Ball Mill Performance & Efficiency Formulas

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Ball Mill Performance & Efficiency Formulas

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Ball Mill Performance & Efficiency
S.DescriptionSymbolFormulaExample
No.
1Arm of gravitya0.666 * ( 1 – 4 * R2 )1.5h0.583
TAN-1 [ 0.5 / R * (1 – 4*R2)0.5] – [ 2*R * (1 – 4*R2)0.5 ]Deff4.18
hCentre Distance (from mill centre to media top layer), mtsR0.139
DeffMill effective diameter, mtsa0.578
Rh/Deff, ratio of centre distance to mill effective diameterTarget
2Torque factor matrixu
2Power consumption, netPn0.514 * F * u * n * Deff * aF175
kWFGrinding media weight, tonsu0.73
uTorque factorn16
nMill speed, rpmDeff4.18
DeffMill effective diameter, mtsa0.578
aArm of gravity, –Pn2538
Target
3Power consumption, grossPgPn * 100 * 100Pn2450
kWEm * EgEm95
EmMotor efficiency, %Eg95
EgGearbox/girth gear efficiency, %Pg2715
Target
4New production rateNPBFormula-1OPB118
(Mill output Vs. Blaine)tphOPBOB4000
Exp ( ( NB – OB ) * 0.49 / 1000 )NB5000
OPBOld production rate, tphNPB72
OBOld blaine, cm2/gmTarget
NBNew blaine, cm2/gm
Formula-2OPB118
OPB * ( OB / NB )1.3OB4000
OPBOld production rate, tphNB5000
OBOld blaine, cm2/gmNPB88
NBNew blaine, cm2/gmTarget
5New production rateNPROPR * ( 2 – log ( OR ) )OPR150
(Mill output Vs. Residue)tph( 2 – log ( NR ) )OR11.5
OPROld production rate, tphNR9.5
OROld residue, %NPR138
NRNew residue, %Target
6Gypsum set pointGSP21500 * ( Scem – Sclk )Scem2.1
(at weigh feeder)tphPu * ( 100 – Fgyp )Pu90
ScemTarget SO3 content in cement, %Sclk0.3
PuGypsum purity, %Fgyp4.8
SclkSO3 content in clinker, %GSP4.52
FgypFree moisture in gypsum, %Target
7Maximum ball sizeMBS36 * F0.5 * { ( SG * Wi ) / ( %C * Deff0.5 ) }0.333F15
mmFFeed size (sieve size in mm which retains 20% material), mmSG3
SGSpecific weight of feed material, gm/cm3Wi15
WiBond’s work index, kWh/t%C75
%CMill speed as %critical, %Deff5.1
DeffMill effective diameter, mtsMBS90
Target
8%Filling%F112.5 – ( 125 * h / Deff )h2.5
%hFree height, mtsDeff4.155
DeffMill effective diameter, mts%F37.3
Target
9Circulation factorCFormula-1FF150
F + GCR170
FC2.13
FFresh feed rate, tphTarget2-3
GCoarse return, tph
Formula-2Rg54.92
Rg – RfRf3.52
Rg – RmRm34.16
RgResidue of coarse return, %C2.48
RfResidue of fines, %Target2-3
RmResidue of separator feed, %
10Circulation loadCL( C – 1 ) * 100C2.48
%CCirculation factor, –CL148
Target
11Separator efficiencySEFormula-1Ro100
%[log(Ro/Rf) – C * log[{Ro+(C-1)*Rg} / {Rf+(C-1)*Rg}]]*100Rf3.52
log(Ro/Rf) – C * log[{Ro+(C-1)*100} / {Rf+(C-1)*100}]C2.48
RoResidue of fresh feed, %Rg54.92
RfResidue of fines, %SE68.8
CCirculation factor, –Target70-80
RgResidue of coarse return, %
Formula-2 (Fines Efficiency)Rf3.52
( 100 – Rf ) * 100Rm34.16
( 100 – Rm ) * CC2.48
RfResidue of fines, %SEf59.1
RmResidue of separator feed, %Target70-80
CCirculation factor, –
Formula-3 (Coarse Efficiency)Rg54.92
Rg * ( C – 1 ) * 100C2.48
C * RmRm34.16
RgResidue of coarse return, %SEc95.9
CCirculation factor, –Target70-80
RmResidue of separator feed, %
12Critical speednc42.3 / Deff0.5Deff4.15
rpmDeffMill effective diameter, mtsPn20.8
Target
1New production rateNPRFormula-1OPB118
(Mill output Vs. Blaine)tphOPBOB4000
Exp ( ( NB – OB ) * 0.49 / 1000 )NB5000
OPBOld production rate, tphNPR72
OBOld blaine, cm2/gm
NBNew blaine, cm2/gm
Formula-2OPB118
OPB * ( OB / NB )1.3OB4000
OPBOld production rate, tphNB5000
OBOld blaine, cm2/gmNPR88
NBNew blaine, cm2/gm
2New Specific power cons.Formula
(sp. power Vs. Blaine)NPRE1E (S1 / S)n
kWh/TC
E1New specific powerE32.5
EOld specific powerS15000
S1New BlaineS4000
SOld Blainen1.3
nMill exponent for close ckt  = 1.3E143.44
1New production rateNPRFormulaOPB118
(Mill output Vs. Blaine)tphOPB * ( OB / NB )1.3OB4000
OPBOld production rate, tphNB5000
OBOld blaine, cm2/gmNPR88
NBNew blaine, cm2/gm
2New Specific power cons.Formula
(sp. power Vs. Blaine)NPRE1E (S1 / S)n
kWh/TC
E1New specific powerE32.5
EOld specific powerS15000
S1New BlaineS4000
SOld Blainen1.3
nMill exponent for close ckt  = 1.3E143.44

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