Hydrometallurgical process involving the electrodeposition of iron-group metals such as Fe, Ni and Co can be found in various industrial fields. An anomalous codeposition behavior in which less noble metal deposits preferentially appears frequently in the codeposition of iron-group metals with others. In the present paper, the examples of the preferential deposition of less noble metal was demonstrated in the electroplating of Zn-iron-group metal alloys and the hydrometallurgical processes of electrowinning of Zn and electrorefining of Fe in sulfate solutions. The electrodeposition behavior of iron-group metals in above three processes was discussed based on the hydroxide suppression mechanism proposed for the anomalous codeposition.

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Image processing is rapidly becoming popular in applied geology. However, it is often difficult to extract the object from other parts by image processing. In order to facilitate visual recognition, pre-processing before image input is useful. Therefore, the object is coated with the fluorescent paint on the photograph, and then examined under ultraviolet ray. The technique is effective for image processing because obtained images display a great difference in both brightness and color between objects and other parts. Three images were obtained by a CCD camera using optical filters (red, green and blue filter), and processed in several steps, including image sharpening, thresholding, and inter-picture operation.
The gold vein in the Hishikari Mine were examined through the method described above. The gold veins in the mine were classified as three types (network veins, a banded vein, and complex veins with the different vein widths from the geological point of view). They demonstrate that all types of veins can be extracted practically from the host rock. The ore grade can accurately and easily be calculated by image analysis combined with chemical analysis.

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A test site with rare frequency of joints was selected in a granitic area in China. Total number of discontinuities were 37 from the surface down to the bottom of a 300 m long borehole. Brazilian strength of the core sample was almost constant along the entire borehole. Pressure pulse tests revealed that there are three regions with low, medium and high permeability along the borehole.
In each of the three permeability regions, hydrofracturings at slow and fast pressurization rates were performed. Most fractures induced were vertical. The direction of them were consistently N6E ±15°. The breakdown pressure Pb was about 14 MPa in the shallower part, and 20 MPa in the deeper region.
In the high permeability region, Pb at slow pressurization rate was clearly lower than that at fast rate. On the other hand, Pb at both fast and slow rates were almost the same in the low permeability region. This result suggests that the increase of pore water pressure around the borehole decreases Pb. Based on this point, normalized pressurization rate has been introduced. At normalized pressurization rate larger than 0.1, the change of pore water pressure is negligible, and does not affect the result of Pb. While Pb decreases considerably at a lower normalized pressurization rate such as 0.001.

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Laboratory experiments have been carried out to investigate the influence of the geological processes on the fabric of the Ishikari sandstones belonging to the Ishikari coal formation of the Tertiary era. For comparison purposes. Taiheiyo and Shirahama sandstones have also been investigated.
It was clear that the velocity of P-waves transmitted parallel to the bedding planes is higher than the perpendicular ones; and that the velocity distribution within the bedding planes can be approximated by the anisotropic model in the case of Ishikari sandstones, and by the isotropic model in case of other sandstones.
Based on microscopic observations of thin sections, the following were common features in every specimen. Rock had planar structures and sutured grains existed, indicating that the rock had experienced “pressure solution” during compaction. In the case of Ishikari sandstones, open elongated pores had preferred orientation coinciding with the direction of the minimum P-wave velocity (L-direction). In other rocks, this characteristic was not recognized. Differences in P-wave velocities perpendicular and parallel to the bedding, and anisotropies within the bedding planes could be explained by these planar structures and by the preferred orientation of open microcracks, respectively.
It is interesting to note that the L-direction was perpendicular to the folding axis which characterizes the geological structure of the Ishikari formation.

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Triaxial compression tests on Ishikari sandstones, using a stiff servo-controlled machine, have revealed the following:
1. The peak strength criterion is expressed as a bent line in the (σ₁-σ₃)-space. The shear angles predicted based on the criterion coincide with the measured ones, and their values are constant for confining pressures higher than the pressure corresponding to the bending point.
2. When the difference between the maximum and minimum P-wave velocities is more than 4 %, the preferred orientation of the shear plane coincides with the direction of minimum velocity. On the contrary, when this difference is less than 4 %, the shear plane is randomly oriented. A yielding zone develops around the shear plane, whose width become narrower with the degree of brittleness. Inside this zone the material readily disintegrates when dipped into water, due to loss of cohesion.
3. Single shear-type fracturing is dominant for the specimen whose P-wave velocity transmitted perpendicular to the loading axis shows anisotropy; and cross-shear type for specimens whose velocity profiling reveals isotropic condition.

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The methods of filling with waste sand, rock and tailings have been widely utilized in the mines because of restraining the failure of pillar, lowering the subsidence of surface, minimizing roof falls and accidents due to falls, and so on. But, the supporting effect of the filling materials on the pillar in mine has not yet been clarified.
In this study, the model tests are carried out unedr the low confining pressure by using the rock specimens regarded as the pillar of mine in order to investigate the deformation and strength of the pillar at the low confining pressure of filling materials and fluid.
The results obtained in this study are summaried as follws;
1) In the range of confining presure from 9.8 kPa to 19.6 kPa, the maximum compressive strength of the rock specimen doesn't increase with the confining pressure, but the negative slop obtained with the filling marerial is gentler as the confining pressure increases.
2) The redisual strength of the rock specimen under the confining pressure of the filling material takes a larger value than that under unconfing or the confing pressure of fluid. Also, it is larger with increasing the axial strain.
3) Under the confining pressure of the filling material, the high confining pressure is induced near the failure plane.
4) The confining pressure of the filling material, which is induced during the failure process of the rock specimen, is larger with increasing the initial confining pressure.
5) From the experimental results with the rock specimens and the specimen made of aluminium, the effect of the filling material on restricting the failure of the pillar becomes greater in the order, wet tailings, wet sand, dry sand.

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The objective of this report is to investigate methods for the estimation of both rock strength and the tooth wear of roller cone bits while drilling. Drilling tests were conducted using milled tooth bits of 98.43 mmdia with different tooth wear. Two types of andesite, tuff and sandstone were drilled in the tests. The uniaxial compressive strength of these rocks ranged from 14.0 MPa to 118 MPa.
We first obtained the equations for the primary performance lines of each bit from the plots of F/d vs. u/N and 8T/d² vs. u/N for each rock, where F is the bit weight, d the bit diameter, u the penetration rate, N the rotary speed, and T the torque.
Second, we estimated information related to rock strength using multiple regression analysis, based on the equations obtained. From this estimation, the relation between F_eu /Nd and (8F_e/d²) ² was investigated, where F_e is the effective weight and T_e the effective torque. From the investigation, it became clear that this relation is closely linked to rock strength, as shown in Fig. 8. Thus, the drilling strength of rock (D_s) was defined based on this relation.
Finally, the method to estimate tooth wear, based on D_s, was investigated. This investigation revealed that the condition of tooth wear can be estimated from the relations between D_s and I_s, D_s and F_c/d, D_s and S_e, D_s and 8T_c /d², where I_s is the penetration strength of rock, Fe the threshold weight, S_e the specific energy calculated from the effective rotary energy, and T_c the threshold torque.

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An artificial fracture made by hydraulic fracturing plays an important role as a heat exchanger in Hot Dry Rock geothermal system. An estimation on distribution of fracture width before hydraulic fracturing is necessary in designing HDR system. A laboratory test was carried out to estimate the width of an artificial fracture. A cubic rock specimen, Inada granite, was set into a rigid steel frame, and hydraulic pressure was applied to make a fracture. After hydraulic fracturing, water was injected. A flow rate of injected water was increased step by step. An injection pressure, flow rate and displacements of free surfaces were measured during these injection tests. Unlikely to similar experiments done before, the displacements of the free surfaces which was parallel to fracture were measured. Based on the experiment result, the distribution of fracture width and pressure along the fracture was estimated by using combine analysis of analytical and Finite Element Method. By the analysis proposed in this paper, the distribution of fracture width and pressure, which had been hard to be measured, could be estimated successfully.

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It is essential to dilute and remove heat, gases and dusts at heading faces for improvement of the working conditions. For establishing effective measures for this, we have to make clear the air-flow patterns around the face, but so far there are few reports on this problem.
From this point of view, the authors have measured the 3-dimensional air-flow vectors by an anemometer using ultrasonic waves in a real scale heading model, and performed the simulation based on k-ε model with SIMPLER algorithm for the same condisions in the experiments.
This paper shows the results of simulation coincide with that of the experiments and present simulation method can be successfully applied to estimate air-flow patterns in a heading face.

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In the previous studies on pulverization of limestone by a Tower Mill Pulverizer, a product containing particles finer than 10μm could be obtained using a newly developed Tower Mill KD-3. From now, the Tower Mill KD-3 needs a higher level of efficiency for its further development, that achieves a high recovery of fine particles from the pulverized products. With this purpose, a series of investigations have been carried out on different types of cyclones and classifiers to clarify the factors which could affect the recovery of pulverized particles: Single Cyclone with Spiral Ribbons (SCSR), Twin Cyclone (TC), Twin Cyclone with Spiral Ribbons (TCSR), Simple Classifying Part (SCP), Classifying Part with Inclined Sieves (CPIS).
The results of these investigations can be summarized as follows:
(1) An increase in the recovery of fine particles was recorded using a TCSR and a CPIS. In both cases the achieved performances are certainly due to the high air flow rate in the cyclone.
(2) The relationships between the maximum particle diameters and the 50 % particle diameters of the products were approximately straight lines whatever cyclones and classifiers were used.

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Experiments on oxidation smelting of zinc sulfide concentrate were carried out by using the injection technology on a pilot scale facility of which a smelting capacity is about 0.3t/h. Concentrate and fluxes were injected in molten slag with oxygen, and consequently, resultant zinc oxide was recovered as molten FeOSiO₂-CaO-ZnO slag. The following results were obtained in this study.
(1) The sulfide concentrate was oxidized sufficiently and melted into slag phase completely at the slag temperature more than 1, 180°C.
(2) The magnetite troubles of the slag, such as the formation of a mush layer and the build-up of the hearth, were avoidable by controlling both of the ratio of iron to silica and sulfur content in the slag. The ratio of iron to silica was 0.9 and sulfur content ranged from 1.5 to 2.0 mass %.
(3) The best operating condition found in this study is as follows; the slag temperature at 1, 250°C, (% Fe)/(% SiO₂) of 0.9, (% 5) of 1.5 to 2.0 mass % and (% CaO) of 5.0 mass % to obtain 20 mass %-zinc containing slag as the final product.

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