CN115219376A - A kind of blast furnace smelting coke adaptability test and analysis method - Google Patents

Abstract

The invention discloses a method for testing and analyzing the adaptability of blast furnace smelting coke. The specific testing steps are as follows: industrial analysis of coke. The standard specifies the method for determining the total moisture, air-drying moisture, ash content and volatile content of coke and the calculation of fixed carbon. Method: For the mechanical strength of coke, take coke with a certain mass and particle size greater than 40mm, put it into a rotating drum equipment, and sieve the coke with a certain particle size for crush resistance test; coke reactivity, coke reactivity refers to coke and carbon dioxide. The ability of chemical reactions such as oxygen and water vapor to carry out chemical reactions, take an appropriate amount of sample and put it into the reactor, and take the mass loss of the sample as the reactivity result; the post-reaction strength of coke, the post-reaction strength of coke refers to the mechanical The ability to resist fragmentation and wear under the action of force and thermal stress, the reacted coke is co-rotated with an I-type drum, and the sample is taken out for sieving, weighing and recording, and the mass percentage is the strength after the reaction.

Description

A kind of blast furnace smelting coke adaptability test and analysis method

technical field

The invention relates to the field of coke testing in the steelmaking industry, in particular to a method for testing and analyzing the adaptability of blast furnace smelting coke.

Background technique

With the large-scale blast furnace and the improvement of the equipment level, the long-term stability of the blast furnace is very important. The three important factors affecting the forward running of the blast furnace are the quality of coke, the properties of iron-containing raw materials and the operation of the blast furnace, among which the quality of coke has the greatest impact on the forward running of the blast furnace. Coke is an essential raw material for blast furnace smelting, and the support of coke skeleton is a prerequisite for achieving stable and smooth blast furnace smelting. After the blast furnace is injected with coal, the coke ratio decreases, and the coke deterioration in the blast furnace aggravates the performance of the coke, which has a more prominent impact on the blast furnace smelting. With the development of large-scale blast furnaces and enhanced smelting technology, it is always the coke workers' demand to continuously improve the quality of coke to meet the quality requirements of blast furnace smelting.

Based on the existing blast furnace production conditions of Delong Iron and Steel, inspect and master the parameters such as iron-containing raw materials and coke physical and chemical characteristics commonly used in blast furnace production, and preliminarily analyze the corresponding laws of raw material incoming grade, coke quality and blast furnace indicators combined with blast furnace production data. ; Then analyze the microstructure of coke from different sources commonly used by Delonghi, master its microcrystalline structure, functional group type, microscopic morphology and optical structure, and analyze the internal relationship between the coke microstructure and macroscopic mechanical properties; The process of melting zone erosion and slag passing through coke behavior are analyzed and studied, the analysis and characterization of primary slag formation of different grades of charge structure, the analysis of coke erosion process of slag corresponding to different grades of charge structure, and the retention behavior of different components of slag in different quality cokes, to obtain coke The thermal erosion process parameters under different grades of charge structure; finally, based on the above data, the adaptability of different quality raw materials and coke is analyzed, and the impact of improving the quality of raw materials on blast furnace smelting based on the quality of existing coke and the impact of improving the quality of raw materials on blast furnace smelting is obtained. The influence of air temperature and large coal injection on blast furnace smelting, and the influence of raw material quality and coke selection on cost under two operating modes are given. Therefore, we propose a blast furnace smelting coke adaptability test and analysis method to solve the above problems.

SUMMARY OF THE INVENTION

In order to overcome the deficiencies of the prior art, the purpose of the present invention is to investigate the microscopic morphology and optical structure of cokes of different qualities, to study the corresponding relationship between the microstructures and macroscopic properties of cokes of different qualities, and to prove the reactivity and strength of cokes after reaction. The correlation between isotropy and anisotropy structure of coke provides a theoretical basis for the selection of blast furnace coke raw materials. The comprehensive matching system provides a theoretical basis for the operation synergy of different quality raw materials and different quality cokes.

The above-mentioned technical purpose of the present invention is achieved through the following technical solutions:

A method for testing and analyzing the adaptability of blast furnace smelting coke, including testing the coke quality one by one, wherein the coke industry analyzes, the mechanical strength of the coke, the reactivity of the coke and the strength after the reaction of the coke.

Further, the specific test steps are as follows:

Step 1: Industrial analysis of coke, the standard specifies the method of determination of total moisture of coke, air-drying base moisture, ash content, volatile matter and calculation method of fixed carbon;

Step 2: For the mechanical strength of coke, take coke with a certain mass and particle size greater than 40mm, put it into a rotating drum equipment, and sieve the coke with a certain particle size for crush resistance test;

Step 3: Reactivity of coke, coke reactivity refers to the ability of coke to chemically react with carbon dioxide, oxygen and water vapor. Take an appropriate amount of sample and put it into the reactor, and react with CO2 at a temperature of 1100±5℃ , after 2h, take the mass loss of the sample as the reactivity result;

Step 4: The post-reaction strength of the coke. The post-reaction strength of the coke refers to the ability of the reacted coke to resist fragmentation and wear under the action of mechanical force and thermal stress. It is 20r/min for 30min. After the revolution reaches 600, the sample is taken out for sieving, weighing and recording. The mass percentage of the part with particle size exceeding 10mm is the strength after reaction.

Further, the second step: the mechanical strength of the coke, the moisture content of the coke is tested: a coke sample of a certain quality is weighed, placed in a drying oven, and dried at a certain temperature until the quality is constant, and the mass loss of the coke sample is measured. Calculate the percentage of moisture.

Further, the second step: mechanical strength of coke, ash content: weigh a coke sample of a certain quality, ashing at 825 ° C, and use the percentage of the residue quality in the coke sample as the ash content. .

Further, the second step: mechanical strength of coke, volatile matter content: weigh a coke sample of a certain quality, place it in a crucible with a lid, and at (900±10) ℃, isolate the air and add it for 7 minutes to reduce the amount of coke. The mass of the sample is the percentage of the mass of the sample minus the moisture content of the sample as the volatile content.

Further, described step 2: mechanical strength of coke, fixed carbon content: calculate with the measured moisture content, ash content, and volatile matter content, find out the coke fixed carbon content, and calculate according to formula (3-2):

FCad=100-Mad-Aad-Vad (3-2)

In formula (3-2): FCad - fixed carbon content % of coke analysis sample; Mad - moisture content % of coke analysis sample; Aad - ash content % of coke analysis sample; Vad - volatilization of coke analysis sample Content %.

Further, in the step 2: in the mechanical strength of the coke, the speed of the sieving drum is 25 rpm, and it is automatically stopped after rotating for 100 revolutions to remove the coke, and sieve with a sample sieve with an aperture of 25 mm and 10 mm, with a particle size greater than 25 mm. The proportion of coke is used as the crushing strength of the conversation, and the proportion of coke with a particle size of less than 10mm is used as the wear resistance of the coke.

Further, described step 3: the calculation formula of the reactivity of coke is as follows:

CRI=(m-m1)/m×100%

In the formula: CRI-coke reactivity, %; m-coke sample mass, g; m1-residual coke mass after reaction, g.

Further, the step 4: the post-reaction strength of the coke, the formula for calculating the post-reaction strength of the coke:

CSR=m2/m1×100%

In the formula: CSR - coke strength after reaction, %; m2 - mass of coke with a particle size greater than 10 mm after drumming, g; m1 - residual coke mass after reaction, g.

To sum up, the present invention has the following beneficial effects:

Through industrial analysis of coke, the mechanical strength of coke, the reactivity of coke and the strength after reaction of coke are tested one by one for the quality of coke below. . Therefore, selecting appropriate coke economic indicators and maintaining stable coke quality can reduce the fluctuation of blast furnaces and achieve long-term stability.

Description of drawings

Fig. 1 is coke microstructure and macroscopic performance test result table in a kind of blast furnace smelting coke adaptability test analysis method of the present invention;

FIG. 2 is a graph showing the relationship between the coarse-grained mosaic structure and thermal properties in a method for testing and analyzing the adaptability of blast furnace smelting coke according to the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

In a preferred embodiment of the present invention, a method for testing and analyzing the adaptability of blast furnace smelting coke includes: testing the quality of the coke below one by one, wherein the industrial analysis of the coke, the mechanical strength of the coke, the reactivity of the coke and the strength after the reaction of the coke, The specific test steps are as follows:

Step 1: Analysis of coke industry

This standard specifies the determination methods of coke total moisture, air-drying moisture, ash content and volatile matter and the calculation method of fixed carbon.

Moisture content: Weigh a certain mass of coke samples, place them in a drying oven, and dry them at a certain temperature until the mass is constant. Calculate the percentage of moisture by the mass loss of the coke samples.

Ash content: Weigh a certain quality of coke sample, ashing at 825 ° C, and take the percentage of the residue mass in the coke sample as the ash content,

Volatile matter content: Weigh a certain mass of coke sample, place it in a crucible with a lid, add it for 7 minutes at (900±10) ℃, isolate the air, and subtract the sample from the percentage of the reduced mass in the sample mass The moisture content is taken as the volatile content,

Fixed carbon content: Calculate with the measured moisture content, ash content, and volatile content to find out the coke fixed carbon content, and calculate according to formula (3-2):

FCad=100-Mad-Aad-Vad (3-2)

In formula (3-2): FCad - fixed carbon content % of coke analysis sample; Mad - moisture content % of coke analysis sample; Aad - ash content % of coke analysis sample; Vad - volatilization of coke analysis sample Content %;

Step 2: Mechanical strength of coke

Take a certain mass of coke with a particle size larger than 40mm, put it into the drum equipment, set the drum speed to 25rpm, automatically stop after 100 revolutions, remove the coke, and sieve it with a sample sieve with an aperture of 25mm and 10mm. The proportion of coke with a particle size greater than 25mm is used as the crushing strength of the conversation, and the proportion of coke with a particle size of less than 10mm is used as the wear resistance of the coke;

Step 3: Reactivity of Coke

The reactivity of coke refers to the ability of coke to chemically react with carbon dioxide, oxygen and water vapor. Take an appropriate amount of sample and put it into the reactor, and react with CO2 at a temperature of 1100±5℃. After 2 hours, take the mass of the sample. Losses are the result of reactivity, and coke reactivity is calculated as:

CRI=(m-m1)m×100%

In the formula: CRI-coke reactivity, %; m-coke sample mass, g; m1-residual coke mass after reaction, g;

Step 4: Post-reaction strength of coke

The strength of the coke after reaction refers to the ability of the reacted coke to resist fragmentation and wear under the action of mechanical force and thermal stress. After the number of revolutions reaches 600, the sample is taken out for sieving, weighing and recording. The mass percentage of the part with a particle size exceeding 10 mm is the strength after reaction. The strength of coke after reaction is calculated according to the formula:

CSR=m2/m1×100%

In the formula: CSR - strength of coke after reaction, %; m2 - mass of coke with a particle size greater than 10 mm after drumming, g; m1 - mass of residual coke after reaction, g;

Preliminary analysis of the corresponding law of raw material entering furnace grade, coke quality and blast furnace index

(1) Blast furnace ironmaking is based on concentrate, and the influence rate of concentrate on blast furnace indicators is about 70%. The content of ironmaking refining technology is: high, cooked, stable, uniform, small, clean, less, and good. Eight aspects, each with specific requirements,

The high grade of ore into the furnace is the core of the concentrate technology. The grade of ore into the furnace is increased by 1%, the coke ratio is reduced by 1.5%, the output is increased by 2.5%, the amount of iron slag per ton is reduced by 30kg, and more coal powder is allowed to be injected by 15kg. The effective method for iron-containing grade is to use more lump ore and pellets with high iron-containing grade. The iron-containing grade of imported iron ore is higher than that of domestic ores, which promotes the improvement of iron-containing grade of the ore entering the furnace.

The proportion of clinker (sinter and pellets) is higher. When the clinker ratio is increased by 1%, the iron-making fuel ratio will decrease by 0.4% to 0.5%. It is hoped that the clinker ratio should not be lower than 80%,

The quality and supply quantity of the raw fuel into the furnace should be stable, and the fluctuation of iron content should be ±<0.5%, the fluctuation of basicity should be ±<0.08 (times), the pass rate should be greater than 90%, and the fluctuation of FeO of sintered ore should be 1%, which affects the fuel ratio by 1%. ～1.5%, and the output fluctuates by 1%～1.5%, which will also affect the reducibility and reflow performance of the sinter; the sinter basicity is below 1.2, and the fluctuation is 1%, which will affect the coke ratio and output by 3%～5%,

The particle size of the raw fuel entering the furnace should be uniform, and the particle size of 20-40mm should account for more than 80%. The particle size of the raw fuel entering the furnace should be small. Increasing the specific surface area of the charge can speed up the reaction speed, improve the gas utilization rate, and reduce the fuel ratio and production. cost purpose,

The raw fuel entering the furnace should be clean, the particle size is less than 5mm, accounting for less than 5% of the total, and the particle size of 5-10mm accounts for less than 30% of the total. The blast furnace is difficult to operate, the coal injection ratio decreases, the powder content of the charge increases by 1%, the fuel ratio increases by about 0.5%, and the output decreases by 0.5% to 1.0%.

The raw fuel entering the furnace contains less harmful impurities, and the blast furnace bag dust contains high alkali metals, so do not return to the sintering process, and do not allow it to be recycled and enriched. The destructive effect of K on the charge and refractory is greater than that of Na. At present, the high content of harmful impurities in the charge has seriously threatened the longevity of the blast furnace; after a batch of blast furnaces used inferior ore, the temperature difference of the hearth water was high, and they were forced to overhaul in advance, and some burn-through phenomenon occurred. ,

The metallurgical properties of iron ore are better: the metallurgical properties of high reducing iron ore are better: high reducibility (>60%), high soft melting temperature (above 1200 ° C), narrow soft melting temperature range (100 ~ 150 ° C), low temperature reduction The pulverization rate and expansion rate should be low (primary <15%, secondary <20%), etc. The reflow performance of the charge seriously affects the shape and gas permeability of the blast furnace reflow zone, and affects the blast furnace operation index. Sintering in the blast furnace When the direct reduction degree of ore increases by 10%, the fuel ratio will increase by 8% to 9%, and the output will decrease by 8% to 9%;

(2) The higher the fixed carbon content in the coke, the more heat and reducing agent provided by the coke, the lower the coke ash content, the less blast furnace slag content, and the different expansion of ash content and coke. There will be cracks around, which will reduce the strength of the coke. In addition, the lower the volatile content of the coke, the lower the moisture content of the coke, the lower the content of harmful elements such as sulfur and phosphorus, the smaller the side effect of coke on blast furnace smelting.

It is required that the coke particle size is uniform and the average particle size is kept at the level of 40-50mm. The large particle size coke is easily broken in the furnace, which produces more powder, which deteriorates the gas permeability of the charge and increases the pressure difference of the blast furnace. As a result, the air volume has to be reduced, resulting in output. decrease, the focal ratio increases.

Generally, the crushing strength M40 and wear resistance M10 of coke are used as the index to measure the mechanical strength of coke in cold state, and M40 is required to be high, which reflects the crack condition of coke, that is, the resistance to mechanical impact, and the ability of coke to maintain lump in blast furnace. It is closely related, and M10 is required to be low, which reflects the coke body strength of coke, that is, the wear resistance of coke, which is closely related to the pulverization performance of coke in blast furnace. The mechanical strength of coke in cold state determines the air permeability of the block belt in the blast furnace. The degree of anterograde nature and furnace conditions.

The microstructural composition of coke is divided into two categories, namely optical isotropy (including isotropy, silk-like carbon and fragments) and optical anisotropy (including fine-grain mosaic, coarse-grain mosaic, flow-like structure, flakes). Its content directly affects the reactivity and post-reaction strength of coke.

From the perspective of microstructure, the optically isotropic structure belongs to the disordered arrangement of carbon chains. There are many defects in the structure and more active sites for reacting with CO2, so the rate of reaction with CO2 is higher, and the carbon-soluble reaction has a higher rate of coke microstructure. The damage is relatively serious; the optical anisotropy structure belongs to the ordered arrangement of carbon chains, and there are few defects in the structure and active sites for reacting with CO2. The post-reaction strength (CSR) of coke with well-developed structure was higher, and the coke reactivity (CRI) was higher with well-developed anisotropy.

The order of influence on reactivity (CRI) is: isotropy > silk carbon and fragment > mosaic structure > fiber structure > flake. In addition, the optical structure of coke also has an important influence on its strength, and high-quality coke contains a lot of mosaic structure , the content of fibrous tissue is less.

As can be seen from the test results of coke microstructure and macroscopic properties as shown in Fig. 1, Pengfei coke, Xuyang CDQ coke and Sinosteel resource coke with higher content of isotropic fragment structure have higher reactivity of corresponding coke; The higher content of structure (fine particle + medium particle + coarse particle) is Donghui resource coke and Huafeng CDQ coke, and the corresponding coke reaction strength is also higher.

At the same time, according to the summary of the production data of coking, the mosaic structure in the coke microstructure has the most obvious influence on the thermal performance, and the corresponding relationship is shown in Figure 2.

Therefore, coke with less isotropic structure content and more mosaic structure content, and control the mosaic structure in the coke microstructure to be greater than 50%, this structure is beneficial to reduce the reactivity and improve the strength after reaction.

The basic principles and main features of the present invention and the advantages of the present invention have been shown and described above. Those skilled in the art should understand that the present invention is not limited by the above-mentioned embodiments, and the descriptions in the above-mentioned embodiments and the description are only to illustrate the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have Various changes and modifications fall within the scope of the claimed invention. The claimed scope of the present invention is defined by the appended claims and their equivalents.

Claims (9)

1. a blast furnace smelting coke adaptability test analysis method is characterized in that: one by one coke quality is tested, wherein coke industrial analysis, the mechanical strength of coke, the reactivity of coke and the strength after reaction of coke. 2. a kind of blast furnace smelting coke adaptability test analysis method according to claim 1, is characterized in that: described concrete test step is as follows: Step 1: Industrial analysis of coke, the standard specifies the method of determination of total moisture of coke, air-drying base moisture, ash content, volatile matter and calculation method of fixed carbon; Step 2: For the mechanical strength of coke, take coke with a certain mass and particle size greater than 40mm, put it into a rotating drum equipment, and sieve the coke with a certain particle size for crush resistance test; Step 3: Reactivity of coke, coke reactivity refers to the ability of coke to chemically react with carbon dioxide, oxygen and water vapor. Take an appropriate amount of sample and put it into the reactor, and react with CO2 at a temperature of 1100±5℃ , after 2h, take the mass loss of the sample as the reactivity result; Step 4: The post-reaction strength of the coke. The post-reaction strength of the coke refers to the ability of the reacted coke to resist fragmentation and wear under the action of mechanical force and thermal stress. It is 20r/min for 30min. After the revolution reaches 600, the sample is taken out for sieving, weighing and recording. The mass percentage of the part with particle size exceeding 10mm is the strength after reaction. 3. a kind of blast furnace smelting coke adaptability test analysis method according to claim 2, it is characterized in that: described step 2: the mechanical strength of coke, test the moisture content of coke: take a coke sample of a certain quality, put In a drying oven, it is dried at a certain temperature until the mass is constant, and the moisture content is calculated by the mass loss of the coke sample. 4. a kind of blast furnace smelting coke adaptability test analysis method according to claim 3, is characterized in that: described step 2: the mechanical strength of coke, ash content: take by weighing the coke sample of certain quality, at 825 ℃ For ashing, the ash content is taken as the percentage of the mass of the residue in the road of the coke sample. 5. a kind of blast furnace smelting coke adaptability test analysis method according to claim 4, is characterized in that: described step 2: mechanical strength of coke, volatile matter content: take by weighing a certain quality of coke sample, place it on a belt In the covered crucible, at (900 ± 10) ℃, isolated from air, add for 7 minutes, and take the reduced mass as a percentage of the sample mass minus the moisture content of the sample as the volatile content. 6. a kind of blast furnace smelting coke adaptability test analysis method according to claim 5, is characterized in that: described step 2: the mechanical strength of coke, fixed carbon content: use the measured moisture content, ash content, volatilization According to formula (3-2), calculate according to formula (3-2): FC _ad = 100-M _ad -V _ad -V _ad (3-2) In formula (3-2): FCad - fixed carbon content % of coke analysis sample; Mad - moisture content % of coke analysis sample; Aad - ash content % of coke analysis sample; Vad - volatilization of coke analysis sample Content %. 7. a kind of blast furnace smelting coke adaptability test analysis method according to claim 2, is characterized in that: described step 2: in the mechanical strength of coke, the screening drum speed is 25rpm, and automatically stops after rotating 100 revolutions , remove the coke, sieve with a sample sieve with an aperture of 25mm and 10mm, take the proportion of coke with a particle size greater than 25mm as the crushing strength of the conversation, and take the proportion of coke with a particle size of less than 10mm as the wear resistance of the coke. 8. a kind of blast furnace smelting coke adaptability test analysis method according to claim 2, is characterized in that: described step 3: the calculation formula of the reactivity of coke is as follows: CRI=(mm ₁ )/m×100% In the formula: CRI-coke reactivity, %; m-coke sample mass, g; m1-residual coke mass after reaction, g. 9. a kind of blast furnace smelting coke adaptability test analysis method according to claim 2, is characterized in that: described step 4: the strength after the reaction of the coke, the strength calculation formula after the reaction of the coke: CSR=m ₂ /m ₁ ×100% In the formula: CSR - coke strength after reaction, %; m2 - mass of coke with a particle size greater than 10 mm after drumming, g; m1 - residual coke mass after reaction, g.

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