Research on Desliming Pretreatment and Electroflocculation Settlement Process of High Ash Coal Slurry Water and Oily Wastewater

In this study, the treatment method of high ash coal mud water and oily wastewater was systematically optimized by combining desliming pretreatment with electroflocculation and sedimentation process. The experiments used gravity settling method for desliming pretreatment and combined with electroflocculation settling process under different settling time, temperature and current density conditions, respectively. The results showed that after the desliming pretreatment, the concentration of suspended solids in the coal slurry water and the oily wastewater was reduced, and the removal rates reached 59.1% and 55.6%, respectively. Under the conditions of electroflocculation treatment with a current density of 3 mA/cm² and a treatment time of 20 min, the suspended solids concentrations of coal slurry water and oily wastewater were further reduced to 200.8 mg/L and 230.1 mg/L with removal rates of 61.0% and 48.9%, respectively. After the application of the combined process, the suspended solids removal rate of coal slurry water and oily wastewater increased to 71.4% and 68.5%, respectively, and the concentration of suspended solids decreased to 145.8 mg/L and 170.2 mg/L, respectively. With regard to the comprehensive indexes of water quality, the combined process significantly reduced the turbidity of coal slurry water and oily wastewater from 314.5 NTU and 344.4 NTU to 90.7 NTU and 105.8 NTU, respectively; electrical conductivity and conductivity of coal slurry water and oil wastewater were further decreased to 200.8 mg/L and 230.1 mg/L, respectively; the removal rate was 61% and 48.9%, respectively. 105.8 NTU; conductivity decreased from 1238.1 μS/cm and 1343.2 μS/cm to 1120.4 μS/cm and 1215.9 μS/cm, respectively; and pH remained relatively stable with small changes. This study provides a set of efficient, low-cost and environmentally friendly treatment technology for coal and oil industries, which significantly improves the production efficiency and product quality of coal preparation plants and oil fields, and has important practical application value.