Defluoridation kinetics of 200 °C calcined bauxite, gypsum, and magnesite and breakthrough characteristics of their composite filter

Reaction kinetics and breakthrough characteristics in water defluoridation were studied through experiments with 200 °C-calcined bauxite, gypsum and magnesite and their composite filter. The aim was to determine defluoridation potential of a composite filter of the three locally sourced natural materials in contribution towards fluorosis mitigation. The materials were crushed and sieved to particle sizes of 1.2-1.4 mm diameter, and then heat-treated at 200 °C for 2 h. Their defluoridation capacities and reaction kinetics were determined in batch. A composite was then prepared in the ratio of the loading capacities. Breakthrough characteristics were experimented on in fixed bed through bed depth service time (BDST) design model, empty bed residence time (EBRT) optimisation model and the two parameter-logistics (2-PL) model. Mean loading capacities of 5.6, 3.4 and 1.7 mg F⁻/g were obtained for bauxite, gypsum and magnesite, respectively. Loading capacities decreased, while sorption percentages increased, with increase in dose level. Second order kinetics observed had rate constants 4.07 × 10⁻², 1.87 × 10⁻², 1.59 × 10⁻² g mg⁻¹ min⁻¹ for bauxite, gypsum and magnesite, respectively. Composites, bauxite and gypsum decreased, while magnesite increased water pH. Time at 50% breakthrough (τ) obtained experimentally compared well with τ obtained through the two-parameter logistics model indicating good fitness of data to the model. Greater doses obtained higher breakthrough times that were, 120, 210, 255 and 360 min for 45, 75, 120 and 150 g, respectively. Critical bed depth (Z_o), 7.71 cm and an operating line, ? = 4 × 10⁻⁴δ − 0.0757δ + 4.86 (? = adsorbent exhaustion rate, δ = EBRT) were obtained. The water quality was within recommended quality limits for pH, apparent colour, hardness, and residual concentrations of SO₄²⁻, Cl⁻, Fe²⁺, and Al³⁺ in fixed bed. The research showed that a composite filter of the three materials, prepared in the ratio of their loading capacities and calcined at 200 °C, is a potential defluoridating filter in fixed bed configuration.     

用工业固体废料合成沸石分子筛的研究进展

系统总结了以工业固体废料为原料合成沸石分子筛材料的最新研究进展, 讨论了以粉煤灰、 珍珠岩工业废料、 煤矸石、 流体催化裂化(FCC)废催化剂、 锂矿渣、 铝土矿渣、 废瓷料和废弃玻璃等工业固体废料为原料, 合成LTA, FAU, MFI, CHA, GIS, SOD, ANA和KFI沸石分子筛材料的工艺方法, 及其在污水中重金属离子的脱除、 空气中CO₂的捕获、 氮氧化物的选择性还原等实际应用中的性能, 并对未来工业固体废料合成沸石分子筛的发展趋势进行了展望.     

铝土矿中高岭石的红外光谱定量分析

本文用红外光谱法对铝土故中的高岭石作了定量分析,得出了校准曲线,并进行了验证（定量特征峰选在３６９５ｃｍ＾－１）,得到了比较满意的结果,在生产具有实用意义。     

悬浮液进样ICP-AES测定铝土矿中的铁、镁、硅、钙和钛

使用悬浮液进样ICP AES法测定铝土矿中的铁、镁、硅、钙和钛。样品以TritonX 100溶液作为分散剂,经超声波分散后,在磁力搅拌下动态进样。使用水溶液标准进行校准,不进行基体匹配。实验结果与溶液进样法一致,检出限为:Fe0.048μg mL,Mg0.0008μg mL,Si0.028μg mL,Ca0.0014μg mL,Ti0.013μg mL,相对标准偏差(RSD):MgO5.5%,Fe2O30.61%,SiO20.40%,TiO20.34%,CaO0.89%。本法与溶液法相比无需熔样,简化操作手续。     

原子吸收光谱法分析铝土矿中氧化镁

本文提出了将试样用氢氧化钠熔融后，转换为酸性溶液，在盐酸介质中直接引入原子吸收测定。主体元素铝、钛，硅对测定有干扰，用氯化锶消除。本方法操作简便、更现性好、灵敏度高，MgO 0-40μg/50mL呈良好线性关系，测量下限可达0.03％，适用于铝土矿中氧化镁的测定。     

Synthesis and characterization of a novel collector for the desulfurization of fine high-sulfur bauxite via reverse flotation

Bauxite is one of the main raw materials in the alumina industry. Fine high-sulfur bauxite flotation desulfurization is a great challenge presently. This study aims to synthesize nanoparticle collectors (NPCs) by emulsion polymerization to improve the abovesaid flotation desulfurization process. The physicochemical properties of high-sulfur bauxite were analyzed, and the experimental conditions for the synthesis of NPCs were optimized. The interaction mechanism between NPCs and pyrite was studied via fundamental analyses including SEM (Scanning Electron Microscope), FT-IR (Fourier Transform Infrared spectoscopy), Zeta-potential, XPS (X-ray Photoelectron Spectroscopy), and wettability. Under the closed-circuit flotation flowsheet of “one roughing-two cleaning-three scavenging”, aluminum concentrate with a yield of 85.91% and sulfur content of 0.56% were obtained using a common collector. However, with the addition of the novel NPC, aluminum concentrate with a yield of 85.70% and sulfur content of 0.36% could be obtained by a simpler flowsheet of “one roughing-one cleaning-two scavenging”. The improvement in flotation performance is suggested to be contributed by the addition of spherical NPC, which induced a rougher and more hydrophobic pyrite surface.