Study on preparation and properties of zinc ferrite product by leaching from zinc calcine

An increase in the anthropogenic load on the environment, in particular, the pollution of water bodies by sewage containing heavy metal ions, leads to an active search for sewage treatment from hazardous carcinogens and toxicants. The use of ion exchange in the process of water purification is relevant. The processes of regeneration solutions processing are important for the creation of closed cycles of water use. The results of studies on the electrochemical processing of acidic regeneration solutions containing zinc and nickel ions are presented. It was shown that the use of a two-chamber electrolyzer effectively removed zinc and nickel ions from sulfuric acid regeneration solutions and concentrated sulfuric acid in the anode chamber. The dependence of the current output of heavy metals on the concentration of sulfuric acid in the cathode space and on the time of electrolysis was studied. It is established that the maximum output of nickel and zinc by current is achieved by decreasing the acidity in the cathode space to values ~ 50 mg-ekv / dm3. It is shown that the yield of nickel and zinc by current does not depend very much on the initial concentration of sulfuric acid in the initial solution. The results on the concentration of sulfuric acid are presented, depending on the time of electrolysis, the initial concentration of acid and heavy metals in the cathode space.

Reductive leaching of indium-bearing zinc ferrite in sulfuric acid using sulfur dioxide as a reductant

A new sodium chlorite – iodide – acetylacetone chemical oscillatory reaction has been studied by the UV-Vis spectrophotometric method. The initial concentrations of acetylacetone, sodium chlorite, iodide, and sulfuric acid and the pH value have great influence on the oscillation observed at a wavelength of 570 nm for the starch–triiodide complex. There is a pre-oscillatory or induction stage and the amplitude and number of oscillations depend on the initial concentration of the reactants. Equations for the starch–triiodide complex reaction rate change with reaction time and the initial concentrations in the oscillation stage were obtained. The induction time decreases linearly with the initial concentration of acetylacetone or sodium chlorite but increases linearly with the initial concentration of sulfuric acid. The oscillation reaction can be accelerated by increasing the reaction temperature. The apparent activation energies at the induction stage and the oscillation stage were 61.02 and 61.36 kJ/mol, respectively, indicating that the two stages have similar reaction mechanisms. Generating the enol isomer by keto–enol tautomerism is an important step to constrain the time of the induction period.

Gossan discarded from mining processes result in metal resource wastage, and its long-term stacking causes environmental hazards. Therefore, this article considers zinc-containing gossan as the research object. The ore was roasted to prepare primary zinc ferrite products and sulfuric acid leaching was performed for purification. Then, XRD analysis was performed to characterize the purified products. The results indicated that the effect of sulfuric acid concentration on the purification of the products was related to its zinc ferrite content. Furthermore, the effect of leaching temperature on the purification of zinc ferrite products was related to sulfuric acid concentration; the lower the sulfuric acid concentration, the more considerable the effect of leaching temperature. The conditions suitable for purifying the products through sulfuric acid leaching are as follows: sulfuric acid concentration of 140 g/L, liquid–solid ratio of 4:1, leaching temperature of 80 °C, leaching time of 120 min, and stirring speed of 300 rpm. This article determines the factors affecting the purification of zinc ferrite by sulfuric acid leaching along with the optimal purification conditions. The findings presented herein provide a theoretical foundation for the development of new processes for preparing zinc ferrite, which has considerable industrial application value.

Concerns have arisen regarding the high concentrations of sodium sulfate in wastewater resulting from the waste Li-ion battery wet recycling process. In addressing this issue, Bipolar electrodialysis was employed to desalinate high-concentration sodium sulfate and recover it as sulfuric acid and sodium hydroxide. The investigation encompassed various experimental variables, such as applied voltage (maintained at a constant level), feed solution concentration, the initial concentrations of sulfuric acid and sodium hydroxide, and volume ratio (F/A/B). Optimal conditions were determined by assessing water migration (%), the recovery rates (%) of sulfuric acid and sodium hydroxide, concentration of the recovered substances, process time, and energy consumption. A higher applied voltage was found to reduce process time while increasing energy consumption, with the 25 V condition considered preferable. When utilizing a high-concentration feed solution, energy consumption rises; however, it decreases per unit of processed solution, rendering a 1.30 M Na<sub>2</sub>SO<sub>4</sub> feed solution preferable. Increasing initial concentrations of sulfuric acid and sodium hydroxide substantially prolonged process time and increased energy consumption, emphasizing the advantage of commencing with low initial concentrations. Adjusting the volume ratio facilitated the concentration and recovery of sulfuric acid and sodium hydroxide with minimal impact on process time or energy consumption. Under the identified optimal conditions, the recovery of 1.70 M sulfuric acid and 2.44 M sodium hydroxide was achieved.

Influence and hydrolysis kinetics in titanyl sulfate solution from the sodium hydroxide molten salt method

Zinc ferrite, a by-product of zinc hydrometallurgy, is a typical secondary resource. This paper focuses on investigating the factors influencing the sulfuric acid leaching process of zinc ferrite and analyzes the leaching kinetics. The research indicates that the zinc leaching rates of both pure zinc ferrite and zinc ferrite within zinc calcine exhibit positive correlations with individual influencing factors. Moreover, a strong positive synergistic effect exists between leaching temperature and leaching time. The differential impact of various factors on the two zinc leaching rates lies in the interaction involving sulfuric acid concentration, where sulfuric acid concentration acts as a limiting factor for the zinc leaching rate from zinc calcine. Kinetic studies on zinc leaching revealed that the rate-controlling step for zinc leaching from pure zinc ferrite is the surface chemical reaction, with an apparent activation energy of 54.22 kJ/mol. At leaching temperatures of 55 °C, 85 °C, and 95 °C, the zinc leaching rate from zinc ferrite in zinc calcine showed high conformity with both the diffusion model and the surface chemical reaction model, suggesting that the leaching process may be influenced by both kinetic mechanisms at these temperatures.

Leaching kinetics of cobalt from the scraps of spent aerospace magnetic materials

Mechanism and kinetics study of sulfuric acid leaching of titanium from titanium-bearing electric furnace slag

In recent years, recovering zinc from zinc calcine with high iron has been a matter of discussion. In this paper, sulfuric acid leaching was carried out to assess the effect of several parameters on zinc and iron extraction in zinc calcine with high iron in which the grade of zinc and iron is 53.90% and 19.38%, respectively. Parameters, such as stirring speed, sulfuric acid concentration, liquid to solid ratio and leaching time, were investigated. The results show that leaching time has done nothing to the leaching rate, but has great influence on leaching efficiency. Liquid to solid ratio and sulfuric acid concentration have significant influence on leaching results, and stirring rate has not obvious influence on leaching results. Under the condition of 120g/L sulfuric acid, 6:1 liquid to solid ratio, 55°C leaching temperature and 120min leaching time, the recovery of zinc and iron is 82.24% and 9.64%, respectively. It is obvious that ZnO in zinc calcine is easy to dissolve in acidity solution, which shown in two aspects: high leaching rate and high leaching speed. ZnO can be dissolved entirely in sufficient sulfuric acid in 10min.

The influence of initial concentration of sulfuric acid, leaching temperature, leaching time and liquid-solid ratio on the dust of the flash smelting furnace was investigated.And the structure of the dust of the flash smelting furnace and leaching slag was characterized by X-ray diffraction (XRD).Results showed that the chemical forms of copper in the dust of the flash smelting furnace are mainly copper sulfate and copper ferrite.The copper sulfate is water-soluble, while the copper ferrite is difficult to leach even under high concentration of acid and high temperature.What's more, it is found that the initial concentration of sulfuric acid, leaching temperature and leaching time have limited influence on the leaching efficiency of copper, iron, arsenic and zinc.

In this work, a thermodynamic study of zinc sulfide high temperature oxidative leaching was carried out. At the metals sulfides dissolution under oxidants action in acidic solutions several simultaneously proceeding reactions are possible. With the aim finding the proportion of potential reactions, a thermodynamic calculation was carried out using stoichiometric equations with equal oxidant consumption. Moreover, stoichiometric coefficients were chosen in such a way that reagents could exchange 1 mole of electric charge. Such an approach allows one to ensure a comparison of different oxidants’ usage effectiveness for sulfide leaching. Thermodynamic analysis results are in accordance with experimental data, which confirm that reactions with the formation of sulfur and sulfate-ions are uppermost at zinc sulfide dissolution in sulfuric acid solutions under oxygen action. Oxygen consumption and initial sulfuric acid concentration influence on proportion of this reactions and zinc equilibrium concentration in solution were investigated. Thermodynamic analysis showed that at insufficient acid concentration, which limits the maximum degree of zinc sulfide oxidation reaction advancements with sulfur formation, oxygen is consumed on oxidation reaction with the formation of sulfate-ions, which spend oxygen less effectively, due to four times smaller zinc dissolution. Thermodynamic calculations carried out allowed us to find out optimal proportions of oxygen consumption and initial sulfuric acid concentration, which provide achievement of a maximal zinc equilibrium concentration in solution at a higher effectiveness of oxidant consumption without labor-intensive experiments. At optimal acid consumption, a zinc equilibrium concentration is directly proportional to initial acid concentration. Directly proportional dependence of zinc cations’ formation on acid consumption was also detected at acid concentration optimal values.

A thermodynamic study of zinc sulfide high temperature oxidation leaching was conducted. Several processes can run simultaneously while metal sulfides are dissolved by oxidants in acidic solutions. Thermodynamic calculations were made using stoichiometric equations with equal oxidant consumption in order to identify the proportion of potential reactions. Moreover, stoichiometric coefficients were chosen in such a way as to reagents could exchange 1 mole of electric charge. This approach ensures a comparison of different oxidants in terms of their effectiveness in sulfides leaching. Thermodynamic analysis results obtained agree with experimental data confirming that oxidizing reactions with the formation of sulfur and sulfate ions prevail in zinc sulfide dissolution in sulfuric acid solutions under the oxygen effect. The effect of oxygen consumption and initial sulfuric acid concentration on the proportion of these reactions and equilibrium concentration of zinc cations in the solution was studied. Thermodynamic analysis showed that if the acid concentration is insufficient and limits the maximum progress of zinc sulfide oxidation with sulfur formation, oxygen is also consumed for the oxidation reaction with the formation of sulfate ions spending oxygen less effective due to 4 times less zinc cations passing to the solution. Thermodynamic calculations made it possible to find out the optimal proportions of oxygen consumption and initial sulfuric acid concentration to achieve the maximum zinc equilibrium concentration in the solution with more effective oxidant consumption without any labor-intensive experiments. The equilibrium concentration of zinc cations in the solution is in direct proportion to the initial acid concentration, and zinc cation formation is in direct proportion to oxygen consumption at the optimal acid concentration.

Sulfuric acid leaching of high iron-bearing zinc calcine

The leaching residue in zinc smelting system is taken as the research object, and the experiment of leaching residue in reduction leaching under sulphuric acid–sulfur dioxide system is carried out. The effects of reaction temperature, liquid–solid ratio, initial sulfuric acid concentration, partial pressure of SO2, and stirring speed on leaching rate of medium leaching residue under sulfuric acid-sulfur dioxide reduction conditions were studied. The leaching rates of zinc 95.24%, iron 98.66%, indium 95.04%, and copper 0.036% in medium leaching residue can be obtained at the conditions of temperature of 105 °C, time of 4 h, liquid–solid ratio of 8 ml/g, initial sulfuric acid concentration of 120 g/L, SO2 partial pressure of 200 kPa, and stirring speed of 500 r/min.