The removal of sulfuric acid in the process solution of zinc leaching residue, which contains about 0.5 kmol/m³ sulfuric acid, 90kg/m³ Zn, 50kg/m³ Fe (II) and 50×10^-3kg/m³ Ga, was investigated by diffusiondialysis using anion-exchange membrane.
The following results were obtained.
1. Sulfuric acid in the process solution of zinc leaching residue is effectively separated from the cations of metals such as Zn, Fe, Ga.
2. The average overall dialysis coefficient for sulfuric acid was evaluated to be 4.5×10^-3 mol/(h-m²-molm^-3).
3. At the flow rates of the process solution of 1.0×10^-3m³ /h-m^-2 and water of 5.0×10^-3 m³ /hm^-2, the concentration of sulfuric acid in the process solution can be reduced to 12.5 mol/m³. In this condition, the water phase after dialysis contains 97.5 mol/m³ sulfuric acid and less than 1.0kg/m³ of Zn and Fe, and less than 0.5×10^-3kg/m³ of Ga.
4. Consequently, when the concentration of sulfuric acid in the dialyzed solution is lowered down to 12.5 mol/m³, at the flow rate of process solution of 1.0 m³ /h, the required membrane area of a diffusiondialysis cell and volumetric flow rate of the generated water were evaluated to be 1, 000 m² and 5.0 m³ /h, respectively.

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Some basic problems concerning on measurements of the hydraulic properties of rock by the transient pulse method have been discussed.
Firstly, a method to evaluate both permeability and specific storage coefficient, using the log [(p1-p2)/Δp]-tdiagram, is presented. Evaluation can be easilyconducted, although this method is rigorous because itis, induced based on the analytical solution.
Secondly, an experimental apparatus and measuring technique to conduct precise measurement have been examined by performing on two kinds of sandstone and one kind of mudstone.
Lastly, proposal has been made to give criteria for judgement whether the Darcy's law holds for the experimental conditions, utilizing the log [(pl-p2)/Δp]-t diagram, which is predicted partially based on the non-Darcy's flow analysis.

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A computer simulation for the continuous multistage countercurrent extraction process of gold from a thiourea leach solution was carried out by using the batch extraction and stripping data. The thiourea/hydrochloric acid/TBP system and the thiourea/sulphuric acid/TOA system were investigated for this simulation. Gold concentration in each extraction and stripping stage, and the final outlet concentration of gold and the recovery were estimated by the simulation under various conditions of stage number and phase ratio.
The simulation by expressing extraction and stripping isotherms as a mathematical function and taking the function in a computer program is considered to be a superior method to estimate the extraction and stripping behaviors in each stage in a steady state. It is recognized that 8 stage extraction with the phase ratio of 5-6 and 8 stage stripping with the phase ratio of 0.3-0.4 gives 90% recovery and 15 times concentration in the case of the thiourea/hydrochloric acid/TBP system. The thiourea/sulphuric acid/TOA system is inferior to the thiourea/hydrochloric acid/TBP system in the viewpoint of the overall recovery and concentration of Au.

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A series of experiments were carried out on production of fine palladium powder by reducing aqueous chloropalladous acid solution in a hydrogen gas bubbling batch reactor for a range of temperatures from 293 to 353K and hydrogen partial pressures from 0.5×10⁵ to 1.0×10⁵Pa. On the basis of the results, reaction mechanism and properties of the powder were analyzed.
Though the extent of reduction was found to considerably fluctuate with the aging duration, the fluctuation was suppressed by an aging treatment of the reactant solution under N₂ gas atmosphere at an optimum condition with a temperature of 353K and duration of 28.8ks. Apparent reaction rates thus obtained showed a 0th-order dependence on the palladium concentration in the initial stage of reduction, while showing a 1st-order dependence in the final stage. The rate increased in proportion to hydrogen patial pressure in the initial stage. Activation energies in these stages were as low as 25 kJ·mol^-1 and 16 kJ·mol^-1, respectively. Hence, the rate determining step of the reaction was presumed to be the diffusion step of dissolved hydrogen or palladium ion to the surface of palladium particles, especially that of dissolved hydrogen in the initial stage.
Particles produced were densely aggromerated and the agglomeration proceeded in proportion to the extent of reduction.

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Chemical cleaning is an effective method to remove the fine mineral matter and organic sulfur from coal which are difficult to separate with physical cleaning method. The alkali-acid leaching processes, such as aqueous caustic process and molten caustic process, are well known as the effective processes which enable to remove both of mineral matter and sulfur. But it has not been reported on the comparison of the both treatment results, in spite of the similarity of these processes.
In this paper, using Miike coal as a sample, the limit of demineralization and desulfurization and the optimum conditions of both processes are compared. In addition, the change of the coal substance during both processes is also investigated.
In the aqueous caustic process, the majority of mineral matter is removed with high recovery of coal substance and low calorific loss, but most of organic sulfur is remained unremoved. Molten caustic process reduces the ash and sulfur contents of the product to less then 0.1% for both, but with low recovery of coal substance and high calorific loss.
The relationships between ash or sulfur rejection and the other cleaning results (recovery of coal substance, calorific loss and the fuel ratio of clean coal) of both processes could be drawn as smooth continuous curves which might characterize the reactions between coal and alkali reagent in the processes. These curves are considered new measures indicating the facility of demineralization and desulfurization of coal.

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The base friction technique is one of the effective and quantitative experimental methods to predict the behavior of rock structures under gravity field. Many kinds of original base friction apparatuses have been developed and effectively used for studying stability of roof and settlement of ground surface due to shallow underground excavation.
This study describes a trial production of the newbase friction apparatus for underground utilization at a depth, though current base friction apparatuses have been limited for fitting within shallow depth. In the newly developed base friction apparatus, friction force on the plate and external forces by jacks and rubber bags in vertical and horizontal directions, respectively, are simultaneously applied to produce a high stress field. Air pressure working on the model surface can be increased up to 600 kPa. Urethane or teflon base can be selected as frictional plate according to the purpose of tests.
It is concluded, by some illustrative experiments, that this development of the new base friction apparatus enables quantitative research on stability of opening in the deep underground.

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The carbothermic reduction of iron ores, including hematite and mill scale, using coal char and limestone was studied under microwave radiation for the development of a novel technique to produce iron powders. Besides coal char, the usability of cokes and Hongei coal was also examined. The principal findings are as follows:
(1) Reduction rate of mill scale with coal char increases with an increase in the amount of coal char. The percent reduction after 10 minutes radiationof microwave increases linearly with an increase in coal char amount when the range of equivalent ratio of coal char to mill scale is less than 4. A further increase in coal char amount, however, was less significant to enhance the reduction.
(2) The percent reduction of mill scale-hematite mixture when the content of mill scale is below 40 wt% can be calculated from the additivity rule. In contrast, the percent reduction of the mixture containing more mill scale is alwayshigher than that expected.
(3) When the sized fraction of carbon staffs of-32+80 mesh was used for the carbothermic reduction of mill scale-hematite mixture, coal char was most efficient amount three carbon staffs examined, while cokes was most inefficient. However with the ground product of cokes of-325 mesh, the reduction of mill scale was greatly improved. Thus the mixed use of suitably ground cokes and coal char and the use of ground cokes in an open atmosphere are useful to proceed reduction quickly enough.
(4) Recycled use of carbon staff was found to be useful to promise a large reduction efficiency, providing a better recovery of iron powders. Judging from these findings, it is considered that the producing process of iron powder under microwave radiation must be economical and productive way when a suitable microwave oven is once designed

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Newly proposed failure criterion for rock is expressed by εT=εTC, whereεT is tensile strain and εTC is critical tensile strain. Some experimental results which support the criterion are shown.

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