QUESTION $4(20)$

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 HP$200$ Series Cone Crushers $-$ Reduction relation $4$

b$)$ Nordberg HP$300$ 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 $P_{80}$ of $350m.$

Bond Work Index of the hematite ore $(Wi)=15\mathrm{.}44kW\frac{h}{t}$

Feed rate $=110\frac{t}{h}$

Power rating of the existing mill motor $=620kW$

Energy Losses from the mill $=16\%$

TABLE $1$: PSD$\text{'}$s

$\backslash$table$[[\backslash$table$[[$Size of$],[$sieve$]],$Feed,$\backslash$table$[[$Size of$],[$sieve$]],$HP$200,\backslash$table$[[$Size of$],[$sieve$]],$HP$300,\backslash$table$[[$Size of$],[$sieve$]],$Mill$],[m,\backslash$table$[[$Crusher$],[(g)$