Run of mine coal is to be treated by jigging (+1/2 mm) and froth flotation (-1/2
ID: 106457 • Letter: R
Question
Run of mine coal is to be treated by jigging (+1/2 mm) and froth flotation (-1/2 mm). The treatment rate is 500 tph of solid (refer to flowsheet below). Other relevant data are: Particle size analysis +1/2 mm = 90% Ash of run-of-mine coal = 28% Ash of +1/2 mm fraction = 27% Jig reject represents 30% of the jig feed and has an ash content of 70% Flotation concentrate has an ash content of 10% Flotation reject has an ash content of 60%. o Calculate the mass of total clean dry coal and the ash percentage Clean coal refers to the concentrate of the unit processes (coal + ash content).
Explanation / Answer
The ash percentage can be calculated by adding the percentages of ash release in each and every unit.
Ash of run of mine coal=28%
Ash of +1/2mm fraction=27%
Given that particle size analysis +1/2mm=90%
The ash fraction is =27/90=0.3%
Ash content in jig=70% and fir jigging=+1/2mm=70/90=0.78%
Flotation ash content=10%
Flotation reject has ash content=60%
Now the ash content 60-10=50% and for flotation it is -1/2mm =-(50/90)=-0.56%
Total ash content=ash of run of mine coal+ash from jig+ash from flotation
=28%+0.3%+0.78%-0.56%=28.52%
The total clean dry coal =coal + ash content
Coal content=Jig feed content=30%
Ash content calculated=28.52%
Total=30+28.52=58.52%
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