.
In the past two to three years, following its final
winning bid in the 1997 Bank of Asia tender for Guiyang Steel, where it signed a contract to supply a complete EF+Constanti system to Guiyang Steel, DEXING Group has succeeded in obtaining the contracts for the Xining
Steel Plant, Lianyuan Iron & Steel, Shaoguan Iron & Steel, and Wuxi Xuelang Iron & Steel, Jigang Shihang Iron & Steel, Lake
North China Iron & Steel, and the Wuxi Iron & Steel, which are the largest steel mills in the world.
North E-cheng Iron and Steel Company of the electric furnace + Constanti system supply contract. Among them, the EF+Constanti systems of Xining Steel, Guiyang Steel and Shaoguan Steel have been successfully put into production one after another in 2000.
On April 3, 2000,
Xining Steel produced 7 furnaces of qualified steel on the first shift of the ignition of the furnaces, and on the subsequent night shifts, the workers, without on-site guidance of the foreign experts,
achieved operate on their own and produce continuously. Has entered a stable
production stage, the highest daily steelmaking 24 furnaces, the average daily output maintained at about 20 furnaces, and has been in November 2000 through the
all performance tests. In addition, Shaoguan Iron and Steel Company's 90-ton CON-STEEL electric furnace now has a daily output of more than 31 furnaces; no
Tin Xuelang Iron and Steel Company's 75-ton CON-STEEL electric furnace on September 6, 2001 began to refine the first furnace, September 14, that is
to reach the level of 20 furnaces of steel per day.
CON-STEEL electric furnace smelting process has ten major features:
First, the scrap preheating: before the scrap is fed into the furnace, the flue gases generated by the furnace are preheated in the preheating section of the infeed channel, with an average
temperature of 600--650C; second, the steel retention operation: there is at least 30 tons of molten steel in the electric furnace, and then the continuous feeding, electrode
feeding, and the carbon-oxygen lance operation. Electric furnace always work in the flat molten pool state, can reduce the arc fluctuations; Third, continuous
feeding: no need to frequently stop and open the furnace cover, reduce heat loss; Fourth, the electric furnace body structure is reasonable: supporting the T
BT eccentric bottom outlet device, tube water-cooled furnace cover, the furnace wall, the furnace identity of the upper and lower, the two segments, easy to repair and maintenance; Fifth
is the furnace is set up to blowing system: The use of supersonic water-cooled oxygen gun, self-consumption carbon spray gun and carbon spray system; six is an advanced conductive
system: transformer for the side of the line, the use of copper, steel composite electrode arm and electrode water-cooled spray system; seven is the operation of
operation technology is simple: to stay in the steel to stay in the dregs, the foam slag submerged arc single melting pot smelting operation technology; eight is the set up of a mechanized charging
system: the electric furnace is set up with two sets of charging system. Among them, one set of bulk material charging system is specially used for charging to CON-STEEL
system; one set of post-furnace ferroalloy charging system is used for deoxidizing and initial alloying in the process of steel production after the furnace
; nine is the advanced dedusting system: the furnace adopts the dedusting facilities with the main function of CONSTEEL exhaust and dust removal and the roof hood is set up for the auxiliary function of smoke removal
; Ten is to ensure that the furnace flue gas fully combustion CO and eliminate harmful gases, set up after the CONSTEEL
secondary combustion chamber. The last feature is the use of automated control: the use of CONSTEEL smelting charging process
control, CONSTEEL preheating combustion process control and foam slag optimization process control.
The CONSTEEL process is suitable for the operation of the following types of charge:
---- Scrap: Without any pre-treatment, all grades of scrap listed in the American Scrap Iron and Steel Institute (ISISI) specifications for use in electric
furnaces can be used directly in CONSTEEL electric furnace production. Baled material, although not as effective as other types of scrap for preheating
, can be used as part of the charge if desired. Automotive slabs cut to ISISI specifications in certain proportions
, loose chips and drill cuttings properly mixed with other grades of EAF scrap are all good feedstocks for the Konstanti
EAF process.
---- Scrap and Pig Iron: Scrap and pig iron, where available, are popular scrap charge additions to improve steel purity
and when both are properly distributed in the charge, they help to maintain the right level of carbon in the charge.
---- Cold Direct Reduced Iron (DRI) and Hot Batch Iron (HBI): these materials are accepted as a source of pure iron for electric furnace smelting for rolling flat
steel and billets required for quality steel mini-mills. Hot massed iron can be loaded into a Comstock
unit along with scrap. Cold direct reduction iron is preferably loaded into a specific location in the preheater or directly into an electric furnace.
---- Hot Direct Reduced Iron: Hot Direct Reduced Iron is extremely beneficial for use in the Konstanti process, as the savings from the energy content
can make it more economically viable to build a Direct Reduction plant in areas where gas is costly. The Konstanti EAF process can use different ratios of direct reduced iron and scrap.
---- Iron, Corex and others from the blast furnace: Hot iron and preheated scrap at 30-50% of the charge
The use of the Künstler EAF has great advantages. In the Künstler process, the hot metal can be loaded into the furnace continuously and slowly, thus eliminating the need to pour the iron from the ladle into the open furnace, and thus avoiding the serious environmental pollution and violent reactions that are often associated with the charging of
iron in steel mills.
---- "Loose" automotive scrap: In the Constanti process of making steel from automotive scrap, this feedstock can make up to
25% of the metal charge, which solves the current problem of disposing of the non-metallic, non-recyclable portion of the automobile body, which is
huge
costly. Because of the large amount of energy present in the flue gas, the steel mill can supply hot water, steam or electricity at the same time.
Savings in production costs are a major advantage of the Consti EF
The savings in production costs resulting from the Consti EF smelting process are mainly due to the continuous charging and the stable smelting
state. These factors dictate that less total energy (electrical and chemical) is consumed in the smelting process and that the energy can be
better and more efficiently utilized. The costs and savings of this electric furnace production are divided into the following two parts: first, energy savings
and second, operational savings.
Energy savings
1. Electricity savings. In addition to the significant advantage of scrap preheating, this technology is unique in
other conditions that reduce energy loss. During normal production, there is no need to open the furnace lid so that the steel is not exposed to the outside air, thus eliminating radiation and spillage losses. In the Constanti method, the molten steel is always heated by the arc covered by the foam slag, which then melts the scrap, so that the arc energy is transmitted very efficiently, and the radiation losses to the refractory
material, roof, and water cooler are greatly reduced compared to a typical roof charging process.
2, power reduction. This process requires less power
from the grid than a conventional electric furnace of the same capacity. Several feasibility studies in the U.S. and Europe have shown that electricity costs can be reduced by at least 10% for this reason.
3. Less oxygen and no other fuel consumption. By a self-consuming oxygen lance or water-cooled oxygen lance blowing oxygen, using
35Nm 3 / t of oxygen can ensure that the smelting power consumption is less than 340kW h / t. The system does not need to be installed on the furnace
Burner, so there is no natural gas or other fuel consumption.
4. Less energy consumption for dust removal system. The process does not need to open the furnace cover for charging, so compared with the traditional
batch operation method, as long as the smaller capacity of the dust removal system, thus reducing the baghouse fan power requirements.
Operational savings
a. Less electrode consumption. The Constant Contact process reduces electrode consumption for the following reasons: virtually no electrode breakage
(due to flat bath operation); lower consumption due to reduced gasification atmosphere in the furnace; lower consumption due to a smoother electrical environment
without large fluctuations in current; no need to open the furnace lid for charging and thus exposing the electrodes to the ambient air; with this technology, the With this technology, the electrode consumption of AC furnace is about 1.5-1.6kg/t, while with DC furnace, the electrode consumption
is about 1kg/mt.
b. Scrap - high molten steel yield. The metal yield from scrap to molten steel will be increased by at least 1% to 2% due to the reduction of FeO content in the slag from
and the reduction of metal loss in the slag by using the Constanti EF process. In fact,
the bath is in a continuous state of refining, and due to the high density and continuity of the reactions within the molten steel and slag,
the FeO content is much lower and in balance with the carbon in the bath. In conventional EAF smelting, the furnace is in a flat bath refining stage only 10 to 15 minutes after power is applied to each furnace
.
c. Less dust pollution. Due to the low flow rate of the flue gas in the preheating section of a Constantan electric furnace, the dust in the flue gas is
deposited on the scrap and sent back into the furnace. At U.S. Steel, 11 kg/ton of dust
is generated as a result of this continuous feeding system. This compares with 16 kg/ton of dust generated in the past using the same furnace. The amount of dust can be reduced by
30%.
d, the number of working hours is less. Usually in the traditional steelmaking shop requires two large tonnage overhead cranes, one for basket
loading and one for ladle lifting. With the Künstler Furnace process, the baskets can be loaded using the same cranes used to lift the ladles. This is used once a week to once every two weeks for the first initial bath formation of a continuous production batch
. Then there is no need for a crane for tank loading.
After more than a decade of industrialized operation, the Comstock process has proven to be a reliable and economically viable
process. Melting shops using the process save on electricity and other consumption, labor expenses and dust handling
. Production levels continue to rise. Due to the reduction of noise and dust, especially the reasonable control of harmful fumes
The environment of the steelmaking workshop has been greatly improved.
With the successful acquisition of Intel Steel in 1995 by the Italian group DEXING, the Consti process has been gradually accepted by steel mills all over the world in the short period of 3-->
5 years, and its advantages have been gradually
emerged in the fierce competition of furnace types. In the United States, the first construction of the Konstanti system of the United States Steel Corporation (Ameris
teel) and Nucor Corporation (NucorSteel), because of the satisfaction of the Konstanti to bring the overall benefits of its decision to
expand the scale of production, and then build the steelmaking system, and coincidentally, once again chose the Konstanti system. The two companies
commenced production of their respective second Consti systems in 2000.