Document ID: EPA-HQ-OAR-2010-1041-0139
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2014-11-13T05:00Z

To: 	Project Files
     From: 	Susan Fairchild, US EPA
     Date: 	22 September 2014
     Re: 	Site Visit to Roxul Mineral Wool Production Facility, Byhalia, MS                                                             August 6-7, 2014
Purpose
In telephone conversations with Roxul, Inc. (a subsidiary of Rockwool International) representatives and contractors during the course of the first and supplemental proposals, the EPA learned that Rockwool International was constructing a new mineral wool production facility in Mississippi. This new facility would use a process which is different in certain respects from the other U.S. production facilities.  Rockwool International operated several such facilities in Europe. 
The EPA's goal for this site visit is to understand Roxul's production processes, how they differ or are similar to other U.S. facilities' mineral wool production processes, the HAP emitted by the new processes, and to understand the regulatory issues arising from the advent of the new processes.   
Attendees
Persons from the EPA, Roxul, ERM (a contractor to Roxul) and the State of Mississippi attended the site visit. 
The following attended from EPA:
	Susan Fairchild, Sr. Environmental Scientist
	Keith Barnett, Group Leader, Minerals and Manufacturing Group
The following attended from Roxul:
      Bent S. Jorgensen, Vice President, Operations
      Ken Cammarato, Vice President General Counsel and General Manager, USA Operations
      Tony Borden, Health and Safety Manager
      Sharon Taylor, Environmental Manager
The following attended from ERM:
	Jeffrey H. Twaddle, P.E.
	Kasey Harrington
The following attended from Mississippi Department of Environmental Quality (DEQ):
	Preston Bridges, EEIT
Background
Section 112 of the Clean Air Act (CAA) outlines the statutory requirements for the EPA's stationary source air toxics program. Section 112 requires EPA to set maximum achievable control technology (MACT) standards for source categories listed for regulation of hazardous air pollutants (HAP). The MACT standards for Mineral Wool Production (Part 63, Subpart DDD were promulgated in June 1999.
The Risk and Technology Review (RTR) is a combined effort to evaluate both risk and technology as required by the Clean Air Act (CAA) after the application of the MACT standards. Section 112(f)(2) directs EPA to conduct risk assessments on each source category subject to MACT standards, and to determine if additional standards are needed to reduce residual risks. Section 112(d)(6) of the CAA requires EPA to review and revise MACT standards, as necessary, taking into account developments in practices, processes and control technologies. The Agency is conducting both these reviews at once under the RTR review. In addition to the requirements of the RTR review, EPA is also reviewing the standards to determine whether any HAP or HAP-emitting processes exist which were not regulated by the 1999 MACTs and whether emission limits for surrogates in the rule should be corrected or replaced by the original listed HAP.
The EPA first proposed the RTR for Mineral Wool on November 25, 2011.  The first supplemental proposal was published on April 15, 2013, and announced several changes to the first proposal, including changes to the emission limits for combined collection and curing, and to startup and shutdown provisions.  The second supplemental proposal is expected to be signed by the Administrator on October 15, 2014, and published in the Federal Register shortly thereafter. 
facility overview
Roxul, a Rockwool International Company headquartered in Toronto, Ontario, Canada sought permits and began site preparation for this new mineral wool production facility in 2012. The Roxul facility currently operates one production line consisting of raw material preparation, transfer and storage; melting; fiber formation, collection and curing; cutting, packaging and storage.  Roxul is permitted to begin construction on a second line.  Roxul is also permitted for fabrication processes for the manufacture of other products. 
Products
Roxul is planned to be capable of manufacturing a variety of bonded and loose-fill (non-bonded) products, including insulation for both residential and non-residential applications, sound-proofing, ceiling tile and asphalt roofing.  
  This facility is currently capable of manufacturing a variety of mineral wool products, including:
         > Residential insulation
         > Commercial/ Institutional insulation
         > Industrial insulation
         > Marine & Offshore
         
         > Soundproofing and Acoustical barriers 
Roxul's products are manufactured in thicknesses from one to 8 inches on the single operating production line. 
Roxul is planning to significantly expand the production capacity at the Byhalia plant.  A second production line is planned and permitted which will double capacity. 
The new production line is planned as a mirror image of the current line, with additional capability for production of ceiling tile and asphalt roofing in addition to the additional capacity for mineral wool insulation products. When the second production line is completed, Roxul plans to simultaneously complete an industrial oxygen plant on site which will supply the compressed gas for both cupolas (melting furnaces).
Existing Production Processes
Raw Material Loading, Preparation, Transfer and Storage Processes
Fuels used for production at Roxul include compressed industrial oxygen, coal and natural gas.  Raw materials include basalt, slag (from iron and steel electric arc furnaces), mineral additives, internal recycled mineral wool and phenol/formaldehyde binder. 
Compressed oxygen is currently transported in tanks and stored onsite. Basalt and slag are received from a quarry and steel plant, respectively, and are received as grain size, and sieved onsite to ensure proper sizing. Rod crushing is used for any materials out of size specification. All fuels and raw materials are stored onsite in silos (coal) and bins (other mineral products).
Startup
The cupola is started empty using only clean fuels (natural gas) for 2-5 minutes until it reaches temperatures sufficient to begin melting the mineral mixture, approximately 3200° F. At that point the coal burners start and feed material is introduced. This phase of startup lasts 10-15 minutes. At this point (12  -  20 minutes) the melting furnace is capable of producing usable melt. Steady state production is reached in less than 90 minutes.
Melting Process
The Roxul process differs from other US mineral wool production facilities in the melting process. The Roxul process uses a melting furnace fired with coal and natural gas, rather than a cupola fired with coke. 
Coal, slag, and basalt from hoppers and silos are measured and weighed onto charging belts; mineral additives are used to achieve the correct chemistry of the melt, and the raw material mixture is blended and fed as a continuous stream into the cupola. The melting furnace operates continuously for a 2 week period under the melting furnace maintenance schedule. 
Shutdown
The melting furnace is shut down for maintenance every two weeks, and is a process that requires about 15 minutes to complete, excluding cooling of the melting furnace. All air pollution control devices (APCD) operate continuously, including during shutdown, and therefore should continue to capture and control any emissions during the shutdown process. 
Fiber Formation, Collection and Curing Process
As molten mineral mixture exits the melting furnace, the melt enters the spinners, forming fibers; phenol-formaldehyde binder is sprayed continuously as the fibers are formed and collected.  The combined collection and curing processes at Roxul are considered Vertical Design as the area where the fibers are collected is vertically oriented. 
The collected fibers form a wooly fleece which is spread onto a moving conveyor to a pendulum device which lays the fiber fleece to the desired thickness.  The formed mat then enters the curing oven which heats and sets the phenol/formaldehyde resin. These processes are automated and are similar to the processes at other mineral wool production facilities. 
Cooling Process
As the formed mat exits the curing oven, it is cooled before cutting and packaging.  When the ceiling tile and asphalt roofing fabrication processes are added at a future date, cooled mineral wool bats will be transferred to those manufacturing processes. 
Fabrication (future) Processes
 Production of ceiling tile and asphalt roofing, products which are fabricated from mineral wool products, is also planned. The production of ceiling tile and asphalt roofing are not regulated under subpart DDD, Mineral Wool Production.
Cutting, Packaging, Storage, and Shipping
After the mineral wool produced to the desired thickness, it is cut to size. All cutting and packaging operations are automated and robotic are operated from a central location. Rollers transfer the product from the cooling section through the cutters, into the bagging section and then to storage until the product is shipped to the customer.
 Air Pollution Control Equipment
Pollutants emitted from the melting furnace are controlled using several sets of devices installed in series. The emissions from the melting furnace are first sent to an integrated SNCR for destruction of nitrogen oxides (NOx) and secondary combustion chamber for destruction of CO, then to a baghouse for PM and HAP metals removal. The emission stream is next directed to a semi- dry lime scrubber for adsorption of sulfur oxides (SOx) in series with a second fabric filter for removal of the lime, then melting furnace emissions are directed to the furnace stack. Emissions from the collection process are sent first to a filter for fiber removal and then to the Wet Electrostatic Precipitator (WESP) for removal of filterable and condensable particulate matter (due to phenol-formaldehyde binder). Emissions of organics, including phenol, formaldehyde and methanol from the curing oven are first sent to an afterburner and then to a filter for removal of both organics and fibers.  Post-control emissions from the collection and curing processes enter separate stacks which run alongside one another and are adjoining at the outlet of the second stack. Particulate (fiber) emissions from the cooling zone are directed to a filter in series with the WESP. All emission control collection material from the furnace is returned to the raw material input bins for reincorporation into the process with the exception of the sorbent material used in the SO2 scrubber. A schematic of the Roxul manufacturing process entitled, "Process Overview" is available in the Appendix to this report.  
Projected Emissions Estimates (commissioning phase underway)
Roxul has provided to the permitting authorities projections of expected emissions estimates from the mineral wool production lines, as shown in Table 4-1 below.  These emissions estimates are based upon production at the European and Canadian facilities, not on emissions testing, material balance, or emission factor-derived estimates. 
Table 4-1: Pollutants and Significant Emissions Rates for the Roxul US Facility
                                   Pollutant
                     Significant Emissions Rate (tons/yr)
                               PTE Exceeds SER?
Carbon monoxide [*]
                                      100
                                      Yes
Nitrogen oxides [* a]
                                      40
                                      Yes
Sulfur dioxide [* b]
                                      40
                                      Yes
Particulate matter [*] (PM)
                                      25
                                      Yes
PM10 [*] 
                                      15
                                      Yes
PM2.5 [* c]
                                      10
                                      Yes
Ozone (VOC) [*]
                              40 (of VOCs or NOx)
                                      Yes
Lead [*]
                                      0.6
                                      No
Asbestos
                                     0.007
                                      No
Beryllium
                                    0.0004
                                      No
Mercury
                                      0.1
                                      No
Vinyl chloride
                                       1
                                      No
Fluorides (excluding hydrogen fluoride[e]) [d]
                                       3
                                     No[e]
Sulfuric acid mist
                                       7
                                      Yes
Hydrogen sulfide (H2S)
                                      10
                                      No
Total Reduced sulfur compounds (including H2S) (excluding COS[e])
                                      10
                                      No
Arsenic [f]
                               Any emission rate
                                      Yes
* Criteria Pollutants
a Nitrogen dioxide is the compound regulated as a criteria pollutant; however, significant emissions are based on the sum of all oxides of nitrogen.
b Sulfur dioxide is the measured surrogate for the criteria pollutant sulfur oxides.
c 10 tpy of direct PM2.5 emissions; 40 tpy of sulfur dioxide emissions; 40 tpy of nitrogen oxide emissions unless demonstrated not to be a PM2.5 precursor under paragraph (b)(50) of this section.
d Total fluorides means elemental fluorine and all fluoride compounds as measured by reference methods specified in §60.195 or by equivalent or alternative methods (see §60.8(b)).  [40 CFR 60.191]
e HF and COS are HAPs and not included in the Fluoride or Total reduced Sulfur Compounds pollutant category. See Section 3.1.1 and §52.21(b)(50)(v) for further explanation.
f Significant emission rates have not been promulgated for these pollutants, and until such time, any emissions by a new major sources or any increase in emissions at an existing major source due to modification, are "significant."
Operating and Maintenance Schedule
Roxul operates for 2 week periods on a 24-hour schedule followed by melting furnace maintenance. Additionally, every 8 weeks additional maintenance and rebuilding of the melting furnace downspout is conducted, along with any other maintenance required downstream of the melting furnace.
Regulatory Issues

Issues regarding regulation of melting furnace emissions
Though the melting furnace process at Roxul is very different from any other mineral wool cupola now in operation, it meets the definition in DDD of a cupola, and would thus be subject to the cupola emissions limits. Roxul does not expect this to raise any compliance issues for any of the pollutants except for the demonstration of compliance with  CO. 
The MACT standard of 1999 requires CO be measured as a surrogate to COS, and CO reductions of 99% are required under that rule. In order to determine percent reduction, measurements of the pollutant must be taken both before and after the APCD. Due to both the design and extreme temperatures (both unique to Roxul among mineral wool producers in the U.S.), the percent reduction cannot be measured. Because the CO limits are required by the existing MACT standard for this industry, and because CO remains the surrogate for COS until the RTR is finalized, as a legal matter, the CO limits cannot be dismissed. The EPA representatives recommended that Roxul pursue an alternative compliance demonstration for the Mineral Wool MACT CO limits. 
Limited testing at the Byhalia facility also showed COS emissions below the method detection limit. Because the Roxul melting furnace design has an oxidizing atmosphere, compared to the standard mineral wool cupola design which has a reducing atmosphere, all the raw material and fuel sulfur is converted to SO2 rather than some being converted to COS. 
Emissions of other pollutants (SO2), NOx, HF and HCl are controlled and are expected to be low. 

Emission testing was conducted at sister sites in Europe on processes that are identical to the processes in place in the commissioning phase at Byhalia.  The available representative testing shows COS also tested below the detection level of the method. 
Issues Regarding Startup / Shutdown Work Practices
Periods of startup and shutdown for this process are approximately 12-20 minutes.  Given this short startup/shutdown times, and the fact that the emission test methods for the pollutants of concern typically require a full day to collect three valid test runs, the EPA representatives noted it would appear that emission testing is not practicable. Therefore, Roxul was requested to provide to EPA any work practices used to minimize emissions during periods of startup and shutdown, and contact us to discuss and follow up on the potential work practices used for the unique cupola operated at this facility. 
Issues Regarding New/Existing Source Status
As described in the Background section of this report, three proposals issued over the 3-year period (November 2011 to October 2014) pertain to the Mineral Wool Production Source Category. Roxul began actual construction of the facility in Byhalia, Mississippi in May of 2013, which was after the first and second proposal but before subsequent October 2014 supplemental proposal. Roxul representatives stated that they would have been considered a new site, not an existing site under the originally proposed version of the rule.