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1.
In the grinding of paracetamol, lactose and sucrose in a vibratory ball mill, it is found that an equilibrium is rapidly attained due to the agglomeration of ground particles. The existence of this agglomerative phase of comminution has been extensively reported in the literature. This study investigates prolonged vibratory ball milling as a means of pharmaceutical granulation. The granules are produced from the agglomeration of very fine particles and become more compacted as comminution proceeds. 相似文献
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I. S. Kainarskii É. V. Degtyareva G. E. Kalita 《Refractories and Industrial Ceramics》1977,18(5-6):360-365
Conclusions Suspensions of alumina wet-ground and dry-ground in a ball mill are characterized by viscosity changes typical for firm systems with static {ie365-01} and dynamic (Bingham) {ie365-02} fluidity limits.These suspensions are thixotropic; the viscositygh
m of their fully broken up structure is higher and their zeta potential lower than for suspensions of vibro-ground alumina, the explanation being the considerably longer grinding time in a ball mill and the fact that in wet grinding a vigorous interaction proceeds between the solid and liquid phases directly in the grinding process.Alumina wet-ground in a ball mill contains more impurities after washing than alumina dry-ground in a vibro mill. The suspension of the former gives a faster rate of casting but the density and strength of the product are lower.Fired commercial alumina to be used for the production of high-quality dense-sintered refractory corundum ceramics should be dry-ground in a vibratory mill.Translated from Ogneupory, No. 6, pp. 44–51, June, 1977. 相似文献
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几种典型水泥粉磨系统的比较 总被引:1,自引:0,他引:1
水泥粉磨系统已由早先的球磨机系统逐步发展到现在的球磨机+辊压机系统和立磨系统。通过分析流程和主要配置及运行参数,归类出比较典型的七种水泥粉磨系统的技术性能持点。其中,立磨终粉磨系统流程最简单,能耗最低,是水泥粉磨方案的首选;辊压机+球磨(带涡流选粉机)组成的联合粉磨系统及立磨和球磨组成的联合粉磨系统流程相近,能耗相近,可作为水泥粉磨系统的优选方案;辊压机和球磨机组成的开流及半开流系统缺点最多,应尽量避免选用。 相似文献
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Jürgen Raasch 《化学工程与技术》1992,15(4):245-253
The motion of grinding bodies in conventional ball mills has been repeatedly investigated, both theoretically and experimentally. It is well-known that, depending on mill filling and speed of rotation, different motion patterns occur and some of these patterns, especially that of cataracting, can be described by simplified theories. This contribution presents such a theory of the cataracting motion of grinding bodies in a planetary ball mill. An analytical method for the evaluation of trajectories is given which permits an iterative calculation of the time and impact location of the grinding bodies on mill shell or mill filling. This leads to the determination of the impact velocity of grinding bodies and its component normal to the mill shell. On the assumption that this component is decisive for the grinding effect, conditions for an optimal design of a planetary ball mill are deduced. 相似文献
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球磨机研磨体合理的级配,对提高磨机产量和产品质量、降低粉磨电耗,具有重大的作用。在总结几百家水泥厂磨机工艺技术员工作经验的基础上,根据笔者长期从事物料粉磨研究和实践的心得体会,综合考虑研磨体总装载量、各仓填充率、平均球径、物料水分、物料流动性、物料粒度、隔仓板形式、隔仓板篦缝大小、各仓长度、粉磨流程等因素,详细介绍了球磨机研磨体级配计算的方法、原理和步骤,并编制成“球磨机研磨体级配及补球计算程序”软件。 相似文献
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在钙镁磷肥半成品加工生产过程中,为了使磨机的粉碎效率高,只单纯考虑研磨体的装载量是不够的,还必须确定研磨体的规格及用量,即研磨体的级配.介绍研磨体级配的平均球径与研磨物料平均粒径的关系. 相似文献
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This article presents the innovative grinding apparatus Pulsar in which comminution is caused by impact of a particle plug on an impact plate. Advantages of the Pulsar principle in comparison to other types of mills are discussed. The aim of the work is to classify the Pulsar system in the field of grinding apparatus and machines in terms of energy consumption. Experiments were carried out in a Pulsar, a cross beater mill and a ball mill for comparison purposes. The results show that, for the material quartz sand, grinding in the Pulsar at a medium pressure of compressed air (pcar,i = 7.5 bars) and a medium magnetic valve opening time (to = 70 ms) is as efficient as in the ball mill. The grinding energy consumption of both mills, the Pulsar and the ball mill, is remarkably higher than that of the cross beater mill. 相似文献
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The conventional model for grinding in tumbling ball mills was modified to allow for air-sweeping, for the case where all the material is carried out of the mill in the air stream. It was shown that this type of mill can be treated as a single fully mixed reactor. The values of the internal classification numbers given by the air-sweeping were determined for a 1 m by 1.5 m pilot-scale mill grinding coal. The results showed that only 1 to 2% of the mill charge are exposed to the sweeping action per mill revolution. S and B values determined in a laboratory mill were scaled-up for use in the continuous mill model and the simulations gave product size distributions and mill capacities which agreed with the pilot-scale mill data within the experimental accuracy of the pilot-scale data. 相似文献
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Previous investigations have shown that the specific energy input is the overall parameter of influence on product size during communition in agitated ball mills, from laboratory up to industrial scale. The specific energy input is the introduced energy related to the amount of comminuted material. This parameter can be used for mill scale-up. Consequently, a method had to be found of introducing power into the mill so as to obtain a given specific energy input. For this purpose, stirring tests with purely Newtonian liquids were carried out in absence of solids and hence, without comminution. Mathematical models are presented which describe the power consumption in agitated ball mills in absence of grinding beads. In addition, tests with grinding beads filling were also performed, leading to scale-up guidelines with respect to power consumption. Finally, the influence of size and material of grinding beads was investigated. 相似文献
14.
Stirred ball mills are frequently used for ultrafine- and nanogrinding in food, pharmaceutical and chemical industry, but only few investigations have been published on empirical or scale-up modeling of stirred ball mills. Experiments have been carried out with a laboratory scale stirred ball mill. During the experiments the main technical parameters such as stirrer speed, grinding media, filling ratio, grinding time and the solid mass concentration have been systematically adjusted. The particle size distribution of mill products can be well estimated by empirical functions, so an empirical model has been prepared for the laboratory mill. The relation between the grinding fineness, grinding time and specific grinding work was represented for several materials such as pumice, andesite, limestone and tailings of ore mining industry. The power consumption of the stirred ball mill for scale-up was determined by a method based on the dimensional analysis. A new scale-up model has been presented as well by with industrial size stirred ball mills can be designed on the basis of the laboratory measurements. 相似文献
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For dry ball mill grinding operation, the effect of ball and mill diameters on grinding rate parameters of the size-discretized population balance model has been investigated for quartz, limestone, a soft cement clinker and a hard cement clinker. Experiments were performed in three mills of 29.2, 40.6 and 61.0 cm diameter. The diameter of the balls used ranged from 1.27 to 3.81 cm. The particle size range covered was to mesh. The rate parameter values were determined very accurately using a special technique. It has been shown that the particle size exponent α in equation Si = Axiα is independent of ball and mill diameters. Based on this fact, a new correlation has been developed to describe the effect of ball and mill diameters on the rate parameters. The various constants in this correlation are strongly material dependent. 相似文献
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The influence of grinding technique on the liberation of clinker minerals and cement properties 总被引:1,自引:0,他引:1
This paper describes a study of the relationship between the physical, chemical and mineralogical parameters of cement products obtained by different grinding mechanisms namely high pressure grinding rolls (HPGR) and ball milling, and their effects upon the properties of cements prepared from the ground clinker. Samples were prepared as narrow size fractions and also as distribution samples. Characterization parameters were ascertained by using XRF, laser sizing, Blaine and BET surface area and image analysis methods. HPGR grinding resulted in higher degrees of liberation of clinker phases arising from the intergranular breakage along the grain boundaries compared to ball mill grinding. As for service properties, water demand of HPGR products was higher than ball mill products resulting from high micro fissured structure. Despite high liberation of particularly alite mineral in HPGR grinding, the compressive strength of ball mill products was slightly higher than HPGR products for narrow size samples. Finally, particle size distribution effect on strength was more obvious for distribution samples; generally ball milling gave higher strength values. 相似文献
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Changes in the structure of hematite by extended dry grinding in relation to imposed stress energy 总被引:1,自引:0,他引:1
The effect of extended dry milling in different mills on the structural changes of hematite concentrate has been investigated using a combination analysis of XRD line broadening, BET and particle size measurements. Structural changes were followed by XRD line broadening analysis using integral breadth method and Warren-Averbach approach. For analysis, the stress energy was estimated by considering different grinding variables in different mills and changes in the structure discussed in terms of stress energy.Within comparable range of stress energy, lower BET surface area was produced by grinding in the vibratory mill. The maximum surface area increased to 18,400 m2/kg in the vibratory mill after releasing 51,300 kJ/kg energy. The conversion of the 80% of initial hematite to amorphous phase during extended dry grinding by tumbling, planetary and vibratory mills, needs 4000, 8500 and 50,000 kJ/kg energy respectively. It was understood that vibratory mill introduces the minimum lattice strain and gives the largest crystallites when applying the same level of stress energy. The smallest crystallites with grinding in tumbling, vibratory and planetary mills were obtained about 17.3, 13.5 and 5.6 nm after releasing 5230, 51,300 and 15,600 kJ/kg respectively. For these levels of stress energy, in turn, the microstrain <εL=10 nm2>1/2 exceeds 4.4 × 10− 3, 3.9 × 10− 3 and 5.3 × 10− 3.It was further revealed that higher concentrations of defects (Amorphization and excess energy) per unit surface area were induced by grinding in the planetary and tumbling mills. A theoretical calculation of the energy contribution to the long-lived defects indicated that products from tumbling and planetary mills have higher excess energy compared to the products from vibratory mill for the same stress energy. The maximum theoretical excess energy was estimated about 75.4, 80.0 and 81.3 kJ per mole of the ground hematite with tumbling, vibratory and planetary mills after releasing 5230, 51,300 and 15,600 kJ/kg of stress energy respectively. Grinding in vibratory mill needs much more energy to reach the same effect as the other used mills. A comparison of specific energy input and stress energy among the used mills points out that for generation of the same levels of stress energy, the planetary mill consumes more energy than the other used mills. 相似文献
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Flaky metal powders commonly used as paint and pigments, are generally produced by grinding in ball mills or vibration mills. The key to good quality powder production is to optimize the processing parameters. In the present work grinding of brass particles is studied in detail in a laboratory size ball mill to determine the optimal levels of the ball to material ratio, type and amount of additives, mill speed, ball load, etc. The quality of the powder is assessed on the basis of water coverage, degree of flattening and luster by visual inspection. Preliminary results in a 35 cm diameter ball mill with 30% ball load show that a material to ball ratio of 0.067 with a 0.1% dosage of stearic acid is required for good quality powder. For determining optimal mill speed and ball size a 22 factorial design of experiment has been followed. It has been determined that to achieve best powder quality the mill must run at 70% critical speed and the ball size must not exceed 20 mm. The quality of the powder assessed through SEM study for surface morphology and particle size analysis compares very well with the industrial samples. 相似文献
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介绍了倒频谱分析的基本原理及在齿轮减速箱故障诊断中的应用.鉴于球磨机齿轮减速箱振动信号中调制源多、频率成分复杂,功率谱中存在大量的非对称边频带及周期性结构信号导致故障识别工作困难的问题,运用倒频谱分析法对其进行故障诊断,它能将功率谱上成族的边频带谱线简化为单根谱线,分离和提取出密集泛频信号中的周期成分、多成分边频,快速准确诊断球磨机齿轮减速箱中零件的故障. 相似文献
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球磨质量与内衬结构形式的探讨 总被引:1,自引:0,他引:1
对采用异形砖砌筑球磨机筒体内衬成两端具有曲面过渡及柱面不连续螺旋复合的新结构形式,进行了球磨釉料的实验。实验结果表明,在相同条件下,新结构内衬球磨机球磨所得釉浆粗颗粒含量较少,颗粒分布范围较窄,颗粒质量优于普通内衬球磨机。同时就8t等大规格球磨机球磨釉料的可行性作了分析讨论。 相似文献