12CaO･7Al2O3 electride is one of the outstanding materials expected to be applied in various fields such as electronics and catalyst, and generally fabricated by sintering high purity CaCO3 and Al2O3. We attempted to fabricate 12CaO･7Al2O3 electride using limestone as a raw material instead of using high purity CaCO3 aiming at further industrial use, and investigated the gas adsorption properties of the fabricated samples. Three samples, two from limestone and one from high purity CaCO3, were prepared and exposed to the atmosphere for about 9 hours, and then the gas adsorption properties of them were analyzed by Py-GC/MS. As a result, desorption of N2 and O2 which are abundant in the atmosphere was not observed by heating the samples exposed to the atmosphere up to 700℃, while desorption of CO and CH4 was identified. It is implied that the desorbed CO originates from CO2 in the atmosphere. This result indicates these samples might selectively adsorb CO2 and CH4 as compared with N2 and O2. Furthermore, for the limestone derived samples, the selectivity of CO2 and CH4 adsorption was improved and this result indicated the possibility that the CO2 adsorption capacity of these samples is higher than that made from high purity CaCO3. One reason of this phenomena is inferred the changes in the electronic state of material surfaces due to the doping of impurities contained in limestones, such as Mg, Sr, and Cu, into the Ca sites of the cage-like structure in 12CaO･7Al2O3 electride.
Rock blasting is one of the most common techniques for rock breakage in the open-pit mining excavation. On the other hand, the application of the technique has been restricted by law since it may cause a serious impact on surrounding environment, such as flyrock, ground vibration and noise. According to the statistics, more than 70% of accidents relating to the usage of explosives is flyrock. This accident may cause serious damage to buildings, human beings, and objects in the surrounding area. However, a detailed guideline for prevention of flyrock has not been developed yet. From these points of views, a series of field experiments was conducted and initial velocity and flying direction of fragmented rock were discussed by considering blasting standard and rock mass conditions such as strength, fractures/cracks and joints. The result shows that powder factor and burden have strong influence on the initial velocity of fragmented rock. Not only blasting designs but also rock mass conditions, cracks/joints strongly effect on the initial velocity. In addition, it was also made clear that the existence of fractures/cracks/joints in the blasting face have an obvious impact on the direction of fragmented rock.