Abstract:A foreign high-sulfur and low-zinc tailings contains 2.69 % zinc and 47.08 % sulfur. The gangue minerals are mainly talc and contain a large amount of pyrite. The high sulfur content is the main reason for the poor flotation index of the ore. Through conditional tests in the laboratory, it is pointed out that insufficient lime dosage and excessive copper sulfate dosage lead to low Zn grade of concentrate in the field. The Zn grade of concentrate is significantly improved by adjusting the dosage of reagent, using combined collector and adding pyrite auxiliary inhibitor Kg-1. Under the optimal reagent system, a closed-circuit process of one roughing, three cleaning and one scavenging was adopted, and the middle ore was returned in sequence. Among them, lime was not added in the scavenging process, and other reagents were halved. Lime 500 g/t was added in the three cleaning processes to adjust the pH of the pulp. The final closed-circuit zinc concentrate product obtained in the test had a Zn grade of 42.86 % and a Zn recovery rate of 71.93 %, which met the flotation index required by the concentrator, and realized the efficient recovery and utilization of zinc from the high-sulfur and low-zinc tailings. The effect of Kg-1 addition on the Zn grade of closed-circuit zinc concentrate was investigated by closed-circuit test. The test results showed that the introduction of Kg-1 could effectively hinder the flotation of pyrite in the flotation process and significantly improve the Zn grade of zinc concentrate. Compared with the closed-circuit test results without Kg-1, the Zn grade of zinc concentrate increased by 13.76 %, indicating that Kg-1 is an effective pyrite inhibitor. The mechanism of Kg-1 inhibiting pyrite is to form insoluble complexes with Cu₂₊ ^{and Fe₂₊} on the surface of pyrite activated by copper sulfate, which hinders the adsorption of collector on the surface of pyrite.