Development of aggregate resources for use in structural concrete has been encouraged in Japan to support infrastructure improvement and national land conservation. Natural aggregate is a valuable resource necessary for sound economic development, and its importance is growing. However, against the backdrop of the ongoing depletion of resources, growing concern over nature conservation and increasingly tightened control over resource use, the supply of natural aggregates such as sea/river/pit sand and sea/river gravel has been decreasing. Under the circumstances, it is necessary to conduct simulations of aggregate resources development technology such as the microtremor survey, the slope stability, and improvement of afforestation from a long-term standpoint in an effort to optimize and enhance the efficiency of the entire production system in the light of the project scale, the quality specifications required by customers and the development processes. Furthermore, because contribution to development of a low carbon society will be required in the future, production plants and working faces need to be designed to enhance efficiency and CO2 reductions.
This study explored the crushing and physical separation technique as the pre-treatment of hydrometallurgical process for recovering valuable metals such as Co, Li, Ni and Cu from spent lithium-ion batteries (LIBs). Two types of LIBs, cylindrical one for personal computer and rectangular one for mobile phone, were roasted in the temperature range 673-873 K under a vacuum and were crushed by using single-axis cutter mill, hammer crusher, two-axis shear force crusher and high speed hammer mill. Then the crushed products were classified with screens and size distributions of the valuable metals were obtained. Selective crushing effects, that is, the degree of the difference in size distribution between several metallic elements, were evaluated in the fine and coarse particle size regions separately. Magnetic separation was carried out for the crushed product of the PC type LIB obtained under the most preferable conditions of the selective crushing. As the results, it was found that the combination of shear force crusher and high speed hammer mill was suitable for enhancing the selective crushing effect in both fine and coarse particle size regions, and this led to higher purity of the Co, Cu and Fe powders recovered after sieving and magnetic separation.
Tunnel boring machine is one of the accepted methods for infrastructural projects for tunnel ventilation or surge shaft in hydroelectric power projects. It is also a widely used technology in the installation of production and ventilation shafts and ore passes for mines. For large diameter inclined shaft boring, there are two solutions: Full-face blind shaft boring machine (FM) and Shaft reaming machine (RM) . In the latter case the excavated muck falls through the pilot hole to a lower level. The pilot hole of a small diameter can be also excavated with a raise-boring machine. Through the careful and comprehensive discussion, a RM was found to be appropriate for our target project (Omarugawa hydroelectric power project) . In the development process, very valuable data taken in former Kazunogawa hydroelectric power project were carefully examined and necessary modifications were done to a new machine for Omarugawa. Special care was taken in designing the cutterhead to optimize the shape for best cutting efficiency and muck removal performance. 1. Open type cutterhead for lightweight machine and easy access to machine parts and tunnel wall. 2. Cone-shape cutterhead for optimum disc cutter arrangement, good face stability and efficient muck removal. 3. Two vertical supports in pilot and reamed shafts for flexible direction control and excellent maneuverability. Finally, it should be noted that the developed machine had successfully completed the inclined shaft without significant troubles.
Atmospheric delays sometimes cause non-negligible errors in the measurement of ground surface displacements using GPS, especially when there is a large difference in height between a measurement point and the reference point of the GPS receiver. In the previous studies, the authors have suggested a correction method for such atmospheric delays, which uses a modified Hopfield model and on-site hourly-observed surface weather data at site. In order to evaluate the effectiveness of this correction method, long-term field measurements were conducted in the present study on a large slope in an open-pit limestone quarry. Nine GPS receivers were set on the slope as the measurement points with height differences of 106 ∼ 209 m to a fixed reference point, and their three-dimensional displacements were measured every hour. The measurement results from the two-year period revealed that the conventionally processed GPS displacements at all measurement points clearly showed yearly-periodic variations and short-wave irregularity in the vertical component, which were concluded to be due to atmospheric delays caused by the difference in height between the measurement points and the fixed reference point. On the other hand, applying our suggested atmospheric delay correction method, we confirmed that the correction could successfully remove the yearly-periodic variations and short-wave irregularity. These results prove that the GPS ground surface displacement measurement system is also applicable to sites where there is a large difference in height of over 100 m, if the atmospheric delays are corrected using the modified Hopfield model and on-site surface weather data.
This study is examined the fundamental property of the circular steel tubular columns which filled light-weight concrete using lapilli. The experiment is conducted under the pure axial compression, and it is carried out with two kinds of loading methods, only core is axially loaded and both core and tube axially are loaded. The use concrete is plain concrete, light-weight concrete II, light-weight concrete with lapilli within 50% and 100%. Steel fiber is mixed with some lapilli light-weight concrete for the purpose of improvement of strength and the toughness of the concrete. As a result, the steel fiber of the lapilli light-weight concrete is effective in suppressing the volume expansion of the lateral direction of the concrete. At the same time, axial compression stress increased, and it shows that the confined effect of the steel tube effectively is promoted. In the lapilli light-weight concrete which does not have enough strength, possibility of the practical use is testified by steel fiber mixture and the restriction effect of the steel tube.