The stability evaluation of large rock slopes left after surface mining in limestone quarry has become to be most important engineering problem. In the mining engineer field, it is the very effective way for mining planner to simulate the final slope model using computer analysis in the first process. And, it is very important to propose the slope models from the several geological conditions and field observational measurements during mining operation in the next process. In this way, it becomes to be most important for mining engineer how to estimate the slope modelling, geological conditions and field measurements.
In the final mining plan at Yoshii Limestone Quarry (located in border of Hiroshima pref. and Okayama pref.), there will appear in near future large rock slope having two different caves which remained after past underground stopping. In such case, we have to consider the three-dimensional influences between two caves and slope.
This paper describes the investigation on the rock slope stability of Yoshii Quarry using 3-D B.E.M.(three dimensional boundary element method). And, it describes the critical block on the slope by the geometrical conditions of discontinuous planes using the block theory.

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The effect of pore gas pressure on the mechanical behavior of rocks has been investigated in order to confirm the validity of the effective confining pressure law among rocks. The triaxial compression tests of Noboribetsu welded tuff, Horonai sandstone (A), (B), Akabira sandstone and Akiyoshi marble were carried out with the strain rate 1.3 × 10^-4/sec for confining and pore gas pressure combined with a conventional hydraulic testing machine. The stress strain curves of five kinds of rocks were determined under the condition of confining and pore gas pressure extending up to 50 MPa.
The experiments show that the effective confining pressure law was valid for more porous and permeable rocks such as Noboribetsu welded tuff, Horonai sandstone (A), (B) and Akabira sandstone but Akiyoshi marble was not possible to adopt this law.
The mechanical behavior of rocks whose pore are not fully saturated with gas pressure seems to largely depend on magnitude of the confining pressure acting on specimens.

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The concentration distribution in a pipe transporting solids is considered the most important parameter in distinguishing flow patterns which can be associated with the prediction of pressure dorp.
The diffusion equation for suspended solid particles could be solved analytically, leading to transcendental equations, which would be dependent on the value of the index of the Richardson-Zaki equation for the hindered settling velocity of the solids. Although these equations, based on a diffusion model, have an advantage of simple calculation for relative concentration, we cannot calculate absolute in-situ concentrations without precise reference concentrations. Therefore an application technique of the Einsten equation for river mechanics to the slurry flow in a pipe were developed and discussed with calculated results.
Furthermore, using a composition method for integrating the transcendental equations, a numerical method was proposed in determining the reference concentrations and then computing the concentration distributions. This method revealed the influence of transport conditions such as the diameters of pipe and solid particles, delivered concentration, and the mean velocity of slurry flow on the concentration distribution. Finally, the parameter related to the degree of homogeneity of the suspended solids and the dimensionless parameter introduced by Batchelor into the diffusion equation were correlated.

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In order to realize the vegetative slope in open-cut mining, non-erosive soil materials have been developed in this study.
The non-erosive soil was compounded from the tailings of cyanide leaching at the Kushikino gold mine through the following two processes ;(1) a mixture of the tailings, water and portland cement was crushed under 12 mesh after the primary generation of cohesive strength for a specified time, (2) the crushed products were applied to the test of the secondary generation of cohesive strength after charging in a pot and consolidating under various compressive stresses.
The structure of the non-erosive soil is composed of soil particles and voids surrounding the particles. The soil particles and voids are formed as the results of the primary generation of cohesive strength before the crushing and the secondary generation of cohesive strength after the consolidating respectively. The soil properties required to satisfy the vegetative conditions result from such agglomerate structure of the soil particles. From the facts described above it is concluded that the vegetative and the non-erosive conditions of the soil are satisfied simultaneously by controlling the curing and solidifying time from mixing to crushing and the secondary generation of cohesive strength.

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In this study non-erosive soil materials have been developed in order to realize a green slope in opencut mining. Practically, the vegetation limit and the erosion limit of artificial soil were determined on the basis of the vegetation tests of lawn grass and the erosion tests by water jet respectively.
The specimens of soil were made of the tailings of cyanide leaching at the Kushikino gold mine through the following two processes;(1) a mixture of the tailings, water, portland cement and woody fi ber was crushed under 12 mesh after the primary generation of cohesive strength for a specific time, (2) the crushed products were applied to the tests of the secondary generation of cohesive strength after charging in a pot and consolidating under various compressive stress.
From the results of the above tests it was proved that the cohesive strength R{τ, ρ, η} of the soil could coexist within the range between the vegetation limit Vc and the erosion limit E_c as given by the following inequality.
Vc >R{τ, ρ, η} >E_c
Here, the time τ of the primary generation of cohesive strength, the consolidating stress ρ and the fiber content η are the parameters of the soil strength. The measured values of V_c and E_c were 140 and 60 kg f/cm² respectively.

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The authors used 10 coal samples, which were vitrinite rich and of different coal rank (carbon content were from 70.0 % to 87.4 %), and the relation between maceral compositions in vitrinite group and grindability indicated by the Hardgrove grinding index (HGI) was elucidated.
Brittleness of the coal structure rather than its hardness dominates coal grindability. The brittleness of collinite and the collinite content have a specific relation with HGI and coal rank. Higher rank coal includes a higher collinite content, and the collinite becomes increasingly brittle with increasing coal rank and collinite content; in the results, the HGI of the coal samples becomes higher.After grinding coal samples by a Hardgrove grinding tester, the collinite content in the fraction of -75μm increases with higher HGI. These results show selective grinding of collinite and indicate that only collinite in vitrinite group has a strong influence on coal grindability.

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Mitsui Kushikino Mine previously processed two gold ores from Kushikino and Iwato ore deposits by the all silme cyanidation method, where the ores were ground to fine size smaller than 75μm and leached with sodium cyanide. A large amount of slimes were produced as waste and discarded in tailings ponds. To save the costs of grinding and waste treatment it is desirable to process coarse sized ores. The Iwato ore is gold and silver bearing silicified porous rock. As most gold and silver in the Iwato ore are concentrated in the pores, leaching of coarse sized ore is expected to be possible. Laboratory tests and pilot plant tests of vat leaching for the Iwato ore were carried out using 0.15-8.0 mm feed. These results showed that the gold dissolution rate was similar to that by the all slime cyanidation and the decrease in gold recovery was a few %. The properties of these tailings can be used in fine aggregate of concrete. Based on the results vat leaching of the Iwato ore was adopted in the plant. The tailings are sold and used as fine aggregate. Utilization of slime tailings from the other ores was also developed and they are used as flux in copper smelters. Now, there is no tailings pond at Mitsui Kushikino Mine.

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The effect of Fe (II) ions on pyrite dissolution with Fe (III) ions around pH 2 was studied. The Fe (II) ions suppressed the dissolution of Fe and S species from pyrite. No secondarily formed compounds were detected. This indicates that Fe (II) ions inhibit the reaction of pyrite with Fe (III) ions. The inhibition may be caused by the preferential adsorption of Fe (II) ions on active S-sites in pyrite over Fe (III) ions.

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As a fundamental study of the Warner process, phase relations in the Cu₂S-ZnS-FeS and Cu₂S-ZnSPbS pseudo ternary systems and the Cu-Zn-S and Cu-Zn-X-S (X: Fe, Pb) systems were determined at 1, 473 K. In the Cu₂S-ZnS-FeS system, the solubility of ZnS in the liquid phase is considerably small at less than N_zns=0.1 in the high Cu₂S and FeS composition ranges. The solubility of Cu₂S in the solid solution of sphalerite (Zn; Fe, Cu) S is also considerably small when conjugated with the high Cu₂S melt. In the Cu₂S-ZnS-PbS system, the solubility of ZnS in the liquid phase is around N_zns=0.1 in the low composition range of PbS. The Raoultian activity coefficients of ZnS in these pseudo ternary systems at 1, 473 K, which were determined from the obtained phase relation data, are very large at about 10.
In the Cu-Zn-S ternary system, a two-phase region consisting of the L₁ alloy phase rich in copper and the L₂ matte phase exists in a considerably wide composition range from N_zn =0 to about 0.2. When 3.4, 4.3 or 5.5 mole % Fe is added to the Cu-Zn-S ternary system, the range of the two-phase region of (L₁ + L₂) in the quaternary system is wider than that in the Cu-Zn-S ternary system. While, when 0.8, 1.5 or 2.4 mole % Pb is added to the Cu-Zn-S ternary system, the range of the two-liquid region does not change with the lead content.
The distribution ratios of iron, lead, arsenic, antimony and silver in the matte (L₂) against the alloy (L₁) in the Cu-Zn-S, Cu-Zn-Fe-S and Cu-Zn-Pb-S systems are approximately 6, 0.4, 0.1, 0.05 and 0.4, respectively.

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Removal of antimony by volatilization from an industrial copper matte or white metal was carried out at 1, 523 K. The experimental conditions favored to the effective removal of antimony was selected from the thermodynamic considerations.
H₂S gas was used as a bubbling gas to increase the partial pressure of sulfur and simultaneously the activity coefficient of antimony in the melt.
The antimony concentrations both in the matte and white metal were effectively lowered by bubbling 10% H₂S-Ar mixed gas into the melt under a reducing atmosphere.
In the case of matte, for example, antimony was removed from 2, 000 mass ppm to a level of 10 mass ppm in 3.6 ks at a gas flow rate of 8.3 cc/s.

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