Raw meal grinding can be divided into dry method and wet method. Dry method generally adopts closed-circuit operation system, that is, raw materials are finely ground by a mill, then separated by a classifier, and coarse powder is returned to the mill for grinding, and most of them adopt the process of drying and grinding materials in the mill at the same time. The equipment used includes tube mill, intermediate discharge mill and roller mill.
Wet process usually adopts open-circuit systems such as tube mill and rod ball mill, which pass through the mill once without reflux, but there are also closed-circuit systems with classifier or arc screen.
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Cement history
1756, British engineer J. Smeaton found that in order to obtain hydraulic lime, limestone containing clay must be used for firing; The ideal composition of masonry mortar for underwater structures is made of hydraulic lime and volcanic ash. This important discovery laid a theoretical foundation for the research and development of modern cement.
In the 20th century, while continuously improving the performance of portland cement, people successfully developed a batch of cement suitable for special construction projects, such as high alumina cement and special cement. There are more than 100 kinds of cement in the world, and the annual output of cement in 2007 is about 2 billion tons.
1952, China formulated the first national unified standard, and determined that cement production should be based on the principle of multi-variety and multi-label. According to its main mineral composition, Portland cement was renamed Portland cement, and later renamed Portland cement, which is still in use today.
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