Study On The Oxidative Hydrolysis Behavior Of Ferrous Sulfate Crystals In High Temperature Aqueous Solution

With the continuous reduction of high-quality zinc resources,the development and utilization of high-speed iron sphalerite has attracted great attention from metallurgical workers.With the rapid development of hematite iron removal technology and the increasingly strict environmental protection regulations,hematite iron removal technology is a waste-free iron removal technology.Hematite iron removal technology is at 180??200?.At this temperature range,A large number of ferrous sulfate crystals cause refractory ferrous sulfate crystals,slow oxidation of ferrous sulfate,reduced hydrolysis of ferric sulfate,high iron ion concentration in the liquid after iron removal,and slow oxidation of ferrous iron.The oxidation process of ferrous ions occurs between gas-liquid-solid three phases.The crystallization-oxidation-hydrolysis chemical reactions and processes have multiple and complex chemical behaviors.In response to the above problems,this paper takes different sulfate solutions as the research object,the main research work and results are as follows:?1?The crystallization behavior of ferrous sulfate in high temperature aqueous solution was studied.The effects of temperature,static adsorption,time,ferrous concentration,zinc ion concentration and magnesium ion concentration on the crystallization of ferrous sulfate were investigated.The physicochemical properties of ferrous sulfate were characterized by SEM and XRD.The results show that the solubility of ferrous sulfate decreases with increasing temperature,and the solubility of ferrous sulfate decreases sharply between 160? and 180?.At 150?,the solution is in the first metastable zone;at 160?-170?,the ferrous sulfate solution is in the second metastable zone;and at 180?-190?,the solution is in the unstable zone.The quiescence is beneficial to the formation of large ferrous sulfate crystals and the crystallization rate of ferrous sulfate.Prolonging crystallization time is conducive to the growth of ferrous sulfate crystals and the crystallization rate of ferrous sulfate.The addition of Zn²⁺and Mg²⁺ will reduce the solubility of ferrous sulfate.The addition of zinc ions and magnesium ions will lead to a sharp decrease in the solubility of ferrous sulfate from 160?-170? to 170?-180?.Changing the concentration of ferrous iron in the initial solution,the sharp decrease in the solubility of ferrous sulfate remains unchanged.When the temperature is 120?-160?,the crystallization amount of ferrous sulfate gradually increases with the increase of the concentration of zinc ions and magnesium ions;when the temperature is higher than 160?,the solubility of ferrous sulfate increases with the concentration of zinc ions.It rises first and then decreases,and the crystalline amount of ferrous sulfate decreases first and then rises.?2?Aiming at the crystallization behavior of zinc,iron and magnesium in FeSO₄-Zn SO₄-MgSO₄-H₂SO₄ system,the effects of different sulfate concentrations on the crystallization of ferrous sulfate,zinc sulfate and magnesium sulfate were investigated.The results show that the solubility of ferrous sulfate,zinc sulfate and magnesium sulfate decreases with the increase of temperature;In the FeSO₄-Zn SO₄-H₂SO₄system:when the temperature is lower than 160?,the crystallization rate of zinc sulfate and ferrous sulfate increases with the increase of the concentration of zinc ions.The presence of ferrous sulfate increases the crystallization rate of magnesium sulfate between 140? and 190?.In the FeSO₄-MgSO₄-H₂SO₄ system:when the temperature is lower than 160?,the presence of magnesium sulfate increases the crystallization rate of ferrous sulfate;when the temperature is higher than 170?,the presence of magnesium sulfate reduces the crystallization rate of ferrous sulfate.The crystallization rate of zinc sulfate is increased by the presence of ferrous sulfate between 140?and 190?.When magnesium sulfate is added to the FeSO₄-ZnSO₄-H₂SO₄ system,the crystallinity of ferrous sulfate and zinc sulfate decreases.When zinc sulfate is added to the FeSO₄-MgSO₄-H₂SO₄ system,the crystallization rate of ferrous sulfate and magnesium sulfate increases between 140? and 170?;the crystallization rate of ferrous sulfate and magnesium sulfate decreases between 170?and 190?.?3?In order to explore the effect of ferrous sulfate crystallization on the oxidative hydrolysis process.The experiment of oxidation hydrolysis of ferrous sulphate was carried out.The weight and composition of the filter residue,the weight and composition of the precipitate,and the iron ion concentration in the solution were used as quantitative indicators.The results show that in the heating stage,a large amount of ferrous sulfate crystallizes,resulting in slow oxidation and hydrolysis of ferrous sulfate,resulting in a high concentration of liquid iron ions after iron removal.In the oxidative hydrolysis stage:in the FeSO₄-H₂SO₄ system,the hydrolysis rate of ferric sulfate is less than that of ferrous sulfate within 1 hour of reaction.After 1 hour of reaction,the oxidation rate of ferrous sulfate is less than the hydrolysis rate of ferric sulfate;In the FeSO₄-ZnSO₄-H₂SO₄ system,the dissolution rate of ferrous sulfate was greater than the oxidation rate of ferrous sulfate within 1 hour.After 1h reaction,the dissolution rate of ferrous sulfate crystal was lower than the oxidation rate of ferrous sulfate.