Natural slate ore is one kind of sedimentary rock and formed from shale by metamorphism. Slate had been used as building stone because it is hard, fine and strong ore, and it has a characteristic of the cleavage.
On the other hand, in north part of Japan during the winter season, in order to ensure a safety driving on the frozen roads the use of non-skid powder is required. A large amount of CaCl₂, NaCI, KCI, etc. are used as reagents and are scattered on the frozen roads during the winter to melt the snow resulting to a high cost.
In this study, the non-skid powder for the frozen road by was developed using natural slate. Primarily, the contact angle and zeta potential of slate and other reagents were measured. Secondly, the properties of the coefficient of static friction and dynamic friction in case of using slate (1.5-4.5 mm, aspect ratio: 1 to 3) mixed with some reagents were investigated. Regarding to experimental results, it was obvious that the nonskid powder created as a mixture of natural slate ore and CaCO₃ 5wt% stick easily to the frozen road and exhibit the highest skidless performance.

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In Japan, about 5 million of automobiles are scrapped recently and the processing of these scrapped automobiles generates a huge volume of waste known as ASR (Automobile Shredder Residues). At this stage, much of ASR is filled in disposal sites or is burned up to the harmless ash. The disposal of ASR by landfill is to keep the noxious substances under the grand and it means to give some loads to the soil environment. As for the disposal by mass burning, the particular equipment for waste gas is needed in incinerators so as to suppress the dioxins. To overcome these problems, it is necessary to recycle and reduce the noxious substances in ASR for the soil and atmosphere environment. In this study, the experiments on the recovery of copper, which is considered to be a catalyst of dioxins, were carried by a dry tower mill and an electrostatic separator from the light materials of ASR. It was found that the solidified light materials from ASR could be easily comminuted to less than 1 mm. Besides the copper content of a comminuted product with the size fraction of-1 mm could be reduced to 0.38% by electrostatic separation.

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The purpose of this research is to recover a metallic resource in wastes by using the thermite reaction that takes place between an oxides and metallic aluminum. We tried to cause the thermite reaction between the chromium oxide in the chromium electroplating sludge and the metallic aluminum in the Al dross, and to recover metallic chromium. After the sample was prepared under various conditions, reaction heat, starting temperature and reaction ratio were analyzed by differential thermal analysis and ICP-AES. As a result, the thermite reaction was caused between the sludge and Al dross, and Cr₂O₃ in the sludge was reduced to metallic Cr. Moreover, along with the processing time by a ball mill, reaction heat and reaction ratio increased, and starting temperature decreased.

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Much of sludge, which is produced by neutralization of the heavy metal ions containing wastewater from pickling and plating lines, is dumped out as industrial waste. To recycle the sludge as iron source, the tramp elements, such as nickel, zinc, must be separated from iron in the treatment of wastewater. This paper describes the experimental study on the separation of tramp elements using the crystal growth with pH control. The results are summarized as follows.
Fe³⁺ ions are separated from the wastewater containing heavy metal ions as solid at pH4, and Ni²⁺, Zn²⁺ ions are separated at pH9.
With the treatment of wastewater containing Ni²⁺ and Zn²⁺ ions using the crystallization reactor which has a cake filtration unit, the mean particle size increased into 35.5 μm by the crystallization.
The growth of particle lowers the specific resistance of cake by two orders.

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