As the cane crushing season gets underway, CSR on Friday closed the operation south of Townsville as three people were taken to hospital.
A low pressure explosion in a 1,000 litre juice clarifier tank caused it to collapse and push over a second tank at around 0900 AEST on Friday, spilling sugar fat.
CSR will investigate the incident after sending most of the mill staff home.
"While it is too early to estimate when production can re-commence, CSR believes this incident will not have a material effect on earnings in its sugar business," it said.
"CSR is working to restore production as soon as possible at Pioneer mill," it said.
CSR shares fell five cents to $2.52 on Friday.
CSR's sugar business is its third biggest division behind building products and aluminium.
In the group's last fiscal year, sugar underlying earnings fell 45 per cent to $71.7 million as raw sugar prices declined and wet weather delayed the start of the crushing season.
This year's season began a few days ago and is due to run until November.
Canegrowers chairman Alf Cristaudo said it was too early to tell if the mill closure would affect the crushing season.
"If it is going to be a couple of days then that won't matter too much, but if it turns out to be a week or two, then it will impact," Cristaudo said.
The Pioneer mill is one of four mills owned by CSR in the Burdekin area and crushes around 1.7 million tonnes of sugar cane annually.
CSR plans to divert cane from the mill area to its other three mills.
CSR crushes 14 million tonnes of sugar cane a year in seven mills.
Source: AAP NewsWire