Wenlong Jiang

Study on Effect of Al-O-C Compound in Alumina Carbothermal Reduction

In this paper, The structures and properties changes for single unit cell of alumina, Al-O-C compounds and aluminium carbide were simulated by first principles method. According to theoretical calculation results, alumina carbothermal reductions with coal and charcoal separately used as reductant were carried out under vacuum. The major equations in carbonthermal reduction reduced to three general equations by reaction temperature; the sequence for each substance which formed in reductions was Al4O4C→Al2OC→Al4C3

Removal of Sulfur from Copper Dross Generated by Refining Lead

Typical copper dross, the byproduct of lead bullion pyrometallurgical refining for copper removal, mainly contains Pb, Cu, S, As, Sb and Sn etc. In traditional treatment process, copper dross is transformed to be copper matte by smelting with iron scarp and iron pyrite. Here, a new treatment process of converting-vacuum distillation (CVD) was proposed and investigated. Based on this concept, the converting process was tentatively investigated in this paper. The results of element distribution of converting samples showed the sample has three layers. The upper layer is mainly sulfides of lead and copper, the middle layer is mainly copper arsenide, and the lower layer is lead arsenide and crude lead. On the condition of oxygen flow rate 400 ml/min, the converting temperature 1000 °C, the holding time 1 h, the converting time 10 min, the lead copper alloy containing 0.17% S was obtained.

A comparison of the thermal decomposition mechanism of wurtzite AlN and zinc blende AlN

The sublimation route is one of the primary and most significant methods for the synthesis of an aluminum nitride (AlN) single crystal. Its long synthesis time and high reaction temperature, however, limit the production of its commercial product. In this work, we applied HSC Chemistry 6 software, ab initio molecular dynamics, and X-ray diffraction to investigate the thermal decomposition of AlN. We calculated the decomposition temperatures of AlN under vacuum and simulated the decomposition mechanism of AlN by the ab initio molecular dynamics method. According to the thermodynamic calculations, the decomposition temperature of AlN decreased following a decrease in the system pressure. The ab initio molecular dynamics results indicated that wurtzite-type AlN (w-AlN) was decomposed by the layer-by-layer mechanism and followed a decomposition reaction equation of AlN → Al(g) + 0.29N2(g) + 0.42N(g), which originated from the inequality sp3 hybridization. The zinc-type AlN (z-AlN) decomposed from the surface to interior of the structure because of the equality of the sp3 hybridization, and the z-AlN decomposition reaction equation followed AlN → Al(g) + 0.5N2(g). The AlN decomposition experiments further verified that Al(g) was the product of the wurtzite-type AlN thermal decomposition. This work can provide valuable information for the preparation of the AlN single crystal.

Investigation on Recycling of Ag from Pb‐Cu‐Ag Alloy by Vacuum Distillation

The feasibility of recycling of Ag from Pb-Cu-Ag alloy by vacuum distillation was analyzed at six different temperatures (973, 1023, 1073, 1123, 1173, and 1223K) under the vacuum of 1–20Pa. The saturated vapor pressure, separation coefficient and gas-liquid phase equilibrium were calculated. The results show that this method is feasible. The influence of distillation temperature and time on the result of experiment was also investigated. The results show that Ag content in the residue and Pb and Cu content in the volatile increase with the increasing distillation temperature and time. The enriching times of Ag and the removal rate of Pb are larger than 32 and 99.9%, respectively at 1223K corresponding to 30–120min. The optimum distillation condition is the temperature of 1223K and time 60 min, and the high purity of Ag (93.3 wt. %) is reached.