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| 2. |
- Wang, Y, et al.
(author)
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The influence of interparticle surface forces on the coagulation of weakly magnetic mineral ultrafines in a magnetic field
- 1994
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In: Colloids and Surfaces A. - 0927-7757 .- 1873-4359. ; 90, s. 117-133
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Journal article (peer-reviewed)abstract
- In this paper, it is shown that the coagulation of dispersions of weakly magnetic mineral ultrfines (such as hematite and chromite) in an external magnetic field can be described theoretically by invoking interparticle forces. Essentially, coagulation occurs when the short-range London-van der Waals interactions and the long-range magnetic forces outweight the stabilizing electric double layer repulsion. From classical colloid chemistry theory, we have calculated the the various components of the potential energy for different-sized particles at a series of ionic strenghts and magnetic field intensities. Principles governing the stability of the suspensions of weakly magnetic oxide mineral ultrafines in a "wet magnetic separation process". Experimentally, the magnetic-field induced coagulation of ultrafines of natural hematite and chromite in aqueous suspensions at moderate ionic strenght was investigated using a laboratory -scale electromagnetic solenoid. The experimental results relate the coagulation process (as determined by magnetosdimentation analysis) to particle size, slurry pH and the external magnetic field. In the magnetic fields, maximum coagulation occured near the pH of the point of zero charge (pH PZC)of the minerals (where the electrostatic double layer repulsionwas reduced to a minimum) enabling the particles to enter the"primary minimum" energy sink. In contrast, in cases where the electrostatic repulsion was not supressed, the long-range magnetic forces enabled coagulation to occur in the "secondary minimum". This caused the formation of chains which appeared to be relatively stable at enhanced rates of setting. The experimental results could be interpreted from a theoretical analysis of the interparticle forces controlling the process.
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| 3. |
- Sammelin, Monika, et al.
(author)
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Gold mineralogy at the Aitik Cu–Au–Ag deposit, Gällivare area, northern Sweden
- 2011
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In: GFF. - : Informa UK Limited. - 1103-5897 .- 2000-0863. ; 133:1-2, s. 19-30
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Journal article (peer-reviewed)abstract
- The low-grade Aitik Cu-Au-Ag deposit is a deformed and metamorphosed porphyry-type deposit, and as such it belongs to the group of ores that require detailed mineralogical investigations of precious metal occurrences to assist in determining the recovery processes. The character of gold in the Aitik deposit varies substantially. Gold alloys display highly variable Au/(Au + Ag) ratios, and Hg is commonly a constituent. A change from dominantly sulphide-associated to groundmass-associated gold as mining progresses towards depth is accompanied by a change in the chemical composition of gold. Towards depth, the gold content in electrum and amalgam decreases (from c. 66 to 22% in electrum and c. 23 to 4% in amalgam), and the amount of native gold grains increases. The most common mineral assemblage associated with gold at deep levels (600m and below) is K-feldspar, biotite, plagioclase, quartz, chalcopyrite and pyrite. This study demonstrates that magmatic-hydrothermal and metamorphic processes responsible for the diversity in copper mineralisation styles within the Aitik ore body probably have also played a role in the variable character of gold observed at Aitik today
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| 4. |
- Jacobowsky, C. Vilh.
(author)
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Svante Caméen
- 1924
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In: Samlaren. - Uppsala : Svenska Litteratursällskapet. - 0348-6133 .- 2002-3871. ; N.F. 5, s. 236-242
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Journal article (other academic/artistic)
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| 7. |
- Zhang, Lei, et al.
(author)
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Large group delay in a microwave metamaterial analog of electromagnetically induced transparency
- 2010
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 97:24, s. 241904-
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Journal article (peer-reviewed)abstract
- We report on our experimental work concerning a planar metamaterial exhibiting classical electromagnetically induced transparency (EIT). Using a structure with two mirrored split-ring resonators as the dark element and a cut wire as the radiative element, we demonstrate that an EIT-like resonance can be achieved without breaking the symmetry of the structure. The mirror symmetry of the metamaterial's structural element results in a selection rule inhibiting magnetic dipole radiation for the dark element, and the increased quality factor leads to low absorption (
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