Zh. E. Yakhiyaeva

Samples of gel-type cation exchangers of the TOKEM nomenclature were tested for lithium extraction from multicomponent natural brines. The dependencies of the extraction of Li and other impurities—Na, Ca, and Mg—on the duration of the sorption process for the tested ion-exchange resins under static conditions are presented. Metal ions can be arranged according to the degree of extraction for each ion exchanger in a row: Ca²⁺ < Mg²⁺ < Li⁺, Na⁺. Testing of ion exchangers under static conditions on technological Li-containing solutions confirms the applicability of TOKEM-140 and TOKEM-160 cation exchangers for lithium extraction. For TOKEM-140, lithium extraction over time varies from 76.2% to 73.8% and for TOKEM-160—from 73.8% to 72.4%. The ionic background of natural brines has a significant effect on the capacity of ion exchangers for lithium and forms the following series Li⁺ << Mg²⁺ < Ca²⁺ << Na⁺ relative to the obtained concentrations of metal ions in natural brine. The overlay of IR spectra of TOKEM-140 and TOKEM-160 ion exchangers before and after saturation shows slight changes in their appearance, indicating that the lithium sorption process has occurred. The values of static exchange capacity (SEC) for TOKEM-140 and TOKEM-160 cation exchangers are identical.

We investigated the electrochemical processing of technogenic wastes of rhenium-containing heat-resistant nickel alloys in the form of large scrap pieces of turbine blades in sulfuric acid solutions. By 80–90% of rhenium can be converted into the solution during the anodic dissolution of compact pieces of these alloys in sulfuric acid solutions with nitric acid addition under a direct current of 500–1000 A/m2 with a temperature of 25–30 oC. A high recovery of cobalt, chromium, aluminum and slightly less nickel in solution is also observed under these conditions. Tungsten, tantalum, hafnium and most part of molybdenum pass into the anode slime almost completely. When the anode slime is chemically processed in sulfuric acid solutions with additives of hydrogen peroxide or nitric acid, some part of rhenium, nickel and cobalt in the slime is transferred to the solution. Rhenium (crude ammonium perrhenate, where rhenium content is not less than 68.9 wt. %) is recovered from the combined solution after anodic processing of alloy wastes and chemical dissolution of anode slimes by a known solvent extraction method. The cake, remaining after chemical processing of anode slimes, is a concentrate of refractory rare metals containing up to 39–42% W; 15–18% Ta and 3–4% Hf. A nickel-cobalt concentrate with a content of 31.5% Ni and 4.8% Co is precipitated by sodium hydroxide after rhenium extraction from the sulphate raffinate containing significant amounts of nickel, cobalt, chromium and aluminum. The carried out studies offered a principal technological flowsheet for processing of large pieces of wastes of rheniumcontaining heat-resistant nickel alloys. The flowsheet includes anodic dissolution of wastes with a direct current in sulfuric acid solutions and the production of crude ammonium perrhenate, a concentrate of refractory rare metals and nickel-cobalt concentrate from the products of electrolysis. Investigations were carried out according to the Grant of the Ministry of Education and Science of the Republic of Kazakhstan No.4351/ГФ4.

The oxidation of cobalt and nickel nanopowders in air and under heating are investigated. Nanopowders are obtained by the chemical deposition of hydroxides from salt solutions with their subsequent reduction in hydrogen flow at various temperatures. Their pyrophoricity is determined.