He was flown by air ambulance to Newcastle Hospital, which has a specialist burns unit, following the incident where he was still receiving treatment the following day.
A spokesperson for Boulby Mine said: “An employee of a contractor carrying out electrical maintenance work at the ICL UK Boulby site was involved in an incident which resulted in him suffering significant burns.”
He added that the healthy and safety executive had been made aware of the incident.
It is the second time in less than two months that the government department has been drafted in to investigate incidents at the troubled plant.
In the early hours of Friday June 17, 56-year-old mine worker John Anderson was killed while working underground.
A gas blast occurred in the area he was working causing displacement of minerals and debris.
It adds to the back catalogue of incidents at the mine.
Two months prior, in April this year, seven miners were rescued by the underground mine rescue unit after a fire broke out. It was started in supposedly fire retardant polystyrene blocks used to circulate air around the mine.
In 2014 the Mines Inspectorate were called in after a serious roof collapse underground and in November last year a huge re-structuring of operations was announced along with the loss of 350 jobs due to a reduction in the level of economically feasible potash reserves.