Experimental investigations and modelling of the ball motion in planetary ball mills

Planetary ball mills feature attractive properties, like the possibility of dry or wet operation, straightforward handling, cleanability and moderate costs. Consequently they are very well suited for lab scale process development in diverse industries, including pharmaceuticals and new materials. A number of questions still remain unanswered regarding this mill type. These include the stress conditions as well as transfer of the grinding results to other types of mills with free moving balls, such as stirred media mills, which can be built in large scales and operated continuously.In order to measure the ball motion and, thus, the stress conditions, a planetary ball mill was equipped with a high speed video camera, so that the grinding ball motion during the comminution process can be recorded and analysed. The influence of important process parameters on the ball motion pattern was assessed in this study, namely speed ratio, ball filling ratio and friction conditions, the latter by applying different mill feeds. The experimental results show considerable influences of the ball filling ratio and friction conditions. The measured ball motion patterns differ significantly from ball trajectories which were calculated using kinetic equations proposed in older publications.In addition to the measurements the ball motion was simulated using a three dimensional Discrete Element Model (DEM). An attempt was made to account for mill feed via altered friction coefficients. Correlations of the DEM results and experimental findings at different operating conditions show a good agreement. Based on simulation data the frequency distribution of the stress energies in the mill could be calculated and compared for different operating conditions.     

Mechanical milling of catalyst support for enhancing the performance in fuel cells

In this work, we studied the characteristic variations of catalyst supports caused by mechanical milling and their electrochemical application in fuel cells. Two different catalyst supports, carbon black (XC-72R) and K20 (mesoporous carbon), were crushed and dispersed by mechanical milling using a bead mill. The bead mill operated with 0.3 μm zirconia beads at the rate of 3500 rpm for 30 min. The secondary particle size of the crushed catalyst supports ranged from around 0.1 μm to 10 μm. The secondary particle size of the catalyst supports after crushing represents a decrease of approximately 10% compared with that of raw catalyst supports. To confirm the role of the catalyst supports in the direct methanol fuel cell (DMFC), Pt and Ru were loaded onto these catalyst supports using an impregnation method. In the single cell test, Pt-Ru/XC-Bead and PtRu/K20-Bead showed power densities of 135 mW/cm² and 144 mW/cm² under air at 60 °C, respectively. The performance values of these catalysts, which were fabricated using reformed catalyst supports, were 10% to 20% higher than those of raw catalyst supports. As a result, the catalyst supports crushed by the bead mill helped to improve the electrochemical performance of the direct methanol fuel cell.     

冲击式粉磨机调控粒度方法的研究

阐述了冲击式粉磨机生产石油焦的工艺流程、技术特点及粒度控制方法,本文通过对分级机转速、风机风量进行调整,由粒度检测结果可知:改变分级机频率,可以调节产品最大粒度,变化幅度大;改变风机风量可以调整成品中细粉含量,改善粒度分布.     

砂磨机湿法粉磨制备超细氧化锌粉体的研究

以粗颗粒氧化锌为原料,通过砂磨机湿法粉磨的方法制备超细氧化锌。用马尔文激光粒度仪、扫描电镜（SEM）对研磨前后的氧化锌粉体进行了表征。考察了分散剂种类及用量、pH、固含量、研磨时间对研磨效果的影响,得出最佳研磨条件：转速为3 000 r/min,固含量为15%（质量分数）,pH为11,聚乙二醇20000加入量为0.5%（质量分数）,研磨时间为40 min。在此条件下可以制备d₅₀约为6 μm、d₉₀为10 μm的超细活性氧化锌粉体。     

A full‐scale system for aerobic biological treatment of olive mill wastewater

Olive mill wastewater (OMW) is a major environmental problem in the Mediterranean basin. Although many methods for OMW treatment have been developed, only a few have been adopted in pilot‐ or full‐scale applications. A full‐scale system for aerobic biological treatment of OMW was developed. The system consists of a trickling filter and a recirculation tank. Continuous recirculation of the wastewater was used to provide oxygen concentrations from 0.7 to 1.2 mg L^?1. Low ambient temperatures did not affect system performance since the raw wastewater was warm enough. Nutrient addition was not necessary as raw wastewater contained sufficient nitrogen and phosphorous concentrations. Indigenous olive pulp bacteria proved to be resistant to full‐scale conditions. Feed chemical oxygen demand and phenolic concentrations were about 43 000 and 9500 mg L^?1, respectively. The system reduced more than half of the organic load under continuous operation and a hydraulic retention time of 24 h. The efficiency of this method could be improved by combining it with another technology to further reduce the organic load. The absence of mechanical aeration and the very low hydraulic retention time denotes that the proposed system could be viable and attractive. Copyright © 2011 Society of Chemical Industry     

Management scenarios for olive oil mill waste based on characterization and leaching tests

BACKGROUND: Olive oil mill waste is a serious environmental problem in the Mediterranean basin given its particular characteristics of high organic content, seasonal and localized generation, and the type of processing involved. RESULTS: Olive mill waste from a three‐phase mill was characterized by means of total analysis, availability and mobility of the pollutants in order to help the decision‐maker about possible options for its valorization and/or disposal. Water content, loss of ignition, total organic carbon, phenol index and metals concentrations were measured to fully characterize the waste. Three leaching tests (NEN 7341, EN 12457 and UNE CEN‐TS 15364 EX) were carried out to evaluate the environmental hazard of the waste material and the leachates were characterized with respect to electric conductivity, pH, heavy metals, anions and organic pollutants (phenol index and total organic carbon) according to European waste directives. The results were compared with EU regulations for inert, non‐hazardous and hazardous waste disposal. CONCLUSION: It was found that not only organic parameters must be taken into account concerning the fate of this waste material, but also the mobility of heavy metals and anions should be studied. Furthermore, stabilization/solidification processes are recommended before landfill disposal of this kind of agro‐waste material. Copyright © 2011 Society of Chemical Industry     

分油管周向10型芯斜槽抽芯注塑模设计

分析周向带有10个出油孔的分油管的工艺特点，介绍成型该塑料件的注塑模结构及一种特殊的圆周方向10型芯侧向抽芯结构，阐述该模具的工作过程和模具设计与制造中应注意的问题。     

提高Φ2.2 m×7.5 m矿渣磨产量和细度的措施

福建三明水泥厂矿渣和熟料易磨性不同,制约了 2.2 m×6.5m闭路水泥磨系统的产质量,导致产量低仅12 t/h;矿渣掺量低,仅7％;水泥强度低R28仅达47.0MPa。为此该厂增加了2台 2.2m×7.5m开流磨单独粉磨矿渣,实现熟料矿渣分别粉磨工艺。同时对 2_2m×6.5m矿渣磨进行结构改造和工艺操作参数调整。这样二套粉磨系统可根据熟料和矿渣的不同粉磨特性分别进行操作控制,工厂实现了高产高质,高矿渣掺量(达15％)和低成本生产。     

提高φ5m×11.5m生料磨产量的措施

针对粘土资源枯竭问题,江苏巨龙水泥集团实施了以粉煤灰和硅石代替粘土的技改工程。但改造后因原料的变更,导致入房物料易磨性变差而影响了φ5m×11.5m生料磨的产质量,并进一步影响察系统的运行。因此该厂在工艺分析的基础上,采取了调整钢球级配、用高铬球替代合金刚球、改造选粉机、加强石灰石二破的管理和减少系统是否是“漏风”等技术措施,效果显著。改造后的生料磨台时产量比调整前提高了12t/h,且节电效果显著。     

浅谈大型中卸烘干磨精细化管理

结合山东德州中联大坝水泥有限公司两φ4．6m×（10＋3．5）m中卸烘干原料磨的实际生产控制和管理经验．从工艺、操作和机械三方面,全面分析了大型中卸磨实现低耗、高产、优质生产的相关影响因素和具体的精细化管理举措。