线切割废砂浆中硅制取白炭黑的新工艺

介绍了废砂浆和白炭黑的研究现状,阐述了硅制取白炭黑的思想,研究了氟化铵与线切割废砂浆中硅的反应,氟硅酸铵的氨化反应以及氟化铵循环过程中的使用.结果表明:氟化反应中氟化铵质量分数40%～55%和反应温度50～60℃最佳;氨化反应pH值成核阶段不大于6.9,生长阶段不大于7.1,氟硅酸铵质量分数12%,分两次沉淀和过滤,沉淀初期,氨水滴加速率每秒2滴,末期,每秒0.5～1滴和反应温度为40~50℃效果最好;循环实验中氟化铵回收率在95%以上.本研究提出的硅制取白炭黑的工艺流程,使氟化法原料多样化,氟化反应温度低,氟化铵损失少,废砂浆回收成本低.

White carbon black production from drained slurry generated by cutting silicon crystal using a wire-saw

Based on the analysis of research progress in drained slurry and white carbon black, the preparation of white carbon black using silicon as starting material is proposed. The reaction of ammonium fluoride with silicon contained in the drained slurry generated by cutting silicon crystal using a wire-saw, the amination reaction of ammonium fluorosilicate, as well as the recycling of ammonium fluoride in the closed cycle system are investigated. Results showed that the recovering of ammonium fluoride is higher than 95% and the optimum conditions are: mass concentration of ammonium fluoride is 40%-55% and temperature is 50-60 ℃ for the reaction ammonium fluoride with the drained slurry. While for the amination reaction, the pH value is no higher than 6.9 in the nucleation stage and 7.1 in the growth stage, the mass concentration of ammonium fluorosilicate is 12% with two stages of precipitation and filtration, the dropping rate of ammonia water is 2 drop/s at the initial precipitation stage and 0.5-1 drop/s at the second precipitation stage and temperature is 40-50 ℃. This process has the advantages of diversity in starting material, low temperature, low-loss of ammonium fluoride and low-cost for reclaiming silicon from drained slurry.