Reference no: EM132505845 , Length: 4 Pages
Mineral Processing Assignment -
Question 1 - Consider a jig feed consisting of different colored blocks representing specific gravities. The blocks range in specific gravity from 1.2 to 2.1 in steps of 0.1 (that is, 10SG values), that is, they cover the range normally encountered in the jig cleaning coal. The feed to the jig consists of 50 blocks of each colour (or SG). Added randomly to the jig, the blocks become segregated (stratify) due to the repeated dilation and settling of the bed so that the light blocks are at the top of the bed and the black blocks are at the bottom of the bed. The stratification is not always perfect as there will be some misplacement of blocks at different levels.
If the jig is stopped and the blocks are removed layer by layer taking 50 blocks at a time, a measure of the amount of misplacement or efficiency of separation could be obtained by counting the number of each colour in each layer as shown in the table below.
|
Layer
|
Olive 1.2
|
Mauve 1.3
|
Green 1.4
|
Blue 1.5
|
White 1.6
|
Yellow 1.7
|
Pink 1.8
|
Red 1.9
|
Brown 2.0
|
Black 2.1
|
No Blocks
|
|
1
|
43
|
5
|
2
|
|
|
|
|
|
|
|
50
|
|
2
|
5
|
40
|
3
|
2
|
|
|
|
|
|
|
50
|
|
3
|
2
|
5
|
28
|
9
|
2
|
1
|
2
|
1
|
|
|
50
|
|
4
|
|
|
6
|
27
|
6
|
4
|
5
|
2
|
|
|
50
|
|
5
|
|
|
5
|
5
|
25
|
7
|
5
|
3
|
|
|
50
|
|
6
|
|
|
4
|
4
|
7
|
20
|
10
|
4
|
1
|
|
50
|
|
7
|
|
|
2
|
3
|
5
|
7
|
20
|
10
|
3
|
|
50
|
|
8
|
|
|
|
|
3
|
4
|
8
|
17
|
13
|
5
|
50
|
|
9
|
|
|
|
|
2
|
4
|
|
10
|
18
|
16
|
50
|
|
10
|
|
|
|
|
|
3
|
|
3
|
15
|
29
|
50
|
|
Total
|
50
|
50
|
50
|
50
|
50
|
50
|
50
|
50
|
50
|
50
|
500
|
Consider the first 6 layers to represent the product (the less dense particles are coal and are the product) then the separation density is 1.7 and the yield of the less dense particles is 60%. It will be noticed from the table that all the blocks in the range 1.2 - 1.3 and 1.3 - 1.4 are recovered as product but in the 1.4 to 1.5 range only 48 blocks report to the product, the remaining 2 being retained in the reject. The percentage of particles of that density range in the product is:
(48x100)/(6x50) = 16%
(6 rows of 50 blocks in product)
Similarly for the other density ranges (see table below).
|
Relative Density
|
Experimental Results
|
Percentage of raw Coal
|
Float Sink Analysis of Raw Coal
|
Distribution Coefficient
|
|
Clean Coal Mass %
|
Reject Mass %
|
Clean Coal Mass %
|
Reject Mass %
|
|
a
|
b
|
c
|
d
|
e
|
f
|
|
1.2
|
-
|
-
|
-
|
-
|
-
|
-
|
|
1.2-1.3
|
16.7
|
0.0
|
10.0
|
0.0
|
10.0
|
100
|
|
1.3-1.4
|
16.7
|
0.0
|
10.0
|
0.0
|
10.0
|
100
|
|
1.4-1.5
|
16.0
|
1.0
|
9.6
|
0.4
|
10.0
|
96
|
|
1.5-1.6
|
|
|
|
|
10.0
|
|
|
1.6-1.7
|
|
|
|
|
10.0
|
|
|
1.7-1.8
|
|
|
|
|
10.0
|
|
|
1.8-1.9
|
|
|
|
|
10.0
|
|
|
1.9-2.0
|
|
|
|
|
10.0
|
|
|
2.0-2.1
|
|
|
|
|
10.0
|
|
|
+2.1
|
|
|
|
|
10.0
|
|
|
Total
|
100.0
|
100.0
|
60.0
|
40.0
|
100.0
|
600
|
The yield is 60% (300 blocks). Column (a) represents 60% of the raw coal feed and column (b) represents 40% of the raw coal. In actual practice columns (a) and (b) are determined by separate sink and float analyses of the product and reject.
Column (c) and (d) are determined by:
Column (c) represents the number of blocks of a given SG recovered in the product as a percentage of the feed. Column (e) represents the percentage of blocks of that SG in the feed. In this case it represents 10% for each density fraction since equal numbers of blocks were used (in practice it would be determined by float and sink analyses of the raw coal).
The distribution coefficient (column f) represents the number of blocks of a given SG recovered in the product as a percentage of the number of blocks of that SG in the feed:
1. Complete the calculations for the remaining SG ranges in the table above and plot a partition curve for the jigging unit.
2. Determine the Partition Density, the Probable Error and the Imperfection.
Question 2 - Samples taken from a bank of flotation cell show the following mass and copper assays:
|
Mass
|
Mass %
|
%Cu
|
Cum %Cu
|
|
Cum
|
Recovery %
|
Cum Recovery %
|
|
Conc. 1
|
4.62
|
|
26.0
|
|
|
|
|
|
|
Conc. 2
|
1.63
|
18.4
|
|
Conc. 3
|
2.25
|
8.9
|
|
Conc. 4
|
10.9
|
2.2
|
|
Tail
|
80.6
|
0.0074
|
|
Feed
|
100
|
|
1. Calculate the recovery of copper for each individual fraction and also the recovery of copper and the grade of the cumulatively combined concentrates e.g., 1, 1+2, 1+2+3, 1+2+3+4.
2. Plot cumulative recovery of copper vs cumulative % Cu in the concentrates.
Question 3 - 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%.
1. 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).
Question 4 - If the run-of-mine coal of question 3 contains 5% water and the jig operates with a water-to- solids ratio (by mass) of 1:1 and the flotation feed has a water-to-solids ratio of 10:1, determine the quantity of water in litres per minute for each section of the plant.
Assume clean coal from jig = 6% water
Reject coal from jig = 4% water
Froth flotation product = 30% water (20% after filtration)
Froth flotation reject = 35% water
From thickener.
Attachment:- Mineral Processing Assignment File.rar