Along with recent progress in advanced technologies, high performance P/M(powder metallurgy)parts has recently been developed and applied to various area including electronics. Very expensive rare metals are used in many of them. Since most of these metals are produced in very limited area, the supply sometimes becomes very tight and the price fluctuates in a wide range. In order to avoid such supply tightness and price fluctuation, demand for recycling these high value P/M parts has been increasing.

Kohsei built a recycling plant for high value P/M parts at Kita-Kyushu city in February, 2000. The present process is called “Zn Process”(zinc process), which is originally developed for WC-Co P/M parts.

What is “Zn Process”?

Zn Process for WC-Co Cemented Carbides

When WC-Co scraps are dipped in a molten zinc bath, molten zinc start penetrating between WC particles and dissolving Co binder, i.e Co film between WC particles. The dissolution of Co film results in separation of WC particles and independent particles float in molten Zn-Co alloy. Since zinc has high vapour pressure, zinc is easily removed in vaccuum condition after separation of WC particles. As zinc evaporates under vaccuum, Co content gradually increases and Co metal has to precipitate on WC surface from molten alloy. When zinc completely evaporates, all Co precipitates on WC particle surface, resulting in WC-Co powders with the same chemistry as original powder before sintering.

Remarks : Other than WC-Co cemented carbide, this Zn Process is very likely to be applied to sintered parts consisting of metals or compounds with high melting point. W-Cu and W-Ag powder metallurgy parts was successfully recycled into powder by this process.

Example: WC-Co Cemented Carbide

Recycling Process

A sputtering target, which is manufactured by sintering metallic powders of ultrahigh purity metals such as chrome and molybdenum, is used in electrodes and color filters of flat panel displays including plasma and LCD TVs, which are getting bigger, and LCDs for cell phones and laptop computers, as well as in semiconductors and magnetic recording materials. The material, which has a broad range of final demand, is essential in the electronic device field.

Based on the technologies related to vacuum furnaces and crushing that have been accumulated through our first plant's operation of recycling powder metallurgy parts, our company has independently developed technologies for reducing and removing impurities such as oxygen and sulfur in electrolytic chrome metals and then powdering them.
And we have completed the second plant adjacent to the first plant in March 2006 and started manufacturing high-purity chrome powders mainly for sputtering targets.

In addition to the manufacture of the chrome powders, the second plant is contracted to recycle spent sputtering targets through rerefining and crushing. On top of that, we will build the technology that is applicable not only to chrome, but also to other powder metallurgical materials used for sputtering targets, including molybdenum and tungsten to satisfy a wide range of needs from demanders.

Flow for Manufacturing High-Purity Chrome Metals

Contact Us:Development and Marketing Department
E-mail: kitakyu-sales@kohsei.co.jp

The Kitakyushu Plant delivers products that can satisfy customers and, in order to contribute to global environmental protection, has built the ISO management system and obtained the certification.

Policies on Quality and Environment

I have set our plant's policies on quality and environment as stated below.

Kohsei Co., Ltd. recycles rare metals, approximately 100% of which Japan has to depend on foreign sources, and provides them as recycled materials to contribute to the effective use of resources, as well as to meet customer needs. At the same time, based on the recognition that we are making an impact on the environment in the recycling process, the Kitakyushu Plant will be committed to providing materials satisfactory to the customers and reducing the burden on the environment as follows:

1. We deliver products that satisfy customers; make efforts for environmental conservation while economically balancing with social needs; and in order to contribute to a sustainable society, continuously improve the effectiveness of our quality and environment management systems in accordance with ISO 9001 and 14001.
2. We comply with laws and regulations related to quality and environment and other requirements agreed by the plant.
3. We work for the development of products that meet customer needs and provide high quality products.
4. We strive to save energy and resources and to reduce wastes, and actively promote the development of recycled materials to contribute to resource saving and recycling.
5. To fulfill the above commitments, we set objectives and targets concerning quality and environment and facilitate efforts to achieve the goals.
6. We document, implement, and maintain the policies on quality and environment, as well as inform every employee thereof.
7. For the purpose of maintaining the adequacy of the policies on quality and environment and their objectives and targets, we perform an annual management review and reconsider them if necessary.
8. We make available to the public the policies on quality and environment.

December 1, 2008 Toshinari Sumi Kitakyushu Plant Manager

1-109, Hibiki-machi, Wakamatsu-ku, Kitakyushu City, Fukuoka Japan (in the Hibikinada Seaside Industrial Area)

• About 20 minutes by taxi from Kokura Station
• About 15 minutes by taxi from Wakamatsu Station