Abstract: Normally，hydrochloric acid is used to decompose phosphorite to produce phosphoric acid and calcium sulfate whiskers,and the process conditions of preparing calcium sulfate whiskers were mainly studied.In the process,the acid solution including Ca²⁺  was prepared by decomposing phosphorite powder with hydrochloric acid,then calcium sulfate whiskers can be produced when sulphuric acid was added to that solution in a proper way.Impacts of various factors,such as  temperature,sulfuric acid concentration,feeding time,and stirring rate,on morphology and slenderness ratio of calcium sulfate whiskers were investigated through single factor and quadric orthogonal regression experiments and regression model equation was obtained.Optimal conditions for preparing calcium sulfate whiskers with relatively larger slenderness ratio were obtainted:reaction temperature was 60 ℃,mass fraction of sulfuric acid was 90%,feeding time was 15 min,and stirring rate was about 200 r/min.Under those optimal conditions,the pure white calcium sulfate whiskers with the length of 800~1 200 μm  and diameter of 10~20 μm were obtained and the slenderness ratio  was up to 78.

Key words: calcium sulfate whiskers, hydrochloric acid, phosphoric acid