One of the benefits of geophysical exploration is that extensive and continuous surveys are possible at low cost principally though elastic wave velocity and electrical resistivity. Therefore, the techniques that can derive quantitative information on the geological environment from geophysical data are essential for engineering applications. Various studies have been conducted to estimate hydraulic conductivity by combining several well logging data sets using rock physical models for sedimentary and crystalline rocks. In this study, the author calculated the hydraulic conductivity using the models for a soft sedimentary rock site and a granite site. As a result, the calculated values closely match the field and laboratory permeable tests using the rock samples. Next, the author have applied a quantitative analysis for porosity, clay content, and salinity profiles using a combined interpretation of multiple surface geophysical surveys data by using the extended bimodal mixture model. The S-wave velocity and resistivity data have been obtained at a soft sedimentary rock site, composed of the muddy or tuffaceous sandstone and mudstone. The results correlate with the salinities of pore water extracted from borehole core samples. It is expected that these techniques will be effective methods to investigate the shape of the interface of the fresh groundwater and salt water at coastal soft sedimentary rock sites.
Construction and calculation using surface precipitation model were attempted for As(V) coprecipitaiton treatment with ferrihydride. Surface precipitation model was defined as extended surface complexation model. Original surface complexation model with parameter values reported by Dzombak and Morel was validated to adsorption experimental results for As(V) removal using ferrihydrite. The surface complexation model could represent experimental As(V) removal and isotherm quantitatively. In surface precipitation model, precipitation was described by the formation of solid compound between ferric hydroxide and ferric arsenate. Activity of these precipitates was determined by surface precipitation ratio of FeAsO4(s) obtained experimentally from XANES analyses. Solubility products of surface precipitation of FeAsO4(s) (KspAsO4(suf. ) were determined by fitting to sorption densities and surface precipitation ratio in each condition. The values of KspAsO4(suf.) were determined 10−7.7 at pH5 and 10−10.2 at pH7, respectively. These values were reasonably relative to the literatures and previous studies. Based on the obtained KspAsO4(suf.) value, As(V) removal and isotherm were calculated for As(V) coprecipitation treatment using surface precipitation model. Good agreement between experimental and calculated values was observed. For both of observed and calculated data, the sorption isotherms in coprecipitation treatment indicated saturated shapes because the species of surface precipitation was FeAsO4(s) and surface precipitation rate largely increased when As/Fe molar ratio is relatively low. These results were suggested that the quantitative prediction of As(V) coprecipitation treatment was possible if KspAsO4(suf.) value was estimated experimentally.
In order to develop the“ Bio-filter”, silicon nitride porous bodies with micro-macro complex pore structure were fabricated using the tape casting process. It was confirmed that the permeability of the macro pore (about 100 microns) was good enough for the waste water with high concentration of organic compounds, while that of the micro pore (about 1 micron) showed much less permeability even for distilled water. The bio-compatibility of betasilicon nitride porous body was first investigated in this study. Small specimens of the silicon nitride porous bodies with or without the surface treatment of amino-silane coupling agents were immersed in the cell culture liquid containing the two kinds of microbes, Saccharomyces cerevisiae and Lactobacillus casei. After several days, their surfaces and fracture surfaces were observed using a scanning electron microscope, and the numbers of microbes fixed on the surfaces were counted. It was found that all specimens fixed certain amounts of both microbes, and no difference in the average number of fixed microbes per unit area was confirmed between specimens with or without the silane surface treatments, which suggests that the surface of beta-silicon nitride crystal possess good biocompatibility. The large average numbers of fixed microbes per unit area was confirmed only when the bio-films existed on the surfaces, suggesting the possible formation of the microbe consortium.
In this review, we summarized the physical factors such as viscosity, surface and interfacial tensions of slag and copper matte affecting the separation between them in copper smelting furnaces. The situation of slag/matte separation and practical measures for keeping the good separability were also introduced. Research results about the matte suspension mechanism in slag by the influences of viscosities, surface tensions and interfacial tensions of slag and matte, and also harmful influences on the slag/matte separation by the magnetite precipitation and the practical measures to reduce magnetite in smelting furnaces were outlined.
Copper slag from copper matte smelting contains iron, which forms fayalite (Fe2SiO4) as the major constituent. Because of its favorable physico-mechanical properties, copper slag has uses such as concrete aggregates, ballast, and abrasives. However, the demand for copper slag for such applications is decreasing in advanced countries such as Japan. In recent years, the depletion of high-grade iron ores and increasing demands for iron resources have resulted in an interest in the development of methods for iron recovery from low-grade metallurgical wastes. This paper gives a review of various processes such as pyrometallurgy, hydrometallurgy, and beneficiation for iron recovery and slag cleaning. Authors also proposed a new process for iron recovery from copper slag, and related simple thermodynamic calculations are provided.
Metallurgical slags are inevitably produced during the present smelting and refining processes as by-products. A lot of ironmaking and steelmaking slags are produced as a by-product of steel production because of the huge amount of its production, and thus the development of effective utilization methods has been the crucial issue in steelmaking industry. Ironmaking and steelmaking slags have been mainly used as a resource for various civil engineering works as a substitute material of natural stone or sand due to its physical and chemical properties so far. However, the growth of the potential demand of ironmaking and steelmaking slags cannot be expected in the future because of the maturation of domestic economic activities and the competition with by-products from various other industries. Therefore, further technical advancement must be conducted from the viewpoints of the decrease of slag generation by improving smelting and refining processes and utilizing the refining ability of slags more efficiently, and the development of new utilization methods. In the present paper, the current situation of ironmaking and steelmaking slags is reviewed and the recent progress of the researches related to slag is described, namely the improvement of the processes by utilizing heterogeneous slag such as solid-liquid or two liquid phases, so called “multi phase flux” as a refining agent, and the development of the utilization of steelmaking slag at coastal area as a rehabilitation material of sea desertification problem. Furthermore, effective methods of slag utilization are summarized and discussed.
Elution property of arsenic and lead from copper slag was investigated. The results obtained are follows. 1. Elution concentration of arsenic from copper slag decreased with increasing silica content in the slag, even though, it increased with increasing lime content in the slag. Elution of arsenic from the slag may be attributed to the network structure of silica. 2. Heat treatment of the slag at 500〜700℃ in the air atmosphere decreased elution concentration of arsenic. Although, elution concentration of arsenic increased extremely by heat treatment over 900℃. 3. Melting treatment of the slag with additional silica decreased elution concentration of lead as well as arsenic, even though, melting treatment with additional lime increased elution concentration of lead. 4. Heat treatment of the slag in the air atmosphere decreased elution amount of arsenic and lead in the elution test by 1N HCl solution. Decreasing in the elution amount of these heavy metals by heat treatment may be attributed to change of micro structure of the slag surface.
Effect of the composition of major components on the crystallization behavior of the melt-solidified slag by slow cooling process (2 K·min−1) was studied. In case of the synthetic melt-solidified slag with minor components, crystallization of the slag is progressed by slow cooling process when the basicity (= (%CaO)/(%SiO2)) is higher than 0.8. The precipitated crystalline phase is only Gehlenite (2CaO·Al2O3·SiO2). Crystallization of the slag initiates from the interface of the slag and the crucible, and from the surface of the slag. The basicity higher than 0.9 is required in order to precipitate the crystal phases over the entire slag. The influence of Al2O3 content on the crystallization is very little compared with that of the basicity. On the other hand, in case of SiO2-CaO-Al2O3 slag without minor components, the crystallization is promoted at higher Al2O3 content and lower basicity. Only few amounts of minor components in the slag can influence on the crystallization behavior, and even change the crystallized phase.
Viscosity changes of RO-SiO2-FexO (R = Ca, Sr, Ba) melts due to changes in the oxidation states of the iron ions by systematically varying the oxygen partial pressure were measured at 1773 K. The initial compositions of the samples were 30RO-60SiO2-10Fe2O3(mol%), and the ratio of Fe3+ to Fe2+ in the RO-SiO2-FexO melts increased with increasing oxygen partial pressure in all samples. Meanwhile, the viscosity of all the RO-SiO2-FexO melts decreased with increasing Fe2+ to total-Fe ratio (Fe2+/t-Fe). The data indicate that the increase in the amount of Fe2+ ions, which behave as network modifiers, would result in depolymerization of the silicate anions. In addition, the viscosity of the melts increased in the order of alkaline-earth cationic radius (Ba > Sr > Ca) when the Fe2+/t-Fe values of the melts were comparable. This would be due to the change in the coordination structure of Fe3+ in the melts.
There is an increasing trend in the copper smelters to recycle electronic materials, which contain relatively high concentration of platinum group metals. Platinum group metals lost in the slag is increasing with increasing of treated scrap amount. To determine the portion of the platinum group metals chemically dissolved in the slag will be a key factor to improve the recovery of those metals. An experimental study was carried out to determine the solubility of platinum in FeOx-SiO2 slag equilibrated with a pure platinum and the liquid Pt-Cu alloy at 1573 K and the range of oxygen partial pressure from 10-9 to 10-6. The solubility of platinum in the slag tends to increase with increasing oxygen partial pressure and content of copper in the slag. Based on the measured platinum solubility, activity coefficients of platinum oxide in the FeOx-SiO2 slag were derived. The activity coefficients decrease by increasing copper contents in slag. Therefore, lower copper content in the slag tend to lower precious metals dissolution in the slag.