DATE: October 16, 2014

SUBJECT: Supplemental Proposal Technology Review for the Secondary Aluminum Production Source Category

F ROM : Mark Bahner and David Green

, RTI , International

TO: Rochelle Boyd, U.S. Environmental Protection Agency, OAQPS

1.0 BACKG ROUND

1.1 Requirements of Section 112(d)(6) of the CAA

Section 112 of the C lean A ir A ct (CAA) requires the EPA to establish technology

- based standards for sources of HAP. These technology

- based standards are often referred to as maximum achievable control tech nology, or MACT, standards. Section 112 also contains provisions requiring the EPA to periodically review these standards. Specifically, paragraph 112(d)(6) states:

(6) REVIEW AND REVISION.

– The Administrator shall review, and revise as necessary (taking into account developments in practices, processes, and control technologies), emissions standards promulgated under this section no less often than every 8 years.

1.2 Description of the Secondary Aluminum Production Source Category and Requirements of the Cur rent NESHAP The current National Emission Standards for Hazardous Air Pollutants (NESHAP) for the Secondary Aluminum Production source category were promulgated on March 2 3, 2000 (6 5 FR 1 5 690 ) as 40 CFR part 63, subpart RRR

. The rule was amended at 67 FR 7 9808

, December 30, 2002; 69 FR 53980 , September 3, 2004; 70 FR 57513 , October 3, 2005 ; and 70 FR 75320

, Dec ember 19, 2005. The NESHAP applies to affected sources of HAP emissions at secondary aluminum production facilities. A secondary aluminum production f acility is defined as any establishment using clean charge, aluminum scrap or dross from aluminum production, as the raw material and performing one or more of the following processes: scrap shredding, scrap drying/delacquering/decoating, thermal chip dryi ng, furnace operations (i.e., melting, holding, sweating, refining, fluxing, or alloying), recovery of aluminum from dross, in

- line fluxing or dross cooling. A secondary aluminum production facility may be independent or part of a primary aluminum producti on facility. For purposes of the NESHAP, aluminum die casting facilities, aluminum foundries and aluminum extrusion facilities are not considered to be secondary aluminum production facilities if the only materials they melt are clean charge,
customer retu rns, or internal scrap, and if they do not operate sweat furnaces, thermal chip dryers, or scrap dryers/delacquering kilns/decoating kilns.2

T here are 161 secondary aluminum production facilit ies that are subject to the NESHAP. Emission limits have been pro mulgated for particulate matter (PM) as a surrogate for metal HAP, total hydrocarbons (THC) as a surrogate for organic HAP other than dioxins and furans, dioxins and furans (D/F) expressed as toxicity equivalents, and hydrogen chloride (HCl) as a surrogate for HCl, hydrogen fluoride and chlorine. HAP are emitted from the following affected sources: aluminum scrap shredders (regulated for PM), thermal chip dryers (regulated for THC and D/F ) , scrap dryers/delacquering kilns/decoating kilns (regulated for PM, D/F, HCl and THC ) , sweat furnaces (regulated for D/F), dross

- only furnaces (regulated for PM), rotary dross coolers (regulated for PM), group 1 furnaces (regulated for PM, HCl and D/F), and in

- line fluxers (regulated for PM and HCl). Group 2 furnaces and c ertain in

- line fluxers are regulated by work practices.

Control devices currently in use to reduce emissions from affected sources subject to the NESHAP include fabric filters for control of PM from aluminum scrap shredders ; afterburners for control of TH C and D/F from thermal chip dryers ; afterburners plus lime

- injected fabric filters for control of PM

, HCl, THC and D/F from scrap dryers/delacquering kilns/decoating kilns ; afterburners for control of D/F from sweat furnaces ; fabric filters for control of PM from dross

- only furnaces and rotary dross coolers ; lime

- injected fabric filters for control of PM and HCl from in

- line fluxers ; and lime

- injected fabric filters for control of PM, HCl and D/F from group 1 furnaces. All affected sources with add

- on contr ols are also subject to design requirements and operating limits to limit fugitive emissions

.

2.0 DEVELOPMENTS IN PRAC TICES, PROCESSES, AN D CONTROL TECHNOLOGIES

For the purposes of this technology review, a “development” was considered to be a (n):

• add

- on co ntrol technology that was not identified during the development of the current NESHAP for the source category;

• i mprovement to an existing add

- on control technology that could result in significant additional HAP emissions reductions;

• w ork practice or ope rational procedure that was not identified during development of the current NESHAP for the source category; or

• applicable p rocess change or pollution prevention alternative that was not identified and considered during the development of the current NESH AP for the source category.

We investigated developments in practices, proce sses, and control technologies through a literature review and discussions with industry representatives, and included questions in a Section 114 information collection request ( ICR) that was sent to all companies thought to be subject to the NESHAP. The results of these analyses are presented in the following sections.3

2.1 Literature review and industry contacts

2.1.1 Multichamber Delacquering Kiln/Melting Furnace

At least one co mpany supplies multichamber furnaces that combine the functions of a delacquering kiln and a melting furnace. This furnace has the potential to reduce emissions

, because all of the emissions from the delacquering of used beverage cans and other coated scra p are swept into another chamber where the delacquered scrap is melt ed

. These emissions are combusted in the melting chamber, reducing energy requirements; destroying THC and D/F; and eliminating the need for an afterburner. A multichamber furnace can ther efore be used as a replacement for a delacquering/decoating kiln (with afterburner) plus a group 1 furnace handling only clean charge, or the multichamber furnace can be used as a replacement for group 1 furnace handling other than clean charge.

At least 1 6 of these furnaces are in operation in Europe, Asia and the M iddle E ast. One furnace of this type is presently operating in the U. S. and is permitted as a group 1 furnace handling other than clean charge

.
The emissions test data for the one multichamber furnace operating in the U.S. indicate that the furnace produces D/F emissions that are within the range of emissions test data for other group 1 furnaces handling other than clean charge

, and delacquering/decoating kilns. Thus, the multichamber furnace D/ F test data are within the range of other equipment using control technology considered by the EPA in the Subpart RRR NESHAP. The multichamber furnace does n ot produce lower D/F emissions (in toxic equivalents, or TEQs) than any other group 1 furnace handl ing other than clean charge, or than any delacquering/decoating kiln , as shown in Table 1 . Table 1 lists D/F emissions from the one multichamber furnace

, operating at Logan Aluminum. Table 1 also lists D/F emissions from three group 1 furnaces handling oth er than clean (i.e., “dirty”) charge, and three delacquering/decoating kilns. The other furnaces and delacquering/decoating kilns in Table 1 w ere selected because they had low reported D/F emissions, and emission test reports were available to support thos e reported emissions. The D/F emissions from these other sources are lower than for the multichamber furnace

. Therefore, based on available information, we are unable to conclude that the multichamber furnace technology reduces HAP emissions to lower emiss ion levels than technologies that were considered in promulgating the subpart RRR NESHAP and are already used by other facilities in the U.S.

Table 1. Comparison of D/F Emissions from a Multichamber Furnace with Other Technologies
RTI ID Facility Name Equ ipment ID Equipment Type Test Date Test

- Condition Av erage D/F in
μ g/Mg TEQ (1) 351 Logan Aluminum Multichamber Furnace Grp1 dirty charge 5/13/2008 1

- 50%Class I/50% Class III 1.061 (2)

351 Logan Aluminum Multichamber Furnace Grp1 dirty charge 5/13/2008 1

- 1 00% Class I 0.461

351 Logan Aluminum Multichamber Furnace Grp1 dirty charge 5/14/2008 2

- 80% UBC’s/20% Class I 0.4964

RTI ID Facility Name Equ ipment ID Equipment Type Test Date Test

- Condition Av erage D/F in
μ g/Mg TEQ (1) 351 Logan Aluminum Multichamber Furnace Grp1 dirty charge 8/12/2008 1

- 50%Class I/50% Class III 0.26

421 Alcan Rolled Products DC1M Grp1 d irty charge 1/29

- 31/2008 1 0.023

335 Jupiter Aluminum Furnace 2 Grp1 dirty charge 1/25/2010 1 0.027

211 Alumax Texarkana EPN 011A Grp1 dirty charge 4/20/2009 1 0.103

198 Novelis P9A Delacquering Kiln 10/01

- 02/2008 1 0.000419

198 Novelis P9B Delacquerin g Kiln 9/30

- 10/1/2008 1 0.000173

415 JL French P30

- 1 Delacquering Kiln 6/22/2009 1 0.02

(1) Average of three test runs, except where noted. (2) Average of two test runs.

2.2.2 Eddy Current Separators

Sweat furnaces are used in the secondary aluminum industry to separate aluminum from ferrous metals. Certain types of scrap , primarily automotive, are composed of individual pieces of metal which contain both aluminum and iron or steel. Automobile parts such as aluminum engine blocks with cast iron cylinders, alumin um transmission cases with steel gears and inserts and aluminum suspension components with steel inserts are examples of sweat furnace feed. These materials, often containing oil and grease, are separated by melting the aluminum from the ferrous metals wit h higher melting points. The molten aluminum is tapped to form ingots or “sows,” and the ferrous residue is raked from the furnace. Sweat furnace emissions contain D/F

, which results from the combustion of the organic contaminants in the scrap

. Eddy curre nt separators are used to separate a concentrated aluminum fraction from a heterogeneous scrap feed. These units operate at ambient temperature and emit no D/F or other gaseous pollutants. Eddy current separators are used to separate a concentrated aluminu m fraction from a heterogeneous scrap feed. These units operate at ambient temperature and emit no D/F or other gaseous pollutants. They are used on the material output from mechanical shredders that shred automobiles and appliances (not on the aluminum sc rap shredders used in the secondary aluminum industry). These units can potentially decrease the need for sweat furnaces. However, the product of eddy current separators is not an aluminum ingot or sow, as with a sweat furnace. Therefore, the product of ed dy current separators must undergo further processing to produce an aluminum ingot or sow , and it is not possible to directly compare eddy current separators with sweat furnaces.

2.1.3 Catalytic Filter Bags Catalytic filtration systems, including catalyt ic filter bags, are available to reduce D/F emissions. These bags incorporate an expanded polytetrafluoroethylene membrane coated with a precious metal catalyst which promotes the oxidation of D/F. One manufacturer claims that this system is installed in o ver 100 applications around the world, including at least one secondary aluminum processing plant

. To determine the extent that these bags are in use in the secondary aluminum5

industry in the U. S., the EPA included a question in an information collection request ( ICR ) sent to all ide n tified secondary aluminum production facilities. The question “ Do you use catalytic filters for dioxin control

. . . ) ? ” was answered “ no ” or “ not applicable ” by 126 of the 159 facilities that responded to the ICR . The remainin g facilities did not answer this question. Some, or all, of the blank responses and the “not applicable” responses are attributable to facilities that do not operate fabric filters

. Therefore, the EPA has no information about a ny secondary aluminum facilit y in the U.S. currently using catalytic filter bags , and no specific secondary aluminum facility in another country that uses catalytic filter bags has been identified

. Catalytic fabric filter bags are potentially problematic for the secondary aluminum pro duction industry because they require a minimum fabric filter inlet temperature of approximately 300 degrees Fahrenheit to produce the catalytic oxidation of D/F . Many fabric filters at se condary aluminum production facilities in the U.S. operate below thi s temperature , specifically to avoid de novo creation of D/F in the fabric filter , w hich occurs at temperatures from approximately 300 to 840 degrees Fahrenheit (150 to 450 degrees Celsius)

, 1 and because large amounts of ambient air flow into hoods are nec essary to meet design guidelines of the American Council of Governmental Industrial Hygienists (ACGIH). Therefore, the fact that catalytic filter bags require a temperature above approximately 300 degrees Fahrenheit conflicts with a need to remain below 30 0 degrees Fahrenheit to avoid de novo sy n thesis of D/F, and the need to draw in large amounts of ambient air into hoods to meet ACGIH guidelines.

Ther e fore, the EPA cannot conclude that fabric filter bags are more effective at reducing D/F emissions at sec ondary aluminum production facilities than the control technologies considered by the EPA in the 2000 Subpart RRR NESHAP. Catalytic filtration systems are not at present a demonstrated control technology for the S econdary A luminum P roduction source categor y that should be used as the technical basis to require more stringent emission limits for the source category.

2.1.4 Work Practices: Good Combustion Practices D/F emissions in municipal and medical waste combustors are controlled in part through “good

c ombustion practice (GCP).” For municipal waste combustors, the major technical objectives of GCP were determined to be achieved by monitoring and controlling: (a) the flue gas concentration of CO; (b) steam load (a surrogate for PM carryover) and (c) tempe rature at the inlet of the PM control device. 1 The first two parameters are not applicable in the operation of secondary aluminum furnaces and kilns, since the fuel in secondary aluminum is not waste, but is instead typically natural gas. [Afterburner oper ation (for sweat fu rna ces, chip dryers and delacquering kilns/decoating kilns/scrap dryers) is presently subject to inspection for burners and proper adjustment of combustion air.] The third parameter, temperature at the inlet of the PM control device, mus t already be monitored in the existing NESHAP. Therefore, GCP, as it relates to D/F formation in secondary aluminum production, is already addressed by the existing NESHAP , and is not a new development in practices, processes, or control technologies for t he S econdary A luminum source category under section 112(d)(6).

2.1.5 Other Work Practices

The EPA investigated other work practices such as better scrap inspection and cleaning, and process monitoring. However, no such practices were identified that were not already identified6

at the time of the original NESHAP. For example, the issue of scrap inspection was investigated extensively in the development of the original NESHAP , and no sampling or analytical procedures were identified then or in our present r eview that can determine whether scrap of unknown origin is completely free of paints , coatings, or lubricants

.
2.2 Responses to ICR In an attempt to identify developments in emission control technologies in use, an ICR was sent to all identified secondary al uminum production facilities. T he following questions were asked:

• Please provide details for any alternative control devices (i.e., control devices other than fabric filters, lime

- coated fabric filters, or afterburners), monitoring (including particulate

m atter or HC l continuous emissions monitors), or operating conditions at this facility for equipment regulated under 40 CFR 63, subpart RRR.

• Have you injected activated carbon or other type of sorbent for HAP control (excluding research efforts)? What barr iers do you envision to adding carbon injection to fabric filters for HAP control?

• Do you have any plans to install any new higher efficiency rated control devices or have any pending applications to add on any new controls?

2. 2 .1 Activated Carbon Injec tion for D/F Control

Three respondents reported using activated carbon injection for control of dioxin, and one respondent reported using activated carbon injection previously on a unit that has since been shut down. Activated carbon is typically added to control D/F, although in one case it was used with a thermal chip dryer and may also have helped control THC. This technology was known at the time of the development of the current standard and was regarded as a possible control alternative for sources th at were unable to demonstrate compliance using lime

- injected fabric filters . Therefore, it is not a development under section 112(d)(6). The broader use of activated carbon for D/F control was evaluated as part of demonstrating an ample margin of safety fo r multipathway risks from D/F. 2

2.2.2 Ammonia Injection for HCl Control

Three respondents reported adding injecting ammonia in to furnace exhaust gas as a means of HCl control. Another respondent plans to replace the lime currently used to control HCl emis sions with ammonia

. We w ere unable to determine from the ICR responses whether the remaining respondents reporting the use of this technology are reducing lime usage as a result of using ammonia, or adding ammonia i n addition to l ime currently used

. Furthe r , w e do not have any HCl test data for the furnaces at these four facilities. The HAP emission reductions achieved from using this technology alone or in addition to lime injection are not known. This technology may be suitable for retrofit to existing fa bric filters

. The applicability of this technology is unlikely to be influenced by furnace configuration because the ammonia is added between the furnace and the fabric filter

. It has the potential of decreasing the amount of fabric filter dust requiring d isposal, but would likely result in increased emissions of ammonia (which is not a HAP, but may contribute to nitrogen deposition). We do not have sufficient data to determine whether ammonia injection provides greater control of HCl emissions than lime in jection.7

3.0 DIOXIN/FURAN LIMIT A NALYSIS

The broader use of activated carbon for D/F control was evaluated as part of demonstrating an ample margin of safety for multipathway risks from D/F. 2 The analysis evaluated two options: 1) lower the D/F limit from 15 t o 10 μ g TEQ/Mg for group 1 furnaces processing other than clean charge at all facilities, and 2) lower the D/F limit for Group 1 furnaces processing other than clean charge to 10 μ g TEQ/Mg, after applying a subcategorization that only required facilities with a Group 1 furnace production capacity of more than 200,000 tons per year (tpy) furnaces to meet the lower limit. The lower limit could potentially be met with activated carbon injection systems.
The results of the analysis indicated Option 1 wou ld re sult in a D/F emissions reduction of 0.49 grams toxic equivalency (TEQ), at a cost effectiveness of approximately $2,900,000 per gram TEQ of D/F, and Option 2 would result in a D/F emissions reduction of 0.12 grams TEQ, at a cost effectiveness of approxima tely $3,800,000 per gram TEQ of D/F.

4.0 CONCLUSIONS: RECOMMENDED REVISIONS BASED ON DEVELOPMENT S IN PRACTICES, PROCES SES, AND CONTROL TEC HNOLOGIES

This review identified several developments in practices, processes , or control technologies that have been impl emented in this source category since promulgation of the current NESHAP. However, t hese technologies are not in use by a substantial number of secondary aluminum production facilities in the U. S. One possible reason for this is that facilities are able t o meet the current MACT emission limits without using them.

Specific developments in practices, processes, or control technologies examined included:

• Multichamber Delacquering Kiln/Melting Furnace

– Only one such furnace is currently in use in the U.S. D/ F emissions from this furnace are within the range of other group 1 furnaces handling other than clean charge, and delacquering/decoating kilns. Therefore, we are unable to conclude that this technology reduces HAP emissions relative to technologies that w ere considered by EPA in promulgating the subpart RRR NESHAP and are already used by other facilities in the U.S.

• Eddy Current Separators

– It is not possible to compare eddy current separators with secondary aluminum production equipment such as sweat fu rnaces. Sweat furnaces produce aluminum ingots or sows, whereas eddy current separators simply provide a concentrated aluminum fraction from a heterogeneous scrap stream. The concentrated aluminum fraction from an eddy current separator requires further pr ocessing to produce an aluminum ingot or sow.

• Catalytic Filter Bags

– The EPA requested all facil i ties potential ly subject to Subpart RRR to identify whether they used catalytic filter bags. None used these bags. Further, there is potential problem in that catalytic filter bags require a mini m um temperature of approximately 300 degrees Fahrenheit to destroy D/F, whereas secondary aluminum fabric filters typically operate at temperatures lower than 300 degrees Fahrenheit to avoid de novo synthesis of D/F, an d because large volumes of ambient air must be drawn into furnace hoods to promote effective capture. Therefore, we cannot conclude that fabric8

filter bags are more effective in reducing D/F emissions at secondary aluminum facilities than control technolog ies considered by the EPA in the 2000 Subpart RRR NESHAP.

• Work Practices: Good Combustion Practices (GCP)

– GCP as they relate to reducing emissions from municipal waste combustors and medical waste incinerators are not generally applicable to secondary al uminum furnaces, since secondary aluminum furnaces burn natural gas rather than waste. One GCP parameter that is applicable to the secondary aluminum i ndustry is to monitor fabric filter inlet temperature; this must already be monitored in the existing NES HAP. Therefore, GCP, as it relates to D/F formation in secondary aluminum, is already addressed by the existing NESHAP.

• Work Practices: Other Work Practices

– In addition to GCP, we investigat e d other work practices such as better scrap inspection and moni toring. No sampling or analytical procedures could be identified that could determine whether scrap of unknown origin was completely free of paints, coatings, or lubricants.

• Activated Carbon Injection

– T hree facilities reported using activated carbon inje ction to control D/F. This technology was identified a t the time of the development of the current NESHAP, and so is not a new development . An analysis of the greater use of activated carbon than is currently practiced in the secondary aluminum production industry was performed as part of demonstrating an ample margin of safety for multipathway risks from D/F.

• Ammonia Injection for HCl Control

– Four facilities use ammonia injection for HCl control

. However, three use ammonia injection in combination with l ime injection, so it is not pos sible to separate the HCl control achieved by lime injection with the HCl control achieved by ammonia. The fourth facility had not yet switched to full ammonia injection. The EPA does not have sufficient data to determine whe ther ammonia injection provides greater HCl control than lime injection.

5.0 REFERENCES

1. Kilgroe, James D., W. Steve Lanier, and T. Rob Van Alten. “Development of Good Combustion Practice for Municipal Waste Combustors.” Presented at 1992 National Waste Proces sing Conference. Available at: http://www.seas.columbia.edu/earth/wtert/s ofos/nawtec/1992

- National

- Waste

- Processing

Conference/1992

- National

- Waste

- Processing

- Conference

- 15.pdf. Accessed January 2012

.

2. Bahner, Mark (RTI, International), to Rochelle Boyd (EPA). “Memorandum: Supplemental Proposal Technical Support Document for th e Secondary Aluminum Source Category.” October 2014

. Available in EPA docket for Secondary Aluminum Production Risk and Technology Review.