The industrial fire which at the Smethwick recycling factory still has a crew of firefighters at the incident which was caused by a single Chinese lantern.
Plant machinery is being used to get to the seat of the fire by breaking up bales of burnt plastic.
A fleet of 45 fire crews from across the West Midlands were sent to the Jayplas depot, Dartmouth Road, on Monday in what is being labelled as one of the largest fires seen in the area.
Firefighters at the plant battled the blaze involving 100,000 tonnes of plastic recycling material. West Midlands Fire Service broadcast live from the scene of the incident.
A single Chinese lantern has been cited as the cause of the incident with the fire service saying it could take several days to deal with the inferno.
Plumes of smoke from the fire rose 6,000 ft into the air and could be seen as far as 30 miles away.
Birmingham International Airport were alerted, though there were no reported delays or cancellations.
Two firefighters were taken to hospital, one for an eye injury and the other for an ankle injury, with a further 11 injured at the scene.
CCTV pictures show the fire took just eight minutes to start after landing on a bale of plastic around 23:00 BST on Sunday evening.
The blaze is said to have caused an estimated £6m worth of damage.
Vij Randeniya, chief fire officer at West Midlands Fire Service, said the fire service had been calling for better controls on Chinese lanterns before the Smethwick fire.
“We believe a Chinese lantern dropped onto some bales of plastic and, looking at CCTV, it would appear that was the cause.
“Chinese lanterns have been involved in a number of incidents and firefighters have been campaigning for there to be better controls.
“They look really nice but they do pose a danger.”
Mr Randeniya added: “These are difficult fires to extinguish and we anticipate being here for a number of days.”
The Smethwick fire is said to be the largest that has occurred in the West Midlands area in recent times.
West Midlands Fire Service area commander, Steve Vincent, said:
“This is the largest fire that we’ve had in the West Midlands. It is a major fire and we’ve got support from surrounding fire brigades to help us deal with this.”
Mr Vincent added that because the fire was in a mainly industrial area, local residents had not been evacuated.
“We haven’t evacuated any of the local residents because this is mainly an industrial area but we have had some minor injuries to some of our firefighters at the scene.
“We’re working with other emergency services and they’re all safely being treated.
“We will have major congestion in this area because we will be fighting this fire for the next few days.”
Environmental authorities are worried about the damaging effect the fire may have on the surrounding plant and wildlife.
The primary concern from the blaze is the impact of potential pollutants and falling oxygen levels in nearby watercourses.
Samples are being taken from nearby canals and rivers by the Canal And River Trust, alongside the Environment Agency, to ascertain the what steps are needed in order to protect fish and other wildlife.
Water is also being pumped from a nearby canal to help reduce any risk.
The Environment Agency in the Midlands said it was “cautiously optimistic about pollution” as watercourses checked earlier showed “no sign of environmental impact” so far.