The Process Diagram Of Preparation Of Iron Oxide Red Or Ferric Chloride From Pyrite Cinder

In this dissertation,the preparation of iron oxide red and liquid ferric trichloride from pyrite cinder was studied.Facing to the problem of low iron leaching rate in leaching of pyrite cinder,auxiliary strengthening circulation acid leaching process was designed and adopted,focusing on the optimization of technological conditions,such as,“auxiliary strengthening acid leaching”,precipitation of iron from leaching solution and purification of iron hydroxide filter cake.The main work includes:(1)According to the principle of selection of auxiliaries,oxalic acid was selected as the more suitable auxiliary agent for the acid leaching.(2)The conditions of “auxiliary strengthening acid leaching” using oxalic acid were optimized as follows: reaction time 7.5h,addition of oxalic acid 20%wt(relative to pyrite cinder),the concentration of sulfuric acid 50%,reaction temperature 98℃,under which the leaching rate of iron could reach 95.7%.(3)The conditions for the precipitation of iron were optimized as follows: initial concentration of iron ions 1.75mol·L-1,molar ratio of H2O2 to Fe2+ 0.875,reaction temperature 35°C,reaction time 2.5h and the p H value of the system 5.8.Under this condition,the recovery rate of iron in the acid leaching solution could reach 99.3%.(4)After precipitation,when the filter cake was dissolved in dilute solution of Na OH for 5 min,the content of Al in the cake decreased from 1.15% to 0.02%.(5)The conditions for the preparation of iron oxide red were optimized as follows: calcination temperature 800°C,calcination time 3h.Under this condition,the mass fraction of iron oxide in the prepared sample reached 99.1%,and the main technical indicators of the samples could meet or exceed that in the national standard(GB/T 1863-2008);The FESEM image analysis showed that the faster the dropping rate of ammonia water in the precipitation process,the smaller the particle size of the prepared iron oxide red sample would be.The main technical indicators of the ferric chloride liquid sample obtained from the purified cake could meet or exceed that in the national standard(GB/T 1621-2008).(6)The ammonium oxalate solid and ammonium sulfate crystals containing a small amount of ammonium sulfate can be obtained by stepwise evaporation and crystallization of the precipitated iron filtrate.It has been experimentally verified that the recovered ammonium oxalate solid could be used as the auxiliary agent in the leaching process.