Top 10 continuous charging EAF features and advantages

Continuous charging EAF smelting process 10 characteristics

1. Scrap preheating: Before the scrap is fed into the furnace, the flue gas generated in the furnace is preheated in the preheating section of the feeding channel, with an average temperature of 600--650C;

2. Steel retention operation: There are at least 30 tons of molten steel in the electric furnace, and then continuous feeding, electrode transmission, carbon-oxygen lance operation, the electric furnace always works in a flat molten pool state, which can reduce arc fluctuations;

3. Continuous feeding: no need to frequently shut down the furnace and open the furnace cover to reduce heat loss;

4. The structure of the electric furnace body is reasonable: it is equipped with a TBT eccentric bottom tapping device, a tubular water-cooled furnace cover, and the furnace wall and furnace body are divided into upper and lower sections, which are easy to repair and maintain;

5. The furnace is equipped with an injection system: supersonic water-cooled oxygen lance, self-consumable carbon injection gun and carbon injection system;

6. Advanced conductive system: the transformer is the side outlet, using copper and steel composite electrode arms and electrode water-cooling spray system;

7. Simple operation technology: steel slag retention, foam slag submerged arc single molten pool smelting operation technology;

8. Set up a mechanized feeding system: the electric furnace is equipped with two sets of feeding systems. Among them, the bulk material feeding system is specially used for feeding the CONSTEEL system. The post-furnace ferroalloy feeding system is used for deoxidation and primary alloying in the post-tapping process of the electric furnace;

9. Advanced dust removal system: The electric furnace adopts CONSTEEL smoke extraction and dust removal as the main, and at the same time, the roof cover smoke extraction is supplemented by dust removal facilities;

10. In order to ensure that the flue gas of the electric furnace fully burns CO and eliminates harmful gases, set up after CONSTEEL secondary combustion chamber is installed.

The last feature is the use of automatic control: the use of CONSTEEL smelting and charging process control, CONSTEEL preheat combustion process control and foam slag optimization process control, etc.

Continous charging electric arc furnace applicable charges

1. Scrap: Without any pretreatment, various grades of scrap listed in the American Scrap Iron and Steel Institute (ISISI) specification for electric furnaces can be directly used in the production of continuous charging EAF. Although preheating is not as good as other types of scrap, bales can be used as part of the charge if desired. Car slabs cut in a certain proportion according to ISISI specifications, loose cuttings and iron cuttings that are properly mixed with other grades of scrap steel in the electric arc furnace are all good raw materials for the continuous charging EAF process.

2. Scrap and pig iron: Scrap and pig iron are popular scrap charge additions to improve steel purity. When both are properly distributed in the charge, it helps to maintain proper carbon levels in the charge.

3. Cold direct reduced iron (DRI) and hot briquetted iron (HBI): These materials are accepted as pure iron sources for electric furnace smelting for rolling flat and quality steel billets required by small steel mills. Hot briquettes can be loaded into CONSTEEL units together with scrap. The cold DRI is preferably loaded into the preheater in a specific location or directly into the electric furnace.

4. Hot-charged DRI: Hot DRI is extremely beneficial for use in the CONSTEEL process, and the savings brought about by the energy contained can increase the economic viability of building DRI plants in areas where gas costs are expensive. Different proportions of DRI and scrap can be used in the CONSTEEL electric furnace process.

5. Hot metal, Corex and others from blast furnace: 30%--50% of the charge of hot metal and preheated scrap are used in continuous charging EAF with great advantages. In the continuous charging EAF process, hot molten iron can be continuously and slowly charged into the electric furnace, so that the molten iron in the ladle can not be poured into the open electric furnace, thus avoiding the severe environment usually generated when the steel mills add molten iron. pollution, and violent reactions.

6. "Loose" automobile scrap steel: In the CONSTEEL process of making steel from automobile scrap steel, this raw material can account for up to 25% of the metal charge, which can solve the problem of the current non-metallic processing of automobile body, and the non-recyclable part costs a lot. The problem. Due to the large amount of energy present in the flue gas, the steel plant can simultaneously supply hot water, steam or electricity.

CONSTEEL electric arc furnace advantages

Saving production costs is a major advantage of continuous charging EAF. The production cost savings brought by the continuous charging EAF smelting process mainly comes from continuous charging and stable smelting state. These factors determine that less total energy (electrical and chemical) needs to be consumed in the smelting process, and can use energy better and more efficient. This kind of electric furnace production cost and saving is divided into the following two parts: one is energy saving; the other is operational saving.

1. Save energy

(1) Energy saving. In addition to the significant advantage of scrap preheating, this technology is unique in other conditions that reduce energy losses. During normal production, there is no need to open the furnace cover, so that the molten steel can not be exposed to the outside air, thereby eliminating radiation and spill losses. In the CONSTEEL method, the molten steel is always heated by the arc covered by the foamed slag, and the molten steel remelts the scrap, so that the energy transfer efficiency of the arc is very high, and the radiation loss to the refractory material, furnace roof, and water-cooled plate is different from the typical furnace roof. Compared with the charging process, it is greatly reduced.

(2) Power reduction. This process requires less power from the grid than conventional electric furnaces of the same production capacity. Several feasibility studies in the US and Europe suggest that electricity bills could be reduced by at least 10% for this reason.

(3) Less oxygen and no other fuel consumption. Oxygen is blown by a consumable oxygen lance or a water-cooled oxygen lance, and the smelting power consumption can be guaranteed to be lower than 340kW h/t by using 35Nm 3/t of oxygen. The system does not need to install burners on the electric furnace, so there is no consumption of natural gas or other fuels.

(4) Less energy consumption of dust removal system. Using this process does not require opening the furnace cover for charging, so compared with the traditional batch operation method, only a smaller capacity dust removal system is required, thereby reducing the power required by the baghouse fan.

2. Operational savings

(1) Less electrode consumption. The reasons for the reduction of electrode consumption by the CONSTEEL process are as follows: In fact, there is no electrode fracture (due to the operation of the flat molten pool); the consumption is reduced due to the reduction of the gasification atmosphere in the electric furnace; The consumption is reduced due to fluctuations; it is not necessary to open the furnace cover to charge the electrode to expose the electrode to the ambient air; using this technology, the electrode consumption of the AC electric furnace is about 1.5--1.6kg/t, using the DC electric furnace, the electrode consumption is about 1kg/t mt.

(2) Scrap steel - high yield of molten steel. The use of the continuous charging EAF process reduces the metal loss in slag removal due to the reduction of FeO content in the slag, and the metal yield from scrap to molten steel will be increased by at least 1% to 2%. In fact, the molten pool is continuously in the refining state, and due to the high density and continuity of the internal reactions of the molten steel and the slag, the FeO content is kept lower and in balance with the carbon in the molten pool. In the traditional electric furnace smelting, each furnace of steel is in the refining stage of the flat molten pool only 10 to 15 minutes after the electricity is charged.

(3) Less dust pollution. Due to the low flow rate of the flue gas in the preheating section of the continuous charging EAF, the dust in the flue gas will be deposited on the scrap steel and sent back to the electric furnace. At American Steel, 11 kg/t of dust was generated due to this continuous feeding system. In the past, the same furnace was used, and the dust generated was 16 kg/ton. The amount of dust can be reduced by 30%.

(4) The number of working hours is small. Usually two large-tonnage cranes are required in a traditional steelmaking workshop, one for basket loading and one for ladle lifting. With the continuous charging EAF process, the basket can be shipped by using a crane that lifts the ladle. Once a week to two weeks for the formation of the first initial melt pool for a continuous production batch. Then there is no need for a crane for tank loading. After more than ten years of industrial operation, the CONSTEEL process has proven to be a reliable and economically viable process. The smelting workshop using this process can save electricity and various consumption, labor costs and dust disposal. Production levels continue to rise. Due to the reduction of noise and smoke, especially the reasonable control of harmful smoke, the environment of the steelmaking workshop has been greatly improved.