Design of a tailings impoundment dam for artisanal and small scale miners :

Abstract

Mineral processing involves the-separation of valuable minerals from gangue minerals through crushing, grinding and concentration. During gravity concentration huge amounts of tailings are discharged to the environment causing pollution of surface and underground water sources. The main objective of this study was to design an impoundment dam to contain the tailings. The methods of Tailings disposal, types of impoundments, Tailings discharge methods; basic structures, for retaining tailings in impoundment, embankment construction methods, Tailings impoundment design and basic design concepts, major components of dams have been described in the literature review. The tailings were characterized by analyzing the samples from the study area in the laboratory for geotechnical and geochemical parameters and MS Excel sheet 2010 was used in analyzing the col1ected data. To know the quantity of tailings being discharged to the environment per year the volumetric flow rate was determined from the field which helped in getting the mass flow rate of the tailings and then the volume to be contained per year was determined. The design of the tailings dam was done using the relevant formulas and equations. The tailings dam was designed using ANCOLD, 1999 guidelines for dam design and AutoCAD 2016 software was used in generating the design drawings. The size of the impoundment area will accommodate the tailings that will be discharged for a given dam life. Finally, economic evaluation of the system was done using benefit cost ratio approach and the project seemed to be economically viable and thus should be implemented to reverse the current trend of open tailings disposal which is subjecting the environment to land degradation and water pollution.