Solid Salt Fluxes for Molten Aluminum Processing—A Review

Abstract

Aluminum recycling is a promising solution to environmental and economic issues. Secondary aluminum production will rise in the near future; however, the process is not without challenges. Some of the major concerns during remelting of aluminum are the metal losses due to the oxidation of the molten metal and the removal of impurities from the metal bath. The current study summarizes the latest progress in the use of solid salt fluxes for secondary aluminum production and the treatment of molten metal. The chemistry of solid fluxes has been reviewed, with a correlation to their main chemical and physical characteristics, such as density, fluidity, wettability, and reactivity. An overview of the main types of solid fluxes is also provided, with a particular focus on their functions and applications. The efficiency of solid fluxes relies on several factors, including but not limited to the fluxes’ chemical composition and physical properties, flux amount, processing temperature, and flux morphology. The effect of salt fluxes in delivering satisfactory metal cleanliness and sufficient metal recovery has been summarized according to the main flux’s properties.

Influence of Metal Processing on Microstructure and Properties: Implications for Biodegradable Metals—A Mini Review

“…Fluxes are chemical elements or compounds that are added to metal melts to create a barrier restricting the interaction between oxygen in ambient air and active metals. Fluxing agents decrease metal oxidation, help remove impurities, and produce better quality materials [105]. Another function performed by fluxing compounds is lowering metal melting point and increase fluidity [106].…”

The Impact of Heating Temperature and Flux Ratio on the In-Situ Casting Technique as a Direct Recycling of AlSi7Mg Machining Chips

“…The fluxing process is one of the preeminent and extensively embraced methodologies for refining molten aluminium and eliminating oxide inclusions, including oxide films. Fluxes typically comprise solid substances designed to eliminate impurities and enhance the fluidity of the molten metal [10]. Shi et al, [11] also have found that the salt flux, comprising equimolar NaCl-KCl, can utilized to reclamation aluminium from waste aluminium and aluminium dross.…”

The Separation Behavior of TiB2 during Cl2-Free Degassing Treatment of 5083 Aluminum Melt

“…On one hand, a good TiB 2 inoculation practice provides sufficient time for the master alloy to dissolve and for TiB 2 particles to disperse in the melt [1]. On the other hand, caution needs to be exercised to avoid the decay of TiB 2 particles during different melt-handling steps, i.e., salt fluxing [4], melt transfer [5], melt holding, degassing [6,7], and filtration [8][9][10]. In order to determine the best location and timing for TiB 2 inoculation, it is imperative to know whether these melt-handling steps remove or lead to decay of the TiB 2 particles.…”