Fire and Emergency New Zealand (FENZ) confirmed to Newshub early on Thursday morning that the blaze is now under control.
A couple of firetrucks remained at the scene overnight to monitor hotspots, the spokesperson said. The blaze was largely contained by early evening and the heavy smoke had mostly dissipated by 6pm.
Appropriate safety measures were carried out in the disposal of the burning scrap metal, Global Metal Solutions chief executive Roger Wilson told RNZ last night.
He said it is still unknown how the fire ignited.
Locals were warned by emergency alerts and the police to avoid the dense, black smoke.