Soda Ash Sets the Margin. The Catalogue Sets the Volume.

The input that decides this market is not phosphate

Sodium tripolyphosphate is a phosphate salt, sold into detergent, made from phosphoric acid by anyone with a reaction vessel and an acid line. Its margin, in 2025, was decided almost entirely by the price of soda ash.

The stoichiometry is not a modelling choice. A tonne of STPP carries 0.5788 t of P₂O₅ and 0.7203 t of soda ash. At the 2025 assessments — acid at RMB 6,760, industrial soda ash at RMB 8,100 and RMB 1,250 respectively for the two inputs on a per-tonne-of-input basis — the cash cost builds like this:

Soda ash fell 18.19 per cent through 2025, from RMB 1,528 to RMB 1,250. On 0.7203 tonnes that was worth RMB 200 a tonne — 11.3 per cent of the entire gross spread — and it happened for reasons no phosphate miner had anything to do with: Chinese soda ash capacity additions and a soft glass market.

This is the only market in the phosphate segment where a commodity cycle outside phosphate sets the margin. It is also why the STPP producers who had a good 2025 may not know why they did.

The tonnage is falling by statute, not by substitution

Chinese STPP output went from 777 kt in 2020 to 463 kt in 2024 — a 12.14 per cent annual decline. Capacity fell 13.90 per cent in 2024 alone. That is not a demand curve. That is an administrative one: NDRC’s 2024 industrial catalogue lists sodium tripolyphosphate as a restricted product and requires elimination of single lines below 10 kt a year.

Which produces the odd structure this market now has. Output in 2025, built from the balance rather than forecast — domestic apparent consumption of 253.0 kt, exports of 222.0 kt, imports of 1.5 kt, giving output of 473.5 kt and 44.5 per cent utilisation on 1,065 kt of capacity. Exports are 46.88 per cent of national output, going to Brazil, Thailand, the Philippines, Mexico, Indonesia, India, the Dominican Republic, Spain, Vietnam and the United States — jurisdictions that have not done what Europe did. Export realisation fell from USD 1,040 in the first eight months to USD 807.56 in December.

The exposure is arithmetic, not speculation. Domestic consumption of 253 kt is more than half detergent. A Chinese detergent-phosphate restriction of the European kind removes 126.5 kt — 26.72 per cent of national output — into a market whose only growth outlet is an export price that fell 22 per cent inside twelve months.

Europe kept the salt and lost the element

The standard explanation for Europe’s absence from this market is the detergent ban. The primary record is better than that.

In its own anti-dumping assessment, the European Commission recorded that Thermphos International BV was “the only producer of white phosphorus in the Union, representing the total Union production”. The company filed for bankruptcy, and the Breda District Court ordered its liquidation on 21 November 2012. Union production of the element stopped. The Commission’s own assessment now puts EU tripolyphosphate production at under 10 per cent of world output.

Europe kept the salt and lost the element. That is a materially different story from a consumer-products regulation, and it explains why the European detergent industry now imports a product that its own regulation would permit it to make: the upstream furnace went first, and nothing downstream survives a missing element.

Everything left of value is grade, not tonne

Industrial STPP sells at RMB 8,000–8,800. Food grade sells at RMB 11,200–12,200. That is a 44.4 per cent premium for a specification with identical phosphorus content.

It is the entire growth story. Value compounds 6.21 times faster than volume in this market — the widest gap in the segment — because volume is capped by catalogue and price is falling. Every increment available is a qualification file, not a reactor.

Which lands the segment’s cleanest cross-market comparison, on contained phosphorus:

The salt is the last product in the chain still priced as a chemical rather than a service — and the only one whose margin can be moved by a glass factory in another province going quiet. Read the table downwards and the segment’s logic is obvious: the further the phosphorus travels from the furnace, the less of the price the phosphorus is, and the more of it is the specification the customer is buying.