Phosphorite Preparation Of Calcium Sulfate Whiskers

Phosphogypsum is a solid waste sulfuric acid leaching of phosphate rock phosphate production selected from the two water calcium sulfate is the main component of phosphogypsum content,probably more than 75%,a lot of impurities in phosphogypsum,the current domestic phosphogypsum slag stockpiling has exceeded 1.2 tons,and each year to produce about 50000000 tons.A large amount of phosphogypsum will cause serious damage to soil environment,water environment and atmospheric environment.It has become a hot spot of research,and also the only way for the sustainable development of phosphorus chemical industry.But due to impurities of phosphogypsum and color has black,and its application is greatly limited.The utilization of phosphogypsum and preparation of calcium sulfate whisker white is an important method of high value utilization of phosphogypsum.In this paper,two water calcium sulfate whisker,preparation of hemihydrate calcium sulfate whiskers,purification and decolorization of crystal modifier effect on growth of hemihydrate calcium sulfate crystals using phosphogypsum,using the method of uniform experiment and single factor experiment combined with the search process conditions of calcium sulfate whisker best prepared by polarizing microscopic observation of microstructure of calcium sulfate crystal and calculate the ratio of length to diameter,the effects of reaction conditions for preparation of calcium sulfate whisker on the phosphogypsum.Phase analysis of the products by X ray diffraction.The effects of the conversion agent on the growth of calcium sulfate hemihydrate crystals were studied.The results of this study provide basic data and theoretical reference for the diversification and high value utilization of phosphogypsum:?1?using solid waste phosphogypsum as raw material was prepared by atmospheric acidification two water calcium sulfate whiskers by polarizing microscope and related software as analysis of the diameter ratio of two water calcium sulfate method,gives the ideal conditions for preparation of two water calcium sulfate whisker as the reaction temperature is 80 DEG C the slurry solid content.0.20g,ml-1,reaction time 10min,the mass fraction of HCl 20%.Under these conditions,the high aspect ratio whiskers were prepared with the aspect ratio of 138.46.The filtered residue and filtrate can be reused to reduce the production cost.?2?the basic preparation experiment of two calcium sulfate whisker in water phosphogypsum atmospheric acidification method on the control of acid solution mass fraction of 10%,the volume of acid solution 300ml,reaction time 10min,reaction temperature is 80 DEG C,changing the dosage of gypsum,phosphogypsum to explore when the dosage is 12g,the purification of phosphogypsum the rate can reach 87.5%.?3?autoclaved preparation conditions of hemihydrate calcium sulfate whiskers optimal for slurry solid-liquid ratio 0.3MPa 0.15g pressure ml-1,reaction time 0.5h,steam pressure,this condition was prepared under the ratio of length to diameter 99.07,a diameter of about 1 m.The preparation of hemihydrate calcium sulfate whisker is the process of dissolution and recrystallization of two calcium sulfate,and the prepared calcium sulfate whiskers have high purity and good crystallinity.?4?after the substitution of Ca²⁺ in the sulfate conversion agent,the metal is weaker than the Ca2+ ion,and the crystal grows in an elongated direction.Small effect on the growth of calcium salt crystal modifier hemihydrate calcium sulfate crystals,calcium nitrate crystal modifier on whisker aspect ratio promote obvious effect,the other found no obvious regularity.Organic carboxylic acid crystal modifier on hemihydrate calcium sulfate crystal growth effect is the main reason for the complexation of carboxymethyl Kyrgyzstan with calcium ions,the adsorption of organic carboxylic acid crystal modifier selective growth of the crystal surface in the crystal C axis,can reduce the surface crystal surface,inhibiting crystal growth of C axis to.Three kinds of organic acids of crystal modifier were one yuan,two yuan,three yuan of carboxylic acid salt,the experimental results show that the strongest complexation of sodium citrate on calcium ion,the complexation of sodium oleate on poor calcium ions,resulting in crystal growth defects.