Elena A. Shchelokova

In this work, we investigate V(V) sorption on amorphous and modified silica. Silicon dioxide was obtained from the metallurgical slag. The impact of modification on vanadium sorption was studied. The surface was modified with hydrazides (HDs) and dimethylhydrazides (DMHDs) of the tertiary carbonic Versatic acids CH₃R₁R₂CC(O)OH of the C_10–19 fractions. The optimal sorption conditions on the unmodified sorbent were pH 4, 1 h, and 40 °C. The sorption capacity of V(V) ions increased with surface modification. For modified sorbents, the range of action shifted to a more acidic area (2.0–3.0), where the HV₁₀O₂₈⁵⁻ polyanion formed a complex with N′,N′-dimethylhydrazide groups. When studying the kinetics of the V(V) sorption process on silica samples, the optimum time of adsorption equilibrium establishment (10 min) and reaction mechanism were determined. The sorption process was significantly accelerated by surface modification. The vanadium sorption process is described by pseudo-second-order kinetics. The study of adsorption isotherms revealed that the vanadium sorption isotherm corresponds to the Langmuir equation. The differences in the extraction of vanadium ions are explained by different sorption mechanisms, which are associated with the variety of vanadium forms in the solution.

In the production of abrasive materials from metallurgical slags, fine waste with a size of less than 40 microns is produced, which contains valuable components. Unlike slag, this waste does not need to be pulverized for processing, which greatly simplifies the process. However, without silica extraction, it is impractical to carry out waste treatment. The authors of the work considered the possibility of obtaining silicon dioxide from abrasive wastes of Rezh, Orsk and Kyshtym, containing up to 20,7 % of silicon, up to 31,7 % of iron and up to 0,7 % of the sum of nickel and copper. Sulfuric acid treatment of waste produced a solution containing magnesium and iron (II) sulfates and silicic acid. It was found that during processing of Orsk wastes the degree of components extraction is significantly lower in comparison with Rezh and Kyshtym wastes 24,5, 67,8 and 59,3, respectively. The obtained solution is used to produce silica powders by dehydrating it. The dried mixture is subjected to aqueous washing of metal sulfates. As a result, samples with high specific surface area in the range of 387,6 to 841,5 m2/g were obtained. The average pore size is 2,3–3 nm, which allows us to attribute these silicas to mesoporous silica. SiO2 content in the samples reaches up to 98 %. Samples of silicon dioxide from abrasive materials were compared with that obtained from metallurgical slag of Pechenganickel Combine and have similar parameters. The obtained insoluble leaching residue contains concentrate of non-ferrous metals and according to X-ray data it consists of calcium sulfate, so after separation of non-ferrous metals it can be used in construction industry.

This work proposes an environmentally safe and economically feasible method of waste copper-nickel production slag utilization (Kola Mining-Metallurgical Company, Nornickel, Kola Peninsula, Russia). This process involves the decomposition of slag by diluted solutions of sulfuric acid (7–10 wt.% H₂SO₄) with a transfer in a solution of more than 70% silicon, 77% iron and 78% magnesium, and a concentration of non-ferrous metals in the residue (~70%). Copper ions were used in the leaching stage to prevent the release of hydrogen sulfide into the working atmosphere. Dehydration of the solution, followed by washing of water-soluble sulphates from silica, was carried out to separate silica from the leaching solution. The dehydration temperature effect on the silica structural characteristics was determined. The possibility of recovering non-ferrous metals from solutions after silica extraction by precipitation, in the form of copper cementite, and the sum of nickel and cobalt sulfides, was evaluated. Pigment-grade iron dioxide, magnesium sulphate and aluminium hydroxide were obtained by dehydration of the solution after extraction of base metals, calcination and other operations. Sulfuric acid leaching resulted in the disclosure of sulfide grains encapsulated in ferrosilicate, which is a favorable factor for flotation. The depleted residue can be successfully used in the construction industry.

The paper presents data on obtaining valuable metal salts from the spent copper electrolyte. During its treatment, it is possible to produce copper, zinc sulfate solution, iron(III) oxide, nickel carbonate, and dilute sulfuric acid.

The possibility of hydrometallurgical processing of converter slag from nickel production aimed at integrated use of mineral raw materials and environmental protection is shown. The scheme of hydrometallurgical processing of slag using hydrochloric acid is proposed. The method involves leaching the slag with hydrochloric acid in the presence of ferric ions. The high values of iron and nonferrous metals extraction into the leaching solution are achieved during hydrochloric acid leaching. Silicon is concentrated in an insoluble residue. Liquid extraction was used to extract iron from hydrochloric acid leaching solutions. Silica-containing residues can be successfully used in the construction industry.

The article presents studies on the extraction of iron from chloride solutions with aliphatic alcohols, ketones, and their mixtures. Dilution of 1-octanol with an inert aromatic diluent to a concentration of 80 vol.% led to an increase in its extraction capacity, while the extraction capacity of 2-octanone has decreased with dilution. A synergistic effect was found for a 1-octanol/2-octanone mixture, the maximum of extraction was observed at a ketone concentration of 80 vol.%. The effect of a mixture composition and chloride ion concentration on the iron extraction degree was studied. McCabe-Thiele results indicated that at Fe(III) concentration in the aqueous phase 9.32 g∙dm⁻³, it is possible to extract iron(III) quantitatively using a mixture of alcohols C₈+C₁₀ (70 vol.%) and 2-undecanone (30 vol.%) after three extraction stages. Stripping of Fe(III) from the mixture was done with distilled water. After the stripping, the loaded Fe(III) concentration in the organic phase was reduced from 27 g∙dm⁻³ to −3 for 3 stages. The conditions were tested in continuous mode at a cascade of laboratory extractors. During the tests on the cascade, the low solubility of the mixture of ketone with alcohol was established, and the concentrated solution of ferric chloride was obtained.

A new solvent impregnated sorbent containing trioctylphosphine oxide was prepared using carriers from mesoporous silica, obtained by hydrometallurgical processing of Kola Mining-Metallurgical Company (Kola MMC, Russia) dump slag waste. The characterization of sorbent was performed using the SEM, FTIR and TGA techniques. Under static conditions, an sorption of rhenium onto impregnated sorbent in sulfuric acid solution was studied in a batch system with respect to contact time, sulfuric acid concentration, solid to liquid ratio and initial rhenium concentration. The recovery of rhenium from a sulfuric acid wash solution of the Kola MMC was demonstrated.

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.