Alumina & Bauxite: Non-traditional Resources
Sponsored by: TMS Light Metals Division, TMS: Aluminum Committee
Program Organizers: Zhang Ting'an, Northeastern University
Wednesday 8:30 AM
March 1, 2017
Location: San Diego Convention Ctr
Session Chair: Guozhi Lv, Northeastern University; Lesley Ironside, WorleyParsons
8:30 AM Introductory Comments
New Process Research on Aluminium Production from Non-traditional Aluminum Resource by Microwave Chlorination: Zhang Ting'an1; Guozhi Lv1; Long Wang1; Zhihe Dou1; Weiguang Zhang1; Yukun Huang1; Yanxiu Wang1; 1Northeastern University
A novel method was developed to prepare aluminium via fluidizing chlorination with untraditional aluminum resources as raw materials. The main steps in this method were: alumina transformed into aluminium chloride through fluidizing chlorination; aluminium chloride reacted with NaOH solution for aluminium hydroxide and NaCl; NaOH and Cl2 were recycled from NaCl solution by electrolytic process. The new process for preparing aluminium resources by fluidizing chlorination method was proposed to realize efficient separation of the valuable components in non-traditional aluminum resources such as fly ash or low grade bauxite, silicon in untraditional aluminum changed into SiCl4 in fluidizing chlorination which could be used as raw materials for high purity Si products. Furthermore, the tailings emission of this process was quite lower than that of Bayer process. This paper mainly introduce the principle of this new process, the thermodynamics of fluidizing chlorination is analysis as well.
Chemical Alumina Preparation by Using High Alumina Content Fly Ash: Guozhi Lv1; Zhang Ting'an1; Weiguang Zhang1; Xiaofeng Zhu1; Yan Liu1; Long Wang1; Zhihe Dou1; Qiuyue Zhao1; 1Northeastern University
Processes of chemical alumina preparation of high alumina content fly ash raw materials were put forward in order to solve the problems of bauxite resource shortage in China and high value application of fly ash. High white aluminum hydroxide and Pseudoboehmite can be obtained by sintering process with the precipitation and carbonate decomposition, 4A zeolite was prepared through the pre-roasting and synthesis process, and activated aluminium oxide was prepared through the acid leaching and pyrolysis method. Typical experiments for preparing different kind of chemical alumina products were presented as well. Whiteness, porosity, pore volume, crystalline and other key parameters of chemical alumina products determined by XRD and ASAP match the industry requirements well.
Iron Separation from Bauxite through Smelting-reduction Process: Hanne Sellæg1; Leiv Kolbeinsen1; Jafar Safarian1; 1NTNU
In the alumina production process through the dominant commercial Bayer process red mud by-product, which is not consumable and causes serious environmental challenges is produced. Alternative sustainable process for alumina extraction from bauxite is Pedersen process, which was patented in 1920s and was in operation in Norway for many years before closing down due to economic reasons. In this process bauxite is smelted and reduced, which yields pig iron and a calcium aluminate slag. Alumina is further produced from the slag through a hydrometallurgical process. In the present study, different bauxites with different chemical compositions are smelted with lime and reduced by coke. The smelting reduction is studied through chemical, microstructural and phase analysis. It is shown that complete separation of iron from the slag is possible and in addition the process is effective for partial separation of the other impurities such as Ti, Si, V,… from the Al2O3-containing slag.
9:50 AM Break
Thermodynamic Behavior of Lime Desulfurization in Sodium Aluminate Solution: Wu Xianxi1; Zhu Weidong1; Jiang Hongshi1; Wu Song1; 1Guizhou University
The method of GoR,Ca4Al2SO10·12H2O=∑Gooxide+∑GoR was used to estimate the Gibbs free energy of calcium hydroaluminosulfate (3CaO·Al2O3·3CaSO4·nH2O, 3CaO·Al2O3·CaSO4·12H2O) and Ca3Al2(OH)12, then to calculate the Gibbs free energies of desulfurization reaction that lime interacts with sodium sulfate in sodium aluminate solution. To make judgments about reaction direction, the correctness of calculation was validated by experiments. Thermodynamic calculation and XRD phase identification indicate that 3CaO·Al2O3·3CaSO4·nH2O and 3CaO·Al2O3·CaSO4·12H2O can be generated in the procces of desulfurization. With the reaction time to extend the calcium hydroaluminosulfate decomposition, the 3CaO·Al2O3·3CaSO4· nH2O has been characterized. The thermodynamic behavior of adding lime to desulfurization in the sodium aluminate solution was discussed.
A Novel Process of Alumina Production from Low-grade Bauxite Containing Sulfur: Bo Wang1; Kai Zhao1; Huilan Sun1; Xuezheng Zhang1; Zepeng Li1; Hongyou Ma1; 1Hebei University of Science and Technology
Soda-lime sintering process and lime sintering process are the research focus on utilization of low-grade alumina recently. The latter process can realize dry-sintering process and its energy consumption is relatively lower. However, its sintering temperature is up to 1350°C, which is unfavorable to industrial production. Based on lime sintering method, a novel process of alumina production from low-grade bauxite containing sulfur or fly ash is carried out in this paper. The phase of alumina transforms from 12CaO•7Al2O3 (C12A7) to 4CaO•3Al2O3•SO3 (C4A3S), whose alumina leaching property is better, through decreasing sinter temperature and time and adjusting the content of CaSO4 in this process. The main phases of the clinker sintered at 1250°C are C4A3S and silicon dioxide. Its leaching ratio reaches 89% after 10min reaction, and the conditions of leaching temperature and sodium carbonate’s concentration are lower than that of C12A7.