Water quality management
Metal Blanc Bourg-Fidèle - France
To meet the requirements of the 2 February 1998 order, water management is organised in a separate circuit with adequate treatment processes.
Treatment of industrial waters
The electrolyte* (mixture of water and sulphuric acid (20%)) which is in the batteries is collected during truck unloading in the crushing unit, and is stored in appropriate tanks.
It is valorized in two different ways which can be concomitant:
- External : In specialised companies which use it as etchant for wastes including non ferrous metals in order to recycle them in hydrometallurgy and then in pyrometallurgy.
- Internal : During crushing, the operations of the hydrodynamic separators require an addition composed of electrolyte* and treated industrial water. This mixture is collected and then sent to the internal physicochemical treatment plant (capacity of 8 m3/h).
The quality of the water after treatment is such that it can be recycled for internal industrial use and the excess can be released into the natural environment, after testing and controlling of the water quality. The quality of the treated industrial water is self-monitored to ensure that the treatment plant is working properly. Frequent unannounced inspections are made by an organisation approved by the Ministry of the Environment.
This treatment generates calcium sulphate (gypsum) which, after dehydration in a press filter, is sent to a pretreatment plant to be recovered for use in cement works.
Treatment of rainwater
Rainwater falling on the roadways and roofs of the site can be polluted by trace particles of lead.
To prevent any accidental contamination of the receiving environment and of the subsoil, Metal Blanc collects all the rainwater falling on the site; that rainwater is stored in a pool with a capacity of 2000 m3, before being treated in a physicochemical treatment unit with a capacity of 20 m3/h.
This treatment generates sludges that are recycled internally.
The recycled water is used in an internal circuit for cleaning, and the surplus is rejected in the natural environment after the water quality is controlled.
The control of the water release is self-monitored; each batch is sampled and analyzed. An agency certified by the French Environment Department is responsible for checking the synchronization of the self-monitoring by cross-analyses on a quarterly basis.