Aluminum refining

Starch monophosphates are quite useful in foods because of their superior freeze—thaw stabiUty. As thickeners in frozen gravy and frozen cream pie preparations, they are preferred to other starches. A pregelatinized starch phosphate has been developed (131) which is dispersible in cold water, for use in instant dessert powders and icings and nonfood uses such as core binders for metal molds, in papermaking to improve fold strength and surface characteristics, as a textile size, in aluminum refining, and as a detergent builder. 

Barium chloride finds use in the production of barium colors, such as the diazo dyes barium hthol ted [50867-36-2] and barium salt of Red Lake C [5160-02-1], a mordant for acid dyes and dying of textiles. Other uses include aluminum refining and boiler water treatment. 

Aluminum refining consumes huge amounts of electricity. Approximately 5% of all electricity consumed in the United States is used to produce aluminum. 

C21-0087. Aluminum refining requires large amounts of electricity. Calculate the masses of A1 and Na that are produced per mole of charge by electrolytic refining of AI2 O3 and NaCl. 

Coke is employed for a number of purposes, but the major use is in the manufacture of carbon electrodes for aluminum refining that requires a high-purity carbon— low in ash and sulfur free. In addition, petroleum coke is employed in the manufacture of carbon brushes, silicon carbide abrasives, and structural carbon (pipes, Rashig rings, and so on), as well as calcium carbide manufacture from which acetylene is produced. 

Most metals can be electrolytically deposited from water-free melts of the corresponding metal salts. It is well known that aluminum, lithium, sodium, magnesium, and potassium are mass produced by electrolytic deposition from melts. Industrial processes for the melt-electrolytic production of beryllium, rare earth metals, titanium, zirconium, and thorium are also already in use. Pertinent publications [74, 137, 163] describe the electrolytic deposition of chromium, silicon, and titanium from melts. Cyanidic melts are used for the deposition of thick layers of platinum group metals. It is with this technique that, for instance, adhesion of platinum layers on titanium materials is obtained. Reports concerning the deposition of electrolytic aluminum layers [17, 71-73, 94, 96, 102, 164, 179] and aluminum refinement from fused salts [161] have been published. For these processes, fused salt... 

The final performance limitation of aluminum alkyl electrolyte systems has not, by far, been reached. Substantially higher deposition rates than those realized today by eletrodeposition technology with organoaluminum electrolytes, i.e., 1-1.5 A/dm, are probably attainable [130]. As a result, the industrial efficiency of both galvanic aluminum deposition and eletrolytic aluminum refinement may be improved. 

Fig. 16. A glass apparatus for aluminum refining from organoaluminum electrolytes [118, 221].

Occupational exposure to inhaled fluoride dusts in cryolite workers during aluminum refining has resulted in severe bone abnormalities, but safety equipment now limits such exposure. No cases of skeletal fluorosis are attributed to use of controlled fluoridation of water supplies. However, skeletal fluorosis may occur in areas of the world where naturally occurring drinking water has high levels of fluoride, such as China and the Indian subcontinent. It is thought that exposure to fluoride intakes of 10 to 25mg/day for 10 years or more may result in skeletal fluorosis, but other nutritional factors may make these populations more susceptible. ... 

Table 6-2 lists the neurological and psychiatric symptoms attributed to aluminum exposure. Most references do not consider aluminum an industrial poison, but chronic inhalation of aluminum dust causes pulmonary irritation leading to lung fibrosis (Shaver s disease) and bronchopneumonia (Katz 1985). An industrial case of pulmonary fibrosis in an aluminum refiner with DD-like symptoms and increased brain aluminum showed the overlap of symptoms between occupational exposures and DD (McLaughlin et al. 1962). Aluminum poisoning from the natural environment is one of several proposed causes of parkinsonism-... 

Aluminum metal (CAS 7429-90-5) Dusts can cause mild eye and respiratory tract irritation, Long-term inhalation of large amounts of fine aluminum powders or fumes from aluminum ore (bauxite) has been associated with reports of pulmonary fibrosis (Shaver s disease). Acute exposures in aluminum refining ("pot room") has been associated with asthma-like responses, Industrial processes used to produce aluminum have been associated with an Increased incidence of cancer in workers, 10 mg/m (metal and oxide) 5 mg/m (pyrophoric powders, welding fumes) 2 mg/m (soluble salts, alkyls NOC) 0 3 1 (powder) Oxidizes readily. Fine powders and flakes are flammable and explosive when mixed with air. Reacts with acids and caustic solutions to produce flammable hydrogen gas. 

Hydrofluoric acid Lithium carbonate Sodium carbonate aluminum refining Barium... 

Cryolite melts (NasAlFe, mp 1273 K), which are of considerable importance in aluminum refining studies, need to be purified from refractory oxides (silica, alumina, etc.) and iron, among others. Preelectrolysis at 1.6 V using a molten silver cathode in a graphite or molybdenum crucible is recom-mended. " "" ... 

Aluminum refining uses two major energy-intensive processes ... 

Table 1 lists several electrochemical processes and their reactions, feeds, and products. The chlor-aUcali process consumes approximately 2 % of the electricity generated in the USA. The process involves electrolysis of a brine solution to produce CI2 at the anode and NaOH at the cathode. In the Hall process for aluminum refining, AI2O2 reacts with a carbon electrode to form A1 and CO2. Water electrolysis is a widespread technology for generating pure H2 and O2. While reforming of methane or other... 

In addition to fluoridated water, some other sources of significant amounts of fluoride are (1) the environments around aluminum refining plants and (2) the consumption of tea, crude sea salt, bone meal, or fish (particularly, fish bones). However, the effects of excess fluoride may be reduced somewhat by diets rich in calcium and magnesium. 

Uses Alloys in vacuum tubes deoxidizer for copper lubricant for anode rotors in x-ray tubes spark-plug alloys in nuclear readors electronic tubes additive in lubricating oils mfg. of pyrotechnics and explosives tanning and finishing leather mordant for fabrics and dyes eledroplating aluminum refining rubber mfg. prod, of paints and enamels Regulatory Canada DSL... 

In other primary metal industries such as aluminum, the refractory properties requirements are quite different than steel making. Although the temperature of aluminum refining and alloying process is much lower than steel, it has the unique problem of penetration in the refractories. Hence, the refractory should be designed so that it has a nonwetting characteristic to molten aluminum. The non wetting properties are introduced in the refractories by special additives. 

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