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

Abstract

The chemical and mineral composition of the red mud from the Ural Aluminum Plant were studied by XRF, XRD, and Mössbauer spectroscopy. Experiments on reductive smelting of red mud were carried out in a range of temperatures (1650–1750 °C) to recover iron from the aluminum production waste with maximum efficiency. It was found that it is possible to obtain pig iron with a high content of titanium, phosphorus, and vanadium, and low sulfur content. The efficiency of iron recovery at 1750 °C was found to be around 98%. Thermodynamic calculations were carried out to assist in finding the optimal conditions for the process (e.g., carbon content, furnace temperature, slag liquidus temperature). It was also found that the pig iron phase obtained at 1650 to 1700 °C is not separated from the slag phase into ingot compared with the sample obtained at 1750 °C. Pig iron obtained at 1750 °C can be used to produce molds for the steel-casting equipment.

Influence of Sodium Sulfate Addition on Iron Grain Growth during Carbothermic Roasting of Red Mud Samples with Different Basicity

“…Six sextets for the sample U include of four subspectra that are analogous to those for the sample B and two additional 2. The detailed description of the spectra for the sample U is presented in [67]. The subspectra parameters of the sample B is similar to those of the sample U.…”

New glass‐based binders from engineered mixtures of inorganic waste

“…However, some “tuning” possibilities are applicable in both technologies. While in conventional vitrification compositional variations of the constituents may be compensated by adjusting the proportion between them, in EAF processing, the production of pig iron by carbothermal reduction is accompanied by the conditioning of slag properties through the addition of fluxes such as lime, quartz, or even other mineral wastes 17–19,36–38 . Other types of inorganic waste (i.e., fly ash) might be co‐reduced alongside red mud.…”

“…In the second vitrification approach, a glass was obtained through an “integrated process,” consisting of the electric arc furnace (EAF) treatment of a red mud‐richer mixture, undergoing carbothermal reduction, 17–19 and yielding a glassy slag as a by‐product of iron alloy extraction. As pointed out by Gomez et al, 11,20 a modern vitrification process is not encouraged commercially only by the transformation of waste‐derived glass; extra revenues may be derived from the extraction of combustible gas and/or metals from the same thermal waste treatment.…”

“…As pointed out by Gomez et al, 11,20 a modern vitrification process is not encouraged commercially only by the transformation of waste‐derived glass; extra revenues may be derived from the extraction of combustible gas and/or metals from the same thermal waste treatment. Such operations represent an extension of traditional pyrometallurgical processes, often termed as “smelting,” typically enabling the obtainment of a metallic liquid accompanied by a nonmetallic “slag” (generally floating on the metallic bath), separated in form of amorphous or semicrystalline material, depending on the fluxing and cooling conditions 18 . In the present case, the mixing of red mud with CaO had an interesting synergistic effect, enabling both a substantial metal recovery and the development of a stable gel by direct activation with pure water.…”

Advances in Understanding of the Application of Unit Operations in Metallurgy of Rare Earth Elements

“…Elements such as Ce and Y present in AMD precipitates under the effect of RM enriching the mineral phase. Several authors had explored a pyrometallurgical treatment of BR to recover pig iron and enhance the content of critical raw material (CRM) in the final slag [100][101][102]. This approach can be beneficial to increase both pig iron and CRM from the filter cakes produce after coagulating AMD ions into an BR matrix.…”