PURIFICATION OF KAOLINS BY SELECTIVE DISPERSION AND FLOCCULATION

To fulfill the increasingly higher requirements on the quality of kaolins from industries, the purification of kaolins has become more and more important. Kaolins from different mines mere studied with the aitn to remove the various impurities. The mineralogical studies on the kaolins indicated that kaolinite and the major gangue minerals in the ore were all very fine. Therefore, it was difficult to separate kaolinite from the gangue minerals by conventional mineral processing techniques, such as gravity concentration, magnetic separation and flotation. Techniques for fine particles processing, i. e. selective dispersion and flocculation ivere tried to purify the kaolins. The experiments were first carried out with pure minerals of kaolinite and the gangue minerals to study the dispersion and flocculation characteristics of the different mineral suspensions under various conditions. The key factors affecting the dispersion and floccula-tion of the minerals in water were the pH of the suspension, the type and dosage of the reagents, and the strength and time of agitation. These fac-tors were adjusted to separate kaolinite from the gangue minerals. Satis-factory results were obtained with kaolin ores with different impurities from different mines. The quality of the kaolins was significantly im-proved ivith the impurities reduced to the level according ivith the specifi-cation set by the industries. The principles of the separation of kaolinite from the gangue minerals by selective dispersion and flocculation ivere dis-cussed.

Particle agglomeration and inhibition method in the fluidized pyrolysis reaction of waste resin

This work investigated the pyrolysis reaction of waste resin in a fluidized bed reactor.It was found that the pyrolysis-generated ash would adhere to the surface of ceramic particles,causing particle agglomeration and defluidization.Adding kaolin could effectively inhibit the particle agglomeration during the fluidized pyrolysis reaction through physical isolation and chemical reaction.On the one hand,kaolin could form a coating layer on the surface of ceramic particles to prevent the adhesion of organic ash generated by the pyrolysis of resin.On the other hand,when a sufficient amount of kaolin(-0.2%(mass))was added,the activated kaolin could fully contact with the Na+ ions generated by the pyrolysis of resin and react to form a high-melting aluminosilicate mineral(nepheline),which could reduce the formation of low-melting-point sodium sulfate and thereby avoid the agglomeration of ceramic particles.

An Investigation into the Performances of Cement Mortar Incorporating Superabsorbent Polymer Synthesized with Kaolin

Cement-based materials are fundamental in the construction industry,and enhancing their properties is an ongoing challenge.The use of superabsorbent polymers(SAP)has gained significant attention as a possible way to improve the performance of cement-based materials due to their unique water-absorption and retention properties.This study investigates the multifaceted impact of kaolin intercalation-modified superabsorbent polymers(K-SAP)on the properties of cement mortar.The results show that K-SAP significantly affects the cement mortar’s rheological behavior,with distinct phases of water absorption and release,leading to changes in workability over time.Furthermore,K-SAP alters the hydration kinetics,delaying the exothermic peak of hydration and subsequently modifying the heat release kinetics.Notably,K-SAP effectively maintains a higher internal relative humidity within the mortar,reducing the autogenous shrinkage behavior.Moreover,K-SAP can have a beneficial effect on pore structure and this can be ascribed to the internal curing effect of released water from K-SAP.

Improvement of Rice Plant Root by Kaolin Application in Iron Toxicity Condition at Zoukougbeu (Central-West of Côte d’Ivoire)

In the tropics, lowland rice cultivation is often confronted with the problem of iron toxicity. The solution proposed by research in general is the use of industrial silicon. However, the high cost of industrial silicon limits its adoption by farmers. A study was carried out in Zakogbeu;Center-West of Côte d’Ivoire, to assess the potential of kaolin to mitigate the effect of this soil constraint on the root of the rice plant. Five kaolin-based treatments were analyzed (T0 = 0 kg kaolin ha−1, T1 = 366 kg kaolin ha−1, T2 = 736 kg kaolin ha−1, T3 = 1097 kg kaolin ha−1 and T4 = 1465 kg kaolin ha−1 are 0, 200, 400, 600 and 800 kg SiO2 ha−1) in a device in complete random blocks, with 5 repetitions. The results obtained show that kaolin supply increases the length of the root tissue as well as the number of branching of the root of the rice plant. Root tissue increased from 10 cm with T0 treatment to more than 15 cm with treatment T4. The microscopic observation of the roots shows that in the treatment T0, the roots present only primary ramifications and the tertiary and quaternary ramifications are observed with the treatments T3 and T4. The contribution of kaolin is an alternative to inhibit the effect of iron toxicity on the rice plant root development in iron toxicity condition.

Development of Kaolin and Glass Fiber Reinforced Composites for Thermal Insulating Panels

In our modern world, where conserving energy is highly valued, thermal insulation panels play a crucial role in reducing heat transfer between two spaces, surfaces, or materials. They are used to enhance the energy efficiency of various industrial applications by minimizing heat loss and temperature control. These panels function as silent protectors, aiding in reducing energy consumption and making things more sustainable and better for the environment. This is where composite materials come in;they are known for their lightweight nature, high strength-to-weight ratio, and excellent thermal insulation properties and have gained significant attention. Researchers are actively engaged in various studies aimed at enhancing these materials further. This research project focuses on the development of kaolin and glass fiber-reinforced composites for thermally insulating panels, to which natural strengthening materials like corn husk and bamboo fibers are added. The aim is to create cost-effective and efficient composite materials for thermal insulation applications by incorporating these components with a binder consisting of potassium silicate, hydroxide, and distilled water. This project involves conducting compression tests, bending tests, impact tests, thermal conductivity measurements, and microscopic analysis to evaluate the mechanical and thermal properties of the developed composites. The profound impact of these engineered composites on thermal insulation panels stands to revolutionize energy conservation efforts, offering a potent avenue to minimize heat loss and enhance overall energy efficiency across an array of industrial sectors.

Fabrication and Characterization of Bamboo—Epoxy Reinforced Composite for Thermal Insulation

As global warming intensifies, researchers worldwide strive to develop effective ways to reduce heat transfer. Among the natural fiber composites studied extensively in recent decades, bamboo has emerged as a prime candidate for reinforcement. This woody plant offers inherent strengths, biodegradability, and abundant availability. Due to its high cellulose content, its low thermal conductivity establishes bamboo as a thermally resistant material. Its low thermal conductivity, enhanced by a NaOH solution treatment, makes it an excellent thermally resistant material. Researchers incorporated Hollow Glass Microspheres (HGM) and Kaolin fillers into the epoxy matrix to improve the insulating properties of bamboo composites. These fillers substantially enhance thermal resistance, limiting heat transfer. Various compositions, like (30% HGM + 25% Bamboo + 65% Epoxy) and (30% Kaolin + 25% Bamboo + 45% Epoxy), were compared to identify the most efficient thermal insulator. Using Vacuum Assisted Resin Transfer Molding (VARTM) ensures uniform distribution of fillers and resin, creating a structurally sound thermal barrier. These reinforced composites, evaluated using the TOPSIS method, demonstrated their potential as high-performance materials combating heat transfer, offering a promising solution in the battle against climate change.

Development of Eggshell Waste Incorporated with a Porous Host as a Humidity Adsorption Material

The duck eggshell waste was developed to the novel desiccant that is friendly to human and environment.The calcium oxide(Ca O)and calcium chloride(CaCl_(2))as the calcium-based desiccants were prepared from eggshell waste.The Ca O desiccant derived from the eggshell waste sintering at 1300℃,while the CaCl_(2)desiccant was extracted from eggshell waste with the hydrochloric(HCl)solution at difierent concentrations from 5 to 30 wt%.The yield percentage of CaCl_(2)desiccant increased with increasing the HCl concentration to 25 wt%.The humidity adsorption behavior were investigated in the range of 75%-5%relative humidity.The results show the CaCl_(2)desiccant has the highest hydration rate.The porous host from the kaolin was sintered at different temperatures from 200 to 1000℃and incorporated with 30%w/v concentrations of CaCl_(2).The physical properties and the humid-adsorption capacity of all porous host conditions were investigated.The porous host at sintering temperature 800℃has the highest specific surface area.Moreover,the porous host at sintering temperature 800℃with the 30%w/v concentration of CaCl_(2)desiccant has the highest humid-adsorption capacity.

A Comparative Study of Different Drying Processes for a Deformable Saturated Porous Medium

Drying of a deformable saturated porous medium based on convective tempering is a novel method that can enhance energy efficiency and the quality of the dried product itself.In this experimental investigation,the performances of this specific technique are compared with those of a standard stationary drying process in terms of deformation,drying kinetics,moisture redistribution,and energy consumption.In particular,the response of a deformable saturated porous medium(Kaolin)is considered.The results are critically discussed pointing out advantages and drawbacks.

Developing Recipe from Local Ceramic Raw Materials for Making Crucibles in Ghana

The study experimented with using local ceramic raw materials (white clay, kaolin and silica or quartz) found in AssinFosu in the Central Region of Ghana to manufacture crucibles for melting metals and other precious minerals. Various physical tests were conducted on the materials to arrive at the body compositions. The compositions were also investigated for their elemental components by using X-ray fluorescence (XRF). The results revealed that the composition of Cruc containing 70% of white clay, 20% of kaolin, 8% of quartz and 2% of white grog;sintered at 1500˚C was very successful and therefore used to develop the recipe to manufacture the proposed crucibles. The “throwing” technique was employed to fabricate the crucibles. Test for thermal expansion was conducted for the manufactured crucibles at 1000˚C for thermal shock and microcracking tests. It was found out among others, that the recipe developed had very good physical and chemical properties of alumina silicate refractory materials and was fit for use at any high-temperature application. The study also recommended among others, that the researchers and institutions responsible for clay research such as Ghana Geological Survey Authority (GGSA) and Centre for Scientific and Industrial Research (CSIR) collaborate to improve upon this innovative idea.

Reaction behavior of ferric oxide in system Fe_2O_3-SiO_2-Al_2O_3 during reductive sintering process

Pure compounds and kaolin were employed to investigate the reaction behavior of ferric oxide in thetrinarysystem Fe2O3?SiO2?Al2O3 during reductive sintering process. The thermodynamic analyses and reductive sintering experimental results show that ferrous oxide generated from the reduction of ferric oxide by carbon can react with silicon dioxide and aluminum oxide to form ferrous silicate and hercynite at 1173 K, respectively. In the trinary system Fe2O3?SiO2?Al2O3, ferrous oxide obtained from ferric oxide reduction preferentially reacts with aluminum oxide to form hercynite, and the reaction of ferrous oxide with silicon dioxide occurs only when there is surplus ferrous oxide after the exhaustion of aluminum oxide. When sintering temperature rises to 1473 K, hercynite further reacts with silicon dioxide to form mullite and ferrous oxide. Results presented in this work may throw a new light upon the separation of alumina and silica present in Al/Fe-bearing materials with low mass ratio of alumina to silica in alumina production.

聚丁二酸丁二酯/聚(3-羟基丁酸酯-co-4-羟基丁酸酯)/纳米高岭土熔融共混力学性能、流变及降解行为研究

用熔融共混挤出法制备的聚丁二酸丁二酯(PBS)/聚(3-羟基丁酸酯-co-4-羟基丁酸酯)[poly(3HB-co-4HB)]/纳米高岭土(nano Kaolin)复合降解材料;利用万能拉力机、旋转流变仪和SEM对其力学性能、流变行为、微观结构及降解性能进行研究。结果表明,PBS/poly(3HB-co-4HB)/nano Kaolin(100/10/8)复合降解材料的缺口冲击强度、断裂伸长率达到最大,此后随着nano Kaolin质量百分比增加,而呈下降趋势;在室外自然条件下,经过土埋一段时间后的降解实验,PBS/poly(3HB-co-4HB)/nano Kaolin(100/10/12)复合材料发生了明显的降解,复合降解材料的失重率也已经降到64%左右,说明材料的降解性能较好;纳米复合降解材料熔融剪切储能模量(G′),剪切损耗模量(G″)随着频率的增大呈单增趋势。

实验性脊髓空洞MRI动态观察及演变分析

目的 :应用 MRI动态观察经皮枕大池穿刺注入 Kaolin诱导的家兔实验性脊髓空洞症模型 ,结合光镜、电镜组织学对比 ,对脊髓空洞症演变过程加以探讨。方法 :取中国白兔 32只 ,16只动物经皮枕大池穿刺注入 Kaolin制作动物模型 ,生理盐水组和假手术组 (各 8只 )作对照。术后行 MRI扫描并与光镜、电镜组织学对比。结果 :2周时 MRI发现上颈髓呈水肿、缺血性改变。 4～ 6周 ,90 %动物形成空洞。空洞随观察时间延长而逐渐增大且受累节段增多。组织学证实了 MRI发现。结论 :Kaolin性肉芽肿引起的上颈髓缺血、水肿和脑脊液循环障碍在脊髓空洞形成中发挥重要作用。其中 ,前者在髓内空洞进展中起主要作用 ,后者在中央管扩张中起主要作用。

银杏注射液防治实验性家兔脊髓空洞症的疗效评价

目的 :评价银杏注射液对枕大池注入 Kaolin诱导的家兔脊髓空洞症的防治作用。方法 :30只中国白兔随机分为 3组。在静脉麻醉下 2 4只动物经皮枕大池穿刺缓慢抽出 0 .6 ml脑脊液后注入等量 2 5 % kaolin;其中 12只于当日起给予银杏注射液静注 5 ml× 7日 ,为银杏组 ;12只以等量生理盐水静注 7天 ,为盐水组 ;6只动物仅作假穿刺和假注射为假手术组以作对照。术后定期行 MRI扫描并取 2周以内灌注的部分组织标本行细胞凋亡、bcl- 2及 bax等研究。结果 :注入 Kaolin后 3～ 16天 ,盐水组有 5只银杏组有 1只死亡。盐水组存活的 7只动物有 2只在 4周、 3只在 6周、 1只在 8周时出现上颈髓或颈胸段空洞 ;银杏组存活的 11只动物中只有 1只在 8周时出现上颈髓空洞。组织切片对比发现同一时间内银杏组组织水肿及神经元变性、坏死等均较盐水组为轻。盐水组神经元凋亡率、Bax反应阳性细胞率高于银杏组 ,而 Bcl- 2反应阳性细胞率低于银杏组。假手术组动物 MRI及组织学观察正常。结论 :银杏注射液可改善Kaolin性肉芽肿引起的上颈髓缺血水肿 。

m-HDPE/Kaolin复合材料流变性质研究

对比研究了采用聚合填充法(Polymerization-filling)和熔融共混法(meltcompounding)制备的m-HDPE/Kaolin复合材料的流变性质.动态流变实验和毛细管挤出实验的结果表明,聚合填充的HDPE/Kaolin复合体系的熔体动态粘度、复数粘度、表观粘度均低于熔融共混复合体系和纯HDPE的相应值.聚合填充的Kaolin粒子与PE分子链的强相互作用及其良好的分散状态,是改善材料流变行为的原因所在.

一种实验性脊髓空洞前状态动物模型的建立

目的:建立一种新西兰兔脊髓空洞前状态动物模型。方法:新西兰兔64只,随机分为Kaolin组、生理盐水组和假手术组,其中Kaolin组48只,经皮枕大池穿刺注入25%Kaolin混悬液0.6ml,分别于Kaolin注射后第1d、3d、7d、14d、21d、28d后常规行MRI观察后处死,取出上颈髓行组织学观察。结果:Kaolin组动物自Kaolin注入后3d出现缺血水肿(72.78±0.88%),7～14d达高峰(72.94±0.64%),21d减轻(70.21±0.49%);在T1WI表现为略低信号,T2WI为高信号且不能为FLAIR序列所抑制。至28d动物出现上颈髓空洞。结论:经皮枕大池Kaolin注射法可以制作出一种稳定性好、可重复率高的脊髓空洞前状态动物模型。

TGF-β1在脊髓空洞前状态的表达变化研究

目的用免疫组化技术动态观察新西兰白兔脊髓空洞症模型中TGF-β1的表达情况,探讨其在脊髓空洞前状态形成中的作用机制。方法将90只健康、体重1. 5～2 kg的新西兰白兔(雌雄不限),随机分为Kaolin组、0. 9%氯化钠溶液组和对照组,每组30只。于术后第1、3、7、10、14天后处死,迅速完整取出C1-2节段4 mm,置4%多聚甲醛后固定48 h,供TGF-β1免疫组织化学染色检查。用HPIAS-1000高清晰度彩色病理图文分析系统对TGF-β1阳性反应物积分光密度值(IOD)进行半定量检测,进行统计分析。结果 TGF-β1免疫组织化学检测发现,对照组和0. 9%氯化钠溶液组动物颈髓灰质和白质神经元及胶质细胞均有弱阳性表达。Kaolin组动物于术后第1天上颈髓组织神经元表达有明显升高,神经胶质细胞亦可见阳性表达,主要为胞浆表达;第3天、7天、10天在上颈髓灰质及白质神经元、神经胶质细胞呈强阳性表达,胞浆可见粗的棕黄色颗分布,以第10天最为显著。第14天则TGF-β1表达稍微减弱。0. 9%氯化钠溶液组和对照组TGF-β1表达的IOD测定差异无统计学意义(P> 0. 05); Kaolin组动物颈髓组织中TGF-β1表达与0. 9%氯化钠溶液组和对照组相比明显升高,其中以第10天最为显著(P <0. 01)。结论本实验结果显示在脊髓空洞形成早期,脊髓组织TGF-β1表达上调,提示其在脊髓空洞前状态病理生理形成过程中可能发挥重要作用。

湿法混炼对NBR/Kaolin复合材料溶胀行为的影响

分别采用湿法混炼和干法混炼制备了2种丁腈橡胶(NBR)/高岭土(Kaolin)复合材料(LNBRK与SNBRK),并采用未加填料的NBR0作为空白对照样,选择了4种酯类溶剂来研究NBR0、LNBRK和SNBRK的溶胀行为,通过扫描电镜(SEM)观察了LNBRK和SNBEK中Kaolin分布差异,计算了NBR0、LNBRK和SNBRK在4种溶剂中的最大溶胀比和摩尔吸收率,并进一步计算出4种酯类溶剂在NBR0、LNBRK和SNBRK中的扩散系数。结果表明,相对于SNBRK,LNBRK在酯类溶剂中的最大溶胀程度增大,而溶胀速度变慢,试样在酯类溶剂中的溶胀行为与溶剂分子碳原子数有较强的关联。

Adsorption of Cadmium by Soil Colloids and Minerals in Presence of Rhizobia

Experiments were conducted to study the adsorption of Cd on two soil colloids (red soil and yellow- brown soil) and three variable-charge minerals (goethite, noncrystalline Fe oxide and kaolin) in the absence and presence of rhizobia. The tested strain Rhizobium fredii C6, tolerant to 0.8 mmol L-1 Cd, was selected from 30 rhizobial strains. Results showed that the isotherms for the adsorption of Cd by examined soil colloids and minerals in the presence of rhizobia could be described by Langmuir equation. Within the range of the numbers of rhizobial cells studied, the amount of Cd adsorbed by each system increased with increasing rhizobial cells. Greater increases for the adsorption of Cd were found in red soil and kaolin systems. Rhizobia influence on the adsorption of Cd by examined soil colloids and minerals was different from that on the adsorption of Cu. The presence of rhizobia increased the adsorption sanity of soil colloids and minerals for Cd, particularly for the goethite and kaolin systems. The discrepancies in the influence of rhizobia on the adsorbability and affinity of selected soil colloids and minerals for Cd suggested the different interactions of rhizobia with various soil components. It is assumed that bacterial biomass plays an important role in controlling the mobility and bioavailability of Cd in soils with kaolinite and goethite as the major colloidal components, such as in variable-charge soil.

APPLICATION OF CLAYS TO REMOVAL OF RED TIDE ORGANISMS III. THE COAGULATION OF KAOLIN ON RED TIDE ORGANISMS*

This article reports studies on the coagulation of kaolin(from Wuxian, Jiangsu, China) on various red tide organisms, and the observation for the first time that the coagulation of kaolin is much greater than that of montmorillonite so that kaolin is a more effective clay for removing red tide organisms. The authors' theoretical explanation and analysis by a mathematical-physical model prove that compared to montmorillonite. kaolin has greater attraction for organism cells and therefore greater coagulation capabil-ity. This project's studies on the effects of pH and acid-treatment show that the acid-treatment does not have much influence on the kaolin system; whereas the effect of pH on the kaolin system is the same as that on the montmorillonite system.

Reaction behavior of kaolinite with ferric oxide during reduction roasting

The pre-separation of silica and alumina in aluminosilicates is of great significance for efficiently treating alumina-/ silica-bearing minerals for alumina production. In this work, the reaction behavior of kaolinite with ferric oxide during reduction roasting was investigated. The results of thermodynamic analyses and reduction roasting experiments show that ferrous oxide obtained from ferric oxide reduction preferentially reacts with alumina in kaolinite to form hercynite, meanwhile the silica in kaolinite is transformed into quartz solid solution and/or cristobalite solid solution. With increasing roasting temperature, fayalite formed by reaction of surplus ferrous oxide with silica at low temperature is reduced to silica and metallic iron in the presence of sufficient carbon dosage. However, increasing roasting temperature and decreasing Fe2O3/Al2O3 molar ratio favor mullite formation. The complete conversion of kaolinte into free silica and hercynite can be obtained by roasting raw meal of kaolin, ferric oxide and coal powder with Fe2O3/Al2O3/C molar ratio of 1.2:2.0:1.2 at 1373 K for 60 min. This work may facilitate the development of a technique for comprehensively utilizing silica and alumina in aluminosilicates.