Rolling mill zinc oxide dusts recycled

Using an innovative procedure, zinc oxide is recycled from steel works dust produced by rolling mills, with GE Fanuc's CIMPLICITY software used to monitor the recycling process. P

Using an innovative procedure, zinc oxide is recycled from steel works dust produced by rolling mills, with GE Fanuc's CIMPLICITY software used to monitor the recycling process, says Chris Milburn, PLC Sales Manager, GE Fanuc Automation (UK) .

The company B U S is one of the leading European suppliers in the field of reprocessing and recycling recoverable materials from industrial processes.

In Freiberg, Saxony, B U S runs an oxide leaching plant.

Since November 2000, a new SDHL procedure is being used to recycle zinc oxide from steel works dust produced in rolling mills.

This procedure was awarded the innovation prize of the Free State of Saxony.

Up to 100,000 tons of steel works dust can be recycled each year.

The new procedure reduces the energy requirement to recover metals such as iron, zinc and lead by more than 40%, while at the same time increasing the plant's throughput by 30%.

The new SDHL procedure is very sophisticated, requiring the highest precision in process parameters.

First, the dust is heated to 1,100 degC in a furnace.

During this step, the zinc is dispersed as powder.

This powder still contains chlorine which needs to be washed out in subsequent stages of the process.

Then, common salt and zinc oxide is obtained by adding soda.

Finally, the zinc oxide is removed from the solution using filter presses and can then be reused for the metallurgical process in the rolling mill.

In order to work properly, this recycling procedure requires a very accurate control of temperature, mixing proportion, flow rate and water conductivity.

The conception, planning, installation and commissioning of the entire control technology was the responsibility of system integrator 'K + L Elektrotechnik' who took six months to realise the project.

The control concept includes a PLC with decentralised peripherals, approximately 300 digital and 50 analog I/Os, Profibus DP-Asi transducers as well as a Display Station 2020 industrial PC running GE Fanuc's monitoring and control software CIMPLICITY HMI Plant Edition.

Communication is carried out via Profibus-DP as well as via an Asi bus between peripherals.

Using the Asi bus enabled a reduction in control costs of 25%.

Altogether, the CIMPLICITY HMI monitoring and control software processes data from around 700 data points.

The software is installed on an industrial PC running under Windows NT.

The CIMPLICITY HMI software monitors the temperature, filling level, flow rate, density and conductivity parameters.

When the monitoring and control software had to be selected, the following features were considered to be CIMPLICITY's strong points: * The workbench and the 'drag and drop' functionality enable a quick configuration of the application.

* Integration with third-party controllers is very easy.

I/Os are accessed directly, there is no need to develop separate modules or I/O connections to access the PLC memory.

* The system is very easy to operate.

When asked about his experience with CIMPLICITY, Jan Kermer, Managing Director at K+ L, replied, "As system integrators, we appreciate the easy configuration of the CIMPLICITY software.

Also, with over 100 drivers, integration of third-party products into a control concept is no problem at all." The plant was put into service over a year ago and has been running smoothly since then.

B U S is now thinking about installing a second furnace in the plant which, of course, would also be monitored by CIMPLICITY HMI.

GE Fanuc Automation is a leading global supplier of automation controls.

These products and services include a wide range of CNCs, motion control products, micro to high-end PLCs, monitoring and control software products, and CO2 and YAG lasers.

GE Fanuc Automation is a joint venture between GE and FANUC and the company's European headquarters are at GE Fanuc Automation Europe in Luxembourg.

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