PHYSICOCHEMICAL AND ELECTROCHEMICAL METHODS FOR MODIFYING THE PROPERTIES OF DIAMONDS AND ORE PULP COMPONENTS DURING THE SEPARATION OF DIAMOND-BEARING KIMBERLITES

The main deposits of kimberlite ores located in the regions of Western Yakutia are enriched at the ALROSA diamond extraction factories using a similar technology, in which the maximum completeness of extraction and safety of diamond crystals is ensured by the stages of schemes. The bulk of diamond crystals is extracted in the processes of heavy medium, sticky and foam separation, the effectiveness of which is determined by the properties of diamonds, kimberlite minerals and the media separating them. The article presents the results of theoretical and experimental studies carried out by ICEMR RAS together with the largest universities in Russia, scientific and industrial enterprises of ALROSA. It is shown that the use of combined energy methods of destruction and removal of hydrophilizing formations on diamond crystals provides hydrophobization of their surface in the processes of sticky and foam separation. It has been established that the efficiency and economic indicators of the process of dense medium separation of diamond-containing raw materials are due to the stability of the technological properties of the weighting agent of the ferrosilicon medium and the suspension prepared on its basis. The method for modifying the corrosion resistance of ferrosilicon by nitriding its surface has been substantiated and tested. The proposed method makes it possible to create a protective shell on the surface of the granules, preventing their destruction upon contact with corrosive components of the water-air environment. Semi-industrial tests have established the possibility of increasing the extraction of diamonds into concentrates for sticky and foam separation by 4 and 5.2%, respectively. The results of laboratory tests have confirmed the possibility of reducing the corrosion rate of ferrosilicon by 5-6 times in the process of dense medium separation.

Intensification of diamond purification from hydrophilic minerals in foam separation process

The reason for diamond loss in foam separation process consists in the fact that the diamond crystals fed to the foam separation are coated with hydroxides and carbonates. A combined method to restore the diamond hydrophobicity through thermal and electrochemical destruction of the mineral coat was proposed. This method provides for the conditioning stage in the foam separation process to enable decreasing the amount of the minerals coating diamonds surface from 3 to 10 times. Technological research showed that using products of diaphragm less electrolysis of recirculating water, with the thermal treatment of the foam separation feed enables increasing the recovery of diamonds in the foam separation concentrate from 76.5% to 83.7%.

Study on the Extraction Technology of Candida antarctica Lipase B by Foam Separation

Candida antarctica Lipase B (CALB) has a wide range of applications in many fields. In this study, Pichia pastoris was used to express CALB for fermentation tank culture. Sodium dodecyl sulfate (SDS) was used as a surfactant, and foam separation technology was used to explore the best experimental conditions for the harvest of CALB. The results showed that the optimal technological conditions for the foam separation and recovery of CALB were as follows: liquid volume was 150 mL, separating gas velocity was 600 mL/min, pH value was 7, and surfactant SDS concentration was 0.5 mg/mL. Under these conditions, the enrichment ratio of CALB was 0.95, and recovery rate R was 80.32%, respectively, indicating that the foam separation technology is feasible to extract lipase B.