minerals Review Gravity Concentration in Artisanal Gold Mining Marcello M. Veiga * and Aaron J. Gunson Norman B. Keevil Institute of Mining Engineering, University of British Columbia, Vancouver, BC V6T 1Z4, Canada;
[email protected] * Correspondence:
[email protected] Received: 21 September 2020; Accepted: 13 November 2020; Published: 18 November 2020 Abstract: Worldwide there are over 43 million artisanal miners in virtually all developing countries extracting at least 30 different minerals. Gold, due to its increasing value, is the main mineral extracted by at least half of these miners. The large majority use amalgamation either as the final process to extract gold from gravity concentrates or from the whole ore. This latter method has been causing large losses of mercury to the environment and the most relevant world’s mercury pollution. For years, international agencies and researchers have been promoting gravity concentration methods as a way to eventually avoid the use of mercury or to reduce the mass of material to be amalgamated. This article reviews typical gravity concentration methods used by artisanal miners in developing countries, based on numerous field trips of the authors to more than 35 countries where artisanal gold mining is common. Keywords: artisanal mining; gold; gravity concentration 1. Introduction Worldwide, there are more than 43 million micro, small, medium, and large artisanal miners extracting at least 30 different minerals in rural regions of developing countries (IGF, 2017) [1]. Approximately 20 million people in more than 70 countries are directly involved in artisanal gold mining (AGM), with an estimated gold production between 380 and 450 tonnes per annum (tpa) (Seccatore et al., 2014 [2], Thomas et al., 2019 [3], Stocklin-Weinberg et al., 2019 [4], UNEP, 2020 [5]).