Natural raw materials of cement production is mainly calcareous material (limestone, marble, etc.), accounting for 70% to 90% of the feed composition, the ingredients for the raw clay, siliceous raw materials and iron-aluminum feedstock like. Cement production is to crush, pre-homogenize and compound the raw materials, prepare them into raw materials after grinding, and calcine them into rotary kiln or shaft kiln to form cement clinker. After clinking, the clinker is added with gypsum and different mixed materials. Different types of cement can be produced. The various ordinary cements produced in China account for more than 90% of the total output. Other special cement varieties include oil well cement, medium and low heat cement, white cement and iron aluminate cement.
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The beneficial components of Portland cement clinker are mainly CaO, SiO 2 , Al 2 O 3 , Fe 2 O 3 , tricalcium silicate (3CaO•SiO 2 ) and dicalcium silicate (2CaO) in the mature component. • SiO 2 ), tricalcium aluminate (3CaO•Al 2 O 3 ), tetracalcium aluminate (4CaO•Al 2 O 3 •Fe 2 O 3 ). CaO is mainly derived from calcareous raw materials, and SiO 2 , Al 2 O 3 , and Fe 2 O 3 are mainly derived from clay raw materials, and insufficient from silicon raw materials, aluminum raw materials, and iron raw materials. In order to obtain the clinker that meets the requirements, the saturation coefficient (KH), the silicic acid ratio (SM) and the aluminum oxygen ratio (AM) of the clinker are generally controlled within a certain range, and the corresponding mineral components and chemical components in the clinker are required. Control is within a certain range.
The harmful components of cement clinker are MgO, K 2 O, Na 2 O, SO 3 , fSiO 2 (free silica), and Cl. National standards stipulate that the content of MgO in cement or clinker should not exceed 5%; generally, the content of K 2 O and Na 2 O in cement should not exceed 1.5%. When producing low alkali cement, alkali content (Na 2 O) is required. + 0.658 K 2 O) Less than 0.6%, or agreed between the supplier and the buyer; there are some special requirements when producing special cement. The content of SO 3 in cement clinker is generally not more than 1.5%, and the content of large particles fSiO 2 in calcareous raw materials is not more than 4% ( vermiculite) or 6% ( quartz ). When using new dry precalcining rotary kiln production, The content of Cl in the raw meal is required to be no more than 0.015%.