SU1097681A1 - Method for smelting steel in open-hearth furnaces - Google Patents

Abstract

METHOD OF STEEL MELTING IN THE MARTENOVO OVEN, including filling of solid metal charge and batch injecting lime into the furnace, characterized in that, in order to increase furnace productivity and yield of suitable metal, 60-80% limestone and 40-70% are produced outside the furnace solid metal from the total consumption of smelting and sequentially pouring into the kiln a previously prepared mixture and the rest of the solid metal charge, and filling the rest of the limestone begins after the formation of slag cover over the entire surface baths and finish by the time of complete melting of the mixture.

Description

The invention relates to ferrous metallurgy, in particular to methods for smelting steel in main open-hearth furnaces. The technological mode of the period for the charge rolls largely determines the course of the processes of smelting the mixture and slag formation, and therefore significantly affects the duration of the smelting and productivity of the open-hearth furnace. There is a known method of steel smelting in the main open-hearth furnace, including heating and mixing bulk materials, for example, limestone, during the heating of each layer, and bulk materials are pushed to the back wall of the furnace and mixed with a mold or a special stroke by the translational and rotational movement of the charging base. Machines With 1J Such a mode of limestone filling is not sufficiently effective, since it does not provide the possibility of even distribution of limestone into the volume of the steelmaking bath. In addition, mixing lime with a filling machine increases the duration of the filling and loss period. rate of radiation through the open charging windows. The closest to the technical essence and the achieved effect to the proposed method is the method of extracting steel in an open-hearth furnace, including the filling of solid metal charge and batch injection of limestone. However, the filling of limestone into the furnace in small increments increases the duration of the period of filling and heat loss by radiation through open windows; the resistance of the charge to the equipment is reduced; additional limestone firing installations are required; The intensity of mixing of the melting bath during the period of melting of the mixture with carbon dioxide decreases, which increases the duration of this period. An increase in the duration of the filling and melting leads to a decrease in the productivity of the furnace and the yield of suitable metal. The aim of the invention is to increase the productivity of the furnace and the yield of metal. The goal is achieved by the fact that according to the method of steel smelting in an open-hearth furnace, including the filling of solid metal charge and batch injection of limestone into the furnace, 60-80% of limestone and 40-70% of solid metal charge from their total consumption are made layered outside the furnace smelting and sequentially filling up, with the furnace the previously prepared mixture and the rest of the solid metal charge, and the filling of the rest of the limestone is started after the formation of the slag cover over the entire surface of the bath and is completed by the time of complete melt charge. Pre-layered loading of limestone and metal charge into the molds leads to a uniform dispersed distribution of limestone in the volume of the steelmaking bath. The amount of metal charge loaded into the molds together with limestone is 40-70% of the total consumption of scrap metal. The filling of limestone with a large 70% of the total consumption of the amount of metal charge leads to a high degree of lime dispersion. However, such a high filling of lime leads to significant losses of free calcium oxide with a descent slag of the melting period and makes it difficult to form the required slag by the time the mixture is melted basicity. The result is an increase in melt finishing time and {Reducing the durability of the main lining of the kiln. The filling of limestone with less than 40% of the total consumption of the amount of metal bars leads to an insufficiently high degree of dispersion of limestone in the volume of the bath. Low lime filling increases the time of its decomposition, slows down the rate of slag formation and reduces the productivity of the furnace. Partial filling of limestone in the amount of 60-80% of its total consumption provides for a fairly even distributed its distribution, respectively, in 40-70% of the metal charge. When the limestone is charged in an amount of less than 60% of that required in the first half of the melting period, acidic slag is formed that is aggressive to the main lining of the furnace. When filling limestone in the amount of more than 80% of the required duration of the melting period, it decreases slightly. Entering lime into the slag accelerates its thermal decomposition. Uniform lime feed from the moment of formation of slag coating over the entire surface of the bath until the charge is completely melted reduces the cooling effect of lime on the slag melt, accelerates the slag formation process and shortens the duration of the melt as a whole. Smelting steel grade 35 HS 100 main open-hearth furnace. The charge of open-hearth smelting consists of 30 tons of pig iron, 70 tons of metallurgical scrap and 8 tons of limestone. Example 1. 4.8 g of limestone and 28 tons of scrap are loaded into the molds into the molds. 14 tons of fine steel scrap are loaded into the furnace bottom, and then a mixture of limestone and scrap is charged into the furnace (4, - 8 tons and 28 tons), the remaining scrap metal in the amount of 28 tons and 30 tons of primary iron. After the slag cover is formed in the second half of the melting period, the rest of the (3.2 t) portions of the limestone begin to enter over the entire surface of the steelmaking bath and finish it by the time the charge is completely melted. Example 2. Layer-by-layer loading of 6.4 tons of limestone and 49 tons of metal hearth into the molds. 14 tons of fine steel scrap are loaded into the furnace hearth, after which a mixture of lime and metal scrap (49 tons respectively) is loaded into the furnace, the remaining scrap in the amount of 7 tons and 30 tons of pig iron. In the course of melting, as in Example 1, limestone in the amount of 1.6 tons is introduced into the furnace. Example 3. 5.6 tons of limestone and 38.5 tons of scrap metal are layered into the molds. 14 tons of fine steel scrap are loaded into the furnace hearth, after which a mixture of lime and metal scrap (5.6 and 38.5 tons respectively) is loaded into the furnace, the remaining metal scrap in the amount of 17.5 tons and 30 tons of pig iron. The remaining limestone (2.4 tons) is added in the same way as in Examples 1 and 2. The main technical and economic indicators of the proposed method of steelmaking in 100 tons of open-hearth furnace as compared to the base and prototype are shown in the table.

Duration of melting, h-min

Duration of melting h-min.

Increased yield of metal,%

Economic efficiency, rub. / T of steel

compared to the base object

with prototype

2-40

2-35 2-40

-50

7-05

7-15

7-10

-20 1,0

0.7

0.8

0.5

0.68

1.06

0.85 0.31 0.61 0.4

) 1097681t

The annual economic effect of the yield of a suitable metal will be

implementation of the steel melting method in comparison with the prototype method

open-hearth shop as a result of uve-180 thousand rubles, and with the basic object

the productivity of furnaces and 320 thousand rubles.

Claims (1)

METHOD OF STEEL Smelting in the open-hearth furnace, including the filling of solid metal charge and the portion input of limestone into the furnace, characterized in that, in order to increase the furnace productivity and yield suitable metal, 60-80% of limestone and 40-70% are layered outside the furnace. solid metal charge from their total consumption for smelting and subsequently heap up the previously prepared mixture and the rest of the solid metal charge into the furnace, and the filling of the rest of the limestone begins after the formation of slag over the entire surface baths and finish at the time of complete melting of the mixture.