阅读说明：本技术 一种利用二氧化碳及氮气溅渣护炉的方法 (Method for protecting furnace by splashing slag with carbon dioxide and nitrogen ) 是由 魏国立 朱青德 胡绍岩 冯超 朱荣 于 2021-07-21 设计创作，主要内容包括：本发明提供了一种利用二氧化碳及氮气溅渣护炉的方法,适用于使用溅渣护炉维护炉况的转炉,在转炉出钢后加入特制的溅渣料,根据终点温度、钢水成分等参数调配加入量,溅渣前期全部采用二氧化碳为溅渣气体,利用二氧化碳动能及与碳反应吸热的特性,实现了前期低黏度炉渣快速稠化,中期利用二氧化碳和氮气的连续性变化,使气体的动能不断变化,丰富了渣块的溅甩角度,扩大了溅渣护炉刮渣的炉膛内面积,减少单一气体溅渣的薄弱部位,后期利用二氧化碳与碳反应的吸热机理,实现了溅渣层快速降温凝固,并将溅渣层表面的碳脱出,提高了溅渣层的抗侵蚀能力,更加有利于转炉炉况的维护和长寿命操作,具有良好的经济效益和社会效益。(The invention provides a method for protecting a furnace by splashing slag by utilizing carbon dioxide and nitrogen, which is suitable for a converter using the splashing slag to protect the furnace to maintain the furnace condition, wherein a special splashing slag material is added after the tapping of the converter, the adding amount is adjusted according to parameters such as end point temperature, molten steel components and the like, carbon dioxide is completely adopted as splashing slag gas at the early stage of splashing slag, the quick thickening of low-viscosity slag at the early stage is realized by utilizing the kinetic energy of the carbon dioxide and the characteristic of heat absorption of reaction with carbon, the kinetic energy of the gas is continuously changed by utilizing the continuous change of the carbon dioxide and the nitrogen at the middle stage, the splashing angle of a slag block is enriched, the inner area of a furnace chamber for scraping the splashing slag by the splashing slag protection is enlarged, the weak part of the single gas splashing slag is reduced, the heat absorption mechanism of the reaction of the carbon dioxide and the carbon is utilized at the later stage, the quick cooling and solidification of the splashing slag layer is realized, the carbon on the surface of the splashing slag layer is removed, the anti-erosion capability of the splashing slag layer is improved, and the maintenance and the long-life operation of the converter under the furnace condition of the converter is more favorable for the converter, has good economic benefit and social benefit.)

1. A method for protecting a furnace by splashing slag with carbon dioxide and nitrogen comprises the following steps:

a. after tapping, rocking the furnace to a normal smelting position, adding 0.8-2kg/t slag splashing material containing 15-25% of carbon and 14-24% of magnesium according to the tapping temperature, fixing the lance position at 220mm higher than the blowing lance position, wherein the slag splashing gas is completely carbon dioxide, and continuously blowing the carbon dioxide at the constant lance position until slag splashing occurs at the furnace mouth;

b. fixing the lance position between 200-1000mm higher than the converting lance position for circular injection, switching slag splashing gas into mixed gas of carbon dioxide and nitrogen, wherein the content of the carbon dioxide and the nitrogen in the mixed gas changes according to a sine curve, the content curves of the two gases always differ by a half sine curve period, and the lance position is changed by 1.0-1.5m in the injection process until dry slag is splashed and thrown out from a furnace mouth;

c. and (3) fixing the lance position at a position 200mm higher than the converting lance position, continuously splashing slag until no dry slag is thrown out at the furnace mouth because all slag splashing gas is carbon dioxide, ending slag splashing operation, and performing secondary furnace loading operation after pouring out the dry slag in the furnace.

2. The method as claimed in claim 1, wherein the slag temperature before the slag splashing in step a is 1500-1600 ℃, and the slag temperature is reduced to below 1500 ℃ after the slag splashing.

Technical Field

The invention belongs to the technical field of metal smelting, and relates to a method for protecting a furnace by splashing slag with carbon dioxide and nitrogen.

Background

The slag plays an important role in the smelting process of the converter, can be used as a smelting medium, a slag splashing furnace protection raw material and the like, and the viscosity of the liquid slag has direct influence on the smelting process and the slag splashing effect. In the converter steelmaking production, the stability of converter smelting is a plurality of problems, which causes the maintenance of the converter shape to be difficult.

The viscosity is one of the characteristics of the slag, the slag with different viscosities directly influences the quality of the slag splashing effect, wherein if the viscosity of the slag is larger, the requirement of dynamic conditions required by slag splashing is improved, the impact area of the slag is smaller, the upper slag is difficult to splash, the lower slag is in a liquid state to flush the bottom of the furnace, the bottom of the furnace and the part of a molten pool are flushed more seriously, and the slag splashing effect is poorer; if the slag viscosity is smaller, the requirement on dynamic conditions is reduced, but the adhesion capability to the furnace wall is weaker, the original slag splashing layer is easy to peel off, and meanwhile, in order to splash the slag, longer slag splashing time is needed, and the operation rate of the converter is influenced.

The current steel-making production is a fast-paced production mode, the safety problem caused by the fact that furnace slag is not splashed dry is avoided, the slag splashing time is shortened through related technical measures, and the purpose of efficiently splashing slag is achieved. In order to achieve the purpose, both domestic and foreign scholars actively carry out technical research and innovation, and through slag splashing furnace protection test research on different slag viscosities under different process conditions, the slag viscosity is found to be within the range of 0.02-0.1 Pa.S, so that the slag splashing time can be shortened, a better slag splashing effect is achieved, and the slag splashing viscosity is regarded as appropriate. Therefore, how to stably and effectively control the viscosity of the final slag to achieve efficient furnace protection in production is a technical problem to be solved.

The invention has the patent name: a method for slag splashing furnace protection (application publication number: CN 106947845A) comprises the following steps: the raw dolomite is added into the converter before tapping to adjust the temperature of the slag, the modifier is added to reduce the oxidability of the slag, and during slag splashing, the purposes of accelerating the cooling of the slag and shortening the slag splashing time are achieved by adjusting the flow rate of top-blown nitrogen. The method controls the addition of raw dolomite according to the tapping temperature of 1660 ℃ as a node, and controls the addition of a modifier according to the end point molten steel oxygen of 800ppm as a limit value, and has the defects that the scheme has certain randomness and blindness because the addition is not accurately calculated and controlled, the waste of resources is easily caused, and the corresponding slag splashing effect cannot be achieved, and the influence of the addition of the raw dolomite and the modifier to the converter on the viscosity of the slag is not involved.

The invention has the patent name: the invention discloses a converter slag splashing protection control system and a method (application publication number: CN 10818383A), and the method specifically comprises the following steps: the laser range finder detects the thickness of each point of the furnace lining, when the thickness of the bottom of the furnace lining is too thin, the converter steelmaking secondary model is used for realizing that the model controls the gun position and the nitrogen flow of the slag splashing gun, so that the audio value in the audio curve is in a bass frequency zone, the audio frequency zone of the bass frequency zone is 20-35hz, when the thickness of the molten pool part of the furnace lining is too thin, the converter steelmaking secondary model is used for realizing that the model controls the gun position and the nitrogen flow of the slag splashing gun, so that the audio value in the audio curve is in a bass frequency zone, the audio frequency zone of the bass frequency zone is 35-70hz, the change rule of the audio value and the slag splashing part is explored mainly by using the modern computer technology and combining with the audio detection technology, the gun position and the nitrogen flow of the slag splashing gun are adjusted based on the audio value, the monitoring and the judgment of the slag splashing condition and the slag splashing effect are realized, thereby the blindness is reduced, and the slag splashing efficiency and the slag effect are improved, is convenient for the control of the converter shape of the converter and is beneficial to prolonging the service life of the converter. The nitrogen slag splashing furnace protection method has the defects that the nitrogen slag splashing furnace protection is used, the temperature of the slag cannot be rapidly reduced when the viscosity of the slag is lower, and meanwhile, the purposes of efficiently splashing the slag and improving the operation rate of the converter in the current stage fast-rhythm production mode cannot be achieved due to the fact that the molecular weight of the nitrogen slag splashing furnace protection method is small and the slag splashing effect and the speed deviation of the slag are small.

Therefore, the gas switching can quickly control the viscosity of the final slag within a proper range, and the slag is thrown and splashed by the large kinetic energy characteristic of the gas, so that the cooling is better, the slag splashing effect is ensured, and the slag splashing time is shortened.

For the above reasons, it is necessary to provide a method for protecting a furnace by splashing slag with carbon dioxide and nitrogen, and solve the problems of rapid adjustment of slag viscosity and change of slag sputtering angle, so as to achieve efficient slag splashing protection.

Disclosure of Invention

The invention aims to provide a method for protecting a converter by splashing slag with carbon dioxide and nitrogen aiming at the problems in the prior art, and solves the problems that the existing method for protecting the converter can not realize high-efficiency slag splashing and improve the operating rate of the converter in the fast-paced production mode at the present stage.

Therefore, the invention provides a method for protecting a furnace by splashing slag by using carbon dioxide and nitrogen, which comprises the following steps:

a. after tapping is finished, the furnace is shaken to a normal smelting position, 0.8-2kg/t of slag splashing material containing 15-25% of carbon and 14-24% of magnesium is added according to the tapping temperature, the gun position is fixed 200mm higher than the converting gun position, slag splashing gas is all carbon dioxide, the constant gun position continuously blows the carbon dioxide until slag splashing occurs at the furnace mouth, wherein the carbon dioxide has larger kinetic energy than nitrogen, the slag and the slag splashing material can be mixed more quickly, and the carbon dioxide reacts with carbon in the slag splashing material to absorb partial heat, so that the thickening of the slag can be accelerated, and the slag splashing period can be shortened;

b. the method comprises the following steps of fixing a lance position between 200-plus-1000 mm positions higher than a blowing lance position for circular blowing, switching slag splashing gas into mixed gas of carbon dioxide and nitrogen, wherein the content of the carbon dioxide and the nitrogen in the mixed gas changes according to a sine curve, the content curves of the two gases always differ by a half sine curve period, and the lance position is changed by 1.0-1.5m in the blowing process until a furnace mouth splashes dry slag, wherein the splashing angle of a slag block can be larger through continuous change of the proportion of the two gases, each corner in a hearth can be better covered, and the covering effect in the hearth is better compared with that of pure nitrogen slag splashing;

c. fixing the lance position at a position 200mm higher than the converting lance position, wherein slag splashing gas is all carbon dioxide, continuously splashing slag until no dry slag is thrown out at a furnace mouth, ending slag splashing operation, and performing secondary furnace loading operation after pouring out the dry slag in the furnace, wherein the reason for adopting pure carbon dioxide gas is that the pure carbon dioxide gas reacts with carbon on the surface of a slag splashing layer, absorbs heat to quickly solidify the slag layer, and increases the strength of the slag splashing layer; meanwhile, the anti-corrosion capability of the slag splashing layer is greatly increased along with the carbon on the surface of the slag splashing layer.

Further, the slag temperature before the slag splashing is added in the step a is 1500-1600 ℃, and the slag temperature is reduced to be below 1500 ℃ after the slag splashing is added.

The invention has the beneficial effects that:

the invention adopts the process of mixing carbon dioxide and nitrogen to splash slag, realizes the quick thickening of low-viscosity slag in the early stage, quickly reduces the temperature of the slag by the principle of heat absorption reaction of carbon in the slag splashing material and the carbon dioxide, continuously changes the kinetic energy of gas by using the continuous change of the carbon dioxide and the nitrogen in the middle stage, enriches the splashing angle of slag blocks, enlarges the inner area of a hearth for splashing slag to protect and scrape the slag, reduces the weak part of single gas splashing slag, quickly cools and solidifies the slag splashing layer by using the heat absorption mechanism of the reaction of the carbon dioxide and the carbon in the later stage, removes the carbon on the surface of the slag splashing layer, improves the anti-erosion capacity of the slag splashing layer, is more beneficial to the maintenance and the long-life operation of a converter, and has good economic benefit and social benefit.

Detailed Description

The technical solution of the present invention will be described with reference to the following examples.

Example 1

A method for protecting a converter by splashing slag by using carbon dioxide and nitrogen is used for smelting a steel species CSPSPHC, the end point carbon content is 0.038%, the end point temperature is 1693 ℃, and the slag 1/2 in a converter is poured out after tapping, and the method comprises the following steps:

a. rocking the furnace to a normal smelting position, adding 1.8-2.0kg/t of slag splashing material containing 15-25% of carbon and 14-24% of magnesium according to the tapping temperature, fixing the gun position 200mm higher than the converting gun position, wherein slag splashing gas is all carbon dioxide, the gas pressure is 1.2MPa, the carbon dioxide blowing gun position is 1m, and slag splashing can be seen when the slag is blown to a furnace mouth within 45-50 s;

b. fixing the lance position between 200 and 1000mm higher than the blowing lance position for circular blowing, switching the slag splashing gas into a mixed gas of carbon dioxide and nitrogen, changing the content of the carbon dioxide and the nitrogen in the mixed gas according to a sine curve, wherein the content curves of the two gases always differ by a half sine curve period, changing the lance position by 1.0-1.2m in the blowing process, blowing the mixed gas to 140 and 150 seconds, and splashing dry slag from the furnace mouth;

c. and (3) fixing the lance position at a position 200mm higher than the converting lance position, wherein slag splashing gas is carbon dioxide, when the blowing is carried out for 160s, no dry slag is thrown out from a furnace mouth, the slag splashing operation is finished, and the secondary furnace loading operation is carried out after the dry slag in the furnace is poured out.

Example 2

A method for protecting a converter by splashing slag by using carbon dioxide and nitrogen is used for smelting a steel seed 355B, the end point carbon content is 0.078%, the end point temperature is 1710 ℃, and the slag 1/2 in a converter is poured out after tapping is finished, and the method comprises the following steps:

a. rocking the furnace to a normal smelting position, adding 1.6-1.8kg/t of slag splashing material containing 15-25% of carbon and 14-24% of magnesium according to the tapping temperature, fixing the gun position 200mm higher than the converting gun position, wherein slag splashing gas is all carbon dioxide, the gas pressure is 1.2MPa, the carbon dioxide blowing gun position is 1m, and slag splashing can be seen when the slag is blown to a furnace mouth for 35-40 s;

b. fixing the lance position between 200-plus-one and 1000mm higher than the converting lance position for circulating injection, switching the slag splashing gas into a mixed gas of carbon dioxide and nitrogen, changing the content of the carbon dioxide and the nitrogen in the mixed gas according to a sine curve, wherein the content curves of the two gases always differ by a half sine curve period, changing the lance position by 1.1-1.3m in the injection process, blowing the mixed gas to 130-plus-one for 140s, and splashing and throwing dry slag out of a furnace mouth;

c. and (3) fixing the lance position at a position 200mm higher than the converting lance position, wherein slag splashing gas is completely carbon dioxide, when the blowing is carried out for 150s, no dry slag is thrown out from a furnace mouth, the slag splashing operation is finished, and the secondary furnace loading operation is carried out after the dry slag in the furnace is poured out.

Example 3

A method for protecting a converter by splashing slag with carbon dioxide and nitrogen comprises the following steps of smelting a steel variety No. 70, controlling the end point carbon content to be 0.65%, controlling the end point temperature to be 1650 ℃, and pouring out 2/3 slag in a converter after tapping is finished:

a. rocking the furnace to a normal smelting position, adding 0.8-1.0kg/t of slag splashing material containing 15-25% of carbon and 14-24% of magnesium according to the tapping temperature, fixing the gun position 200mm higher than the converting gun position, wherein slag splashing gas is all carbon dioxide, the gas pressure is 1.2MPa, the carbon dioxide blowing gun position is 1m, and slag splashing can be seen when the slag is blown to a furnace mouth for 25-30 s;

b. the lance position is fixed between the position 200-plus-one pressure-sensitive material and the position 1000mm higher than the converting lance position for circular injection, the slag splashing gas is switched into the mixed gas of carbon dioxide and nitrogen, the content of the carbon dioxide and the nitrogen in the mixed gas changes according to a sine curve, the content curve of the two gases always differs by half a sine curve period, the slag splashing amount at the furnace mouth also changes along with the change of the gas proportion, the lance position is changed to 1.3-1.5m in the injection process, the mixed gas is blown to 100-plus-one pressure-sensitive material for 105s, and the furnace mouth splashes dry slag;

c. and (3) fixing the lance position at a position 200mm higher than the converting lance position, wherein slag splashing gas is carbon dioxide, when the blowing is carried out for 130s, no dry slag is thrown out from a furnace mouth any more, the slag splashing operation is finished, and the secondary furnace loading operation is carried out after the dry slag in the furnace is poured out.