Coal prices have been driven to record highs by increased gas-to-coal switching especially after Russia, a major gas supplier to Europe, invaded Ukraine in February.
Thungela reported on Monday headline earnings per share (HEPS) - the main profit measure in South Africa - of 67.23 rand for the six months to June 30, up from 3.05 rand a year earlier.
The company, which was spun off from global mining giant Anglo American Plc in June 2021, said it would return 8.2 billion rand to shareholders after declaring a dividend of 60 rand per share.
Its shares were 6.38% up by 0745 GMT.
The coal exporter however said it could not fully take advantage of the elevated prices as it had to curtail production due to the state-owned rail utility Transnet's limited capacity to haul the mineral to ports.
As a result of the rail woes, Thungela has revised its production guidance for 2022 to between 13 and 13.6 million tonnes, from the previous 14-15 million range. The company is exploring the possibility of using trucks to haul coal to port.
Thungela expects its full-year unit costs to be higher than previously expected, partly due to lower production. It now expects unit costs to be between 885-915 rand, from the previous forecast of 850-870 rand.
($1 = 16.2954 rand)
(Reporting by Nelson Banya; editing by Jason Neely and Emelia Sithole-Matarise)