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MEMORANDUM

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

From: Mark Bahner and David Green, RTI 

Date: January 4, 2012

Subject: Draft Technology Review for the Secondary Aluminum Production Source 

Category

1.0 BACKGROUND

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

Section 112 of the CAA requires EPA to establish technology-based standards for 

sources of HAP. These standards are often referred to as maximum achievable control 

technology, or MACT standards. Section 112 also contains provisions requiring EPA to 

periodically revisit 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 Emissions Standards for Hazardous Air Pollutants (NESHAP) for 

the Secondary Aluminum Production source category was promulgated on March 23, 2000 (65

FR 1690) as 40 CFR part 63, subpart RRR. The rule was amended at 67 FR 79814, December, 

30, 2002; 69 FR 18803, April 9, 2004; 69 FR 53984, September 3, 2004; 70 FR 75346, October 

3, 2005; and 70 FR 57517, 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, foundries and 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.
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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

(D/F), dioxins and furans are expressed as toxicity equivalents, and hydrogen chloride (HCl) as a 

surrogate for acid gases, including hydrogen fluoride. HAP are emitted from the following 

affected sources: aluminum scrap shredders (regulated for PM), thermal chip dryers (THC and 

D/F), scrap dryers/delacquering kilns/decoating kilns (PM, D/F, HCl and THC), sweat furnaces

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

D/F), and in-line fluxers (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 minimize 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.

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 
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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 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. 

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 test reports were available to support those reported emissions. The D/F 

emissions from these other sources are lower than the D/F emissions from the multichamber 

furnace, indicating that emissions from the multichamber furnace are not lower than any other 

group 1 furnace handling other than clean charge, or any delacquering/decoating kiln. Therefore, 

based on available information, it is not clear that the multichamber furnace technology would 

reduce HAP emissions relative to technologies that 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 

ug/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

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.
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2.1.2. 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. The 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 industry in the U. S., a question was included in an information collection request 

(ICR) sent to all identified secondary aluminum production facilities. The question “Do you use 

catalytic filters for dioxin control (e.g., 

http://www.donaldson.com/en/industrialair/literature/051754.pdf )?” was answered no or “not 

applicable” by 126 of the 159 facilities that responded. The remaining facilities did not answer 

this question. We have insufficient information to conclude that this technology is generally 

applicable to secondary aluminum production facilities, or to estimate the extent of emission 

reductions that it might achieve. 
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2.2 Responses to ICR

In an attempt to identify new emission control technologies in use, an ICR was sent to all 

identified secondary aluminum production facilities. To identify new technologies 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 HCI 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. This technology is suitable for retrofit to existing fabric filters. In addition to the cost of 

the feeder system and carbon supply, all of the added carbon ultimately adds to the mass of dust 

requiring disposal. Carbon injection systems in other industries are typically about 80 to 90% 

efficient at D/F control.

2.2.2 Ammonia Injection for HCl Control

Four respondents reported injecting ammonia into furnace exhaust gas as a means of HCl 

control. This technology was unknown at the time of development of the current rule. At least 

one of the four respondents plans to replace the lime currently used to control HCl emissions 

with ammonia. It is not clear from the ICR responses whether the remaining respondents 

reporting the use of this technology are replacing lime with ammonia or adding ammonia in 

addition to lime. The HAP emission reductions achieved from using this technology alone or in 

addition, to lime injection are also not known. This technology is 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 air emissions of ammonia, which is not a HAP but may be problematic due to 

nitrogen deposition.
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3.0 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. 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. In other industries, such as 

Portland cement and electric arc steel mills, D/F emission reductions of 80-90 percent have been 

achieved with the addition of activated carbon injection. 

In general, existing technologies can be adapted to achieve lower emissions. For 

example, decreased HCl emissions might be achieved by increasing the lime injection rate. 

Decreased THC emissions might be achieved by increasing afterburner temperature. If more 

stringent risk-based standards are justified, it is likely that either improvements to existing 

control devices, implementation of new technologies or pollution prevention techniques will be 

selected on the basis of overall cost and reliability. None of the newer technologies have 

supporting test data that justify more stringent technology-based standards. The technologies 

implemented since the development of the current NESHAP may provide a means for decreasing 

HAP emissions from secondary aluminum production, however there are insufficient data to 

justify more stringent technology-based standards for either new or existing sources.