CN117025943A - Modified fuel for improving sintering technical index, preparation method and application - Google Patents

Abstract

The invention relates to the technical field of iron ore sintering, in particular to a modified fuel for improving sintering technical indexes, a preparation method and application. The specific steps of fuel preparation include: (1) Crushing the raw fuel, and screening to obtain the fuel with the particle size smaller than 1 mm; (2) Fully mixing the fuel with particle size less than 1mm, carbon-containing solid waste and a fuel slow-combustion agent to obtain modified fuel; the fuel slow-combustion agent comprises a solid fuel slow-combustion agent and/or a liquid fuel slow-combustion agent, wherein the mass ratio of the fuel slow-combustion agent in the modified fuel is 3% -10%. The fuel prepared by the invention is used for sintering iron ores, and after fine-fraction fuel is mixed with a slow-combustion agent, the combustion performance (ignition temperature rise and combustion time extension) of the fine-fraction fuel is improved, so that the high-temperature retention time of a sintered upper material layer is prolonged, the quality of the sintered upper material layer is improved, and the sintering return rate is reduced.

Description

Modified fuel, preparation method and application to improve sintering technical indicators

Technical field

The invention relates to the technical field of iron ore sintering, and specifically relates to a modified fuel that improves sintering technical indicators, a preparation method and application.

Background technique

The fuel used in the iron ore sintering process is still mainly solid fuel (coke powder, anthracite coal powder). The fuel particle size requirements vary slightly depending on the ore blending structure and production needs, generally less than 3mm accounting for 75%-85%. The fuel is generally crushed using pairs of rollers and four rollers to obtain fuel with qualified particle size, which is then used in the production of sintering batches. Through long-term production data, inspections, and benchmarking, it was found that most of the sintered fuel after crushing in the sintering plant is over-crushed, which is manifested in that the proportion of particles smaller than 1mm accounts for more than 50%, and the proportion of particles smaller than 0.5mm accounts for more than 40%, which is extremely undesirable. It is beneficial to the stability of sintering production, improvement of sinter quality indicators and reduction of energy consumption. At the same time, in order to reduce costs, the application of carbon-containing dust removal ash in the sintering process has gradually become the norm, which has further caused an increase in the proportion of particles smaller than 1mm in the sintered fuel, further deteriorating the production and quality indicators of the upper sintered material layer, and The heat utilization efficiency of fine-grained fuel is low.

In order to improve the quality index of sintered minerals, it is necessary to achieve particle size segregation of sintered mixture and fuel. After segregation and distribution, the fuel in the upper material layer is mainly fine-grained, and the large-particle fuel is mostly located in the middle and lower material layers. Studies have shown that fuels with particles smaller than 1 mm will flash over due to their fine particle size and large specific surface area under the high temperature and highly oxidizing atmosphere of the sintering ignition and exhaust. The excessive combustion speed will result in a short retention time of the upper sintering high temperature and a small amount of liquid phase production. Or the liquid phase condensation and crystallization speed is fast, the strength of this part of the sinter decreases, and the mineral return rate increases.

In view of the problem that the high proportion of fine-grained fuel in sintering is not conducive to the improvement of economic and technical indicators, the existing Chinese patent CN111996367A discloses a method of utilizing ultra-fine coal powder in sintering and a sintering mixture. Ultra-fine coal is obtained through fuel screening. The fine fuel is further finely ground to less than 200 mesh and mixed with part of the iron ore powder to prepare 3-8mm pellets, which are then mixed with the remaining sintering mixture and then sintered to realize the application in the early sintering process of ultra-fine fuel. This method requires additional screening, fine grinding, pelletizing, weighing and other supporting equipment, and the investment and operating costs are relatively high. It is also possible to pre-screen the crushed sintered fuel, and finely grind the part with a particle size smaller than 1 mm for blast furnace injection. However, due to the influence of pulverized coal performance, screening efficiency, transportation costs, etc., it has not yet been promoted and applied.

Contents of the invention

Aiming at the technical problem of insufficient combustion of fuel with a particle size smaller than 1 mm, the present invention provides a modified fuel that improves sintering technical indicators, a preparation method and application.

In a first aspect, the present invention provides a modified fuel preparation method that improves sintering technical indicators. The specific steps include:

(1) Crush the original fuel and then screen it to screen out fuel with a particle size of <1mm and fuel with a particle size >1mm;

(2) Fully mix fuel with particle size <1mm, carbon-containing solid waste and fuel retardant to obtain modified fuel; fuel retardant includes solid fuel retardant and/or liquid fuel retardant, fuel retardant The mass proportion of the agent in the modified fuel is 3%-10%.

Further, the solid fuel retardant is a fine-grained powder material, including any one or more of quicklime powder, dust removal ash, and finely ground mineral powder.

Further, the liquid fuel retardant is any one or more of coking wastewater, blast furnace slag washing water, CMC solution, and PVA solution.

Further, step (2) is to fully mix <1mm particle size fuel, carbon-containing solid waste, solid fuel retardant, and water in a powerful mixer. The mass proportion of water is 2%-8%; add water It can avoid the generation of dust during the mixing process of adding solid fuel retardant.

Further, step (2) is to thoroughly mix the <1mm particle size fuel, carbon-containing solid waste and liquid fuel retardant in a powerful mixer.

Further, step (2) also includes thoroughly mixing dust removal ash or quicklime with fuel with particle size <1mm, carbon-containing solid waste and fuel retardant.

In a second aspect, the present invention provides a modified fuel prepared by using the above modified fuel preparation method.

In a third aspect, the present invention provides an application of the above-mentioned modified fuel in iron ore sintering.

Further, the prepared modified fuel, >1mm particle size fuel, flux, homogeneous material, and returned ore are mixed and granulated to obtain a sintered mixture, which is then distributed, ignited, sintered, crushed, cooled, and granulated to obtain the finished product sintered Ore and return ore; modified fuel is laid on the upper layer when distributing.

The beneficial effects of the present invention are:

1. After mixing the fine-grained fuel with the flame retardant, the combustion performance of the fuel is improved (the ignition point temperature increases and the combustion time is prolonged), thereby extending the high-temperature retention time of the upper sintered material layer and improving the sinter quality of the upper material layer. The sintering return rate is reduced;

2. Improves the fuel heat utilization rate of <1mm particle size, which is beneficial to the consumption of sintered solid fuel;

3. Using common solid materials or liquid materials inside steel plants as fuel retarder will help reduce the emission of gas pollutants (NO _x );

4. It has high economic and social benefits; it improves the economic and technical indicators of sintering.

Description of the drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those of ordinary skill in the art, It is said that other drawings can also be obtained based on these drawings without exerting creative work.

Figure 1 is a flow chart of the sintering process of modified fuel added with a solid fuel retardant in Embodiment 1 of the present invention.

Figure 2 is a flow chart of the sintering process of modified fuel added with liquid fuel retardant in Embodiment 2 of the present invention.

Detailed ways

In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described The embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts should fall within the scope of protection of the present invention.

Example 1

A modified fuel with added solid fuel retardant is used in the iron ore sintering process. The specific steps include:

(1) The original fuel is crushed and screened to obtain <1mm particle size fuel and >1mm particle size fuel, which are separately filled into silos for later use;

(2) Mix <1mm particle size fuel with quicklime, carbon-containing solid waste, and water in a powerful mixer to obtain modified fuel, in which the mass proportion of quicklime in the modified fuel is 5%;

(3) Mix and granulate the modified fuel, >1mm particle size fuel, flux, homogeneous material, and returned ore, and then carry out distribution, ignition, sintering, crushing, cooling, and granulation to obtain the finished sintered ore and returned ore.

Example 2

A modified fuel with added liquid fuel retardant is used in the iron ore sintering process. The specific steps include:

(1) The original fuel is crushed and screened to obtain <1mm particle size fuel and >1mm particle size fuel, which are separately filled into silos for later use;

(2) Mix the <1mm particle size fuel with blast furnace slag flushing water and carbon-containing solid waste in a powerful mixer to obtain modified fuel, in which the mass proportion of blast furnace slag flushing water in the modified fuel is 6%;

(3) Mix and granulate the modified fuel, >1mm particle size fuel, flux, homogeneous material, and returned ore, and then carry out distribution, ignition, sintering, crushing, cooling, and granulation to obtain the finished sintered ore and returned ore.

Example 3

A modified fuel with added solid fuel retardant is used in the iron ore sintering process. The specific steps include:

(1) The original fuel is crushed and screened to obtain <1mm particle size fuel and >1mm particle size fuel, which are separately filled into silos for later use;

(2) Mix <1mm particle size fuel with dust ash, water, and carbon-containing solid waste in a mixer to obtain modified fuel. The mass proportion of dust ash in the modified fuel is 3%, and water is in the modified fuel. The mass proportion of fuel is 5%;

(3) Mix and granulate the modified fuel, >1mm particle size fuel, flux, homogeneous material, and returned ore, and then carry out distribution, ignition, sintering, crushing, cooling, and granulation to obtain the finished sintered ore and returned ore.

Example 4

A modified fuel with added liquid fuel retardant is used in the iron ore sintering process. The specific steps include:

(1) The original fuel is crushed and screened to obtain <1mm particle size fuel and >1mm particle size fuel, which are separately filled into silos for later use;

(2) Mix <1mm particle size fuel and carbon-containing solid waste with a PVA solution with a mass fraction of 0.5% in a mixer to obtain modified fuel. The PVA solution has agglomeration effect and can reduce the consumption of solid fuel. The mass proportion of sexual fuel is 6%;

(3) Mix and granulate the modified fuel, >1mm particle size fuel, flux, homogeneous material, and returned ore, and then carry out distribution, ignition, sintering, crushing, cooling, and granulation to obtain the finished sintered ore and returned ore.

Comparative example 1

The crushed fuel is directly involved in the sintering batching, and the finished sinter and returned ore are obtained through mixing and granulation, distribution, ignition, sintering, crushing, cooling and granulation.

Comparative example 2

The application of a fuel in the iron ore sintering process, the specific steps include:

After the raw materials are crushed, quicklime with a mass proportion of 5% is directly added without screening, and mixed with flux, mixing material, and returned ore for granulation. Afterwards, distribution, ignition, sintering, crushing, cooling, and granulation are performed to obtain the finished sinter. and return minerals.

Comparative example 3

The application of a fuel in the iron ore sintering process, the specific steps include:

(1) The original fuel is crushed and screened to obtain <1mm particle size fuel and >1mm particle size fuel, which are separately filled into silos for later use;

(2) Mix <1mm particle size fuel, flux, returned minerals and quicklime with a mass ratio of 5%, then mix it with >1mm particle size fuel and sintering mixture, then pelletize, and then carry out distribution, ignition and sintering. , crushing, cooling and granulation to obtain finished sinter and returned ore.

The key economic and technical indicators of sintering in Examples 1-4 and Comparative Examples 1-3 were measured, and the results are shown in Table 1.

Table 1 Key economic and technical indicators of sintering

project Solid fuel consumption/(kg/t) Yield/% NO _x /(mg/m ³ ) Example 1 54.24 78.25 22.29 Example 2 54.23 78.26 22.05 Example 3 54.42 78.39 22.59 Example 4 54.12 78.72 22.36 Comparative example 1 56.52 76.96 26.64 Comparative example 2 55.26 77.85 25.06 Comparative example 3 55.35 77.68 25.23

Through the analysis of Examples 1-4 and Comparative Examples 1-3, it can be seen that by screening the fuel, adding fuel retardant modification to <1mm particle size fuel and then participating in the batching, the solid fuel consumption can be reduced and the sinter finished product can be achieved. The efficiency increases, and at the same time, the emission concentration of _NO Although the ore solid consumption and yield indicators have improved, the effect is not obvious; Comparative Example 3 first mixes fuel with particle size <1mm with flux, return ore, fuel retardant, etc., and then mixes fuel with particle size >1mm and The mixing and granulation of other mixtures will also affect the economic and technical indicators of iron ore sintering.

Although the present invention has been described in detail with reference to the accompanying drawings in conjunction with preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the invention, those of ordinary skill in the art can make various equivalent modifications or substitutions to the embodiments of the invention, and these modifications or substitutions should be within the scope of the invention/any Those skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present invention, and they should all be covered by the protection scope of the present invention.

Claims (8)

1. The preparation method of the modified fuel for improving the sintering technical index is characterized by comprising the following specific steps of:

(1) Crushing the raw fuel, and screening to obtain the fuel with the particle size of <1mm and the fuel with the particle size of >1 mm;

(2) Fully mixing the fuel with particle size less than 1mm, carbon-containing solid waste and a fuel slow-combustion agent to obtain modified fuel; the fuel slow-combustion agent comprises a solid fuel slow-combustion agent and/or a liquid fuel slow-combustion agent, wherein the mass ratio of the fuel slow-combustion agent in the modified fuel is 3% -10%.

2. The method for producing modified fuel according to claim 1, wherein the solid fuel slow-combustion agent is a fine-grained powder material comprising any one or more of quicklime powder, fly ash, and fine-ground mineral powder.

3. The method for producing modified fuel according to claim 1, wherein the liquid fuel slow-combustion agent is any one or more of coking wastewater, blast furnace slag-washing water, CMC solution, and PVA solution.

4. The method for producing modified fuel according to claim 1, wherein step (2) is to mix <1mm size fraction fuel, carbon-containing solid waste, solid fuel retarder and water in a strong mixer sufficiently, the mass ratio of water being 2% -8%.

5. The method for producing a modified fuel according to claim 1, wherein the step (2) is to mix the <1mm size fraction fuel, the carbonaceous solid waste and the liquid fuel retarder sufficiently in a intensive mixer.

6. A modified fuel produced by the modified fuel production method of any one of claims 1 to 5.

7. Use of the modified fuel according to claim 6 in iron ore sintering.

8. The use of the modified fuel according to claim 7 in iron ore sintering, wherein the prepared modified fuel, fuel with the particle size of >1mm, flux, blending material and return ore are mixed and granulated to obtain a sintered mixture, and the sintered mixture is subjected to material distribution, ignition, air draft sintering, crushing, cooling and granulating to obtain finished sintered ore and return ore.