LITERATURE REVIEW — Yuma completes feasibility study — Delays caused by efforts to gain approvals for process water

A bankable feasibility study is in hand for Yuma Copper’s (YUM-V) Tuina copper project, 60 km southeast of Chuquicamata, in northern Chile.

Prepared by Bateman Engineering in association with New Baron Leveque and Parsons, the study outlines plans for a 12,000-tonne-per-year solvent extraction-electrowinning project. Construction

is planned to start later this year, with startup in late 1998.

The project has proven (80%) and probable (20%) reserves of 9.4 million tonnes averaging 1.12% copper, plus an additional 3.5 million tonnes classified as inferred. The overall stripping ratio has been calculated at 1-to-1.72.

The potential to expand reserves and thereby extend the project life is described as “excellent.”

The plant design incorporates 2-stage crushing, followed by conventional heap-leaching. The pregnant solutions will be collected and clarified, followed by treatment using conventional solvent extraction methodology to produce a rich electrolyte that will be processed into copper cathodes using conventional extraction technology. Copper recovery is expected to be more than 85%.

Yuma is in the process of arranging financing for the project, development of which had been delayed by the lengthy procedure involved in gaining approvals to obtain process water. Those permits were secured earlier this year. Power will be obtained through an overland transmission line.

Basic engineering, yet to be completed, is expected to lower capital and operating costs.

Tuina is the first of three segments of Yuma’s Sierra Gorda project to be developed using modern technology. Sierra Miranda and Dona Ada are in operation and together produce more than 7,000 tonnes (15.4 million lb.) of copper per year. The copper is contained in solutions and precipitate sold under contract to Anglo-American and Refimet.