627 F.2d 416 (D.C. Cir. 1980), 78-1385, National Lime Ass'n v. E.P.A.

Docket Nº:78-1385.
Citation:627 F.2d 416
Party Name:Envtl. NATIONAL LIME ASSOCIATION, Petitioner, v. ENVIRONMENTAL PROTECTION AGENCY and Douglas M. Costle, Administrator of Environmental Protection Agency.
Case Date:May 19, 1980
Court:United States Courts of Appeals, Court of Appeals for the District of Columbia Circuit

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627 F.2d 416 (D.C. Cir. 1980)





Administrator of Environmental Protection Agency.

No. 78-1385.

United States Court of Appeals, District of Columbia Circuit

May 19, 1980

Argued Dec. 11, 1979.

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Arthur A. March, Englewood, Colo., a member of the bar of the Supreme Court of Connecticut pro hac vice by special leave of court with whom Henry W. Leeds, Washington, D. C., was on the brief, for petitioner.

Earl Salo, Atty., EPA, Washington, D. C., with whom Joan Z. Bernstein, Gen. Counsel,

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EPA, James W. Moorman, Asst. Atty. Gen., Angus MacBeth and Raymond W. Mushal, Attys., Dept. of Justice, Washington, D. C., were on the brief, for respondents.

Before TAMM and WALD, Circuit Judges, and GREENE [*], United States District Judge for the District of Columbia.

Opinion for the Court filed by Circuit Judge WALD.

WALD, Circuit Judge:

The National Lime Association (NLA), representing ninety percent of this country's commercial producers of lime and lime hydrate (the industry), challenges the new source performance standards (NSPS) for lime manufacturing plants issued by the Environmental Protection Agency (EPA, Administrator or Agency) under § 111 of the Clean Air Act (the Act), 42 U.S.C. § 7411 (Supp. I 1977). The standards limit the mass of particulate that may be emitted in the exhaust gas from all lime-hydrating and from certain lime-manufacturing facilities and limit the permitted visibility of exhaust gas emissions from some facilities manufacturing lime. We find inadequate support in the administrative record for the standards promulgated and therefore remand to the Administrator.


A. The Industry

In sheer size and weight of production, the limestone industry ranks among the largest in this country. Limestone production in the United States ranks second only to sand and gravel in commodity tonnage and exceeds petroleum, coal and iron ore in volume produced. Limestone deposits can be found beneath an estimated fifteen to twenty percent of the surface of the United States and occur in every state. Total national production approximates twenty-two million tons annually and derives from plants in over forty states. 1

The recent development of two important industrial uses for lime 2 has ensured the continuing growth of production 3 despite a decline in agricultural use. 4 The industry is capital-intensive with declining employment, but because so many other industrial processes depend on the use of lime, any decline in production would have "a large multiplier effect on U.S. employment." 5

B. The Production of Lime From Limestone

The process by which commercially valuable lime is produced is relatively simple. Limestone is quarried, crushed, sized and fed into a kiln where it is subjected to high temperatures (1100o C/2000o F). By a process

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known as "calcination," the heating ("burning") of limestone produces quicklime, a soft, porous, highly reactive material commonly used in industry. As might be expected, the process generates a substantial quantity of dust, or in the language of the Agency, particulate matter, sufficiently lightweight to be carried off in the hot exhaust gas and emitted from the kiln. The particulate matter thus released is composed of partially burned limestone, raw limestone feed, deadburned lime 6 and quicklime. Typically, the process also releases sulfur dioxide (SO 2). 7

Almost ninety percent of total United States lime production is processed in rotary kilns. 8 Uncontrolled emissions from rotary kilns have been reported to run from 150 to 200 pounds per ton of lime produced, roughly five percent of the feed poundage and nine percent of the produce. 9 A typical lime plant 10 producing 500 tons per day from a rotary kiln, conforming to typical state pollution-control standards, 11 emits about 150 megagrams (165 tons) of particulate matter per year. Rotary kilns produce a greater volume of particulate emissions than the formerly widely used vertical kilns but they are also the only kilns which can retain product quality while burning coal, a fuel on which the industry has become increasingly dependent. 12

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C. The Production of Hydrated Lime

A comparatively small amount (ten percent) of all lime produced is further processed into hydrated or slaked lime. This is done by adding water to lime and introducing the mixture into an agitated hydrator. An exothermic reaction occurs and a fluffy, dry, white powder, known as hydrated lime, is the result. 13 Particulate matter is carried off in the steamy exhaust emitted from the hydration process.

D. Emissions Control in the Production of Lime

Rotary kilns here and abroad have employed several different methods of emissions controls including the fabric filter baghouse, the electrostatic precipitator (ESP), the high energy scrubber, and the gravel bed filter. 14 One survey showed that of eighty-five domestic rotary kilns, twenty-four percent used a baghouse, thirty-one percent used a high energy scrubber and eight percent used an ESP. 15 However, use of the baghouse method is increasing because this method requires less energy and does not itself create additional problems of pollution control. 16

EPA has identified baghouses, ESPs and scrubbers as "best systems" of emissions control for rotary lime kilns. 17


The operation of baghouses and electrostatic precipitators was briefly explained in our initial review of EPA's performance standards for portland cement plants, Portland Cement Association v. Ruckelshaus, 486 F.2d 375, 390-91 (D.C.Cir. 1973), cert. denied, 417 U.S. 921, 94 S.Ct. 2628, 41 L.Ed.2d 226 (1974) (hereinafter cited as Portland Cement I ). The baghouse method employs fabric filters ("bags"), situated within an enclosed area (a "house"), to remove particulate from the kiln exhaust gas which is channeled through the house.

As the exhaust gas passes through, a dust cake forms on the filters. The cake itself improves filtration efficiency, but from time to time the filters must be cleaned. This is done by forcing a reverse gas flow through the fabric, thus releasing the cake for disposal.

EPA acknowledges that fabric filter effectiveness is primarily a function of kiln exhaust particle size distribution, fabric type, fabric age and maintenance history. 18

Electrostatic Precipitators

Under this method, "dust particles are charged (by discharge electrodes) and pass through an electrical field (collector plates) of the opposite charge, thus causing the dust to be precipitated out of the exhaust gas . . . ." Portland Cement I, 486 F.2d at 390. Two basic criteria must be met before an ESP can be utilized: (1) the suspended particle must be able to accept an electric charge; and (2) the particle must then pass through an electric field of sufficient strength to ensure removal of the particulate from the gas stream at the desired efficiency.

Precipitability is a function of the chemical composition of the dust particles, and will vary with the different kinds of material that make up the kiln exhaust dust (limestone, quicklime, fly ash, calcium sulfate, etc.). 19 Assuming precipitability, the two main factors influencing the efficiency of a precipitator are the gas velocity and treatment time. The ESP method experiences a relatively low collection efficiency on submicron particles.

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Although most particles collected by an ESP fall by gravity into waiting hoppers, programmed rapping of the electrodes is also required to keep the collector plates and discharge electrodes clean. As with the baghouse method, the dust collected is dry and may be disposed of in a variety of ways. A high level of maintenance skill is needed to keep an ESP in operation at design conditions.


Scrubbers operate on the principle that wet particles are easier to control than dry. High pressure (or high energy) scrubbers of the type EPA considers capable of meeting the promulgated standards are those which because of their design increase the likelihood of contact between particle and water.

The most common high pressure drop scrubber used for controlling emissions from rotary lime kilns is the venturi scrubber. This scrubber operates by accelerating the velocity of the exhaust gas through a narrow venturi-shaped throat, where it is then brought into contact at great force with a spray of water. The particles thus dampened coalesce to form a slurry that can then be collected by a comparatively simple water-gas separation device. The separated gas is then released into the atmosphere.

The efficiency of particulate removal is a direct function of energy input, measured by pressure drop across the venturi throat. 20 Gas-water contact in the venturi scrubber is so thorough that even submicron particles are removed. Although low pressure drop scrubbers use less energy than high pressure drop scrubbers, even a low efficiency scrubber requires more energy than either the baghouse or the ESP. The slurry which is the by-product of scrubber use is deposited in ponds, where the collected particulate settles out from the scrubbing water. The "clean" scrubbing water is then reused. Under present law settling ponds must be located so that they do not receive excessive rainwater run-off, causing overflow into local navigable waters.

E. Emissions Control in the Production of Hydrated Lime

Hydration emissions have been...

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