国内外纯碱工业的现状及市场

在全球范围内,纯碱生产和进出口贸易主要是由中国、欧洲SOLVAY公司和美国主导和控制,中国已经成为世界上生产量和消费量最大的国家,美国则是世界上最大的纯碱出口国,SOLVAY公司不断采取各种措施,调整策略,收购美国和中国的纯碱企业,积极参与国际市场竞争。分析了我国及世界纯碱工业的生产、进出口等现状及发展趋势。     

Pozzolanic properties of reject fly ash in blended cement pastes

Low-grade fly ash (reject fly ash, r-FA), a significant portion of the pulverized fuel ash (PFA) produced from coal-fired power plants and rejected from the ash classifying process, has remained unused due to its high carbon content and large particle size. But it may be used in certain areas, such as in solidification and stabilization processes of hazardous waste and materials for road base or subbase construction, which require relatively lower strength and reactivity. It is therefore necessary to extend research on the properties of r-FA and explore its possible applications. This paper presents experimental results of a study on the mechanical and hydration properties of cementitious materials prepared by blending r-FA with ordinary Portland cement (OPC). Parallel mixes were also prepared with the good ash [i.e., classified fine fly ash (f-FA)] for comparison. Selective chemical activators were added to the mix to study the effects of the activators on the properties of the blend system. The results show that r-FA generally has a lower rate of hydration than f-FA particularly at the early stage of hydration. Adding Ca(OH)₂ alone almost had no effect on accelerating the hydration of r-FA. But adding a small quantity of Na₂SO₄ or K₂SO₄ together with Ca(OH)₂ significantly accelerated the hydration reaction. The results of the compressive strength measurement correlated nicely with the degree of hydration results. It was also found that water-to-binder ratio (w/b) was an important factor in affecting the strength development and the hydration degree of r-FA pastes.     

Zeolite Formation in Class F Fly Ash Blended Cement Pastes

Zeolite formation in Class F fly ash blended cement pastes is under investigation. A Na–P type zeolite and Zeolite Y were synthesized from Class F fly ash and NaOH solution after 2 days of aging at room temperature and 6 days of curing at 80°C. However, no zeolites formed when KOH was used. In additional experiments, a Na–P type zeolite, Zeolite Y, and chabazite developed in cement pastes blended with Class F fly ash and NaOH solution which had been aged 2 days at room temperature and then cured 6 days at temperatures ranging from room temperature to 90°C. Seeding the pastes with natural zeolites was also investigated.     

废渣粉煤灰纤维棉增强PVC复合材料

本文选用废渣制成的粉煤灰纤维棉(FAF)和聚氯乙烯(PVC)树脂作为原料,成功制备了FAF/PVC复合材料,研究了FAF的表面处理及其加入量对复合材料力学性能、热性能和硬度的影响,并用SEM对复合材料的界面进行了表征。实验结果表明,相对于纯PVC树脂而言,复合材料含经KH550处理的FAF40phr时,拉伸强度提高约12%;含经软化剂处理的FAF10phr时,冲击强度提高约110%;含经偶联剂和软化剂联合处理的FAF10phr时,冲击强度提高约70%,拉伸强度提高约11%,维卡软化温度随FAF添加量的增加呈上升趋势。研究结果证明,KH550和软化剂联合使用会对复合材料起到有效的增强增韧效果,因此能提高复合材料中FAF的填充量。制成的环保型FAF/PVC复合材料不仅性能全面高于纯PVC,而且材料成本显著降低,为综合利用废渣FAF开拓了新方向。     

上海地区不同商品粉煤灰水泥浆体的流变性能

采集了上海地区不同种类，等级和加工方式的7种商品粉煤灰，测定了种各种粉煤灰水泥浆体的流变性能，研究了商品粉煤灰品质与掺量对浆体流变参数的影响，并分析了影响浆体流变性能的粉煤灰主要品质因素。     

热媒炉热效率分析与提高

分析了影响热媒炉热效率的主要因素 ,介绍了通过对热媒炉盘管干冰除灰和改进风油比控制方式来提高热效率的方法 ,指出提高热媒炉热效率的主要途径是 :降低排烟温度和空气过剩系数。     

Mobility of trace elements from selected Australian fly ashes and its potential impact on aquatic ecosystems

Batch leaching tests have been performed on fly ashes collected from four Australian power stations fuelled by chemically different coals. Two acidic and two alkaline fly ashes were subjected to long-term (144 h) leaching tests, and the behaviour of As, B, Mo and Se was investigated to obtain data on their potential for mobilisation during fly ash-water interactions. All four elements are mobile under different conditions and over different leaching times. The concentrations of these elements released in leaching solutions with initial pH values of 4, 7 and 10 were used to assess the influence of pH conditions on element mobility from the acidic and alkaline fly ashes. The most mobile of the four elements leached were Mo from alkaline fly ashes and B from acidic fly ashes. Arsenic concentration increased with time in leachate solutions from acidic and alkaline fly ashes; however, in solutions in contact with alkaline fly ashes the As concentration, after reaching a maximum, later decreased with time. Selenium mobility shows a similar pattern to that of As, with similar leaching concentrations. Boron has the highest relative mobility of all four elements. A process possibly responsible for the decrease in concentration of B, As and Se in alkaline leaching solutions is the formation of ettringite. Equilibrium between the solid phase (ash) and the leaching solution was not reached in any of the leaching experiments. The pH of the leaching solution is the key factor affecting the mobility of these trace elements in these fly ashes.     

粉煤灰对混凝土拌合物泵送性能的影响

介绍了粉煤灰对掺有M17塑化剂的混凝土拌合物泵送性能和混凝土强度的影响，通过扫描电镜对粉煤灰颗粒形貌进行了观察，初步探讨了粉煤灰的作用机理。试验说明在接有M17塑化剂的泵送混凝土中加入粉煤灰，可增加坍落度，降低泌水率，泵逆性能可得到改善。     

电除尘器分电场灰密度变化规律及粉煤灰密度与成份的关系

本文介绍粉煤灰经电除尘器分离后所得分电场灰密度沿电场方向的变化规律及影响因素，并阐述了粉煤灰密度与成份之间的关系。     

脱硫石膏粉煤灰胶结材水化硬化机理及耐水性研究

以火电厂的两种废渣即脱硫石膏和粉煤灰为主要原料制得的胶结材，其强度明显高于普通石膏制品，软化系数大于０．８５。采用水化热测定、ＸＲＤ和ｐＨ值测定及ＳＥＭ／ＥＤＸＡ分析，并结合宏观试验结果，分析了这种胶结材的水化硬化机理和微结构特点，并对其耐水性提高的原因进行了讨论。