Dominy, S.C., and Phelps, R.F.G. (2002) Gold extraction at the Gwynfynydd Mine, North Wales, United Kingdom: a case study of environmentally sustainable mineral processing within a national park. In: Green Processing 2002 (4/2002) pp. 225-232. From: International Conference on the Sustainable Processing of Minerals 2002, 29-31 May 2002, Cairns, QLD, Australia.

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Abstract

The former Gwynfynydd gold mine is located within the heart of the Snowdonia National Park, North Wales, United Kingdom. The black shale-hosted quartz reefs have intermittently produced more than 50 000 ounces of gold since 1863. Its most recent period of operation by Wclsh Gold PLC was between 1992 and 1999 when it extracted 10 000 tonnes annually from a total resource base of 180 000 tonnes. A historical mining grade of 15 grammes/tonne was recovered from the Chidlaw Reef on which all production was based. Erratically distributed gold pockets hosted in the footwall zone of a 3 - 6 111 wide quartz reef characterise the mineralisation. The gold exhibits a high-nugget effect and as a consequence the accurate determination of tonnage and grade was difficult. Production was undertaken by overhand shrinkage sloping. Due to its location within a National Park certain environmental constraints were placed on the operators. The principal requirement or planning permission was that processing should take place above ground and not involve chemicals. As a result, an underground mill based on physical separation methods was constructed in response to these environmental constraints. Much of the mine discharge is related to the flow of rainwater through the workings from surface openings on the reefs. Discharge from the underground milling facility was enhanced in various metals, particularly zinc, though was reduced to legally acceptable levels using liming tanks prior to discharge into the River Muwddach, The company was required to monitor and treat all water discharged from the mine before it reached the river. The mine closed in l 999, since which time a tip re-processing has continued as part of an environmental remediation and gold supply program.

Item ID:	14648
Item Type:	Conference Item (Research - E1)
ISBN:	978-1-875776-92-4
Date Deposited:	16 Oct 2017 03:02
FoR Codes:	04 EARTH SCIENCES > 0403 Geology > 040307 Ore Deposit Petrology @ 100%
SEO Codes:	84 MINERAL RESOURCES (excl. Energy Resources) > 8402 Primary Mining and Extraction Processes of Mineral Resources > 840205 Mining and Extraction of Precious (Noble) Metal Ores @ 100%
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