Assignment $1,05$ March $2024$

Stock Preparation

A pulp screen is fed with $50000\frac{m^3}{d}$ of stock at $1\%$ consistency. The feed pulp has a long fibre fraction of $20\%$ and a shive content of $0\mathrm{.}5\%.$ The screen accepts flow is at $0\mathrm{.}8\%$ consistency, with a long fibre fraction of $28\%$ and a shive content of $0\mathrm{.}1\%.$ The consistency of the reject stream is $1\mathrm{.}3\%.$ Calculate the following screen performance characteristics:

$50001$

istency

$1\%$ co

$\frac{L}{f}=$ :

Shives

$\mathrm{.}1\%$

a$)$ Volumetric reject rate

$(11)$

b$)$ Volumetric reject rate $(1)$

c$)$ Mass reject rate $(1)$

Template updated by CQPA & approved by AEM $20$ April $2017$

Page $7$ of $11$

c$)$ Shive removal efficiency $(3)$

d$)$ Compare the selectivity of the screen with respect to shives and long fibres.

$(3)$

e$)$ Comment on the magnitude of the rejects flow $(2)$

f$)$ Briefly explain what is "rejects thickening".

$(3)$