The recycling of valuable resources has currently became a major worldwide subject in the industries from the viewpoint of saving energy and protection of environment. Since the accumulated amount of steel product is reaching almost one billion ton in Japan, it is very important to develop the technology for the removal of tramp-elements such as tin, copper and zinc from steel scrap. In the present work, the rate of tin removal by the evaporation from carbon saturated liquid Fe-Sn-S alloy has been studied at 1, 673 K under reduced pressure.
Tin evaporates from molten iron and equimolar amount of sulfur is also removed together with tin. The evaporation rate of tin increases with increasing initial sulfur content in the melt. It is confirmed that tin dissolved in liquid iron is removed in the form of SnS under the presence of sulfur in the metal. The rate of tin evaporation becomes faster with reducing the pressure in the reaction chamber. This indicates that the rate is controlled mainly by the mass transfer of SnS in the gas phase.

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Used aluminum beverage cans (UBC) are able to be recycled into can body material (JIS3004) by remelting. However, in these remelting processes, such problems attributed to “paints” occur as unfavorable molten metal composition (primarily titanium) and lowering of molten metal yield. Consequently, for promoting recycling of aluminum UBC, removal of these “paints” is essential, and the paints have been removed by thermal method etc. Previous paper repoted the development of a swell-peeling method in which paints are chemically removed, ensuring the good possibility of promoting recycling of aluminum UBC. This paper reports the details of swell-peeling mechanism.

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A mixture of iron, copper and carbon was melted in a carbon crucible at 1, 453 K. The top layer which was rich in iron and the bottom layer which was rich in copper were clearly separated in the crucible. We could thus make fundamental experiment to carry out a phase separation for copper recovery from iron scrap containing copper. One of the focuses is the effect on the phase separation and the suspension of an extra element to the Fe-Cu-C ternary system. We added Cr, Mn, Al, Si or S to Fe-Cu-C ternary system, and determined the compositions of miscibility gap at 1, 453 K under carbon saturation. In some cases scrap contains precious metal. On this account the recovery distribution ratios of precious metal were also measured.
The alloy compositions on the miscibility gap in the Fe-Cu-C system are 91.1% Fe-4.7% Cu-4.2%C and 96.7%Cu-3.3% Fe. Addition of aluminum, Silicon or sulfur causes the gap to narrow. An increase in carbon solubility in the phase rich in iron reduces copper solubility, which affects recovery of copper from scrap. The relation between copper and carbon solubility in the phase rich in iron is
(% Cu)=0.68 (%C) 2-7.26 (%C) +22.77
Gold, silver and palladium are enriched in the phase rich in copper. Platinum distributes both phases equally. The activity coefficients of Ag, Au, Pd and Pt were estimated from the distribution ratios.

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Soil washing treatment is a water based process for mechanically scrubbing soils ex situ to remove undesirable contaminants. The process remove contaminants by dissolving or suspending them in wash solution or by concentrating them into a smaller volume of soil through particle size separation techniques. This process together with biological treatment is relatively mild to soil nature compared thermal treatment, so adequate for recycling of soil.
The concept of reducing contamination through the use of particle size separation is based on the finding that most inorganic or organic contaminants tend to bind to clay and silt soil particles. Washing processes that separate the clay and silt particles from sand and gravel soil particles effectively separate and concentrate the contaminants into a smaller volume of soil that can be further treated or disposed. The clean, larger fraction can be recycled.
In this paper, we demonstrate our trials with four types of heavy metal contaminated soil by three methods. Those method are a laboratory size separation experiment, a pilot plant experiment and a full scale plant treatment.
For one type of soil the results of the laboratory experiment were shown to be different from those of the pilot plant experiment. It was suggested that a laboratory test with small volume of soil would make a incorrect estimation for treatability caused by heterogeneity of soil.
Another type of soil showed a result that heavy metals exist at higher concentration in coarse particles than fine ones. It was suggested that for this type of soil, simple soil washing treatments are not applicable.
A full scale treatment process were shown, and practical quality control were emphasized.

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The subsurface contamination with Petroleum Hydrocarbon (PH) can cause serious environmental problems such as the effect to human health or the decline of soil-bearing capacity. Numerous remediation technologies for PH has been developed, and one demonstrated technology is well known as bioremediation. In this study, our goal is to recycle the soil which contaminated with PH using the bio-pile and flotation methods. The bio-pile as one of the bioremediation methods is heaping contaminated soil in which the pipe for supplying air, water and nutrients were installed to activate the indigenous microorganisms in the soil to degrade contaminants. Heap also contains sawdust to keep ventilation for air and initial nutrients in proportion to the amount of contaminants. During this study, oxygen concentration, volatile compounds, number of bacteria, temperature and moisture were monitored. From the fact thatoxygen in the gas decreased from 20 to about 2% and the temperature inside the pile increased from 20 to 40°C, it was confirmed the indigenous microorganisms were activated by this method. And Total Petroleum Hydrocarbon (TPH) was finally degraded to about 50% of the initial amount.
The soil remediated by the bio-pile still contained 3, 000-5, 000mg/kg of Asphaltene (it shared about 15% of the rest TPH) and 4, 000-8, 000mg/kg of Resin (about 20%) which were not degraded by the microorganisms. For this soil, flotation treatment was conducted sequentially to the rest of PH, and it was confirmed that the TPH concentration of soil could be degraded to less than 1, 000 mg/kg.
It was concluded that the combination of this bio-pilewith other methods such as the flotation method could effectively remediate the soil contaminated with PH and remediated soil could be recycled as a clean soil.

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