Rational grinding circuit for siliceous apatite ore type III of Lao Cai Vietnam

Apatite ores type III of Lao Cai area, Vietnam is a class ofweathered sileceous apatite ores, which may have most variable compositionand primary slime content according to the weathering level and location.The three operating flotation plants use similar single-stage grinding circuitsto process the highly weathered sileceous apatite ores and to achieve theconcentrate grade requirement of 31% P2O5 with the aimed averagerecovery of about 70%. Single stage grinding circuits have worked well inthe past as the designed criteria were achieved, however, mine productionhas increased sharply and deeper ores are being mined recently, so that thematerial composition of the run of mine ores have become more complicatedand are the ores become more difficult to be floated. As a result, processingcriteria of these plants become critically unstable and low. The study is toinvestigate the suitabity of two-stage grinding circuits for Lao Cai apatiteore type III. The report presents the results of the study on middlingsregrinding of hard floatable apatite samples of Bac Nhac Son flotation plant,where high loss of valuable apatite has occured due to low grindingperformance. Research results show that regrinding of all middlings to thefineness of 75% -0.04mm not only improves recovery but also help tostabilize technological operations and their processing criteria. The finalconcentrate grade of more than 31% P2O5, tailings content of less than 5%P2O5 and recovery of over 70% were achieved.