Mixed rare earth concentrate leaching with HCl-AlCl_3 solution

Abstract A method of Baotou mixed rare earth concen- trate leaching was investigated. According to the principle of complex leaching, the quadratic orthogonal regression experiment was used to investigate effect of six factors. An optimal condition of low energy and environment friendly was determined as follows： HCl acidity is 4 mol.L-1, AlCl3 concentration is 2 mol.L-l, reaction temperature is 85 ℃, reaction time is 90 rain, liquid to solid ratio is 35 ml.g-1, and stirring speed is 100 r.min-1. According to this condition, the leaching ratio of mixed rare earth con- centrate is 76.5 %. The analyses of X-ray diffraction shows that bastnasite disappears, and the main peaks of filter residue is monazite and cheralite after leaching of HCl- AlCl3 solution. The result indicates that REFCO3 of the mixed rare earth concentrate can be dissolved, but REPO4 remains in the leaching residue. This method provides a way to separate and extract rare earth.

Effects of Ag,Co,and Ge additions on microstructure and mechanical properties of Be-Al alloy fabricated by investment casting

The effects of Ag,Co,and Ge additions on microstructure and mechanical properties of Be-35Al(wt.%)alloys fabricated by investment casting were studied.The results reveal that the trace metals 1.5wt.%Ag,0.7wt.%Co,and 0.8wt.%Ge additions do not change the nucleation temperature of Be phase.However,the nucleation temperature of the Al phase decreases from 642℃ to 630℃ by DSC due to the Ge addition.The strength of the alloys sharply increases due to the dissolution of the Ag and Ge solutes into the Al phase and the Co into the Be phase characterized by SEM and EDS.Obviously,the strength of Be-Al-Ag-Co-Ge alloy is improved by the solution strengthening.Furthermore,a few Ag_(3) Al particles contribute to the strength of the Al phase.Be-Fe-Al ternary intermetallic compounds which can effectively reduce the negative effect of an impurity element Fe on the mechanical properties of Be-Al alloys are also found by XRD and EDS.

Agglomeration behavior of petal-shaped cerium carbonate with different operating conditions

Agglomeration phenomenon can often be observed during the fabrication process of petal-shaped, nano-sized Ce2（CO3）3 powders. This kind of powder was produced by liquid-phase precipitation method with the template agent of polyallylamine hydrochloride （PAH）. In this study, the effects of the polymer concentration, pH value, and stirring speed on the agglomeration phe- nomenon of cerium carbonate were investigated. On the condition that the concentration of PAH is 0.9 g·L^-1, the pH value of the adjusting solution is 3-4, the final pH value is 8-10, and the stirring speed is 300-400 r·min^-1, it is found that the agglomeration phenomenon of Ce2（CO3）3 particles can be greatly prevented and the regular petal- shaped particles are formed.