Leaching and Recovery Kinetics of Gold Fine in Percolation Leaching with and without Agglomeration

Abstract

The extraction of gold in PAD leaching is an operation that is increasingly used for the extraction of metal from its ores; this is done by the low processing costs using this method, among other reasons. Gold recovery by using PAD is always low compared to recovery by leaching in agitation tanks. Leaching of fines is always a problem due to the channeling of the leaching solution and the formation of puddles; this generates low recoveries and even more, in the presence of clays in the ore, they further damage the recovery of gold from these ores. The processing in leach pads always requires research evidence to improve the recovery of gold in leaching. To achieve this improvement, optimization tests of the parameters are generally carried out. This experience relates the contribution of plumbous nitrate in the recovery by leaching in PAD of agglomerated mineral, compared to this process without the contribution of this salt. The metallurgical tests seek to evaluate the contribution of added nitrate of lead in small quantities in the improvement of the extraction of gold and silver, very apart from its wide use in the activation of zinc in the Merrill Crowe process. The agglomeration tests were carried out with different variants, taking into account the size of the globe formed, as well as the composition of the mixture and with the variation of the curing, thereof compared with a leaching process without the agglomeration process. The main reason for the experience is to determine the percentage of improvement in the recovery of gold in solution with the use of lead salts. Probable lead compounds are mostly insoluble in aqueous solutions; lead nitrate and lead acetate are the two products that are very soluble in water The column leaching process worked with an irrigation rate of 8 and 10 and shown improvements in the recovery of gold and silver. Several leaching tests were carried out with different dosages of lead nitrate, with the best result being the experience in which the lead nitrate dosage was 30g / MT of head mineral. The percentage increase in recovery with the addition of lead nitrate was 7.58 % compared with the non-use of this reagent, a variant that led us to perform additional tests to corroborate these results. The results obtained show the effectiveness of lead nitrate in the leaching-based recovery of gold by attacking the antimony and arsenic minerals, which are found in small quantities in the gold minerals, maintaining the same operating parameters as without its addition in the leaching process. The experimental tests were carried out in the laboratories of minerals processing and hydrometallurgy of Tecsup, as well as part of the chemical analyzes, and the rest of the analysis was made by a certified laboratory for the test contrast.