CZ278900B6 - Process of making technological iron - Google Patents

Abstract

A process of making technological iron with chemical composition in mass percentage: C - 2.00 to 4.3 %, Mn - 0.1 to 1.00 %, Si traces up to 5 %, P traces up to 0.020 %, S traces up to 0.015 %, Cu traces up to 0.15 %, Ni traces up to 10.0 %, Cr traces up to 5.0 %, Mo traces up to 1.0 %, V traces up to 0.1 %, Ti traces up to 0.1 %, Al traces up to 0.05 %, Pb. + Sb + As + Sn + Bi combined traces up to 0.02 %, the remainder iron and acceptable foreign matter. The technical iron is produced by smelting in a smelting aggregate and processed in a basin of steel waste, a carboniser, oxidation substances and flux material. A maximum of 50 % by weight of carbon is added to the smelt after dephosphorising and it is added to the smelt until the moment of the conclusion of discharge. The remaining iron is added to the smelt in the basin, in a powdered form in flowing inert gas.

Description

Technical field

The invention relates to a process for the production of high carbon feedstock with a low content of undesirable impurities and accompanying elements. This iron is intended as a basic corona load for the production of very pure steels and cast iron.

BACKGROUND OF THE INVENTION Separate technical waste

It is known that blast furnace pig iron, waste, pure ferro-alloys or high-carbon alloys are used as the basic metallurgical feedstock in the production of steels and cast iron. This technical iron is produced from steel sponge, iron ore or mixtures thereof.

steel iron. iron agglomerate by gas while blowing lime. After reduction of the melt in the steel furnace blown dust

It is known to produce technical iron carbon in a steel furnace by reducing the mixture of iron and pellets, reducing or melting the carbon.

high ore,

Furthermore, a process for producing high carbon technical iron in an induction or electric arc furnace by melting steel waste with a carburizing agent is known, wherein a further proportion of carbon is introduced into the furnace after the melting of the charge or added to the bottom of the ladle.

The disadvantage of the known methods so far is that they are technologically demanding. Carburizing in the furnace or adding to the ladle results in low utilization of the carburizing agent. The correction of the carbon content carried out by feeding the lump carburizer without sufficient melt mixing is not effective enough, because the local saturation of the melt around the carburizing particles causes a slowing down of the process, which must be completed before the carburant floods into the slag. This has a major impact on the usability of the carburizer and hence on the accuracy of the final carbon content. No additional correction can be made when dosing the carburizer to the bottom of the pan.

It is also known to melt steel scrap and iron sponge in a metallurgical aggregate by the action of an oxy-fuel burner, whereby the melt is continuously poured through a shaft in which the carburizing agent is placed in lump form.

The main disadvantage of the continuous carburization process is that it requires the interaction of both aggregates, and the degree of carburization, especially when lower carbon content is required, is difficult to control.

SUMMARY OF THE INVENTION

These deficiencies are solved by the method of production of technical iron with chemical composition in masses, percentages:

-1., Z ..

C from 2.00 to 4.3% Mn od 0,1 to 1.00% Si tracks to 5% P tracks to 0.020% with tracks to 0.015% Cu tracks to 0.15% Ni tracks to 10.0% Cr tracks to 5.0% Mo tracks to 1.0% IN tracks to 0.1% Ti tracks to 0.1% AI tracks to 0.05%, where the sum contents of Pb + Sb + As + Sn + Bi form

traces up to 0.02%, the remainder iron and permissible impurities, melting in the melting aggregate and processing in a ladle, from steel waste, carburizing agent, oxidizing agents and slag-forming additives.

It is an object of the invention that at most 50% of the carbon introduced into the melt after the phosphophosphation is complete is carried out until the tapping is complete and the remaining carbon is introduced into the melt in powder form in an inert gas stream.

An advantage of the process according to the invention is that in the furnace, the carbon is introduced into the melt only until it reaches a content which allows this operation to be carried out efficiently. Further carburization until the desired carbon content is achieved is carried out by blowing into the ladle. This process can accurately meter the amount of carbon. The utilization of this carbon is very high because small particles are introduced into the melt, which is in the form of high turbulence, and fully dissolves before they reach the melt surface. The use of simultaneously blown inert gas contributes to increasing the purity of the metal, reducing the hydrogen or nitrogen content. The advantage is also the possibility of subsequent processing of the melt. on off-furnace steel processing equipment.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

In the first example, industrial iron containing 3.78% carbon was produced. The melt was produced in a 70 ton electric arc furnace, the charge was composed of unalloyed steel waste, carburizing agent, lime and ore. After melting, the liquid bath contained 1.95% carbon, 0.022% phosphorus, and 0.018% sulfur. During the melting and oxidation periods, dephosphorus was carried out, after which the carbon content was 1.58%, the phosphorus content was 0.006%, and the sulfur content was 0.010%. After the final oxidation slag was removed from the bath, aluminum was added at a rate of 1 kg / t.

-2GB 278900 B6

At this stage, the melt carbon content was 1.58%. In order to reach a final content of 3.78%, an additional amount of carbon corresponding to an increase of 2.20% is required. This amount was taken on a 100% basis from which 27.3% of the carbon was introduced as a carbohydrate added from the beginning of the reduction period into the furnace and the ladle, i.e. until the tapping was complete. The remainder was dosed by blowing. At the end of tapping, the carbon content was 2.18%, phosphorus content 0.008% and sulfur content 0.007%. Calcined pitch coke was blown into the ladle in a stream of argon in powder form. CaSi was simultaneously dosed to further reduce the sulfur content. The finished melt contained 3.78% carbon, 0.008% phosphorus and 0.004% sulfur. The melt was cast into blocks of 0.5 to 3 tons, which were used as a charge in an electric arc furnace to produce high-grade steel for nuclear power components.

Example 2

According to a second example, the batch was treated as in Example 1. Prior to casting, the melt at the vacuum station was thermally and chemically homogenized, doped and degassed. The blocks were then cast and used as a charge in an induction furnace for the production of high-quality cast iron.

All the above percentages are by weight.

Claims (1)

PATENT CLAIMS Process for producing industrial iron having a chemical composition in mass, percent, from 2.00 to 4.3% carbon, from 0.1 to 1.00% manganese, traces up to 5% silicon, traces up to 0.020% phosphorus, traces up to 0.015% traces up to 0.15 copper, traces up to 10.0% nickel, traces up to 5.0% chromium, traces up to 1.0% molybdenum, traces up to 0.1% vanadium, traces up to 0.1% titanium, traces up to 0.05% aluminum and traces up to 0.02% of total lead, antimony, arsenic, tin and bismuth, iron and permissible residues, melting in melting aggregate and frying, steel waste, carburizing agent, oxidizing agents and slag-forming agents % of additives, characterized in that at most 50 wt. % of the carbon introduced into the melt after the phosphophosphation is complete is carried out until the tapping is complete and the remaining carbon is introduced into the melt in powder form in an inert gas stream.