Study On Comprehensive Recovery Of Mg And P From Phosphate Floatation Tailings By Calcination And Leaching Of Ammonium Salt Method

Based on the resource and characteristics of the floatation tailings from Wengfu phosphate,the selective leaching technique using ammonium salt was carried out to treat the phosphate tailings instead of the traditional dolomite carbonization arts and crafts.By means of the technique,not only the high added value products,such as magnesium hydroxide,magnesium oxide and light calcium carbonate,were obtained, but also enriched phosphate concentrate from the phosphate tailings was obtained, which can be used in wet-phosphorous acid process.Furthermore,the environmental questions arised from the pile-up of a mass of phosphate tailings can be solved and the comprehensive utilization of resources can be come true.The phase composition and chemical constituent of the phosphate tailings were analyzed,and the physicochemical properties of each component were studied detailedly.Meantimes,the thermodynamics theories were applied to analyze the rationality and the feasibility of calcination and leaching test.Based on the calcination test of the phosphate tailings,the optimum calcined conditions were obtained,in which the weight-loss ratio of the phosphate tailings can get to 38.06%.The optimum conditions of calcium oxide leaching were obtained through the leaching test of the calcined product,in which the leaching ratio of calcium can reach 80.43%,the leaching ratio of magnesium being only 1.12%,and calcium and magnesium can be separated well.In the test of ammonium sulfate leaching filter residue after extracting calcium,single factor tests combined orthogonal test were adopted to find the optimum conditions of magnesium oxide leaching.Under the conditions,the leaching ratio of magnesium can achieve over 91%,and leaching effect was very satisfactory.In experiments,light calcium carbonate was obtained from nitrate of lime solution by cleaning and carburizing process,magnesium hydroxide obtained from magnesium sulfate solution by cleaning and using ammonia water as precipitant,and magnesium oxide was obtained from magnesium hydroxide by roasting.The above-mentioned three products can all meet the correlative quality standard of GB of China by check analysis. By means of the two-phase leaching of the calcined product of the phosphate tailings,the resulting filter residue is a high quality of phosphate concentrate with a over 38%P₂O₅ grade and 88.58%recovery.The technological conditions of the test are easy controlled with simple operation and low facility request.NH₃ and CO₂ can also be utilized circularly,and only a small quantity of waste slag that is pollution-free to our environment was produced.The research in this paper can provide some valuable reference for exploitation and utilization of Wengfu phosphate floatation tailings.