Severstal completes construction of environmental facilities for new blast furnace
by David Fleschen
PAO Severstal, one of the world's leading vertically integrated steel and mining companies, has completed the construction of environmental facilities for blast furnace No. 3.
The modernization of blast furnace No. 3 will mitigate the environmental impact of pig iron production throughout the production chain through use of the best available technologies.
The main environmental advantage of the dust and gas capture facilities is the aspiration system and gas cleaning system. The aspiration system cleans the air from the dust of workplaces and technological operations. The gas cleaning system cleans the blast furnace gas.
The main operational activities during which pollutants are released into the atmosphere from blast furnace No. 3 are the preparation and dosing of charge materials, loading the charge into blast furnaces, and operating the casthouse. By covering dust and gas formation sites, the aspiration suction system, featuring control and shut-off valves, extracts contaminated air and gas for cleaning.
The aspiration valves are automatic. The process is organized from the places of discharge of cast iron and slag, using a skimmer and side suction from the tap holes, which are covered. As the release of fusion products is carried out simultaneously from just one tap hole, suction is cut off from the other notches. The operating mode of the valves is synchronized with that of the casting equipment.
To prevent emissions of pollutants when loading materials into the furnace (through a coneless loading device), emissions from the loading device are suppressed using compressed nitrogen, which is used to blow dirty gas from the blast furnace under the furnace top. Dusty air from the intake chamber of the coneless loading device will be directed to the collector at the new central exhaust station (CVS).
Cleaning the aspiration air from dust will be carried out by bag filters. The filter consists of 1056 hoses, each 10m long. The particular bag filters procured by Severstal are characterized by their compactness and large filtration area, which enables them to work effectively in cramped conditions.
Residual dust content of the air is below 8 mg / m3, which will be released through an 80m chimney. Severstal invested 850 million rubles in the aspiration system, amounting to 2.5% of the total blast furnace No. 3 modernization costs.
Cleaning the gas from the blast furnace comprises two stages of cleaning - dry and wet. The cleaning process, which is 99.99% effective, involves dry cleaning the blast furnace gas in a cyclone-style dust collector and a scrubber with an adjustable gap and a drop collector designed by Paul Wurth. The dust caught in the dust collectors is then transferred to the sintering plant for disposal. Before unloading the dust collectors, the dust is first moistened to prevent dust emissions.
Gas from the blast furnace fuels the air heaters, which provide the blast furnace with hot blast. The cost of construction of the gas treatment plant according to the project is 1,083 million rubles, 3.3% of the project’s total investment.
Water is supplied to blast furnace No. 3 through the closed-loop water circulation system. With the launch of blast furnace No. 3, there is no increase to the consumption of household and stormwater wastewater entering the household and industrial waste systems. There are no direct discharges from the blast furnace No. 3 complex into water bodies.
The project also features a waste management scheme. Almost all waste (99.99%) is utilized in production, with the remainder transferred for disposal at Severstal’s industrial waste landfill facility.
Source: Severstal, Photo: Foolia