Bad Honnef - At two locations, i.e. Melbourne, Australia and East Chicago, USA, CMA - in a strategic partnership with Scholz AG - runs worldwide unique recycling plants for Zinc – the Meretec Technology. Meretec is a patented technology that represents a significant world breakthrough in the environmentally friendly removal of zinc from galvanised steels that has been too difficult, too expensive and too dangerous to recycle. Galvanized steel is widely used in applications where rust resistance is needed, and can be identified by the crystallization patterning on the surface.

In total the technology is a 6-step de-zincing process:

1. Shredding: Galvanised scrap from the auto and building industries plus end-of-life coated products are pulverised into fist-sized pieces.
2. Removing the zinc coating: The steel is added to the reactor drum where hot caustic washes the coating from steel.
3. Washing: The steel is washed and a rust inhibitor added to produce, clean melt stock ready for foundries.
4. Purification process: The solution is purified to remove dirt and elements limiting zinc recovery.
5. Electro winning: The solution is electroplated in cells where the zinc is grown and harvested. The solution is returned via the evaporator to the drum and is washed.
6. Separation, washing, packing: The zinc is sent to a centrifuge and drier for drying and packaging.

The current demand of “clean black steel“ in the industry is pretty high (“Meretec Meltstock”). Zinc in the melting process creates problems; mills that smelt coated steel and many foundries cannot tolerate zinc. The Meretec process has different advantages: It reduces costs through higher melt yields less waste generation and cleaner melts, therefore it helps to meet increasing environmental and hazard standard regulations. According to Meretec experts the process can save in total 3000 tons of hazardous waste annually. In addition, it generates a tremendous resource saving effect, because zinc ores have – like most of the other metals – only a statistical availablity of around 20 to 30 years. Per year around 9 Mio tons of the world zinc resources are used but only a small amount is recycled.

Annually, at full capacity, each Meretec plant recycles 120.000 tons of galvanised steel – producing 2.000 tons of high grade zinc powder and 118.000 tons of clean black steel. Black steel is a worldwide important raw material for mills and foundries, it has to be free of contaminants such as zinc, tin, paint or chemical coatings. Each ton of galvanised steel which is de-zinced by Meretec and recycled saves more than one ton of iron ore, 0.635 tons of coal, 0.055 tons of limestone and 0.020 tons of zinc.

According to Scholz experts resource efficiency is one of the greatest demands in the future. Resource efficiency means we need a “managing concept” for raw materials. The need is to reduce energy, water and other resources in order to minimise waste and thereby reduce cost. Industry needs concepts for sustainable consumption and production in both developed and developing countries. The focus is on achieving increased understanding and implementation by public and private decision makers of policies and actions for resource efficiency. Decoupling economic growth from environmental impact is the answer, since we have a worldwide growing population and only small reserves of non renewable metals.

Quelle: Scholz-Group

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