The Key Technology Of The Preparation Of Gypsum Whisker

The appropriate conditions of preparing gypsum whisker in the system of wet process phosphoric acid and hydrochloric acid-tungsten slag were explored. In the system of wet process phosphoric acid, when the reaction temperature was 100℃, reaction time was 30 minutes, stirring speed was 300r/min, the amount of CPAM was 6,0 mg/L, the sulfuric acid concentration was 50%, the appearance of the generated gypsum whisker was thin rod, diameter was between 1 to 3 μm, length to diameter ratio could reach more than 50, In the system of hydrochloric acid-tungsten slag, when the reaction temperature was 95 ℃, the crystallization was after recycling the phosphor and iron, the amount of CPAM was 8,0 mg/L, diameter was between 2 to 4 μm, length to diameter ratio could reach more than 30.Through the experiment, we found that the initial concentration of calcium chloride solution had a big effect on the growth of gypsum whisker, the most suitable mass fraction was 15%; The effect of impurities on the gypsum whisker was also explored, results showed that, the change of the concentration of chloride ion had little impact on the gypsum whisker; Na+ and Al3+ could make whisker become thicker, so the length to diameter ratio decreased; the right amount of Mg2+ and Fe3+ were good for the growth of gypsum whisker, in the process of preparing gypsum whisker, adding quantity should be respectively less than 0.3% and 0.2%; the presence of phosphorus was good for the growth of gypsum whisker.In order to reduce the solubility of gypsum whisker in the water, the titanate coupling agent JC-981 was used for the surface modification of gypsum whisker. The right conditions were:the modifier dosage was 2.0%, the initial slurry concentration was 100g/L, modification temperature was 100℃, modification time was 10 minutes, the stirring speed was 300r/min, the drying temperature was 100℃, the drying time was 2 hours. Under the conditions of the above, the modified rate could reach 65.6%. When dissolved in the water, the calcium content was 0.0678%, which was 32.6% of the unmodified gypsum whisker.