Amino acid transformation of oscillatory Ca2+ signals in mouse pancreatic beta-cells

This work investigates the relationships between the wet mass consistency/viscosity of samples prepared in a mixer-granulator and physical properties of the dry granules produced from the wet mass; namely, size distribution, bulk density (Hausner ratio), friability, and flow avalanching behavior. The correlation between the consistency of the wet mass and the downstream dry granule properties confirms that consistency is the key parameter to control in wet granulation by mechanical agitation. Variations in the formulation affect the dimensionless power relationship of the mixer-granulator considered; that is, the equivalence between wet mass consistency and mixer net power consumption, which is actually the parameter used to monitor the wet granulation process. The same variations in formulation also affect the relationships between wet mass consistency and dry granule properties.     

Turbine mixer fundamentals and scale-up method at the Port Nickel Refinery

The Port Nickel Refinery at Braithwaite, Louisiana is being rehabilitated and expanded to achieve a capacity of 80 million pounds per year of nickel. The atmospheric leaching of granulated and ground matte with recirculated and aerated electrolyte from the copper tankhouse is one of the first steps in the Port Nickel flowsheet. An investigation was undertaken to develop the design parameters necessary for the commercial scale-up of this leach circuit. Mechanical factors to be specified include tank geometry, impeller type, and froth handling capability. Also needed for scale-up was quantitative data showing the effect of mixer power and gas input rate on the rate of oxygen transfer. During the leaching period, the rate mechanism changed from oxygen diffusion control to chemical rate control which necessitated careful correlation of the kinetic data with mixer scale-up parameters. The scaled up system calls for a co-current five stage leaching train. Use of a single turbine impeller on a vertical central shaft provides sufficient power for off-bottom solids suspension while providing the required oxygen mass transfer rate. Radial impellers are provided for the first three tanks in which oxygen transfer is rate controlling, and axial impellers for the last two tanks where hydrolysis of basic copper sulfate is the rate controlling factor.     

铁矿粉烧结制粒过程颗粒行为研究综述

摘要：烧结原料需经过制粒处理以确保高效低耗的烧结生产,即在水或其他粘结剂的参与下混合料颗粒在相互运动、碰撞中形成粒度更大且粒度分布更窄的聚团颗粒体。制粒效果受制粒设备参数和铁矿粉物理化学性质的影响,因而合适的制粒工艺和铁矿粉优化配置对烧结技术经济指标的改善具有显著作用。阐述了制粒现象的基本理论,综述了制粒过程中颗粒聚结长大的作用力以及颗粒的长大机制,制粒工艺参数如加水量、搅拌动能、制粒时间等和铁矿石的粒度组成、表面性质、颗粒形貌等性质对制粒效果的影响规律。相关结果为系统深入理解铁矿粉制粒过程以及高效生产优质准颗粒提供理论基础。     

Simultaneous optimization of wet granulation process involving factor of drug content dependency on granule size

Computer optimization technique was applied to the simultaneous optimization of wet granulation process by a high-speed mixer granulator. Four pharmaceutical properties, including yield, drug content uniformity, geometrical mean diameter of granules, and uniformity of granule size, were selected to evaluate the quality of the granules. In particular, dependence of drug content uniformity on granule size was investigated using two model drugs, ascorbic acid and ethenzamide. An appreciable dependence of ascorbic acid content on granule size was not observed in model formulations. On the other hand, ethenzamide was contained more in small-size granules, and its content was decreased with an increase in amounts of hydroxypropyl cellulose (HPC-L; used as a binder) and binder solution. These observations suggested that drug content uniformity is influenced not only by drug solubility in the binder solution, but also by the use of HPC-L. A simultaneous optimal point incorporating four pharmaceutical properties was obtained using the generalized distance function. The experimental values of the four response variables obtained in newly prepared granules were found to correspond well with the predicted values of both granules containing ascorbic acid and ethenzamide. These results suggested that computer optimization would benefit the wet granulation process even if drug content segregation was involved in the process. Further, data obtained from computer optimization, in particular the contour diagram, will be valuable in the process validation.     

熔渣干式粒化与集成热能回收

全球钢铁行业每年有数以亿吨计的熔渣产生,并且越来越多的高炉渣通过水淬粒化处理而生产一种玻璃质产品。这种物质作为硅酸盐水泥的替代物,可以带来可观的价值增值,同时减少了由于石灰石煅烧而产生的CO2排放。然而,水淬粒化渣处理却需要消耗大量的水资源,并且可能带来有害气体排放。更为重要的是,现有的渣处理工艺没有回收其中所含有的热量(大约1.8GJ/t渣)。熔渣干式粒化(DSG)是渣处理领域发生的根本性变革。在这种新的处理方法中,熔渣在旋转盘中由于离心力的作用而自动分离,产生的熔滴在空气的作用下快速急冷固化,同时可回收热能。由DSG工艺处理得到的固态粒渣适用于生产水泥,同时产生的热空气(约500～600℃)可作为现场就地利用的热源。DSG工艺同水淬法相比,在节水、减少排放、余热回收、减少能源消耗和温室气体排放等方面,提供了一种更加可持续的处理方法。澳大利亚联邦科学与工业研究组织对DSG工艺的研究始于2002年,并且在工艺设计创新方面已经取得重大的突破。近期与博思格和一钢公司(澳大利亚钢铁行业CO2减排关键问题解决计划成员之一)合作,研究工作已经拓展到了渣中的热能回收方面。试验设备的应用已经成功验证了这种处理理念,渣处理能力达到了10kg/min,渣处理产品的评估以及初步的技术经济分析取得了令人满意的结果。新工艺的处理规模扩大了一个数量级,并且建造了一个半工业化规模的装置(渣处理能力提高到了100kg/min),业已投入运行,用于对工艺设计进行深度优化和论证。如果一切顺利的话,计划在两年内建立一个更具规模的工业化工厂(熔渣放流速度达到1～2t/min)。介绍了这项新工艺的进展情况,并对近期的一些进展进行了总结。     

圆筒混合机清壁装置的设计

针对烧结机混合制粒系统所用圆筒混合机简体内壁粘料后,影响混匀与制粒效果、影响烧结机的正常稳定生产、增加烧结风机功耗、增大混合机运转负荷、降低混合机使用寿命问题,设计了一种可靠的混合机清壁装置,实现了不停机清壁,保证了混合机及烧结机的正常稳定运行.     

Effect of the conditions of sintering of sodium-reduced tantalum powders on their characteristics

The effect of the granulation and heat treatment of sodium-reduced tantalum powders with a specific surface area of 2.5–3.6 m²/g on the bulk density, the powder flow time, and the specific surface area of the powders and the specific capacitance of the anodes made of them is studied. It is shown that heat treatment of a granulated powder in vacuum at 1100°C or in a mixture with magnesium at 800°C makes it possible to achieve the required powder flow time.     

Numerical Modeling of Helical Static Mixers for Water Treatment

To improve the understanding of how static mixers work and how to better utilize them in environmental engineering (or, specifically, drinking water treatment), a numerical model for simulating turbulent flows in helical static mixers is developed. The model solves the three-dimensional, Reynolds-averaged Navier-Stokes equations, closed with the k-ω turbulence model, using a second-order-accurate finite-volume numerical method. Numerical simulations are carried out for a two-element helical static mixer, and the computed results are analyzed to elucidate the complex, three-dimensional features of the flow. The results show that the flow field within the mixer is characterized by the presence of pockets of reversed flow and the growth and interaction of strong longitudinal vortices. As an example of the kind of practical insights that can be gained from such detailed three-dimensional computations, the simulated flow field is used to investigate two quantities that are often used to characterize mixing within a static mixer and to discuss the merits of these quantities for coagulant mixing in drinking water treatment.     

Investigating Factors Affecting on the Efficiency of Dynamic Mixers

Mixers are widely used in chemical and hydrometallurgical processes. For instance, one of the greatest challenges in the field of hydrometallurgy process is agitation made by impeller inside mixers. Solvent extraction is a process for separating components in solution by their distribution between two immiscible liquids. Dynamic mixers are qualified as efficient vessels for mixing in processes accompanied by mass, momentum and heat transfer and chemical reaction. One of the advantages of this type of receptacles is their high productivity. In this study, recent conceptual and technological innovations in various dynamic mixers are reviewed. For this purpose, geometrical, operational, and physical effective parameters in the most important research are investigated. In addition, optimal parameters, drop size measurement, and distribution are discussed. Current industrial applications and efficiency are discussed from a process perspective, focusing on mixing. Considering the development of flow equipment in various flow regimes, advances in this field will play a crucial role in scientific and industrial communities. For design and optimization of the dynamic mixers, some models are used. The model structure is selected based on its good compromise between accuracy and complexity. Validation of the computational fluid dynamics models with experimental data by using progressive methods resulted in realistic simulations. In recent researches, there has been an increasing interest in the development of alternative designs for improvements of key elements, such as geometry of baffles, mixer vessels, impellers, operational parameters of mixers and impellers, etc.     

Investigation into processes of mechanical alloying when obtaining composite materials with nanodimensional strengthening particles

This work is devoted to obtaining metal-matrix composites with powderlike nanodiamond reinforcements. The following flowchart was accepted for investigations: mechanical alloying of the starting components in planetary mills with obtaining granules of composite materials and subsequent compacting the granules into a bulk material. To investigate mechanical alloying, a mixture of copper and brass powders was treated in a planetary mill. The difference in the coloration of components made it possible to investigate their stirring. It is established that an insufficient treatment time leads to the agglomeration of strengthening particles on the surface of granules, which results in a worsening of the mechanical characteristics. In the case of the uniform distribution of strengthening particles in the matrix, a high level of properties of composite materials is attained.     

日本使用离心转动型造球机对焦粉制粒的研究

本文介绍了国外某钢铁公司研究与开发实验室关于使用离心转动型造球机对烧结用焦粉制粒的研究成果。通过实验室试验和工业试验，他们发现，（１）离心转动型造球机不仅可以使细粒焦粉成球，而且可以防止制粒焦粉的粒度过大。（２）制粒焦粉成为混合料准颗粒的核心，并且可以改善其它烧结料的制粒。（３）使用该制粒焦粉可以减少烧结时氮氧化合物的排放量，也可以使烧结矿的还原性得到改善。     

Evaluation of two dextrose-based directly compressible excipients

The objectives of this research were to evaluate the physical properties and compaction behavior of two dextrose-based directly compressed excipients. Anhydrous theophylline (10% w/w) was used as a drug model, Emdex and or Maltrin M510 (89.5% w/w) were used as diluent, and magnesium stearate (0.5% w/w) was used as lubricant. Direct compression and wet granulation methods were used for preparing the compacts. In general, the wet granulation method reduced the density of the mixture and consequently its flow rate compared to the mixture prepared only by solid-solid mixing. All formulations were compressed at four different compressional forces and at a target weight of 450 mg +/- 5%. Tablets obtained were different in physical properties and mechanical strength based on type of excipient used and methods of tablet preparation (direct compression versus wet granulation). Compacts prepared from Maltrin M510 had a longer disintegration time and slower drug release than compacts of the same composition but prepared with Emdex. Disintegration time and drug dissolution from tablets containing Maltrin M510 as diluent and prepared by wet granulation appeared to be controlled by a "gel" layer formation around the tablets and not by the tablets porosity. This study demonstrates that full characterization of excipients is needed because a different manufacturing process for the same excipients may produce differences in the pharmaceutical products.     

钢渣风碎技术研究

研究钢渣粒化生产工艺技术参数，粒化钢渣理化性能及在工业上的用途，设计了新的钢渣风碎粒化装置，为钢铁厂提供了一种安全，节能，低耗，节省投资和变废为宝钢渣处理先进方法。     

Manufacture of NiAl-based rods for plasma centrifugal spraying using mechanochemical synthesis

An alternative technology is proposed for the production of NiAl–Co–Cr–Hf–Al₂O₃ alloy rods. It includes the fabrication of a powder by mechanochemical synthesis (MCS) followed by hot isostatic pressing in forming tool. The processes of MCS of the intermetallic alloy in a planetary mill and an attritor are studied. The products of synthesis in various mixers are compared. The microstructure and the properties of compacted samples are studied: their ultimate compressive strength is 1390–1480 MPa at a plasticity of 8.5–8.8%. Spherical granules with a target size of 20–200 μm are fabricated by plasma centrifugal spraying of the rod workpiece formed by the proposed technology.     

马钢2 500 m3高炉水渣处理技术研究及应用

根据马钢1号高炉(2500m^3)水渣处理系统存在的问题,分析了水渣颗粒度对冲渣工艺的影响,改进了INBA工艺并在2号高炉的水渣处理系统予以应用。     

铝粉方锥混合机的设计与应用

粉体物料的混合设备种类繁多,各有特点。在现代粉体工业生产中,混合机是不可缺少的一种生产工具。专门用于金属粉末的混合机鲜有报导,因为金属粉末有其特殊性,例如铝粉易氧化、易燃、易爆、粒度小。介绍了针对铝粉的混合而设计的一种新型混合机。该混合机主要用于铝粉或其他金属粉体物料的混合,混合的目的主要有二:一是2种或2种以上物料的组分均匀度的混合;二是同一种物料粒度均匀度的混合。其主要特点是一机多罐,减少辅助时间,可大大增加单位时间的混合量;可以将不同的物料装入不同的罐内进行混合操作,节省了混合罐的清洗、烘干等工序。     

Destratification by Mechanical Mixers: Mixing Efficiency and Flow Scaling

Experiments have been performed to assess the efficiency of mechanical mixers in destratifying water bodies. The effects of Reynolds number, physical scale, and Richardson number were all considered. The results demonstrated that the variation of mixing efficiency with Richardson number was well described by two different power-law regimes. At low Richardson numbers, the efficiency increased with increasing Richardson number. Above a critical value, however, the efficiency decreased rapidly with further increases in Richardson number. The experiments further showed that, over the range of Reynolds numbers considered, the results collapsed fairly well. Finally, experiments at different physical scales showed reasonable agreement. The main conclusion of the present technical note is that the destratification efficiency of mechanical mixers can be well parameterized by an overall Richardson number. The results, however, are specific to the particular geometric configuration studied. It is hoped that the present technical note will help to guide future studies of destratification systems in small lakes and reservoirs and fluid mixing in the chemical and process industries.     

An analysis of radial segregation for different sized spherical solids in rotary cylinders

Rotary reactors such as ball mills, driers, mixers, blenders, and kilns are extensively used in chemical and metallurgical industries to process billions of tons/year of granular solids. Longitudinal and radial segregation of the feed and/or product due to size, shape, and density differences of the feed or product are often encountered in these unit operations. This paper presents some observations of radial segregation due to size differences of spherical solids for slumping, rolling, cascading, cataracting, and centrifuging beds. The mechanism by which spherical beads segregate radially is a combination of percolation and flow. The kinetics of radial segregation for rolling beds is observed and quantified using high speed photography. The rate of segregation is shown to be a function of the cylinder rpm but is independent of bed depth. Furthermore, the larger the size ratio of coarse to fines, the faster the rate of segregation. The scale-up of the segregation process is investigated using two cylinders, 0.2 m ID × 0.2 m L and 0.4 m ID × 0.4 m L. Both the size ratio of the solids and the Froude number are the scale-up criteria for the rate of radial segregation. The former is related to the packing characteristics of loosely packed beds when rolling and to the effective radius of rotation of particles when cataracting or centrifuging. N. NITYANAND, formerly a Graduate Student B. MANLEY, formerly an Undergraduate Student     

湿压缩在燃气轮机中应用的计算分析

燃气轮机动力透平输出功约有三分之二用于压缩空气,减少空气压缩机耗功可以显著提高燃气轮机净输出功率,近年来发展的湿压缩技术通过湿化工质降低压缩过程温升,使其压缩过程趋近等温压缩,降低了压气机耗功,提高了循环效率。通过对干、湿空气的热力性质的计算,对喷雾湿化引起的工质热力性质变化以及压缩过程中耗功进行了分析,得出了湿化量对燃气轮机比功及功率的影响。研究了湿压缩过程提高燃气轮机功率的原理。     

高炉渣干式离心粒化实验研究

针对水冷高炉渣耗水量大、能量未回收、污染重等问题,进行了高炉渣干式离心粒化实验研究。结果表明:(1)高炉渣的玻璃体含量均在95%以上,可以作为水泥原料使用;(2)渣温度高、流量小、粒化盘直径大,粒化后渣粒越小,粒化理想时,88%渣粒径<4.75mm;(3)粒化盘的表面特性影响其粒化效果。其表面光洁度越高,渣粒的粒径越小且均匀,粒化后的渣粒越接近于球形;粗糙的粒化盘易拉出玻璃丝。