The plant, which produces speciality steel bars for the automotive sector, had been shut down for almost a year after energy prices in Spain affected the company's performance.
Last Friday, Sidenor's management held a meeting with representatives of the works council and announced that the plant will restart in October with two shifts involving 20-25 employees.
"The restart was made possible thanks to the company's investments in innovation, energy efficiency, decarbonisation, optimisation of resources and increasing competitiveness," commented the workers' union UGT.
In June, Sidenor announced the construction of a new 30 kilovolt (Kv) electricity supply line for the Reinosa plant. The project, valued at €2 million ($2.14 million), is expected to be completed in December.