As the consulting engineer for Iron Ore Recourses you need to assist a client in selecting one of two possible second-hand secondary crushers used as the final stage crushing for hematite ore. This secondary crusher is needed to replace the existing secondary crusher, which has broken down beyond repair, on the plant. The following two crushers are available: a) Nordberg HP200 Series Cone Crushers - Reduction relation 4 b) Nordberg HP300 Series Cone Crushers - Reduction relation 5 The secondary crusher is followed by an existing efficient milling circuit. The client also informed you that they operate at 80% efficiency. Additional information you received with your characterisation study and with consultation with the client: • The liberation size of the hematite was determined to be at P80 of 350 μm. Bond Work Index of the hematite ore (Wi) = 15.44 kWh/t • Feed rate 110t/h • Power rating of the existing mill motor = 620 kW Energy Losses from the mill = 16% TABLE 1: PSD's Size of sieve Feed Size of sieve HP200 Size of HP300 sieve Size of Mill sieve Crusher Product Product Product μm μm (g) (g) μm (g) um (g) 67882 75 19250 15 19250 424 60 48000 25 13600 85 13600 10 300 67 33941 75 9600 75 9600 90 212 90 24000 105 6800 75 6800 100 150 105 16971 45 4800 25 4800 40 106 85 12000 75 3400 100 3400 60 75 55 8485 25 2400 25 2400 50 53 10 pan 75 pan 100 pan 150 pan 20 Please indicate, with all the necessary calculations and figure(s) Appendix C (using Gaudin-Schumann plot), how you have decided on which crusher to use.
