Investigation on the possibilities for copper recovery improvement through additional treatment of the bulk concentrate at the DPMCh flotation plant (Bulgaria)

Abstract

The Chelopech gold-copper mine is located in west-central Bulgaria on the southern flank of the Balkan Range at Chelopech village. It can be classified as a “gold-enargite high-sulphidation epithermal mineralizing system”. The objective of this work was to study the possibilities to improve the performance of the Cu Selective Flotation stage in terms of grade and recovery through re-grinding the Bulk Concentrate. An average P80 = 37.6 ± 7.8 µm for the re-ground Bulk Concentrate has proved to enhance the kinetics (Km) and selectivity (S.I) of the valuable copper bearing minerals against gangue. However, the re-grinding process poses some challenges in terms of recovery. Changing the pH and conditioning time with lime before the Cu selective flotation stage proved to have effects in the grade and selectivity of the Cu concentrates, but little improvements in terms of recovery. The increment in Cu recovery using higher collector (PAX) dosage demonstrated that part of the difficulties in improving the recovery can be related to the higher specific surface of the re-ground particles, partial removal of the collector from the surfaces by attrition during the re-grinding process or even partial decomposition of the collector due to the strong mechanical forces. Preliminary tests with alternative collector regime (AEROFLOAT® 238 Promoter and AERO® MX-5148 Promoter) added to the standard PAX dosages, showed some little or none improvements in terms of grade and recovery; and when they did; the improvements were proportionally lower than the improvements achieved with similar amounts of additional PAX. Preliminary tests for splitting the re-ground Bulk Concentrate through hydrocycloning in a fine fraction (< 20 µm) and a coarse fraction (> 20 µm) and then floating them separately showed some improvements in terms of recovery, even when the splitting process efficiency was low. Those tests were performed with standard collector (PAX) dosage; and therefore, further tests should be envisaged to prove the efficiency of this alternative flowsheet in conjunction with a higher collector regime.