Perpustakaan Digital ITB

North and South concentrator is part of concentrating division PT Freeport Indonesia located in MP74 Tembagapura Papua. Gold recovery at North and South concentrator is below target. Increasing of gold prices lately, have encourage concentrating division to improve gold recovery at North and South concentrator. Improvement of gold recovery by 1% will increase about $4.63M annual revenue. Plant surveys indicate that 56% of gold in flotation feed distributed in particle size below 53μm. There is 58.8% of recoverable gold size below 212μm present in the cyclone underflow. Circulating load of gold in grinding circuit was very high (1000%). The large portion of coarse liberated gold in cyclone underflow suggest that sliming of gold is occurring in the ball mill and the large portion of very fine gold in cyclone overflow (flotation feed) is result of overgrinding in the ball mill. Low gold recovery at North and South concentrator mostly relate to large portion of very fine gold in process flotation. This very fine particle is very difficult to recover in flotation process. Very fine particles are resulted from overgrinding before sent to flotation process. Therefore, recovering coarse and liberated gold in the grinding circuit and avoiding overgrinding, presents an opportunity to reduce gold losses in flotation system and increase overall gold recovery. Four alternative business solution are discussed: install pre-flotation cell, install sluice box, install knelson concentrator, and install flash flotation. Financial analysis shows that install flash flotation, is the most beneficial alternative. Install flash flotation require initial investemt about $25M and installation time about 1 year periode. NPV(15%) of project is $32M. Laboratory test indicate that potential recovery improvement about 4.7% can be achieved.