A method for visually identifying the cause of a crack in a pellet

Abstract

The application discloses a method for intuitively distinguishing causes of pellet crack, and comprises the following steps: (1) taking a plurality of finished pellet; selecting the pellet with surface cracks from the taken pellet, and counting as crack pellet; (2) judging the pellet surface crack length as longer when the length is greater than or equal to 5 mm, and judging as shorter when the length is less than 5 mm; judging the pellet surface crack width as thicker when the width is greater than or equal to 0.5 mm, and judging as thinner when the width is less than 0.5 mm; judging the pellet surface crack depth as deeper when the depth is greater than or equal to 2 mm, and judging as shallower when the depth is less than 2 mm; classifying the crack pellet according to the surface crack of the crack pellet, and associating the crack pellet of different categories with the causes of crack; and deducing the primary and secondary causes of the pellet crack by calculating the quantity proportion of each category of crack pellet. The method can quickly and accurately judge the causes of the pellet crack, timely improve the process, effectively reduce the proportion of crack pellet in the finished pellet, and improve the quality of the pellet.

Description

Technical Field

[0001] This invention relates to the field of metallurgical raw material testing technology, and in particular to a method for visually identifying the causes of cracks in pellet ore. Background Technology

[0002] With the increasing proportion of pellets used in blast furnaces, the quality requirements for blast furnace pellets have become more stringent. The presence of cracked pellets has a significant impact on the strength and overall particle size of the pellets. Cracked pellets are prone to breakage during loading, unloading, transportation, and charging and descent within the furnace, producing broken pellets and dust. This affects the permeability of the blast furnace charge and the efficiency of gas utilization, and also increases the amount of furnace dust. Therefore, the large presence of cracked pellets has a significant impact on blast furnace smelting.

[0003] The ability to quickly and accurately determine the cause of cracks in pellets and make timely process improvements has a significant impact on reducing the proportion of cracked pellets in the finished product and improving the quality of the pellets. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for quickly, accurately and intuitively identifying the causes of cracks in pellet ore.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention includes the following steps: (1) taking a number of finished pellets; selecting pellets with surface cracks from the taken pellets and counting them as cracked pellets; (2) The length of the surface crack of the pellet is ≥5mm and is judged to be relatively long, and <5mm and is judged to be relatively short; the width of the surface crack of the pellet is ≥0.5mm and is judged to be relatively coarse, and <0.5mm and is judged to be relatively fine; the depth of the surface crack of the pellet is ≥2mm and is judged to be relatively deep, and <2mm and is judged to be relatively shallow. (3) Select from the cracked balls at least one short, fine and shallow crack on the surface and at least one long, fine and deep curved crack, and calculate the proportion b1 of the selected cracked balls in the total number of cracked balls; b1 is the proportion of cracked balls generated when the pellets are not suitable due to the moisture content of the green pellets or the roasting regime. (4) Select from the cracked spheres at least one long, thin and deep straight crack on the surface, and at least one long, thick and deep crack, and calculate the proportion b2 of the selected cracked spheres in the total number of cracked spheres; b2 is the proportion of cracked spheres generated when the pellet ore is not suitable for bursting temperature. (5) Select crack spheres from the crack spheres that have at least one short, coarse, and shallow crack on their surface, and calculate the proportion b of the selected crack spheres in the total number of crack spheres. 3（1） Combined with the following steps (6), calculate b3 = b 3（1） +b4（3） b3 refers to the proportion of cracked pellets produced when the compressive strength of the green pellets is unsuitable. (6) Select cracked spheres from the cracked spheres that have at least one long, thick, and deep crack on their surface, and calculate the proportion b4 of the selected cracked spheres in the total number of cracked spheres; where b4 is the proportion of cracked spheres generated when the green pellets are not suitable due to unsuitable drop strength, compressive strength, or bursting temperature; select cracked spheres again from the cracked spheres selected in this step, and select cracked spheres with bilateral deformation on their surface, and calculate their proportion b in the total number of cracked spheres. 4（3） .

[0006] Furthermore, in step (1), take no less than 10 kg of finished pellets with a particle size of 8-16 mm.

[0007] Furthermore, in step (6), cracked spheres with unilateral surface deformation are selected again, and their proportion in the total number of cracked spheres is calculated and denoted as b. 4（5） The b 4（5） The proportion of cracked balls generated when raw balls fall due to differences in strength.

[0008] Furthermore, the following steps are also included: the proportions b1, b2, b3, and b4 are arranged in order of size, and the corresponding causes are the primary and secondary order of the causes of cracked spheres.

[0009] Furthermore, the ratios b1, b2, b3, b4, b 4（5） Arranged in order of size, the corresponding causes are the primary and secondary ranking of the causes of cracked spheres.

[0010] The beneficial effects of adopting the above technical solution are as follows: the present invention classifies cracked balls according to the crack morphology of cracked balls produced when the moisture content of green balls, the compressive strength and drop strength of green balls, the bursting temperature, and the firing regime is unsuitable, and calculates the proportion of each category. Finally, the primary and secondary causes of cracked balls are determined based on the proportion of different categories of cracked balls.

[0011] This invention classifies cracked pellets based on the length, thickness, depth, and straightness of cracks on their surface, as well as the degree of deformation of the pellets. It then correlates different categories of cracked pellets with the causes of crack formation through experiments and production practice. By classifying the morphology of cracks in pellets and calculating the proportion of each type of cracked pellet in the total number of pellets, the primary and secondary causes of pellet crack formation can be inferred. This allows for rapid and accurate identification of the causes of pellet crack formation, enabling timely process improvements, effectively reducing the proportion of cracked pellets in the finished pellets, and improving pellet quality. It is particularly suitable for pellets produced by belt roasters. After improvements are made using the causes identified by this invention, the permeability of the blast furnace's bulk belt can be effectively improved during blast furnace smelting, especially when the proportion of pellets in the furnace is high, ensuring stable and smooth blast furnace operation. Furthermore, this method is highly operable, simple, accurate, intuitive, and rapid. Attached Figure Description

[0012] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0013] Figure 1 This is a schematic diagram of the cracked sphere described in this invention. Detailed Implementation

[0014] Figure 1 As shown, surface cracks can form on ore pellets during the production process. These surface cracks are caused by several factors: poor falling strength of the green pellets, unsuitable compressive strength of the green pellets, unsuitable moisture content during the roasting process, and low bursting temperature of the green pellets. Through experiments and production practice, the morphologies of cracks caused by different reasons have been creatively summarized, revealing that the crack morphologies of pellets under different causes each have their own characteristics, making them easy to distinguish. Therefore, this method for intuitively identifying the causes of surface cracks in ore pellets can quickly and accurately determine the cause of surface cracks by observing the crack morphology.

[0015] This method for visually identifying the causes of cracks in pellets is particularly applicable to pellets produced by belt roasters, and includes the following steps: (1) Take no less than 10 kg of finished pellets from the sampling port at the tail of the belt roaster. The particle size of the finished pellets should be 8–16 mm. Select pellets with surface cracks from the collected pellets, i.e., pellets with one or more obvious cracks visible to the naked eye on the surface, such as… Figure 1As shown, each cracked ball is considered a fraction of the total number of finished pellets. The percentage (a) of cracked balls in the final product is calculated as: a = number of cracked balls / number of finished pellets. When the percentage (a) is less than 3%, the proportion is low, and the following analysis is not performed. When the percentage (a) is greater than or equal to 3%, the following analysis is performed based on the crack morphology of the pellets and the causes of crack formation.

[0016] (2) The following criteria are used to determine the type of surface cracks in the pellets: a surface crack length ≥ 5 mm is considered relatively long, and < 5 mm is considered relatively short; a surface crack width ≥ 0.5 mm is considered relatively coarse, and < 0.5 mm is considered relatively fine; a surface crack depth ≥ 2 mm is considered relatively deep, and < 2 mm is considered relatively shallow. Based on the type of surface crack, the following crack types are selected.

[0017] (3) First type: Crack morphology caused by unsuitable moisture content or roasting regime in pellets. One type is a long, thin, and deep crack, which is a curved crack; the other type is a short, thin, and shallow crack, which is a surface crack. Select the above two types of crack balls from all the crack balls selected in step (1), that is, crack balls with one or more long, thin, and deep curved cracks on the surface, and crack balls with one or more short, thin, and shallow cracks on the surface; and calculate the proportion b1 of the crack balls selected in this step in the total number of crack balls; b1 is the proportion of crack balls caused by unsuitable moisture content or roasting regime in pellets.

[0018] (4) Second type: Crack morphology generated when the pellet ore is at a low blasting temperature. One type is a long, thin, and deep crack, which is a straight crack; the other type is a long, thick, and deep crack, which is also a straight crack. Select the crack balls of the above two types from all the crack balls, that is, crack balls with one or more long, thin, and deep straight cracks on the surface, and crack balls with one or more long, thick, and deep cracks on the surface; and calculate the proportion b2 of the crack balls selected in this step in the total number of crack balls; b2 is the proportion of crack balls generated when the pellet ore is at an unsuitable blasting temperature.

[0019] (5) Third category: Select crack spheres from the crack spheres that have at least one short, coarse and shallow crack on their surface, and calculate the proportion b of the selected crack spheres in the total number of crack spheres. 3（1） Combined with the following steps (6), calculate b3 = b 3（1） +b 4（3） b3 refers to the proportion of cracked pellets produced when the compressive strength of the green pellets is unsuitable.

[0020] (6) Fourth category: When the ore pellets have poor drop strength, the crack morphology is a long, thick, and deep crack, which is a straight crack; when the ore pellets have poor compressive strength, one type of crack morphology is a long, thick, and deep crack with the diameter of the pellet decreasing along the crack direction, and the other type is a short, thick, and shallow crack with the outer layer of the pellet decreasing in diameter along the crack direction. Select crack balls with one or more long, thick, and deep cracks on the surface from the crack balls, and calculate the proportion b4 of the total number of crack balls selected in this step; b4 is the proportion of crack balls generated when the ore pellets have unsuitable drop strength, compressive strength, or bursting temperature.

[0021] From the fourth type of cracked spheres selected in this step, the following two subcategories are further selected: The first subcategory consists of cracked spheres with unilateral surface deformation, and the proportion of this subcategory in the total number of cracked spheres is calculated and denoted as b. 4（5） The cause of cracks in this type of small-scale cracked ball is the poor falling strength of the green ball. 4（5） The first category represents the proportion of cracked spheres generated when green spheres are dropped due to varying strength; the second category comprises cracked spheres with bilateral surface deformation, and the percentage (b) of this category in the total number of cracked spheres is calculated. 4（3） The reason for the cracking of this type of cracked ball is the poor compressive strength of the green ball.

[0022] Based on b2 and b3, the cause of the crack in b4 can be deduced as follows: if b2 and b4 are higher than b3, then the crack in b4 is mainly caused by an unsuitable bursting temperature; if b3 and b4 are higher than b2, then the crack in b4 is mainly caused by an unsuitable green ball compressive strength. 4（5） If the values ​​are higher than b2 and b3, then the cracks in b4 are considered to be mainly caused by the inappropriate drop strength of the green ball.

[0023] (7) Combining b1, b2, b3, b4, b 4（5） The size of the crack ball determines the primary and secondary causes of crack formation. The deduction process is as follows: if b1 is the largest, the main cause of crack formation in the pellet is considered to be unsuitable moisture or roasting regime; if b2 is the largest, the main cause of crack formation in the pellet is considered to be unsuitable bursting temperature; if b3 is the largest, the main cause of crack formation in the pellet is considered to be unsuitable compressive strength of green pellets; if b4 is the largest, the deduction is made according to the process in step (6). Crack balls that do not belong to the crack morphology described in steps (3)-(6) above are caused by other reasons.

[0024] Example 1: The method for visually identifying the causes of cracks in pellet ore is described in detail below.

[0025] (1) The ore blending structure is as follows: four different types of iron concentrate powder, A, B, C, and D, are used, with a mass ratio of 40% A + 15% B + 30% C + 15% D. Then, 4.2% hydrated lime and 0.5% bentonite by weight of iron concentrate powder are added to form pellets. 10.2 kg of finished pellets were taken from the sampling hole of the belt roaster tail, and 3095 pellets were counted, with a particle size of 8-16 mm. A total of 242 pellets with surface cracks were selected, and the proportion of cracked pellets was calculated to be a = 7.8%.

[0026] (2) All cracked spheres were classified as follows, and the proportion of each category was calculated: Category 1: 124 cracked spheres with one or more short, fine, and shallow cracks on the surface and long, fine, and deep curved cracks were selected from all cracked spheres. The proportion of each category was calculated as b1 = 51%. Category 2: 66 cracked spheres with one or more long, fine, and deep straight cracks on the surface were selected from all cracked spheres. The proportion of each category was calculated as b2 = 27%. Category 3: 61 cracked spheres with one or more short, coarse, and shallow cracks on the surface were selected from all cracked spheres. The proportion of each category was calculated as b1 = 51%. 3（1） =25%. The fourth category, 39 cracked spheres were selected from all cracked spheres, exhibiting one or more relatively long, coarse, and deep cracks on their surface. Their proportion, b4 = 16%. Among these, 8 cracked spheres showed bilateral deformation on their surface, i.e., b 4（3） =3%, there are a total of 5 cracked spheres with unilateral deformation on the surface, namely b 4（5） =2%. The fifth category consists of 12 crack spheres with other crack morphologies, and their proportion is calculated as b5 = 5%.

[0027] (3) Based on the different crack morphologies, the five types of cracked balls can be approximated as follows: The cause of cracks in the first type of cracked balls is: unsuitable moisture content and firing regime of the green balls, accounting for b1=51%; the cause of cracks in the second type of cracked balls is: unsuitable bursting temperature, accounting for b2=27%; the cause of cracks in the third type and some of the fourth type of cracked balls is: unsuitable compressive strength of the green balls, accounting for b3=b 3（1） +b 4（3） =28%; The causes of Class IV cracked balls are: unsuitable green ball drop strength, compressive strength, or bursting temperature, accounting for b4=16%, of which cracks caused by unilateral deformation of the surface due to poor green ball drop strength account for b 4（5） =2%; The fifth type of crack ball crack is caused by other reasons, accounting for b5=5%.

[0028] (4) b1>b3>b2>b4>b5>b 4（5）Therefore, the main cause of cracks in pellets is unsuitable moisture content and roasting regime in green pellets, and the secondary cause is unsuitable compressive strength of green pellets.

[0029] (5) Based on the above analysis, the moisture content of green pellets was reduced from 9.5% to 9%, the temperature of the hood in the blower drying section was increased from 65℃ to over 70℃, the temperature of the hood in the exhaust drying section was increased from 275℃ to over 285℃, the average particle size of green pellets was increased from 12.3mm to over 13mm, and the proportion of cracked pellets in the finished pellets was reduced from 7.8% to 5.2%.

[0030] Example 2: The method for visually identifying the causes of cracks in pellet ore is described in detail below.

[0031] (1) The ore blending structure is as follows: four different types of iron concentrate powder, A, B, C, and D, are used, with a mass ratio of 40% A + 15% B + 30% C + 15% D. Then, 4.2% hydrated lime and 0.5% bentonite by weight of iron concentrate powder are added to form pellets. 10.3 kg of finished pellets were taken from the sampling hole of the belt roaster tail, and 3182 pellets were counted, with a particle size of 8-16 mm. A total of 395 pellets with surface cracks were selected, and the proportion of cracked pellets was calculated to be a = 12.4%.

[0032] (2) All cracked spheres were classified as follows, and the proportion of each category was calculated: Category 1: 82 cracked spheres with one or more short, fine, and shallow cracks on the surface and long, fine, and deep curved cracks were selected from all cracked spheres. The proportion of each category was calculated as b1 = 21%. Category 2: 167 cracked spheres with one or more long, fine, and deep straight cracks on the surface were selected from all cracked spheres. The proportion of each category was calculated as b2 = 42%. Category 3: 75 cracked spheres with one or more short, coarse, and shallow cracks on the surface were selected from all cracked spheres. The proportion of each category was calculated as b1 = 21%. 3（1） =19%. The fourth category, selecting 117 cracked spheres from all cracked spheres, characterized by one or more relatively long, coarse, and deep cracks on the surface, represents a proportion b4 = 30%. Among these, 13 cracked spheres exhibit bilateral deformation on the surface, i.e., b 4（3） =3%, there are a total of 16 cracked spheres with unilateral deformation on the surface, namely b 4（5） =4%. The fifth category consists of 24 crack spheres with other crack morphologies, accounting for 6% of the total.

[0033] (3) Based on the different crack morphologies, the five types of cracked balls can be approximated as follows: The cause of cracks in the first type of cracked balls is: unsuitable moisture content and firing regime of the green balls, accounting for b1=21%; the cause of cracks in the second type of cracked balls is: unsuitable bursting temperature, accounting for b2=42%; the cause of cracks in the third type and some of the fourth type of cracked balls is: unsuitable compressive strength of the green balls, accounting for b3=b 3（1） +b 4（3） =22%; The causes of Class IV cracked balls are: unsuitable green ball drop strength, compressive strength, or bursting temperature, accounting for b4=30%, of which cracks caused by unilateral deformation of the surface due to poor green ball drop strength account for b 4（5） =4%; The cause of the fifth type of crack ball crack is: other reasons, accounting for b5=6%.

[0034] (4) b2>b4>b3>b1>b5>b 4（5） Since b2 is the largest, the main reason for the cracks in the pellets is the unsuitable bursting temperature of the green pellets. For the second ratio b4, since b2 and b4 are higher than b3, the reason for the cracks is also the unsuitable bursting temperature. Therefore, in summary, the main reason for the cracks in the pellets is the unsuitable bursting temperature of the green pellets.

[0035] (5) Based on the above analysis, by optimizing the ore blending structure and appropriately increasing the proportion of binder, the bursting temperature of green pellets was increased from 440℃ to 470℃, and the proportion of cracked pellets in the finished pellets decreased from 12.4% to 7.3%.

[0036] Example 3: The method for visually identifying the causes of cracks in pellet ore is described in detail below.

[0037] (1) The ore blending structure is as follows: four different types of iron concentrate powder, A, B, C, and D, are used, with a mass ratio of 40% A + 15% B + 30% C + 15% D. Then, 4.2% hydrated lime and 0.5% bentonite by weight of iron concentrate powder are added to form pellets. 10.15 kg of finished pellets were taken from the sampling hole of the belt roaster tail, and 3012 pellets were counted, with a particle size of 8-16 mm. A total of 344 pellets with surface cracks were selected, and the proportion of cracked pellets was calculated to be a = 11.4%.

[0038] (2) All cracked spheres were classified as follows, and the proportion of each category was calculated: Category 1: 59 cracked spheres with one or more short, fine, and shallow cracks on their surface and long, fine, and deep curved cracks were selected from all cracked spheres. The proportion of each category was calculated as b1 = 17%. Category 2: 65 cracked spheres with one or more long, fine, and deep straight cracks on their surface were selected from all cracked spheres. The proportion of each category was calculated as b2 = 19%. Category 3: 131 cracked spheres with one or more short, coarse, and shallow cracks on their surface were selected from all cracked spheres. The proportion of each category was calculated as b1 = 17%. 3（1） =38%. The fourth category, 113 cracked spheres were selected from all cracked spheres, exhibiting one or more relatively long, coarse, and deep cracks on their surface. Their proportion, b4, was calculated to be 33%. Among these, 48 cracked spheres showed bilateral deformation on their surface, i.e., b 4（3） =14%, and there are a total of 27 cracked spheres with unilateral deformation on the surface, namely b 4（5） =8%. The fifth category consists of 14 crack spheres with other crack morphologies, accounting for 4% of the total.

[0039] (3) Based on the different crack morphologies, the five types of cracked balls can be approximated as follows: The cause of cracks in the first type of cracked balls is: unsuitable moisture content and firing regime of the green balls, accounting for b1=17%; the cause of cracks in the second type of cracked balls is: unsuitable bursting temperature, accounting for b2=19%; the cause of cracks in the third type and some of the fourth type of cracked balls is: unsuitable compressive strength of the green balls, accounting for b3=b 3（1） +b 4（3） =52%; The causes of Class IV cracked balls are: unsuitable green ball drop strength, compressive strength, or bursting temperature, accounting for b4=33%, of which cracks caused by unilateral deformation of the surface due to poor green ball drop strength account for b 4（5） =8%; The cause of the fifth type of crack ball crack is: other reasons, accounting for b5=4%.

[0040] (4) b3 > b4 > b2 > b1 > b 4（5） >b5, since the largest proportion, b3, represents the third type of crack formation due to unsuitable green pellet compressive strength, it is inferred that the main cause of cracked pellets is unsuitable green pellet compressive strength. For the second proportion, b4, since b3 and b4 are higher than b2, it is determined that the cause of its crack formation is also unsuitable green pellet compressive strength, further verifying that the main cause of pellet crack formation is unsuitable green pellet compressive strength.

[0041] (5) Based on the above analysis, the average compressive strength of the green balls was adjusted to above 12N, and the proportion of green balls with less than 8N was less than 5%. The proportion of cracked balls in the finished balls decreased from 11.4% to 7.2%.

[0042] Example 4: The method for visually identifying the causes of cracks in pellet ore is described in detail below.

[0043] (1) The ore blending structure is as follows: four different types of iron concentrate powder, A, B, C, and D, are used, with a mass ratio of 40% A + 15% B + 30% C + 15% D. Then, 4.2% hydrated lime and 0.5% bentonite by weight of iron concentrate powder are added to form pellets. 10.03 kg of finished pellets were taken from the sampling hole of the belt roaster tail, and 2975 pellets were counted, with a particle size of 8-16 mm. A total of 301 pellets with surface cracks were selected, and the proportion of cracked pellets was calculated to be a = 10.1%.

[0044] (2) All cracked spheres were classified as follows, and the proportion of each category was calculated: Category 1: 114 cracked spheres with one or more short, fine, and shallow cracks on the surface and long, fine, and deep curved cracks were selected from all cracked spheres. The proportion of each category was calculated as b1 = 38%. Category 2: 30 cracked spheres with one or more long, fine, and deep straight cracks on the surface were selected from all cracked spheres. The proportion of each category was calculated as b2 = 10%. Category 3: 81 cracked spheres with one or more short, coarse, and shallow cracks on the surface were selected from all cracked spheres. The proportion of each category was calculated as b1 = 38%. 3（1） =27%. The fourth category, selecting 118 cracked spheres from all cracked spheres, characterized by one or more relatively long, coarse, and deep cracks on the surface, represents a proportion b4 = 39%. Among these, 28 cracked spheres exhibit bilateral deformation on the surface, i.e., b 4（3） =9%, there are a total of 21 cracked spheres with unilateral deformation on the surface, namely b 4（5） =7%. The fifth category consists of 12 crack spheres with other crack morphologies, accounting for 4% of the total.

[0045] (3) Based on the different crack morphologies, the five types of cracked balls can be approximated as follows: The cause of cracks in the first type of cracked balls is: unsuitable moisture content and firing regime of the green balls, accounting for b1=38%; the cause of cracks in the second type of cracked balls is: unsuitable bursting temperature, accounting for b2=10%; the cause of cracks in the third type and some of the fourth type of cracked balls is: unsuitable compressive strength of the green balls, accounting for b3=b 3（1） +b 4（3）=36%; The causes of Class IV cracked balls are: unsuitable green ball drop strength, compressive strength, or bursting temperature, accounting for b4=38%, of which cracks caused by unilateral deformation of the surface due to poor green ball drop strength account for b 4（5） =7%; The cause of the fifth type of crack ball crack is: other reasons, accounting for b5=4%.

[0046] (4) b4 > b1 > b3 > b2 > b 4（5） >b5, and the largest proportion of cracks, represented by b4, indicates the fourth type of crack formation caused by unsuitable green ball drop strength, compressive strength, or bursting temperature. Since b3 and b4 are higher than b2, it is assumed that the cracks in b4 are mainly caused by unsuitable green ball compressive strength. Furthermore, because b1 > b3, and b4 represents the proportion of cracked balls caused by multiple factors, it is inferred that the main causes of cracked balls include unsuitable green ball compressive strength and unsuitable green ball moisture content and firing regime.

[0047] (5) Based on the above analysis, the average compressive strength of green balls is stabilized to 12N to 16N, and the proportion of green balls with less than 8N is less than 5%. The moisture content of green balls is reduced from 9.5% to 8.5% to 9%, and the proportion of cracked balls in the finished balls is reduced from 10.1% to 6.1%.

[0048] Comparative Example: In Example 4, using traditional methods to reduce the proportion of cracked pellets, through optimization of ore blending structure, green pellet quality, and roasting regime, the proportion of cracked pellets in the pellet ore did not decrease significantly because the main causes of cracked pellet formation were not improved; instead, it increased from 10.1% to 10.5%. However, according to this method, through analysis of crack morphology in the pellets, it was determined that the main causes of crack formation in the pellet ore were the compressive strength of the green pellets, the moisture content of the green pellets, and an unsuitable roasting regime. Based on the above analysis, the average compressive strength of the green pellets was stabilized to 12N-16N, and the proportion of green pellets with a strength less than 8N was less than 5%. The moisture content of the green pellets was reduced from 9.5% to 8.5%-9%, and the proportion of cracked pellets in the finished pellets decreased from 10.1% to 6.1%, establishing a better improvement effect.

Claims

1. A method for intuitively identifying the causes of cracks in ore pellets, characterized in that, Includes the following steps: (1) Take a number of finished pellets; select pellets with surface cracks from the taken pellets and count them as cracked pellets; (2) The length of the surface crack of the pellet is ≥5mm and is judged to be relatively long, and <5mm and is judged to be relatively short; the width of the surface crack of the pellet is ≥0.5mm and is judged to be relatively coarse, and <0.5mm and is judged to be relatively fine; the depth of the surface crack of the pellet is ≥2mm and is judged to be relatively deep, and <2mm and is judged to be relatively shallow. (3) Select from the cracked balls at least one short, fine and shallow crack on the surface and at least one long, fine and deep curved crack, and calculate the proportion b1 of the selected cracked balls in the total number of cracked balls; b1 is the proportion of cracked balls generated when the pellets are not suitable due to the moisture content of the green pellets or the roasting regime. (4) Select from the cracked spheres at least one long, thin and deep straight crack on the surface, and at least one long, thick and deep crack, and calculate the proportion b2 of the selected cracked spheres in the total number of cracked spheres; b2 is the proportion of cracked spheres generated when the pellet ore is not suitable for bursting temperature. (5) Select crack spheres from the crack spheres that have at least one short, coarse, and shallow crack on their surface, and calculate the proportion b of the selected crack spheres in the total number of crack spheres. 3（1） Combined with the following steps (6), calculate b3 = b 3（1） +b 4（3） b3 refers to the proportion of cracked pellets produced when the compressive strength of the green pellets is unsuitable. (6) Select cracked spheres from the cracked spheres that have at least one long, thick, and deep crack on their surface, and calculate the proportion b4 of the selected cracked spheres in the total number of cracked spheres; where b4 is the proportion of cracked spheres generated when the green pellets are not suitable due to unsuitable drop strength, compressive strength, or bursting temperature; select cracked spheres again from the cracked spheres selected in this step, and select cracked spheres with bilateral deformation on their surface, and calculate their proportion b in the total number of cracked spheres. 4（3） .

2. The method for intuitively identifying the cause of cracks in pellet ore according to claim 1, characterized in that: In step (1), take no less than 10 kg of finished pellets with a particle size of 8-16 mm.

3. The method for intuitively identifying the cause of cracks in pellet ore according to claim 1, characterized in that: In step (6), cracked spheres with unilateral surface deformation are selected again, and their proportion in the total number of cracked spheres is calculated and denoted as b. 4（5） The b 4（5） The proportion of cracked balls generated when raw balls fall due to differences in strength.

4. A method for visually identifying the cause of cracks in pellet ore according to claim 1, 2, or 3, characterized in that, It also includes the following steps: the proportions b1, b2, b3, and b4 are arranged in order of size, and the corresponding causes are the primary and secondary order of the causes of cracked spheres.

5. The method for intuitively identifying the cause of cracks in pellet ore according to claim 4, characterized in that: The ratios b1, b2, b3, b4, b 4（5） Arranged in order of size, the corresponding causes are the primary and secondary ranking of the causes of cracked spheres.

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