Agglomeration in liquid is a promising method for mineral and material processing, fuel beneficiation and waste treatment. In this process, fine particles suspended in a liquid are agglomerated by addition of a second immiscible liquid (bridging liquid) which preferentially wets the particles under appropriate agitation conditions. The authors reviewed recent progress in fundamental studies of agglomeration and its application; especially, the main factors affecting the agglomeration, on-line monitoring systems and topics in industrial fields were described.

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For the precise measurement of rock stress tensor by means of the conical-ended borehole technique, a minute numerical simulation of stress reliving process based on the elasticity has been presented and discussed. The change of bottom strains during the compact overcoring operation has been analyzed by the boundary element method, and the numerical procedure for the simulation of stress reliving process has been presented as well as successful case examples. Showing a good agreement of the numerical results with monitored strains, it has been discussed that the continuous strain measurement system proposed in the previous paper has an accuracy high enough for the practical use.
The anomalous data rejection based on the process simulation has been discussed for the minimization of error in rock stress determination. From the examination of case examples having some points of difference between the numerical results and the monitored strains, which suggests non-elastic behavior associated with micro-cracking, it has been concluded that the minute simulation of stress reliving process and subsequent rejection procedure are indispensable for the improvement of the accuracy of rock stress determination.
Finally the partial stress relieving and the three dimensional rock stress determination by it have been examined and it has been shown that the diameter of the borehole gives the standard advance of the compact overcoring after passing through the strain measurement section necessary for the precise rock stress determination, though the shortest distance required is much smaller than it.

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Flue dust produced from Kosaka copper flash smelting furnace contains metals such as Cu, Pb, Zn, Fe, As, Cd etc. To recover these metals, the dust is treated in the hydrometallurgical plant. Previous iron oxidation by air blowing at pH5 and 50°C to remove iron from the leached solution has been changed by becterial iron oxidation and precipitaion process. Fundamental experiments carried out prior to the change showed that solution from copper removal process depressed ability of iron oxidizing bacteria. The solution contained heavy metal ions and halogen ions (F, Cl, Br) originated from the waste water of sulfuric acid producing plant. The effects of these ions on bacteria iron oxidation were tested. The main inhibitor in this solution was found to be fluoride ions. Resistant bacteria for fluoride were not found, but their adaptation to fluoride was effective to oxidize iron in solution containing fluoride.

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Separation of heavier rare earths, Tb, Dy and Ho was investigated by a batch and column method. Solvent impregnated resin can be made by soaking macro porous resin in organo-phosphorous extractant, whose trade name is PC-88 A, diluted in chloroform and removing chloroform from the mixture.
It has been revealed from the measurements of pore size distribution and specific surface area of the solvent impregnated resin that extractant is physically adsorbed or holded in macro porous resin. In a batch method the adsorption behavior of Tb, Dy and Ho with the solvent impregnated resin is quite similar to the extraction behavior with solvent extraction. The adsorption behavior for Tb, Dy and Ho, namely the relation of log D vs. pH is very close one another, which suggests the difficulty in the separation of Tb, Dy and Ho by the solvent impregnated resin. In a column method, it is possible to separate and recover lighter rare earth in the adsorption process, and heavier rare earth in the elution process. For instance, in a binary system of Tb and Ho, terbium can be recovered in the yield of 30-70% at 100% purity in the adsorption process, while holumium is collected in the yield of 45-50% at 100% purity in the elution process. From the measurement of the adsorption distribution of Tb and Ho in the column for the binary system, it has been proved that heavier rare earth is substitutionally adsorbed in the column to release lighter rare earth.

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The relations between equilibrium oxygen pressures and compositions of melts in cupellation process were investigated in laboratory tests as well as in a commercial furnace. The oxygen pressure change of lead bullion during cupellation process was successfully measured by using oxygen sensors based on stabilized zirconia with a reference electrode of Fe/FeO.
The following results were obtained.
(1) The measured oxygen pressure changes of the melts during cupellation agreed approximately with those estimated by equilibrium calculations.
(2) The oxygen pressure increased continuously with the progress of cupellation reaction, and drastically changed to the high level when the reaction approached to the completion.
(3) The changes of compositions and oxygen pressures of metals showed a good correspondence.
(4) Oxygen pressure measurements can be used for process control such as a judgment of the completion of the reaction.

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The ASR (Anelastic Strain Recovery) method for measuring three-dimensional in-situ stresses, which had been developed by one of the authors, was successfully applied at Yunomori geothermal field, Japan for seven cores collected from the depths of up to about 1, 500m of two wells. The rocks were tuffs, a shale and an andesite. Temperatures of the cores were from 100 to 210°Cbefore drilling. From the data of anelastic normal strains measured with strain gauges in six independent directions, both principal stress directions and the ratios of principal stress deviations were determined without knowing the anelastic strain recovery characteristics of the rocks. The results were consistent with the orientation of the maximum principal stress estimated from borehole breakouts observed in the wells and also consistent with the direction of the maximum horizontal compression observed by surface survey. Furthermore, for one of the cores, magnitudes of principal stresses were determined by calibrating the anelastic strain recovery compliances of both shear and volumetric modes in the laboratory under the conditions of drained triaxial compression. The results were compared with those obtained by DSCA and the combined AE and DRA methods carried out by NEDO. The results of the ASR method were consistent with those of DSCA.

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As a fundamental study of new zinc smelting processes in which liquid copper is used to recover zinc in a liquid Cu-Zn alloy, activity measurements in the liquid Cu-Zn-Pb, Cu-Zn Ag and Cu-Zn-Au ternary alloys were conducted at 1, 075 K using an isothermal isopiestic method.
Activity of zinc in the Cu-Zn-Pb system forming a wide miscibility gap in the liquid phase represented a very large negative deviation from a Raoultian behavior. The isoactivity lines showed a good agreement with the tie-lines of the miscibility gap. On the other hand, the activities of zinc in the Cu-Zn-Ag and Cu-Zn-Au systems forming electron compounds in the solid phase represented negative deviations from the Raoultin behavior. The deviation in the Cu-Zn-Au system was much larger than that in the Cu-Zn-Ag system, owing to the large difference in the electronegativity factor between the systems.
A Redlich-Kister polynomial formula with the first order for expressing the excess molar free energy of mixing as a function of the alloy compositions was applied to the ternary systems, and the constants in the formula were determined by a regression analysis of the obtained data. The vapor pressure over the ternary melts was estimated at 1, 423 K, using the derived constants.

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In order to prevent silica scaling, the removal of silicic acid from the Kakkonda geothermal water has been investigated by adding mineral particles such as quartz, feldspar and dickite as seed crystals. After being held at 80°C for 2 hours, the geothermal water was cooled in the water bath maintained at 40°C. Then a seed crystal was added in it and the concentrations of monosilicic acid and total silicic acid were measured periodically. The effects of particle size, amount of seed crystal addition, repeated uses of seed crystals on the removal of silicic acid were examined.
Results obtained are summarized as follows;
(1) Quartz and feldspar did not enhanced the removal of monosilicic acid.
(2) The finer the particle size of dickite was, the more effectively monosilicic acid and polysilicic acid were removed. The concentrations of monosilicic acid and polysilicic acid decreased, for example, from 335mg/l to 285mg/l and from 140mg/l to 0mg/l respectably in ten minutes with the addition of-37μm size fraction of dickite. When dickite was repeatedly used, the removal rate of monosilicic acid decreased, but that of polysilicic acid did not.

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Solubilities of magnesium sulphate in sulphuric acid solutions and hydrolysis of acidic ferric sulphate solutions of various concentrations with the addition of magnesium sulphate have been investigated in an autoclave at temperatures of 185°C and 200°C.
The results obtained were as follows:
1. Solubilities of magnesium sulphate increased with an increase in sulphuric acid concentrations in solutions, while at the same sulphuric acid concentration, solubilities of magnesium sulphate at 185°C were slightly higher than that at 200°C.
2. Solubilities of magnesium sulphate in sulphuric acid solutions at temperatures of 185°C and 200°C were represented by the following emnirical formulas:
Mg²⁺ (g/l)=4.981+3.044×10^-1 [H₂SO₄ (g/l)]-4.651×0^-1 [H₂SO⁴ (g/l)] ²at a tenlperature of 185°C
MgSUP>²⁺ (g/l)=2.962+2.947×10-^-1 [H₂SO₄ (g/l)]-3.889×10^-4 [HH₂SO⁴ (g/l)] ² at a temperature of 200°C
3. When the hydrolysis of ferric sulphate soulutions was at equilibrium, the concentration of ferric ion increased with an increase in that of sulphuric acid in solutions, while at the same sulphuric acid concentration, the concentration of ferric ion decreased considerably with an increase in the addition of magnesium sulphate.
4. In the hydrolysis of acidic ferric sulphate solutions, ferric oxide, Fe₂0₃, was precipitated at lower sulphuric acid concentrations, and ferric basic sulphate, Fe (OH) SO₄, was precipitated at higher concentrations of sulphuric acid, while hydrolysis and precipitation of ferric oxide increased withthe addition of magnesium sulphate in the ferric sulphate solutions.
5. At a temperature of 185°C in the absence of magnesium sulphate, hydrolysis and precipitation of ferric oxide occurred up to the sulphuric acid concentration of 55.8g/l or below, and at 55.8g/l or above, ferric basic sulphate was precipitated. When respectively about 15g/l Mg²⁺ion and 30g/l Mg²⁺ion as magnesium sulphate were added in the ferric sulphate solutions, hydrolysis and precipitation of ferric oxide occurred up to the sulphuric acid concentration of 76.5g/l and 100.5g/l.
6. At a temperature of 200°C in the absence of magnesium sulphate, hydrolysis and precipitation of ferric oxide occurred up to the sulphuric acid concentration of 69.3g/l or below, and at 69.3g/l or above, ferric basic sulphate was precipitated. When respectively about 15g/l Mg²⁺ion and 30g/lMg²⁺ion as magnesium sulphate were added, hydrolysis and precipitation of ferric oxide occurred up to the sulphuric acid concentration of 82.1g/l and 105.1g/l.
7. When magnesium sulphate was added in solutions, empirical formulas of the ferric ion concentration and the sulphuric acid concentration over the stable region of ferric oxide were as follows. at a temperature of 185°C
log [Fe³⁺ (g/l)] =5.30 log [H₂SO₄ (g/l)]-9.61 about 15g/l Mg²⁺ion as magnesium sulphate log [Fe³⁺ (g/l)] =5.46 log [H₂SO₄ (g/l)] -10.24 about 30g/l Mg²⁺ion as magnesium sulphate at a temperature of 200°C
log [Fe³⁺ (g/l)] =5.09 log [H₂SO₄ (g/l)] -9.46 about 15g/l Mg²⁺ion as rnagnesium sulphate log [Fe³⁺ (g/l)] =5.74 log [H₂SO₄ (g/l)] -11.02 about 30g/l Mg²⁺ion as magnesium sulphate

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This paper describes fundamental studies on numerical prediction system related to air temperature and humidity of underground airways and shafts that are in dry and wet conditions.
The mathematical model including angle of inclined airways, heat and mass transfer at rock surface of airway and phase change of water vapor to fog is presented. The quasi three dimensional finite difference model was used for numerical calculations of rock temperature. The wetness was used to express the degree of wet condition of the rock surface.
The prediction calculations about the variations of air flow temperature and humidity along the dry and wet airways have been carried out. The air flow temperature of inlet side is affected by the wet condition and inclined angle of airway. The air temperature in the exhaust shaft has tendency to be kept a constant temperature by the latent heat released by the phase change of water vapor. The amount of fog in airflow of the exhaust shaft is presented.
Finally, the practical equations (33) and (37) to predict air temperature of the dry airways and shafts are presented on the basis of results by the finite difference calculations.

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An airflow distribution in an ventilation network is changed when an airway resistance in the network is changed by an airflow regulator damaging or an airway collapsing. The occurrence of an abnormal airway will be found by analysing the airflow changes created in the network, if airflows are monitored in several airways. This paper describes the newly developed methods to locate an abnormal airway and estimate the changed value of resistance by means of analysis of the measured airflow data.
In the first method the ventilation network is analyzed, measured airflow data being introduced, and the pressure distribution thereby obtained are examined, which enables us to detect the place creating an abnormal airflow resistance and to evaluate the change.
The second method utilises a data base of airflow distributions which are calculated in advance for various combination of network resistances.
In the case of the occurence of an abnormal airway, it is generally impossible to get the accurate airflow distribution by an ordinary method for ventilation analysis method, because the value of the changed resistance there is unknown. However, it is proved that the correct airflow distribution can be obtained, if measured airflow data are introduced in the ventilation network analysis method proposed in this paper.

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To investigate the mechanical behavior of coal specimens with the pore gas pressure, the following laboratory experiments on coal collected from Ashibestu and Akabira Coal Mine were conducted; the triaxial compression tests and those with the pore gas pressure by useing the triaxial testing machine under the condition of the strain rate of 1.3×10^-4/sec and confining pressure and pore gas pressure extending up to 40MPa, the gas permeability tests under the hydrostatic pressure by means of the transient pulse method.
The experiments showed that coal strength increased and brittle behavior became predominant with the increase of the effective confining pressure. The law of effective stress for the fracture criterion was valid for coal specimens whose pore were fully saturated with gas pressure.
As the experimental results, the coal specimens were more permeable under the low hydrostatic pressure than under the high hydrostatic pressure, and these phenomena and deformation were largely concerned with the collapse processes of cracks in a coal specimen under the hydrostatic pressure.

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