Aluminum recovery

Another method of secondary aluminum recovery uses aluminum drosses as the charge instead of scrap. Traditionally, the term dross was defined as a thick liquid or solid phase that... 

Adequate digestion methods are important in the determination of all metals, including aluminum. Que Hee and Boyle (1988) showed that Parr bomb digestions were always superior to hot plate digestions for many elements, including aluminum, in feces, liver, and testes. Microwaving in closed vessels produced lower aluminum recoveries in liver than Parr bomb digestions. The Parr bomb values for citrus leaves were within 5% of the NBS certified values. 

Petruzzelli, D., et al. (1998). Aluminum recovery from water clarifier sludges by ion exchange. Reactive Functional Polymers. 38, 2-3, 227-236. 

FIGURE 34.10 Aluminum recovery from the AWTP residuals during the DMP decrease in Al concentration in feed, percentage recovery, and increase in Al concentration in recovery solution. 

FIGURE 34.13 Aluminum recovery in two consecutive runs with WTR obtained from the AWTP. 

For Nafion 117, the aluminum recovery profile approached saturation after 12 h but the same was linear after 24 h for lonac 3470. 

Increasing the initial H2SO4 concentration, Cq, from 1 M to 2 M increased aluminum recovery uptake for both membranes but there was a drop in aluminum concentration at the end for Nafion 117. This observation of drop in aluminum concentration beyond saturation is counterintuitive and was reconfirmed through a replicate experiment. 

Characteristically, the aluminum recovery plot for Nafion 117 could be identified as a combination of three zones Zone A (where the plot is linear). Zone B (where the plot reaches a plateau), and Zone C (where it tapers downward). The following provides a scientific explanation leading to the existence of the three zones. 

The material losses of alternate RDF processing plants depend mainly on the sophistication and plant. This should depend upon economics if it is economically justified to recover more combustibles, it should be done. There is a limit to the investment and operating costs which can be justified to recover the last Calorie. The same applies to recovering aluminum and glass. At this date fuel energy is the valuable product ferrous metals have low economic value, aluminum recovery... 

Continued growth in the production of aluminum is unlikely to be hampered by a shortage of mineral since the earth s crust consists of about 8% aluminum, chiefly as aluminosilicates. Even though aluminum is the most abundant metallic crustal element, bauxite ores suitable for aluminum recovery only occur in more limited areas where natural leaching processes have concentrated the aluminum-containing minerals. Since the free metal is chemically reactive it is never found in nature in this form. 

In this procedure, extensively tested by Alcan at one time, dissolution of aluminum from the alloy using aluminum trichloride at about 1,300°C produces the volatile aluminum subhalide [19]. Cooling the subhalide moderately returns a pool of molten product aluminum, and aluminum trichloride (boiling point approximately 183°C), which serves as a working fluid and can be recycled. Despite problems with the aluminum recovery methods there remains an interest in nonelectrolytic aluminum production, such as that offered by carbothermic processes [20]. 

One of the most important technological parameters in molten salt chemistry is surface tension, as the majority of important reactions take place at the interface of electrolytes or molten reacting media. In aluminum electrolysis, for instance, this parameter influences the penetration of the electrolyte into the carbon lining, the separation of carbon particles from the electrolyte, the coalescence of aluminum droplets and fog in the electrolyte, the dissolution rate of aluminum oxide in the electrolyte, etc. Similar is the effect of interface in aluminum recovery. 

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. 

Iron [7439-89-6J, Fe, from the Latin ferrum, atomic number 26, is the fourth most abundant element in the earth s cmst, outranked only by aluminum, sihcon, and oxygen. It is the world s least expensive and most useful metal. Although gold, silver, copper, brass, and bron2e were in common use before iron, it was not until humans discovered how to extract iron from its ores that civilization developed rapidly (see Mineral processing and recovery). 

Other recovery methods have been used (10). These include leaching ores and concentrates using sodium sulfide [1313-82-2] and sodium hydroxide [1310-73-2] and subsequentiy precipitating with aluminum [7429-90-3], or by electrolysis (11). In another process, the mercury in the ore is dissolved by a sodium hypochlorite [7681-52-9] solution, the mercury-laden solution is then passed through activated carbon [7440-44-0] to absorb the mercury, and the activated carbon heated to produce mercury metal. Mercury can be extracted from cinnabar by electrooxidation (12,13). 

Precipitation. The precipitation of aluminum tribydroxide ia the recovery step of the Bayer process is achieved either by loweting the temperature or by diluting the pregnant Hquor and reduciag its pH. Both methods reverse the direction of equation 35, but seeding with previously precipitated crystals is required ia order to initiate nucleation. 

A conservative estimate of the total value of the products from the mineral industry is ca 3.9 trillion ia terms of 1992 dollars (4). This estimate does not include the value of products derived from secondary sources such as recycling (qv) or reclamation. Secondary recovery is significant for certain commodities. For example, in 1992 ca 30% of the world steel (qv) production, 46% of the world refined lead output, 15% of the world refined copper (qv) production, and ca 30% of the aluminum (see Aluminumand ALUMINUM alloys) output from the Western world were clearly identified as being derived from scrap. The value of the world mineral commodity export trade in 1992 was ca 616,698 million ia 1992 dollars. This accounted for ca 18% of all commodities exported (4). 

Phosgene can be employed in a variety of metal-recovery operations, eg, in the recovery of platinum, uranium, plutonium, and niobium (69—73). Phosgene has been proposed for the manufacture of aluminum chloride, beryllium chloride, and boron trichloride (74—76). Phosgene has been patented as a stabilizer, either by itself or in combination with thionyl chloride, for Hquid SO2 (77). 

One appHcation patented ia 1989 is the injection of sodium alumiaate into silica-containing formations for enhanced petroleum recovery (39). Additionally, the pharmaceutical industry uses sodium alumiaate as an alkaline source of aluminum for the production of certain antacids (40). 

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