It is important to know the temperature distribution in the wellbore during drilling to develop and evaluate the bit and/or mud for high temperature geothermal wells. But, normally only the inlet and outlet temperatures of drilling fluid can be measured during drilling in the field.
Authours proposed a method which estimates temperature distribution in the wellbore from measured inlet and outlet temperatures of drilling fluid by computer simulation even when formation temperature distribution is not known exactly. In this paper, we described the method and estimated bottom-hole temperatures during drilling for four geothermal wells. Conclusions are as follows:

(1) When the fluid is circulated in the well at a certain flow rate and the inlet and outlet fluid temperatures coincide with the given inlet and outlet temperatures respectively, the temperature distributions in the wellbore are almost the same for different formation temperature distributions.
(2) The temperature distribution in the wellbore during drilling can be estimated from the measured inlet and outlet temperatures of drilling fluid even when undisturbed temperature distribution and thermal disturbance in the formation are not given exactly.
(3) The estimated bottom-hole temperatures of mud during drilling were about 140 to 200°C lower than the undisturbedf ormation temperatures.Differences between the bottom-hole temperature and the outlet temperature of mud were only 1 to 18°C.

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This paper describes an effect of water content on initial tangent modulus (elastic constant) of granitic rock sample in tension.Rock samples containing various levels of water content were prepared, where water-saturated or vacuum-dried samples are made through the procedures in accordance with ASTM recommendation (ASTM C97).A degree of water saturation, S_r, is determined for each sample by use of the equation.
S_r=W_i-W_d/W_s-W_d × 100 (%)
where W_s is a weight of a water-saturated sample, W_d weight of a completely dry sample and WZ is a weight under air-dry or vacuum-dry condition.
Based upon linear elastic fracture mechanics, elastic moduli could be precisely measured for these rock samples by means of compliance calibration technique.The experimental results obtained indicate a strong dependece of elastic modulus on degree of water saturation.Water contained in rock sample can be divided into three kinds of water, pore water, capillary water and adsorbed water (physisorption and chemisorption).The elastic modulus changes as a function of S_r-values.When S_r is below 35%, the elastic modulus increases abruptly.These increases in the elastic modulus are due to the reduction of capillary water in the rock sample.
It is also considered that significant effect of water content on the elastic modulus can be interpreted as the results of frictional force acting on a microcrack plane in rock samples.

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As widely known, an inadvertent break or make of a live circuit or poor connections in the circuit of any electric instrument may touch off a fire in underground coal mines unless both the voltage and the current in the circuit are small enough. A built-in battery, whenever it is implemented, may well be capable of igniting the inflammable gases when its terminals crash. JIS type 006P battery or an equivalent, however, is conceived to be satisfactorily a safe power source when it is engaged with micropower electric thermometer circuit systems with semiconductor temperature transducer. Due to the laminated construction of manganese elementary dry cells in this type of batteries, the internal resistance is fairly high, so it consequently suppresses the intensity of the short circuit current within a safe extent.This paper discusses the basic consideration of the power circuits of the new electric thermometers from the point of view of the gas inflammability.The compatibility of temperature transducers which assort with several versions of the thermometer circuitry is also described accompanying with a tabulation. Integrated, semiconductor, terr, ierature-transducing devices of the electric current output mode are regarded as competent for use in underground coal mines.Although both the thermal resistance and the thermal capacity of the transducer alone are very small, the effective time constant depends on the thermal properties of the protecting sheath, so that the time response of the transducer, in several media is almost the same to that of conventional alcohol thermometers.

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In order to find the limitations of safety operations in off-shore borings, the authors' previous theory on the lateral vibration of the boring rod in the sea has been checked by the model experiments and improved by the new method for evaluating the factor of damping due to the water surrounding the rod as well as by the application of the virtual mass of the water. Furthermore, the maximuiri bending_stresses of off-shore boring rods have been calculated by the above-improved theory, and the limitations of safety operations in off-shore borings have been presented by comparing those bending stresses with the fatigue strength of the rod-material.The main results obtained are as follows:
1) The previous theory provides the natural frequencies of the rods which are higher by about 16% than the actual frequencies. However, these discrepancies could be almost reduced by applying the two-dimensional virtual mass of the surrounding water to the theory.
2) Owing to improper evaluation of the damping factor of the surrounding water, the previous theory gives the bending stress almost twice as large as that of the practical rod at the resonance of its lateral vibration in case of the deep sea. However, the theory combined with the new method for obtaining the equivalent viscous damping factor from the drag coefficient, which is already known, is very useful for estimating the bending stress of an off-shore boring rod.
3) Within the limits where the buckling of the rod does not occur, the range of safety operation of an off-shore boring is wider in case of deeper depth of the sea and narrower in case of greater tensile load axially applied at the top of the rod. Besides, it can be said that the current rule of thumb is very insufficient for telling the limitation of safety operation in an off-shore boring.

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The reddish brown flint clay alias Akabannendo which mainly consists of kaolinite exists enormously in Iwaizumi-cho, Iwate Prefecture.In spite of its high alumina content, the utilization of the clay has not been achieved because of its high iron content.In this paper, the acid treatment has been investigated for the purpose of iron removal from the clay.The clay specimen was crushed into different size fractions, and treated with 0.1-10N hydrochloric acid, sulfuric acid and nitric acid under the temperature condition between 20°C and boiling point.The results are summarized as follows.
(1) The specimen almost consists of fine grains of kaolinite under 1μ size and its iron content is 5.63wt% as ΣFe₂O₃. Some iron minerals, such as hematite, siderite and magnetite were ascertained in the specimen and the amount of hematite consist of fine particle was much larger than that of the other iron minerals.
(2) The extent of iron leaching is mainly affected by the sort of acid solution, acid concentration and treating temperature. Under the same treating condition, the amount of iron leached by each acid solution decreases in the order of hydrochloric acid, sulfuric acid and nitric acid, but alumina is leached in the reverse order.
(3) The iron content of the specimen decreased to 0.56wt% by hydrochloric acid treatment and the yield of purified product obtained was about 90% in weight.But about 10% portion of iron constituent in the specimen could not be removed by the acid treatment.
(4) According to the autoclaving tests, it is considered that the decomposition of kaolinite structure by the acid treatment arises at the lower crystalline part and gradually goes on to the higher one with proceeding the reaction.
(5) The most suitable acid for the iron removal from “Akabannendo” is concluded to be hydrochloric one for the reasons of its difficulty to destroy the structure of kaolinite and its high iron extractability.In this case, the treatment was effectively carried out under the condition in which the acid concentration and temperature of the solution were 6N and 60°C, respective.

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The extraction and stripping of Mo (VI) and W (VI) with a tertiary amine, Alamine 336 were chiefly studied and these characteristics of pH, diluent, extraction temperature, rate of extraction, maximum loading capacity and stripping were clarified. At the extraction of Mo.the third phase was formed below pH 2.8 with the kerosene diluent but the extraction rate of about 99% was obtained.When the dihlent of Alamine 336 was C₆H₆ and CCl₄.the extraction rate of Mo was about 75% at pH 2.4. The extraction rate of W was 97% at pH2.3 with the kerosene diluent and at below these pH the third phase was formed.When the diluent of Alamine 336 was C₆H₆ and CCl₄, the extraction rate of W was about 70 and 60% at pH2.3, respectively, and the formation of third phase was observed at below this pH.As the results of investigating these data, the kerosene was chosen as the diluent on the extraction of Mo and W.
The species that take part in the reaction were mainly MoO^2-₄, Mo₇O^6-₂₄, Mo₈O^4-₂₆, WO^2-₄, H₂W₆O^3-₂₁ and H₂W₁₂O^10-₄₂.In order to prevent the formation of third phase, it was necessary to add 0.3ml of decanol in 15mlα of the organic phase on Mo extraction and 1mα of decanol in 15ml of the organic phase on W extraction.Stripping of Mo and W from A lamine 336 were about 80 to 85% at pH greater than 10 with 0.1M (NH₄) ₂SO₄ solution and about 85 to 98% at pH greater than 9.5 with 0.1M (NH₄) ₂CO₃ solution, respectively.
Recovery of Mo and W from the solution which was not coexisted of those two species were possible by the selection of optimum pH and stripping reagent.

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Disposable oxygen probes based on the following galvanic cell were applied toa copper flash smelting furnace:
M, M_xO_y/ZrO₂+CaO or MgO/O in Gas, Slag or Matte, where M, M_xO_y means Fe, FeO or Cr, Cr₂O₃. All types of oxygen probes used in this study were applicable to the slag andmatte phases, but not to the gas phase due to the adhesion of the dust to the zirconia surface and the occurrence of the temperature difference at the outer and inner surfaces of zirconia.
Measured oxygen potentials were normalized to 1200°C with respect to the reaction:
4 FeO (1) +O₂(g) =4 FeO_1.5(1).
Normalized oxygen potential was independent of the depth from the slag surface in the matte phase near the slag-matte interface as well as in the slag phase. Furthermore normalized oxygen potentials in theslag and matte phases were almost constant along the plant from the flash furnace to the electric one. These results imply that the metallurgical reactions among copper concentrates, oxygen gas and flux would be completed in the reaction shaft or in thesettler just under the reaction shaft.

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