Hispavic Ibérica SL and Vinilis SA are two companies of the SOLVAY group dedicated to the manufacture of polyvinyl chloride (PVC) that constitute the same industrial complex located in the municipality of Martorell.

For the manufacture of polyvinyl chloride (PVC) there is a previous stage of obtaining chlorine gas through a process of electrolysis of the salt (NaCl) that comes from Súria. This chlorine is the raw material that is sent by pipeline to the vinyl chloride production plant (VC / DCE process) located in the same industrial complex. From the polymerization of this vinyl chloride the final product is obtained, the polyvinyl chloride (PVC).

The chlorine gas leaves the electrolytic hot cell (70-80ºC). Once it is saturated with moisture it has to be supplied cold and dry. This process needs three stages: cooling, drying and compression. In order to dry the chlorine, concentrated sulphuric acid (98%) is diluted in the process at 50-60% of concentration. This sulphuric acid is the waste that is managed as a by-product (acid to adjust the pH) in the treatment process of the wastewater. Nevertheless, limits to the sulphate use in wastewater were established. As a result, it could no longer be used in SOLVAY wastewater treatment plant.

For the search of outputs as a by-product, the characterization of dilute sulphuric acid was undertaken. It has a richness between the 50% and 60%, and a chlorine concentration of less than 50 mg/ kg was made.

The possible industrial applications that were found, and that were carried out by the administrative framework of the by-product in Catalonia, were:

MANUFACTURE OF SALTS (aluminium sulphates, chromium sulphates ...). The receptors use the diluted sulphuric acid as a dosage for the manufacture of different salts in substitution of concentrated sulphuric acid and water.

MANUFACTURE OF FERTILIZERS (organominerals ...). The waste receptors use the sulphuric acid solution as the primary material in the production of organic mineral fertilizers.