We were discussing “Cements and
its types” and " Raw
materials for manufacturing of cements” and “Material preparation technology in cement manufacturing” in our previous posts. We have also
see the concept of cement manufacturing process and its selection in our recent
post.
Today we are going to start here one very important
topic i.e. process technology of cement manufacturing: Storage and pre-blending.
We will understand the various terminologies and engineering concepts used in
cement technology with the help of this category.
Further we will go for discussion of properties
of burning technology, firing technology, clinker cooling and grinding, cement
packing and dispatch, pollution control and much more facts about cement
technology in our next post in this category of cement technology.
Let us see here the process technology of cement manufacturing
Process technology of cement manufacturing: Storage and pre-blending
Buffer stores are required between the crushing and
grinding plants because of the following reasons:
Receipt of the raw materials from the mines is not
continuous as the mines are operated in shifts. The grinding plants, on the
other hand, are operated continuously as far as possible.
To provide better homogeneity in raw materials
before feeding them to the grinding plants due to possible variations in
properties e.g. chemical, physical and mineralogical, depending on the nature
of deposits and the method of exploration.
There are broadly two types of stores:
1. Homogenizing
stores
2. Buffer
stores
Homogenizing Stores
These are rather expensive, especially if they are
covered. The two types of stockpiles most widely used are as mentioned here.
1. Longitudinal
stockpile
2. Circular
stockpile
The quality of the blending bed depends upon the
method of stockpiling. Reclaiming may be done using a Lateral scraper or in a
transverse direction using a bridge type re-claimer fitted with a harrow.
There are two methods usually used for stockpiling
are as mentioned here
1. Chevron
method (Roof method)
2. Windrow
method (Line method)
Blending effect by either method is as high as 1: 10.
However, the Chevron method is cheaper. The stockpiling of horizontal beds by
Chevron method is performed by
1. A
belt conveyor with traveling tripper
2. A
travelling stacker with a rigid boom
The stockpiling of a circular blending bed is
performed by a belt conveyor which is swivel mounted in the beds centre- point.
The blending effect for either system is 1: 10.
However, in the longitudinal system, the materials at the end cone areas of the
stockpile are less homogenized.
Simultaneous operation i.e. stacking and reclaiming
from the same pile is possible in circular stockpile but not in longitudinal
type.
The cost of installation is relatively high for
longitudinal stockpile (higher if it is covered) whereas covered construction
is cheaper for circular stockpile.
The space requirement for a fixed capacity is higher
for a longitudinal stockpile as compared to a circular one.
Expansion of storage capacity in future is possible
In a longitudinal stockpile but not in a circular stockpile.
Quality adjustment in the complete pile due to
chemical variations in raw materials is possible in longitudinal stockpile but
not in circular.
Non - Homogenizing Stores
Buffer stores e.g. the portal scraper type, give o
much lower investment cost and is also suited for sticky material. Additives
and admixtures are stored in this type of stores.
Do you have any suggestions? Please write in comment
box.
We will see other topic i.e. “Process technology of cement manufacturing: Raw grinding plant” in our next post in the category of
Steel and cement technology.
I am very thankful to Mr. Subrata Bhaumik,
Independent cement consultant, for providing such beautiful information and
contents about cement technology.
Mr. Subrata Bhaumik has more than 50 (Fifty) Years
(1965 - 2016) of Experience in Cement and other related Industry covering more
than 100 assignments in cement plants with capacities ranging from 100 tpd to
10,000 tpd in India and abroad involving visit to 25 countries overseas in
connection with work.
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Author of this content, please click the Author profile link below.
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