Experimental and Numerical Studies on a One-Step Method for the Production of Mg in the Silicothermic Reduction Process

Abstract

In this paper, a new efficient one-step technical method was first developed for the production of magnesium in the industry. The one-step method could combine the two processes of dolomite decomposition and magnesium reduction in the magnesium reduction retort. Thus, the high-temperature carbon dioxide produced by the dolomite decomposition process could be collected in a timely manner instead of being emitted into the atmosphere, and excessive heat loss caused by the two separate processes also could be almost completely avoided. This paper presents an experimental study on the intrinsic chemical kinetics mechanisms of this new efficient one-step technology. By applying each of the most likely solid-state kinetic models, the kinetic parameters of the two reactions that reacted during the dolomite decomposition stage and magnesium reduction stage were evaluated, and the kinetic models that best verify the experimental data were attempted. For the dolomite decomposition stage of the one-step technology, the equation of the chemical kinetic model can be represented by α2/2 = k D1τ in the temperature range of 1173–1473 K, and the apparent activation energy was determined to be 160.6 kJ mol–1. For the magnesium reduction stage of the one-step technology, the surface reaction chemical kinetic model 1 – (1 – β)1/3= k Sτ described very satisfactorily the experimental values for the different reduction temperature. Then, a one-step model incorporating the chemical reaction kinetics of the dolomite decomposition stage and the magnesium reduction stage and heat conduction was first developed. The simulations of the impact of heating temperature on the dolomite decomposition stage and magnesium reduction stage were carried out in the reduction retorts of the furnace utilizing this model. The distribution of dolomite decomposition extent in the retorts, the total extent of dolomite decomposition with time, the distribution of magnesium reduction extent in the retorts, and the total extent of magnesium reduction with time were studied in detail. The analysis showed that the one-step technology is effective in not only reducing the cycle time of dolomite decomposition stage and magnesium reduction stage but also saving energy.

In Situ Observation of Carbon Dioxide Capture on Pseudo-Liquid Eutectic Mixture-Promoted Magnesium Oxide

“…In this regard, practical and cost-effective technologies to capture and greatly reduce greenhouse gas emissions are critically needed. Currently, carbon capture and sequestration (CCS) is among the leading technologies that can significantly and practically reduce greenhouse gas emissions, as various transformational capture technologies are close to application. − Among the materials available, solid sorbents are considered to be promising because they are applicable over a wide range of temperatures (ambient to 700 °C), yield less waste during cycling, and are easier and safer to dispose. , Solid sorbents are also easier to regenerate and are applicable at higher pressures as compared to liquid sorbents, making them more efficient. − …”

Experimental Study of Magnesium (Mg) Production by an Integrated Calcination and Silicothermic Reduction Short Process

“…It was estimated that about 7.55 MJ per kilogram of magnesium can be saved. [10] In addition, high-temperature dolime might have higher activity to react with ferrosilicon, improving the utilization rate of dolime and yield of magnesium. Third, the high investment in a rotary kiln and flue gas purification equipment can be saved.…”

“…Hence, these reaction processes need to be investigated, analyzed and discussed. First, it was inferred that metal oxides of Fe 2 O 3 , FeO, Fe 3 O 4 and SiO 2 might produce reactions [8] through [10] and [11] In this study, the metal oxide compositions in briquettes and residuals after thermal decomposition at various conditions were determined by the ethylene diamine tetraacetic acid (EDTA) complexometric titration method; the content of silica in briquettes and residuals was determined by the molybdenum blue spectrophotometric method. Figure 8 shows the contents of CaO, MgO, SiO 2 and Fe 2 O 3 for residual samples decomposed at 900°C, 1000°C, 1100°C and 1200°C, respectively.…”

“…However, a remarkable difference was observed in the reddish brown color of the residual obtained when decomposed at 1100°C in the briquette with ferrosilicon. Combining the red Fe 2 O 3 , dark FeO and Fe 3 O 4 and the metal elements in ferrosilicon, it was inferred that reactions between Fe and CO 2, i.e., reactions [8] through [10], did occur.…”

Nucleation and Condensation of Magnesium Vapor in Argon Carrier

“…Zhang et al have combined calcination and reduction steps to study the kinetics of a one-step Mg reduction by experiment and simulation. They obtained a result that the one-step Mg reduction production process can reduce reduction time and save energy [10][11][12][13]. Fu et al studied the thermodynamics and kinetics of the integration process of calcination and reduction and found that canceling the calcination process can greatly save energy [14][15][16][17][18].…”