Abstract: In order to solve the quality problem of sulfur concentrate after recycling copper (containing gold and silver) and iron in a mine of Tongling Nonferrous Metals Group Holding Co.,Ltd.On the basis of small scale condition test,continuous sulfur selection test was carried out.The results showed that: ①The metal minerals in magnetic separation tailings were mainly pyrite and pyrrhotite,both of which liberation degree was about 90%,and the particle size was mainly distributed in 10～60 μm.Gangue minerals were mainly quartz,followed by calcite,garnet and so on.②The floatability of pyrrhotite was worse than that of pyrite and similar to that of easily floating gangue minerals.It was the reason that it was difficult to obtain high quality sulfur concentrate by flotation process.According to the difference in the floatability of pyrite and pyrrhotite,and the difference in the magnetic properties of pyrrhotite and gangue minerals,the flotation processes of step-selection,middlings by high intensity magnetic separation and high intensity magnetic concentrate by flotation process were adopted.The total sulfur concentrate containing sulfur grade 40.36%,iron grade 49.25%,total sulfur + iron grade 89.61% and sulfur recovery 66.78% was obtained.The iron grade of sulfuric acid burn slag can reach 65% after the concentrate is burnt by sulfuric acid ,which greatly increases the additional value of sulfuric acid burn slag.③Microscopic analysis of the product shows that,the main useful minerals in magnetic separation tailings are pyrite and pyrrhotite.Pyrite is the main metal mineral in sulfur concentrate 1,and pyrrhotite is the main metal mineral in tailings of first-stage concentation and second-stage concentration.Pyrrhotite is the main metal mineral in sulfur concentrate 2.This shows that the flotation processes of staged flotation,middlings by high intensity magnetic separation and high intensity magnetic concentrate via flotation process are reasonable process for recovering pyrite and pyrrhotite from tailings of magnetic separation.④In this continuous separation test,tailings 2 (high intensity magnetic separation tailings) has a high content of sulfur,up to 14.53%.It is mainly non-magnetic pyrite.Follow-up research should be carried out on the recovery of the minerals containing sulfur.

Key words: Pyrite, Pyrrhotit, Step-flotation, High intensity magnetic separation+flotation