Abstract: In view of the serious environmental pollution caused by the traditional gold leaching process with sodium cyanide， sodium dicyandiamide was used as gold leaching agent to effectively treat a quartz vein gold ore with 3.39 g/t gold from Canada. The results indicated that， at the grinding fineness of 75% passing 45 μm， roasting 1 h at 700 ℃， the roasted products with sodium dicyandiamide dosage of 8 kg/t， hydrogen peroxide1.2 mL， pulp pH=11.5， liquid-solid ratio 4 mL/g， leaching temperature of 35 ℃ for 24 h， gold leaching rate is 89.08%， and the gold grade of leaching residual is 0.38 g/t. Using sodium dicyandiamide as leaching reagents can obtain good leaching results. The total cyanide content in the leaching system is far below the national environmental protection discharge standard. Therefore， sodium dicyandiamide as a high-efficiency and low-toxicity gold ore leaching agent has a certain application prospect.

Key words: Sodium dicyanamide, Gold ore, Leaching, Total cyanide content, Environmental friendly