Sulfur

An unwanted by-product of cleaning oil and gas that becomes sulfuric acid, the workhorse chemical behind phosphate fertiliser and metal leaching.

Fertilisers · No. 5

• Not on a critical list
• HHI 935 · unconcentrated

Almost no sulfur is mined any more: it is the waste scrubbed out of oil and gas, and the world needs it.

Chart: Illustration: Sulfur

Where it comes from

Chart: Map of where it comes from

Refineries and gas plants strip hydrogen sulfide from sour oil and gas to meet fuel rules, then turn it into elemental sulfur. Smelters capture sulfur dioxide and make acid directly.

Three things to know

1. Morocco bought 31% of the world's imported sulfur by value in 2024, to turn its phosphate rock into fertiliser.
2. Gypsum holds an almost limitless amount of sulfur, but nobody has a cheap way to extract it.
3. Each year refineries and chemical plants reclaim 2.5 to 5 million tons of spent sulfuric acid.

The journey

1. 1 Sour oil, gasPlus sulfide ores at metal smelters
2. 2 DesulfurisationHydrogen sulfide stripped at refineries, plants
3. 3 Claus processConverted to bright yellow elemental sulfur
4. 4 ShippingMolten, prilled or granulated in bulk
5. 5 Sulfuric acidBurned near users to make acid
6. 6 End usesPhosphate fertiliser, metal leaching, chemicals

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