A comaparative study on the effect of using conventional and high pressure grinding rolls crushing on the ball mill grinding kinetics of an iron ore
 
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Department of Mining Engineering, Lorestan University, Khorramabad, Iran
CORRESPONDING AUTHOR
Kianoush Barani   

Lorestan University, Lorestan University- Engineering Faculty-Mining Department, 6129620942 Khorramabad, Iran
Publication date: 2016-06-01
 
Physicochem. Probl. Miner. Process. 2016;52(2):920–931
 
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ABSTRACT
The effect of using conventional and high pressure grinding rolls (HPGR) crushing on the ball mill grinding of an iron ore was assessed to determine how these different comminution processes affect the ball mill grinding kinetic. For this purpose, the sample was obtained from the Jalalabad Iron Ore Mine and crushed by conventional crusher and HPGR. Then, the crushing products were ground in a laboratory ball mill. Five single-sized fractions of (–4+3.15 mm), (–2+1.7 mm), (–1+0.850 mm), (–0.500+0.420 mm), and (–0.212+0.180 mm) were selected as the ball mill feed. The specific rates of breakage (Si) and cumulative breakage distribution function (Bi,j) values were determined for those size fractions. It was found that for all fraction the Bi,1 values of the HPGR product were higher than those for the crusher product. It means that the particles produced by the dry ball milling of the HPGR product were finer than by the crusher. Also, the results showed that the specific breakage rate of the material crushed by HPGR at coarse fractions (–4+3.15 mm, -2+1.7 mm, and -1+0.850 mm) was higher than the material crushed by conventional crushers. However, at fine fractions (–0.500+0.420 mm and -0.212+0.180 mm), there was a small difference and the specific breakage rates were the same. This issue can be explained by the fact, that for coarse fractions the particles had longer side surfaces and thus were more affected by the lateral pressure. The results of verification test showed that after 60 seconds of grinding the 80% passing size of the HPGR and crusher products (D80) were reduced from 3311 μm to 760 μm and 1267 μm, respectively.
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