The Compañia Minera Santa Luisa S.A. has been successfully operating mines in Peru for a number of years. Operation of the Huanzalá mine in the Huallanca township area began in 1968, the Pallca mine in the Pocpa and Llamac villages area in 2006, and the Atalaya prospect in the village of Chiuruco, Ancash department in 2006. The company is owned 70% by the Mitsui Mining & Smelting Co.,Ltd. and 30% by the Mitsui & Co., Ltd.
Since the commencement of operations, the Compañia Minera Santa Luisa S.A. has made contributions to the social well being of local communities, provided assistance in constructing infrastructure, and undertaken measures for environmental mitigation. These activities are consistent with contemporary corporate social responsibilities for all mining companies.
Social contributions are based on agreements made with local communities. Among other contributions the company provides electric power to the Huallanca township at no charge from company’s hydroelectric plant, contributes towards school and medical supplies, provides medical examinations for local residents, and assists with stock-raising and selective live stock breeding programs. In addition to donating vehicles, the company has conducted a number of infrastructure projects including the construction of roads, water and sewage systems, school buildings, a gymnasium, a public hall, and an irrigation canal. One of the largest projects was the relocation of the entire Pocpa village from a landslide slope to a flat area in 2011.
Environmental control programs include neutralizing acid drainage from mine portals, recycling mine water, and conducting stability studies for tailings dams in accordance with the “Program of adaptation and management of environment” as promulgated by Peruvian law in 1997. The Huanzalá neutralization plant installed in 1998 has the distinction of being the first in Peru.
Discussions with local communities and agreements reached on the company’s corporate social responsibilities have resulted in a peaceful relationship with local residents. It can be stated that socially responsible corporate activities have helped to develop confidence and a positive relationship between the company and local communities to maintain stable mining operations.

抄録全体を表示

Due to the Naturally Occurring Radioactive Materials (NORM) existing in the earth’s crust, the entire natural ore always contains some amount of radioactivity. In particular, rare-earth ore tends to contain relatively high amount of radioactive materials due to the geochemical property of rare-earth element. The main components of radioactivity in rare-earth ore are Uranium, Thorium and their descendant nuclides in the radioactive decay series. Therefore, the refinement and other processing of these ores, especially Monazite, Bastnasite and Zircon, could bring concentrated portions of U, Th or other radioactive materials, which might conflict to the laws and regulations on the handling of radioactive materials, depending on the collected amount and the concentration.
In this article, the analysis method for the radioactivity in the ore based on γ-ray spectrometry and α spectrometry are introduced with the results for several rare-earth ores. Then, the concerning regulation laws and guideline on the nuclear source material, nuclear fuel material and radioisotopes are explained by focusing on the treatment of natural radioactive materials. Finally, the basics of chemical separation techniques of radioactive materials from rare-earth elements, i.e., conventional precipitation method, solvent extraction method and advanced chelate impregnated absorbent method are explained with the help of chemical equilibrium calculations and reported experimental data.

抄録全体を表示

For therapeutic use of hard tissue biomaterials, a number of biomaterials have been investigated eagerly. Especially titanium and sintered hydroxyapatite have been used from the viewpoint of biocompatibility. Last century sintered ceramics such as calcium phosphates were main hard tissue biomaterials from the view point of mechanical strength. However, they are fundamentally less biodegradable and not easy to process. Recently, tissue engineering has been developed. Various kinds of scaffold biomaterials have often been used in medical and dental fields. The concept of biomaterials has appeared to shift to biodegradable scaffold biomaterials.
On the other hand, inorganic materials of human hard tissues such as bone and teeth are composed with hydroxyapatite. Tooth enamel is well-crystallized, contrary to poorly-crystallized dentine and bone. Physicochemical properties of apatites are affected dramatically by the substitution of trace elements. Especially, biological apatites constituting bone and teeth contain several wt% of CO₃^2- ions, which are related to the crystallinity and solubility. Recently, scaffold biomaterials are expected with a shape-maintaining property in addition to large pores and high porosity, in which cells can easily invade. To develop a new biodegradable scaffold biomaterial, bone-like carbonate apatites (CO₃Ap) were synthesized and CO₃Ap-collagen scaffolds were created. This scaffold biomaterial is useful itself for the region with bone regeneration ability. When these sponge-frame complexes with rh-BMP2 were implanted beneath the periosteum cranii of rats, sufficient new bone was created after 4 wks’implantation. Furthermore, when the CO₃Ap-collagen sponge containing SVVYGLR peptide was implanted as a graft into a tissue defect created in rat tibia, the migration of numerous vascular endothelial cells as well as prominent angiogenesis inside the graft could be detected after 1 week. Thus, the modification of higher function such as cytokine and angiogenesis factors is effective for low regeneration region as tissue engineering biomaterials.

抄録全体を表示

Groundwater samples in Horonobe district, Hokkaido, were analyzed to evaluate the possibility that formic and acetic acids are active substrates for methanogens in Quaternary and Neogene (Koetoi formation) formations. ΔG_r corresponding to CH₄-producing reactions indicates that both acids could be active substrates in almost all sampling locations. However, acetic acid was recognized to be an active substrate only in the Koetoi formation on the basis of the principle of competitive exclusion (CE) of microorganisms. The limited possibility by the CE principle suggests that dynamic equilibrium between substrate production rates and consumption rates is established only in the Koetoi formation for acetic acid.

抄録全体を表示

There are many paper mills in the eastern area of Ehime Prefecture where the pulp and paper industry has been well developed. Paper sludge containing large amounts of water is generated during paper manufacturing processes. The paper sludge is incinerated to reduce its volume, and then the paper sludge ash is produced. The greater part of the paper sludge ash has been disposed to landfills and an effective utilization of the paper sludge ash has not been promoted. Due to environmental policy and regulations in Japan, it will become difficult to obtain supplies of river sand and sea-bed sand which have been used for concrete aggregate. On the other hand, demands for the effective utilization of industrial wastes for construction materials that are typically made of natural resources will rise in future. From this background, the authors propose an effective utilization of granulated paper sludge ash produced from the paper mills as concrete aggregate.
In this study, the applicability of granulated materials made of the paper sludge ash to concrete aggregate is evaluated by carrying out the following experiments. Firstly, the physical and chemical properties of the paper sludge ash are evaluated and a mixture proportion of the granulated paper sludge ash is examined through its strength measured by point load tests. Secondly, Particle size distribution, density, water absorption rate, and solid content of the granulated paper sludge ash are evaluated from the view point of concrete aggregate. Finally, durability, mechanical and physical properties of concretes mixed with the granulated paper sludge ash used as proxy of sand aggregate are also evaluated. From results of the above experiments, it is found that the concrete using the granulated paper sludge ash is lighter, and its water absorption is much higher than those of ordinary concretes. The strength can satisfy the requisite for design standards of reinforced concretes. The drying shrinkage strain is larger and the air tightness is lower than those of ordinary concretes.

抄録全体を表示

The time-dependence of molecular weight of gelatin in Zn electrowinning was investigated by gel permeation chromatography to make clear the effect of various factors on the degradation of gelatin. The molecular weight of gelatin decreased significantly with increasing the time even in the case without electrolysis. Although gelatin acted as a polarizer for Zn deposition, shifting the cathode potential to less noble direction, the polarization effect gradually decreased with time. The decrease in polarization effect of gelatin with time was apparently caused by the decrease in molecular weight due to the degradation. The degradation of gelatin was accelerated with electrolysis, and the degradation was faster at anode than at cathode. However, the difference in degradation rate between anode and cathode was small, showing that the degradation of gelatin was accelerated even at cathode. The observed degradation constant k’ of gelatin for hydrolysis reaction in solution without electrolysis was linearly increased with concentration of sulfuric acid. The degradation constant k’ of gelatin increased significantly with solution temperature, but no k’ depended on the existence of Zn²⁺, and Cu²⁺, ions in solution. The linear relationship was observed between lin k’ and 1/T , showing the formation of Arrhenius’ equation. The activation energy for hydrolysis of gelatin in electrowinning solution containing 1.5 mol/dm³ of H₂SO₄ calculated by the inclination of Arrhenius plot was to be 60.1 kJ·mol^-1, and the following equation was derived. k’ =7.4×10³ exp(-60.1×10³/RT) min^-1

抄録全体を表示

Electrodeposition of Cu was conducted in a synthetic electrorefining solution to investigate the effect of gelatin, thiourea and chloride ions on the polarization curve for Cu deposition, morphology, texture, surface roughness and the throwing power of the deposited Cu. In a solution containing both gelatin and chloride ions, the cathode potential for Cu deposition was significantly polarized at current densities above 200A/m², while the thiourea depolarized the potential for Cu deposition at 200 to 1000A/m². In a solution containing the three additives, i.e. gelatin, thiourea and chloride ions, the potential for Cu deposition was polarized at 500A/m². It is supposed that the synergistic effect of gelatin and chloride ions on the polarization prevailed over the depolarization effect of thiourea. In the Cu deposited at initial stage, the chloride ions promoted the field-oriented texture with the orientation of <110> direction. However, Cu deposited at initial stage from the solution containing gelatin, thiourea and chloride ions was composed of both the inclined texture type and the epitaxial growth type of crystals. The surface roughness and throwing power of the deposited Cu was most improved in the solution containing gelatin, thiourea and chloride ions, showing the synergistic effect of three additives. The thiourea had an effect on decreasing the surface roughness of the deposited Cu, and chloride ions improved the throwing power of Cu.

抄録全体を表示