MEMORANDUM

DATE:	January 30, 2012

SUBJECT:	Draft 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

Background

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

Section 112 of the 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 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.

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 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.

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.  

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.

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 relative
to technologies that were considered by the EPA 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 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



RTI ID	Facility Name	Equipment ID	Equipment Type	Test Date
Test-Condition	Average D/F in ug/Mg TEQ(1) 

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

Average of three test runs, except where noted.

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 industry in
the U. S., 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 (e.g.,  
HYPERLINK
"http://www.donaldson.com/en/industrialair/literature/051754.pdf" 
http://www.donaldson.com/en/industrialair/literature/051754.pdf )?”
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 development in practices, processes, or control
technologies for the Secondary Aluminum source category under section
112(d)(6). 

2.1.5 Work Practices: 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 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.  

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; 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

Four respondents reported adding injecting ammonia into furnace exhaust
gas as a means of HCl control. One of the four respondents plans to
replace the lime currently used to control HCl emissions with ammonia.
The EPA was 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 technologically 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 contribute to nitrogen deposition). The EPA
does not have sufficient data to determine whether ammonia injection
provides greater control of HCl emissions than lime injection.

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 heterogeneneous 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 potential
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 mininum 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 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. 

References

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:   HYPERLINK
"http://www.seas.columbia.edu/earth/wtert/sofos/nawtec/1992-National-Was
te-Processing-Conference/1992-National-Waste-Processing-Conference-15.pd
f. Accessed January 2012" 
http://www.seas.columbia.edu/earth/wtert/sofos/nawtec/1992-National-Wast
e-Processing-Conference/1992-National-Waste-Processing-Conference-15.pdf
. Accessed January 2012 .

Bahner, Mark (RTI, International), to Rochelle Boyd (EPA).
“Memorandum: Draft Technical Support Document for the Secondary
Aluminum Source Category.” January 2012. Available in EPA docket for
Secondary Aluminum Production Risk and Technology Review. 

  PAGE   \* MERGEFORMAT  1 

