Simulation of the kinetics of the autoclave dissolution of copper and nickel sulfides in the presence of oxygen

Kinetic regularities of the oxidative autoclave dissolution of iron, copper, and nickel sulfides when leaching the ore of the Shanuch deposit are investigated in controllable experimental conditions. It is shown that the dissolution rate of sulfides is limited by the oxygen absorption. © 2013 Allerton Press, Inc

Mechanism of sorption equilibrium in the recovery of zinc, calcium, and magnesium from waste water by the use of iminodiacetate resins

A study is made of the laws that govern the sorptive equilibrium of zinc, calcium, and magnesium in aqueous solutions on iminodiacetate commercial resin Lewatit TP 207. The relations that are obtained show that the cation sorption process is described by the Langmuir and Freundlich models. The selectivity series Zn2+ > Ca2+ > Mg2+ was established based on determination of the affinity constants in the corresponding equations. Thus, the resin can be used to remove zinc cations from waste water even when it contains high concentrations of hardness ions. © 2013 Springer Science+Business Media New York

Hydrothermal Treatment of Arsenopyrite Particles with CuSO4 Solution

The nature of the hydrothermal reaction between arsenopyrite particles (FeAsS) and copper sulfate solution (CuSO4 ) was investigated in this study. The effects of temperature (443–523 K), CuSO4 (0.08–0.96 mol/L) and H2 SO4 (0.05–0.6 mol/L) concentrations, reaction time (1–120 min), stirring speed (40–100 rpm) and particle size (10–100 µm) on the FeAsS conversion were studied. The FeAsS conversion was significant at >503 K, and it is suggested that the reaction is characterized by the formation of a thin layer of metallic copper (Cu0 ) and elemental sulfur (S0 ) around the unreacted FeAsS core. The shrinking core model (SCM) was applied for describing the process kinetics, and the rate of the overall reaction was found to be controlled by product layer diffusion, while the overall process was divided into two stages: (Stage 1: mixed chemical reaction/product layer diffusion-controlled) interaction of FeAsS with CuSO4 on the mineral’s surface with the formation of Cu1+ and Fe2+ sulfates, arsenous acid, S0, and subsequent diffusion of the reagent (Cu2+ ) and products (As3+ and Fe2+ ) through the gradually forming layer of Cu0 and molten S0; (Stage 2: product layer diffusion-controlled) the subsequent interaction of CuSO4 with FeAsS resulted in the formation of a denser and less porous Cu0 and S0 layer, which complicates the countercurrent diffusion of Cu2+, Cu1+, and Fe2+ across the layer to the unreacted FeAsS core. The reaction orders with respect to CuSO4 and H2 SO4 were calculated as 0.41 and −0.45 for Stage 1 and 0.35 and −0.5 for Stage 2. The apparent activation energies of 91.67 and 56.69 kJ/mol were obtained for Stages 1 and 2, respectively. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Funding: This work was funded by State Assignment, grant number № 075-03-2021-051/5

Effect of preliminary alkali desilication on ammonia pressure leaching of low-grade copper–silver concentrate

Ammonia leaching is a promising method for processing low-grade copper ores, especially those containing large amounts of oxidized copper. In this paper, we study the effect of Si-containing minerals on the kinetics of Cu and Ag leaching from low-grade copper concentrates. The results of experiments on the pressure leaching of the initial copper concentrate in an ammonium/ammonium-carbonate solution with oxygen as an oxidizing agent are in good agreement with the shrinking core model in the intra-diffusion mode: in this case, the activation energies were 53.50 kJ/mol for Cu and 90.35 kJ/mol for Ag. Energy-dispersive X-ray spectroscopy analysis (EDX) analysis showed that reagent diffusion to Cu-bearing minerals can be limited by aluminosilicate minerals of the gangue. The recovery rate for copper and silver increases significantly after a preliminary alkaline desilication of the concentrate, and the new shrinking core model is the most adequate, showing that the process is limited by diffusion through the product layer and interfacial diffusion. The activation energy of the process increases to 86.76 kJ/mol for Cu and 92.15 kJ/mol for Ag. Using the time-to-a-given-fraction method, it has been shown that a high activation energy is required in the later stages of the process, when the most resistant sulfide minerals of copper and silver apparently remain. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.Russian Science Foundation, RSF: 0836-2020-0020Funding: This work was financially supported by the Russian Science Foundation Project No. The SEM-EDX analyses were funded by State Assignment, grant number 0836-2020-0020

УрФУ И УГМК – МНОГОЛЕТНИЙ СОЮЗ УЧЕНЫХ И ПРОИЗВОДСТВЕННИКОВ

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Lignosulfonate, anionic surfactants and their mixtures influence on water solutions surface tension and zinc concentrate pressure leaching

The formation of elemental sulfur during sulfide concentrate pressure leaching leads to the appearance of sulfur-sulfide granules, which significantly reduces zinc dissolution rate. The solution for this problem was the use of surfactants, which prevents the negative effect of molten sulfur, avoiding the granule formation during leaching. Lignosulfonates (waste from the woodworking industry) are most often used as reagents for sulfide concentrate pressure leaching. Influence of individual and mixtures of surfactants on surface tension of aqueous solutions, zinc extraction and size-grade distribution of cakes after sulfide zinc concentrate pressure leaching. Surface tension of aqueous solutions was analyzed by stalagmometric method. Leaching was performed in titanium autoclave in presence of lignosulfonate, sodium dodecylbenzenesulfonate and sodium dodecylsulfate. Solutions after leaching were analyzed on zinc by atomic absorption spectroscopy. Size-grade analysis of cakes after leaching was carried out by laser diffraction particle size analyzer. In this work, synergetic influence was observed of anionic surfactants and lignosulfonate on decreasing of aqueous solutions surface tension. The best results were obtained when LS-SDBS mixture was used, namely in the range of sodium dodecylbenzenesulfonate concentrations 400-600 mg / l. Usage of combined surfactants allowed to achieve high rates of zinc extraction and optimal particle size of cakes after leaching. At Ls and SDBS using zinc extraction was increased from 77,2 % up to 82,8 %, with the bulk of the cake (96,7%) having a particle size of-150 μm. Combined surfactants usage (lignosulfonate and sodium dodecylbenzenesulfonate) can be recommended for applying at pressure leaching of sulfide zinc concentrates. © Published under licence by IOP Publishing Ltd.Leaching experiments and grade size analysis were conducted at the expense of the Russian Science Foundation grant (project No. 18-19-00186)

Pressure oxidation of arsenic (Iii) ions in the h3aso3-fe2+-cu2+-h2so4 system

The processing of low-grade polymetallic materials, such as copper–zinc, copper–lead– zinc, and poor arsenic-containing copper concentrates using hydrometallurgical methods is becom-ing increasingly important due to the depletion of rich and easily extracted mineral resources, as well as due to the need to reduce harmful emissions from metallurgy, especially given the high content of arsenic in ores. Ferric arsenates obtained through hydrothermal precipitation are the least soluble and most stable form of arsenic, which is essential for its disposal. This paper describes the investigation of the oxidation kinetics of As (III) ions to As (V) which is required for efficient puri-fication of the resulting solutions and precipitation of low-solubility ferric arsenates. The effect of temperature (160–200 °C), the initial concentration of Fe (II) (3.6–89.5 mmol/dm3), Cu (II) (6.3–62.9 of mmol/dm3) and the oxygen pressure (0.2–0.5 MPa) on the oxidation efficiency of As (III) to As (V) was studied. As (III) oxidation in H3AsO-Fe2+-Cu2+-H2SO4 and H3AsO-Fe2+-H2SO4 systems was controlled by a chemical reaction with the apparent activation energy (Ea (≈84.3–86.3 kJ/mol)). The increase in the concentration of Fe (II) ions and addition of an external catalyst (Cu (II) ions) both have a positive effect on the process. When Cu (II) ions are introduced into the solution, their catalytic effect is confirmed by a decrease in the partial orders, Fe (II) ions concentration from 0.43 to 0.20, and the oxygen pressure from 0.95 to 0.69. The revealed catalytic effect is associated with a positive effect of Cu (II) ions on the oxidation of Fe (II) to Fe (III) ions, which further participate in As (III) oxidation. The semi-empirical equations describing the reaction rate under the studied conditions are written. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.This work was financially supported by the Russian Science Foundation Project No. 20‐ 79‐00321

РАСЧЕТ РЕАКТОРА ДЛЯ ИЗВЛЕЧЕНИЯ ТРЕХВАЛЕНТНОГО МЫШЬЯКА ПО СУЛЬФИДНОЙ ТЕХНОЛОГИИ

The accumulation of arsenic in solid, liquid and gaseous waste of metallurgical production is an acute problem. Deposition of arsenic by sodium hydrosulfide is an effective and fast method of arsenic removal from solutions. The paper proposes a reactor design procedure for extraction of As (III) using the sulfide technology from washing solutions for wet gas scrubbing in sulfuric acid production. The paper takes into consideration the optimum parameters for removal of arsenic from solutions: the specific consumption of sulfide sulfur per1 kgof arsenic, the concentration of As (III) ions in the solution, the rate of sodium hydrosulfide feeding into the solution, and the hydrodynamic regime of the reactor. The obtained results are useful for design of experimental-industrial reactors used in dearsenication of solutions.Накопление мышьяка в твердых, жидких и газообразных отходах металлургического производства является острой проблемой. Осаждение мышьяка гидросульфидом натрия – эффективный и быстрый метод удаления мышьяка из растворов. Предложена методика расчета реактора для извлечения As(III) по сульфидной технологии из промывных растворов мокрой очистки газов сернокислого производства. Учтены оптимальные параметры для удаления мышьяка из растворов: удельный расход сульфидной серы на 1 кг мышьяка, концентрация ионов As(III) в растворе, скорость дозировки гидросульфида натрия в раствор, гидродинамический режим работы реактора. Полученные результаты полезны для проектирования опытно-промышленных реакторов в цикле очистки растворов от мышьяка