Fourier transform infrared spectroscopic analysis was applied to determine the molecular structures of compounds formed on the surface of copper plate in the 2-mercaptobenzothiazole (MBT) aqueous solution. Copper plates were dipped into aqueous solutions of MBT at various pH values. They were then removed, dried under vacuum and their spectra were analyzed. A surface MBT compound having the infrared spectrum of copper-MBT complex was formed on the copper plate. A structure was suggested for the surface complex, Cu(II)-MBT. The complex of copper(II)-MBT on copper plate may be assigned to the formation mode of thiol groups that are strongly ion-bonded to Cu(II) to form a scquare planer structure.

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Several new collectors including Benzoyl thiourea, Butyl thiourea, Butyl thiocyanate and Dodecyl thiophenol were designed and synthesized, and their collecting performances on gold, pyrite and pyrite bearing gold were studied as well in this paper. The collecting effect on gold decreased in order of Dodecyl thiophenol, Butyl thiocyanate, Butyl thiourea and Benzoyl thiourea. The selectivity increased in sequence of Dodecyl thiophenol, Butyl thiourea, Benzoyl thiourea and Butyl thiocyanate. Furthermore, the unusual high selectivity of Butyl thiocyanate was investigated using modern structural theory. We suggested that a rather unusual π-bond selectively formed between Butyl thiocyanate and ores. The gold containing d¹⁰ electrons had a stronger ability to form a kind of bond than ferrum containing d⁶ electrons. This led to the high selectivity of Butyl thiocyanate for gold flotation.

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It is longed to improve high water content soil which is discharged at the civil engineering works and to reuse the improved soil effectively because of decreasing the lands for spoil-banks.
High water content clay is usually dehydrated to reduce its volume, but further the dehydrated cake needs to be hardened by a cement type stabilizer to be reused. So, the authors worked out a new method that was adding a small amount of cement before dehydrating in order to improve the both dehydrating and solidifying characteristics of the cake.
As the result of the research on this method, the following were clarified.
1. Due to the addition of a small amount of cement, the dehydration characteristic was greatly improved, and the strength of the dehydrated cake became larger.
2. The dehydration characteristic was affected by the liquid limit of soil, and the strength of the dehydrated cake could be designed by cement content rate to dry soil.

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Rare-earth magnetic roll separators have been established in numerous industrial minerals processes since the first useful concept was developed in 1981 by the author. Initially believed to be a machine suitable for certain "niche" applications, such as coarse refractory materials, further improved separators have replaced electromagnetic separators in most industrial uses. Major reasons are higher capacity (typically 50 to 200%, sometimes more), greater product recovery and enhanced quality, all at lower cost.
The most recent development is a separator that is performing similarly to the most powerful superconducting drum separators for coarse rock particles. Also, a new machine with 3 to 5 times greater capacity per unit compared to prior standard rare-earth magnetic roll equipment (approximately 10 times that of induced magnetic roll separators) is ready for industrial use. Another product development is the extension of the processing width of 100 mm (4") rolls from 1.0 to 1.5 meters (40 to 60").
The paper emphasizes gains in product quality and economics by using rare-earth magnetic roll separators at current development stage. Projections for the near future will also be provided.

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Platinum group metal catalysts have been developed for synthesis of chemicals and intermediates due to their unique activity and selectivity in such reaction as hydrogenation and oxidation. Recently, the increased importance of environmental control catalysts now represent the largest single application and one that is likely to evolve further in terms of the technology due to the increased demand for a clean up of vehicle exhaust fumes. Thus, the demand for platinum group metals has increased because of their applications in the automobile industry as emission control catalysts. Consequently, it is necessary to establish recycling technology for spent catalysts containing platinum group metals. This paper will describe some examples of practical operations to recover platinum group metals such as platinum, palladium and rhodium from spent catalysts.

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