Aluminum Alloys with the Addition of Reduced Deep-Sea Nodules

Abstract

An innovative way to utilize deep-sea manganese nodules is described in this paper. The manganese nodules were reduced by aluminothermy and subsequently added into aluminum as a mixture of alloying elements in their natural ratio. The microstructure and properties of aluminum alloys containing 1.2, 7.7, and 9.7 wt % of reduced nodules were studied. The alloys were formed by Al matrix and minor amounts of Al6(Fe,Mn) and Al11Fe7 intermetallic phases. The alloys containing a higher amount of reduced nodules are characterized by very good thermal stability. The obtained alloys were studied by X-ray diffraction, their microstructure was observed by scanning electron microscopy, and their local chemical composition was analyzed by energy dispersive spectrometer. The hardness of the samples was measured on the initial materials and after long-term annealing. Based on the obtained results, the aluminum alloys, with the addition of reduced deep-sea nodules, can serve as precursors for processing, e.g., by rapid solidification or hot working methods.

Deep-sea nodules metallo-thermic reduction as a new “natural alloys” concept

“…The Heusler phases Mn 2 FeSi and Mn 2 FeAl were observed as one of earliest observation within the presented projects [1]. Beyond structural observations the thermal stability up to 1600 °C, hardness, tribological properties and corrosion resistance were investigated [1,2], even using reduced nodules in aluminum alloys [3]. The narrower set of alloys were reduced by titanium, Fig.…”

Possibilities of a Direct Synthesis of Aluminum Alloys with Elements from Deep-Sea Nodules

“…The individual elements are thus further removed by specific reactions, such as copper extraction using active powdered sulfuric anhydride; nickel and cobalt extraction using active sulfur together with manganese or MnO 2 extraction from ammonia; and where filtration is used, washing the filter with manganese hydroxide, drying in rotary kilns and briquetting. A more sophisticated way is the selective extraction of metals of interest in acids or bases [16,17]. This selective extraction of metals of interest in acids is achieved by the use of various types of reducing agents, where in the latest study, steel scrap is repeatedly used as a reducing agent for manganese recovery [18,19].…”

“…It is based on the nonseparation of individual elements from nodules and the use of nodules as a whole, when a completely new alloy is formed. Since nodules contain a high percentage of MnO 2 and the process of aluminothermic reduction to reduce MnO 2 is a commonly used process, a process for treating deep-sea nodules by aluminothermic reduction has been proposed [16], which was used also in this work. In metallothermic reduction, metal is used as a reducing agent.…”