Production of aluminum

Of the fluoroaluminates known, cryoflte, ie, sodium hexafluoroaluminate [15096-52-2], Na AlF, has been an integral part of the process for production of aluminum. Recently, the mixtures of potassium tetrafluoroaluminate [14484-69-6], KAIF, and potassium hexafluoroaluminate [13575-52-5], K AlFg, have been employed as bra2ing fluxes in the manufacture of aluminum parts. 

The principal producers of aluminum trifluoride in North America are Alcan, Alcoa, and AUiedSignal. It is also produced in other countries, eg, France, Mexico, Norway, Italy, Tunisia, and Japan. Total worldwide production of aluminum trifluoride in 1990 was 400,000 metric tons and the price was 1100/t. In 1993, because of excess recovery of fluorine values, use of energy efficient smelters, and the worldwide economic climate, the price was down to 750/t. 

A low grade fluoroboric acid (16) is used in the manufacture of cryoflte (28) for the electrolytic production of aluminum ... 

Production. Global hydrogen fluoride production capacity in 1992 was estimated to be 875,000 metric tons. An additional 204,000 metric tons was used captively for production of aluminum fluoride. Worldwide capacity is tabulated in Table 5 (38). Pricing for hydrogen fluoride in 1990 was about 1.52/kg (39). 

Anydrous HF for the production of aluminum fluoride. See also Table 6. 

Aluminum Industry. Large amounts of HE are consumed in the production of aluminum fluoride [7784-18-17, AIE, and cryoHte [15096-52-3] (sodium aluminum fluoride), used by the aluminum industry. Both of these compounds are used in the fused alumina bath from which... 

A commercial process which uses hydrothermal leaching on a large scale is the Bayer process for production of aluminum oxide (see Aluminum compounds). This process is used to extract and precipitate high grade alurninum hydroxide (gibbsite [14762-49-3]) from bauxite [1318-16-7] ore. The hydrothermal process step is the extraction step in which concentrated sodium hydroxide is used to form a soluble sodium aluminate complex ... 

Examples of similar processes are the decomposition of precipitated aluminum trHiydroxide to alumina, which is the feed for the electrolytic production of aluminum metal, and the drying of wet sulfide concentrates in preparation for flash roasting (see Aluminumand aluminum alloys). 

Annual production of aluminum nitride is 50—100 t and it is sold for ca 40/kg. Extra high purity, ie, high heat conductive aluminum nitride, is sold... 

Table 10. Annual World Production of Aluminum, Copper, Magnesium, Lead, and Zinc, 10 t/yr ...

Eigure 1 illustrates the Bayer process as it is practiced in the 1990s. The primary purpose of a Bayer plant is to process bauxite to provide pure alumina for the production of aluminum. World production of Al(OH)2 totaled ca 55 x 10 t in 1988. Practically all of the hydroxide was obtained by Bayer processing and 90% of it was calcined to metallurgical grade alumina (AI2O2). However, about 10% of the bauxite processed serves as feedstock to the growing aluminum chemicals industry. 

The chlorination of aluminous materials in the production of aluminum chloride has been thoroughly investigated (2). The Gulf Oil Company produced aluminum chloride from calcined bauxite [1318-16-7] and coke from 1920 to 1960 (3). 

Both the Toth and Alcoa processes provide aluminum chloride for subsequent reduction to aluminum. Pilot-plant tests of these processes have shown difficulties exist in producing aluminum chloride of the purity needed. In the Toth process for the production of aluminum chloride, kaolin [1332-58-7] clay is used as the source of alumina (5). The clay is mixed with sulfur and carbon, and the mixture is ground together, pelletized, and calcined at 700°C. The calcined mixture is chlorinated at 800°C and gaseous aluminum chloride is evolved. The clay used contains considerable amounts of silica, titania, and iron oxides, which chlorinate and must be separated. Silicon tetrachloride and titanium tetrachloride are separated by distillation. Resublimation of aluminum chloride is requited to reduce contamination from iron chloride. 

Approximately 600,000 metric tons of aluminum hydroxides were used in chemical appHcations in the United States in 1988 40% as fillers, 45% for the production of aluminum chemicals, and 15% for various other uses. Carpet backing was the principal filler type appHcation foUowed by polyester products. 

Table 5. Annual U.S. Production of Aluminum Sulfate on a 17.0% AI2OJ Basis in Thousands of Metric Tons ...

Clays are used in a vast number of products. In a few cases, clays are used as a chemical raw material as, for example, for synthetic zeoHte production or for production of aluminum. 

Electrochemical systems convert chemical and electrical energy through charge-transfer reactions. These reactions occur at the interface between two phases. Consequendy, an electrochemical ceU contains multiple phases, and surface phenomena are important. Electrochemical processes are sometimes divided into two categories electrolytic, where energy is supplied to the system, eg, the electrolysis of water and the production of aluminum and galvanic, where electrical energy is obtained from the system, eg, batteries (qv) and fuel cells (qv). 

Hydrogen fluoride Catalyst in some petroleum refining, etching glass, silicate extraction by-product in electrolytic production of aluminum Petroleum, primary metals, aluminum Strong irritant and corrosive action on all body tissue damage to citrus plants, effect on teeth and bones of cattle from eating plants... 

The production of aluminum begins with the mining and beneficiation of bauxite. At the mine (usually of the surface type), bauxite ore is removed to a crusher. The crushed ore is then screened and stockpiled, ready for delivery to an alumina plant. In some cases, ore is upgraded by beneficiation (washing, size classification, and separation of liquids and solids) to remove unwanted materials such as clay and silica. 

Primary smelting and refining of copper 3334 Primary production of aluminum 3339 Primary smelting and refining of nonferrous metals, except copper and aluminum 3341 Secondary smelting and refining of nonferrous metals... 

The annual production of aluminum in the United States in 2000 was 3.6 Mt (1 Mt = 1.0 X 109 kg). What mass of carbon, lost from the anode of the electrolysis cell, was required to produce this amount of aluminum by the Hall process ... 

Hall process (Hall-Herault process) The production of aluminum by the electrolysis of aluminum oxide dissolved in molten cryolite, haloalkane An alkane with a halogen substituent. 

C21-0090. The first commercially successful method for the production of aluminum metal was developed in 1854 by H. Deville. The process relied on earlier work by the Danish scientist H. Oersted, who discovered that aluminum chloride is produced when chlorine gas is passed over hot aluminum oxide. Deville found that aluminum chloride reacts with sodium metal to give aluminum metal. Write balanced equations for these two reactions. 

Certain minerals may be mined and processed for more than one purpose. For instance, bauxite, on the one hand, can be utilized for making bricks or abrasives and, on the other, is used for the production of aluminum. It is often found that many nonmetallic minerals are associated with metalliferous minerals. As an example mention may be made of galena, the main mineral source of lead, which is found very frequently to be associated with fluorite (CaF2) and barytes (BaS04), both of which are important industrial minerals. 

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. 

A consolidated picture of the different processes for the production of aluminum is shown in Figure 6.25. There are altogether four processes (i) Alcan process (ii) Toth process (iii) Alcoa process and (iv) Bayer process. 

The waste materials produced during the primary production of aluminum are fluoride compounds. Fluoride compounds are principally produced during the reduction process. One reason that prebaked anodes are favored is that the closure of the pots during smelting facilitates the capture of fluoride emissions, although many modern smelters use other methods to capture and recycle fluorides and other emissions. 

In the secondary production of aluminum, scrap is usually melted in gas- or oil-fired reverberatory furnaces of 14,000 to over 45,000 kg capacities. The furnaces have one or two charging wells separated from the main bath by a refractory wall that permits only molten metal into the main bath. The principal processing of aluminum-base scrap involves the removal of magnesium by treating the molten bath with chlorine or with various fluxes such as aluminum chloride, aluminum fluoride,... 

A typical plant production of aluminum fluoride indicating water use and wastewater generation is shown in the flow diagram (Figure 22.2). 

Results of waste load found in verification sampling of unit product of aluminum fluoride are given in Table 22.6. 

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