SU819179A1 - Method of treatment of liquid cast iron - Google Patents

Description

additional mixing it with slag.

In the initial calciferous slag, the total content of iron and manganese oxides E (FeO + MnO) is 10-30%. Before the second batch of pig iron is drained (40-90%), the total content of iron and manganese oxides should be 2 (FeO + MnO) 5-15%. Obtaining a lower content of 2 (FeO-f + MpO) before draining a portion of cast iron is impractical due to the considerable lengthening of the treatment process and can be dried out more effectively with the subsequent casting of iron onto slag. The content of E (FeO + MnO) of more than 15% leads to emissions of metal and slag from the discharge of pig iron, a, and slag. The limits of the total; contains oxide; iron and manganese (Fs; p 4-Mn €) t) ei 5-157о were determined experimentally in the semi-industrial conditions of the NPO Tulachermet during the processing of cast iron with liquid converter and open-hearth slag.

Thus, when pouring the first batch of cast iron, it is necessary to remove AS (FeO-f + MnO) 5-25%. About 80% of the slag oxides are reduced by cast iron silicon and about 20% of the oxides are reduced by cast iron. Taking into account that cast iron contains on average 1% silicon and about 4% carbon, stoichiometric calculations of the reduction reactions of iron and manganese oxides from slag with carbon and silicon cast iron show that l decrease in DE (FeO + MnO) 5-25% with an average consumption slag 12.5% by weight of cast iron must be poured 10-60% of cast iron.

Example 1. In an electric furnace, 3 tons of cast iron were melted down, its composition,%: C-4.05; MP-0.10; Si-0.74; S-0.040; P-0.10.

After smelting CT.45, a slag of the following composition was obtained in a 10-ton open-hearth furnace,%: FeO-3.35; Fe203-2.57; aO-32.4; SiOa-22.8; MnO-6.5; E (FeO + f MnO) 13,32; 2 FeO FeO-f l, 35Fe2O3.

Cast iron in the amount of l; 400 kg at a temperature of 1400 ° C was released into a ladle equipped with gas-permeable porous blocks and an inert gas or air supply system. S ::; 400 kg of open-hearth slag was poured onto the surface of the cast iron from a steel-teeming ladle. Then melt was bubbled by blowing it with air with an intensity of 0.3. min for 5 min

Upon reaching E (FeO-f MpO) 5-8%, the content of which was estimated visually by comparing with the reference slag samples, additional smelting of the iron in an amount of 2600 kg was carried out from the electric furnace for 10 minutes. To more quickly carry out reactions of the reduction of iron and manganese oxides, and

also, for a deeper degree of desulfurization of cast iron, 3-4 minutes before the end of the treatment process, a deoxidizing desulphurization mixture consisting of lime, fluorspar and aluminum, taken in the ratio 6: 3: 1, was seated. The amount of the mixture dropped to 5% of the weight of the slag, i.e. 20 kg. At the end of the treatment, pig iron of the following composition was obtained,%: C-3.62; Mp-0,69; Si-0.32; S-0.008; P-0.14.

Slag after cast iron treatment had the following chemical composition,%: FeO-1.93; FegOs-1.43; CaO-32.0; SiOa-25,6; MnO- 1.20; E (FeO + MnO) 5.06.

Thus, DE (FeO + MnO), 26.

The degree of desulfurization was 80%.

The degree of re-phosphorization is significantly lower than in the above prototype, and was 40%.

The degree of reduction of iron and manganese was 50 and 81.5%, respectively.

Example 2. In the cupola melted 8 tons of pig iron of the following composition,%: C-4.00; Mp-0.68; S-0.082; P-0.14; Si-1.20.

In the 10-ton converter after smelting CT.20, slag of the following composition was obtained,%: FeO-15.42; FeaOg-6.52; CaO-38,19; SiOg-12.60; MnO-5.60; E (FeO + MnO) 29.82.

Cast iron in the amount of l; 5000 kg at a temperature of 1430 ° С were released in a furnace and on the surface of cast iron kg of slag was poured. The remaining operations were similar to the first experiment.

At the end of the treatment, pig iron of the following composition was obtained,%: С-3.75; Mp-0.80; S-0.050; P-0.14; Si-0.64. The chemical composition of the slag after treatment,%: FeO-9.93; Fe203-0.86; CaO- 35.20; SiOj-16.40; MnO-3.96; E (FeO-f + MnO) 15.05; D2 (FeO + MnO) 14.77.

The degree of desulfurization was 40%, refosporatsi is absent. The degree of reduction of iron and manganese was 54 and 31%, respectively.

Similarly, the processing of iron in an electric furnace can be carried out. The method of processing liquid iron provides a high degree of reduction of metal oxides from spent lime-ferrous slags, a high degree of desulfurization of cast iron with a slight degree of refhosphorization, significantly reduces energy costs, significantly increases the productivity of steelmaking units when using refined iron.

ich

Claims (2)

Invention Formula The method of processing liquid iron, which includes pouring it into a lined container, pouring on the surface of iron casting lime-ferrous slag in 5 amounts of 10-15% by weight of iron and mixing them, characterized in that, in order to increase the efficiency and efficiency of the process, 10-60% of cast iron is poured and mixed 5 with slag to obtain a total content of iron oxides and manganese in the slag 5-15%, after which 6 remaining cast iron is poured and additional mixing is carried out with the slag. Sources of information are accepted e into account in the examination of 1- USSR Copyright Certificate № 502040, cl. C 21C 5/54, 1974. 2. Japan patent No. 51-48480, cl. 15A-95, 1976.