VIRGINIA DEPARTMENT OF ENVIRONMENTAL QUALITY 

Valley Regional Office 

INTRA-AGENCY MEMORANDUM 

441 I Early Road - P. O. Box 3000 Harrisonburg, VA 22801-3000 

Permit Writer Laura R Justin Date 12/23/09 

Air Permit Manager (j~/o1 7<- Date 

Deputy Regional 

Director Date 

Memo To Air Permit File Date 

Description 

Registration 

Number 80252 

County-Plant I.D. 51-171-0003 

UTM Coordinates 

(Zone 17) 731.3 

Elevation 

(feet) 630 

Distance to Nearest 

Class I Area 

(select one) -22 

FLM Notification 

Required 

(YIN) Y 

AIRS Classification Before permit After permit 

(A,SM, B) A Action A Action 

Pollutants for Which 

the Source is Title V S02, NOx, Before permit S02, NO" After permit 

Major PM-lO, CO action PM-I0, CO Action 

PSD Major Source Before pel'mit After permit 

(YIN) Y action Y Action 

Pollutants for Which 

The Source is PSD S02, NOx, Before permit S02, NOx, After permit 

Major PM-I0, CO action PM-lO, CO Action 
I. Introduction 

O-N Minerals (Chemstone) Company - Strasburg Facility 

Engineering Memo for BART Determination 

Page 2 

On July 1, 1999, the U. S. Environmental Protection Agency (EPA) promulgated its 

Regional Haze Rule (40 CFR Part 51). The objective of the rule is to improve visibility 

in the 156 national parks and wilderness areas around the country known as Class I areas. 

There are two Class I areas within Virginia: Shenandoah National Park (SNP) and the 

James River Face Wilderness Area (JRFWA). 

According to the Regional Haze Rule, states must require certain older, large facilities to 

install emission controls as part of the state's strategy to meet regional haze improvement 

goals. The requirement applies to such plants emitting pollutants that contribute to 

visibility degradation and is known as the Best Available Retrofit Technology (BART) 

requirement. EPA published amendments to the Regional Haze Rule and final BART 

guidelines July 6, 2005. According to the guidelines, there are three criteria for 

determining which sources are potentially subject to BART (i.e., "BART-eligible" 

sources): 

1. The emission unit must have been in existence prior to August 7, 1977 and begun 

operation after August 7, 1962. 

2. The emission unit must be located at a facility which falls into one of26 categories. 

3. The aggregate potential emissions of all emission units identified in Items 1 and 2 

must be greater than or equal to 250 tons per year of any visibility impairing 

pollutant. The pollutants that reduce visibility include particulate matter (PM -10 

and PM2.5), and compounds which contribute to PM2.5 fOlmation, such as 

nitrogen oxides (NOx), sulfur dioxides (S02), and under certain conditions volatile 

organic compounds, and ammonia. 

After the BART eligible units in the state were identified, each facility had the option 

of either conducting BART exemption modeling to detelmine the aggregate impact of 

the BART eligible emissions units or proceeding straight to the BART permitting 

process. 

The O-N Minerals (Chemstone) Company - Strasburg Facility (Chemstone) is a lime 

manufacturing plant located on State Route 629 in Shenandoah County. Lime 

manufacturing is one of the 26 categories identified by EPA for BART eligibility. 

Chemstone received its first air permit in 1973. The aggregate potential emissions of 

NOx exceed 250 tons per year (tpy). Two BART-eligible units at Chemstone were 

identified: the rotary and calcimatic kilns. 

In September 2006, Chemstone submitted a BART Applicability Analysis that included 

refined modeling (Attachment A). According to the analysis, the predicted visibility 

impacts attributable to its kilns exceeded the threshold (0.5 deciview) above which a 

source is considered to contribute to visibility degradation. Accordingly, Chemstone was 
O-N Minerals (Chemstone) Company - Strasburg Facility 

Engineering Memo for BART Detetmination 

Page 3 

required to submit a permit application identifying the BART-eligible emissions units 

and the appropriate BART controls. Since Chemstone's potential emissions of S02 and 

PM-I0 exceed the de minimis tlll"esholds, BART analyses are required for S02 and PM10 as well as for NOx• 

According to EPA's BART guidelines, for each BART-eligible source and each 

pollutant, the BART analysis should identify the best system of continuous emission 

reduction taking into account: 

1. The available retrofit control options; 

2. Any pollution control equipment in use at the source; 

3. The costs of compliance with control options; 

4. The remaining useful life of the facility; 

5. The energy and non-air quality environmental impacts of control options; 

and 

6. The visibility impacts analysis. 

Once the BART determination for each emissions unit/pollutant is made, the 

requirements are to be written in a state operating permit as federally enforceable 

conditions and submitted to EPA as part the Virginia State Implementation Plan (SIP). 

On February 26, 2007, Valley Regional Office (VRO) received Chemstone's permit 

application and accompanying BART determination analysis. Supplemental information 

was also received, submitted in response to requests by DEQ, dated April 27, 2007, May 

31,2007, July 12, 2007, August 30, 2007, September 27,2007, October 30, 2007, 

December 5, 2007, January 7,2008, March 17,2008, July 15, 2008, April 3, 2009, May 

8,2009, and June 4, 2009. The submittals are appended (Attachments B through Land 

Q). 

II. Emission Units I Process Descriptions 

Chemstone operates two lime kilns that are subject to a BART analysis: a rotary kiln and 

a calcimatic kiln. The visibility impairing pollutants emitted from the units are NO" PM10 andS02. 

The rotary kiln system, constructed in 1974, consists of a preheater, kiln and cooler. 

Approved fuels for the rotary kiln are coal, distillate oil and natural gas. Its rated 

capacity is 50 tons per hour limestone feed input (25 tons lime per hour output). 

Chemstone's application indicates that the heat input capacity for the kiln varies 
O-N Minerals (Chemstone) Company - Strasburg Facility 

Engineering Memo for BART Determination 

Page 4 

according to fuel used as follows: 135 MMBtu/hr for coal, 125 MMBtu/hr for gas and 

115 MMBtuIhr for oil. A multi cyclone and baghouse control particulate matter. 

Operation of both controls is required in the facility's July 31, 2000 minor new source 

review (NSR) permit and in its Title V federal operating permit. The product cooler is 

not being separately evaluated for BART, because its emissions are routed through the 

rotary kiln and to the baghouse (i.e., its emissions are included in the rotary kiln's BART 

evaluation). 

The calcimatic kiln system was constructed before 1972 and its approved fuels are 

distillate oil, recycled oil and natural gas. Its rated capacity is 16.6 tons/hr limestone feed 

input (8.3 tons/hr output). Heat input capacity for the kiln is 60 MMBtuIhr for either gas 

or oil. Particulate matter emissions are controlled by multiple cyclones and a Venturi 

scrubber. Operation of the controls are enforceable requirements in the facility's May 1, 

2002 minor NSR permit and in its Title V permit. 

III. Regulatory Review - Best Available Retrofit Technology (BART) review 

Review of Chern stone's BART analysis has been conducted in accordance with EPA 

guidance issued July 6, 2005. 

According to 9 VAC 5-80-800 C, DEQ may issue a State Operating Permit (SOP) to 

establish a source-specific emission standard or other requirements necessary to 

implement the federal Clean Air Act or the Virginia Air Pollution Control Law. Thus, a 

SOP is issued to establish BART for subject units. BART for Chemstone, as approved 

by DEQ, will be enforced through issuance of a SOP that will be submitted to EPA as 

part of Virginia's State Implementation Plan (SIP). 

A. Summary of proposed BART 

The BART analysis has resulted in the following control determinations: 
O-N Minerals (Chemstone) Company - Strasburg Facility 

Engineering Memo for BART Detelmination 

Page 5 

Table 1. Chemstone BART determination SUIIIlIlaJY 

Emission Proposed Pollutant Proposed Visibility Class I area 

unit BART controlled BART improvement impacted 

emission on 98th 

limit* percentile 

day (delta 

deciview) 

Combination 

of inherent dry 0.29Ib/tsf, Shenandoah 

sClUbbing in S02 14.71bslhr 0.11 National Park 

kiln and wet (SNP) 

sClUbber 

Rotary kiln Good 

(U5) combustion I. 74 lbs/tsf, practices; NO, 87.01bslhr None SNP 

indirect firing 

system 

Multicyclone PMlPM-IO 0.12Ibsltsf, None SNP & baghouse 6.0lbslhr 

Venturi S02 0.16Ib/tsf, None SNP scrubber 2.6lbs/hr 

Good 0.61Ibs/tsf, Calcimatic kiln combustion NOx None SNP 

(Ul2) _practices 9.81bslhr 

Multicyclones 0.60 lbs/tsf, & Venturi PMlPM-1O None SNP 

scrubber 9.6lbslhr 

* Calculated as a 24-hour average for S02 and as a three-hour average for NOli: and PMlPM-lO. 

B. BART-eligible emission units subject to MACT staudard 

According to EPA's BART guidance at 70 FR 39163-39164, states may rely on MACT 

standards for purposes of BART, unless there are new technologies subsequent to the 

MACT standard's promulgation which would lead to cost-effective increases in the level 

of control. EPA's rationale is that it is unlikely that states will identify emission controls 

more stringent than the MACT standards that are not found to be cost-prohibitive. 

The National Emission Standards for Hazardous Air Pollutants from Lime Manufacturing 

(Lime MACT) were promulgated on January 5, 2004 (40 CFR 63 Subpali AAAAA). 

The Lime MACT limits PM emissions from lime kilns to 0.12 Ibs/ton stone feed (tsf) if a 

dry control device is used or 0.60 Ibs/tsf if a wet scrubber is used. Chemstone has 

submitted stack testing results indicating that the Strasburg facility is not a major source 

of hazardous air pollutants (HAPs) and is therefore not subject to the Lime MACT. 

Previous stack testing of both kilns had indicated that emissions ofPMlPM-10 were 

below the MACT standards. The rotary kiln uses a fabric filter to control emissions, so 

the applicable MACT standard would be 0.12 lbs/tsf. The calcimatic kiln controls 

emissions using a wet scrubber, so the appropriate MACT standard is 0.60 Ibs/tsf. 
O-N Minerals (Chemstone) Company- Strasburg Facility 

Engineering Memo for BART Determination 

Page 6 

No new control technologies for PMlPM-1 0 from lime kilns have emerged since the 

promulgation of the Lime MACT. Accordingly, the PM emission standards in 40 CFR 

63 Subpart AAAAA constitute a BART level of control for both lime kilns. The permit 

limits both PM and PM -10 to the Subpart AAAAA PM emission levels. 

The following table compares previously-reported actual emissions from each kiln with 

the appropriate MACT standard. 

Table 2 Actual emission rates vs MACT standards 

Emission unit Actual emission rate (lb/tsi) 

PM PM-IO 

Rotary kiln (U5) 0.01285' 0.0090' 

Calcimatic kiln (U12) 0.5716' 

a Based on 12/7/04 stack and particle size testmg 

b 40 CFR 63 Subpart AAAAA standard for lime kilns controlled by fabric filter 

C Based on 10/18/01 stack and particle size testing 

0.442' 

d 40 CFR 63 Subpart AAAAA standard for lime kilns controlled by wet scrubber 

Applicable MACT 

PM rate (Ib/tsi) 

0.12" 

0.60a 

In October 2008, Chemstone submitted a repOli of results from stack testing conducted in 

August 2008 on the rotary kiln. PM results from the test are in excess of the MACT 

(proposed BART) limits. No explanation has been offered for the discrepancy between 

the 2004 and 2008 rotary kiln test results. However, a properly operating fabric filter 

should be able to meet the corresponding MACT limit, so the fact that the August 2008 

test results exceed the limit will not preclude use of that limit as BART. However, the 

draft BART permit includes a six-month compliance extension for the PMlPM-lO limits, 

to allow Chemstone to conduct maintenance on the control devices (i.e., the PMlPM-lO 

limits are effective 180 days after the permit effective date). The pelmit requires 

Chemstone to conduct stack testing within 180 days of the permit issuance date to show 

compliance with the PM limits. 

C. Baseline conditions and visibility impacts for BART-eligible units 

Details concerning the baseline conditions modeled to determine visibility impacts and 

the visibility modeling results were provided in Chemstone's September 2006 repOli 

("Best Available Retrofit Technology Applicability Analysis, O-N Minerals (Chemstone) 

Company"). The 2006 refined analysis indicated a 98th percentile impact of 0.744 

deciview (dv), which is above the contribution threshold of 0.5 dv at SNP. The analysis 

is attached (Attachment A). 

Stack testing voluntarily conducted by Chemstone for S02 emissions from the rotary kiln 

on October 30, 2007, indicated that S02 emissions were orders of magnitude higher than 

the rates indicated by previous stack testing (2001) and on which the original BART 

proposal was based. At DEQ's request, Chemstone revised its BART-applicability 

modeling analrsis to reflect the higher baseline emissions of S02. The revised analysis 

indicated a 98t percentile impact of 0.80 dv. The report of the revised analysis is 

attached (Attachment I). 
O-N Minerals (Chemstone) Company - Strasburg Facility 

Engineering Memo for BART Determination 

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In October 2008, Chemstone submitted a report of results of rotary kiln stack testing 

conducted in August 2008. The report indicated PM emissions exceeding those used in 

the BART-applicability modeling (the PM emissions levels modeled were based on a 

2004 stack test). As explained in Section m.B above, the rotary kiln is controlled by a 

multicyclone and baghouse and Chemstone has proposed use of the Lime MACT (40 

CFR 63 Subpart AAAAA) PM limits as BART limits; DEQ has concurred with the 

proposal. EPA's BART guidelines allow use ofa MACT limit as BART (40 CFR 51, 

Appendix Y, Section N.C). Accordingly, the BART determination for PM (fabric filter 

control and the MACT emissions level) would be the same if the visibility impact were 

higher. Therefore, DEQ did not require Chemstone to revise its modeling to reflect the 

PM emission rate measured during the August 2008 test. 

D. BART analysis for BART~eligible emission units 

1. Rotary kiln (US) 

a. NOx 

(1) Step 1: Identify all available retrofit control technologies 

(a) Existing controls: The rotary kiln currently is controlled by proper kiln 

design and operation and by use of an indirect firing system. In the 

indirect firing system, the coal mill air is separated from the pulverized 

fuel, which is stored in a tank. The pulverized fuel is conveyed to the 

burner with the quantity of air that is optimal for flame considerations. 

Indirect-fired cement kilns are believed to emit 20 to 30% less NOx 

than those that are direct-fired; it is not known whether this level of 

control is achieved in lime kilns. Chemstone's actual NOx emissions 

from the rotary kiln are as low, on a lb/tsf basis, as those of recent lime 

kilns listed in EPA's RACTIBACT/LAER Clearinghouse (RBLC) (see 

Attachment M). 

(b ) Available retrofit control tecllllologies 

(i) Selective Catalytic Reduction (SCR) 

(ii) Selective Non-Catalytic Reduction (SNCR) 

(iii) Non-Selective Non-Catalytic Reduction (NSNCR) 

(iv) Low-NOx burner (LNB) 

(v) Proper kiln design and operation 

(vi) Water/steam injection 

(vii) Reburn at the burner (fuel staging) 

(viii) Mid-kiln firing (MKF) 

(2) Step 2: Eliminate technically infeasible options 
O-N Minerals (Chemstone) Company - Strasburg Facility 

Engineering Memo for BART Determination 

Page 8 

(a) Selective Catalytic Reduction (SCR): Selective catalytic reduction 

(SCR) is a post-combustion technique that involves the injection of 

ammonia into the flue gas upstream of a catalyst bed. In the presence 

of a catalyst, the ammonia reacts with the flue gas to reduce NO, to 

nitrogen and water. When operated within an optimum temperature 

range of 480 to 800 of, this technology can result in between 70 and 

90 percent NO, emission reductions on some combustion units. The 

rate of NO. removal increases with temperature, up to a maximum 

removal rate at a temperature between 700 of and 750 of. As the 

temperature increases above the optimum temperature, the NO. 

removal efficiency begins to decrease. Efficient operation of the SCR 

process requires fairly constant exhaust temperatures. Fluctuations in 

exhaust gas temperature reduce removal efficiency. If the temperature 

is too low, ammonia slip occurs. Ammonia slip is caused by low 

reaction rates and results in both higher NO. emissions and 

appreciable ammonia emissions. If the temperature is too high, 

oxidation of the ammonia to nitric oxide can occur. Also, at higher 

removal efficiencies (beyond 80 percent), an excess of ammonia is 

necessary, thereby resulting in some ammonia slip. Other emissions 

possibly affected by SCR include increased paliiculate matter 

emissions (from ammonia salts in a detached plume) and increased 

sulfur trioxide emissions (from oxidation of S02 on the catalyst). 

To avoid fouling the catalyst bed with the particulate matter in the 

exhaust stream, a SCR unit should be located downstream of the 

particulate matter control device. However, due to the low exhaust gas 

temperature exiting the rotary kiln's fabric filter, the exhaust stream 

would need to be reheated (potentially with a heat exchanger) to the 

desired reaction temperature. The source of heat in the heat exchanger 

would be the combustion of fuel that would generate additional NO,. 

Therefore, in addition to storage and handling equipment for the 

ammonia, the required equipment for the SCR system will include a 

catalytic reactor, heat exchanger, and potentially additional NOx 

control equipment for the emissions associated with the heat 

exchanger fuel combustion. 

In addition the handling and disposal of spent catalyst has been 

recognized as an environmental risk and a potential health hazard. 

Additional concerns with a SCR system include the safety and 

environmental hazards involved with storage and use of large 

quantities of ammonia. This technology is not listed in the RBLC for 

kilns in the lime industry and has never been commercially 

demonstrated on a lime kiln. The Ozone Transport Commission has 

concluded that SCR is an infeasible control option for lime kilns 
O-N Minerals (Chemstone) Company - Strasburg Facility 

Engineering Memo for BART Detelmination 

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("Summary of Ozone TranspOli Commission (OTC) Candidate 

Control Measures - Control Measure Summary for Lime Kilns" 

(5/3/06)). Accordingly, SCR has been eliminated as technically 

infeasible for further consideration for BART. 

Update fOllowing FLM comments provided during its 60-day review 

period: On March 2,2009, Don Shepherd of the National Park Service 

(NPS) submitted comments on the draft BART permit provided to the 

FLMs for their 60-day review period. In the comments, NPS 

questioned the technical infeasibility of SCR use prior to the baghouse 

and, asserting that post-baghouse SCR use is technically feasible, 

requested a cost analysis for SCR following the baghouse. Following 

receipt ofNPS' comments, VRO requested that Chemstone address the 

issues raised. A summary ofVRO's conclusions follows. NPS' 

comments are attached as Attachment P. 

• Pre-baghouse SCR: NPS questioned why a high-dust SCR unit 

would not be technically feasible for the rotary kiln when such 

units have been successfully used to control pulverized coal 

boilers (PCBs). As reported in Chemstone's May 8, 2009 

response (attached as Attachment Q), the particulate matter 

control device loading typical for a PCB is approximately 10 

glNm3

, whereas the dust loading for a lime kiln prior to a 

baghouse is typically several times higher, in excess of 80 

glNm3

• A lime kiln's higher dust loading combined with the 

fact that the dust from a lime kiln is primarily calcium oxide 

(CaO), known to deactivate conventional catalysts by its 

conversion to calcium sulfate, further distinguishes the process 

from a typical PCB application. 

Furthermore, there is no record of SCR having ever been used 

to control a lime kiln. There has been very limited use of SCR 

to control cement kilns in Germany (one plant) and Italy (two 

plants), while SCR has not yet been employed in the U.S. to 

control a cement kiln. The most recent information available 

on the Gelman facility indicates that the SCR is no longer 

operating (replaced instead by SNCR) due to various technical 

issues, including inability to achieve the required reduction 

efficiency. The limited data available on one of the Italian 

plants does not establish the SCR unit's ability to consistently 

meet the desired reduction efficiency; there is no publiclyavailable testing data for the second Italian plant. 

Because SCR has never been used to control a lime kiln, it is 

likely that extended pilot-scale trials would be required prior to 
O-N Minerals (Chemstone) Company - Strasburg Facility 

Engineering Memo for BART Determination 

Page 10 

its application on a lime kiln. Accordingly, SCR may not meet 

the definition of "available" technology for a lime kiln given in 

the BART guidelines. As stated in EPA's final BART 

guidelines (at 70 FR 39164): "Technologies which have not yet 

been applied to (or permitted for) full scale operations need not 

be considered as available; we do not expect the source owner 

to purchase or construct a process or control device that has not 

already been demonstrated in practice." Due to its lack of 

successful demonstration on the few cement kilns to which it 

has been applied and given EPA's guidance, SCR is not an 

appropriate candidate at this point for technology transfer 

consideration for BART control of a lime kiln. 

Based on the high dust concentration in the lime kiln's exhaust 

stream, the content of the dust, and the lack of commercial 

demonstration on lime kilns, we find that SCR use prior to the 

baghouse is not a technically feasible control option for 

Chemstone's rotary kiln. 

• Post-baghouse SCR: In its comments, NPS requested that the 

economic feasibility of SCR use following the baghouse be 

evaluated. 

In response to NPS' comments, VRO asked Chemstone to 

conduct a cost analysis for post-baghouse SCR control ofNOx . 

Chemstone's analysis indicates a cost effectiveness of 

$7,400Iton, a cost per ton exceeding that resulting from any 

BART determination of which VRO is aware. As noted above, 

we are unaware of any SCR use on a lime kiln. The cost 

effectiveness calculation did not include pilot testing that 

would therefore likely be required in any proposed application 

of SCR to a lime kiln. VRO finds post-baghouse SCR to be 

economically infeasible for control of the rotary kiln. 

Additionally, the lack of demonstration on a lime kiln cited 

above makes questionable the technical feasibility at this time 

as a BART control. 

Chemstone's responses regarding the FLM comments are appended as 

Attachment Q. VRO's response to the FLMs following evaluation of 

Chemstone's submittals is in Attachment R. 

(b) Non-Selective Non-Catalytic Reduction (NSNCR) (Also referred to as 

staged combustion air): NSNCR is comprised of an initial bum zone 

(oxidizing), a secondary bum zone (reducing), and a final bum zone 

(oxidizing). In the initial bum zone, there is a slight excess air. The 
O-N Minerals (Chemstone) Company - Strasburg Facility 

Engineering Memo for BART Detennination 

Page 11 

highest temperatures are reached here, which generate thermal NOx. 

In the secondary burn zone, a secondary burner injects additional fuel 

into the marginally lean air, creating strongly rich air. In this reducing 

atmosphere, NO is reacted to N as the hydrocarbons and CO scavenge 

oxygen. 

Theoretically, NSNCR can result in NOx reductions of20 to 50 

percent in kilns. Only a few cement kilns use this technology and 

there is no infonnation that any lime kiln uses this technology. 

Process differences between cement and lime production are the 

reason this technology has not been applied to the lime industry. A 

multi-stage preheater and cyclones, which the subject lime kiln does 

not have, are necessary to apply this control technology. As this lime 

kiln does not possess the requisite process equipment for this control 

technology, the control technology is technically infeasible. 

(c) Low-NOx burner (LNB): LNBs reduce the amount of NO x initially 

formed in the flame. The principle of all LNBs is the same: stepwise 

or staged combustion and localized exhaust gas recirculation (i.e. at 

the flame). LNBs are designed to reduce flame turbulence, delay 

fuel/air mixing, and establish fuel-rich zones for initial combustion. 

Due to fuel-rich conditions and lack of available oxygen, formation of 

thelmal NOx and fuel NOx are minimized. 

The RBLC lists one facility for which LNB is the listed control for a 

lime kiln. However, the source has not commenced operation and the 

resulting NOx emissions rate, as listed in the RBLC, is higher than 

Chemstone's actual emission rate as demonstrated through stack 

testing. 

As applied to combustion sources such as boilers, this technology 

requires staged combustion in the primary fuel burning zone. This 

fOlm of combustion has not been achieved in a lime kiln. One reason 

for this is that the required product temperature in a lime kiln is 

approximately 2000 of, so a very hot flame temperature is required. 

This operating requirement is generally not compatible with limiting 

the flame temperature, which is a key aspect of LNB technology. 

Accordingly, this technology is not considered technically feasible for 

lime kilns. 

(d) Water/steam injection: Injection of water or steam into the main flame 

reduces the flame temperature and the generation ofNOx. In some 

industrial applications, NOx can be reduced by as much as 75 percent 

through water/steam injection. Water/steam injection is effective for 

reducing thelmal NOx in natural gas fired boilers and turbines. 
O-N Minerals (Chemstone) Company - Strasburg Facility 

Engineering Memo for BART Determination 

Page 12 

Because of low initial costs, but high operating costs, this technique is 

considered particularly effective for small, single-burner packaged 

boilers that are operated infrequently. Water/steam injection reduces 

flame temperature by absorbing the latent heat of vaporization, which 

results in decreased process efficiency. It is mainly recommended as a 

temporary control measure to reduce NOx during peaking periods. 

The lime kiln at this facility is operated close to 8760 hours per year 

and primarily fueled by coal or coal/fuel oil. Although this technology 

is effective for natural gas fired boilers and turbines that are operated 

infrequently, it has not been utilized on a coal/fuel oil fired lime kiln 

that is operated year-round. Since water/steam injection can decrease 

process efficiency, interfere with product quality, increase CO 

emissions generation, and has not been commercially demonstrated on 

a lime kiln, it is considered technically infeasible. 

(e) Rebul'll at the bUl1ler (fuel staging): Reburn is a NOx control 

technology that involves diverting a portion of the fuel from the 

bUl1lers to a second combustion area (rebul1l zone) above the main 

combustion zone. The NOx produced in the main combustion zone is 

reduced downstream in a second combustion zone. The major 

requirements of rebul'll are to have the fuel feed rate to the main 

combustion zone be reduced and have an equivalent amount of fuel 

being fed to the reburn burners in the rebul1l zone. Reburning would 

require major changes for a lime kiln, which could impact the quality 

of the lime being produced. A lime kiln does not have a "rebul'll 

zone", therefore, this technology has not been previously applied to 

rotary lime kilns. Reburn is not technically feasible. 

(f) Mid-kiln firing (MKF): MKF is a form of staged combustion of fuels. 

A specially designed fuel injection system introduces a second fuel 

source at a mid point in the kiln. This system is typically used in 

cement kilns and allows the fuel to be burned at a material calcination 

temperature of 1,100 of to 1,650 of, which is much lower than the 

burning temperature of 1,950 of to 2,050 of in the lime kiln. Although 

MKF can reduce NOx emissions in cement kilns, it is technically 

infeasible for lime kilns because the addition of fuel to the lime will 

have a negative effect on the quality of the lime produced. 

(3) Step 3: Evaluate control effectiveness of remaining control technologies 

(a) Selective Non-Catalytic Reduction (SNCR): Selective non-catalytic 

reduction (SNCR) is a post-combustion control technique that involves 

injecting ammonia or urea into specific temperature zones in the upper 

ful1lace or convective pass. The reagent reacts with the NOx to form 

Nz, C02 (using urea), and water. In order for SNCR to be technically 
O-N Minerals (Chemstone) Company- Strasburg Facility 

Engineering Memo for BART Dete!mination 

Page 13 

feasible, the location for ammonia/urea injection must meet the 

following criteria: placement of the injector to ensure adequate mixing 

of the ammonia or urea with the combustion gases, residence time of 

the ammonia with the combustion gases, and temperature profile for 

ammonia injection. There is basically one location in a rotary lime 

kiln where the ammonia/urea injection could occur - after the 

particulate matter control device. Ammonia or urea could be injected 

after the fabric filter if it is feasible to install heat exchangers after the 

fabric filter to reheat the exhaust gases back up to the required 

temperature of between 1,600 of and 2,100 of. No data was found on 

the level of emission reduction to be expected for SNCR if applied to a 

lime kiln. However, the Ozone Transport Commission indicates that 

SNCR would achieve a 60% reduction in NOx when applied to cement 

kilns ("Identification and Evaluation of Candidate Control Measures", 

FeblUary 28, 2007). In the absence of lime kiln-specific information, 

the estimate for cement kiln control will be assumed to apply to a lime 

kiln. 

(b) Proper kiln design and operation (good combustion practices): Part of 

Chemstone's kiln design is the indirect firing system, described in 

III.D.I.a(1 )(a) above, which reduces NOx formation by minimizing 

excess air delivered to the combustion chamber. According to 

Chemstone's application, EPA has indicated that indirect-fired cement 

kilns can emit 20-30% less NOx than direct-fired ones. No 

information on reductions achieved in lime kilns was found. 

(4) Step 4: Evaluate impacts and document results 

(a) Impact analysis part I: Costs of compliance 

(i) SNCR: At the request of DEQ, Chemstone provided a cost per 

ton estimate for controlling NOx using SNCR. In doing so, 

Chemstone states that use of SNCR has not been successfully 

demonstrated or achieved in practice on any known lime kilns 

or related process industries. Based on the estimated natural 

gas and ammonia reagent costs, using a conservative 

assumption of$I,OOO,OOO capital costs, and the expected 60% 

control effectiveness, the resulting cost per ton is $17,210, 

annualized!. Chemstone indicates that it is likely that the 

capital costs would be much higher than $1,000,000 

considering the lack of previous application of this technology 

to the industry. DEQ concurs with Chemstone's conclusion 

that SNCR is not economically feasible. 

I The May 31, 2007 SNCR cost analysis, indicating a cost per ton of$12,800, was based on an incorrect rotmy kiln 

exhaust flowrate. The May 2009 cost analysis adjusted the original data to both correct the kiln exhaust flowrate 

and reflect recent decreases in natural gas pricing and resulted in a cost effectiveness of $ 17,21O/ton. 
O-N Minerals (Chemstone) Company - Strasburg Facility 

Engineering Memo for BART Determination 

Page 14 

(ii) Proper kiln design and operation (good combustion practices): 

No cost to implement, as proper kiln design and operation, 

including an indirect firing system, is currently used on the 

rotary kiln. 

(b) Impact analysis part 2: Energy impacts 

(i) SNCR: The primary energy impact from SNCR use is the fuel 

(natural gas) that would be required to operate the control 

device. The costs associated with the natural gas required were 

factored into the costs of compliance to derive the cost per ton 

to control NOx • Additionally, Chemstone's analysis indicates 

that burning the natural gas would result in 4.8 tons per year 

additional NOx emissions (assuming 10w-NOx burners). 

(ii) Proper kiln design and operation (good combustion practices): 

NI A (currently used) 

(c) Impact analysis part 3: Non-air quality environmental impacts 

(i) SNCR: None were identified in the application. 

(ii) Proper kiln design and operation (good combustion practices): 

NI A (currently used) 

(d) Impact analysis part 4: Remaining useful life 

(i) SNCR: The remaining useful life of the unit was not 

considered in the evaluation. 

(ii) Proper kiln design and operation (good combustion practices): 

NI A (currently used) 

(5) Step 5: Visibility impacts 

(a) SNCR: Since SNCR was found to be cost prohibitive, visibility 

impacts resulting from its use were not evaluated. 

(b) Proper kiln design and operation (good combustion practices): N/A 

(currently used) 

(6) Step 6: Propose BART 

The evaluation of available control measures for NOx from lime kilns 

demonstrates that proper kiln design and operation (good combustion 
O-N Minerals (Chemstone) Company - Strasburg Facility 

Engineering Memo for BART Detelmination 

Page IS 

practices) is the only control that is both technically feasible and cost 

effective. In addition to proper kiln design and operation, Chemstone's rotary 

kiln employs an indirect firing system and the resulting NOx emission rate is 

as low as recent RBLC listings for lime kilns. Accordingly, it has been 

determined that use of proper kiln design and operation (good combustion 

practices) and the indirect firing system constitutes BART for NO, from the 

rotary kiln. 

b. S02 

(I) Step I: Identify all available retrofit control technologies 

(a) Existing controls: As a preheater rotary kiln, the unit is expected to 

achieve a significant level of S02 adsorption onto the lime during the 

lime production process. New preheater kilns typically achieve a 

reduction of greater than 90% through such inherent dry scrubbing. 

Recent listings in EPA's RACTIBACTiLAER Clearinghouse (RBLC) 

indicate that a minimum 92% reduction has been required for new 

preheater kilns. 

Chemstone's initial BART proposal for S02 (which proposed basecase or inherent scrubbing as BART) was based on the assumption that 

the unit was achieving S02 reductions greater than 99% through 

inherent scrubbing (based on a 2001 stack test). Stack testing 

conducted in October 2007, however, indicated much higher than 

expected S02 emissions and a removal rate of 55%, considering sulfur 

input from fuel only. (Chemstone's October 2007 stack test report did 

not indicate the sulfur content of the limestone feed used during the 

test. Depending on the limestone sulfur content, it is possible that the 

rotary kiln's inherent removal rate is greater than 55%.) 

To date, Chemstone has provided no clear explanation for the apparent 

increase in S02 emissions (and apparent decrease in inherent 

scrubbing) from the rotary kiln. Further stack testing conducted in 

August 2008 indicated a much lower S02 emission rate, indicative of a 

higher level of inherent scrubbing closer to the 2001 test results. It is 

clear from the disparate test results that the level of inherent S02 

adsorption is variable and dependent on a combination of process 

parameters. Further testing will be conducted in the future (as required 

by the BART permit). For the present; the level of S02 reduction 

achieved in the kiln through inherent scrubbing appears to be less than 

that typically experienced in preheater rotary kilns. 

(b) Available retrofit control technologies 
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Engineering Memo for BART Detelmination 

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(i) Wet sClUbbing with lime 

(ii) Inherent dry sClUbbing (process) 

(iii) Semi-wet sClUbbing (spray dryer adsorber) 

(2) Step 2: Eliminate technically infeasible options 

All of the identified retrofit technologies are technically feasible for 

controlling S02 from the rotary kiln. 

(3) Step 3: Evaluate control effectiveness of remaining control technologies 

(a) Wet scrubbing with lime: Wet S02 sClUbbers operate by flowing the 

gas to be sClUbbed upward tlU'ough a large reactor vessel that has an 

alkaline reagent (limestone or lime) flowing down from the top. A 

series of spray nozzles distribute the reagent throughout the sClUbber 

chamber and thereby mix the gas stream with the alkaline liquid. The 

calcium in the reagent reacts with the S02 in the gas stream to form 

calcium sulfite and/or calcium sulfate that is removed from the 

sClUbber with the sludge and disposed. Wet scrubbing with lime has 

been known to achieve greater than 95% efficiency for acid gas 

removal. 

(b) Inherent dry scrubbing (process): In a lime kiln, S02 that is released 

during lime production will react with the lime in the kiln. The 

amount of S02 adsorbed in the system is a function of not only the 

sulfur in the fuel, but also the sulfur in the limestone feed, the amount 

of sulfur in the product, and the degree of calcium oxidation that takes 

place in the kiln (greater oxidation generally results in more sulfur 

removal). For new preheater kilns, inherent dry sC11lbbing can provide 

control efficiencies greater than 90%. According to one recent stack 

test (October 2007), Chemstone's rotary kiln appears to be achieving 

approximately 55% removal efficiency from inherent sClUbbing. As 

detailed above, other tests have indicated higher removal rates. 

(c) Semi-wet sClUbbing (spray dryer adsorber): Spray dryer systems 

operate by injecting a moist sorbent (normally lime or calcium 

hydroxide) into the sC11lbber. As the hot gas stream mixes with the 

sorbent, water is evaporated. The surfaces of the solid sorbent react 

with S02. The process fOlms a dry waste product that is collected in a 

baghouse. The semi-wet system is sensitive to operating conditions, 

particularly temperature fluctuations. High-temperature gas streams 

reduce the performance of the sC11lbbing system. The semi-wet 

sC11lbber system would need to be located prior to the rotary kiln 

baghouse, where the gas stream temperature is approximately 500 OF. 

Semi-wet sClUbbers have been known to achieve up to 90% removal 
O-N Minerals (Chemstone) Company - Strasburg Facility 

Engineering Memo for BART Detelmination 

Page 17 

efficiency. Chemstone's analysis indicates that the rotary kiln outlet 

gas stream may need to be cooled to enable a semi-wet scrubber to 

achieve that removal level. 

(4) Step 4: Evaluate impacts and document results 

( a) Impact analysis part 1: Costs of compliance 

(i) Wet scrubbing with lime: In its January 7,2008 submittal, 

Chemstone calculates annualized costs per ton for wet 

scrubbing with lime at $4,090 (at 95% removal) and $4,317 (at 

90% removal), each based on control of the proposed 

emissions level and assuming seven percent interest and an 

equipment life of 15 years. DEQ staff adjusted the calculations 

to reflect the guidelines in EPA's Control Cost Manual and 

detelmined annualized costs of$4,007/ton (95% removal) and 

$4,225/ton (90% removal). 

(ii) Inherent dry scrubbing (process): No cost of compliance, as 

this method of control is inherent to the process and is 

currently used. 

(iii) Semi-wet scrubbing (spray dryer adsorber): In its 117108 

submittal, Chemstone calculated an annualized cost for semiwet scrubbing of$5,218 per ton, based on 90% control of 

proposed emissions, seven percent interest and a 15-year 

equipment life. The calculations do not appear to include the 

cooling system likely needed to reduce the temperature of the 

rotary kiln outlet (inlet to adsorber). 

(b) Impact analysis part 2: Energy impacts 

(i) Wet scrubbing with lime: Electricity would be required to 

operate the wet scrubber. Electrical costs were accounted for 

in calculating the annualized cost per ton for wet scrubbing. 

(ii) Inherent dry scrubbing (process): NI A (currently utilized). 

(iii) Semi-wet scrubbing (spray dryer adsorber): Electricity would 

be required to operate the spray dryer adsorber. Electrical 

costs of operating the adsorber were factored into the 

annualized cost per ton. 

(c) Impact analysis part 3: Non-air quality environmental impacts 
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Engineering Memo for BART Detelmination 

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(i) Wet scrubbing with lime: Chemstone's 11/30/07 application 

addendum identified sludge handling and disposal issues as 

non-air quality environmental impacts of wet sClUbbing. 

Specifically, the need to handle the sludge so as to avoid 

groundwater contamination and the need to permanently set 

aside from future surface uses the area used for sludge 

disposal, as the disposed sludge cannot bear weight from uses 

such as buildings or cultivated agriculture. 

(ii) Inherent dry sClUbbing (process): NI A (currently utilized). 

(iii) Semi-wet sClUbbing (spray dryer adsorber): Chemstone's 

11130/07 application addendum lists the production of dry 

waste requiring landfilling and water usage as non-air quality 

environmental impacts of semi-wet sClUbbing. 

(d) Impact analysis part 4: Remaining useful life 

(i) Wet sClUbbing with lime: The remaining useful life ofthe unit 

was not considered in the evaluation. 

(ii) Inherent dry sClUbbing (process): N/A (currently used). 

(iii) Semi-wet sClUbbing (spray dryer adsorber): The remaining 

useful life of the unit was not considered in the evaluation. 

(5) Step 5: Visibility impacts 

(a) Wet sClUbbing with lime: In its 11/30/07 application addendum, 

Chemstone evaluated visibility impacts at SNP associated with two 

S02 control scenarios: 80% reduction and 90% reduction. The 

scenarios were not associated with a specific control device but rather 

applied to either wet or semi-wet scrubbing. The analyses were 

conducted using CALPUFF and represented base-case (no control) and 

base-case with 80 and 90 percent S02 removal applied. Visibility 

improvement was calculated as the difference between the existing 

visibility impairment (base case) and the visibility impairment for the 

controlled emission rates as measured by the 98th percentile modeled 

visibility impact. 

The (higher) S02 emission rate determined in the October 2007 rotary 

kiln stack test was used in the visibility impact modeling. Other 

pollutants were modeled at the same rates as in prior (i.e., BART 

applicability) modeling analyses. The visibility improvement 

modeling analysis was reviewed by both DEQ and NPS staff. 
O-N Minerals (Chemstone) Company- Strasburg Facility 

Engineering Memo for BART Determination 

Page 19 

The visibility impact analysis compared the 981h percentile modeled 

imr.act resulting from base case (no add-on control) conditions to the 

9811 percentile modeled impacts resulting fi'om 80% control of S02 

and 90% control of S02. The base case analysis used the actual S02 

emission rate determined in the October 30, 2007 stack test (66.1 

lbs/hr). The analyses determined that the visibility improvement 

predicted for 80% control was 0.04 dv and that the improvement 

predicted for 90% control was 0.05 dv. Chemstone also analyzed the 

visibility impact associated with both control levels when the base case 

was Chemstone's proposed BART S02 emission limitation (79.3 

lbs/hr). In that case, Chemstone reported visibility improvement of 

0.06 dv resulting from either control level. 

On Febtuary 26, 2008, DEQ staff, after consultation with the NPS 

(FLM), requested several clarifications and refinements to be made to 

Chemstone's analyses. Requested adjustments included use of a 

higher ammonia background concentration, use of a PM speciation 

background value that varies based on monthly average relative 

humidity, and modeling a reduction in primary sulfate emissions linear 

to the projected S02 reductions. Chemstone's response, dated March 

17, 2008, indicated a revised visibility improvement of 0.11 dv 

resulting from 90% S02 (and primary sulfate) control. 

(b) Inherent dry sctubbing (process): N/A (currently used). 

(c) Semi-wet sctubbing (spray dryer adsorber): Please see discussion of 

visibility impact analysis for wet scrubbing above. 

(6) Step 6: Propose BART 

The following table summarizes the impacts analysis described above. 
O-N Minerals (Chemstone) Company - Strasburg Facility 

Engineering Memo for BART Determination 

Page 20 

To a hi e 3 S UlIll1lary 0 Impacts analysIs I - so 2 fi rom rotmy k"l I n 

Inherent dry Semi-wet 

Wet scrubbing scrubbing scrubbing 

with lime (process) (spray dryer 

(base case) adsorber) 

Expected I Ibs/hr 4.0 79.3' 7.93 

emission rate I tons/yr 17.4 347 34.7 

% pollutant removed' 95 55 90' 

Expected emissions 330 NIA 312 rednction (tons/yr) 

TAC' 1,322,423 NIA 1,631,421 Costs of ($) 

compliance4 $/ton 4,007 NIA 5,218 

$/dv' 12MM NIA 14MM 

Energy impacts Electricity to NIA Electricity to 

operate operate 

Non-air quality Sludge handling NIA Landfilling of 

dry waste; environmental impacts & disposal water usage 

Modeled visibility 

improvement' (dv) 0.11 NlA 0.11 

I Inherent dry scmbbmg represents base case. The pounds-pel-haUl emiSSIOns level IS the 

BART limit proposed by Chemstone and is based on October 2007 stack testing (66.1 

Ibs/hr) with a 20% margin of compliance added. 

, Base-case (inherent dry scrubbing) removal percentage is based on percent sulfur in fuel 

used versus mass of sulfur emitted in October 2007 stack test (sulfur content of limestone 

feed was not indicated in stack test report; percent removal may be higher depending on 

limestone sulfur content). Percent removal for wet and semi-wet scrubbing is based on 

removal of SO, in kiln outlet gas stream (i.e., after base-case removal shown). 

J For a semi-wet scrubber to achieve this level of reduction, it would likely require 

cooling of kiln outlet stream. Costs of cooling gas stream were not evaluated. 

4 Incremental cost effectiveness was not evaluated because the most stringent control 

(wet scrubber) had lower total amlUalized costs than the alternative add-on control (semiwet scrubber). 

5 TAC = total annualized cost (sum of direct annual costs and indirect ammal costs) 

6 Based on 90% control. 

The impact analysis summarized above indicates that wet sClUbbing with 

lime constitutes BART for S02 from the rotary kiln. The finding is based 

on the following considerations: 

• Of the add-on control altematives evaluated, wet sClUbbing 

with lime has higher removal efficiency and lower costs 

than semi-wet sClUbbing (spray dryer adsorption). 

Accordingly, no further consideration is given to semi-wet 

sClUbbing. 

• The cost effectiveness of wet sClUbbing ($4,007/ton at 95% 

efficiency and $4,225/ton at 90% efficiency) is not 
O-N Minerals (Chemstone) Company - Strasburg Facility 

Engineering Memo for BART Detelmination 

Page 21 

considered prohibitive. The BART determination for 

another Virginia facility, Georgia Pacific, is control of S02 

with a wet sClUbber at a cost per ton that is slightly higher 

than that indicated for Chemstone. 

• The variable and at times low level of control achieved 

inherently in the kiln, as indicated by recent testing. Newer 

preheater rotary kilns typically achieve greater than 90% 

removal of S02 tlll'ough inherent dry sClUbbing. The 

control level listed for inherent dry sClUbbing for most 

preheater kilns in the RBLC is 92 percent. For reasons that 

are not yet clear, Chemstone's rotary kiln appears to be 

operating at times at a significantly lower level of inherent 

removal (55%). In terms oflbs S02/tsf or Ibs SO~ton lime, 

Chemstone's rotary kiln emission rate is higher than most 

kilns listed in the RBLC. As a result, inherent dry 

sClUbbing alone does not meet BART requirements, given 

that an economically feasible alternative is available. 

The BART limits for S02 from the rotary kiln are 14.7 Ibslhr and 0.29 

Ibs/tsf. The limits are based on 95% control of S02 emitted assuming all 

sulfur in the limestone feed and fuel is emitted as S02 and assuming a 

maximum coal sulfur content of one percent (calculations in Attachment 

N). Uncontrolled emissions have been conservatively based on raw 

material and fuel sulfur mass balance because there are insufficient data 

available on which to determine the percentage removed through inherent 

sClUbbing. Two performance tests on the rotary kiln indicate inherent 

removal as high as above 99% (April 2000) and as low as 55% (October 

2007, considering fuel sulfur only). No explanation has yet been offered 

for the fluctuation in dry sClUbbing efficiency between the tests. Further 

testing and data collection are needed before a reliable inherent removal 

rate can be determined for the kiln. Given the limited and highly variable 

test results, DEQ has no confidence that the October 2007 testing 

represents the maximum S02 emissions rate from the kiln. Accordingly, 

the BART limits have been based not on the October 2007 test results but 

rather on the maximum sulfur in the kiln (from limestone and fuel), as this 

determines the potential S02 that needs to be controlled. Chemstone's 

cost analyses were based on controlling the emissions level determined in 

the October 2007 testing, adjusted for a 20% margin of compliance. The 

level of control (95%) determined to be cost effective at this lower 

emissions level has been applied to the potential emissions (based on 

sulfur mass balance) to derive the BART limits. Calculations are in 

Attachment N. (Note that, as explained below, the permit requires 

Chemstone to operate a Continuous Emissions Monitoring System 

(CEMS) to monitor S02 emissions.) 
O-N Minerals (Chemstone) Company - Strasburg Facility 

Engineering Memo for BART Determination 

Page 22 

The BART permit also restricts maximum sulfur content to one percent by 

weight; prior to the BART permit, the sulfur content limit was 1.5% by 

weight. In discussions with DEQ staff, Chemstone has indicated a 

willingness to accept a 1.0% S limit on its rotary kiln coal. The BART 

pelmit enforces the limit and thereby further reduces potential S02 

emissions. 

The BART permit requires that S02 from the rotary kiln be controlled by a 

wet scmbber or, upon DEQ approval, an alternative control technology 

(including inherent process scmbbing) capable of meeting the BART 

emissions limits. The limits are based on an overall control efficiency of 

95%, meaning that between the inherent dry scmbbing within the kiln and 

the wet scmbber, emissions will be reduced to 14.7 Ibs SO:J]u· and 0.29 

lbs/tsf. The production-based limit (lbs/tsf) applies at all times except 

during startup, which is defined in the permit. The hourly emission limit 

(lbs/hr) applies at all times, including startup. The permit requires that the 

S02 emissions limits be met no later than September 10,2010 and that the 

wet scmbber, if needed to meet the emissions limits, be installed by 

August 1, 2012. The effective date of the emissions limits was chosen for 

consistency with terms of a pending EPA enforcement settlement. 

2. Calcimatic kiln (UI2) 

a. NOx 

(1) Step 1: Identify all available retrofit control technologies 

(a) Existing controls: The calcimatic kiln controls NOx emissions by 

proper kiln design and operation (good combustion practices). The 

kiln employs a 27-burner system having a multi-channel burner at each 

of the 27 locations. Recycled oil or fuel oil is mixed with combustion 

air and atomizing air at each location to produce the most efficient 

burn possible and to minimize emissions. Each bumer location can be 

fine-tuned individually as needed. The gases are monitored by an 

oxygen/combustible analyzer to ensure proper combustion. 

(b) Available retrofit control technologies 

The control technologies available for the calcimatic kiln are the same 

as those identified for the rotary kiln: 

(i) Selective Catalytic Reduction (SCR) 

(ii) Selective Non-Catalytic Reduction (SNCR) 

(iii) Non-Selective Non-Catalytic Reduction (NSNCR) 
O-N Minerals (Chemstone) Company - Strasburg Facility 

Engineering Memo for BART Determination 

Page 23 

(iv) Low-NOx burner (LNB) 

(v) Proper kiln design and operation 

(vi) Water/steam injection 

(vii) Reburn at the bU11ler (fuel staging) 

(viii) Mid-kiln firing (MKF) 

(2) Step 2: Eliminate technically infeasible options 

The rationale for determining technical feasibility for the calcimatic kiln is 

the same as that for the rotary kiln. Please refer to discussion of 

technically infeasible control options for the rotary kiln in Section 

IILD.I.a(2). 

(3) Step 3: Evaluate control effectiveness of remaining control technologies 

The control effectiveness of the remaining feasible technologies, SNCR 

and proper kiln design and operation, are the same as indicated for the 

rotary kiln in Section III.D.I.a(3). 

(4) Step 4: Evaluate impacts and document results 

(a) Impact analysis patt I: Costs of compliance 

At DEQ's request, Chemstone conducted a cost analysis for 

controlling NOx from the rotary kiln using SNCR. The resulting 

average annual cost per ton was deemed cost prohibitive when 

compared to recent costs for controlling NOx encountered by the 

agency. NOx emissions from the calcimatic kiln are limited by a 

minor new source review pelmit to 41.4 tpy. Assuming 60% control, 

use of SNCR would reduce NOx emissions from the calcimatic kiln by 

24.7 tpy. Given the results of the cost analysis for the rotary kiln 

(which has potential emissions over 300 tpy), it is reasonable to infer 

that a SNCR cost analysis for a 24.7 tpy reduction would result in a 

finding that the control was not economically feasible for the 

calcimatic kiln. 

(b) Impact analysis patt 2: Energy impacts 

Energy impacts are similar to those described for the rotary kiln in 

Section IILD.I.a.( 4)(b). 

(c) Impact analysis palt 3: Non-air quality environmental impacts 

(i) SNCR: None were identified in the application. 
O-N Minerals (Chemstone) Company- Strasburg Facility 

Engineering Memo for BART Detennination 

Page 24 

(ii) Proper kiln design and operation (good combustion practices): 

NI A (currently used) 

(d) Impact analysis patt 4: Remaining useful life 

(i) SNCR: The remaining useful life of the unit was not 

considered in the evaluation. 

(ii) Proper kiln design and operation (good combustion practices): 

NI A (currently used) 

(5) Step 5: Visibility impacts 

(a) SNCR: Since SNCR was found to be cost prohibitive, visibility 

impacts resulting from its use were not evaluated. 

(b) Proper kiln design and operation (good combustion practices): N/A 

(cUlTently used) 

(6) Step 6: Propose BART 

The evaluation of available control measures for NOx from lime kilns 

demonstrates that proper kiln design and operation (good combustion 

practices) is the only control that is both technically feasible and cost 

effective. Chemstone's calcimatic kiln is designed to allow tuning of 

individual burners as needed to optimize combustion efficiency and minimize 

emissions. The calcimatic kiln is subject to BACT limits for NOx of9.82 

Ibs/hr and 41.4 tpy (minor New Source Review permit dated May 1, 2002). 

Considering the 16 tsJThr capacity of the kiln, the BACT limits are equivalent 

to 0.611bs NOx/tsf, which is lower than recent limits on lime kilns in the 

RBLC. Accordingly, it has been determined that use of proper kiln design 

and operation (good combustion practices) constitutes BART for NOx from 

the calcimatic kiln. 

(1) Step 1: Identify all available retrofit control technologies 

(a) Existing controls: The calcimatic kiln is controlled by a Venturi 

scrubber. The scrubber was installed primarily for PM control but also 

achieves S02 removal. The calcimatic kiln is subject to minor New 

Source Review pennit limits of7.52Ibs S02/br and 31.7 tons S02/yr. 

The calcimatic kiln is limited to use oflow-sulfur fuels (natural gas, 

distillate oil (maximum 0.5% S) and recycled fuel oil (maximum 0.5% 

S). The minor NSR limits were derived assuming all sulfur in both the 
O-N Minerals (Chemstone) Company- Strasburg Facility 

Engineering Memo for BART Determination 

Page 25 

limestone feed and the fuel was emitted and a S02 removal efficiency 

of 85.9%. The 85.9% removal efficiency was based on data submitted 

by Chemstone from stack testing at an Oregon facility and apparently 

reflected a combination of inherent scrubbing and wet scrubber 

control. Testing conducted in 2001 on the Chemstone calcimatic kiln 

indicated an emissions rate of 0.04 Ibs S02ihr. The emissions rate 

presumably results from a combination of inherent dry scrubbing 

within the kiln and wet scrubbing by the Ventnri scrubber. 

(b) Available retrofit control technologies 

(i) Inherent dry scrubbing (process) 

(ii) Semi-wet scrubbing (spray dryer adsorber) 

(2) Step 2: Eliminate technically infeasible options 

All of the identified retrofit teclmologies are technically feasible for 

controlling S02 from the calcimatic kiln. 

(3) Step 3: Evaluate control effectiveness of remaining control teclmologies 

(a) Inherent dry scrubbing (process): According to Chemstone's 11130107 

submittal, inherent scrubbing in the calcimatic kiln would be expected 

to remove less than 80 percent of S02. Note that the calcimatic kiln 

does not have a preheater and therefore the inherent scrubbing 

potential is lower than that for the (preheater) rotary kiln. 

(b) Semi-wet scrubbing (spray dryer adsorber): A semi-wet scrubber can 

achieve removal efficiencies up to 90%. Please see item 

III.D.1.b(3)(c) above for details (discussion of semi-wet scrubbing 

under rotary kiln evaluation). 

(4) Step 4: Evaluate impacts and document results 

(a) Impact analysis part 1: Costs of compliance 

Since the calcimatic kiln is controlled by the most stringent 

technology, no cost analyses were conducted. 

(b) Impact analysis part 2: Energy impacts 

Energy impacts were not evaluated because the calcimatic kiln is 

controlled by the most stringent technology. 

( c) Impact analysis part 3: Non-air quality environmental impacts 
O-N Minerals (Chemstone) Company - Strasburg Facility 

Engineering Memo for BART Determination 

Page 26 

Non-air quality environmental impacts were not evaluated since the 

kiln is controlled by the most stringent technology. 

(d) Impact analysis part 4: Remaining useful life 

The remaining useful life of the kiln was not considered in the 

evaluation. 

(5) Step 5: Visibility impacts 

Since the calcimatic kiln is controlled by the most stringent control 

alternative, no visibility impact analysis was conducted. 

(6) Step 6: Propose BART 

Chemstone's 11/30107 analysis concluded that use of a wet scmbber (such 

as the Venturi scmbber currently employed) constitutes BART for S02 

from the calcimatic kiln. DEQ concurs with the conclusion. However, the 

level of S02 removal (85.9%) currently required by the minor NSR pennit 

does not meet BART requirements. As indicated in Chemstone's 

11/30107 analysis, wet scmbbing can achieve up to 95% removal and the 

October 2001 stack testing of the calcimatic kiln demonstrated such 

removal. Accordingly, BART limits have been established based on 95% 

removal of S02, assuming all fuel and limestone feed sulfur is emitted as 

S02. The limits included in the BART pennit are 2.61bs S02/hr and 0.16 

lbs SOz/tsf. Calculations are attached (Attachment 0). 

IV. Compliance Demonstration 

Except for the rotary kiln (US) S02 and PMlPMto limits, compliance with the BART 

emission limits and supporting provisions is required following the effective date of the 

permit. Compliance with the rotary kiln S02limits is required by September 10, 2010. 

Compliance with the rotary kiln PM and PMto limits is required 180 days after the pelmit 

effective date. The pennit prescribes several means of compliance demonstration, 

including continuous monitoring of emissions (rotary kiln S02) and of control device 

parameters, recordkeeping, testing and repOlting. 

The monitoring required by the permit includes: 

• Rotary kiln fabric filter pressure drop is to be continuously measured; the 

measurement is to be observed at least once each operating day and a log 

kept of the observations. 

• Calcimatic kiln Venturi scmbber's pressure drop, liquid flow rate and exit 

gas temperature is to be continuously measured; the measurements are to 
O-N Minerals (Chemstone) Company - Strasburg Facility 

Engineering Memo for BART Determination 

Page 27 

be observed at least once each operating day and a log kept of the 

observation results. 

• A BART Monitoring Plan is required to be developed within six months 

of permit issuance. The plan is required to detail procedures for proper 

operation and maintenance of each kiln, procedures for monitoring and 

proper operation of monitoring equipment and corrective action to be 

taken when necessary. 

• The permit requires that each kiln be monitored in accordance with the 

BART monitoring plan. 

• The combustion apparatus on both kilns are to be tuned annually to 

minimize emissions ofNOx• 

• Use of a Continuous Emissions Monitoring System (CEMS) on the rotary 

kiln to measure S02 emissions by September 10, 2010 (the S02 

compliance date for the rotary kiln). The CEMS is to be installed, 

calibrated, maintained and operated in accordance with 9 VAC 5-40-41. 

A performance evaluation of the CEMS is to be conducted and a CEMS 

quality control program implemented. 

Records required to be kept (for each kiln) include amount of each fuel consumed, 

throughput of limestone, operating hours, fuel supplier certifications, emissions 

calculations to verify compliance with all emission limits, CEMS data, operational and 

control device monitoring records (including records of monitoring required by the 

BART monitoring plan and a copy of the plan), scheduled and unscheduled maintenance 

and stack test results. 

The permit requires performance testing to be conducted on each kiln for NOx, S02 and 

PM to demonstrate initial compliance with the emission limits. The tests are to be 

conducted according to EPA Reference Methods 7 or 7E (NOx), 6 or 6C (S02) and 5 

(PMlPM -10). RM5 has been specified for PMlPM -10 compliance because it is the test 

method prescribed by the Lime MACT (40 CFR 63 Subpatt AAAAA) for demonstration 

of compliance with the MACT's PM limits. The MACT PM limits have been used as 

Chemstone's BART determination (the emission level has been applied to both PM and 

PM-IO). Testing for S02 from the rotary kiln is required within 60 days of September 10, 

20 I 0 (S02 limit compliance date). The remaining tests are required to be completed 

within 180 days ofthe effective date of the permit. For the calcimatic kiln (UI2), which 

is not currently operating, initial testing is required to be conducted within 90 days after 

the unit resumes normal operation. 

To show continuing compliance with the limits, the permit requires that an annual stack 

test for NOx be conducted for each kiln. After three consecutive stack tests showing 

compliance with the NOx limits, the required frequency of testing is reduced to once 

every five years. If any subsequent stack test indicates noncompliance with the NOx 

limits, stack testing frequency reverts to once per year. The permit requires that 

compliance with the S02 limits for the rotary kiln be shown by use of a CEMS. The 
O-N Minerals (Chemstone) Company - Strasburg Facility 

Engineering Memo for BART Determination 

Page 28 

permit also requires additional stack testing at least once every five years for PM and 

upon request ofDEQ. 

The permittee is required to report its emissions of each pollutant from both kilns semiannually, in writing. 

V. Public Participation 

According to 40 CFR 51.308(i)(2), Federal Land Managers (FLMs) are to be provided a 

60-day review period for consultation on implementation plans related to regional haze, 

which includes proposed BART permits. Therefore, the FLMs were given the 

opportunity to review and comment on the draft permit beginning January 15,2009. 

Comments were received from the National Park Service (NPS) on March 2, 2009 (see 

Attachment P). VRO responded in a letter dated September 22, 2009 (see Attachment 

R). 

The draft permit was placed on public notice in the Harrisonburg Daily News-Record 

from October 15,2009; the public comment period began October 16,2009 and ended 

November 16,2009. Two comments were received: one from the National Park Service 

and one from Chemstone. Both letters are appended as Attachment S. VRO's response 

to the comments received is attached (Attachment T). There were no requests for a 

public hearing. 

As a result of public comment, the following changes have been made to the permit: 

• Condition 4 was changed to allow additional time for installation of a wet scrubber. 

The original condition required that scrubber installation be completed by September 

1, 2010. In its comments provided during the public comment period, Chemstone 

requested that the scrubber installation deadline be extended to September 1, 2012 

(see Attachment S for full request). VRO agreed that it was appropriate to allow 

more time to complete scrubber installation, but extended the deadline to August 1, 

2012 to comply with Virginia's BART Rule (see 9 VAC 5-40-7590). It should be 

noted that the compliance date for the S02 limit was not changed: the permit still 

requires Chemstone to meet the BART S02 emissions limits by September 1, 2010. 

Condition 4 now reads: Emission Controls: Rotary Kiln - No later than September 

10,2010, sulfur dioxide (S02) emissions from the rotary kiln (US) shall be controlled 

to achieve the S02limits in Condition 23. Unless the Director, Valley Regional 

Office, approves inherent process scrubbing as an alternative control technology by 

September 10,2011, a wet scrubber shall be installed by August 1, 2012. The wet 

scrubber or other technology employed to meet the S02 limits shall be provided with 

adequate access for inspection and shall be in operation when the rotary kiln is 

operating. 

(9 V AC 5-80-850, 9 V AC 5-40-7580, 9 V AC 5-40-7590 and 9 V AC 5-40-7650) 
O-N Minerals (Chemstone) Company - Strasburg Facility 

Engineering Memo for BART Determination 

Page 29 

• The recordkeeping condition has been changed to correspond to the extended 

scrubber installation date in revised Condition 4. 

Condition 26J now reads: Beginning on August 1, 2012, control device monitoring 

records for the wet scrubber serving the rotary kiln (U5) as required in Conditions 9 

and 14. 

• The rotary kiln S02 stack test condition has been revised to require testing within 60 

days of the compliance date in Condition 23. The original condition required testing 

within 60 days of the compliance date or following scrubber installation, whichever 

occurred first. Since the scrubber installation deadline has been changed, there is no 

question that the compliance date in Condition 23 (September 1, 2010) will occur 

first. 

Condition 28 now reads: Stack Test: Rotary KiIn- Initial perfOlmance tests shall be 

conducted for S02 from the rotary kiln (U5) using EPA Reference Method 6 or 6C 

(40 CFR 60 Appendix A) to determine compliance with the emission limits contained 

in Condition 23. The tests shall be performed and demonstrate compliance within 60 

days after the compliance date in Condition 23. Tests shall be conducted and 

reported and data reduced as set forth in 9 V AC 5-40-30 and the test methods and 

procedures contained in each applicable section or subpmt listed in 9 V AC 5-50-410. 

The details of the tests are to be arranged with the Director, Valley Regional Office. 

The pelmittee shall submit a test protocol at least 30 days prior to testing. A copy of 

the test results shall be submitted to the Director, Valley Regional Office, within 60 

days after test completion and shall conform to the test report format enclosed with 

this permit. 

(9 VAC 5-80-850 and 9 VAC 5-40-7660) 

• At Chemstone's request, the word "caustic" has been removed from all references to 

the scrubber throughout the permit. 

VI. Conclusions 

The BART analysis submitted by Chemstone for its rotary and calcimatic kilns has been 

reviewed in accordance with guidelines provided in 40 CFR 51 Appendix Y. The BART 

detelminations for each pollutant and each kiln are summarized in Table 1 and the 

underlying rationale has been documented in Section III.D. A state operating permit has 

been drafted to make enforceable the emission limitations, monitoring, testing, 

recordkeeping and reporting requirements needed to implement the BART determination, 

in accordance with 9 V AC 5 Chapter 40, Article 52. 

Attachments 
A: 

B: 

C: 

D: 

E: 

F: 

G: 

H: 

I: 

J: 

K: 

L: 

M: 

N: 

O-N Minerals (Chemstone) Company - Strasburg Facility 

Engineering Memo for BART Determination 

Page 30 

Best Available Retrofit Technology Applicability Analysis 

submitted by O-N Minerals (Chemstone) Company, 

September 2006 

Best Available Retrofit Technology Determination 

submitted by O-N Minerals (Chemstone) Company, 

Febmary 2007 

Letter dated April 27, 2007, submitted by Chemstone in support 

of its BART determination (response to VRO 30-day letter) 

Letter dated May 31, 2007, submitted by Chemstone in support 

of its BART determination (SNCR evaluation) 

Letter dated July 12, 2007, submitted by Chemstone in support 

of its BART detelmination 

Letter dated August 30, 2007, submitted by Chemstone in support 

of its BART determination (application for de minimis S02limits) 

Letter dated September 27, 2007, submitted by Chemstone in 

SUppOlt of its BART detelmination (comments on draft permit) 

October 30, 2007 rotary kiln emissions test summary report (cover 

letter dated 11112/07) 

November 30, 2007 revised S02 BART proposal (cover letter 

dated 12/05/07) 

Letter dated January 7,2008, submitted by Chemstone in SUppOlt 

of its BART determination (response to VRO 30-day letter for 

revised S02 BART proposal) 

Letter dated March 17, 2008, submitted by Chemstone in SUppOlt 

of its BART determination (response to DEQ and FLM modeling 

comments) 

Letter dated July 15, 2008, submitted by Chemstone in support of 

its BART detelmination (response to June 2008 draft permit) 

Recent listings for lime kilns in EPA's RACTIBACT/LAER 

Clearinghouse (NOx) 

Calculations showing derivation of BART S02 limits for rotary 

kiln 
0: 

P: 

Q: 

R: 

S: 

T: 

O-N Minerals (Chemstone) Company - Strasburg Facility 

Engineering Memo for BART Determination 

Page 31 

Calculations showing derivation of BART S02limits for 

calcimatic kiln 

Comments dated March 2, 2009 from Don Shepherd (NPS) on 

draft BART permit 

Letters dated April 3, 2009, May 8, 2009 and June 4, 2009 

submitted by Chemstone in response to VRO request to address 

FLM comments 

Letter dated 09/22/09 from VRO to FLM responding to FLM 

comments 

Comments received on the draft permit during the public comment 

period (from NPS and Chemstone) 

VRO's Response to Comments received