Combination-Bayer process

In the combination-Bayer process, the bauxite is finely ground with sodium carbonate and sufficient limestone to give a CaO -r SiOa ratio of 2.0 to 2.2 [11.6], The mixture is sintered in a rotary kiln at 1100 °C to calcine the sodium carbonate to sodium oxide (equation 11.6) and the limestone to quicklime (11.7). The sodium oxide reacts with the alumina to form sodium aluminate (11.8) and the quicklime reacts with the silica to produce dicalcium silicate (11.9). 

Liu Yong, Lin Chuxia, Wu Yonggui. (2007). Characterization of red mud derived of from a combined Bayer Process and bauxite calcination method. Journal of Hazardous Material, 146, 255-261. 

The first production of aluminum was by the chemical reduction of aluminum chloride with sodium. The electrolytic process, based on the fused salt electrolysis of alumina dissolved in cryolite, was independently developed in 1886 by C. M. Hall in America and P. L. Heroult in France. Soon afterwards a chemical process for producing pure alumina from bauxite, the commercial source of aluminum, was developed by Bayer and this led to the commercial production of aluminum by a combination of the Bayer and the Hall-Heroult processes. At present this is the main method which supplies all the world s needs in primary aluminum. However, a few other processes also have been developed for the production of the metal. On account of problems still waiting to be solved none of these alternative methods has seen commercial exploitation. 

Bayer MaterialScience (Germany) in the Project "Dream Production" combines part of waste streams of coal-fired power plants, CO2, with the production of polymers. The target is the design and development of a technical process able to produce C02-based polyether polycarbonate polyols on a large scale. The first step was to convert the C02 in new polyols, and these polyols showed similar properties such as products already on the market and can be processed in conventional plans as well (Figure 22). 

Franz, C., Kern, J., Pdtschacher, F. and Bayer, K. (2005) Sensor combination and chemomet-ric modelling for improved process monitoring in recombinant E. coli fed-batch cultivations. JBiotechnol, 120 (2), 183-196. 

Ford Sierra featured the first all-plastic bumper in Europe, and the Ford Taurus and Sable featured the first of these bumpers in the United States. The bumper is molded from GE s Xenoy polycarbonate (PC)/polybutylene terephthalate (PBT) blend. The high impact strength of PC, combined with the resistance to gasoline and oil and the processing ease of PBT, has boosted the use of PC/PBT blends in car bumpers. Bayer s PC/PBT blends are called Makrolon PR. They are used for several automobile impact-resistant parts. 

Limonene as a by-product of orange juice production can be used for polymer production together with CO2 to form a polystyrol-like foam. Menthon can be used as a precursor for branched dicarbonic acids and alpha-pinen (a by-product of the forest industry) as precursor for cymol production or for enzymatic verbenone production. Other important terpenoids are phytosterols. They are used in the production of steroid hormones such as cortison or progesteron by Bayer Sobering Pharma. Probably the most important example where plant secondary metabolism and microbial fermentation are synergistically combined, steroid hormones, are produced from phytosterols. A fermentation process by Bayer Schering Pharma uses a plant metaboUte and converts it by a single-step microbial fermentation into the desired end product. 

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