氢氧化钙处理隐晶质石墨纯化后的酸性含氟废水研究

Study on the Acidic Fluoride Wastewater of Purified Aphanitic Graphite by Calcium Hydroxide

采用氢氧化钙处理隐晶质石墨纯化后的酸性高浓度含氟废水,考察了氢氧化钙用量、pH值、搅拌时间、沉降时间对废水中F-质量浓度的影响。结果表明,随着氢氧化钙用量的增加,废水中F-质量浓度先逐渐降低后基本保持不变;随着pH值的增加,废水中F-质量浓度先降低后升高;随着搅拌时间的延长,废水中F-质量浓度缓慢降低;随着沉降时间的延长,废水中F-质量浓度基本不变。其最佳处理工艺为:每100mL废水中直接加入9.00g氢氧化钙,搅拌10 min后立即过滤。此处理工艺可使废水pH值从0.98提高到7,F-质量浓度从7900mg/L降低至3.94mg/L,F-去除率达99.94%。

Using the calcium hydroxide to treat the fluoride wastewater of puiefied aphanitic graphite with a high concentration of acid. The influence of the consumption of calcium hydroxide, the pH value, the stirring time and the sedimentation time on the mass concentration of fluoride in wastewater is analyzed by respectively. The findings reveal that as calcium hydroxide scales up, the mass concentration of fluoride in wastewater basically remains unchanged after gradually dropping off, with the increase of the pH value, the mass concentration of fluoride in wastewater decreases firstly and increases subsequently, following the extension of the stirring time, the mass concentration of fluoride slowly decreases; along with the extension of the sedimentation time, the mass concentration of fluoride mainly keeps unchangeable. The optimal treatment process is as follows： 9.00 g calcium hydroxide is directly added to the wastewater per 100 mL filtered at once after stirring for 10 min, which shows that in wastewater the pH value increases from 0.98 to 7, the mass concentration ofF- decreases from 7900 mg/L to 3.94 mg/L, and the removal rate of F reaches 99.94%.