Firefighters battled a blaze at a Darley Dale firm for more than three hours.
The fire was discovered just before 3pm at Firth Rixson, in Dale Road North, on Friday, June 6.
Matlock, Bakewell and Wirksworth firefighters were called in with an aerial ladder platform from Chesterfield fire station.
A Derbyshire fire service spokesman said: “There was a fire in a chimney spreading to the roof space of the building.
“Crews began using a hose reel jet to control the blaze and police were needed to control nearby traffic.”
The aerial ladder platform was used to help with observing the incident and with cutting away dangerous debris.
A Derbyshire fire service spokesman added: “The fire in the flu of a dropped forge at the building was brought under control by 4.08pm and cutting away continued.”
A thermal imaging camera was also used to search for any other dangerous hot spots that could reignite the blaze which was extinguished and made safe by about 6.30pm.