Chain grate machine-rotary kiln oxidized pellet production process evaluation method

Abstract

Aiming at the lack of comprehensive evaluation on the whole pellet production process in the prior art, the invention mainly aims to provide the grate-rotary kiln oxidized pellet production process evaluation method. The method comprises the following steps: 1) respectively carrying out uniformity calculation of evaluation characteristic parameters on a plurality of samples in each pellet production process; 2) performing weight assignment on the influence intensity of the pellet production single process according to each evaluation characteristic parameter, and evaluating the uniformity of the pellet production single process by adopting a uniformity index; and 3) carrying out weight assignment on the influence strength of each evaluation characteristic parameter on the whole pellet production process, and evaluating the raw material characteristics and the pellet quality uniformity of the whole grate-rotary kiln oxidized pellet production process by adopting a uniformity index. According to the method, systematic, scientific and comprehensive evaluation on the uniformity of the whole pellet production process can be realized, quality improvement and consumption reduction of the pellet production process are promoted, and the method has important significance on evaluation of the pellet production process flow.

Description

Technical Field

[0001] The invention belongs to the technical field of iron and steel metallurgical pelletizing process, and in particular relates to a method for evaluating the production process of chain grate-rotary kiln oxidation pelletizing. Background Art

[0002] In the field of domestic sintering and pelletizing, compared with sintering, pelletizing has the characteristics of low energy consumption and low carbon emission. The steel industry is developing towards high efficiency, low carbonization and decarbonization, and pelletizing also has a broad development prospect. In the development of pelletizing, the quality improvement, production increase and consumption reduction of the entire process also play a vital role in the domestic mainstream long process ironmaking process.

[0003] In the field of pellet production, it is very important to ensure the uniformity of the pellet production process. In the process of material mixing, whether the material is mixed evenly or not is directly related to the subsequent pelletizing process. Therefore, pelletizing plants at home and abroad are currently equipped with powerful mixers to enhance the material mixing effect, make the subsequent green ball quality and composition more uniform, and reduce the volatility of the subsequent preheating and roasting process.

[0004] At present, the evaluation of the production process of pellets often requires consideration of multiple factors, such as raw material composition, mixing process, etc. There is currently a lack of a comprehensive evaluation system for pellets in China. The existing evaluation methods include: Based on the analysis of the chemical composition, physical properties and metallurgical properties of belt roaster pellets, a comprehensive evaluation method for pellets based on principal component analysis is proposed. This method uses multivariate statistics to calculate the comprehensive quality characteristic index, comprehensive melting characteristic index and comprehensive softening characteristic index to comprehensively evaluate the pellets. The above method is not comprehensive in the evaluation of the pellet production process. The comprehensive evaluation method is limited to the evaluation of some indicators of the pellets, and does not evaluate other production processes of the pellets, or even the entire production process of the pellets. Therefore, there are certain limitations, and the evaluation method cannot fully and accurately describe the entire production process. Summary of the invention

[0005] The main purpose of the present invention is to provide a method for evaluating the production process of chain grate-rotary kiln oxidized pellets, in view of the lack of comprehensive evaluation of the entire production process of chain grate-rotary kiln oxidized pellets in the prior art. The present invention intends to systematically consider the entire pellet production process, first evaluate the characteristics of each link separately, and construct a method for evaluating the entire pellet production process based on independent links. This method can achieve a systematic, scientific and comprehensive evaluation of the uniformity of the entire production process of chain grate-rotary kiln oxidized pellets, which is conducive to promoting the quality improvement and consumption reduction of the pellet production process, and is of great significance to the evaluation of the pellet production process.

[0006] In order to achieve the above technical purpose, the present invention provides a method for evaluating the production process of chain grate-rotary kiln oxidation pellets, wherein the production process is divided into a raw material mixing process, a pelletizing process, a preheating process and a roasting process, and the method comprises the following steps:

[0007] 1) The evaluation characteristic parameters of several samples of each pellet production process are measured and data are obtained. The evaluation characteristic parameters include TFe content, FeO content, moisture content and raw material particle size of the raw material mixing process; TFe content, FeO content, green ball falling strength and green ball compressive strength of the raw ball for the pelletizing process; TFe content, FeO content and preheated ball compressive strength of the preheated ball for the preheating process; TFe content, FeO content and preheated ball compressive strength of the calcined ball for the calcining process;

[0008] 2) Assign weights according to the influence intensity of each evaluation characteristic parameter on the pelletizing production process, and use the uniformity index of each evaluation characteristic parameter of the pelletizing production process to evaluate the uniformity of the raw material characteristics or pellet quality of the pelletizing production process;

[0009] 3) Weights were assigned according to the intensity of the impact of a single pellet production process on the entire pellet production process, and the uniformity index was used to evaluate the comprehensive uniformity of the entire grate-rotary kiln oxidation pellet production process.

[0010] In a preferred embodiment, in step 1), when calculating the uniformity of the evaluation characteristic parameter, the number of samples taken is not less than 10.

[0011] In a preferred embodiment, in step 2), the method for weighting the impact intensity of each evaluation characteristic parameter on the pellet production process is:

[0012] 2.1) For the raw material mixing process, the weights of the TFe content, FeO content, moisture content and particle size of the raw materials on the raw material mixing process are set to 10-20%, 20-30%, 30-35% and 20-25% respectively, and the sum of the four weight values ​​is 100%; because there is a significant difference in the FeO content of magnetite and hematite with the same TFe content, the uniformity of the FeO content of the raw material can better reflect the effect of raw material mixing, so its weight assignment is higher than TFe; the uniformity of moisture content will seriously affect the stability of the ball-making process, so its weight assignment is larger;

[0013] 2.2) For the pelletizing process, the weights of the TFe content, FeO content, moisture content, drop strength and compressive strength of the green balls on the pelletizing process are set to 10-15%, 20-25%, 20-25%, 15-20% and 15-20% respectively, and the sum of the five weight values ​​is 100%; because there are obvious differences in the FeO content of magnetite and hematite with the same TFe content, the uniformity of the FeO content in different green balls can better reflect the uniformity of the pellet composition, so its weight assignment is higher than that of TFe; the uniformity of moisture content will seriously affect the bursting performance of the pellet, so its weight assignment is also relatively high;

[0014] 2.3) For the preheating process, the weights of the TFe content, FeO content and compressive strength of the preheating balls on the preheating process are set to 20-25%, 35-40% and 35-40% respectively, and the sum of the three weights is 100%; due to the obvious difference in FeO content of hematite and magnetite of the same grade, the uniformity of FeO content in different preheating balls can better reflect the uniformity of the composition of the preheating balls, so its weight assignment is higher than TFe; because the uniformity of the compressive strength of the preheating balls has an important influence on their crushing and powder removal characteristics during the rotary kiln roasting process, its weight assignment is also relatively high;

[0015] 2.4) For the roasting process, the weights of the TFe content, FeO content and compressive strength of the roasted balls on the roasting process are set to 20-25%, 35-40%, and 35-40%, respectively, and the sum of the three weight values ​​is 100%. As above, whether the FeO content of a single roasted ball is uniform can better reflect the uniformity of the composition of the finished pellets, so its weight assignment is higher than that of TFe; the uniformity of the strength of a single roasted ball is directly related to its effect in the subsequent blast furnace smelting process, so its weight assignment is also relatively high.

[0016] Preferably, in step 2), the calculation process of the uniformity index comprises the following steps:

[0017] ① Calculate the average value of a certain evaluation characteristic parameter:

[0018]

[0019] Among them, μ is the average value of a certain evaluation characteristic parameter; X i is the value of a certain evaluation characteristic parameter measured for each sample; n is the number of selected samples;

[0020] ② Use the average value of a certain evaluation characteristic parameter obtained in step ① to calculate the standard deviation σ of the corresponding evaluation characteristic parameter:

[0021]

[0022] ③ Use the average value of a certain evaluation characteristic parameter obtained in step ① and the standard deviation of a corresponding evaluation characteristic parameter obtained in step ② to calculate the dispersion coefficient CV of a corresponding evaluation characteristic parameter:

[0023] CV=σ / μ

[0024] ④ Use the discrete coefficient CV corresponding to a certain evaluation characteristic parameter obtained in step ③ to calculate the uniformity index M of the pellet production process corresponding to a certain evaluation characteristic parameter i :

[0025] M i =(1-CV)×100%

[0026] ⑤Use the uniformity index M corresponding to a certain evaluation characteristic parameter obtained in step ④ i As well as the weight of each evaluation characteristic parameter on the pelletizing production process, the uniformity index M of the pelletizing production process is calculated. j :

[0027] M j =∑(M i *ω i )

[0028] Among them, ω i It is the weight value of the influence of a certain evaluation characteristic parameter on a certain pellet production process.

[0029] In a preferred embodiment, in the step 3), the method of weighting the influence intensity of each evaluation characteristic parameter on the whole process of pellet production is as follows: the influence weights of the raw material mixing process, the pelletizing process, the preheating process and the roasting process on the whole process of chain grate-rotary kiln oxidation pellet production are 30-35%, 20-25%, 25-30% and 10-20% respectively, and the sum of the four weight values ​​is 100%; because the mixing process of pellet raw materials is the first link of the whole pellet preparation process, the uniformity of physical and chemical properties has an important influence on the quality of finished pellets, so its weight assignment is the highest, and the rotary kiln used in the pellet roasting process has the function of adjusting the uniformity of pellet quality, and the influence of this process on the uniformity of pellet quality in the whole pellet production process is relatively small, so its weight assignment is relatively low.

[0030] Preferably, in step 3), the calculation process of the uniformity index is:

[0031] The uniformity index M of the pellet production process obtained in step 2) is used j As well as the weight value of the impact of the single pellet production process on the whole pellet production process, the comprehensive uniformity index M of the whole process of chain grate-rotary kiln oxidation pellet production is calculated:

[0032] M=∑(M j *ω j )

[0033] Among them, ω j It is the weight value of the impact of each pelletizing production process on the whole pelletizing production process.

[0034] In a preferred embodiment, the calculation formula of the uniformity index is applicable to the entire production process of chain grate-rotary kiln oxidation pellets.

[0035] In a preferred embodiment, the calculation process formula of the uniformity index is applicable to all evaluation characteristic parameters in the pellet production process: namely, TFe content, FeO content, raw material moisture content, raw material particle size, green ball falling strength, green ball compressive strength, preheated ball compressive strength and roasted ball compressive strength.

[0036] In a preferred embodiment, the relationship between the uniformity index M and the uniformity of the entire process of grate-rotary kiln oxidation pellet production is:

[0037] If M≥90%, the material properties and pellet quality uniformity of the production process are excellent;

[0038] If 80%≤M<90%, the material characteristics of the production process and the uniformity of the pellet quality are good;

[0039] If 60%≤M<80%, the material characteristics of the production process and the uniformity of the pellet quality are medium;

[0040] If M is less than 60%, the material properties and pellet quality uniformity of the production process will be poor.

[0041] According to a preferred solution, if the uniformity index M is less than 80%, the uniformity of the production process is medium. In the chain grate-rotary kiln oxidation pellet production process, the raw material mixing process can be strengthened, such as by adjusting the speed and time of the high-power mixer to enhance the uniformity of the pellet production process. The pelletizing process can also be strengthened, such as by adjusting the speed, inclination, and feeding speed of the disc pelletizing machine.

[0042] Compared with the prior art, the main innovations of the present invention are:

[0043] (1) The present invention constructs a uniformity model for each evaluation characteristic parameter in a single pellet production process, and determines a dimensionless uniformity index to evaluate the uniformity of each characteristic parameter in a single pellet production link, which helps to identify the key issues in a single pellet production link.

[0044] (2) The present invention calculates the uniformity of a single pelletizing production process by comparing the influence weights of each evaluation characteristic parameter in a single pelletizing production process with its uniformity index, thereby achieving a uniformity comparison between the pelletizing production processes, which helps to find the key links that affect the uniformity of the entire process of chain grate-rotary kiln oxidation pelletizing production.

[0045] (3) The present invention calculates the uniformity of the entire chain grate-rotary kiln oxidation pellet production process through the influence weights of each process in the pellet production process and its uniformity index, thereby achieving a comprehensive evaluation of the entire pellet production process, which helps to improve the quality of the pellet production process and thus reduce production costs and energy consumption. DETAILED DESCRIPTION

[0046] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and carefully in combination with preferred embodiments below, but the protection scope of the present invention is not limited to the following specific embodiments.

[0047] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The patent terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0048] Example 1

[0049] The iron concentrate was sampled before and after the pelletizing process, and the TFe content, FeO content, moisture content and particle size of the samples in each process were measured. The uniformity M of each parameter was calculated according to formulas (1) to (4). i The calculation results are shown in Table 1. Similarly, the green balls were sampled to determine the TFe content, FeO content, drop strength and compressive strength of the green balls, and the uniformity M of each parameter of the green balls was calculated. i The results are shown in Table 2 below; the preheated balls were sampled, the TFe content, FeO content and compressive strength of the preheated balls were determined, and the uniformity M of each parameter of the preheated balls was calculated. i The results are shown in Table 3 below; the calcined balls were sampled, the TFe content, FeO content and compressive strength of the calcined balls were determined, and the uniformity M of the parameters of the calcined balls was calculated. i The results are shown in Table 4. The uniformity M of the four pellet production processes is calculated based on the weight ratio of each evaluation parameter and formula (5): j The comprehensive uniformity M of the entire pelletizing production process is calculated by the weights of the four pelletizing processes in the total pelletizing production process and formula (6) as shown in Table 5 below.

[0050]

[0051]

[0052] CV=σ / μ (3)

[0053] M i =(1-CV)×100% (4)

[0054] M j =∑(M i *ω i ) (5)

[0055] M=∑(M j *ω j ) (6)

[0056] Table 1 Homogeneity of pellet raw material mixing process

[0057]

[0058] Table 2 Uniformity of pelletizing process

[0059]

[0060] Table 3 Uniformity of pellet preheating process

[0061]

[0062] Table 4 Pellet roasting process uniformity

[0063]

[0064]

[0065] Table 5. Uniformity of the whole process of pellet production

[0066]

[0067] Example 2

[0068] The iron concentrate was sampled before and after the pelletizing process, and the TFe content, FeO content, moisture content and particle size of the samples in each process were measured. The uniformity M of each parameter was calculated according to formulas (1) to (4). i The calculation results are shown in Table 6 below. Similarly, the green balls were sampled to measure the TFe content, FeO content, drop strength and compressive strength of the green balls, and the uniformity M of each parameter of the green balls was calculated. i The results are shown in Table 7 below; the preheated balls were sampled, the TFe content, FeO content and compressive strength of the preheated balls were determined, and the uniformity M of each parameter of the preheated balls was calculated. i The results are shown in Table 8 below; the calcined balls were sampled, the TFe content, FeO content and compressive strength of the calcined balls were determined, and the uniformity M of the parameters of the calcined balls was calculated. iThe results are shown in Table 9. The uniformity M of the four pellet production processes is calculated based on the weight ratio of each evaluation parameter and formula (5): j The comprehensive uniformity M of the entire pelletizing production process is calculated by the weights of the four pelletizing processes in the total pelletizing production process and formula (6) as shown in Table 10 below.

[0069] Table 6 Homogeneity of pellet raw material mixing process

[0070]

[0071] Table 7 Uniformity of pelletizing process

[0072]

[0073] Table 8 Uniformity of pellet preheating process

[0074]

[0075] Table 9 Pellet roasting process uniformity

[0076]

[0077] Table 10 Uniformity of the whole process of pellet production

[0078]

[0079] Comparative Example 1

[0080] Using the materials and production process of Example 1, the iron concentrate was sampled before and after the pellet production mixing process, and the TFe content of the samples in each process was measured, and the uniformity M was calculated according to formulas (1) to (4). i Similarly, take samples of green balls, measure the TFe content of green balls, and calculate the uniformity M of green balls. i ; Sample the preheated ball, determine the TFe content of the preheated ball, and calculate the uniformity M of the preheated ball i ; Sampling the calcined balls, determining the TFe content of the calcined balls, and calculating the uniformity M of the calcined balls i According to the weight of each pellet production process in the total production process, the comprehensive uniformity M of the entire pellet production process is calculated. The above results are shown in Table 11 below.

[0081] Table 11 Uniformity of pellet production process

[0082] Pellet production process Uniformity Index Before strong mixing 97.60 After strong mixing 98.91 Ball making process 97.74 Warm-up process 92.57 Roasting process 89.00 Pellet production process 96.67

[0083] in conclusion

[0084] It can be concluded from the embodiments and comparative examples that only the uniformity of the TFe content in the pellet production process is not enough to reveal the uniformity of the entire process of chain grate-rotary kiln oxidation pellet production. This indicator is relatively one-sided, and it can be concluded from the embodiments that the uniformity of the FeO content is most significantly improved in the raw material mixing stage. Therefore, it can be considered that the uniformity of the FeO content has a greater impact on the pellet production process, while the conventional evaluation method of the comparative example cannot know the impact of the uniformity of the FeO content on the pellet production process. Therefore, the chain grate-rotary kiln oxidation pellet production process evaluation method of the present invention is based on each indicator of each pellet production stage, and more comprehensively judges the uniformity of the pellet production process, and reveals that the links that have a greater impact on the uniformity of the entire process of chain grate-rotary kiln oxidation pellet production are the raw material mixing process and the pelletizing process, and explains that the factors that have a greater impact on the uniformity of pellet performance in the pellet production process are the FeO content and the raw material moisture content, which provides a direction for subsequent optimization of the pellet production process and improvement of production quality.

Claims

1. A method for evaluating the production process of grate-rotary kiln oxidation pellets, characterized in that: The production process is divided into a raw material mixing process, a pelletizing process, a preheating process and a roasting process, and the method comprises the following steps: 1) The evaluation characteristic parameters of several samples of each pellet production process are measured and data are obtained. The evaluation characteristic parameters include TFe content, FeO content, moisture content and raw material particle size of the raw material mixing process; TFe content, FeO content, green ball falling strength and green ball compressive strength of the raw ball for the pelletizing process; TFe content, FeO content and preheated ball compressive strength of the preheated ball for the preheating process; TFe content, FeO content and preheated ball compressive strength of the calcined ball for the calcining process; 2) Assign weights according to the influence intensity of each evaluation characteristic parameter on the pelletizing production process, and use the uniformity index of each evaluation characteristic parameter of the pelletizing production process to evaluate the uniformity of the raw material characteristics or pellet quality of the pelletizing production process; 3) Weights are assigned according to the intensity of the impact of a single pellet production process on the entire pellet production process, and the uniformity index is used to evaluate the comprehensive uniformity of the entire chain grate-rotary kiln oxidation pellet production process.

2. The method for evaluating the production process of grate-rotary kiln oxidation pellets according to claim 1, characterized in that: The number of samples taken in step 1) is not less than 10.

3. The method for evaluating the production process of grate-rotary kiln oxidation pellets according to claim 1, characterized in that: In the step 2), the method for weighting the impact intensity of each evaluation characteristic parameter on the pellet production process is: 2.1) For the raw material mixing process, the influence weights of the raw material TFe content, FeO content, moisture content and particle size on the raw material mixing process are set to 10-20%, 20-30%, 30-35% and 20-25% respectively, and the sum of the four weight values ​​is 100%; 2.2) For the ball making process, the weights of the TFe content, FeO content, moisture, drop strength and compressive strength of the green balls on the ball making process are set to 10-15%, 20-25%, 20-25%, 15-20% and 15-20% respectively, and the sum of the five weight values ​​is 100%; 2.3) For the preheating process, the influence weights of the TFe content, FeO content and compressive strength of the preheating ball on the preheating process are set to 20-25%, 35-40% and 35-40% respectively, and the sum of the three weight values ​​is 100%; 2.4) For the roasting process, the weights of the TFe content, FeO content and compressive strength of the roasted balls on the roasting process are set to 20-25%, 35-40%, and 35-40%, respectively, and the sum of the three weights is 100%.

4. The method for evaluating the production process of grate-rotary kiln oxidation pellets according to claim 1, characterized in that: In step 2), the calculation process of the uniformity index includes the following steps: ① Calculate the average value of a certain evaluation characteristic parameter: Among them, μ is the average value of a certain evaluation characteristic parameter; X i is the value of a certain evaluation characteristic parameter measured for each sample; n is the number of selected samples; ② Use the average value of a certain evaluation characteristic parameter obtained in step ① to calculate the standard deviation σ of the corresponding evaluation characteristic parameter: ③ Use the average value of a certain evaluation characteristic parameter obtained in step ① and the standard deviation of a corresponding evaluation characteristic parameter obtained in step ② to calculate the dispersion coefficient CV of a corresponding evaluation characteristic parameter: CV=σ / μ ④ Use the discrete coefficient CV corresponding to a certain evaluation characteristic parameter obtained in step ③ to calculate the uniformity index M of the pellet production process corresponding to a certain evaluation characteristic parameter i : M i =(1-CV)×100% ⑤Use the uniformity index M corresponding to a certain evaluation characteristic parameter obtained in step ④ i As well as the weight of each evaluation characteristic parameter on the pelletizing production process, the uniformity index M of the pelletizing production process is calculated. j : M j =∑(M i *ω i ) Among them, ω i It is the weight value of the influence of a certain evaluation characteristic parameter on a certain pellet production process.

5. The method for evaluating the production process of grate-rotary kiln oxidation pellets according to claim 1, characterized in that: In the step 3), the method of assigning weights to the intensity of influence of each evaluation characteristic parameter on the whole process of pellet production is as follows: the influence weights of the raw material mixing process, pelletizing process, preheating process and roasting process on the whole process of chain grate-rotary kiln oxidation pellet production are 30-35%, 20-25%, 25-30% and 10-20% respectively, and the sum of the four weight values ​​is 100%.

6. The method for evaluating the production process of grate-rotary kiln oxidation pellets according to claim 1, characterized in that: In step 3), the calculation process of the uniformity index is: The uniformity index M of the pellet production process obtained in step 2) is used j As well as the weight value of the impact of the single pellet production process on the whole pellet production process, the comprehensive uniformity index M of the whole process of chain grate-rotary kiln oxidation pellet production is calculated: M=∑(M j *ω j ) Among them, ω j It is the weight value of the impact of each pelletizing production process on the whole pelletizing production process.

7. The method for evaluating the production process of grate-rotary kiln oxidation pellets according to claim 1, characterized in that: The evaluation relationship between the comprehensive uniformity index M and the uniformity of the entire process of chain grate-rotary kiln oxidation pellet production is: If M≥90%, the material properties and pellet quality uniformity of the production process are excellent; If 80%≤M<90%, the material characteristics of the production process and the uniformity of the pellet quality are good; If 60%≤M<80%, the material characteristics of the production process and the uniformity of the pellet quality are medium; If M is less than 60%, the material properties and pellet quality uniformity of the production process will be poor.

8. The method for evaluating the production process of grate-rotary kiln oxidation pellets according to claim 7, characterized in that: If the uniformity index M is less than 80%, in the grate-rotary kiln oxidation pellet production process, the raw material mixing process can be strengthened, and the pelletizing process can also be strengthened.

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