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

  • Luan Pham VAN
  • Phu Nguyen NGOC
  • Ha Le VIET


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