Energy and chemicals group Sasol reports that construction of its coal destoning plant has been completed and that the facility, which should be ramped up to full production by December, is producing coal with a ‘sinks’ content (rock fragments or other impurities) of between 0% and 1.5%.

The brownfield project has involved a repurposing of the Twistdraai export coal plant and an investment of less than R1-billion.

It is part of the JSE-listed group’s strategy to address persistent coal quality problems that have negatively affected gasifier yields and caused mechanical damage.

Output at Sasol’s Secunda Operations, in Mpumalanga, has in turn been negatively affected, with the facility having produced 6.7-million tons in the year to June 30, 2025 – an outcome that was below targeted volumes of between 6.8-million and 7-million tons.

CEO Simon Baloyi told Engineering News in an interview that the 10-million-ton-a-year destoning plant would reduce the average sinks content of coal being used by the gasifiers to between 12% and 14% once material from the plant was blended with coal from Sasol’s own mines and that which it bought in from other miners.

It will also enable Sasol to reopen sections at certain mines that were closed owing to poor quality, and enable it to progressively decrease its purchases of third-party coal.

However, he said the group would continue to buy coal for quality, quantity and cost reasons and would be looking to replace volumes currently being purchased under a contract with Thungela Resources’ Isibonelo colliery with a similar long-term contract.

During its 2025 financial year, Sasol produced 28.2-million tons of coal, down from 30.2-million in the prior year, and made external purchases of 10-million tons (9.2-million tons).

The destoning plant would treat coal from Sasol’s Bosjesspruit and Thubelisha, where the sinks content was sometimes as high as 20%, before being blended to ensure that the average sinks content did not exceed the stated range.

The expectation is that the yields from the 74 gasifiers that Sasol typically operates at any one time will rise, while also improving the overall mechanical integrity of the gasifiers.

“In other words, the amount of gas that comes out of a gasifier will go up and we also expect an availability benefit, which you should see in the Secunda volumes, which is the true test for us,” Baloyi said.

Sasol is aiming to produce between 7-million and 7.2-million tons at Secunda in its 2026 financial year and is targeting to sustain output of about 7-million tons by 2030.

However, it has indicated that yearly volumes from its Secunda liquid fuels refinery, which has been fully impaired, will fall to 6.4-million tons from 2034 as natural gas from Mozambique is depleted.

GAS CLIFF?

The tapering of gas volumes from Mozambique will be felt far earlier by domestic gas customers, with Sasol having announced that supply will be halted in 2028; a stoppage that has come to be known as the ‘gas cliff’.

The 60 PJ of gas consumed domestically would represent between 10% and 15% of the yearly output from the gasifiers, Baloyi indicated.

He confirmed with Engineering News that Sasol remained committed to supplying domestic customers to 2030, but with methane-rich gas (MRG) produced by the Secunda gasifiers.

The price of MRG would be higher, however, and Sasol would seek to justify these prices in a future application to the National Energy Regulator of South Africa (Nersa).

Its submission to Nersa for the 2027 financial year would include MRG and the regulator would need to make a pricing determination.

He also insisted that MRG, which was being diverted from being used by Sasol internally to produce fuels and chemicals, had to be viewed as a bridging solution ahead of the importation of liquefied natural gas (LNG).

Sasol had already determined that it would be uneconomic to use LNG in its own production processes, but was a strong advocate of supplementing existing domestic demand with gas-to-power to anchor LNG imports.

However, Baloyi said that Sasol could consider buying LNG to produce higher-value products, such as wax at Sasolburg, once imports from Mozambique ended in 2034.

Other production facilities at the Free State complex would source feedstock from the Secunda gasifiers, or would be replaced by imports.