在碳达峰、碳中和背景下，水泥等建材行业能耗高、排放高、产能过剩，面临巨大挑战。从水泥行业现有CO2减排技术出发，分析了水泥低碳生产方式的原理和现状，归纳总结了原料替代、燃料替代和熟料替代技术现状。最后结合国内现状和发展规划，对水泥行业低碳技术进行展望。水泥行业现有CO2减排技术包括将低碳原料或工业废弃物代替生料中某些成分的原料替代技术；将低碳排放的清洁燃料应用于水泥生产的燃料替代技术；将有凝胶活性的材料添加到混凝土中以节省熟料使用量的熟料替代技术；应用电能和使用燃料时提升能源利用效率的方法和技术以及颇具前景但尚未大规模应用的碳捕集、封存技术(CCS)。原料替代方式是最有效的低碳生产方式，硅酸盐水泥原料中包含大量石灰石，会在水泥生产过程中分解产生烧制熟料必需的CaO和大量CO2，利用富钙废弃物替代石灰石等高载碳原料，可显著减少CO2排放，同时提供等量的CaO，用以替代的原料包括电石渣、硅钙渣、钢渣、石英污泥及造纸污泥等，其中不同工业废料对于水泥生产不仅可代替石灰石原料，还可能提供额外效益，如硅钙渣能提供硅质原料，钢渣的应用可能改善生料易烧性。应用农林业废弃物提供生产水泥的热量可降低碳排放，将生活垃圾或城市污泥部分代替生产用燃煤还可协同处置废弃物和垃圾，燃料预热技术是将燃料经一次预热后投入生产窑炉中，代替直接投入的燃料，是实现低排放和提升能源效率的有效方法。熟料替代可有效降低碳排放，将矿渣、粉煤灰、火山灰、石灰石、烧黏土等混合型材加入混凝土，利用其本身具有的胶凝活性可发挥部分替代熟料的作用，有利于CO2减排，但我国水泥熟料系数较低，建议国内适当提高水泥的熟料系数。当前技术水平决定了熟料替代应用依然广泛，燃料和生料替代率预期将逐步提高。中期目标是实现替代燃料和替代原料技术的应用能力最大化，CCS技术更成熟，且可全面淘汰落后产能。长期目标是水泥企业可根据政策和生产要求制定有效且经济的减排方案，助力水泥行业实现碳中和。

Under the background of carbon peak and carbon neutrality, cement and other building materials industry, as an industry with high energy consumption, high emissions, and overcapacity, face a great challenge. Starting from the existing CO2 emission reduction technologies in the cement industry, the principle and current situation of low-carbon cement production mode were analyzed, and the current situation of raw meal substitution, fuel substitution and clinker substitution technology were summarized. Finally, combined with the domestic current situation and development plan, the low-carbon technology of the cement industry was prospected. The existing carbon dioxide emission reduction technologies in the cement industry include: the raw meal substitution technology that substitutes low-carbon raw meal or industrial wastes for a component in raw meal, the fuel substitution technology that applies low-carbon clean fuels to cement production and adds materials with partial cementation properties to concrete to reduce the use of clinker, the technologies to improve energy efficiency when using electricity and fuel, as well as promising but not yet large-scale application of carbon capture and carbon storage technology. The raw meal component substitution method is the most effective low-carbon production method. Portland cement raw meal contain a large amount of limestone, which will decompose and produce CaO and a large amount of CO2 necessary for clinker firing in the process of cement production. Using calcium rich waste to replace limestone and other high carbon loaded raw meal can significantly reduce CO2 emissions and provide the same amount of CaO. The raw meal to be replaced include calcium carbide slag, calcium silicate slag, steel slag, quartz sludge, papermaking sludge, etc. Different industrial wastes can not only replace limestone raw meal for cement production, but also provide additional benefits. For example, providing calcium silicate slag can provide silicon raw meal, and the application of steel slag may improve the burnability of raw meal. The fuel substitution method can serve multiple purposes, using agricultural and forestry wastes to provide heat for cement production can reduce carbon emissions. Substituting domestic waste or municipal sludge with high calorific value for coal for production can also be used for disposal of waste, the fuel preheating technology, which replaces the directly input fuel after preheating, has been proved to be an effective method to achieve low emissions and improve energy efficiency. Clinker substitution can effectively reduce carbon emissions. Adding slag, fly ash, pozzolan, limestone, burnt clay to concrete can replace clinker by using its own cementitious activity, which is conducive to CO2 emission reduction, but China′s cement clinker coefficient is low. It is recommended that the domestic cement clinker coefficient be appropriately increased. The current technical determines that clinker replacement is still widely used, and the replacement rate of fuel and raw meal is expected to gradually increase. The medium-term goal is to maximize the application capacity of alternative fuels and alternative raw meal technologies. CCS technology is more mature, and backward production capacity is completely eliminated. The long-term goal is that cement enterprises can formulate reasonable, effective and economic emission reduction plans according to policies and production requirements, and the cement industry can achieve carbon neutrality.

0 引言

1 水泥行业现有CO2减排技术

2 原料替代

   2.1 电石渣替代

   2.2 硅钙渣替代

   2.3 钢渣替代

   2.4 石英污泥替代

   2.5 造纸污泥替代

3 燃料替代

   3.1 生物质燃料

   3.2 生活垃圾及城市污泥

   3.3 燃料预热改性技术

4 熟料系数适当降低

5 结语及展望