Recycling waste
Keywords: Recycling, Wedge Group, Galvanizing
Wedge Group and other members of the UK hot dip galvanizing industry are at the heart of a new project to recycle waste and turn it into a valuable raw material that will they believe benefit the environment.
The scheme has attracted funding by the DTI, under the auspices of its Recycling Programme - one of only nine projects to do so out of a total of 241 submitted.
It involves recycling waste acid from the galvanizing process and turning it into ferric chloride which can be used to treat and clean up waste water.
`We're talking about being able to regard something as a desirable and useful product, rather than as waste material that has to be dumped.
"It's industry with a green spotlight on it", explained Bob Duxbury who is very much involved in his capacity as both director of process development at Wedge, and as chairman of the Technical Committee of the national Galvanizers Association, which has set up the project.
The demand for ferric chloride is driven by the EU's urban wastewater directive, which is increasingly stringent on controlling the discharge of phosphates.
One effect in the UK is that the Environment Agency has the objective of reducing contamination levels and cleaning up rivers.
Two methods for taking out phosphates were tried initially, biological removal and chemical precipitation, but neither proved ideal.
Experiments were then carried out with ferrous salts, and, as a result, it has been found that the addition of ferric chloride to systems for purifying water are an efficient and economical way to get rid of the contaminants.
"It is capable of completely knocking out the nasties - they've found it does the trick", says Bob.
Last year, 40,000 tonnes of ferric chloride were sold for this purpose and the level is expected to grow significantly to enable UK water companies to meet their consent levels.
The galvanizing industry produces ferric chloride as a waste by-product from the pre- treatment cleaning processes carried out on the metal before it goes for dipping into zinc in the galvanizing bath.
About 4050,000 tonnes of spent liquor is produced from the industry's pretreatment plants every year.
The waste also contains other solutions in varying amounts and, at the moment, is tankered away, then mixed with alkaline, filtered and taken to landfill sites in a solid cake-like format.
This method is not 'environmentally friendly' and it. is also becoming increasingly expensive in both transport and treatment charges.
So the new project, if successful, could be a big boon all round.
Central to its success will be the ability of individual galvanizing plants to control the content of their spent liquors for efficient use of the iron chloride in the water treatment sector.
The School of Chemical Engineering at the University of Birmingham is carrying.out technical work, in particular to establish the required criteria for generating ferric chloride and where appropriate will be suggesting how working practices and processes could be modified to achieve these aims.
Details available from: Wedge Group Galvanizing Ltd; Tel: +44 (0) 1902 630311; Fax: +44 (0) 1902 366353; E-mail: info@wegde-galv.co.uk;Web site: http:\\www.wedge-galv.co.uk
