阅读说明：本技术 一种钢包脱磷方法 (Ladle dephosphorization method ) 是由 管挺 徐建飞 谢立 于 2020-05-29 设计创作，主要内容包括：本发明涉及一种钢包脱磷方法,针对转炉出钢过程不慎下渣引起的钢水磷出格所采取的一种补救方法。其特征在于：出钢结束后,将钢包运转至捞渣工位,通过捞渣机捞出部分炉渣；之后重新将钢包运转至出钢位,加入合成渣和石英砂,并通过大流量底吹搅拌进行脱磷。本发明可避免出钢下渣造成钢水磷出格而重新回炉炼钢的损失,成本低、效率高。(The invention relates to a ladle dephosphorization method, and aims to provide a remedy method for molten steel phosphorus rejection caused by careless slag discharge in the converter tapping process. The method is characterized in that: after steel discharging is finished, the steel ladle is operated to a slag salvaging station, and partial slag is fished out through a slag salvaging machine; and then, the steel ladle is operated to the steel tapping position again, synthetic slag and quartz sand are added, and dephosphorization is carried out through high-flow bottom blowing stirring. The invention can avoid the loss of re-melting and steelmaking caused by discharging phosphorus from the molten steel due to tapping and slag discharging, and has low cost and high efficiency.)

1. A ladle dephosphorization method is characterized in that: after steel discharging is finished, the steel ladle is operated to a slag salvaging station, and partial slag is fished out through a slag salvaging machine; and then, the steel ladle is operated to the steel tapping position again, synthetic slag and quartz sand are added, and dephosphorization is carried out through high-flow bottom blowing stirring.

2. Ladle dephosphorization method according to claim 1, characterized in that: when the slag remover drags slag, 3/4 +/-0.1 slag in the ladle is fished out.

3. Ladle dephosphorization method according to claim 1, characterized in that: the synthetic slag is added in an amount of 4-5 kg/t steel, and the quartz sand is added in an amount of 0.2-0.5 kg/t steel.

4. Ladle dephosphorization method according to claim 1, characterized in that: after the synthetic slag and the quartz sand are added, the steel ladle slag comprises CaO: 25% -45%, MgO: 3% -5% of SiO₂：10％～20％，Al₂O₃：30％～50％，FeO：6％～13％。

5. Ladle dephosphorization method according to claim 1, characterized in that: the composition of the synthetic slag is as follows: CaO: 30-40%, MgO: 2% -5% of SiO₂：6％～10％，Al₂O₃：50％～60％。

6. Ladle dephosphorization method according to claim 1, characterized in that: the quartz sand comprises the following components: SiO 2₂：90％～95％，Al₂O₃：2％～5％，Fe₂O₃：2％～5％。

7. Ladle dephosphorization method according to claim 1, characterized in that: the stirring intensity is 10-15L/min, and the stirring time is 3-5 min.

8. Ladle dephosphorization method according to claim 1, characterized in that: the converter end-point slag comprises the following components in percentage by weight: CaO:35％～50％，MgO：6％～10％，SiO₂：13％～17％，FeO：15％～25％。

Technical Field

The invention belongs to the technical field of converter steelmaking, in particular to a ladle dephosphorization method, and belongs to the technical field of smelting.

Background

Phosphorus is generally considered as a harmful impurity in steel, and is easy to segregate in grain boundaries to cause the steel to be cold-brittle, so that the low-temperature impact toughness of the steel is remarkably reduced.

Various dephosphorization techniques are developed by domestic and foreign steel mills, mainly comprising a converter duplex smelting technique, a converter double-slag smelting technique and a converter single-slag smelting technique, wherein the phosphorus content at the smelting end point of the converter duplex smelting method can be stably controlled within 0.006 percent, and the phosphorus content at the smelting end point of the converter double-slag method can be stably controlled within 0.006 percentThe phosphorus content can be stably controlled within 0.01 percent, and the phosphorus content at the smelting end point of the converter single slag method can be stably controlled within 0.016 percent. In the traditional converter steelmaking technology, the dephosphorization method adopts an operation mode of high alkalinity, high FeO, large slag quantity and low temperature, and actually, phosphorus in the slag is mainly enriched in C₂S-C₃P phase, and is most favorable for increasing C₂S-C₃The basicity of the slag with the P-phase mass fraction is 2.5-3.0.

With the increase of market pressure, steel products enter a micro-profit era, and in order to improve benefits and improve steel making yield, a more common steel making method is converter single slag method smelting, and simultaneously, in order to further shorten the steel making period, the more common method is to enlarge the inner diameter of a steel outlet and shorten the steel tapping time. By adopting the method for smelting, the increase of the slag amount in the tapping process is difficult to avoid. Particularly, in the later stage of the steel tapping hole, when the operation is improper, the slag is seriously discharged, so that the rephosphorization of molten steel is increased, and the phosphorus of a product is qualified. When smelting low-alloyed steel, after molten steel is discharged completely, and molten steel is rephosphorized due to slag discharge, how to adopt effective measures to dephosphorize a steel ladle is a difficult problem for the staff of the factory. For efficient dephosphorization, chinese patent document CN101979672A discloses a method for dephosphorization to ultra-low in ladle, comprising the steps of: before converter tapping, lime, fluorite and carbon steel fly ash briquettes are added into a steel ladle, and the oxygen content of molten steel is controlled to be not less than 0.065% and the phosphorus content is not more than 0.015% when the converter tapping is carried out; the molten steel is not deoxidized and alloyed in a steel ladle; argon blowing and stirring are carried out at the bottom of the ladle in the whole tapping process. Compared with the technical scheme of the invention, the method has the following disadvantages: the problem of rephosphorization caused by slag discharge in the converter tapping process cannot be solved. The document is used for smelting extremely low phosphorus steel (the phosphorus content is less than or equal to 0.003 percent), and the dephosphorization task is divided into two parts: dephosphorizing by a converter and dephosphorizing by a steel ladle, wherein the dephosphorizing by the steel ladle needs to add lime, fluorite and carbon steel dedusting ash briquetting into the steel ladle in advance. The invention mainly aims at the problem of rephosphorization caused by tapping and slag discharging, the technology is not needed when slag discharging is not carried out, and materials do not need to be prepared in a steel ladle in advance, so that the waste of resources is caused. In addition, fluorite is added into the steel ladle in the comparison technology, so that the service life of the steel ladle is shortened to a certain extent, and the environment is polluted.

Disclosure of Invention

The invention aims to provide a ladle dephosphorization method to meet the requirement of recovering qualified molten steel during converter slag tapping.

The specific method steps and the control method parameters are as follows:

a ladle dephosphorization method, which is a remedy method aiming at the molten steel phosphorus rejection caused by the careless slag discharge in the converter tapping process. The method comprises the following steps: after steel discharging is finished, the steel ladle is operated to a slag salvaging station, and partial slag is fished out through a slag salvaging machine; and then, the steel ladle is operated to the steel tapping position again, synthetic slag and quartz sand are added, and dephosphorization is carried out through high-flow bottom blowing stirring.

Preferably, when the slag remover drags slag, about 3/4 slag in the ladle is fished out.

Preferably, the synthetic slag is added in an amount of 4-5 kg/t steel, and the quartz sand is added in an amount of 0.2-0.5 kg/t steel.

Preferably, after the synthetic slag and the quartz sand are added, the steel ladle slag has the following components of CaO: 25% -45%, MgO: 3% -5% of SiO₂：10％～20％，Al₂O₃：30％～50％，FeO：6％～13％。

Preferably, the composition of the synthetic slag is as follows: CaO: 30-40%, MgO: 2% -5% of SiO₂：6％～10％，Al₂O₃：50％～60％。

Preferably, the quartz sand comprises the following components: SiO 2₂：90％～95％，Al₂O₃：2％～5％，Fe₂O₃：2％～5％。

Preferably, the stirring intensity is 10-15L/min, and the stirring time is 3-5 min.

Preferably, the converter end point slag comprises the following components in percentage by weight: CaO: 35% -50%, MgO: 6 to 10 percent of SiO₂：13％～17％，FeO：15％～25％。

The invention has the advantages that: the method discovers that the molten steel phosphorus is discharged due to the slag discharge of the converter after the molten steel is discharged, and develops the ladle furnace dephosphorization methodMost of the furnace slag in the ladle can effectively reduce the phosphorus-rich slag in the ladle and reduce the risk of rephosphorization; then reasonably proportioning, controlling the alkalinity of the slag to be 2.5-3.0, and improving C in the slag₂S-C₃P phase while controlling Al₂O₃: 30% -50%, FeO: 6 to 13 percent of liquid slag can be more beneficial to fixing phosphorus and effectively removing the phosphorus in the molten steel.

Detailed Description

The invention is described in more detail below with reference to the following examples: