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

Dmitry Valeev,Dmitry Lubyanoi,Dmitry Zinoveev,Alex Kondratiev,Denis Pankratov

doi:10.3390/met10010032

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.

Highlights

The accumulation and storage of the alumina production waste, red mud (RM), represents one of the most critical ecological problems for the aluminum industry
Sodium was removed from RM on the plant by leaching with a lime slurry at 90 ◦ C for a duration of 3 h [30], which can be described by the following equation [31,32]: Na8 Al6 (SiO4 )3 (OH)14 ·nH2 O(s) + 9Ca(OH)2(l) = 3Ca3 Al2 (SiO4 )(OH)8(s) + 8NaOH(l) + nH2 O(l)
The obtained pig iron can successfully be used at EVRAZ

Summary

Introduction

The accumulation and storage of the alumina production waste, red mud (RM), represents one of the most critical ecological problems for the aluminum industry. Depending on the composition of the initial bauxite ore and its processing technology, 1.0 to 1.4 tons of RM can be formed from the production of 1 ton of alumina [1,2]. RM in Russia is barely utilized but stored in slurry storages. About 600 million tons of RM are already accumulated at aluminum plants in Russia [3]. The construction and operation of slurry storages require significant costs that leads to an increase of the cost value of alumina and, of metallic aluminum. There is a high risk of ecological disasters: Dams breaks and weathering process make this problem even more severe [4]

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Results

Conclusion