Desulfurization gypsum particles size and grading

                                        Desulfurization gypsum particles size and grading

As a fine granular material, it is easy to ignore the fact that the desulfurization gypsum specific surface area is relatively small, chongqing and taiyuan desulfurization gypsum respectively Bertrand surface 1060 cm2 / g and 1501 g/cm2, is after grinding of 40% and 60% of natural gypsum.

We use laser particle size analyzer was carried out on two kinds of desulfurization gypsum sample particle size analysis, the results show that the desulfurization gypsum relatively average particle size, and not a lot of fine powder, its distribution is very narrow, particles are mainly concentrated in 40 ~ 60 m between, grading far worse natural gypsum grinding fine after gesso. High purity of dihydrate gypsum desulfurization gypsum in chongqing are more obvious, and for taiyuan desulfurization gypsum, due to a large number of fine particles impurities, particles will, in the whole screening accumulation curve to smooth some.

That can be observed from the scanning electron microscopy (sem), after calcining desulfurization gypsum powder its crystal form similar to that of two water desulfurization gypsum, just smaller particle size, particle size distribution characteristics did not change, grading is still not very good, the desulfurization gypsum powder particle specific surface area is natural gypsum powder production line is much smaller. Thus lead to the desulfurization gypsum after adding water flow property is bad, granular segregation, serious statified phenomenon, product density is larger. If use this kind of gypsum for gypsum board, on the one hand, difficult to control the flow of powder, transportation, feeding performance, on the other hand due to the segregation and stratification, will lead to uneven surface strength and density, and protective paper board core bonding problems; Make stucco gypsum can also lead to poor workability and water retention, difficult to operate. Therefore, desulfurization gypsum production process of desulfurization gypsum used should be grinded after calcination. As you can see in table 1-2-17: through the analysis phase composition before and after the grinding, grinding will not change the phase composition of desulfurization gypsum.

Plaster of Paris's specific surface area increased significantly after grinding, water/paste ratio is also expected to increase, standard consistency is according to the measured in DINll68.

Sem photos showed that hydration after desulfurization gypsum crystals are short columnar, makings structure closely, make the hydration hardening body has high strength, desulfurization gypsum sclerotium the apparent strength of the relatively high natural gypsum 10% ~ 20%, also proves that the compact structure of the degree of difference.