Nie Donggen, Li Wei, Xie Lilan, Deng Min, Ding Hao, Liu Kaiwei
College of Material Science and Engineering, Nanjing Tech University, Nanjing 211816, China.
Anhui Province Key Laboratory of Advanced Building Materials, Anhui Jianzhu University, Hefei 230000, China.
Materials (Basel). 2024 Jul 21;17(14):3601. doi: 10.3390/ma17143601.
With the increasing depletion of high-quality raw materials, siliceous limestone, sandstone and other hard-to-burn raw materials containing crystalline SiO are gradually being used to produce clinker. This study investigates the influence of the quartz content and particle size in siliceous limestone on the calcination process and the resultant quality of cement clinker. Two different siliceous limestones were grinded to different fineness, and calcinated with some other materials. The content of the clinkers was analyzed with the XRD-Rietveld method and the microstructure of the clinkers was observed with laser scanning confocal microscopy (LSCM) and field emission scanning electron microscopy (FESEM). Three key outcomes of this study provide new insights on the use of siliceous limestone in cement production, namely that (i) reducing the fineness values of siliceous limestone from 15% to 0% of residue on a 0.08 mm sieve decreases the quantity of these larger quartz particles, resulting in an increase in CS content by up to 8% and an increase in 28d compressive strength by up to 4.4 Mpa, which is 62.30 Mpa; (ii) the morphology of quartz-either as chert nodules or single crystals-affects the microstructure of CS clusters in clinker, finding that chert nodules result in clusters with more intermediate phases, whereas large single crystals lead to denser clusters; (iii) the sufficient fineness values of siliceous limestone SL1 and SL2 are 5% and 7% of residue on a 0.08 mm sieve, respectively, which can produce a clinker with a 28d compressive strength greater than 60 Mpa, indicating that for different kinds of quartz in siliceous limestone, there is an optimum grinding solution that can achieve a balance between clinker quality and energy consumption without having to grind siliceous limestone to very fine grades.
随着优质原材料的日益枯竭，硅质石灰石、砂岩等含有结晶二氧化硅的难烧原材料逐渐被用于生产熟料。本研究调查了硅质石灰石中石英含量和粒度对煅烧过程及水泥熟料最终质量的影响。将两种不同的硅质石灰石粉磨至不同细度，并与其他一些材料一起煅烧。采用XRD - Rietveld方法分析熟料的含量，并用激光扫描共聚焦显微镜（LSCM）和场发射扫描电子显微镜（FESEM）观察熟料的微观结构。本研究的三个关键结果为硅质石灰石在水泥生产中的应用提供了新的见解，即：（i）将硅质石灰石在0.08 mm筛上的残留量细度值从15%降至0%，可减少这些较大石英颗粒的数量，使C₃S含量增加高达8%，28天抗压强度增加高达4.4 Mpa，达到62.30 Mpa；（ii）石英的形态（燧石结核或单晶）会影响熟料中C₃S簇的微观结构，发现燧石结核会导致簇中有更多中间相，而大单晶会导致簇更致密；（iii）硅质石灰石SL1和SL2的足够细度值分别为0.08 mm筛上残留量的5%和7%，可生产出28天抗压强度大于60 Mpa的熟料，这表明对于硅质石灰石中的不同种类石英，存在一种最佳粉磨方案，能够在熟料质量和能耗之间实现平衡，而无需将硅质石灰石粉磨至极细程度。
