Two blast furnaces at Tata's biggest UK steelworks have been restarted after a large explosion left two workers with burns.
A train carrying molten metal derailed at the Port Talbot plant shortly after 03:30 BST on Friday. An investigation is under way.
Tata Steel said its fourth and fifth furnaces had been successfully restarted.
Hub manager Martin Brunnock praised staff for their professionalism.
Following yesterday’s incident at #porttalbot steelworks, ironmaking operations have resumed with today’s restart of #BlastFurnace5. BF4 is expected to restart later today. Apologies to local residents who may witness noise & steam emissions which are normal part of BF restarts— Tata Steel UK (@TataSteelUK) April 27, 2019
Images and footage posted on social media showed a large mushroom cloud and plumes of smoke rising above the plant.
Two workers were aboard the train - carrying a "torpedo" which holds the molten metal - when it derailed, leading to the metal coming into contact with cold water.
Tata said one worker had a burn to the head and the other to the chest, and were later released after treatment for minor burns.
The site had reopened by 07:00 Friday but production at furnaces four and five were halted in order for checks to be completed.
Tata said supply to customers had been uninterrupted.