Assessment of blending bed

For Assessing the homogenizing performance of a blending bed, following parameters will be considered. Four of these are introduced as estimated values of the statistical variance.

Sa: Overall variance of the input variations

Sb: Overall variance of the output variations

So: Variance of the output variations within the reclaimed slice. ( is very small)

Sx: Variance of the averages of the slices. (is very small for a good homogeneous pile)

Other Parameters are

N: the Number of Layers

T: the quantity of material per layer

t: the quantity of material per reclaimed slice

The homogenizing effect can be estimated in advance. For estimating the output variations the following relation is available:



Sx = Sa/Sq.Rt. of N



Theoretically, high homogenizing effects can be attained by making the number of layers large enough i.e. using very thin layers.

* Cement Engineers' Handbook Originated by Otto Labahn Fourth English Edition by B. Kohlhaas ISBN 3-7625-0975-1

In a iron ore pellet plant based on receipt of concentrate from two locations, a 40,000 T stckpile made by chevron stacking method required 400 layers for getting acceptable variance in Al2O3 & SiO2.

In a cement plant using neighbourhood limestone diposit with some variation in CaCO3 content, a 36000 T stockpile made by chevron stacking method required 90 layers for getting acceptable variance in CaCO3 content. ■

Dear Sir,

We can consult book Edited by Dr. Wohlbier.... Stackin, blending & reclaiming. The chapter written by Mr. Gerstel.

Regards.

A.Banerjee ■