pillar method of mining with a continuous miner. Sasol successfully used the longwall mining method from 1967 to 1987. Today, Sasol is one of the leaders in coal-mining technology and was the first to develop in-seam drilling from surface using a directional drilling methodology. This has been developed into an effective exploration tool. Working with Fifth Dimension, Sasol developed a virtual reality technology to help train continuous miner operators in a 3D environment in which various scenarios can be simulated, including sound, dust and other signs of movement. This has recently been expanded to include shuttle car, roof-bolting, and load-haul dumper simulators. Fischer–Tropsch reactor technology The initial reactors from Kellogg and Lurgi gasifiers were tricky and expensive to operate. The original reactor design in 1955 was a circulating fluidised bed reactor (CFBR) with a capacity of about 1,500 barrels per day. Sasol improved these reactors to eventually yield about 6,500 barrels per day. The CFBR design involves moving the whole catalyst bed around the reactor, which is energy intensive and not efficient as most of the catalyst is not in the reaction zone. Sasol then developed fixed fluidized bed (FFB) reactors in which the catalyst particles were held in a fixed reaction zone. This resulted in a significant increase in reactor capacities. For example, the first FFB reactors commercialised in 1990 (5 m diameter) had a capacity of about 3,000 barrels per day, while the design in 2000 (10.7m diameter) had a capacity of 20,000 barrels per day. Further advancements in reactor engineering have resulted on the development and commercialisation of Sasol Slurry Phase Distillate (SSPD) reactors which are the cornerstone of Sasol's first of a kind GTL plant in Qatar. From fuels to chemicals The fuel price is directly linked to the oil price, so is subject to potentially large fluctuations. With Sasol only producing fuels, this meant that its profitability was largely governed by external macroeconomic forces over which it had no control. How could Sasol be less susceptible to the oil price? The answer was right in front of them, in the treasure chest of chemicals co-produced in the Fischer–Tropsch process. Chemicals have a higher value per ton of product than fuels. In the 1960s ammonia, styrene, and butadiene became the first chemical intermediates sold by Sasol. The ammonia was then used to make fertilizers. By 1964, Sasol was a major player in the nitrogenous fertilizer market.