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UBC Theses and Dissertations

Continuous centrifugal concentrator operation and control McLeavy, Michael J.


A study was conducted to evaluate the operation and control of a continuous centrifugal gravity concentrator. The unit that was tested was a pilot scale Knelson Continuous Variable Discharge (CVD6) Concentrator. The primary objective was to determine the effects of the machine operating variables on separation performance; concentrate grade and recovery. The secondary objective was to use the results to develop an operating strategy for the concentrator. Thirdly, in testing the machine the practical limits of the equipment were determined in order to develop a basic understanding of where this technology could be applied commercially. To achieve these objectives four sets of pilot scale experiments were conducted including: 1. Quartz/magnetite statistical experimental design 2. Quartz/magnetite incremental testing 3. Synthetic sphalerite/quartz incremental testing 4. Pb/Zn flotation tailings plant testing at Hudson's Bay Mining and Smelting Statistical experimental design was used to rank the effects of operating variables on concentrator grade and recovery. The following table lists the operating variables in order, from most significant to least significant: [Table omitted] The first stage of research in evaluating the operating variables of the CVD was to evaluate the feed and machine variables using a statistical experimental design approach. This methodology was selected because of the large number of variables and was the only practical way to evaluate the individual variables and their interaction effects. A synthetic feed of quartz and magnetite was tested in a pilot plant that included a Knelson CVD6 concentrator. The result of the factorial design was a ranking of effects on both grade and recovery for each of the feed and machine variables. Testing of both synthetic quartz/magnetite and synthetic quartz/sphalerite resulted in a better understanding of the trends that result from incremental changes in operating variables. The plant testing at HBM&S created a large database of information that confirmed the information from the laboratory scale tests. Based on the results an operating strategy was developed that includes the following general strategy: • Identification of performance expectations • Testing to produce an array of results that span the spectrum of concentrator abilities • Identification of a performance boundary layer • Qualitative tuning of operating variables to approach boundary layer conditions • Fine tuning of operating variables using knowledge of the impact of individual operating variables Combining information from all of the test programs, the effect of particle specific gravity differential was investigated. The result was that the CVD was shown to be able to separate particles down to a specific gravity differential of 0.2. However, the practical limitation where a reasonable recovery was obtained was a differential of 2.

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