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Data Entry: September 2011
Name of recycling technology Recycling of Sludge/Dust containing Valuable Metals (Nickel/Zinc)
Name of recycler Daido EcoMet Co., Ltd.
Location Aichi Prefecture
Name of eco industrial park -
Receiving waste materials for recycling - Dust and reduced slag generated from electric arc furnaces (EAFs) for steel making (Zn: 18%)
- Sludge generated from acid pickling of stainless steel products (Ni(OH)2: 2-3%)
- Sludge generated from nickel plating (Ni:≥5%)
Recycled products/recovered materials - Zinc raw materials (Zn: 40-50%)
- Nickel alloy (Ni: 7-14%)
- Aggregate (gravel for construction materials, etc.)

Zinc raw material

Nickel alloy

Capacity of recycling plant 43,000 t/year
Area of recycling plant 2,310 m2
Number of employees in recycling plant Employees at Chita Plant, Daido EcoMet Co., Ltd.: 55
Among them, recycling equipment staff: 19
(As of April 2011)
Start of recycling operation March 1996 
Technical description
  • Technology for recovering nickel alloy
    Extracts nickel by drying to powder, melting and reducing sludge (Ni(OH)2: 2-3%) from the stainless steel production process or sludge (Ni ≥ 5%) from the nickel plating process.

Recycling process

(1) Drying process
Using heat generated in the melting process, dries wet sludge to powder.
(2) Melting and reducing process
Dry, powder-like sludge is directly melted at high temperature generated by a specially designed fuel-oxygen burner. Carbon (reducing agent) injected into the molten sludge reduces metals (nickel and iron). A high-specific gravity nickel-iron alloy forms in the lower layer, while molten slag remains as the upper layer. These layers are collected separately. Nickel alloy is used as a material for stainless steel. The molten slag after cooling is used as aggregate for road construction.

  • Technology for recovering zinc material
    Dust (Zn: 18%) from steel-making electric arc furnaces and reduction slag are melted. Vaporized zinc is cooled and recovered.

Recycling process

(1) Melting process: A specially designed fuel-oxygen burner is used to directly melt dust and slag from electric arc furnaces at high temperature. Zinc is vaporized, leaving molten slag. After collection and cooling, the molten slag is used as aggregate for road construction.
(2) Cooling and recovery process: Rapidly cools exhaust gas from melting furnaces. Collects powder containing a high concentration of zinc with a dust collector. The collected powder is used as a zinc raw material.
Background of starting recycling business and participating in eco-town program
  • Disposal problem associated with industrial waste produced from specialty steel production processes
    - Slag, dust and sludge produced from specialty steel production processes were rendered harmless, stabilized and then disposed of at a waste disposal site as industrial waste. However, the disposal fee increased as such disposal sites ran out of space.
    - The company's customers and society demanded it to achieve zero emissions.
  • Surge in price of rare metals on the international market
    - Slag, dust and sludge containing rare metals such as nickel and zinc were disposed of at waste repositories instead of being recycled.
    - The prices of imported nickel and zinc raw materials increased, enabling recycled nickel and zinc raw materials to compete in price.
  • Initiatives of local government
    - The Aichi Prefectural Government (via the Deputy Governor and others) enthusiastically invited the company to take part in the eco-town program.
Fund procurement - Their parent company (Daido Steel Co., Ltd.) constructed the zinc material recovery equipment, while Daido EcoMet operates it.
- The company provided the capital investment for the nickel alloy recovery equipment through a loan from the parent company. Since the subsidiary (Daido EcoMet Co., Ltd.) is financially independent from the parent company, the loan must be repaid.
- The national government and the Aichi Prefectural Government valued the high performance of the nickel alloy recovery technology and awarded the company subsidies.
  • Nickel alloy recovery plant construction cost: JPY1.65 billion
    Breakdown Subsidy from national government: JPY340 million
    Subsidy from Aichi Prefectural Government: JPY10 million
    Loan from parent company: remainder
Major success factors
  • Established fundamental technologies
    - The recycling technology is an application of the electric arc furnace technology of the parent company (Daido Steel Co., Ltd.).
    - The nickel alloy recovery technology was developed based on technology for recovering zinc raw material.
  • Ensuring distribution channels for recycled products
    - The parent company was ready to purchase recycled nickel alloy as a raw material for stainless steel.
    - The aggregate can be marketed as a material for concrete products.
  • Demand for recycling sludge from specialty steel production process
    - There was potential demand for the recycling of sludge produced from specialty steel production processes in Aichi Prefecture, which is the largest producer of specialty steel in Japan.
  • Parent company's high interest in environmental management and corporate social responsibility (CSR)
    - The company established a recycling system between the parent company and subsidiary.
    - Some 80% of the required capital investment was lent by the parent company.
    - Since the recycling facilities were built on the same site as the parent company, no new site or infrastructure (roads, water, fuel, etc.) was required.
Issues and Challenges
  • Covering high project costs
    The company used multiple funding sources, such as subsidies from the national and prefectural governments and a loan from the parent company.
  • Technology development
    The company had technical and financial difficulties in developing the equipment and operation procedures. The design department of the parent company helped the company to develop the technologies.
Future prospects - The company's business is basically to recycle byproducts from the steel industry.
- Human resources (intellectual resources) are essential to overcoming challenges in developing new technologies. The company plans to continue to use its experience in metallurgical technology to develop new technologies.

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