Study On Preparation Of Iron Oxide Red From Hematite Slag In Hydrometallurgy

In the process of hydrometallurgical zinc smelting,the iron settling slag produced by hematite method to separate zinc and iron has the characteristics of small slag content,high iron content and stable thermodynamic properties,so it has been paid much attention by hydrometallurgical zinc enterprises.The main iron phase of hematite precipitation slag is iron oxide,and the iron content is 55%?65%.It can be used as cement raw material,pigment and steelmaking raw material for comprehensive recovery and utilization of precipitation slag.However,the application of submerged iron slag is restricted by adsorbent salts and impurity such as osalum and basic ferric sulfate.For hematite impurities exist in the method of heavy iron slag,affect the recycling of the problem,in this paper by the method of wet zinc smelting hematite heavy iron slag as the research object,this paper proposes a atmospheric acid with high temperature hydrothermal method,realize the heavy iron slag surface adsorption of salt removal,and the impurities of the decomposition and transformation of iron phase at the same time,will become a high value-added heavy iron slag preparation of iron oxide red pigment,It provides a new method for the preparation of ferric oxide pigments.The main research work and results are as follows:(1)The feasibility of the decomposition and transformation reaction of impurity phase containing iron,such as jarosite and basic ferric sulfate,under the condition of high temperature hydrothermal reaction was studied from the perspective of thermodynamics.Thermodynamic calculation results show that:under the temperature of 180?260?,the decomposition reaction of erosite,the dissolution reaction of iron oxide and sulfuric acid(35)_rG_T^?value is negative,the reaction can be spontaneous;Ferric iron ion in reaction system by the reaction of hydrolysis reaction into iron oxide delta r value is positive,the reaction can't occur spontaneously,the reaction is endothermic reaction,temperature,the hydrolysis reaction is good,but in the high temperature and high pressure conditions,such as ferric iron ion hydrolysis reaction can be,and the experiments show that with the extension of reaction time,It is beneficial to increase the iron deposition rate of hydrolysis reaction.The(35)_rG_T^?value of the decomposition reaction between iron oxide and sulfuric acid is small,and it is not easy to react and decompose with sulfuric acid at high temperature,that is,iron oxide has a certain high temperature thermal stability.(2)The effects of adsorbent salts ZnSO₄ and Fe₂(SO₄)₃on the desorption of Zn²⁺and Fe³⁺ions on the surface of hematite sedimentation iron slag were studied under the conditions of reaction temperature of 50?70?,acid concentration of 0?15g/L and reaction time of 4.5h.The concentration of Zn²⁺and Fe³⁺in the liquid phase was determined by chemical analysis.The experimental results show that:The optimum temperature of zinc ion desorption in atmospheric pressure section is 65?.The presence of sulfuric acid solution is conducive to the desorption of zinc in hematite precipitation slag,and the desorption of zinc does not change with the reaction time.In the process of pickling of hematite precipitation slag,the content of zinc in the slag decreases from 1.03%to 0.26%,and the acid concentration in pickling experiment ranges from 0g/L to 15g/L.The concentration of zinc ions in the solution fluctuated between 1.0g/L and 1.5g/L.The results of pickling experiments show that the main form of zinc is adsorbent sulfate,and the surface of hematite precipitation slag adsorbed with trivalent iron ions.Under the condition of neutral water washing,goethite(Fe O(OH))precipitates are generated.In order to avoid the introduction of new impurity phase containing iron,The removal of adsorbent salts can be achieved to the maximum extent by pickling the submerged iron slag with an acid concentration of 15g/L under acidic conditions.(3)In view of the decomposition and transformation behavior of the impurity phase containing iron in the high-pressure hydrothermal reaction process,the effects of different hydrothermal reaction conditions,such as acidity,temperature,time and liquid-solid ratio on the grade of iron oxide red prepared by precipitation of iron slag from hydrothermal zinc hematite process were studied.The results show that under the conditions of p H value 1,temperature 220?,holding time 3h,liquid-solid ratio 6:1,stirring speed 400r/min,the mass fraction of iron oxide red product increases from58.66%to 66.83%.The content of iron in Fe₂O₃increases from 55.17%to 65.35%.The sulfur content decreased from 2.96%to 0.82%.The zinc content decreased from1.03%to 0.18%.Iron oxide red product through the related chemical detection,meet the national standard iron oxide red content of iron grade C,water soluble and water-soluble chloride and sulfate content type ?,sieve residue type 2,105?volatile V₂,source type A standard,namely GB/T 1863-C-?-2-V₂-a standard.