CN109929964A - A kind of method of oxygen coverter high pressure blow smelting operation agstone slag making dephosphorization - Google Patents

Abstract

The present invention relates to technical field of ferrous metallurgy, a kind of more particularly to method of oxygen coverter high pressure blow smelting operation agstone slag making dephosphorization, now propose following scheme, comprising the following steps: S1, the raw material for preparing following parts by weight: 20-80 parts, 2-8 parts of lime stone powder of ferriferous raw material (iron powder, pig iron, ladle)；S2, it the ferriferous raw material of above-mentioned parts by weight is placed into molten iron container generates molten iron, molten iron temperature is controlled at 1350 DEG C -1500 DEG C；S3, above-mentioned parts by weight lime stone powder is blown into molten iron using carrier gas as carrier by oxygen rifle, the blowing time is 0.5min-30min；S4, thermometric sampling analysis is carried out to finished product.The present invention utilizes the resolution characteristic of lime stone, and the advantage of jet metaurgy is utilized, and lime stone powder is effectively utilized via the product decomposed after rapidly heating up, wherein the process of CaO participation slag making dephosphorization, and CO₂CO is generated after reacting with C, Si, Mn etc. in molten iron, can continue to utilize, with low, the high-efficient advantage of cost of investment.

Description

A method for high-pressure injection of limestone powder in an oxygen converter for slagging and dephosphorization

technical field

The invention relates to the technical field of iron and steel metallurgy, in particular to a method for high-pressure injection of limestone powder in an oxygen converter for slagging and dephosphorization.

Background technique

Slag making is a crucial part of the converter process. The purpose of converter slagging is to remove phosphorus and sulfur in molten iron. Therefore, the quality of slagging effect directly affects the effect of converter to remove impurity elements in molten iron. The materials required for current converter slagging include lime, fluorite, dolomite, iron ore and synthetic slagging agents. Lime is used as a slagging raw material and its main component is CaO. The activity of lime directly determines the slagging situation. The oxygen supply time of oxygen converter steelmaking is generally only ten minutes. During this period, the converter must form a slag with a certain basicity, good fluidity, reasonable oxidation and normal foaming. Only when all the above conditions are met can Smelting out qualified molten steel.

The current method for dephosphorization of molten iron in converter is to supply oxygen quickly into molten iron to make phosphorus generate P ₂ O ₅ and float in the slag, but P ₂ O ₅ in the slag is unstable and can be easily reduced and re-entered into molten iron, so it is necessary to add alkaline The slagging agent lime makes P ₂ O ₅ react with CaO in the slag to form calcium silicate. The calcium silicate has a high and stable melting point, so that the P element is stably dissolved in the slag to achieve the purpose of removing P. In the reaction process of molten iron dephosphorization, lime plays a vital role as a phosphorus-fixing agent. Since lime is not a natural thing, it is obtained by calcining limestone at high temperature in a lime kiln. It can fully complete the decomposition process. Generally, the limestone is calcined in the furnace for 2 to 4 hours, and the calcination temperature is 1000℃～

About 1200℃, while the temperature required for limestone decomposition is 900℃, which is much lower than the calcination temperature. Therefore, when the internal area of the massive limestone is decomposed, the lime that has already been decomposed on the outside needs to be heated for several hours under high temperature conditions, which will inevitably lead to serious overburning of the exterior of the lime, and overburning will inevitably reduce the activity of the lime. At the same time, it is well known that the lime calcination process has a series of problems such as a large amount of energy waste and environmental pollution.

The main component of limestone is CaCO ₃ , which is decomposed into CaO and CO ₂ when heated at high temperature. CaO can be used as a slag-forming material in the converter process, and the released CO ₂ can participate in the molten pool reaction. Therefore, adding limestone as a slag-forming material into the converter can not only complete the task of slag-forming and dephosphorization, but also utilize the CO ₂ produced by it as a resource, which greatly reduces the utilization cost of CO ₂ . Therefore, it is proposed to use limestone instead of lime to make slag to make steel, and try to save energy and reduce emissions in the production process and control environmental pollution. The method of replacing lime with lime to make slag for steelmaking eliminates the lime calcination link, thus shortening the production line, and the lime generated in the converter does not need to be cooled and then heated up, which improves the heat utilization efficiency and eliminates the pollution discharge during lime calcination and transportation. The research shows that: compared with the calcination at low temperature and long time in the traditional lime kiln, the newly generated lime calcined at high temperature and short time in the early stage of the converter has higher activity, so that it can quickly participate in the slagging process; the CO ₂ decomposed by the limestone in the converter , which can react with [C], [Si], [Mn], and Fe(l) in molten iron to generate CO, thereby increasing the concentration of CO in the furnace gas and the recovery of gas.

However, the decomposition of limestone consumes a lot of heat, especially when it is added centrally from the top through the silo, the heat consumption is even greater. The diameter of limestone is generally between 10-40mm. Larger limestone blocks are not easy to be calcined and decomposed. After limestone is added to slag, the temperature of the contact surface between limestone and primary slag decreases rapidly due to the decomposition and absorption of heat, forming a relatively hard slag shell and the reaction surface. The activity is reduced, which is not conducive to the subsequent slagging process, resulting in that the CO ₂ carried by the limestone is not used; in addition, the density of the limestone is about 2.7g/cm ³ , and the density is about half of the molten iron pool. There is a stirring effect of top-blowing oxygen, but some limestone still floats on the upper part of the molten pool. The CO ₂ generated by the decomposition of limestone cannot fully contact the molten pool and directly enters the furnace gas, and the utilization rate of CO ₂ is not high. In order to solve this problem, a method of high-pressure injection of limestone powder in oxygen converter is proposed to make slag and steelmaking. The limestone powder is injected into the high-temperature metal molten pool with gas as a carrier in the form of high-pressure injection, which just makes use of the advantages of injection metallurgy. The injection metallurgy technology sends the powder carrier gas into the deep part of the molten steel through the injection element, so that the powder and the molten steel fully contact and participate in the reaction, which improves the contact area and surface activity between the reactants, improves the production efficiency and further improves the molten steel. Cleanliness: The particle size of the limestone injected by the converter is small, the heat transfer process is no longer restricted, and it can be quickly decomposed by heating in the metal molten pool. The high-quality lime produced by calcination has large specific surface area, large porosity and small bulk density. It has the characteristics of high surface activity, which can improve the effect and rate of slagging; and the CO ₂ released by the decomposition of limestone particles can fully participate in the steelmaking reaction as an internal gas source, replacing part of the oxygen for oxygen supply while achieving soft blowing and improving the power of the molten pool. study conditions.

If the above-mentioned method of high-pressure injection of limestone powder in the converter is used for slagging and dephosphorization, after the small-particle limestone enters the molten iron pool at a high speed, the decomposition process will be completed within a few milliseconds, and the small particles of active high-activity lime produced by the decomposition can fully participate in the production process. Slag reaction. The _CO2 produced by the decomposition of granular limestone, as a weak oxidant, can fully react with the elements in molten iron, replace part of the oxygen supply, and at the same time play the role of stirring the molten pool. Therefore, the above-mentioned method of high-pressure injection of limestone powder in a converter for slagging and dephosphorization can efficiently accomplish the task of slagging and dephosphorization, and at the same time, CO ₂ can be utilized as a resource.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the problem of difficulty in slagging by using massive limestone slag in the prior art, and the low utilization rate of CO ₂ produced by limestone decomposition. Method for slag dephosphorization.

In order to achieve the above object, the present invention adopts the following technical solutions:

A method for high-pressure injection of limestone powder in an oxygen converter for slagging and dephosphorization, comprising the following steps:

S1, prepare the following raw materials by weight: 20-80 parts of ferrous raw materials (iron powder, pig iron block, ladle), and 2-8 parts of limestone powder;

S2, place the iron raw material of the above-mentioned weight portion into the molten iron container to generate molten iron, and the temperature of the molten iron is controlled at 1350 ℃-1500 ℃;

S3, the above-mentioned weight portion limestone powder is blown into molten iron by oxygen lance as carrier with carrier gas, and the injection time is 0.5min-30min;

S4. Perform temperature measurement and sampling analysis on the finished product.

Preferably, the carbon content in the molten iron is 2.5%-5%, the Si content is 0.3%-0.4%, the Mn content is 0.1%-0.3%, and the P content is 0.1%-0.2%.

Preferably, the particle size of the limestone powder is 0.01mm-2mm.

Preferably, the molten iron container is one of a converter, a ladle, a corundum crucible, and a vacuum induction furnace.

Preferably, the carrier gas is one or more of N ₂ , Ar, Ne, and Kr.

Preferably, the material of the nozzle of the oxygen lance is one of a metal material or a material resistant to high temperature erosion.

Preferably, the limestone blowing method is one or more of bottom blowing, top blowing and side blowing.

The beneficial effects of the present invention are:

The invention utilizes the decomposition characteristics of limestone and the advantages of spray metallurgy, and effectively utilizes the decomposed products of limestone powder through rapid heating, wherein CaO participates in the process of slagging and dephosphorization, and CO ₂ and C, Si in molten iron , Mn and other reactions generate CO, which can be used continuously, and has the advantages of low investment cost and high efficiency.

Description of drawings

1 is a schematic diagram of the thermodynamic limit of _CO2 participating in the high-carbon and low-temperature molten iron reaction in a method for slagging and dephosphorization by high-pressure injection of limestone powder in an oxygen converter proposed by the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments.

Example 1

S1, prepare the following raw materials by weight: 20 parts of iron powder, 2 parts of limestone powder;

S2, the iron powder of the above-mentioned weight portion is placed in the corundum crucible to generate molten iron, the molten iron temperature is controlled at 1450 ° C, the carbon content in the molten iron is 4.5%, the Si content is 0.38%, the Mn content is 0.2%, and the P content is 0.1%;

S3, the above-mentioned weight portion limestone powder is _sprayed into molten iron by oxygen lance with N as a carrier, and the spray time is 10min;

S4. Perform temperature measurement and sampling analysis on the finished product. The molten iron temperature is 1395°C, the carbon content of the molten iron is 4.32%, the Si content is 0.28%, the Mn content is 0.16%, and the P content is 0.08%.

Embodiment 2

S1, prepare the following raw materials by weight: 50 parts of pig iron blocks, 5 parts of limestone powder;

S2, place the pig iron block of the above weight portion into a vacuum induction furnace to generate molten iron, the temperature of the molten iron is controlled at 1500 ° C, the carbon content in the molten iron is 4.2%, the Si content is 0.3%, the Mn content is 0.2%, and the P content is 0.15% ;

S3, the above-mentioned weight portion limestone powder is _sprayed into molten iron by oxygen lance with N as a carrier, and the spray time is 30min;

S4. Perform temperature measurement and sampling analysis on the finished product. The molten iron temperature is 1442°C, the carbon content is 3.85%, the Si content is 0.12%, the Mn content is 0.08%, and the P content is 0.08%.

Embodiment 3

S1, prepare the following raw materials by weight: 80 parts of molten iron;

S2, placing the iron raw material of the above-mentioned weight portion into a molten iron container to generate molten iron, and the temperature of the molten iron is controlled at 1432 ° C, wherein the carbon content in the molten iron is 4.2%, the Si content is 0.32%, and the P content is 0.12%;

S3, the CO ₂ with a purity of 100% is injected into the molten iron through an oxygen lance at a gas supply intensity of 3Nm ³ per ton of iron, and the injection time is 10min;

S4. Perform temperature measurement and sampling analysis on the finished product. The obtained molten iron temperature is 1401° C., the carbon content is 3.79%, the Si content is 0.14%, and the P content is 0.11%.

The above description is only a preferred embodiment of the present invention, but the protection scope of the present invention is not limited to this. The equivalent replacement or change of the inventive concept thereof shall be included within the protection scope of the present invention.

Claims (7)

1. a kind of method of oxygen coverter high pressure blow smelting operation agstone slag making dephosphorization, which comprises the following steps:

S1, the raw material for preparing following parts by weight: 20-80 parts of ferriferous raw material (iron powder, pig iron, ladle), lime stone powder 2-8 Part；

S2, the ferriferous raw material of above-mentioned parts by weight be placed into molten iron container generate molten iron, molten iron temperature control 1350 DEG C- 1500℃；

S3, above-mentioned parts by weight lime stone powder is blown into molten iron using carrier gas as carrier by oxygen rifle, blowing the time be 0.5min-30min；

S4, thermometric sampling analysis is carried out to finished product.

2. a kind of method of oxygen coverter high pressure blow smelting operation agstone slag making dephosphorization according to claim 1, feature exist In, in the molten iron carbon content be 2.5%-5%, Si content be 0.3%-0.4%, Mn content be 0.1%-0.3%, P content For 0.1%-0.2%.

3. a kind of method of oxygen coverter high pressure blow smelting operation agstone slag making dephosphorization according to claim 1, feature exist In the granularity of the lime stone powder is 0.01mm-2mm.

4. a kind of method of oxygen coverter high pressure blow smelting operation agstone slag making dephosphorization according to claim 1, feature exist In the molten iron container is one of converter, ladle, corundum crucible, vaccum sensitive stove.

5. a kind of method of oxygen coverter high pressure blow smelting operation agstone slag making dephosphorization according to claim 1, feature exist In the carrier gas is N₂, one of Ar, Ne, Kr or a variety of.

6. a kind of method of oxygen coverter high pressure blow smelting operation agstone slag making dephosphorization according to claim 1, feature exist In the material of the nozzle of the oxygen rifle is metal material or material one kind that high temperature resistant corrodes.

7. a kind of method of oxygen coverter high pressure blow smelting operation agstone slag making dephosphorization according to claim 1, feature exist In the mode of the lime stone blowing is one of bottom blowing, top blast, side-blown or a variety of.