Kinetics of extracting magnesium from prefabricated pellets by silicothermic process under flowing argon atmosphere

Abstract

The Pidgeon process is the main extraction method of magnesium, but its continuous production cannot be achieved due to the switch between vacuum and atmospheric pressure. Therefore, it is vital to realize continuous extraction of magnesium under atmospheric pressure. In this paper, the process of extracting magnesium from prefabricated pellets in flowing argon was proposed. The isothermal kinetic analysis of the reduction process was carried out. The results showed that the reduction process was controlled by diffusion process in 1 h, and the apparent activation energy of extracting magnesium from prefabricated pellets in flowing argon was 218.75 kJ/mol. Then the influence of experimental factors on the reduction rate was explored, including briquetting pressure, carrier gas flow rate, ferrosilicon content, reaction temperature and time. Through analysis and calculation, it was concluded that the main control step of diffusion process was silicon diffusion.

The effect of calcium fluoride on extracting magnesium from magnesite and calcium carbonate by silicothermal reduction in flowing argon

“…After reaching the reduction temperature, the crucible was put back to the original position for reduction experiment. The specific isothermal reduction operation method had been described in detail in the previous literature [23]. After the experiment, the phase analysis and magnesium content in the cooling slag were determined by X-ray diffraction (XRD, Bruker D8, Germany) and inductively coupled plasma emission spectrometer (ICP-OES, Optima 8300DV, Perkin-Elmer, USA),respectively.…”

“…However, due to the excessive CaF2 content, the reduced slag would bond to the reduction tank in a semi molten state, which made it difficult to slag out. For the novel magnesium production technology, the preparation process, properties and calcination decomposition kinetics of pellets had been investigated [20,21], and the reduction kinetics and element diffusion mechanism had been studied by thermogravimetric experiments and isothermal reduction experiments [22,23]. However, the effect mechanism of CaF2 on the calcination and reduction process of magnesium production process with prefabricated pellets was still unclear.…”

Thermal process for magnesium production with Al-Si-Fe from coal fly ash: Thermodynamics and experimental investigation

“…More and more AlN can be produced after 1969.14K by the reaction (1). The generated AlN will react with SiC by the reaction (2) by reactions ( 8) and ( 9) proceeds more and more with the increase of temperature.…”

“…Carbothermic reduction of magnesia to produce magnesium is reported experimentally [1]. Among thermal reduction processes, Pidgeon process has made a strong revival, particularly in China during the past few decades [2]. The advantage of Pidgeon process over electrolytic process is that the main source of magnesium is dolomite, which merely requires calcining, unlike the complex purification that the electrolytic route requires to produce anhydrous magnesium chloride feed [3,4].…”