CN111910072A - Preparation and use method of pre-reduced flux pellets using steel slag as part of raw materials - Google Patents

Abstract

The invention relates to a method for preparing pre-reduced flux pellets using steel slag as part of the raw material. 1) sieving the steel slag, taking out steel slag particles with a particle size of 2-4 mm, and grinding the remaining steel slag into steel slag powder; 2) drying and grinding the dust 3) Steel slag powder, dust removal ash powder, iron red, iron ore concentrate powder and composite binder are mixed in a mixer; 4) Steel slag particles with a particle size of 2-4 mm are used as the pelletizing core, and the The steel slag particles are put into a pelletizing machine for pelletizing to obtain green pellets; 5) drying, preheating and roasting are performed to prepare finished pellets of pre-reducing flux pellets. After the blast furnace production adopts the technical solution, the blast furnace production cost is reduced, the market competitiveness of the ironmaking process is enhanced, the recycling of the secondary resources of the iron and steel plant can be realized, the application of high value-added products can be realized, and the green manufacturing of the blast furnace smelting can be realized.

Description

Preparation and use method of pre-reduced flux pellets using steel slag as part of raw materials

technical field

The invention relates to the technical field of metallurgy, in particular to a method for preparing and using pre-reduced flux pellets using steel slag as part of raw materials.

Background technique

In modern iron-making production technology, blast furnace process, as the main manufacturing process, is self-evident for iron-making production, accounting for more than 90% of pig iron production capacity. For the ironmaking production process, the core is to use coke and pulverized coal to generate the necessary reducing agent in the furnace to reduce the charge in the furnace, so as to obtain the raw material pig iron required for subsequent products. The charging charge of the blast furnace is mainly composed of two types of materials: one is iron-containing raw materials, mainly composed of sintered ore, pellets, lump ore (a small part will also have granulated iron, etc.), used for Provide the necessary components required for the reduction of molten iron; one is fuel, which is mainly composed of coke and pulverized coal, and plays the role of providing reducing agent and necessary heat in the furnace. Among them, the raw materials entering the furnace must maintain a certain alkalinity, so that the furnace smelting process can be carried out smoothly. Due to the relatively fixed composition of natural lump ore, the adjustment of alkalinity mainly includes the following three categories: ①High alkalinity sinter with low alkalinity pellets, ② sinter with flux pellets, ③ sinter with flux and low alkalinity pellets; and for the sake of economy and operability, the first two are As the main mode of feeding raw materials at the moment. But what needs to be explained here is that as the country's environmental protection requirements become more and more strict, since sintering production is a relatively serious polluting process, it will emit a large amount of sulfur-containing and sales-containing pollutants. Therefore, for the purpose of environmental protection, the national It is also transforming and advocating a pelletizing process with lower pollution and emission, which has led to more and more attention of metallurgical enterprises on the pelletizing mode of low alkalinity sintered ore with flux.

For flux pellets, it can be mainly divided into magnesium-containing, calcium-containing, and both types. Compared with ordinary low-basicity pellets, its main purpose is to adjust the basicity and slag composition of the slag in addition to providing the necessary iron-containing material components during the smelting process in the blast furnace. The production process of flux pellets mainly uses iron ore concentrate powder as the basic iron-containing material, adds part of the flux, and mixes it for pelletizing production. Under the process of chain grate-rotary kiln or belt roaster, It is supplemented by the necessary roasting temperature and time to produce high-strength flux pellets that meet blast furnace smelting. For the selection of fluxes, it is mainly composed of magnesium- and calcium-containing fluxes such as dolomite, limestone, quicklime, magnesite, and serpentine. For iron and steel plants, since iron and steel process products need to be processed through multiple processes, after each process is processed, coupled with the huge output of iron and steel products, almost every process will produce a large number of secondary products. As a secondary product of a steel plant, steel slag powder is one of the main substances, which is the remaining substance after steelmaking in a converter or an electric furnace. The main use of steel slag powder for steel mills is to re-participate in the process production after the magnetic separation process, and then re-distribute it to the sintering process. As far as the external market is concerned, its main use is to manufacture low value-added products such as cement and bricks, and the profit is low. It should be noted here that due to the process characteristics, the main components of steel slag powder are iron and calcium oxide, and as the most important raw material for the production of flux pellets, steel slag contains a large amount of calcium oxide. , for the production of flux pellets, iron and other materials can be effectively utilized, and the green manufacturing advocated by the state and enterprises can be realized.

For the secondary product steel slag powder of metallurgical enterprises, the purpose of external enterprises is to process and produce some low value-added products (see Chinese patent "Steel slag iron removal process and application of steel slag fine powder" patent application number: CN1566010, "Steel slag composite Micropowder and its preparation method" patent application number: CN102584042B, "steel slag production process of high-activity steel slag powder and inert mineral products": CN106755650B, "foamed asphalt steel slag mixture and its preparation method" patent application number: CN102964108B, "a kind of The method for preparing bricks by grinding steel slag and steel slag particles as raw materials "Patent Application No.: CN110790554A, etc.), this kind of technology has simple process flow and good iron removal effect. Salt cement, the cement produced by it meets the requirements of national standards, and solves the technical problems of steel slag slag Portland cement, such as low early strength and poor stability, or can also partially replace natural aggregates such as sand and crushed stone, further reducing the material It has good practicability in terms of cost, but its shortcomings are also obvious, that is, the effective ingredients cannot be used, resulting in low added value of the product, and it has nothing to do with the present invention from the application point of view. For the production of flux pellets, products and technologies on the market are not uncommon (see Chinese patent "Production method of flux iron ore powder composite pellets" patent application number: CN100342041C, "A high alkalinity pellet and its Preparation method" patent application number: CN110129550A, "a kind of high basicity pellets for blast furnace ironmaking and its production method" patent application number: CN107488784B, "a kind of production method of flux composite carbon-containing pellets for blast furnace" patent Application No.: CN104975173B, Patent Application No.: CN104975173B, "Production Method of Flux-based Composite Carbon-Containing Pellets for Blast Furnace" Patent Application No.: CN106435170B, etc.) the existence of such technologies has the advantages of small investment, low energy consumption, less pollution, greatly improving the strength of high basicity pellets, and excellent metallurgical properties, which is beneficial to blast furnace ironmaking to increase output and reduce energy consumption. It has great practical value in production, and also solves the technical problem of the low proportion of pellets used in blast furnace smelting, thereby increasing the proportion of pellets fed into the furnace and improving blast furnace smelting indicators, but it needs to be explained here. Yes, this type of flux pellet technology is only used as a conventional flux pellet production technology, and cannot realize the rational processing and utilization of secondary waste in enterprises. In addition, there are some documents available at home and abroad (see the journal "Steel" "Influence of Additive Flux on the Reduction Expansion Rate of Pellets", 2009, Vol. 44, No. 10, 14-16; "Sintered Pellet" "Shougang" "Experimental Research on Flux Pellets", 2004, Vol. 29, No. 2, 6-8; "Pellet" "Influence of MgO Content on the Properties of Magnesium Flux Pellets", 2017, Volume 42, Issue 2, 31-34; "Sintered Pellet" "Shougang Jingtang Sintering Flux Structure Optimization Research and Application", 20167, Volume 441, Issue 4, 15-18; etc.) It is mentioned in this type of research that the calcination temperature has a significant effect on the compressive strength of the pellets, and the alkalinity of the pellets has a more significant effect, producing pellets with higher alkalinity. The calcination temperature should be increased accordingly, and the alkalinity of the pellets is the main factor affecting the reductibility of the pellets. The increase in the alkalinity of the pellets will significantly improve the reductibility of the pellets. However, this kind of literature does not mention how the steel slag produced by the iron and steel plant can be applied to the production of flux pellets, and it has not been able to realize the rational application of the dust removal of the secondary product of the iron and steel plant.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a pre-reduced flux ball with steel slag powder as part of the raw material, so as to reduce the production cost of the blast furnace and realize the recycling of the secondary resources of the iron and steel plant.

To achieve the above object, the present invention adopts the following technical solutions to realize:

The preparation method of pre-reduced flux pellets using steel slag as part of the raw material comprises the following steps:

1) sieve the steel slag, take out the steel slag particles with a particle size of 2-4 mm, and grind the remaining steel slag into steel slag powder;

2) Dry and grind the dust removal dust into dust dust powder;

3) Steel slag powder, dust removal ash powder, iron red, iron ore concentrate powder and composite binder are mixed in a mixer;

4) Take steel slag particles with a particle size of 2 to 4 mm as the pelletizing core, and continuously put the steel slag particles into the pelletizing machine for pelletizing to obtain green pellets;

5) drying, preheating and roasting to obtain finished pellets of pre-reducing flux pellets;

In step 1), the grinding time is 30-80 min, and the mass ratio of the steel slag powder with a particle size of less than 0.074 mm after grinding is ≥80%.

In step 2), the drying temperature is 150-300° C., the drying time is 4-8 h, and the grinding time is 30-80 min.

The mixing time in step 3) is 20-60 min.

In step 5), drying time is 8～12min, drying temperature is 300～500 ℃; preheating time is 6～10min, preheating temperature is 800～1100 ℃; calcination time is 10～15min, calcination temperature is 1240～1310 ℃.

The dedusting ash includes one or more of blast furnace gravity ash, dry-process dedusting ash, gas sludge, and steelmaking dust sludge.

A method for using pre-reduced flux pellets with steel slag powder as part of the raw material, the pre-reduced flux pellets, sintered ore and lump ore are mixed to form a charging charge, which is transported to the top of the blast furnace through a blast furnace charging main belt In the material tank, it is put into the blast furnace through the material clock distributor and rotary chute, and the proportion of pre-reduced flux pellets into the furnace charge is based on the needs of basicity setting in blast furnace production. The pre-reduction degree, basicity of the pellets, as well as the basicity and proportion of sintered ore and lumps are used as the basic reference data. Under the condition of batch ore charging into the furnace, the determination of the proportion of pre-reduced flux pellets shall meet the following requirements: condition;

P _sinter +P _pellet +P _ore = 1 (1)

Symbols in the formula:

P _pellet is the proportion of pre-reducing flux pellets in the batch of ore, %;

P _sinter is the proportion of sinter in the batch, %;

Pore is the proportion of lump _ore in the batch, %;

R _sinter is the binary basicity of sinter in the batch;

R _pellet is the binary alkalinity of pre-reduced flux pellets in the batch ore;

R _ore is the binary alkalinity of the lump ore in the batch;

C is an arithmetic value, and its value ranges from 1.50 to 1.60;

m(Fe) is the percentage of metallic iron in the pre-reduced flux pellets in the batch, %.

In the batch of ore, the proportion of sintered ore is 30% to 85%, and the binary basicity of the sintered ore is 1.6 to 2.2.

The binary basicity of the pre-reduced flux pellets in the batch ore is 0.6-1.2.

The binary basicity of the lump ore in the batch ore is 0.03-0.10.

The percentage content of metallic iron in the pre-reduced flux pellets in the batch ore is 5% to 20%.

Compared with the prior art, the beneficial effects of the present invention are:

The invention uses secondary products in the smelting process of iron and steel plants, such as steel slag powder, dust removal ash, iron red and other iron-containing materials, to produce pre-reducing flux pellets for blast furnace smelting, and the blast furnace production adopts this technical scheme After that, it can reduce the production cost of blast furnace, enhance the market competitiveness of the ironmaking process, and also realize the recycling of secondary resources in iron and steel plants, realize the application of high value-added products, and then realize the green manufacturing of blast furnace smelting.

Detailed ways

Below in conjunction with embodiment, the present invention is further described:

The following examples illustrate the invention in detail. These examples merely describe the best embodiments of the present invention and do not limit the scope of the present invention.

Example 1

Mixing ratio and processing plan of dust removal and ash

See Table 1 for the mixing ratio of dust removal ash.

Table 1: Mixing ratio scheme of dust removal and ash

raw material name Mass proportioning ratio, % blast furnace gravity ash 25 dry dust removal 20 gas mud 25 steelmaking dust 30

See Table 2 for the dust removal and ash mixing processing plan.

Table 2: Mixing ratio scheme of dust removal and ash

project Numerical value drying temperature, ℃ 200 drying time, h 5 Grinding time, min 40 Mixing time, min 35 Mixing particle size (less than 0.074mm accounts for the proportion of mass), % 85

Pre-reduced flux pelletizing solution

See Table 3 for the pre-reduced flux pelletizing scheme.

Table 3: Pre-reduced flux pelletizing scheme

project Numerical value Steel slag particle size range, mm 2 to 4 Grinding time, min 40 The particle size of steel slag powder (in 0.074mm, the proportion of mass), % 85 Mixing ratio of dust and dust, % 30 Iron red ratio, % 5 Iron ore concentrate powder ratio, % 63 Compound binder ratio, % 2 Ball making time, min 12 Green ball diameter, mm 10～16

Pre-reduced flux pellet roasting scheme

See Table 4 for the calcination scheme of the pre-reduced pellets.

Table 4: Pre-reduced flux pellet firing scheme

The application method of the blast furnace with pre-reduced flux pellets using steel slag powder as part of the raw material, (an example of the application of a blast furnace with an effective furnace capacity of ^450m3 in a steel plant)

See Table 5 for the blast furnace usage of pre-reduced flux pellets with steel slag powder as part of the raw materials.

Table 5: How to use pre-reduced flux pellets with steel slag powder as part of the raw materials

project Numerical value Arithmetic value C takes the value 1.55 Binary alkalinity of sinter in batch ore 1.8 The proportion of sintered ore in the batch of ore into the furnace, % 79 Lump ore alkalinity in batch 0.05 The proportion of lump ore into the furnace in the batch, % 15 Binary Basicity of Prereduced Flux Pellets in Batch Ore 0.6 The percentage of metallic iron in the pre-reduced flux pellets in the batch, % 10 The proportion of pre-reduced flux pellets in the batch of ore, % 16

Blast furnace use effect

Table 6 shows the effect of the pre-reduced flux pellets manufactured according to the present invention using steel slag powder as part of the raw material in a blast furnace with an effective furnace capacity of 450 m ³ in an iron and steel plant.

Table 6: Application effect of blast furnace

project Manufacturing cost, RMB/ton Original charge (high basicity sinter, acid pellet, lump ore) mode 2350 Using pre-reducing flux pellet mode 2300 Effect -50

Using this method, the pre-reduced flux pellets using steel slag powder as part of the raw materials and their blast furnace use, pass through the secondary products in the smelting process of the iron and steel plant, such as steel slag powder, dust removal ash, iron red and other iron-containing materials. To produce pre-reducing flux pellets for blast furnace smelting, after adopting this technical solution for blast furnace production, it can process and manufacture low-cost flux pellets, reduce blast furnace production costs, and enhance the market competitiveness of iron-making processes. After the application of the blast furnace with an effective furnace capacity of ^450m3 in the iron and steel plant, the production cost per ton of iron is reduced by 50 yuan/ton, realizing the recycling of the secondary resources of the iron and steel plant, realizing the application of high value-added products, and then realizing the green manufacturing of blast furnace smelting.

Example 2

Mixing ratio and processing plan of dust removal and ash

See Table 7 for the proportioning scheme of dust removal and ash mixing.

Table 7: Mixing ratio scheme of dust removal and ash

raw material name Mass proportioning ratio, % blast furnace gravity ash 30 dry dust removal 30 gas mud 10 steelmaking dust 30

See Table 8 for the dust removal and ash mixing processing plan.

Table 8: Mixing ratio scheme of dust removal and ash

project Numerical value drying temperature, ℃ 250 drying time, h 6 Grinding time, min 40 Mixing time, min 40 Mixing particle size (less than 0.074mm accounts for the proportion of mass), % 88

Pre-reduced flux pelletizing solution

See Table 9 for the pre-reduced flux pelletizing scheme.

Table 9: Pre-reduced flux-based pelletizing scheme

project Numerical value Steel slag particle size range, mm 2 to 4 Grinding time, min 40 The particle size of steel slag powder (in 0.074mm, the proportion of mass), % 86 Mixing ratio of dust and dust, % 35 Iron red ratio, % 10 Iron ore concentrate powder ratio, % 53 Compound binder ratio, % 2 Ball making time, min 12 Green ball diameter, mm 10～16

Pre-reduced flux pellet roasting scheme

See Table 10 for the pre-reducing pellet roasting scheme.

Table 10: Pre-reduced flux pellet firing scheme

project Numerical value Roasting process selection Chain Grate Machine - Rotary Kiln drying time, min 11 Drying temperature, °C 400 Preheating time, min 9 Preheat temperature, °C 970 Roasting time, min 12 Roasting temperature, °C 1270

The application method of the blast furnace with pre-reduced flux pellets using steel slag powder as part of the raw material, (an example of the application of a blast furnace with an effective furnace capacity of ^1280m3 in a steel plant)

See Table 11 for the blast furnace usage of pre-reduced flux pellets with steel slag powder as part of the raw materials.

Table 11: How to use the pre-reduced flux pellets with steel slag powder as part of the raw materials

project Numerical value Arithmetic value C takes the value 1.52 Binary alkalinity of sinter in batch ore 2.0 The proportion of sintered ore in the batch of ore into the furnace, % 58 Lump ore alkalinity in batch 0.05 The proportion of lump ore into the furnace in the batch, % 5 Binary Basicity of Prereduced Flux Pellets in Batch Ore 0.8 The percentage of metallic iron in the pre-reduced flux pellets in the batch, % 15 The proportion of pre-reduced flux pellets in the batch of ore, % 37

Blast furnace use effect

Table 12 shows the effect of the pre-reduced flux pellets manufactured according to the present invention using steel slag powder as part of the raw material in a blast furnace with an effective furnace capacity of 1280 m ³ in a steel plant.

Table 12: Application effect of blast furnace

project Manufacturing cost, RMB/ton Original charge (high basicity sinter, acid pellet, lump ore) mode 2300 Using pre-reducing flux pellet mode 2240 Effect -60

Using this method, the pre-reduced flux pellets using steel slag powder as part of the raw materials and their blast furnace use, pass through the secondary products in the smelting process of the iron and steel plant, such as steel slag powder, dust removal ash, iron red and other iron-containing materials. To produce pre-reducing flux pellets for blast furnace smelting, after adopting this technical solution for blast furnace production, it can process and manufacture low-cost flux pellets, reduce blast furnace production costs, and enhance the market competitiveness of iron-making processes. After the application of the blast furnace with an effective furnace capacity of ^1280m3 in the iron and steel plant, the production cost per ton of iron is reduced by 60 yuan/ton, realizing the recycling of the secondary resources of the iron and steel plant, realizing the application of high value-added products, and then realizing the green manufacturing of blast furnace smelting.

Example 3

Mixing ratio and processing plan of dust removal and ash

See Table 13 for the proportioning scheme of dust removal ash.

Table 13: Mixing ratio scheme of dust removal ash

raw material name Mass proportioning ratio, % blast furnace gravity ash 30 dry dust removal 35 gas mud 15 steelmaking dust 20

See Table 14 for the dust removal and ash mixing processing plan.

Table 14: Mixing ratio scheme of dust removal and ash

project Numerical value drying temperature, ℃ 300 drying time, h 7 Grinding time, min 35 Mixing time, min 35 Mixing particle size (less than 0.074mm accounts for the proportion of mass), % 88

Pre-reduced flux pelletizing solution

See Table 15 for the pre-reduced flux pelletizing scheme.

Table 15: Pre-reduced flux pelletizing scheme

project Numerical value Steel slag particle size range, mm 2 to 4 Grinding time, min 45 The particle size of steel slag powder (in 0.074mm, the proportion of mass), % 88 Mixing ratio of dust and dust, % 25 Iron red ratio, % 10 Iron ore concentrate powder ratio, % 63 Compound binder ratio, % 2 Ball making time, min 12 Green ball diameter, mm 10～16

Pre-reduced flux pellet roasting scheme

See Table 16 for the pre-reducing pellet roasting scheme.

Table 16: Pre-reduced flux pellet firing scheme

project Numerical value Roasting process selection Belt roaster drying time, min 12 Drying temperature, °C 400 Preheating time, min 19 Preheat temperature, °C 950 Roasting time, min 12 Roasting temperature, °C 1270

The application method of the blast furnace with pre-reduced flux pellets using steel slag powder as part of the raw material, (an example of the application of a blast furnace with an effective furnace capacity of ^2580m3 in a steel plant)

See Table 17 for the blast furnace usage of pre-reduced flux pellets with steel slag powder as part of the raw materials.

Table 17: How to use pre-reduced flux pellets with steel slag powder as part of the raw materials

Blast furnace use effect

Table 18 shows the effect of the pre-reduced flux pellets manufactured according to the present invention using steel slag powder as part of the raw material in a blast furnace with an effective furnace capacity of 2580 m ³ in a steel plant.

Table 18: Application effect of blast furnace

project Manufacturing cost, RMB/ton Original charge (high basicity sinter, acid pellet, lump ore) mode 2240 Using pre-reducing flux pellet mode 2150 Effect -90

Using this method, the pre-reduced flux pellets using steel slag powder as part of the raw materials and their blast furnace use, pass through the secondary products in the smelting process of the iron and steel plant, such as steel slag powder, dust removal ash, iron red and other iron-containing materials. To produce pre-reducing flux pellets for blast furnace smelting, after adopting this technical solution for blast furnace production, it can process and manufacture low-cost flux pellets, reduce blast furnace production costs, and enhance the market competitiveness of iron-making processes. After the application of the blast furnace with an effective furnace capacity of ^2580m3 in the iron and steel plant, the production cost per ton of iron has dropped by 190 yuan/ton, realizing the recycling of the secondary resources of the iron and steel plant, realizing the application of high value-added products, and then realizing the green manufacturing of blast furnace smelting.

Example 4

Mixing ratio and processing plan of dust removal and ash

See Table 19 for the proportioning scheme of dust removal ash.

Table 19: Mixing ratio scheme of dust removal ash

raw material name Mass proportioning ratio, % blast furnace gravity ash 35 dry dust removal 35 gas mud 30

See Table 20 for the dust removal and ash mixing processing plan.

Table 20: Mixing ratio scheme of dust removal ash

project Numerical value drying temperature, ℃ 300 drying time, h 8 Grinding time, min 40 Mixing time, min 35 Mixing particle size (less than 0.074mm accounts for the proportion of mass), % 85

Pre-reduced flux pelletizing solution

See Table 21 for the pre-reduced flux pelletizing scheme.

Table 21: Pre-reduced flux-based pelletizing protocol

project Numerical value Steel slag particle size range, mm 2 to 4 Grinding time, min 45 The particle size of steel slag powder (in 0.074mm, the proportion of mass), % 85 Mixing ratio of dust and dust, % 35 Iron red ratio, % 15 Iron ore concentrate powder ratio, % 48 Compound binder ratio, % 2 Ball making time, min 12 Green ball diameter, mm 10～16

Pre-reduced flux pellet roasting scheme

See Table 22 for the pre-reducing pellet roasting scheme.

Table 22: Pre-reduced flux pellet firing scheme

project Numerical value Roasting process selection Belt roaster drying time, min 10 Drying temperature, °C 450 Preheating time, min 8 Preheat temperature, °C 1000 Roasting time, min 12 Roasting temperature, °C 1270

The application method of the blast furnace with pre-reduced flux pellets using steel slag powder as part of the raw material, (an example of the application ^of a blast furnace with an effective furnace capacity of 3200m3 in a steel plant)

See Table 23 for the blast furnace usage of pre-reduced flux pellets with steel slag powder as part of the raw materials.

Table 23: How to use pre-reduced flux pellets with steel slag powder as part of the raw materials

project Numerical value Arithmetic value C takes the value 1.55 Binary alkalinity of sinter in batch ore 2.2 The proportion of sintered ore in the batch of ore into the furnace, % 64 Lump ore alkalinity in batch 0.05 The proportion of lump ore into the furnace in the batch, % 20 Binary Basicity of Prereduced Flux Pellets in Batch Ore 0.6 The percentage of metallic iron in the pre-reduced flux pellets in the batch, % 10 The proportion of pre-reduced flux pellets in the batch of ore, % 16

Blast furnace use effect

Table 24 shows the effect of the pre-reduced flux pellets manufactured according to the present invention using steel slag powder as part of the raw material in a blast furnace with an effective furnace capacity of 3200 m ³ in a steel plant.

Table 24: Blast furnace application effect

Using this method, the pre-reduced flux pellets using steel slag powder as part of the raw materials and their blast furnace use, pass through the secondary products in the smelting process of the iron and steel plant, such as steel slag powder, dust removal ash, iron red and other iron-containing materials. To produce pre-reducing flux pellets for blast furnace smelting, after adopting this technical solution for blast furnace production, it can process and manufacture low-cost flux pellets, reduce blast furnace production costs, and enhance the market competitiveness of iron-making processes. After the application of the blast furnace with an effective furnace capacity of 3200m ³ in the iron and steel plant, the production cost per ton of iron is reduced by 100 yuan/ton, realizing the recycling of the secondary resources of the iron and steel plant, realizing the application of high value-added products, and then realizing the green manufacturing of blast furnace smelting.

Example 5

Mixing ratio and processing plan of dust removal and ash

See Table 25 for the proportioning scheme of dust removal ash.

Table 25: Mixing ratio scheme of dust removal ash

raw material name Mass proportioning ratio, % blast furnace gravity ash 35 dry dust removal 35 steelmaking dust 30

See Table 26 for the dust removal and ash mixing processing plan.

Table 26: Mixing ratio scheme of dust removal ash

project Numerical value drying temperature, ℃ 300 drying time, h 6 Grinding time, min 50 Mixing time, min 50 Mixing particle size (less than 0.074mm accounts for the proportion of mass), % 90

Pre-reduced flux pelletizing solution

See Table 27 for the pre-reduced flux pelletizing protocol.

Table 27: Pre-reduced flux pelletizing protocol

Pre-reduced flux pellet roasting scheme

See Table 28 for the pre-reducing pellet roasting scheme.

Table 28: Pre-reduced flux pellet firing scheme

project Numerical value Roasting process selection Chain Grate Machine - Rotary Kiln drying time, min 10 Drying temperature, °C 450 Preheating time, min 8 Preheat temperature, °C 1050 Roasting time, min 12 Roasting temperature, °C 1270

The application method of the blast furnace with pre-reduced flux pellets using steel slag powder as part of the raw material, (an example of the application of a blast furnace with an effective furnace capacity of ^4038m3 in a steel plant)

See Table 29 for the blast furnace usage of pre-reduced flux pellets using steel slag powder as part of the raw materials.

Table 29: How to use pre-reduced flux pellets with steel slag powder as part of the raw materials

project Numerical value Arithmetic value C takes the value 1.58 Binary alkalinity of sinter in batch ore 1.9 The proportion of sintered ore in the batch of ore into the furnace, % 75 Lump ore alkalinity in batch 0.05 The proportion of lump ore into the furnace in the batch, % 15 Binary Basicity of Prereduced Flux Pellets in Batch Ore 1.1 The percentage of metallic iron in the pre-reduced flux pellets in the batch, % 10 The proportion of pre-reduced flux pellets in the batch of ore, % 10

Blast furnace use effect

Table 30 shows the effect of the pre-reduced flux pellets manufactured according to the present invention using steel slag powder as part of the raw material in a blast furnace with an effective furnace capacity of 4038 m ³ in an iron and steel plant.

Table 30: Blast furnace application effect

project Manufacturing cost, RMB/ton Original charge (high basicity sinter, acid pellet, lump ore) mode 2150 Using pre-reducing flux pellet mode 2100 Effect -50

Using this method, the pre-reduced flux pellets using steel slag powder as part of the raw materials and their blast furnace use, pass through the secondary products in the smelting process of the iron and steel plant, such as steel slag powder, dust removal ash, iron red and other iron-containing materials. To produce pre-reducing flux pellets for blast furnace smelting, after adopting this technical solution for blast furnace production, it can process and manufacture low-cost flux pellets, reduce blast furnace production costs, and enhance the market competitiveness of iron-making processes. After the application of the blast furnace with an effective furnace capacity of 4038m ³ in the iron and steel plant, the production cost per ton of iron is reduced by 50 yuan/ton, which realizes the recycling of the secondary resources of the iron and steel plant, realizes the application of high value-added products, and then realizes the green manufacturing of blast furnace smelting.

Claims (8)

1. a method for preparing pre-reduced flux pellets with steel slag as part of raw materials, is characterized in that, comprises the following steps: 1) sieve the steel slag, take out the steel slag particles with a particle size of 2-4 mm, and grind the remaining steel slag into steel slag powder; 2) Dry and grind the dust removal dust into dust dust powder; 3) Steel slag powder, dust removal ash powder, iron red, iron ore concentrate powder and composite binder are mixed in a mixer; 4) Take steel slag particles with a particle size of 2 to 4 mm as the pelletizing core, and continuously put the steel slag particles into the pelletizing machine for pelletizing to obtain green pellets; 5) Drying, preheating and calcining to obtain finished pellets of pre-reducing flux pellets. 2. the pre-reduced flux pellet preparation method with steel slag as part of raw materials according to claim 1, is characterized in that, in step 1), the grinding time is 30～80min, and the granularity after grinding is less than the quality of the steel slag powder of 0.074mm The ratio is ≥80%; in step 2), the drying temperature is 150-300 ° C, the drying time is 4-8h, and the grinding time is 30-80min; the mixing time in step 3) is 20-60min; the drying time in step 5) 8～12min, drying temperature is 300～500℃; preheating time is 6～10min, preheating temperature is 800～1100℃; roasting time is 10～15min, roasting temperature is 1240～1310℃. 3. The method for preparing pre-reduced flux pellets with steel slag as part of raw materials according to claim 1, characterized in that, described dust removal ash comprises blast furnace gravity ash, dry dust removal ash, gas sludge, steelmaking dust sludge one or more of them. 4. a method of using steel slag powder as part of raw material pre-reduced flux pellets according to claim 1, is characterized in that, pre-reduced flux pellets, sintered ore, lump ore are mixed and formed into furnace charge , through the blast furnace feeding main belt, transported to the blast furnace top tank, and put into the blast furnace through the material clock distributor and rotary chute, and the proportion of pre-reduced flux pellets into the furnace charge is based on the blast furnace production process. For the basicity setting, the pre-reduction degree and basicity of the pre-reduced flux pellets, as well as the basicity and ratio of sintered ore and lumps are used as basic reference data. The determination of the proportion of reducing flux pellets must meet the following conditions; P _sinter +P _pellet +P _ore = 1 (1)

Symbols in the formula: P _pellet is the proportion of pre-reducing flux pellets in the batch of ore, %; P _sinter is the proportion of sinter in the batch, %; Pore is the proportion of lump _ore in the batch, %; R _sinter is the binary basicity of sinter in the batch; R _pellet is the binary alkalinity of pre-reduced flux pellets in the batch ore; R _ore is the binary alkalinity of the lump ore in the batch; C is an arithmetic value, and its value ranges from 1.50 to 1.60; m(Fe) is the percentage of metallic iron in the pre-reduced flux pellets in the batch, %. 5 . The method for using pre-reduced flux pellets using steel slag powder as part of raw materials according to claim 4 , wherein the proportion of sintered ore in the batch of ore is 30% to 85%, and the sintered ore The binary alkalinity is 1.6 to 2.2. 6 . The method for using the pre-reduced flux pellets with steel slag powder as part of the raw material according to claim 4 , wherein the binary basicity of the pre-reduced flux pellets in the batch of ore is 0.6～ 1.2. 7 . The method for using pre-reduced flux pellets using steel slag powder as part of raw materials according to claim 4 , wherein the binary basicity of lump ore in the batch of ore is 0.03-0.10. 8 . 8. the using method of the pre-reduced flux pellets with steel slag powder as part of raw materials according to claim 4, is characterized in that, in the described batch ore, the percentage of metallic iron in the pre-reduced flux pellets is 5 %～20%.