CN110904334A - Preparation method of iron ore pellets - Google Patents

Preparation method of iron ore pellets Download PDF

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Publication number
CN110904334A
CN110904334A CN201911104426.0A CN201911104426A CN110904334A CN 110904334 A CN110904334 A CN 110904334A CN 201911104426 A CN201911104426 A CN 201911104426A CN 110904334 A CN110904334 A CN 110904334A
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pellets
powder
iron ore
magnesium
content
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Inventor
朱德俊
范晓慧
陈许玲
甘敏
季志云
张海峰
翁兴洋
于军
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Ansteel Mining Co Ltd
Angang Group Mining Co Ltd
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Angang Group Mining Co Ltd
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    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22BPRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00Preliminary treatment of ores or scrap
    • C22B1/14Agglomerating; Briquetting; Binding; Granulating
    • C22B1/24Binding; Briquetting ; Granulating
    • C22B1/242Binding; Briquetting ; Granulating with binders
    • C22B1/243Binding; Briquetting ; Granulating with binders inorganic
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22BPRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00Preliminary treatment of ores or scrap
    • C22B1/14Agglomerating; Briquetting; Binding; Granulating
    • C22B1/24Binding; Briquetting ; Granulating
    • C22B1/2406Binding; Briquetting ; Granulating pelletizing

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Geology (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Abstract

The invention relates to a preparation method of iron ore pellets, which is characterized in that raw materials for manufacturing the iron ore pellets comprise mixed iron powder, a magnesium additive, a calcium-containing additive and bentonite, the mixed ore powder is prepared from hematite concentrate and magnetite concentrate according to the mass percentage, and the mixed ore powder of the hematite concentrate and the magnetite concentrate meets the following technical indexes: the TFe content is more than 66 percent, and the fraction content of-0.074 mm is more than or equal to 80 percent. The invention has the advantages that: the technological parameters are close to those of the acid pellets, the alkalinity of the pellets is 0.2-0.4, the MgO content is 1.0-2.0%, the compressive strength is more than 2500N/P, the low-temperature reduction expansion rate is less than 10%, the reduction degree is more than 75%, and the dropping temperature is more than 1300 ℃.

Description

Preparation method of iron ore pellets
Technical Field
The invention belongs to the technical field of iron-making furnace burden preparation of a blast furnace in ferrous metallurgy, and particularly relates to a preparation method of iron ore pellets.
Background
The pellet has the characteristics of high iron grade, uniform granularity, good strength and the like, and is a high-quality blast furnace iron-making furnace charge. The domestic blast furnace iron making basically adopts a furnace burden structure of more than 70 percent of high-alkalinity high-magnesium sintering ore (R is more than 1.8, MgO is more than 2 percent), less than 25 percent of acid pellet ore (natural alkalinity R is less than 0.1 and MgO is less than 0.5 percent) and 5 to 15 percent of lump ore, and the furnace burden structure has the following disadvantages under the conditions of the current high-iron low-silicon raw materials: (1) the MgO content in the sintering ore is too high, the strength of the sintering ore is reduced, and the fuel consumption is increased; (2) the acid pellets have the defects of poor reducibility, low reflow temperature and the like, and have great difference with the performance of sintering ore metallurgy; (3) the whole melting section of the blast furnace is wide, the air permeability is poor, the energy consumption is high, and the utilization coefficient is low. However, under the current economic situation and environmental protection pressure conditions, it is difficult to greatly adjust the productivity and charging ratio of the sintered ore and the pellet ore in a short time. Therefore, on the basis of a typical blast furnace burden structure, the flux in the sintered ore is transferred to the pellet ore, the metallurgical performance of the pellet ore is optimized, the difference of the metallurgical performance of the pellet ore and the sintered ore is reduced, and the method has important significance for further improving the technical and economic indexes of the blast furnace.
Numerous studies have shown that: the MgO content of the pellet ore is improved by adopting magnesium-iron-containing concentrate, magnesium-rich bentonite, a magnesian binder, magnesia powder, forsterite and the like, the reduction expansion rate of the pellet ore can be reduced, and the softening temperature is improved; however, no matter magnesium-iron-containing concentrate is adopted and added with a magnesium binder or an additive, the strength of the preheated pellet and the roasted pellet is obviously reduced along with the increase of the MgO content of the pellet, the proper roasting temperature of the pellet is increased, the interval is narrowed, and the difficulty in pellet production is increased. The high-pressure roller milling or wet milling pretreatment is adopted, so that the specific surface area of the pellet raw material can be increased, the green pellet strength is improved, the pellet consolidation is strengthened, but the green pellet bursting temperature is reduced, the pellet powder amount is increased, a process link needs to be added, the energy consumption of the pretreatment process is high, and the comprehensive cost is high. The boron-containing additive can be used for strengthening the magnesium pellet consolidation, but the reduction expansion of the pellets is aggravated; the calcium-containing additive can generate a certain amount of liquid phase to improve the strength of the pellets, but can change the alkalinity of the pellets, and needs to improve the charging proportion of the pellets or reduce the alkalinity of the sinter, thus breaking through the original blast furnace burden balance system.
Disclosure of Invention
Aiming at the problems of low softening temperature, low strength of magnesium pellets, high production operation difficulty, easy ring formation of alkaline pellets, high reduction expansion rate, high required charging proportion and the like of the existing acidic pellets, the invention aims to provide a preparation method of iron ore pellets with high strength and good metallurgical performance, and components (TFe, CaO, MgO, SiO) of the pellets are regulated and controlled by a calcium-containing additive and a magnesium-containing additive on the basis of basically not regulating pellet production process configuration and blast furnace burden structure2) The method has the advantages of improving the metallurgical performance of the pellet while ensuring the strength of the pellet, reducing the difference of the metallurgical performance of the pellet and the sinter and improving the smelting index of the blast furnace comprehensive burden.
The purpose of the invention is realized by the following technical scheme:
the preparation method of the iron ore pellets is characterized in that raw materials for manufacturing the iron ore pellets comprise mixed iron powder, a magnesium additive, a calcium-containing additive and bentonite, the mixed ore powder is prepared from hematite concentrate and magnetite concentrate according to the mass percentage, and the mixed ore powder of the hematite concentrate and the magnetite concentrate meets the following technical indexes: the TFe content is more than 66 percent, and the fraction content of-0.074 mm is more than or equal to 80 percent.
The preparation method of the iron ore pellets is characterized by comprising the following steps of:
step 1) mixing mineral powder: according to the mass percentage, the hematite concentrate is 25-35: 75-65;
step 2) batching: mixing the mixed mineral powder obtained in the step (1) with bentonite, a magnesium-containing additive and a calcium-containing additive according to a certain proportion, wherein the magnesium-containing additive is one of magnesia powder, magnesite or dolomite, and the grain size of the magnesia powder, the magnesite and the dolomite is-0.074 mm, and the grain fraction content of the magnesia powder, the magnesite and the dolomite is more than or equal to 80%;
step 3), pelletizing: uniformly mixing the raw materials in the step 2) by a mixer, adding the mixture into a disc pelletizer, and adding water according to the water content of 8.5-9.5% to prepare green pellets;
step 4), drying and roasting: drying, preheating, roasting and cooling the green pellets prepared in the step 3) on a chain grate machine, a rotary kiln and a circular cooler to obtain finished pellet ore.
As a further optimization of the invention, the MgO content in the magnesium oxide powder is more than or equal to 82 percent, and when magnesium oxide powder is adopted as the magnesium-containing additive, the magnesium oxide powder is added according to the mass ratio of 93.0 to 96.4 percent of mixed mineral powder, 1.2 percent of bentonite, 0.7 to 2.0 percent of magnesium oxide powder and 1.7 to 3.8 percent of limestone.
As a further optimization of the invention, the MgO content in the magnesite is more than or equal to 42 percent, and when the magnesium-containing additive adopts magnesite, the magnesite is added according to the mass ratio of 90.5 to 95.3 percent of mixed mineral powder, 1.2 percent of bentonite, 1.5 to 3.8 percent of magnesite and 2.0 to 4.5 percent of limestone.
As a further optimization of the invention, the MgO content in the dolomite is more than or equal to 20 percent, and when the magnesium-containing additive adopts the dolomite, the dolomite is added according to the mass ratio of 90.8 to 95.5 percent of mixed mineral powder, 1.2 percent of bentonite and 3.2 to 8.0 percent of dolomite.
As a further optimization of the invention, in the step 3), the green pellets are subjected to forced air drying at 200-300 ℃ for 1.5min, induced draft drying at 300-400 ℃ for 3.5min, preheating at 900-1000 ℃ for 7.5-10min in sequence on a chain grate machine to obtain the preheated pellets.
As further optimization of the invention, the obtained preheated pellets are roasted in a rotary kiln at 1250-1300 ℃ for 10-15 min to obtain roasted pellets, and the roasted pellets are cooled to obtain iron ore pellets with the MgO content of 1.0-2.0%, the compressive strength of 2500N/P, the low-temperature reduction expansion rate of 10%, the reduction degree of 75% and the dropping temperature of 1300 ℃.
Compared with the prior art, the invention has the advantages that:
(1) reduction degree of acid pellet in prior art<70% dropping temperature<1250 ℃; compression strength of magnesium pellet (MgO1.0% -2.0%) roasted ball<2200N/P, high pellet energy consumption, easy ring formation of the rotary kiln and high production and operation difficulty. The technological parameters of the pellet production are close to those of acid pellets, and the obtained pellets have the MgO content of 1.0-2.0 percent and the MgO/SiO content20.15-0.3 of CaO/SiO20.2-0.4; compressive strength>2500N/P, low temperature reduction expansion ratio<10% reduction degree>75% dropping temperature>1300℃。
(2) In the prior art, the rotary kiln for alkaline pellets (R0.8-1.2) is easy to form rings, the reduction expansion rate is more than 15 percent, and the charging proportion of the pellets is more than 40 percent; on the premise that the charging proportion of the pellet is improved by 3-5% (less than or equal to 30%), the alkalinity of the sinter is unchanged, the MgO content of the sinter is reduced from more than 2.0% to 1.5-1.8%, and the strength of the sinter is indirectly improved; the metallurgical performance of the comprehensive furnace charge is improved under the condition that the structure of the blast furnace charge is not changed much.
Detailed Description
The present invention will be further described with reference to examples and comparative examples.
1. Physicochemical Properties of the respective raw materials used in examples and comparative examples
The raw materials of the pellets used in the examples and the comparative examples are mixed mineral powder of hematite concentrate and magnetite concentrate, and the binders of the pellets are bentonite, magnesia powder, magnesite, dolomite and limestone. The physical and chemical properties of each raw material are shown in Table 1.
TABLE 1 physicochemical Properties of the various raw materials
Figure BDA0002270845150000031
Figure BDA0002270845150000041
2. Concentrate proportioning and process parameters of examples and comparative examples
Mixing mineral powder: the pellet raw material is iron ore concentrate, and the iron ore concentrate is hematite according to the mass ratio: mixing magnetite ore in the ratio of 30 to 70 to prepare mixed mineral powder;
the pelletizing process parameters are as follows: the green ball has the water content of 8.5-9.5%, the pelletizing time is 10min, and the disc rotating speed is 23 r/min;
the thermal parameters are as follows: blowing and drying at 200-300 deg.C for 1.5min, blowing and drying at 300-400 deg.C for 3.5min, preheating at 900-1000 deg.C for 7.5-10min, and calcining at 1250-1300 deg.C for 10 min; and cooling to obtain the pellet.
3. Pellet composition of examples and comparative examples
The pellet raw materials used in the embodiment and the comparative example are hematite concentrate and magnetite concentrate, and the pellet binder is bentonite; the magnesium-containing additive of the pellets in the embodiment is one of magnesia powder, magnesite and dolomite, and the calcium-containing additive is limestone; the acid pellet comparative example has no other additives except for iron ore concentrate and bentonite; the calcium-containing additive of the alkaline pellet comparative example is limestone; the magnesium-containing additive of the magnesian pellets is magnesia powder.
The invention provides three comparative examples of acid pellets, alkaline pellets and magnesian pellets as comparison references, wherein the addition ratios of magnesium-containing additives, namely magnesia powder, magnesite, dolomite and calcium-containing additives, limestone in the comparative examples and the examples are shown in Table 2.
TABLE 2 different types of pellet compositions
Figure BDA0002270845150000042
4. Comparative analysis of technical indexes of pellet products of examples and comparative examples
GB/T13240-91 is adopted to detect the reduction and expansion performance of the pellet, GB/T13241-91 is adopted to detect the reduction performance of the pellet, and GB/T34211-2017 is adopted to detect the reflow performance of the pellet. The technical indexes of the pellets of the examples and comparative examples of the present invention are shown in Table 3.
TABLE 3 comparison of different types of pellet indexes
Figure BDA0002270845150000051
As can be seen from tables 2 and 3, the basic pellets had low green strength and high reduction swell ratio; the strength of the baked magnesia pellet is low; the pellet obtained by the 3 examples of the invention has high strength and good metallurgical performance, and is more matched with the metallurgical performance (the reduction degree is 89.5%, the dropping temperature is 1450 ℃, and the soft melting range is 274 ℃) of the sinter ore (the alkalinity is 2.0).

Claims (7)

1. The preparation method of the iron ore pellets is characterized in that raw materials for manufacturing the iron ore pellets comprise mixed iron powder, a magnesium additive, a calcium-containing additive and bentonite, the mixed mineral powder is prepared from hematite concentrate and magnetite concentrate according to the mass percentage, and the mixed mineral powder of the hematite concentrate and the magnetite concentrate meets the following technical indexes: the TFe content is more than 66 percent, and the fraction content of-0.074 mm is more than or equal to 80 percent.
2. The method for manufacturing iron ore pellets according to claim 1, characterized by comprising the steps of:
step 1) mixing mineral powder: according to the mass percentage, the hematite concentrate is 25-35: 75-65;
step 2) batching: mixing the mixed mineral powder obtained in the step 1) with bentonite, a magnesium-containing additive and a calcium-containing additive according to a certain proportion, wherein the magnesium-containing additive is one of magnesia powder, magnesite or dolomite, and the grain size of the magnesia powder, the magnesite and the dolomite is-0.074 mm, and the grain size content of the magnesia powder, the magnesite and the dolomite is more than or equal to 80%;
step 3), pelletizing: uniformly mixing the raw materials in the step 2) by a mixer, adding the mixture into a disc pelletizer, and adding water according to the water content of 8.5-9.5% to prepare green pellets;
step 4), drying and roasting: drying, preheating, roasting and cooling the green pellets prepared in the step 3) on a chain grate machine, a rotary kiln and a circular cooler to obtain finished pellet ore.
3. The method for preparing iron ore pellets according to claim 1, wherein the MgO content in the magnesium oxide powder is not less than 82%, and when magnesium oxide powder is used as the magnesium-containing additive, the magnesium oxide powder is added according to the mass ratio of-93.0% to 96.4% of mixed ore powder, 1.2% of bentonite, 0.7% to 2.0% of magnesium oxide powder and 1.7% to 3.8% of limestone.
4. The method for preparing the iron ore pellets as claimed in claim 1, wherein the content of MgO in the magnesite is not less than 42%, and when the magnesium-containing additive is magnesite, the magnesite is added according to the mass ratio of 90.5% -95.3% of mixed mineral powder, 1.2% of bentonite, 1.5% -3.8% of magnesite and 2.0% -4.5% of limestone.
5. The method for preparing iron ore pellets as claimed in claim 1, wherein the content of MgO in dolomite is not less than 20%, and when the magnesium-containing additive is dolomite, the dolomite is added in a mass ratio of 90.8-95.5% of mixed ore powder, 1.2% of bentonite, and 3.2-8.0% of dolomite.
6. The method for preparing iron ore pellets as claimed in claim 1, wherein in the step (3), the green pellets are subjected to forced air drying at 200-300 ℃ for 1.5min, induced draft drying at 300-400 ℃ for 3.5min, preheating at 900-1000 ℃ for 7.5-10min in sequence by a chain grate machine to obtain preheated pellets.
7. The method for preparing iron ore pellets according to claim 6, characterized in that the obtained preheated pellets are roasted in a rotary kiln at 1250-1300 ℃ for 10-15 min to obtain roasted pellets, and the roasted pellets are cooled to obtain iron ore pellets with MgO content of 1.0-2.0%, compressive strength of 2500N/P, low-temperature reduction expansion rate of less than 10%, reduction degree of 75% and dropping temperature of more than 1300 ℃.
CN201911104426.0A 2019-11-13 2019-11-13 Preparation method of iron ore pellets Pending CN110904334A (en)

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113073196A (en) * 2021-03-23 2021-07-06 包钢集团矿山研究院(有限责任公司) Method for inhibiting malignant reduction and expansion of iron pellet
CN113528812A (en) * 2021-07-26 2021-10-22 中南大学 Preparation method of wear-resistant alkaline pellets
CN114763582A (en) * 2021-01-15 2022-07-19 宝山钢铁股份有限公司 Method for producing magnesium pellets by using oriented silicon steel magnesium oxide waste
CN114774678A (en) * 2022-05-31 2022-07-22 本钢板材股份有限公司 Method for producing fluxed pellets from high-silicon ore powder
CN114891999A (en) * 2022-05-16 2022-08-12 唐山钢铁集团有限责任公司 Ore blending method for producing alkaline pellets by belt type roasting machine
CN116532214A (en) * 2023-03-01 2023-08-04 中天钢铁集团(南通)有限公司 Method for applying iron ore powder on-line grinding to pellet production

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CN105063348A (en) * 2015-08-19 2015-11-18 山西太钢不锈钢股份有限公司 Fluxed MgO pellet ore production method
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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114763582A (en) * 2021-01-15 2022-07-19 宝山钢铁股份有限公司 Method for producing magnesium pellets by using oriented silicon steel magnesium oxide waste
CN114763582B (en) * 2021-01-15 2023-09-12 宝山钢铁股份有限公司 Method for producing magnesium pellets by using oriented silicon steel magnesia waste
CN113073196A (en) * 2021-03-23 2021-07-06 包钢集团矿山研究院(有限责任公司) Method for inhibiting malignant reduction and expansion of iron pellet
CN113528812A (en) * 2021-07-26 2021-10-22 中南大学 Preparation method of wear-resistant alkaline pellets
CN113528812B (en) * 2021-07-26 2022-04-05 中南大学 Preparation method of wear-resistant alkaline pellets
CN114891999A (en) * 2022-05-16 2022-08-12 唐山钢铁集团有限责任公司 Ore blending method for producing alkaline pellets by belt type roasting machine
CN114774678A (en) * 2022-05-31 2022-07-22 本钢板材股份有限公司 Method for producing fluxed pellets from high-silicon ore powder
CN116532214A (en) * 2023-03-01 2023-08-04 中天钢铁集团(南通)有限公司 Method for applying iron ore powder on-line grinding to pellet production
CN116532214B (en) * 2023-03-01 2024-04-19 中天钢铁集团(南通)有限公司 Method for applying iron ore powder on-line grinding to pellet production

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