A scale model study was carried out to clarify the source mechanisms of acoustic emissions induced.by excavating an underground flat opening. AE signals during excavation were detected by six accelerometers embeded in the strata model and their source mechanisms were determined from two dimensional moment tensor inversion.
The experimental results confirmed that the source mechanisms of acoustic emissions depended on their source location relative to the opening. The AE waveforms from the front of the opening showed compression or double-couple type of source mechanism. The more the source location was remote from the opening, the more double-couple type became predominant. On the other hand, the AE signals above the opening showed broad spectra in their source mechanisms including tensile type as well.
A numerical experiment by FEM suggests that moment tensor of AE around an underground opening reflects stress tensor by which the fracture criterion of the focal region of AE is satisfied.

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The mixing properties of an ore pass system have a significant importance for a quality control, especially in quarries, through blending in ore pass systems. In this study, an experiment to clarify the mechanism and the properties of the mixing was performed using glass beads (as the boulders) and a scale model of a particular ore pass system.
Especially in vertical systems, mixing except in the periphery mainly occurs in funnel flow region. The point in the ore shaft part where the flow begins to funnel tends to become higher and the mixing will be promoted, according to the intention of the interlocking effect of the beads. The calculated mixing property curves, which are based on the assumed apparent descent velocity field in the funnel flow region, were in good agreement with the result of the experiment.
The discontinuous gravity flow, which is usual with the real ore pass system, could not be reproduced in this experiment. Therefore, a particular mixing in the inclined ore pass depending on the discontinuous action of the flow could not be seen. Nevertheless the mixing was slightly more promoted in the inclined systes compared to the vertical systems.

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In this paper, drag coefficients of sphere and non-sphere ice particles and its effects on pressure loss in icewater two-phase flow were described. Drag coefficients of sphere ice particles fell close to the previous CD-Res curve (drag coefficient-particle Reynolds number), while those of non-sphere ice particles were in the range of 1-6 in this experiment.
Particle motion in water was analyzed by the equation of motion taking into account Basset term. By comparing the experimented particle trajectories with calculated ones, it was confirmed that the Basset term played an important role in motion of particles with densities near that of water such as snow, ice and polystyrene.
Pressure loss for ice-water two-phase flow was measured and compared with the results calculated by Durand'sand Newitt's equation. The use of adequate drag coefficient in Durand's equation gave a good agreement between the experimental results and calculated ones at low velocities. At high velocities, a discrepancy was observed because Durand's equation always gave positive values, but negative values of pressure loss coefficients were obtained in this experiment. Newitt's equation showed larger values than the experiments because this equation was applicable to the flow with a moving bed.

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The flotation of -10 μm diameter quartz particles using dodecyltrimethylammonium bromide (DTAB), one of the typical complete ionizable collectors, was carried out at pH 5, 7.4 and 10 by varying the DTAB concentration in the presence of 1×10^-3 mol·dm^-3 KNO₃ as a supporting electrolyte. The adsorption density of dodecyltrimethylammonium ions (DTA⁺) and zeta potential of quartz were also measured in order to analyze the flotation results. The results obtained are summarized as follows.
1. Almost complete flotation is achieved at a surface coverage of DTA⁺ of the order of several percent on quartz surfaces.
2. The negative zeta potential of quartz decreases with DTAB concentration and changes its sign after passing through an isoelectric point (iep) at some particular DTAB concentration depending upon the pH of the solution. By analyzing the adsorption data at the iep using Stern-Langmuir adsorption isotherm, the free energy change of specific adsorption of DTA⁺, ΔG_sp, was obtained as follows: pH 5, -4.4 kcal·mol^-1; pH 7.4, -4.7 kcal·mol^-1; pH 10-5.9 kcal·mol^-1.
3. The bilayer adsorption of DTA⁺ occurs simultaneously on top of the first monolayer formed patchwise on the surface even at low surface coverage of DTA⁺, whereby the quartz surfaces are made hydrophilic and flotation ceases. No flotation occurred at an adsorption density of DTA⁺ corresponding to θ_DTA⁺=100%(corresponding. to the first monolayer coverage of 50%) at pH 10. This contrasts with the result of dodecylammonium acetate (DAA) at pH 9.8, in which quartz showed complete flotation even at an adsorption density of DAA corresponding to a bilayer adsorption. This is in support of the capillary condensation of undissociated dodecylamine at the point of contact between fine grained quartz particles.
4. There was no significant difference in the adsorption and flotation behavior at pH 5 between DTAB and DAA.

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A disk mill with several rings and a rod as grinding media in the chamber was developed. There is much frictional crushing between grinding media and a chamber in the mill. It is generally accepted that frictional crushing is effective for ultrafine grinding. There is the possibility of realizing the disk mill can produce alarge quantity of submicron particles with less energy consumption.
Effects of rotating speed of the mill, the feed weight and etc. on grinding performance were tested to obtain the optimum operating conditions for the disk mill. And it was proved the median size of ground product was not related to rotational speed but total number of rotations.

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The Huanuni ore deposit in the central part of the eastern Andes is a representative tin vein type ore deposit in Bolivia, The veins consist of cassiterite as a economic mineral, being associated mainly with pyrite, pyrrhotite, quartz, tourmaline and rutile.
In this study, the species, grain sizes, shapes of the grains, types of intergrowth, compositions of grains, etc., of each mineral were characterized to assess the liberationcharacteristics of the ore. Observation on polished specimens under the microscope, heavy liquid separation, powder X-ray diffraction and chemical analysis by ICP were the techniques used to accomplish the mineral liberation study.
Samples collected from the feed in the Huanuni's beneficiation plant were ground and classified into 6 size fractions from mesh Nos. 2 to 200. Each fraction was then separated according to their densities into 8 ranks from+3.20g/cm³ to -2.05 g/cm³.
The density spectrum has been distributed into two fraction groups, one of +3.20 g/cm3 and the other of -2.90g/cm3, with lack of intermediate density fractions between them.
X-ray diffraction and microscope analysis have revealed that the heavy group was characterized by the presence of predominant sulfides-cassiterite, and the light one by predominant quartz. The results were confirmed by the chemical analysis of tin and iron. Detailed particle counting under the microscope indicated that about 70% of total cassiterite was liberated by grinding the raw ore to sizes of -100 +200 ineshes. However, some “liberated” cassiterite particles, even in the finer fraction (-150 +200) still contained inclusions of about 3 pm to 15 pm of tourmaline, pyrrhotite, pyrite and rutile.

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The electrodeposition of copper was carried out at 298 K in 1M CuSO₄-0.5M H₂SO₄ solution with KCl. The effect of the KCl concentration in the solution on the morphology and on the crystal orientation of the deposits were investigated in comparison with the behavior of the interfacial impedance response in the deposition process. The KCl concentration affected the morphology and the orientation of the deposits. In the solution with 100 mg/l KCl, the deposits have the (220) orientation and the surface morphology with the shape of many pyramids. The impedance data were analyzed with respect to a non-linear model. The parameter θ, which corresponds to the uniformity of the surface of the deposits, has minimum value (good uniformity) in the solution with 100 mg/l KCl. It was found that the parameter θ is related to the surface uniformity.

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Using a pilot flash furnace with the capacity of about 1 t/h, suspended copper concentrate particles were water-quenched in the reaction shaft and the settler. These samples as well as dust generated from the furnace were examined by optical microscope. The results are summarized as follows:
(1) Final products in the reaction shaft consisted of molten excessively oxidized particles rich in chalcocite or bornite and solid less oxidized chalcopyrite particles.
(2)The molten excessively oxidized particles were much larger in size than the original and many of them had relatively large amounts of slag.
(3) However neither of solid particles with oxidized rims nor cenospheres showing fragmentation were observed.
(4) The above results have proved the validity of a two-particle model14) for copper flash smelting.

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