Pursuant to Directive 2003/53/EC of the European Parliament and the Council of 18 June 2003 related to restrictions on the use of certain dangerous substances such as chromate (Cr6+) in cement, all Member States have been required to apply this legislation since 17 January 2005.
In practice, this means that the chromate (Cr6+) content is limited to 2 ppm of dry weight for all cement available on the market (except for use in closed manufacturing circles). Most natural cement contains more than 8 ppm of chromate (Cr6+) (up to 25 ppm), which in soluble form causes severe chrome dermatitis. Thus, this cement has to be treated to reduce Cr6+ to chromate Cr3+ form, which does not cause eczema. The most economical reducing agent for such treatment purposes is ferrous sulphate. It can be supplied and used in various forms such as wet heptahydrate, free-flowing heptahydrate or monohydrate. Chromate reduction by means of ferrous sulphate has already been successfully practiced in Scandinavian countries for almost 20 years. To meet the increasing demand as a result of the new legislation, copperas generated in line with titanium dioxide production can contribute significantly to compliance with the new legislation.
Did you know?
Ferrous Ions are also used in the leather industry to reduce and remove toxic Chromium from the waste water after the tanning process.
