Flue gas, water and steel by-products must be treated to meet strict emission levels. Our steel and environmental specialists can co-develop products with you to meet regulatory requirements effectively and economically.
At Lhoist, we can help you eliminate or market certain steel by-products. For example, non-recyclable dust collected in the furnace extraction system can be inertized and applied as a strengthening material in mines. Converter slag can also be valorized for use in other markets.
The industry faces increasingly severe environmental regulation, shortages of raw materials, and high metal prices. These challenges make the implementation of dedicated processes to treat metallurgical residues and recover their valuable contents even more relevant. Oily mill scale is a typical by-product in steel manufacturing. It is possible to recover its iron content efficiently without impeding the main iron-steel flowsheet.
Engineering and technology supplier to the iron and steel industry Paul Wurth worked with Lhoist to develop an innovative deoiling process, using a low temperature pyrometallurgical approach.
The process :
- is easy to integrate into a normal steelmaking flow sheet
- requires no specific residue preparation before it is loaded into the furnace
- is flexible with regards to sludge analysis
- offers high-quality iron oxide
- provides deoiled oxide that is easy to handle and charge to the sinter plant
- has no impact on the plant’s other steel processes.
Very low emission levels are being imposed for flue gases, such as acid gases, dioxins, furans and heavy metals. To meet these requirements, you need a highly-effective reagent and process that can be incorporated into existing installations.
For flue gas treatment in a dry sorption system, SO2 and other acid gases are neutralized using hydrated lime. Our flue gas treatment range has been specially developed to increase the efficiency of dry flue gas cleaning systems and reduce disposal costs of residues.
We deliver tailor-made mixtures of lime comprising activated carbon, lignite coke or special minerals to trap pollutants (e.g. dioxins and furans). The neutralizing effect of lime combined with the micro-pollutant capturing power of the additives eliminates the negative side effects associated with the injection of pure activated carbon.
Scrubbing flue gas is an alternative process to dry sorption. Sorbacal® reagents neutralize the acid gases in spray sorption and wet scrubbers.
Our milk of lime neutralizes the acidic water resulting from pickling, rinsing and flue gas scrubbing. It also assures an appropriate pH level and precipitates heavy metals. Following sedimentation, the water can be recycled back into your process or returned to the sewage system.
Water treatment generates a certain amount of sludge. Adding milk of lime before filtration makes the sludge easier to filter. Post-conditioning of filter cakes or centrifuge sludge with quicklime facilitates handling and disposal.
Converter flue gas that contains dust is usually washed. You can treat the resulting sludge with lime and recycle the iron-containing material back into the process.
If the sludge cannot be recycled, it can be dried and solidified using milled quicklime, making it easier to handle, transport and store.
Calexor® brand products help improve productivity and enable you to comply more readily with environmental legislation.
