First grind and second bake. The largest advantage of this technique, compared with that of “first grind and second bake”, is energy consumption reduction. Large plaster stone shall be ground into powders with diameter less than 0.2mm, which increases the specific surface when calcining, enlarges the contact area with heat medium, improves calcination heat exchange efficiency and lowers energy consumption greatly. This equipment has small bulk, large production capacity, and simple structure and is hard to destroy.
Analysis on technique features:
I. Concept of technique
Crusher grinds large gypsum into small granules less than 25mm. After storage and measurement with weigh belt, transfer them into Raymond mill for milling. Transfer qualified calcined gypsum powder to clinker bin for storage or to board-manufacturing workshop for usage.
II. Technique’s advantages:
１．Features of first grind and second bake:
Compared with that of first grind and second bake, the largest advantage of this technique is great energy consumption reduction. The reason lies in: great plaster stones are ground into powders with diameter less than 0.2mm, which increases the specific surface when calcining, enlarges contact area with heat medium, improves calcining heat exchange efficiency and lowers energy consumption greatly; the disadvantages are three powder pollution positions in technical process, which shall be solved with dust-removing equipment.
２．Features of two other techniques:
First bake and second grind: due to high energy consumption and low production capability of this technique and that the quality of the products is hard to control and is unstable, at present, it is a kind of backward technique and is seldom adopted. Only a few small factories are still applying it.
Integration of grind and bake: this technique has good features: low energy consumption, small investment, high efficiency, stable quality of the products and small area coverage. Besides, the dust volume is concentrated and is easy for protecting environment. However, it is not mature at home and only BNBM imported from German one set of Peters-mill, which runs to manufacture thistle board.
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