Secondary Aluminum Production Waste — A Raw Material for the Refractory Industry

Abstract

Secondary aluminum waste products, and processes that occur during heating and mineral formation on introducing fine periclase powder into the composition of waste products are studied. It is demonstrated that secondary aluminum production waste may be used as a raw material for synthesizing aluminomagnesia spinels.Currently in many countries there is research into the use of technogenic waste products and comprehensive processing of raw materials. This tendency is due to the exhaustion of natural resources and the worsening ecological situation in industrial regions. From this point of view there is specific interest in slags of the metallurgical industry [1 -3], in particular secondary aluminum production waste (SAPW) that with respect to Al 2 O 3 content is a potential raw material for the refractory industry. The chemical composition of waste materials is presented in Table 1.The mineral composition of SAPW has been determined by petrographic and x-ray phase analyses. Within it there are KCl, NaCl, g-Al 2 O 3 , a-Al 2 O 3 , MgO·Al 2 O 3 , aluminum metal, quartz, aluminosilicates of variable composition, and periclase.The content of up to 20% of alkali metal compounds (see Table 1) makes these waste materials unsuitable for utilization in production, and therefore it would be necessary to establish the possibility and degree of removal of these alkali metal compounds. For this it is possible to use hydrometallurgical or pyrometallurgical methods. In choosing a method for removing alkali metal compounds a rough estimation of their residual content has been made: it should not exceed 1% in treated material. It has been established that it is impossible to reduce by the hydrometallurgical method the content of chloride-ions to less than 0.5%, and for alkali oxides to less than 3%. This content of alkali oxides is unsuitable for preparing refractories.Results of thermogravimetric analysis of SAPW dust in an argon atmosphere and in air are shown in Figs. 1a, b. Three sections of the specimens weight loss are observed. The first section in the range 40 -560°C is connected with

Recycling of Secondary Aluminium Production Waste in Processing of Mullite Based Refractory Ceramics

“…Predictable high alumina contents of SAPW makes them very attractive for recycling processes, such as the recovery of aluminium-based compounds [1]. Aluminosilicate-based ceramics such as mullite (3Al 2 O 3 · 2SiO 2 ) have attracted much attention as a high-temperature structural ceramic, due to their good physical properties, such as low dielectric constant, low thermal expansion, high melting point, high resistance to creep, high temperature mechanical stability and resistance to chemical corrosion [2,3].…”