DATE: October 16, 2014

SUBJECT: Supplemental Proposal Technology Review for the Secondary Aluminum 

Production Source Category 

FROM: Mark Bahner and David Green, RTI, International

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

1.0 BACKGROUND

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

Section 112 of the Clean Air Act (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 technology, 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 Current NESHAP

The current National Emission Standards for Hazardous Air Pollutants (NESHAP) for the 

Secondary Aluminum Production source category were promulgated on March 23, 2000 (65 FR 

15690) as 40 CFR part 63, subpart RRR. The rule was amended at 67 FR 79808, December 30, 

2002; 69 FR 53980, September 3, 2004; 70 FR57513, October 3, 2005; and 70 FR 75320, 

December 19, 2005. The NESHAP applies to affected sources of HAP emissions at secondary 

aluminum production facilities. A secondary aluminum production facility 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 drying, 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 production 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 returns, or internal scrap, and if they do not operate sweat furnaces, thermal chip 

dryers, or scrap dryers/delacquering kilns/decoating kilns.
2

There are 161 secondary aluminum production facilities that are subject to the NESHAP.

Emission limits have been promulgated 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 certain 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 THC 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 controls are also subject to design 

requirements and operating limits to limit fugitive emissions. 

2.0 DEVELOPMENTS IN PRACTICES, PROCESSES, AND CONTROL 

TECHNOLOGIES

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

• add-on control technology that was not identified during the development of the current 

NESHAP for the source category; 

• improvement to an existing add-on control technology that could result in significant 

additional HAP emissions reductions; 

• work practice or operational procedure that was not identified during development of the 

current NESHAP for the source category; or

• applicable process change or pollution prevention alternative that was not identified and 

considered during the development of the current NESHAP for the source category. 

We investigated developments in practices, processes, 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 company 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 scrap 

are swept into another chamber where the delacquered scrap is melted. 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 therefore 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 16 of these furnaces are in operation in Europe, Asia and the Middle East. 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 not produce lower D/F emissions (in toxic equivalents, or TEQs) than any other group 1 

furnace handling 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 other than 

clean (i.e., “dirty”) charge, and three delacquering/decoating kilns. The other furnaces and 

delacquering/decoating kilns in Table 1 were selected because they had low reported D/F 

emissions, and emission test reports were available to support those 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 emission 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

Equipment 

ID

Equipment 

Type

Test Date Test-Condition Average D/F in 

μg/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 1-100% Class I 0.461

351 Logan 

Aluminum

Multichamber 

Furnace

Grp1 dirty 

charge

5/14/2008 2-80% UBC’s/20% 

Class I

0.496
4

RTI 

ID

Facility 

Name

Equipment 

ID

Equipment 

Type

Test Date Test-Condition Average D/F in 

μg/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 dirty 

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 Delacquering 

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, aluminum 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 with 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 current 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 aluminum 

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 scrap 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 eddy 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 catalytic 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 over 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 aluminum 
5

industry in the U. S., the EPA included a question in an information collection request (ICR) sent 

to all identified 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 remaining 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 any secondary 

aluminum facility 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 production 

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 secondary 

aluminum production facilities in the U.S. operate below this temperature, specifically to avoid 

de novo creation of D/F in the fabric filter, which 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 necessary 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 300 degrees Fahrenheit to avoid de novo synthesis of D/F, and the need to draw in 

large amounts of ambient air into hoods to meet ACGIH guidelines.

Therefore, the EPA cannot conclude that fabric filter bags are more effective at reducing D/F 

emissions at secondary 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 Secondary Aluminum Production source category 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 

combustion 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) temperature 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 operation (for sweat furnaces, 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, must 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 the 

Secondary Aluminum 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 identified 
6

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 review 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 aluminum production facilities. The 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 

matter or HCl 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 barriers 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 Injection 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 that 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 for 

multipathway risks from D/F.2

2.2.2 Ammonia Injection for HCl Control

Three respondents reported adding injecting ammonia into furnace exhaust gas as a means of 

HCl control. Another respondent plans to replace the lime currently used to control HCl 

emissions with ammonia. We were 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 in addition to lime currently used. Further, we 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 fabric 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 disposal, 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 injection.
7

3.0 DIOXIN/FURAN LIMIT ANALYSIS

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 to 10 μg 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 μg 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 would result 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 approximately $3,800,000 per gram TEQ of D/F.

4.0 CONCLUSIONS: RECOMMENDED REVISIONS BASED ON DEVELOPMENTS 

IN PRACTICES, PROCESSES, AND CONTROL TECHNOLOGIES

This review identified several developments in practices, processes, or control technologies that 

have been implemented in this source category since promulgation of the current NESHAP.

However, these 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 to 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 were 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 furnaces. 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 processing to produce 

an aluminum ingot or sow.

• Catalytic Filter Bags – The EPA requested all facilities potentially 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 minimum 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, and because large volumes of ambient air must be drawn into 

furnace hoods to promote effective capture. Therefore, we cannot conclude that fabric 
8

filter bags are more effective in reducing D/F emissions at secondary aluminum facilities 

than control technologies 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 aluminum furnaces, since secondary aluminum 

furnaces burn natural gas rather than waste. One GCP parameter that is applicable to the 

secondary aluminum industry is to monitor fabric filter inlet temperature; this must 

already be monitored in the existing NESHAP. 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 investigated other work 

practices such as better scrap inspection and monitoring. 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 – Three facilities reported using activated carbon injection to 

control D/F. This technology was identified at 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 lime injection, so it is 

not possible 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 whether 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 

Processing Conference. Available at: 

http://www.seas.columbia.edu/earth/wtert/sofos/nawtec/1992-National-Waste-ProcessingConference/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 the Secondary Aluminum Source Category.”

October 2014. Available in EPA docket for Secondary Aluminum Production Risk and 

Technology Review.