Materials Science Forum Vol. 946

Abstract: This article presents a study of Tomtor rare earth ore decomposition. This material contains a lot of valuable components such as REE and niobium (mas., %: 12,8 ΣREO (rare earth oxides), 0.039 Sc, 18.4 P₂O₅, 9.9 Fe, 9.0 Al, 0.24 ThO₂, 8.2 Nb₂O₅). The study aims to find efficient ways of processing this deposit. Technologies using the sulfuric acid as the main reagent to leach are described in this article. Investigation has three trends. The first trend is agitation leaching at low sulfuric acid concentrations, temperatures up to 95 °C and atmospheric pressure. The second trend is pressure leaching at low sulfuric acid concentrations, high temperatures (up to 180 °C) and high pressure. The third trend is high temperature sulfatization with concentrated sulfuric acid at elevated temperature (up to 180 °C) and atmospheric pressure followed by aqueous leaching. The dependence of target components (rare earth elements, scandium, phosphorus) and the impurity (iron, aluminum, thorium) extractions into solution from major factors was studied.

Abstract: The problem of copper leaching from copper-electrolyte slimes is discussed. To intensify the long and costly process, it is proposed to use a leaching system containing sulfuric acid and hydrogen peroxide as an oxidizing agent. The chemical transformations possible variants at the treatment of slime under the specified conditions and the thermodynamic parameters of the predicted reactions are considered. Solution composition effect on the copper dissolution rate at room temperature was studied in the presence of hydrogen peroxide using the rotating disc technique. It is found that dissolution rate constant at using hydrogen peroxide slightly inferior to dissolution rate constant under autoclaved conditions in an oxygen atmosphere.

Abstract: The problem of processing slimes of galvanic production, formed as a result of neutralization of technological solutions and wastewater containing heavy non-ferrous metals is considered. At present, sludges are transported to disposal area and are not used in any way. Typically, such sludges contain significant amounts of chromium and nickel, which creates environmental hazard. Investigated sludge of Dimitrovgrad Automobile Units Plant (Russia) contains up to 6.6% Ni and up to 7,4% Cr. The hydrometallurgical process is proposed to treatment of these sludges. Solutions of sulfuric acid, ammoniaс chloride and Trilon B were used as lixiviants. It is shown that when using a solution of sulfuric acid with pH=1,5, extraction of up to 93,3% Cu, 70,2 Ni, 90,3 Zn is achieved.

Abstract: The known designs of tank for precipitation of aluminum hydroxide from sodium aluminate solution, used in the production of alumina are considered, and the improvement of the design of the precipitator with mechanical mixing is proposed, which allows to intensify the process of precipitation and to avoid strong caustic module of the solution changes.

Abstract: The efficiency of iron oxy-hydrate application for cleaning aqueous media from arsenic has been studied. It is proposed to precipitate the active layer to a coarse-grained carrier to improve filterability. Metallurgical alumina and quartz sand are considered as carrier materials. Conditions for the synthesis of inorganic sorbent based on iron oxy-hydrate are established. The dependence of the sorbent capacity on the pH of the solution is determined. IR spectra of the sorbent before and after sorption of arsenic are given, and the mechanism of sorption of arsenic is proposed. The data on the capacity of the obtained sorbent modifications for the sorption of As (III) ions under static conditions are presented.

Abstract: Low grade copper concentrate, composed mainly of plagioclase, quartz, pyrite, chlorite, chalcopyrite, glauconite, is a promising source for the future recovery of copper and other valuable components, which processing by existing methods are not economical. An alkali pressure leaching method, followed by acid leaching for extraction of aluminum and silica from such low-grade copper concentrate with the aim to enrich other valuable metals content, was explored in this research. The samples were characterized by using wet chemical analysis and X-ray diffraction. An alkali pressure leaching, followed by dilute acid leaching for enrichment of low-grade copper concentrate, allows to extract in a solution of 90,4% Si, 83.82% Al and 7.73% of Cu with the following optimal parameters: NaOH/concentrate-1 mass ratio = 65%, alkali leaching temperature = 240 °C, the alkali leaching time = 90 min. The content of copper in the final concentrate was 19.17%. Consequently, the technology of processing of low-grade copper raw materials is proposed, that allows to increase the comprehensiveness of raw materials usage.

Abstract: At present, arsenic content in copper concentrates is increasing, which leads to an increase in its content in all smelting products, the largest amount of arsenic is transferred in fine dust (dust composition,%: 10-12 Zn, 11-13 Pb, 8-15 Cu , 12-14 Fe, 5-10 As). Autoclaved leaching of dusts (temperature 160-200 °C, oxygen pressure 0.4-0.8 MPa, molar ratio H₂SO₄ /(Cu + Zn) = 0.75-2.25) to obtain a copper-zinc solution and a cake containing arsenic, iron and lead was studied. Copper extraction in the solution reaches 92%, zinc 95%. Lead, arsenic and iron are concentrated in the cake. Lead from cake is extracted by leaching in sodium chloride solution (temperature 60-70 ° C, NaCl concentration 300 g / dm³). The extraction of lead into the solution is 95%, subsequently lead is precipitated as lead carbonate.

Abstract: The importance of the research is due to the lack of potable water (~1.6 million m³ per year) in a rapidly developing city in the Urals. One way to solve this problem is to purify water from the spent copper mine with a debit of ~4.4 million m³ of water per year. The most advanced techniques recently used for obtaining drinking water of a high quality are based on ion exchange and reverse osmosis, which can ensure an obtainment of water with initial contents of impurities much below the maximum permissible values. Based on the real experience the article compares sorption and membrane technologies in terms of water purification efficiency and cost of potable water production. The large-scale tests of mine water purification were carried out at sorption and reverse osmosis pilot plants with the capacity of 1 m³ per hour for the incoming flow. The source water had the following composition, mg/dm³: 0.5–0.9 Mn; 1.0–1.7 Ni; 80-140 Ca; 30-40 Na; 40-70 Mg; 0.2–0.6 Cu; 8.1–9.5 Si; 0.01–0.03 Zn; 0.01–1.70 Fe; <0.01 Al; < 0.005 As; < 0.005 Pb. At the same time the salinity was 640–680 mg/dm³, the water hardness was 9.5–11.5 mmol/dm³ and pH was 7.0-7.5. The content of non-mentioned impurities was below the detection limit. The resulting treated water met the requirements for the quality of potable water for both purification techniques. It was concluded, that the best option for treatment of mine water is ion exchange.

Abstract: The article discusses the features of the casting process of non-ferrous metals, the basic properties of various alloys, affecting the appearance of various defects of the resulting casting. The proposals to improve the efficiency of the casting of non-ferrous metals in metal molds and specific recommendations for improving the performance properties of metal depending on the melt being poured are given.

Abstract: The authors studied the possibility of modifying aluminum-silicon alloys using titanium dioxide at standard melting temperatures up to 800 °C. The result is achieved due to the combined use of titanium dioxide and alkali and alkaline-earth metal fluorides. Calculations of the change in the Gibbs energy of chemical reactions of interaction of titanium dioxide with aluminum, cryolite, barium fluoride were carried out. The thermodynamic possibility of modifying silumin by the reduction of titanium from dioxide in the presence of additives selected was shown. Experimental melting was carried out and the results of mechanical tests of experimental alloys depending on the additives used were obtained. After melt treatment using the study combinations, the alloy structure becomes partially modified, which increases the mechanical properties of silumin.