Geometallurgical methodology to improve the small-scale gold mining process of the Gualconda mine in Nariño – Colombia

Abstract

In the gold beneficiation processes, the degree of particle size reduction is strongly influenced by the size and shape of the mineral species associated with the economically important metals. The capacity, energy consumption, and costs of the gold-bearing ore processing depend mainly on the operational parameters of the equipment of comminution and gravimetric concentration; therefore, it is essential to characterize the liberation degree of the minerals of interest as function of particle size. The small-scale mining beneficiation plants usually do not consider the liberation of sulfide particles as a requirement to define the grinding size reduction ratio, this is determined empirically, evaluating in which size a higher percentage of gold recovery is obtained. The methodology proposed in this paper constitutes a low cost analytical technique, using the free software IMAGE-J, to determine the appropriate liberation size for sulfide particles and associated gold particles, as well as the size distribution of gold ore particles. Additionally, the Molycop-Tools software was used to simulate the best grinding strategy based on the liberation results obtained. Through the methodology of automatic image analysis to determine the liberation degree of sulfides, the mineralogical characterization, and the recommendation of a metallurgical processing strategy for the gold-bearing ore based on steady-state simulations, it was possible to establish the appropriate parameters of ball mill grinding and gravimetric concentration of the Gualconda mine in the Department of Nariño, in order to improve the gold recovery and increase the plant capacity.