Most geothermal areas in Japan are located in the volcanic provinces of complex geology. The seismic reflection method which is considered to be one of the best of the existing exploration techniques for the detailed subsurface structures has been applied to clarify the deep geothermal, geological setting. However the most results obtained are far from satisfactory.
Some of the reasons for it are,
1) actually, there exist no reflecting boundaries,
2) too many conflicting reflections returning from subsurface produce complex reflection patterns.
Supposing that the second case is true, there may be certain methods for decomposing such events to get true subsurface structures.
In this paper, one method of separating reflection events through a moveout domain transformation using a stacking technique along each reflection lineup is presented.
The basic idea is examined by some synthetic seismogram sections proving its effectiveness, then the underlying basic concepts also studied in spatial frequency domain using characteristic transfer functions.
The basis of this method is one of the reflection picking techniques, thus the results are easily displayed by a conventional x-y plotting device.

抄録全体を表示

It has become very important in estimating the strength, the permeability and the other properties of rock to detect the distribution, the direction and the width of cracks in rock.
A crack-detector which can obtain the crack distribution and the sonic velocity change in rock, as already stated in 1st report, had been developed in this study.
The in-situ tests using a crack-detector which improved the inadequate points of the old type crack-detector are described in this report. It is the characteristic of the new type crack-detector with rotating two probes as show in Fig. 1 that the time required for a round measurement of its crack-detector is saved than that of the old type crack-detector.
The results obtained from the basic and the applied research for the study of crack distribution and sonic velocity change in, rock are as follows.
1) As basic research for this study, the measurements of crack distribution and sonic velocity change were made on the surface of concrete floor with cracks. The results obtained from the basic research are shown in Fig. 3. The maximum value of sonic velocity of concrete floor, as shown in Fig. 3, is nearly equal to that of the concrete specimen. It is also clear that the patterns of pulse waves differ in the condition of concrete floor, that is the intact parts, the parts with closed cracks and the parts with open cracks, as shown in Fig. 2.
2) At Yaguki mine, Fukushima prefecture, the crack distribution and the sonic velocity change of rock were measured by inserting the crack-detector in NX boreholes. From the measurements, it is seen that the maximum value of sonic velocity in Fig. 6 is nearly equal to the velocity of specimen which is collected from the rock. Considering that the amount of scatter of sonic velocity as shown in Fig. 6 is closely related to the properties of rock, the correlation between the coefficient of variation of sonic velocity and RQD (Rock Quality Designation) obtained from NX- boring core is investigated. It is recognized from Fig. 7 that the coefficient of variation has linear correlation with RQD.
3) The results of in-situ measurements at the underground of Shakanai mine, Akita prefecture, are similar to those at Yaguki mine, as shown in Fig. 10. But, the coefficient of variation of sonic velocity has not a correlation with RQD, because the rock situated in where in-situ measurements are performed has many fractures along the core axis.

抄録全体を表示

A method of determination of the fracture toughness of rocks has been studied in this paper. The fracture toughness is obtained by the splitting test under the stiff-load as shown in Fig. 3. The rock specimens in which have a slot as Fig. 2, are prepared in this test. The slot produces a stress concentration around the tip of slot when the splitting force is applied to the slot, and a crack occurs from the end of slot into the rock specimen as. Fig. 4. The crack initiation and the process of crack propagation are studied by the measurement of splitting load and crack opening displacement, and the observation of crack propagation.
The main results obtained in this study are as follows;
1) When the splitting force which becomes increase gradually reaches to the tensile strength of rock, a fracture cracki nitiates and propagates into the rock specimen. From these tests, splitting load crack opening displacement curves are obtained as Fig. 5. Further, the growth of fracture crack in the post failure region is controlled by the stiff-load as Fig. 4.
2) Values of stress intensity factor KI are determined experimentally with the compliance method as Fig. 9. From this study, it becomes clear that the fracture crack propagates unstably when KI exceeds the constant value, namely, thef racture toughness KIC. From above, it is considered that Kw is also the material constant of rock.
3) The splitting tests of rock specimens with different height, width, and thickness are undertaken in order to obtain the size effect on the fracture toughness. It is considered from these tests that the suitable size of tuff specimen used for the rock splitting test is 200mm×150mm×20mm as shown in Fig. 10, Fig. 12 and Fig. 13.

抄録全体を表示

Experimental studies were carried out to investigate explosion characteristics of coal dust-rock dust (limestone) mixture. The apparatus used was of closed-type (Combustion and Flame, Vol.21, No.2). Before experiments, the rock dust percentage, R, in the cloud of mixture was experimentally confirmed to be equal to that of mixture. R is defined as
R/100=r/D=r/(r+c)
where D: total dust concentration
r: rock dust concentration
c: coal dust concentration.
Relations between R and D, r and c, r/c and c, and R and c under the condition of explosion limit are shown, respectively, in Figs. 13 and 14, Fig. 15, Fig. 16, and Fig. 17 in the text. As a result, it was found that
1) reduction of the explosion pressure by the rock dust mixed may be little, if rock dust mixed is not sufficient to suppress the explosion completely (Fig. 12),
2) the minimum rock dust concentration may be defined to suppress explosions at any coal dust concentration, and the highest value of the minimum rock dust concentration obtained in the present study is ca. 1300g/m³ for Horonai coal of 270-400 mesh in size (Fig. 15),
3) the rock dust percentage required to suppress the explosion at the coal dust concentration of 250g/m³ may be considered as the minimum rock dust percentage required for suppression of explosions at any coal dust concentration (Fig. 17).

抄録全体を表示

The removal of arsenic from waste water has been investigated by means of coprecipitation with aluminum hydroxide or ferric hydroxide. Artificial waste solutions cotaining 10mg/l of As (III) or As (V) were used as experimental solutions.
The results obtained were as follows:
1) By the coexistence of 200mg/l of aluminum ion, As (III), was scarecely removed at all pH range, whereas As (V) was lowered to about 2mg/l at pH range between 5 and 8. The removal of As (V) may be attributed to the adsorption of As (V) anionic species on the surface of aluminum hydroxide.
2) When ferric ion was added to the waste water, As (V) was effectively removed over wide pH range, even though the addition of ferric ion was low. The settling characteristics of ferric hydroxide coprecipitated with arsenic were rather poor, meanwhile the arsenic concentration of supernatant solution after settling the precipitate for 3 hours was remarkably higher than that of the filtrate. In order to reduce the concentration of As (III) to meet the effluent standard (0.5mg/l) by settling the precipitate for 1 or 3 hours, it was necessary to add ferric ions in the weight ratio of more than 20 or 10, respectively, against arsenic involved. The concentration of As (III) in the filtrate, however, could be reduced to 0.5mg/l by adding ferric ions in the weight ratio of 3 against arsenic involved. While, in the case of As (V), the addition of ferric ions in the weight ratio of more than 10 or 5 against arsenic involved was sufficient for reducing the concentration of arsenic to 0.5mg/l by settling the precipitate for 1 or 3 hours, respectively. Also, the concentration of As (V) in the filtrate was reduced to 0.5mg/l when ferric ion was added in the weight ratio of 0.75 against arsenic involved.
3) The removal of As (V), which was obtained in the presence of ferric ions in a limited acidic pH range, may be due to the formation of ferric arsenate, while the removal of As (V) in a higher pH range could be explained by the specific adsorption of As (V) anionic species on the surface of ferric hydroxide. On the other hand, As (III) is considered to be removed only by the specific adsorption of As (III) anionic species on the surface of ferric hydroxide.

抄録全体を表示

For a hydrodynamic approach to the flotation process, the collision of particles with air bubbles in fllotation cells was studied in terms of the turbulent diffusion model and Kolmogoroff's theory. Comparison of the theoretical development and the experimental work resulted in the following conclusions:
(1) the average diameter of air bubbles generated in the flotation cell is expressed by eq.(11).
(2) the gas-liquid interfacial area in the flotation cell was measured using the method of CO₂ absorption into the aqueous solution of NaOH to deduce eq.(18).
(3) the rate constant of the collision is given by eq.(25) supposing that the dissipation energy in the cell varies proportionately with the agitation energy.
(4) the flotation rate constant obtained from flotation tests is in accordance with eq.(25).
(5) the appropriate agitation energy may be decided from the consideration of the rate constant given by eq.(27) oreq.(28) and the power consumption of the flotation cell.

抄録全体を表示

Hydrometallurgical process, leaching out metals into the solution from ores at low temperature, is more economical consumption of energy than the high temperature treatment as the smelting process. The purpose of this study, is to research for the optimal condition of the leaching process of nickel by nitric acid solution from garnierite ore. In above mentioned treatment, metal, leached out into the solution from the ore, is not only nickel but also iron and magnesium etc. The extractions of these metals are affected by the leaching conditions.
In this report, the experimental conditions were arranged to the table of orthogonal array. The data obtained from these experiments were treated statistically, and the factorial effects of a series of experiment wee evaluated. In the sphere of these experiments, the condition of maximization of nickel extraction was pursued, and in this condition the extractions of nickel, iron and magnesia were estimated as follows:
Ni=98.4-99.0%, Fe=47.1-55.1%, MgO=87.1-92.9%.
Standing on the viewpoint of the industrial evaluation, the extraction of nickel in this condition will be regarded as satisfactory. The extractions of iron and magnesia, however, cannot be so. Where, the development of this statistical treatment, that is, the steepest ascent method will be lead our study to discover the industrial optimal condition.

抄録全体を表示