Slag Engineering Patents: Who Leads, Where the Gaps Are 2026
Slag Engineering in Steelmaking: Patents Behind Dephosphorization, Basicity Control and Refractory Protection
53.4% of all 640 records sit with just five assignees — filing here means competing directly against entrenched claim positions, not carving out open ground. Filings peaked at 43 in 2018, cooled through the early 2020s, then rose 13% from 8 in 2021 to 9 in 2024 — the last year the dataset treats as complete. 2025 and 2026 counts (down to 1 by 2026) reflect publication lag, not a retreat from the technology.
- 1JFE STEEL CORP110
- 2NIPPON STEEL CORPORATION101
- 3NU IRON TECHNOLOGY LLC73
- 4SUMITOMO METAL IND LTD32
- 5NIHON JIRIYOKU SENKOU26
See the full slag engineering in steelmaking analysis in Eureka
- The complete ranking, not just the top five
- Every IPC branch with its share of the corpus
- The most-cited records, and where claim space is still thin
Common questions on slag engineering patents
Who holds the most patents in steelmaking slag engineering?
The assignee ranking in this dataset is led by a single company with 110 of the 640 records in scope, well ahead of the fifth-ranked assignee at 26. The top five assignees combined account for 53.4% of all 640 records, and the top ten for 67.0%, so the field is concentrated rather than fragmented. Japanese steelmakers and their corporate successors appear repeatedly in the ranking, reflecting decades of continuous filing on dephosphorization and basicity control.
Is patent filing activity in slag engineering growing or shrinking?
Filing peaked in 2018 at 43 records and declined afterward, but the picture from 2021 to 2024 shows a 13% increase, from 8 to 9 filings. Counts for 2025 and 2026 appear lower, but that reflects the roughly 18-month lag between filing and publication rather than a real drop in activity. Treat 2024 as the most recent year with a complete picture and expect the 2025-2026 figures to rise as more applications publish.
What is slag basicity and why does it attract patent activity?
Slag basicity is the ratio of basic oxides (like CaO) to acidic oxides (like SiO2) in furnace slag, and it governs how effectively a heat removes phosphorus and sulfur while protecting refractory linings from chemical attack. Because basicity control interacts with dephosphorization, magnesia saturation and refractory wear simultaneously, it sits at the centre of the C21C steelmaking subclass, which covers 52.7% of the 640 records in this dataset. Patent activity clusters here because small changes in basicity targets translate directly into measurable yield and refractory-life gains, making the claims commercially valuable to defend.
Disclaimer. This analysis is based on Patsnap Eureka data drawn from a limited snapshot of global patent records and is provided for general information and reference only. Patent data carries inherent limitations — recent filings are under-counted because of publication lag, counts may be on a record or family basis, classification and applicant-name data may contain errors or duplicates, and the underlying search query defines the scope shown — so the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing here is an exhaustive prior-art, novelty, freedom-to-operate or validity search, nor does it constitute legal, financial or professional advice, and it should not be relied upon as such. Verify independently and review with qualified patent and legal professionals before acting on it.
Method: Filing trend and technology composition. Derived from a Patsnap search on Slag Engineering in Steelmaking covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish. Every share divides by all records in scope. Data: Patsnap Eureka. See the full landscape report.