碱矿渣复合水泥--放射性废物固化基材力学性能的研究(一)

在碱矿渣水泥中,掺入参改性其水化产物,提高其吸附性能的粘土矿物材料,构成用于放射性废物固化的碱矿渣复合水泥体系。研究了该体系的力学性能,结果表明,粘土矿物的掺量和养护制度对碱矿渣复合水泥的强度有较大影响,当热活化高岭土,沸石,改性凹凸棒掺量分别为１０％、５％、１５％时,其２８ｄ净浆抗压强度达８９．８ＭＰａ。该复合水泥浆体宜湿气养护,且具有良好的耐辐照和抗硫酸盐性能。     

碱矿渣复合水泥--放射性废物固化基材力学性能的研究(二)

3 结果与讨论3.1 热活化高岭土掺量对强度的影响 C—S—H凝胶具有一定的离子吸附和交换能力,尤其在铝部分取代了硅之后。在碱矿渣水泥中掺入热活化高岭土来提高体系的铝含量,为该水泥浆体形成富铝、低碱C—S—H凝胶和沸石类水化产物提高了物质条件。热活化高岭土掺量对碱矿渣水泥强度的影响见图1(激发剂为工业水玻璃,模数为1.5,掺量为5％以Na_2O计,另加2％的工业Na_2CO_3,在相对湿度大于90％的湿空气中养护,下同)。     

Comparison of radioactive transmission and mechanical properties of Portland cement and a modified cement with trommel sieve waste

In this study, it was aimed to stabilize trommel sieve waste (TSW) occurring during manufacture of borax from tincal. The effects of TSW added on the mechanical properties and radioactive transmission of modified cement prepared by adding TSW to clinker was investigated. The properties which TSW as additive caused the cement to gain were tested and compared with normal Portland cement.Measurements have been made to determine variation of mass attenuation coefficients of TSW and cement by using an extremely narrow-collimated-beam transmission method in the energy range 15.746-40.930 keV with X-ray transmission method. The characteristic Kα and Kβ X-rays of the different elements (Zr, Mo, Ag, In, Sb, Ba and Pr) passed through TSW and cement were detected with a high-resolution Si(Li) detector. Results are presented and discussed in this paper.     

Electrochemical treatment of low-level nuclear wastes

Electrochemical reductions of Hg(ii), [RuNO(NO2)4OH]2-, CrO42-, and NO3- in 1.33 NaOH solution were studied at packed bed electrodes with a view to application of the electrochemical technique to treat nuclear waste solution. The reductions of Hg(ii), [RuNO(NO2)4OH]2-, and CrO42- were mass-transfer controlled while nitrate reduction was activation controlled. Based on the data obtained, scale-up for each reduction is proposed and discussed. The experimental data obtained have been used in the design of a plant and detailed calculations have been made. An economic analysis has been made to point out the advantages of the electrochemical treatment.     

中国水泥工业消纳社会废弃物与发达国家的差距

预分解水泥窑消纳各种含有可燃质的废物,既可充分利用其残留的热值,还能彻底干净地处置其燃烧后的残渣,消除二次污染隐患;加之水泥窑适应范围广,可以消纳各种状态的废料,处置能力很大。此法比新建垃圾填埋场或焚烧厂等办法经济得多,收效更快。水泥工业还可以将各种工业废渣用作混合材掺于水泥熟料中一并粉磨成水泥;有的工业废料还可以用作水泥原料以替代天然的石灰石、粘土或铁矿石等。在水泥工业消纳社会废弃物方面,我国与德日美等发达国家,在理念和技术上还有差距：我国看似消纳混合材不少,实为部分超掺滥掺所致;我国原料和石膏的替代率尚有较大提升空间;我国替代燃料的应用十分滞后,须急起直追。     

资源化利用固体废弃物研发生态水泥

要使我国水泥工业适应时代发展的需要,就要树立可持续发展的生态水泥观,充分发挥水泥工业在资源化利用固体废物方面的优势,研发和生产生态水泥,这既是水泥工业自身发展的需要,又是可持续发展的需要,以此来指导我国水泥工业的规划、设计和自主创新,走可持续发展的生态水泥之路。     

Comparison between rheological models for portland cement pastes

Rheological properties of Portland cement pastes, measured with a rotating viscosimeter, have been correlated by means of different mathematical models. The best results are obtained with Eyring's equation, Herschel & Bulkley's equation and the parabolic equation, while Vom Berg's model only holds for low shears. The authors propose another equation derived from Eyring's but explicitly containing the term τ_o.     

Calcium sulfoaluminate cement blended with OPC: A potential binder to encapsulate low-level radioactive slurries of complex chemistry

Investigations were carried out in order to solidify in cement a low-level radioactive waste of complex chemistry obtained by mixing two process streams, a slurry produced by ultra-filtration and an evaporator concentrate with a salinity of 600 gxL^− 1. Direct cementation with Portland cement (OPC) was not possible due to a very long setting time of cement resulting from borates and phosphates contained in the waste. According to a classical approach, this difficulty could be solved by pre-treating the waste to reduce adverse cement–waste interactions. A two-stage process was defined, including precipitation of phosphates and sulfates at 60 °C by adding calcium and barium hydroxide to the waste stream, and encapsulation with a blend of OPC and calcium aluminate cement (CAC) to convert borates into calcium quadriboroaluminate. The material obtained with a 30% waste loading complied with specifications. However, the pre-treatment step made the process complex and costly. A new alternative was then developed: the direct encapsulation of the waste with a blend of OPC and calcium sulfoaluminate cement (CS̄̄A) at room temperature. Setting inhibition was suppressed, which probably resulted from the fact that, when hydrating, CS̄̄A cement formed significant amounts of ettringite and calcium monosulfoaluminate hydrate which incorporated borates into their structure. As a consequence, the waste loading could be increased to 56% while keeping acceptable properties at the laboratory scale.     

SHS of mineral-like ceramics for immobilization of radioactive nuclear wastes

Synthetic analogs of titanate ceramics (perovskite and zirconolite) designed for use as a matrix for immobilization of high-level nuclear fuel reprocessing wastes (HLW). Such ceramics have been prepared by SHS method from a mixture of titanate ceramics and non-radioactive model oxides. Synthesis conditions have been optimized. The synthesized low-porosity cylindrical compacts exhibited a high strength and low rate for leaching Cs, Sr, Y, Ce, and La in bidistilled water. The phase composition and microstructure of synthesized products have been characterized. The immobilization of Cs was found to be accompanied by a marked loss of this element. The text was submitted by the authors in English.     

水泥工业利废进展及前景

水泥工业消纳利废的途径是将各种合适的废弃物或经适当加工预处理后的废弃物分别用作水泥的替代原料,或用作水泥窑的替代燃料,或用作混合材。相对而言,这三种利废方式中用作混合材是最简便易行的,来源也多;用作替代原料的往往具有一定的技术难度,来源较有限;用作替代燃料的难度最大,但各种可燃废弃物的来源却在日益扩大之中,数量也呈上升之势。然而,在中国水泥中混合材掺入量超标太多,而且大都作为填充料机械地掺入。今后必须严格监督执行国家标准（GB175—2007）,坚决制裁超标或滥掺混合材的行径,加强发掘混合材活性的研发工作,从单纯追求数量转向提升质量的轨道上来。我国利用工业废渣作为替代水泥天然原料资源已取得一定成绩,但我国水泥工业始终对替代燃料不感兴趣,缺乏市场利益驱动,更谈不上什么协同全社会的环保利废责任感。笔者分析认为,在我国当前的具体情况下,一条5000t／d新型干法水泥生产线,采用可燃废料替代25％的煤耗时,其经济效益可与其增设纯低温余热发电的相媲美（包括CO2减排CDM的收益在内）。     

Comparison between oil-shale ash and cement pastes

It was shown that the structures and properties of both ash and cement pastes can be described and explained by the same structural models. At the same age, and for the same water/binder ratio, the ash pastes, however, exhibited higher total and capillary porosities, lower specific surface area and, to the age of 28 days, greater threshold diameter. The strength of both systems was essentially the same implying that intrinsic strength of the gel of the ash was greater than that of the cement.     

Polyfunctional microspherical materials for long-term disposal of liquid radioactive wastes

The possibility of immobilizing liquid radioactive wastes into polyfunctional microspherical materials of the block and powdered types is demonstrated. These materials are intended for reprocessing radioactive wastes of different compositions and make it possible to perform a multistage process of conditioning radioactive wastes under relatively mild conditions (at temperatures below 1000°C) with the conversion of water-soluble cesium and strontium compounds into water-insoluble mineral forms in the course of solid-phase transformations. Owing to the aluminosilicate composition of microspherical components of energy ashes (cenospheres), the cenospheres can serve as precursors of aluminosilicate granitoid minerals. Different techniques are proposed and conditions are experimentally determined for transforming precursors into final mineral-like materials of the predicted structure types chosen in the framework of the geoecological approach. The framework structures of aluminosilicates and phosphates thus formed can fix cesium and strontium in the crystal lattice and ensure the geochemical equilibrium between the matrix and incorporating granitoid rocks under conditions of long-term disposal.     

Use of local loam in vitrifying radioactive wastes

Translated from Steklo i Keramika, No. 11, pp. 23–25, November, 1991.     

New technique for improvement on reactivity of cement industry wastes

Abstract

A new technique, in which fly ash was first ground before grinding together with cement kiln dust (CKD), was developed in order to activate reactivity of CKD–fly ash systems. Test results of particle size distribution, rate of heat evolution and compressive strength of mixtures made with the new technique are discussed and compared with those of mixtures made with previous technique, in which CKD and fly ash were ground together without prior grinding of fly ash. The test results showed that CKD–fly ash mixtures made with the new technique exhibited significantly improved performance in comparison with that of mixtures made with the previous process.     

Relationships between electrical and physical properties of cement pastes

Many aspects of mechanical behavior of engineering materials, specifically concrete and soils, can be explained from a knowledge of physico-chemical and/or particle geometry factors. A qualitative measure of the above factors has been used to describe a modelled structure of the cement gel system, and attempts have been made to correlate the engineering properties of hardened cement pastes with their microstructure. This paper presents the results of preliminary investigations which suggest that some of the important mechanical properties of mature cement pastes may be predicted quantitatively from measurements of their electrical properties at early ages.

Abstract

La représentation qualitative de leurs propriétés physicochimiques, et de relations géométriques entre leurs particules élémentaires, expliquant bien des aspects du comportement mécanique des matériaux di construction industriels, a été appliquée aussi à la définition d'un “modèle” de représentation de structure pour les gels de ciment. On a même tenté d'établir une corrélation entre leurs propriétés industrielles, et la structure microscopique de diverses pâtes cimentaires après durcissement. Le présent mémoire exposura les résultats d'études préliminaires qui donnent à croire que certaines caractéristiques mécaniques importantes de ces pâtes, une fois arrivées a un stade de vieillissement assez avancé, pourraient se prédire également d'une manière quantitative, grâce à la mesure de leurs propriétés électriques aux premiers stades.     

水泥回转窑处理废弃物的现状和前景

水泥生产需要消耗大量的天然资源,如石灰石、煤等都是不可再生的天然资源,这一特性制约了水泥行业的可持续发展之路.而地处上海的水泥企业由于无矿产资源,产品成本较高,从而在市场竞争中处于劣势,进一步制约了企业的生存和发展.如何改变劣势,走出困境,利用废弃物代替水泥生产中的原燃料,减少天然矿物的消耗,利用水泥窑的工艺特点,合理处置工业危险废弃物,加强与环境的亲和力,是水泥企业可持续发展的方向之一.上海工业发达、人口密集,废弃物产生量大,为其利用创造了较大的空间(见表1).……     

Decontamination of radioactive soil wastes using an agglomeration-leaching process

An agglomeration-leaching process was evaluated to decontaminate Co-60 and Cs-137 from radioactive soils. Radioactive soils were screened based on the particle size of 0.075 mm. The soils with particle size of less than 0.075 mm were agglomerated by using a 2 wt% Na₂SiO₃ which had been predetermined to be an optimum reagent for an agglomeration. The agglomerated soils were mixed with the other soils with particle size bigger than 0.075 mm for leaching tests. Several leaching solutions were evaluated for their leaching performances for Co-60 and Cs-137 from simulated soil wastes, and the 0.1 M HCl solution was shown to be the most effective one. Leaching tests for radioactive soils in a column showed that the radioactive soils contaminated with Co-60 and Cs-137 radionuclides could be decontaminated down to the potential release criteria (∼100 Bq/kg) by using the appropriate conditions of an agglomeration-leaching process.     

浅谈水泥窑协同处置危险废物配伍

水泥窑协同处置危险废物配伍解决的问题就是使得一些易混合发生反应的、爆炸的、高腐蚀性的物料进行单独预处理,并适当和惰性的物料混合,控制适当热值和水分、尺寸,以利于燃烧稳定;将含钾、钠、镁等碱金属和含氟、氯等卤族元素可以反应生成稳定化合物的危险废物应适当搭配,并控制进入水泥窑中有害元素含量,控制入窑物料中重金属含量,减少对...     

Computer-aided simulation of radioactive pollution of environment upon destruction of geologic repositories of radioactive wastes with allowance for uncertainty

Some mathematical and computer models of the propagation of radioactive pollutants in the environment upon the destruction of geologic repositories of radioactive wastes have been developed with allowance for the interval uncertainty of some physicochemical parameters of the propagation of radioactive pollutants in the environment (the velocity of the rise of underground water from radioactive wastes and the diffusion coefficients of radioactive pollutants in a geologic horizon). Computer-aided simulation results show that the half-life of radioactive wastes, the rate of the leak of radioactive pollutants from a repository, and the velocity of the advection of radioactive pollutants towards the ground are the principal characteristics of the propagation of radioactive pollutants in the environment. These characteristics of the propagation of radioactive pollutants in the environment must be taken into account in the design of safe geologic repositories of radioactive wastes. As a result of the computer-aided simulation of the propagation of radioactive pollutants, it has been established that the minimization of the radioactive pollution dose requires that the hermeticity periods of geologic repositories exceed or be nearly equal to the half-lives of radioactive pollutants.