Recycling detoxified cement asbestos slates in the production of ceramic sanitary wares

The recycling of cement asbestos slates (CASs) thermally treated in air at 1100 °C as secondary raw material in the production of Vitreous China (VC) sanitary wares has been investigated. Deactivated cement asbestos powder (DCAP) has been used in individual substitutions (5 wt%) of quartz and feldspar. The single raw materials, the ceramic technological properties before and after firing, and the phases and microstructure evolution during firing have been investigated with a variety of techniques, including those commonly used for production quality checks and instrumental methods for mineralogical analyses. DCAP acts as flux rather than as inert in the firing process, promoting greification. Although the substituted samples have some critical aspects that need to be addressed before processing, such as the presence of sulphate salts that increase the dispersant demand and the colour of the fired ceramic body, the overall technological properties are comparable to those of normal production, suggesting the possible reuse of DCAP powder in the production of sanitary wares.     

国外石棉水泥制品工艺设备及发展趋势

本文介绍了国外石棉水泥制品的品种、用途、新工艺、新设备及发展趋势。     

Evaluation of permeation of organic solvents through PVC,asbestos/cement,and ductile iron pipes

Buried potable waterpipes are susceptible to permeation by organic solvents. In studying piping made of PVC, asbestos/cement, and ductile iron, full-pipe assemblies and laboratory bench techniques were employed. Elastomeric gaskets for all three systems become permeated, at least under exaggerated conditions. Results show that thermodynamic activity, as opposed to concentration, is the driving force. At solvent activities well above those encountered in typical soil, PVC is seen to be an effective barrier against permeation.     

Fabrication of highly isotactic polypropylene fibers to substitute asbestos in reinforced cement composites and analysis of the fiber formation mechanism

Highly isotactic polypropylene (PP) is currently studied as a cement‐reinforcement fiber that could potentially be substituted for asbestos because of its resistance to prolonged high‐temperature curing. The higher the isotacticity of the PP fiber is, the higher the tensile modulus and breaking strength of the cured fiber are. The PP fiber that exhibits a isotacticity of 99.6% (XI) and draw ratio of 6.0 retains a tensile modulus of 4.23 GPa, even after high‐temperature curing at 175°C for 5 h. PP fiber is cut into 6‐mm lengths and dispersed throughout a cement mixture to prepare a reinforced cement composite. The mixture is cured in an autoclave at 175°C for 5 h. The Charpy impact strength and flexural strength of the obtained cement composite tends to increase with increasing PP isotacticity. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 981‐988, 2013     

预处理对石棉尾矿酸浸反应效果的影响

提高石棉尾矿与酸的反应效果是提高利用石棉尾矿制备氢氧化镁和二氧化硅产率的重要途径.本文就石棉尾矿的预处理对石棉尾矿与酸反应效果的影响进行了研究.采用的预处理方法有:将石棉尾矿在700℃下煅烧、超细研磨、浮选提纯等,以预处理后的石棉尾矿与酸反应后的残渣质量作为评价指标.结果表明:预处理没有达到提高石棉尾矿酸浸效果的目的.文中对产生这一结果的原因进行了讨论.     

Polyvinylpyridine-divinylbenzene and asbestos composites

The in situ copolymerization of vinylpyridine and divinylbenzene in crysotile asbestos cardboards yields composites of higher mechanical strength and chemical stability than plain carboard. The composites have been tested as gasket rings and separators of advanced alkaline water electrolysers. The chemical and morphological changes to which the materials are subjected under these conditions have been followed up by i.r. spectroscopy and SEM and correlated with chemico-physical properties.     

国产石棉绒的应用分析

介绍三门峡天成电化有限公司隔膜电解槽用石棉绒经历的国产石棉绒一进口石棉绒一国产石棉绒的过程。实际运行表明,每台电解槽的国产石棉绒用量为20kg,比进口石棉绒少8kg;总管氯中氢体积分数也由1．5％左右降至0．5％。     

化妆品中石棉检测方法的研究

本文采用X射线衍射和扫描电镜联合分析法来检测化妆品中的石棉,该方法检测石棉用样量小,重现性好,快速有效,特别适用于粉状化妆品中石棉检测,为产品的质量监督提供了可靠的方案。     

Hollow shell hydration of cement particles in bulk cement paste

Investigations on bulk cement paste specimens made from different cements confirm the occurrence of hollow-shell or “Hadley grains”, similar to those previously established as occurring near interfaces with glass slides. The existence of such grains in previous microstructural investigations of cement pastes has apparently been overlooked. Since few grains in bulk cement pastes fracture to reveal details of their interiors, the relative frequency of occurrence of hollow-shell grains and grains showing inner hydration product in contact with the exterior shell can not be assessed unambiguously, but almost all fractured grains observed seem to be of the hollow-shell variety.     

Influence of polymer on cement hydration in SBR-modified cement pastes

The influence of styrene-butadiene rubber (SBR) latex on cement hydrates Ca(OH)₂, ettringite, C₄AH₁₃ and C-S-H gel and the degree of cement hydration is studied by means of several measure methods. The results of DSC and XRD show that the Ca(OH)₂ content in wet-cured SBR-modified cement pastes increases with polymer-cement ratio (P/C) and reaches a maximum when P/C is 5%, 10% and 10% for the pastes hydrated for 3 d, 7 d and 28 d, respectively. With wet cure, appropriate addition of SBR promotes the hydration of cement, while the effect of SBR on the content of Ca(OH)₂ and the degree of cement hydration is not remarkable in mixed-cured SBR-modified cement pastes. XRD results illustrate that SBR accelerates the reaction of calcium aluminate with gypsum, and thus enhances the formation and stability of the ettringite and inhibits the formation of C₄AH₁₃. The structure of aluminum-oxide and silicon-oxide polyhedron is characterized by ²⁷Al and ²⁹Si solid state NMR spectrum method, which shows that tetrahedron and octahedron are the main forms of aluminum-oxide polyhedrons in SBR-modified cement pastes. There are only [SiO₄]⁴⁻ tetrahedron monomer and dimer in the modified pastes hydrated for 3 d, but there appears three-tetrahedron polymer in the modified pastes hydrated for 28 d. The effect of low SBR dosage on the structure of aluminum-oxide and silicon-oxide polyhedron is slight. However, the combination of Al³⁺ with [SiO₄]⁴⁻ is restrained when P/C is above 15%, and the structure of Al³⁺ is changed obviously. Meantime, the polymerization of the [SiO₄]⁴⁻ tetrahedron in C-S-H gel is controlled.     

Polymer encapsulation of colloidal asbestos fibrils

The free-radical polymerization of several monomers in an aqueous suspension containing chemically opened chrysotile asbestos fibrils was investigated with the intention of promoting complete encapsulation of the individual colloidal fibrils. The degree of polymer deposition on the colloidal substrate is dependent upon several factors including monomer and polymer solubility, initiator type, ionic comonomers, and degree of interfacial wetting. Successful encapsulation was achieved by the addition of novel unsaturated polyelectrolytes which served a dual role as dispersing agent and comonomer. Such methods are useful for the preparation of reinforced composites with controlled interfacial properties. In one example, it is shown that asbestos fibrils surrounded by a rubbery layer can impart greater toughness to a reinforced composite, compared to a composite in which the rubbery phase is dispersed at random or isolated from the interface. The technique can be extended to other types of fillers. The various methods of chemically “opening” asbestos are summarized.     

Dielectric characterization of UICC asbestos samples

The frequency dispersion of the dielectric coefficient and of the dielectric loss measured on suspensions of asbestos fibers in paraffin oil as functions of fiber concentration and temperature showed for Canadian chrysotile relatively large energy dissipation maxima which can be explained in terms of relaxation of transverse and longitudinal polarization with slightly different energies of activation. Amosite fibers, in contrast, were found to be dielectrically inactive compared with the large-scale effects exhibited by chrysotile. Chrysotile suspensions were slightly thixotropic at volume concentations of the fibers as low as 0.5%, while the amosite suspensions did not show thixotropic behavior up to fiber concentrations of 1.0 vol.%.     

浅谈希普CGA型助磨剂在水泥粉磨中的应用

0前言新疆阿克苏多浪水泥有限公司(简称多浪公司)属于新疆天山水泥股份有限公司的控股子公司,地处新疆的中部。多浪水泥公司年产65万t“多浪牌”各品种水泥,供应阿克苏市及周边市场。由于品质优良,售后服务周到,深得用户的青睐,销售一直很好。为了进一步降低成本、提高磨机台产,我们在多浪公司2台覫2.6m×13m开流水泥磨机上进行水泥助磨剂应用,使用了引进美国希普公司技术生产的C GA—1D D型水泥助磨剂生产32.5级普通水泥、52.5级普通水泥两个品种,达到了提高水泥磨机台产效果。通过2002年～2004年两年多的水泥助磨剂应用,公司取得了较好…     

The drag reduction of chrysotile asbestos dispersions

The drag reduction (DR) of dispersions of Chrysotile asbestos fibers in aqueous solutions of Aerosol OT and in ethylene glycol, and of glass microfibers in water at a pH of 3 were studied as a function of concentration and temperature with a rotating disc apparatus. Only the dispersions of asbestos in aqueous Aerosol OT showed DR comparable to poly(ethylene oxide) WSR 35 (～500,000 MW), and these dispersions were more fully studied. As was the case with Polyox WSR 35, the asbestos dispersions achieved maximum DR at a concentration of about 200 ppm. They showed no DR temperature dependence at constant Reynolds number at high concentrations but displayed a decreasing DR with increasing temperatures at low concentrations. However, the temperature effect was much smaller for the asbestos dispersions than for Polyox. The asbestos dispersions also showed a much smaller decrease of DR with time at a given disc rotation than was previously measured for poly(ethylene oxide). Electron microscope evidence indicated that less than 10% of the fibers were fully separated, and it is probable that these were the fibers which were primarily active in DR. Hence, if complete separation and dispersion could be accomplished without breaking the fibers, Chrysotile asbestos would be a most potent, not very shear-degradable DR species.     

硫铝酸盐水泥与硅酸盐水泥复配性能研究

基于硫铝酸盐水泥、硅酸盐水泥各自的特点,研究了二者复配后的标准稠度用水量、凝结时间、水化热效应、胶砂强度、膨胀性、水化产物的物相及微观形貌。结果表明,复配水泥的标准稠度用水量因复配比例不同而变化,凝结时间相对于占主导地位的单组分水泥明显缩短;复配水泥的早期水化速率得到提高,1d、7d的水化放热量均低于占主导地位的单组分水泥;28d抗压、抗折强度低于任何单组分水泥;膨胀性的大小取决于两种水泥的复配比例;硫铝酸盐水泥与硅酸盐水泥的复配使二者的水化相互促进,随着硫铝酸盐水泥掺量的增加,Ca(OH)2相的衍射峰减弱,AFt相的衍射峰增强;纯硅酸盐水泥水化后的微观形貌是致密的,而与硫铝酸盐水泥复配后则出现微观裂纹。     

Evaluation of asbestos composite separators in advanced water test electrolysers

Work performed at Milan Politecnico under sponsorship by the Commission of European Communities and in cooperation with international institutions involved in hydrogen energy programs in the last decade is surveyed. The performance of composite separators made from various linear, cross-linked and sulphonated aromatic polymers and asbestos cardboards or cloth from various sources is reported in medium temperature (95–125°C) alkaline (40–50% KOH) water electrolysers having different configurations. The results are interpreted based on knowledge of the separator structures and properties.     

白色硅酸盐水泥质量统计比对

一般水泥厂均以28d龄期的强度值为其水泥质量标志向用户承诺而印在出厂的包装袋上，由于生产条件限制，水泥厂不太可能将生产的所有水泥都库存到28d后判断其强度是否合格再出厂。但人们可以利用水泥早期强度与28d强度间相关性规律，提出7d或3d强度的控制值，以预估28d强度可否达到预期的强度等级，从而提前出厂，这给生产和使用双方均带来极大方便。