The Caronno Pertusella plant (Varese) was the starting point of the business adventure of Emilio Riva and is the “historical plant” of Riva Acciaio. It was built in just seven months, from August 1956 to February 1957, and was inaugurated on 7 March 1957 with the first casting. The date of 7 March is still celebrated as the official foundation day for the whole group. Few years later, in 1964, a disruptive innovation was introduced in the Caronno plant: three-line curved-type continuous casting, which would revolutionise the Italian steel industry in time. This new technology, introduced into Italy for the first time by Emilio Riva, was a milestone in steel production because from that time onwards, the small-sized lingots that had to be hot rolled in roughing mills into semi-products (billets) to be forged or rolled again into end products were abandoned altogether and the billets were obtained directly from liquid steel. The yield of the production cycle was improved and costs were reduced considerably.

By investing in production and environmental issues over a period of decades, Riva Acciaio developed one of the most advanced and environmentally sustainable plants in Italy and Europe. Today, the Caronno factory only produces specialty steel, both carbon steel and alloy steel in billets or continuous-cast square blooms in various sizes and grades that are employed in high-performance products for earth-moving machines, in the mining industry and in the energy and automotive sectors.