Sulphuric acid: Cycles

From near-zero to several times higher in months

Acid prices are among the most volatile in chemicals because a large part of supply is a by-product and acid is costly to store and ship. When sulphur is cheap and smelters run hard, acid can trade near zero or negative at the smelter gate. When sulphur spikes or smelters cut output, delivered acid in Chile or Brazil can multiply several times in months. The floor is the cost of neutralising smelter acid; the ceiling is the price at which leach mines and fertiliser plants cut output. Spikes came in 2008, 2021-22 and 2026; CRU expected the 2026 episode to exceed both earlier peaks.

A burner's margin is the acid price less a third of the sulphur price and about $15-25/t conversion cost (indicative). At US Gulf acid of $400/t and sulphur of $1,060/t FOB US Gulf (May 2026, Platts) the spread was about $50/t; smelter acid captured almost all of the $400/t.

Booms and busts

1. 2007-2009

   Chinese phosphate demand and a sulphur spike tightened acid, then the financial crisis and stockpiles collapsed both.

   Sulphur rose from $45/t (Jan 2007) to over $700/t in 2008 and fell to $50/t by Q2 2009 (Hydrocarbon Engineering, via sulfur tile); acid price peak not found in sources used

2. 2021-2022

   Post-Covid fertiliser demand, smelter outages and the Russia-Ukraine war tightened sulphur and acid markets; prices fell back in 2023.

   US sulphur average $90.40/t (2021) to $177.80/t (2022) and $46.42/t (2024) (USGS); CRU names 2022 as the previous acid peak

3. 2025-2026

   Shipping through Hormuz largely stopped after the Iran war began on 28 Feb 2026, stranding Gulf sulphur, and China suspended acid exports from May 2026. Chile, Indonesia and Saudi Arabia lost supply; Huayou cut Indonesian HPAL output by about 50%.

   Delivered Chile $175/t (late Dec 2025) to $270/t (mid-Apr 2026) (CRU); CFR Mejillones $380/t (15 Apr 2026, Platts); CFR US Gulf $155/t to $400/t (Feb-May 2026, Platts); China domestic $161/t to $214/t (Feb-Mar 2026, CRU)

What drives the cycle

• Sulphur price. Sets the cost of about two-thirds of supply; sulphur depends on Gulf gas and refinery runs and on shipping through Hormuz.
• Smelter output and outages. Copper and zinc smelter cuts or maintenance remove by-product acid that cannot be replaced quickly; Chinese smelter policy matters most.
• Copper leach and nickel HPAL demand. Chile, the DRC and Indonesia need acid at remote sites; HPAL acid use rose from 3.5 Mt (2021) to 16 Mt (2025).
• Phosphate fertiliser margins. Fertiliser plants are the base load; when DAP margins collapse, burners cut runs and acid demand falls.
• Chinese export policy. China moved from quota (700 kt in Jan-Apr 2026) to a near-full ban, removing about 2.8 Mt of 2026 trade.

Metrics to track