圆筒型磨机中冲击和研磨两类机制的磨矿贡献及其量化分离.pdf

圆筒型磨机中冲击和研磨两类机制的圆筒型磨机中冲击和研磨两类机制的 磨矿贡献及其量化分离磨矿贡献及其量化分离 杨晓静杨晓静 二二○○二二一年一年八八月月 博士学位博士学位 论论文文 博博 士士 杨杨 晓晓 静静 圆圆 筒筒 型型 磨磨 机机 中中 冲冲 击击 和和 研研 磨磨 两两 类类 机机 制制 的的 磨磨 矿矿 贡贡 献献 及及 其其 量量 化化 分分 离离 2021 万方数据 分类号TF19密级公开 UDC 博士学位论文博士学位论文 圆筒型磨机中冲击和研磨两类机制的 磨矿贡献及其量化分离 圆筒型磨机中冲击和研磨两类机制的 磨矿贡献及其量化分离 杨 晓 静 学科专业 杨 晓 静 学科专业化学工艺 指导教师指导教师马少健教授 论文答辩日期论文答辩日期2021.08.08学位授予日期学位授予日期2021.08.30 答辩委员会主席答辩委员会主席韩跃新 教授 万方数据 万方数据 I 圆筒型磨机中冲击和研磨两类机制的磨矿贡献及其量化分离圆筒型磨机中冲击和研磨两类机制的磨矿贡献及其量化分离 摘摘 要要 圆筒型磨机磨矿广泛应用于矿山、冶金、建材、化工等工业行业的固 体矿产资源加工，提高磨机生产处理能力和优化调节磨矿产物粒度组成对 于提高经济效益和资源回收利用率具有十分重要的意义。理论上，圆筒型 磨机磨矿过程主要通过磨机筒体的转动提升磨矿介质对被磨物料施加冲击 作用和研磨作用而使物料粒度尺寸减小，因此，磨矿介质的运动状况是影 响磨矿效果的直接和关键因素。然而，磨机运转时磨矿介质的冲击作用和 研磨作用同步并存、连续发生、分区施力、周期转化，使得两者的磨矿贡 献难以分割和独立量化表征。这一状况无疑制约了有关磨矿过程和行为的 理论解析及其“白箱”化进程，进而影响了磨矿模拟预测与优化实践。据此， 本文从成分较简单的矿物磨矿入手，以石英、磁黄铁矿、黄铁矿三种矿物 样品为研究对象，通过落重试验、研磨磨矿试验、抛落磨矿试验等方法， 结合MATLAB编程和Origin函数拟合方法，借助磨矿总体平衡动力学理论， 研究圆筒型磨机中冲击作用和研磨作用两类机制的磨矿特征以及两者在抛 落磨矿中各自磨矿贡献率的量化分离与耦合变化特征。 采用落重试验进行矿物样品冲击破碎特性研究，得到了三种矿物样品 抵抗冲击破碎能力的硬度等级结果和表征冲击破碎特性的粒能关系方程， 揭示了冲击比破碎能等因素对矿物样品破碎特性的影响规律，为磨矿总体 平衡动力学模拟提供了最直接的破碎试验基础数据。三种矿物样品的落重 万方数据 II 破碎试验结果表明，冲击破碎产物的粒度组成分布范围宽，涵盖了从“0”到 接近给料粒级尺寸的全部粒度尺寸；且冲击比破碎能存在临界值和“能垒” 效应，其他因素的影响规律受冲击比破碎能的影响。 在圆筒型磨机低速研磨磨矿试验中，通过改变给料粒度、样品种类、 磨矿时间等磨矿影响因素，研究得到研磨磨矿的产物粒度分布结果和磨矿 行为特征。结果表明，低速研磨磨矿是一个低能磨矿过程，其产物粒度组 成与冲击破碎差异很大，突出表现为产物粒级分布不均，集中“两端”，即临 近给料自身原始粒度的第二个粗粒级和-0.038 mm的微细颗粒，“磨削”特征 明显。给料粒度和矿物样品种类影响研磨磨矿行为，从磨矿产物各细粒级 生成速率看，矿物硬度越小，或给料粒级粒度越小，相同细粒级的生成速 率越大；但从给料粒级的自身破碎率看，矿物样品的破碎率及其增速与给 料粒度和矿物硬度的相关性较为复杂，没有明显的一致性规律。 在圆筒型磨机高速抛落磨矿试验中，研究得到抛落磨矿的产物粒度分 布结果和磨矿行为特征。结果表明，高速抛落磨矿是一个高能磨矿过程， 其产物粒度组成中的主要粒级数量多，粒度分布范围宽，与低速研磨磨矿 结果差异大，与冲击磨矿的产物粒度分布相近。三种矿物样品在抛落磨矿 中的破碎率与磨矿时间呈正相关增长关系，并与矿物硬度相关，磁黄铁矿 和黄铁矿破碎率接近，均大于石英，石英最难被磨碎。三种矿物样品在抛 落磨矿过程中生成各产物粒级的速度与矿物样品的硬度有关，石英磨矿产 物的生成速率始终最小，磁黄铁矿和黄铁矿的磨矿产物生成速率相对较大， 且两者的相对大小与给料粒度有关。抛落磨矿各产物粒级的生成速率均比 研磨磨矿大。 万方数据 III 基于落重试验和抛落磨矿试验结果，模拟构建了仅有冲击作用的假想 冲击磨矿及冲击磨矿总体平衡动力学模型，求解了模型参数，得到了模拟 磨矿结果。冲击磨矿模拟结果的构建方法和步骤主要包括产物粒级划分、 冲击比破碎能计算、任意相对粒度尺寸的负累积产率计算、破裂分布函数 计算、选择函数获取、总体平衡方程 Reid 解求解。研究表明，总体平衡动 力学方程的选择函数随磨矿时间的延长而呈现下降趋势，粗粒级的选择函 数比细粒级的变化显著，且选择函数随给料粒度的减小而下降。 采用磨矿技术效率作为磨矿效果表征指标，可以更好地反映磨矿目的 的实现程度。磨矿方式显著影响磨矿技术效率，其中，研磨磨矿的技术效 率显著低于冲击磨矿和抛落磨矿，抛落磨矿的技术效率最高，冲击磨矿和 抛落磨矿的技术效率更接近，变化趋势更相似。磨矿技术效率与矿物样品 硬度密切相关，大多数情况下，矿物硬度越大，其合格粒级的磨矿技术效 率越小。 按照归一化思想将冲击磨矿和研磨磨矿的磨矿技术效率耦合到抛落磨 矿的磨矿技术效率中，通过引入耦合因子建立三种磨矿方式的磨矿技术效 率数量关联关系，得到了抛落磨矿中冲击和研磨两类磨矿机制各自磨矿贡 献率的计算方法和数量结果，实现抛落磨矿中两类磨矿机制贡献率的量化 分离。研究表明，抛落磨矿中冲击作用和研磨作用的贡献率随磨矿时间变 化，总体上，冲击作用的贡献率随磨矿时间延长呈整体上升，并逐渐趋于 稳定，而研磨作用贡献率正好相反，在本文试验条件下，磨矿过程以冲击 作用贡献为主，研磨作用贡献为辅。抛落磨矿中冲击作用和研磨作用的贡 献率也与给料粒度有关，冲击作用贡献率随给料粒度的减小而降低，研磨 万方数据 IV 作用贡献率则逆向增加。抛落磨矿中冲击作用和研磨作用的贡献率会随磨 矿条件变化波动，其波动范围与矿物样品硬度有关，石英的贡献率波动范 围最小，磁黄铁矿与黄铁矿较为相近。 综上，论文首次提出在圆筒型磨机内将磨矿介质的冲击作用和研磨作 用的磨矿贡献进行量化分离表征的磨矿解析新方法，建立了集JK落重冲击 破碎、研磨磨矿、抛落磨矿等试验方法和传统磨矿动力学拟合及磨矿总体 平衡动力学模拟方法相结合的完整技术路线和试验计算步骤，实现了抛落 磨矿中冲击和研磨两类机制的磨矿贡献率的量化分离。研究成果创新了磨 矿解析的方法途径，丰富了磨矿解析理论，对磨矿模拟和优化具有重要的 方法借鉴意义和实践指导价值。 关键词关键词圆筒型圆筒型磨机磨机磨矿磨矿机制机制研磨作用研磨作用冲击作用冲击作用总体平衡总体平衡动力学动力学 磨矿磨矿模拟模拟量化量化分离分离磨矿贡献率磨矿贡献率 万方数据 V STUDY ON THE RESPECTIVE GRINDING CONTRIBUTION AND CORRESPONDING SEPARATED QUANTITATIVE CHARACTERISTICS OF IMPACTANDABRASION ACTION MECHANISMS IN CYLINDRICAL MILL GRINDING ABSTRACT The cylindrical mill is widely used in the processing of solid mineral resources in mine, metallurgy, building materials, chemical industries etc. Improving the production and processing capacity of the mill and optimizing the particle size composition of the grinding products have very important practical significance for enhancing the economic efficiency of enterprises and the resource recovery rate. Theoretically, for the cylindrical mill, the grinding is mainly driven by the rotation of the mill cylinder to enhance the impact and abrasion effects and thus the size of the materials is reduced, which indicates that the movement status of the grinding medium is the key grinding factor. However, during the running process of mill, the impact and abrasion actions synchronously coexist and continuously occur, and the two actions may rt forces in different areas and trans to each other periodically. So it is very difficult to separate and quantitative characrerize the respective grinding contributions of the impact and abrasion actions. It is obvious that this problem limits the theoretical analysis of the grinding process and behavior, as well as its 万方数据 VI white-box process, and further affects the grinding simulation prediction and optimization. Therefore, three kinds of mineral samples of quartz, pyrrhotite and pyrite with relative simple minerals composition were chosed as the research subjects to conduct the experiments of drop weight, abrasion and cataracting in this thesis. Combined with MATLAB programming and Origin function fitting , the grinding characteristics of the impact and abrasion actions in cylindrical mill, as well as the quantitative separation and coupling-change characteristics of their respective grinding contribution rates under cataracting condition were investigated by means of the population balance dynamics theory of grinding. The drop weight test was applied to investigate the impact crushing characteristics of three kinds of mineral samples and obtain the hardness grade results of the resistance to impact crushing ability and the relationship equation between the particle size and impact specific crushing energy, which revealed the influence rules of impact specific crushing energy and other factors on the crushing characteristics of mineral samples, and provided the most direct basic data of the crushing test for the population balance dynamics simulation of grinding. The drop weight test results of three kinds of mineral samples showed that the particle size compositions of the impact crushing products had a wide distribution range, covering all particle sizes from 0 to close to the size of the feed material, and impact specific crushing energy had a critical value and energy barrier effect, and the influences of other factors were affected by the 万方数据 VII impact specific crushing energy. In the low-speed grinding test of the cylindrical mill, the particle size distribution results and abrasion behavior characteristics of the grinding products were investigated by changing the grinding influence factors such as the feed size, sample type and grinding time. The results showed that low-speed grinding was a low-energy grinding process, and the product particle size composition was different from that obtained by impact crushing. The difference was highlighted by the uneven distribution of the product particle size, and the product particle size tended to distribute in the second coarse fractions near the original particle size of the feed itself and the fine fractions of -0.038 mm, which indicated that there were obvious abrasion behavior characteristics in the low-speed grinding process. The abrasion behaviors were affected by feeding particle size and mineral sample types. From the perspective of the generation rate of the fine fractions of grinding products, the smaller the mineral hardness or the feed size, the greater the generation rate of the same fine fractions. However, from the perspective of the crushing rate of the feed size, the correlation of the crushing rate and its growth rate of mineral samples with the feed size and mineral hardness were relatively complicated, and there was no obvious consistency rule. In the high-speed grinding test of the cylindrical mill, the particle size distribution and the grinding behavior characteristics of the grinding products were studied under cataracting condition. The results showed that the high-speed 万方数据 VIII grinding was a high-energy grinding process, and the product particle size was composed of a large number of main particle sizes and distributed in a wide particle size range. This suggested that there were significant difference between the high-speed and low-speed grinding processes in the product particle size compositions, while the product particle size distribution under high-speed grinding was similar to that obtained by impact grinding. The breakage rates of the three kinds of mineral samples under cataracting condition were positively correlated with the grinding time, and also related to the mineral hardness. The breakage rates of pyrrhotite and pyrite were similar, both of which were larger than that of quartz, and quartz was the most difficult to be ground by comparison with the other two minerals. The generation speeds of each product size of the three kinds of mineral samples under cataracting condition were related to the hardness of the mineral samples. The generation rate of each grinding product size of quartz was always the smallest, while the generation rate was relatively large for pyrrhotite and pyrite, and the relative sizes of the two were related to the feed size. The generation rate of each product size under cataracting condition was higher than that of the abrasion grinding. Based on the results of the drop weight and cataracting test, a hypothetical impact grinding and its population balance dynamic model with only impact action were constructed, and the simulated grinding results were obtained by solving the model parameters. The construction s and steps of simulation results of impact grinding mainly included the size grade classification of 万方数据 IX grinding products, the calculation of impact specific crushing energy, negative cumulative yield of any relative particle size and fracture distribution function, as well as the acquisition of selection function and Reid solution of the population balance equation. The results indicated that the selection function of the population balance kinetic equation showed a declining trend with the increase of grinding time. The selection function of the coarse fractions of the grinding products changed dramatically by comparison with the fine fraction, and the selection function decreased with the decrease of the feed size. Using the grinding efficiency as the indicator of the grinding effect could better reflect the achievement degree of the grinding purpose. The grinding efficiency was remarkably affected by the grinding s. Among them, the efficiency of abrasion was obviously lower than that of the grinding under impacting and cataracting condition. The grinding efficiency under cataracting condition was the highest, while the grinding efficiencies under impacting and cataracting condition were closer and the change trends were also more similar. The grinding efficiency was closely related to the hardness of mineral samples. In most cases, the greater the hardness of the mineral, the lower the grinding efficiency of the qualified particle size. According to the normalization , the total contribution rates of the impact and abrasion actions must be equal to 100 for the grinding effects of any particle size in actual grinding process, and the grinding efficiencies of impact and abrasion actions were coupled to the grinding efficiency under 万方数据 X cataracting condition. The quantitative relationship of the grinding efficiency of the three grinding s was established by introducing the coupling factor, and the calculation s and quantitative results of the respective contribution rates of the impact and abrasion actions under cataracting condition were obtained, which would achieve the quantitative separation of the contribution rates of the two kinds of grinding actions under cataracting condition. Studies showed that the contribution rates of impact and abrasion actions under cataracting condition varied with grinding time. In general, the contribution rate of the impact action increased with the increase of grinding time, and gradually tended to be stable, while the contribution rate of abrasion action decreased with the increase of grinding time. Under the experimental conditions of this thesis, the impact action was the dominant contribution during the grinding process followed by the abrasion action. The contribution rates of the impact and abrasion actions under cataracting condition were also related to the feed size. The contribution rate of impact action decreased with the decrease of feed size, while the contribution rate of abrasion action increased inversely. The contribution rates of impact and abrasion actions under cataracting condition would fluctuate with the change of grinding conditions, and the fluctuation range was related to the hardness of the mineral sample. The respective contribution rates of impact and abrasion actions of quartz had the smallest fluctuation range, and for pyrrhotite and pyrite, the fluctuation ranges were relatively similar. 万方数据 XI In a word, a new grinding analysis for quantitatively separating and characterizing the contribution rates of impact action and abrasion actions in the cylindrical mill was firstly proposed in this thesis. The complete technical route and test calculation steps that combined the test s such as JK drop weight impact crushing, abrasion action and cataracting with the traditional dynamics fitting and population balance dynamics simulation of grinding were established, which could realize quantitative the separation of contribution rates of the impact and abrasion actions under cataracting condition. The research results have innovated the and approach of grinding analysis and enriched the theory of grinding analysis, which had important referential significanceandpracticalguidingvalueforgrindingsimulationand optimization. KEY WORDS cylindrical grinding mill; grinding mechanisms; abrasion action; impact action; population balance dynamics; grinding simulation; quantitative separation; grinding contribution rate 万方数据 XII 目 录 摘 要...........................................................................................................................................I ABSTRACT...............................................................................................................................V 目 录.......................................................................................................................................XII 第一章 绪 论.............................................................................................................................1 1.1 磨矿概述........................................................................................................................1 1.2 磨矿介质运动理论........................................................................................................1 1.2.1 磨矿介质在磨机中的运动形态理论..................................................................1 1.2.2 磨矿介质运动学研究..........................................................................................4 1.3 传统磨矿动力学............................................................................................................5 1.3.1 磨矿动力学模型..................................................................................................5 1.3.2 磨矿动力学研究进展.................................................................................