AA-TRBR-2000.pdf
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1、STD*AA TRBR-ENGL 2000 Ob04500 0037048 7T9 Copyright The Aluminum Association Inc. Provided by IHS under license with AA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 04/18/2007 10:56:28 MDTNo reproduction or networking permitted without license from IHS -,-,- “The coastal plai
2、n of Perth, Western Australia was once pari of the Indian Ocean floor, and is characterized by poor sandy soils and limestone outcrops. The soils drain freely, allowing fertil- izers to leach into waterways where they boost nutrient levels and can lead to problems such as algal blooms. The applicati
3、on of bauxite residue to these sandy soils will aid the retention of phosphates and moisture as well as reducing the need to apply lime for soil pH adjustment. In areas where bauxite residue has been applied there has been a significant increase in crop yield and a significant reduction in the level
4、 of phosphorus being leached into local waterways.” Copyright The Aluminum Association Inc. Provided by IHS under license with AA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 04/18/2007 10:56:28 MDTNo reproduction or networking permitted without license from IHS -,-,- Technol
5、ogy Roadmap for Bauxite Residue Treatment and Utilization February 2000 Summary o f workrshop prepared by Energetics, Inc. sponsored by The Aluminum Association Washington DC www .aluminum.org Copyright The Aluminum Association Inc. Provided by IHS under license with AA Licensee=IHS Employees/111111
6、1001, User=Wing, Bernie Not for Resale, 04/18/2007 10:56:28 MDTNo reproduction or networking permitted without license from IHS -,-,- STD-AA TRBR-ENGL 2UOO I I ObOq500 0017051 i73 R Table of Contents . Executive Summary . 111 1 . 2 . 3 . 4 . 5 . Introduction . 1 Issues 3 Approaches 5 Research Needs
7、11 Next Steps 15 A . Workshop Participants 17 References . 19 Bauxite Residue Technology Roadmap 1 February 2000 Copyright The Aluminum Association Inc. Provided by IHS under license with AA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 04/18/2007 10:56:28 MDTNo reproduction o
8、r networking permitted without license from IHS -,-,- STDIAA TRBR-ENGL 2000 I Ob04500 0017052 3ZT Executive Summary The treatment and use of bauxite residue (sometimes known a s red mud) was the focus of a recent meeting sponsored by the Aluminum Association. Representatives from Alcoa, Alcan, and K
9、 a i s e r were joined by several outside technical experts (Appendix A) to discuss various approaches and set priorities for possible collaborative research efforts. The group assigned the highest priority to the following approaches for residue treatment: o metal recovery from residue o removal of
10、 desilication product (DSP) before it becomes residue beneficiation of bauxite o consolidation O use for removing SO, and CO, from gaseous streams use for levee construction, including both dikes in disposal areas and road bases The key technical, economic, environmental, and market factors influenc
11、ing the success of each approach were determined. Research needs for the approaches listed above were identified and discussed and priorities assigned. The group indicated that a top priority in metal recuvev is a joint brainstorming effort between the aluminum industry and outside experts, perhaps
12、part of a collaborative development effort with other metal producers. A key research need under removal of DSP is the development of a cost-effective means of recovering soda from DSP product. In the area of bauxite beneficiatiun, the focus should be on the development of new separation technology.
13、 Aluminum companies have joined together to work cooperatively on the common problem of treating bauxite residue. The next step in this process is to identify specific pre-competitive research activities for the highest-priority needs based on the output of the workshop. Aluminum companies with a po
14、tential stake in the outcome should collaborate to jointly seek govemment funds or fund university research. By leveraging their resources and knowledge, the companies will be able to develop economical solutions faster than they could acting independently. . February 2000 Bauxite Residue Technology
15、 Roadmap 1 1 1 Previous page is blank Copyright The Aluminum Association Inc. Provided by IHS under license with AA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 04/18/2007 10:56:28 MDTNo reproduction or networking permitted without license from IHS -,-,- 1 Introduction For de
16、cades, the aluminum industry has been investigating options for treating, disposing, and using bauxite residue (or red mud), a byproduct of the Bayer process to extract aluminum oxide fi-om bauxite ore. This report examines the issues surrounding bauxite residue, discusses different approaches for t
17、reatment/disposal/utilization, and identifies research and development needs for some of the most promising options. Alumina Production and Bauxite Residue The starting material for electrolytic smelting of aluminum is pure, anhydrous aluminum oxide (A1203), also known as alumina. The principal ore
18、from which aluminum is extracted is called bauxite. The principal ingredients contained in the bauxite are hydrated aluminum oxide, iron oxide (which gives it its reddish-brown color), silicates (e.g., clay, quartz), and titanium dioxide. The Bayer process is used to produce alumina from bauxite. Be
19、cause of variability in ores, each alumina plant is almost tailored to suit a particular bauxite. III the Bayer process, the bauxite is crushed and ground, then mixed with a solution of caustic soda and pumped into large autoclaves. There, under pressure and at a temperature of 110C to 27OoC, the al
20、umina contained in the ore is dissolved to form sodium aluminate. The silica in the bauxite reacts and precipitates fiom solution as sodium-aluminum-silicate. The remaining residues consist partly of minerals that do not dissolve during the caustic treatment of the bauxite (e.g., iron and titanium o
21、xide), calcium carbonate and calcium aluminates from lime addition, and also of what is known as the dedication product (DSP), which contains not only silica but considerable quantities of unrecoverable alumina and soda. Some bauxite residues contain as much as 24% Tio, 43% Alio3, and 54% Fe,O, depe
22、nding on the mineralogical make-up of the bauxite. The residue also contains trace amounts of the metals niobium, gallium, zirconium, thorium, scandium, and vanadium. The residue settles out of solution and is separated from the sodium aluminate solution, washed to recover the caustic soda, and pump
23、ed to disposal areas. The worldwide alumina industry produces over 70 million dry metric tons of bauxite residue annually. Australia is the largest alumina refiner in the world, processing around 30% of the total alumina (see text box next page). The production of one ton of aluminum metal yields 1.
24、5 to 4 tons of bauxite residue (on a dry basis) to be disposed. The worldwide average of residue in disposal sites is 50% solids in the residue. Bauxite Residue Technology Roadmap 1 Februas, 2000 Copyright The Aluminum Association Inc. Provided by IHS under license with AA Licensee=IHS Employees/111
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