王村硬质高岭土精细加工技术研究

以淄博某地煤系硬质高岭土为试样,进行矿物成分和含量的分析,研究了煅烧过程中煅烧温度、入料粒度、保温时间、添加剂用量以及成球直径对白度的影响,探讨了添加剂的增白机理,分析了煅烧产品的结构、性能.在1025℃煅烧2h并添加2wt％的NaCl作为氯化剂氯化增白煅烧高岭土,试样煅烧白度达到了90％以上,满足橡胶填料、涂料的需要,为淄博某地区煤系硬质高岭土的开发利用提供了依据.     

降低电煅无烟煤电能消耗的工艺技术探讨

根据电煅炉煅烧无烟煤的工艺原理，通过调整上部电极长度、烟道闸板及改变电煅无烟煤前上料系统通风除尘灰的排放方向等工艺控制方法，对电煅无烟煤电耗进行研究。实践证明，这些工艺条件的实施，有效地降低了电煅无烟煤的电耗，降低了生产成本。     

磷矿对牙舟陶土煅烧性能的影响研究

牙舟陶在陶瓷业界具有举足轻重的地位,陶土对牙舟陶性能具有重要的影响。为加强对牙舟陶的研究,采用化学分析法、激光粒度仪、X射线衍射仪、综合热分析仪、数显白度仪等测试手段对牙舟陶土的化学组成、粒度分布、晶相组成、热性能及白度进行了检测。结果表明：牙舟陶土主要由石英和珍珠石组成,石英质量分数为59.34%、珍珠石质量分数为34.78%。牙舟陶土颗粒分布广泛,粒径小于6.5 μm的颗粒质量分数达到58.67%,粒径越小石英含量越低。在此基础上,结合贵州黔南丰富的磷矿资源,研究加入磷矿后牙舟陶土在煅烧过程中白度、硬度及物相组成的变化规律。研究表明：牙舟陶土的白度随着温度的升高先增大后减小,在1 100 ℃时达到最大值45.5%;加入磷矿组分后,在1 100 ℃时牙舟陶土的白度增加至54%,且煅烧时固熔体形成温度下降、烧结温度降低,并伴随钙长石矿物的产生。     

Properties of phyllosilicate-based porous ceramics shaped by conventional tape casting and freeze tape casting

Silicate ceramics were shaped using tape casting (TC) and freeze tape casting (FTC) processes from three clays labeled HCR, KORS, and KCR. These clays exhibited mass content of 77% halloysite–10 Å, 29% kaolinite, and 98% kaolinite minerals, respectively. After casting the slurries, the dried tapes were sintered at 1200°C. The microstructure changes were characterized before and after sintering using scanning electron microscopy. The apparent porosity of TC samples was lower (36–47 vol.%) compared to values obtained with FTC samples (67–79 vol.%). The latter samples exhibited a highly textured porosity, with micron-sized pores aligned perpendicular to the tape surfaces. Upon sintering, the porosity of TC samples tended to decrease conversely to the case of FTC samples. Such behavior seemed related to the simultaneous effect of organic additives and ice templating. Consequently, the FTC samples showed a relatively low mechanical strength of 3–7 MPa and thermal conductivity of .14– .22 W m⁻¹ K⁻¹. After sintering, the mullite crystallization contributed to strengthen the bulk materials, helping to compensate for the detrimental effect of porosity on the stress to rupture and on thermal conductivity values.     

Intercalated kaolinite with ammonium dihydrogen phosphate as an effective flame retardant to enhance the flame retardance and smoke suppression of epoxy resins

To improve the compatibility and flame retardance of kaolinite (Kaol) in polymeric materials, ammonium dihydrogen phosphate (ADP) was intercalated into kaolinite to obtain a novel intercalated kaolinite (K-ADP) for enhancing thermal stability, flame retardance, smoke suppression, and mechanical performance of epoxy resins (EPs). The results show that the presence of K-ADP exerts a more positive effect on reducing the heat release and smoke generation of EPs than the same addition of Kaol. Condensed phase analysis shows that EP/K-ADP composite generates more aromatic cross-links in the condensed phase to reinforce the compactness and intumescence of char compared to EP/Kaol composite. Especially, 5 wt% K-ADP confers a 43.7% reduction in peak heat release rate value and a 36.3% reduction in peak smoke production rate value to EP. Toxic gases analysis shows that K-ADP conduces to inhibiting the release of combustible gases including isocyanates and aromatic volatiles, and generating incombustible gases including ammonia and carbon dioxide to reduce the intensity of EP combustion. The mechanical test shows that K-ADP imparts less adverse impact on mechanical behavior to EP composites than Kaol due to the good dispersion and compatibility between K-ADP with EP matrix.     

Behavior of Paramagnetic Iron during the Thermal Transformations of Kaolinite

Kaolinites with various degrees of structural order and iron content were heated and subsequently analyzed via electron paramagnetic resonance. Iron was present in two different states in the heated materials, either as dilute structural Fe³⁺ ions or in concentrated Fe³⁺ phases. During metakaolinization, the environment of dilute Fe³⁺ ions changed, following modifications of the Al³⁺ coordination, and the Fe³⁺ concentration increased. With the breakdown of metakaolinite, the diffusion of Fe³⁺ ions induced their exsolution in superparamagnetic iron-rich domains (Fe³⁺ clusters in γ-Al₂O₃ and/or Fe³⁺ oxide nanophases), which produced a decrease in the dilute Fe³⁺ concentration. The subsequent breakdown of γ-Al₂O₃ and the formation of mullite made the dilute Fe³⁺ concentration increase again, because of the incorporation of Fe³⁺ ions in the mullite structure.     

Aluminophosphates Oxynitrides as Base Catalysts for the Production of Dicyanomethylene Derivative Dyes

The two-step synthesis of dicyanomethylene derivative dyes has been performed using as base catalysts MgO, calcined hydrotalcites and ALPON. These solids catalyse with good conversions and selectivities the Knoevenagel reaction step, but only ALPON catalysts are able to catalyse efficiently the two reaction steps, as well as the global reaction in a one-pot system.     

Preparation of Porous Silica from Mechanically Activated Kaolinite

Mesoporous silica has been prepared by leaching of the Al₂O₃ component from mechanically amorphized kaolinite. The kaolinite was amorphized by grinding in a planetary ball mill for 1 h. After grinding the amorphized kaolinite was chemically treated with dilute sulfuric acid at 90°C for varying times. The influence of the leaching time on the porous properties and structure of the silica was studied by XRD, XRF, FTIR and BET adsorption methods. The specific surface areas of the leached samples were found to vary from 312 m²/g to 284 m²/g. The pore size distribution, calculated by the BJH method based on N₂ gas isotherms, showed a unimodal pore size distribution with an average pore size of about 3.8 nm. The total pore volume of the porous silica varied from 0.28 ml/g to 0.312 ml/g, with a uniform pore size distribution in the mesopore regions. New applications exploiting the characteristic pore size of this material are to be expected.     

煤与高岭石表面性质对凝聚过程的影响机制

煤泥水中含大量高岭石等黏土矿物,为其絮凝沉降带来较大的困难。为明确矿物性质对凝聚过程的影响机制,在应用扩展的DLVO理论计算煤和高岭石颗粒间作用力的基础上,采用聚焦光束反射测量仪监测了CaCl2用量为4.50 mmol/L时20 g/L的煤和高岭石的悬浮液在60, 100和150 r/min的搅拌转速下的凝聚过程。结果表明,颗粒间的静电作用力在颗粒表面间距2?200 nm范围内起主导作用,高岭石的电负性较大,在凝聚过程中更难发生靠近和碰撞;较高的转速可为颗粒提供较大的动量,有利于提高碰撞频率,缩短完成凝聚所需时间,实验条件下,煤和高岭石的凝聚时间分别由74和123 s缩短至47和89 s。疏水性作用力在颗粒表面间距小于2 nm的范围内起主导作用,决定了颗粒的黏附效率;煤因强疏水性,在碰撞后更易黏附,且能抵抗更高的流体剪切作用,可由19.32 μm凝聚形成100 μm的大凝聚体,而高岭石则因其亲水性难以得到较大粒度的凝聚体,均小于30 μm。     

高岭石-氨基硅烷插层复合物的制备与表征

以高岭石-甲醇(K-M)复合物为前驱体,利用置换法于常温下制备了3种高岭石-氨基硅烷插层复合物。用X射线衍射、Fourier变换红外光谱仪、透射电子显微镜、热分析仪等对复合物进行了表征。结果表明:3种高岭石-氨基硅烷插层复合物的层间距均扩大至2nm以上,插层率都大于95%。3种氨基硅烷分子均和K-M前驱体的甲氧基共同存在于高岭石层间,均呈两层倾斜排列,倾斜程度不同。氨基硅烷的插入破坏了高岭石层间的氢键,加剧了高岭石自身结构中硅氧四面体片层与铝氧八面体片层之间的错位,使得复合物片层出现不同程度的卷曲变形。3种高岭石-氨基硅烷插层复合物的热分解过程均分三步进行:表面水的蒸发及层间甲氧基的脱嵌分解、插层剂氨基硅烷分子的脱嵌、高岭石脱羟基。