摘要 摘 要
固硫灰是电厂循环流化床锅炉中含硫煤与石灰石等固硫剂在900℃左右燃烧固硫副产物。随着循环流化床燃烧技术迅速发展，固硫灰产量急剧攀升，目前年产生量约8000万吨，主要以堆放为主，资源化迫在眉睫。水泥工业发展对混合材需求量越来越大，固硫灰作水泥混合材是其应用重要方面，资料匮乏，需要进一步研究。
本文采用有代表性电厂固硫灰，首先系统分析了固硫灰的特性，与粉煤灰进行对比，其次根据固硫灰SO3含量特点提出活性评定方法，利用XRD、SEM等对活性来源进行分析，最后对固硫灰作水泥混合材对水泥强度、凝结时间和安定性、减水剂相容性和膨胀性等影响进行了初步研究，重点分析SO3形态及含量对水泥性能影响。
研究表明，与粉煤灰相比，固硫灰高硫高钙高烧失量，颗粒疏松无定形，其中的SO3以硬石膏Ⅱ-CaSO4形式存在，与天然硬石膏具有相同的结构。根据固硫灰SO3含量特点，活性评定采用“水泥熟料28天抗压强度比”进行，按水泥中SO3含量为3.5%确定是否外掺二水石膏，试验表明固硫灰SO3含量不超过11.6%时活性较高，满足水泥活性混合材用粉煤灰标准要求。
固硫灰中硬石膏可以完全取代二水石膏对水泥凝结时间进行调节，且水泥中SO3含量不能超过3.5%，否则会引起SO3安定性不合格。固硫灰SO3含量高，需水量大，单掺作水泥混合材时允许掺量低，且固硫灰中SO3含量增加和固硫灰掺量增加都使得减水剂饱和掺量点提高，水泥初始流动度降低，经时损失率增大，与减水剂相容性差，在实际应用中应与粉煤灰或其它混合材复合，掺量不超过30%，控制水泥中SO3≤3.5%。
关键词：固硫灰；特性；活性；强度；凝结时间；减水剂相容性；膨胀
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中国建筑材料科学研究总院硕士学位论文 ABSTRACT
The Circulated Fluidized Bed Combustion (CFBC) ashes are by-products from the power plants with CFBC boilers which use sulfur coal and sulfur capture agent such as limestone burning and desulfurizing in the boiler at about 900℃. As the rapid spread of CFBC technology, the yearly ash output is about 80 million tons and increases rapidly; as a result, the utilization is urgent. As the development of cement industry, the cement admixture demand is more and more. The CFBC ash as cement admixture is one of its important use methods, which has little information and needs more research.
In this paper, the CFBC ash samples from different power plants were studied. The CFBC ash properties were investigated compared with the pulverized coal (PC) fly ash, a modified method was demonstrated to evaluate the reactivity of CFBC ashes and the reactivity origin was analyzed by XRD, SEM, and the feasibility as cement admixture was initially studied on cement strength, setting time and soundness, compatibility with water-reducing agent and expansion performance, which lays emphasies on the influence of SO3 morphology and content on the cement performance.
The results showed that, compared to the PC fly ash, the CFBC ashes had more content of SO3, f-CaO and loss on ignition. The particles of CFBC ashes were irregular and loose textured. The SO3 existed as anhydrite Ⅱ-CaSO4, which had the same structure with natural anhydrite. A modified method of ―clinker 28d compressive strength ratio‖ was demonstrated to evaluate the reactivity of CFBC ashes according to the SO3 content, which showed that CFBC ash reactivity was high when the CFBC ash SO3 content was less than 11.6%, satisfing the standard requiments of PC fly ash used as cement active addition.
The anhydrite of CFBC ash could completely replace gypsum to retard the clinker setting time, and the SO3 content should less than 3.5%, otherwise, the SO3 soundness was unqualified.With high SO3 content and water requirement content,
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摘要 when the CFBC ashes were used as cement admixture, the permitted addition were limited, at the same time, when the SO3 content and CFBC ash addition increased, the saturation of water-reducing agent increased, the initial fluidity decreased, and the loss rate of fluidity as time increased, so the compatibility of CFBC ash with water-reducing agent was bad. Consequently, when the CFBC ashes were used in cement, it should better mix with PC fly ash or other admixtures, the admixture addition should be less than 30%, and he cement SO3 content was less than 3.5%.
Key words：CFBC ashes, properties, reactivity, mortar strength, setting time, compatibility with water-reducing agent, expansion
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