A statistical approach for estimation of significant variables in wet attrition milling

Production of ultrafine particles by grinding in attritor mill has been successfully applied in chemical, pharmaceutical and mineral processing industries. It has also been demonstrated as a cost effective and efficient method for production of nanoparticles. The present study attempts to relate the effects of operating variables on the Rosin Rammler equation parameter (X_d), which is indicative of the size of product. Operating parameters considered for the investigation are initial size of particles, ball loading, slurry mass fraction, diameter of grinding media, pin tip velocity and ratio of Young's modulus. The results indicate that the ratio of Young's modulus and initial size of particles have significant effects; ball loading, diameter of grinding media and pin tip velocity have moderate effects; and slurry mass fraction does not have a significant effect on the final size of the powder. The paper illustrates how statistical analysis, when appropriately applied, can be used to analyze complex unit operations such as the attritor mill and can be effective in gathering of process understanding.     

纳米磷酸锌的可控合成

在氧化锌、磷酸固-液反应体系中,以研磨反应代替搅拌反应,辅助表面活性剂对磷酸锌的颗粒尺寸进行可控合成,考察了研磨介质、磨球比例、球料比、固液比、表面活性剂等工艺条件对磷酸锌粒径分布、形貌及团聚状况的影响,并采用SEM、XRD、粒度分布和TEM对纳米磷酸锌做了表征。结果表明,表面活性剂CTAB浓度为9×10^-4 mol/L、研磨时间为3 h、锆球为研磨介质、球料质量比为150:1、Φ10 mm与Φ6 mm磨球质量比为1:4、转速为200 r/min、固液比[氧化锌和（磷酸+表面活性剂）的质量比]为1:1时,可以制备粒径分布为59~79 nm、平均粒径为68 nm、无团聚的粒状纳米磷酸锌。     

球磨法制备超细稻壳二氧化硅

将稻壳用10％(体积分数)的盐酸处理后在600℃焚烧得到稻壳二氧化硅,再利用球磨法进行研磨,得到平均粒径为5.01 μm、分散度为1.31的超细稻壳二氧化硅粉体.研究了研磨时间、球料比和磨球直径对粉体粒径的影响,并对研磨前后粉体的性质、红外光谱(FTIR)及X-衍射图谱(XRD)进行了比较.结果表明:合适的球料比、磨球...     

Dispersion and Rheology of Aqueous Zirconium Diboride Nanosuspensions

The dispersion and rheology of aqueous ZrB₂ nanosuspensions were investigated by zeta potential measurements, particle size measurements, sedimentation tests, and rheology measurements, with poly (acrylic acid) (PAA) as dispersant. Results showed that the dispersion and rheology of nanosized ZrB₂ suspensions in aqueous media were dependent on pH value, PAA concentration, solid loading, and ball milling time. Concentrated (up to 30 vol% solid loading) and well‐stabilized aqueous ZrB₂ nanosuspension with low viscosity (0.485 Pa s at 60/s) was prepared at pH 10, with 1.0 wt% PAA.     

氧化硼研磨的实验与理论研究

用行星式球磨机对13个不同尺寸区间氧化硼的研磨过程进行了实验与理论研究. 实验测量了13个不同尺寸区间氧化硼的粉碎速率常数及其分布系数,通过对测量结果的分析得到了不同尺寸氧化硼的粉碎速率函数及其分布系数函数,进而建立了粉碎过程质量分数的积分微分方程. 用四阶龙格-库塔法对氧化硼研磨过程的质量分数积分微分方程进行了数值计算,并与实验结果进行了比较. 计算与比较结果表明,氧化硼的研磨过程具有时变特征.     

球磨法制备POE-g-MAH/OMMT增韧母粒及其对PA6增韧改性

通过球磨法制备马来酸酐接枝(乙烯-辛烯)共聚物(POE-g-MAH)／有机化蒙脱土(OMMT)增韧母粒,并将其用于尼龙(PA)6的增韧改性.结果表明,球磨法制备的POE-g-MAH/OMMT增韧母粒尺寸比较均匀,有少量POE-g-MAH进入OM MT片层之间,导致OMMT片层间距有所增加.POE-g-MAH/OMMT增...     

Application of grinding kinetics analysis of inorganic powders by a stirred ball mill

The need for ultra fine particles has been increasing in the preparation field of raw powders such as fine ceramics and high functional products. A series of wet grinding experiments were carried out on inorganic powders such as calcite, pyrophyllite and talc by a stirred ball mill. The grinding rate constant K’ in the equation of grinding kinetics was examined based on the grinding kinetics analysis as the same type of function of a previous paper on a vertical type planetary ball mill. The experimental particle size distribution of the ground products was obtained in various grinding conditions. The grinding rate constants K and K’ were expressed by empirical equation involving experimental conditions by a stirred ball mill. The empirical equation on the grinding rate constant was expressed in terms of a function involving the ball diameter of grinding balls, the median diameter of feed material, and Bond’s work index of material, in the experimental conditions. The values of empirical constants C1 and C₂ were 21.13 and 0.0109 on K, while C₁ and C₂ were 120.99 and 0.0192 on K′, respectively. And the particle size distribution of ground products of each test material for a given grinding time was found to be expressing the selection function (the specific rate of breakage) which was obtained from the grinding kinetics analysis. In this study, the grinding rate change on calcite and pyrophyllite was similar at the same experimental operation condition. However, in the case of talc, it was observed that the grinding rate was not increased compared with other samples.     

Naßmahlung in Rührwerksmühlen

Wet grinding in agitated ball mills. To ensure certain product qualities it is necessary to have very fine particles or a narrow particle size distribution. For this process agitated ball mill grinding can be used as well as crystallisation and precipitation. Cost effective grinding of very fine products to a narrow particle size distribution requires that the effects of variation of strain intensity, frequency of impacts, residence time distribution, size of grinding media, viscosity of liquid and concentration of feed material should be known. The most important parameters and their effects on the grinding result are demonstrated, as well as explained by a model, and the consequences for the operating conditions of agitated ball mills are presented. By using small grinding media in agitated ball mills the production rate can be increased, or at the same energy level smaller particles can be obtained by grinding or deagglomeration. At high flow rates and a narrow residence time distribution the feed material becomes more homogeneous. These facts require the development of new or modified types of agitated ball mills.     

Empirical and scale-up modeling in stirred ball mills

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.     

Analysis of individual and interaction effects of processing parameters on wet grinding performance in ball milling of alumina ceramics using statistical methods

It is of great interest and necessary to closely investigate and understand how ball milling parameters can affect the overall quality of milled ceramic powders. In this paper, we analyzed the individual and interaction effects of the key processing parameters on the wet grinding performance in a ball mill for alumina powder using statistical methods. The grinding performance was evaluated based on three quality characteristics of milled alumina powder: the median particle size (d₅₀), width and skewness reflecting the shape of particle size distributions (PSDs). For this determination, the volume percentage of slurry, solid content, milling speed, milling time, and ball size are regarded as the key parameters affecting these characteristics. Milling experiments were designed by central composite design, and an experimental dataset was collected systematically. The analysis results show that it is worthwhile to consider not only the d₅₀ but also the shape of the PSDs when assessing the ball milling performance. These results are useful for the production of high-quality alumina powders in ceramic industries.     

高浓度料浆制备磨矿特性研究

为优化高浓度料浆制备技术,在实验室高浓度料浆制备的基础上,采用两级磨矿工艺,进行了料浆粒度分布和磨矿单位能耗的研究。实验结果表明:第一级磨矿时间19 min时,粒径<45μm的煤粒质量分数约为95%,能耗16.0 kWh/t;第二级磨矿时间35 min时,粒径<20μm的煤粒质量分数约为95%,能耗36.0 kWh/t。两级磨矿均可得到符合要求的粒度分布,研磨过程中得到的相关参数可为工业化应用提供基础设计依据参考。     

燃烧法和固相法所制备的红褐色陶瓷颜料ZnFe1.2Cr0.8O4的研磨效果研究

本文以燃烧法和固相法分别制备的红褐色陶瓷颜料ZnFe_1.2Cr_0.8O₄(燃烧法：C-ZnF;固相法：S-ZnF)为研究对象,采用正交试验的方法对颜料颗粒的研磨最优参数进行分析探讨。使用激光粒度仪表征研磨前后颜料颗粒的粒度及其分布,通过极差分析法来分析研磨的最优参数。结果表明,上述两种颜料颗粒的最优研磨条件均为：添加5wt%的分散剂WF211,研磨时间为100min,研磨转速为2000rpm。在相同的研磨条件下,对比固相法制备的颜料颗粒S-ZnF,燃烧法制备的颜料颗粒C-ZnF可以得到颗粒粒度细且分布窄的颜料颗粒产品。另外,采用一种粒数衡算模型(PBM)来模拟颜料颗粒的研磨过程破碎行为,计算颜料颗粒在研磨过程中的选择函数矩阵。通过模拟分析表明,颜料颗粒C-ZnF的研磨效果要优于颜料颗粒S-ZnF。     

钛精矿重选分离含硅物相影响因素研究

针对四川某钛精矿中存在的硅含量过高的问题,提出了摇床重选法分离二氧化硅的方法。通过球磨工艺获得不同粒径颗粒,然后采用摇床进行重选,研究粒径大小、粒径组分占比、冲程等因素对钛精矿含硅相的分离效果。结果表明,随着磨矿时间的增加,-200目(＜75 μm)钛精矿占比逐渐增加。当研磨时间为8 min时,-200目钛精矿的占比为83.0%(质量分数)。随着冲程的增大,SiO₂的品位和TiO₂的回收率均呈逐渐增大的趋势。当冲程为15 mm时,SiO₂的品位由2.46%(质量分数)降低至1.07%。重选分离后原矿分为三部分,TiO₂品位:钛精矿>中矿>尾矿,SiO₂品位:钛精矿<中矿<尾矿。当-200目铁精矿占比85.5%(质量分数)时,重选后SiO₂的含量最低可降至0.93%(质量分数)。     

蛋白污布的染制均匀性对洗涤剂去污力评价的影响

采用球磨机代替手工磨制炭黑制备改进蛋白污布(改进JB-02),通过测试标准洗衣粉、市售洗衣粉和含蛋白酶的标准洗衣粉对改进JB-02的去污值来评价所制备污布的质量。结果表明,使用球磨机磨制相比于手工磨制的炭黑颗粒的粒径变小,粒度分布变窄,分散均匀性提高;改进JB-02的染制均一度提高;标准洗衣粉对改进JB-02的去污值提高;当标准洗衣粉中蛋白酶的质量分数低于0.15%时,改进JB-02对蛋白酶的敏感度提高;改进JB-02的稳定性较好,可考虑作为标准产品使用。     

湿法纳米研磨制备药物纳米晶体——铝碳酸镁

低溶出速率和溶解度严重影响其生物利用度和药效, 是造成药物研发候选化合物不能成药的首要因素。近年的研究发现,当颗粒粒径减小到100～200nm,其溶出速率和溶解度会出现显著提升。本文研究了利用湿法纳米研磨技术制备铝碳酸镁药物纳米晶体的工艺。铝碳酸镁是治疗胃病的有效药物,其纳米颗粒悬浮液抗酸效果更好,起效速度更快。本文选择了六偏磷酸钠为分散剂,利用湿法研磨机,考察了分散剂用量、研磨转速、铝碳酸镁含量、研磨时间等参数对颗粒粒度分布的影响规律,获得了在最佳的工艺操作条件为研磨转速3000r/min、研磨时间105min、主药体积分数2%、分散剂为固含量质量分数的1.5%时,成功得到粒径D₁₀(76.4nm)、D₅₀(161nm)、D₉₀(352nm)的铝碳酸镁纳米悬浮液。制酸力实验结果证明纳米铝碳酸镁悬浮液比微米级悬浮液在盐酸中的溶出速率快5倍以上。     

Influence of solid loading on the rheological,porosity distribution,optical and the microstructural properties of YAG transparent ceramic

Stable aqueous dispersed mixture of commercial Al₂O₃ and Y₂O₃ nano powders was prepared by ball mill. Ammonium poly meta acrylate (Dolapix CE64) and tetraethyl orthosilicate (TEOS) were added as dispersant and sintering aid, respectively. The effects of slurry solid loading on the fabrication of transparent polycrystalline YAG ceramics by slip casting method were investigated. The rheological properties of slurries with different solid loading (64, 70 and 76?wt%) were studied by measuring the viscosity and shear stress as a function of shear rate. The effect of solid loadings on the porosity distribution was examined. The specimens were vacuum-sintered at 1715?°C for 10?h. Slips with 64 and 70?wt% solid loading behaved as near-Newtonian and as non-Newtonian with thixotropic behavior at 76?wt% solid loading. The relative densities of the green bodies increased from 58.0?±?0.6% (SD?=?0.424) to 64.0?±?0.3% (SD?=?0.228) by increasing the solid loading from 64?wt% to 70?wt% and then decreased to 63.0?±?0.2% (SD?=?0.141) at 76?wt% solid loading. The results showed that the suitable solid loading for fabricating transparent YAG ceramics is 70?wt%. This sample had the narrowest pore size distribution (4–100?nm), homogenized surface fracture of green body, dense microstructure (99.990?±?0.005% final relative density, SD?=?0.003) and the average grain size of 6?µm. It had the highest in-line transmittance, which was approximately 77% at 1064?nm.     

The investigation of grinding kinetics of power plant solid fossil fuel in ball mill

The kinetics of batch dry grinding of power plant solid fossil fuel, from the feeds of sieve sizes −3.350 + 2.360, −2.360 + 1.700, −1.180 + 0.850, −0.425 + 0.300 and −0.212 + 0.150 mm have been determined using a Bond ball mill with a mixture of five ball sizes. The mill used has a diameter of 30.5 cm, length of 30.5 cm, providing a total mill volume of 22.272 cm³ with a total mass of 20.125 g steel ball mixtures of 38.10, 31.75, 25.40, 19.05 and 12.70 mm diameters. The balls occupied 22% of mill volume. The speed of rotation of the mill was chosen as 70 rpm. The specific rates of breakage (S_i) and primary breakage distribution (B_i,j) values, called as grinding breakage parameters, were determined for those feed size fractions to simulate the product size distributions for comparison to the experimentally obtained data. As the feed sizes increase, the S_i values also increase, that is, faster breakage values from higher to lower values were in the order of solid fossil fuel by comparing to its α values. Breakage distribution functions were found non-normalizable. It is dependent upon the initial feed particle sizes. In other words, the simulations of product size distributions for fossil fuels were in good agreement with the experimental data using a ball mill simulation program, called JKSimMet.     

Effect of solid loading on properties of Y2O3–Al2O3–Nd2O3 powder mixtures obtained by planetary ball milling and ceramics based on them

The effect of the solid loading (41–50 wt%) of the slurry on granulometric composition and physico-chemical characteristics of Y₂O₃–Al₂O₃–Nd₂O₃ powder mixtures obtained by planetary ball milling has been studied for the first time. It was shown that the particle size distribution of powder, its Zeta potential, and specific surface area depend on the solid loading of the milled slurry and, consequently, on the interparticle distance during milling. The interparticle distance decreases from 200 nm to 142 nm with an increase of solid loading in the range of 41–50 wt%. It was shown that for the solid loading of 47 wt%, the convergence of particles to a distance comparable to their median diameter promotes subsequent clustering of particles. This facilitates the sintering of highly-homogenous ceramics. It was found that solid loadings in the 46–50 wt% range is useful for obtaining high-quality Nd:YAG transparent ceramics. The lowest optical losses optical losses of 1 × 10^?3 cm^?1 and the highest in-line transmittance of 84.1%@1064 nm were obtained for 1 at.% Nd:YAG transparent ceramics (22 × 3 × 4 mm³) prepared from slurries with 47 wt% solid loading (taking all other ball milling parameters fixed). If the interparticle distance in the powder is higher (solid loading of 41 wt%) than the median particle diameter, the ceramics are characterized by significant residual porosity due to the survival of large particles (insufficient milling).     

激光粒度分析仪在微细粒级荧光粉粒度测量中的应用

采用激光粒度分析仪对某种微细粒级荧光粉运用不同的样品循环运动速度和加载超声波进行粒度组成与分布的测量。通过正态曲线叠加比较获得:该微细粒级荧光粉颗粒平均直径为4.128μm,中值为3.145μm,标准差为3.930μm,变异系数为95.10%,众数为4.048μm,并测得不同粒径颗粒所占的质量分数。结果表明,该方法是粉末粒度及粒度分布测量的准确方法。     

球磨机研磨体级配设计与计算

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。