Environmentally friendly approach for sustainable recycling of spent SCR catalysts and Al alloy scrap to prepare TiAl₃ and low-Fe Al alloys

Abstract

A new environmentally friendly (no waste gas, liquid, and slag), efficient (two steps), and low-cost (wastes as raw material) approach is proposed to recycle spent SCR catalysts and Al alloy scrap for preparing TiAl3 and low-Fe Al alloys.

Comprehensive Utilization of Diamond Wire Saw Silicon Powder Waste and Low-Grade Mn Ore to Prepare a MnSi1.73–1.75-Rich Alloy

“…From the bottom to the top of the ingot, the concentration of impurities increases gradually, indicating that most impurities are eliminated through directional solidification. The largest concentrations of Ca and Mg in the ingot (A4 region) are significantly smaller than those in the raw Si–Mn alloy, attributed to their vapor pressures being significantly higher than that of Si . Some of these impurities could be lost by evaporation during the electromagnetic directional solidification process.…”

“…The largest concentrations of Ca and Mg in the ingot (A4 region) are significantly smaller than those in the raw Si− Mn alloy, attributed to their vapor pressures being significantly higher than that of Si. 45 Some of these impurities could be lost by evaporation during the electromagnetic directional solidification process. The segregation coefficient of element i, k i , can be given by the ratio of the molar concentration of i in the solid phase, C i in solid phase , to that in the liquid phase, C i in liquid phase , as expressed by eq 4.…”

Recovery of tungsten from spent selective catalytic reduction catalyst by sulfuric acid precipitation and evaporation crystallization method

“…However, based on some of our early results, when NH 3 .H 2 O was employed as the leaching agent, the leaching efficiency of tungsten was only 60-70% under atmospheric pressure, resulting in the lower recovery efficiency of tungsten in this method. Zhang et al 29 used the process of soda melting and water leaching to convert tungsten into the solution, followed by removing impurities, precipitating tungsten by hydrochloric acid, dissolving in NaOH solution and evaporating to obtain Na 2 WO 4 .2H 2 O. The recovery efficiency of tungsten was 76.8%, while the purity of tungsten product was only 78.8 wt%, which may be due to the tungsten product adsorbing some impurities in the process of Na 2 WO 4 hydrolysis and crystallization.…”