ИСТИНА

In this research, the ammonium alum solution was purification from Fe (III) – the main impurity in the acid technology for alumina production using ion exchange method. The acid solution was obtained after Coal Fly Ash high-pressure leaching by 7.5M H2SO4 + 40% NH4HSO4 mixture at T = 210 ºC. Two type of resins, Purolite S957 and S950 were used in sorption tests. At optimum parameters (T = 25 ºС, sorption time 24 h and the resin to solution ratio - 1:25), it is possible to extract more than 90% of iron. Using the Langmuir model, the batch sorption values for iron were calculated: for Purolite S957 resin - 19.48 g/g; for Purolite S950 - 3.39 g/g. The dynamic sorption was studied for Purolite S957 resin at a solution flow rate of 0.4, 0.65, and 1.6 specific volumes (Vsp.vol.) per min. Using the Thomas model, dynamic capacity values were calculated for each of the rates: 0.4 Vsp.vol./min - 6344.56 mg/g; 0.65 Vsp.vol./min - 5590.23 mg/g; 1.65 Vsp.vol./min - 1632.77 mg/g. The desorption of Fe(III) from resin using 2M H2SO4 at the rate of 0.4-0.65 Vsp.vol was studied. The required volume of desorbent at both rates is 6 Vsp.vol.. The possibility of removal the Fe(III) from ammonium alum solution by 12 times (from 27.2 mg/L to 2.2 mg/L) using Purolite S957 resin was founded.