在冶金带式焙烧机上投笼焙烧的煤矸石陶粒及其性能分析

Gangue Ceramsites Roasted in a Metallurgical Belt Roaster with Cage Casting and Its Performance Analysis

煤矸石是我国堆存量和排放量最大的固体废弃物之一,而砂石骨料是消耗量最大的建筑材料。制备煤矸石陶粒骨料替代天然砂石是规模化利用煤矸石的有效途径,但是高温烧制煤矸石陶粒需要研发产量大和能耗低的创新设备。带式焙烧机是冶金行业成熟的生产球团矿的工艺,具有生产率高,能耗低等特点。基于此,本文提出通过借鉴冶金带式焙烧技术烧制煤矸石陶粒的新工艺,并在504 m2球团带式焙烧机生产线上进行了煤矸石陶粒烧制的可行性验证试验,通过XRD、XRF、TG-DSC、TG-MS等分析手段研究了煤矸石陶粒在焙烧过程中的矿物转化和脱碳行为,分析了陶粒性能影响因素。结果表明:由于采用冶金球团矿焙烧制度,烧制的陶粒能够完成高岭岩转化为石英和莫来石的主要矿相转化,但是由于最高温度达到1300℃,产生了玻璃相,在冷却过程导致部分陶粒产生裂缝。陶粒的筒压强度为8.9 MPa,吸水率为9.92%,满足国家标准GBT17431.1-2010-轻集料及其试验方法对高强陶粒的要求。带式焙烧机预热段400~600℃时间较短,升温快,碳无法完全脱除,烧制完成后仍有微量残碳存在。通过延长脱碳时间、降低焙烧时间和降温速率,确定了煤矸石陶粒干燥、预热、脱碳、焙烧、缓冷和急冷6个阶段的最佳焙烧制度,进一步通过烧结杯试验进行了验证。

Coal gangue is one of the largest solid waste stockpiles and emissions in our country, while sand and gravel aggregates are the construction materials with the highest consumption. Preparing coal gangue expanded clay aggregates to replace natural sand and gravel is an effective way to utilize coal gangue on a large scale, but the high-temperature firing of coal gangue expanded clay aggregates requires the development of innovative equipment with high output and low energy consumption. The belt sintering machine is a mature production process for metallurgical pellet ore, with characteristics of high production rate and low energy consumption. Based on this, this paper proposes a new process for firing coal gangue expanded clay aggregates by referencing the metallurgical belt sintering technology, and conducted a feasibility verification experiment on the 504 m2 pellet belt sintering production line. Through analysis methods such as XRD, XRF, TG-DSC, and TG-MS, the mineral transformation and decarbonization behavior of coal gangue expanded clay aggregates during the firing process were studied, and the factors affecting the performance of the aggregates were analyzed. The results show that due to the adoption of the metallurgical pellet ore firing system, the fired aggregates can complete the main mineral phase transformation, with kaolinite transformed into quartz and mullite, but due to the maximum temperature reaching 1300°C, a glassy phase was formed, causing partial cracking of the aggregates during the cooling process. The cylinder compressive strength of the aggregates is 8.9 MPa, and the water absorption rate is 9.92%, meeting the requirements of the national standard GBT17431.1-2010 for high-strength lightweight aggregates and their test methods. The preheating section of the belt sintering machine at 400~600°C has a short residence time and rapid heating, so the carbon cannot be completely removed, and there is still a small amount of residual carbon after firing. By extending the decarbonization time, reducing the firing time and cooling rate, the optimal firing process of coal gangue expanded clay aggregates was determined, including six stages: drying, preheating, decarbonization, firing, slow cooling, and rapid cooling. Further verification was obtained through a sintering pot.