SU956568A1 - Method for preparing magnesium or magnesium alloy chip - Google Patents

Description

The invention relates to ferrous metallurgy, in particular to secondary furnace desulfurization of iron with magnesium.

The use of shavings of magnesium or magnesium alloys for entry into molten iron without special preparation of them is not possible.

The preparation of magnesium and magnesium alloy chips is the formation of cylindrical briquettes by pressing chips on conventional hydraulic presses 1.

The disadvantages of this method of preparing chips are the low use of magnesium for desulfurization, the significant pyro effects and metal emissions that are observed during the processing of cast iron with briquettes.

A known method of preparing magnesium chips for the desulfurization of cast iron is concluded in the fact that during the briquetting of magnesium chips the binding material is added, in particular up to 5% of resin G2.

. This method makes it possible to significantly reduce the degree of destruction of briquettes made of magnesium shavings only during their transportation and storage.

The process of treating molten iron with such briquettes is unstable with metal emissions and a pyro effect and with a low degree of use of magnesium for desulfurization. At the temperature of the molten iron (1300-1450 ° C), the binder (resin) present in the briquette melts and burns out during the first 10-15% of the reaction time of the briquette and loses its binding properties, after which the briquette is destroyed and the magnesium interaction with liquid. Chugunom acquires an explosive character.

15

The purpose of the invention is to improve the degree of use of magnesium, to eliminate the pyroelectric effect and metal emissions in the process of cast iron with briquetted magnesium chips or magnesium alloys.

This goal is achieved by the fact that according to the method of preparing chips of magnesium or magnesium alloys for entry into the liquid iron,

25 in briquetting, the surface of the briquette is melted to form a shell of 0.01-0.10 of the mass of the briquette.

Claims (2)

The melting of the surface of the briquettes is carried out by immersing them in 30 molten L salts of alkali and alkali earth metals, heated to 700 eso c. The forging of the molten shell of 0.01-0.10 mass of the briquette provides the necessary mechanical STRENGTH of all standard sizes of briquettes used in practice and prevents their destruction both during transportation and storage, and during the whole process of liquid iron processing. The optimal size of the shell is established in each particular case empirically, depending on the geometric dimensions of the briquette. The foil / shell of less than 0.01 mass of the briquette will not provide the necessary mechanical strength and may lead to premature destruction of the briquette during transportation or during the processing of the liquid metal. An increase in the shell of more than 0.10 mass of the briquette is impractical because it does not give a positive effect. This increases energy costs and decreases labor productivity. Melting the surface of the briquette in molten salts of alkali and alkaline earth metals eliminates magnesium loss (these salts are inert with respect to magnesium and protect the briquette from atmospheric interaction with oxygen) and simplifies the design of the device for this method. The established heating interval of the salts (700–850 ° C) ensures the production of monolithic molten surfaces of briquettes weighing from 8 to 24 kg that can be used on actual installations for the desulfurization of cast iron without changing the existing technology and modes of magnesium input. When the briquette is less melted (about 8 kg), the heating temperature of the salts is set closer to the lower limit, and with a larger mass, the briquette is closer to the upper one. Heating the salts below leads to freezing of the salts on the surface of the briquette and to the lengthening of the process of melting the briquette. Heating salts above 850 ° C is impractical because it does not give an additional positive effect and leads to additional energy costs, i Example. Magnesium briquettes of circular cylinders with a mass of 4.6 kg are immersed by means of a special device in a bath with a melt of foam w of the alkali and alkaline earth metal (carnalite) having a temperature of 750 ° C. After 60 s, the briquettes are removed and placed in a chamber with a neutral atmosphere (nitrogen) for cooling. The briquettes prepared in this way have a smooth melted surface without visible inclusions of unmolded chips. Veicina melted shell 0,028 mass of the briquette. During transportation, reloading and storage of melted briquettes, their destruction is not observed. The treatment of cast iron with fused briquettes of magnesium shavings of ocyujecTB is carried out at the advanced desulphurization unit in 100 tons of cast iron-carrying ladles in accordance with the usual technology used in the processing of nugune with ingot magnesium. Briquettes weighing 16 kg are introduced into liquid cast iron by means of a submersible device of the bell type to a depth of 1.5 m. The process of processing cast iron proceeds smoothly, without metal emissions and the pyro effect. The sulfur content in the pig iron before treatment is 0.042%, after treatment - 0.018%. The degree of use of magnesium for desulfurization is 68.5%. When the cast iron is processed with unmolded magnesium chips, under similar conditions, the degree of use of magnesium does not exceed 45.2%, and the process proceeds rapidly, accompanied by a pyro effect, and emissions of liquid iron from the ladle are observed. When using the proposed method, the destruction of briquettes during the processing of cast iron is completely eliminated, as a result of which the process proceeds exactly without metal emissions and pyroeffect, and the degree of use of magnesium increases by 20–25 abs.%; Molten briquettes can be introduced into liquid iron by known devices in existing cast iron desulfurization plants, which is solved by the complete disposal of waste by an enterprise for the processing of magnesium magnesium chips, which does not find effective use in the national economy, the costs of cast iron desulphurization are reduced; conditions for transporting and storing the briquettes are facilitated and safe working conditions are ensured. The economic effect of using the method of preparing magnesium chips for desulfurization of cast iron is 0.202 p / t of pig iron. The formula of the invention 1. A method of preparing magnesium chips or magnesium alloys for entry into liquid iron, which consists in briquetting it, is also distinguished by the fact that, in order to increase the use of magnesium, eliminate the pyroelectric effect and metal emissions during processing, after briquetting the surface the cake is melted to form a shell. 5956568 0.01-0.10 the mass of a briquette; Sources of information, taken into account in the examination 2. The method of pop. 1, distinguished by the fact that reflow over-1. Krasavtsev N.I. et al. The introduction of briquettes is done by immersing them on the desulfurization of cast iron. Kiev, Nauv molten alkali salts and shchekona dumpka, 1975, p. 46. earth metal, heated2. Patent of Poland W 190798, up to 700-8500Сl. From 21 to 1/02, published. 1979