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Unformatted text preview: 1.00AIM The aim of this experiment is to determine the Bond Work Index of granite by comparative grind with a known work index. 2.00INTRODUCTION The Bond Work Index was developed by Fred C. Bond and was first published in 1961. The index relates to “the energy required in kWh/t to reduce a given material from theoretically infinite feed size to 80% passing 100 microns” 1 . Berry and Bruce 2 developed a method of determining the grindability of an ore, by comparing it to the grindability of a standard ore of which the work index is known. Reasonable results will be obtained by the Berry and Bruce method if each test is conducted with identical operating parameters. The reference sample should have similar grinding characteristics to the sample of unknown index; the initial sample mass of each ore should be equal and should have equal residence times in the mill. The standard bond ball charge 3 should be used at 70rmp. Theoretically, the same energy will be used to grind the two samples under identical conditions in order to give a reasonable comparison. The Bond Work Index value for quartz shall be referenced at 13.57 kWh/t 4 . Quartz = ( W WiQ 1PQ- ) 1FQ Ore sample of granite = ( W Wio 1Po- ) 1Fo The Work Index of a sample of granite can be calculated using the following equation: (Equation 1) 1 1 Mular & Jergensen 1982 2 2 Wills 2007 3 3 Murdoch University Laboratory Manual 2009 4 4 Wills 2007 Page 1 = ( Wi WiQ 1PQ- )( 1FQ 1Po- ) 1Fo P = 80% passing size of product F = 80% passing size of feed 3.00PROCEDURE The procedure stated below is an abstract from Murdoch University’s EXM301 Mineral processing I Laboratory Manual, 2009, pp 11. 1. From the sample of granite and quartz supplied conduct particle size analysis on sufficient material to enable the preparation of equal particle size distributions of a charge of each material weighing 1kg. Take a 150g sample of each material and determine their size distribution. 2. Batch grind the quartz and granite sample separately for 3 minutes each using the rod mill operating at 70rpm and using the standard Bond charge of rods. 3. Conduct particle size analyses on the products obtained, using at least 5 sieves, to determine their 80% passing size and hence calculate the work index of the ore sample....
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