Almost every pharmaceutical, fine chemistry, fertiliser or refining plant has a cabinet, a container or a yard of industrial filters waiting for disposal. Cartridges, mats, screens, baghouse elements, fixed-bed filter media, molecular sieves, spent activated carbon. Material classified as waste, usually under an active licensed disposal contract, with no prior recoverable-value assay.
In several cases this material is carrying palladium, platinum, rhodium or ruthenium in a commercially relevant amount. In other cases it is not. Knowing which scenario yours is costs little — not knowing costs whatever was there.
Filter types that often retain PGM
Filters after Pd/C, Pt/C, Ru/C, Rh/C hydrogenation
In pharma and fine chemistry, selective hydrogenation uses fine metal catalyst dispersed on activated carbon. The catalyst is separated from the reaction by press-filtration. The recovered solid — cake — concentrates virtually all the PGM of the batch. Even the disposable filter used at this stage can retain meaningful grade.
Pt/Rh gauzes in ammonia oxidation
Nitric acid production uses woven Pt/Rh alloy gauzes as oxidation catalyst. Gauzes age, lose tension, shed particles. That material goes to downstream capture — collectors, mats, baghouse. The old gauze itself has declared catalogue value at the manufacturer; what often goes to disposal is what came off it.
Dust collection and particulate
Reforming, isomerisation and operations with moving-bed catalyst drag fines. Those fines end up in cyclones, baghouse filters and condensers. In many lots the collected dust carries metal — at low concentration per unit mass, but in relevant aggregate volume.
Purification activated carbon
Purification operations using activated carbon to remove organic contaminants can retain metals as a by-product. When the spent carbon comes from a process with PGM somewhere upstream, it is worth assaying before disposal.
Molecular sieves and adsorbents
Silica, alumina, molecular sieves, ion-exchange resin can adsorb metal in certain processes. Not a rule; case by case. Simple analysis allows separating positive lots from those going to normal disposal.
Why this typically goes unnoticed
- Correct operational focus. The plant is focused on the main product; residue is treated as cost, not as potential asset.
- Active disposal contract. Often there is an annual contract with a licensed waste management company. The flow is set, no one stops to rethink.
- Hazardous-waste classification looks at toxicity, not value. Class I dangerous waste is classified by environmental risk, not recoverable grade.
- Analysis cost is small but starts a project. "Too small to stop the plant, too big for nobody to approve."
- No channel. Those who know they have valuable material often don't know which buyer specialises in this flow.
Minimum playbook before next disposal
- Identify origin of each accumulated lot. Which process generated it. Which catalyst was in use. Which scale.
- Do not mix lots from different processes. Mixing kills average grade and prevents representative sampling.
- Photo + brief datasheet. This already enables preliminary technical screening — in some cases the initial reply is "yes, worth it" or "not worth it" without moving material.
- Volumetric sampling when indicated. Filters, mats and media can be sampled with a simple protocol; solid (cake, dust) requires sub-samples at multiple points with mixing and quartering.
- Assay. Preliminary XRF gives direction; ICP-MS or fire assay confirms when the lot justifies extra precision.
What NOT to do
- Incinerate before assay to reduce volume.
- Hydrojet or solvent-wash without protocol.
- Send to generic disposal before at least a photo.
- Trust surface XRF without proper sample preparation.
- Stockpile for years waiting to "be big enough" — old material contaminates and mixes.
Cost vs. potential value
In orders of magnitude: photo + datasheet + preliminary screening is virtually no cost. In-house XRF on prepared sample is an order of magnitude smaller than ICP-MS. Per-sample ICP-MS is an order of magnitude smaller than what a lot with relevant PGM can yield. The math of "test before disposing" is generally obvious once you have the analysis figure in hand.
Technical page on filters and black powder →
For a specific lot, send process datasheet and photos via the submission form or WhatsApp. Preliminary screening usually goes out the same business day — before the next licensed pickup.