摘要
以TFT-LCD磷酸蚀刻废液为原料,重质CaCO_3和工业Ca(OH)_2为中和剂,通过二段结晶法制备饲料级磷酸氢钙,考察了结晶温度、搅拌速度、进料速度、一段/二段终点pH、CaCO_3料浆浓度、Ca(OH)_2料浆浓度、一段/二段终点停留时间等因素对磷酸氢钙产品品质的影响。结果表明,制备饲料级磷酸氢钙的优化条件为:结晶温度40℃、搅拌速度200 r/min、进料速度10 mL/min、CaCO_3料浆浓度200 g/L、Ca(OH)_2料浆浓度100 g/L、一段终点pH=3.5、一段终点停留时间0 min、二段终点pH=5.5、二段终点停留时间60 min。在优化的结晶条件下,磷酸蚀刻废液制备得到的饲料级磷酸氢钙可满足《GB/T 22549-2008饲料级磷酸氢钙》中Ⅰ型产品的要求,并且其含水率可控制在30%以下。
Feed-grade dibasic calcium phosphate（DCP） was prepared from spent phosphoric acid etching solution during the manufacture of thin film transistor liquid crystal display（TFT-LCD） by two stage neutralization, using ground calcium carbonate（CaCO3） and industrial grade calcium hydroxide（Ca（OH）2） as precipitator. Effects of crystallization temperature, agitator speed, feed speed, final pH value at the first and second stage, CaCO3 slurry concentration, Ca（OH）2 slurry concentration, retention time at the first and second stage were examined. The results showed that the optimum condition to prepare feed-grade DCP was crystallization temperature of 40~C, agitator speed of 200 r/min, feed speed of 10 mL/min, final pH value at the first stage of 3.5, final pH value at the second stage of 5.5, CaCO2 slurry concentration of 200 g/L, Ca（OH）2 slurry concentration of 100 g/L, retention time at the first stage of 0min and retention time at the second stage of 60 min. The properties of the prepared feed-grade DCP at the optimum condition can all meet the demands of the I type DCP in the national standard of GB/T 22549-2008, and the moisture content of DCP can be controlled below 30 %.
出处
《广东化工》
CAS
2017年第18期66-68,23,共4页
Guangdong Chemical Industry
基金
深圳市科技计划项目(CXZZ20150525165208062)
关键词
磷酸蚀刻废液
饲料级磷酸氢钙
TFT-LCD
含水率
spent phosphoric acid etching solution
feed-grade dibasic calciura phosphate
TFT-LCD
moisture content
