Technological efficiency of methods for modifying the properties of ferrosilicium and water systems in the processes of dense medium separation of difficult-rated diamond-containing material

Introduction. Taking into account the results of experimental bench studies previously carried out at ICEMR RAS on the effectiveness of the use of physical, physico-chemical and electrochemical influences to increase the corrosion resistance of ferrosilicon in the technology of DMS of diamond-containing raw materials of weakly altered kimberlites of the primary deposits of the Mirny ore field, at this stage, their pilot industrial testing was carried out under processing conditions intensively altered ores of deep horizons with the involvement of alluvial and technogenic deposits in the processing of diamond-containing raw materials. Research methods. In accordance with the testing methodology, the tests were carried out in two directions, the ultimate task of which was to create process conditions that ensure the protection of ferrosilicon granules from corrosion destruction caused by their oxidation upon contact with corrosive aqueous systems: 1. Modification of the properties of the liquid phase of the ferrosilicon suspension to values that reduce its corrosiveness towards the surface of ferrosilicon granules (variable factor – properties of the aqueous process medium). 2. Modification of the surface properties of ferrosilicon granules by creating a protective shell on it, preventing their oxidation during contact with corrosive aqueous systems (the variable factor is the surface of the ferrosilicon used: original and coated). Research results. The article presents the results of pilot industrial tests of technical solutions, the implementation of which made it possible to reduce the consumption of ferrosilicon in the dense medium separation cycle of diamondcontaining material using the above methods for modifying the properties of the aqueous medium and ferrosilicon used for the preparation of the ferrosilicon suspension, by increasing the corrosion resistance of the components of the ferrosilicon suspension. Discussion of research results. A comparative assessment of the technological efficiency of the applied methods for modifying the properties of the aqueous phase and ferrosilicon under experimental test conditions was carried out with the determination of ferrosilicon losses in the regeneration cycle of the ferrosilicon suspension and its content in the volume of the ferrosilicon suspension. The use of electrochemically treated water as a reagent for modifying the properties of the components of a ferrosilicon suspension provides a reduction in ferrosilicon consumption by 1.9 times, but is limited by the fairly high power consumption required for processing large volumes of water in the DMS process. The use of inert nitrogen gas as a bubbling agent instead of oxygen-containing air in the ferrosilicon suspension preparation cycle reduces ferrosilicon consumption by 2.5 times while increasing its service life by 1.5 times. However, the use of this method is limited to use only in part of the DMS process – the cycle for preparing a ferrosilicon suspension. The use of the method of nitriding ferrosilicon granules ensures a reduction in ferrosilicon losses by 2.7 times while increasing its service life by 2.2 times. At the same time, the entire volume of ferrosilicon in the process retains its anticorrosion properties in relation to the corrosive components of the surrounding water system. Conclusion on the article. A comparative analysis of the results obtained using mathematical processing methods has established the maximum technological efficiency of using the method of nitriding the surface of ferrosilicon, which causes the creation of a protective nitride layer on it, ensuring high corrosion resistance of ferrosilicon granules under the conditions of active processes of dense medium separation of diamond-containing raw materials of the material composition under consideration. Nitrided ferrosilicon has parameters that make it possible to increase its service life by no less than 2.2 times while reducing losses in the regeneration cycle by 2.7 times. Suggestions for practical applications and directions for future research. The experimentally established advantages of the technological efficiency of using nitrided ferrosilicon in DMS processes of diamond-containing raw materials are recommended for industrial implementation in the conditions of ALROSA’s processing plants and can be used in similar schemes for dense medium separation of mineral raw materials of various compositions. Tests are planned under industrial conditions at one of the processing plants of PJSC ALROSA.