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16.10.2017

Reducing over coating – saving zinc with EMG eMASS®

Various process improvements lead to significant savings in zinc and aluminium by using EMG eMASS®.

Range of achieved and published results

There are various process improvements that lead to significant savings in zinc and aluminium by using EMG eMASS® electromagnetic strip stabilisation, as well as quality improvements in hot-dip galvanising or hot-dip aluminising lines. Roughly speaking, the respective implementation scenarios can be divided into three groups:

  • Reduction of the zinc over coating at existing or new hot-dip galvanising lines
  • Achievement of thin coating layers and thus massive savings on existing hot-dip galvanising lines
  • Narrow nozzle spacing at the air knife and extra homogeneous layers for new or existing hot-dip galvanising lines with a focus on e.g. the automotive industry.


Of course, users of EMG eMASS® strip stabilisation solutions are carefully and cautiously publishing figures on the actual savings achieved, but in the last 10 years they have presented results at conferences and trade fairs, which we want to take up in this series of articles and put into the context of the above-mentioned application scenarios.

Let's start with the reduction of the zinc over coating at existing or new hot-dip galvanising lines

In a narrower sense, this scenario only applies to existing plants that are already in production. In new plants, EMG eMASS® is used from the very beginning to avoid over-galvanizing as far as possible. A before/after comparison is neither sensible nor possible with regard to costs. Let us therefore concentrate on the upgrading of existing plants.

In 2007, thyssenkrupp Steel was already able to demonstrate at the EMG eMASS® pilot plant that it is possible to reduce the standard deviation in the zinc coating from 4.4 g/m2 to 1.8 g/m2 for a single-sided layer of 160 g/m2. A reduction of the over coating by 1.5 - 2 g/m2 seemed to be within reach.

Results from continuous operation of EMG eMASS® were then provided by ArcelorMittal Columbus, USA, at the Galvanizers Conference 2010: "Immediately after commissioning, the coating target of the plant could be reduced by 1 g/m2/side".

These results were topped by Galvatech in 2011, also on the occasion of the Galvanizers Conference. The total coating could be reduced by an average of 3.3 g/m2 (or 1.65 g/m2/side) and in terms of production volume in 2011, Galvatech reported a zinc saving of 202 tons/year. This was at that time equivalent to €359,000 and would now be worth over €520,000!

At the JSI-ESTAD Conference 2014 in Paris, ArcelorMittal added: "In Cleveland [ArcelorMittal, USA] the over coating could be reduced by 1 to 1.5 g/m² with this solution [EMG eMASS®].”

Conclusion:
Based on this and supported by internal information from various customer projects, we can now say that upgrading an existing modern type of hot-dip galvanising line with an
EMG eMASS® strip stabilisation system can lead in regular operation to a reduction in the over coating of at least 1 g/m2/side or more. This has been proven and published by the world's leading steel manufacturers!

And of course, the added value that can be achieved by using EMG eMASS® is not limited to zinc savings. In addition, there is the significantly more homogeneous coating in the cross profile as an important requirement of demanding end customers (e. g. in the automotive or packaging sector) as well as a possible increase in line speed without any loss of quality.

Just to make it clear: this applies to modern systems that already produce high-quality surfaces even with low coating layer weights. The next article in this series discusses the potential for significantly higher added value through an investment in EMG eMASS® for systems that cannot yet produce thin zinc coatings, e. g. due to the design of the blow-off nozzle.

Read more: Producing thin layers – massive zinc savings with EMG eMASS®

What this means for your plant can of course only be estimated after taking a close look at the situation on site and knowing the actual production data. We are also happy to provide you with the corresponding calculation aids and advise you in detail.

You also want to save zinc and want to know more about EMG eMASS® and the specific application in general? Please feel free to contact our sales organisation or our product management directly at: steffen.dombrowski@emg-automation.com and visit our website.