| Many developed countries have already carried on the comprehensive utilization research of yellow phosphorus slag many years ago. Although the use of yellow phosphorus slag was on the late start of the study in China, has achieved fruitful results. With the yellow phosphorus slag as the raw materials and with nitric acid as leaching agent, the alcium was separated from the yellow phosphorus slag in the form of calcium nitrate, the paper researched the technology of producing the high quality white carbon black product and the high quality calcium sulfate dehydrate product by leaching, washing, drying, calcining,grinding and which the calcium nitrate was precipitated with sulphuric acid. The technology has used fully of Si, Ca and other valuable components in yellow phosphorus slagFirstly, in this paper, the author studied the technology of manufacturing white carbon black by precipitation method. The author studied effects of calcining, leaching, optimizing conditions on the quality of white carbon black by using nitric acid leaching yellow phosphorus slag. The experimental study indicated that the optimum process conditions manufacturing white carbon black are:the calcination time was 30 minutes, the calcination temperature was 750℃, the stirring speed was 360 r·min-1, the reaction time was 6 hours, the reaction temperature was 100℃, the fluid-solid ratio was 10:1, the concentration of nitric acid was 25%, the washing terminal pH of the leaching residue was 6.0, the charging way was A. Under the condition of the system to get white carbon black product, its appearance is white powder, particle size mainly distributed in the 9.66-11.89um, between the XRD and FTIR analysis indicated that the compound is mainly amorphous silica form, the whiteness is 90.24%, the mass fraction of silica (SiO2) could reach 98.50%, the mass fraction of Fe is11.90mg/kg, specific surface area is 249m2/g, and the main qualities of product reach HG/T3061-2009 DAP product quality requirements.In addition, the paper researched the technology of manufacture calcium sulfate product with the lixivium produced in the course of leaching yellow phosphorus slag by nitric acid.The author studied effects of the reaction time, the concentration of sulphuric acid, the stirring speed, the reaction temperature, the ratio between H2SO4 and Ca(NO3)2, the washing terminal pH,the charging way on calcium sulfate product by using sulfuric acid as precipitant. The optimum technological conditions:the reaction time was 30 minute, the concentration of sulphuric acid was 20%, the stirring speed was 200～250 r·min-1, the reaction temperature was room temperature, the ratio between H2SO4 and Ca(NO3)2 was 0.6:1, the washing terminal pH was 5.0. In different reaction temperature and charging way, can get three different morphology of calcium sulfate crystals. Under the condition of the system to get calcium sulfate product, its appearance is white crystal, particle size mainly distributed in the 14.63～27.28μm, the XRD, FTIR and TG-DSC analysis indicated that the compound is mainly calcium sulfate dihy form, the SEM analysis indicated that three different crystalline form were irreqularity, schistose, acicular, and the chemical analysis indicated that the mass fraction of CaSO4 is above 99%, the mass fraction of H2O is about 21%.the paper researched the technology of producing the high quality white carbon black product and calcium sulfate dihydrate product by using Si, Ca and other valuable components contained in yellow phosphorus slag, which can not only make full use of waste, clean production, energy-saving, emission reduction, protecting the environment but also reducing the production cost of white carbon black and calcium sulfate, producing a high economic efficiency, improving comprehensive utilization process of yellow phosphorus slag. Therefore the researched technology has a good application prospect. |
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