A kind of high-density pellet for converter dephosphorization and using method thereof

Abstract

The invention relates to a high-density pellet for dephosphorization of a converter and a using method of the high-density pellet. Main raw materials of the high-density pellet are composed of, by mass, 55-75% of ferric oxide powder, 15-35% of scrap iron, 5-10% of coke powder and 2-5% of a bonding agent. The high-density pellet is in a spherical shape or an oval spherical shape or a flat spherical shape. The maximum diameter of the high-density pellet is 4-8 cm, the minimum diameter of the high-density pellet is 3-4 cm, and the density of the high-density pellet is 3,500-4,500 kg / m<3>. In the dephosphorization stage of a double-slag method of the converter, the high-density pellet is added during the period from 1 min after initial oxygen blowing to 1-3 min before dephosphorization slag pouring so that dephosphorization slag with low iron content can be conveniently poured out; meanwhile, FeOx can be constantly provided for the dephosphorization slag to maintain the dephosphorization capability of the dephosphorization slag, and the stable dephosphorization technology of the double-slag method of the converter is achieved.

Description

technical field [0001] The invention relates to the field of converter steelmaking, in particular to a high-density pellet for converter dephosphorization and a use method thereof. Background technique [0002] With the increase of the amount of low-phosphorus steel, and in order to reduce the dependence on the dephosphorization of hot metal pretreatment, more and more attention has been paid to dephosphorization by double slag method. The so-called double slag method refers to dephosphorization in the same converter first, after the dephosphorization is completed, part of the slag is discharged, and then decarburized. After the smelting, the slag can be left for the next furnace smelting. The slag left in the previous furnace greatly reduces the addition of lime and dolomite, and ensures the production of low-phosphorus steel. However, since pouring the dephosphorization slag needs to be completed at a relatively low temperature in the molten pool, when the fluidity or foa...

AI Technical Summary

Problems solved by technology

[0003] Chinese patent CN102839251A discloses a method for smelting low-phosphorus steel. The main method is to add bauxite to the furnace to adjust the fluidity of the slag before pouring out the dephosphorization slag, so as to ensure that the amount of dephosphorization slag poured out is greater than 70%. The addition of bauxite will inevitably reduce the phosphorus capacity of the slag, thereby reducing the dephosphorization ability of the slag

However, the iron ore added may be poured out when the dephosphorization slag is poured later, causing waste

Chinese patent CN102965463A discloses a high-efficiency converter dephosphorization process. It operates at a low gun position during the dephosphorization stage. After dephosphorization for 2 to 3 minutes, iron ore is added to ensure that the FeOx content in the slag is within an appropriate range. This method also has the disadvantage of adding iron The ore has been dumped, creating a waste risk

Chinese patent CN102559985A discloses a converter low-phosphorus steel smelting method, which mainly uses the double slag method to smelt low-phosphorus steel, and provides a calculation method for the amount of sinter added. However, even if the amount of sinter added is properly controlled, it is difficult Ensure that the sinter can produce a good foaming effect of dephosphorization slag

[0006] Chinese patent CN102634629A discloses a smelting process for producing low-carbon ultra-low-phosphorus steel with a converter. The main method is to use ferrosilicon to adjust slag, and to produce ultra-low-phosphorus steel by pouring slag multiple times to avoid the problem of poor fluidity of dephosphorization slag. However, repeated slag dumping will lengthen the smelting time and greatly affect the production efficiency

[0007] Chinese patent CN1600872A discloses a converter dephosphorization agent and its manufacturing method, the main components are 51%-70% iron oxide, 20-39% calcium oxide and 1-10% aluminum oxide, and use high temperature chemical reaction to generate ferroaluminic acid Calcium is used to achieve dephosphorization. This dephosphorization agent has a good pre-melting effect, but it greatly increases the cost of dephosphorization. Dumping Contribution

[0008] To sum up, in the prior art, it is mainly through increasing Al in dephosphorization slag 2 o 3 content or FeOx content to improve its fluidity, however, the influence of dephosphorization slag foaming on slag dumping is rarely considered

But in fact, if the foaming effect of the dephosphorization slag is poor, there is a great risk of pouring iron during the slag dumping process

At the same time, the common practice in converter double slag dephosphorization production is to directly add iron ore to supplement oxygen to the dephosphorization slag to improve the fluidity of the dephosphorization slag, but the iron ore cannot improve the foaming effect of the dephosphorization slag. During the slag process, the iron ore will also be poured out, making the iron element unable to be recovered