Abstract: The low-grade diatomite of Linjiang County，Jilin Province，is grade-three diatomite with high burning loss，and gangue minerals are mainly quartz and albite.Dispersant selection tests ate carried out in order to purification the diatomite，as well as roasting-acid leaching tests on the flotation concentrate.The results showed that the flotation index is optimum when using sodium tripolyphosphate（STPP) as dispersant under pH 9，slurry is 40 ℃ and lurylamine as collector.By STPP as dispersant solvent，through one roughing and two cleaning flotation operation，concentrate with 79.38% SiO₂，5.04%Al₂O₃ is obtained.And the concentrate of flotation was roasted for 1 h at temperature of 600 ℃，and leaching for 1.5 h using 20% sulfuric acid as solvent.Finally，diatomaceous concentrate with 89.57% SiO₂，4.77% Al₂O₃，0.71% Fe₂O₃ is obtained，which can meets the standard of top-grade diatomite.

Key words: Diatomite, Dispersant, Sodium tripolyphosphate, Roast, Acid leaching