Palladium will be most increased demand in rare metals because the use of electrical and electronic fields in the future. Therefore, it is nesessary to construct the stable supply of resource in our country. Currently, the separation and recovery of palladium from urban mines have trying to carry out the solvent extraction method using the dihexylsulfide (DHS) extractant as the mainstream. However, DHS have some problems which the extraction process is lengthening because DHS's extraction rapid is so slowly. In this study, it was focused that triphenylphosphine (TPP) as an alternative DHS extractant. TPP shows the extraction rapid is about 5-6 times higher than DHS extractant. Therefore, we have been investgating to establish the Palladium separation and recovery process using TPP extractant. In our previous work, it was found that the multistep extraction is possible to separate Pd(II), Au(III)and Ni(II) from the coated electronic parts waste which use Cu as base material using TPP extractant. In this work, we investigated that the separation and extraction behavior of Pd(II), Au(III), Ni(II) and Cu(II) using TPP extractant. Furthermore, we considered that the separation and recovery process from the coated electronic parts waste by the extraction method with TPP extractant.
Pyrometallurgical extraction of a concentrated phase of Ni and Co from high-grade copper matte that is obtained by copper matte smelting of low-grade secondary materials was studied. The process consists of melting of the high-grade copper matte mixed with the metallic copper at 1,623K and subsequently occurred liquid-liquid phase separation. The two liquid phase region in Cu-β-S pseudo-ternary system (β=Fe+Pb+Ni+Co) appears similar composition range to that in Cu-X-S ternary system（X ＝Fe，Pb，Ni，Co) previously reported. The supernatant phase termed as the matte, of which sulfur content is comparatively high, and settled phase termed as metal, of which sulfur content is comparatively low, are formed when the composition of the melt is in the immiscible region of two liquid phases. The nickel and cobalt concentrations in the settled metallic phase are significantly higher than those in the supernatant matte phase. Because the concentrations of constituent elements in both the metallic and matte phases are strongly correlated each other, conjugated composition of the melt in the immiscible region can be obtained from the simulation. The simulation showed that repeated phase separations with addition of metallic copper or elemental sulfur result in the concentrated phase of Ni and Co with small iron concentration. The obtained concentrated phase of Ni and Co is expected to be an economical resource of Ni and Co, because the phase is applicable to the refining process that is already commercially operated.
CCS has been expected as a countermeasure against global warming in recent years. When the injected CO2 reacts to rock minerals, it may form secondary minerals such as calcite, which is called mineral trapping of CO2. It is of significant importance to examine how the mineral trapping exerts an influence on the physical properties in the targeted reservoir rocks because the trapped minerals may change the strength, deformability, and permeability of the reservoir rocks, although such works are quite sparse in literature. In this study, the influence of the mineral trapping on the evolution of physical properties has been evaluated by replicating precipitation of calcium carbonate that may occur in the mineral trapping. The results of mechanical and permeability experiments show that the change of the mechanical and hydraulic properties is significant even if the amount of calcite precipitation is relatively small.
The development and advancement of new technologies have been considered for carbon fixation and its effective utilization as being indispensable for the achievement of greenhouse gas emissions reduction targets without adversely impacting economic growth in the world. Among such technologies, the one considered to present the greatest potential in terms of both of feasibility and CO2 reduction, as well as offering a relatively low cost burden, is CO2 capture, usage and geological storage (CCUS). The costs of CO2 recovery present a barrier to carry the CCS and CCUS project. Large-scale project models for carbon sequestration, recovery and underground storage that involve the construction of long-distance pipelines have been either implemented or planned in North America and Australia, etc., but such projects are not well matched to the land conditions of Japan. The development of Japanese-style CO2 sequestration, recovery and underground storage technologies is required that ensures linkage in a compact and high economical way among local area-based CO2 recovery, storage or fixation processes and also energy supply. In this article, the concept“ Low-Carbon Smart Cities” have been proposed with some technical challenges that can be solved by research developments with including environmental monitoring. This concept is targeted for areas with relatively high population density and where land use constraints are in place. By applying the resulting model to the situation in Southeast Asian countries, which have similar land conditions and also possess coal resources, the aim is to combine and integrate the local environment with the provision of carbon-free energy and realize CO2 reduction with greater economic efficiency.
The long-term promise of geological sequestration of CO2 is dependent on capillary sealing and slow flow mechanisms for low-permeable rocks such as caprocks. The purpose of this study is to investigate threshold pressure of Namihana (NMH) Fm. and Ohara (OHR) Fm. mudstones depending on effective confining stress at 40℃ and effective pressures up to 20 MPa. The mudstone specimens tested were taken from Kazusa group of Boso peninsula in Japan. Two support experiments of water permeability and porosity measurements were performed before the threshold pressure test to assess mechanical behaviors of OHR and NMH mudstones. After the threshold pressure experiment, porosities of OHR and NMH mudstone specimens were measured using Mercury Intrusion Porosimetry (MIP) method. Our results demonstrated that OHR mudstone exhibited a steep decreasing trend in water permeability with increasing effective pressure at around 5 MPa, while water permeability of NMH mudstone decreases monotonously as effective pressure increases. It has been reported by previous studies that the observed significant reduction in water permeability for OHR mudstone could be attributed to the presence of crack-like voids in rocks. Thus, it was suggested that there were a rich crack-like voids in OHR mudstone compared to NMH mudstone. The critical pressure inferred from the obtained compression curves for OHR and NMH mudstones, corresponding to transient from elastic to elasto-plasticity deformations was around 5 MPa and 7 MPa, respectively. These values were fairly consistent with the MIP data. All the data for threshold pressure as a function of effective pressure exhibited a linear correlation with water permeability except for OHR mudstone in lower effective pressure range. It can, therefore, be concluded that the presence of such crack-like voids in mudstones has a significant effect on threshold pressure and will require an additional model to be capable of having the relationships between threshold pressure and water permeability.
In geologic CO2 sequestration, the pH of formation water may be decreased due to CO2 dissolution, which may cause the change of porosity and permeability of reservoir rock. The pH changes of formation water are widely varied depending on CO2 pressure and the content of substances having pH buffering action, therefore, it is important to determine the wide range of pH change of various types of formation water under the various CO2 pressure conditions. We considered a determination method of pH change of various types of formation water under the various CO2 pressure conditions based on the spectrophotometry using a windowed high-pressure cell and a mixed pH indicator consisting of 4 single pH indicators. The well-defined absorption peaks were found at the wavelength of 614 nm or 444 nm when the pH of the solution was 5.6 or <5.6 respectively, therefore, two different calibration curves were derived from the absorbance of standard pH buffer solutions at each wavelength. The validity of this method was confirmed by an experimental result that the pH change of deionized water under 0.1 MPa CO2 pressure had been determined accurately by this method. We carried out experiments on this method using the real formation water samples which contained bicarbonate ion having pH buffering action with different concentration under various CO2 pressure. The results of the experiments demonstrated that this method is capable of determining the pH change of various types of formation water under various CO2 pressure conditions.
Among in-situ microbes within depleted oil-gas reservoir, the species dominant in CO2 rich environment produce methane much faster than those dominant in CO2 poor environment. CO2 acts as a catalyst in the reaction. If we maintain preferable conditions for methanogenic microbes during geological CCS, we will be able to abate greenhouse gas emission and produce natural gas as one of natural energy resources at the same time. We named the technological concept as‘ Microbial Associated Geological CCS (Bio-CCS)'. In Bio-CCS, CO2 will be injected from a well for two purposes: to abate greenhouse gas emission and to cultivate methanogenic geomicrobes. CH4 gas will be produced later using other wells. The procedure is similar to the Enhanced Oil/Gas Recovery (EOR/EGR) operation, but in Bio-CCS, the target is production of methane gas out of residual oil in depleted oil/gas reservoir CO2 abatement. To evaluate the basic feasibility of the new conceptual technology, we conducted preliminary risk assessment of Bio-CCS conceptual process. First of all, based on result of numerical calculations using geological model of Bio-CCS process, we assumed a procedure of Bio-CCS site: 1 million CO2 will be injected into depleted oil reservoir in 10 years; the reservoir will be kept still for 90 years and 0.5 million t CH4 will be produced; after 100 years from the first CO2 injection, CH4 production will be started. We developed hazard scenarios by way of literature survey and statistical analysis of accident statistics. Then we applied the hazard scenarios to the assumed Bio-CCS procedure. As the result, the preliminary risk assessment assures that the Bio-CCS process will be safe. Even it happens any leaking accidents, most impacts on peripheral area of Bio-CCS site will be negligible.
We often have unusual weather in these days and it might be due to an increase in the CO2 concentration in the atmosphere and the global warming. The recent IPCC report (AR5) concluded that it is extremely likely that human influence has been the dominant cause of the warming. The report also presented a new analytical model of the temperature increase based on several scenario of the measure against the CO2 increase. The simulation showed that the greenhouse gas emission will be zero and the predicted temperature will rise but remain within 0.3 ℃by the end of this century if we will perform adequately the measure. However, if not, the temperature increase will be expected to be 2.6 to 4.8 ℃ centring around 3.7 ℃. The establishment of the CCS technology, therefore, is important for the early measures. The number of participants and the titles of the papers in the GHGT show a kind of indicator of the current and necessary technologies. The number of participants had been increased since the first meeting but decreased in 2014, implying that it might be in response to the global economic decline. It is also reported that the capture and storage technologies are major but are shifting from the post-combustion capture technology to other technologies such as the oxy-fuel and the pre-combustion capture technologies. The CCS technology, which is combined of various technologies, has been developed on the basis of the development of the oil and the natural gas, especially, for the storage and monitoring know-how and technique which are used in the petroleum industry. The demonstration sites in US are selected in the EOR fields and the standardization of EOR in ISO is discussed while the CCS economy becomes more and more important.