### Determination of Work Index of Gyel Bukuru Columbite Ore in

23 May 2015 tion called Berry and Bruce comparative Bond 39 s equation that was used to determine the work index of the ore determining it by Berry and Bruce 1966 known as the comparative method 8 Table 2 gives the sieve analysis result of the feed to ball mill of test ore columbite and Figure 1 is the graph