The techniques of initial stress measurement were developed and improved in Japan. It is recommended to standardize some dominant methods in domestic market at first, and then encourage related organizations to promote them to international standard, in order to take an advantageous position of the methods in the international market. Currently, stress relief method and hydraulic fracturing method are considered to be valuable and practical methods. The compact conical-ended borehole overcoring method, one of the stress relief methods, was assigned as the standard of the Japanese Geotechnical Society in 2012. In addition, the new committee has been organized recently for standardizing the high stiffness testing method, an improved hydraulic fracturing technique. If international standard methods that are not the method used in Japan were assigned in future, we may be at a disadvantage for international bids. We may lose opportunities to apply our valuable technical resources such as engineers, instruments, established standards, and know-how in international market. And our techniques may become irrelevant in the international market. Our methods havebeen applied in many domestic foundation investigation fields such as construction of underground power plants, nuclear power plants, and large scale tunnels. It is in our best interest to have our techniques become the international standard as we expect an increase of requirement of those techniques in developing countries in future.
Platinum group metals(PGMs), such as rhodium(Rh) and ruthenium(Ru), are rare and unevenly distributed in the earth's crust. They are used in automobile catalytic converters and electronic equipment. The consumption of such rare resources is unsustainable; therefore, recycling technologies are needed. In this paper, the chemical properties and separation/recovery of Rh and Ru, and PGM smelting/refining technologies are reviewed. In PGM refining processes, Rh and Ru are converted into chloride complexes. To effectively separate each metal, operating conditions of the reaction have to be optimized. The valences of PGM chloro-complexes change with redox potential, and the distributions between chloro- and aquo- complexes vary with chloride ion concentration. The Ru and Os oxides are separated by distillation.
Understanding of interfacial interactions among supercritical CO2 (scCO2), water, and mineral phase is necessary for a precisely prediction of CO2 migration into aquifers. The purpose of this study is to assess the impact of scCO2 on flow property of Kimachi sandstone and Iidate granite in a CO2 rich dense phase i.e., the condition of which scCO2 is expected to displace formation water in the course of CO2 injection. In this experiment, the permeability test for CO2 gas was conducted before and after a CO2 saturation procedure that is filled with scCO2 in pores of rocks. To investigate a mechanical property of rock specimen in the presence of scCO2, the axial strain was also measured using a laser displacement sensor during scCO2 saturation processes. Our results showed that both Kimachi sandstone and Iidate granite samples tested have a more or less decreasing trend of gas permeability with increasing exposure time to scCO2. It was further shown that the axial strain of Kimachi sandstone and Iidate granite increased as scCO2-exposure time increased. Additionally, increases in masses and dimensions of test samples before and after scCO2 saturation processes were clearly observed under atmospheric pressure conditions. It can, therefore be said that Kimachi sandstone and Iidate granite could be capable of swelling and permeability change accompanied by CO2 sorption into their internal structures in the presence of scCO2. Furthermore, the observed significant reduction in permeability cannot fully be explained by two model predictions based on Kozeney-Carman equation and Hagen-Poiseuille law, considering CO2 sorption onto mineral phases. The present results pointed out that CO2 sorption on rocks under geological CO2 storage conditions could have a significantly impact on flow property of rocks during CO2 injection and storage processes.
Anodic dissolution of tungsten or tungsten carbide in a molten sodium hydroxide bath was investigated at 723K in order to simplify a tungsten dissolution step during tungsten recycling process from secondary resources like used cemented carbide (super hard material) tools. Cyclic voltammetry using tungsten and other metal wire electrodes suggested that tungsten is easily oxidized and dissolves into the melt, while nickel, iron and copper are hardly dissolved because of stable film formation on them as a result of oxidation. Cobalt was also oxidized, but the resultant oxide or hydroxide film seemed unstable. Anodic dissolution was carried out at constant voltage using throw-away tips and rotators of vibration motors. When the rotator was anodically oxidized at constant voltage of 1.0 V using a nickel plate as the cathode, tungsten was selectively dissolved at a high current efficiency of 97% and binder metals (nickel and copper) remained as residue. The amount of tungsten remained in the residue was less than 1% of initial value after the electrolysis for 9 hours. In the case of throw-away tips, both the tungsten carbide and binder metal of cobalt were anodically dissolved at constant voltage of 1.0 V, and whole the tips were dissolved by a long-term electrolysis of 20 hours. Although the dissolved tungsten remained in the melt, the greater part of dissolved cobalt deposited as metal powder on the cathode. The current efficiencies of tungsten carbide dissolution were calculated to be 86% and 96% in the cases of ceramic coated and uncoated tips, respectively. These results suggest that the proposed electrolysis is effective to dissolve tungsten from secondary resources, and indicate the possibility of selective recovery of both the tungsten and cobalt in the case of cemented carbide tools.