Mechanische Eigenschaften zyklisch be‐ und entfeuchteter Zeolithgranulate

The production of zeolite granules varies in the amounts of binder content and different drying/activation temperatures. Here, the influence of moisture content and cyclic moisture loading and unloading on the mechanical properties like the strength of three different types of zeolite granules has been studied by uniaxial compression tests. The force‐displacement curves and scanning electron microscopy pictures of the granule and fracture surfaces show that with increasing number of moistening‐drying cycles, a continuous decrease in the strength of granules take place due to non‐regenerative damage of the structure.     

Logistikzentren für die Kunststoffindustrie

Logistics Centers for the Plastics Industry The capacity of reactors and extruders for the production of polymers is growing steadily. New catalysts and reactor modifications allow significant improvement of the performance of existing plants. At the same time the proportion of plastics that is sent in bulk to processors, rather than packed in sacks directly to the customer, is increasing globally. The various delivery demands and the storage of pellets define a series of possibilities for the design of logistic centers. An optimal design can only be achieved through close collaboration and agreement with specialized companies so that the needs and procedures of the operation can be fulfilled. Good design and planning can lead to a reduction of the operating costs or an increase of the dispatch capacity per employee of up to 30 %.     

Aufbereitung kohlenstofffaserverstärkter Thermoplaste zu Granulat für den Wiedereinsatz in Strukturbauteilen

Due to the continuing trend towards lightweight construction, more and more carbon fiber reinforced plastics (CFRP)-containing waste is generated, particularly in the areas of transportation, energy technology as well as in the mechanical engineering or leisure sector. For CFRP-containing waste with thermoplastic matrix, a closed-loop recycling by regranulation could be demonstrated. Under multi-stage mechanical stress, the CFRP material was comminuted to a defined granule size. This granulate from secondary material was converted by means of a special process in an injection molding complex into new components.     

Festigkeitsuntersuchungen von Agglomeraten in Abhängigkeit der Herstellungsparameter in Intensivmischern

Granules of ceramic materials are differently stressed by the processes during pelletizing in high shear mixers. This has a major influence on the resulting agglomerate size distribution. The paper presents the results of different mixing tools and impeller speed on the agglomerate strength. Therefor agglomerates have been compounded under certain conditions. Subsequently, their strength has been determined with a single particle breakage equipment.     

降低混凝土成本的秘密武器--磨细矿粉

本文介绍了磨细矿粉用于混凝土后可以降低混凝土成本，同时减少混凝土坍落度损失、大大提高混凝土耐久性、显著增加混凝土后期强度，并且磨细粉还是优良的碱骨科抑制剂。     

Effect of mechanical cleaning with granular material on the permeability of submerged membranes in the MBR process

The research on fouling reduction and permeability loss in membrane bioreactors (MBRs) was carried out at two MBR pilot plants with synthetic and real wastewater. On the one hand, the effect of mechanical cleaning with an abrasive granular material on the performance of a submerged MBR process was tested. Additionally, scanning electron microscopy (SEM) measurements and integrity tests were conducted to check whether the membrane material was damaged by the granulate.The results indicate that the fouling layer formation was significantly reduced by abrasion using the granular material. This technique allowed a long-term operation of more than 600 days at a flux up to 40 L/(m² h) without chemical cleaning of the membranes. Moreover, it was demonstrated that the membrane bioreactor (MBR) with granulate could be operated with more than 20% higher flux compared to a conventional MBR operation. SEM images and integrity tests showed that in consequence of abrasive cleaning, the granular material left brush marks on the membrane surface, however, the membrane function was not affected.In a parallel experimental set up, the impact of the operationally defined “truly soluble fraction” <0.04 μm from wastewater and activated sludge on the ultrafiltration membrane fouling characteristics was investigated. It was shown that the permeability loss was caused predominantly by the colloidal fraction >0.04 μm rather than by the dissolved fraction of wastewater and activated sludge.     

Silo-quake—measurements, a numerical approach and a way for its suppression

Silo-quake can be observed in granular bodies during silo emptying in the form of dynamic effects as pulsations or shocks. Measurements were carried out in full-scale aluminium silos containing potato powder and polymer granulates, and in a model perspex silo containing different fills to investigate this phenomenon. Theoretically, dynamic effects in silos were analysed with a finite element method developed in the frame of a polar (Cosserat) continuum using an elastoplastic and a hypoplastic approach. The onset of a dynamic silo flow with controlled and free outlet velocity in a plane strain model silo was simulated. A reliable, practical method to significantly reduce dynamic effects and to suppress resonance effects in mass flow during silo emptying was proposed. It was verified with experiments and FE-calculations.     

Integrierte Versuchsmethode zur Analyse des Matrizenfüllprozesses beim uniaxialen Trockenpressen

Die filling during dry compaction shaping operations is one important process step, which influences quality and complexity of the compacts as well as the processing speed. A method for characterizing the die filling behavior under process‐oriented conditions will be presented. By the use of a self‐constructed filling device, the filling progress can be visualized and quantified via image processing. The density structure of the resulting bulk in the die is analyzed using computer tomography. On the basis of experiments with ceramic granules the potential of the new method is shown.