The year 2008 is symbolical for Zaporizhstal not only because of its 75th Anniversary. There’s a hope that it will go down into history as a year of the beginning of the construction of the oxygen-converter shop because a contract has already been concluded on the delivery of the main processing equipment for the new steel making complex. According to the contract the Austrian firm “SIEMENS-VAI” is to delivery to the Works 2 converters of capacity 250 tons each, 2 ladle-furnaces, one vacuumator, 2 steel continuous casting machines and two units for hot metal desulphuration. In the new shop production of 4.7 million tons of steel is foreseen.
The output of the converter shop is calculated in such a way to use the full capacity of the blast furnace shop. 4 million tons of pig iron per year will be produced by 4 furnaces.
At the first stage it is foreseen that 2 million tons of cast slabs will pass through the continuous furnaces of the hot strip mill shop. The quality of these slabs will be much higher than the quality of the rolled ones. Today their price is the same as our hot rolled coils. In the future it will be possible to sell cast slabs as commercial products of the Works and about 2.7 million tons of such slabs could be sold annually depending on the market demand.
The Works has already transferred the first tranche under the terms of the contract and is continuing preparation work for this big new building project. Transfer to the converter method of steel production will open new possibilities for our Works, increase its rating among world producers of steel and, what is of great importance, will deprive us of many old problems, including ecological ones.
But if the construction of the converter complex is the future, then the construction of the PCI unit is today’s reality, about which it can be spoken of in the present tense because its construction has already started and it is planned to put this strategic object into operation in 2009.
The strategy of this project is to exclude the use of natural gas from the blast furnace production process as soon as possible. The reasons for such a solution are well known: each citizen of the city has noticed how the gas prices have skyrocketed, in private life too. And this is not a limit. The situation in the metallurgical production is even more complicated and that is why it should not continuously depend on the political situation and speculations of home and foreign owners of power resources.
This construction started in February this year after a contract was concluded with the German firm “Kuettner”. It is being fulfilled by the general contractor SMU “Zaporozhstalstroy-1” under the supervision of the Deputy Technical Director of the Works, O.M. Klevtsov. Introduction of the PCI unit foresees complete replacement of expensive natural gas, which is delivered to the blast furnace tuyeres, and partial, up to 10%, replacement of such an expensive melting element, as coke. Under the terms of the contract we are to achieve the guaranteed flow rate of 150 kg of pulverized coal per ton of pig iron. This will allow to completely give up the usage of natural gas, 100 m3 of which is used today to produce 1 ton of pig iron and reduce by 50 kg the consumption of coke for the production of each ton of pig iron. Due to the introduction of a PCI unit special demands are made on the coke quality, i.e. why we are busy solving problems connected with the improvement of coke quality delivered to us by the Zaporozhye coke oven plant.
The pulverized coal preparation department of the PCI complex is being built on the site of the dismantled blast furnace No.1. Two lines for pulverizing and drying coal will be located here. The main aggregate of each line will be a roller mill with a capacity of 52.5 tons per hour each. This is a rather complicated device. Lumps of coal with humidity up to 13% are delivered from bunkers into the mills and dry pulverized coal comes out with humidity not more than 1%. This actually is that particular fuel which from the bunkers by pneumatic pumps will be transported under high pressure nitrogen to the distributing units of each blast furnace. These devices distribute the flow of pulverized coal to each air tuyere individually. Pulverized dust will be blown through the tuyeres together with oxygen which will enter the furnace through the lance. And already in the furnace fuel and the burning intensifier will help to produce pig iron. Injection of oxygen together with pulverized coal is a brand of firm “Kuettner”, which has designed the PCI unit. The German designers insist that using such a method increases the effect of pulverized coal combustion. The heat transfer from combustion of 150 kg of pulverized coal per one ton of pig iron is the same as when firing 160 kg without the usage of oxygen.
Today blast furnaces of our Works are using much less oxygen than other metallurgical enterprises due to the highest blast temperature (average temperature 11700C in the shop). One more significant point is to be mentioned. When making out the project a lot of the Works’ measures regarding energy saving have been taken into consideration. In particular, it is foreseen to utilize the heat of cowper stove gas with temperature from 1500 to 3500C in pulverized coal gas generators to produce drying gas. In short, firm “Kuettner” offered us a rather economical technology which is working efficiently at iron and steel works in Germany where they have never known such luxury as natural gas.
The construction of the unit is still in the initial stage. It is getting more complicated due to the peculiarity of the earth in that area. To strengthen the foundation of the pulverized coal preparation department 459 reinforced concrete pilings and in less than 24 hours 380 m3 of concrete has been underpoured into the foundation of the pulverized coal preparation department. The framework of the buildings of the distribution units for PCI into the blast furnace have been mantled, certain other jobs are being accomplished in correspondence with the approved PCI unit construction schedule. Its construction is of prime importance. This is well known to the specialists of SMU “Zaporozhstalstroy-1”, responsible for the construction work, and the specialists of the Works, responsible for its putting into operation in due time.