In this study, the mesoporous silica material was hydrothermally synthesized from the rice husk ash of biomass energy industry with cetyltrimethylammonium bromide (CTAB) as template agents. The structure and morphology of mesoporous silica material was investigated based on the analysis of X-ray diffraction (XRD), N2 sorption/desorption (BET), Fourier transformation infra-red spectrum (FTIR). The results indicated that mesoporous silica material was successfully prepared by substituting rice husk ash for the traditional silica source of tetraethyl orthosilicate, and the mesoporous silica material displayed pore sizes in the 2-4 nm range with specific surface areas as high as 363 m2/g.
Based on the analysis of the properties of a high carbon pyrite from Yunnan, a series tests on gravity concentration and flotation were carried out. According to this basis, a closed-circuit flotation test scheme was worked out, which obtained a fine quality pyrite concentrate with a sulfur grade of 38.24%, comprehensive sulfur recovery of 70.87% and carbon content of only 0.87%.
Under the premise of comprehensive recycling valuable metals, a novel technology was developed to extract vanadium from spent Al2O3-based catalyst. Mixture of spent catalyst and sodium carbonate was roasted at 1000°C for 30 min with the mol ratio of Na2O to (Al2O3 + V2O5 + MoO3) as 1.15, after water leaching, 97.3% of vanadium could be extracted. With CaO addition of 25 g/L and reacting at 90°C for 4 h, 98.6% of vanadium in sodium aluminate solution was precipitated as desilication residue. The desilication residue was leached at 80°C for 45 min with sodium bicarbonate concentration of 100 g/L and L/S of 4 mL/g, over 96.4% of vanadium could be leached. By two purification steps with addition of 30 wt.% H2SO4 and Mg(NO3)2, respectively, over 99% of Al, 96% of Si, 93% of P and 95% of As were removed from leach liquor. Adding 50 g/L NH4NO3 to the purified leach liquor and adjusting pH to 8.2, 99.8% of vanadium could be precipitated as ammonium metavanadate. After calcination, the purity of V2O5 product was 98.25%. In the whole process, up to 88.7% of vanadium could be recovered from the spent catalyst.
The high-quality MCM-41 was synthesized from silica fume with Citric acid and cetyltrimethylammonium bromide (CTAB) as template agents. Silica fume entered into liquid system in silicate and matched with CTA+. Mesoporous phase formed with the help of Citric and PEG-6000 in an acidic process followed. The structure and morphology of mesoporous silica material so-prepared was investigated based on the analysis of X-ray diffraction (XRD), N2sorption/desorption (BET) and transmission electron microscopy (TEM). The results indicated that MCM-41 was successfully prepared by substituting silica fume for the traditional silica source of tetraethyl orthosilicate, and the MCM-41 displayed high quality with the pore sizes 4.3 nm, the BET areas 1058 m2/g, the total pore volume 0.862 cm3/g.
Based on the analysis of the properties of spent catalyst, extract vanadium and molybdenum from spent catalyst by roasting alkaline leaching. Sodium carbonate was leaching agent. The effects of roasting temperature, roasting time, the concentration of sodium carbonate and the number of leaching times on the leaching rate of vanadium and molybdenum were studied. Roasting temperature of 650°C, roasting time of 3h, the concentration of sodium carbonate of 50g/L and once counter-current leaching, under this condition, the leaching of vanadium is 83% and the leaching of molybdenum is 93%.Roasting alkaline leaching has good effect on extracting vanadium and molybdenum from spent catalyst.
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