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  • 51.
    Sundqvist, Åsa
    et al.
    Luleå tekniska universitet.
    Sellgren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Addie, G.
    Pipeline friction losses of coarse sand slurries: comparison with a design model1996In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 89, no 1, p. 9-18Article in journal (Refereed)
    Abstract [en]

    Friction losses in 0.2-0.3 m i.d. pipelines were investigated for three coarse sands with mass median particle sizes of 0.6-0.7 mm and size distributions of 1.4, 5.4 and 27.3, respectively, when expressed in terms of the ratio of particle diameters 85 to 15% by mass finer. The partially-stratified friction loss model proposed by K.C. Wilson, G.R. Addie and R. Clift, Slurry Transport Using Centrifugal Pumps, Elsevier, Oxford, 1992 [1] predicted the observed friction losses reasonably well at volumetric concentrations of 12-15% for velocities of practical interest. Good agreement was found for concentrations of up to 31% for sand with the intermediate distribution. However, predictions for the narrowest sand underestimated friction losses at higher concentrations of 26-31%. Friction losses for the broadest sand were overestimated markedly at concentrations of 28-39%. With these two sands, observed losses did not increase linearly with concentration, in disagreement with model assumptions. The different mechanisms involved are discussed in light of results demonstrating how particle size distribution, content of particles 0.1-0.5 mm in size, and concentration affect friction losses. The flow conditions discussed here correspond to velocities that clearly exceed those for which there are risks of deposition at the bottom of the pipe.

  • 52.
    Sundqvist, Åsa
    et al.
    Luleå tekniska universitet.
    Sellgren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Addie, Graeme
    Slurry pipeline friction losses for coarse and high density industrial products1996In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 89, no 1, p. 19-28Article in journal (Refereed)
    Abstract [en]

    Experimental results showed energy-efficient pseudohomogeneous-like flow behaviour when a mixture of coarse (20-200 mm) granite rock in tar sand tailings ( - 1 mm) in mass proportions 1:9 was transported at a total volumetric solids concentration of 31% in a 0.44 m i.d. (D) pipeline loop. Similar results were obtained with an industrially comminuted copper ore ( - 100 mm; mass median particle size 0.75 mm) when pumped in a 0.2 m i.d. pipe at a concentration of 39%. The partially-stratified friction loss model proposed by K.C. Wilson, G.R. Addie and R. Clift, Slurry Transport Using Centrifugal Pumps, Elsevier, Oxford 1992 predicted well the observed losses of an iron ore (relative solids density 4.1, mass median particle size 0.42 mm) at a concentration of 23% (D = 0.1 m). With a slightly heavier and coarser iron ore the model tended to underestimate losses at concentrations of 14-29%. The favourable friction loss performance in some results may demonstrate how broad particle size distributions and high concentrations may cause reduced pipe wall friction without influence of true theological mechanisms. An alternative way of characterizing experimental data in terms of excess pressure gradient versus the ratio of mean velocity to hindered settling velocity is introduced. The flow conditions discussed here correspond to velocities that clearly exceed those for which there are risks of deposition at the bottom of the pipe.

  • 53.
    Tano, Kent
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Öberg, Eva
    LKAB.
    Samskog, Per-Olof
    Monredon, T
    Svedala-Cisa, Orléans.
    Broussaud, A.
    Svedala-Cisa, Orléans.
    Comparison of control strategies for a hematite processing plant1999In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 105, no 1-3, p. 443-450Article in journal (Refereed)
    Abstract [en]

    A model-assisted method is used for designing the control strategy for the new LKAB hematite plant in Malmberget (Sweden). Steady-state and dynamic process simulations successively help to select strategic controlled and manipulated variables, and specify the corresponding instrumentation. The control system implemented in the plant reflects the conclusions of the study. It includes an optimizing control system based on specified software, with a fuzzy logic expert system, a dynamic model of the process and an optimizer.

  • 54.
    Wilson, K.C.
    et al.
    Department of Civil Engineering, Queen's University, Ellis Hall, Kingston, ON.
    Clift, R.
    Centre for Environmental Strategy, University of Surrey.
    Sellgren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Operating points for pipelines carrying concentrated heterogeneous slurries2004In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 123, no 1, p. 19-24Article in journal (Refereed)
    Abstract [en]

    Early studies of slurry pipeline systems were based on moderate volumetric concentrations of solids (say up to 18%), for which the excess pressure gradient caused by solids is proportional to concentration. Much larger concentrations now coming into common use show more complicated behaviour. An algebraic analysis is developed to determine desirable operating points and associated energy consumption for settling slurries. This deals initially with the simple proportional behaviour, and then is extended to other cases. Comparison is made to recent experiments using highly concentrated settling slurries with various particle gradings. It is found that near-uniform gradings tend to have high frictional losses, while very broad gradings can give rise to energy-efficient transport at high concentrations

  • 55.
    Yu, Liang
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Liu, Dong
    State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing University of Technology.
    Yan, Baili
    State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing University of Technology.
    Zeng, Changfeng
    College of Mechanic and Power Engineering, Nanjing Tech University.
    Wang, Chongqing
    State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing University of Technology.
    Zhang, Lixiong
    State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology.
    A Universal Biological-materials-assisted Hydrothermal Route to Prepare Various Inorganic Hollow Microcapsules in the Presence of Pollens2016In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 301, p. 26-33Article in journal (Refereed)
    Abstract [en]

    A universal bio-economical hydrothermal route has been developed to prepare various inorganic hollow microcapsules with the help of rapeseed pollens for the first time. The pollens were used without any modifications. TiO2, ZnO, zeolite ZSM-5, BaTiO3 and ZnS were prepared by this route using the regular synthesis solutions added with rapeseed pollens. The obtained products were examined by scanning and transmission electron microscopy, X-ray diffraction, FT-IR, N2 adsorption and thermogravimetric analysis. The hollow microcapsules are composed of inorganic particles around the derivations of pollens. And the diameter of the hollow has been demonstrated almost the same size as the derivations microspheres. The derivations were decomposed in high temperature crystallization procedure; therefore, no additional procedure is needed to remove the templates for the hollow structure. The hollow microcapsules prepared with rapeseeds have much higher specific surface area. The formation mechanism can be ascribed to the template effect of derivative microspheres formed from decomposition of these pollen grains. Furthermore, other pollens are also used in the preparation by the universal hydrothermal route. Still, inorganic hollow microcapsules but with different hollow diameters were obtained probably resulting from the different size of the derivations.

  • 56.
    Zeng, Yigen
    et al.
    Luleå University of Technology.
    Forssberg, Eric
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Application of vibration signals to monitoring crushing parameters1993In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 76, no 3, p. 247-252Article in journal (Refereed)
    Abstract [en]

    Vibration measurements for fine crushing have been performed on a laboratory scale jaw crusher on dolomite. The original vibration signal was sensed by an accelerometer and stored on a DAT recorder during the whole testing period. The vibration signal was resampled and converted into an IBM PC compatible data format with a digital oscilloscope. The time-domain vibration signal was analyzed with the aid of a digital signal processing technique. The crushing process can be inspected by replaying the sample of the time-domain waveform. The variation of the vibration pattern was described by a few `latent' variables obtained by principal component analysis. Relations were established between the crusher setting, the product size and the latent variables by multiple regression. Measurement of the vibration signal provides a new strategy for monitoring crushing processes.

  • 57.
    Zeng, Yigen
    et al.
    Luleå University of Technology.
    Forssberg, Eric
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Effects of mill feed size and rod charges on grinding performance1992In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 69, no 2, p. 119-123Article in journal (Refereed)
    Abstract [en]

    The effects of mill feed sizes and the rod charges on ground product fineness, energy utilization and energy consumption have been investigated on a rod mill under dry batchwise grinding conditions. The effect of reducing mill feed size on product fineness decreases with grinding time, while the effects of different composition of rod charges are very small. Smaller rod diameter, coarser mill feed size and shorter grinding time will increase the energy utilization. The energy consumption in batch grinding is described by the Bond method. Using smaller rod diameter and reducing the mill feed size will optimize energy use in coarse grinding.

  • 58.
    Zhang, Shunli
    et al.
    Luleå University of Technology.
    Forssberg, Eric
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Intelligent liberation and classification of electronic scrap1999In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 105, no 1, p. 295-301Article in journal (Refereed)
    Abstract [en]

    Mechanical recycling of electronic scrap oriented towards overall materials recovery from obsolete electronics is being implemented worldwide. The main reason is that the amount of electronic scrap is increasing and that the content of the precious metals present is decreasing. In this context, an effective liberation of various materials like metals and plastics is a crucial step towards mechanical separation. In addition, classification of electronic scrap is also important to be able to provide an appropriate feed material for the subsequent separation process. In the present study, liberation and its impact on the separation of personal computer (PC) scrap and printed circuit board (PCB) scrap has been investigated in detail. A special equipment functioning as a shape separator and an aspirator was used for the classification of electronic scrap.

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