Study On The Comprehensive Utilization Of Phosphate Tailings

With the massive exploitation of phosphorite in China,phosphorus resources are becoming scarce.The phosphate tailings refers to the“wastes”produced by the beneficiary companies after the use of mine concentrates under certain technical conditions.It belongs to the mining solid waste in industrial waste materials.At present,there is no effective method for the treatment and utilization of the phosphate tailings.Waste phosphate tailings are piled up,which it’s not just about the land,and it’s polluting the environment around it,and also cause the loss of a lot of useful elements in the tailings.As a potential"secondary mineral resource",calcium,magnesium,phosphorus and other useful elements can be recovered synthetically,which can be used to produce a series of materials with low added value or high added value.The comprehensive utilization of tailings can not only solve the problem of stacking,environmental pollution,but also bring huge economic,environmental and social benefits.The raw materials selected in this paper are the remaining tailings from a certain process of ore dressing in hubei ezhong phosphate mine.The slagging phase and the acid solution were obtained after the acid-lysis reaction with industrial hydrochloric acid.The effective element calcium,magnesium and phosphorus in acid solution were recycled.And we washed the slag with water,then mixed washingwater with the acid solution,gaving the solid No.1.After the solid liquid separation,the liquid was treated with dilute sulfuric acid treatment to obtain the calcium sulfate whisker,and the acidizing filtrate was enriched to produce No.2.And then separated it.The phosphorus and magnesium in the concentrated filtrate were enriched by cyclic acid hydrolysis.The research conclusions are as follows:（1）Using X-ray diffraction,X-Ray Fluorescence,scanning electron microscope and thermogravimetric analysis to analyze the magnesium phosphate tailings,the results show that the the content of this tailings is about 93.53%dolomite,the rest part is mostly fluorophosphatite and contains a small amount of other minerals.The chemical composition of different tailings samples is basically the same,in which the content of P₂O₅ fluctuates around 5.32%,while the content of MgO is high up to24.08%.Therefore,it can be regarded as medium-low grade phosphate ore.The tailings are mainly dolomite,and fluorapatite has obvious contrast with dolomite.The magnesia phosphate tailings before 650℃,the quality is stable,650℃⁸50℃for weightlessness,magnesium carbonate decomposition temperature about 650℃,the calcium carbonate decomposition temperature about 750℃,the mass loss rate is about 35%.（2）Circulating Acidolysis can effective enrichment of effective element phosphorus,magnesium.In the process of acid hydrolysis,magnesium oxide and phosphorus pentoxide in the acid solution reached116.07 g/L and 49.99 g/L,respectively,and magnesium oxide and phosphorus pentoxide in the acidizing fluid reached 170.37 g/L and 72.06g/L,respectively.The main components of the solid No.1 were monocalcium chlorophosphate and dihydrate gypsum,which can be treated with concentrated sulfuric acid and effective separation of calcium,Magnesium and phosphorus;and the main components of the solid No.2were magnesium chlorideand calcium metaphosphate,which can be treated with 70%dilute sulphuric acid effective separation of calcium,Magnesium and phosphorus,and produce high quality Calcium Sulfate Dihydrate.（3）Under the optimal process flow chart,when the system reaches equilibrium,The concentrations of calcium oxide,magnesium oxide and phosphorus pentoxide in acid solution tended to be 68 g/L,98 g/L and 58g/L respectively.The concentrations ofcalcium oxide,magnesium oxide and phosphorus pentoxide in the acidizing fluid tended to be 3 g/L,98g/L and 58 g/L respectively.The quality of silica slag is controlled at about 21 g,Output rate 8.02%,and the quality of No.1 is controlled at about 12 g,Output rate 4.58%.The quality of gypsum is around 185 g,Output rate 70.66%and the quality of No.2 is controlled at about 140 g,Output rate 53.48%.The concentration of concentrated liquid hydrogen ion is controlled at 1.14 mol/L,and the amount of concentrated sulfuric acid is controlled at about 80 mL.（4）The optimum conditions for the preparation of gypsum whiskers by acid leaching solution with industrial hydrochloric acid leaching high magnesium phosphate tailings:5%sulfuric acid mass fraction,reaction temperature 95℃,reaction time 30 min,mechanical agitation speed 200r/min,under the technological conditions of whisker of dihydrate gypsum whisker,length to diameter ratio in 50⁹0,and the color white.The innovation points of this paper are as follows:（1）Using circulation pickling and acidification and enrichment process of phosphate tailings technologize processing,calcium,magnesium and phosphorus,silicon slag,No.1,No.2,gypsum whisker and solid all exports of comprehensive and effective use of the product,"three wastes"emissions and circulation system is stable,for phosphorus tailings comprehensive utilization has provided the theory and reference data.（2）Using a cyclic acid solution-cooling crystallization is extracted from the phosphorous of the phosphorous to make calcium sulfate crystals.