The cement factory proprietors of Südbayerische Portland-Zementwerke Gebr. Wiesböck & Co. GmbH have for many decades fully embraced their social, ecological and economical responsibilities. Continuous modernization and upgrading projects have safeguarded production at the factory location in Rohrdorf ( Fig. 1 ). The company’s latest projects are an SCR system and a waste heat recovery system [1, 2]. These were reason enough for ZKG INTERNATIONAL to present an overview of the whole factory. History The factory was established in 1930 as the family business of the Wiesböck brothers. Originally, the company quarried natural stone, but it later changed over to the production of cement. Despite initial scepticism, this business became more and more profitable. The commencement of an economic upswing made the situation more difficult, as a number of competing factories were set up in the surrounding area. At that time, a production limit of 6000 tpy was imposed on the factory. Despite this restriction, and with a generous interpretation of the imposed limit, business developed positively, so that the company participated actively in the years of the German‚ ‘economic miracle’. This was followed by a period of diversification, and the raising of the Iron Curtain prompted a great trend for economic engagement in Eastern Germany. In addition to the factory in Bavaria, the company now operates a grinding plant in Eiberg near Kufstein and a cement works in Gmunden/Austria. When Austria joined the EU the factory started supplying the Austrian region, i.e. the company served the entire surrounding market. The Rohrdorf Group presently has a turnover of around 250 million €, generated by five fields of activity: cement, ready mixed concrete, sand and gravel, concrete products and precast elements. On the cement sector the company operates two cement factories with clinker production and one grinding plant, two mixing plants in Gmunden and Rohrdorf for special products and 11 quarries. It also has a major shareholding in a recycling company manufacturing alternative fuels. More than 1000 people work for the group. Corporate philosophy “ Everything we do, we do a little sooner ” said Heinrich Rodlmayr, the company manager responsible for technology. “ Innovation has always been a central aspect of our corporate philosophy ” , he added. For example: the factory was one of the very first to install a X-ray fluorescence system for raw material analysis. Rohrdorf also pioneered the usage of alternative fuel and raw materials, such as no longer recyclable foundry sand ( Fig. 2 ) and waste products from Tetra Pak recycling. This strategy helps to ensure long-term production at the various Rohrdorf Group locations and to safeguard jobs. The production line The raw materials are transported from the quarries to the factories by railway or truck (Eiberg Plant). The company possesses concessions for the next 127 years, so there is no reason to doubt raw material availability. However, transportation of the materials from some of the more distant quarries is quite expensive, making it necessary to achieve savings in other areas, e.g. energy costs. The raw material is fed into a crusher and then transported to a blending bed. Raw material grinding is performed by a Quadropol vertical roller mill (260 t/h), after which the raw meal is supplied to a DOPOL preheater ( Fig. 3 ). The raw mill was put into operation in 2006, replacing the original ball mill that represented a bottleneck in the production process. This modernization measure increased the plant’s capacity from 3000 to 3500 tpd. In addition, the kiln inlet zone and the upper cyclone stage were modified and a new kiln exhaust gas fan was installed. At the same time, the electrostatic precipitator serving the plant was replaced with a combined bag filter for the kiln and raw mill. Alternative fuels and raw materials The employed alternative fuel ( Fig. 4 ) is a mixture of shredded tyres and roofing felt, which is supplied to the preheater. In addition, paper rejects are burnt in the kiln inlet zone. The alternative raw materials fed to the kiln inlet are foundry sands and a special lime, which is a waste product of the calcium cyanamide (lime-nitrogen) production process and also contains ammonia. The special lime has an effect like a non-controlled SNCR system, which brings the disadvantage that the plant previously had a very high volatile ammonia emission. This problem has been eliminated through the installation of a new SCR system. The average annual thermal substitution rate is 77 %. The company has a permit operation with a rate of 100 %....
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