Study on dealkalization and settling performance of red mud

Abstract

At present, the dealkalization and comprehensive utilization of red mud is a worldwide problem. Studies on the settling performance and phase transformation of red mud by HCl, CaO, and HO leaching are limited. In this study, the characteristics of red mud were systematically analyzed. The average sizes of graded and initial red mud were 4.11 and 9.20 μm, respectively. X-ray diffraction (XRD), X-ray fluorescence spectra (XRF), and thermogravimetry-differential scanning calorimetry (TG-DSC) results indicated the different mineralogical phases, composition, and thermal behavior. The addition of HCl could neutralize the alkalization in the red mud slurry, and CaO could replace the Na and K. Notably, the pH of the red mud slurry had no obvious change with the increase in water washing times in a certain pH. Interestingly, soluble Al and Fe were not detected in the HCl-red mud and CaO-red mud. In addition, the settling ratio was used to express the settling performance of the red mud slurry. Their interaction mechanisms were proposed, which may include phase transformation and the changing of the size and surface area. The research provided a better understanding of the phase transformation and settling performance in the treatment of red mud by HCl, CaO, and HO leaching.

Reductive Smelting of Neutralized Red Mud for Iron Recovery and Produced Pig Iron for Heat-Resistant Castings

“…Despite this fact, most studies are devoted to the pyrometallurgical processing of the initial RM [10][11][12], because the alkali present in RM significantly reduces its melting point and improves the separation of slag and metal [13,14]. However, from our point of view, it would be more practical to regenerate the alkali for recirculation by autoclave leaching of bauxite [15,16], since during the smelting of red mud with high sodium content, the alkali goes into the gas phase, and its further regeneration is very difficult [17].…”

Experimental Research on the Bearing Properties of Red Mud Geopolymer Foundations

“…Red mud is an insoluble industrial solid waste from aluminum production plants (Luo et al, 2017). It is estimated that the total stockpile of red mud across the world is more than 3 billion tons and about 120 million tons of red mud are produced around the world per year, the comprehensive utilization of red mud is a worldwide problem (Bai et al, 2017a;Zhu et al, 2017).…”

Study the Recycling of Red Mud in Iron Ore Sintering Process

“…Red mud (RM) is the tailing produced during the extraction of alumina from bauxite ore using the Bayers process. In this process, bauxite ore is digested with sodium hydroxide to produce alumina which leads to the formation of huge amounts of tailing assigned as red mud [11][12][13][14][15][16][17][18][19][20][21][22][23][24]. In total global red mud production in 2019 was approximately 4 billion tones [21,31,34].…”

“…The collapse of a red mud reservoir in 2010 in western Hungary, resulted in the release of approximately one million cubic meters of red mud (with a pH of approximately 12), resulting in the deaths of ten people, while 150 were infected by various diseases [34]. The red mud produced from the treatment of various bauxite ore usually contains a high percentage of iron, aluminum, and titanium in oxide forms with the presence of some rare earth elements like scandium and vanadium [28] Thus, the comprehensive utilization of this red mud via its recycling in different applications has received a lot of attention [10,14,17].…”