Browsing by Author "Miller, Jan D."

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Evaluation of Stucco Binder for Agglomeration in the Heap Leaching of Copper Ore
(Pergamon-elsevier Science Ltd, 2011) Kodali, Phanindra; Depci, Tolga; Dhawan, Nikhil; Wang, Xuming; Lin, C. L.; Miller, Jan D.
It is known that the presence of excess fines in heap leaching operations may cause low recovery due to reduced heap permeability and/or channeling of lixiviant flow. These problems are mitigated to some extent by agglomeration pretreatment prior to heap leaching. Sulfuric acid leach solution is the conventional liquid bridge used for copper ore agglomeration, but these agglomerates exhibit poor stability when compared to the agglomerates formed using stucco binder, calcium sulfate hemihydrates, CaSO(4)center dot 1/2H(2)O. Results obtained from agglomeration experiments on the Zaldivar ore reveal that the stucco hydration reaction provides the agglomerates with more stability, increased size with less release of fines, and better permeability of the packed agglomerate bed. A phase diagram has been constructed to identify preferred agglomeration conditions. Finally a proposed description for the action of stucco binder during the agglomeration process is presented and discussed. (C) 2011 Elsevier Ltd. All rights reserved.
Evaluation of Stucco Binder for Agglomeration in the Heap Leaching of Copper Ore (Vol 24, Pg 886, 2011)
(Pergamon-elsevier Science Ltd, 2011) Kodali, Phanindra; Depci, Tolga; Dhawan, Nikhil; Wang, Xuming; Lin, C. L.; Miller, Jan D.
Particle Damage and Exposure Analysis in Hpgr Crushing of Selected Copper Ores for Column Leaching
(Pergamon-elsevier Science Ltd, 2011) Kodali, Phanindra; Dhawan, Nikhil; Depci, Tolga; Lin, C. L.; Miller, Jan D.
In mining operations, jaw and gyratory crushers are generally used for primary crushing, and cone crushers are used for secondary crushing. During the past decade, however, high-pressure grinding rolls (HPGR) are being considered due to potential processing benefits such as energy savings, improved exposure/liberation and particle weakening. At this time there is no detailed quantification of particle damage and downstream benefits from HPGR crushing are uncertain. In the present research, copper ores (copper oxide ore and copper sulfide ore) were crushed by a jaw crusher and by HPGR and the products were evaluated for particle damage and copper grain exposure by X-ray computed tomography. Column leaching was done to determine the rate and extent of copper recovery. X-ray computed tomography analysis and laboratory column leaching experiments for copper oxide ore revealed that products from HPGR crushing have more particle damage and higher copper recoveries when compared with products of the same size class from jaw crusher crushing. Generally the copper recovery from column leaching of the oxide ore was found to be dependent on the extent of grain exposure, which increases with a decrease in particle size. In the case of the copper sulfide ore, copper recovery was found to be independent of the crushing technique despite the fact that more particle damage was observed in products from HPGR crushing. This unexpected behavior for the copper sulfide ore might be due to the high head grade and strong leach solution. Column leaching results also show that about 80-90% of the copper was recovered from the copper sulfide ore in a relatively short leaching time irrespective of crushing technique. As expected, copper recoveries improved with a decrease in the particle size of the copper sulfide ore as exposure of copper mineral grains increased. (C) 2011 Elsevier Ltd. All rights reserved.