In Japan, about 5 million end-of-life vehicles are generated every year, of which about 1 million are exported as used cars, while the remaining 4 million are dismantled and scraped in Japan. In Japan, end-of-life cars are scraped and dismantled in the same way as in the U.S. and Europe, but the recycling rate of the resultant used parts is low compared to these countries in the west.
Currently there are no established legal frameworks for the recycling of used vehicles in Japan. End-of-life vehicles are disposed along the individual action plans of the related economic operator in accordance to the End-of-Life Vehicle Recycling Initiative schemed by the Ministry of International Trade and Industry in 1997.
Recently, with increasing opinions voiced on the restrictions of the Recycling Initiative, the Ministry of International Trade and Industry has announced their plans to come up with a draft of end-of-life vehicle recycling system at the beginning of 2001.
Regarding the recycling of vehicles abroad, the current end-of-life vehicle recycling situation of German, the Netherlands, and Sweden who already have laws for the recycling of end-of-life vehicles is introduced along with an outline of the EU directive which is about to be enforced shortly.
Except for the Netherlands which adopts the method of appropriating fees collected from new car users to the disposal of end-of-life vehicles, it seems that recycling systems in the other countries are not functioning smoothly because the enforcement of laws and systems had not started with the free-of-charge collection system of used vehicles, and owing to the high export rate of end-of-life vehicles.

抄録全体を表示

Our objects are 1) providing a method for forecasting the future copper price, 2)forecasting the future copper price applying our method and 3)evaluating the expansion plans of copper supply in developing countries, especially in Chile (from 2000 to 2002).
Our method for forecasting copper price is as follows. First of all, the supply and demand functions in copper market are estimated by 2SLS (two stage least squares). The independent variables of supply function are copper price, the present mine production and the previous mine production. Those of demand function are copper price and the world GDP.
Secondly, we calculate the critical prices for closure for the existing copper mines and then we can estimate the maximum copper supply (the copper supply frontier) for various copper prices. Thirdly, we forecast the future copper price using the estimated supply and demand functions and the copper supply frontier.
The expansion plans of copper supply in developing countries (2000~2002) have a considerable effect on the forecasted future copper price. It can be thought that those countries, especially Chile have the expansion plans strategically. That is, some of the existing mines will have to be closed in 2000 and 2001 because of low prices derived by the expansion plans in developing countries. As a result, the developing countries can increase largely their profits in the relatively high price period (2002) followed by the low price period (2000~2001).

抄録全体を表示

A specific fixed depth chipping experiment is conducted to investigate the mechanism of chipping upon water jet drilling in rocks. It is shown that the net impinging time: t for a fixed depth chipping is closely associated with the bottom incident pressure: p evaluated by the Third Power Method, and that the fixed depth chipping occurs in the case that the bottom incident pressure: p is greater than a thresholding pressure: p _th. The relation of p - t determined by the experiment is explained, basing on the fracture mechanics, and it is discussed that the chipping upon drilling is a kind of the fatigue fracture and initiates at a circumference of the advancing bottom. In order to forecast the incidence of the chipping upon water jet drilling, a chipping potential is subsequently proposed as a function of p and p_th. It is clarified that the chipping potential P_C in the case of p = p_th = S_e, where S_e: the erosion strength of materials, is available for forecasting the incidence of chipping upon drilling.

抄録全体を表示

Comminution plays a major role in many processes where raw materials are converted into intermediate or final products. The efficiency of comminution is very low, and research and development to save the comminution energy have been performed. Then, it is necessary to estimate correctly the comminution energy. Work Index proposed by Bond is an important factor in designing comminution processes and has been widely used. Work Index is measured by a ball mill grinding and the measurement procedure is closely defined in JIS (Japanese Industrial Standard) but the optimum grinding condition is varied with samples. Then, it would be possible to overestimate the comminution energy to get products.
In this paper, the above was studied by grinding conditions for the measurement of a Corresponding Work Index which was proportional to the Work Index. The feed size, the mass of feed and the mass of ball were investigated as the grinding conditions when the rotational speed of mill and the ball diameter were constant. The samples used were silica glass, quartz, feldspar, limestone and gypsum. The result indicated that the comminution energy based on the Bond's theory might be larger than the energy required to get fine particles.

抄録全体を表示

Biochemical activities of Thiobacillus ferrooxidans in the presence of activated carbon were studied under the shaking and stationary conditions using the 9K medium at pH 1.5. In the shaking condition, the biochemical activities of the bacterium were lower in the presence of activated carbon than in the absence. On the contrary, the activities were higher under the stationary condition. In the shaking condition, the bacteria were adsorbed onto the activated carbon according to the Langmuir isotherm. The adsorbed cells became inactive with regard to their ferrous ion-oxidizing and growth. Under the stationary condition, the oxidation rate of ferrous ion was higher in the presence of activated carbon than in the absence, because the cells gathered to the gas-liquid interface in the presence of activated carbon.

抄録全体を表示

The separation performance of zigzag air classifier with angle of 90 degrees was studied using narrow size fractions of thin square samples and granular samples. The simulation results of air velocity inside the classifier indicated that the zigzag geometry induces a flow pattern consisting of an upward flow and a circulation flow. Experimental results showed that float product recovery was described as an integral calculus of normal distribution as a function of dimensionless air velocity (V_A/V_A50), where V_A is superficial air velocity and V_A50 is the V_A at the fifty percent recovery. The V_A values were predicted using the equations derived theoretically from dynamics for a particle dropping in air and derived experimentally. Newtons efficiencies of coal-quartz mixture and coal-pyrite mixture were estimated based on the recovery calculated using the above relations and coincided with the experimental results.

抄録全体を表示

Lithium-ion secondary battery scrap, which contains LiCoO₂, graphite and PVDF (poly vinyliden fluorine), was subjected to dry grinding using a planetary mill with and without quartz powder as a grinding aid, following its room temperature leaching using 1N HCl solution. The scrap material becomes amorphous state as grinding time and the quartz additive ratio increase. Accordingly, Co and Li in the scrap can be easily extracted from the ground product, and the former yield reaches about 90 mass% at 4-hour grinding with 50 wt% additive. Only about 2 mass% of F in PVDF in the scrap can be extracted under the same grinding condition.

抄録全体を表示

In the present work the adsorption of selenium six valence electrons from Na₂SeO₄ solution was investigated. The lead compound 1,000 mg·dm^-3 showed the ability to adsorb Se⁶⁺ ion from the Se⁶⁺ ion solution.
Under the experimental conditions of Se⁶⁺ ion concentration = 30 mg·dm^-3 and pH = 3~9, the Se⁶⁺ ion adsorbed amount was about 0.025 kg·kg^-1.
When the experimental conditions were: pH = 7 and 100 mg·dm^-3 Se ⁶⁺ ion concentration in the solution, maximum adsorbed Se⁶⁺ ion amount was 0.041 kg·kg^-1. Using x-ray photoelectron spectroscopy, the changes of the adsorbed Se⁶⁺ ion to Se⁴⁺ and Se⁰ were observed as Molybdomerite was formed.
On the other hand, the absorption of Pb cations from the lead solution was investigated. When 2000 mg·dm^-3 fly ash was mixed with 40 mg·dm^-3 lead solution, the concentration of the lead solution was under 0.1 mg·dm^-3 after 1 hour.
The adsorption of Se-cations from the selenium wastewater was observed. When 0.02 kg·dm^-3 lead compound was mixed with 70 mg·dm ^-3 selenium wastewater, the concentration of the selenium wastewater was under 0.1 mg·dm^-3 after 30 minutes.
The removal of selenium ion from actual wastewater is possible.

抄録全体を表示

Extraction of Pd(II) and Pt(IV) with dihexyl sulfide (DHS) from chloride solutions, and the degradation of DHS to dihexyl sulfoxide (DHSO) were investigated in this study.
When Pt(IV) exists in aqueous solution to be extracted, the extraction of small amounts of Pt(IV) causes the oxidation of DHS to DHSO as well as the reduction of Pt(IV) to Pt(II). The presence of DHSO in organic phase results in the formation of insoluble substances with metals ions such as Sn(IV), Fe(III), Si(VI), Zn(II) and Pt(IV) at the interface between the organic and aqueous phases. The appearance of the insoluble substances is due to the low solubility both in aqueous and organic phases. The insoluble substance is decreased by the addition of the modifier like alcohols.
In the extraction of metal ions, the repeated operation of extraction and stripping of metal ions with DHS increases the amount of DHSO. The extraction of Pt(IV) is increased, when the contact time is extended and when the concentration of Pd(II) is lower in the extraction operation of Pd(II) and Pt(IV) by DHS. It is considered that the oxidation of DHS takes place by the following reaction.
H₂PtCl₆ + 3DHS_org + H₂O →PtCl ₂·(DHS)_{2, org} + DHSO_org + 4HCl

抄録全体を表示

The conditions for the selective oxidation of copper and iron sulfide minerals contained in a low-grade molybdenite concentrate during autoclave leaching in acidic media have been studied. The effect of oxygen partial pressure, reaction time and temperature on copper removal has been examined. Oxidation of minerals follows the order; chalcopyrite, pyrite, molybdenite and has been explained from the point of view of electrochemical kinetics. Cementation on iron was used for copper recovery from the leach liquor. The partly oxidized residue consisting of molybdenite and iron (hydro-) oxide can be treated by means of flotation or oxygen pressure leaching in alkaline media to extract molybdenum and rhenium values.

抄録全体を表示

The effect of anionic species (SO₄ ^2-, Cl^-, NO₃^-) in synthesizing fine particles of phosphor (Y₂O₃ : Eu) from the homogeneous solution which dissolved Y₂O₃ and Eu₂O₃ by the addition of H₂SO₄, HCl or HNO₃ by liquid-phase method which used the urea for the precipitant generator was studied. The shape of synthetic fine particles is different by the anionic species in the solution, and in the system including SO₄^2-, the shape of the fine particles was irregular, and in the system including Cl^- or NO₃^-, it was spherical and monodispersed. Monodispersed spherical fine particles synthesized from the solution including Cl^- or NO₃^- was guessed with the amorphous basic carbonate. On the other hand, the fine particle synthesized from the solution including SO₄^2- showed crystal structure, and it was the different composition which contained the SO₄^2- as a component. The fine particles synthesized from the solution including Cl^- or NO₃ ^- were inverted to the monophase of metal oxide by calcination at the temperature ove r about 600^°C, and it confirmed that it was not almost influenced to spherical form and monodispersion. And, these calcined fine particles showed fluorescence spectra with luminescence peak in 611nm which was peculiar to the Y₂O₃ : Eu phosphor. On the other hand, in case of the synthesis from the solution including SO₄ ^2-, SO₄^2- contained in the fine particle remained after calcination, and the crystallinity after calcination was comparatively low. And, these calcined fine particles showed different fluorescence spectra with the Y₂O ₃ : Eu phosphor.

抄録全体を表示