ash

Formation and collection evidence

Records the evidence supporting combustion-ash identity and the collected fraction.

1. What evidence connects this material to a combustion event and identifies the feedstocks, including any mixed or unknown inputs? provenance
2. Was it collected from a gas stream, a combustion bed or bottom, or a mixture of collection points? definition

Ash lot delimitation

Defines the represented material and preserves uncertainty about mixed constituents.

1. What physical extent, collection interval or container set defines this ash lot, and where were other fractions combined with it? boundary
2. What evidence distinguishes this lot from separately managed char, soot, slag or ash-containing products? definition

Sampling coverage

Records which parts of the lot were sampled and the limitations of extrapolation.

1. Which depths, collection times and coarse or fine fractions do the ash samples represent? provenance
2. What sampling variability, unsampled regions or subsequent mixing limits application of the results to the whole lot? boundary

Composition with method

Preserves analytical methods, reporting bases and unresolved constituent identities.

1. Which mineral phases, elements and potential contaminants were measured, using what methods, reporting bases and detection limits? measurement
2. Was residual carbon measured directly, and if loss on ignition was used, what evidence supports its interpretation for this ash? measurement

Current handling condition

Establishes observed conditions without assuming that elapsed cooling time or a dry appearance proves readiness.

1. What temperatures and trends were measured at the surface and within the ash, and is there evidence of continuing heating or combustion? measurement
2. What are the moisture content, particle-size distribution and degree of crusting or agglomeration at the intended handling time? measurement

Scenario-specific release evidence

Links dust observations, extract chemistry and wetting assessments to the conditions actually considered.

1. What observations or tests describe dust release during the proposed transfer, disturbance or storage conditions? measurement
2. What do specified extraction and compatibility tests establish about pH, constituent release and response to wetting, and which proposed contact conditions remain untested? boundary

Condition-dependent actions

Records prerequisites for transfer, containment, separation or conditioning and their verification.

1. Which measured ash conditions determine the containment, cooling, dust-control and transfer measures required before movement? action
2. If screening, wetting, washing or another treatment is proposed, what compatibility evidence and post-treatment checks are required? action

Acceptance evidence and gaps

Records the criteria, evidence, conditions and unresolved issues for the proposed destination.

1. Which intended use or receiving facility, jurisdiction and current acceptance criteria govern this ash lot? boundary
2. Which requirements are met by representative evidence, and what missing tests, treatment or authorisation prevent acceptance? action

Kinds and varieties

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• wood ash (biomass / fireplace / boiler)
• coal fly ash (pulverized-fuel ash)
• coal bottom ash and boiler slag
• municipal-solid-waste incinerator (MSWI) fly ash and bottom ash
• volcanic ash (tephra, pyroclastic fall)
• cremated human remains (cremains)
• analytical ash (proximate-analysis residue / ash content)
• oil-shale and petroleum-coke ash

1. Which of these kinds and varieties hold for the sense of ash this model covers, and on what evidence? provenance

Identifiers and schemes

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Wikidata - Q167336 (ash as combustion residue); Q185242 (fly ash); Q1151405 (volcanic ash / tephra); Q3775684 (wood ash) - No single Wikidata item covers every PHY.MAT sense; coal CCR, volcanic tephra, wood ash and cremains are distinct items.
• CAS Registry Number - 68131-74-8 (ashes, residues; coal fly ash as a UVCB substance); 60676-86-0 (silica, vitreous, often cited for glassy fly-ash fraction) - Fly ash is a UVCB (Unknown or Variable composition, Complex reaction product, Biological material), not a stoichiometric compound.
• EC / EINECS - 268-627-4 (Ashes (residues)); 931-322-8 (Ashes (residues), coal) - REACH substance identifiers for combustion residues as industrial chemicals.
• HS / Combined Nomenclature - HS 2621 (slag, ash and residues from incineration of municipal waste, etc.); HS 262190 (other slag and ash, including seaweed ash / kelp) - Trade classification of ash as a commodity, not a material specification.
• UN GHS / waste codes - European List of Waste 10 01 02 (coal fly ash); 10 01 01 (bottom ash, slag and boiler dust); 19 01 11*/19 01 12 (MSWI bottom ash, hazardous/non-hazardous); 19 01 13*/19 01 14 (MSWI fly ash) - Hazardousness is code- and jurisdiction-dependent; MSWI fly ash is frequently hazardous (*).

1. Which of these identifiers and schemes hold for the sense of ash this model covers, and on what evidence? provenance

Standards and regulation

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• ASTM C618 (ASTM International) - coal fly ash and natural pozzolan for concrete (Class F / Class C).
• EN 450-1 and EN 450-2 (CEN) - fly ash for concrete, definition/specifications and conformity evaluation.
• EN 197-1 (CEN) - cement: fly ash as a main constituent of CEM II/IV/V cements.
• AASHTO M 295 (AASHTO) - coal fly ash for use in Portland-cement concrete (U.S. highway practice).
• ISO 18122 (ISO) - solid biofuels, determination of ash content at 550 °C.
• ASTM D3174 / ISO 1171 (ASTM / ISO) - ash in coal and coke (proximate analysis, typically 750-815 °C).
• 40 CFR Part 257 Subpart D, Coal Combustion Residuals (CCR) Rule (U.S. EPA) - disposal, groundwater monitoring, and structural integrity of CCR units.
• Directive 2008/98/EC on waste, as amended, and Decision 2000/532/EC List of Waste (EU) - classification of incineration and combustion ashes; end-of-waste criteria vary by member state.
• Regulation (EC) No 1907/2006 (REACH) (ECHA / EU) - registration of ashes (residues) as UVCB substances when placed on the market as substances.
• ICAO Doc 9974 / volcanic-ash contingency procedures and VAAC products (ICAO / WMO) - aviation operations in volcanic ash.
• IMO MARPOL Annex V and related circulars (IMO) - restrictions on discharge of incinerator ash at sea from ships.
• National building and environmental codes implementing the above (e.g. ACI 232.2R on fly ash in concrete; UK Quality Protocol for pulverised fuel ash / furnace bottom ash).

1. Which of these standards and regulation hold for the sense of ash this model covers, and on what evidence? provenance

Real-world use

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Coal fly ash is the largest industrial pozzolan: blended into Portland cement and concrete (typically 15-40 % of cementitious material), used in flowable fill, embankments, and as a raw mix component in clinker manufacture.
• Coal bottom ash is used as a lightweight aggregate, structural fill, and in road-base; boiler slag as blasting grit and roofing granules.
• Wood and biomass ash is returned to forest and agricultural soils as a liming agent and potassium/phosphorus source, or landfilled when heavy-metal or PAH limits are exceeded.
• MSWI bottom ash is processed (aging, metals recovery, screening) and used as unbound aggregate in road construction in several EU states; MSWI fly ash is usually treated and landfilled as hazardous waste.
• Volcanic ash is encountered as a natural tephra deposit and airborne plume: it closes airspace, abrades jet engines, collapses roofs when wet, contaminates water, and is locally mined as pozzolan or abrasive.
• In fuel and biomass laboratories, 'ash' is the measured residue after controlled ashing and is reported as a quality specification (ash content of coal, wood pellets, food, waste).
• Cremated remains are a commercial and funerary product (cremains), chemically similar to bone-derived calcium phosphate ash, not to coal or volcanic ash.
• High-carbon or off-spec fly ash is used in geopolymers, as a filler, or remains in surface impoundments pending remediation.

1. Which of these real-world use hold for the sense of ash this model covers, and on what evidence? provenance

Typical measurements

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Ash content (loss-free residue after specified ashing) - Coal: ~5-20 % (bituminous) to >30 % (high-ash lignite); wood pellets: typically ≤0.7-2 % (ISO 17225 grades); MSW: highly variable, often 15-30 % of as-received waste appearing as bottom ash - mass % (dry basis unless stated)
• Ashing / determination temperature - 550 °C (solid biofuels, ISO 18122); 750-815 °C (coal/coke, ISO 1171 / ASTM D3174); ~815 °C common for coal in Europe - °C
• Particle size (fly ash vs volcanic ash vs bottom ash) - Coal fly ash: mostly 1-100 µm, median often 10-30 µm; volcanic ash: <2 mm by definition, with a large respirable fraction; bottom ash: millimetres to centimetres - µm or mm
• Bulk density (dry, loose to compacted) - Coal fly ash ~0.5-1.5 g/cm³ loose; bottom ash ~0.7-1.6 g/cm³; volcanic ash deposits highly variable with vesicularity and packing - g/cm³ or kg/m³
• Specific gravity of solids - Coal fly ash typically 1.9-2.9; Class C often denser than high-carbon Class F - dimensionless (relative to water)
• Oxide chemistry (SiO2, Al2O3, Fe2O3, CaO, SO3, Na2O/K2O, unburned carbon as LOI) - Class F: SiO2+Al2O3+Fe2O3 ≥70 %, CaO often <10-18 %; Class C: SiO2+Al2O3+Fe2O3 ≥50 %, CaO often >20 %; wood ash: high CaO/K2O, low SiO2 relative to coal ash; volcanic ash: magmatic, typically high SiO2 in rhyolite, lower in basalt - mass % of ash
• Loss on ignition (unburned carbon and bound volatiles) - Concrete-grade fly ash often limited to ≤5-6 % LOI (ASTM C618 / EN 450); off-spec ashes may exceed 10-15 % - mass %
• pH of ash-water leachate / ash slurry - Wood ash often pH 10-13; Class C fly ash alkaline (often >11); some Class F near-neutral to alkaline; MSWI fly ash highly alkaline and saline - pH units
• Leachable metals and salts (As, B, Cr, Mo, Pb, Se, Tl, Cl−, SO4^2−) - Highly source-dependent; MSWI fly ash and some CCR leachates can exceed drinking-water or hazardous-waste thresholds; wood ash typically lower in As/Se, higher in K and soluble alkalis - mg/L (leachate) or mg/kg (solid)
• Pozzolanic / hydraulic activity (strength activity index) - ASTM C618 SAI typically ≥75 % of control at 7 or 28 days for qualifying fly ash - % of control mortar strength

1. Which of these typical measurements hold for the sense of ash this model covers, and on what evidence? provenance

Failure modes and hazards

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Airborne respirable particles (PM2.5/PM10): irritation, exacerbation of asthma and COPD; volcanic ash and some coal ashes may contain crystalline silica (quartz, cristobalite) with silicosis risk on chronic occupational exposure.
• Wet volcanic ash and some fly ashes are heavy and electrically conductive: roof collapse, shorting of insulators, failure of wastewater and stormwater systems.
• Jet-engine ingestion of volcanic ash: melting of silicate glass on hot-section components, compressor abrasion, and inflight flameout (historical near-loss events, e.g. British Airways 9, KLM 867).
• Alkali-silica reaction and delayed ettringite / sulfate attack in concrete if fly ash chemistry, alkali load, or sulfate content is out of specification.
• Carbon in fly ash (high LOI) adsorbs air-entraining admixtures, collapsing freeze-thaw resistance of concrete.
• CCR and MSWI ash leachate: arsenic, selenium, boron, mercury, lead, hexavalent chromium, chloride and sulfate contamination of groundwater from ponds and landfills; catastrophic pond failures (e.g. Kingston 2008, Dan River 2014).
• Alkali burns and high-pH dust from wood ash, Class C fly ash, and MSWI ash (CaO/Ca(OH)2, KOH).
• MSWI fly ash concentrates dioxins/furans, soluble chlorides and heavy metals; untreated reuse in construction can re-emit salts and organics.
• Radioactivity: some coal ashes and certain volcanic ashes concentrate NORM (U, Th, 40K, 226Ra); phosphate and coal ashes may exceed building-material activity-index limits in some jurisdictions.
• Self-hardening and heat release of high-CaO (Class C) fly ash in stockpiles; dust explosions are uncommon but carbon-rich ashes can smoulder.
• Cremains are chemically stable but are not a soil amendment equivalent to wood ash; scattering in water bodies is regulated in many places.

1. Which of these failure modes and hazards hold for the sense of ash this model covers, and on what evidence? provenance

Regional variation

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• United States: 'coal ash' and 'CCR' (fly ash, bottom ash, boiler slag, FGD gypsum) are the dominant legal and industrial senses; ASTM C618 Class F vs Class C is the working taxonomy for concrete. Volcanic ash is a USGS/aviation sense, not a construction commodity except locally (e.g. Pacific Northwest pozzolans).
• European Union / UK: 'pulverised fuel ash' (PFA) and 'furnace bottom ash' (FBA) are the traditional coal-ash names; EN 450 siliceous fly ash is narrower than ASTM Class F/C (calcareous fly ash is treated via other cement standards). End-of-waste and Quality Protocols allow specified PFA/FBA as products. MSWI bottom-ash reuse in roads is common in the Netherlands, Denmark, Germany and France, restricted or landfilled elsewhere.
• East Asia: very large coal-fly-ash volumes in China and India; utilization rates and pond/lagoon practice differ sharply from EU productization. Japan uses 'coal ash' and volcanic ash (shirasu, etc.) as distinct construction materials.
• Nordic and boreal forestry: 'wood ash recycling' to forests is a named practice (Sweden, Finland, parts of Canada) with Cd and other metal limits that do not apply to coal ash.
• Pacific volcanic arcs (Japan, Indonesia, Philippines, Andes, Alaska, New Zealand): 'ash' in public communication almost always means volcanic tephra; grain-size and colour (andesitic grey vs rhyolitic pale) enter local naming.
• Trade English vs geology: geologists reserve 'ash' in the volcanic sense for clasts <2 mm (tephra classification); combustion engineers use 'ash' for any incombustible residue regardless of size (fly vs bottom is a capture location, not a grain-size class).
• Food and fuel testing: 'ash' means the analytical residue (ash content), a number on a specification sheet, not a bulk material one can shovel.

1. Which of these regional variation hold for the sense of ash this model covers, and on what evidence? provenance

Neighbouring kinds and how to tell them apart

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Slag (iron/steel blast-furnace or steelmaking slag) - Slag is a molten silicate separated from metal in a furnace and cooled as a glass or crystalline aggregate; ash is the solid residue of fuel or waste combustion and was never a metal-smelting melt. Test: process origin plus chemistry (slag is Ca-Mg-Al-silicate with very low unburned carbon and LOI ≈ 0; fly ash often has cenospheres, residual carbon, and spherical glassy particles).
• Pozzolan (natural), e.g. volcanic tuff, metakaolin, calcined clay - Natural pozzolans are mined or calcined rocks, not combustion residues. Some volcanic ashes are both volcanic ash and natural pozzolans. Test: ASTM C618 / EN 197 designation (Class N vs Class F/C) and whether the material is a coal-combustion residual.
• Cement kiln dust (CKD) and lime kiln dust (LKD) - CKD/LKD are process dusts from clinker or lime manufacture, typically much higher in free CaO, alkali and chloride than coal fly ash. Test: free-lime content, particle morphology (irregular vs fly-ash cenospheres), and plant origin.
• Silica fume (microsilica) - Silica fume is amorphous SiO2 fume from silicon/ferrosilicon furnaces, ultrafine (~0.1-0.2 µm), >85 % SiO2. Fly ash is coarser and a mixed aluminosilicate. Test: particle size, SiO2 assay, and BET surface area.
• Soot / black carbon / char - Soot is carbonaceous particulate from incomplete combustion; ash is the inorganic residue. High-LOI fly ash contains both. Test: LOI / elemental carbon vs oxide sum; optical/SEM morphology (fractal carbon vs glassy spheres).
• Pumice, scoria, and tuff - These are volcanic products related to ash: pumice and scoria are vesicular clasts, usually lapilli-sized or larger; tuff is lithified tephra. Loose volcanic ash is unconsolidated tephra <2 mm. Test: grain size (ash <2 mm), welding/lithification, and deposit context.
• Dust (mineral dust, construction dust, PM) - Dust is a particle-size/air-quality category, not a material. Ash may be a dust when airborne. Test: source and chemistry, not particle size alone.
• Bone ash / hydroxyapatite / cremains - Bone ash is calcium phosphate from calcined bone (historically for porcelain and cupellation); cremains are analogous. Wood and coal ashes are silicate-oxide-carbonate mixtures with little phosphate unless bone was in the feed. Test: P2O5 and Ca/P ratio vs silicate-dominated XRF.
• Clinker (Portland-cement clinker) and unhydrated cement - Clinker is a designed, sintered hydraulic product (alite/belite). Fly ash may be a cement constituent but is not clinker. Test: XRD (C3S/C2S vs glass + mullite + quartz typical of Class F fly ash).

1. Which of these neighbouring kinds and how to tell them apart hold for the sense of ash this model covers, and on what evidence? provenance