New Method to Measure the Fill Level of the Ball Mill I——Theoretical Analysis and DEM Simulation

The accurate measurement of the fill level in the ball mill has not been resolved because of the interplay of many variable factors, which led the mill to be operated under the uneconomical condition and lost a lot of energy. At present, some methods, such as vibration method and acoustic method, have been applied for measuring the fill level by the researchers. Aiming at the problem of the traditional methods for measuring the fill level, that is, the feature variables of the fill level suffer the influences of the ball load and the water content of the coal, a novel method to measure the fill level is proposed and a possible relation between the fill level and the angular position of the maximum vibration point on the mill shell is investigated. The angular positions of the maximum vibration point on the mill shell for different fill level cases are calculated theoretically under two assumptions, respectively. Meanwhile the charge motions of the mill for different fill level cases are simulated with the discrete element method （DEM）. And the simulation results are verified by comparing the motion trajectories of steel balls and power draft of the mill. The simulated movement trajectories of the outmost layer steel balls in the mill are monitored and analyzed to obtain the angular positions of the maximum vibration point on the mill shell. Both the results of the theoretical calculation and the 3D DEM simulation show that the position of the maximum vibration point on the mill shell moves to a lower angular positions as the fill level decreasing, which provides a new idea for measuring the filllevel accurately.

Modelling of the High-Energy Ball Milling Process

In this paper, the milling parameters of high energy ball mill (Fritsch Pulverisette 7) like vial geometry, number and size of balls and speed of the mill were modelled and discussed. Simulations through discrete element method (DEM) provide correlation between the milling parameters. A mathematical model is used to improve and develop this process. The results show that the loss of powder mass can remarkably improve the performance of milling. The balls made of stainless-steel have a positive effect on the milling efficiency. The simulation shows that the high ball milling velocities can contribute to faster particle size reduction.

Simulation of a Laboratory Scale Ball Mill via Discrete Element Method Modelling

Discrete Element Method (DEM) is a powerful tool for simulating different types of mills. It also used for computing different types of particles such as rocks, grains, and molecules. DEM has been widely used in the field of rock mechanics. In the present work, DEM approach is applied to model the milling media (powder particles and balls) inside a planetary ball mill and to estimate the distribution of particles of a dry powder during milling. In fact, the efficiency of the DEM strongly depends on the input parameters. The DEM simulation results indicated that DEM is a promising tool for the simulation of the dynamic particles motion and interactions within planetary ball mill. These results could be utilized to further develop the synthesis performance, anticipate the reaction, and reduce the wear in the dry milling reactions.

Calibration of DEM Parameters to Simulate a Planetary Ball Mill

Planetary ball mill is a powerful tool, which has been used for milling various materials for size reduction. The discrete element method (DEM) was used to simulate the dynamics of particle processes in a planetary ball mill. This work includes the calibration of DEM parameters to simulate a planetary ball mill using EDEM Altair 2021.2 software, which provides both faster workflows and results. The iterative input parameters changed to a close correlation between the simulation and experimental results are attained. The results showed that the standard tests could be used to generate various experimental reference values for the calibration. The numerical modeling results agree with theexperimental, indicating that the calibrated parameters are accurate.

Enhanced photocatalytic activity of Gd3+ doped TiO2 and Gd2O3 modified TiO2 prepared via ball milling method

Gd^3+/TiO2 and Gd2O3/TiO2 nanoparticles were prepared by ball milling method.The effects of Gd^3+ion and Gd2O3 on the structure and optical property of TiO2 were studied by XRD and UV-vis DRS.Specific surface area was determined by Brunauer-Emmett-Teller(BET)method.The morphology and elemental composition were characterized by SEM-EDS.XPS was used to determine the surface compositions and chemical character of elements.The sample sizes and microstructures were observed by TEM.The photocatalytic activities of TiO2 nanoparticles modified with rare earth metal gadolinium(Gd^3+ion or Gd2O3)were evaluated by degradation of methylene blue(MB)under UV light.Experimental results indicate that 2,5 mol%Gd^3+/TiO2 shows the best photocatalytic activity compared with Gd2O3/TiO2 and pure TiO2.The existence of gadolinium can exhibit the aggregation and induce lattice distortion of TiO2 obtained from XRD,SEM and TEM results.The band gap energy of 2.5 mol%Gd^3+/TiO2 decreases to3.07 eV and it leads to visible light absorption response which can be seen from UV-vis absorption spectra.The surface area of 2.5 mol%Gd^3+/TiO2 equals to 85.8 m^2/g and average crystal size is 21.1 nm.EDS and XPS analyses reveal that gadolinium can be introduced either into TiO2 lattice or adsorbed on the surface of TiO2.The content of surface OH groups in 2.5 mol%Gd^3+/TiO2 is 50,88%(1.55 times higher than that of pure TiO2)and the content of lattice oxygen decreases to 11.26%.The MB(25 mg/L)degradation reaction rate constants of 2,5 mol%Gd^3+/TiO2,0.5 mol%Gd2O3/TiO2 and pure TiO2 were0.0713,0.0588 and 0.0263 min^-1,respectively.The degradation rates of rhodamine B(30 mg/L)in 60 min are 97,9%,90.1%and 84.6%for 2,5 mol%Gd^3+/TiO2,0.5 mol%Gd2O3/TiO2 and pure TiO2,respectively.

Photocatalytic activity of Lu^(3+)/TiO_2 prepared by ball milling method

Ball milling method was applied to prepare Lu^3＋/TiO2 photocatalysts. The catalysts were characterized with X-ray powder diffraction（XRD）, X-ray photoelectron spectroscopy（XPS）, UV-visible diffuse reflectance spectra（UV-vis DRS）, energy dispersive X-ray spectrometer（EDS）, transmission electron microscopy（TEM） and Brunauer-Emmett-Teller（BET） method. The photocatalytic activities were determined by the degradation of methylene blue（MB） equipped with a 300 W medium pressure mercury lamp. Results show that the first order reaction rate constants of Lu^3＋/TiO2 and pure TiO2 are0.0565 and 0.0263 min-1, respectively, which both were evaluated under the condition of catalysts loading of 0.2 g/L,initial concentration of 25 mg/L for MB, mole ratio of Lu^3＋/TiO2 of 1.5% and milling time of 4 h. The average crystal sizes of 1.5 mol% Lu^3＋/TiO2 and pure TiO2 are 18.7 and 19.3 nm, respectively.

A combination of density-based clustering method and DEM to numerically investigate the breakage of bonded pharmaceutical granules in the ball milling process

Ball milling is widely used in industry to mill particulate material.The primary purpose of this process is to attain an appropriate product size with the least possible energy consumption.The process is also extensively utilised in pharmaceuticals for the comminution of the excipients or drugs.Surprisingly,for ball mill,little is known concerning the mechanism of size reduction.Traditional prediction approaches are not deemed useful to provide significant insights into the operation or facilitate radical step changes in performance.Therefore,the discrete element method(DEM)as a computational modelling approach has been used in this paper.In previous research,DEM has been applied to simulate breaking behaviour through the impact energy of all ball collisions as the driving force for fracturing.However,the nature of pharmaceutical material fragmentation during ball milling is more complex.Suitable functional equations which link broken media and applied energy do not consider the collision of particulate media of different shapes or collisions of particulate media(such as granules)with balls and rotating mill drum.This could have a significant impact on fragmentation.Therefore,this paper aimed to investigate the fragmentation of bounded particles into DEM granules of different shape/size during the ball milling process.A systematic study was undertaken to explore the effect of milling speed on breakage behaviour.Also,in this study,a combination of a density-based clustering method and discrete element method was employed to numerically investigate the number and size of the fragments generated during the ball milling process over time.It was discovered that the collisions of the ball increased proportionally with rotation speed until reaching the critical rotation speed.Consequently,results illustrate that with an increase of rotation speed,the mill power increased correspondingly.The caratacting motion of mill material together with balls was identified as the most effective regime regarding the fragmentation,and fewer breakage events occurred for centrifugal motion.Higher quantities of the fines in each batch were produced with increased milling speed with less quantities of grain fragments.Moreover,the relationship between the number of produced fragment and milling speed at the end of the process exhibited a linear tendency.

Evaluating the Effects of Crystallinity on Drug Release Behaviour in Itraconazole- or Miconazole-Loaded PLGA Microparticles Prepared Using a Co-Grinding Method

This study aimed to prepare and characterize itraconazole (ITCZ)- or miconazole (MCZ)-loaded poly (lactide-co-glycolide) (PLGA) microparticles (MP) using a co-grinding method with ball milling, which is a solvent-free and convenient procedure. PLGA MP was prepared by grinding for 60 min, and the fixed theoretical drug loading was set at 9.1% and 16.7% for both drugs. The obtained loading efficiency for both drugs was estimated to be approximately 100%. The average diameters of the drug-loaded PLGA MP were approximately 20 - 35 μm. Powder X-ray diffraction (PXRD) or differential scanning calorimetry (DSC) confirmed amorphization of ITCZ and MCZ in ITCZ- or MCZ-loaded PLGA MP in all formulations. The drug release percentage from 9.1%-loaded ITCZ-PLGA7505 MP at 24 h was almost 50%, which was higher than that of ITCZ powder. The drug release percentage from MCZ-loaded PLGA7505 MP at 4 h was over 80%, which was higher than that of MCZ powder. This enhancement of release rate is caused by the amorphization of ITCZ or MCZ in the PLGA matrix. MCZ-loaded PLGA7510 MP showed a sustained release profile up to 24 h, suggesting that MCZ exists in an amorphous form in the PLGA matrix;however, the release rate declined owing to the large molecular weight of PLGA. Therefore, the release enhancement of antifungal drugs loaded on PLGA MP could be achieved by their amorphization using a co-grinding method with ball milling.

玛瑙球磨法制备微米介孔球状材料催化剂及其应用

利用玛瑙球磨法合成出一种负载酸催化剂三氟甲磺酸铜的微米级球状介孔材料,研究了催化剂的微观结构、微观形貌和催化反应活性。通过对环己酮和乙二醇的催化反应表明,样品作为催化剂具有较高活性。初次使用时环己酮转化率为97%,环己酮缩酮的选择性为99%,经过4次使用后依旧具有较高催化活性-环己酮转化率为96%。环己酮缩酮的选择性为99%,远远高于工业用硫酸催化剂的环己酮转化率(90%)和环己酮缩酮的选择性(91%)。

球磨法制备堇青石负载Fe/Ce载氧体的甲烷化学链重整性能

通过球磨法制备一系列堇青石负载Fe/Ce的复合载氧体,并在固定床装置上评价复合载氧体的甲烷化学链重整的反应性能。系统考察了堇青石质量分数、Fe/Ce摩尔比、椰壳添加量以及球磨参数对复合载氧体的氧化还原性能的影响,并进行了一系列表征(XRD、H2-TPR、BET、SEM、XPS)。研究发现,在球料比10∶1、转速500r/min、时间1h的球磨参数下制备质量分数30%堇青石负载Fe/Ce摩尔比为1∶9的复合载氧体具有较优的氧化还原性能。质量分数15%椰壳炭的添加使复合载氧体的实际出氧量提升了38.7%,并且在还原氧化循环反应中表现出良好的稳定性和氧释放能力。

四苯基甲烷球磨法合成多孔碘蒸气吸附材料

【目的】避免在核能利用过程中产生的常见放射性污染核素129I和131I等碘蒸气泄漏对环境和生物产生危害,制备并探讨具有丰富孔道的有机多孔聚合物对碘蒸气的吸附性能。【方法】采用简便快捷的机械合成法,以具有正四面体结构的四苯基甲烷为单体,利用高能行星式球磨机球磨2 h制备3种具有较大比表面积和丰富孔道的有机多孔聚合物T-FDA、T-DCM和T-DCE,并利用碘单质在温度为75℃的密闭体系内升华模仿放射性碘蒸气,分别测试3种多孔材料的碘蒸气吸附性能。【结果】T-FDA、T-DCM、T-DCE的碘蒸气吸附质量分数分别可达461%、486%、444%,达到饱和吸附量的时间分别为5、8、6 h,且多孔材料在循环使用5次后碘吸附性能仅有轻微下降(≤6.8%)。【结论】以四苯基甲烷为单体,通过快速球磨法合成的多孔材料具有良好的碘蒸气吸附性能,有望在放射性碘蒸气吸附领域发挥重要作用。

废旧LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2)材料球磨-喷雾法再生研究

为了改善再生锂离子电池材料的电化学性能,提出了一种球磨-喷雾法对废旧LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2)(NCM523)进行回收再生。该方法是通过对预处理后的废旧正极材料进行球磨细化,经过喷雾干燥迅速制备再生材料的前驱体,并结合高温煅烧制备再生NCM523材料。采用SEM、EDS、XRD、HRTEM、FT-IR、XPS、TG-DSC等对再生过程中材料的形貌、成分、物相及化学变化等进行了分析,且对再生NCM523组装的电池进行了电化学性能分析。结果表明,再生材料具有多孔结构,锂镍混排程度降低,电化学性能得到改善。在实验条件下得到的再生NCM523材料在0.11 C下的首圈放电比容量为159.053 mA·h/g,循环100圈后放电比容量为145.615 mA·h/g,容量保持率为91.55%,具有良好的容量保持率;电流密度为5 C的首圈放电比容量为126.974 mA·h/g。相较于传统的直接再生方法,球磨-喷雾再生法制备的NCM523的电化学性能得到明显改善。

Al-Mg共掺杂钴酸锂的合成及其电化学性能研究

钴酸锂(LCO)作为锂电池正极材料,在电子产品领域有非常广泛的应用,但由于高电压下会导致其晶相的不可逆相变从而导致循环稳定性降低,因此如何提高钴酸锂在高电压下的电化学稳定性一直是研究热点。为了改善钴酸锂的电化学稳定性,采用固相球磨-烧结法合成了Al-Mg共掺杂的LCO材料。采用X射线衍射(XRD)和扫描电镜(SEM)及电化学性能测试表征晶体结构、形貌和测量其循环稳定性。结果表明:Mg、Al进入钴酸锂晶格内部后有效地提高了其电化学稳定性,当Al掺杂量为0.1%,Mg掺杂量为1%时,在0.5C的倍率,3~4.5V的电压下,首圈放电比容量可达136.7mAh/g,100圈后的容量保持率可达76.2%,同时也表现出了良好的倍率性能。

一种新型Al-2.5GNPs细化剂制备及其对AZ31镁合金的细化作用

镁合金因自身强度低和塑性较差限制了其在工业领域的应用,向镁合金中添加晶粒细化剂的方法能够改善其组织并提高材料的强度和塑性,是提升镁合金性能的最有效方法之一。本文利用球磨工艺结合粉末冶金的方法制备出一种含有GNPs(石墨烯纳米片)的新型镁合金细化剂。采用拉曼光谱分析法探究了不同球磨参数对GNPs的质量影响规律,得出较优球磨工艺参数为:转速300 r/min、球磨时间2 h,可以保证球磨后GNPs的高质量。将其混合粉体进行冷压,并在400℃烧结2 h,得到含有GNPs且组织致密、成型良好的Al-2.5GNPs细化剂。采用OM、SEM、XRD、TEM等表征手段初步分析了细化剂中Al4C3和GNPs对AZ31镁合金中的细化及强化机理。在720℃下加入质量分数为1.5%的Al-2.5GNPs细化剂,可以使AZ31镁合金的晶粒尺寸从228.8μm细化至65.6μm,抗拉强度从112.6 MPa提升至178.2 MPa,伸长率从8.9%提升至16.7%,分别提高了58.3%和87.6%。

基于高速球磨法的磷酸锰锂正极材料制备及Fe掺杂性能研究

锂离子电池具有较高的能量密度及倍率性能,已成为新能源汽车的首选电池应用体系。其中LiMnPO_(4)正极材料具有安全性能好、成本低等优点,是锂离子电池中的主流材料之一,但由于其导电性较差、电化学性能不理想,制约了其市场应用。本文基于高速球磨法制备了LiMnPO_(4)正极材料,考察了球磨时间和焙烧温度对材料电化学性能的影响,结果表明:当球磨时间为20 h时,在0.1 C倍率下LiMnPO_(4)正极材料的首次放电比容量可达162 mA·h/g,在1 C倍率下经过100周循环后的容量保持率可达94.3%;当焙烧温度为750℃时,LiMnPO_(4)正极材料经过100周不同倍率循环后,在2 C倍率下放电比容量仍可达132.3 mA·h/g。采用Fe掺杂制得LiMn_(1-x)Fe_(x)PO_(4)正极材料,在最佳掺杂量为30%的条件下制得的LiMn_(0.7)Fe_(0.3)PO_(4)正极材料首次放电比容量达165 mA·h/g,经过100周循环后的容量保持率达98%。

Cu-Mn-Al三元尖晶石催化甲醇重整反应特性

以硝酸铜为铜源、拟薄水铝石为铝源、柠檬酸为添加剂,以乙酸锰为第三组分部分取代铜,采用球磨法制备了Cu_(0.7)Mn_(0.3)Al_(2.5)三元固溶体尖晶石催化剂;借助XRD、BET、H_(2)-TPR和XPS等表征技术,对Cu_(0.7)Mn_(0.3)Al_(2.5)的晶相结构、织构性质、还原性质及表面阳离子状态及分布进行研究,并在甲醇水蒸气重整制氢(MSR)反应中考察其缓释催化性能。结果表明,与Cu Al_(2.5)、Cu_(0.7)Zn_(0.3)Al_(2.5)相比,Cu_(0.7)Mn_(0.3)Al_(2.5)的晶粒最小,比表面积最大,且晶胞收缩最大,晶胞常数最小;该催化剂呈富铝状态,但表面尖晶石相Cu^(2+)占比更高,H_(2)气氛下还原难度增大,在MSR反应中表现出较好的缓释催化性能;在温度为265℃、n(H_(2)O)/n(CH_(3)OH)=2、质量空速为2.25 h^(-1)的条件下反应40 h,甲醇转化率高达84%。该研究为研发高效铜基缓释催化剂提供了数据参考。

Ni-Al合金药型罩的制备及其射孔性能研究

为了提升油气井用射孔弹的射孔性能和清洁效果,在常规药型罩配方中加入铝镍活性材料,试验研究了不同质量比的Ni-Al合金粉以及不同Ni-Al合金粉含量的药型罩的放热特性,对Ni-Al合金药型罩配方进行了优化设计;并通过地面模拟穿钢靶试验和地面模拟地层岩石应力试验,对Ni-Al合金药型罩和常规药型罩的射孔孔径、穿深和自清洁效果进行了对比。结果表明:当w_(Ni)∶w_(Al)=2∶1时,Ni-Al金属粉的放热量最大,达到255.5 J·g^(-1);当Ni-Al金属粉和其它金属粉材的配比为6∶4时,Ni-Al合金药型罩的放热量最大,达到9806 J·g^(-1);相较于常规射孔弹,自清洁射孔弹的射孔孔径和穿深分别提升了23.8%和9.4%,并且达到了清洁孔道的效果。

球磨法制备芡实超微粉及其理化功能性质分析

芡实淀粉属小颗粒淀粉,且以超聚合的复粒形式存在。为了解超微粉碎对淀粉复粒结构及其中功效组分溶出的影响,文中采用球磨法制备超微芡实粉,分析了不同球磨参数对芡实粉理化功能性质的影响。研究显示,芡实粉的适宜球磨参数为:转速200 r/min,m(用料量)∶m(研磨球)=1∶30,研磨球直径4 mm,研磨时间30 min。与对照相比,所得超微芡实粉中超细粉末(粒径0~1μm)占比达到85.04%,其中总黄酮溶出量增加不显著,但总酚溶出量有明显增加(P≤0.05)。所得超微芡实粉吸水性和吸油性显著提高,分别达到3.88、2.46 g/g,分别增加了3.26、1.34倍。X-衍射图谱和扫描电子显微镜照片显示,超微芡实粉中淀粉的复粒结构发生碎裂,淀粉颗粒完整性及其晶体结构也被严重破坏,印证了超微芡实粉理化功能性质改变的内在原因。研究结果表明,球磨处理不仅改善了芡实粉的理化功能性质,也有利于其中功效组分的溶出。

球磨法高性能Na_(3)MnTi(PO_(4))_(3)@rGO-KB钠离子电池正极材料制备

钠超离子导体(NASICON)结构的聚阴离子材料由于具有稳定的晶体结构而引起了极大的关注.然而,NASICON型材料导电性差、能量密度低和库仑效率低等固有缺陷限制了其发展.为此采用高能球磨法对Na_(3)MnTi(PO_(4))_(3)(NMTP)晶粒表面进行科琴黑(KB)和还原氧化石墨烯(rGO)的碳包覆,极大地提高了材料的导电性和离子传输效率,使其在常温和低温下的比容量和循环性能均有明显提升.在常温下NMTP@rGO-KB的质量比容量高达166.6 mAh/g,具有5000圈的循环稳定性和优异的倍率性能.在-30℃的低温下质量比容量为111.4 mAh/g,循环1000圈后质量比容量保持率为85.3%,平均库仑效率高达99.9%,为低温钠离子电池开发提供了广阔的应用前景.

片状银粉制备方法的研究进展

片状银粉作为银浆的重要组成部分,其制备方法得到了广泛研究。阐述了片状银粉制备方法,包括机械球磨法、光诱导法和模板法等3种方法的工艺原理,分析了各方法的优缺点,并对机械球磨法和模板法的研究方向进行了展望,以期为片状银粉的制备提供参考。