Aluminum industrial importance

Scrap that is unsuitable for recycling into products by the primary aluminum producers is used in the secondary aluminum industry for castings that have modest property requirements. Oxide formation and dross buildup are encountered in the secondary aluminum industry, and fluxes are employed to assist in the collection of dross and removal of inclusions and gas. Such fluxes are usually mixtures of sodium and potassium chlorides. Fumes and residues from these fluxes and treatment of dross are problems of environmental and economic importance, and efforts are made to reclaim both flux and metal values in the dross. 

The type of attack that occurs in liquid media is highly dependent on the chemical nature of the liquid—that is, molten metal, molten ceramic, or aqueous solution. We will consider two industrially important cases attack by molten metals and attack by aqueous media. The attack of most metal oxide ceramics by molten metals involves a simple exchange of one metal ion for another. For example, silicon dioxide in contact with molten aluminum is susceptible to the following corrosion reaction ... 

Ipatieff and Grosse4 showed in 1936 that n-butane is isomerized to isobutane by properly promoted aluminum chloride. The importance of isobutane in the alkylation of alkenes and the possibility of converting n-alkanes of low octane values into branched high-octane alkanes for gasoline quickly resulted in much research that furnished information of both theoretical and industrial importance.5-11... 

The production of industrially important perfluoroalkane sulfonic acids is generally accomplished by electrochemical fluorination. This method of preparation remains expensive and proceeds in good yields only for short hydrocarbon chains.30 Recently however, Wakselman and Tordeux have described a chemical method for the preparation of trifluoromethane sulfonic acid.31 The procedure involves reaction of a metal selected from zinc, cadmium, manganese, and aluminum with sulfur dioxide in DMF, followed by the introduction of trifluoromethyl bromide under slight pressure. The intermediate sulfinate is subsequently oxidized by hydrogen peroxide, and then hydrolyzed which leads to formation of the trifluoromethane sulfonic acid. Successful extension of the sulfination process to the modification of PCTFE should result in the formation of a sulfinated polymer which can ultimately be oxidized to give a sulfonic-acid modified polymer. 

An interesting property of HNO3 is its ability to passivate some metals, such as iron and aluminum. This property is of significant industrial importance, since modem processes for producing the acid depend on it. Modern suitability formulated stainless sleel alloys are usefully resistant to nitric add through a wide range of conditions. The acid s passivity or the metal s resistance to attack is attributed to the formation of a protective oxide layer on the surface of the metal. 

It is the purpose of this paper to review the important factors which affect anode carbon usage in the aluminum industry, Consideration is given to the entire chain of events affecting carbon consumption, from the properties of the precursors for filler cokes and binder pitches, through production of these raw materials and their fabrication into anode carbon, and concluding with anode performance evaluation in full-size prebake and Soderberg cells of different designs. 

Aluminum is the most abundant metal and the third most abundant element in the Earth s cmst, behind only oxygen and silicon. Its low weight and useful properties make aluminum and its alloys valuable materials for manufacturing and electrical applications. Inorganic compounds of aluminum are plentiful and used as absorbents, catalysts, ionic conductors, ceramics, and electrical materials. Organometalhc compounds of aluminum are also of great industrial importance and fundamental discoveries continue to be made regarding the variety of coordination numbers, structures, oxidation states, and reactivity exhibited by aluminum. ... 

Oxygen, silicon, aluminum, iron, calcium, sodium, potassium, and magnesium constitute 99% of the Earth s crust. If the next four most abundant elements—titanium, hydrogen, manganese, and phosphorus—are included, then nearly 99.9% of the composition of the crust is explained. That is, most of the industrially important elements, aside from iron and aluminum, make up a very small proportion of the Earth s crust. If we define the scarce elements as those with average abundances less than 1,000 ppm (i.e., elements with abundances less than that of phosphorus), then the 80 or so scarce elements amount to about one-tenth of 1 wt.% (0.1%). 

Two molecules of aluminum chloride for each molecule of the anhydride are employed in the reaction. If chlorobenzene is used in place of benzene a substituted o-benzoylbenzoic acid is formed (4 -chloro-2-benzoylbenzoic acid). The preparation of these substituted keto acids is of industrial importance, as by cyclization they form anthraquinone derivatives. 

Lithium hydride Lithium hydride is manufactured from metallic lithium and hydrogen. It is industrially important as a source of hydrogen and as a reducing agent in organic synthesis, particularly in the form of its derivatives lithium aluminum hydride and lithium borohydride. 

The most important compounds apart from aluminum silicate-based ceramics and clay products are aluminum hydroxide and aluminum oxide, since they are raw materials in the manufacture of aluminum. Other industrially important aluminum compounds are aluminum sulfate, aluminum chloride, sodium aluminate, aluminum fluoride and cryolite (see Section 1.7.1). 

Production processes other than the melt electrolysis of aluminum oxide, such as the energetically more favorable and environmentally more favorable electrolysis of aluminum chloride, have only minor industrial importance. 

The industrial manufacture of aluminum hydroxide and aluminum oxide currently proceeds almost exclusively by the Bayer process i.e. by wet digestion of bauxite. The sinter- and melt-digestion processes with sodium carbonate and/or lime only have minor industrial importance. 

Sodium aluminate (theoretical formula NaA102) has a certain industrial importance not only as an intermediate in the digestion of bauxite in the Bayer process (see Section 3.2.4.2). USA production of sodium aluminate in 1993 was estimated to be 85 10- t/a. Sodium aluminate is produced by dissolving hydrated aluminum oxide in 50% sodium hydroxide. It is utilized in water purification, in the paper industry, for the post-treatment of Ti02-pigments, for the manufacture of aluminum-containing... 

This article has described the Hall-Heroult cell that is the mainstay of the aluminum industry throughout the world. Emphasis has been on the electrochemistry and electrochemical engineering that govern cell performance. The cell operation, electrolyte chemistry, thermodynamics, and electrode kinetics have been reviewed. Some complexities, notably the anode effect and the environmentally important fluoride emissions and anode gas bubbles and their effect on cell voltage, flow, and CE, have been examined. The incorporation of these phenomena, along with current distribution, magnetic fields, electromagnetically driven flow, heat and mass transport, and cell instability into mathematical models was summarized. 

Irrespective of these controversies, research in this intriguing area is crucially important from both fundamental and applied points of view. For instance, solid electrolytes and mixed conductors with mobile AP + cations may find applications in new types of rechargeable battery, and also in the aluminum industry alkaline-earth cation conductors may be used, in particular, for precise humidity control in gaseous media and for CO2 sequestration. This chapter includes a brief introduction to the field, with emphasis placed primarily on the authors own studies. Although many aspects of materials electrochemical behavior require detailed investigation and further validation, the chapter provides an excellent overview of the phases where multivalent cation conduction may occur. 

In 1958, plastics production reached and slightly exceeded total U.S. supply of aluminum, including imports. Figure 2 compares the growth of the two industries since 1960. In looking at this graph and considering... 

Tribromo-l,3,5-triazine (cyanuric bromide) has no industrial importance. It is prepared in 60% yield by the addition of aluminum tribromide to a solution of cyanogen bromide in nitromethane at 40 - 60"C.220 Cyanuric iodide, which cannot be prepared by the trimeriza-tion of cyanogen iodide, can be obtained by the halogen-exchange reaction of cyanuric chloride and hydrogen iodide (cf. Section 2.3.1.5.5.l.l.l.)221... 

Trialkylaluminum compounds are colorless liquids at room temperature. Must be stored in an inert atm sensitive to oxidation and hydrolysis in air the lighter trialkylalumi -ntims ignite spontaneously in air. The low mol wt, linear-chain alkyl compounds exist as dimers the branched-chain alky] compounds exist primarily as monomers. Among the industrially important trialkyl aluminums are triethylalmm-nuut (dimeric liq, dB 0.832. bp 194°, bp,3 100°) and triiso-butylaluminum (primarily monomeric liq. dB 0.781 bp. 86°, mp 6°). 

Aluminum. Aluminum is used extensively in modem India particularly in house wiring and the transmission of electrical power, about 50% of the production going for this use. All of the technology has been imported primarily from the United States. Production has increased from about 3000 metric tons in 1951 to 180,000 metric tons in 1977. It is estimated that the demand for aluminum in 1984 will be 400,000 metric tons. The demand is likely to increase dramatically since the per capita use in India is 0.4 vs. 22 kg in the United States and of 2.9 kg in the rest of the world. Aluminum today is produced in five producing plants, four of them in the private sector and one in the pubhc sector. The most serious problem with the aluminum industry is the pricing pohcy. By law, 50% of production goes to the government at a fixed price, so-called levy metal. The current levy price is 903 a metric ton vs. a production cost of 1,084 per metric ton. 

Zeolites. A large and growing industrial use of aluminum hydroxide and sodium aluminate is the manufacture of synthetic zeolites (see Molecular sieves). Zeolites are aluminosilicates with Si/Al ratios between 1 and infinity. There are 40 natural, and over 100 synthetic, zeoUtes. All the synthetic stmctures are made by relatively low (100—150°C) temperature, high pH hydrothermal synthesis. For example the manufacture of the industrially important zeolites A, X, and Y is generally carried out by mixing sodium aluminate and sodium silicate solutions to form a sodium aluminosilicate gel. Gel-aging under hydrothermal conditions crystallizes the final product. In special cases, a small amount of seed crystal is used to control the synthesis. 

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