Abstract
In this paper, the effects of water circulation on flotation performance of a polymetallic sulphide ore containing, chalcopyrite, galena, sphalerite and magnetite was investigated. The study evaluated the effectiveness of recycling process water in 15 flotation cycles and how the different water constituents affect the recovery and grade of the valuable metals in particular copper, lead and zinc as a way of solving the problems associated with water supply and discharge in mining industries particularly in the metallurgical plants. The flotation experiments were conducted using : pH of 4.5, 1200 rpm, 0.025 g of SEX, 0.025 g of Cu2SO4, 0.025 g of CaO , 2.5 drops of MIBC, conditioning time of 2 minutes and flotation time of 5minutes. The flotation test results indicated that the grade of both Cu and Pb increased from 0.19 to 0.36 % and 3.17 to 4.14 % respectively. The recoveries were 82.44% Cu and 81.82% Pb. Zn grade decreased from 3.90 to 1.14% at a recovery 45.48%. All the studied parameters that affect water quality have increased as the number of flotation cycles increased except for pH which decreased as a result of sulphuric acid added and they all significantly influenced the performance of the flotation process. The pH decreased from a value of 6.4 down to a range of 3.42-3.81 while the electrical conductivity increased from 0.23 to a range of 2.78-4.92 mS/cm. The total suspended solids and total dissolved solids increased from 72-968 mg/L and 115.5-2460 mg/L respectively whilst the Mg and Ca contents increased from 7.19-33.1 mg/L and 13.41-97.75 mg/L respectively. Process water can be circulated several cycles in a flotation process of a polymetallic ore before it can significantly affect the flotation performance.