陶瓷食品包装材料有害重金属迁移研究进展

食品接触材料尤其塑料和纸制品中有毒有害化学物向食品的迁移是近年来国内外研究的热点,美国FDA和欧盟及其成员国等均就相关问题开展了广泛而深入的研究,并取得了一系列重要成果,成为许多标准和法令法规制定颁布的依据。对于陶瓷制品,相比较而言国内外更多关注的是重金属铅和镉的溶出限量,而对它们及其他重金属向食品的迁移研究较少,本文就相关内容作介绍。     

Influence of fine ceramic aggregates on the residual properties of concrete subjected to elevated temperature

The residual properties of concrete subjected to elevated temperature are of importance to assess the stability of the structure. This paper investigates the performance of concrete containing white ware ceramic sand exposed to elevated temperature. Concrete mixes containing 0%, 50%, and 100% ceramic sand were prepared. The specimen were exposed to elevated temperatures of 200°C, 500°C, and 800°C for a duration of 60 minutes. Their residual mechanical properties (compressive strength, split tensile strength), ultra sonic pulse velocity, and mass change for different cooling regimes were investigated and compared among specimen. The results showed that incorporation of ceramic sand in concrete mixes improved the resistance against elevated temperature of hardened concrete.     

无人机叶片特殊三次脱模机构简化型模具设计

针对无人机叶片塑件的叶片部分和榫台部分形状特殊,脱模困难的模具设计难题,首先运用CAE分析确定了其成型浇注方案;而后,在两种脱模方案对比分析的基础上,选用并设计了一种简化型两板模具来对其进行注塑成型,有效地降低了模具制造成本。模具中,塑件的叶片部分采用简化型两板模的主体成型件来进行成型,保证了叶片的成型质量。塑件的榫台部分,则采用一种新型的三次脱模机构来对其进行成型和脱模,机构由两个子机构组成,一个是活动座板机构,一个是滑块顶杆复合机构;机构脱模时,利用模具的开模动力来实施第一次脱模,利用油缸驱动T型块形式先驱动侧面滑块进行第二次侧抽芯脱模,利用油缸的继续顶出驱动顶针将塑件从侧边型芯是上完全顶出脱模。机构设计巧妙,模具结构简单,能有效降低模具的加工制造成本。     

有序多孔陶瓷的功能化组装

以多孔陶瓷为过滤元件的陶瓷过滤器,已在化工和冶金等领域得到广泛的应用,尤其在含有重金属离子的废水处理中具有非常广阔的前景.本实验主要研究了以硅藻土、活性炭和硅溶胶作为组装原料,对有序多孔陶瓷材料进行功能组装.实验结果表明:在功能组装过程中,活性炭和硅藻土填充效果一般;活性炭浓度为10%的组装效果较为理想,而硅藻土浓度为...     

新型耐高温耐腐蚀涂层材料——陶瓷塑料

所介绍的陶瓷塑料,既具有陶瓷耐高温、耐腐蚀及高强度的性能,又具有塑料的良好可塑性和粘结性能,并且陶瓷塑料还与各种材料（包括金属）有良好的附着性。     

Neuere Entwicklungen bei Härtbaren Formmassen. Werkstoffe – Anwendungen – Verarbeitungs-Technologien

New developments in thermosetting moulding compounds – Materials – Applications – Processing technology . Thermosetting moulding compounds are defined as raw materials manufacturing plastic parts under the influence of pressure and heat, mainly by compression, transfer and injection moulding which are formulated in workable form from thermosetting reactive resins, fillers, reinforcers, and other additives. The present article will consider only moulding compounds in granular form whose processing to moulded parts is mainly automated and which represent a group of plastics clearly distinct from pasty or liquid thermosetting moulding materials.     

Rheological properties of carbon mixes at very low shear rates using a capillary rheometer—III

A capillary rheometer has been used to determine the rheological properties of carbon mixes consisting of petroleum coke as filler and coal tar pitch as binder. It is shown that carbon mixes behave as Bingham materials with definite yield stresses. The yield stress was found to be a general property of all carbon mixes and its value is independent of the size of the capillary die. It was also seen that extrusion at low shear rates through big diameter capillaries results in slipflow. The slipflow occurs when the applied stress is somewhat below the yield stress, the material then extrudes without the formation of a core which otherwise would cause cracks in the product after baking. This explains why big diameter rods are generally extruded at very low speeds in usual manufacturing process. The modified Buckingham-Reiner equation has been applied to the case of slipflow and the values of yield stress and plastic viscosity calculated. These values agree well with those obtained from the consistency curve.     

Orimulsion fly ash in clay bricks—part 3: chemical stability of ash-bearing products

The chemical stability of clay bricks containing Orimulsion ash (up to 6 wt.%) was assessed with a laboratory simulation of the brickmaking process. The development of efflorescence, the amount of water soluble salts and their elution, the fraction of S, V, Ni, Mg, Ca, Na and K immobilized in the ceramic matrix, and the amount of volatile elements potentially released during firing were determined by ICP–OES, XRPD, TGA, SEM and EMP analyses. The stabilizing mechanism acts through the capture of metals into the crystalline structure of silicates formed at high temperature. However, the firing conditions adopted in the brick industry (about 900 °C) do not permit the complete reaction of sulphates; there is considerable efflorescence and soluble salts are formed, even with 1.5% of ash added, producing a risk of sulphate attack to the mortars. On the other hand, the decompostion of sulphates during firing could bring about remarkable SO_x emissions, particularly in carbonate-free bodies. In conclusion, the disposal of Orimulsion ash in clay bricks must be practiced with caution and an amount of ash below 1 wt.% weight is strongly recommended.     

Utilization of wastewater precipitates from Tanneries in production of construction ceramics

Ceramic samples were obtained from the mixtures containing sewage precipitate from Ryazan’ Tannery, clay from a local brick factory, and basic slag from Ryazan’ Metallurgical Plant. The sample properties (compressive strength, acid resistance, and alkali resistance) as well as the presence of heavy metals in the solutions after testing were determined. The mixtures containing the precipitate reliably bind heavy metals and are promising for utilization of tannery waste in production of ceramic wall materials. The processes occurring in sintering of the samples are explained.     

重金属污染土壤回转窑协同处置和资源化利用

在中国,土壤中的重金属污染问题形势严峻,本文探索了一条采用先将重金属污染土壤中铅、镉、铜、锌固定再利用回转窑协同处置并资源化利用的技术途径。实验发现：添加适量的凹土及稳定化试剂并经稳定化处理以后,可以实现污染土壤由危险废物向一般固废的转变;进一步将稳定化处理后的土壤采用回转窑深度加工、能生产得到安全指标和产品性能合格的陶粒。经过优化实验方案后的结果显示,在铅、镉、铜、锌等重金属初始含量（上限）为2280mg/kg、592mg/kg、2000mg/kg、93400mg/kg的污染土壤添加4%的凹土（质量分数）及其他辅助材料后稳定化48h,上述重金属的可溶态检出量分别降低了50%、66%、59%、52%,经治理后的土壤可以转变为一般固废。用这种固定化处理后的土壤可以生产出合格的陶粒,而且在陶粒生产过程中逸散排放的铅、镉含量均低于大气污染物排放限制要求。     

Toxic Species Emissions from Controlled Combustion of Selected Rubber and Plastic Consumer Products

The main objective of this research is to identify the principal toxic species, either airborne or ash phase, expected to be released to the environment when selected plastics or rubberized materials undergo controlled combustion. The results are indicative of what can occur in municipal incinerators, in residential or industrial fires, or in open-air burning of waste materials in areas that are not serviced by trash pickup. The current emphasis is on materials used by the shoe manufacturing industry, especially rubber and plastic-type materials. The results are compared to those obtained during the combustion of a vehicle rubber tire, which was adopted as an arbitrary standard for comparison because of its current importance in recycling efforts. In addition, a comparison is made with the published results on a related topic dealing mainly with polyvinylchloride plastics. Highly toxic gases such as hydrocyanic acid, sulfur dioxide, and hydrogen chloride were among the main substances found during gas colorimetric testing. More than 92% of the particulate mass was found to be in the respirable range (i.e., less than 10 μm in size as based on cascade impactor analysis). In addition, toxic heavy metals, such as lead, chromium, and antimony, were detected in the smoke and ash phases of some of the materials. One of the materials analyzed (USA rubberized sole) was found to generate more hazardous gaseous contaminants (hydrogen chloride in both the smoke and ash phases, in addition to hydrocyanic acid and sulfur dioxide) than the rubber arbitrary standard. This result is suggestive of the need for additional studies with a larger sampling base. Should future studies show a similar trend, then recycling efforts to collect the huge amount of rubber and plastic that is discarded every year as harmless waste in the form of footwear would seem to be in order.     

固体废物焚烧灰渣毒性评估及其控制方法研究进展

固体废物焚烧产生的灰渣时环境是一种二次污染物,其中,焚烧飞灰因其含有重金属及有毒有机污染物而被列为危险固体废物,因此在其最终处置前,必须进行稳定化处理.作者介绍了灰渣的污染特性,尤其是飞灰中所含重金属、有毒有机污染物的毒性及其各种评估方法,包括水平震荡法、浸出柱实验法、毒性浸出程序(TCLP),并综述了当前灰渣的控制技术方法和资源化利用手段,如水泥固化法、熔融固化法、化学药剂固化法.     

Fabrication of coloured zirconia ceramics by infiltrating water debound injection moulded green body

Abstract

Abstract

The authors developed a new technique combining ceramic injection moulding and liquid precursor infiltration, presenting a new strategy for fabrication of coloured zirconia ceramics. The authors’ strategy includes ceramic injection moulding 3Y‐TZP powder using a water debinding binder system, debinding moulded parts in water and drying, immersing debound parts in solutions containing different colouring ions and then sintering and creating coloured zirconia ceramics. The fabricated coloured ceramic bars exhibit a core shell structure, and the thickness of the coloured shell can be tailored by adjusting immersion time and temperature. Using solutions containing different colouring ions, ceramic bars with various colours can be prepared.     

Impact of powder morphology on quality of low-pressure injection moulded reaction-bonded net shape oxide ceramics

Low-pressure injection moulding is a very efficient process for net shape manufacturing of ceramic micro parts. In order to obtain sintered ceramic specimens without shape distortion or damages, density gradients in the green bodies have to be avoided. Especially feedstocks with a solid loading near the critical powder volume content often tend to segregate the binder while flowing. However, the value of critical powder content can be significantly influenced by particle size, particle size distribution and particle morphology. This paper compares two powder mixtures of identical chemical compositions with different specific surfaces and morphology and evaluates their workability for low-pressure injection moulding. The aim of this paper is to identify the influence of morphology on feedstock rheology as well as on accuracy, mechanical properties and microstructure of net shape manufactured reaction-bonded zircon ceramics.     

水泥窑协同处置危险废物过程中重金属固化的问题研究进展

本文对水泥窑协同处置废弃物过程中,重金属固化机理以及相关影响因素的研究进行综述分析,结果表明:水泥生产过程中存在生料窑灰冷凝吸附、熟料晶格固溶以及水化凝胶吸附交换的作用机理,可确保危险废物中重金属有效固化;同时,可通过调控影响重金属固化效果的相关因素,减少重金属的挥发迁移,降低对生态环境造成污染和破坏的可能性。     

Dense glass-ceramics by fast sinter-crystallization of mixtures of waste-derived glasses

Dense glass-ceramics were obtained by cold pressing and sinter-crystallization of a glass originated from the plasma gasification of municipal solid waste (“Plasmastone”) mixed with recycled soda-lime glass and kaolin clay. The optimum mixture featured 45% Plasmastone/45% soda-lime glass/10% kaolin clay and it was sintered according to a fast heat treatment (30 minutes at 1000°C with heating and cooling rates of approximately 40°C/min), mimicking that of industrial ceramic tiles. The fast treatment avoided extensive crystallization during heating, promoting the viscous flow. In this way, dense glass-ceramics with a water absorption below 0.7% could be produced. The developed tiles presented mechanical properties comparable to those of commercial ceramic tiles. Finally, the environmental impact assessment performed on these materials showed that the leaching of hazardous elements was particularly limited. Microprobe analyses indicated that heavy metals were incorporated in newly formed crystals, consisting mainly of hedenbergite, wollastonite, and iron oxide-rich “islands” surrounded by residual glass. The results show that Plasmastone, combined with recycled soda-lime glass and kaolin clay, may be converted in building materials, with a possible commercial exploitation.     

Low cost ceramic moulding composites: materials and manufacturing technology

Abstract

Low cost ceramic moulding compounds/composites are composed of inorganic metal silicates, fillers and different types of chopped fibre reinforcements, such as glass fibres. This research investigated manufacturing process of a series of ceramic moulding compounds that could be moulded at modest temperature (～150°C) and pressure (0–8 MPa). This manufacturing process replicated a process of the fibre reinforced polymeric moulding composites or dough moulding compounds. The conventional polymeric matrix of the dough moulding compounds has been replaced by a soluble metal silicates based on an inorganic system which can be compounded with fibres, minerals or synthetic fillers and hardening additives, to produce a thick paste or a doughy substance, so called ceramic dough moulding compounds. The ceramic dough moulding compounds demonstrated a good handle ability and can be adjusted by the viscosity of the matrix through the use of various amount of fillers and additives. The mechanical properties of the compounds have been tested and additional formulation changes have been introduced to maintain desirable processing characteristics.     

On the determination of free silica in ceramic raw materials

The accurate quantitative determination of free quartz contained in local feldspars and clays was achieved through special methods of differential thermal analysis, and chemical analysis. and chemical analysis. Aswan feldspar and Aswan clays were found to contain varying free quartz contents and were therefore considered as suitable sources of raw materials for the preparation of clay-feldspar-quartz ceramic body mixes. Accordingly, no quartz addition was necessary for the production of pottery and porcelain ceramic bodies.     

含铬工业废水的绿色回收技术

铬是环境中普遍存在的几种微量金属之一,铬作为环境中的一种主要重金属污染物,主要以三价和六价形态存在,其中的三价铬对人和动物是必需的微量元素,而六价铬则是一种毒性较大的致畸、致突变的有害物。当前含铬废水进入了综合防治、回收利用与总量控制阶段,基于含铬废水的回收是当前较为迫切的任务,本文重点阐述了重金属铬的绿色回收技术。