A worker lost two fingers after his hand was crushed by a gate in Sheffield.
The employee was trying to repair the main entrance gate at LKAB Minerals (Richmond), in Coleford Road, Darnall, when the horrific accident happened.
The company, which admitted breaching health and safety regulations, was fined £8,000 and ordered to pay £2,080 in costs.
Sheffield Magistrates' Court heard the man was one of two employees attempting to repair the gate, which weighed more than 400kg, on January 18, 2016.
One of the men used a forklift truck to lift the gate around 18 inches off the ground so his colleague could access the guide roller underneath.
But as the second man reached under to do so the chains slipped and the gate fell onto his right hand.
He lost the ring finger and his middle finger up to the first knuckle on his right hand.
HSE inspector Eddy Tarn said: "This injury was easily prevented and the risks should have been identified.
"Those in control of work have a responsibility to devise safe methods of working and to provide the necessary information, instruction and training to their workers in those safe methods along with effective supervision and monitoring."