Alternatives to improve technological and environmentally the miner-metallurgic processes of recovery of gold in Vetas and California (Santander, Colombia)

With the purpose of improving the recovery of gold, to eliminate the use of the mercury and to diminish the contamination with cyanide in the Mining District of Vetas and Californian, the concentration processes were studied in a machine knelson and the intensive cyanidation of the concentrate. As fundamental part of this work, it was carried out the characterization of the samples, determining and quantifying the most influential characteristics in the processes of gravimetric concentration and of cyanidation, as well as the necessary for the design of plants. Of the mineralogical characterization it concluded that the ore of the two municipalities present significant differences that bear to think of the necessity of using different extractive processes. In general, the ore of California, bigger tenors of gold contain and of silver and they are poly-sulphurated; while those of Vetas are of pyritic type, except for that of the Golden Mine that presents similarity with those of California. The minerals of California presented a high percentage of gold (40-60%), fine coming from the alteration of the mineral; a high lixiviability in bottle; especially the samples of the Sinues Mine, with dissolutions of gold of the order of 95%, while of the Vetas was of the order of 60%. The experimental results in the knelson equipment, allowed to check the applicability of this concentration type for the case of the minerals of Vetas, obtaining under controlled operative conditions, concentrated with high tenors of gold, 421.16 g/t; significant enrichment reasons, 29.5 (tenor of the concentrate / tenor of the mineral head), with recoveries of gold notables, bigger to 80%. On the contrary, with those of Californian ores, satisfactory results were not obtained, accountable for the presence of the high percentage of gold in the fines. The application of the intensive cyanidation to the obtained concentrates, it was evaluated in presence and absence of the catalytic Leachwell and Pb(NO3)2. It was determined that without the use of catalysts, this process can be applied with excellent results for the case of the Vetas ores; for example, carrying out tests with samples -65 Tyler (d80), mechanical agitation, continuous aeration, 40% solids, (NaCN) = 5000ppm, in times of so alone 4 at 6 hours of lixiviation, dissolutions of gold superiors to 90 % were obtained with cyanide consumptions among 2 to 4 mineral kg/t. For the samples of California, the best dissolutions of gold, of the order of 90%, were achieved using the cyanidation for conventional agitation with the mineral head without concentrating, milled at -200 Tyler (d80) and with times of 24 hours of reaction. For the gold recovery from the cyanidates solutions, they were carried out tests with activated coal and cementation with powder of zinc, obtaining very satisfactory results. With base in the obtained results, they propose flow diagrams of three recovery plants of gold from the minerals of the studied mines. For the Vetas case, a plant with the processes of centrifugal concentration and intensive cyanidates of the concentrates, while for those of California, they propose two plants applying the conventional cyanidation, a recovering the gold with activated coal and the other one with the process Merrill-Crowe