RU2071977C1 - Plant for continuously melting steel - Google Patents

Abstract

FIELD: metallurgy, namely, pig iron and converter production. SUBSTANCE: plant includes intermediate reservoir fluid-tightly mounted on mouth of reaction chamber and connected with iron receiver by means of barometric solution. Interchangeable refractory partitions are mounted on draining ducts of metal collector. Intermediate reservoir has through port passing along center of hearth and framed by annular refractory stream-generating baffle. EFFECT: improved design. 2 dwg

Description

 The proposal relates to the metallurgical industry and can be implemented at enterprises with a blast furnace and converter production.

 The intensification of converter steelmaking processes primarily depends on the impact of the components of liquid and gaseous media (phases) in contact with each other.

The oxygen-converter steel production process, firmly established in the industry, has improved a number of necessary conditions for the intensification of the process. However, the specific area of heat and mass transfer processes increased very slightly. In the known constructions of the converters, the specific area is only 0.11-0.182 m ² / t and practically these are the limits of the possible, because an increase in pressure in the oxygen stream causes emissions of metal and slag beyond the limits of the converter capacity. Thus, a substantial reserve of increasing the productivity of oxygen-converter plants is exhausted, in addition, CO in exhaust gases is growing inexorably and has become a significant threat to the environment.

 The expansion of the specific area of heat and mass transfer processes, which is the ratio of the surface area of the liquid phase with a gas oxidizing medium, to the mass of metal in the converter bath, sets this proposal as its task.

 It is known that the highly developed surface of the molten iron with an oxidizing phase provides almost instant removal of impurities and their slagging in the presence of fluxes. It was found that steelmaking processes are regulated not only by the rate of chemical reactions, because at high temperatures, they proceed almost instantly, and the rate of diffusion and delivery of reacting components to the reaction site. With a highly developed surface of the molten iron, which is in contact with the oxidizing phase, all chemical processes proceed quickly, and under certain conditions they can proceed continuously. For example, in continuous installations.

 A known option is a continuous steelmaking process. A one-stage installation consists of a receiver in which liquid iron is continuously supplied from a ladle, tilting according to a certain program with a tilter, and a reactor in which iron is blown with oxygen carrying pulverized lime, or lime and ore, through a water-cooled lance. The metal-slag emulsion foamed by intensively formed carbon monoxide bubbles in the metal flows through the connecting channel into the sump.

 In the sump, the processes of metal refining from carbon, manganese, phosphorus, and sedimentation from slag are completed. Silicon oxidizes completely in the reactor. Deoxidizing agents and alloying additives are added to the drain receiver, which makes it possible to change steel grades (see Yavoisky et al. Metallurgy of Steel, Moscow, Metallurgy, 1973, p. 344, Fig. 161).

 However, a one-stage installation provides a relatively low oxidation of the metal in the sump and in the connecting channel, due to the low specific area of interaction between liquid and gaseous media, which naturally affects the performance of the installation and the quality of the steel produced.

 A known installation of continuous action for steel, which can be adopted as a prototype.

 Liquid iron from a blast furnace in a uniform stream enters the reaction chamber mounted on the tank metal collector. Through eight inclined nozzles of the ring device, oxygen is supplied under high pressure, the jets of which break the stream of cast iron into small droplets. The resulting slag-metal emulsion accumulates in the metal collector, from which the slag is drained through a side outlet, and the finished steel continuously flows through the hole of the glass integrated in the bottom of the metal collector, and is drained into the steel pouring ladle (see Yavoisky et al. Metallurgy of Steel, Moscow, Metallurgy, p. 343, p. 160, 1973).

 The huge contact surface of drops of molten iron with oxygen and fluxes provides almost instant removal of impurities from cast iron and the slagging of the resulting oxides.

The disadvantages of cast iron blasting is the low yield of liquid steel
80% due to the large number of metal kings in the drained slag of the lateral branch. The degree of heat absorption is also insignificant, and due to the high oxygen pressure at the nozzles and forced lateral removal, the presence of CO in the exhaust gases reaches more than 40%, which causes an urgent need to burn it in special waste heat boilers.

 However, in continuous processes of jet processing of molten iron, the supply of reagents and the removal of by-products of the reactions is carried out continuously and uniformly. Continuously means more. Evenly means better. It is better to manage and control the processes in the smelting of various grades of steel, with high productivity of the installation as a whole; relatively low rates of loading of raw materials and continuous production of finished steel.

 The aim of this proposal is to increase the yield of liquid steel per calendar time unit and to expand the technological capabilities of the steelmaking unit, with a continuous process of steel production.

 This goal is achieved by the fact that a continuous steelmaking unit, including an intermediate metal-intensive reaction chamber, a metal collector, a gas outlet, a gas-oxygen lance, and filling apparatuses for supplying slag-forming coolers, deoxidizers and alloying additives, according to the proposal, an intermediate metal consumption is installed on the neck of the reaction chamber. In the center of the hearth of the intermediate metal, depending on the shape of the neck of the reaction chamber, a through hole is made, which is framed by an annular refractory jet-forming threshold. A metal receiver is integrated in the side wall of the intermediate metal intensity, which is activated through a ferrobarometric shutter. The reaction chamber and gas outlet are installed on the metal collector at a certain distance from each other, which ensures the flow of oxidizing and exhaust gases through a free opening above the bath of the metal collector. The metal collector is equipped with steel and slag drains, and fireproof partitions are interchangeable in size of their height on the drain channels of these grooves. By changing the height of the partitions, you can adjust the ratio of the thicknesses of the layers of metal and slag in the bath of the metal collector. The shape of the metal collector, which is made of a teapot type, also contributes to this. The design of the unit allows you to have a wide opportunity to install filling devices where they are necessary for technological reasons. A gas-oxygen tuyere moving deep into the reaction chamber provides a wide opportunity to control and control the oxidation processes of the raw materials entering the reaction chamber, taking into account the state of the thermal zones of the reactor and the chemical composition of the raw materials.

 The essence of the proposal is illustrated by drawings, where in FIG. 1 shows a steelmaking unit in longitudinal section; in FIG. 2, section AA in FIG. one.

 The steelmaking unit consists of a reaction chamber 1, an intermediate metal 2, in the bottom of which there is a through opening framed by an annular refractory jet-forming threshold 3, and a metal receiver 4 of the vessel is activated through a ferrosborometric shutter 5. The reaction chamber 1 and gas outlet 6 are mounted on a metal collector 7, which is made of a teapot type 8, and on its steel and slag troughs 9 interchangeable refractory partitions 10 are installed. Gas-oxygen tuyere 11 and a series of backfilled apparatuses 12, complement the technical biological units of the unit.

 The unit operates as follows.

 A reaction chamber 1 and a gas outlet 6 are installed and secured to the metal collector lined with refractory 7 and an intermediate metal 2 is installed and secured to the neck of the reaction chamber 1 and a gas-oxygen lance 11 is inserted into its arch 11. Refractory partitions 10 are installed and secured to the drain gutters 9 of the metal collector 7 and height dimensions partitions 10, in steel and slag troughs 9, are determined in advance for technological reasons, which of the grades they intend to receive, the chemical composition of the molten iron, chemical I will leave the availability of raw materials for the charge, and, most importantly, in what quantity and quality the output of slag is forecasted per ton of finished product output. The filling devices are put into a pre-start state and the operation of the metering elements is checked.

 Through special false windows made at the necessary points of the lined parts of the unit, with the help of gas-air burners, the refractory masonry is dried and heated to temperatures that exclude the formation of pressure when the first portions of cast iron melt arrive.

 The molten iron can be supplied from an iron ladle, mixer, or directly from a blast furnace to an intermediate metal 2. When installing a ferrobarometric shutter 5 in a metal receiver 4, oxidizing gas is fed into the reaction chamber 1. While the intermediate tank 2 is filling, the entire opening of the reaction chamber 1 manages to fill with oxidizing gas. After the intermediate vessel is filled with melt above the upper edge of the annular refractory threshold, the melt begins to pour over a wide front into the reaction chamber filled with oxidizing gas.

 Overflow of the melt through threshold 3 is carried out in the form of thin film jets and small droplets dispersed around the entire perimeter of the aperture in the metal consumption, which form a huge specific contact surface of the cast iron melt with oxidizing gas.

 As is known, under such favorable conditions for heat and mass transfer processes, chemically hot cast iron melt gives more than half of all heat generated, which mainly accounts for carbon oxidation. The arrival of such an abundance of heat into the reaction chamber 1 takes place in a short time, during which thin film jets and small drops of melt move along the path to the bath of the metal collector 7, where they are abundantly washed with fresh oxidizing gas. This heat is enough for the initial heating of the melt, necessary to activate the refining processes.

 The slag composition is determined by the corresponding dynamics of the oxidation of associated impurities, due to favorable conditions, these processes are accompanied by the formation of a balanced slag-metal emulsion, which is a favorable environment for the development of further processes.

 Further filling of the sump 7 with the actively formed slag-metal emulsion continues to be accompanied by oxidation reactions of the remaining part of the impurities. The early formation of active slag contributes to the concomitant high oxide content.

 In the course of continuing the oxidation of impurities, the temperature of the melt in the bath of the metal collector rises. 7. The resulting slag overheats and the fluxes dissolve. The fluidity of the slag and the entire melt rises. The final chemical reactions, mainly in the middle part of the bath in the collector 7, proceed at a rate ahead of the filling of the collector. At the same time, in the lower part of the metal collector there is an active separation of slag-metal emulsion into metal and slag. When the metal collector 7 is completely filled with the melt, the process goes into an operating mode of continuous steelmaking.

 This means that the upper level of slag in the metal collector 7 has reached its limit and merges through the refractory partition of the trough 9. At the same time, the lower level of slag is slightly lower than the upper edge of the partition 10 located in the steel-drain trough 9. However, under the prevailing pressure of the slag column in the metal collector 7, the metal is squeezed into the teapot compartment of the bathtub 8, forcing it to pour over the partition 10 installed in the steel-drain trough 9, and further into the steel-pouring ladle. At the same time, all the necessary raw materials and oxidizing gas are continuously and in the required amount into the reaction chamber 1.

 One of the main advantages of the proposed process is the predetermined presence of a sufficient amount of active slag in the metal collector. This is due to the ability to regulate: the ratio of the layers of metal and slag in the bath of the collector 7, the supply of oxidizing gas and the whole complex of raw materials and to control the initial product steel, slag and gas.

 The following can be used as coolers: iron ore, sinter, ore pellets, as well as rolled and other scale, small steel and cast iron shavings, which are used for overstocking in several regions of our country, as Processing such a return in converters gives a very significant waste. The main advantage of these materials compared to large scrap metal is their low cost and the ability to feed them into the installation continuously and evenly. Ore materials, moreover, can reduce oxygen consumption and improve slag formation due to the fact that iron oxides significantly accelerate the dissolution of fluxes.

 The supply of bulk coolers and slag-forming fine fractions is justified by the fact that the gas flow from the reaction zone and metallovanny, taking into account the continuity of the process, is determined to be uniform and relatively calm, and its path to the gas outlet is through the opening in the metal collector, reducing the power of the exhaust gas flow due to the stability and continuity of the process eliminates the removal of small particles of metal and slag from the installation, which provides a significant metal burn from coolers.

Based on the foregoing, the proposed option for continuous steelmaking is a high-performance process that incorporates all the highly efficient technological methods of steelmaking of various grades and meets the obvious:
continuously means more
evenly means better.

 It is better to manage and control literally all the processes of steelmaking during the continuous supply of raw materials to the reaction chamber of the unit.

Claims (1)

 A continuous steelmaking unit comprising a metal receiver, a reaction chamber, a metal collector equipped with steel and slag channels, a gas outlet, a gas-oxygen form, charging devices, characterized in that it is equipped with an intermediate tank sealed on the neck of the reaction chamber and connected to the metal receiver by means of a barometric shutter and interchangeable refractory baffles installed on the drain channels of the metal collector, while the intermediate tank is made and with a through opening in the center of the hearth framed circular refractory strueobrazuyuschim threshold.

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