Sulfur Has Halved From Its Peak — What It Means for STPP, SHMP and Phosphoric Acid Prices
Sulfur is the raw material behind sulfuric acid, and sulfuric acid is behind most wet-process phosphoric acid — which in turn sets the cost floor for sodium tripolyphosphate (STPP), sodium hexametaphosphate (SHMP) and phosphoric acid 85%. Earlier this year, record sulfur prices pushed that floor sharply higher. That story has now reversed, fast.
China's sulfur benchmark fell 30.6% in October alone, from RMB 7,702/ton to RMB 5,344/ton, and sits around RMB 5,300 in early November. Against the June peak above RMB 11,000/ton, sulfur prices have halved in four months.
What Changed in the Sulfur Market
The missing cargoes arrived. Delayed shipments reached Chinese ports in concentration, and port inventories rebuilt from the decade low of 800,000–900,000 tons in July to about 1.11 million tons by early November.
Demand paused. The autumn fertilizer season ended before winter stocking began, phosphate fertilizer operating rates dropped — monoammonium phosphate utilization was reported below 40% in late October — and holders cut prices to move stock.
How Sulfur Feeds Into Phosphate Prices
Most STPP, SHMP and TSPP produced in China starts from wet-process phosphoric acid, which is made by reacting phosphate rock with sulfuric acid. When sulfur falls, acid costs fall with it, and phosphate salt offers follow — usually with a lag of several weeks while producers work through raw materials bought at higher prices. The exception is the thermal route: phosphoric acid made from yellow phosphorus does not depend on sulfur, and yellow phosphorus prices are holding firm at RMB 28,233/ton into November, with dry-season electricity tariffs rising and producers cutting operating loads.
What It Means for STPP, SHMP and Phosphoric Acid Prices
STPP (sodium tripolyphosphate). Detergent-grade STPP is produced from wet-process acid, so its cost base is now genuinely lower than in the summer. Expect STPP offers to soften gradually rather than drop in one step, as producers clear acid and sulfur bought near the peak.
SHMP (sodium hexametaphosphate). SHMP pricing depends on which acid route the producer uses. Wet-route material should follow the same softening path as STPP; SHMP made from thermal-process acid — common for higher-specification grades — sees little cost relief, because yellow phosphorus has not fallen. Two SHMP offers can therefore move in different directions this quarter.
Phosphoric acid 85%. Merchant phosphoric acid follows sulfur most directly, and prices are already easing. In our earlier update on why phosphoric acid prices were rising, the driver was the same sulfur chain — now running in reverse.
Why Phosphate Prices Will Not Fall as Fast as Sulfur
Domestic sulfur is now below import cost. Qatar's November contract price is FOB USD 735/ton and Kuwait's USD 720/ton — both cut by USD 100 for November — yet their landed cost in China still works out well above RMB 6,400/ton, against domestic spot near RMB 5,000–5,300. Imports are effectively frozen at that inversion, and port stocks, even after rebuilding, remain more than 50% below last year. Early November already brought firmer auctions in Shandong and buyers returning at Zhenjiang Port around RMB 4,800/ton.
The structural tightness has not gone away. Russia's sulfur export ban runs to the end of 2026, global export supply this year is estimated some 30% lower, and winter fertilizer stocking is still ahead.
Our Read for Phosphate Buyers
Budget for a partial pass-through, not a collapse: STPP, SHMP and phosphoric acid offers should soften with a lag, unevenly by product and production route. Cover Q4/Q1 requirements in tranches, and treat very cheap spot sulfur as a signal to lock in some volume rather than a new normal.
Theone Chemical supplies technical grade phosphates — STPP, SHMP, TSPP and phosphoric acid — from China's leading producers and our own partner bases, and follows this market daily. Contact us for current prices against your specification.