Aluminothermic Reduction of Manganese Oxide from Selected MnO-Containing Slags

Abstract

The aluminothermic reduction process of manganese oxide from different slags by aluminum was investigated using pure Al and two types of industrial Al dross. Two types of MnO-containing slags were used: a synthetic highly pure CaO-MnO slag and an industrial high carbon ferromanganese slag. Mixtures of Al and slag with more Al than the stoichiometry were heated and interacted in an induction furnace up to 1873 K, yielding molten metal and slag products. The characterization of the produced metal and slag phases indicated that the complete reduction of MnO occurs via the aluminothermic process. Moreover, as the Al content in the charge was high, it also completely reduced SiO2 in the industrial ferromanganese slag. A small mass transport of Ca and Mg into the metal phase was also observed, which was shown to be affected by the slag chemistry. The obtained results indicated that the valorization of both Al dross and FeMn slag in a single process for the production of Mn, Mn-Al, and Mn-Al-Si alloys is possible. Moreover, the energy balance for the process indicated that the energy consumption of the process to produce Mn-Al alloys via the proposed process is insignificant due to the highly exothermic reactions at high temperatures.

Aluminum Recovery from White Aluminum Dross by a Mechanically Activated Phase Separation and Remelting Process

“…The recent published work by the authors showed that the rich Al particles can be recycled via their use for the reduction of manganese oxide from waste from the ferromanganese industry, which yields Al-Mn alloys. 36 In this process, a large portion of the Al in the dross particles is distributed into the produced alloy, and the rest is consumed to reduce manganese oxide (MnO). The non-metallic components are removed via an oxide slag byproduct, without any salt use.…”

Valorization of Aluminum Dross with Copper via High Temperature Melting to Produce Al-Cu Alloys

“…Pure aluminum is the Earth's third most abundant element, accounting for about 8% of the mass of the Earth's crust, and it never occurs as a free element in nature [3,4]. At present, aluminum is mainly produced via two different methods: (I) a primary aluminum production from bauxite ore via the Bayer process for alumina extraction, followed by Hall-Heroult electrolysis for Al extraction from alumina, and (II) by recycling aluminum from process scrap and used aluminum products [3][4][5][6][7]. The world's production of aluminum is increasing every year and was approx.…”

“…The world's production of aluminum is increasing every year and was approx. 64 million metric tons in 2019 with a daily average of 174.5 thousand tons [3,7], while in 2020 it was over 65 million metric tons in 2020 [8]. As a result of the exposure of liquid aluminum to the oxidizing atmosphere that is present during the process of melting and alloying, a surface oxidation takes place, leading to the formation of a semisolid skin over the molten Al metal, which also hinders further oxidation [7].…”

“…64 million metric tons in 2019 with a daily average of 174.5 thousand tons [3,7], while in 2020 it was over 65 million metric tons in 2020 [8]. As a result of the exposure of liquid aluminum to the oxidizing atmosphere that is present during the process of melting and alloying, a surface oxidation takes place, leading to the formation of a semisolid skin over the molten Al metal, which also hinders further oxidation [7]. This floating skin over liquid Al is called aluminum dross and consists mainly of aluminum oxide, metallic aluminum, magnesium spinel (MgAlO 4 ), periclase (MgO), quartz (SiO 2 ), and salts with small traces of aluminum carbides and nitrides [9,10].…”

“…The recycling of Al dross, which is a by-product, is important from both environmental protection and economic points of view [4,6]. Generally, there are two types of Al dross: (I) White Dross (the primary dross) and (II) Black Dross (the secondary dross) [3,7].…”