SU711104A1 - Cast iron desulfurizer - Google Patents

Description

I

The invention relates to chemistry and metallurgy and can be used in the desulfurization of liquid cupola iron.

Known desulfurizer containing lime, fluorspar, as well as iron oxides and sawdust, which in the form of tablets injected into cast iron I.

The disadvantage of this desulfurizer is the need to manufacture tablets, as well as its high consumption in order to obtain a satisfactory degree of desulfurization, which increases the cost and increases the cost of iron.

The closest to the present invention is a cast iron desulfurizer containing components in the following ratio,

weight.o / o:

Lime40-80

Calcium

soda10-35

Fluorspar 25-35

This desulfurizer gives good results in the desulfurization of steel and blast iron having a high temperature (1500-1650 ° C) 12.

The disadvantage of this desulfurizer is the low degree of desulfurization of a metal having a low temperature (13001400 ° C), for example, cupola iron.

The purpose of the invention is to increase the degree of desulfurization of the cupola cast iron at. processing temperatures of 1300-1400 ° C.

To achieve this goal, these components are taken in the following ratio, wt. ° / o:

Lime 20-40

Calcium

soda 40-70

Fluorspar 10-20

Lime should be in the form of calcined powder fraction of 0.3-1 mm. containing up to 5% SiQ, At, SC and other impurities. The moisture content of lime should not exceed 3%. When lime is consumed below 1400 ° C, lime solid slags are formed, forming floorings on the lining of ladles and furnaces, which contain 10 cast iron, which is lost with slag. Moreover, the degree of desulfurization does not exceed U / o. Therefore, lime is used in conjunction with other materials, where it is stored with basic desulphate, which increases the basicity of the forming slag, which determines its sulphide capacity, which ensures the degree of desulfurization.

Soda ash should be in the form of a powder fraction 0.03-1 mm, containing up to 1 ° / about NaCI. Soda ash is an active desulphurizer in the area of cast iron treatment temperatures up to 1300 ° C. When temperatures above 1300 ° C are used, the soda will evaporate intensively, forming a liquid silky shlak, which erodes the lining of ladles and furnaces. The method of desulphurisation of cupola iron with soda (manually in a ladle) used in mechanical engineering provides a desulphurisation rate of no higher than 30% at high consumption of soda (30 kg / t and above) and is used for metal processing of critical castings.

Fluorine resin (Sap2), for example, grade F-92 according to GOST 7618-55, fraction 0.03-1 mm, containing up to 8% of impurities (Si4, 3%, CaCQ, 4, 3%, etc.), is used in metallurgy as a flux for reducing the viscosity of slags and in welding production. Supplied as a powder, grinding 30% of the residue 0.7 mm.

The preparation of the desulfurizer is carried out as follows.

These components are loaded into a hopper where they are mixed by blowing with

bottoms, creating a fluidized bed. In this state, the mixture is injected into the pneumatic pump from the hopper and transported through a flexible hose in a stream of gas carrier (dry air) to the tuyere immersed in a ladle or digger to a depth of 2/3 of the metal level. The pressure to blow at a depth of 1-1.2 m of the tuyere is PO-120 kn / m (1.1 -1.2 atm). The gas-powder mixture leaving the tuyere at a desulfurator concentration of 40 kg / m3 of gas carrier due to intensive mixing of the metal with air and carbon dioxide released during decomposition of soda is evenly distributed in the metal volume. This provides a large surface of the reacting phases and a high rate of desulfurization reactions. The purge time does not exceed 3 minutes.

Briquettes, granules, tablets can be made from this mixture of components. Briquettes are thrown into the bucket on the metal mirror at the beginning of the release. However, experiments have shown that their effectiveness is 2 times lower than when blowing a powder mixture (at equal costs).

Five mixture compositions were prepared and tested at a cast iron temperature of 1350 ° C. For comparison, the mixture was made according to a known composition. The compositions of the known and proposed mixtures are given in table. I. The test results are presented in table. 2

Table

Indicators Sulfur content before treatment, Bes.% 0.072 0.100 0.096 Sulfur content after treatment, O, 035 0.025 0.019% by weight Degree of desulfur51 75%,%

Table 2

Claims (2)

The composition of the desulphurizer is 0.101 0.129 0.140 O, 030 0.044 0.082 As can be seen from the table. The 2 limits of the desulfurizer are selected correctly. When this desulfurizer composition changes, the degree of desulfurization decreases. The optimum content of lime should be in the range of 20-40%. A decrease in optimal content; an lime lime leads; to a sharp decrease in the degree of desulfurization. An increase in the optimum lime content leads to a slight change in the degree of desulfurization and to the formation of walling and overgrowth of viscous viscous lime slag. The use of the specified iron desulfurizer provides a 70-80% degree of desulfurization at a mixture flow rate of up to 22 kg / t of iron. The disadvantage of desulfurato () is the reduction of the temperature of the pig iron being processed by 20-25 ° C. The decrease in sulfur content compensates for the reduction in the linear properties of molten iron caused by a decrease in temperature during its processing. The quality of cast iron castings increases, cast iron casting decreases on surface types of defects, shrink holes and porosity, hot cracks, the service life of castings is 25 --- 30 / o. At approximately equal cost, the described iron desulfurator is twice as efficient, which equals savings around I rub. on 1 t of cast iron. Claims of cast iron desulphurizer, including lime, soda ash and fluorspar, characterized in that, in order to increase the degree of desulfurization of cupola iron at a temperature of 1300-400 ° C, it contains components in the following ratio, wt.%: Lime 20-40 Calcium soda40 -70 Fluor spar 10-20 Sources of information taken into account during the examination 1. Japanese Patent No. 47-14622, cl. 10 J 154, 1972. 2. The patent of England No. 1288872, cl. From 7 D, 1972.