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PAHs (according to EPA 610) in the exhaust gas of rotary kilns usually appear at a distribution dominated by naphthalene, which accounts for a share of more than 90% by mass. The rotary kiln systems of the cement industry destroy virtually completely the PAHs input via fuels. Emissions are generated from organic constituents in the raw material.
A rotary kiln is a pyroprocessing device used to raise materials to a high temperature (calcination) in a continuous process. Materials produced using rotary kilns include: Cement; Lime; Refractories; Metakaolin; Titanium dioxide; Alumina; Vermiculite; Iron ore pellets; They are also used for roasting a wide variety of sulfide ores prior to ...
The first kiln at the Coplay Cement Company was a dome kiln. Dome kilns were inefficient; they had to shut down often. In 1893 Coplay Cement built Mill B, containing the Schoefer kilns standing today. Originally enclosed in a large building, Schoefer kilns could run continuously. Soon, however, the even more efficient rotary kilns came into use.
Biscuit kiln: The first firing would take place in the biscuit kiln. Glost kiln: The biscuit-ware was glazed and given a second glost firing in glost kilns. Mantou kiln of north China, smaller and more compact than the dragon kiln; Muffle kiln: This was used to fire over-glaze decoration, at a temperature under 800 °C (1,500 °F). In these ...
This became a specification for portland cement. The next development in the manufacture of portland cement was the introduction of the rotary kiln, patented by Frederick Ransome in 1885 (U.K.) and 1886 (U.S.); which allowed a stronger, more homogeneous mixture and a continuous manufacturing process. [3]
In 1893, the company exhibited at the World's Fair in Chicago. 1898 saw the design and manufacture of the first rotary cement kiln in Europe. This was followed in 1912 by the construction of the Jesarbruch plant near Nienburg (Saale) for the Sächsisch-Thüringische Portland-Cement-Fabrik Prüssing & Co. KGaA.
Portland cement clinker is made by heating a homogeneous mixture of raw materials in a rotary kiln at high temperature. The products of the chemical reaction aggregate together at their sintering temperature, about 1,450 °C (2,640 °F).
Chromium present in the cement as Cr[III] is of no consequence. Mn 2 O 3 is not deleterious, acting as a substitute for iron. But it contributes more color to the cement than iron, and high-Mn 2 O 3 cements (>1%) are almost black. ZnO is encountered in some rawmix additives (as well as tires used as kiln fuel). At levels above 0.2%, it causes ...