Nowadays, rock excavating works and building destruction works near the habitation by utilizing the expansive agents have been increasing remarkably. In this case, reduction of the cost of works is an important problem.
This paper discribes at first the results of the basic expansive characteristics of the expansive agents which were obtained by experimental test. And then, using the cement mortar specimen, developing formof cracks were observed by experimental test. Moreover, the results were ascertained by numerical analysis named “Crack Analysis Method”.

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In deep coal mines, many microseismic events occur accompanying mining activities. If a microseismic event occurs near a working, it would be a hazard even if its scale is small. In this point of view, microseismic measurement is an important means to predict and prevent hazards such as rockbursts.
It had been realized that degree of microseismic activity is well represented by a variable called seismic energy release rate which is defined as a total amount of seismic energy during unit face advance. Therefore, a numerical method, which is based on three dimensional displacement discontinuity method (DDM), has been developed to calculate indices which are comparable directly with the seismic energy release rate. These indices are strain energy release rate and the energy release rate. The former is defined by the authors as a total amount of strain energy changes summed up over only newly fractured region of rock mass and coal seam with unit face advance, while the latter is more of a conventional concept and defined as a total amount of strain energy changes summed up over whole rock mass with unit face advance. Their behavior with face advance is compared with that of the seismic energy release rate obtained from the observation.
It is realized that the strain energy release rate obtained from the numerical model behaves in similar manner as the seismic energy release rate does, whereas the energy release rate behaves in completely different way. It implies that the simulation model could be used as a means to predict microseismicity.

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The present paper deals with a new nordal-point method for analysis of mine ventilation network. The new method adapts a new approximation procedure of static pressure at each nordal point which are obtained by minimizing total energy loss of flows around the nordal-point.
Present method was successfully applied to a simple model of ventilation network. The results of calculation were compared with already reported methods by Inoue & Uchino and Scott & Hinsley. It has been comparatively found to possess simplicity of procedure and rapid convergence with high accuracy to the answer for any initial values of nordal-point pressures.

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In this paper, the measuring results of gas emission and cuttings volume exhausted by the large diameter (250mmφ) boring for a prevention of gas outburst are described. The large diameter boring has been carried out from the heading of gateroad into advancing direction up to the depth of 20-30m.
Main results obtained are as follows.
(1) It is probably assumed that complicated seam condition is existent under such circumstances as cuttings volume over 1, 000l/m, boring time over 30 min./m or gas emission volume per cuttings over 100m³/m³ on the large diameter boring.
(2) The relation between cuttings volume and boring depth are classified into three patterns as shown in Fig. 7. In such a case that the peak position of pattern B-curve is located within the safety depth of existing borehole from the heading, it i s desirable to shift pattern B to A or C by new large diameter boring.

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Theoretical analyses on the capsule running were carried out by the method of characteristics under the three different conditions; polytropic, irreversible adiabatic (based on the energy equation) and isentropic changes. The results of comparing the characteristics obtained by each method are summarized as follows;
(1) Analytical results based on the polytropic change (n=1.01, 1.20) and irreversible adiabatic change agree well with each other. Therefore, the former analysis is more useful because of the more simplicity.
(2) The results obtained under the polytropic change with n=1.40 have a little difference from the others for the pressure change in the pipe.
(3) For the same convergence condition, the iterative calculation is necessary for the analysis based on the irreversible adiabatic change, but not necessary in other analyses.
(4) Calculated results based on the isentropic change don't agree with the results obtained by the other methods or experimental results.

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In fields of mining and public works a hydraulic breaker is used to break rocks and so forth. Recently, improvement of the performance and durability of the hydraulic breaker is required, as the works become on a large scale.
The authors have proposed a mathematical model of the hydraulic breaker which gives evaluation on the performance of the breaker. The model was directly solved by use of numerical calculation and the numerical result was compared with the experimental result. This paper is treated to obtain an analytic solution of the mathematical model of the breaker. A state-space equation is derived from motions of a piston and a valve, hydraulic oil flow and behavior of accumulators and solved. The result h as little distinction against the previous result of numerical solution.

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The choking-free cyclone was developed primarily to remove solid particles suspended in a slurry containing fibros mate-rials, such as municipal solid waste.
This cyclone is characterized by a screw conveyor at the underflow side of the cyclone. The screw conveyor has a holl ow rotational shaft for air supply and is driven by a variable speed motor for discharge control. Thi s cyclone has the excellent performance to catch the fluid state of underflow by detecting the shaft torque of the screw conveyor.
The separation size for the choking-free cyclone can be kept in a constant state in spite of fluctuations of feed, if the cyclone controlled by detecting the shaft torque of s crew conveyor and defining 5N obtained substituting ΔN calculated bythe equation (9) and d 175 for equation (10) as a manipulated variable.

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The difference in surface charge and floatability of chromites from various localities were clarified, and the relationship between mineralogical properties and these characteristics were investigated.
Followings are the summary of the results obtained.
(1) Although zeta-potential of chromites are varied by gangue minerals accompanying with them and the existance of metal ions in the chromite-water system, i.e.p.(isoelectric point) of pure chromite which has fresh surface is around pH 8.0 regardless of the chemical composition.
(2) There are considerable difference in floatability among the chromites investigated, which is greatly influenced by the surface charge in the case of DAC and SDS as collectors. In addition, surface structure and crystallinity also produce an effect on the floatability, that is, non-homogeneity of the surface and internal structure tends to depress the floatability. The optimum particle size of chromite in flotation ranges 60-100μm, with the floatability diminishing out of this range.

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The oxidation of Fe (II) in weakly acidic solution containing Cu (II) was studied by blowing a mixed gas of 80% N₂ and 20% O₂ from an upward vertical nozzle into the solution. The adsorption of Cu (II) and Fe (II) on Fe (III) precipitate formed by the oxidation was also studied.
The experimental results are summarized as follows.
(1) The concentration of Cu (II) i in the solution tion which is not adsorbed on Fe (III) precipitate is apparently expressed as
[Cu (II) i] =0.25 [Cu (II)][Fe (III)] ^-0.2
(2) The oxidation is composed of the sequential steps of the dissolution of gaseous oxygen and the oxidation of Fe (II) by dissolved oxygen. The latter reaction is presumed to proceed along three paths:(i) homogeneous reaction in the solution in which Cu (II) does not participate, (ii) heterogeneous reaction on the surface of Fe (III) precipitate and (iii) homogeneous reaction in the solution in which Cu (II) reacts as the catalyser.
(3) The oxidation rate of Fe (II) through path (iii) is expressed by
r₃=3.5×10³[Cu (II)][Fe(II)]²[Fe (III)^-0.2[O₂]]/17.1[Cu (II)][Fe (III)]^-0.2+[Fe (II)]
The oxidation rate of Fe (II) in weakly acidic solution containing Cu (II) is presumed to be the sum of the oxidation rates through paths (ii) and (iii). It is expressed as
-d[Fe (II)]/dt=(8.14×10³[Fe(III)]/1+36.2[Fe (II)]+3.5×10³[Cu (II)][Fe (III)]^-0.2/17.1[Cu (II)][Fe (III)]^-0.2+[Fe (II)])[Fe (II)]²[O₂].
The calculated [Fe (II)] and [O₂] from the above rate equation and the mass balance equation of dissolved oxygen agree with the observed values.

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Solvent extraction equilibria of Cu (II) from hydrochloric acid solutions with Acorga P-5100 have been studied at 298 K by using xylene as a diluent. For comparison, the extractabilities of Fe (III) and Ni (II) have been also examined. Moreover, the effect of p-nonylphenol and that of sodium chloride have been investigated. The results obtained are summarized as follows.
(1) The value of pH_1/2 increases in the following sequence: Cu (II)<Fe (III)<Ni (II). High selectivity for Cu (II) is also observed.
(2) It is estimated tha the extraction equilibrium is represented as follows:
Cu²⁺
(3) Distribution data of Cu (II) are reasonably explained by taking account of the series aggregation of the oxime and its adduct formation with p-nonylphenol. Apparent constants of the stepwise aggregation and the adduct formation are determined to be 0.8dm³/mol and 1.2 dm³/mol respectively. Apparent extraction constants at various pH values are also determined.
(4) The addition of sodium chloride causes a slight decrease in the distribution ratio of Cu (n) at a constant hydrogen ion concentration. This phenomenon is interpreted by means of the model of Cognet et al.; where the empirical determination of BCuCl₂ value in Bromley's formula for the activity coefficient estimation is necessary.
(5) In the above phenomenon, the increase in the hydrogen ion activity due to the decrease in free water plays an important role.

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