MADRID (Reuters) – ArcelorMittal has started negotiations with unions this week on a broad furlough scheme for the 8,300 workers at its Spanish mills in the face of weakening demand and soaring energy prices, a company spokesperson said on Friday. The world’s largest steelmaker expects to reach an agreement within a couple of weeks to allow it to idle any of its plants in Spain for any period of time until the end of 2023, the spokesperson added. ArcelorMittal’s Sestao steelworks near the northern city of Bilbao, which has an annual capacity of 700,000 tonnes, is already idle and the company a…