CaO-CaCl_(2)混凝沉淀结合电化学氧化法去除钨冶炼高盐废水中的氟和氨氮

Removal of Fluoride and Ammonia Nitrogen from High Salt Wastewater from Tungsten Smelting by CaO-CaCl_(2) Coagulation Precipitation Combined with Electrochemical Oxidation Method

由于不同矿石的成分组成较为复杂,导致经原矿加工的钨冶炼前段处理过程中产生大量包含各种污染物的高盐含氟、含氨氮废水。本研究首先利用钙盐混凝沉淀法对低钨交后液进行两次除氟,再采用电化学氧化法处理水中氨氮,并对不同条件下废水处理效果进行对比。结果发现,加入3.50 g/L的CaO在pH=13左右的较优条件下进行第一次除氟,可除至17.68 mg/L左右,去除率为95.1%;加入0.50 g/L的CaCl_(2)在pH=12左右的较优条件下进行第二次除氟,可将氟除至9.24 mg/L,达到《污水综合排放标准》(GB8978—1996)一级标准。除氟后废水利用电化学氧化法除氨氮,在pH=9、电流密度200A/m^(2)的较优条件下反应11min可将氨氮除至《污水综合排放标准》(GB8978—1996)一级标准。经过CaO-CaCl_(2)混凝沉淀除氟,再经电化学氧化法除氨氮后的钨冶炼废水可达标排放。

Due to the complex composition of different ores,a large amount of high-salinity wastewater containing fluorine and ammonia nitrogen,along with various pollutants,is often generated during the pre-treatment process of tungsten smelting directly processed from raw ore.This study first utilized the calcium salt coagulation precipitation method to remove fluoride from the low tungsten post treatment solution twice,and then employed the electrochemical oxidation method to remove ammonia nitrogen form water.Comparative analyses of water treatment under different conditions were conducted.The results show that the addition of 3.50 g/L CaO in the first stage can reduce fluoride level to around 17.68 mg/L under optimal conditions of pH 13,with a removal rate of 95.5%,the subsequent addition of 0.50 g/L CaCl_(2) in the second stage can reduce fluoride level to 9.24 mg/L under optimal conditions of pH 12,meeting the first level standard of the Comprehensive Wastewater Discharge Standard(GB8978-1996).After fluoride removal,electrochemical oxidation method is applied.Under optimal conditions of pH around 9 and current density of 200 A/m^(2),ammonia nitrogen can be reduced to the first level standard of the“Comprehensive Wastewater Discharge Standard”(GB8978-1996).The tungsten smelting wastewater,treated by calcium salt coagulation precipitation followed by coagulation precipitation electrochemical oxidation,can meet the discharge standards for both fluoride and ammonia nitrogen concentrations.