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Kitakyushu Plant
Recycle of Powder Metallurgy Parts

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.

One of very unique points is that Zn Process does not generate any wastes, neither waste water/gas nor waste material. It also results in “very high yield”, i.e., very little material is lost in this process. This is an ideal recycling process in respect of environmental protection.

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
WC-Co Cemented Carbide


Manufacture of High-Purity Metals

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
Flow for Manufacturing High-Purity Chrome Metals

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


Efforts for Quality Improvement and Environmental Protection

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.

Quality and Environment Policy

We, Kohsei. Co., Ltd, approach to recycle of rare metals and supply of the high quality reclaimed materials to the market, which let us be a part of environment-friendly industry. Thus we strongly comprehended that the industrial processes effects the environment. In order to provide customer satisfactory products with reducing the impact on the environment in the production process, we claim and implement the following quality and environment policy:

  1. We approach to quality underscores our dedication to product and service excellence, customer satisfaction and environmental responsibility, endeavor to reclaiming the rare metal products so as to contribute to a recycling-based society.
  2. We comply with laws and regulations related to product quality and the environment, and other requirements which we agree with.
  3. We endeavor to develop high quality new products that meet customers’ demand by promoting the development on recycle technology which can save energy and resources, and reduce waste, so as to contribute to resource saving and environment improvement.
  4. We endeavor to take balance between economical productions and social requirements. In order to contribute to a sustainable society, we continuously improve our quality and environmental management systems in accordance with ISO 9001 and 14001.
  5. We document, implement and maintain the quality and environment policy, and publish them to every employee. We also undertake an annual management review and implement corrective action accordingly, which make the policy be easily implemented by every employee.
January 1,2023
Kitakyushu Plant Manager

Location of the Kitakyushu Plant

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


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