SU1090725A1 - Method for preventing splashes in steel making in oxygen converter - Google Patents

Abstract

A METHOD FOR PREVENTING THE REMOVAL OF RELAYS IN THE PRODUCTION OF STEEL IN OXYGEN KQHBEPTEPE, including the deposition of a foamed gas-slag metal emulsion with a jet of gas, which is due to the fact that, in order to prevent emissions without changing the pattern of oxygen, it will be on the surface of the system. the layer of the steel outlet with a mixture of inert gas with fuel and air in a ratio of 4.5: 1: 7 while simultaneously blowing the melt with an oxidizing gas, the mixture consumption rate being 10-15% of the flow rate of gas.

Description

The invention relates to ferrous metallurgy, in particular to the production of steel, and can be used to control the purge flow in an oxygen converter to prevent emissions and overflows of the surrounding gas-slag metal emulsion. In the processes of steel production in metallurgical aggregates, the oxidation reactions of impurities dissolved in a molten iron bath — primarily silicon manganese, carbon, phosphorus, and sulfur — are most important. The refining of the metal from these elements is provided by oxygen entering the bath from the azole phase. Purification of the metal from sulfur and phosphorus is carried out by transferring them from metal to slag, which must be of appropriate chemical composition and physically} {properties. To induce active, highly basic slag, the oxygen lance is in a high position at the beginning of the purge. After slag induction, the tuyere is transferred to the working position, and the slag metal is formed, and the emulsion is foamed as a result of the reaction in it to prevent the metal droplets from getting into the slag from the interaction zone of the oxygen jet with the metal. As the slag-metal emulsion is foamed, its upper layer may reach the level of the steel outlet orifice and exceed it, which corresponds to the pre-surge situation. The known method of deposition of foamed slag in the process of purging in an oxygen converter by introducing into the bath special fluxes containing 20–50% of organic components and 30–70% of refractory material mixed with a binder added in an amount of 10% Ij. The disadvantage of this method is the need to prepare the fluxes, the rate of their precipitating effect on the slag is low, and the content of ferrous oxide in the slag is reduced due to its consumption for the combustion reaction of organic materials. There is also known a method of preventing emulsion emission from the converter, which consists in replacing part of the oxygen (5-30%) going to purge with argon 2. The disadvantages of this method are an increase in the duration of melting due to a decrease in the amount of injected oxygen and a decrease in slag oxidation, which is especially undesirable with phosphoric redistribution of cast iron. The closest in technical essence and the achieved effect to the invention is a method of preventing emissions from steel production in an oxygen converter, including precipitation of a foamed gas and slag metal emulsion with gas streams. When over-slag foaming the lance is briefly elevated above the level of the foamed bath and oxygen is precipitated by foam jets t3. The main disadvantage of the known method is a sharp slowdown in the process of oxygen supply to the metal volume, associated with raising the mold above the level of the foamed bath. In this connection, the decarburization reaction rate and bath temperature are reduced, which leads to an increase in the duration of the purge. In addition, the entry of metal droplets into the slag prevents the mass transfer processes in the emulsion, in particular the oxidation of phosphorus, to be slowed down. In addition, a disadvantage of the known method is the possible pereokislenie slag, because the deposition of foam occurs using oxygen jets, with the result that after transferring the tuyere to the working position and falling of the beads into the slag, the latter may foam excessively, resulting in emissions. The known method can be applied practically only at the end of the oxygen purging of the bath before the converter is poured. For a more complete reaction between the metal and the bag, as well as to reduce the metal loss iC and to remove the tuyere, it is advisable to blow to the verge of approaching the formed slag-metal emulsion to the throat of the converter without preventing its emissions and overflows. The aim of the invention is to prevent emissions without changing the mode of purging with oxygen. This goal is achieved by the fact that according to the method of preventing emissions from steel production in an oxygen converter, which includes precipitation of a foamed gas-metal emulsion with gas, the precipitation of the emulsion is carried out at the moment of passing through its upper layer of the discharge layer. openings with a mixture of inert gas with fuel and air in a ratio of 4.5: 1: 7 while simultaneously sweeping the melt with an oxidizing gas, the mixture consumption rate being 10-15% of the oxidizing gas consumption. The essence of the invention is as follows. The process of destruction of foamed gas-slag-metal emulsion starts from the upper layers, therefore, a superficial effect of the inert gas jets with fuel and air is sufficient.

The use of an inert gas in the mixture is necessary for the mechanical destruction of the foamed bath while exceeding its level in the steel outlet. In order to compensate for the heat carried away with the waste inert gas, it is proposed to supply fuel, and for its combustion, respectively, air. In calculating the amount of fuel, heat loss carried with inert gas was taken into account, as well as heat consumption to heat the foam, and loss of heat carried with combustion products and air nitrogen was estimated. The flow rate of the mixture fed to the precipitated pepper should be 10-15 % of the amount of oxidizing gas entering the bath per unit of time, which corresponds to the surface introduction of the mixture jets into the foamed gas-slag metal emulsion.

When the mixture consumption is less than 10%, a slight penetration of the mixture jets into the foamed gas-slag-metal emulsion is observed, the foam is stroked, and the expected effect is not observed. Increasing the mixture flow above 15% is impractical because the volume of exhaust gases greatly increases and the gas cleaning system is obstructed. The ratio of inert gas, top gas and air should be 4.5: 1: 7, as noted above, which allows not only to compensate for the heat carried away with the waste inert gas, but also to heat the foam, because heating contributes to foam.

The amount of fuel supplied (4.5: 1) is selected on the basis of the conditions for the compensation of heat carried with an inert gas, according to the expression

 CpV () - V5 (lco, Vcoi + iHiQVK ,.),

where C is the heat capacity of the inert gas,

cap / g hail; p is the inert gas density,

T. - waste gas temperature,

 to;-

T „- the temperature of the feed gas. TO; V - consumption of inert ra3a, MVc; Vj - fuel consumption, MVc; v, n are the enthalpies of the components of the top SOPs. Ti

Liva, cal / m;

iu о - composition of combustion products, m3 / m,

as well as the heat consumption for heating the foam and the loss of heat carried away with the combustion products and air nitrogen. These losses are difficult to determine by calculation, so j

a series of experiments and selected the optimal ratio of components in the mixture with regard to the calculated recommendations and laboratory conditions.

In this case, the air consumption is chosen equal to the quantity necessary for burning the supplied fuel (Vj) with an excess factor of 5L to 1.05.

A mixture of inert fuel and air is supplied at the time when the steel outlet hole is in excess of the foamed gas-slag-metal-metal emulsion. The supply of the precipitating mixture takes place through the second nozzle of the oxygen tuyere, while oxygen is supplied continuously throughout the entire nozzle through the bottom of the no. The distance between the nozzle cusses is selected so that the top nozzle cusp is located at the neck slice.

The limitation of the maximum height of the gas-slag-metal emulsion layer to the level of the steel outlet is caused by the fact that the free volume of the converter (transition to the conical part), which can accommodate new emulsion volumes, is sharply reduced above its level.

Purging with a mixture of inert gas with fuel and air continues until the emulsion level drops below the steel outlet, which can be fixed with a special sensor indirect; Slag formation roll. -.

Example. In the laboratory oxygen converter with a capacity of 60 kg, piled up preheated scrap in the amount of 10 kg was poured, cast iron (50 kg) containing%: C 4,1,: M 0.71, -Si 0.50, P 0.15, S was poured 0.30 at 1400 ° C, and were purging with oxygen, sitting down in the course of purging. Purging was carried out through a two-tiered four-nozzle lance with Laval nozzles (nozzle diameter 1.0 mm), the second nozzle was located at a distance of 540 mm from the first, the oxygen supply intensity was 0.2 (3.3 min), and oxygen It was supplied only through the lower rus nozzles. Snaсs la Furma was at a height of 45 calibers from the level of a quiet metal, after aiming the active liquid-mobile donkey (after 2.5 min) the tuyere was transferred to the working position (32 calibres). On the seventh minute of the blowdown, the indirect slagging device showed that the level of foamed gas-slag metal emulsion exceeded the level of the steel-outlet hole immediately started supplying natural gas through the second stage, snuffled an oxygen tuyere mixture of argon with gas and air: 0.008 m / min of natural gas - 0.0013, WHO

Claims (1)

METHOD FOR PREVENTION OF SELECTION OF OWLS IN THE PRODUCTION OF STEEL IN OXYGEN CONVERTER, including the deposition of foamed gas ^- slag-metal emulsion with gas jets ^- , σ t L which means that, in order to prevent emissions without changing the oxygen purge, the emulsion is deposited at the level steel outlet with a mixture of inert gas with fuel and air in a ratio of 4.5: 1: 7 while blowing the melt with oxidizing gas, and the flow rate of the mixture is 10-15% of the consumption of oxide itelnogo gas. S