SULFUR

Mining sulfur using Frasch technology has ended. The last mine in Poland is said to be operating, but economics contradict that notice. The Mishraq Mine in Iraq has minuscule production of very-highcarbon sulfur. It was to have been rehabilitated, and sulfur purification technology added, five years ago. However, establishment of the ISIS Califate left the task undone and equipment scattered in the Iraqi desert. Sulfur recovered from refineries, having grown dramatically due to clean-air mandates, is now generally declining (except in China and the Arab Gulf). The development of electric transport should eventually temper that growth. Sulfur extracted from the purification of natural gas, on the other hand, will continue to rise as a source of “blue” energy. Production increases are presently located in China and West Asia, including the Arab Gulf. The area, led by Saudi Arabia and Abu Dhabi, just displaced North America as the locus of global production. Revamping logistics and the present molten sulfur infrastructure is the principal challenge confronting suppliers and consumers. U.S. consumers are facing the most challenges to transform infrastructure to enable imports of solid sulfur for melting. That challenge is particularly severe in California, Nevada and northwest Mexico, where extraction and processing of lithium, copper and other elements are growing. Decline in mined sulfur output Commercial mining of sulfur began to decline in the early 1980s as global environmental regulation focused on eliminating atmospheric sulfur emissions. Motor fuels became a primary target, lowering almost all fuels to a 15 parts per million (ppm) sulfur content 40 years later. U.S. statistics best illustrate the point due to its large output of Frasch-mined sulfur and numerous competing oil refineries. Prior to the Clean Air Act, offroad equipment and rail locomotive fuels contained at least 3 percent (30,000 ppm) sulfur. Fuel oils and marine bunkers reached as much as 6 percent (60,000 ppm). Table 1 illustrates the transformative impact of fuels desulfurization: a six-fold increase from 1970 to 2017’s peak output of sulfur from refinery and gas output of 9.1 mt, leading to Frasch sulfur mining’s demise in 2001. A drop in refinery production from 2017 to 2019 is linked to the sweet/sour crude price relation. The differential between sour (with high carbon dioxide (CO2) and hydrogen sulfide (H2S) content) and sweet crudes delivered to U.S. refineries narrowed to the point where sweet crudes were preferred even by refineries technically specialized in processing “sour” feedstocks. Collapsing bituminous crude oil prices in Canada led the Alberta Energy Regulator Control Board to mandate production curtailments at oil sands operations in the province hoping (in vain) to raise the price of the “Alberta Select” crude oil grade and posted-price-associated bitumen feedstocks. Evaluating market and logistical conditions that led to sulfur production’s 2019 decline, we believe 600 kt of the 1.1 Mt drop represents a permanent drop linked to using “sweeter” feedstocks. The drop in 2020 is directly attributable to the COVID-19 pandemic, which was followed by a late 2021-2022s slight recovery. This trend is expected to continue toward what may become a “new normal” sulfur production of 8.7 t/y. Comparing U.S. performance to the U.S. Geological Survey’s global data (USGS Mineral Commodity Summaries for specific years) shows interesting trends: World sulfur output in all forms rose almost 29 t (57 percent) from 1994 to 2020.That growth was driven by dramatic increases of 15.5 t in West Asia that more than offset the U.S. and Canadian drop of 7.9 t (38 percent) in the period. Table 1 U.S. sulfur production, 1970–2022, in million metric tons (U.S. Geological Survey, Con-Sul-2022e). The sole Frasch mine in the world might still operate at Osiek, in Poland. However, given the reduction in Russian natural-lgas exports and resultant increase in European energy prices, we find this implausible. If production at Osiek has ceased, resuming production may be technically and economically impractical. This is due to Frasch mining requiring heating of the limestone-containing crystalline sulfur formation to a temperature that only slightly exceeds the melting point of sulfur, once liquefied sulfur percolates down to a point where a double annulus collection well(s) has been drilled. Extraction utilizes compressed air injected down one annulus to lift molten sulfur up the other. If the formation cools for lack of superheated water injection, molten sulfur will solidify in the limestone’s pores, effectively preventing hot water/steam from repenetrating that portion of the deposit. Further, this will lead to overheating certain areas being revitalized, and overheated sulfur becomes increasingly viscous to the point of immobility. Allowing a formation to cool prior to full sulfur extraction is always avoided. Supply outlook The USGS’ evaluation of world resources is that resources of elemental sulfur in evaporite and volcanic deposits, and sulfur associated with natural gas, petroleum, tar sands and metal sulfides total about 5 billion t. The sulfur in gypsum and anhydrite is almost limitless, and 600 billion t of sulfur is contained in coal, oil shale and shale that is rich in organic matter. Production from these sources would require the development of low-cost methods of extraction. The domestic sulfur resource is about one-fifth of the world total. North American challenge Following the demise, and dominance, of a domestic Frasch mining industry, North America has been affected by several wild price swings. These developed as a consequence of consumer angst regarding immediately available supply, which Frasch companies tended to mitigate 20 years ago with extensive operating inventories of sulfur and careful contracts. Price swings are expected to continue over the next five to 10 years as significant supply infrastructure is developed to meet new Western demand, reductions in phosphate fertilizer output and refinery sulfur output, and changing ownership of logistical assets. While the mining of sulfur has ceased, the large demand fluctuations, inventory management issues and logistics common to that activity remain. Table 2 World production of sulfur, 1994–2020.* All forms (elemental and H2SO4 in S equivalent, million metric tons/year – Mt/y).

SULFUR

Authored by:
Gerard D'Aquin

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