You need to wet grind 1250 tonnes/hr copper ore (copper ore p 4200kg/m. the slurry is made up at 26 vol % solids a) using bonds method, calculate the energy required to reduce the ore from 2 mm to 120 microns in size (dso). b) you plan to use wet overflow ball mills to grind the ore. your ball mill supplier produces mills in either 3 m or 4.5 m diameters as standard sizes and any length between 1 and 2.5 times the diameters long. specify the number of mills required and the operating conditions (including actual rotational speed) for each of the mill diameters available. calculate the total length of the mills needed by using the equation for power draw (franks notes, chapter 2, eqn. 8.8 in kelly and spottiswood). you will need to specify the operating conditions (mill rotational speed and loading of mill etc) to do the calculation. note, that to get the total power required (answer to part a) you may need more than one mill since they may not be made very long relative to their diameter. 1 mark) determine how many and what diameter of cyclones are needed to separate 2,000 tonnes per hour (on a dry wt basis) of ilmenite into fractions greater than and less than 70 microns? the slurry is at 30 volume % solids, and the density of ilmenite is 4,700 kg /m 3, the hydrocyclones will be operated at 70 kpa pressure so the pressure correction factor will be 1.0. use figure 10.23 from kelly and spottiswood and the following equations. "typical" size cut actual size cut / correction factors actual capacity "typical" capacity * correction factors.