Environment-friendly low-toxicity gold extraction agent, preparation method thereof and gold leaching method thereof

The invention relates to the technical field of gold extraction agents and hydrometallurgy, in particular to an environment-friendly low-toxicity gold extraction agent and a preparation method and a gold leaching method thereof. The gold extraction agent comprises urea, thiourea, alkali, ammonium salt and a reducing agent, the mass ratio of the urea to the thiourea to the alkali to the ammonium salt to the reducing agent is (0-30): (5-45): (1-20): (0-10): (0-10). The gold leaching method of the gold extraction agent mainly comprises the following steps: a, preparing an agent; b, preparing ore; c, carrying out size mixing; d, adjusting the pH value of ore pulp; e, adjusting the oxidation potential of the ore pulp; and f, carrying out gold leaching. In the step a, the environment-friendly low-toxicity gold extraction agent is added into an alkaline solution to be completely dissolved; in the step c, size mixing is carried out on an ore sample, wherein the solid-liquid ratio is 1: (2-6); and in the step d, an al