Aluminothermic reduction of Cr2O3 contained in the ash of thermally treated leather waste

Abstract

-In this study the viability of utilising ashes with high chromium oxide content, obtained by thermal treatment of footwear leather waste, in the production of low-carbon ferrochromium alloy (Fe-Cr-LC) by aluminothermic reduction was investigated. The following key-factors were selected for process modelling: the quantity of aluminium (Al) employed in the reaction, the iron amount added, the iron compound (Fe and/or Fe 2 O 3 ) used, and the chromic acid addition. The process was investigated using a 2 4 full factorial design where the percentage of Cr 2 O 3 reduced was used as the response. Variance analysis was employed to determine the significant effects and to validate the obtained model. The model was useful for finding the optimal operating conditions, including the maximisation of chromium conversion and the gross margin. Both resulted in similar process conditions, with 76.8±12.3% of chromium being reduced to the metallic phase, and 1.65±0.52 USD (kg ash) -1 as the gross margin. The qualities of some alloys obtained were investigated by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy analysis (SEM/EDS). The results showed that the main problem for these alloys in a standard specification was the P and S content, suggesting that a pre-treatment is required.

A Decarbonization Approach for FeCr Production

“…The results of this study showed that the Cr content was slightly below standards and the Ti, P, and S content levels were high. Therefore, it has been reported that more pre-treatment is required to remove the impurities from the ash [ 18 ].…”

Chemical and Structural Analysis of Newly Prepared Co-W-Al Alloy by Aluminothermic Reaction

“…By using this mixture, temperatures of up to 2500 • C can be achieved [10]. The aluminothermic reactions of various metal oxides (such as TiO 2 [11][12][13][14], SiO 2 [15][16][17][18], ZnO [19][20][21][22][23][24], Cr 2 O 3 [25][26][27], CuO [28][29][30]) have been studied for many years. The aluminothermic reaction is useful in the production of metals and alloys, such as refractory ceramics, composite materials, nanowires and nanocoatings, ceramic coatings for metallic pipes, and railway welding [7,29,31,32].…”

Effects of added aluminum chromium slag on the structure and mechanical properties of colored zirconia ceramics

“…Aluminum chromium slag is a byproduct produced during the production of metallic chromium by aluminothermic reduction 22,23 . The chemical reaction equation is as follows 24 :…”