Study On Extracting Rare Earth From Baotou Rare Earth Production Waste

In this paper, an environmental-friendly technology of extracting rare earth from Baotou production waste has been developed, according to the larger amount of residue discharged in the process with the method of the high temperature sulfuric acid. The aim is to extract rare earths in the form of carbonate, using the three main steps:roasted at low temperature with sulfuric acid, double salt precipitation and the conversion among carbonates. This proposed technology has some advantages with respect to less exhaust in the whole process, the enrichment of valuable elements in different stages and convenient for recycle, which has been applied in the practical production, and achieved better economic benefits.This thesis mainly divides into four parts. In the first part, Through XRF, XRD, SEM and chemical analysis, research analysed the baotou slag phase composition, distribution and occurrence of the condition, and found that rare earths are widely distributed in the iron phosphate, calcium sulfate and barium sulfate as rare earth sulfate, monazite and bastnaesite, etc. And base on the thermodynamics analysis, through a series of exploratory experiments, The preliminary plan was builded. The method extracted rare earth from residue and solved the problem of the rare earth separate from Fe and P through sulfuric acid at low temperature roasting, double salt precipitation and carbonate conversion of rare earth.The second part through the orthogonal experiment the influece of the temperature, time, amount of acid, minerals, water content to examine the effect of rare earth extaction, and get the best experiment condition:50 g of material moisture content less than 5.67%, after mixed with 13 ml concentrated sulfuric acid, roasting 3 h under 240? temperature, can obtain the REO yield> 84%. Through means of XRF, XRD, SEM and chemical analysis methods to find that the rest of rare earth has been concentrated in barium sulfate of leaching residue as sulfate.The third part through the single factor experiment to examine the influence of addition amount of rare earths to the effect of sulfate double salts convertion under 70?.80?, and strring 1h. At 80?, the excess sodium sulfate 90%, can obtain 95.23%of the rare earth yield; At 70?, with adding 150% excess sodium sulfate, rare earth yield of rare earth yield can reach 93.15% only. The Fe, P wt% was reduced to 0.27%,0.74% in rare earth sulfate double salts.The fourth part through the orthogona experiment examines the influence of temperature, time, concentration of sodium carbonate, sodium carbonate amount to the result. And production conditions were determined according to the results of the orthogonal experiments: 50 g of sulfuric acid double salt in sodium carbonate excessive concentration of 35%; 35wt%; transformation temperature 75 "C; transformation time,1 h, the rare earth conversion rate over 99%. Research continue to purify the rare earth product through adjusted pH to except Fe in solution after acid dissolving carbonas. Again converted rare earth to carbonate, then calcinated the carbonate under 800? 1h. Final obtained the pure mixed rare earth oxides.