Remote sensing for remediation
Legacy mercury tailings, found from orbit and ranked for cleanup.
Caelo uses Sentinel-2 satellite imagery and machine learning to locate the abandoned tailings ponds left by artisanal gold mining, so governments, operators and remediation teams know where to act first. With our partner AuroClear, the gold left in those sites pays for the cleanup.
The problem
Decades of mercury, with no map of where it sits
2,000+ t
of mercury released every year by artisanal and small-scale gold mining
80+
countries where up to 20 million artisanal miners work
100M
people directly or indirectly exposed to mercury from the sector
Much of that mercury stays behind in tailings ponds after mining moves on. In water and wet sediment it can turn into methylmercury, which builds up through the food web and reaches communities that rely on fish.
It doesn’t go away on its own. Studies in French Guiana, Australia and California find amalgamation mercury still in soils and sediments 60 to 150 years after mining ended, and mining ponds in the Peruvian Amazon convert mercury to methylmercury five to seven times faster than rivers.
Remediation money is limited, and nobody can prioritize sites that haven’t been found. Caelo builds that inventory.
Sources: UNEP planetGOLD programme; Guédron et al. 2011, Water Research; Schneider et al., Environmental Pollution; USGS; Gerson et al. 2020, Science Advances
Approach
Three passes over every scene
- Pass 1
Detect
Multispectral Sentinel-2 imagery is screened for the surface signatures of mine tailings, at 10 m resolution, across whole districts at once.
- Pass 2
Filter
Sentinel-1 radar, time-series data and terrain (elevation and slope) separate standing ponds from rivers, wet ground and recently disturbed land, so only quiet legacy sites stay on the list.
- Pass 3
Rank
Candidates are ordered for field characterization and remediation, giving planners a short list instead of a whole map.
Evidence
Tested on ground truth, then in the field
Predictions are written down before field data is collected, so results can’t be tuned after the fact.
0.87
Proof of concept, Canada
F1 score on labelled historic tailings in Nova Scotia, with every test site held out of training. Published benchmarks sit near 0.7.
2
Districts scanned, Guyana
Applied under dense rainforest canopy and persistent cloud, the hardest conditions for optical satellite work.
17
Field-validation samples
GPS-logged and laboratory-assayed, collected in November 2026 with a university partner in Guyana. Results due January 2027.
How we work
Built for cleanup, not policing
Remediation first
Caelo maps legacy contamination to direct cleanup. It is not a surveillance or enforcement product.
Claims we can defend
Outputs indicate likely tailings and conditions that favour mercury transport. They never claim measured concentrations.
Predictions on record
Expected results are fixed before validation data is examined, and negative results are reported too.
Local expertise at the centre
Field work is done with in-country geologists and institutions, and environmental findings are shared with the communities where samples are taken.
Roadmap
One platform, more of the tailings problem
Detection and ranking are what Caelo has validated today. The same satellites and pipeline extend naturally to the rest of the tailings lifecycle, and every new layer stays inside the remediation mandate.
Remediation verification
Tracking revegetation, surface water and ground stability on treated sites over time, to show that a cleanup held. Relevant wherever closure has to be certified, including orphaned mines in Canada.
Downstream water
Mapping sediment plumes and turbidity below legacy ponds, to flag where tailings may be reaching rivers and the communities that depend on them.
Tailings stability
InSAR ground-movement monitoring for the small artisanal ponds that no one watches today.
Critical minerals
Extending detection to artisanal cobalt and lithium workings.
Industry challenges
How we answer the sector’s pressures
Water and tailings
Legacy ponds are found, reprocessed and reclaimed, with process water reused on site rather than discharged.
Safety
No open burning of amalgam, the largest source of miners’ mercury-vapour exposure. Legacy mercury is captured in a closed retort, and remote screening means fewer field trips into difficult terrain.
Digitalization and AI
Satellite imagery and machine learning replace district-wide field reconnaissance.
Sustainability
Gold-funded cleanup, progressive reclamation to a background-referenced endpoint, and a 5% community commitment.
Community health
Removing legacy mercury cuts the path from tailings ponds into fish and the riverside communities that rely on them.
Critical minerals
On the roadmap: extending detection to artisanal cobalt and lithium workings.
Business model · partner company
A cleanup that pays for itself
AuroClear Technologies Inc. reprocesses legacy tailings without mercury. The gold left behind by mercury mining pays to remove the mercury and reclaim the ground, so remediation is funded by what it recovers, not by grants alone. Its first pilot plant is planned for Guyana in 2027.
Pre-optimized feedstock. Caelo selects the ground from orbit, and a proprietary pre-conditioning step prepares clay-rich pond sediment before it reaches proven gravity equipment.
AuroClear is committed to writing a 5% community commitment into its corporate articles.
- CaeloFinds and ranks legacy tailings from satellite imagery
- CharacterizeField sampling confirms the site and measures mercury
- AuroClearMercury-free gravity reprocessing recovers residual gold
- RemediateMercury in processed material is captured, not released
- ReclaimGround is regraded and revegetated as work progresses
- VerifyCaelo will confirm from orbit that the cleanup held (planned, 2027)
Who it serves
Anyone responsible for a legacy site
The same detect-and-prioritize problem exists wherever mercury amalgamation was used, from South America to Africa, the Philippines and beyond, and at orphaned and abandoned mines in Canada.
Governments
Site inventories for national mercury action plans under the Minamata Convention
Mining operators
Legacy liabilities mapped across concessions and closure areas
NGOs and funders
Evidence to target remediation programmes where they matter most
Researchers
Field-validated detections for environmental and public-health studies
Contact
Talk to us about a pilot
George McDonald, Founder. Kitchener-Waterloo, Ontario, Canada.
george@caelotechnologies.ca