Enhancement of the Efficiency of Flotation Tailings Dewatering on the Belt Presses Using New Combinations of Flocculants and Coagulants

摘要

The practice of coal flotation tailings dewatering shows that the performance of belt press filters in the said operation is significantly determined by efficiency of flocculation conditioning of suspension of tailings being dewatered. This operation is carried out after thickening of suspension and, as a rule, consists in consecutive treatment of slurry with anionic and cationic flocculants. However, in a number of cases the application of any combination of anionic and cationic flocculants does not bring to a satisfactory performance of belt press filters. The tailings with high yield of fine clay particles are the most difficult to treat. In the present paper the regimes of tailings treatment at stages of thickening and dewatering have been investigated. For thickening operation the parameters of suspension mixing with flocculant have been determined. For tailings conditioning before dewatering the experimental results of using new combinations of reagents have been obtained. It has been shown that the consecutive treatment of flotation tailings before dewatering with two cationic flocculants, one of which has low molecular weight and high quantity of the charged functional groups, and another one has high molecular weight and low quantity of the charged functional groups, allows in a number of cases to obtain an easily dewaterable cake, when conditioning of tailings with a combination of anionic and cationic flocculants does not bring to satisfactory dewatering. The other way to increase the efficiency of tailings conditioning is consecutive treatment of suspension with a heterocoagulant, anionic and cationic flocculants. The parameters of tailings conditioning using the above mentioned methods have been experimentally determined. As a result of application of new combinations of flocculants and coagulants at reasonable rates of mixing the cake specific resistance is reduced by 3 ～ 5 times as compared with the results obtained using the combination of anionic and cationic flocculants.