The fineness grinding (the grinding quality) depends on the ratio the grinding media surface area (S) to grinding media volume (V). The greater this ratio value means the greater fineness grinding, i.e. more qualitatively grinding. The following table summarizes all physical and geometrical data of the most commonly used grinding media.
|Grinding media size, mm||Grinding media mass, kg||Surface area, sq.mm||Volume, cmm||The ratio of surface area to volume||Grinding media quantity in one cubic meter|
|The 100mm steel grinding ball||4,620||31 400||522 025||0,060||1 532|
|The 90mm steel grinding ball||3,410||25 434||380 556||0,067||2 102|
|The 80mm steel grinding ball||2,350||20 096||267 277||0,075||2 993|
|The 70mm steel grinding ball||1,600||15 386||179 055||0,086||4 468|
|The 60mm steel grinding ball||0,980||11 304||112 757||0,100||7 095|
|The 50mm steel grinding ball||0,580||7 850||65 253||0,120||12 260|
|The 40mm steel grinding ball||0,294||5 024||33 410||0,150||23 945|
|The 30mm steel grinding ball||0,128||2 826||14 095||0,201||56 759|
|The 25mm steel grinding ball||0,064||1 963||8 157||0,241||98 080|
|The 20mm steel grinding ball||0,033||1 256||4 176||0,301||191 562|
|The 15mm steel grinding ball||0,014||707||1 762||0,401||454 072|
|The 28х28mm cast-iron cylpebs||0,117||2 190||12 315||0,178||64 961|
|The 27х32mm cast-iron cylpebs||0,122||2 269||12 215||0,186||65 496|
|The 35х35mm cast-iron cylpebs||0,135||3 287||22 449||0,146||35 636|
As you can see at above table, the smaller geometrical dimensions of grinding media replies the greater ratio of surface area to volume. This is also confirmed by the practical application the grinding media during the material grinding. The 70mm – 120mm grinding balls use for coarse grinding (coarse grinding is 1-st stage of grinding at mining enterprises or the grinding in first mill chamber at cement plants).
The 15 – 40 mm grinding balls (or cylpebs) use for the maximum fine grinding. This grinding balls size use in the final stage of grinding in mining enterprises, in the cement production (grinding in second chamber) and at aerated concrete plants.
As we noted before, many enterprises revise the grinding media diameter in the reduction direction. We want to share one example as the confirmation above.
One of the greatest Ukrainian mining enterprise use the 100mm steel grinding balls for the primary material grinding. We conducted industrial tests for replacement the 100mm to 80mm grinding balls in the end of 2017. The industrial tests purpose has been to achieve a better ore grinding without changing the existing technological parameters at factory, especially – the ball mills productivity decrease. The obtained result has showed the effectiveness of 80mm grinding balls using in comparison with 100mm grinding balls – the finished class has increased more than 10%, with decreased the grinding media specific consumption.
Similar situations observe in the cement industry. One of the largest Ukrainian cement producers started use the 17-25 mm grinding balls assembly in the second chamber of a ball mill instead previously used cylpebs, in 2018. For now we have noted the fineness grinding improvement and the mill productivity increasing.
We hope that this information is useful for our readers and will help in considering questions about making changes into the grinding process at your enterprises. ENERGOSTEEL Company specialists always happy to help in any questions related the material grinding.