Ghana – Major Gold Deposits
Chirano is an operating open-pit and underground mining operation located in southwestern Ghana, immediately south of the Company’s Bibiani Gold Mine. Chirano was first explored and developed in 1996 and began production in October 2005. The mine comprises the Akwaaba, Suraw, Akoti South, Akoti North, Akoti Extended, Paboase, Tano, Obra South, Obra, Sariehu and Mamnao open pits and the Akwaaba and Paboase underground mines. Gold Equivalent Production in 2021 was 154,668 oz on a 100% basis
Placer Outokumpu Exploration (POE) carried out the first systematic reconnaissance exploration of the area, via stream sediment sampling, widely spaced soil geochemical traversing, rock chip sampling, then trenching and pitting of the more promising soil anomalies. This work defined several gold prospects, however POE judged that the area was unlikely to deliver the company’s minimum target object of one million ounces and the project was joint ventured to Reunion Mining Plc in May 1995.
Reunion carried out the first detailed exploration work. They extended and in-filled the soil sampling grid and excavated trenches across the better soil anomalies. Many of the trenches defined wide-zones of potentially ore grade gold mineralization and several prospects worthy of drilling were defined. Twenty five short diamond drill holes were completed, testing the Obra and Paboase Prospects. These holes confirmed that the mineralized widths and grades encountered in trenches persisted deep into the bedrock. The exploration program undertaken by Reunion focused on shallow oxide mineralization. A modest oxide gold resource was defined and preliminary metallurgical testing was completed.
Work was halted in March 1996 by a government imposed moratorium on exploration work in Forest Reserves, but in November 1997 Reunion was given permission to resume exploration under strict environmental constraints and temporary permits. Eventually they chose to farm out the project so that they could concentrate on a project in Namibia. Total expenditure by POE and Reunion from 1993 to 1998 is estimated at approximately US$2.35 million.
After technical and legal due diligence studies, CGML as a subsidiary of Red Back, proceeded with intensive exploration of the project area. Between 1998 and 2004 CGML’s work included very extensive and detailed soil geochemistry, geological and regolith mapping, trenching, ground geophysics (magnetics and induced polarization), and RC and diamond core drilling. As well as routine field exploration, CGML studied the petrography of the mineralization and associated alteration, the trace element signature of the gold deposits, the metallurgy of the lode material, local hydrology, and the geotechnical characteristics of the host rocks.
By mid-2004 all of the deposits had been drilled sufficiently to define their gold resources. The company had collected 15,000 soil samples, dug 81 trenches with a total length of 4,063 meters, and completed 605 drill holes totaling 60,489 meters. A prefeasibility study for establishing a mining operation was completed by CGML in 2000, and a Bankable Feasibility Study was completed in early 2003. Pre- development exploration expenditure totaled US$17.5 million.
Kinross acquired its ownership in the Chirano Gold Mines Limited on September 17, 2010 upon completing its acquisition of Red Back Mining Inc.
New discoveries by CGML have brought the number of known Chirano gold deposits to eleven (eight open pits and six undergrounds), distributed along a strike length of ten kilometers.
Exploration has continued both during and after the development of the mine. Most significantly, drilling below Akwaaba, Paboase, Akoti, Tano, Suraw, and Obra open pits have delineated higher grade underground resources. Further drilling below the pits has also identified underground targets at Sariehu and Mamnao. Other open pit has been discovered on a parallel western splay structure at Mamnao and currently being mined as part of the Mamnao enclave open pit complex.