45 Processing of Scrap Aluminum • Crushing, shredding, and grinding• Drying• Heating in a dryer or kiln• Heating in a sweat furnace
46 Crushing, Shredding, and Grinding To reduce the size of scrap aluminumEmissions: Particulate matter (PM)and HAP metals generated as dustfrom coatings & other contaminants
47 Chip Dryers To reduce the size of scrap aluminum Emissions: Particulate matter (PM)& HAP metals generated as dust fromcoatings and other contaminants
48 Applicability and Description of Affected Units • Secondary aluminum production operationsAffected sourcesWe’ll discuss in general terms the types of operations that are considered to be part of a secondary aluminum production operation. Then we will identify “affected sources” as defined by the rule.
52 Preprocessing of Scrap Aluminum Crushing, shredding, and grindingDryingHeating in a dryer or kilnHeating in a sweat furnace
53 Crushing, Shredding, and Grinding To reduce the size of scrap aluminumEmissions: Particulate matter (PM) and HAP metals generated as dust from coatings and other contaminants
54 Chip DryersEvaporates oil and moisture from uncoated aluminum chips & boringsGenerally operate at temperatures ranging between 300oF to 750oFEmissions: Organic HAP’s including dioxins and furansThese are characteristics associated with “thermal chip dryers.” Pre-heating boxes, centrifuges, and other devices used to remove just water are not the same as thermal chip dryers.
55 Scrap Dryers/Delacquering Kilns/Decoating Kilns Remove coatings and other contaminants that may be present in scrap prior to melting (e.g., oil, grease, lubricants, lacquers, rubber, and plastic laminates)
56 Heat scrap to exit temperature of 1000 °F • Emissions: Inorganic HAP’s including particulate metal HAP’s and hydrogen chloride and organic HAP’s including dioxins and furans
68 FluxingDone to refine molten aluminum to improve product quality, achieve product specifications, or reduce material loss
69 Fluxes may be added to remove impurities and reduce aluminum oxidation May be performed in the furnace or outside the furnace by an in-line fluxer
70 Fluxing Processes Addition of salts (cover flux) Addition of solvents Injection of gasses (demagging and degassing)Chloride and fluoride salt fluxes are added to reduce oxidation. Flux gasses typically consist of chlorine or chlorine mixtures.
71 Process FurnacesRefractory-lined metal vessels heated by oil, gas, or electricity that are used to melt scrap
72 Types include melting, holding, and refining furnaces Charging of scrap can be done from the side, front, or top of the furnace
73 Examples of Process Furnaces Top charging and front charging furnaces
74 Sidewell melting furnace – a furnace with an open well adjacent to the hearth used for charging scrap & solid flux or salt to the furnace, injecting fluxing agents, & skimming dross
75 Transferring Molten Aluminum to Holding Furnace
77 Examples of Process Furnaces - Continued Induction furnaces – heating mechanism is electric energyReverberatory furnaces – typically gas
78 Process Furnace Emissions HAP emissions from scrap and fluxing agents include:• Particulate metal HAPsHydrogen chlorideDioxins and furans
79 Dross-only FurnacesTypically rotary barrel-designed furnaces dedicated to reclamation of aluminum from dross formed during melting, holding, alloying, or fluxing operations carried out in other process units
80 Dross-only Furnaces Cont’d. Dross and salt flux are sole feedstocksEmissions: Particulate matter including metal HAPs
81 In-line FluxingFluxing performed in a device exterior to furnace, located in a transfer line from furnaceInvolves injection of chlorine, argon, nitrogen, or other gases to achieve desired metal purity
82 In-line Fluxing - Continued Found primarily at facilities that manufacture high quality aluminum or in facilities with no other means of degassingEmissions: Hydrogen chloride and particulate matter
83 TappingTransferring molten metal from melting furnace to molds or to a ladle
84 Cooling of Dross“Dross” - slags and skimmings from melting and refining consisting of fluxing agents, impurities, and/or oxidized and non-oxidized aluminum
85 Cooling of Dross - Continued Accomplished in rotating, water-cooled drumsSole feedstock to dross-only furnacesEmissions: Particulate matter including metal HAPs
88 Affected Sources at Major Sources of HAP’s - §63.1500 Each new and existing:Aluminum scrap shredderThermal chip dryerScrap dryer/delacquering kiln/decoating kiln
89 Each new and existing group 2 furnace: Melts, holds, or processes only clean charge, andPerforms no fluxing, orPerforms fluxing using only non-reactive, non-HAP-containing/non-HAP-generating gases or agents
90 Each new and existing:Sweat furnaceDross-only furnaceRotary dross cooler
91 Each new and existing secondary aluminum processing unit (SAPU) Group 1 furnace: processes non-clean charge; or processes clean charge with reactive fluxingGroup 1 furnace is a furnace that processes non-clean (dirty) charge with or without reactive fluxing, or that processes clean charge and does reactive fluxing.
92 Combination of all group 1 furnaces and all in-line fluxers within a secondary aluminum production facility
94 Secondary Aluminum Processing Units (SAPU) Existing SAPU – all existing group 1 furnaces and all existing in-line fluxersProposed amendments would allow adding an existing emission unit to a new SAPU.
95 New SAPU – any combination of new group 1 furnaces and new in-line fluxers constructed after 2/11/99 Group 1 furnaces and in-line fluxers are emission units within an existing or new SAPU
97 Affected Sources at Area Sources of HAPs Emission limits for dioxins and furans and associated operating, monitoring, reporting, and recordkeeping requirements apply to affected sources located at area sourcesArea sources that have emissions of dioxins and furans are also subject to the D/F emission limits as well as the operating, monitoring , reporting, and recordkeeping requirements.
98 Affected Sources at Area Sources of HAPs Cont’d. Each new and existing:Thermal chip dryerScrap dryer/delacquering kiln/decoating kiln
99 Affected Sources at Area Sources of HAPs Cont’d. Sweat furnaceSAPU with one or more group 1 furnace emission units processing other than clean charge
101 Affected SourcesDoes not include aluminum die casters, foundries, or extruders that:Melt only clean charge and materials generated within the facility or returned clean materials originally from facility, and
102 Affected Sources Cont’d. Do not operate a thermal chip dryer, sweat furnace, or scrap dryer/delacquering kiln/decoating kiln
109 Runaround ScrapScrap generated on-site or returned that does not contain paint or solid coatingMachining chips that have not been dried ≥650° F, or by equivalent non-thermal drying method, are not runaroundAs defined by current rule.
115 Format of Emission Standard Emission limitsMass per unit (lb/ton) of feed/charge (or production)Concentration (gr/dscf)Percentage reduction
116 Format of Emission Standard - Continued Emission limitsD/F in units of TEQInternational method of expressing toxicity equivalents for D/FDifferent isomers of dioxins and furans have differing levels of toxicity. Analytical results report concentrations of these isomers and the method provides a means of calculating toxicity on a uniform basis.
117 Format of Emission Standard - Continued Except for D/F, apply to major sources onlyApply to all new and existing affected sources and emission units
124 Thermal Chip Dryers0.80 lb of total hydrocarbon emissions (THC) per ton of feed2.50 micrograms of dioxins and furans (D/F) toxicity equivalents (TEQ) per megagram (Mg) of feedA chip dryer that is not a thermal chip dryer, for example, a centrifugal dryer that only removes water, would not be subject to these limits.
125 Thermal Chip Dryers Cont’d. D/F limit for units at major or area sources
127 Scrap Dryers/Delacquering Kilns/Decoating Kilns 0.08 lb PM per ton of feed0.80 lb HCl per ton of feed0.06 lb THC per ton of feed0.25 micrograms of D/F TEQ per Mg of feed
128 Scrap Dryers/Delacquering Kilns/Decoating Kilns – Alternate Limit Applies if afterburner has a design residence time ≥ 1 second, and operates at a temperature ≥ 1400oF0.30 lb PM per ton of feedBecause the same process equipment can be used as a scrap dryer, a delacquering kiln o r a decoating kiln, an alternate emission limit was developed. The limits in the previous slide were are more stringent, but the afterburner design parameters are not required.The alternate limits are less stringent, but the source must meet the afterburner design criteria.
129 Scrap Dryers/Delacquering Kilns/Decoating Kilns – Alternate Limit Cont’d. 1.50 lb HCl per ton of feed0.20 lb THC per ton of feed5.0 micrograms D/F TEQ per Mg of feed
131 Sweat Furnaces0.80 nanograms D/F TEQ per dry standard cubic meter (dscm) at 11 percent oxygenNo test required if sweat furnace has afterburner with design residence time≥ 2 seconds and operates at ≥ 1600oFUnder the proposed amendments, the residence time would be corrected and changed to 0.8 seconds.
135 In-line FluxersLimits are used to calculate the standard applicable to secondary aluminum processing units (SAPU)0.04 lb HCl per ton of feed0.01 lb PM per ton of feedNote that in-line fluxers are emission units within the SAPU affected source.
136 In-line Fluxers With No Reactive Fluxing No HCl and PM limits applyWork practice – no reactive fluxing
142 Group 1 Melting/Holding Furnaces (Clean Charge Only) Limits are used to calculate the standard applicable to secondary aluminum processing units (SAPU)0.80 lb PM per ton of feedLike in-line fluxers, group 1 furnaces are emission units within a SAPU affected source.
143 Group 1 Melting/Holding Furnaces (Clean Charge Only) – Cont’d. 0.40 lb HCl per ton of feed, or 10 percent of the HCl upstream of an add-on control deviceNo D/F limit for clean charge furnaces – and only clean charge can be used
144 Group 1 FurnacesLimits are used to calculate the standard applicable to secondary aluminum processing units (SAPU)0.40 lb PM per ton of feed
145 Group 1 Furnaces Cont’d.0.40 lb HCl per ton of feed, or 10 percent of the HCl upstream of an add-on control device15.0 micrograms of D/F TEQ per Mg of feed
156 Emission Standards and Operating Requirements - Continued §
157 Capture/Collection Systems All sources and emission units with an add-on air pollution control device (APCD):Unless there have been complaints or direct observations of failures, an inspector might assume compliance. This is something that normally could not be determined during the inspection. The inspector can request to see records documenting the proper operation of the system (required in the monitoring requirements, ). Also, the inspector could request a copy of the design calculations showing adequate design and may include blueprints or drawings of the hood in relation to the process, information on plume temperatures, air velocity measurements, etc. for a later review by someone with experience in designing or evaluating hood systems.
158 Design and install a capture and collection system in accordance with American Conference of Governmental Industrial Hygienists (ACGIH) guidelines
159 Industrial Ventilation: A Manual of Recommended Practice - Chapter 3: Local Exhaust Hoods- Chapter 5: Exhaust SystemDesign ProcedureChapter 3 describes hood types, hood design factors, and design for ventilation of hot processes. It provides the procedure for estimating the air removal rate that will capture emissions vented by a hot process for a given hood design.2) Chapter 5 describes the design procedure for hooding and ducting systems, and provides the method for calculating required information for fan selection.
160 Vent captured emissions through a closed system (except dilution air fabric filter temperature control)Operate in accordance with operation, maintenance, and monitoring (OM&M) plan
162 Feed/Charge Weight Measurement All sources and emission units subject to production-based (lb/ton of feed) emission limits:- Operate a device that recordsthe weight each charge, orproduction weight
163 Operate in accordance with OM&M plan May use production basis instead of feed if:• Production is measured for allemission units within a SAPU
164 All emission limit compliance calculations for SAPUs are based on production
166 Labeling Post visible labels at each: - group 1 furnace - in-line fluxer- scrap dryer/delacquering kiln/decoating kiln
167 Labels identify emission limits and means of compliance, including: - Type of source or emission unit- Applicable operational standardsand control methods- Afterburner operating temperatureand residence timeOperational standards and control methods would include operating parameter ranges, type charge to be used, flux materials, etc.2) Afterburner info for scrap dryer/delacquering kiln/decoating kiln
169 Affected Sources and Emission Units with Fabric Filters Scrap shreddersScrap dryer/delacquering kiln/decoating kilnDross-only furnaceRotary dross coolerIn-line fluxerFor all of these sources with a fabric filter, the following operating requirements apply.
170 Group 1 furnaceMust operate a bag leak detection system or continuous opacity monitorExcept scrap shredders may alternatively choose to monitor VE
204 Site-specific Monitoring Plan For group 1 furnaces without control devices - OM&M plan must include a section that documents work practices and pollution prevention measures, including procedures for scrap inspection
205 Site-specific monitoring plan and testing to demonstrate adequacy of the monitoring plan must be developed in coordination with, and approved by, the permitting authority