Rajaonarivony Rova Karine, Rouau Xavier, Fabre Charlène, Mayer-Laigle Claire
IATE, Université de Montpellier, INRAE, Montpellier SupAgro, Montpellier, 34060, France.
Open Res Eur. 2022 Mar 16;1:125. doi: 10.12688/openreseurope.14017.2. eCollection 2021.
Lignocellulosic biomass has many functionalities that hold huge potential for material, energy or chemistry applications. To support advanced applications, the biomass must be milled into ultrafine powder to increase reactivity. This milling unit operation needs to be fully mastered to deliver high-quality standard end-products. Here we studied the relationship between the characteristics of the starting lignocellulosic plant material and the properties of the resulting ultrafine powder in different ball-mill process routes. Two lignocellulosic biomasses (pine bark and wheat straw) with contrasted compositional and mechanical properties were milled using three ball-mill set-ups delivering different balances of impact force and attrition force. The resulting powders were analysed for particle characteristics (size, agglomeration extent, shape) and powder flow properties (compressibility, cohesion) using a dynamic powder rheometer. : Pine bark is more amenable to a fast particle size reduction than the fibrous wheat straw. The resulting pine bark powders appear less compressible but much more cohesive than the straw powders due to particle shape, density and composition factors. The mill set-up working by attrition as dominant mechanical force (vibratory ball mill) produced a mix of large, elongated particles and higher amounts of fines as it acts mainly by erosion, the resulting powder being more prone to agglomerate due to the abundance of fines. The mill set-up working by impact as dominant mechanical force (rotary ball mill) produced more evenly distributed particle sizes and shapes. The resulting powder is less prone to agglomerate due to a preferential fragmentation mechanism. The attrition-dominant mill yields powders with dispersed particle sizes and shapes and the poorest flow properties, while the impact-dominant mill yields more agglomeration-prone powders. The mill set-up working with impact and attrition as concomitant mechanical forces (stirred ball mill) produces powders with better reactivity and flow properties compared to rotary and vibratory mills.
木质纤维素生物质具有多种功能，在材料、能源或化学应用方面具有巨大潜力。为了支持先进应用，必须将生物质研磨成超细粉末以提高反应活性。需要充分掌握这种研磨单元操作，以提供高质量标准的最终产品。在此，我们研究了起始木质纤维素植物材料的特性与不同球磨工艺路线中所得超细粉末性能之间的关系。使用三种提供不同冲击力和磨蚀力平衡的球磨装置，对两种具有不同组成和机械性能的木质纤维素生物质（松树皮和小麦秸秆）进行了研磨。使用动态粉末流变仪对所得粉末的颗粒特性（尺寸、团聚程度、形状）和粉末流动性能（压缩性、内聚性）进行了分析。结果表明：与纤维状的小麦秸秆相比，松树皮更易于快速减小颗粒尺寸。由于颗粒形状、密度和组成因素，所得松树皮粉末的压缩性似乎较小，但内聚性比秸秆粉末大得多。以磨蚀作为主要机械力的球磨装置（振动球磨机）产生了大的、细长颗粒的混合物以及大量细粉，因为它主要通过侵蚀作用，所得粉末由于细粉含量高而更容易团聚。以冲击作为主要机械力的球磨装置（旋转球磨机）产生的颗粒尺寸和形状分布更均匀。由于优先破碎机制，所得粉末不太容易团聚。以磨蚀为主的球磨产生的粉末颗粒尺寸和形状分散，流动性能最差，而以冲击为主的球磨产生的粉末更易团聚。与旋转球磨机和振动球磨机相比，以冲击和磨蚀作为伴随机械力的球磨装置（搅拌球磨机）产生的粉末具有更好的反应活性和流动性能。
