CN111733320A

CN111733320A - Granulation method for improving particle size of sintering mixture

Info

Publication number: CN111733320A
Application number: CN202010743961.7A
Authority: CN
Inventors: 唐文博
Original assignee: Pangang Group Research Institute Co Ltd
Current assignee: Pangang Group Research Institute Co Ltd
Priority date: 2020-07-29
Filing date: 2020-07-29
Publication date: 2020-10-02

Abstract

The invention discloses a granulation method for improving the granularity of a sintering mixture, and belongs to the field of ferrous metallurgy. The invention mixes the dedusting ash and the fine active lime, adds water to digest, fully stirs and prepares pulp, mixes with the coarse active lime after adding water to digest and other sintering materials to pelletize and obtain sintering mixture. The process of mixing, adding water and digesting carries out prewetting on the fly ash, and simultaneously the heat released by the digestion of the active lime can increase the temperature of fly ash particles, thereby improving the water absorption speed of the fly ash and making up the adverse effect of the hydrophobicity of the fly ash on sintering granulation to a certain extent. In addition, because the fly ash and the fine active ash particles are smaller, the core particles required by granulation are not needed, and the fly ash and the fine active ash particles are not aggregated after mixing, the uniformity of the slurry is ensured, and the digested active ash has viscosity and can be adhered with the fly ash particles, so that the granulation capability of the fly ash is improved, the particle size composition of a sintering mixture is favorably improved, and the technical and economic indexes of the sintering ore are improved.

Description

Granulation method for improving particle size of sintering mixture

Technical Field

The invention belongs to the field of ferrous metallurgy, and particularly relates to a granulation method for improving the granularity of a sintering mixture.

Background

The sintering process is the process of mixing iron-containing material, fuel and flux, adding water to pelletize and igniting to sinter, and the size, micro shape and other performance of the sintering material are important factors affecting the size of the mixture. The sintering fly ash contains more valuable elements, and most of domestic iron and steel enterprises use the sintering fly ash as a sintering material, but due to the characteristics of fine particle size, poor balling performance, poor hydrophilicity and the like of the fly ash, the proportion of the fly ash added into the sintering material is improved, the particle size composition of the vanadium-titanium sintering ore mixture can be further deteriorated, and the air permeability of the sintering mixture is reduced. Meanwhile, the ash discharge amount of the dust removing ash is difficult to stabilize, and the proportion will fluctuate, so that the stable production of the sinter is not facilitated.

Disclosure of Invention

The invention aims to solve the technical problem that the particle size composition of a sintering mixture is influenced after sintering fly ash is added.

The technical scheme adopted by the invention for solving the technical problems is as follows: a granulation method for improving the particle size of a sintering mixture comprises the following steps:

a. weighing dedusting ash, wherein the mass of the dedusting ash is 1-3% of the total weight of the new sintering material; weighing active lime, wherein the mass of the active lime is 4-8% of the total weight of the new sintering material;

b. sieving active lime to obtain oversize product and undersize product with sieve aperture of 0.2-0.25 mm;

c. fully mixing the undersize product and the fly ash, adding water for digestion, and uniformly mixing to obtain mixed slurry; directly adding water to digest the oversize product;

d. and mixing the completely digested mixed slurry and oversize materials with other sintering materials, and granulating to obtain a sintering mixture.

As will be understood by those skilled in the art, the sinter material mainly comprises iron-containing materials (iron ore concentrate, fine ore, rich ore, iron-containing secondary resource, etc.), a solvent (activated ash, quicklime, limestone, etc.), a fuel (mainly coke breeze, washed coal), and return ores (generally, sinter ore smaller than 5 mm), and the materials except for the return ores are new materials.

In the method, the water consumption in the digestion process of the step c is controlled, and the moisture content of the sintering mixture in the step d is controlled within the range of 7.5 +/-0.2%.

Wherein, the aperture of the sieve in the step b of the method is 0.25 mm.

In the method, the proportion of the particle size of the dust removal ash is less than 0.25mm and more than 80%, and the proportion of less than 0.5mm is 100%.

In the step a of the method, the mass of the fly ash is 2 percent of the total weight of the new sintering material.

In the method, the mass of the active lime is 7.5 percent of the total weight of the new sintering material.

In the method, the CaO content in the active lime is more than or equal to 85 percent.

The mixing and granulating process in the step d of the method adopts two sections.

Further, the time for mixing and granulating in the two stages is 3-5 minutes.

The invention has the beneficial effects that: mixing the fly ash and fine active lime, adding water for digestion, fully stirring for pulping, and mixing with other sintering materials to obtain a sintering mixture; the mixing and water adding digestion is carried out on the fly ash for prewetting, and simultaneously, the heat discharged by the digestion of the active lime can increase the temperature of fly ash particles, thereby increasing the water absorption speed of the fly ash and compensating the adverse effect of the hydrophobicity of the fly ash on sintering granulation to a certain extent. In addition, because the fly ash and the fine active ash particles are smaller, the core particles required by granulation are not needed, and the fly ash and the fine active ash particles are not aggregated after mixing, the uniformity of the slurry is ensured, and the digested active ash has viscosity and can be adhered with the fly ash particles, so that the granulation capability of the fly ash is improved, the particle size composition of a sintering mixture is favorably improved, the technical and economic indexes of the sintered ore are improved, and the stability of the components of the sintered ore is improved.

Detailed Description

The granulation method for improving the granularity of the sintering mixture comprises the following steps:

In order to optimize the granulation performance, the moisture content of the sinter mix in step d is preferably controlled to be in the range of 7.5% ± 0.2% by controlling the amount of water used in the digestion process of step c.

Likewise, the preferred sieve size in step b is 0.25 mm. The particle size of the dust is preferably more than 80% in a fraction of <0.25mm and 100% in a fraction of <0.5 mm.

Preferably, the mass of the fly ash in the step a is 2% of the total weight of the new sintering material. The mass of the active lime is preferably 7.5 percent of the total weight of the sintering fresh material.

The CaO content in the active lime is more than or equal to 85 percent.

Preferably, the mixing granulation process in step d is carried out in two stages. It is further preferred that the time for both mixing and granulation stages is 3-5 minutes.

The present invention is further illustrated by the following examples.

Example (b):

the fly ash and the active ash with the mass of 2 percent and 7.5 percent of the total weight of the new sintering material are respectively weighed, the fly ash of the first part is directly mixed in a first mixing mode (namely, first-stage mixing granulation), and the active ash is mixed after digestion (as a comparative example). And screening the fly ash, mixing the part below 0.25mm with the fly ash, adding water, digesting the active ash, stirring to prepare pulp, directly digesting the active ash above 0.25mm, respectively adding the first mixture (example), and then performing second-mixture mixing (i.e. second-stage mixing granulation). Carrying out a sintering experiment, controlling the moisture of the mixture within the range of 7.5 +/-0.2%, controlling the first mixing time to be 4min, the second mixing time to be 4min, sintering new material amount to be 70kg, material layer to be 700mm, externally preparing 30% of return ores (the return ores are specially fired to ensure that the granularity components of the return ores are the same), paving 2.5kg of bottom materials, sintering ignition time to be 2min, ignition temperature to be 1050 +/-50 ℃, and a sintering ore preparation scheme as follows (Table 1):

TABLE 1 sintering batch structure

Name (R)	Dry matter proportion/%)
		White horse concentrate	42
Taihe concentrate	3
		Plain concentrate	5.5
Height of 58 nation	6.5
		South African mine	13.5
Material screening	7
		Dust removal ash	2
Gas ash	5
		Coke powder	4
Limestone	4
		Active ash	7.5

The sintering experiment is carried out by the above burdening scheme and experimental method, and the particle size of the mixture is firstly counted, as shown in table 2:

TABLE 2 particle size/% of the mixture

Size fraction/mm	>8	8-5	5-3	3-1	<1	>3
							Comparative example	1.3	13.4	43.8	27.6	13.9	58.5
Examples	1.2	13.8	46.6	25.8	12.6	61.6

After mixing the fly ash and the fine active ash, adding water to digest the active ash, stirring and pulping simultaneously, pre-wetting the fly ash to a certain degree can be carried out, and simultaneously the heat emitted by digesting the active ash can improve the temperature of the fly ash particles, so that the water absorption speed of the fly ash is improved, and the adverse effect of the hydrophobicity of the fly ash on sintering granulation is compensated to a certain degree. Meanwhile, the active ash mixed slurry uses fine active ash with the particle size of less than 0.25mm, the total particle size of the dust is less than 0.5mm, the particle size of less than 0.25mm reaches about 95%, the active ash mixed slurry belongs to adhesive powder in the granulation process, no pelletizing core particle is formed after mixing, no large particle occurs in the pulping process, but the dust particle and the active ash particle can be adhered to a certain degree and are uniformly distributed in the slurry, so that the granulation performance of the dust is improved to a certain degree, and the uniformity of the sintering mixture is not influenced. From the results in the table, the implementation of the method of the patent can increase the proportion of the grain size of the sintering mixture of more than 3mm by 3.1 percent, and obviously improve the sintering, mixing and granulating effects.

The sintering experiment sintering technical economic indexes are shown in table 3:

TABLE 3 sintering technical economic index/%)

From the above table, it can be seen that the utilization coefficient of the sintered ore is significantly improved, and the drum index and the yield of the sintered ore are also slightly increased after the application of the method.

In conclusion, after the method is implemented, the granulating capacity of the sintering mixture is improved, the proportion of the grain size of more than 3mm is increased by 3.1%, the utilization coefficient of the sintering ore is obviously improved, and the drum index and the yield of the sintering ore are also slightly increased.

Claims

1. A granulation method for improving the particle size of a sintering mixture is characterized by comprising the following steps:

2. A granulation process to improve the particle size of a sinter mix as claimed in claim 1, wherein: and d, controlling the water consumption in the digestion process in the step c, and controlling the moisture content of the sintering mixture in the step d to be within 7.5 +/-0.2%.

3. A granulation process to improve the particle size of a sinter mix as claimed in claim 1, wherein: in the step b, the aperture of the sieve is 0.25 mm.

4. A granulation process to improve the particle size of a sinter mix as claimed in claim 1, wherein: the particle size of the dust removal ash is less than 0.25mm, the proportion of the particle size fraction is more than 80%, and the proportion of less than 0.5mm is 100%.

5. A granulation process to improve the particle size of a sinter mix as claimed in claim 1, wherein: the mass of the fly ash in the step a is 2 percent of the total weight of the new sintering material.

6. A granulation process to improve the particle size of a sinter mix as claimed in claim 1 or claim 5, wherein: the mass of the active lime accounts for 7.5 percent of the total weight of the new sintering material.

7. A granulation process to improve the particle size of a sinter mix as claimed in claim 1, wherein: the CaO content in the active lime is more than or equal to 85 percent.

8. A granulation process to improve the particle size of a sinter mix as claimed in claim 1, wherein: in the step d, two sections are adopted in the mixing and granulating process.

9. The granulation method for improving the particle size of a sinter mix, as claimed in claim 8, wherein: the time for mixing and granulating the two sections is 3-5 minutes.