Lime Manufacturing (U.S.) — NAICS 327410

An investor's primer for public- and private-market readers.

1. Overview

Lime is one of the oldest and most useful industrial chemicals. Manufacturers heat high-purity limestone (calcium carbonate) in kilns at roughly 1,000 °C to drive off carbon dioxide (CO₂) and produce quicklime (calcium oxide) and, by adding water, hydrated lime (calcium hydroxide). These are not decorative products — they are reactive chemicals that steelmakers, power plants, water utilities, road builders, and chemical plants consume in bulk. This is a distinct business from quarrying crushed stone or grinding "ag lime": the value is created in the kiln, not the quarry.

For an investor, lime is best understood as a regional, capital-intensive, commodity-processing business with unusual pricing power. Lime is heavy and cheap per ton, so it cannot travel far before freight eats the margin. That physical fact turns most plants into local near-monopolies, and the leading U.S. operators have earned steel-and-cement-beating margins as a result — the one U.S.-listed pure-play runs gross margins near 49% [7][8].

There are few clean ways to own it. The public market offers essentially one U.S.-listed pure-play (United States Lime & Minerals) plus a giant aggregates company (Martin Marietta) that is buying its way to the top of the industry [9][10]. The rest of the field is private or foreign-owned — Belgian, Canadian, and private-equity-backed firms control most U.S. capacity [4][5][6][11]. So private and strategic buyers, not stock pickers, own most of this industry.

2. What it is and how it's structured

Scope (NAICS 327410 — Lime Manufacturing). The industry comprises establishments that manufacture lime — quicklime, hydrated (slaked) lime, and dead-burned dolomite — from calcitic limestone, dolomitic limestone, or other calcareous material. Producers often mine or quarry their own stone, but the defining step is calcination (kiln firing) [1].

Production process. A producer may own the quarry or mine, lease mineral rights, or buy feedstone. Production begins by drilling, blasting, or underground-mining limestone, then crushing, sizing, screening, and washing it. The stone is heated in a rotary or vertical kiln so that calcium carbonate decomposes into calcium oxide and carbon dioxide. The kiln product is quicklime. Producers may crush and size it, add controlled amounts of water to make powdered hydrated lime, or mix it with more water to produce lime slurry or "milk of lime." Dolomitic stone yields calcium-magnesium products; more intensely fired "dead-burned" dolomite is used in refractories. Lime-kiln dust is a coproduct with uses in soil stabilization, remediation, and waste treatment [12][13].

This is normally a vertically integrated, continuous-process business: reserve development, quarry or mine, crushing, kiln, optional hydration or slurrying, storage, and truck or rail delivery. Kilns are large, long-lived, and permitting-intensive. As a company example, United States Lime & Minerals' new Texas vertical kiln was expected to cost approximately $65 million [7].

What it excludes (adjacent codes, so you know where the boundaries are):

• Crushed and broken limestone mining/quarrying — NAICS 212312. Simply digging and crushing stone is mining, not lime manufacturing.
• Ground or treated agricultural limestone ("ag lime") — NAICS 327992 (Ground or Treated Mineral and Earth Manufacturing). Ag lime is ground raw limestone; it is not calcined and is a different product from manufactured (kiln-fired) lime.
• Cement manufacturing — NAICS 327310 — and gypsum products — NAICS 327420. Related building chemistry, different processes.

Terminology note. "Lime," limestone, and cement are not interchangeable. Lime is the calcined product, principally calcium oxide or calcium hydroxide; limestone is the carbonate feedstock and can also be sold uncalcined; cement is a separate hydraulic binder. Even "agricultural lime" frequently means pulverized limestone rather than manufactured quicklime or hydrate [13]. Market reports that combine limestone, lime, and cement materially overstate the addressable market for actual kiln-produced lime.

Ownership mix. This is a concentrated, professionally owned industry, not a fragmented trade of small operators. Federal data count 29 firms across 93 establishments [2][3]. Ownership skews private and foreign: the Belgian groups Lhoist and Carmeuse and Canada's Graymont are among the largest North American producers, alongside private-equity-backed Mississippi Lime [4][5][6][11]. The notable exceptions are publicly traded United States Lime & Minerals and — after a 2026 acquisition — Martin Marietta [7][9][10]. The last authoritative named ranking is USGS's 2019 Minerals Yearbook: Lhoist North America, Graymont, Carmeuse Americas, Mississippi Lime, Martin Marietta Magnesia Specialties, and United States Lime & Minerals were the first six names in descending production order; those ten companies accounted for 99% of commercial lime sales and 91% of total output that year [14].

3. How big it is

Two official yardsticks describe this industry, and they measure different things.

U.S. Geological Survey (production view, 2025 estimate). U.S. producers made about 15 million tons of quicklime and hydrated lime, valued at roughly $4.0 billion — an average of about $265 per ton (value ÷ tonnage). Output came from 24 companies running 70 primary (kiln) plants in 30 states, plus 11 hydrating plants. The five leading companies accounted for about 80% of production, and the top producing states were Alabama, Missouri, Ohio, and Texas [1].

Pricing trend. Recent pricing has been unusually strong. USGS's average plant value for quicklime rose from $149.90 per metric ton in 2022 to $261.40 in 2024 and an estimated $260 in 2025. Hydrated lime rose from $179.10 to $274.20 and then an estimated $280 over the same years. Meanwhile, U.S. production declined from 16.7 million metric tons in 2022 to 15.0 million in both 2024 and 2025. These are average values at the plant, not delivered customer prices [1].

Trade. This is overwhelmingly a domestic and regional market. Imports were 360,000 metric tons, exports were 280,000 metric tons, and net import reliance was below 1%. Canada supplied 76% of imports during 2021–2024 and Mexico supplied 19% [1].

U.S. Census Bureau (business view). Counted as a manufacturing industry, NAICS 327410 recorded (latest federal figures):

Undercount caveat. The Census receipts figure ($2.76 billion) is smaller than the USGS production value ($4.0 billion) for two honest reasons. First, timing and coverage differ (2022 census vs. 2025 estimate, during a period of sharp price increases). Second, and more structural, a meaningful amount of lime is made captively — consumed on-site by the plant that makes it and buried inside another industry's statistics. Kraft pulp-and-paper mills regenerate lime in on-site recovery kilns; some sugar refiners and steel mills burn their own. USGS notes that 8 of its 24 companies produce lime strictly for internal use and excludes independent commercial hydrators from its tonnage [1]. So the merchant market that Census captures understates total U.S. lime activity. The undercount is modest and specific (captive production), not the small-operator or government-dominated blind spot seen in some other industries — lime is capital-intensive and consolidated.

4. The investable universe

Public exposure is thin. There is one U.S.-listed pure-play; everything else is diversified, foreign, or private.

Publicly traded

Major private and foreign owners (not directly investable by public shareholders)

Bottom line: if you want direct public equity in lime, USLM is effectively the only pure bet, and MLM is the diversified way to own the sector's new leader. Most of the industry sits in private and foreign hands.

5. How the money works

Lime economics are a capacity-utilization, energy, and freight story — the toolkit of a commodity processor, not a retailer or a bank.

Revenue = tons × price, and price is unusually sticky. Because lime is dense and low-value, delivered freight can exceed 25% of the product's price [16]. A plant therefore competes only against others within economic trucking or rail distance, and many markets have one or two suppliers. That freight moat gives producers local pricing power: over the recent cycle, list prices rose faster than inflation, and USLM's gross margin expanded from roughly 30% to about 49% [8]. Contracts often include energy surcharges and index escalators, letting producers pass through fuel costs. USLM identifies price, specification, supply reliability, proximity, and delivery timing as primary competitive factors [7].

Cost is dominated by energy and fixed plant. Calcination is intensely energy-hungry — theoretically about 2.77 million British thermal units (Btu) per ton of lime, and more in practice — with energy at 25%+ of production cost [16]. Kilns burn natural gas, coal, or petroleum coke, so fuel prices swing margins directly. Here USLM has a structural edge: its Texas kilns draw natural gas near the Permian Basin's Waha hub, where prices are chronically depressed (occasionally negative), worth an estimated ~$23 million to 2025 results [8]. USLM explicitly says its profitability is exposed to volatile coal, petroleum coke, diesel, natural-gas, electricity, and freight costs, and that it has not undertaken significant energy hedging [7]. The rest of the cost base is fixed (kilns, quarries, labor), so kiln uptime and volume are what turn revenue into profit.

The real moat is reserves. A plant needs a high-purity limestone quarry beside the kiln with decades of permitted reserves. Those assets are scarce, hard to permit, and effectively irreplaceable — which is precisely why Martin Marietta valued Lhoist's 2 billion-plus tons of reserves (200-year life) so highly [9][10]. USLM reports individual reserve lives ranging from approximately 17 years to more than 80 years [7].

What to watch in the financials: capacity utilization, realized price per ton vs. energy cost per ton (the spread), delivered freight, and reserve life. Public-company results show the potential economics of advantaged assets, but should not be treated as industry averages. USLM reported 2025 revenue of $372.7 million, gross profit of $182.4 million (~48.9% gross margin), and operating profit of $157.9 million (~42.4% operating margin). Revenue increased 17.3%, reflecting 11.7% higher volume and a 5.6% increase in average selling prices. The company has a debt-free balance sheet and pays both regular and periodic special dividends [7]. Lhoist North America reported $1.75 billion of 2025 revenue and $786 million of adjusted EBITDA, a 45% adjusted EBITDA margin, in transaction materials — though that calculation includes company-defined adjustments and is not directly comparable with USLM's GAAP operating margin [10].

Cyclicality. The industry is cyclical, though diversified end markets reduce dependence on any single construction cycle. Lime sold or used fell from 19.9 million metric tons in 2008 to 15.8 million in 2009, then recovered to 19.1 million in 2011. Output fell again from 16.9 million metric tons in 2019 to 15.8 million in 2020 as plants temporarily closed during the pandemic [12][17].

6. What drives demand

Lime demand tracks heavy industry, environmental rules, and infrastructure. USGS ranks the U.S. end markets, in descending order of consumption [1]:

1. Steelmaking (largest). Quicklime is a flux that strips impurities into slag. This is the swing factor — and the most cyclical. Independent estimates put steel at roughly a third or more of consumption [18].
2. Chemical and industrial. Fertilizer, glass, paper/pulp, precipitated calcium carbonate (a paper and plastics filler), and sugar refining.
3. Flue-gas treatment. Hydrated lime and quicklime scrub sulfur dioxide (SO₂) and acid gases from power-plant and industrial exhaust — demand created directly by air-quality regulation.
4. Construction. Soil stabilization for roads and building pads, asphalt anti-strip additive, and mortars — driven by highway and infrastructure spending [19].
5. Water treatment. Adjusting pH, softening, and corrosion control in drinking-water and wastewater systems.
6. Nonferrous-metal mining. pH control in gold, copper, and other ore processing.

Quantified end-use split (2021). The latest detailed government breakdown shows metallurgical uses consumed 6.25 million metric tons, including 5.25 million in iron and steel. Environmental uses consumed 4.39 million metric tons, including 2.92 million for flue-gas treatment and 1.22 million for water treatment. Chemical and industrial uses consumed 3.27 million metric tons. Construction consumed 2.08 million metric tons, of which 1.64 million was soil stabilization [12].

The mix matters for stability: steel and construction are cyclical, while environmental and water demand is steadier and regulation-driven, giving diversified producers a buffer. However, the shift from coal-fired power toward natural gas and renewables has reduced utility-sector flue-gas-desulfurization demand, and USLM explicitly notes that significant new U.S. coal-fired generation is unlikely [7].

Historical market shift. USGS notes that more than 90% of present consumption is in chemical and industrial uses broadly construed, whereas more than 80% went to construction at the beginning of the twentieth century [20].

7. Regulation

Regulation cuts both ways for lime — it is a cost on the producer and a demand driver for the product.

As a regulated emitter. Lime kilns are major air-pollution sources. Under the Clean Air Act, the EPA regulates them through the National Emission Standards for Hazardous Air Pollutants (NESHAP) for Lime Manufacturing (40 CFR part 63, subpart AAAAA). In July 2024 the EPA finalized new limits adding four previously unregulated pollutants — hydrogen chloride, mercury, total organic hazardous air pollutants, and dioxin/furans — raising compliance capital costs [21]. Kilns are also large CO₂ emitters, and producers must report greenhouse-gas emissions under 40 CFR part 98, subpart S; in 2023, 68 lime-manufacturing reporters emitted 25.6 million metric tons of direct CO₂-equivalent emissions [22][23].

Compliance costs. EPA estimated $484 million of control capital and approximately $167 million of annual engineering cost (in 2022 dollars) across affected facilities. Its model projected a 5.5% lime-price increase and a 1.4% decline in domestic output, though EPA explicitly lacked lime-specific elasticity estimates; these are modeled effects, not observed outcomes [12]. EPA's current rule page also notes a March 2025 announcement that the agency would reconsider several air rules, so the final compliance trajectory retains policy uncertainty [24].

The carbon problem is structural. Roughly 0.75–0.79 ton of CO₂ per ton of lime is released chemically by calcination itself — unavoidable regardless of fuel, and about two-thirds of a plant's emissions — with fuel combustion adding the rest [16]. That makes lime hard to decarbonize and exposes it to future carbon pricing, but it also opens a path to carbon capture subsidized by tax credits (e.g., U.S. Section 45Q). DOE has supported an initial design for a system intended to capture at least 95% of process-stream CO₂ at a Carmeuse Kentucky plant, though this remains technology-development evidence, not proof of commercial industry-wide economics [25]. This is the industry's biggest long-term regulatory swing factor.

As a beneficiary. Tighter air rules (SO₂ scrubbing), drinking-water and lead-corrosion rules, wastewater standards, and acid-neutralization requirements all increase lime demand. Environmental regulation is, on net, a tailwind for volumes even as it raises the cost of running a kiln.

8. Competitive dynamics and consolidation

Lime is concentrated nationally and even more so regionally. The top four firms hold 82.6% of shipments and the HHI of 1,931 sits in the "moderately concentrated" band [3]; USGS's top five make ~80% of tonnage [1]. But those national numbers understate reality — because freight limits competition to a local radius, many individual markets are effective duopolies or monopolies, which is the source of the pricing power. Low imports do not mean weak competition — the market is intensely competitive within regional freight sheds. Its apparent insulation comes from heavy products, high delivery cost, customer specifications, permitted mineral reserves, and the need for dependable continuous supply.

Barriers to entry are steep: permitted high-purity reserves, large kiln capital, air permits, and the freight moat around incumbents. New national entrants are essentially unheard of.

The defining event is the 2026 consolidation. On June 27, 2026, Martin Marietta agreed to acquire Lhoist North America for $13.5 billion ($7 billion cash + $6.5 billion stock), a deal set to make Martin Marietta the largest lime-and-limestone producer in the U.S. Lhoist NA generated ~$1.8 billion of 2025 sales and ~$786 million of adjusted EBITDA — a 45% margin — and brings 2 billion-plus tons of reserves [9][10]. The strategic signal is clear: cash-rich aggregates majors now see lime's margins and pricing power as worth premium multiples, and further consolidation (and antitrust scrutiny) should be expected. The deal is subject to regulatory review and expected to close in the second half of 2026 [9][10]. The disclosed transaction equates to approximately 15 times 2025 adjusted EBITDA including expected run-rate synergies, but it is a national-scale strategic transaction and should not be treated as a private-market multiple for smaller regional plants [10].

9. Risks

• Steel and construction cyclicality. The largest end markets are tied to the industrial and building cycle; a steel or infrastructure downturn hits volumes and pricing.
• Energy prices. Fuel is 25%+ of cost; a natural-gas or coal spike compresses margins quickly, and low-cost-gas advantages (e.g., Permian) can reverse.
• Carbon and compliance costs. Unavoidable process CO₂ makes lime exposed to future carbon pricing; the 2024 NESHAP tightening and decarbonization capex raise the cost of doing business. EPA estimated $484 million in control capital across the industry [12][16][21].
• Freight inflation. The freight moat works both ways — rising trucking/rail costs raise delivered prices and can shrink each plant's serviceable market. Because some customers buy on delivered-price terms, diesel increases may remain with the producer [7].
• Concentration and antitrust. Regulatory review could constrain further consolidation (and the Martin Marietta–Lhoist deal itself).
• Single-asset / regional exposure. Smaller producers depend on a handful of plants and quarries; a reserve, permit, or kiln problem is material.
• Demand substitution. Substitutes are application-specific rather than universal. EPA identifies crushed limestone in some agricultural, steel-flux, and emissions-control applications; cement, cement-kiln dust, fly ash, and lime-kiln dust in some construction uses; calcined gypsum in certain plasters and mortars; magnesium hydroxide for pH control; and magnesium oxide for dolomitic lime in steelmaking. Substitution risk is highest where a customer primarily needs alkalinity or bulk stabilization and lower where lime's reaction speed, purity, or process behavior is qualified and critical [12].
• Coal-plant retirements. The shift from coal toward natural gas and renewables has reduced utility-sector flue-gas-desulfurization demand [7].
• Permitting risk. Quarry expansion may require zoning, land-use, blasting, water, and reclamation approvals; kilns require air permits. Community opposition or stricter limits can delay capacity additions.
• Operating risks. Variable stone chemistry, mine conditions, kiln or crusher failure, refractory and maintenance outages, weather, utility interruptions, and mine safety and reclamation liability. A kiln outage can be especially costly because customers use lime continuously and may qualify alternative suppliers [7].
• Thin float / control. USLM, the only pure-play, is closely controlled by a majority shareholder, limiting the tradable float and minority-holder influence [7].

10. How to invest, and the outlook

Public-market routes.

• United States Lime & Minerals (Nasdaq: USLM) — the only U.S.-listed pure-play. Debt-free, high-margin (~49% gross, ~42% operating), dividend-paying, with a low-cost gas position; but closely held (thin float) and single-industry, single-region concentrated [7][8].
• Martin Marietta (NYSE: MLM) — the diversified way to own the sector's emerging leader once the Lhoist deal closes, blended with a large aggregates business [9][10].
• Foreign/diversified names — Imerys (Euronext: NK) for lime within a broader minerals group; aggregates majors like Vulcan (VMC) and Eagle (EXP) offer only incidental lime exposure [15].

Private-market routes. Most U.S. capacity is private or foreign — Lhoist, Carmeuse, Graymont, Mississippi Lime — so direct private access comes through private-equity and infrastructure ownership of these platforms (Mississippi Lime is PE-backed) or through industrial buyout funds, not a liquid market for physical lime [4][5][6][11]. A buyer can acquire a regional integrated quarry-and-kiln platform, a captive industrial lime operation, or distribution and hydration assets, but reserve quality, permits, fuel flexibility, and delivered-market radius matter more than nominal nameplate capacity. There is no practical retail commodity route.

Near-term drivers (forward-looking judgment). Volumes hinge on U.S. steel output and on infrastructure/road spending (soil stabilization), with steadier support from environmental and water demand. In 2025, USLM attributed volume growth chiefly to construction, environmental, and steel customers, partly offset by weaker oil-and-gas-services demand [7]. Margins depend on the price-vs-energy spread, which has been historically wide; the risk is normalization if gas prices spike or steel softens. The Martin Marietta–Lhoist combination will reshape competition and likely invites more consolidation and antitrust attention. Longer term, the carbon question — the cost of unavoidable process CO₂ versus the opportunity in subsidized carbon capture — is the single biggest variable that could either erode or entrench the industry's economics. On balance, the freight moat, reserve scarcity, and regulation-driven environmental demand make this a structurally attractive but cyclical and capital-heavy industry, where ownership — not trading — is how most of the money is made.

---

Sources

1. U.S. Geological Survey, Mineral Commodity Summaries 2026 — Lime, 2026. https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-lime.pdf
2. U.S. Census Bureau, County Business Patterns 2023 (NAICS 327410 — establishments, employment, payroll), 2023. https://www.census.gov/programs-surveys/cbp.html
3. U.S. Census Bureau, 2022 Economic Census — Concentration & Receipts (NAICS 327410: firms, receipts, CR4/CR8, HHI), 2022. https://www.census.gov/programs-surveys/economic-census.html
4. U.S. Small Business Administration, Table of Small Business Size Standards (NAICS 327410 = 1,050 employees), 2023. https://www.sba.gov/document/support-table-size-standards
5. Lhoist North America — company profile (Belgian-owned; ~20 quarries/facilities, 45 terminals; ~$1.8B gross sales), 2025. https://rocketreach.co/lhoist-north-america-inc-profile_b5c68ec5f42e0ce3
6. Wikipedia, Carmeuse (Belgian, private; ~14 U.S. plants, ~8.7M tons capacity, ~1,400 employees), 2025. https://en.wikipedia.org/wiki/Carmeuse
7. United States Lime & Minerals, Inc., 2025 Form 10-K (revenue $372.7M; gross profit $182.4M; operating profit $157.9M; reserve lives; risk factors), SEC EDGAR, 2026. https://www.sec.gov/Archives/edgar/data/82020/000110465926020480/uslm-20251231x10k.htm
8. Macrotrends, United States Lime & Minerals Gross Margin (expansion to ~49%) and USLM analysis (Waha gas advantage), 2025. https://www.macrotrends.net/stocks/charts/USLM/united-states-lime-minerals/gross-margin
9. Martin Marietta Materials, Martin Marietta to Combine with Lhoist North America in $13.5 Billion Transaction (announced June 2026; $7B cash + $6.5B stock; largest U.S. lime+limestone producer), IR News Release, 2026. https://ir.martinmarietta.com/news-releases/news-release-details/martin-marietta-combine-lhoist-north-america-135-billion
10. Martin Marietta Materials, Form 8-K and Transaction Presentation (Lhoist NA 2025 ~$1.75B revenue / ~$786M EBITDA / 45% margin; 2B+ tons reserves; ~15x EV/EBITDA with synergies), SEC EDGAR, 2026. https://www.sec.gov/Archives/edgar/data/916076/000095015726000758/ex99-2.htm
11. Growjo / IBISWorld, Graymont & Mississippi Lime company profiles (Graymont ~$1B revenue; Mississippi Lime PE-backed via HBM Holdings), 2025. https://growjo.com/company/Carmeuse_Lime_and_Stone
12. U.S. EPA, Regulatory Impact Analysis: NESHAP for Lime Manufacturing Plants Technology Review (2021 end-use breakdown; compliance costs; cyclicality data), June 2024. https://www.epa.gov/system/files/documents/2024-06/ria_lime_manufacturing_neshap_final_2024.pdf
13. National Lime Association, How Lime Is Made (production process overview; terminology), 2025. https://www.lime.org/resource/how-lime-is-made/
14. U.S. Geological Survey, 2019 Minerals Yearbook — Lime (named producer ranking; top-10 companies = 99% commercial sales), 2021. https://pubs.usgs.gov/myb/vol1/2019/myb1-2019-lime.pdf
15. Market Data Forecast / Ken Research, U.S. & North America Lime Market (key players; end-market context), 2025. https://www.marketdataforecast.com/market-reports/united-states-lime-market
16. European Lime Association (Ecofys), A Competitive and Efficient Lime Industry and related life-cycle analyses (energy ~25%+ of cost; ~2.77 MMBtu/ton; ~0.79 tCO₂/t process emissions ≈ 65% of total; freight >25% of price), 2019. https://www.eula.eu/wp-content/uploads/2019/02/A-Competitive-and-Efficient-Lime-Industry-Technical-report-by-Ecofys_0.pdf
17. U.S. Geological Survey, Mineral Commodity Summaries 2023 (historical production data), 2023. https://pubs.usgs.gov/periodicals/mcs2023/mcs2023.pdf
18. IndexBox, Calcium Oxide Market Outlook (steel ~one-third-plus of lime consumption), 2025. https://www.indexbox.io/blog/calcium-oxide-market-growth-trajectory-points-higher-toward-2035-driven-by-steel-and-environmental-demand/
19. National Lime Association, Lime-Treated Soil Construction Manual (soil stabilization uses), 2004. https://www.lime.org/wp-content/uploads/construct-manual2004.pdf
20. U.S. Geological Survey, Lime Statistics and Information (historical market shift: >90% industrial now vs. >80% construction early 20th century), current. https://www.usgs.gov/centers/national-minerals-information-center/lime-statistics-and-information
21. U.S. EPA / Federal Register, NESHAP: Lime Manufacturing Plants Technology Review (final rule adds HCl, mercury, organic HAP, dioxin/furan limits), July 16, 2024. https://www.federalregister.gov/documents/2024/07/16/2024-14692/national-emission-standards-for-hazardous-air-pollutants-lime-manufacturing-plants-technology-review
22. U.S. EPA / eCFR, 40 CFR Part 98, Subpart S — Lime Manufacturing (greenhouse-gas reporting), current. https://www.ecfr.gov/current/title-40/chapter-I/subchapter-C/part-98/subpart-S
23. U.S. EPA, GHGRP Minerals Profile (68 lime reporters, 25.6M tCO₂e in 2023), 2024. https://www.epa.gov/ghgreporting/ghgrp-minerals
24. U.S. EPA, Lime Manufacturing Plants NESHAP (rule status; March 2025 reconsideration announcement), current. https://www.epa.gov/stationary-sources-air-pollution/lime-manufacturing-plants-national-emission-standards-hazardous
25. U.S. Department of Energy, Net-Zero Lime Kiln and Carbon Removal Facility (Carmeuse Kentucky plant; 95% CO₂ capture design), NEPA, 2025. https://www.energy.gov/nepa/articles/cx-027632-net-zero-lime-kiln-and-carbon-removal-facility