The rupture and collapse of a boiling tank of sugar, and its subsequent collision with a second tank, has forced a full evacuation of North Queensland's Pioneer Sugar Mill, with three employees taken to Ayr Hospital for treatment.

According to mill management, no-one has been seriously injured, with one employee receiving minor injuries and two others being treated for shock.

Paramedics treated one patient at the scene while another was transported to Ayr Hospital with a throat irritation from the steam that issued from the vats.

A spokesperson for the mill says all employees and contractors have been accounted for, following the completion of a full-site evacuation.

Emergency crews attendended the scene this morning after a 1000-litre sugar vat collapsed and collided with a second 1000l tank at about 9am.

Fire crews were reportedly unable to get into the area because of the heat of the mixture.

The 'mud' that spilt from the vats ran into an adjoining lab facility where nine staff members were working.

CSR sugar, which runs the mill, says it is still too early to say what impact the incident will have on the Burdekin crush, which began last week.

However, it appears likely that cane already delivered to the mill will be transported to other mills for crushing, while investigations and repairs are conducted at Pioneer.