Sulfur shortage due to tensions in the Middle East can be relieved by recovering coal waste

Since the war between US/Israel and Iran broke out at the end of February, world oil trade has been under pressure. This is due to the effective closure of the Strait of Hormuz, a narrow waterway through which around 20% of the world’s oil production must travel to reach its destination. The economic impacts of the world-wide reduction in available fuel and the associated increase in fuel prices are well-understood. 

An impact that is perhaps less well-understood is that of reduction in the availability of elemental sulfur. Elemental sulfur is a by-product of oil production and is converted to sulfuric acid before being used in copper and nickel refining or to produce fertilizers. The situation is so serious that China has banned the export of sulfuric acid from May[1]. In South Africa, sulfuric acid consumption is estimated at 11 Mtpa, of which around 7 Mtpa is produced by burning sulfur[2]. A reduction in available sulfur and increase in sulfur price has the potential to place South Africa’s agricultural and mining industries, amongst others, under severe pressure. 

This, however, does not need to be the complete picture. South Africa has ample reserves of coal, which tends to contain both organic sulfur and mineral sulfur in the form of pyrite. Pyrite is important to note, because it can be roasted to produce sulfuric acid. The pyrite component in coal is rejected with the coal waste during processing and can be effectively separated from the rest of the waste material[3], although this is not currently standard practice. This means that there is a real opportunity for South Africa to start roasting coal-derived pyrite to replace some of the sulfur currently being imported. In fact, a recent study conducted at the University of Cape Town has found that up to 0.8 Mtpa of sulfuric acid can be produced from the current arisings of coal waste[4]. More can naturally be produced if we also start reprocessing coal waste facilities to recover pyrite. It is therefore well within reach for South Africa to increase its sulfuric acid production with 1.4 Mtpa by burning coal-derived pyrite and make up for the estimated shortfall created by tensions in the Middle East. 

There are other advantages of taking this approach as well, since pyrite is the mineral responsible for generating acid mine drainage, a naturally-occurring process that takes place in mine waste and mine cavities. Acid mine drainage threatens the water quality of the Upper Olifants River catchment and thereby the livelihoods of countless communities and farmers as well as the water quality of the Kruger National Park[5]. Pyrite oxidation is also an important heat source in the processes that cause spontaneous combustion on coal waste heaps, which contributes to air pollution in Mpumalanga[6]. Along with reducing the environmental risks associated with coal mine waste, the additional separation step also creates the opportunity to recover coal from the waste as well as recover a relatively benign waste stream that can be used in applications ranging from producing aggregate for construction to producing soils for mine rehabilitation[7].

Recovering pyrite from coal waste to produce sulfuric acid can alleviate some of the economic impacts of tensions in the Middle East, can reduce the environmental impacts associated with coal mining, and can provide additional economic opportunities. This geopolitical moment is an opportunity for the industry to demonstrate its value both to South Africa and the world at large. 

 In the press...