41 posts

### Mass Balance

I was just wondering how important it is to a Cement machinery supplier that the Mass Balance is ?? Based on which they give Performance Guarantee. Being a Auditor Myself i came across a plant where they don't have a drop test facility for Mass Balance (Lime consumption factor) so with no other option we have to apt for the equation given by peray in Cement Manufacturer's Handbook Page 100 (Metric system) Here is that excerpt of that equation** (Peray doesn't gives the derivation of the equation as usual, All we have is the black box, So believe it to use it or crack the nut)**

a = 0.01784 Cca

b = 0.0209 Cmg

c = 0.01 CAl

d = 0.01 CSi

e = 0.01 CFe

f = 0.00075 Csi + 0.0035 CAl

subtotat = a + b+c+d+e+f

g = subtotal * ((100-Hig)/100)

Where C = Composition in % on loss free basis

Ca = CaO , Si = SiO2 , Mg = Mgo , Al = Al2O3 and Fe = Fe2O3

subtracting Ash in clinker form g we get Amount of feed required to produce on kilogram of clinker

Trust Me having done Many, literally Many Audits of cement plants i have found that peray equation (the one above) rarely gives empirical figures

So I was just again wondering if somebody can crack the nut?rather than giving some wild guess !! or just Blindly follow as being done from many years?

I'll be waiting......

Er.Raza Hussaini

Asst.Manager

B.tech., (Chemical Engg)

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77 posts

537 posts

### Re: Mass Balance

Hello Raza,

The nut is fairly easy to crack, I think.

The factors you quoted from Peray are related to the molecular weights of the oxides (and, in the case of CaO and MgO, their carbonates) in an attempt to estimate the loss-included contribution of each oxide. eg.

CaCO3 =100.09

CaO =56.08

MgCO3 =84.41

MgO =40.30

Therefore the factor for the loss-included contribution of CaO (present as limestone) would be;-

(100.09/56.08)/100 = 0.017848

while that of MgO would be;-

(84.41/40.30)/100 = 0.020945

Since the rest of the major oxides (Al2O3, Fe2O3 and SiO2) occur predominately in raw mix minerals that do not have any significant loss, their percentage factors are all simply;-

1/100 = 0.01

These are the theoretical values, and they agree with those quoted by Peray's handbook. However I cannot so easily explain the last factor;-

(f = 0.00075 * CSi + 0.0035 * CAl)

Perhaps this is an empirically-derived correction which allows for the contribution of complex silicate and aluminate minerals which contain silica and alumina in a hydrated form (ie Hydroxides rather Oxides) such as kaolinites and montmorillonites which are the most common of all clays.

I hope this helps,,,

Best regards,

Ted.

41 posts

### Re: Mass Balance

Well Thaks Ted Krapkat for Cracking nut!!