Geometallurgical analysis on the metallurgical behavior of the ore originating from selected block of the DPM Chelopech underground mine in Bulgaria

Abstract

Geological complexity of the Dundee Precious Metals (DPM) Chelopech mine, Bulgaria has motivated the proposal and development of a geometallurgical characterization of the new block 103, scheduled to start production in the second half of 2017. This project aimed to achieve such characterization by performing metallurgical test on samples selected from the block, such as lab scale batch sulphide flotation with copper and pyrite cleaning stages, drop weight and batch grinding tests. Optical microscopy, X-ray diffraction and ZEISS Mineralogic Mining Automated Mineralogy were used to identify mineralogical features in the samples tested. A geometallurgical methodology using a principal component analysis and linear modelling was followed. Sulphosalts recovery, Axb index and operating work index were correlated with mineral characteristics. As a result it was possible to identify that enargite, tennantite and chalcopyrite contents and grain sizes controlled copper recovery in the flotation circuit; gold recovery in the copper cleaning stage was influenced by sulphosalts – pyrite association. Pyrite, chalcopyrite and sulphosalts content controlled the recovery of pyrite in the pyrite cleaning stage. Gangue minerals such as quartz, kaolinite, alunite and enargite/tennantite controlled impact breakage and operating work index; however, it is believed that texture played an important role in rock comminution testing. A proposed sub-division of the block 103 in two geometallurgical domains, East and West, was performed following a previous delimitation by the geological team of DPM Chelopech. Further sub-domaining should be performed using extra sampling and tests.