At this link you will find the program and abstracts from a past Conference of Metallurgists. You can purchase the proceedings, but they are terribly expensive. To keep you informed and help you decide, here are my edited (shortened) versions of abstracts of papers that caught my attention.

GALVANOX – a novel galvanically-assisted atmospheric leaching technology for primary copper concentrates
D.G. Dixon, D.D. Mayne, University of British Columbia,
K.G. Baxter, Bateman Engineering

A novel technology for leaching copper from primary copper concentrates takes advantage of the galvanic couple between pyrite and chalcopyrite to ensure rapid and complete oxidation of chalcopyrite under mild conditions in acidic iron sulfate solution, without the need for microbes, ultrafine grinding, or chemical additives such as chloride, nitrate, or surfactants. Copper recoveries of 98% or greater can be achieved at 80°C under atmospheric conditions in as little as 4 hours of residence time.


Analysis of heap leach processes with modeling and simulation tools
J.E. Gebhardt, A. Hernandez, Process Engineering Resources Inc.,
M. Cross, C.R. Bennett, D. McBride, University of Wales Swansea

A phenomenological model developed within a computational fluid dynamic software framework provides a general heap leach modeling tool that describes reactive dissolution and fluid flow through the stockpile. A one-dimensional form of the model is used to parameterize the kinetic leach reactions for a mixture of copper sulfide and oxide minerals against data from operational leach tests. A two dimensional version of the model provides a means to investigate the effects of irrigation rate, lift height, air injection, bacteria limitations, and other factors on recovery and pregnant leach solution concentrations.


Solution management at Mantoverde Division of Anglo American Chile
U. Troncoso, C. Pérez, G. Zárate, Anglo American Chile

Mantoverde is a heap leach-SX-EW operation that was commissioned in December 1995 at a production rate of 42,130 ton of copper per year and 5.4 million ton of ore per year. Copper production has been steadily increased to reach 62,000 ton in 2005. Several improvements in the heap leach process have been implemented to cope with the higher ore throughput and copper production. However, the solvent extraction plant has remained unchanged which has resulted in a lower availability of raffinate solution and, as a consequence, in longer leach cycles. Different studies have been undertaken in order to optimize the solution management system at Mantoverde, including column test work aimed to reduce the leach cycle and solvent extraction plant modifications aimed to increase the raffinate solution availability.


Impact of heap operational changes on Zaldivar Copper production
S.C. Bouffard, Barrick Technology Centre,
D. Flores Godoy, Compañia Minera Zaldívar

Barrick’s Zaldívar operation in Chile produces copper by heap leaching, solvent extraction, and electrowinning. The heap consists of a dynamic pad, and its stacking and operating conditions have changed over its 11 years of operation. These changes have included pad re-mining midway through the cycle, tightening of the irrigation drip lines, an increase of the coarseness of the particles, and an increase of the heap height. Field tests demonstrated that neither re-mining nor tightening the irrigation grid added value for both low and high grade oxide and sulfide ores. The P80 of the feed ore was increased by 0.8 mm, which did not reduce the copper recovery of oxide and sulfide ores. The increase of the heap height above 8 m lowered moderately the copper recovery from sulfide minerals, and very slightly the recovery from oxide minerals. Despite the lower recovery, the higher tonnage stacked in the taller heap increased the copper output. Optimizing the chemistry of the agglomeration and feed solution holds more promise for increasing the copper recovery than the above physical changes.


Agglomeration for copper heap leaching
K.A. Lewandowski, S.K. Kawatra, Michigan Technological University

Agglomeration of ore used in heap leaching allows for the immobilization of fine particles that would otherwise migrate and cause permeability problems in the heaps. For copper ore, binders are needed in order to make stable agglomerates. However, the majority of binders break down when introduced to an acidic environment, allowing fine particles to be released from the agglomerate surfaces. These particles migrate through the heap impeding solution flow, leading to a decrease in metal recovery rates. The authors have developed a series of testing procedures to determine the acid resistance of several binders. Only five binders were shown to be acid resistant in soak tests, decreasing fines migration by up to 93%, compared to tests which were agglomerated with leach solution, raffinate, as a binder.


Searching for the optimal heap leach application rate
O. Bernal, G. Velarde, Sociedad Minera Cerro Verde S.A.A

The Sociedad Minera Cerro Verde S.A.A, a subsidiary of Phelps Dodge Mining Company, operates a copper mining facility located in southern Peru. This "mine-for-leach" operation currently produces 90,000 mtpy of copper cathode from secondary sulfide ore utilizing crushing, leaching, solvent extraction and electrowinning processes. The leach solution handling and application rates have undergone constant development over the years. This paper discusses the improvements in leach application designed to: 1) satisfy the needs of the “lixiviant request rate”, which requires the use of application rates as low as 3.5 L/h/m2 and as high as 15 L/h/m2 with variable rest periods according to the leach kinetics, and 2) alleviate the poor solution distribution on the surface of the leach heaps inherent to drip emitters. Low application rates result in poor surface solution distribution and the formation of upside down cones of dry, non-leached material in the top meter of stacked ore, with heavy jarosite and iron salt precipitation; moreover, ferric iron is lost as insoluble precipitates.


Bioleaching of chalcopyrite by the thermophilic archaean acidianus brierleyi in batch and continuous-flow stirred tank reactors
Y. Konishi, N. Saitoh, T. Nomura, Osaka Prefecture University

This paper reviews the mechanism and kinetics of bioleaching of chalcopyrite by the thermophilic archae Acidianus brierleyi in batch and continuous-flow reactors


Acid generation by in-situ sulfur biooxidation for copper heap leaching
P.G. West-Sells, Western Copper Corporation,
S.C. Bouffard, Barrick Technology Centre,
A.F. Tshilombo, Dynatec Corporation,
A. Bruynesteyn, Westcoast Biotech Ltd.

At Barrick’s Zaldívar Copper Mine in Chile, the addition of sulfuric acid to the ore going to heap leaching is a major expense. A process in which a portion of this acid is replaced by elemental sulfur added to the heap has been developed by Barrick and Westcoast Biotech that has the potential for significant cost savings. Initial shake flask tests with plant raffinate solution indicated that oxidation of elemental sulfur by a culture of sulfur-oxidizing bacteria, some indigenous to the Zaldívar heap, showed a significant lag period. This lag period could be reduced by dilution of the raffinate, but dilution would not be economical to implement at Zaldívar. Short (0.75 m) column tests indicated that after the initial lag period, sulfur biooxidation occurred steadily and the acid requirement for obtaining the same copper recovery as the control without sulfur was reduced by as much as 13 kg/t.