Humidity Drying of Plastic Clay

The humidity drying cycle gives rise to surface and body cracks in plastic clay. The cracks appear in the initial stages when the clay is being heated in a saturated atmosphere. Various factors affecting cracking in this initial heating stage were studied using a purified kaolin in the plastic state, and appropriate experimental models were used to isolate certain aspects for study. It is shown that the condensation of moisture on the clay surface is the major factor influencing the cracking of the plastic clay. The effect of thermal diffusion is insignificant and the loss of mechanical strength is of secondary importance. The balance af evidence from the literature and from this study indicates that capillarity plays a major part in the movement of moisture and the production of stresses during drying. When air spaces are present in the body, thermal capillarity may become important. Stresses caused by thermal expansion oppose those caused by drying shrinkage, while the thermal expansion of capillaries will have a negligible effect.     

A Numerical Study of Transient Deformation and Stress Behavior of a Clay Slab During Drying

A transient three-dimensional analysis was carried out on internal strain-stress as well as heat and the moisture transfer in a ceramic slab during drying. A model was developed to analyze viscoelastic behavior, heat conduction and moisture diffusion. The basic equations were solved by the finite element method. The effects of several dimensionless parameters are discussed to find an optimum drying process and a precise design of molds in ceramic production. The stress and the gradient of moisture content were influenced significantly by the Biot or Lewis number. When the moisture diffusion is enhanced or the drying is controlled well so as to form only gentle gradients of moisture content in the slab, the maximum tensile stress can be reduced. Nonuniform drying results in the develoment of warp and increase in the maximum tensile stress. The drying characteristics were not appreciably influenced by shrinkage.     

Morphology,Rheological Properties,and Crystallization Behavior of Polypropylene/Clay Nanocomposites

Polypropylene/clay nanocomposites (PP/I.44P, PPCNs) were prepared in a twin-screw extruder using maleic anhydride grafted polypropylene (MAPP) as a compatibilizer. The intercalation of polypropylene into nanoclay particles was studied using X-ray diffraction. Rheological properties of the nanocomposites were investigated using a rheometer. The enhanced complex viscosity at low frequency regime indicated that the melt elasticity and melt strength of the nanocomposites were improved by adding nanoclay. The non-isothermal crystallization behavior of the nanocomposites was studied using differential scanning calorimetry (DSC) at various cooling rates and was analyzed with the Avrami method. It was found that the nanoclay acted as a heterogeneous nucleating agent resulted in higher crystallization temperature and higher crystallization rate than neat PP. Polarized optical microscopy revealed that the spherulites in the nanocomposites were finer than in the neat system.     

Drying Rates in Infrared Drying of Clay

Equations are presented showing the effect of ( a ) distance of lamp bank from drying surface, ( b ) thickness of material, ( c ) absorptivity of the material, ( d ) intensity of radiation, and ( e ) humidity on the drying rate of clay. The equations were developed by graphical methods and it was found that the drying rate was a linear function of intensity of radiation and absorptivity of clay and a power function of thickness and distance of lamps from the drying surface. Infrared drying was independent of humidity below an absolute humidity of 71%.     

纳米黏土增强材料研究

玉山蒙脱土经提纯、钠化和有机插层处理后制得纳米黏土,阳离子交换容量为114 mmol/100 g土,晶层间距由1.238 nm增大到2.090 nm。采用挤水转相技术,以酯类为有机相置换纳米黏土中的水相,且m(有机相)∶m[纳米黏土(干土)]=100∶30,可防止纳米黏土的二次团聚,获得颗粒高度分散的纳米黏土增强材料。纳米黏土增强树脂的最佳质量分数为m(树脂)∶m(纳米黏土)=100∶5,用于环氧树脂时,冲击强度可提高302.3%,弯曲强度提高45.5%;用于聚丙烯树脂时,冲击强度提高35.7%。     

Spray Drying of Skim Milk Mixed with Milk Permeate: Effect on Drying Behavior,Physicochemical Properties,and Storage Stability of Powder

The possibility of using milk permeate (MP) to lower the protein level of skim milk powder (SMP) in producing powders of 34% and lower protein is explored. Skim milk suspensions with various levels of MP were prepared by mixing SMP and MP powder (MPP) at the ratios of 1:0, 7:3, 3:7, and 0:1: from 34 to 5.3% protein. The suspensions were dried in a spray dryer with inlet and outlet temperatures of 180 and 80°C, respectively. Increasing permeate concentration in the mixture showed a greater tendency to stickiness manifested by lowered the cyclone recovery of the powder as more powder stuck on the wall of the dryer. Increasing permeate concentration in the resultant powder did not significantly affect the bulk density but led to a reduction in the particle size and also made the powder slight green and yellowish in color. It also found to lower the glass transition temperature (T_g ) of the skim milk powder (SMP) and induce crystallization of lactose at lower water activity (a_w  ≥ 0.328 for SMP:MPP of 3:7 and 0:1 compared to a_w  ≥ 0.0.432 for SMP:MPP of 1:0 and 3:7). Addition of MP in SMP lowered the T_g values of the resulting powders. The permeate fraction in spray-dried SMP/MPP mixtures found to lower the critical a_w and moisture content, suggesting the SMP mixed with MPP is more likely to become sticky than SMP alone (at 34% protein) when stored at a similar water activity and moisture content.     

Spray Drying of Skim Milk Mixed with Milk Permeate: Effect on Drying Behavior, Physicochemical Properties, and Storage Stability of Powder

The possibility of using milk permeate (MP) to lower the protein level of skim milk powder (SMP) in producing powders of 34% and lower protein is explored. Skim milk suspensions with various levels of MP were prepared by mixing SMP and MP powder (MPP) at the ratios of 1:0, 7:3, 3:7, and 0:1: from 34 to 5.3% protein. The suspensions were dried in a spray dryer with inlet and outlet temperatures of 180 and 80°C, respectively. Increasing permeate concentration in the mixture showed a greater tendency to stickiness manifested by lowered the cyclone recovery of the powder as more powder stuck on the wall of the dryer. Increasing permeate concentration in the resultant powder did not significantly affect the bulk density but led to a reduction in the particle size and also made the powder slight green and yellowish in color. It also found to lower the glass transition temperature (T_g) of the skim milk powder (SMP) and induce crystallization of lactose at lower water activity (a_w ≥ 0.328 for SMP:MPP of 3:7 and 0:1 compared to a_w ≥ 0.0.432 for SMP:MPP of 1:0 and 3:7). Addition of MP in SMP lowered the T_g values of the resulting powders. The permeate fraction in spray-dried SMP/MPP mixtures found to lower the critical a_w and moisture content, suggesting the SMP mixed with MPP is more likely to become sticky than SMP alone (at 34% protein) when stored at a similar water activity and moisture content.     

Properties of Calcined Clay Waste and its Influence on Blended Cement Behavior

This paper describes research on clay wastes (CWs) produced in the paper manufacture process. Once activated under controlled thermal conditions, CW is transformed into calcined clay products providing added value as supplementary cementing materials. The obtention of a pozzolanic material (metakaolin (MK)) from valorized CW constitutes an alternative source of pozzolans for the elaboration of blended Portland cements, as well as a priority research line from the environmental point of view. This research work presents the properties of calcined CW (chemical, mineralogical, and pozzolanic) and its influence on Portland cements containing 10% calcined clay product. The results obtained with different characterization techniques (XRF, DTA, XRD, SEM-EDX) showed that the thermally activated CW exhibits acceptable properties to be used as supplementary cementing materials in the manufacture of commercial Portland cements. The derived MK can react with calcium hydroxide, from cement hydration, producing hydrated phases with hydraulic properties (calcium silicate hydrate gels, tobermorite, C₄AH₁₃, zeolite). These novel blended cements comply with the chemical, physical, and mechanical specifications established in the existing standards.     

孝义铝土矿区半软质粘土烧结性研究

通过全面分析研究孝义铝土矿区半软质粘土的矿物构成和化学成份，证明该矿物属含有少量多水高岑石的高岑石型半软质粘土。根据矿物的性质制定出矿物原料的成型、煅烧工艺。实验表明：该矿物的烧结性与煅烧温度关系密切，且烧结温度范围较窄，是良好的陶瓷及耐火材料原料。     

CHT作为粘土稳定剂的性能研究

实验测定了3-氯-2-羟丙基三甲基铵氯化物（CHT）作为粘土稳定剂的某些性能。作为粘土稳定剂,防膨剂CHT的防膨性能与油田常用的防膨剂相比,明显高于其他几种防膨剂,表现出了良好的防膨性能。CHT含量在溶液中应在0.1%及以上。并具有良好的耐冲刷性能。XRD实验中,当CHT的吸附量由0逐步增大到0.46mm ot/g时,钙蒙脱土的晶层间距由1.5713nm逐渐减小到1.4122nm,表明CHT作为粘土稳定剂,可以有效的抑制粘土矿物的膨胀。作为粘土稳定剂,CHT可用于油气储层防膨处理及阳离子聚合物驱油前的地层预处理。     

清洁燃料-乙醇柴油基本特性的研究

考察了乙醇柴油的基本性能,经研究发现,柴油中加入一定量的乙醇后,存在互溶性变差、燃烧性变差、腐蚀性增加、润滑性变差等问题,因此建议采用添加剂技术改善其性能以满足发动机的使用要求。     

作为非塑性材料的砂对粘土砖陶瓷性能的影响

研究了砂作为代替品用于粘土砖中对粘土砖的物理-机械性能及陶瓷性能的影响。砂作为代替品用于粘土砖中,最大量可达20%。将坯体成型、干燥,然后在不同温度下烧结直到1000℃,浸渍2h。结果显示,用于粘土砖中的砂可以将干燥控制在较短时间内,改进了干燥和烧结收缩、体积密度、显气孔率和抗压强度。含有10%砂的配料显示出最好的结果,因此选择作为最佳配料用于制备粘土砖。     

Powder Properties and System Behavior during Spray Drying of Bauhinia forficata Link Extract

This article presents a study of the effects of the spray-drying conditions on product properties and dryer performance during manufacture of dried extracts of Bauhinia forficata. The product properties (loss on drying of the dried extract, flavonoids degradation ratio, product size distribution, bulk and loose densities, powder morphology) and the equipment performance were determined as a function of the input parameters (dryer inlet temperature, ratio between the feed flow rate of the extract to the dryer evaporation capacity, and feed flow rate of the drying gas). Regression equations correlating powder characteristics and dryer behavior to input process parameters were obtained. The results demonstrate significant impact of the processing conditions on product properties and dryer performance. The loss on drying is a key property, since low values are demanded for the acceptance of the dried extract. In general, due to strict product specifications, the drying conditions that give an end product with the required quality are not associated with the optimal drying performance.     

Powder Properties and System Behavior during Spray Drying of Bauhinia forficata Link Extract

This article presents a study of the effects of the spray-drying conditions on product properties and dryer performance during manufacture of dried extracts of Bauhinia forficata. The product properties (loss on drying of the dried extract, flavonoids degradation ratio, product size distribution, bulk and loose densities, powder morphology) and the equipment performance were determined as a function of the input parameters (dryer inlet temperature, ratio between the feed flow rate of the extract to the dryer evaporation capacity, and feed flow rate of the drying gas). Regression equations correlating powder characteristics and dryer behavior to input process parameters were obtained. The results demonstrate significant impact of the processing conditions on product properties and dryer performance. The loss on drying is a key property, since low values are demanded for the acceptance of the dried extract. In general, due to strict product specifications, the drying conditions that give an end product with the required quality are not associated with the optimal drying performance.     

Effect of Heat Treatment Temperature on Properties of Chinese Calcined Flint Clay Based Plastic Refractories

Effects of different heat treatment temperatures on properties of Chinese calcined flint clay based plastic refractories were investigated using Chinese calcined flint clay as starting material,aluminum sulfate and fireclay as binding system.The results showed that with temperature rising,Chinese calcined flint clay based plastic refractories shrinked firstly and then expanded.The modulus of rupture (MOR) and the cold crushing strength (CCS) increased firstly and then decreased from 110 ℃ to 600 ℃,then increased obviously.Thermal expansion coefficient increased from 110 ℃ to 760 ℃,decreased from 760 ℃ to 1 300 ℃,and increased from 1 300 ℃ to 1 500 ℃.     

Granulation and Drying of Modified Clay Incorporated Pesticide Formulation

The extensive use of chemicals in agriculture, in particular herbicides, is a serious environmental concern. There is an urgent need to develop smart herbicide formulations that combine both optimum bioactivity and minimum dosages. In the current article, an attempt has been made to design the formulation based on one of the most widely used herbicide, Atrazine (AT). This potent herbicide along with “China clay” as the carrier and suitable clay modifiers can be thought as one of the potential way of formulation keeping in view the desired dosage and bioavailability of the same. The China clay was subjected to modification using a surfactant blend of alpha olefinic sulphonate (AOS) and alkyl polyglucosides (APG). The intercalation of the surfactant into the clay was confirmed by XRD and FTIR and the morphology was studied by SEM. The process of granule formulation and the drying was carried out using rapid mix granulator and the fluidized-bed dryer, respectively, at the desired conditions of temperature and relative humidity. These granules were then compared on the basis of key parameters such as dissolution rate, dispersion stability, and other physical properties such as bulk density, angle of repose, and particle size distribution. The study reveals the desired effect of clay modifications on the granules in terms of above-mentioned quality parameters.     

聚环氧氯丙烷-二甲胺粘土稳定剂合成及其防膨性能评价

文章采用环氧氯丙烷和二甲胺为原料,采用交联聚合法进行聚合,合成了聚环氧氯丙烷-二甲胺粘土稳定剂,探讨了合成条件并评价了粘土稳定剂的防膨性能。确定聚环氧氯丙烷-二甲胺的最佳合成条件为:反应温度70℃,反应时间5h以上,n(环氧氯丙烷):n(二甲胺)=1.5:1,n(乙二胺):n(环氧氯丙烷+二甲胺)=3%。该粘土稳定剂防止粘土膨胀性能良好,防膨率达到90.3%。     

橡塑保温产品热解行为的研究

采用热重—傅立叶变换红外光谱(TGA-FTIR)联用技术研究了氧气气氛下橡塑保温产品的热解和燃烧行为。结果表明,材料TGA曲线有两个失重阶段,第一失重阶段是材料中NBR和PVC官能团的热氧降解,主要生成CO2、H2O、HCl及氰酸等气体逸出;第二阶段是材料中碳链受热燃烧,生成CO2逸出。