February 15, 2023

New Emission Limits Proposed for Lime Manufacturing NESHAP

Though EPA finalized its risk and technology review (RTR) for the lime manufacturing NESHAP on July 24, 2020 (85 FR 44960), not all hazardous air pollutant (HAP) emissions were addressed. In Louisiana Environmental Action Network vs. EPA (U.S. Circuit Court of Appeals, D.C. Circuit; Docket No. 17-1257; April 21, 2020), the court held EPA must address unregulated emissions from a major source category during a standard’s periodic review.

When the agency collected emissions data for the 2020 RTR, it found lime kilns emitted unregulated HAPs, including hydrogen chloride (HCl), mercury, organic HAPs, and dioxin/furans (D/F). On January 5, 2023, EPA proposed amendments to the Part 63, Subpart AAAAA air toxics standard. [88 FR 805] The amendments include a set of emission limits for these unregulated pollutants and operating parameters for the associated emission control equipment. Comments may be submitted through February 21, 2023 via Docket ID No. EPA-HQ-OAR-2017-0015.

Emission Limits

In 2017, EPA prepared a questionnaire to collect information on the lime kiln industry. The industry reported on the location and number of lime kilns, types and quantities of emissions, annual operating hours, types and quantities of fuels burned, and information on air pollution control devices and emission points. The collected data indicated that HCl, mercury, organic HAPs, and D/F are emitted, but unregulated, HAPs. Though the agency conducted a “beyond-the-floor” MACT analysis, it did not identify any techniques that would achieve greater HAP reductions than the new and existing source floors. Consequently, the proposed emission standards are based on the MACT floor. Additionally, total hydrocarbon (THC) is used as a surrogate for organic HAPs. The proposed numerical emission limits vary depending on the type of kiln used and the lime produced, as shown in the table below.

Summary of Proposed New and Existing Source Limits for the Lime Manufacturing NESHAP

Pollutant¹	Kiln type²	Lime produced³	New source limit	Existing source limit	Unit of measure
HCl	SR	DL, DB	1.6	2.22	lb/ton lime produced
	SR	QL	0.021	0.58	lb/ton lime produced
	PR	DL, DB	0.39	0.39	lb/ton lime produced
	PR	QL	0.015	0.015	lb/ton lime produced
	VK	All	0.021	0.021	lb/ton lime produced
Mercury	All	QL, DL	24.9	24.9	lb/MMton lime produced
Mercury	All	DB	24.4	33.1	lb/MMton lime produced
THC	All	All	1.86	3.21	ppmvd as propane @7% O₂
D/F	All	All	0.028	0.028	ng/dscm (TEQ) @7% O₂

ng/dscm = nanograms of pollutant per dry standard cubic meter of air; ppmvd = parts per million by volume, dry; TEQ = toxic equivalency

¹Hydrogen chloride (HCl), total hydrocarbon (THC), dioxin/furans (D/F).

²Straight rotary (SR), preheater rotary (PR), vertical (VK).

³Dolomitic lime (DL), quick lime (QL), dead burned dolomitic lime (DB).

Source: Adapted from 88 FR 815.

Demonstrating Compliance

Affected sources that commence construction or reconstruction on or before January 5, 2023 would be considered existing sources and have three years after the effective date of the final rule (or upon startup, whichever is later) to comply with the provisions of this rule. Affected sources that commence construction or reconstruction after January 5, 2023 would be considered new sources and must comply with the provisions of this rule by the effective date of the final rule (or upon startup, whichever is later). The effective date of the final rule will be its promulgation date. [88 FR 816]

New sources must demonstrate initial compliance with the new emission limits within 180 days after startup, while existing sources must do so within three years of the final rule’s promulgation. Subsequent performance testing would be required every five years thereafter. Continuous compliance with the emission limits would be demonstrated through control device parameter monitoring coupled with periodic emissions testing. New operating parameters are proposed for three types of control devices: activated carbon injection, dry sorbent injection, and regenerative thermal oxidizers.

Facilities will be required to submit semi-annual compliance summary reports documenting compliance and any deviations from the standard. Records of this report and the calibration and accuracy checks on the continuous parameter monitoring system will also be required. [88 FR 815]

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This document addresses issues of a general nature related to the federal environmental regulations. Persons evaluating specific circumstances dealing with the environmental regulations should review state and local laws and regulations, which may be more stringent than federal requirements. In addition, the assistance of a qualified professional should be enlisted to address any site-specific circumstances.