The fire service says the blaze which destroyed part of the Environcom recycling plant on Saturday night was caused by a spark inside machinery.
Linda Ramscar, of Lincolnshire Fire and Rescue, said: “We established it was caused by a spark from a metal fragment within a shredding machine used to dismantle old fridges.”
The chief executive of Environcom has told the Journal he is grateful nobody was hurt in the fire which started about 8pm.
Sean Feeney said the incident was “nowhere near as bad as it looked. He said: “We expect Monday morning to be business as usual.”
Mr Feeney said the fire damage was confined to one cormer of the site. He added: “There are no casualties at all and the fire brigade did an excellent job. There is minimal damage. There is far less damage than you might expect.
“We take the issue of fire safety very seriously. Everybody takes fire precautions to make sure everyone is safe during such an eventuality. Everyone got out quickly and safely. It is an extremely unusual occurrence.”
Mr Feeney said there was a full shift of about 30 people on site when the fire broke out.