Electrochemical deposition removal of mine water hardness in the western coal-mining region
摘要
The electrochemical deposition method was used to remove the hardness of mine water of the Daliuta Coal Mine in Shendong Mining Area. The effect of cathode material structure and morphology on the hardness removal of mine water was analyzed. The results showed that the abrasive structure of the electrode surface was more conducive to the removal of calcium and magnesium ions by electrodeposition, and the reticulated cathode could further enhance the electrodeposition efficiency. The effects of parameters such as initial hardness, current density, number of electrodes and pH on the electrochemical removal of mine water hardness were also investigated. Under neutral conditions, with an initial hardness of 310 mg/L, a current density of 2-6 mA/cm2, and a cathode to anode electrode are a ratio of 3∶2, mine water hardness could be removed by 90% within 180 min. With the decreasing hardness/bicarbonate alkalinity, the hardness removal efficiency increased. The interaction of different factors on the effect of electrochemical hardness removal efficiency was investigated by response surface method, and it was found that the order of the interaction effects on the water softening efficiency was as follows:current density and initial hardness>initial hardness to hardness and bicarbonate alkalinity>current density to hardness and bicarbonate alkalinity. Under the optimized conditions of initial hardness of 795.6 mg/L, hardness/bicarbonate alkalinity of 0.668 and current density of 4.74 mA/cm2, the hardness removal efficiency of mine water could reach 99.91%, and the hardness removal efficiency of 99.54% was obtained from the validation test, with a relative error of 0.37%. The results of SEM, EDS and XRD analysis showed that the main crystalline form of the cathodic deposit was calcite, which was mainly composed of irregularly shaped, 2-10 μm calcium carbonate crystals.