Search

As a refractory industrial solid waste, high-alumina fly ash is discharged into nature in large quantities, causing serious environmental harm. The extraction of valuable components, such as aluminum, from high-alumina fly ash has become a research hotspot at home and abroad. The shortcomings of traditional alumina extraction from high-alumina fly ash include long technological processes, large amounts of waste acid and alkali, and serious equipment corrosion. A novel method for alumina preparation by electrotransformation AlCl3 solution(EAS) under NH4Cl catalysis with injected CO2 has been proposed by Northeastern University. The process has advantages, such as short flow and no waste acid discharge. In this study, the influence of initial NH4Cl concentration in the cathodic chamber on solution pH, phase and morphology of electrotransformation products, phase, D(50) and D(90) of roasting products, and Al recovery rate were examined. Simultaneously, EAS was examined and compared with and without injected CO2, as well as EAS under NH4Cl catalysis with and without injected CO2. The results showed that, when the solution in the cathodic chamber was NH4Cl with CO2 injection, with electrotransformation time extension, pH increased slowly and the morphology of electrotransformation products were all rough and fluffy block structures. Increasing initial NH4Cl concentration effectively improved the product crystallization states, roasting products D(50) and D(90), and Al recovery rate.

Copyright of Journal of Mining & Metallurgy. Section B: Metallurgy is the property of Journal of Mining & Metallurgy and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The present study attempts to prepare Al-substituted α-Ni(OH)2 and Al-substituted α-Ni(OH)2 with modified interlayer anions by directly immersing pure α-Ni(OH)2 into AlCl3-containing solutions. XRD and FT-IR analysis demonstrated Al-substituted α-Ni(OH)2 can be prepared directly by soaking pure α-Ni(OH)2 into AlCl3 solution. Al-substituted α-Ni(OH)2 with S2O32− as the primary anion in the interlayer can be obtained by immersing pure α-Ni(OH)2 into AlCl3-Na2S2O3 solution. The analysis of Al content in samples demonstrated the Al content in the Al-substituted α-Ni(OH)2 was regulated by adjusting the molar ratio of pure α-Ni(OH)2 soaked in the solution and Al3+ dissolved in the solution. The Al element entered the lattice of pure α-Ni(OH)2 through a process of pure α-Ni(OH)2 dissolved followed by the precipitation of Al3+, Ni2+ and OH−. The S2O32− entered the interlayer of Al-substituted α-Ni(OH)2 through the formation process of the Al-substituted α-Ni(OH)2 or though ion exchange with the intercalated Cl−. The strongly alkaline solution soaking results demonstrated that Al-substituted α-Ni(OH)2 prepared by soaking pure α-Ni(OH)2 into AlCl3-containing solutions could preliminary get stabilized in the strongly alkaline solution.

With rapid economic development, a bauxite shortage has seriously restricted China's aluminum industrial development. As a potential alumina secondary resource, high-alumina fly ash has alumina content comparable to China's low-medium grade bauxite. Traditional alumina extraction processes have many problems, such as high-energy consumption, large amounts of waste acid and alkali, serious secondary pollution, and large amounts of slag discharge. In view of this situation, Northeastern University has proposed a new method for electrolyzing AlCl3 solutions to prepare alumina under ammonium chloride (NH4Cl) catalysis. This method has the advantages of catalyst recycling and no waste acid. In this study, the effects of initial NH4Cl concentration and stirring on the cathodic chamber pH and voltage were examined during electrolyzing AlCl3 solution under NH4Cl catalysis process. In addition, the phase, morphology, D(50) and D(90) of the products, the phase and morphology of subsequent roasted products, and Al recovery rate during electrolyzing AlCl3 solution under NH4Cl catalysis process were investigated. The results suggested that, with lower initial NH4Cl concentration, solution pH and voltage increased, while stirring can slow down the increasing trend of solution pH and voltage. The initial NH4Cl concentration and stirring were observed to have great influence on the product phase and the electrolytic products were all Al(OH)3. Stirring made products take on block and ball shapes. The initial concentration and stirring had no clear influence on product D(50) and D(90) nor the phase and morphology of the roasted products. The roasted products were all bulk amorphous alumina. Increasing initial NH4Cl concentrations and stirring can increase Al recovery rate. Without stirring and increased NH4Cl initial concentration, Al recovery rates increased from 10.2 to 21.2%, while with stirring and increased NH4Cl initial concentration, Al recovery rates increased from 19.5 to 21.8%. [ABSTRACT FROM AUTHOR]

• Al-substituted α-Ni(OH) 2 was prepared by immersing pure α-Ni(OH) 2 into AlCl 3 -containing solution. • Al atom and S 2 O 3 2- were incorporated in the lattice of α-Ni(OH) 2 by immersing pure α-Ni(OH) 2 into AlCl 3 -Na 2 S 2 O 3 solution. • Al-substituted α-Ni(OH) 2 prepared by soaking pure α-Ni(OH) 2 into AlCl 3 -containing solutions can get a preliminary stability in the strong alkali. The present study attempts to prepare Al-substituted α-Ni(OH) 2 and Al-substituted α-Ni(OH) 2 with modified interlayer anions by directly immersing pure α-Ni(OH) 2 into AlCl 3 -containing solutions. XRD and FT-IR analysis demonstrated Al-substituted α-Ni(OH) 2 can be prepared directly by soaking pure α-Ni(OH) 2 into AlCl 3 solution. Al-substituted α-Ni(OH) 2 with S 2 O 3 2− as the primary anion in the interlayer can be obtained by immersing pure α-Ni(OH) 2 into AlCl 3 -Na 2 S 2 O 3 solution. The analysis of Al content in samples demonstrated the Al content in the Al-substituted α-Ni(OH) 2 was regulated by adjusting the molar ratio of pure α-Ni(OH) 2 soaked in the solution and Al3+ dissolved in the solution. The Al element entered the lattice of pure α-Ni(OH) 2 through a process of pure α-Ni(OH) 2 dissolved followed by the precipitation of Al3+, Ni2+ and OH−. The S 2 O 3 2− entered the interlayer of Al-substituted α-Ni(OH) 2 through the formation process of the Al-substituted α-Ni(OH) 2 or though ion exchange with the intercalated Cl−. The strongly alkaline solution soaking results demonstrated that Al-substituted α-Ni(OH) 2 prepared by soaking pure α-Ni(OH) 2 into AlCl 3 -containing solutions could preliminary get stabilized in the strongly alkaline solution. [ABSTRACT FROM AUTHOR]