Production method for producing low-alkalinity fluxed pellets from whole hematite limonite

Abstract

The invention discloses a production method for producing low-alkalinity fluxed pellets from whole hematite limonite, which comprises the following steps: taking flue gas treatment by-product desulfurized fly ash and carbon-containing dedusting ash, feeding into a first batching bin, blanking according to a first preset proportion, feeding into a powerful mixer, mixing, and rolling at high pressure to obtain a first mixture; performing dry grinding or wet grinding on the hematite and limonite coarse powder to obtain hematite and limonite fine powder; the first mixture, hematite and limonite fine powder and bentonite are blanked according to a second preset proportion, and a second mixture is obtained; carrying out strong mixing and high-pressure roller milling on the second mixture, and pelletizing to form green pellets; and the green pellets sequentially enter a forced air drying section, an air draft drying section, a preheating section and a roasting section of a belt type roasting machine, and finally the all-hematite limonite low-alkalinity fluxed pellets are obtained. The method has the advantages that the pulverization phenomenon caused by the low bursting temperature of the drying section can be eradicated, the quality of green pellets is improved in the drying section, conditions are provided for liquid phase generation in the preheating and roasting sections, and the compressive strength of pellets is remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of pellet production, and in particular to a production method for producing low-basicity flux pellets from whole hematite. Background Art

[0002] Semi-dry sintering flue gas desulfurization ash is a by-product produced in the iron ore flue gas desulfurization process, which mainly contains CaSO 3 (Mainly CaSO 3 0.5H 2 O exists), CaCO 3 、CaSO 4 , Ca(OH) 2 , Fe 2 O 3 etc. Due to CaSO 3 The instability of desulfurization ash makes it difficult to use. It is dumped and abandoned, which causes waste of resources, environmental pollution and occupation of land. At present, the desulfurization ash is modified and oxidized to prepare CaSO 4 Whiskers have achieved good results, but these utilization studies are still in the laboratory stage. In the production of whole hematite pellets, because of the high silicon content, generally silicon can reach 6-7%, the compressive strength of the pellets can be improved by adjusting the low alkalinity range of the pellets, but calcium-containing flux materials, such as metallurgical powder ash and slaked lime, are directly added to the pellets. Because the metallurgical powder ash needs to be digested or the slaked lime is not completely digested, large particles of calcium-containing materials appear in the pellets, causing the pellets to burst at a low temperature and easy to pulverize, resulting in a sharp decrease in the compressive strength of the finished pellets, and the low alkalinity range fails to improve the compressive strength of the whole hematite pellets. The adjustment of calcium-containing materials in the pellets can also be improved by the use of calcium-containing concentrate, but the variety of resources used is limited. Summary of the invention

[0003] The purpose of the present invention is to provide a production method for low-basicity flux pellets from whole hematite, which can prevent the phenomenon of pulverization caused by low bursting temperature in the drying stage, improve the quality of green balls in the drying stage, provide conditions for generating liquid phase in the preheating and roasting stages, and significantly improve the compressive strength of the pellets.

[0004] The above technical objectives of the present invention are achieved through the following technical solutions:

[0005] A method for producing low-basicity flux pellets from whole hematite, characterized in that it comprises the following steps:

[0006] The desulfurization ash and carbon-containing dust removal ash, which are byproducts after flue gas treatment, are taken into a first batching bin, fed according to a first predetermined ratio, mixed in a strong mixer, and rolled under high pressure to obtain a first mixture;

[0007] The coarse hematite powder is dry-milled or wet-milled to obtain the hematite concentrate;

[0008] The first mixture, hematite concentrate, and bentonite are added according to a second predetermined ratio to obtain a second mixture;

[0009] The second mixture is subjected to intensive mixing and high-pressure roller grinding to form green balls;

[0010] The raw balls enter the blast drying section, exhaust drying section, preheating section and roasting section of the belt roaster in sequence, and finally obtain the low-alkalinity flux pellets of full hematite.

[0011] Preferably, the first predetermined ratio of the first mixture is a mass ratio of desulfurization ash to gravity dust removal ash of 1:3.

[0012] Preferably, the first mixture has 1 / 3 of its mass diverted and circulated into the first batching bin through a plough-type distributor to be mixed with desulfurization ash and gravity dust removal ash.

[0013] Preferably, the desulfurized ash has a Ca content of no less than 28%, a S content of no more than 12%, a Cl content of less than 3.5%, a particle size of less than 0.5 mm, and a specific surface area of ​​no less than 2000 m 2 / kg.

[0014] Preferably, the fixed carbon in the gravity dust removal ash is not less than 28%, the Ca is not less than 4.5%, the particle size is required to be less than 0.5 mm and account for more than 95%, and the specific surface area is not less than 2000m 2 / kg.

[0015] Preferably, the first mixture has a Ca content of 10.4% with a deviation range of ±0.5%, and a carbon content of 21% with a deviation range of ±0.5%.

[0016] Preferably, the proportion of -200 mesh in the hematite concentrate is not less than 83%, and the specific surface area is not less than 1500cm 2 / g.

[0017] Preferably, the second predetermined ratio of the second mixture is: first mixed powder ≤ 4%: hematite concentrate ≥ 95.6%, bentonite ratio ≤ 0.4%, and the specific surface area of ​​the second mixture is 1700-2000cm 2 / g, the moisture content is controlled at 9.0%-9.5%, and the particle size range of raw balls is controlled at 8-12mm, accounting for more than 90%.

[0018] Preferably, the temperature of the blast drying section is 200-260°C, the temperature of the exhaust drying section is 300-380°C, the temperature of the preheating section is 950-1000°C, and the temperature of the roasting section is 1280-1300°C.

[0019] Preferably, the CaO / SiO in the low-basicity flux pellets of all-hematite is 2 Controlled ≤0.35, the silicon content of the pellets is greater than 6%, the compressive strength is greater than 2500N / P, the reduction expansion is less than 15%, and the reducibility is greater than 65%.

[0020] In summary, the present invention has the following beneficial effects:

[0021] 1. The desulfurization ash used in the present invention is a common byproduct of flue gas treatment in long-process enterprises. Carbon-containing dust removal ash is also a common byproduct of blast furnaces. It is generally used as a carbon-matching material for sintering. However, due to its fine particle size and short combustion time, it provides limited heat during the sintering process and is easily pumped to the sintering machine head for electrostatic dust removal. Through the pretreatment of carbon-containing dust removal ash and desulfurization ash, as a carbon-containing calcium additive for pellets, the desulfurization ash CaSO 3 The reaction is fine CaO and SO entering the flue gas. 2 and residual sulfide, among which fine CaO is generated in the preheating stage of pellets. After the green pellets are dried by blast drying and exhaust drying, fine CaO does not participate in H 2 O reacts directly with iron and silicon in the pellets to form a liquid phase, thereby improving the bonding phase strength of the pellets. This improves the effect of calcium-containing flux addition on pellet drying, preheating, roasting and other stages, and realizes the production method of applying desulfurized ash and carbon-containing ash pretreatment to the production of low-basicity flux pellets from all-limonite ore, improving the compressive strength of low-basicity flux pellets from all-limonite ore pellets.

[0022] 2. The present invention realizes the production method of pre-treatment of desulfurized ash and carbon-containing ash for producing low-basicity flux pellets from whole hematite. The by-products of flue gas treatment, desulfurized ash and carbon-containing dust removal ash, are fed in a certain proportion and mixed vigorously as carbon-containing calcium additives. The desulfurized ash and carbon-containing dust removal ash are pre-mixed to form carbon substances and CaSO in the desulfurized ash. 3 Mutually wrapped, some CaSO 3 Directly decomposes into fine CaO particles and SO in an anaerobic environment 2 , and another part of CaSO 3 Oxidation to form CaSO 4 The Gibbs free energy of the reaction formula of the carbon element in the carbon-containing dust is negative at the reaction temperature of the present invention, CaSO 4Due to the presence of reducing agent carbon, its decomposition temperature is greatly reduced, and it will be decomposed to form CaO, which will directly react with iron and silicon to form a liquid phase. The limonite is dry-ground or wet-ground to obtain limonite concentrate. The limonite concentrate, carbon-containing and calcium-containing additives, bentonite, etc. are fed in a certain proportion, vigorously mixed, and high-pressure roller milled to obtain a mixture. After disc balling, it enters the roasting machine for drying, preheating, roasting, and cooling to obtain full limonite low-alkalinity range flux pellets with performance that meets the requirements of blast furnaces.

[0023] 3. The present invention utilizes the coupling reaction of desulfurization ash, a byproduct of flue gas treatment, and carbon-containing dust ash, a byproduct of blast furnace, to generate fine CaO particles without participating in H 2 O reaction can significantly improve the compressive strength of the pellets, realizing the utilization of waste and the improvement of the compressive strength of the low-alkalinity flux pellets of all-limonite. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a flow chart of a production method for producing low-basicity flux pellets from whole hematite. DETAILED DESCRIPTION

[0025] The specific implementation manner of the present invention is further described below in conjunction with the accompanying drawings, and this embodiment does not constitute a limitation of the present invention.

[0026] like Figure 1 The method for producing low-basicity flux pellets from whole hematite ore comprises the following steps:

[0027] The desulfurization ash and carbon-containing dust removal ash, which are byproducts after flue gas treatment, are taken into a first batching bin, fed according to a first predetermined ratio, mixed in a strong mixer, and rolled under high pressure to obtain a first mixture;

[0028] The coarse hematite powder is dry-milled or wet-milled to obtain the hematite concentrate;

[0029] The first mixture, hematite concentrate, and bentonite are added according to a second predetermined ratio to obtain a second mixture;

[0030] The second mixture is subjected to intensive mixing and high-pressure roller grinding to form green balls;

[0031] The raw balls enter the blast drying section, exhaust drying section, preheating section and roasting section of the belt roaster in sequence, and finally obtain the low-alkalinity flux pellets of full hematite.

[0032] The first predetermined ratio of the first mixture is a mass ratio of desulfurization ash to gravity dust removal ash of 1:3.

[0033] The first mixture is diverted and circulated with 1 / 3 of its own mass through a plough-type distributor to the first batching bin to be mixed with desulfurization ash and gravity dust removal ash.

[0034] The Ca content of desulfurized ash should not be less than 28%, the S content should not be higher than 12%, the Cl content should be lower than 3.5%, the particle size should be less than 0.5 mm, accounting for more than 95%, and the specific surface area should not be less than 2000m 2 / kg.

[0035] The fixed carbon in the gravity dust removal ash components shall not be less than 28%, Ca shall not be less than 4.5%, the particle size shall be less than 0.5 mm and account for more than 95%, and the specific surface area shall not be less than 2000m 2 / kg.

[0036] The first mixture has a Ca content of 10.4% with a deviation range of ±0.5%, and a carbon content of 21% with a deviation range of ±0.5%.

[0037] The proportion of -200 mesh in the hematite concentrate is not less than 83%, and the specific surface area is not less than 1500cm 2 / g.

[0038] The second predetermined ratio of the second mixture is: first mixed powder ≤ 4%: hematite concentrate ≥ 95.6%, bentonite ratio ≤ 0.4%, and the specific surface area of ​​the second mixture is 1700-2000cm 2 / g, the moisture content is controlled at 9.0%-9.5%, and the particle size range of raw balls is controlled at 8-12mm, accounting for more than 90%.

[0039] The temperature of the blast drying section is 200-260°C, the temperature of the exhaust drying section is 300-380°C, the temperature of the preheating section is 950-1000°C, and the temperature of the roasting section is 1280-1300°C.

[0040] CaO / SiO in low basicity flux pellets of whole hematite 2 Controlled ≤0.35, the silicon content of the pellets is greater than 6%, the compressive strength is greater than 2500N / P, the reduction expansion is less than 15%, and the reducibility is greater than 65%.

[0041] Example 1

[0042] Desulfurization ash and carbon-containing dust removal ash are fed according to a first predetermined ratio, mixed in a strong mixer, and rolled under high pressure to obtain a first mixture, and 1 / 3 of the first mixture is diverted by a plow-type distributor and circulated to the first batching bin, and mixed according to the ratio of desulfurization ash to gravity dust removal ash = 1:3. The first mixture, hematite concentrate, and bentonite are fed according to a second predetermined ratio to obtain a second mixture. The second predetermined ratio is: 2.0% of the first mixed powder: 97.6% of hematite concentrate, and 0.4% of bentonite, as described in Table 1 below. After the second mixture is subjected to strong mixing and high-pressure roller grinding, its specific surface area is required to be controlled within a range of 1700-2000cm 2 / g, the moisture content of the second mixture is controlled at 9.0%, the particle size of the green balls is controlled at 8-12mm and the proportion is controlled to reach 90%. The green balls entering the belt roaster are required to have the following requirements: the temperature control range of the blast drying section is 200-260℃, the exhaust drying section is 300-380℃, the temperature control range of the preheating section is 950-1000℃, and the roasting temperature is 1280-1300℃. After the green balls are roasted in the belt roaster, the flux-oxidized pellets with low basicity range of full hematite are obtained. The CaO / SiO 2 =0.10, the compressive strength is above 2556N / P, the reduction expansion is 13.6%, and the reducibility is 69.7%, which meets the requirements of blast furnace smelting.

[0043] Table 1: Material ratios in Example 1

[0044] materials Ratio TFe C Feo <![CDATA[SiO 2 ]]> CaO MgO <![CDATA[Al 2 THE 3 ]]> Ig <![CDATA[H 2 THE<!-- 3 --> ]]> Hematite 97.6％ 62.56 2.34 6.18 0.05 0.12 1.70 5.64 8.12 Desulfurization ash 0.5％ 38.00 2.0 Gravity dust removal 1.5％ 45.85 28 6.38 4.74 0.98 4.08 2.1 Bentonite 0.4％ 62 2.8 3.2 14

[0045] Example 2

[0046] Desulfurization ash and carbon-containing dust removal ash are fed according to a first predetermined ratio, mixed in a strong mixer, and rolled under high pressure to obtain a first mixture, and 1 / 3 of the first mixture is diverted by a plow-type distributor and circulated to the first batching bin, and mixed according to the ratio of desulfurization ash to gravity dust removal ash = 1:3. The first mixture, hematite concentrate, and bentonite are fed according to a second predetermined ratio to obtain a second mixture. The second predetermined ratio is: 4.0% of the first mixed powder: 95.8% of hematite concentrate, and 0.2% of bentonite, as described in Table 2 below. After the second mixture is subjected to strong mixing and high-pressure roller grinding, its specific surface area is required to be controlled within a range of 1700-2000cm 2 / g, the moisture content of the second mixture is controlled at 9.0%, the particle size of the green balls is controlled at 8-12mm and the proportion is controlled to reach 90%. The green balls entering the belt roaster are required to have the following requirements: the temperature control range of the blast drying section is 200-260℃, the exhaust drying section is 300-380℃, the temperature control range of the preheating section is 950-1000℃, and the roasting temperature is 1280-1300℃. After the green balls are roasted in the belt roaster, the flux-oxidized pellets with low basicity range of full hematite are obtained. The CaO / SiO 2 =0.15, the compressive strength is above 2566N / P, the reduction expansion is 13.1%, and the reducibility is 68.2%, which meets the requirements of blast furnace smelting.

[0047] Table 2: Material ratios in Example 2

[0048] materials Ratio TFe C Feo <![CDATA[SiO 2 ]]> CaO MgO <![CDATA[Al 2 THE 3 ]]> Ig <![CDATA[H 2 The]]> Hematite 95.8％ 62.56 2.34 6.18 0.05 0.12 1.70 5.64 8.12 Desulfurization ash 1.0％ 38.00 2.0 Gravity dust removal 3.0％ 45.85 28 6.38 4.74 0.98 4.08 2.1 Bentonite 0.2％ 62 2.8 3.2 14

[0049] Example 3

[0050] Desulfurized ash and carbonaceous dust ash are fed according to a first predetermined ratio, mixed in a strong mixer, and rolled under high pressure to obtain a first mixture, and 1 / 3 of the first mixture is diverted by a plow-type distributor and circulated to the first batching bin, and mixed according to the ratio of desulfurized ash to gravity dust ash = 1:3. The first mixture, hematite concentrate, and bentonite are fed according to a second predetermined ratio to obtain a second mixture. The second predetermined ratio is: 2.0% of the first mixed powder: 97.6% of hematite concentrate, and 0.4% of bentonite, as described in Table 3 below. After the second mixture is subjected to strong mixing and high-pressure roller grinding, its specific surface area is required to be controlled within a range of 1700-2000cm 2 / g, the moisture content of the second mixture is controlled at 9.8%, the particle size of the green balls is controlled at 8-12mm and the proportion is controlled to reach 90%. The green balls entering the belt roaster are required to have the following requirements: the temperature control range of the blast drying section is 200-260℃, the exhaust drying section is 300-380℃, the temperature control range of the preheating section is 950-1000℃, and the roasting temperature is 1280-1300℃. After the green balls are roasted in the belt roaster, the flux-oxidized pellets with low basicity range of full hematite are obtained. The CaO / SiO 2 =0.10, the compressive strength is above 2321N / P, the reduction expansion is 14.7%, and the reducibility is 69.4%, and the compressive strength is low.

[0051] Table 3: Material ratios in Example 3

[0052] materials Ratio TFe C Feo <![CDATA[SiO 2 ]]> CaO MgO <![CDATA[Al 2 THE 3 ]]> Ig <![CDATA[H 2 The]]> Hematite 97.6％ 62.56 2.34 6.18 0.05 0.12 1.70 5.64 8.12 Desulfurization ash 0.5％ 38.00 2.0 Gravity dust removal 1.5％ 45.85 28 6.38 4.74 0.98 4.08 2.1 Bentonite 0.4％ 62 2.8 3.2 14

[0053] Example 4

[0054] Desulfurization ash and carbon-containing dust removal ash are fed according to a first predetermined ratio, mixed in a strong mixer, and rolled under high pressure to obtain a first mixture, and 1 / 3 of the first mixture is diverted by a plow-type distributor and circulated to the first batching bin, and mixed according to the ratio of desulfurization ash to gravity dust removal ash = 1:3. The first mixture, hematite concentrate, and bentonite are fed according to a second predetermined ratio to obtain a second mixture. The second predetermined ratio is: 4.0% of the first mixed powder: 95.8% of hematite concentrate, and 0.2% of bentonite, as described in Table 4 below. After the second mixture is subjected to strong mixing and high-pressure roller grinding, its specific surface area is required to be controlled within a range of 1700-2000cm 2 / g, the moisture content of the second mixture is controlled at 9.0%, the particle size of the green balls is controlled at 8-12mm and the proportion reaches 82%. The green balls entering the belt roaster are required to have the following requirements: the temperature of the blast drying section is controlled at 200-260℃, the exhaust drying section is controlled at 300-380℃, the temperature of the preheating section is controlled at 950-1000℃, and the roasting temperature is 1280-1300℃. After the green balls are roasted in the belt roaster, the flux-oxidized pellets with low basicity range of full hematite are obtained. The CaO / SiO 2=0.15, the compressive strength is above 2167N / P, the reduction expansion is 15.7%, and the reducibility is 69.1%. The compressive strength is low and the expansion is high.

[0055] Table 4: Material ratios in Example 4

[0056] materials Ratio TFe C Feo <![CDATA[SiO 2 ]]> CaO MgO <![CDATA[Al 2 THE 3 ]]> Ig <![CDATA[H 2 The]]> Hematite 95.8％ 62.56 2.34 6.18 0.05 0.12 1.70 5.64 8.12 Desulfurization ash 1.0％ 38.00 2.0 Gravity dust removal 3.0％ 45.85 28 6.38 4.74 0.98 4.08 2.1 Bentonite 0.2％ 62 2.8 3.2 14

[0057] Comparative Example 1

[0058] Desulfurization ash, hematite concentrate, and bentonite are fed according to the predetermined ratio: desulfurization ash 0.5%: hematite concentrate 99.1%, bentonite ratio: 0.4%, as shown in Table 5 below. After the mixture is vigorously mixed and high-pressure roller milled, its specific surface area is required to be controlled within the range of 1700-2000cm 2 / g, the moisture content of the second mixture is controlled at 9.0%, the particle size of the green balls is controlled at 8-12mm and the proportion is controlled to reach 90%. The green balls entering the belt roaster are required to have the following requirements: the temperature control range of the blast drying section is 200-260℃, the exhaust drying section is 300-380℃, the temperature control range of the preheating section is 950-1000℃, and the roasting temperature is 1280-1300℃. After the green balls are roasted in the belt roaster, the flux-oxidized pellets with low basicity range of full hematite are obtained. The CaO / SiO 2 =0.08, the compressive strength is above 2088N / P, the reduction expansion is 15.2%, and the reducibility is 69.9%, and the compressive strength is low.

[0059] Table 4: Ratio of materials in Comparative Example 1

[0060] materials Ratio TFe C Feo <![CDATA[SiO 2 ]]> CaO MgO <![CDATA[Al 2 THE 3 ]]> Ig <![CDATA[H 2 The]]> Hematite 99.1％ 62.56 2.34 6.18 0.05 0.12 1.70 5.64 8.12 Desulfurization ash 0.5％ 38.00 2.0 Gravity dust removal 0 45.85 28 6.38 4.74 0.98 4.08 2.1 Bentonite 0.4％ 62 2.8 3.2 14

[0061] Comparative Example 2

[0062] Gravity dust ash, hematite concentrate and bentonite are fed in a predetermined ratio: 1.5% gravity dust ash: 98.1% hematite concentrate, 0.4% bentonite. After the mixture is vigorously mixed and high-pressure roller milled, its specific surface area is required to be controlled within the range of 1700-2000cm 2 / g, the moisture content of the second mixture is controlled at 9.0%, the particle size of the green balls is controlled at 8-12mm and the proportion is controlled to reach 90%. The green balls entering the belt roaster are required to have the following requirements: the temperature control range of the blast drying section is 200-260℃, the exhaust drying section is 300-380℃, the temperature control range of the preheating section is 950-1000℃, and the roasting temperature is 1280-1300℃. After the green balls are roasted in the belt roaster, the flux-oxidized pellets with low basicity range of full hematite are obtained. The CaO / SiO 2=0.08, the compressive strength is above 2237N / P, the reduction expansion is 14.9%, and the reducibility is 67.3%, and the compressive strength is low.

[0063] Table 5: Ratio of materials in comparative example 2

[0064]

[0065]

[0066] The desulfurization ash used in the present invention is a common byproduct of flue gas treatment in long-process enterprises. Carbon-containing dust removal ash is also a common byproduct of blast furnaces. It is generally used as a carbon-matching material for sintering. However, due to its fine particle size and short combustion time, it provides limited heat during the sintering process and is easily pumped to the sintering head for electrostatic dust removal. Through the pretreatment of carbon-containing dust removal ash and desulfurization ash, as a carbon-containing calcium additive for pellets, the desulfurization ash CaSO 3 The reaction is fine CaO and SO entering the flue gas. 2 and residual sulfide, among which fine CaO is generated in the preheating stage of pellets. After the green pellets are dried by blast drying and exhaust drying, fine CaO does not participate in H 2 O reacts directly with iron and silicon in the pellets to form a liquid phase, thereby improving the bonding phase strength of the pellets. This improves the effect of calcium-containing flux addition on pellet drying, preheating, roasting and other stages, and realizes the production method of applying desulfurized ash and carbon-containing ash pretreatment to the production of low-basicity flux pellets from all-limonite ore, improving the compressive strength of low-basicity flux pellets from all-limonite ore pellets.

[0067] The present invention realizes the production method of low-basicity flux pellets produced by pre-treating desulfurized ash and carbon-containing ash for all-limonite ore. The by-products of flue gas treatment, desulfurized ash and carbon-containing dust removal ash, are fed in a certain proportion and strongly mixed as carbon-containing and calcium-containing additives. The desulfurized ash and carbon-containing dust removal ash are pre-mixed to form carbon substances and CaSO in the desulfurized ash. 3 Mutually wrapped, some CaSO 3 Directly decomposes into fine CaO particles and SO in an anaerobic environment 2 , and another part of CaSO 3 Oxidation to form CaSO 4 The Gibbs free energy of the reaction formula of the carbon element in the carbon-containing dust is negative at the reaction temperature of the present invention, CaSO 4Due to the presence of reducing agent carbon, its decomposition temperature is greatly reduced, and it will be decomposed to form CaO, which will directly react with iron and silicon to form a liquid phase. The limonite is dry-ground or wet-ground to obtain limonite concentrate. The limonite concentrate, carbon-containing and calcium-containing additives, bentonite, etc. are fed in a certain proportion, vigorously mixed, and high-pressure roller milled to obtain a mixture. After disc balling, it enters the roasting machine for drying, preheating, roasting, and cooling to obtain full limonite low-alkalinity range flux pellets with performance that meets the requirements of blast furnaces.

[0068] The present invention utilizes the coupling reaction of desulfurization ash, a byproduct of flue gas treatment, and carbon-containing dust removal ash, a byproduct of blast furnace, to generate fine CaO particles without participating in H 2 O reaction can significantly improve the compressive strength of the pellets, realizing the utilization of waste and the improvement of the compressive strength of the low-alkalinity flux pellets of all-limonite.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art may make various modifications or equivalent substitutions to the present invention within the essence and protection scope of the present invention, and such modifications or equivalent substitutions should also be deemed to fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for producing low-basicity flux pellets from whole hematite, characterized in that: The steps include: The desulfurization ash and carbon-containing dust removal ash, which are byproducts after flue gas treatment, are taken into a first batching bin, fed according to a first predetermined ratio, mixed in a strong mixer, and rolled under high pressure to obtain a first mixture; The coarse hematite powder is dry-milled or wet-milled to obtain the hematite concentrate; The first mixture, hematite concentrate, and bentonite are added according to a second predetermined ratio to obtain a second mixture; The second mixture is subjected to intensive mixing and high-pressure roller grinding to form green balls; The raw balls enter the blast drying section, exhaust drying section, preheating section and roasting section of the belt roaster in sequence, and finally obtain the low-alkalinity flux pellets of full hematite.

2. The method for producing low-basicity flux pellets from whole hematite according to claim 1, characterized in that: The first predetermined ratio of the first mixture is a mass ratio of desulfurization ash to gravity dust removal ash of 1:

3.

3. The method for producing low-basicity flux pellets from whole hematite according to claim 1, characterized in that: The first mixture is diverted and circulated to the first batching bin through a plough-type distributor to have 1 / 3 of its own mass mixed with desulfurization ash and gravity dust removal ash.

4. The method for producing low-basicity flux pellets from whole hematite according to claim 1, characterized in that: The desulfurized ash has a Ca content of no less than 28%, a S content of no more than 12%, a Cl content of less than 3.5%, a particle size of less than 0.5 mm, and a specific surface area of ​​no less than 2000 m 2 / kg.

5. The method for producing low-basicity flux pellets from whole hematite according to claim 1, characterized in that: The fixed carbon in the gravity dust removal ash is not less than 28%, the Ca is not less than 4.5%, the particle size is required to be less than 0.5 mm and account for more than 95%, and the specific surface area is not less than 2000m 2 / kg.

6. The method for producing low-basicity flux pellets from whole hematite according to claim 1, characterized in that: The first mixture has a Ca content of 10.4% with a deviation range of ±0.5%, and a carbon content of 21% with a deviation range of ±0.5%.

7. The method for producing low-basicity flux pellets from whole hematite according to claim 1, characterized in that: The proportion of -200 mesh in the hematite concentrate is not less than 83%, and the specific surface area is not less than 1500cm 2 / g.

8. The method for producing low-basicity flux pellets from whole hematite according to claim 1, characterized in that: The second predetermined ratio of the second mixture is: first mixed powder ≤ 4%: hematite concentrate ≥ 95.6%, bentonite ratio ≤ 0.4%, and the specific surface area of ​​the second mixture is 1700-2000cm 2 / g, the moisture content is controlled at 9.0%-9.5%, and the particle size range of raw balls is controlled at 8-12mm, accounting for more than 90%.

9. The method for producing low-basicity flux pellets from whole hematite according to claim 1, characterized in that: The temperature of the blast drying section is 200-260°C, the temperature of the exhaust drying section is 300-380°C, the temperature of the preheating section is 950-1000°C, and the temperature of the roasting section is 1280-1300°C.

10. The method for producing low-basicity flux pellets from whole hematite according to claim 1, characterized in that: The CaO / SiO2 in the all-hematite low-alkalinity flux pellets is controlled to be ≤0.35, the silicon content of the pellets is greater than 6%, the compressive strength is greater than 2500N / P, the reduction expansion is less than 15%, and the reducibility is greater than 65%.

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