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Distribution of elements in slag, matte, and speiss during settling operation
2008 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

To cope with current trends in the base metals industry due to the lack of pure mining resources, booming metals prices, and growing demand for base metals: new thinking regarding the nature of metal resources as well as novel recycling technologies is needed. Slags from base metals' production can be a superior material for recycling. Currently, at the Rönnskär smelter plant, copper slag is recycled in a continuous procedure, including fuming, settling, and granulation. The main product is called Iron Sand with smaller amounts of matte and speiss. These two phases contain a considerable amount of Cu, Ni, and precious metals. Investigating the distribution of elements and oxides in these separate phases and the effect of CaO as a common impurity, is the main aim of this study. The original materials, including settling slag, matte, and speiss, were delivered by Boliden AB, Rönnskär Smelter Plant. Each material was dried, crushed, milled, and separated in the mineral processing laboratory of Luleå University of Technology for later analysis with X-ray diffractometery (XRD) and thermal treatment. Six different samples were prepared by homogenously mixing these three phases along with different ratios of CaO. Then, the six samples were placed in alumina crucibles and remelted in a Tamman furnace under N2 atmosphere at 1400°C for one hour to attain maximum settling. After cooling, slag, matte, and speiss were carefully separated from solidified material. A fraction of the materials were mounted and prepared for light optical microscopy (LOM) and scanning electron microscopy (SEM) investigations. The remaining material was crushed and milled for X-ray diffractometery (XRD) and chemical analysis. XRD analysis disclosed that the matte and speiss result in very complicated patterns, which are not easily interpreted. Treated samples along with original samples were sent to Rönnskär smelter plant for accurate chemical analysis of Cu, Ni, Fe, Zn, Pb, Sn, Sb, As, Ag, S, Al2O3, MgO, CaO, and Fe3O4. The results of XRD, LOM, SEM, Chemical Composition, and Thermodynamic studies reveal that the distribution of elements and components change with respect to CaO content. The results have been extracted and tabulated in this thesis work. The higher the lime content the greater the formation of Augite [Ca (Mg, Fe) Si2O6] in the slag phase, whereas little or no affect was noticed on distribution of elements in matte and speiss. Iron content in the speiss phase did decrease with addition of lime into the system. Furthermore, it was determined that Ni present in speiss mostly occurs with either As and Fe, or Sb and Cu.

Place, publisher, year, edition, pages
Keyword [en]
Technology, Copper, Slag, Matte, Speiss, Distribution coefficient, Settling, Chemical Composition
Keyword [sv]
URN: urn:nbn:se:ltu:diva-50845ISRN: LTU-PB-EX--08/111--SELocal ID: 81103397-f2e9-4f17-91e4-26345ed26330OAI: diva2:1024208
Subject / course
Student thesis, at least 30 credits
Educational program
Chemical Engineering, master's level
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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