The influence of composition and temperature on the formation of solid solution x FeTiO₃ (1-x) Fe₂O₃ were examined, using artificial materials. The mixture of pure ilmenite and hematite, sealed in a quartz tube under evacuated approximately below 10^-3mmHg, was sintered in a furnace. The results obtained were as follows.
1) Ilmenite and hematite begin to dissolve each other at the temperature above 600°C. At the temperature range of 600-700°C, solid solutions, having two compositions, were formed overthe wide range of the initial compositions. These solid solutions did not turn into a single composition even after sixty hours of sintering. Solid solutions, having the single composition, were formed above 800°C.
2) At the temperature range of 600-800°C, spinel and rutile were formed with xFeTiO₃ (1-x) Fe₂O₃ solid solutions. This phenomenon was most obvious at 700°C and about x=0.3. This spinel was identified as magnetite.
3) There were two mechanisms to form x FeTiO₃ (1-x) Fe₂O₃ solid solution. One is the formation of xFerTiO₃ (1-x) Fe₂O₃ solid solution from the mixture of ilmenite and hematite. The other is the formation of magnetite and rutile from the mixture of ilmenite and hematite, followed by the formation of x FeTiO₃ (1-x) Fe₂O₃ solid solution. The former was remarkable at the compositionof x≥0.6 and the latter was remarkable at the composition of about x=0.3.
4) Solid solution x FeTiO₃ (1-x) Fe₂O₃, excluding magnetite and rutile, are formed over the whole range of compositions at the temperature above 1000°C. The magnetization increased with the decrease ofx, reaching the maximum at x=6.65 and then decreased. The magnetization of solid solution with the composition x<0.5 was very small, while the solid solution with the composition x≥0.5 showed ferrimagnetism. The magnetization curves of the latters was saturated but that of solid solutions (x≥0.5) preparedby slow cooling method was not saturated even at 9400 Oe.
5) When solid solution xFeTiO₃ (1-x) Fe₂O₃ formed at 1200°C was maintained at lowertemperature for appropriate time, the magnetization increased. Therefore the magnetization of solid solution obtained by the slow cooling method is higher than thatof solid solution obtained by the quenching method.

View full abstract

At two closed mines, Kanagato (in Yamaguchi Pref.) and Takahi (in Yamagata Pref.), application of the mine sealing has been carefully considered in order to prevent the pollution due to the underground mine water drainage, now. Authors tried numerically to estimate the amount of mine water drainage in each of these mines.
First, a numerical analysis on the ground-water infiltration was carried out on the cone-shaped ground model with a gentle slope by using the finite element method on a field problem, and consequently characteristics of the free ground-water surface and the effluent seepage from the water-bearing zone in this model were derived.
Next, a hydrological survey for distributions of the source and the water flow on the surface stream was carried out on each of these mine areas, and consequently the mean recharged value of ground-water and the apparent permeability of ground were decided.
Lastly, the amount of underground mine water drainage, when the sealing would be performed in each mine, was predictedby the computational method developed previously, as described in the 1st and 2nd reports. As the result, it was predicted that on the amount of mine water drainage about 40% in Kanagato Mine and 20-50% in Takahi Mine could be decreased by sealing, respectively. Moreover, many useful data concerning the mine sealing were obtained.

View full abstract

Laboratory experiments were conducted to examine the validity of the observation equations 1 through 6 in the hydrofracturing stress measurements. Three kinds of rock materials having properties as shown in Table 1 were tested using the apparatus as illustrated in Fig. 2, under the controlled pressurizing rates of 1.0 to 200kg/cm² s for fluid injection, and under the various confining pressure up to 250kg/cm². The results of this study may be summarized as follows:
1. The relationship between the breakdown pressure (P_c) and the confining pressure (σ∞) of these materials was found to be linear as described by Eq. 1, at least in a range of low confining pressure levels (Figs. 7, 8, 9, 10 and 11). However, it was observed in the samples of mortar and plaster that the P_c-σθ curves were bent over a critical confining pressure (Figs. 8 and 9).
2. For permeable materials, it was recognized that the breakdown pressure was liable to be influenced by the flow rate of injection (Fig. 13).
3. Stable crack growth could be achieved, too, for the permeable materials, bymeans of repetition of the testing procedures which consist of first pressurizing to the maximum value then followed by shut-in of the injected fluid and/or by releasing fluid (Figs. 4 and 5). The results of these tests revealed that the breakdown pressures were decreasing and converged to the value defined by Eq. 4, with elapsed pumping cycles. This means that the borehole strenth T_θ in Eq. 1 can be estimated from Eq. 6 (Fig. 10 and 11).
4. It sedms reasonable to define the instantaneous shut-in pressure P'_s used in Eq. 5' as the one at which the pressure-time curve during the shut-in process becomes linear with a constant slope (Table 3).

View full abstract

In order to determine the fracture toughness of rocks at confining pressure, the splitting tests in a triaxial vessel are undertaken on four kinds of rocks, namely OGINO tuff, AKIYOSHI marble, KIMACHI sandstone and INADA granite.
The rock plates of 200mm×150mm×20mm which have a slot are prepared in this test. The slot produces a stress concentration around the tip of slot when the splitting force in the triaxial vessel is applied to the slot, and a crack occurs from the end of slot into the rock plate. The relationships among splitting load, crack opening displacement and crack length during the fracture process of rock plate are studied in this test, and the values of fracture toughness KIC of various rock specimens at confining pressure are determined with the compliance method.
The outline of this study is as follows;
(1) To measure a crack length of rock plate splitted in triaxial vessel, the silver conducting 7 grid lines are drawn on rock plate as shown in Fig. 3. The position of crack-tip propagating in rock plate is recorded on a pen-recorder when the silver conducting grid lines are broken by the crack.
(2) The splitting load-crack opening displacement curves of various rock specimens are obtained at atmospheric and confined pressure as shown in Fig. 4. From the figure, it is clear that the rising part of splitting load-crack opening displacement curves at atmospheric pressure is relatively linear, but as confining pressure increases, the rising part of these curves becomes non-linear and the splitting load increases.
(3) From the study of the effect of confining pressure on the fracture toughness, it becomes clear that the fracture toughness of rocks increases with increasing confining pressure. For instance, compared with the fracture toughness at confining pressure of 240kg/cm² and that at atmospheric pressure, an increasing rate of the fracture toughness of OGINO tuff is about 70%, AKIYOSHI marble about 50%, KIMACHI sandstone about 150% and INADA granite about 100%.

View full abstract

The purpose of this study is to investigate the mechanism of coal burst and the effective methods for destressing and strata control in order to conquest the coal bursts. In this paper, we study on the actual features of coal bursts in Miike mine and the geological characteristics in the locations.
The coal bursts have occurred many times along the longwall face of a flat coal seam, 1.8m thick. But every one of them is located in the limited area shown in Fig. 1. We can classify them by the magnitudes of damages likely shown in Table 1 and 2. Up to the present, the coal bursts have occurred anywhere in the face, but severe in the rise part of face. This may be caused by the concentrated stress in the intersection of the pressured zone in front of the face and the abutment of old working.
The important geological preconditions are the very thick sandstone in the roof, lying directly on the seam without faults, and the floor sandstone which is 2-3m thick and under which there is a locally developed coal seam, 0.4m thick, and a stiff sandstone, 6m thick, they are shown in Fig. 10-12. Statistically we conclude that the occurrence of coal bursts in this area closely correlates with the thickness of floor sandstone. Under 2m thick, the floor only swells along the levels and over 3m thick, the hazard of coal burst is removed. Other geological factors which may play a part in assessing the hazard of coal burst is the local fluctuations in coal seam thickness.

View full abstract

It is a very important problem in hydraulic transportation to establish the method of evaluating the pressure loss of non-Newtonian fluid flow containing coarse particles in pipes, since the non-Newtonian fluid is used as carrier fluid in recent years.
In order to find out the method, theoretical and experimental studies on the pressure loss of pseudo-plastic fluid flow containing coarse particles in a horizontal pipe were carried out.
The results of this study are summarized as follows;
A theoretical equation and an empirical one concerning the coefficient of additional pressure loss for pseudo-plastic fluid flow containing coarse particles in a horizontal pipe are obtained as Eq.(28) and Eq.(29) respectively.
The value of coefficient Ao in Eq.(29) is 2.0 in case of coarse particle whose lower limit for pseudo-plastic fluid flow in pipes is found about 2 mm in this research.
Comparing the experimental results with the theoretical equation, Eq.(28), the empirical equation of friction factor μs is obtaited as Eq.(31).

View full abstract

This paper describes an application of an infrared analysis method to quantitative determination of fatty acid salts and alkyl amine salts which are collectors used mainly in nonsulfide mineral flotation. Sodium oleate (NaOl) and sodium palmitate (NaPa) as a fatty acid salt, and dodecyl ammonium acetate (DAA) as an alkyl amine salt are used and for the measurement an infrared analyzer (nondispersion type) in the wave length range 3.4-3.5μm is used. The effect of pH on extraction of the reagents from aqueous solution into carbon tetrachloride phase is examined. Under a constant concentration, the indicated values in the fatty acid salts and alkyl amine salt are shown to be maximum and constant below pH 2.9 and above pH 10.6 respectively (Fig. 2, 5). Each calibration curve for NaOl, NaPa and DAA under such conditions of pH represents good straight line (Fig. 3, 4, 6).
The experimental results show that behavior of the extraction does not simply follow results of calculation based on the dissociation constant. In weakly alkaline range fatty acid salt is considerably extracted into carbon tetrachloride phase (Fig. 2), and the pH range is almost the same as that of acid soap formation. And also DAA is completely extracted at such lower pH as 10.6 (Fig. 5), it may indicate formation of amine ion-molecule complexes.
On the other hand, under higher concentration of NaCl even at pH 4, NaOl is extracted satisfactorily (Table 1).

View full abstract

As a first step in a series of equilibrium study on calcium ferrite slags, the composition of the Fe-O-CaO slags saturated with solid iron was determined as a function of the oxygen potential at 1200°C and 1300°C. The slags were equilibrated with CO-CO₂ mixtures in iron crucibles. From the data obtained, activities of FeO and CaO in the slags were calculated, which represent slightly negative deviation from Raoult's law.
The relation between log (p_co2/p_co) and T for the gas-slag-solid iron-wustite equilibria is represented by the equation:
log (p_co2/p_co) = (190/T)-0.63
and for the gas-slag-solid iron-calcium oxide equilibria:
log (p_co2/p_co) = (2920/T)-2.65

View full abstract

Distribution of nickel, cobalt, lead, antimony and arsenic among three liquid phases of copper, white metal and silicasaturated iron silicate slag was investigated. The melting experiments were carried out at 1300°C under varying oxygen partial pressure which was realized by controlled SO₂ pressure. In the lower oxygen pressure region, copper content in the matte was designated under flow of nitrogen gas. On the basis of the analytical results for the minor elements in the solidified samples, the distribution ratios for an element X, defined by equations 1 to 3, were derived, and are plotted against oxygen potential as illustrated in Figs. 1 to 3. As are thermodynamically expected by equations 8, 11and 12, considerable dependences on oxygen pressure are observed in the distribution ratios between copper and slag, and also matte and slag, but any appreciable dependence can not be recognized in the distribution ratio between copper and matte. Under reducing conditions, minor elements tend to be concentrated in the metal and matte phases, while are oxidized into the slag phase under higher oxygen potential. In the conventional smelting condition characterized by the coexistence of considerable SO₂ pressure, Co is highly concentrated in slag, Pb and Ni are distributed among all three melts in rather similar concentration, while As and Sb arehighly concentrated in copper metal.

View full abstract