effective extraction of copper and gold. Currently ore is classified into 22 different quality categories using a system called “Mat_Type”. Only the “best quality” ore is directed to the metallurgical process plant, while the remaining “poor quality” ore is directed to long term stockpiles. These stockpiles are unlikely to be processed until the end of the life of mine despite containing metal quantities of significant value. A systematic investigation of Kansanshi’s mine value chain was carried out to determine if this value could be realised sooner. It was found that, due to a lack of integration between technical silos that form the mine value chain, the Mat_Type system does not take due consideration of geological, mineralogical nor metallurgical processes. Ore quality control factors are incorrect and economic data to determine suitable cut-off grades is both outdated and applied in an inappropriate manner. As a result 12 of the 22 Mat_Type ore categories are unnecessary, while a further six categories are inaccurately defined, leaving only four categories that can be considered to be correct. It is because of these errors, that so much ore is being directed to long term stockpiles. Through the research study presented in this report it was found that five key factors determine an effective ore classification system for Kansanshi mine. These factors can be defined as: Spatial distribution of mineralogical relationships between in-situ geological, oxidation and weathering domains;  The impact of mineralogical groupings on copper recovery in each metallurgical process;  The size, statistical distribution, range and accuracy of available data sets; The application of appropriate economic factors in the mineral resource to mineral reserve conversion process; and,  The practicality of overcoming physical constraints at various stages of the mining process A more appropriate geo-metallurgical ore classification system can be developed that will consider the above listed factors. Three mineralogical groupings naturally exist in the deposit. Using total copper and acid soluble copper assay data, these mineralisation categories can be defined by a specific range of oxidation ratio. These ranges can be listed as: Primary copper sulphide minerals, with oxidation ratio < 0.1 ;  Secondary copper sulphide minerals, with an oxidation ratio between 0.1 to 0.8; and ,  Primary copper oxide minerals, with an oxidation ratio between 0.8 to 1.0. Each mineralogical grouping can be assigned to a specific metallurgical process. Further subdivisions of these groupings can be made based upon economic grade ranges and appropriate metallurgical quality control factors which are linked to a specific metallurgical process. By implementing the proposed geo-metallurgical ore classification system, 12 of the erroneous ore categories in the Mat_Type system can be removed. The remaining 10 categories would be accurately and consistently defined. This will lead to a significant reduction in the quantity of ore directed to long-term stockpile, thereby releasing previously lost value. The new ore classification methodology proposed would be supported by a systematic process to manage regular, periodic updates, based on new data and developments in technical understanding across all functional areas of the mine value chain. A continued dialogue and sharing of knowledge between the main technical silos is critical when promoting a robust and integrated ore classification system. Such a system has the potential to remain relevant throughout the life of Kansanshi mine.