MEMORANDUM

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

From:		Mark Bahner and David Green, RTI  

Date:	DATE:	January 430, 2012

SubjectSUBJECT:	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 169015690) as 40 CFR part 63,
subpart RRR. The rule was amended at 67 FR 7981479808, December, 30,
2002; 69 FR 18803, April 9, 2004; 69 FR 5398453980, September 3, 2004;
70 FR 75346FR57513, October 3, 2005; and 70 FR 5751775320, 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 (D/F),, dioxins
and furans are(D/F) expressed as toxicity equivalents, and hydrogen
chloride (HCl) as a surrogate for acid gases, includingHCl, 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 minimizelimit 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 the D/F emissions fromfor 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 clearwe are unable to conclude that the
multichamber furnace technology would reducereduces 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.

2.12.2. Eddy Current Separators

Sweat furnaces are used in the secondary aluminum industry to separate
aluminum from ferrous metals. Certain types of scrap (primarily
automotive) 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. TheOne 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 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.,   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. We(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 have
insufficientno information to conclude that this technology is generally
applicable to about any secondary aluminum production facilities, or to
estimate the extent of emission reductionsfacility in the U.S. currently
using catalytic filter bags, and no specific secondary aluminum facility
in another country that it might achieve. uses catalytic filter bags has
been identified.

Catalytic fabric filter bags are potentially problematic for the
secondary aluminum production industry because they require a
mininumminimum 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, w (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 hood 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 Ssecondary Aaluminum
Pproduction source category that should be used as the technical basis
to require more stringent emission limits for the secondary alumium
production 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 Ssecondary Aaluminum 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 newdevelopments in emission control
technologies in use, an ICR was sent to all identified secondary
aluminum production facilities. To identify new technologies the 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 HCIHCl
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.; 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. This technology was unknown at the time
of development of the current rule. At least one One of the four
respondents plans to replace the lime currently used to control HCl
emissions with ammonia. It is not clear The EPA was unable to determine
from the ICR responses whether the remaining respondents reporting the
use of this technology are replacingreducing lime with 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 also not known.
This technology ismay 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 be problematic duecontribute 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. These 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. 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.  

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. 

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