Zinc, unwrought

1. Scope and Applicability

This PCR applies to the production of zinc metal in unwrought market form at the zinc-production facility gate. It covers primary electrolytic and thermal production from zinc concentrate and secondary recovery from zinc scrap when the reference output is unwrought zinc. It includes feed preparation within the facility, roasting or sintering when used, leaching and purification when used, electrowinning or thermal reduction and condensation, refining, melting, casting into unwrought form, and directly associated onsite off-gas, water, and residue management.

Mining, beneficiation, and concentration of ore are represented by upstream datasets for purchased zinc concentrate. Collection and preparation before zinc scrap reaches the facility, external transport, downstream galvanizing, alloy fabrication, rolling, extrusion, drawing, powder production, zinc-oxide production, product use, and end-of-life are outside the foreground boundary unless the study explicitly extends it. Zinc dust and powder, fabricated zinc products, zinc compounds, and waste zinc are not reference products under this PCR.

The foreground data package shall identify the production route, feed origin, zinc grade, product grade, facility geography, electricity supply, fuel mix, and whether sulfuric acid or another recoverable material leaves the facility as a co-product.

2. Product Category Identity

Field	Value
canonical_pcr_id	pcr.metal-products-machinery-and-equipment.basic-metals.zinc-unwrought
classification_refs	CPC 3.0: 41442, Zinc, unwrought
covered_products	Zinc metal sold in unwrought form from primary or secondary zinc production, including slab or ingot output before downstream fabrication
excluded_products	Zinc dust, powders, flakes, oxide, peroxide, fabricated bars, rods, profiles, wire, plates, sheets, strip, foil, zinc-coated articles, and zinc waste or scrap sold as waste
representative_product	Facility-gate unwrought zinc metal
production_route	Primary electrolytic, primary thermal, or secondary zinc recovery; route and feed shares shall be declared
market_state	Solid unwrought zinc at the facility gate, with declared physical form, zinc grade, alloying status, and purity specification

3. Reference Flow

Field	Value
What	Supply unwrought zinc metal for downstream fabrication or metallurgical use
How much	1 kg unwrought zinc at the zinc-production facility gate
How well	Meets the declared zinc grade, composition, physical-form, and customer or product-specification requirements
How long or cycle	One production lot; no service duration is assigned
reference_flow_link	The normalized output row out_unwrought_zinc

Field	Value
Reference amount	1 kg
Reference product flow	Zinc, unwrought
Reference flow property	Mass 93a60a56-a3c8-11da-a746-0800200b9a66
Reference unit group	Units of mass 93a60a57-a4c8-11da-a746-0800200c9a66
Reference unit	kg
Required qualifiers	production route; primary and secondary feed shares; product physical form; zinc grade and purity; alloying status and composition; facility geography; technology; reference year; electricity supply; fuel mix; sulfuric-acid recovery status; allocation method; facility-gate boundary

When constructing a foreground data package, the items listed in Required qualifiers must be declared in dataset metadata, process notes, reference flow comment, product description, or an equivalent data package field. Missing required qualifiers make the reference flow definition incomplete for that data package.

4. Measurement and Unit Rules

rule_id	Applies to	Required property	Required unit	Rule
reference_mass	reference product and all mass-normalized rows	Mass 93a60a56-a3c8-11da-a746-0800200b9a66	kg	Normalize all inventory exchanges to 1 kg of saleable unwrought zinc leaving the facility gate; report gross cast mass, internal remelt, off-spec return, and net saleable mass separately before normalization.
wet_dry_basis	concentrate, scrap, slag, and leach residue	Mass 93a60a56-a3c8-11da-a746-0800200b9a66	kg	Record as-weighed mass and moisture or dry-solids fraction; convert to the stated wet or dry basis without mixing bases.
contained_zinc	zinc-bearing feed and residue	Zinc content 7c367337-54f2-4fe9-8ee3-3f42681b0792	kg Zn	Retain laboratory zinc grade and calculate contained zinc independently from total material mass; do not substitute contained-zinc mass for total flow mass.
electricity_energy	purchased and onsite electricity	energy	kWh	Preserve metered kWh; if an energy conversion is needed, use 1 kWh = 3.6 MJ and disclose the original meter unit and voltage level.
gas_reference_conditions	natural gas	Volume 93a60a56-a3c8-22da-a746-0800200c9a66	m3	Report gas volume at declared temperature and pressure and retain supplier net calorific value so energy and volume records remain auditable.
solution_concentration	sulfuric acid	Mass 93a60a56-a3c8-11da-a746-0800200b9a66	kg	Record solution mass and acid mass fraction; separately identify purchased, onsite-generated, internally recycled, and exported sulfuric acid.

5. System Boundary

Boundary Abstraction

Field	Value
declared_starting_condition	Zinc concentrate received at the primary smelter gate and/or sorted zinc scrap received at the secondary zinc-recovery gate, together with purchased utilities and reagents
starting_condition_role	Upstream products and wastes entering the foreground zinc-production facility
product_classification_scope	Unwrought zinc metal only; zinc compounds, powders, fabricated products, and zinc waste are outside the reference-product identity
recursive_input_rule	Purchased unwrought zinc used for remelting shall be recorded as a separate product input with an upstream dataset and shall not be silently treated as internal recycle or recursively expanded within this PCR
upstream_dataset_requirement	Use geographically and technologically representative upstream datasets for concentrate, scrap preparation, electricity, fuels, reagents, water supply, and external waste treatment
disclosure	Declare route, feed shares and grades, included unit operations, onsite energy generation, internal recycling, controlled and fugitive emission points, water boundary, residue destinations, co-products, and cut-offs

rule_id	Applies to	Rule	source_ids
boundary_facility_gate	all routes	Include all unit operations from receipt of qualified concentrate or scrap through saleable unwrought-zinc casting, including directly associated onsite off-gas, effluent, and residue treatment.	us-epa-ap42-zinc-smelting-1986; us-epa-ap42-secondary-zinc-1981
boundary_upstream	purchased inputs	Model mining, concentration, scrap collection and preparation outside the facility, purchased energy, reagents, and water through upstream datasets; do not duplicate their upstream emissions as direct facility emissions.	us-epa-ap42-zinc-smelting-1986; us-epa-ap42-secondary-zinc-1981
boundary_route_disclosure	route-dependent operations	Include roasting, leaching, purification and electrowinning only when used; include sintering, reduction, retorting, condensation or secondary pretreatment only when used, and state every exclusion.	us-epa-ap42-zinc-smelting-1986; us-epa-ap42-secondary-zinc-1981; ipcc-2006-metal-industry-zinc
boundary_carbon_accounting	fuels and carbonaceous reductants	Separate direct process carbon dioxide from fuel-combustion emissions and prevent double counting with upstream coke production or energy datasets.	ipcc-2006-metal-industry-zinc

6. Process Inventory Structure

Process Map

process_id	process_name	inclusion	inclusion_condition	role	quantitative_reference
zinc_unwrought_production	Unwrought zinc production, refining, and casting	required	All datasets; route-specific exchanges apply only when their stated route is used	Foreground aggregation of feed preparation, hydrometallurgical or thermal zinc recovery, refining, casting, and onsite pollution control	1 kg saleable unwrought zinc output

Process: Unwrought zinc production, refining, and casting (zinc_unwrought_production)

Inputs

Product flows

Zinc concentrate for primary production (in_zinc_concentrate)

Record zinc concentrate received from beneficiation when a primary route is used; do not use this row for run-of-mine ore or finished zinc metal.

• Selected flow: Zinc concentrate ecb60d59-d9e3-4d96-958d-7b4453a8174f
• Flow property / unit: Mass / kg
• Amount rule: measured received concentrate mass, with moisture and zinc grade retained
• Value mode: Foreground record (foreground_record)
• Specificity: Route-specific (route_specific)
• Normalization basis: per 1 kg saleable unwrought zinc output
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_feed_mass
• Sources: us-epa-ap42-zinc-smelting-1986

Sulfuric acid used in leaching (in_sulfuric_acid)

Record net sulfuric acid entering the hydrometallurgical route after separating onsite generation and internal recycle.

• Selected flow: Sulfuric acid 7ee2e3c3-bee7-4520-92b7-3e23afbfcd6f
• Flow property / unit: Mass / kg
• Amount rule: purchased plus transferred-in sulfuric acid, excluding internal recycle, with concentration recorded
• Value mode: Foreground record (foreground_record)
• Specificity: Route-specific (route_specific)
• Normalization basis: per 1 kg saleable unwrought zinc output
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_reagent_mass
• Sources: us-epa-ap42-zinc-smelting-1986

Process water (in_process_water)

Record process water consumed in leaching, washing, cooling make-up, gas cleaning, and other onsite zinc-production operations; exclude water merely passing through without consumption.

• Selected flow: Process Water 94a04f7e-2d5c-41f0-b182-d54a3b373a02
• Flow property / unit: Mass / kg
• Amount rule: metered water entering the foreground system minus separately measured pass-through returns
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg saleable unwrought zinc output
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_water_meter
• Sources: us-epa-ap42-zinc-smelting-1986; us-epa-ap42-secondary-zinc-1981

Purchased electricity (in_electricity)

Record electricity delivered across the facility boundary for electrolysis, retorting, material handling, pumping, gas cleaning, and casting. The Tiangong UUID remains unresolved because ranked candidates did not provide consistent property and unit support.

• Selected flow: Purchased electricity, delivered at the declared voltage level
• Flow property / unit: Energy / kWh
• Amount rule: revenue-meter imports minus metered exports, with onsite generation reported separately
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg saleable unwrought zinc output
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_electricity_meter
• Sources: us-epa-ap42-zinc-smelting-1986

Natural gas used onsite (in_natural_gas)

Record natural gas consumed for direct process heat only when the facility uses it; retain reference conditions and net calorific value.

• Selected flow: natural gas in the gaseous state 4f19ca0e-7b3b-11dd-ad8b-0800200c9a66
• Flow property / unit: Volume / m3
• Amount rule: metered natural-gas consumption assigned to included zinc-production operations
• Value mode: Foreground record (foreground_record)
• Specificity: Technology-specific (technology_specific)
• Normalization basis: per 1 kg saleable unwrought zinc output
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_fuel_meter
• Sources: us-epa-ap42-zinc-smelting-1986; ipcc-2006-metal-industry-zinc

Metallurgical coke reductant (in_metallurgical_coke)

Record metallurgical coke only for thermal reduction, Imperial Smelting, electrothermic, Waelz-kiln, or other declared carbon-reduction operations.

• Selected flow: metallurgical coke a94c42b1-7fa9-42f3-a9d1-1e7353e8490d
• Flow property / unit: Mass / kg
• Amount rule: measured coke charged to included zinc-production operations, with moisture, ash, and carbon content retained
• Value mode: Foreground record (foreground_record)
• Specificity: Route-specific (route_specific)
• Normalization basis: per 1 kg saleable unwrought zinc output
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_fuel_meter
• Sources: us-epa-ap42-zinc-smelting-1986; ipcc-2006-metal-industry-zinc

Waste flows

Zinc scrap for secondary recovery (in_zinc_scrap)

Record zinc scrap accepted as a waste input only when the secondary route is included; retain source, composition, contamination, and any burden-allocation convention.

• Selected flow: zinc scrap b1629e09-83ea-4027-aab4-3a02406fac02
• Flow property / unit: Mass / kg
• Amount rule: measured received zinc-scrap mass, with moisture, zinc content, and contaminants retained
• Value mode: Foreground record (foreground_record)
• Specificity: Route-specific (route_specific)
• Normalization basis: per 1 kg saleable unwrought zinc output
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_feed_mass
• Sources: us-epa-ap42-secondary-zinc-1981; ipcc-2006-metal-industry-zinc

Elementary flows

No elementary input is prescribed. Resource extractions embodied in purchased products are represented in their upstream datasets.

Outputs

Product flows

Saleable unwrought zinc (out_unwrought_zinc)

Record only conforming zinc metal leaving the facility in unwrought market form. The reference-product UUID remains unresolved because the zinc-ingot candidate conflicts with its fabricated-zinc classification.

• Selected flow: Zinc, unwrought
• Flow property / unit: Mass / kg
• Amount rule: normalize measured net saleable unwrought-zinc output to 1 kg
• Value mode: Calculated value (calculated_value)
• Specificity: Generic (generic)
• Normalization basis: 1 kg reference product
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Calculated from collection (calculated_from_collection)
• Collection protocol: cp_product_mass
• Sources: un-cpc-3-0-structure-2025; us-epa-ap42-zinc-smelting-1986; us-epa-ap42-secondary-zinc-1981

Sulfuric acid co-product (out_sulfuric_acid)

Record sulfuric acid leaving the foreground facility as a saleable co-product; do not count acid internally recycled to leaching as an output.

• Selected flow: Sulfuric acid 7ee2e3c3-bee7-4520-92b7-3e23afbfcd6f
• Flow property / unit: Mass / kg
• Amount rule: measured exported acid solution mass with acid concentration retained
• Value mode: Foreground record (foreground_record)
• Specificity: Technology-specific (technology_specific)
• Normalization basis: per 1 kg saleable unwrought zinc output
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_product_mass
• Sources: us-epa-ap42-zinc-smelting-1986

Waste flows

Zinc slag from thermal processing (out_zinc_slag)

Record zinc slag crossing the facility boundary from thermal zinc production or secondary recovery; retain destination and recoverable zinc content.

• Selected flow: zinc slag (unspecified) 1fe4a169-ae95-4eb8-b3d4-f5db63d1ca23
• Flow property / unit: Mass / kg
• Amount rule: measured slag mass leaving the foreground system, separated from internally recycled slag
• Value mode: Foreground record (foreground_record)
• Specificity: Route-specific (route_specific)
• Normalization basis: per 1 kg saleable unwrought zinc output
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_waste_mass
• Sources: us-epa-ap42-zinc-smelting-1986; ipcc-2006-metal-industry-zinc

Zinc-bearing leach residue (out_zinc_leach_residue)

Record solid residue leaving leaching and purification in the hydrometallurgical route. No exact Tiangong waste UUID was found; do not substitute zinc scrap or thermal zinc slag.

• Selected flow: Zinc-bearing leach residue
• Flow property / unit: Mass / kg
• Amount rule: measured residue mass leaving the foreground system, with wet mass, moisture, dry mass, and zinc content retained
• Value mode: Foreground record (foreground_record)
• Specificity: Route-specific (route_specific)
• Normalization basis: per 1 kg saleable unwrought zinc output
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_waste_mass
• Sources: us-epa-ap42-zinc-smelting-1986

Elementary flows

Fossil carbon dioxide to air (out_fossil_carbon_dioxide)

Record direct fossil carbon dioxide from carbonaceous reducing agents and onsite fuel combustion, while preventing double counting between process and energy accounting.

• Selected flow: carbon dioxide (fossil) 08a91e70-3ddc-11dd-923d-0050c2490048
• Flow property / unit: Mass / kg
• Amount rule: measured direct fossil CO2 or facility carbon balance for included operations
• Value mode: Calculated value (calculated_value)
• Specificity: Route-specific (route_specific)
• Normalization basis: per 1 kg saleable unwrought zinc output
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Calculated from collection (calculated_from_collection)
• Collection protocol: cp_emissions
• Sources: ipcc-2006-metal-industry-zinc

Sulfur dioxide to air, unspecified (out_sulfur_dioxide_air)

Record sulfur dioxide remaining after sulfur recovery and air-pollution control, including quantified fugitive releases. No exact unspecified-air UUID was found.

• Selected flow: Sulfur dioxide to air, unspecified
• Flow property / unit: Mass / kg
• Amount rule: measured controlled stack plus quantified fugitive sulfur-dioxide emissions
• Value mode: Calculated value (calculated_value)
• Specificity: Technology-specific (technology_specific)
• Normalization basis: per 1 kg saleable unwrought zinc output
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Calculated from collection (calculated_from_collection)
• Collection protocol: cp_emissions
• Sources: us-epa-ap42-zinc-smelting-1986

Zinc to air, unspecified (out_zinc_air)

Record zinc in controlled and fugitive air emissions as elemental zinc mass, not total particulate mass.

• Selected flow: zinc 08a91e70-3ddc-11dd-94e3-0050c2490048
• Flow property / unit: Mass / kg
• Amount rule: measured zinc mass in stack and fugitive air releases
• Value mode: Calculated value (calculated_value)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg saleable unwrought zinc output
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Calculated from collection (calculated_from_collection)
• Collection protocol: cp_emissions
• Sources: us-epa-ap42-zinc-smelting-1986; us-epa-ap42-secondary-zinc-1981

Zinc to water, unspecified (out_zinc_water)

Record dissolved and suspended zinc discharged across the facility water boundary after treatment; disclose the receiving-water compartment when known.

• Selected flow: zinc 08a91e70-3ddc-11dd-94e9-0050c2490048
• Flow property / unit: Mass / kg
• Amount rule: treated-effluent volume multiplied by representative zinc concentration, plus separately measured direct releases
• Value mode: Calculated value (calculated_value)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg saleable unwrought zinc output
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Calculated from collection (calculated_from_collection)
• Collection protocol: cp_emissions
• Sources: us-epa-ap42-zinc-smelting-1986; us-epa-ap42-secondary-zinc-1981

7. Allocation and Co-product Handling

rule_id	Applies to	Rule	source_ids
allocation_subdivision	separately metered unit operations	Avoid allocation by subdividing primary, secondary, acid-production, lead-recovery, residue-treatment, and utility operations wherever separate measurements exist.	us-epa-ap42-zinc-smelting-1986; us-epa-ap42-secondary-zinc-1981
allocation_joint_lead_zinc	simultaneous lead and zinc production	Assign jointly consumed coke and direct process emissions using a documented plant-specific physical relationship or mass balance; report factors and prevent double counting between lead and zinc.	ipcc-2006-metal-industry-zinc
allocation_sulfuric_acid	saleable sulfuric acid	First assign directly measured acid-plant inputs and outputs to acid production; allocate only residual inseparable burdens using a declared physical relationship, or economic allocation when no defensible physical relation exists, and report a sensitivity result.	us-epa-ap42-zinc-smelting-1986
allocation_waste_inputs	zinc scrap and other waste feeds	State the waste-allocation convention, any incoming burden, pretreatment boundary, and credits; do not claim avoided primary zinc production inside the inventory unless the study applies and discloses a consequential substitution model.	us-epa-ap42-secondary-zinc-1981

8. Foreground Data Collection, Calculation, and Quality Rules

Data Collection Protocols

protocol_id	process_id	flow_role	record_type	raw_fields	collection_method	unit	frequency	temporal_coverage	site_scope	aggregation_rule	quality_evidence
cp_feed_mass	zinc_unwrought_production	zinc concentrate and zinc scrap	weighbridge and laboratory records	received mass; tare; moisture; zinc grade; lot id; supplier; feed route	reconcile weighbridge tickets with laboratory certificates and stock change	kg; mass fraction	each receipt and monthly close	representative continuous 12-month period	all feed receiving points in scope	receipts plus opening stock minus closing stock, separated by feed type, then normalized	calibrated scale records; sampling plan; laboratory QA/QC; stock reconciliation
cp_reagent_mass	zinc_unwrought_production	sulfuric acid input	purchase, transfer, tank, and concentration records	solution mass or volume; density; acid fraction; opening and closing stock; internal recycle	reconcile invoices and calibrated tank measurements; distinguish purchased, generated, recycled, and exported acid	kg solution; kg H2SO4	batch or daily meter and monthly close	same 12-month period as product output	all included acid storage and process circuits	purchased plus transfer-in plus opening stock minus closing stock minus export, excluding internal recycle	tank calibration; density and assay method; invoice reconciliation
cp_water_meter	zinc_unwrought_production	process water input	water-meter records	withdrawal; purchased water; returned pass-through water; meter id	read calibrated boundary and sub-meters and reconcile with utility invoices	kg or m3	daily or monthly	same 12-month period as product output	all included water entry points	net consumed boundary water, converted with documented density when needed	meter calibration; water balance; missing-data log
cp_electricity_meter	zinc_unwrought_production	purchased electricity input	revenue and sub-meter records	imported kWh; exported kWh; onsite generation; voltage; meter id	reconcile revenue meter, sub-meters, and onsite generation records	kWh	interval or monthly	same 12-month period as product output	all included electrical boundary meters	imports minus exports; do not net onsite generation against fuel inputs without disclosure	meter calibration; invoices; energy balance
cp_fuel_meter	zinc_unwrought_production	natural gas and metallurgical coke	fuel meter, scale, inventory, and assay records	gas volume; reference conditions; calorific value; coke mass; moisture; ash; carbon; stock change	reconcile gas bills and calibrated meters; reconcile coke receipts, scales, and stocks	m3; MJ; kg	continuous or each delivery and monthly close	same 12-month period as product output	all included fuel and reductant entry points	consumption equals receipts plus opening stock minus closing stock, separated by material and use	meter and scale calibration; supplier assay; carbon balance
cp_product_mass	zinc_unwrought_production	unwrought zinc and sulfuric acid outputs	casting scale, dispatch, tank, and laboratory records	gross cast zinc; internal remelt; off-spec return; net saleable zinc; acid solution mass; acid fraction; shipment id	reconcile production, internal return, inventory, and dispatch records	kg	lot and monthly close	same 12-month period as inputs	all product and co-product exit points	net saleable output equals shipped plus closing stock minus opening stock, excluding internal recycle	calibrated scales and tanks; product assay; dispatch reconciliation
cp_waste_mass	zinc_unwrought_production	zinc slag and zinc-bearing leach residue	waste scale, manifest, moisture, and assay records	wet mass; moisture; dry mass; zinc grade; destination; internal recycle	reconcile scales, waste manifests, laboratory assays, and internal returns	kg	each shipment and monthly close	same 12-month period as product output	all included waste exit points	external output only; internal recycle remains inside the boundary	scale calibration; chain of custody; laboratory QA/QC; waste-handler receipt
cp_emissions	zinc_unwrought_production	fossil CO2, sulfur dioxide, zinc to air, and zinc to water	continuous monitoring, stack tests, effluent monitoring, fuel and reductant assays	gas flow; concentration; operating hours; effluent flow; zinc concentration; fuel carbon; coke carbon; control-device downtime	use validated direct measurements where available; otherwise calculate from collected activity and assay data with stated equations	kg; concentration; flow rate	continuous, campaign, or permit-compliant sampling with monthly aggregation	representative continuous 12-month period including abnormal operation	all included point, fugitive, and water discharge boundaries	sum measured points and justified fugitive estimates; prevent process-energy double counting	calibration; detection limits; sampling representativeness; laboratory QA/QC; mass and carbon balances

Calculation Rules

rule_id	Applies to	Formula or rule	Inputs	Output	source_ids
calc_normalize_inventory	every inventory row	normalized exchange = period exchange / net saleable unwrought-zinc output	period exchange; net saleable zinc mass	exchange per 1 kg unwrought zinc
calc_dry_mass	zinc-bearing feed and residue	dry mass = wet mass × (1 − moisture mass fraction)	wet mass; moisture mass fraction	kg dry material
calc_contained_zinc	zinc-bearing feed and residue	contained zinc = dry mass × dry-basis zinc mass fraction	dry mass; zinc assay	kg Zn
calc_acid_mass	sulfuric acid	acid mass = solution mass × sulfuric-acid mass fraction	solution mass; concentration	kg H2SO4	us-epa-ap42-zinc-smelting-1986
calc_waterborne_zinc	zinc to water	zinc mass = treated-effluent volume × representative zinc concentration, with unit conversion and detection-limit treatment disclosed	effluent volume; zinc concentration	kg Zn to water
calc_process_co2	thermal zinc routes	Prefer measured facility emissions; otherwise apply a transparent carbon balance to collected reducing-agent and other carbonaceous process-material data and separate fuel-combustion accounting	carbon inputs; carbon retained in outputs and wastes; measured emissions where available	kg fossil CO2	ipcc-2006-metal-industry-zinc

Data Quality Requirements

requirement_id	Applies to	Requirement	Evidence
dq_identity	reference product	Retain product form, zinc grade, purity or alloy composition, lot definition, and conformity evidence.	product assay, specification, and dispatch record
dq_route	all inventory	Identify primary electrolytic, thermal, or secondary route and report primary and secondary feed shares.	process flow diagram, feed records, and production log
dq_temporal	all foreground data	Use one representative continuous 12-month period or justify a shorter campaign that captures start-up, shutdown, maintenance, and abnormal operation.	dated meter, production, maintenance, and emission records
dq_completeness	mass, zinc, sulfur, energy, carbon, and water balances	Reconcile inputs, saleable outputs, internal recycle, stocks, wastes, and direct releases; explain material residuals and all exclusions.	signed balance worksheets and reconciliation findings
dq_measurement	meters, scales, assays, and emission monitoring	Retain calibration status, method, sampling frequency, detection limits, missing-data treatment, and laboratory QA/QC.	calibration certificates, method records, and QA/QC results
dq_geography	upstream supplies and direct releases	Match electricity, fuel, water, concentrate, scrap, and treatment datasets to the declared geography and disclose receiving compartments.	supplier and facility location records; dataset metadata
dq_allocation	co-products and joint production	Retain subdivision logic, allocation basis, factors, price period if economic allocation is used, and sensitivity results.	allocation worksheet and source records

9. Validation Rules

rule_id	Applies to	Rule	source_ids
validate_reference_output	out_unwrought_zinc	Net saleable unwrought-zinc output shall equal 1 kg after normalization, and gross casting, internal remelt, off-spec return, and inventory change shall remain auditable.
validate_product_boundary	reference product	Reject a dataset whose reference output is zinc powder, zinc oxide, a fabricated zinc product, or zinc scrap rather than unwrought zinc metal.	un-cpc-3-0-structure-2025
validate_route_rows	route-specific inventory	A route-specific row shall be present only when its declared operation is used; absence shall be supported by route documentation, not a zero entered without explanation.	us-epa-ap42-zinc-smelting-1986; us-epa-ap42-secondary-zinc-1981; ipcc-2006-metal-industry-zinc
validate_zinc_balance	feed, product, co-product, slag, residue, and emissions	Complete a contained-zinc balance using consistent wet/dry bases and assays; investigate and explain the residual.
validate_sulfur_balance	sulfide concentrate, sulfuric acid, sulfur dioxide, and sulfur-bearing residue	Complete a sulfur balance when sulfide concentrate is processed and distinguish recovered acid from emitted sulfur dioxide.	us-epa-ap42-zinc-smelting-1986
validate_carbon_double_count	natural gas, coke, and fossil carbon dioxide	Demonstrate that process CO2, onsite fuel-combustion CO2, upstream fuel burdens, and coke-production emissions are neither omitted nor double counted.	ipcc-2006-metal-industry-zinc
validate_uuid_gaps	unresolved Tiangong flows	Before publication, resolve or explicitly review the unwrought-zinc reference product, electricity, leach-residue, and sulfur-dioxide UUID gaps; do not substitute a near match.
validate_sources	externally constrained rules	Every external source id shall resolve to the Data Sources table and shall be used only for the original-text-supported role stated there.

10. Published Dataset Profile

Field	Value
dataset_role	Facility-specific foreground production dataset suitable for reviewed publication as a secondary_dataset or background_dataset after source, UUID, and methodology review
downstream_use	Attributional process inventories and lifecycle models requiring unwrought zinc at the production facility gate
allowed_use	Use for the declared route, product grade, geography, technology, reference period, feed shares, electricity supply, fuel mix, water boundary, and allocation method
excluded_use	Do not use as a generic zinc-mining dataset, fabricated-zinc dataset, zinc-compound dataset, or consequential recycling credit without a separate model and disclosure
required_metadata	PCR id and version; product form and grade; route and feed shares; facility geography; technology; reference period; electricity and fuel supply; water boundary; co-products; allocation; cut-offs; upstream dataset identities
required_quality_disclosure	Data coverage; meter and scale calibration; sampling and assay methods; temporal representativeness; mass, zinc, sulfur, energy, carbon, and water balance results; missing-data treatment; uncertainty; unresolved UUIDs; source applicability
update_trigger	Change in route, feed shares or grade, product grade, major technology, electricity or fuel supply, emission control, water system, co-product recovery, allocation method, facility geography, or reference period

11. Data Sources

Source id	Type	Reference	Used for
un-cpc-3-0-structure-2025	official_guidance	United Nations Statistics Division, Central Product Classification Version 3.0 structure, 30 June 2025, https://unstats.un.org/unsd/classifications/Econ/Download/In%20Text/CPC_Ver_3.0_Structure_30Jun2025.csv (retrieved 2026-09-04)	Original text verifies CPC 41442 as “Zinc, unwrought” and distinguishes fabricated zinc product subclasses
us-epa-ap42-zinc-smelting-1986	official_guidance	U.S. EPA, AP-42 Section 12.7, Zinc Smelting, October 1986, reformatted January 1995, https://www.epa.gov/sites/production/files/2020-11/documents/c12s07.pdf (retrieved 2026-09-04)	Original text verifies primary zinc process decomposition, concentrate roasting, electrolytic leaching/purification/electrolysis, thermal retorting, slab zinc and sulfuric-acid output, and sulfur-dioxide, particulate, and metal-emission control points
us-epa-ap42-secondary-zinc-1981	official_guidance	U.S. EPA, AP-42 Section 12.14, Secondary Zinc Processing, April 1981, https://www.epa.gov/sites/production/files/2020-11/documents/c12s14.pdf (retrieved 2026-09-04)	Original text verifies secondary zinc recovery from scrap through pretreatment, melting, refining, and slab-zinc output and supports the secondary-route boundary and waste/emission collection needs
ipcc-2006-metal-industry-zinc	official_guidance	IPCC, 2006 Guidelines for National Greenhouse Gas Inventories, Volume 3, Chapter 4, Section 4.7 Zinc Production, https://www.ipcc-nggip.iges.or.jp/public/2006gl/pdf/3_Volume3/V3_4_Ch4_Metal_Industry.pdf (retrieved 2026-09-04)	Original text verifies electrolytic, electrothermic, Imperial Smelting, Waelz-kiln, and secondary routes; carbonaceous reductant and direct process-CO2 accounting; plant-specific activity data; allocation and double-counting controls