模拟高钠高放废物铁硼磷酸盐玻璃固化体的结构和性能

以36Fe2O3--10B2O3--54P2O5为基础玻璃,制备了不同模拟高钠高放废物包容量的铁硼磷酸盐玻璃固化体,用Fourier变换红外光谱测试方法系统研究了由废物包容量引起的玻璃固化体结构变化,并用溶解速率法初步测试了固化体的化学性能。结果表明:随着废物包容量的增加,固化体试样结构中(PO4)3-四面体基团增加,[BO3]基团向[BO4]基团转变,磷酸盐基团彼此间的连接程度减小,Fe—O—P键在包容量为25%(质量分数)到30%时存在量较大。玻璃固化体网络结构以(PO4)3-四面体基团为主,易水化的(PO3)-磷酸盐基团的含量很小。但固化体结构中[BO3]基团的存在量还较大,该组分的基础玻璃网络形成体氧化物配比还可进一步优化。当废物包容量小于40%时,固化体不同浸泡周期的质量损失速率均在10--8 g/(cm2·min)数量级。     

Inertization of Coal Ashes by the Vitrification Technique: A Mixture Design Approach

This article deals with the study of the vitrification mechanism as an inertization method for coal ashes contaminated with heavy metals. Ashes from coal (thermoelectric) and wastes from mining of fluorite and feldspar and from plating were used to compose vitreous systems using a mixture design. The chemical composition of the wastes was determined by XRF and the formulations were melted at 1450°C for 2 h using 10% (mass) of Na₂CO₃ (as a fluxing agent). The glasses were poured into a mold and annealed (600°C). The characteristic temperatures were determined by thermal analysis (DTA, air, 20°C/min) and the mechanical behavior by HV. As a result, the softening temperature is strongly dependent on silica content of each glass, and the fluorite residue, being composed mainly by silica, strongly affects on the glass transition (T_g) and softening (T_s) temperatures. The hardness by micro-indentation of all glasses is mainly affected by the plating (galvanic) residue due to the high iron and zinc content of this waste.     

Kiyoteru Tokuyasu: a pioneer of cryo‐ultramicrotomy

In July 2015 Professor K.T. Tokuyasu passed away in San Diego giving us the opportunity to reflect on the contribution this electron microscopist made to the field of immunocytochemistry. His work provided a sensitive, minimally invasive approach to producing thin sections of biological material for labeling with antibodies. His approach has been applied to a wide range of biological applications and provided important information on cellular processes.     

Thermodynamic modelling of the spontaneous vitrification process using transformation diagrams

Spontaneous vitrification is a phenomenon where a crystalline phase transforms to the amorphous phase on annealing at low temperatures. It has been reported to occur in several binary alloy systems. This phenomenon has been widely investigated in the Ti–Cr system through experiments as well as thermodynamic modeling. The models reported in literature suffer from several drawbacks. They are not consistent with experimental observations. These models treat this non-equilibrium process as an essentially equilibrium process albeit involving two meta-stable phases. The thermodynamics of the “spontaneous vitrification” process has been modeled using the concept of Transformation Diagrams. This method considers the thermodynamics of non-equilibrium phase transformation and does not involve assumptions of equilibrium at any stage. A significant conclusion derived from the present model is that it is the close-packed hcp structure that transforms to the amorphous phase whereas the transformation of the relatively open bcc structure to the amorphous phase is forbidden thermodynamically. These conclusions are in contrast with the predictions of the earlier models.     

SiO2和B2O3含量对模拟高放废物玻璃结构的影响

硼硅酸盐玻璃具有特别高的化学稳定性、较好的热稳定性、较大的放射性废物包容量等优点,被广泛作为固化高放废液的基础玻璃料。废物玻璃固化体的结构与其组成存在一定的内在依存关系,它将对废物玻璃的性质产生影响。以组分含量作为变量,所引起的废物玻璃固化体的某些结构特征的变化,是探索影响高放废物玻璃固化体性能的内在线索。为了获取废物玻璃组分含量对其结构特征参数（非桥氧键数）的影响规律,以对废物玻璃固化体的性能进行估计,进而指导设计高效处理高放废液的玻璃固化体配方,以某模拟高放废物玻璃固化体的配方为基础,通过改变其中SiO₂和B₂O₃含量制备一系列的废物玻璃样品,并进一步采用拉曼光谱法对废物玻璃的硅酸盐网络结构单元（Qn,Q和n分别代表四面体单元和每个四面体结构单元所具有的桥氧键数）进行分析,讨论SiO₂和B₂O₃含量对此废物玻璃固化体网络结构的影响。结果表明：随着SiO₂含量（SiO₂的质量与剩余氧化物质量的比值）由0.721增加到1.037,废物玻璃固化体中桥氧键的比例随之而增多,同时玻璃网络结构的聚合度（N,非桥氧/桥氧的比例）减小,但是,随着B₂O₃的含量（B₂O₃的质量与剩余氧化物质量的比值）由0.117增加到0.143,再到0.176,桥氧键的比例先减小后增大。在本实验的范围内,废物玻璃固化体的密度变化不明显,无析晶现象。     

模拟高放废液玻璃固化体溶解液的ICP／AES分析法

利用我院制造的高浓盐雾化器解决了送样过程中同心雾化器堵塞的问题,并且详细观察了存在于溶解液中诸元素,尤其是具有复杂光谱结构的元素之间的谱线干扰现象。我们注意到硫的最灵敏的主共振线S 180.73nm为Ca线所干扰,为此,采用次灵敏的S 1820.4nm谱线;还观察到铀和钛对Li323.26nm和Na330.24nm的谱线干扰。改变等离子体的工作参数,即增加载气流,减小高频功率,可提高被测元素Li,Na的谱线强度,同时降低干扰元素的谱线强度,从而可以在U,Ti共存的溶液中测定Li和Na。本法可测定玻璃模拟体中主次成分,共十九个元素:B,Si,Na,Li,Al,Ca,Mg,Sr,Zr,Ti,Ce,La,Nd,Fe,Cr,Mn,Ni,S,U。方法的相对标准偏差随元素不同约为1%～5%。     

Cure and properties of thermosetting systems

A generalised time-temperature-transformation cure diagram for thermosetting systems is discussed from the point of view of understanding relationships between cure, properties, and thermal degradation.     

Thermal spray vitrification process for the removal of lead-based paint from steel structures: An applications note

Lead-based paints and primers have long been used to protect steel structures from corrosion, but are now recognized as environmental hazards. During lead-based paint removal via abrasive blasting, federal, state and local environmental requirements mandate the use of containment structures to prevent contamination of air, soil, or water. The thermal spray vitrification (TSV) process was developed and optimized in laboratory experiments to remove hazardous lead-based paint. TSV consists of thermal spraying a molten glass onto the painted surface. As the glass strikes the substrate, it reacts with the paint, and organic components are pyrolyzed, while lead ions are trapped on the glass surface. Quenching stresses in the glass cause it to crack and spall off the substrate. The resulting glass fragments are collected, and further remelted to completely immobilize lead (Pb) ions in the glassy iron (Fe) silicate matrix. The glass waste is thus rendered non-hazardous, as determined by the Toxicity Characteristic Leaching Procedure (TCLP). The TSV process was field tested on a fire hydrant, using minimal personal protective equipment and without using a containment structure. The lead-containing paint was removed, without producing hazardous waste, leaving de-painted surfaces suitable for repainting.     

侧吹炉处置危险废物若干问题的探讨

对侧吹炉处置危险废物的国民经济行业分类、玻璃化、水淬渣性质鉴别等问题进行了探讨。结论为:采用侧吹炉处置危险废物应属于国民经济行业分类中的危险废物治理(7724),而不属于有色金属冶炼和压延加工业(32)。尽管侧吹炉处置危险废物存在高温熔融状态,但在玻璃化相关定义和标准公布前,不宜直接将水淬渣定性为玻璃态物质。尽管已有证据表明水淬渣属一般工业固体废物,但入炉危险废物的种类、来源、成分复杂,产生的水淬渣性质具有一定的不确定性,不论其是否为玻璃态,均应从实际处置效果判定,应当在投产后对水淬渣进行性质鉴别。