Document daq7emD0DOpB6YR8a2Ooxk7w5

I aconite Rule Presidential Exemption Request March 31, 2025 Page 6 not considered in L.S. EPA's assumption that this control technology was feasible when applied to the taconite sector. The parameters and efficacy of this application are unknown until actual testing is done. This will take a significant amount of time, and thus it is unknown if this technology can be consistently installed at taconite furnaces and successfully achieve the HC1 standards before the current compliance date. Thus, this technology should be deemed currently unavailable. In its comments submitted to EPA, with support from its technical consultants, Cliffs identified numerous technical problems with EPA's prediction of the efficacy of DSI for control of HCI in taconite furnaces. As a baseline. EPA did not establish the rates for DSI representative of actual production levels. Unlike mercury, where EPA permitted establishment of rates at low, medium, and high production levels, EPA only permitted rate establishment at and/or near maximum capacity during a single stack test. By putting industry in a position where rates are set at the maximum, further technical issues include waste of the resource of hydrated lime, additional scrubber and/or wet ESP systems to address the increased lime, and sludge buildup leading to increased maintenance costs. Mercury 'Ile technology identified by EPA for treatment ofmercury is Activated Carbon Injection ("ACI"). As with all the technologies addressed here, ACI has not been used at Taconite Iron Ore Processing plants in the United States to treat mercury. Once again, U.S. EPA's projections of the feasibility and costs of using this technology were not based on data from indurating furnaces and thus arc speculative. Since AC1 changes the form ofmercury emitted from elemental to particle-bound or oxidized, this technology will change how and where mercury will be deposited. It is irresponsible for EPA to proceed with a rule relying on this technology without fully assessing how these changes applied for the first time to -I-aconite processing may affect the deposition and availability of mercury in the environment. A technology should not be considered "available" for this industry until the data are available to confirm that it does not cause more harm than good. A two-year extension offers U.S. EPA time to better understand the data relevant to this issue before requiring facilities to invest in ACI control systems. Testing to determine how to treat mercury in each taconite furnace will take a significant amount of time, and thus it is unknown if this technology can be consistently installed at taconite furnaces and successfully achieve the mercury standards before the current compliance date. Given the novelty of the technology, design, engineering, fabrication, installation, and testing will take a minimum of two to three years to complete. Pilot testing alone must be completed within the first year, testing which requires outages and production shutdowns that can range in costs from $300,000 to $1,300,000 per day. Not only arc such costs exponential, but facilities are expected to undertake them with no precedent for using ACI in the industry before. Thus, this technology should be deemed currently unavailable. Overall, L.S. EPA's candidate control technologies identified as necessary for taconite furnaces to comply with the Taconite Rule will require significant research and development, pilot plant experimentation, and great expense (and uncertainty). Furthermore, their application Sierra Club FOIA 2025-EPA-04883 ED_018388_00000218-00006 SC_EVERSPLIT0005988