DATE:	January 30, 2012

SUBJECT:	Draft Technical Support Document for the Secondary Aluminum
Production Source Category

FROM:	Mark Bahner, RTI International

TO:		Rochelle Boyd, U.S. Environmental Protection Agency (the EPA)

The purpose of this memorandum is to document the technical approach and
rationale used to develop certain proposed modifications to the National
Emission Standards for Hazardous Air Pollutants (NESHAP) for Secondary
Aluminum Production (40 CFR Part 63, Subpart RRR). The modifications are
to be proposed in January 2012.

Capture Efficiency Assumption for Uncontrolled Furnaces

Test data related to the capture efficiency for uncontrolled furnaces
were analyzed. Two tests were available. Both were conducted at
Southwire Corporation in Hawesville, KY. Testing was also conducted on
an in-line fluxer, but those results were not included in the analysis.
Testing was performed for PM, HCl and PCDD/PCDF from April 30 – May
02, 2007 at Furnace #5 in Mill 3, as reported on June 26, 2007. Testing
was performed for PM, HCl and PCDD/PCDF from July 17 – 19, 2007 at a
Group 1 furnace located in Rod Mill 1 and reported on September 5, 2007.
Testing was performed on a furnace stack and also on a temporary canopy
hood, which was installed for the test, to capture emissions not
directed through the furnace stack.

One aspect of this testing, regarding sampling time at the canopy hoods
versus the furnace stacks, potentially affects the results. In the
testing reported on June 26, 2007, sampling at the furnace stack was
performed from 7.7 to 8 hours per run, whereas sampling at the canopy
hood was performed for 3.0 to 3.33 hours per run. This is consistent
with the concept that emissions captured by the canopy hood would only
occur during furnace charging, whereas emissions through the furnace
stack would occur throughout the cycle (charging, melting, tapping)
which presumably lasted 7.7 to 8.0 hours. However, in the testing
reported on September 5, 2007, testing at the furnace stack was
performed for 3.2 hours per run, whereas testing at the canopy hood was
performed for 3.0 hours per run. This could mean that the complete
furnace cycle was only 0.2 hours longer than the charging period, or it
could be a mistake in the testing reported on September 5, 2007, such
that the testing at the furnace stack did not occur throughout the
entire furnace cycle. If the testing reported on September 5th was
indeed flawed in that the sampling at the furnace stack did not occur
throughout the furnace cycle, then the ratio of emissions in the canopy
hood stack to total emissions would be biased high.   

The results of the two tests are summarized in Table 1. From Table 1, it
can be seen that the average capture by the furnace stack, for all
pollutants and for both tests, was 71 percent. The EPA has considered
various potential furnace stack capture effiencies and resultant stack
test estimation factors for uncontrolled furnaces. For example, if the
furnace capture efficiency is assumed to be 50 percent, the furnace test
results would need to be multiplied by a factor of 2. If the furnace
capture efficiency was assumed to be 66.67 percent (approximately 67
percent), the furnace test results would need to be multiplied by a
factor of 1.5. The test results in Table 1 support multiplying the
furnace test results by a factor of 1.5, because the average capture
efficiency for all tests was 71 percent, which is slightly higher than
67 percent.

Additional tables related to this analysis are included in Appendix A to
this memorandum. The tables can be summarized as follows:

Table A1: This table presents data from the June 26, 2007 report. The
data included pollutant emissions in pounds per hour and test sampling
time. These are converted into total mass measured, so that the total
emissions from the furnace stack can be compared to the total emissions
in the canopy hood stack.

Table A2: This table presents data from the June 26, 2007 report. The
data are exclusively in pounds and the table includes a calculation of
the percentage of polluetants emitted through the canopy hood stack
versus the total mass of pollutants emitted through both the canopy hood
stack and the furnace stack.

Table A3: This table presents data from the September 5, 2007 report.
The data included pollutant emissions in pounds per hour and test
sampling time. These are converted into total mass measured, so that the
total emissions from the furnace stack can be compared to the total
emissions in the canopy hood stack.

Table A4: This table presents data from the September 5, 2007 report.
The data are exclusively in pounds and the table includes a calculation
of the percentage of polluetants emitted through the canopy hood stack
versus the total mass of pollutants emitted through both the canopy hood
stack and the furnace stack.

Costs for Lowering the Dioxin/Furan (D/F) limit for Group 1 Furnaces

The EPA multipathway screen analysis results indicated exceedances of
worst-case screening levels, which do not necessarily indicate risks;
however, they cannot be ruled out based on the results. 

To evaluate the potential to reduce D/F emissions, our analysis focused
on two options: 1) lower the D/F limit from 15 to 10 µg TEQ/Mg
(micrograms toxic equivalent per Megagram of feed) 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 producing more than 200,000 tpy in group 1 furnaces to meet
the lower limit. These lower limits could potentially be met with
activated carbon injection systems. 

With regard to the first option, based on testing reported in
information collection request responses1,  it was estimated that
approximately 11 facilities would need to reduce their D/F emissions,
and that the costs would be approximately $5.9 million in total capital
costs, with total annualized costs of approximately $2.7 million. This
option was estimated to achieve an approximately 1.66 grams TEQ
reduction of D/F, with an overall cost-effectiveness of approximately
$1.61 million per gram D/F TEQ.

For the second option, again based on testing and production data
reported in information collection responses, approximately 4 facilities
were estimated to  need to reduce their D/F emissions, and that the
costs would be approximately $129,000 in total capital costs, with total
annualized costs of approximately $464,000. This option is estimated to
achieve an aproximately 0.38 grams TEQ reduction of D/F with an overall
cost-effectiveness of approximately $1.22 million per gram D/F TEQ.

Our cost estimates were based on furnaces that were already controlled
by fabric filters simply adding an activated carbon injection system,
which is relatively low in capital cost, but is high in operating costs,
due to the cost of activated carbon. Our cost estimates for uncontrolled
furnaces were based on adding fabric filters and activated carbon
injection systems, which have high capital costs as well as operating
costs. All costs were based on a study done for the costs of adding
fabric filters and activated carbon injection done for a utility in New
Jersey2, with costs adjusted for the lower flow rate for secondary
aluminum furnaces (assumed to be 45,000 acfm, based on ICR responses).

Compliance with Emission Limits during Startup/Shutdown

The EPA is proposing standards for startup and shutdown for all
secondary aluminum process units. The subpart RRR standards would apply
at all times, including periods of startup and shutdown. Because the
scrap processed at secondary aluminum production facilities is the
source of emissions, emissions during startup and shutdown are expected
to be no higher and probably much lower than emissions during normal
operations since no scrap would be processed. Therefore, the agency sees
no reason why the existing standards should not apply at all times.  

For production processes in the secondary aluminum production source
category where the standards are expressed in units of pounds per ton of
feed or similar units (i.e. thermal chip dyers, scrap dryer/delacquering
kiln/decoating kilns, dross-only furnaces, in-line fluxers using
reactive flux and group 1 furnaces), the form of the standard would
raise implementation issues if facilities were simply required
facilities to demonstrate compliance in the exact same way as they do
during normal operations , because the equipment is not receiving feed
material during startup and shutdown periods. For example, the startup
procedure for a furnace consists of gradually heating the furnace to
normal operating temperature, without any addition of feed material.
Since the feed rate is zero, the emission rate per ton of feed would be
calculated to be infinite. 

One possibility would be to have concentration-based limits. However,
these are probably not appropriate for the secondary aluminum industry,
because hooding draws in large amounts of ambient air in order to
increase hooding capture. Therefore, it is expected that emissions
during startup and shutdown will be measured and determined under the
applicable test method in pounds per hour (lb/hr).Under the proposed
rule, to demonstrate compliance during the startup and shutdown periods,
for the emissions standards that are in units of lbs per ton, the
emissions in units of pounds per hour would be divided by the feed rate
in tons per hour (ton/hr) from the most recent or current performance
test and compared to the emission limit for the affected source. For
example, the PM limit for a new or existing group 1 furnace is 0.4
lb/ton. If, during a startup or shutdown, the emission rate determined
under the applicable test method is 2 lb/hr, and the furnace charge rate
during the most recent performance test was 10 tons per hour, the
calculated emission rate for that test during a period of startup or
shutdown would be 0.2 lb/ton of feed (2 lb/hr of PM divided by 10 tons
per hour of feed). This would be in compliance with the PM standard of
0.4 lb/ton of feed. 

Representativeness for Nine-Company HAP Metals and HAP Organics Testing

The EPA used a nine-company ICR to gather testing data that would
correlate emissions of THC surrogate to speciated organic HAPs and
emissions of PM surrogate to speciated metal HAPs. Testing was limited
to nine companies for efficiency and to avoid undue burden to the
industry. The nine companies were chosen primarily because they were
large companies operating many facilities, and because they were
companies that were known to operate major source facilities that had
thermal chip dryers or scrap dryer/delacquering/decoating kilns. Thermal
chip dryers and scrap dryer/delacquering decoating kilns are the only
types of equipment that have THC limits. These two pieces of equipment
were limiting in selecting companies for testing, in that few companies
in the secondary aluminum source category currently operate those pieces
of equipment. Therefore, the sampling for those pieces of equipment was
representative, because the sampling represented a large fraction of
those pieces of equipment operated by the industry. The sampling for HAP
metals in fabric filter dust represented a much smaller fraction of the
industry (less than 10 percent of all pieces of equipment). However,
there were a total of 55 samples analyzed for the full suite of HAP
metals (including arsenic, cadmium, total chromium and hexavalent
chromium, manganese, mercury, nickel, etc.). Because 55 samples were
taken from many facilities owned by nine companies, these results are
believed to be representative of metal concentrations in fabric filter
dust within the secondary aluminum industry and are suitable for use in
developing speciated metal HAP emissions from PM emissions. 

References

Letter, Peter Tsirigotis (U.S. EPA) to Russell Mayfield (Mayfield
Salvage Company) et al., “Requirement to provide information according
to 42 U.S.C 7414,” February 7, 2011. This was the cover letter for the
all-company data collection ICR.

Memorandum, Serpil Guran (New Jersey Department of Environmental
Protection) to William O’Sullivan (New Jersey Department of
Environmental Protection). Subject: Analysis for Coal Burning Boilers
Mercury Emissions Levels and Control Options. May 8, 2003.

List of Tables

  TOC \h \z \t "Table Title,1"    HYPERLINK \l "_Toc315445237"  Table 1.
    Southwire Test Results Summary	  PAGEREF _Toc315445237 \h  6  

  HYPERLINK \l "_Toc315445238"  Table 2.     Group 1 Furnace D/F
Reduction Options	  PAGEREF _Toc315445238 \h  7  

  HYPERLINK \l "_Toc315445239"  Table 3.     Cost-effectiveness
Calculation for D/F Reduction Options	  PAGEREF _Toc315445239 \h  7  

  HYPERLINK \l "_Toc315445240"  Table A1.  Southwire Testing Reported
June 26, 2007: Complete Test Results	  PAGEREF _Toc315445240 \h  9  

  HYPERLINK \l "_Toc315445241"  Table A2.  Southwire Testing Reported on
June 26, 2007: Results in Pounds	  PAGEREF _Toc315445241 \h  10  

  HYPERLINK \l "_Toc315445242"  Table A3.  Southwire Testing Reported
September 5, 2007: Complete Test Results	  PAGEREF _Toc315445242 \h  11 


  HYPERLINK \l "_Toc315445243"  Table A4.  Southwire Testing Reported on
September 5, 2007: Results in Pounds	  PAGEREF _Toc315445243 \h  12  

 

Table 1. Southwire Test Results Summary 

Test Report Date	Pollutant	Three-run Average

Fraction in Furnace Stack	Three-run Average

Fraction in Canopy Hood Stack

June 26, 2007	PM	0.78	0.22

June 26, 2007	HCl	0.81	0.19

June 26, 2007	D/F	0.97	0.03

Sept. 5, 2007	PM	0.49	0.51

Sept. 5, 2007	HCl	0.77	0.23

Sept. 5, 2007	D/F	0.42	0.58

Average for all	All	0.71	0.29



Table 2. Group 1 Furnace D/F Reduction Options 

Option	Furnace Status	Number of Furnaces	Capital Cost1 Each (2011 $)
Annual Operating Cost Each

(2011 $)	Combined Total Capital Cost (2011$)	Combined Total Annualized
Cost (2011$)

Limit of 10 µg/Mg TEQ for all	Controlled	11	32,478	115,983	5,910,258
2,680,713

Limit of 10 µg/Mg TEQ for all	Uncontrolled	9	617,000	156,100



Limit of 10 µg/Mg TEQ if production >200,000 tpy	Controlled	4	32,478
115,983	129,912	463,932

Limit of 10 µg/Mg TEQ if production >200,000 tpy	Uncontrolled	0	617,000
156,100





Table 3. Cost-effectiveness Calculation for D/F Reduction Options 

Option	Combined Total Annualized Cost (2011$)	Annual D/F Emission
Reduction (grams TEQ)	D/F Removal Cost Effectiveness

($/gram TEQ)

Limit of 10 µg/Mg TEQ for all	2,680,713	1.66	1,610,000

Limit of 10 µg/Mg TEQ if production >200,000 tpy	463,932	0.38	1,220,000



Appendix A

Southwire Test Results

Table A1.  Southwire Testing Reported June 26, 2007: Complete Test
Results 

* reported as 2378-TCDD equivalent

Table A2.  Southwire Testing Reported on June 26, 2007: Results in
Pounds

Table A3.  Southwire Testing Reported September 5, 2007: Complete Test
Results

Table A4.  Southwire Testing Reported on September 5, 2007: Results in
Pounds

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