
September 3, 2019
SUBJECT: 	Trip report for site visit to United Taconite LLC, Cleveland-Cliffs, Inc., Eveleth, MN, October 11, 2018
FROM:	Michael Laney, RTI International
TO:		David Putney, U.S. Environmental Protection Agency (EPA)
       BACKGROUND
As part of the risk and technology review (RTR) project for the national emission standards for hazardous air pollutants (NESHAP) for taconite iron ore processing, site visits were conducted to three taconite iron ore processing facilities located along the Mesabi Range in Minnesota. This trip report summarizes the October 11, 2018 visit to the United Taconite processing facility in Eveleth, MN.
       PARTICIPANTS
United Taconite
Candice Maxwell, Area Manager  -  Environmental Affairs
Jason Aagenes, Director, Air Reg Strategy & Prog
Chan Paine, Section Manager for Plant Operations
EPA
David Putney, Office of Air Quality Planning and Standards
RTI International
Michael Laney
       SUMMARY
 Preliminary Discussions
Prior to touring the facility, participants met to discuss the agenda for the day.
Overview of plant operations. Candice Maxwell provided the following overview of plant operations.
The mine is located about 7 miles from the processing facility. Ore undergoes primary and secondary crushing at the mine. Crushed ore is transported to the processing facility via third party rail. The mine is covered by a separate title V permit.
After unloading, the ore is conveyed to third stage crushing, screened, and oversize ore sent to stage 4 crushing. Excess ore from the mine is stored in the coarse ore surge pile. The facility uses dry controls or wet scrubbers to control particulate matter emissions from crushing and screening operations and various transfer points.
The crushed ore is then conveyed to the concentrator process. Upon entering the concentrator process, the ore is wet and any emissions are minimal. The wet ore is subjected to a series of processes to reduce the particle size and separate the iron from tailings. The process consists of series rod mills, ball mills, magnetic separators, roughers, concentrators, cyclones, hydro-separators, fine screens and vacuum disk filters to remove excess water.
The dewatered material next is conveyed to balling drums where the iron-rich material is formed into unfired ("green") pellets, ready for the indurating furnace.
Unfired pellets enter the grate kiln furnace and travel through increasingly hot sections of the furnace to dry the pellets, and then gradually heat them before they are hardened in the hottest part of the furnace. Typical of grate kiln furnaces, a variety of fuels are used, including natural gas, coal, coke, or fuel oil. From the furnace the fired ("finished") pellets pass through an annular rotary cooling section.
This facility uses wet scrubbers to control particulate emissions from both the furnace and cooler.
After cooling, the finished pellets are conveyed to bins and eventually loaded on to train cars. Particulate emissions from transfer of finished pellets to the bins are controlled using wet scrubbers.
Large amounts of water are used in processing the ore. Most of the water (about 95 percent) is recycled, recovered, and reused in the process. The tailings basin is also the water retention pond.
Following the overview of the plant operations, David Putney, EPA, provided background information on the RTR project, specific information needs for the RTR project, and responded to questions from United Taconite and Cleveland-Cliffs representatives. Topics discussed included the following:
Process diagrams. EPA requested a process flow diagram.
Technology review. According to United Taconite, there have been no developments in the material handling operations. Wet scrubbers, fabric filters, and cartridge filters are the principal technologies for emissions control of these operations.
Similarly, there have been no developments in the control of emissions from indurating furnaces. Venturi scrubbers, wet ESPs, and dry ESPs continue to be the principal controls. The selection of controls is affected by factors such as differences in dust characteristics (e.g., resistivity). United Taconite has considered using baghouses but they are not considered technically feasible due to the temperature and moisture content of the exhaust gases.
Minnesota Pollution Control Agency (MPCA) mercury initiative. United Taconite representatives stated that they are currently evaluating control options for meeting the requirements in Minnesota's 2014 Mercury Rule. Their proposal to MPCA for meeting the required reduction is due by December 30, 2018. The MPCA has scheduled implementation of the mercury reductions for January 2025. In MPCA's 2009 TMDL Implementation Plan, MPCA stated "... plant-ready mercury-reduction technology does not currently exist for use on taconite pellet furnaces."
United Taconite is conducting pilot plant tests of control technologies. They are looking at several technologies including oxidized mercury for wet scrubber removal, fixed carbon bed absorption, carbon injection, and membrane technology. Other technologies have been considered but eliminated.
Mercury concentration in raw ore. David Putney explained the process that would be used for setting emission limits for mercury if the EPA decides to propose numerical MACT standards for mercury emissions. He explained that, in addition to emissions data, information on the variability of mercury concentrations in raw ore could be important information for EPA to consider in developing emission standards that accurately reflect variability in mercury emissions. He noted that there is precedence for using information on mercury variability in raw ore to set emission standards. He requested that United Taconite provide the EPA with any such mercury data they may have, or can get, to assist EPA in the event they propose mercury emission standards for the industry.
United Taconite personnel stated that they did not have mercury concentration data from core samples. They noted that MDNR did perform sampling of raw ore many years ago.
David Putney described changes to the NESHAP that are being planned beyond any that might be made as a result of the RTR. Among the revisions currently planned are the following:
Once in always in. This refers to a provision of the rule (i.e., 40 CFR 63.9581), and has been EPA policy, whereby if a source was subject to the rule as a result of being a major source for purposes of title III of the CAA (greater than 10 tons of a single HAP or 25 tons of all HAP combined), it would always be subject to the rule, even if they reduce their HAP emissions to less than major source status. As a result of a change in EPA policy, this provision in the NESHAP will be modified.
Startup, shutdown, and malfunction (SSM). As a result of a court ruling, the exemption from the emission standards during periods of SSM will be removed. Sources will be subject to an emissions standard, but it may be a work practice standard if it is not possible to demonstrate compliance with the emission limits.
Electronic reporting. Compliance test results will be required to be submitted to EPA through EPA's electronic reporting tool (ERT).
Burden reduction. David Putney explained the EPA is interested in industry's experience with any requirements of the current rule that they consider to be burdensome that could be revised to be less burdensome while not comprising environmental protection.
United Taconite identified the following issues they have with the current rule:
-Bag leak detection (BLD) alarms are often triggered by events other than excessive dust loading in exhaust gases, such as atmospheric conditions. Such false alarms usually resolve themselves in a short amount of time (a few seconds). But under the current rule requirements, each BLD alarm must be investigated within an hour and resolved. They would like to see that requirement revised to account for false alarms that do not need to be investigated (and resolve themselves).
-The requirement to monitor pressure differential for certain types of scrubbers was not appropriate. They noted that this was the case for low pressure scrubbers.
- The rule limits to six the number of units that can be covered by testing one representative unit. They stated that they have eight identical units but under the current rule they cannot perform a single test on a representative unit. They are required to conduct additional tests to cover the other two units.
 Site Tour
Mine Operation. The tour did not include the mine operation, which is located about 7 miles from the processing facility. The mine is a NESHAP area source and is not subject to the Taconite MACT.
Processing. Chan Paine, Section Manager for Plant Operations, conducted the tour of the facility. The processes viewed included the fine crushing, concentrator operations, and the pellet plant. The details of the process are those that were described during the preliminary discussions at the beginning of site visit.
 Wrap Up
During the wrap up meeting, David Putney summarized the procedure and schedule for the final risk results and rule development. He noted that proposal is scheduled for April 2019 and promulgation of a final rule in June 2020.
United Taconite stated that they would be providing EPA with a flow diagram of their processing facility.
Following up on earlier discussions regarding mercury concentrations of taconite ore, parts of the rule that United Taconite considered particularly burdensome, and developments in processes, controls and work practices (as part of the technology review), David Putney requested that any information or input that United Taconite could provide on these and other topics be provided by the middle of November 2018.
