磷石膏在硅酸盐水泥生产中的应用

磷石膏是硫酸分解磷矿、萃取磷酸过程中的副产物,制取1 t磷酸,副产磷石膏约5 t;目前我国磷石膏累计堆存量已超过1亿t,不仅占用大量土地,而且容易造成大气、水等环境污染。搞好磷石膏的综合利用和三害化处理是磷肥行业的重要任务。     

改性磷石膏在普通硅酸盐水泥中的应用

通过小磨试验研究了改性磷石膏对普通硅酸盐水泥凝结时间及强度的影响,确定了冬夏两季应用改性磷石膏生产水泥的配比。生产实际表明,应用pH值为7～13的磷石膏生产的水泥产品完全满足国家标准要求,凝结时间可调控范围宽;应用改性磷石膏既消化了工业生产废渣,又降低了生产成本,带来了较好的社会效益与经济效益。     

磷石膏在水泥生产中的应用

1 磷石膏的化学组成 磷石膏是用磷矿石与硫酸反应,制取磷酸的副产品,其反应方程式如下: Ca_5F(PO_4)_3 5H_2SO_4 10H_2O =5CaSO_4·2H_2O 3H_3PO_4 HF 刚排放的磷石膏含有25％左右的水份,呈分散的细小颗粒,外观象豆腐渣,略有异味,pH=3～4,容重约800～850kg/m~3。干燥后的磷石膏外观呈灰白色粉状,密度为2240kg/m~3。     

磷石膏替代天然二水石膏在水泥生产中的应用

简要介绍了磷石膏的特性与天然二水石膏的性能区别;重点就皖维高新材料股份有限公司在用磷石膏代替天然二水石膏作缓凝剂生产P·O42.5水泥的试验方案、试验效果及其在大磨生产中的应用情况和经济效益分析作了介绍。结果表明,磷石膏替代天然二水石膏生产,效益显著,每年为公司可节约生产成本692万元。     

磷石膏替代天然二水石膏在水泥生产中的应用

简要介绍了磷石膏的特性与天然二水石膏的性能区别;重点就皖维高新材料股份有限公司在用磷石膏代替天然二水石膏作缓凝剂生产P·O42.5水泥的试验方案、试验效果及其在大磨生产中的应用情况和经济效益分析作了介绍。结果表明,磷石膏替代天然二水石膏生产,效益显著,每年为公司可节约生产成本692万元。     

磷石膏作缓凝剂在水泥生产中的应用

磷石膏作缓凝剂在水泥生产中的应用孙国芳江苏省扬中县水泥厂（２１２２００）１磷石膏的物化特性及作缓凝剂的可行性水泥工业生产中一般以天然石膏作通用水泥的缓凝剂，而化学副产石膏的应用并不普及，磷石膏是湿法制造磷酸的工业废渣，含自由水２０％～３０％，外观为灰...     

磷石膏在普通硅酸盐水泥生产中的应用

磷石膏与脱硫石膏搭配生产P·O52.5、P·O42.5(R)水泥,虽然1d强度有所降低,但后期较高。掺加一定比例的磷石膏可以改善夏季高温季节水泥凝结时间与外加剂适应性的问题。     

煅烧磷石膏作水泥缓凝剂和增强剂

磷石膏为湿法生产磷酸排放的工业废渣，因含可溶磷杂质，不能直接使用。试验提出对磷石膏在730℃煅烧，应用于配制硅酸盐水泥。结果表明，磷石膏经高温煅烧可消除可溶磷的不良影响，能代替二水石膏作水泥的缓凝剂，且有显著的增强效果，文中对增强机理亦作了探讨。     

Utilization of weathered phosphogypsum as set retarder in Portland cement

In this study, usability of weathered phosphogypsum (PG) from residue areas as set retarder in Portland cement was investigated. The effects on the setting and mechanical properties of PG added in ratios 1, 3, 5, 7, 10, and 12.5 wt.% to Portland cements were studied and compared with a Portland cement containing natural gypsum (NG). It was found that PG can be used in place of NG for Portland cement according to Turkish standards. The highest 28-day compressive strength was found in the sample with 3 wt.% PG.     

磷石膏中可溶性磷对硅酸盐水泥性能的影响

本文通过向磷石膏中外掺可溶性磷,研究了可溶性磷含量对硅酸盐水泥与外加剂相容性及其强度的影响。研究结果表明,磷石膏中可溶性磷的含量影响着水泥与外加剂的相容性,外掺H₃PO₄、H₂PO₄^-、HPO₄^2-时,随其掺量的增加,硅酸盐水泥与外加剂的相容性逐渐变差。相对于天然石膏而言,磷石膏中可溶性磷的含量仅引起硅酸盐水泥早期强度有所降低。     

微膨胀型中热硅酸盐水泥生产与控制

三峡工程为了避免或减轻大坝产生裂缝，提高大坝的耐久性，除了对结构设计、施工技术和降温措施等多方面严格要求以外，对大坝所使用的水泥的性能与质量更是放在重中之重的位置。三峡工程开发总公司经大量的研究论证，决定采用微膨胀型中热硅酸盐水泥，对水泥的成分与性能提出了各项指标要求。湖南石门特种水泥有限公司作为三峡工程水泥供应单位之一，研制生产了合格的微膨胀型中热硅酸盐水泥。１微膨胀型中热硅酸盐水泥的特点微膨胀型中热硅酸盐水泥利用熟料中MgO膨胀的特点，在中热硅酸盐水泥的基础上，把熟料中MgO含量提高到４．５％左…     

用磷石膏作水泥缓凝剂的试验研究

为了提高工业副产品--磷石膏的利用率,减少其废渣占用土地、污染环境等问题,进行了不同陈化期磷石膏单掺或与二水石膏双掺作水泥缓凝剂的试验研究.在此基础上进行了工业性生产实践.结果表明：（1）工业性生产中可单掺磷石膏作为水泥缓凝剂,与二水石膏按适当比例搭配双掺效果更好;（2）陈化1个月至5年后的磷石膏作缓凝剂对硅酸盐水泥熟料具有良好的缓凝、增强作用;（3）用磷石膏作水泥缓凝剂,水泥生产企业可实现经济和社会效益的双赢.     

The AFm phase in Portland cement

The AFm phase of Portland cements refers to a family of hydrated calcium aluminates based on the hydrocalumite-like structure of 4CaO·Al₂O₃·13-19 H₂O. However OH⁻ may be replaced by SO₄²⁻ and CO₃²⁻. Except for limited replacement (50 mol%, maximum) of sulfate by hydroxide, these compositions do not form solid solutions and, from the mineralogical standpoint, behave as separate phases. Therefore many hydrated cements will contain mixtures of AFm phases. AFm phases have been made from precursors and experimentally-determined phase relationships are depicted at 25 °C. Solubility data are reported and thermodynamic data are derived. The 25 °C stability of AFm phases is much affected by the nature of the anion: carbonate stabilises AFm and displaces OH and SO₄ at species activities commonly encountered in cement systems. However in the presence of portlandite, and as carbonate displaces sulfate in AFm, the reaction results in changes in the amount of both portlandite and ettringite: specimen calculations are presented to quantify these changes. The scheme of phase balances enables calculation of the mineralogical balances of a hydrated cement paste with greater accuracy than hitherto practicable.     

硅酸盐水泥的性能及其应用(一)

硅酸盐水泥国外称波特兰水泥，它是性能最好、应用最为普遍的水硬性胶凝材料，近几年，不论是国内还是国外水泥市场都对它提出了更高要求。一方面要求水泥性能优良、稳定，具有多样性，能满足不同用户的各种个性要求，以确保混凝土具有良好的质量和足够的耐久性；另一方面，从环保角度考虑要尽可能多地利用劣质原料和废料，最大限度地减少有用资源和能源消耗、降低CO2排放量，为全球治理温室效应做贡献。这两方面要求在某种程度上又是相互矛盾的。我国水泥工业也是如此，也有一些较为突出的矛盾，如水泥性能如何与混凝土耐久性联系起来，如何正确选用各类水泥，在利用废料开发新水泥品种时如何评价水泥性能及适用范围等等。本文想就这些问题结合欧洲国家的相关情况谈些个人看法，以供参考。     

硅酸盐水泥的性能及其应用(二)

对水泥适用领域的确定还没有评价标准，随着废料利用的扩大，还会有更多新品种水泥问世，这一问题就显得尤为重要。一种水泥对某种环境条件是否适用，除强度、凝结特性等有据可查的性能外主要是混凝土的耐久性。如何检测和评价混凝土耐久性，国内文献报道不多。德国水泥研究所等部门在研究确定掺矿渣与石灰石的复合波特兰水泥适用领域时，就其混凝土耐久性方面作了许多带有示范性的试验工作，这里仅就其主导思想和评价方法作些归纳和介绍。     

The permeability of Portland limestone cement concrete

The effect of limestone addition on the air permeability, water permeability, sorptivity, and porosity of limestone cement concrete has been investigated. Six Portland limestone cements (PLCs) with different limestone content (10-35% w/w) were produced by intergrinding clinker, gypsum, and limestone. A water-to-cement ratio (w/c) of 0.70-0.62—depending on the cement strength class—was used to prepare concrete of the compressive strength class C20/25 of EN 206-1. A modified commercial triaxial cell for 100-mm-diameter samples was used for the determination of the gas (N₂) and the water permeability of concretes. In addition, the sorptivity and porosity of the samples were measured, while thin sections of the concrete specimens were examined by means of optical microscopy. It is concluded that the PLC concrete indicates competitive properties with the ordinary Portland cement (OPC) concrete. Furthermore, the limestone addition has a positive effect on the water permeability and the sorptivity of concrete.     

Sulfate ingress in Portland cement

The interaction of mortar with sulfate solutions leads to a reaction front within the porous material and to expansion. Thermodynamic modelling coupled with transport codes was used to predict sulfate ingress. Alternatively, “pure” thermodynamic models - without consideration of transport - were used as a fast alternative to coupled models: they are more flexible and allow easy parameter variations but the results relate neither to distance nor to time. Both transport and pure thermodynamic modelling gave comparable results and were able to reproduce the changes observed in experiments. The calculated total volume of the solids did not exceed the initial volume of the paste indicating that not the overall volume restriction leads to the observed expansion but rather the formation of ettringite within the matrix and the development of crystallisation pressure in small pores. The calculations indicate that periodic changing of the Na₂SO₄ solution results in more intense degradation.