Iron Ore Tailings Dewatering: Measurement of Adhesion and Cohesion for Filter Press Operation

Globally, mining operators focus increasingly on tailings filtration to recover process water and store tailings more safely. Generally, required water contents below 20-w% are reached by using filter presses. To maintain high efficiency, complete cake detachment is needed because incomplete discharge reduces plant performance. However, filter cake discharge can occur in different ways, mainly influenced by adhesion of the filter cake to the filter cloth as well as by cohesion of the cake. Therefore, this study points out different major detachment behaviors and a theoretical approach to describe them. Furthermore, investigations on iron ore tailings filtrations were carried out to show the influences of different filter media, different filtration pressure and cake post-treatment on adhesion and cohesion

Removal of fine-grained and thin filter cakes by a counter-current backwash treatment

In industrial solid/liquid separation, the removal of fine particles (≤ 10 μm) in a suspension with a low solids content (0.01-1 v/v %) is a challenging and demanding task. This application takes place in a wide array of industrial production such as metal processing and treatment industries. In order to achieve the required purity, different types of filters like candle and leaf filter can be used. In Figure 1, the commonly used candle filters are shown inside the vessel (a), during filtration (b), and cake removal (c). In respect of the field of applications, the procedure of removal has revealed that there is potential for improvement in pressure difference and amount of backwash reflux. These process variables highly depend on the material properties like cohesion within the filter cake and adhesion of the filter cake onto the filter media. In order to guarantee the removal of the filter cake, the applied removal force has to be larger than the adhesive forces. Furthermore, to remove the filter cake in large fragments, the removal force has to be lower than the cohesive force. These two effects also depend on porosity, pH-value, and further properties; they can be reflected by and measured as shear and tensile strength of the filter cake. Currently, the amount of backwash reflux is oversized and leads to an operating point below the optimum. Hence, research must be carried out how to improve the backwash treatment in respect of the process conditions in an economic and process-technical context. This presentation comprises a state-of-the-art review of the current backwash filters and differentiate between the various physical principles of cleaning process. Moreover, the project and experimental facility will be presented, followed by first results

Jet Cleaning of Filter Cloths Used in Solid‐Liquid Separation: A High‐Speed Video Evaluation

Cleaning avoids cross-contamination and sustains production safety and efficiency. While there have been discoveries for technical surfaces, data on activities for filter cloth are still in the early stages. In the food industry, there is a lack of knowledge and innovative ideas on how to clean cloths efficiently. This study combined high-speed recordings with cleaning experiments. Cleaning of eleven filters was captured, enabling time-resolved analysis of the cleaning degree, the cleaning homogeneity, and insights into the mechanisms. The findings divide cloth cleaning into three phases, each significantly influenced by the properties of the cloth. Exemplarily, close-mesh cloths have smoother surfaces that facilitate cleaning. Coarse structures with flow channels on the cloth surface can complicate cleaning

Azimuthal anisotropy of charged jet production in root s(NN)=2.76 TeV Pb-Pb collisions

We present measurements of the azimuthal dependence of charged jet production in central and semi-central root s(NN) = 2.76 TeV Pb-Pb collisions with respect to the second harmonic event plane, quantified as nu(ch)(2) (jet). Jet finding is performed employing the anti-k(T) algorithm with a resolution parameter R = 0.2 using charged tracks from the ALICE tracking system. The contribution of the azimuthal anisotropy of the underlying event is taken into account event-by-event. The remaining (statistical) region-to-region fluctuations are removed on an ensemble basis by unfolding the jet spectra for different event plane orientations independently. Significant non-zero nu(ch)(2) (jet) is observed in semi-central collisions (30-50% centrality) for 20 <p(T)(ch) (jet) <90 GeV/c. The azimuthal dependence of the charged jet production is similar to the dependence observed for jets comprising both charged and neutral fragments, and compatible with measurements of the nu(2) of single charged particles at high p(T). Good agreement between the data and predictions from JEWEL, an event generator simulating parton shower evolution in the presence of a dense QCD medium, is found in semi-central collisions. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Peer reviewe

Production of He-4 and (4) in Pb-Pb collisions at root(NN)-N-S=2.76 TeV at the LHC

Results on the production of He-4 and (4) nuclei in Pb-Pb collisions at root(NN)-N-S = 2.76 TeV in the rapidity range vertical bar y vertical bar <1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN/dy4(He) = (0.8 +/- 0.4 (stat) +/- 0.3 (syst)) x 10(-6) and dN/dy4 = (1.1 +/- 0.4 (stat) +/- 0.2 (syst)) x 10(-6), respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (T-chem = 156 MeV) as for light hadrons. The measured ratio of (4)/He-4 is 1.4 +/- 0.8 (stat) +/- 0.5 (syst). (C) 2018 Published by Elsevier B.V.Peer reviewe