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Aiming at the problems of low oxygen utilization rate and slow dissolution of sphalerite in the pressure leaching process of zinc concentrate, the strong oxidizability of Fe3+ in zinc leaching residue and the oxygen transport efficiency of Fe2+/Fe3+ redox ion pair were used to improve the efficient oxidation of S2- in sphalerite and the utilization rate of O2, so as to realize the synergistic enhanced leaching of zinc concentrate and zinc leaching residue. The results show that Fe3+ can improve the solubility of oxygen, and the back-and-forth valence behavior of Fe2+/Fe3+ accelerates the oxidative dissolution of sphalerite (ZnS) in the leaching system, and the leaching rate and leaching efficiency of zinc are significantly improved. Under the optimal process conditions of initial sulphuric acid concentration of 95 g/L, oxygen partial pressure of 0.8 MPa, temperature of 160 °C, reaction time of 120 min, and pH value of 3, and the addition of 6.1 g/L Fe3+ in the form of zinc leaching residue results in a high leaching rate of 98.60% of zinc, and 92.47% of iron is precipitated into the residue. The synergic Caching of zinc concentrate and zinc leaching residue is controHed by external diffusion with apparent activation energy of 15.61 kj/mol. The kinetic equation of synergc Caching process Is as follows; 1-(1-a)1/3=4.78X 10-3 X {[exp(-15610/8.314T)] Xc(H2SO4)1,21 XP(O2)0.33 Xc(Fe3+)0.43Xt} . [ABSTRACT FROM AUTHOR]

In this study, hydrothermal metallurgy technology was used to convert arsenic in the solution into a stable, dense, and granular arsenic-fixing mineral, scorodite (FeAsO4·2H2O), that is conducive to storage. The effect of Na+ on the precipitation rate of arsenic and iron, the phase composition, and the transformation of arsenic residue during the mineralization and arsenic precipitation of hydrothermal scorodite in the H3AsO4-FeSO4-Na2SO4-H2O system were studied. The results show that Fe3+ co-precipitates with As5+ to form scorodite (FeAsO4·2H2O). In the later stage of the reaction, Fe3+ and Na+ combine to precipitate in the form of sodium jarosite [NaFe3(SO4)2(OH)6]. Under the conditions of an initial Na+ concentration of 10 g/L, an arsenic concentration of 10 g/L, a molar ratio of iron to arsenic of 1.5, a pH of 1, a reaction temperature of 160 °C, a stirring speed of 500 r/min, a reaction time of 3 h, and an oxygen partial pressure of 0.6 MPa, the precipitation rates of arsenic and iron were 98.2% and 93.2%, respectively. The phase composition of the arsenic residue is mainly composed of large-grained polyhedral crystal scorodite, and a small amount of irregular, small-grained crystal sodium jarosite is dispersed in it. By controlling the initial molar ratio of iron to arsenic, the concentration of Na+, and prolonging the reaction time, the formation of the sodium jarosite phase can be inhibited, and the transformation of the sodium jarosite phase into the scorodite phase can be promoted, so as to realize the efficient precipitation of arsenic, reduce the amount of arsenic residue, ensure the stability of arsenic residue, and avoid potential environmental pollution risks. [ABSTRACT FROM AUTHOR]

For the conventional wet zinc refining processes of the jarosite method and goethite method of iron removal, the process that existed was iron residue low iron, high zinc, large amount of residue, and high cost of harmless treatment, this paper carried out a study on hydrothermal iron removal from wet zinc refining solutions and an iron residue that reduces emissions. The results show that the reaction temperature is a prerequisite for the precipitation of Fe3+ to precipitate hematite (Fe2O3). Prolonging the reaction time can induce the conversion of jarosite (KFe3(SO4)2(OH)6) to hematite. Increasing the partial pressure of oxygen will accelerate the oxidation of Fe2+ to Fe3+ and promote the formation of the hematite phase. Under the optimized technical parameters of reaction temperature 180 °C, oxygen partial pressure 0.6 MPa, reaction time 3 h, and controlled alkali metal ion concentration, 92.49% of the iron in the solution was precipitated into the residue in the form of hematite(Fe2O3), and the precipitated iron residue contained 57.75% iron and 0.82% zinc; compared with the jarosite process, the amount of iron residue was reduced by about 65%, and the zinc content of iron residue was reduced by 5.86%. The use of hydrothermal mineralization iron precipitation processes can realize the mineralization precipitation of iron in solution under low-acid conditions and obtain hematite iron precipitation residue with iron content up to the industry standard of iron oxide. And can be realized for resource utilization, helping the wet process zinc industry to develop in a green and low-carbon direction. [ABSTRACT FROM AUTHOR]