Crystallization is the process by which a solid material precipitates from a vapor, solution, or melt in a crystalline state. A lot of chemical production process includes the crystallization of the basic unit operation. In liquid phase industrial crystallization, establishing an appropriate supersaturation in solution and controlling it is the most important issue in the crystallization process.
A simple classification of the production method of the crystal by way of generation of supersaturation:
(1) cooling crystallization
(2) evaporation crystallization
(3) flash crystallization
(4) reaction crystallization
(5) salting-out crystallization
The production of continuous classification of the crystallization of production methods are classified:
(1) intermittent crystallization
(2) continuous crystallization
(3) semi-continuous crystallization
Continuous crystallization is the trend of development in the era of large-scale industrial production. In the process of system operation, the crystallization device maintains continuous feeding and discharges continuously. The production status of the production line avoids batch differences of products and reduces the labor intensity of operators. In particular, For large-scale automated production.
The role of the mold wall, one is to support the molten steel in the mold to form a blank shell, the second is the molten steel and the heat within the shell out, to accelerate the formation of the shell. With the increase of the thickness of the billet, the billet section should gradually shrink. In order for the mold to function as described above, the cross section of the mold must vary with the continuous shrinkage of the slab section, which can be achieved by making the crystallizer a certain taper. Taper size must be appropriate, too large a taper will cause mold squeeze the blank shell, leading to corner depression, the shell and the mold friction increases, increasing the wear of the mold, but also the surface of copper. In the corner area due to the role of the air gap will form a hot spot, causing the shell thinning and cracking. Conic small will make the air gap increases, heat flow decreases, the shell thinning, prone to breakout; the other will be too small taper corner rotation, induced subcutaneous cracks and longitudinal depression. Due to the nonuniformity of the air gap thickness and the irregular shape of the air gap in the longitudinal direction of the mold, a single taper mold does not well eliminate the adverse effect of the air gap, especially in continuous casting of mild steel or high speed continuous casting When the problem is more obvious. For this reason, along with the development of high-speed continuous casting, the development of double taper, three taper, four taper and parabolic taper multi-taper mold, taper mold in the longitudinal shape more in line with the actual laws of the crystal shell, better To adapt to the shrinkage of the blank in the longitudinal direction of the mold so that the thickness of the air gap in the longitudinal direction of the mold is further reduced to better eliminate the adverse effect of the air gap and increase the heat transfer effect of the entire mold for the high- Provided a guarantee.