Rationale for the temperature regime of the foam separation cycle

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The research objective is to determine the optimal temperature regimes for slurry preparation and foam separation of diamond-bearing kimberlites to ensure maximum diamond recovery under high selectivity of the process. Methods of research include the electron probe X-ray spectral analysis, IR spectrophotometry, and measurement of the contact angles of a collecting agent drop on diamonds or minerals. Technological studies were carried out on the setup for foam separation. Research results. It was shown that when the feedstock of the foam separation cycle is heated to a temperature of 80–85 °C the diamonds are effectively purified from hydrophilic coatings, which leads to the restoration of their natural floatability. Through contact angles measurement, the temperature range of 30–40 °C was determined in the feedstock reagent conditioning operation. It is shown that the maximum water repellence of diamonds is achieved in this temperature range without a significant increase in the kimberlite minerals water repellence. Laboratory experiments have shown that the best foam separation results are achieved when in the conditioning operation the feedstock with flotation reagents is maintained at a temperature of 30–38 °C. The flotation studies using F-5 bunker fuel oil as base collecting agent, as well as its compounds with diesel fraction and Machchobinsky oil, determined the optimal temperature of 14–24 °C directly in the process of foam separation. After data analysis, a temperature regime was proposed and tested, which includes the foam separation feedstock heating before the operation of slurry removal and conditioning with flotation reagents up to 85 °C and the subsequent use of accumulated heat in the operations of foam separation feedstock conditioning (30 °C) with reagents and the foam separation process itself (18 °C). The prospects of the technology. The test results of the selected temperature regime for the foam separation process on a test bench show the possibility of increasing the diamonds recovery into the concentrate by 2.3–4.5% when using applied and potential collecting agents, including F-5 bunker fuel oil and compounds based on it. The developed regime is recommended for commercial development in the foam separation cycle at Alrosa processing plants.