气泡去除夹杂物技术研究现状 （2 ）Current status of research on bubble removal technology for inclusions（part II）

文章对气泡去除夹杂物技术的研究现状进行了介绍，主要包括钢包吹氩技术、钢包长水口吹氩技术、反应诱发微小异相技术、中间包气幕挡墙技术、增压减压法、超声空化法、增氮析氮法和微小氢气泡法。This article introduces the current research status of bubble removal technology, which mainly includes ladle argon blowing technology, ladle long nozzle argon blowing technology, reaction induced micro-heterogeneous phase technology, tundish gas curtain retaining wall technology, pressurization and decompression method, ultrasonic cavitation method, nitrogen addition and nitrogen precipitation method and micro hydrogen bubble method.

1 钢包吹氩技术。钢包吹氩是重要的精炼手段之一，不仅可以均匀钢液成分和温度，还可以通过气泡粘附夹杂物和气泡尾流携带夹杂物上浮的方式净化钢液。钢包吹氩用透气砖的结构对气泡尺寸有直接的影响，其孔径一般为2mm~4mm，在常用的吹氩流量范围内产生的气泡直径约为10mm~20mm，且底吹氩产生的气泡在钢液中上浮过程中会迅速膨胀，因此，气泡捕获小颗粒夹杂物概率很小，对尺寸较小的夹杂物去除效果不理想。Argon blowing technology in ladle. Argon blowing in ladle is one of the important refining methods. It can not only make the composition and temperature of molten steel uniform, but also purify molten steel by allowing bubbles to adhere to inclusions and the bubble tail to carry inclusions to float. The structure of the air-permeable bricks used for argon blowing in ladle has a direct impact on the bubble size. The pore size is generally 2mm~4mm. The diameter of the bubbles generated within the commonly used argon blowing flow range is about 10mm~20mm. The bubbles generated by bottom argon blowing will expand rapidly during the floating process in molten steel. Therefore, the probability of bubbles capturing small particle inclusions is very small, and the removal effect of smaller inclusions is not ideal.

钢包吹氩技术具有设备简单、投资少且操作简单的优点，已经被各大钢厂应用；但是其对显微夹杂物去除效果差也是无法避免的“短板”。

Ladle argon blowing technology has the advantages of simple equipment, low investment and simple operation, and has been applied by major steel mills; however, its poor effect on removing microscopic inclusions is also an unavoidable "shortcoming".

2 钢包长水口吹氩技术。连铸时在接缝下方向钢包保护套管中吹入较大量的氩气，利用套管中湍急的钢液将气体破碎为弥散微小气泡，形成的气泡随湍流钢液进入中间包中上浮长大，并不断与夹杂物发生碰撞粘附，最终携带夹杂物上浮去除。相对于传统的长水口与钢包连接处密封吹氩，钢包长水口吹氩技术吹氩量大，能在长水口和中间包注流区形成大量弥散细小气泡，具有良好的去除夹杂物效果。Argon blowing technology for ladle shroud. During continuous casting, a large amount of argon is blown into the ladle protective sleeve below the joint. The turbulent molten steel in the sleeve breaks the gas into dispersed tiny bubbles. The formed bubbles enter the tundish with the turbulent molten steel, float and grow, and constantly collide and adhere to inclusions, and finally carry the inclusions to float and be removed. Compared with the traditional argon blowing at the connection between the shroud and the ladle, the argon blowing technology for the ladle shroud has a large amount of argon blowing, which can form a large number of dispersed tiny bubbles in the shroud and the injection area of ​​the tundish, and has a good effect in removing inclusions.

钢包长水口吹氩技术须向钢液吹入较大量氩气，容易在中间包形成“裸眼”，造成钢液二次氧化。随着中间包密封技术的提高，特别是密封中间包的采用，长水口吹氩技术有望得到良好应用。

The argon blowing technology for the long shroud of the ladle requires blowing a large amount of argon into the molten steel, which is easy to form a "naked hole" in the tundish, causing secondary oxidation of the molten steel. With the improvement of tundish sealing technology, especially the adoption of sealed tundish, the argon blowing technology for the long shroud is expected to be well applied.

3 反应诱发微小异相技术。反应诱发微小异相去除钢中细小夹杂物，是通过向钢液中加入细小的碳酸钠，在钢液中生成微小气泡使夹杂物上浮去除。有研究者对此方法进一步研究，设计了一种具有该功能的复合球体。此微小球体加入钢液中，在高温下分解产生气泡和渣滴，产生的渣滴与Al2O3等夹杂物碰撞、聚集和长大，加快其上浮去除。该复合球体在鞍钢RH精炼炉开展了工业试验研究。采用该技术对钢液进行处理后，铸坯中氧化物夹杂的数量明显减少、尺寸变小，钢中全氧最低可达6×10-6。

Reaction-induced micro-heterogeneous phase technology. Reaction-induced micro-heterogeneous phase removal of fine inclusions in steel is achieved by adding fine sodium carbonate to the molten steel to generate tiny bubbles in the molten steel to make the inclusions float up and be removed. Some researchers have further studied this method and designed a composite sphere with this function. This tiny sphere is added to the molten steel and decomposes at high temperature to produce bubbles and slag droplets. The generated slag droplets collide, aggregate and grow with inclusions such as Al2O3, accelerating their floating removal. The composite sphere has been subjected to industrial test research in the RH refining furnace of Anshan Iron and Steel. After the molten steel is treated with this technology, the number of oxide inclusions in the ingot is significantly reduced, the size is reduced, and the total oxygen in the steel can be as low as 6×10-6.

该技术目前还未在钢铁企业大规模推广应用，对于该技术的理论研究还不完善，如产生的气泡尺寸、气泡在钢液中的分布及钢液温降等问题还没有深入研究。

This technology has not yet been widely promoted and applied in steel enterprises, and the theoretical research on this technology is still incomplete. For example, the size of the bubbles generated, the distribution of bubbles in the molten steel, and the temperature drop of the molten steel have not been studied in depth.

4 中间包气幕挡墙技术。中间包气幕挡墙技术即中间包底部吹氩技术，其原理是通过埋设于中间包底部的透气砖向钢液中吹入的气泡，与流经此处钢液中的夹杂物颗粒相互碰撞聚合吸附，增加了夹杂物的垂直向上运动，从而达到净化钢液的目的。同时，中间包吹氩可以改变钢液的流动状态，促进钢液的混合，有利于温度及成分的均匀。

Tundish air curtain retaining wall technology. Tundish air curtain retaining wall technology is the argon blowing technology at the bottom of the tundish. Its principle is that the bubbles blown into the molten steel through the air-permeable bricks buried at the bottom of the tundish collide with the inclusion particles in the molten steel flowing through this place, aggregate and adsorb, increase the vertical upward movement of the inclusions, and thus achieve the purpose of purifying the molten steel. At the same time, argon blowing in the tundish can change the flow state of the molten steel, promote the mixing of the molten steel, and is conducive to the uniformity of temperature and composition.

虽然中间包吹氩在理论研究方面取得了一些进展，但部分企业反映，使用效果不太稳定，在实际中应用不太广泛。目前存在的主要问题有：生成的气泡尺寸较大，捕捉去除夹杂物效果不明显；气体吹入量受限制，因为要防止中间包卷渣及钢液二次氧化；透气砖的成本稍高，埋设不方便等。

Although some progress has been made in theoretical research on argon blowing in the tundish, some companies have reported that the effect of use is not very stable and is not widely used in practice. The main problems currently exist are: the size of the generated bubbles is large, and the effect of capturing and removing inclusions is not obvious; the amount of gas blowing is limited because it is necessary to prevent the slag from rolling up in the tundish and the secondary oxidation of the molten steel; the cost of the air-permeable bricks is slightly high, and it is inconvenient to bury them, etc.

5 增压减压法。20世纪90年代初期，日本NKK公司提出了增压减压法（Pressure Elevating and Reducing Method，PERM）去除钢中夹杂物技术，其原理主要分为3个步骤：一是通过加压使N2溶解在钢液中达到过饱和；二是迅速减压，气泡在夹杂物表面异相形核并长大；三是气泡携带夹杂物上浮，最终与钢液脱离。

In the early 1990s, Japan's NKK company proposed the Pressure Elevating and Reducing Method (PERM) to remove inclusions from steel. The principle is mainly divided into three steps: first, pressurizing the steel to dissolve N2 in the molten steel to reach supersaturation; second, rapidly reducing the pressure, allowing bubbles to nucleate and grow heterogeneously on the surface of inclusions; third, the bubbles carry the inclusions to float up and eventually separate from the molten steel.

增压减压法去除钢中夹杂物效果显著。然而，由于此方法须要对钢液进行高压处理，操作难度较大，至今没有工业化生产。

The pressure increase and pressure reduction method is effective in removing inclusions from steel. However, since this method requires high pressure treatment of molten steel, it is difficult to operate and has not yet been industrialized.

6 超声空化法。超声波是一种机械波，在液体介质传播过程中会产生周期性的应力和声压变化，在钢液中传播时，会将钢液中的微小气泡核激活，使其产生包括振荡、生长、收缩乃至崩溃等一系列过程，微气泡的这种从振荡生长到崩溃的过程被称为超声空化。

Ultrasonic cavitation method. Ultrasonic waves are mechanical waves that produce periodic stress and sound pressure changes during the propagation of liquid media. When propagating in molten steel, they activate the tiny bubble nuclei in the molten steel, causing them to undergo a series of processes including oscillation, growth, contraction, and even collapse. This process of microbubbles from oscillation growth to collapse is called ultrasonic cavitation.

超声波产生的空化气泡直径小，仅有几十微米，空化气泡在上浮过程中有更多的机会和微小夹杂物发生碰撞并粘附在一起形成簇状物，从而使钢液中的微小夹杂物得到有效去除。但由于难以将超声波导入到钢液中，且很难找到可以在高温下使用的导波材料，超声空化气泡法去除夹杂物研究仍集中在水模型和实验室实验阶段，未进行大规模工业化应用。

The cavitation bubbles generated by ultrasonic waves have a small diameter of only tens of microns. During the floating process, cavitation bubbles have more opportunities to collide with tiny inclusions and adhere to each other to form clusters, thereby effectively removing tiny inclusions in the molten steel. However, due to the difficulty in introducing ultrasonic waves into molten steel and the difficulty in finding waveguide materials that can be used at high temperatures, research on the removal of inclusions by ultrasonic cavitation bubbles is still concentrated in the water model and laboratory experiment stage, and has not been applied on a large scale in industrial applications.

7 增氮析氮法。其技术原理是前期将N2充入钢液中，使钢液中氮含量显著增加；后期通过真空处理迅速减压，使钢中过饱和气体以夹杂物为核心生成大量弥散微小气泡；最后气泡携带夹杂物上浮，并在上浮过程中不断捕捉细小夹杂物，达到去除显微夹杂物的目的。

Nitrogen enrichment and nitrogen precipitation method. Its technical principle is to fill N2 into the molten steel in the early stage to significantly increase the nitrogen content in the molten steel; in the later stage, the pressure is quickly reduced through vacuum treatment, so that the supersaturated gas in the steel generates a large number of dispersed tiny bubbles with inclusions as the core; finally, the bubbles carry the inclusions to float up, and continuously capture the tiny inclusions during the floating process, so as to achieve the purpose of removing microscopic inclusions.

增氮析氮法尚处于实验室研究阶段，未进行工业验证，并且对生产氮含量敏感的钢不适用。

Nitrogen enrichment and nitrogen precipitation method is still in the laboratory research stage, has not been industrially verified, and is not applicable to the production of steel that is sensitive to nitrogen content.

8  微小氢气泡法。考虑到增氮析氮法对钢中氮含量控制的困难，有研究者研发出微小氢气泡法去除钢中夹杂物技术。其原理是，向钢液中通入焦炉煤气或天然气，焦炉煤气或天然气与钢液相互作用，其中的氢组元溶解于钢液中，使钢液中氢含量达到8ppm以上；钢液精炼脱氧后，对该钢液进行真空处理，钢中溶解氢以夹杂物为异质形核核心生成细小气泡，气泡携带夹杂物上浮到渣中去除；气泡在上浮过程中也会通过粘附夹杂物促进夹杂物上浮至渣中去除。

Tiny hydrogen bubble method. Considering the difficulty of controlling the nitrogen content in steel by nitrogen enrichment and precipitation method, some researchers have developed a tiny hydrogen bubble method to remove inclusions in steel. The principle is to introduce coke oven gas or natural gas into the molten steel. The coke oven gas or natural gas interacts with the molten steel, and the hydrogen component therein dissolves in the molten steel, so that the hydrogen content in the molten steel reaches more than 8ppm; after the molten steel is refined and deoxidized, the molten steel is vacuum treated, and the dissolved hydrogen in the steel uses the inclusions as heterogeneous nucleation cores to generate tiny bubbles, and the bubbles carry the inclusions to float to the slag for removal; during the floating process, the bubbles will also adhere to the inclusions to promote the floating of the inclusions to the slag for removal.

此技术可在吹氩站、CAS处理站、LF处理工位、AOD处理工位、RH处理工位和VD/VOD处理工位进行充氢处理，将原先向钢液吹入氩气改成吹入天然气或焦炉煤气，然后通过RH处理、VD/VOD处理工位等进行真空处理，适用范围设备多，几乎无须对现有设备进行改造；操作简单，成本低；生成的氢气泡体积细小，对钢中显微夹杂物及氮去除效果好。相较于增氮析氮法，该技术对钢中氮具有良好的去除效果，对氮含量敏感钢种依然适用。

This technology can be used for hydrogen charging treatment at argon blowing stations, CAS treatment stations, LF treatment stations, AOD treatment stations, RH treatment stations and VD/VOD treatment stations. The original argon blowing into the molten steel is changed to blowing natural gas or coke oven gas, and then vacuum treatment is performed through RH treatment, VD/VOD treatment stations, etc. It has a wide range of applicable equipment and almost no need to modify existing equipment; it is simple to operate and low in cost; the generated hydrogen bubbles are small in volume and have a good effect on removing microscopic inclusions and nitrogen in steel. Compared with the nitrogen enrichment and nitrogen precipitation method, this technology has a good removal effect on nitrogen in steel and is still applicable to steels sensitive to nitrogen content.

由于微小氢气泡法具有对钢中显微夹杂物及氮去除效果良好、适用设备广泛、操作简单等优势，在今后有望实现大规模工业应用。

Due to the advantages of the micro hydrogen bubble method, such as good removal effect on microscopic inclusions and nitrogen in steel, wide application of equipment, and simple operation, it is expected to achieve large-scale industrial application in the future.