Particle shape and particle-size distribution (PSD) are important factors for pigment packing and water retention in the pigment coating process, being closely associated with many runnability problems. Diverse experimental investigations on the packing and dewatering of pigment slurries have been made. However, theoretical approaches remain lacking. This paper presents a joint experimental and theoretical analysis of the influence of pigment shape and PSD on pigment packing and dewatering. The relative viscosities of very dilute pigment slurries were measured and used to determine the intrinsic viscosity, based on the Einstein equation. The deviation of pigment shape from spherical caused an increase in viscosity of the slurries. Acicular precipitated calcium carbonates gave lower shape factor values than platy clay particles, which indicated that the needle-like particles could rotate more easily around their long axes under shearing conditions. The packing of pigments, which determines porosity, permeability, light scattering, and mechanical properties, was examined. The packing volumes of nonspherical pigments were estimated based on their respective PSDs, using an algorithm developed for spherical particles, modified with a correction factor. This model is based on the close random-packing volume fraction (\(\emptyset_{\text{p}}^{ 2}\)) of particles of uniform size being an independent variable, regardless of their shape. Therefore, it was valid as long as the particles always achieve the same close random-packing volume (\(\emptyset_{\text{p}}^{ 1}\)) by sedimentation or tapping. Overall, the effect of the particle shape and PSD on the dewatering and filter-cake permeability (K_f) was analyzed. The dewatering rates were measured with a common pressure filtration method, and the permeability of the filter cakes was obtained by fitting the data to a filtration equation. The particle size and PSD were found to influence the permeability constant, but there was little correlation between the permeability and particle shape.

颗粒形状和粒度分布（PSD）是颜料包衣过程中颜料堆积和保水性的重要因素，与许多可运行性问题密切相关。已经对颜料浆的填充和脱水进行了各种实验研究。但是，仍然缺乏理论方法。本文对颜料形状和PSD对颜料堆积和脱水的影响进行了联合实验和理论分析。基于爱因斯坦方程，测量了极稀颜料浆的相对粘度，并将其用于确定特性粘度。颜料形状与球形的偏离导致浆料粘度的增加。针状沉淀碳酸钙的形状因子值低于板状粘土颗粒，这表明在剪切条件下，针状颗粒可以更容易绕其长轴旋转。检查了决定填料的孔隙率，渗透性，光散射和机械性能的颜料堆积。非球形颜料的填充量是根据它们各自的PSD估算的，使用针对球形颗粒开发的算法，并用校正因子进行修改。该模型基于接近的随机包装体积分数（使用针对球形粒子开发的算法，并用校正因子进行修改。该模型基于接近的随机包装体积分数（使用针对球形粒子开发的算法，并用校正因子进行修改。该模型基于接近的随机包装体积分数（大小均匀的粒子的\（\ emptyset _ {\ text {p}} ^ {2} \））是自变量，而不管其形状如何。因此，只要粒子始终通过沉降或拍打达到相同的紧密随机堆积体积（\（\ emptyset _ {\ text {p}} ^ {1} \）），它就是有效的。总的来说，分析了颗粒形状和PSD对脱水和滤饼渗透率（K _f）的影响。用常规的压力过滤方法测量脱水速率，并且通过将数据拟合到过滤方程式获得滤饼的渗透性。发现粒径和PSD影响渗透率常数，但是渗透率与颗粒形状之间几乎没有相关性。