Soil thermal desorption is a remediation process that heats contaminated soil to a controlled temperature to vaporise organic contaminants without necessarily combusting them, after which the resulting off-gas is captured and treated separately. Across the 62 records in this dataset, the dominant framing pairs a desorption chamber with a dedicated off-gas or tail-gas treatment stage, which the two most-cited filings in the corpus both implement. Desorption temperature, residence time and moisture content are the process variables that recur most often in the underlying search criteria, and they are the parameters most patents claim control over.

The assignee ranking in this dataset covers 41 companies, counted in records, with the leading assignee holding 17 records and a long tail of single- or few-filing entrants beyond that. This is not a top-50 or top-100 list; it is the full ranking the dataset returns, and it is dominated by Chinese research institutes and environmental-technology firms, alongside international filers such as Haemers Technologies. Concentration cannot be reliably stated as a percentage from this evidence because the ranking and the total record count are measured in different units, so it is best read as showing a clear leader plus a broad field of smaller filers rather than a precise market share.

Filing activity peaked at 11 records in 2019 and, over the most recent complete span from 2021 to 2024, moved from 5 to 4 filings, a -20% change. Because patent publication lags filing by roughly 18 months, the 2025 and 2026 figures in the trend are necessarily incomplete and should not be read as evidence of a slowdown. The safest reading is that filing activity has moderated from its 2019 peak but the true current-year rate will not be visible until later publications catch up.

The classification spread shows most claim density concentrated in the core B09C soil-reclamation class, present in 95.2% of the 62 records, while supporting process classes are thinner: B01F mixing and stirring appears in only 3.2% of records, and B02C crushing/grinding and B08B cleaning each sit at 6.5%. These lower-density classes point to under-claimed territory around soil pre-conditioning, particle-size control ahead of the desorption chamber, and equipment cleaning cycles, rather than the desorption process itself, which is already densely claimed.

Off-gas treatment is a defining feature of the highest-cited filings in this dataset rather than an optional add-on: both CN105032913A and CN108714621A, the two most-cited records, integrate a desorption unit with downstream exhaust treatment in the same claim set. Dioxin formation and off-gas treatment were part of the search criteria used to build this dataset, reflecting their regulatory importance whenever organic contaminants are thermally treated. Filers looking to enter this space should expect that a standalone desorption claim without an integrated off-gas or emissions-control element is filing into already well-covered ground.