The higher the index is the easier the coal to be pulverized.However, this index can not be used to size a pulverizer and mill power directly.Only the specific energy, mill power over capacity, is a main parameter for mill sizing.Specifically, the bond work index is suitable for utilization in.
Get PriceDrop weight index dwi and the coarse ore grinding index m ia.Test data from the bond ball mill work index test is used to calculate the fine grinding index m ib.The m ia and m ib indices are used to calculate specific energy for the coarse w a and fine w b components of the total grinding specific energy at the pinion w.
In the second step of the testing method, the test is based on the bond ball mill.The product from the first step is then used for determination of the required ball mill energy for the secondary grinding stage to reach the target grinding size.The empirical formula to calculate bond mill work index bwi is presented in the equation 2.
Figure 8 rod millball mill work index ratio v.Unconfined compressive strength 100 200 300 400 ucs mpa 0 0.5 2 wirmwibm metric siddall et al 1996 identified the ratio of bond rod mill work index and ball mill work index as being indicative of an ores compentency.Figure 8 plots this ratio versus ucs no trend is apparent.
A method using bond indices than adding a single factor of 1.25 to arrive at the agsag speci c energy.In 1991 the canadians developed the sagpower index spi, test using 2 kg of material in a 300 mm diameter mill.This test has been further developed by starkey, hindstrom and orser 2006.This test now includes a bond ball mill work.
The work index of a particular material is determined in the laboratory by conducting the standard bond grindability test.Bond developed separate tests for the rod mill and the ball mill.The simplified test method described in this paper, which is used at anaconda research center to approximate the work index, is an alternative procedure to.
The bond work index is a measure of ore resistance to crushing and grinding and is determined using the bond grindability test.Its value constitutes ore characteristic and is used for industrial comminution plants designing.Determining the bond work index value is quite complicated, timeconsuming and requires trained operating personnel and therefore is subjected to errors.A quick method.
Commercial grinding conditions for the test in a 0.5 m diameter sag mill.In the 2009 database, sag pinion energies to grind from f80 152 mm to t80 1.7 mm vary from 1.4 to 34 kwht and bond ball mill work index values vary from 6 to 24 kwt for the same ores.Project design tonnages varied from 200 to 150,000 td, sag mill sizes varied from 10 ft.
The basic parameters used in ball mill design power calculations, rod mill or any tumbling mill sizing are material to be ground, characteristics, bond work index, bulk density, specific.
Mill ball mill closed circuit crushing to 16 mm open circuit 8 dia.Rod mill to 1 mm closed circuit 8 dia.Ball mill to p80 um the ore test work index circuit operating work index 9 the standard bond circuit coarse ore bins fine ore bins screen crushing screen classification rod mill ball mill this is the reference basis for all work.
The mill power is 22.5 watts, calculated by 6.Fi- p nally the product is wet screened to find the size d80.Rod mill semi continuous process the same mill is used for the semi continuous grinding tests which is similar to the bond test but with the exist- ing mill of known power.After time the mill.
In conjunction with the bond ball mill work index they can be used to accurately predict the overall specific energy requirements of circuits containing ag and sag mills, ball mills, rod mills, crushers, high pressure grinding rolls hpgr.