The fineness grinding dependence on the grinding media size

16.08.2018

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.