铝电解槽内熔体流动和铝液传质规律研究

本文以300kA系列铝电解槽为研究对象,以数值模拟方法为研究手段,建立了铝电解槽内多相流动模型和极距间铝液传质模型,研究了铝电解槽内熔体流动和铝液传质规律,分析了阳极气泡对于流场和铝液浓度场的影响,并计算了不同工况下槽内流场和铝液浓度场,分析了铝水平和极距对电解槽的影响并求得300kA系列下的最优解。

Equilibrium concentration of lithium ion in sodium aluminate solution

Excess lithium in alumina is significantly bad for aluminum reduction.In this study,the concentration variation of lithium ion in sodium aluminate solution with addition of synthetic lithium aluminate was investigated.Elevating temperature,increasing caustic soda concentration,reducing alumina concentration or raising molar ratioαk improved equilibrium concentration of lithium ion in sodium aluminate solution.Agitation speed had a minimal effect on lithium ion concentration.Over 0.65 g/L lithium ion equilibrium concentration was observed in digestion process,whereas 35 mg/L lithium ion concentration remained in solution after precipitation time of 9 h.Moreover,equilibrium concentration decreased sharply from digestion of boehmite or diaspore to seed precipitation,about 95%lithium was precipitated into red mud(bauxite residue)and aluminum hydroxide.This study provides a valuable perspective in removal or extraction of lithium from sodium aluminate solution in alumina refineries.

pH Value Effects in Shear Rheology of Concentrated Alumina Suspensions

The influence of pH on the rheological properties of concentrated alumina suspensions was investigated. At various pH values, the alumina exhibited pseudoplastic, near Bingham flow behaviors. The fully-deflocculated suspensions exhibited Newtonian flow behaviors, while the fully-flocculated suspensions demonstrated very high viscosity and shear yield stress.

A study on Cr(Ⅵ)reduction from aqueous solutions by bauxite

The reduction of Cr（Ⅵ） in aqueous solution by using bauxite ore was investigated.Experimental results for Cr（Ⅵ）reduction in aqueous solution depending on some factors such as time,sulfuric acid amount,bauxite dosage,initial Cr（Ⅵ）concentration,formic acid concentration,daylight and temperature were presented.The obtained results show that sulfuric acid amount,bauxite dosage and initial Cr（Ⅵ） concentration of solution are most effective parameters on the reduction process.Also,it has been found that the 60 g/L of bauxite dosage is sufficient to reduce up to 100% of Cr（Ⅵ） from acidic solution under the condition of low initial Cr（Ⅵ） mass concentrations such as 10 mg/L.The reduction reaction is completed within 30 min at 25 ℃ under the experimental conditions：bauxite dosage of 60 g/L,amount of sulfuric acid 40-60 stoichiometric and initial mass concentration of Cr（Ⅵ）,10 mg/L.It was determined that reduction percentage is decreasing with increasing initial Cr（Ⅵ） concentration.The chemical oxygen demand of bauxite ore was found to be 26 mg COD/g.

Improving the performance of inverted organic solar cells by adjusting the concentration of precursor solution of Al-doped ZnO

Al-doped ZnO(AZO) has been used as an electron transport and hole blocking buffer layer in inverted organic solar cells(IOSCs). In this paper, the AZO morphology, optical and structural properties and IOSCs performance are investigated as a function of precursor solution concentration from 0.1 mol/L to 1.0 mol/L. We demonstrate that the device with 0.1 mol/L precursor concentration of AZO buffer layers enhances the short-circuit current and the fill factor of IOSCs simultaneously. The resulting device shows that the power conversion efficiency is improved by 35.6% relative to that of the 1.0 mol/L device, due to the improved surface morphology and transmittance(300–400 nm) of AZO buffer layer.