The separation and purification methods of precious metals from the scrap containing precious metals are introduced in this review. The solid waste containing precious metals first is dissolved by the solution comprising oxidation agents and ligands, such as aqua regia, Cl₂ + HCl and NaCN + O₂. The separation of precious metals in the leached solution or wasted solution is carried out by using various methods like classic precipitation, cementation, ion exchange resin, activated carbon adsorption and solvent extraction. It depends on the concentration and combination of precious metals what kind of separation method is applied. Generally, adsorption and ion exchange methods are applicable to the dilute solution, while precipitation, cementation and solvent extraction are used for the concentrated solution. In the recovery of the precious metals in automobile catalyst, the collection of the platinum group metals in Cu or Fe metal melted by a plasma melting method is performed as one of the recovery techniques by the pyro-metallurgy.
The fundamental of separation and purification methods, and some commercial plant examples are described for recycling of precious metals.

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Numerous studies have been made to control the climate conditions in underground mines, but most of them are concentrated on a single roadway with through airflow, and those on the simulation of heat problems in developing roadway with local ventilation are very few. Therefore it is necessary to establish a proper method to simulate the thermal environmental conditions within the working face with auxiliary ventilation for controlling the thermal climate there effectively.
As a basic study on control of the thermal environment in working face with auxiliary ventilation, the CFD method is employed to simulate the transfer of heat and moisture between rock surface and the airflow at a heading face with forcing auxiliary ventilation. Based on the simulation results, the distribution of local heat-transfer coefficient and its relationship with airflow rate, variation of heat transfer flux from the strata to the ventilation air with time and wetness fraction, the distribution of rock temperature and its variation with time elapse are discussed in the paper.
The study provides an important basis for establishing a proper method to predict the thermal environment conditions on locally ventilated working places.

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Although forced auxiliary ventilation is widely employed at heading faces, it is not easy to design an optimum ventilation system for a working face because of the complexity of airflows. Therefore, it is essential to obtain airflow patterns at the face where a heavy machine works.
From this point of view the influence of a machine such as a road header upon airflow patterns are investigated by both methods of measuring of airflow velocity in reduced scale model and using Computational Fluid Dynamics (CFD).
As a result, some important information is obtained concerning the influence of a machine upon airflow patterns in the face. A vortex is generated in the space between a face and a machine, and the wake was created behind a machine. The authors pointed out a possibility that these flows may lead the stagnation of both dust and gases.
The results also show that the CFD is an effective tool for simulating the airflow under varied conditions of the ventilation system.

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Uniaxial compression, uniaxial tension and indirect tension (Brazilian) tests were carried out for coal (anthracite) obtained in a coal mine located about 26 km west of Beijing.
Complete stress-strain curves not only in uniaxial compression test but also in uniaxial tension test were successfully obtained. In post-failure region of uniaxial tension test, the curve showed Class I characteristics accompanied with small amount of residual strength. The peak strength obtained by the uniaxial tension test was far less than the indirect tensile test frequently conducted.
The strain rate was alternatively increased and decreased to obtain the loading-rate dependency. When strain rate was increased, stress increased abruptly by a certain amount depending on the loading-rate dependency of the rock. The experimental results showed that loading-rate dependency of the coal both under the uniaxial compression and tension stress was relatively smaller than the most rocks that had been tested by the authors.

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A bleeding examination and a flow characteristic examination of grout materials were performed to understand the fundamental characteristic of grout materials. Moreover, an injection experiment of grout materials which used a decomposed granite was conducted to understand the applicability of the analysis technique which introduced filtration theory. The results are as follows:
1) When cement water ratio is large, a bleeding speed becomes slow, but the bleeding ratio becomes small.
2) Plastic viscosity and yield stress become large with increase of cement water ratio. Particularly, plastic viscosity change greatly on C / W = 1 / 1.6. And as compared with yield stress, it is larger about influence on the discharge.
3) Where a cement water ratio does not exceed C / W = 1 / 5, the clogging of the voids was done by a suspension custody. And where C / W = 1 / 3.5, that was done by a surface filter layer.
4) The plastic viscosity measured using Brookfield viscometer is a result when some cement particles aggregate, and shows big value as compared with the theoretical relative viscosity.
5) The result of injection analysis using the theoretical relative viscosity assumed that the cement particle is distributing completely is well as an experiment result in agreement. In the grout materials which flow the inside of the voids, it cleared that plastic viscosity follows the theoretical relative viscosity which the cement particles distributed.

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Two long-term creep tests of Tage tuff were carried out as long as three years. In the tests, specimens were submerged under the water, and creep stress was applied and maintained at 30 % of the peak strength.
The first one was started in 1994. The result indicated that creep strain rate was monotonically decreasing with elapsed time approximately proportional to (elapsed time)^-0.9. Through the testing period, creep strain was increasing approximately following (elapsed time)^0.1 and did not reach the creep limit to which creep strain leveled off. The second one was started in 1997 and the result was similar to the first one except that creep strain was slightly smaller than the first.
A constitutive equation of variable compliance type was modified especially focusing on the long-term creep at low stress level. Experimental results of not only this study but also previous studies were carefully examined. It was found that the creep strain and strain rate calculated by the modified equation reasonably well coincided with the experimental results.

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Dilute polymer solutions produce considerable drag reduction in turbulent pipe flows. The mechanisms of drag reduction have been widely studied by many researchers. Despite these many their efforts, it is still difficult to define the mechanisms. In order to understand the turbulent structures of dilute polymer solution flow and surfactant solution flow, we measured 2 components of velocity by 2D-LDV, estimated mean velocity and turbulent intensity, and calculated Reynolds shear stress from the velocity fluctuation data. Reynolds shear stress was analyzed by classifying the data into four quadrants. The characteristics of coherent structure (amplitude for each event, amplitude ratio, probability for each event) are discussed and compared with drag reducing flow and solvent (water) flow. It was found that the contributions to Reynolds shear stress from ejection(event of quadrant 2 ) and sweep(event of quadrant 4 ) are smaller near the wall in drag reducing flow than in solvent flow. We also found that the contributions to Reynolds shear stress from outward interaction(event of quadrant 1 ) and wallward interaction(event of quadrant 3 ) are important to reduce the drag. Contributions from each event in high drag reducing flow such as surfactant flow are equal, thus the flow has no coherent structure and it is a randomly mixing flow. Moreover, the relationships between eddy extension and Reynolds shear stress in drag reducing flows are discussed under the consideration that the drag reducing solutions are viscoelastic fluids. It is predicted that the eddy extension of drag reducing flow would be suppressed by the elasticity of the surfactant. The results obtained from this research are useful for the construction of a constitutive equation.

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The Tower mill KD-3 is an improved version of laboratory tower mills VD-1, KD-1 and KD-2 in which a specific classifying column has been introduced to facilitate the recovery of fine particles with the ascending airflow generated by the blower as soon as they are ground. Unfortunately, because of the fast circling airflow in the center of the classifying column, it was difficult to have control over the maximum size of particles collected in the cyclone. The present study aimed at leveling the circling airflow by installing a vertical plate, a horizontal plate or net inside the classifying column to correct this deficiency. It was found that installing a horizontal plate or a net inside the column reduced the maximum size and weight of products collected in the cyclone. Furthermore, the maximum size of cyclone products could be consistent, regardless of the duct airflow rate. Through this process, coarse particles blown from the comminution zone collide with the plate or the net and settle down to the bottom of the classifying column.

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Aqueous oxidation of phosphorous acid by dissolved oxygen proceeds very slowly, but when sulfur dioxide is coexistent with oxygen gas, cooperative oxidation processes for both sulfurous acid and phosphorous acid proceed quickly in aqueous solution. Though sulfur dioxide itself is a popular reducing agent, it affects like the oxidizing agent as if. This somewhat strange phenomenon is investigated mainly from a stoichiometrical point of view. An aqueous solution of 0.1 ∼ 1 mol / dm³ H₃PO₃ is oxidized by oxygen gas containing 0 ∼ 5 volume% SO₂ under the condition of pH4.5 and 80 °C. Addition of 1 volume% SO₂ increases the oxidation rate as high as 10 times than without SO₂, but the oxidation rate of phosphorous acid does not pass over that of SO₂ itself. Hydrogen peroxide generated during the oxidation of SO₂ by oxygen is attributed to the oxidation of phosphorous acid.

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In the previous report, it was explained that O₂-SO₂ mixed gas oxidized the phosphorous acid to phosphoric acid. In this report, effects of reaction conditions, such as agitation speed, partial pressure of oxygen, pH, and temperature, on the aqueous oxidation of H₃PO₃ by O₂-SO₂ mixed gas are investigated. The results were summarized as follows.
Agitation speed hardly changes over 1,000min-1 on the oxidation rate of H₃PO₃. The oxidation rate of H₃PO₃ is proportional to the partial pressure of oxygen. The oxidation rate of H₃PO₃ increases with the increase of pH. With the rise in solution temperature, the oxidation rate of H₃PO₃ increases, however, the temperature dependency is low. In all conditions of reaction, the quantity of H₃PO₃ oxidized did not exceed the quantity of SO₂ oxidized. Within the range of these experimental conditions, the oxidation rate of SO₂ was not affected.

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