Costa Ana R D, Coppe Mateus V, Bielefeldt Wagner V, Bernal Susan A, Black Leon, Kirchheim Ana Paula, Gonçalves Jardel P
Polytechnic School, Post-Graduate Program in Civil Engineering (PPEC), Federal University of Bahia (UFBA), Salvador, 40210-630, Brazil.
School of Civil Engineering, University of Leeds, Leeds, LS2 9JT, UK.
Sci Rep. 2023 Oct 16;13(1):17589. doi: 10.1038/s41598-023-44078-7.
The valorisation of waste or by-products in Portland clinker production is a promising alternative for developing sustainable cements. The complexity of the chemical reactions during clinkering demands an adequate dosing method that considers the effect of feedstock impurities to maximise the potential substitution of natural resources by waste or by-products, while guaranteeing the clinker reactivity requirements. This study proposes a raw meal proportioning methodology for optimising co-processing of natural feedstocks with alternative raw materials in clinker production, intending to reduce the content of natural raw materials needed, while promoting an optimal clinker reactivity. A thermodynamic modelling sequence was developed considering the variability of raw materials composition and heating temperatures. The model was then validated by comparing simulation outcomes with results reported in previous studies. An experimental case study was conducted for validation of the proposed method using a spent fluid catalytic cracking catalyst (SFCC), a by-product from the oil industry as an alternative alumina source during clinkering. The modelling simulations indicated that substitution of natural feedstocks by 15 wt% SFCC promotes the formation of reactive clinkers with more than 54% tricalcium silicate (CS). Mixes with the potential to form the highest CS were then produced, and heating microscopy fusibility testing was applied for evaluating the clinkers' stability. The main factors governing the reactivity and stability of the clinker phases were the melt phase content, alumina modulus, and formation of CS and dicalcium silicate (CS). The self-pulverisation of clinker during cooling was observed in selected mixes, and it is potentially associated with high viscosity and low Fe content in the melt phase. The proposed framework enables optimisation of the dosing of raw meals containing alternative alumina-rich feedstocks for clinker production and allows a deeper interpretation of limited sets of empirical data.
在波特兰熟料生产中对废物或副产品进行增值利用是开发可持续水泥的一种有前景的替代方法。熟料煅烧过程中化学反应的复杂性需要一种适当的配料方法，该方法要考虑原料杂质的影响，以最大限度地利用废物或副产品替代自然资源，同时保证熟料反应活性的要求。本研究提出了一种生料配料方法，用于优化熟料生产中天然原料与替代原料的共处理，旨在减少所需天然原料的含量，同时促进最佳的熟料反应活性。考虑到原料成分和加热温度的变化，开发了一个热力学建模序列。然后通过将模拟结果与先前研究报告的结果进行比较来验证该模型。进行了一个实验案例研究，以验证所提出的方法，该方法使用废流化催化裂化催化剂（SFCC），一种石油工业副产品作为煅烧过程中的替代氧化铝来源。建模模拟表明，用15 wt%的SFCC替代天然原料可促进形成具有超过54%硅酸三钙（CS）的活性熟料。然后制备了具有形成最高CS潜力的混合料，并应用加热显微镜熔融性测试来评估熟料的稳定性。控制熟料相反应活性和稳定性的主要因素是熔体相含量、铝氧率以及CS和硅酸二钙（CS）的形成。在选定的混合料中观察到熟料在冷却过程中的自粉化现象，这可能与熔体相中高粘度和低铁含量有关。所提出的框架能够优化含有替代富铝原料的生料配料以用于熟料生产，并能更深入地解释有限的经验数据集。
