Study On Production Of Ferromagnesium Sulfate With White Waste Acid And Phosphate Rock Flotation

China has a wealth of resources,but the process of resource utilization will produce a large number of industrial waste.How to deal with and utilize industrial waste resources effectively and achieve sustainable production without destroying the environment has became the consensus and research hotspot in the world's industrial field.A large number of waste acid which contained 20%to 25%H2SO4 and 10%to 15%FeSO4 will be brought in the production process of sulfuric acid,and the process of enriching the phosphate rock usually use chemical flotation in China,which will produce a lot of rich magnesium tailings(MgO>15%).This paper presents a technique that discussed the comprehensive utilization of titanium chemical waste acid and phosphorus chemical flotation tailings.Through the development of the new fertilizer ferromagnesium sulfate to achieve the purpose of recycle waste products.The specific method is to utilize the sulphuric acid in the waste acid to extract the magnesium in the tailings,so as to prepare the ferromagnesium sulfate with the iron in the waste acid.And can be adjusted by the process of different magnesium and iron ratio of the series of products to meet the different crops's growth requirements.In this paper,the metastable phase equilibrium in the ternary system Mg2+,Fe2+//SO42-was investigated at 20?,30? and 40? using an isothermal evaporation method.The results showed that the ternary system belongs to the complete isomorphous series,and double salts were not found at the investigated temperature.The crystallization region of the solid solution[(Fe,Mg)SO4·7H2O]occupies the entire phase region,in which Mg2+ and Fe2+ can be interchanged in any proportion.Provide a thermodynamic and crystal structure basis for the development of ferromagnesium sulfate production technology.In the study of the acidolysis process,the optimum acid digestibility of Mg was investigated.The optimum conditions for acid hydrolysis of waste tailings were as follows:the ratio of acid to ore was 4?6,the reaction time was 90min,the reaction temperature was 50?60?,under the conditions the acid hydrolysis rate of Mg was above 92.5%.Based on the acid hydrolysis of tailings,the kinetic study of tailings acidolysis was carried out.The Drozdoff equation can describe the acidolysis behavior of tailings in sulfuric acid,the apparent activation energy Ea?6.889kJ/mol,belonging to diffusion control process.The crystallization process was studied,and the optimal parameters of crystal(Mg/Fe=1)were as follows:initial crystallization temperature 65?;crystallization termination temperature 35?;cooling rate 0.1?/min;crystallization material molar ratio Mg/Fe=1.80;stirring rate 150 rpm,and the above conditions have a certain influence on the molar ratio of Mg/Fe in ferrous sulfate.In order to achieve the most cost-effective production costs,the three routes of non-return slurry process,filtrate back-pulp process and filtrate back-pulp waste acid washing filter cake were compared,the results showed that the filtrate back-pulp waste acid washing filter cake process has a lower cost.But it need to be decided by multi-angle such as equipment corrosion and cost from the perspective of industrial transformation.The above results provided theoretical basis and technical guidance for the production of ferromagnesium sulfate with white waste acid and phosphate rock flotation,and some of the industrial processes had been completed.