Abstract: Manganese ore resources in China are rich,but there are some problems such as low grade of manganese in raw ore,extremely fine disseminated grain size of useful minerals and easy slime of gangue components. Therefore,it is of great practical significance to improve the technical level of manganese ore dressing. Taking a manganese oxide ore from Gejiu,Yunnan Province as the research object,the beneficiation tests were carried out by the process of washing,desliming and magnetic separation combined with the ore properties. The results showed that:① the manganese grade of the raw ore is 6. 40%,and manganese mainly exists in the form of manganese oxide minerals such as psilomelane and pyrolusite,among which the extremely fine manganese oxide minerals with the disseminated particle size of -0. 01 mm have a higher yield. ② Under the condition of stirring intensity of 2 000 r / min,the ore slime with a yield of about 69% can be removed by the hydrocyclone in the laboratory,which creates favorable conditions for obtaining high grade manganese concentrate by subsequent sand settling. ③ For manganese oxide minerals in settled sand deposition,magnetic materials with manganese grade of 29. 13% and 7. 86% were obtained by using the high intensity magnetic separation process of one roughing and one scavenging,which realized the efficient recovery of manganese minerals with coarse grain size. For the manganese oxide minerals in the slime,the magnetic materials with manganese grade of 18. 07% were obtained by the process of high intensity magnetic separation with one rough separation,and the comprehensive utilization of fine manganese minerals was realized. Through the whole process test,a manganese concentrate with a cumulative yield of 16. 08%,an average manganese grade of 23. 78% and a cumulative recovery rate of 60. 21% was obtained,which realized the efficient and comprehensive utilization of the refractory extremely low grade and high mud-containing manganese ore.

Key words: extremely low grade,high mud content,manganese oxide ore,desliming,high intensity magnetic separation