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Original set of GORE® membrane filter bags were in service for more than three years and were removed during a planned maintenance shutdown. Emission levels measured less than required by standards/regulations during this operational period.

An emergency order was placed for GORE® Low Emission Filter Bags. The new filters were rushed to the plant site, where the leaking filters were completely replaced.

A South African producer of silicomanganese (SiMn) with five submerged arc furnaces tapped GORE LOW DRAG Filter Bags to help expand its production capacity through greater emissions control and overall cost savings.

The system now runs with a consistent airflow of 41,000 acfm and compartment pressure drops of 4.5 - 6.5" H2O. The customer is able to run two ladles simultaneously, increasing metal throughput.

After the GORE Filter Bags were installed, bag life increased from one year to five years. Production downtime caused by the need to replace bags prematurely was virtually eliminated.

Results showed furnace extraction has been increased by 41%, blockage was eliminated from furnace offtake ducts, hood temperatures were been reduced and stack emissions were below 5 mg/Nm3.

Extraction at the furnace has increased above the design. The main fan damper is partially closed to control the extraction at the furnace. Tapping fume has been added into the same baghouse. The smelt house environment is much cooler, and it led to a decrease in maintenance of the electrode system and mechanical stokers.

System optimization and installation of GORE filter bags resulted in improvements to the baghouse and overall production process. Emissions from all the filters are well below 10 mg/Nm, maintenance on the filters has been significantly reduce, and extraction volumes from the furnaces have been significantly increased, leading to lower stack temperatures.

With the new high temperature membrane filter media, required dilution air from the canopy hood is reduced and furnace suction pressure is consistently maintained, reducing furnace fugitive emissions.

Bag failures stopped since the GORE ePTFE membrane and the fiberglass backing material are not subject to hydrolysis and resist spark damage. The bags have not required tensioning since start up. Furnace suction and shop evacuation have improved due to the more consistent operation of the baghouse.