The majority of its uses are based on its properties as a strong non-oxidising mineral acid, and on the properties of its inorganic by-products.
The major applications of hydrochloric acid are:
Metal Cleaning and Treatment. The 'pickling' of steel is the major use for hydrochloric acid. Combined with small amounts of inhibitors, it dissolves the iron oxides formed in the process of hot rolling steel while minimising any significant attack on the base metal. This produces the metal surface needed for further processing.
Mining. The mining industry relies heavily on the acid leaching of certain minerals from ore deposits, an economical method of recovering valuable minerals from otherwise inaccessible bodies of ore.
Food and Dairy Industry. Hydrochloric acid is used in protein and starch manufacture, as well as demineralising whey. It is also used extensively in casein manufacture and the regeneration of ion exchange resins.
Water Treatment. Hydrochloric acid is used widely in water treatment as an effective neutralisation agent for alkaline (high pH) effluent. It is also regarded as a very suitable alternative to sulphuric acid in this application as a result of the inorganic by-products that are generated in this process. It is also used in some swimming pool purification systems.
Chemical Raw Material. Hydrochloric acid is used as a raw material for both organic and inorganic chemical reactions, such as in the production of chlorine dioxide and the esterification of aromatic acids.
How hydrochloric acid is manufactured
Orica ChlorAlkali produces hydrochloric acid in its concentrated form (33% by weight) at its three manufacturing sites in Victoria, New South Wales, and Queensland.
It is mainly produced synthetically by burning hydrogen and chlorine to form hydrogen chloride gas. This is then absorbed in water to form hydrochloric acid. Hydrogen chloride gas is also produced as a valuable co-product from the Cereclor® manufacturing plant in Melbourne, Victoria. This is also absorbed in water and the acid produced then purified and filtered.