XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1149
applying the least square method using mathematical soft-
ware package Minitab 16.
The model equation is of the following form:
Y =β0 +β1X1 +β2X2 +β3X3 +β11X1 2
+β22X2 2 +β33X3 2 +β12X1X2
+β13X1X3 +β23X2X3 (1)
where β0 is the model constant X1, X2 and X3 are inde-
pendent variables β1, β2, β3 are linear coefficients β12, β13,
β23 are cross product coefficients and β11, β22, β33 are the
quadratic coefficients.
RESULTS AND DISCUSSION
The experiments were carried out using the multi gravity
separator to separate the Iron values from sub grade iron
ore. The variables and their levels are given in table 3. The
experimental results of the test program along with their
condition are tabulated in Table 4. It was observed that rota-
tional speed of the drum had great influence on the grade
and recovery of the concentrate fraction. It was possible to
achieve the concentrate grade of 62.00% Fe with a recov-
ery of 12.90% by weight at 3 degrees of Drum inclination,
4LPM wash water and 175 rpm drum rotational speed.
The highest recovery of 67.00% by weigh with a grade of
55.80% Fe at 5degree of drum inclination, 4LPM wash
water and 225 rpm respectively. It was observed that the
grade of the concentrate decreased as the drum rotational
speed (RPM) increased from 175 to 225RPM and recov-
ery increased. As the wash water increased from 2LPM to
6 LPM recovery decreased and grade increased. It is also
observed that the recovery decreased as the drum angle of
inclination increased from 3 degrees to 5 degrees where
as grade increased. The model equation for the recovery
(YRecovery) and grade (YGrade) of the concentrate fraction of
the MGS are presented in Eqs. 2, and 3 respectively.
YRecovery =43.44 +3.94X1 – 3.19X2
+22.03X3 +0.62X12 +3.25X22
– 7.30X32 +1.34X1X2
– 0.1X1X3 – 0.14X2X3 (2)
YGrade =56.8 – 0.11X1 +1.38X2
– 3.71X3 +1.48X12 – 0.45X22
– 0.23X32 – 1.68X1X2
+0.85X1X3 +1.33X3X2 (3)
Table 3. List of variables and their levels
Sl.
No. Variables Units
Level
Low (–1) Centre(0) High (+1)
1 Drum angle of inclination Degrees X1 3 4 5
2 Wash water flow rate Liters per minute -LPM X
2 2 4 6
3 Drum rotational speed Revolutions per minute (RPM) X
3 175 200 225
Table 4. Experimental results of coded and uncoded variables
Experiment Run
No.
Coded and Uncoded Values of Variables
Recovery Grade
X
1 (Angle)
X
2 (wash water)
X
3 (RPM)
1 –1 (3) –1(2) 0(200) 47.70 54.60
2 1(5) –1(2) 0(200) 53.60 57.00
3 0(4) 0(4) 0(200) 43.44 56.80
4 –1(3) 1(6) 0(200) 38.34 62.00
5 1(5) 1(6) 0(200) 49.60 57.70
6 –1(3) 0(4) –1(175) 12.00 62.00
7 1(5) 0(4) –1(175) 19.00 60.80
8 0(4) 0(4) 0(200) 43.44 56.80
9 –1(3) 0(4) 1(225) 54.34 53.60
10 1(5) 0(4) 1(225) 61.73 55.80
11 0(4) –1(2) –1(175) 19.50 60.80
12 0(4) 1(6) –1(175) 13.70 59.60
13 0(4) –1(2) 1(225) 65.37 50.00
14 0(4) 1(6) 1(225) 59.00 54.10
15 0(4) 0(4) 0(200) 43.44 56.80
applying the least square method using mathematical soft-
ware package Minitab 16.
The model equation is of the following form:
Y =β0 +β1X1 +β2X2 +β3X3 +β11X1 2
+β22X2 2 +β33X3 2 +β12X1X2
+β13X1X3 +β23X2X3 (1)
where β0 is the model constant X1, X2 and X3 are inde-
pendent variables β1, β2, β3 are linear coefficients β12, β13,
β23 are cross product coefficients and β11, β22, β33 are the
quadratic coefficients.
RESULTS AND DISCUSSION
The experiments were carried out using the multi gravity
separator to separate the Iron values from sub grade iron
ore. The variables and their levels are given in table 3. The
experimental results of the test program along with their
condition are tabulated in Table 4. It was observed that rota-
tional speed of the drum had great influence on the grade
and recovery of the concentrate fraction. It was possible to
achieve the concentrate grade of 62.00% Fe with a recov-
ery of 12.90% by weight at 3 degrees of Drum inclination,
4LPM wash water and 175 rpm drum rotational speed.
The highest recovery of 67.00% by weigh with a grade of
55.80% Fe at 5degree of drum inclination, 4LPM wash
water and 225 rpm respectively. It was observed that the
grade of the concentrate decreased as the drum rotational
speed (RPM) increased from 175 to 225RPM and recov-
ery increased. As the wash water increased from 2LPM to
6 LPM recovery decreased and grade increased. It is also
observed that the recovery decreased as the drum angle of
inclination increased from 3 degrees to 5 degrees where
as grade increased. The model equation for the recovery
(YRecovery) and grade (YGrade) of the concentrate fraction of
the MGS are presented in Eqs. 2, and 3 respectively.
YRecovery =43.44 +3.94X1 – 3.19X2
+22.03X3 +0.62X12 +3.25X22
– 7.30X32 +1.34X1X2
– 0.1X1X3 – 0.14X2X3 (2)
YGrade =56.8 – 0.11X1 +1.38X2
– 3.71X3 +1.48X12 – 0.45X22
– 0.23X32 – 1.68X1X2
+0.85X1X3 +1.33X3X2 (3)
Table 3. List of variables and their levels
Sl.
No. Variables Units
Level
Low (–1) Centre(0) High (+1)
1 Drum angle of inclination Degrees X1 3 4 5
2 Wash water flow rate Liters per minute -LPM X
2 2 4 6
3 Drum rotational speed Revolutions per minute (RPM) X
3 175 200 225
Table 4. Experimental results of coded and uncoded variables
Experiment Run
No.
Coded and Uncoded Values of Variables
Recovery Grade
X
1 (Angle)
X
2 (wash water)
X
3 (RPM)
1 –1 (3) –1(2) 0(200) 47.70 54.60
2 1(5) –1(2) 0(200) 53.60 57.00
3 0(4) 0(4) 0(200) 43.44 56.80
4 –1(3) 1(6) 0(200) 38.34 62.00
5 1(5) 1(6) 0(200) 49.60 57.70
6 –1(3) 0(4) –1(175) 12.00 62.00
7 1(5) 0(4) –1(175) 19.00 60.80
8 0(4) 0(4) 0(200) 43.44 56.80
9 –1(3) 0(4) 1(225) 54.34 53.60
10 1(5) 0(4) 1(225) 61.73 55.80
11 0(4) –1(2) –1(175) 19.50 60.80
12 0(4) 1(6) –1(175) 13.70 59.60
13 0(4) –1(2) 1(225) 65.37 50.00
14 0(4) 1(6) 1(225) 59.00 54.10
15 0(4) 0(4) 0(200) 43.44 56.80