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A Lantern Retort for Small-Scale Gold Extraction
International Journal of Environmental Protection and Policy
Volume 2, Issue 5, September 2014, Pages: 161-167
Received: Aug. 25, 2014; Accepted: Sep. 5, 2014; Published: Sep. 20, 2014
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Authors
Richard Kwasi Amankwah, Mineral Engineering Department, University of Mines and Technology, Tarkwa, P. O. Box 237, Ghana
Grace Ofori-Sarpong, Mineral Engineering Department, University of Mines and Technology, Tarkwa, P. O. Box 237, Ghana
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Abstract
Two major retorts used in small-scale gold mining operations to reduce mercury emissions, during amalgam distillation are the steel and thermex retorts. Steel retorts are not very popular due to the reported darkening of gold after retorting. In addition, its opaque nature prevents miners from observing the process directly. The Thermex glass retort introduced by the United Nations Industrial Development Organisation (UNIDO) is also not patronised due to the extended heating periods resulting from the low thermal conductivity of glass. This paper describes a new retort, the Lantern retort, a combination of highly conductive steel with transparent glass, and therefore, a potential solution to the above concerns. The Lantern retort has a shorter warm-up and amalgam distillation time, and the rate of heating is 1.81oC/s while that of the Thermex is 1.49oC/s. For an amalgam of mass 20 g, 900 s was required to carry out complete distillation in the Lantern retort as against 2100 s in the Thermex. The height of the distillation column of the Lantern retort required to reduce mercury loss to below 1%, as it is with the Thermex retort, is 2.5 cm. Other advantages of the Lantern retort are that, it is less expensive and can withstand the harsh terrain of small-scale gold mining.
Keywords
Small-scale Mining, Gold, Mercury, Amalgamation, Retorting, Lantern Retort
To cite this article
Richard Kwasi Amankwah, Grace Ofori-Sarpong, A Lantern Retort for Small-Scale Gold Extraction, International Journal of Environmental Protection and Policy. Vol. 2, No. 5, 2014, pp. 161-167. doi: 10.11648/j.ijepp.20140205.13
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