Combination of Different Size Distributions for Mineral Particles by Applying Experimentally Determined Apparent Mean Shape Factor

As is well known, the behavior of systems of fine particles is strongly dependent on the size of the individual particles, and the size effects become increasingly important as the particles become progressively smaller. This study covers two different size analysis techniques, sieving and laser diffraction measurement, and constructs whole size distribution for different mill (ball and rod) products of some industrial minerals: barite and quartz minerals. A smooth overlap of corrected laser diffraction size distribution and sieve size distribution was obtained by applying the particle size with the apparent mean shape factor shifting to the right side of the curve for the rod-milled barite and ball- and rod-milled quartz. The apparent mean shape factors determined from the corrected particle size distributions were found to be 1.02 and 1.39 for ball- and rod-milled barite and 1.29 and 1.25 for ball- and rod-milled quartz, respectively. The results indicate that the ball-milled products of barite mineral have more regular (rounder in shape) particles than those of rod-milled barite, but there are not significant differences between the shape factors of ball- and rod-milled products of quartz mineral, i.e., both of them have irregular particles that deviate from spherical shape, as evident from the SEM pictures taken.     

Combination of Different Size Distributions for Mineral Particles by Applying Experimentally Determined Apparent Mean Shape Factor

As is well known, the behavior of systems of fine particles is strongly dependent on the size of the individual particles, and the size effects become increasingly important as the particles become progressively smaller. This study covers two different size analysis techniques, sieving and laser diffraction measurement, and constructs whole size distribution for different mill (ball and rod) products of some industrial minerals: barite and quartz minerals. A smooth overlap of corrected laser diffraction size distribution and sieve size distribution was obtained by applying the particle size with the apparent mean shape factor shifting to the right side of the curve for the rod-milled barite and ball- and rod-milled quartz. The apparent mean shape factors determined from the corrected particle size distributions were found to be 1.02 and 1.39 for ball- and rod-milled barite and 1.29 and 1.25 for ball- and rod-milled quartz, respectively. The results indicate that the ball-milled products of barite mineral have more regular (rounder in shape) particles than those of rod-milled barite, but there are not significant differences between the shape factors of ball- and rod-milled products of quartz mineral, i.e., both of them have irregular particles that deviate from spherical shape, as evident from the SEM pictures taken.     

激光粒度仪颗粒联测的结果与评价

为了解不同激光粒度仪的硬件、软件等方面差异对粒度测量结果的影响,用4种颗粒形状不同的粉末在不同公司生产的激光粒度仪上进行测试。结果表明:激光粒度仪测试结果重复性很好;对于球形粉末和形状较规则的粉末,大部分激光粒度仪测得的中位径值之间可以比较;而粒径范围较宽和不规则形状粉末,个别仪器测量的中位径值有差异。     

石墨微粉形状参数分布的研究

采用激光衍射法和沉降法的粒度分析结果,研究了石墨微粉颗粒的形状及其参数分布,给出了３ 种石墨微粉产品的长径比随粒径变化的分布曲线。通过对曲线的分析,可提取与颗粒制备机理有关的信息。本文从一个角度证明了颗粒的粒度分析与形状分析是相互影响、相互依存、不可分割的整体     

粒子尺寸分布的激光衍射测量研究

提出了用于喷雾雾化分析和固体粉末粒子的激光粒度分析仪的设计原则。给出了进行粒子测试的数学模型,编制了系统软件。用实际设计的仪器进行了喷雾雾化分析和流化床催化剂粒度测量,证明了所提出的设计原则的正确和该仪器研制的成功。     

不同方法测试粒度分布的比较研究

介绍了不同原理仪器粒度测试结果间存在差异的原因以及对测试结果准确性应如何评价。用筛分法和激光法对氧化铝样品进行测试对比,初步分析结果间的差异。结果表明,筛分法和激光法测试粒度分布在质量(体积)累积分布达到50%时,测试结果相差最小,不同的粒度组成、颗粒的形状都会造成两种方法测试结果的差异。     

激光粒度法测试结果与库尔特法、沉降法的比较

分别采用马尔文激光粒度仪、库尔特颗粒粒度计数仪、岛津离心粒度分析仪对玻璃微珠、聚苯乙烯微球、钨粉、氧化铝微粉、二氧化硅微粉等6种不同类型的粉末进行了测试,并对几种测试方法所得的结果进行比较。结果表明:激光法测试的结果重复性较好;对于粒径范围窄的球形粉体,几种仪器测得的中位径具有可比性,粒度分布曲线也相似;对于粒径范围较宽的球形粉体和不规则形状粉体,测得的中位径和粒度分布曲线一般没有可比性。     

Image analysis algorithm and verification for on-line molecular sieve size and shape inspection

An online machine vision inspection method is proposed to implement feedback control of molecular sieve growth process in rotary drum granulation. An experimental platform, comprising of a high-resolution digital camera and an image analysis system, has been developed to confirm the validity of the method on particle size distribution (PSD) and sphericity measurements. Experiments were performed with non-uniform molecular sieve particles (1–3 mm diameter) obtained from production line. The particle images are first obtained through digital camera and are then processed by image analysis system. After separating the overlap particles and removing non-target particles of the images, the molecular sieve size and shape are computed in less than 0.9 s. The validity of the size measuring accuracy is confirmed through comparing with the results from micrometer. The experimental results show that the repetitive precision of the proposed inspection system is about ±1%, the diameter measurement error between image method and micrometer is about ±3%, single image inspection speed is around 0.9 s/frame. The proposed method is reliable to provide feedback information for control system in rotary drum granulation.     

超细OAK木炭及竹炭粉粒度测定方法的研究

采用激光粒度分析法测定超细OAK木炭及竹炭粉粒度,探讨了分散剂种类、分散时间、搅拌速度、超声时间等因素对超细OAK木炭及竹炭粉粒度的影响.结果表明:以六偏磷酸钠为分散剂时分散效果最佳,其用量为0.06g/(100mlOAK木炭及竹炭粉乳液);在测定时选择循环搅拌泵速为2200～2400r/min较好;超声时间为200s左右时,可达到最佳分散效果.     

Comparison of Particle Size Distributions Measured Using Different Techniques

In this article, particle size distributions (PSDs) measured by different techniques, including image analysis (IA), laser diffraction (LD), ultrasonic attenuation spectroscopy (UAS), and focused-beam reflectance measurement (FBRM), are compared for spherical glass beads and nonspherical silica flakes. It is shown that particle shape strongly affects the results obtained by different techniques. For spheres, the PSDs obtained by IA, LD, and UAS agree well. There is no consistent result among different particle measurement techniques for nonspherical particles. The conversion between PSDs obtained by IA, LD, and UAS has been based on particle shape factors. Caution must be exercised when a measured chord length distribution (CLD) is used to indicate the PSD during a process because the CLD result obtained by FBRM is complex, depending not only on the PSD, but also on particle optical properties and shape.     

Machine Vision for Size Distribution Determination of Spherically Shaped Particles in Dense-Granular Beds,Oriented to Pelletizing Process Automation

A machine vision has been devised for determination of the size distribution of spherically shaped pellets in granular beds under static and dynamic conditions. This machine vision involved establishing the optimal distance between the illumination source and the top layer of the granular bed, as well as the development of the data image acquisition software and control systems, I/O interface hardware, and electromechanical system. The size distribution of pellets given by the whole system gives an error lower than 5% for pellets. The size distribution histogram or the Sauter diameter of the pellets given by the vision system is used as the input signal for controlling an electromechanical scanning device, which can be reliably used for automation tasks. The system software was developed for open access on a commercially widely used platform. As the machine vision is robust, it can be used in industrial environments and it has the potential to contribute in improving and optimizing pelletizing industrial processes. This machine vision is reliable, flexible, user friendly, inexpensive, and easy to implement.     

激光粒度分析和筛分法测粒径分布的比较

分别采用筛分法和马尔文激光粒度分析仪两种方法对16种颗粒的粒径分布进行了测量。通过比较,发现两种测量手段得到的粒径分布结果存在较大的差异,马尔文激光粒度方法对颗粒粒径的测量结果偏小,受颗粒形状的影响很大;筛分法对微细颗粒的测量误差较大,但对大粒径颗粒的测量较为准确。通过对不同粒径段灰颗粒的显微照相,发现细颗粒的团聚是筛分法测量小颗粒结果偏小的主要原因。     

两种粒度分布测定方法的对比分析

采用激光粒度仪和国标两种分析方法,测试了4A沸石样品的粒度分布。通过实验,得到了优选的激光粒度仪测试条件为:循环泵的转速为2 000 r/min、超声时间5 min、停留时间1 min≤t≤5 min。结果表明:在此条件下,小于4μm的颗粒所占体积分数为99.29%左右,并与国家标准QB/T 1768—2003的测试结果进行了比较,两种分析方法的结果相差约0.4%。在用实际产品检验后,对这两种测试方法进行了分析和讨论。     

Mastersizer 2000型激光粒度仪技术参数对粒度分布的影响

根据英国马尔文Mastersizer 2000型激光粒度仪的特点,探讨不同技术参数对样品粒度分布测试结果的影响。结果表明,影响样品粒度分布的主要参数为样品量(检测遮光度)、采集时间、循环速度、检测光源波长、反演光学模型及数学模型等;对于状态不明确的未知样品,应借助其他检测技术进行样品状态表征后,选择合理的光学模型和数学模型进行粒度测试。