Relationships among Preparative Technique,Phase Composition and Bending Strength of Bauxite Porcelain

1 INTRODUCTION Bauxite porcelain is a novel “K2O–Al2O3–SiO2” system ceramic by using sintered bauxite, clay and potash feldspar and albite as the main raw materials with the Al2O3’s content of 50%～60(massfraction). Compared to the traditional“K2O–Al2O3–SiO2” feldspar porcelain by using quartz, bolus alb and potash feldspar and albite as the main raw materials, the bauxite porcelain possesses such advantages as high mechanical strength, excellent electrical insula- tion prop…     

A structural model for the time-dependent recovery of mineral suspensions

A thixotropic recovery model has been developed that is based on consideration of the microstructural interactions that occur between particles within a suspension particle network. The model is based on Smoluchowski coagulation rate theory, utilizing second order kinetics to describe the thixotropic recovery behavior. The model is applied to Na-montmorillonite-based coal tailings suspensions and is also shown to be applicable to brown coal and bauxite residue suspensions. The model describes all the recovery data well, especially at intermediate to large recovery times. The recovery of the montmorillonite suspensions at short times was faster than predicted, indicating the existence of additional factors in early-time structure development. The discrepancy may have also been due to the highly anisotropic nature of the clay platelets. The recovery rate constant, K _r , increases with increasing solids concentration (for constant surface chemical conditions) as would be expected from the basis of the model. Received: 22 September 2000 Accepted: 16 March 2001     

铝土矿中微量镓的分析方法进展

综述了近几年国内铝土矿中镓分析方法的研究进展,叙述了用于微量镓分析测定的光度法、伏安法、原子吸收光谱法、电感耦合等离子体-原子发射光谱法、电感耦合等离子体-质谱法、X射线荧光光谱法等分析方法,对方法的优缺点进行了评述,并对今后微量镓分析测定方法进行了展望.     

基于红外光谱分析研究矿化剂对铝酸钙粉制备的影响

研究了矿化剂对中低品位铝矾土对所制备铝酸钙粉的结构及其光谱性能的影响。以中低品位铝钒土和碳酸钙为主要原料,矿化剂CaF₂为添加剂,三者经充分混合、 高温煅烧和粉磨后,生产出的铝酸钙粉可直接用于制备聚合氯化铝、 聚合硫酸铝、 铝酸钠等水处理剂。通过调整原料中铝矾土和碳酸钙的质量比和矿化剂CaF₂投加量的方法优化铝酸钙粉的制备工艺,采用红外光谱分析对铝酸钙粉和铝矾土进行表征,并对矿化剂的矿化机理进行研究。红外光谱分析结果表明：加入矿化剂CaF₂,可促进铝矾土中硬水铝石、 三水铝石和高岭石的分解转化,使碳酸钙的分解完全,使原料中的铝矾土与碳酸钙进行更加充分的反应,不仅有助于碳酸钙中的Ca与铝矾土中的Si结合,还有助于促进铝矾土中的Si—O,Si—O—Al及Al—Si键的断裂,使铝矾土中的Al充分溶出,从而提高Al₂O₃的溶出率;矿化剂CaF₂的投加量(质量比)为3%时,可有效促进Al₂O₃的溶出;矿化剂CaF₂的投加量为1.5%时,不足以起到充分的矿化作用;中低品位铝矾土较高品位铝矾土更易于烧结制备铝酸钙粉;在1 250 ℃下制备铝酸钙粉的最佳物料配比是：原料中铝矾土与碳酸钙的质量比为1∶0.6,矿化剂CaF₂的投加量为3%。     

铝土矿矿泥固化技术的试验研究

铝土矿选洗过程中排尾形成的高含水量矿泥,传统上采用建库堆存,泌干固结时间长,污染环境。试验研究结果表明,选用由72%水泥、20%石膏、5%石灰、3%硫酸钠组成的复合固化剂,或由72%石灰、20%石膏、5%粉煤灰、3%硫酸钠组成的复合固化剂,按固化剂与矿泥质量比1:10掺加,对矿泥进行固化处理,其固化体强度高、耐久性好,且成本低廉,具有广泛的工程应用价值。     

改性铝土矿载体负载Ru催化剂上的水煤气变换制氢

采用水热法对天然铝土矿进行改性,获得高比表面积的铝土矿(bauxite)载体.用等体积浸渍法制备了Ru含量为1.0%-4.0%(质量分数,下同)的Ru/bauxite催化剂和Ru含量为2.0%的Ru/Al2O3催化剂,以水煤气变换反应为探针反应,考察了催化剂性能.利用X射线荧光元素分析(XRF)、X射线粉末衍射(XRD)、低温N2物理吸附、H2程序升温还原(H2-TPR)以及CO程序升温脱附(CO-TPD)等对载体和催化剂样品进行表征.结果表明,不同Ru含量的Ru/bauxite催化剂具有优异的水煤气变换制氢性能,优于Ru/Al2O3催化剂.其原因是铝土矿本身含有的Fe2O3与负载的Ru之间发生了相互作用,降低了Fe2O3还原温度,提高了对CO的吸附能力且降低了CO的脱附温度,进而提高了催化剂的水煤气变换反应性能.     

X射线荧光光谱法测定铝土矿中的主成分

建立了X射线荧光光谱法测定铝土矿中主要成分氧化铁、氧化硅、氧化铝、氧化钠、氧化钾、氧化钛、氧化钙、氧化镁的方法。将铝土矿样品以四硼酸锂作熔剂,氟化锂作助熔剂,碘化铵作脱模剂高温熔融制备成玻璃熔片,以标准物质和自制标样作校准曲线,在XRF-2400仪上按选定的仪器条件测量强度,按预先建好的校准曲线计算结果,并与化学法进行对照,结果基本一致,方法操作简单、快速,准确度和精密度均达到国家标准方法规定的要求。     

Determination of Ga,Th, and U in Bauxite and Coal Ash by Epithermal Neutron Activation Analysis

Neutron activation analysis is applied to the determination of Ga, Th and U in Bauxite and coal ash; thermal and epithermal irradiations are used. The other analytical methods are also quantitatively surveyed for gallium. The results indicate that epithermal neutron activation is prefered for those trace elements because the former method is more simple and quick.     

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.