In this experimental investigation a refractory gold ore from Santiago de Chuco was studied, the chemical composition analyzed was 17.71 g / MT Au and 19% As, which presents refractoriness for gold extraction, with less 16.91% and 33.28% extraction of gold to mesh # 200 and mesh # 400 respectively, for which it was proposed to pretreat grinding with oxidizing reagent of calcium carbide in 3, 6 and 9 Kg / TM and varying the granulometry in P80 = mesh # 200, and P90 = # 400 mesh, followed by agitation leaching using sodium cyanide at 5000 ppm concentration and sodium silicate dispersant. The results obtained are determined by using calcium carbide in low doses and fine granulometry, gold recovery is increased, obtaining the highest gold recovery of 55.52% at 3 Kg / MT of calcium carbide and with granulometry of 90 % through mesh # 400, being the lowest gold recovery of 43.72% at 6 Kg / MT ...