(a) Briefly discuss how the Bond Work Index is determined ( 8 marks) b) Discuss why the Bond Index approach has been widely adopted for mill sizing and also explain why the selection and breakage function approach is preferable ( 8 marks) (c) A mill with its length equal to its diameter is operated at a mill filling of 40% and a mill speec of 70%. A 1:10 size reduction ratio is achieved when the mill throughput is 200tph, but when the throughput is only 180 tph the reduction is 1:12. The feed size distribution is given by the equation. If needed, you may use any relevant assumptions to answer the following equations. (i) Calculate the work index ( 8 marks) (ii) Calculate the mill diameter (10 marks)