| How to remove magnesium from the hydro-zinc smelting process cleanly and efficiently is a technical problem for the clean utilization of complex high-magnesium zinc concentrates,and it is also an industry problem that the hydro-zinc smelting industry has faced for a long time and has not been properly resolved.This paper takes the Spent electrolyte of hydrometallurgical zinc smelting as the research object,studies and analyzes the solid-liquid equilibrium data of magnesium sulfate in the H2SO4-H2O system and Zn SO4-H2SO4-H2O system,and obtains the basic data of the solubility of magnesium sulfate under low temperature conditions.,Adopting frozen crystallization technology to research and develop a new technology for the removal of magnesium by freezing and crystallization of the Spent electrolyte of hydrometallurgical zinc smelting to realize the clean and efficient removal of magnesium sulfate in the process of hydrometallurgical zinc smelting The main research work and results are as follows:1)Starting from the basic research on the physical and chemical properties of multiple complex sulfate solutions and the solid-liquid equilibrium,the equilibrium method is used to determine the solubility of magnesium sulfate in sulfuric acid and zinc sulfate acidic solutions,and the data is fitted with the Apelblat equation,and the equilibrium solid is analyzed.phase.It is found that the solubility of magnesium sulfate in the H2SO4-H2O system decreases with the decrease of temperature and the increase of sulfuric acid concentration.At a temperature of 263.15K and a sulfuric acid concentration of 1.5 mol·L-1,the solubility of magnesium sulfate is 0.988 mol·kg-1.The solubility of magnesium sulfate in the Zn SO4-H2SO4-H2O system decreases with the decrease of temperature,the increase of sulfuric acid concentration,and the increase of zinc sulfate concentration.At the temperature of 263.15K,the concentration of zinc sulfate is 0.80 mol·L-1,and the concentration of sulfuric acid is respectively Under the conditions of 1.00,1.45,and 1.99mol·L-1,the solubility of magnesium sulfate in the quaternary system is 0.708,0.604,0.411mol·kg-1,respectively,and the main components of the equilibrium solid phase are Mg SO4·7H2O and Zn SO4·7H2O,Compact structure,short rod shape,uniform distribution of zinc,magnesium,sulfur and oxygen on the surface,it is a zinc-magnesium sulfate double salt containing crystal water.2)Based on the solubility data of magnesium sulfate in sulfuric acid and zinc sulfate acidic solutions under low temperature conditions,a study on the removal of magnesium from the Spent electrolyte of hydrometallurgical zinc smelting at low temperature by freezing and crystallization was carried out.The study found that when the temperature is 263.15K and the reaction time is 120min,the waste The magnesium ions in the electrolyte decreased from 23.60 g·L-1 before crystallization to 14.22 g·L-1after crystallization,realizing the selective crystallization separation of magnesium sulfate in the Spent electrolyte.The crystalline products are mainly Mg SO4·7H2O and Zn SO4·7H2O,which are short rods.The content of magnesium sulfate heptahydrate is52.0%?53.5%.The distribution of zinc,magnesium,sulfur and oxygen on the surface of the crystalline product is consistent,indicating that it is zinc sulfate containing water.Magnesium double salt.3)A series of experiments were carried out to remove magnesium from zinc hydrometallurgy spent electrolyte by freezing crystallization.It was found that magnesium,zinc and manganese in the mother liquor were maintained in the range of14?15 g·L-1,34?35 g·L-1 and 3.7?3.9 g·L-1 at 263.15 K,respectively.Sulfuric acid was almost not lost.The content of magnesium sulfate heptahydrate in the crystallization product was 53.0%?53.5%The composition of the product is consistent with that of the optimized product.No chemical reagent is needed in the process of magnesium removal by freezing crystallization.The obtained magnesium removal solution can be returned to the zinc hydrometallurgy system for recycling.The crystallization products can be used to prepare magnesium salt products.This technology has the characteristics of clean,efficient and environment-friendly. |
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