Solvay: EPO upholds unitary soda-ash purge-stream recycling patent

EPO decision

The European Patent Office has upheld Solvay’s European patent EP 3 971 138 B1 following opposition proceedings filed by WE Soda Ltd on 13 February 2025. The decision, issued after oral hearings on 19 May 2026, maintains the patent’s validity subject only to limited amendments and may be subject to appeal.

Patent scope

EP ’138, granted in May 2024, protects Solvay’s process for treating and recycling purge streams generated during sodium carbonate (soda ash) and sodium bicarbonate production. The patent also covers a process for manufacturing sodium carbonate and sodium bicarbonate that includes the recycling process, as well as the products directly obtained from that process.

Related litigation

EP ’138 is part of a patent family that includes EP 2 878 579 B1 (EP ’579), currently the subject of separate litigation between Solvay and WE Soda. Solvay initiated patent infringement proceedings in the Netherlands in August 2021 against WE Soda and affiliates based on the Dutch designation of EP ’579. On 3 December 2025 the Dutch court upheld EP ’579 and granted an injunction requiring the defendants to halt import and supply of the contested products to the Netherlands; WE Soda and the relevant entities have appealed.

Unitary patent and enforcement

EP ’138 is a unitary patent. Infringement actions before the Unitary Patent Court based on unitary patents can be pursued in a single action covering at least 18 countries, with the possibility of obtaining an injunction to stop imports of infringing products.