Please Answer ALL. Thanks. 1) The ore fed to a rod mill has a Bond Work Index of
ID: 107176 • Letter: P
Question
Please Answer ALL.
Thanks.
1) The ore fed to a rod mill has a Bond Work Index of 18 kWht-1. The p80 of feed to the mill is 22 mm (f) and the p80 of the product from the mill is 0.140 mm (p). Calculate the work (in kW/tonne) required to grind the ore to the product size.
2)A ball mill with an internal diameter of 2,600 mm is operated at 75% of the critical speed. At what speed in revolution per minute should the mill be operated at. Assume all the balls have a diameter of 120 mm.
3) A copper concentrator using froth flotation, processes 12,000 tonnes of ore at 4.0 % Cu grade (mainly as the mineral chalcopyrite) and produces 4,500 tonnes of copper concentrate. The assay grade of the tailings is 0.25% Cu. Calculate the grade of the concentrate.
4)Calculate the basicity index (BI) of a slag with the following composition:
CaO = 25%, SiO2= 47%, MgO = 15%, Al2O3 = 10%
Is this slag acidic or basic?
5)
Which mineral ore would require the most tonnes of ore to be moved per tonne of metal produced?
Select one:
a. zinc
b. nickel
c. iron
d. lead
Explanation / Answer
1)Bond work index=18kWh t-1
Amount of feed to the mill=22mm
Product from the mill=0.140mm
The work done=(amount fed to mill/(product output*total power))
=(22)/(0.140*18)=8.730kW/tonne
2)The rated speed=75%
The internal diameter=2600mm
The diameter of the balls=120mm
Now first the speed is converted to RPM.75% of speed =75/60=1.25RPM
Now the internal diameter=2600mm
The speed of mill=2600*1.25=3250RPM
3)The grade of concentrate can be calculated as,
Out of 12000,4%of copper and out of 4500,0.25%of copper.
Grade of concentrate=(12000*4/100)/(4500*0.25/100)=42.66% of concentrate is present.
4)The slag is basic in nature because the concentration of all the elements do not exceed 50% and above and hence they are basic. If they are above 50%,they may be considered to have acidic nature.
5)zinc would require most tonnes of ore to be moved per tonne of metal because it is available mostly in combined form and in order to separate it,may elements must be taken from it.