Method for reducing the swelling rate of pellets

Abstract

The application discloses a method for reducing the expansion rate of pellet, which comprises the following steps: adding a mixture of fine ground rotary kiln ring forming material and iron flux slag into iron ore powder, then preparing finished product pellet through proportioning, pelletizing, roasting and cooling. The method solves the technical problem of the deterioration of the expansion rate of pellet when producing alkaline pellet through a chain grate machine-rotary kiln by taking fine ground limestone powder as flux and fine particle level iron ore powder as iron material, so that the expansion rate of the pellet is 14-19%, which is completely suitable for high proportion of blast furnace iron making, and is beneficial to the stable and smooth operation of the blast furnace.

Description

Technical Field

[0001] This invention belongs to the field of iron pellet production technology for blast furnace ironmaking, and more specifically relates to a method for reducing the expansion rate of pellets. Background Technology

[0002] When alkaline pellets are produced using finely ground limestone powder as flux and fine-grained iron ore powder as iron feedstock through a chain grate-rotary kiln, the reducibility of the pellets can be improved, which is beneficial for blast furnace smelting. However, the expansion rate of the pellets also deteriorates, which is not conducive to large-scale blending in blast furnaces and to stable furnace operation. Therefore, it is necessary to take measures to reduce the expansion rate of alkaline pellets. Summary of the Invention

[0003] To address the technical problems existing in the prior art, the present invention provides a method for reducing the expansion rate of pellets, comprising the following steps:

[0004] Step 1: Preparation of flux clinker

[0005] Weigh and mix the rotary kiln ring material and iron flux slag according to the following weight proportions, the specific ratio is as follows:

[0006] 20 portions of rotary kiln ring material

[0007] 80 parts of iron flux slag

[0008] The rotary kiln ring material and iron flux slag after batching are mixed and ground in a ball mill to obtain flux clinker, and the proportion of particles with a particle size of less than 0.044mm in the flux clinker is controlled to be more than 70%.

[0009] Step 2: Ingredient Preparation

[0010] The flux clinker, limestone powder, iron ore powder, and bentonite are weighed and mixed according to the following weight proportions to obtain the mixed pelletizing material. The specific proportions are as follows:

[0011]

[0012] Step 3: Mix and form pellets

[0013] The above-mentioned mixed pelletizing material is mixed evenly by a high-strength mixer, and then added to a disc pelletizer to supplement moisture and produce pellets. The moisture content of the pellets is controlled at 9.6% by weight, and the average particle size of the pellets is controlled at 9-13 mm.

[0014] Step 4: Calcination and Cooling

[0015] The pellets are fed and roasted on a chain grate rotary kiln. The roasted high-temperature pellets are then cooled by an annular cooler to obtain finished pellets. The temperature of the preheating section II of the chain grate is controlled at 1140-1160℃, the time for the pellets to pass through the preheating section II is controlled at 7.3-9 minutes, and the temperature of the rotary kiln head is controlled at 1180-1200℃.

[0016] Furthermore, in the above methods for reducing the expansion rate of pellets:

[0017] The rotary kiln agglomerates are the lump-shaped agglomerates produced in the rotary kiln during the production of alkaline pellets using a chain grate-rotary kiln. Their main chemical components, by weight percentage, are: TFe 59–62%, FeO 0.5–1.5%, SiO2 4.0–6.5%, CaO 3.5–5.0%, MgO 0.3–0.8%, and Al2O3 1.2–1.8%.

[0018] The iron flux slag is a lump ore-type iron-containing flux slag formed by sintering iron ore powder with other high Al2O3 content mineral powders, quicklime, and coke powder. Its main chemical components by weight percentage are: TFe 43-50%, FeO 10-15%, SiO2 4.6-5.5%, CaO 23-30%, MgO 1.2-2.0%, and Al2O3 1.0-2.0%.

[0019] Furthermore, in the above methods for reducing the expansion rate of pellets:

[0020] The iron ore powder contains 99.5% particles smaller than 0.044 mm, has an iron grade of 65.8%, and contains 15.3% FeO, 4.2% SiO2, 0.48% CaO, and 10.7% moisture by weight percentage.

[0021] The proportion of particles smaller than 0.074 mm in the bentonite is controlled to be 86%.

[0022] The binary basicity of the finished pellet is 0.7.

[0023] As one implementation method, in the above-described method for reducing the expansion rate of pellets:

[0024] In step one, the main chemical components of the rotary kiln ring-forming material, by weight percentage, are: TFe 61.13%, FeO 0.93%, SiO2 5.5%, CaO 4.8%, MgO 0.6%, and Al2O3 1.6%; the main chemical components of the iron flux slag, by weight percentage, are: TFe 44.4%, FeO 13.7%, SiO2 4.76%, CaO 27.62%, MgO 1.73%, and Al2O3 1.8%; the proportion of particles smaller than 0.044mm in the flux clinker is 83%.

[0025] In step two, the weight ratio of flux clinker, limestone powder, iron ore powder, and bentonite is as follows:

[0026]

[0027] In step four, the temperature of the preheating stage II of the chain grate is controlled at 1150℃, the time for the pellets to pass through the preheating stage II is controlled at 8.7 minutes, and the temperature of the rotary kiln head is controlled at 1185℃.

[0028] As one implementation method, in the above-described method for reducing the expansion rate of pellets:

[0029] In step one, the main chemical components of the rotary kiln ring-forming material, by weight percentage, are: TFe 61.13%, FeO 0.93%, SiO2 5.5%, CaO 4.8%, MgO 0.6%, and Al2O3 1.6%; the main chemical components of the iron flux slag, by weight percentage, are: TFe 44.4%, FeO 13.7%, SiO2 4.76%, CaO 27.62%, MgO 1.73%, and Al2O3 1.8%; the proportion of particles smaller than 0.044mm in the flux clinker is 83%.

[0030] In step two, the weight ratio of flux clinker, limestone powder, iron ore powder, and bentonite is as follows:

[0031]

[0032] In step four, the temperature of the preheating stage II of the chain grate is controlled at 1150℃, the time for the pellets to pass through the preheating stage II is controlled at 8.7 minutes, and the temperature of the rotary kiln head is controlled at 1185℃.

[0033] As one implementation method, in the above-described method for reducing the expansion rate of pellets:

[0034] In step one, the main chemical components of the rotary kiln ring-forming material, by weight percentage, are: TFe 61.13%, FeO 0.93%, SiO2 5.5%, CaO 4.8%, MgO 0.6%, and Al2O3 1.6%; the main chemical components of the iron flux slag, by weight percentage, are: TFe 44.4%, FeO 13.7%, SiO2 4.76%, CaO 27.62%, MgO 1.73%, and Al2O3 1.8%; the proportion of particles smaller than 0.044mm in the flux clinker is 83%.

[0035] In step two, the weight ratio of flux clinker, limestone powder, iron ore powder, and bentonite is as follows:

[0036]

[0037] In step four, the temperature of the preheating stage II of the chain grate is controlled at 1150℃, the time for the pellets to pass through the preheating stage II is controlled at 8.7 minutes, and the temperature of the rotary kiln head is controlled at 1185℃.

[0038] As one implementation method, in the above-described method for reducing the expansion rate of pellets:

[0039] In step one, the main chemical components of the rotary kiln ring-forming material, by weight percentage, are: TFe 61.13%, FeO 0.93%, SiO2 5.5%, CaO 4.8%, MgO 0.6%, and Al2O3 1.6%; the main chemical components of the iron flux slag, by weight percentage, are: TFe 44.4%, FeO 13.7%, SiO2 4.76%, CaO 27.62%, MgO 1.73%, and Al2O3 1.8%; the proportion of particles smaller than 0.044mm in the flux clinker is 83%.

[0040] In step two, the weight ratio of flux clinker, limestone powder, iron ore powder, and bentonite is as follows:

[0041]

[0042]

[0043] In step four, the temperature of the preheating stage II of the chain grate is controlled at 1150℃, the time for the pellets to pass through the preheating stage II is controlled at 8.7 minutes, and the temperature of the rotary kiln head is controlled at 1185℃.

[0044] As one implementation method, in the above-described method for reducing the expansion rate of pellets:

[0045] In step one, the main chemical components of the rotary kiln ring-forming material, by weight percentage, are: TFe 61.13%, FeO 0.93%, SiO2 5.5%, CaO 4.8%, MgO 0.6%, and Al2O3 1.6%; the main chemical components of the iron flux slag, by weight percentage, are: TFe 44.4%, FeO 13.7%, SiO2 4.76%, CaO 27.62%, MgO 1.73%, and Al2O3 1.8%; the proportion of particles smaller than 0.044mm in the flux clinker is 83%.

[0046] In step two, the weight ratio of flux clinker, limestone powder, iron ore powder, and bentonite is as follows:

[0047]

[0048] In step four, the temperature of the preheating stage II of the chain grate is controlled at 1150℃, the time for the pellets to pass through the preheating stage II is controlled at 8.7 minutes, and the temperature of the rotary kiln head is controlled at 1185℃.

[0049] As one implementation method, in the above-described method for reducing the expansion rate of pellets:

[0050] In step one, the main chemical components of the rotary kiln ring-forming material, by weight percentage, are: TFe 61.13%, FeO 0.93%, SiO2 5.5%, CaO 4.8%, MgO 0.6%, and Al2O3 1.6%; the main chemical components of the iron flux slag, by weight percentage, are: TFe 44.4%, FeO 13.7%, SiO2 4.76%, CaO 27.62%, MgO 1.73%, and Al2O3 1.8%; the proportion of particles smaller than 0.044mm in the flux clinker is 83%.

[0051] In step two, the weight ratio of flux clinker, limestone powder, iron ore powder, and bentonite is as follows:

[0052]

[0053] In step four, the temperature of the preheating stage II of the chain grate is controlled at 1150℃, the time for the pellets to pass through the preheating stage II is controlled at 8.7 minutes, and the temperature of the rotary kiln head is controlled at 1185℃.

[0054] The method for reducing the expansion rate of pellets in this invention has the following advantages and beneficial effects: By adding a certain proportion of finely ground rotary kiln ring material and iron flux slag mixture (i.e., flux clinker) to iron ore powder, and then through batching, pelletizing, roasting and cooling, finished pellets are obtained. This solves the technical problem of the deterioration of the expansion rate of pellets when using finely ground limestone powder as flux and fine-grained iron ore powder as iron material to produce alkaline pellets through a chain grate-rotary kiln. The expansion rate of the pellets is 14-19%, which is fully suitable for large-scale blending in blast furnace ironmaking and is conducive to stable and smooth furnace operation. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0056] To address the technical challenge of deteriorating pellet expansion rate when producing alkaline pellets using finely ground limestone powder as flux and fine-grained iron ore powder as feedstock via a chain grate-rotary kiln, this invention provides a method for reducing pellet expansion rate. This method involves adding a certain proportion of a mixture of finely ground rotary kiln agglomerates and iron flux slag to the iron ore powder, followed by batching, pelletizing, roasting, and cooling to obtain the finished pellets. The specific steps include:

[0057] Step 1: Preparation of flux clinker

[0058] Weigh and mix the rotary kiln ring material and iron flux slag according to the following weight proportions, the specific ratio is as follows:

[0059] 20 portions of rotary kiln ring material

[0060] 80 parts of iron flux slag

[0061] The rotary kiln ring material and iron flux slag after batching are mixed and ground in a ball mill to obtain flux clinker, and the proportion of particles with a particle size of less than 0.044mm in the flux clinker is controlled to be above 70%.

[0062] The rotary kiln agglomerates are the lump-shaped agglomerates produced by the rotary kiln during the production of alkaline pellets using a chain grate-rotary kiln. Their main chemical components by weight percentage are: TFe 59–62%, FeO 0.5–1.5%, SiO2 4.0–6.5%, CaO 3.5–5.0%, MgO 0.3–0.8%, and Al2O3 1.2–1.8%. The iron flux slag is a lump-shaped iron-containing flux slag formed by sintering iron ore powder mixed with other high-Al2O3 content mineral powders, quicklime, and coke powder. Its main chemical components by weight percentage are: TFe 43–50%, FeO 10–15%, SiO2 4.6–5.5%, CaO 23–30%, MgO 1.2–2.0%, and Al2O3 1.0–2.0%.

[0063] Step 2: Ingredient Preparation

[0064] The flux clinker, limestone powder, iron ore powder, and bentonite are weighed and mixed according to the following weight proportions to obtain the mixed pelletizing material. The specific proportions are as follows:

[0065]

[0066]

[0067] The iron ore powder contains 99.5% particles smaller than 0.044 mm, has an iron grade of 65.8%, and contains 15.3% FeO, 4.2% SiO2, 0.48% CaO, and 10.7% moisture by weight. The bentonite is commercially available conventional bentonite, and the proportion of particles smaller than 0.074 mm in the bentonite is controlled at 86%.

[0068] Step 3: Mix and form pellets

[0069] The above-mentioned mixed pelletizing material is mixed evenly by a high-power mixer, and then added to a disc pelletizer to supplement moisture and produce pellets. The moisture content of the pellets is controlled at 9.6% by weight, and the average particle size of the pellets is controlled at 9-13 mm.

[0070] Step 4: Calcination and Cooling

[0071] The pellets are fed and roasted on a chain grate-rotary kiln. The roasted high-temperature pellets are then cooled by an annular cooler to obtain finished pellets. The temperature of the preheating section II of the chain grate is controlled at 1140-1160℃, the time for the pellets to pass through the preheating section II is controlled at 7.3-9 minutes, the kiln head temperature of the rotary kiln is controlled at 1180-1200℃, and the binary basicity (CaO / SiO2) of the finished pellets is 0.7.

[0072] Experimental tests were conducted on the expansion rate of the pellets prepared as described above. The expansion rate of the pellets prepared by the method of reducing the expansion rate of the pellets in this invention is 14-19%, which is fully suitable for large-scale blending in blast furnace ironmaking and is conducive to stable and smooth furnace operation.

[0073] The following comparative examples and embodiments further illustrate the specific implementation of the method for reducing the expansion rate of ore pellets according to the present invention.

[0074] Comparison Example

[0075] As a comparative example, the conventional process for producing fine-grained iron ore powder pellets includes the following steps:

[0076] (1) Ingredients

[0077] Iron ore powder, limestone powder, and bentonite are weighed and mixed according to the following weight proportions, with the specific ratio as follows:

[0078] 936 parts of iron ore powder

[0079] 54 parts limestone powder

[0080] 10 parts bentonite

[0081] The iron ore powder is from Lanxian County, Shanxi Province, with 99.5% of the particles smaller than 0.044mm, an iron grade of 65.8%, and by weight percentage, the FeO content is 15.3%, the SiO2 content is 4.2%, the CaO content is 0.48%, and the moisture content is 10.7%. The bentonite is commercially available conventional bentonite, with 86% of the particles smaller than 0.074mm.

[0082] (2) Mixing and pelletizing

[0083] The mixture obtained from the above step (1) is mixed evenly by a high-power mixer, and then added to a disc pelletizer to replenish water and produce pellets. The resulting pellets have a moisture content of 9.6% (by weight percentage) and an average particle size of 8-16 mm.

[0084] (3) Roasting

[0085] The pellets obtained in step (2) above are fed and roasted on a chain grate-rotary kiln. The high-temperature pellets after roasting are then cooled by an annular cooler to obtain finished pellets. The temperature of the preheating section II of the chain grate is 1150℃, the time for the pellets to pass through the preheating section II is 6 minutes, the temperature of the kiln head of the rotary kiln is 1185℃, and the main chemical components of the finished pellets by weight percentage are: TFe 63.38%, SiO2 4.74%, CaO 3.30%, MgO 0.85%, Al2O3 1.03%, and the binary basicity (CaO / SiO2) of the finished pellets is 0.7.

[0086] Experimental tests showed that the expansion rate of the pellets in the control example was 21.3%. This control example indicates that alkaline pellets produced using conventional processes have an expansion rate exceeding 20%, which is unfavorable for large-scale blast furnace application and hinders stable furnace operation.

[0087] Example 1

[0088] Example 1 of this invention mainly involves adding a certain proportion of finely ground rotary kiln agglomerates and iron flux slag to iron ore powder, followed by batching, pelletizing, roasting, and cooling to obtain finished pellets. Compared to the control example, in Example 1, the particle size of the pellets during pelletizing is adjusted from 8-16 mm to 9-13 mm, and the time for the pellets to pass through the preheating stage II during roasting is extended from 6 min to 8.7 min. Specifically, Example 1 includes the following steps:

[0089] Step 1: Preparation of flux clinker

[0090] Weigh and mix the rotary kiln ring material and iron flux slag according to the following weight proportions, the specific ratio is as follows:

[0091] 20 portions of rotary kiln ring material

[0092] 80 parts of iron flux slag

[0093] The rotary kiln agglomerates are the lump-shaped agglomerates produced by the rotary kiln during the production of alkaline pellets using a chain grate-rotary kiln. Their main chemical components, by weight percentage, are: TFe 61.13%, FeO 0.93%, SiO2 5.5%, CaO 4.8%, MgO 0.6%, and Al2O3 1.6%. The iron flux slag is a lump-shaped iron-containing flux slag formed by sintering a mixture of iron ore powder from Taiyuan Iron & Steel Group's Lanxian County with other high-Al2O3 content mineral powders, quicklime, and coke powder. Its main chemical components, by weight percentage, are: TFe 44.4%, FeO 13.7%, SiO2 4.76%, CaO 27.62%, MgO 1.73%, and Al2O3 1.8%.

[0094] The rotary kiln ring material and iron flux slag after batching are mixed and ground in a ball mill to obtain flux clinker. The proportion of particles smaller than 0.044 mm in the flux clinker is 83%. The main chemical components of the flux clinker by weight percentage are: TFe 47.74%, FeO 11.14%, SiO2 4.91%, CaO 23.06%, MgO 1.5%, and Al2O3 1.76%.

[0095] Step 2: Ingredient Preparation

[0096] The flux clinker, limestone powder, iron ore powder, and bentonite are weighed and mixed according to the following weight proportions to obtain the mixed pelletizing material. The specific proportions are as follows:

[0097]

[0098] The iron ore powder is from Lanxian County, Shanxi Province, with 99.5% of the particles smaller than 0.044mm, an iron grade of 65.8%, and by weight percentage, the FeO content is 15.3%, the SiO2 content is 4.2%, the CaO content is 0.48%, and the moisture content is 10.7%. The bentonite is commercially available conventional bentonite, with 86% of the particles smaller than 0.074mm.

[0099] Step 3: Mix and form pellets

[0100] The above-mentioned mixed pelletizing material is mixed evenly by a high-power mixer, and then added to a disc pelletizer to supplement moisture and produce pellets. The moisture content of the pellets is controlled at 9.6% by weight, and the average particle size of the pellets is controlled at 9-13 mm.

[0101] Step 4: Calcination and Cooling

[0102] The pellets are fed and roasted on a chain grate rotary kiln. The roasted high-temperature pellets are then cooled by an annular cooler to obtain finished pellets. The temperature of the preheating section II of the chain grate is controlled at 1150℃, the time for the pellets to pass through the preheating section II is controlled at 8.7 min, and the temperature of the rotary kiln head is controlled at 1185℃. The main chemical components of the finished pellets by weight percentage are: TFe 63.30%, SiO2 4.75%, CaO 3.37%, MgO 0.85%, Al2O3 1.03%, and the binary basicity (CaO / SiO2) of the finished pellets is 0.7.

[0103] Experimental tests were conducted on the expansion rate of the pellets prepared as described above. The expansion rate of the pellets prepared by the method of reducing the expansion rate of pellets in Example 1 of this invention was 18.2%, which is fully suitable for large-scale blending in blast furnace ironmaking and is conducive to stable and smooth furnace operation.

[0104] Example 2

[0105] Example 2 of this invention mainly involves adding a certain proportion of finely ground rotary kiln agglomerates and iron flux slag to iron ore powder, followed by batching, pelletizing, roasting, and cooling to obtain finished pellets. Compared to the control example, in Example 1, the particle size of the pellets during pelletizing was adjusted from 8-16 mm to 9-13 mm, and the time for the pellets to pass through the preheating stage II during roasting was extended from 6 min to 8.7 min. Furthermore, compared to Example 1, the flux clinker used in Example 2 was increased from 12 parts by weight to 16 parts by weight. Specifically, Example 2 includes the following steps:

[0106] Step 1: Preparation of flux clinker

[0107] Weigh and mix the rotary kiln ring material and iron flux slag according to the following weight proportions, the specific ratio is as follows:

[0108] 20 portions of rotary kiln ring material

[0109] 80 parts of iron flux slag

[0110] The rotary kiln agglomerates are the lump-shaped agglomerates produced by the rotary kiln during the production of alkaline pellets using a chain grate-rotary kiln. Their main chemical components, by weight percentage, are: TFe 61.13%, FeO 0.93%, SiO2 5.5%, CaO 4.8%, MgO 0.6%, and Al2O3 1.6%. The iron flux slag is a lump-shaped iron-containing flux slag formed by sintering a mixture of iron ore powder from Taiyuan Iron & Steel Group's Lanxian County with other high-Al2O3 content mineral powders, quicklime, and coke powder. Its main chemical components, by weight percentage, are: TFe 44.4%, FeO 13.7%, SiO2 4.76%, CaO 27.62%, MgO 1.73%, and Al2O3 1.8%.

[0111] The rotary kiln ring material and iron flux slag after batching are mixed and ground in a ball mill to obtain flux clinker. The proportion of particles smaller than 0.044 mm in the flux clinker is 83%. The main chemical components of the flux clinker by weight percentage are: TFe 47.74%, FeO 11.14%, SiO2 4.91%, CaO 23.06%, MgO 1.5%, and Al2O3 1.76%.

[0112] Step 2: Ingredient Preparation

[0113] The flux clinker, limestone powder, iron ore powder, and bentonite are weighed and mixed according to the following weight proportions to obtain the mixed pelletizing material. The specific proportions are as follows:

[0114]

[0115] The iron ore powder is from Lanxian County, Shanxi Province, with 99.5% of the particles smaller than 0.044mm, an iron grade of 65.8%, and by weight percentage, the FeO content is 15.3%, the SiO2 content is 4.2%, the CaO content is 0.48%, and the moisture content is 10.7%. The bentonite is commercially available conventional bentonite, with 86% of the particles smaller than 0.074mm.

[0116] Step 3: Mix and form pellets

[0117] The above-mentioned mixed pelletizing material is mixed evenly by a high-power mixer, and then added to a disc pelletizer to supplement moisture and produce pellets. The moisture content of the pellets is controlled at 9.6% by weight, and the average particle size of the pellets is controlled at 9-13 mm.

[0118] Step 4: Calcination and Cooling

[0119] The pellets are fed and roasted on a chain grate rotary kiln. The roasted high-temperature pellets are then cooled by an annular cooler to obtain finished pellets. The temperature of the preheating section II of the chain grate is controlled at 1150℃, the time for the pellets to pass through the preheating section II is controlled at 8.7 min, and the temperature of the rotary kiln head is controlled at 1185℃. The main chemical components of the finished pellets by weight percentage are: TFe 63.36%, SiO2 4.75%, CaO 3.35%, MgO 0.85%, Al2O3 1.04%, and the binary basicity (CaO / SiO2) of the finished pellets is 0.7.

[0120] Experimental tests were conducted on the expansion rate of the pellets prepared as described above. The expansion rate of the pellets prepared by the method of reducing the expansion rate of pellets in Example 2 of this invention was 17.5%, which is fully suitable for large-scale blending in blast furnace ironmaking and is conducive to stable and smooth furnace operation.

[0121] Example 3

[0122] Example 3 of this invention mainly involves adding a certain proportion of finely ground rotary kiln agglomerates and iron flux slag to iron ore powder, followed by batching, pelletizing, roasting, and cooling to obtain finished pellets. Compared to the control example, in Example 1, the particle size of the pellets during pelletizing was adjusted from 8-16 mm to 9-13 mm, and the time for the pellets to pass through the preheating stage II during roasting was extended from 6 min to 8.7 min. Furthermore, compared to Example 2, the flux clinker used in Example 3 was increased from 16 parts by weight to 19 parts by weight. Specifically, Example 3 includes the following steps:

[0123] Step 1: Preparation of flux clinker

[0124] Weigh and mix the rotary kiln ring material and iron flux slag according to the following weight proportions, the specific ratio is as follows:

[0125] 20 portions of rotary kiln ring material

[0126] 80 parts of iron flux slag

[0127] The rotary kiln agglomerates are the lump-shaped agglomerates produced by the rotary kiln during the production of alkaline pellets using a chain grate-rotary kiln. Their main chemical components, by weight percentage, are: TFe 61.13%, FeO 0.93%, SiO2 5.5%, CaO 4.8%, MgO 0.6%, and Al2O3 1.6%. The iron flux slag is a lump-shaped iron-containing flux slag formed by sintering a mixture of iron ore powder from Taiyuan Iron & Steel Group's Lanxian County with other high-Al2O3 content mineral powders, quicklime, and coke powder. Its main chemical components, by weight percentage, are: TFe 44.4%, FeO 13.7%, SiO2 4.76%, CaO 27.62%, MgO 1.73%, and Al2O3 1.8%.

[0128] The rotary kiln ring material and iron flux slag after batching are mixed and ground in a ball mill to obtain flux clinker. The proportion of particles smaller than 0.044 mm in the flux clinker is 83%. The main chemical components of the flux clinker by weight percentage are: TFe 47.74%, FeO 11.14%, SiO2 4.91%, CaO 23.06%, MgO 1.5%, and Al2O3 1.76%.

[0129] Step 2: Ingredient Preparation

[0130] The flux clinker, limestone powder, iron ore powder, and bentonite are weighed and mixed according to the following weight proportions to obtain the mixed pelletizing material. The specific proportions are as follows:

[0131]

[0132] The iron ore powder is from Lanxian County, Shanxi Province, with 99.5% of the particles smaller than 0.044mm, an iron grade of 65.8%, and by weight percentage, the FeO content is 15.3%, the SiO2 content is 4.2%, the CaO content is 0.48%, and the moisture content is 10.7%. The bentonite is commercially available conventional bentonite, with 86% of the particles smaller than 0.074mm.

[0133] Step 3: Mix and form pellets

[0134] The above-mentioned mixed pelletizing material is mixed evenly by a high-power mixer, and then added to a disc pelletizer to supplement moisture and produce pellets. The moisture content of the pellets is controlled at 9.6% by weight, and the average particle size of the pellets is controlled at 9-13 mm.

[0135] Step 4: Calcination and Cooling

[0136] The pellets are fed and roasted on a chain grate rotary kiln. The roasted high-temperature pellets are then cooled by an annular cooler to obtain finished pellets. The temperature of the preheating section II of the chain grate is controlled at 1150℃, the time for the pellets to pass through the preheating section II is controlled at 8.7 min, and the temperature of the rotary kiln head is controlled at 1185℃. The main chemical components of the finished pellets by weight percentage are: TFe 63.28%, SiO2 4.75%, CaO 3.37%, MgO 0.85%, Al2O3 1.04%, and the binary basicity (CaO / SiO2) of the finished pellets is 0.7.

[0137] Experimental tests were conducted on the expansion rate of the pellets prepared as described above. The expansion rate of the pellets prepared by the method of reducing the expansion rate of pellets in Example 3 of this invention was 16.3%, which is fully suitable for large-scale blending in blast furnace ironmaking and is conducive to stable and smooth furnace operation.

[0138] Example 4

[0139] Example 4 of this invention mainly involves adding a certain proportion of finely ground rotary kiln agglomerates and iron flux slag to iron ore powder, followed by batching, pelletizing, roasting, and cooling to obtain finished pellets. Compared to the control example, in Example 1, the particle size of the pellets during pelletizing was adjusted from 8-16 mm to 9-13 mm, and the time for the pellets to pass through the preheating stage II during roasting was extended from 6 min to 8.7 min. Furthermore, compared to Example 3, the flux clinker used in Example 4 was increased from 19 parts by weight to 22 parts by weight. Specifically, Example 4 includes the following steps:

[0140] Step 1: Preparation of flux clinker

[0141] Weigh and mix the rotary kiln ring material and iron flux slag according to the following weight proportions, the specific ratio is as follows:

[0142] 20 portions of rotary kiln ring material

[0143] 80 parts of iron flux slag

[0144] The rotary kiln agglomerates are the lump-shaped agglomerates produced by the rotary kiln during the production of alkaline pellets using a chain grate-rotary kiln. Their main chemical components, by weight percentage, are: TFe 61.13%, FeO 0.93%, SiO2 5.5%, CaO 4.8%, MgO 0.6%, and Al2O3 1.6%. The iron flux slag is a lump-shaped iron-containing flux slag formed by sintering a mixture of iron ore powder from Taiyuan Iron & Steel Group's Lanxian County with other high-Al2O3 content mineral powders, quicklime, and coke powder. Its main chemical components, by weight percentage, are: TFe 44.4%, FeO 13.7%, SiO2 4.76%, CaO 27.62%, MgO 1.73%, and Al2O3 1.8%.

[0145] The rotary kiln ring material and iron flux slag after batching are mixed and ground in a ball mill to obtain flux clinker. The proportion of particles smaller than 0.044 mm in the flux clinker is 83%. The main chemical components of the flux clinker by weight percentage are: TFe 47.74%, FeO 11.14%, SiO2 4.91%, CaO 23.06%, MgO 1.5%, and Al2O3 1.76%.

[0146] Step 2: Ingredient Preparation

[0147] The flux clinker, limestone powder, iron ore powder, and bentonite are weighed and mixed according to the following weight proportions to obtain the mixed pelletizing material. The specific proportions are as follows:

[0148]

[0149] The iron ore powder is from Lanxian County, Shanxi Province, with 99.5% of the particles smaller than 0.044mm, an iron grade of 65.8%, and by weight percentage, the FeO content is 15.3%, the SiO2 content is 4.2%, the CaO content is 0.48%, and the moisture content is 10.7%. The bentonite is commercially available conventional bentonite, with 86% of the particles smaller than 0.074mm.

[0150] Step 3: Mix and form pellets

[0151] The above-mentioned mixed pelletizing material is mixed evenly by a high-power mixer, and then added to a disc pelletizer to supplement moisture and produce pellets. The moisture content of the pellets is controlled at 9.6% by weight, and the average particle size of the pellets is controlled at 9-13 mm.

[0152] Step 4: Calcination and Cooling

[0153] The pellets are fed and roasted on a chain grate rotary kiln. The roasted high-temperature pellets are then cooled by an annular cooler to obtain finished pellets. The temperature of the preheating section II of the chain grate is controlled at 1150℃, the time for the pellets to pass through the preheating section II is controlled at 8.7 min, and the temperature of the rotary kiln head is controlled at 1185℃. The main chemical components of the finished pellets by weight percentage are: TFe 63.3%, SiO2 4.75%, CaO 3.33%, MgO 0.85%, Al2O3 1.04%, and the binary basicity (CaO / SiO2) of the finished pellets is 0.7.

[0154] Experimental tests were conducted on the expansion rate of the pellets prepared as described above. The expansion rate of the pellets prepared by the method of reducing the expansion rate of pellets in Example 4 of this invention was 15.4%, which is fully suitable for large-scale blending in blast furnace ironmaking and is conducive to stable and smooth furnace operation.

[0155] Example 5

[0156] Example 5 of this invention mainly involves adding a certain proportion of finely ground rotary kiln agglomerates and iron flux slag to iron ore powder, followed by batching, pelletizing, roasting, and cooling to obtain finished pellets. Compared to the control example, in Example 1, the particle size of the pellets during pelletizing was adjusted from 8-16 mm to 9-13 mm, and the time for the pellets to pass through the preheating stage II during roasting was extended from 6 min to 8.7 min. Furthermore, compared to Example 4, the flux clinker used in Example 5 was increased from 22 parts by weight to 25 parts by weight. Specifically, Example 5 includes the following steps:

[0157] Step 1: Preparation of flux clinker

[0158] Weigh and mix the rotary kiln ring material and iron flux slag according to the following weight proportions, the specific ratio is as follows:

[0159] 20 portions of rotary kiln ring material

[0160] 80 parts of iron flux slag

[0161] The rotary kiln agglomerates are the lump-shaped agglomerates produced by the rotary kiln during the production of alkaline pellets using a chain grate-rotary kiln. Their main chemical components, by weight percentage, are: TFe 61.13%, FeO 0.93%, SiO2 5.5%, CaO 4.8%, MgO 0.6%, and Al2O3 1.6%. The iron flux slag is a lump-shaped iron-containing flux slag formed by sintering a mixture of iron ore powder from Taiyuan Iron & Steel Group's Lanxian County with other high-Al2O3 content mineral powders, quicklime, and coke powder. Its main chemical components, by weight percentage, are: TFe 44.4%, FeO 13.7%, SiO2 4.76%, CaO 27.62%, MgO 1.73%, and Al2O3 1.8%.

[0162] The rotary kiln ring material and iron flux slag after batching are mixed and ground in a ball mill to obtain flux clinker. The proportion of particles smaller than 0.044 mm in the flux clinker is 83%. The main chemical components of the flux clinker by weight percentage are: TFe 47.74%, FeO 11.14%, SiO2 4.91%, CaO 23.06%, MgO 1.5%, and Al2O3 1.76%.

[0163] Step 2: Ingredient Preparation

[0164] The flux clinker, limestone powder, iron ore powder, and bentonite are weighed and mixed according to the following weight proportions to obtain the mixed pelletizing material. The specific proportions are as follows:

[0165]

[0166] The iron ore powder is from Lanxian County, Shanxi Province, with 99.5% of the particles smaller than 0.044mm, an iron grade of 65.8%, and by weight percentage, the FeO content is 15.3%, the SiO2 content is 4.2%, the CaO content is 0.48%, and the moisture content is 10.7%. The bentonite is commercially available conventional bentonite, with 86% of the particles smaller than 0.074mm.

[0167] Step 3: Mix and form pellets

[0168] The above-mentioned mixed pelletizing material is mixed evenly by a high-power mixer, and then added to a disc pelletizer to supplement moisture and produce pellets. The moisture content of the pellets is controlled at 9.6% by weight, and the average particle size of the pellets is controlled at 9-13 mm.

[0169] Step 4: Calcination and Cooling

[0170] The pellets are fed and roasted on a chain grate rotary kiln. The roasted high-temperature pellets are then cooled by an annular cooler to obtain finished pellets. The temperature of the preheating section II of the chain grate is controlled at 1150℃, the time for the pellets to pass through the preheating section II is controlled at 8.7 min, and the temperature of the rotary kiln head is controlled at 1185℃. The main chemical components of the finished pellets by weight percentage are: TFe 63.28%, SiO2 4.75%, CaO 3.34%, MgO 0.85%, Al2O3 1.05%, and the binary basicity (CaO / SiO2) of the finished pellets is 0.7.

[0171] Experimental tests were conducted on the expansion rate of the pellets prepared as described above. The expansion rate of the pellets prepared by the method of reducing the expansion rate of pellets in Example 5 of this invention was 14.7%, which is fully suitable for large-scale blending in blast furnace ironmaking and is conducive to stable and smooth furnace operation.

[0172] Example 6

[0173] Example 6 of this invention mainly involves adding a certain proportion of finely ground rotary kiln agglomerates and iron flux slag to iron ore powder, followed by batching, pelletizing, roasting, and cooling to obtain finished pellets. Compared to the control example, in Example 1, the particle size of the pellets during pelletizing was adjusted from 8-16 mm to 9-13 mm, and the time for the pellets to pass through the preheating stage II during roasting was extended from 6 min to 8.7 min. Furthermore, compared to Example 5, the flux clinker used in Example 6 was increased from 25 parts by weight to 28 parts by weight. Specifically, Example 6 includes the following steps:

[0174] Step 1: Preparation of flux clinker

[0175] Weigh and mix the rotary kiln ring material and iron flux slag according to the following weight proportions, the specific ratio is as follows:

[0176] 20 portions of rotary kiln ring material

[0177] 80 parts of iron flux slag

[0178] The rotary kiln agglomerates are the lump-shaped agglomerates produced by the rotary kiln during the production of alkaline pellets using a chain grate-rotary kiln. Their main chemical components, by weight percentage, are: TFe 61.13%, FeO 0.93%, SiO2 5.5%, CaO 4.8%, MgO 0.6%, and Al2O3 1.6%. The iron flux slag is a lump-shaped iron-containing flux slag formed by sintering a mixture of iron ore powder from Taiyuan Iron & Steel Group's Lanxian County with other high-Al2O3 content mineral powders, quicklime, and coke powder. Its main chemical components, by weight percentage, are: TFe 44.4%, FeO 13.7%, SiO2 4.76%, CaO 27.62%, MgO 1.73%, and Al2O3 1.8%.

[0179] The rotary kiln ring material and iron flux slag after batching are mixed and ground in a ball mill to obtain flux clinker. The proportion of particles smaller than 0.044 mm in the flux clinker is 83%. The main chemical components of the flux clinker by weight percentage are: TFe 47.74%, FeO 11.14%, SiO2 4.91%, CaO 23.06%, MgO 1.5%, and Al2O3 1.76%.

[0180] Step 2: Ingredient Preparation

[0181] The flux clinker, limestone powder, iron ore powder, and bentonite are weighed and mixed according to the following weight proportions to obtain the mixed pelletizing material. The specific proportions are as follows:

[0182]

[0183] The iron ore powder is from Lanxian County, Shanxi Province, with 99.5% of the particles smaller than 0.044mm, an iron grade of 65.8%, and by weight percentage, the FeO content is 15.3%, the SiO2 content is 4.2%, the CaO content is 0.48%, and the moisture content is 10.7%. The bentonite is commercially available conventional bentonite, with 86% of the particles smaller than 0.074mm.

[0184] Step 3: Mix and form pellets

[0185] The above-mentioned mixed pelletizing material is mixed evenly by a high-power mixer, and then added to a disc pelletizer to supplement moisture and produce pellets. The moisture content of the pellets is controlled at 9.6% by weight, and the average particle size of the pellets is controlled at 9-13 mm.

[0186] Step 4: Calcination and Cooling

[0187] The pellets are fed and roasted on a chain grate rotary kiln. The roasted high-temperature pellets are then cooled by an annular cooler to obtain finished pellets. The temperature of the preheating section II of the chain grate is controlled at 1150℃, the time for the pellets to pass through the preheating section II is controlled at 8.7 min, and the temperature of the rotary kiln head is controlled at 1185℃. The main chemical components of the finished pellets by weight percentage are: TFe 63.26%, SiO2 4.75%, CaO 3.36%, MgO 0.85%, Al2O3 1.05%, and the binary basicity (CaO / SiO2) of the finished pellets is 0.7.

[0188] Experimental tests were conducted on the expansion rate of the pellets prepared as described above. The expansion rate of the pellets prepared by the method of reducing the expansion rate of pellets in Example 6 of this invention was 14.3%, which is fully suitable for large-scale blending in blast furnace ironmaking and is conducive to stable and smooth furnace operation.

[0189] Comparative analysis between the above embodiments and the control examples:

[0190] In Embodiment 1 of the present invention, 12 parts of a mixture of finely ground rotary kiln ring material and iron flux slag are added to iron ore powder. Then, after batching, pelletizing, roasting and cooling, finished pellets are obtained. During pelletizing, the particle size of the pellets is adjusted from 8-16 mm to 9-13 mm, and the time for the pellets to pass through the preheating stage II during roasting is extended from 6 min to 8.7 min. After roasting, the expansion rate of the finished pellets is 18.2%, which is 3.1 percentage points lower than the 21.3% of the prior art comparative example. This is suitable for large-scale blending in blast furnace ironmaking and is conducive to stable and smooth furnace operation.

[0191] In Embodiment 2 of the present invention, 16 parts of a mixture of finely ground rotary kiln ring material and iron flux slag are added to iron ore powder. Then, after batching, pelletizing, roasting and cooling, finished pellets are obtained. The expansion rate of the finished pellets is 17.5%, which is 3.8 percentage points lower than the 21.3% of the prior art comparative example. It is suitable for large-scale blending in blast furnace ironmaking and is conducive to stable and smooth furnace operation.

[0192] In Embodiment 3 of the present invention, 19 parts of a mixture of finely ground rotary kiln ring material and iron flux slag are added to iron ore powder. Then, after batching, pelletizing, roasting and cooling, finished pellets are obtained. The expansion rate of the finished pellets is 16.3%, which is 5 percentage points lower than the 21.3% of the prior art comparative example. It is suitable for large-scale use in blast furnace ironmaking and is conducive to stable and smooth furnace operation.

[0193] In Embodiment 4 of the present invention, 22 parts of a mixture of finely ground rotary kiln ring material and iron flux slag are added to iron ore powder. Then, after batching, pelletizing, roasting and cooling, finished pellets are obtained. The expansion rate of the finished pellets is 15.4%, which is 5.9 percentage points lower than the 21.3% of the prior art comparative example. It is suitable for large-scale blending in blast furnace ironmaking and is conducive to stable and smooth furnace operation.

[0194] In Embodiment 5 of the present invention, 25 parts of a mixture of finely ground rotary kiln ring material and iron flux slag are added to iron ore powder. Then, after batching, pelletizing, roasting and cooling, finished pellets are obtained. The expansion rate of the finished pellets is 14.7%, which is 6.6 percentage points lower than the 21.3% of the prior art comparative example. It is suitable for large-scale blending in blast furnace ironmaking and is conducive to stable and smooth furnace operation.

[0195] In Embodiment 6 of the present invention, 28 parts of a mixture of finely ground rotary kiln ring material and iron flux slag are added to iron ore powder. Then, after batching, pelletizing, roasting and cooling, finished pellets are obtained. The expansion rate of the finished pellets is 14.3%, which is 7 percentage points lower than the 21.3% of the prior art comparative example. It is suitable for large-scale blending in blast furnace ironmaking and is conducive to stable and smooth furnace operation.

[0196] In summary, compared with the prior art, the method of reducing the expansion rate of pellets in this invention involves adding a certain proportion of finely ground rotary kiln ring material and iron flux slag (i.e., flux clinker) to iron ore powder, followed by batching, pelletizing, roasting, and cooling to obtain finished pellets. This method solves the technical problem of the deterioration of the expansion rate of pellets when using finely ground limestone powder as flux and fine-grained iron ore powder as iron material in the production of alkaline pellets through a chain grate-rotary kiln. The expansion rate of the pellets is 14-19%, which is fully suitable for large-scale blending in blast furnace ironmaking and is conducive to stable and smooth furnace operation.

[0197] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method of reducing the expansion rate of a pellet, characterized by, It comprises the following steps: Step one, flux clinker preparation The rotary kiln ring material and iron flux slag are weighed and mixed according to the following weight ratio: the specific ratio is as follows: Rotary kiln ring material 20 parts Iron flux slag 80 parts The rotary kiln ring material and iron flux slag are mixed and ground in a ball mill to prepare flux clinker, and the proportion of particles with particle size less than 0.044mm in the flux clinker is controlled to be more than 70%; Step two, batching The flux clinker, limestone powder, iron ore powder and bentonite are weighed and mixed according to the following weight ratio to obtain mixed pelletizing material, and the specific ratio is as follows: Flux clinker 10~30 parts Limestone powder 40~55 parts Iron ore powder 920~980 parts Bentonite 9~15 parts Step three, mixing and balling The above mixed pelletizing material is mixed uniformly by a strong mixer, and then added to a disc balling machine to supplement water and produce pellets, the moisture content of the pellets is controlled to be 9.6% by weight percentage, and the average particle size of the pellets is controlled to be 9~13mm; Step four, roasting and cooling The pellets are distributed and roasted on a grate-kiln, and then the high-temperature pellets after roasting are cooled by a circular cooler to obtain finished pellet, wherein the temperature of the preheating II stage of the grate-kiln is controlled to be 1140~1160℃, the time of the pellets passing through the preheating II stage is controlled to be 7.3~9min, and the temperature of the rotary kiln head is controlled to be 1180~1200℃.

2. The method for reducing the expansion rate of pellet according to claim 1, characterized in that: The rotary kiln ring material is a ring material in the form of lump ore generated by the rotary kiln during the production of alkaline pellets by the grate-kiln, and its main chemical components are as follows by weight percentage: TFe 59~62%, FeO 0.5~1.5%, SiO2 4.0~6.5%, CaO 3.5~5.0%, MgO 0.3~0.8%, Al2O3 1.2~1.8%; The iron flux slag is an iron-containing flux slag in the form of lump ore formed by sintering of iron ore powder and other high Al2O3 content ore powder, lime and coke powder, and its main chemical components are as follows by weight percentage: TFe 43~50%, FeO 10~15%, SiO2 4.6~5.5%, CaO 23~30%, MgO 1.2~2.0%, Al2O3 1.0~2.0%.

3. The method for reducing the expansion rate of pellet according to claim 2, characterized in that: The content of particles with particle size less than 0.044mm in the iron ore powder is 99.5%, the iron grade of the iron ore powder is 65.8%, and the content of FeO, SiO2, CaO and water in the iron ore powder is 15.3%, 4.2%, 0.48% and 10.7% by weight percentage respectively; The proportion of particles with particle size less than 0.074mm in the bentonite is controlled to be 86%; The binary basicity of the finished pellet is 0.

7.

4. The method for reducing the expansion rate of pellet according to claim 1, characterized in that: In step one, the main chemical components of the rotary kiln ring-forming substance are as follows in percentage by weight: TFe 61.13%, FeO 0.93%, SiO2 5.5%, CaO 4.8%, MgO 0.6%, Al2O3 1.6%; the main chemical components of the iron flux slag are as follows in percentage by weight: TFe 44.4%, FeO 13.7%, SiO2 4.76%, CaO 27.62%, MgO 1.73%, Al2O3 1.8%; the proportion of particles with particle size less than 0.044 mm in the flux clinker is 83%; In step two, the weight ratio of the flux clinker, limestone powder, iron ore powder and bentonite is as follows: flux clinker 12 parts limestone powder 50 parts iron ore powder 928 parts bentonite 10 parts; In step four, the temperature of the preheating stage II of the chain grate machine is controlled at 1150℃, the time for the pellets to pass through the preheating stage II is controlled at 8.7 min, and the temperature of the rotary kiln head is controlled at 1185℃.

5. The method for reducing the expansion rate of pellets according to claim 1, characterized in that: In step one, the main chemical components of the rotary kiln ring-forming substance are as follows in percentage by weight: TFe 61.13%, FeO 0.93%, SiO2 5.5%, CaO 4.8%, MgO 0.6%, Al2O3 1.6%; the main chemical components of the iron flux slag are as follows in percentage by weight: TFe 44.4%, FeO 13.7%, SiO2 4.76%, CaO 27.62%, MgO 1.73%, Al2O3 1.8%; the proportion of particles with particle size less than 0.044 mm in the flux clinker is 83%; In step two, the weight ratio of the flux clinker, limestone powder, iron ore powder and bentonite is as follows: flux clinker 16 parts limestone powder 48 parts iron ore powder 926 parts bentonite 10 parts; In step four, the temperature of the preheating stage II of the chain grate machine is controlled at 1150℃, the time for the pellets to pass through the preheating stage II is controlled at 8.7 min, and the temperature of the rotary kiln head is controlled at 1185℃.

6. The method for reducing the expansion rate of pellets according to claim 1, characterized in that: In step one, the main chemical components of the rotary kiln ring-forming substance are as follows in percentage by weight: TFe 61.13%, FeO 0.93%, SiO2 5.5%, CaO 4.8%, MgO 0.6%, Al2O3 1.6%; the main chemical components of the iron flux slag are as follows in percentage by weight: TFe 44.4%, FeO 13.7%, SiO2 4.76%, CaO 27.62%, MgO 1.73%, Al2O3 1.8%; the proportion of particles with particle size less than 0.044 mm in the flux clinker is 83%; In step two, the weight ratio of the flux clinker, limestone powder, iron ore powder and bentonite is as follows: flux clinker 19 parts limestone powder 47 parts iron ore powder 924 parts bentonite 10 parts; In step four, the temperature of the grate preheating II section is controlled at 1150℃, the time for the pellets to pass through the preheating II section is controlled at 8.7min, and the temperature of the kiln head is controlled at 1185℃.

7. The method of claim 1, wherein: In step one, the main chemical components of the rotary kiln ring-forming substance are as follows in percentage by weight: TFe 61.13%, FeO 0.93%, SiO2 5.5%, CaO 4.8%, MgO 0.6%, and Al2O3 1.6%; the main chemical components of the iron flux slag are as follows in percentage by weight: TFe 44.4%, FeO 13.7%, SiO2 4.76%, CaO 27.62%, MgO 1.73%, and Al2O3 1.8%; and the proportion of particles with a size less than 0.044mm in the flux clinker is 83%; In step two, the flux clinker, limestone powder, iron ore powder, and bentonite are mixed in the following proportions by weight: Flux clinker 22 parts Limestone powder 46 parts Iron ore powder 922 parts Bentonite 10 parts In step four, the temperature of the grate preheating II section is controlled at 1150℃, the time for the pellets to pass through the preheating II section is controlled at 8.7min, and the temperature of the kiln head is controlled at 1185℃.

8. The method of claim 1, wherein: In step one, the main chemical components of the rotary kiln ring-forming substance are as follows in percentage by weight: TFe 61.13%, FeO 0.93%, SiO2 5.5%, CaO 4.8%, MgO 0.6%, and Al2O3 1.6%; the main chemical components of the iron flux slag are as follows in percentage by weight: TFe 44.4%, FeO 13.7%, SiO2 4.76%, CaO 27.62%, MgO 1.73%, and Al2O3 1.8%; and the proportion of particles with a size less than 0.044mm in the flux clinker is 83%; In step two, the flux clinker, limestone powder, iron ore powder, and bentonite are mixed in the following proportions by weight: Flux clinker 25 parts Limestone powder 44 parts Iron ore powder 921 parts Bentonite 10 parts In step four, the temperature of the grate preheating II section is controlled at 1150℃, the time for the pellets to pass through the preheating II section is controlled at 8.7min, and the temperature of the kiln head is controlled at 1185℃.

9. The method of claim 1, wherein: In step one, the main chemical components of the rotary kiln ring-forming substance are as follows in percentage by weight: TFe 61.13%, FeO 0.93%, SiO2 5.5%, CaO 4.8%, MgO 0.6%, and Al2O3 1.6%; the main chemical components of the iron flux slag are as follows in percentage by weight: TFe 44.4%, FeO 13.7%, SiO2 4.76%, CaO 27.62%, MgO 1.73%, and Al2O3 1.8%; and the proportion of particles with a size less than 0.044mm in the flux clinker is 83%; In step two, the weight ratio of fluxed sinter, limestone powder, iron ore powder and bentonite is as follows: Fluxed sinter 28 parts Limestone powder 43 parts Iron ore powder 919 parts Bentonite 10 parts In step four, the temperature of the preheating stage II of the chain grate is controlled at 1150℃, the time of the pellets passing through the preheating stage II is controlled at 8.7 min, and the temperature of the kiln head of the rotary kiln is controlled at 1185℃.

Images