选煤废水（CPW）混凝过程中Ca2＋作用特性研究

用硫酸钙和硫酸铝作凝聚剂、PAM作絮凝剂对同一选煤废水（CPW）做混凝试验，测定电动电位和澄清水的SS。通过试验数据和试验现象的分析认为Ca2＋和Al3＋的作用机理不同。Ca2＋是和煤粒表面通过化学键发生化学吸附，即在双电层内产生定位离子吸附，既改变了煤粒的表面电位，又改变了电动电位。考电位随cah浓度的增大而降低，但降幅不大。Ca2＋被沉淀物带走的较少，澄清水中含有大量可循环利用的Ca2＋。必须保证废水体系中Ca2＋浓度足够高才能使Ca2＋具有足够强的与其他离子（如Al3＋、H＋、Na＋、K＋）的竞争性。Ca2＋能降低PAM的利用效率。

Study on the role of Ca2+ in coagulation process clarifying coal preparation waste water (CPW)

The calcium inorganic salts have become a coagulant to clarify coal preparation wastewater（CPW） in recent years, but the mechanism of action is unknown. Made clarifying CPW test using coagulant of CaSO4 or Al2 （SO4） 3 and the flocculant of PAM, the electrokinetic potential of mine drainage and the SS of clarified water are determined. The experimental results show that there is different effect mechanism between Ca2＋ and Al3＋. Ca2＋ being locative cation will be absorbed to the surface of coal particle in the electrical double layer by chemical bond and the surface potential and electrokinetic potential are changed. The electrokinetic potential will be reduced when the density of Ca2＋ is amplified, but the dropping range was not much. The Ca2＋ being taken away by the sediment is smaller. In clarified water Ca2 ＋ amount is bigger in endless cycles in the slurry system. The content of Ca2＋ was must enough to use in compete with other cation （Al3＋ ,H ＋ , Na ＋ , K ＋ ）. Ca2＋ can make the PAM efficiency cut down.