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Neu-Ulm, Germany

Bauer K.,Schwenk Zement KG | Hoenig V.,Verein Deutscher Zementwerke VDZ
Cement International | Year: 2010

Discussions of efficient production processes in the cement industry generally focus on assessments of cement works performance levels measured as fuel energy consumption in a performance test lasting 24 to 48 hours. The fuel energy requirement is also listed in the BAT (Best Available Techniques) Reference Document, abbreviated to BREF, for the cement industry, a document used, for example, by the licensing authorities as a basis for evaluation when formulating approvals. This value cannot, by itself, do justice to the wide scope influencing parameters on the clinker production process and is thus insufficient for assessing normal operations, even over fairly short periods. The objective was therefore formulated of obtaining a description of the performance capability of a cement works that reflects the entire scope of the phenomena occuring in actual practice. With the help of extensive calculations based on a process engineering model developed at the Research Institute of the Cement Industry and using experimental data collected from the cement industry, it is now possible to quantify the essential operational parameters that influence performance. For example, this approach facilitates a clear and reliable description of production lines with widely differing fuel energy requirement levels, due for example to kiln capacities or the properties of both fuel and raw materials. These plants can nevertheless operate on the energy efficiency level. The modelling results have been used as a basis within the revision process of the BREF for the cement industry. Source

Szabo L.,Duna Drava Cement Ltd. | Csoerge V.T.,Duna Drava Cement Ltd. | Braig T.,Schwenk Zement KG
Cement International | Year: 2010

At the Beremend cement plant of the Hungarian cement producer Duna-Drava Cement Ltd. (affiliated to HeidelbergCement and Schwenk Zement KG), one of the two old 1500 t/dclinker 4-stage preheater kilns was modernised with an extended capacity of 3450 t/dclinker. The results of the project outlined in this article present the equipment selection procedure and first operational experiences during the commissioning phase. During the modernization, the preheater cyclones were replaced by a new 4-stage DOPOL-90 preheater tower in front of the old one. The old tower was used to install the PREPOL AS-MSC calciner and the alternative fuels dosing systems. The kiln system contains in addition the new gas conditioning tower, baghouse filters for kiln, by-pass system and for the POLYTRACK 7/4.0 clinker cooler as well as the process control system. As a result of the efficient cooperation between DDC's project management and the main contractor Polysius AG, who supplied the equipment on semi-turnkey contract basis, the project was successfully completed on time. Duna-Drava Cement took a big step in achieving its long-term production goal for steady and sustainable development. Source

Trenkwalder J.,Schwenk Zement KG
Cement International | Year: 2010

Since 1969 at the cement plant in Karlstadt a rotary kiln with a daily capacity of 3500 t has been in operation for the production of cement clinker. This kiln system from the Polysius corporation is fitted with a 4-stage Dopol preheater, the kiln is 90 m long and has a Claudius Peters grate cooler. This existing plant was expanded by Schwenk to include integrated technology designed for the dehydrating and incineration of sludge, an exemplary concept which today is the only one of its kind in the cement industry. One hundred percent of the thermal energy for the heating of the dryer is obtained from the exhaust air of the clinker cooler. The decoupled waste heat is transported via a thermal oil system to the heat exchangers installed in the dryer. This drying system represents one of the world's largest single-stage belt dryers, with a dehydration capacity of 8 t/h, the annual throughput is roughly 100000 t. With this novel installation concept a highly innovative and environmentally friendly solution was created, and the company has set standards in terms of environmental protection, sustainability and resource conservation. Source

Trankle S.,Universitatstrasse 1 | Jahn D.,University of Salzburg | Neumann T.,Schwenk Zement KG | Nicoleau L.,BASF | And 2 more authors.
Journal of Materials Chemistry A | Year: 2013

The naturally occurring mineral 11 Å tobermorite is an important calcium silicate hydrate phase often used as a model structure for the poorly ordered calcium silicate hydrate phase (C-S-H) present in hydrated cement. In this work we present a hydrothermal synthesis of highly crystalline anomalous 11 Å tobermorite by conventional and microwave treatment. The microwave assisted synthesis provides a faster access to crystalline 11 Å tobermorite material in terms of reaction time, while the conventional method yields samples with a higher crystallinity. For conventional hydrothermal synthesis borosilicate glass was used as a Si precursor, which proves to be an excellent starting material for synthesis of highly crystalline 11 Å tobermorite. Furthermore, to the best of our knowledge, this is the first time the synthesis of unsubstituted 11 Å tobermorite by microwave synthesis is described. IR- and 29Si-NMR spectroscopy reveals Q3 Si-O tetrahedra sites only present in the double "dreierkette" structure typical for 11 Å tobermorite. The water content of the synthesized calcium silicate hydrates was examined by TGA which shows a weight loss (corrected for the loss of CO2 from carbonate) of 8.3-10.7% for tobermorite samples from conventional synthesis and 10.6-12.5% for those from microwave assisted synthesis. While samples from microwave assisted synthesis typically showed a water loss from hydroxyl groups from DTG data at ∼760 °C, this could not be observed for tobermorite from conventional synthesis. By XRD investigations at different temperatures it could further be shown that the samples consist of the anomalous form of 11 Å tobermorite. The morphology of the needle-like tobermorite crystals was examined by AFM and HRTEM. The layered structure of 11 Å tobermorite could be visualized via the HRTEM investigations and the basal spacing of ∼11 Å could be measured directly. © 2013 The Royal Society of Chemistry. Source

Fylak M.,Schwenk Zement KG | Pollmann H.,Martin Luther University of Halle Wittenberg | Wenda R.,Nurnberg University of Applied Sciences
34th International Conference on Cement Microscopy 2012 | Year: 2012

Advanced Cryo preparation techniques open new ways for SEM investigations on hydrating cementitious systems. Common SEM analyses are not practicable at early hydration times because of the hydrous or liquid state of cement pastes. Preparation and analysis of older specimens often cause a formation of artefacts. The Cryo preparation allows setting liquid, beam and vacuum sensitive specimens into a stable state by shock-freezing. Thus this method enables proper SEM preparations for all kinds of cementitious systems. Fast freezing processes allow sample preparations at very low hydration times and high resolution imaging of cement particles and hydration products. Already after a few seconds of reaction investigations of crystal structures, characterisations of microstructure and EDS analyses are possible. The article shows results of Cryo-SEM investigations combined with in-situ XRD and isothermal Heat Flow Calorimetry. The different methods are combined for early time hydration studies of Portland cements from one minute to three days reaction time. Results are crosslinked to receive detailed information about microstructure, phase development and hydration kinetics. The focus lies on very early hydration products (first minutes), changes in ettringite morphology and C-S-H microstructures. Applications and possibilities of Cryo preparation techniques are discussed. Source

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