Bayer’s process

The alkali process uses sodium hydroxide and is well known as Bayer s process. It involves relatively simple inorganic and physical chemistry and the entire flowsheet can be divided into caustic digestion, clarification, precipitation and calcination. Although mineral assemblage in bauxites is extensive, processing conditions are primarily influenced by the relative proportions of alumina minerals (gibbsite and boehmite), the iron minerals (goethite and hematite), and the silica minerals (quartz and clays-usually as kaolinite). 

With the exception of bayerite, all these hydroxides occur in nature. Hydrargillite is the main form in the final product of the Bayer s process. 

Recently, Bayer reported a promising PO space-time yield of more than 0.2 gpo gcat h, with selectivity for PO of 95%, obtained with a propene/oxygen/hydrogen feed of molar composition 30 10 60, at 180 °C and 2 atm pressure [41a[. However, as with the other catalysts, the main problem was a rapid catalyst deactivation. Key issues of Bayer s process include ... 

There are several processes available for the manufacture of cryoHte. The choice is mainly dictated by the cost and quaUty of the available sources of soda, alumina, and fluoriae. Starting materials iaclude sodium aluminate from Bayer s alumina process hydrogen fluoride from kiln gases or aqueous hydrofluoric acid sodium fluoride ammonium bifluoride, fluorosiUcic acid, fluoroboric acid, sodium fluosiUcate, and aluminum fluorosiUcate aluminum oxide, aluminum sulfate, aluminum chloride, alumina hydrate and sodium hydroxide, sodium carbonate, sodium chloride, and sodium aluminate. 

Pilz, V. (1995). Bayer s Procedure for the Design and Qperation of Safe Chemical Plants. Inherently Safer Process Design, 4.54-4.65. Rugby, England The Institution of Chemical Engineers. 

A few years later, an Austrian chemist, Karl Joseph Bayer, refined Hall s process, and it is now called the HaU-Heroult or Bayer process, which is the method used today for obtaining aluminum at very reasonable prices... 

The GMP s process eliminates the use of sheet metal for the skin of the refrigerator door. In this application, the thermoplastic film forms a durable, protective outer skin with a wide choice of color options that are applied directly to the film. In addition more innovations exist apart from the film and thermoplastic interior liner, the doors consist entirely of polyurethane. GMP backs the thermoplastic film with an approximately 4 mm thick layer of the Baydur 110 structural foam polyurethane RIM system from Bayer AG that creates a rigid, dimensionally stable outer shell with no need for sheet metal. Then, GMP fills the space between this shell and the inner liner with insulating polyurethane foam, a rigid, low-density foam. The result is a self-supporting door that satisfies all stability, thermal insulation, and surface finish requirements. 

This durable, new composite is extremely strong, and yet it weighs 25% less than steel. Some HarvestForm panels will utilize Bayer s Baydur structural foam polyurethane RIM system, which utilizes a soybean-based polyol component. This structural foam PUR RIM formulation is based on soybeans that would produce physical properties and processing parameters equivalent to Bayer s conventional formulations. 

Other catalytic systems that generate long chain-branched polyolefins have been reported such as Dow s half-sandwich constrained geometry titanium catalysts (CGC) [14e], and Bayer s novel donor/acceptor metallocenes [14f]. This polymer structural feature improves material and processing properties. 

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. 

Electronic applications for Bayer s Desmopan thermoplastic PU film include a solar cell encapsulation process. In November 2005, Bayer revealed that its new manufacturing process for the innovative carbon nanotubes had reduced their manufacturing cost. Bayer has also introduced formable PC films which incorporate EMI/RFI shielding. This is obtained by printing them with conductive ink or by dispersing the ink into the cap layer of the sheet. 

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