Abstract: The useful minerals in complex associated uranium-rare earth ores are finely disseminated. Overgrinding tends
to occur in the traditional fine grinding process,resulting in a decrease in resource recovery rate. In order to improve grinding
efficiency and reduce slime generation,the study took the tailings from rough grinding-high intensity magnetic separation-gravity
separation of this ore as the object and systematically compared the grinding effects of ball mills (closed circuit) and Isa mills
(open circuit),and detailly explored the influence laws of key operating parameters of Isa mills. The results showed that the
optimal grinding conditions of Isa mills are a feed rate of 60 L/ h,a medium filling rate of 45%,a rotational speed of 1 700
r/ min,and a pulp concentration of 36%. Under these optimized conditions,when preparing products with -0. 15 mm accounting
for 95%,the -0. 074 mm particle size content is as high as 93. 74%,which is 21. 42 percentage points higher than that of
the closed-circuit ball mill product. At the same time,the contents of -0. 025 mm fine particle size is 8. 65 percentage points
lower,effectively suppressing overgrinding. Isa mills can achieve a better narrow-size distribution of grinding products through
open-circuit grinding alone,demonstrating significant advantages in improving grinding efficiency,reducing energy consumption
and medium consumption. This study provides an effective technical solution and theoretical basis for solving the efficient fine
grinding of similar complex associated minerals.

Key words: Isa mill,fine grinding,reduce overgrinding,product particle size distribution