E. K. Kopkova

According to the explored reserves of titanium ores, Russia holds the second place in the world (China holds the first place). Titanium ores are strategic raw materials: 20 deposits were explored and evaluated, and balance reserves were accounted in 13 of them. The Gremyakha-Vyrmes deposit, located at the Kola Peninsula, is one of the most prospective and largest native deposits of highquality titanium-magnetite-ilmenite ores. Ilmenite is the main mineral for production of metallic titanium, dioxide, carbide and other titanium-based compounds. Ilmenite belongs to hardly-opened minerals: either pyrometallurgical or hightemperature hydrometallurgical methods are applied for its decomposition. Preliminary mechanical activation is one of the methods for intensification of raw material processing. It leads to deformation and change of surface characteristics of minerals and improves their reaction ability. We investigated the influence of mechanical activation duration of the specific surface, structure of particles and morphology of ilmenite’s surface layer. We also considered the possibility of decomposition of activated ilmenite concentrate of the Gremyakha-Vyrmes deposit in sulphuric acid solutions with concentration of 750 g/l and the temperature range from 80 to 120 oC. We also investigated the influence of main technological parameters (duration of mechanical activation, concentration and consumption of acid, temperature) on efficiency of sulphuric acid process of ilmenite decomposition. Preliminary mechanical activation considerably intensifies the dissolution of iron and titanium in sulphuric acid as a result of decrease of activation energy in this process. We defined the duration of mechanical activation and conditions of sulphuric acid leaching, providing a high level of decomposition of ilmenite (>92%) and extraction of titanium (>94%) in solution.

The main physicochemical properties of the extracts, such as density, viscosity, and conductivity, as well as the mutual solubility of the phases in the ROH-H₂O and ROH-H₂O-H₃PO₄ extraction systems, where ROH (R = C₅–C₁₀) stands for higher monofunctional aliphatic alcohols with a different length and structure of the hydrocarbon radical, have been studied in water and aqueous solutions containing phosphoric acid. The properties correlate with the length and structure of the hydrocarbon chain in the aliphatic alcohols, as well as with the concentration of mineral acid in the extracts.

The interaction of Khibins titanomagnetite concentrate (TMC) with hydrochloric acid solutions has been investigated. The decomposition of TMC in the HCl solutions has been optimized using factorial experimental design. The main factors in the efficiency of TMC decomposition with hydrochloric acid and in metal extraction into the filtrate are the HCl concentration, HCl input, processing temperature, and reaction mixture stirring time. By varying the decomposition conditions, it is possible to control the selectivity of the process: in TMC decomposition at a high temperature and a high acid concentration and input (t = 95°C, C _HCl = 320−340 g/L, TMC (S): HCl (L) = 1: 10, τ = 4 h), the metals pass collectively into the solution with a large recovery factor (93–95%); at smaller values of the above parameters (t = 50−80°C, C _HCl = 200–220 g/L, S: L = 1: 6–7, τ = 2 h), TMC decomposition proceeds more selectively towards iron and vanadium leaching into the solution with the minimum possible leaching of titanium (<15%).

The process of the sulfuric decomposition of copper-nickel converter slags with the obtainment of solutions of nonferrous metals suitable for their further isolation and separation by liquid-liquid extraction by selective reagents is investigated. The process kinetics is studied and it is obtained that the sulfuric decomposition of the slag is characterized by a retarded reaction rate and effectively proceeds only at elevated temperatures (90°C), consumptions (S: L = 1: 10), and acid concentrations (400 g/l). It is shown that the solutions of sulfuric acid can be used for the isolation of the sum of nonferrous metals and iron from slag, and the process most effectively proceeds during the decomposition into two stages, for which the technological recycle solutions of the acting copper-nickel enterprise can be used, for example, copper sulfuric electrolytes.