TORONTO (miningweekly.com) – Vancouver-based Greystar Resources, which has just completed a prefeasibility study on its flagship Angostura gold/silver mine, in northeastern Colombia, expects its newest big shareholder, the International Finance Corporation (IFC), to play a key role in financing the project, president David Rovig said on Wednesday.
The Angostura openpit mine could produce an average of 511 000 oz of gold and 2,3-million ounces of silver a year, over 15 years.
The project, which is touted by Greystar as one of the biggest undeveloped gold deposits in the world, contains measured and indicated resources of 11,5-million ounces, plus 3,5-million ounces in the inferred category.
A bankable feasibility study should be completed by September or October this year, Rovig said in an interview.
If all goes to plan, the company is hoping to start construction in 2010, with first production in 2012.
Last week, the IFC invested some C$12,04-million in Greystar, in return for shares and warrants in the company. The IFC now owns 12,49% of the company's outstanding common shares, which would increase to 19,99% if the warrants are fully exercised.
Rovig said that the proceeds from the IFC investment, plus about C$25-million already in the firm's treasury, will easily fund the completion of the bankable study.
The project itself will be financed through a combination of debt and equity, and the IFC has indicated it will syndicate the debt portion with other development finance bodies and commercial banks, he said.
Start-up capital costs for Angostura are estimated at $638-million, with additional sustaining capital of $307-million, including the construction of a concentrator.
The prefeasibility study envisages a 70 000 t/d conventional heap leach operation, producing a total of 4,2-million ounces of gold over the mine life, plus a 5 200 t/d conventional milling and flotation process, which would produce a total of 3,5-million ounces of gold in concentrates.
The average cash operating cost, excluding byproduct credits from silver, is estimated at $391/oz.
The operation will start-up by processing oxides, transitional and low-sulphide material by heap leaching, but will begin producing flotation sulphide concentrates from higher-grade, high sulphur mineralisation in the third year of operation.
As part of the feasibility study, Greystar plans to relook at the gold price estimates used in the initial study, as it believes the assumptions made in the prefeasibility study may now be “conservative”.
The base case scenario for the prefeasibility study was calculated using a gold price of $700/oz for the first three years of operation at Angostura, and $650/oz thereafter.
The firm will also consider using a fixed primary crusher instead of a semi-mobile, to improve the economics of the project, and is testing three different process streams for the recovery of gold and silver from the flotation concentrates: roasting on site, bio-oxidisation on site; and super-fine grinding and tank leaching.
Greystar shares gained 5,4% on Wednesday, to C$3,91 apiece by 13:35 in Toronto.