Aluminum processing

In this type of system, silicon is leached out by manganese in the 3003 layer, leaving a corrosion-resistant third layer. The process described is critical, especially with automobile condenser production. In the case of condensers, the tubes used to carry high-pressure refrigerant need to be extruded. These extruded tubes need to be brazed in order to maintain the structural integrity of the thin design (100 pm). 

In the profile in the figure, the 250°F point is where the thermal degreasing takes place. The intent is to thermally remove oils utilized in earlier operations. The actual brazement takes place at the 1100°F point. It is necessary to keep a steady, consistent mass of material (thermal mass) going through the oven to maintain proper mass transfer of heat into the parts being brazed. 

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Production of hydrogen fluoride from reaction of Cap2 with sulfuric acid is the largest user of fluorspar and accounts for approximately 60—65% of total U.S. consumption. The principal uses of hydrogen fluoride are ia the manufacture of aluminum fluoride and synthetic cryoHte for the Hall aluminum process and fluoropolymers and chlorofluorocarbons that are used as refrigerants, solvents, aerosols (qv), and ia plastics. Because of the concern that chlorofluorocarbons cause upper atmosphere ozone depletion, these compounds are being replaced by hydrochlorofluorocarbons and hydrofluorocarbons. 

However, in heavy industry, meaning metallurgical (steel and aluminum) processes, mining, petroleum refining, pulp and paper production, and the process industries like ehemical and pharmaceutical production, potable water, wastewater, edible products, and manu-... 

In 1885, Charles Martin Hall invented his aluminum process and Hamilton Young Castner in 1890 developed the mercury-type alkali-chlorine cell, which produced caustic (sodium hydroxide) in its purest form. Edward G. Acheson in 1891, while attempting to make diamonds in an electric furnace, produced silicon carbide, the first synthetic abrasive, second to diamond in hardness. Four years later, Jacobs melted aluminum oxide to make a superior emeiy cloth. Within two decades, these two abrasives had displaced most natural cutting materials, including naturally occurring mixtures of aluminum and iron oxides. 

The material inputs and pollution outputs resulting from primary and secondary aluminum processing are presented in Table 3.4. 

Wastewaters generated from primary aluminum processing are produced during clarification and precipitation, although much of this water is fed back into the process to be reused. 

A very limited amount of individual plant specific data for the aluminum forming industry is available. Data available on the influent and effluent streams are discussed briefly in the following subsections for specific plants. This aluminum processing plant uses lime precipitation (pH adjustment) followed by coagulant addition and sedimentation as its treatment system. Data... 

Use of Less Hazardous Acid or Alkaline Compounds. The aluminum processing industry employs deoxider and desmutter systems in which chromic acid is used. This... 

Peterson, W.S. Hall-Herouit Centennial—First Century of Aluminum Process Technolog) —1886-1986, The Metallurgical Society, London, 1986,... 

Castner, Hamilton Young — (Sep. 11, 1858, Brooklyn, New York, USA - Oct. 11,1899, Saranac Lake, New York, USA) Castner studied at the Brooklyn Polytechnic Institute and at the School of Mines of Columbia University. He started as an analytical chemist, however, later he devoted himself to the design and the improvement of industrial chemical processes. He worked on the production of charcoal, and it led him to investigate the Devilles aluminum process. He discovered an efficient way to produce sodium in 1886 which made also the production of aluminum much cheaper. He could make aluminum on a substantial industrial scale at the Oldbury plant of The Aluminium Company Limited founded in England. However, - Hall and - Heroult invented their electrochemical process which could manufacture aluminum at an even lower price, and the chemical process became obsolete. Castner also started to use electricity, which became available and cheap after the invention of the dynamo by - Siemens in 1866, and elaborated the - chlor-alkali electrolysis process by using a mercury cathode. Since Karl Kellner (1851-1905) also patented an almost identical procedure, the process became known as Castner-Kellner process. Cast-... 

Fig. 1.23. Direct injection of aluminum processing solution. Conditions Supelco LC-18 DB column gradient program at a flow rate of 1.0 ml/min from 0.05 mol/l HIBA to 0.4 mol/1 HIBA over 10 min and held at 0.4 mol/1 for 5 min modifier, 1-octanesulfonate at 1 x 10 2 mol/1 Curve (A), eluents at pH 3.8 Curve (B), eluents at pH 4.5 detection at 658 nm after post-column reaction with Arsenazo III sample, 50 pi sample dilution, 20 ml...

More than one boride phase can be formed with most metals, and in many cases a continuous series of solid solutions may be formed. Several methods have been used for the relatively large-scale preparation of metal borides. One that is commonly used is carbon reduction of boric oxide and the appropriate metal oxide at temperatures up to 2000 °C. Fused salt electrolysis of borax or boric oxide and a metal oxide at 700 1000 °C have also been used. Small-scale methods available include direct reaction of the elements at temperatures above 1000 °C and the reaction of elemental boron with metal oxides at temperatures approaching 2000 °C. One commercial use of borides is in titanium boride-aluminum nitride crucibles or boats for evaporation of aluminum by resistance heating in the aluminizing process, and for rare earth hexaborides as electronic cathodes. Borides have also been used in sliding electrical contacts and as cathodes in HaU cells for aluminum processing. 

The practical utilization of silicon carbide and silicon nitride ceramics or of SiAlON in the above-mentioned application sectors has steadily increased in recent years. Ca. 400 t/a of SN-powder is currently consumed in the manufacture of SN-components. The main applications are for cutting tools, roller bearings, dosing and deliver pipes for aluminum processing, as well as a multiplicity of other components which enjoy the advantages of SN-ceramics. 

Power costs for aqueous chlor-alkali cells amount to about 50% of the total operating costs and almost 75% for water electrolysis. Molten salt sodium and aluminum processes are even more power intensive than chlor-alkali cells. 

Describe how the weak monoprotic acid hydrofluoric acid, HF (used in aluminum processing) acts when it is added to water, including a description of the nature of the particles in solution before and after the reaction with water. 

Aluminum salts precipitate all pectins, and this principle has been applied in the commercial production of pectins (8). The aluminum process as applied to high-methoxyl pectins accounts for over 1,000,000 pounds of powdered pectin per year, or about 15% of present production. On the other hand, the calcium process for low-methoxyl pectins is seldom used, perhaps because of lack of fundamental knowledge about calcium pectinates and the preference of industry for alcohol precipitation. 

O. Midling, L. Oosterkamp, and J. Bersaas, Friction Stir Welding Aluminum—Process and Applications, INALCO 98, Seventh Int. Conf. Joints in Aluminum (Cambridge, U.K.)... 

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