Yuzhu Sun

Leaching of aluminum from coal spoil by mechanothermal activation

The process of activating coal spoil (CS) in order to recover aluminum as a high value product was investigated. The CS was first characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD) and thermo-gravimetric analysis-differential scanning calorimetry (TGA-DSC) in order to determine the chemical and mineral compositions of the CS. Then a mechanothermal activation method was adopted to increase the aluminum activity in the coal spoil. Over 95% of the aluminum in the CS could be extracted using this activation method. The mechanothermal activation process promoted the destruction of kaolinite structures and hindered the formation of amorphous γ-Al2O3. This resulted in a high aluminum leaching activity in the mechanothermally activated CS.

Modeling of strontium chloride hexahydrate growth during unseeded batch cooling crystallization by two-dimensional population balance equation

In this study, the growth of strontium chloride hexahydrate during unseeded batch cooling crystallization was investigated and modeled by the two-dimensional population balance equation. The results suggested that in a well-mixed crystallizer, no obvious agglomeration and breakage were observed. The initial supersaturation and cooling rate were the key factors of crystal growth and the crystals grew following a size dependent mechanism. Thus, the growth of SrCl2·6H2O was modeled as a function of supersaturation, temperature, and crystal size. The calculated crystal size and size distribution showed good agreement with the experimental values, proving that the model could well predict the growth behavior of SrCl2·6H2O in the system. This study not only fills the research vacancy of SrCl2·6H2O crystallization, but also contributes to the optimal design of the crystallization process, aiming at preparing SrCl2·6H2O crystals with a larger size and a narrower size distribution.

Study on Multi-Phase Flow Field in Electrolysis Magnesium Industry

Magnesium, the 8th most abundant element in the earth’s crust, was discovered and isolated by Sir Humphrey in 1808. Magnesium is classified as an alkaline earth metal. It is found in Group 3 of the periodic table. It thus has a similar electronic structure to Be, Ca, Sr, Ba and Rd. The density of magnesium at 20°C is 1.738 g/cm3. At the melting point of 650°C this is reduced to 1.65 g/cm3. On melting there is an expansion in volume of 4.2%. Magnesium is the lightest metal in large-scale commercial use. After World War II, the magnesium industry attempted to develop magnesium for a number of applications. Most of its peacetime uses take advantage of the light weight or other chemical properties. The uses of magnesium as a structural material were, however, very few. The bulk was used as an alloying element in aluminium alloys. Other uses, such as deoxidation of steel, chemical and pyrotechnics, outweighed structural uses, especially in energy-saving and environmental protection applications was wide because of its contribution to reduce energy consumption and greenhouse gas emissions. The most successful peacetime application for magnesium was in the original German Volkswagen car that was designed by Ferdinand Porsche. The VW Beetle used large magnesium alloy die castings for the crankcase and the transmission housing (both cast in halves) plus a number of smaller castings. Each Beetle contained more than 20 kg of magnesium alloy. Many of the other applications developed during the World War II, could not be quickly converted to civilian uses. Some of the uses such as aircraft wheels and aircraft engine castings and troop carrying buses were modified and then used for the basis of civilian industries. With more attention to energy and environment, magnesium will hold greater promise as a new weight-saving replacement for denser steel and aluminum alloys, and demands for magnesium will increase sharply in the future. In recent decades, demands for magnesium and its productivity increased sharply shown in Figure 1, the world productivity of magnesium reached 860,000 tons at 2007.[1-3] There are six sources of raw materials for the production of magnesium: magnesite, dolomite, bischofite, carnallite, serpentine and sea water. These sources differ in the magnesium content, in production methods, and in their origins. Some are mined from mines, some in open