Análisis Estadístico Multivariable

Plant Discharge Crusher Hot Screen Cooler Cold Screen

Bethlehem, IN Baghouse Baghouse Baghouse None N/A

Inland Steel, IN Baghouse Baghouse Baghouse Baghouse None

LTV Steel, IN Scrubber Scrubber Scrubber None None

U.S. Steel, IN Baghouse Baghouse Baghouse None Baghouse

Bethlehem, MD Baghouse Baghouse Baghouse Cyclone Baghouse

AK Steel, OH Baghouse Baghouse Baghouse Baghouse Water sprays

WCI Steel, OH Baghouse Baghouse Baghouse Baghouse Baghouse

Wheeling-Pitt, OH Baghouse N/A N/A Water sprays Water sprays

Geneva Steel, UT Rotoclone N/A Rotoclone N/A N/A

* Certain transfer points are controlled by the discharge baghouse. 4.1.3 Materials Handling

Emissions from material handling are generally fugitive emissions and are usually uncontrolled.

These emissions result from material storage, materials mixing, and sinter storage. Fugitive emissions

escaping the raw material handling equipment are normally confined within the building in which they are

processed, and primarily affect the worker environment. Only one sinter plant in the country uses a

baghouse to control emissions from material storage and handling; the remaining plants use no control.

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the building. One plant, however, uses water sprays to wet the materials at the various transfer points.

While water sprays by themselves may be effective on materials such as dry ore, they are not effective

in controlling hot fines. Emissions from sinter storage are generally uncontrolled, although one plant

uses chemical dust suppression on the product.

4.1.4 Capture and Control System Performance.

Windbox capture efficiencies were reported by six companies in a 1993 industry survey and by

one company in a 1991 screening survey response. These efficiencies range from 93 to 99.9 percent

based on engineering estimates. Control device efficiencies varied considerably, ranging from 96.2 to

99.5 percent for a baghouse and from 70 to 99+ percent for a wet scrubber.

4.1.5 Pollution Prevention

Pollution from sinter plants is generated by particulate emissions from various emission points

and by organic emissions from the windbox. Sinter plants serve as a means of recycling waste iron-

bearing materials that would otherwise be landfilled from other processes at an integrated iron and steel

facility and within the sinter plant itself. The use of sinter plants is an effective pollution prevention

measure, but significant quantities of particulate and organic compounds are generated as a result of the

recycling process.

One of the major sources of organic emissions in the sinter plant is from oily mill scale blended

into the feed materials. One way to reduce organic emissions in the sinter plant would be to set a limit

for the oil content of the sinter mixture or for the amount of oily mill scale that a plant may use. Even

though a high energy wet scrubber may be able to handle larger quantities of oil than a comparable

baghouse system, limiting the amount of oil for all plants may reduce organic emissions. Another option

4.2 BLAST FURNACE 4.2.1 Casthouse

Emissions from molten iron and slag occur primarily at the tap hole of the blast furnace and in

the iron trough immediately adjacent to it. Emissions also result from the runners that transport the iron

and slag and from the ladle that receives the molten iron. These emissions include flakes of graphite

(carbon) called "kish" that is released as the metal cools (because the solubility of carbon in the metal

decreases as it cools) and metal oxides that form when the reduced metal (e.g., iron, manganese) reacts

with oxygen in the air.19 _{Factors affecting these emissions include the duration of tapping, exposed}

surface area of metal and slag, length of runners, and the presence/absence of runner covers and flame

suppression, which reduce contact with air.

Table 4-3 presents the capture and control systems in place on each furnace in the industry.

Three furnaces at three facilities did not report the presence of capture or control systems for emissions

from the casthouse. A combination of flame suppression and covered runners is most commonly used

at the remaining furnaces in the industry; in addition, more than one-third of the furnaces evacuate

emissions to a control device, most commonly a baghouse.

Flame suppression consists of blowing natural gas over the iron runners and torpedo cars. The

combustion of the gas consumes oxygen, which suppresses emissions. In addition to flame suppression,

many facilities use covered runners on the iron and slag runners. Most furnaces have a removable

cover over the iron trough; the cover is removed during drilling of the furnace and is quickly put back

into place when the molten iron starts to flow. The cover is removed again at the end of the tap to plug

the taphole with refractory clay.

One method of controlling emissions from the casthouse is to totally enclose the casthouse and

evacuate it to a baghouse. Alternatively, there may be localized hooding over the iron trough, iron and

slag runners, and hot metal ladles that are evacuated to a baghouse. Two furnaces at one facility use a

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