CN112941311B - A kind of preparation method of composite cold-pressed pellets for converter steelmaking - Google Patents

Abstract

The invention belongs to the technical field of composite cold-pressed pellets. The technical scheme is as follows: uniformly mixing 5-15 parts by mass of steel rolling oil sludge, 5-15 parts by mass of steel making sludge and 2-8 parts by mass of organic acid, and standing for 20-60 min at 20-60 ℃ to obtain a primary mixed material; adding 15-25 parts by mass of iron scale, 15-30 parts by mass of blast furnace gas mud and 30-40 parts by mass of fly ash into the primary mixed material, and stirring to obtain a secondary mixed material; and then pressing and molding the secondary mixed material, and drying until the moisture content is less than 2wt% to obtain the composite cold-pressed pellet. The invention has the characteristics of simple process, low production cost, no special requirement on equipment and capability of reducing environmental pollution, and the prepared composite cold-pressed pellets for converter steelmaking have high compressive strength.

Description

A kind of preparation method of composite cold-pressed pellets for converter steelmaking

technical field

The invention belongs to the technical field of composite cold-pressed pellets. In particular, it relates to a preparation method of composite cold-pressed pellets for converter steelmaking.

Background technique

In the production process of iron and steel enterprises, a large amount of various types of iron-containing dust sludge will be produced, including various dust removal dust, blast furnace gas sludge, iron oxide scale, steelmaking sludge and steel rolling sludge. These iron-containing dust sludges are complex in type and high in iron content, and have a certain recycling value. At present, the main utilization method of this type of iron-containing dust and sludge is extensive return sintering, but the excessive addition of these iron-containing dust sludge will reduce the Quality of sinter and damage to sinter equipment. In particular, steel rolling sludge and steelmaking sludge have a huge output and are accompanied by foul odors, which are difficult to handle. At present, the commonly used treatment methods in iron and steel enterprises include incineration, pyrolysis, etc., but there is a risk of secondary pollution during the treatment process. Mechanical separation and solvent extraction methods have the problem of small treatment capacity and cannot be applied on a large scale. This has resulted in the accumulation of such solid wastes in factories, occupying land and polluting the environment.

"A method, binder and application of iron ore sintered pellets prepared by using steel oily sludge" (CN110699543 A) patented technology, which proposes a method for preparing iron ore sintered pellets using iron and steel oily sludge to bond The method is to prepare the iron ore sintered pellet binder by carrying out multi-stage solid-liquid separation of oily steel sludge and adding oxidant for catalytic oxidation treatment, and then used in the sintering pelletizing process of iron ore concentrate. This technology solves the problem of recycling oily sludge by catalyzing the oxidation of iron and steel oily sludge to prepare a binder, but the process is relatively complex, requires high equipment and high production costs.

"High-strength composite metallized pellets produced by using metallurgical iron-containing dust and sludge and its production process" (CN 104726699B) patent technology, which proposes a method for producing composite metallized pellets by using metallurgical iron-containing dust and sludge and its production process , the core of pellets is prepared by metallurgical iron-containing dust sludge such as blast furnace gas ash, converter OG sludge, and converter secondary dust ash, and iron concentrate and bentonite are used to make outer shell to obtain composite metallized pellets. However, in this process, bentonite is used as a binder and mixed with iron ore to prepare the shell, and the amount of the binder is large, which reduces the performance index of the pellets, and the preparation process is complicated and the cost is high.

The patented technology of "a rotary hearth furnace treatment process for iron-containing dust and sludge" (CN 107326128 A) proposes a method of mixing iron-containing dust and sludge, a binder and coal powder or carbon-containing dust dust evenly, and then cold-solidified The pellets are formed, and then enter the rotary hearth furnace for reduction and roasting. This process uses a large amount of binder in the process of producing pellets, and the production cost is high.

To sum up, the current recycling process of iron-containing dust and sludge, except for the direct return to sintering, has the problems of large environmental pollution, high equipment requirements and high production cost due to the large amount of binder.

SUMMARY OF THE INVENTION

The main technical problem to be solved by the present invention is to provide a method for preparing composite cold-pressed pellets for converter steelmaking, which is simple in process, low in production cost, has no special requirements for equipment and can reduce environmental pollution. The compressive strength of composite cold-pressed pellets is high.

In order to solve the above-mentioned technical problems, the technical scheme adopted by the present invention is:

Mix 5-15 parts by mass of steel sludge, 5-15 parts by mass of steel-making sludge and 2-8 parts by mass of organic acid, and let stand for 20-60 minutes at 20-60°C to obtain a primary mixing material .

Then, 15-25 parts by mass of iron oxide scale, 15-30 parts by mass of blast furnace gas mud and 30-40 parts by mass of dust removal ash are added to the primary mixing material, and stirred to obtain a secondary mixing material.

Then, the secondary mixed material is press-molded and dried to a moisture content of less than 2 wt % to prepare a composite cold-pressed pellet.

The organic acid is one of acetic acid, oxalic acid and citric acid.

The rolling sludge is a solid waste obtained by chemically treating the rolling oily wastewater in the cold rolling process and the hot rolling process in the rolling mill.

The steelmaking sludge is the sludge obtained by wet dust removal in an oxygen top-blown converter.

The iron oxide scale is an iron-containing oxide produced on the surface of the steel after the rolling stock is rapidly cooled in the rolling process in the rolling mill.

The blast furnace gas sludge is the sludge obtained by precipitation after adopting a wet dust removal system in the blast furnace ironmaking process.

The dust-removing dust is gravity dust-removing dust produced in the process of sintering, iron-making and steel-making.

Due to adopting the above-mentioned technical scheme, the beneficial effects of the present invention compared with the prior art are:

(1) The present invention prepares high-performance composite cold-pressed pellets by replacing the binder with organic acid-modified steel rolling sludge and steelmaking sludge, so that the rolling sludge and steelmaking sludge that are difficult to be handled by iron and steel enterprises can be recycled and utilized, solving the problem of Steel rolling sludge and steelmaking sludge accumulate in large quantities in the factory, occupying land and polluting the environment, reducing environmental pollution.

(2) The present invention uses organic acid modified steel rolling sludge and steelmaking sludge to replace the binder to prepare high-performance composite cold-pressed pellets without the addition of other binders and special equipment, which not only reduces the production of composite cold-pressed pellets The cost of pellets is high, and the prepared composite cold-pressed pellets for converter steelmaking have high compressive strength.

(3) The present invention prepares composite cold-pressed pellets by using steel rolling sludge, steelmaking sludge, iron oxide scale, blast furnace gas sludge and dust removal ash. Simple and scalable.

Therefore, the invention has the characteristics of simple process, low production cost, no special requirements for equipment, and can reduce environmental pollution, and the prepared composite cold-pressed pellets for converter steelmaking have high compressive strength.

Detailed ways

The present invention will be further described below with reference to the specific embodiments, which are not intended to limit the protection scope of the present invention.

A preparation method of composite cold-pressed pellets for converter steelmaking. The preparation method of this specific embodiment is:

Mix 5-15 parts by mass of steel sludge, 5-15 parts by mass of steel-making sludge and 2-8 parts by mass of organic acid, and let stand for 20-60 minutes at 20-60°C to obtain a primary mixing material .

Then, 15-25 parts by mass of iron oxide scale, 15-30 parts by mass of blast furnace gas mud and 30-40 parts by mass of dust removal ash are added to the primary mixing material, and stirred to obtain a secondary mixing material.

Then, the secondary mixed material is press-molded and dried to a moisture content of less than 2 wt % to prepare a composite cold-pressed pellet.

The organic acid is one of acetic acid, oxalic acid and citric acid.

In this specific embodiment, the following technical features are the same in each embodiment:

The steel rolling sludge is solid waste obtained by chemically treating the oil-containing wastewater from steel rolling during cold rolling and hot rolling in iron and steel enterprises;

The steelmaking sludge is the sludge obtained by wet dust removal in an oxygen top-blown converter;

The iron oxide scale is iron-containing oxides produced on the surface of the steel after the rolling stock is rapidly cooled in the rolling process in the rolling mill;

The blast furnace gas sludge is the sludge obtained by the precipitation treatment after adopting the wet dust removal system in the blast furnace ironmaking process;

The dust-removing dust is gravity dust-removing dust produced in the process of sintering, iron-making and steel-making.

It is not repeated in the embodiment.

Example 1

A preparation method of composite cold-pressed pellets for converter steelmaking. The preparation method of the present embodiment is:

8 parts by mass of steel rolling sludge, 5 parts by mass of steelmaking sludge and 2 parts by mass of organic acid were mixed uniformly, and allowed to stand at 20° C. for 60 minutes to obtain a primary mixed material.

Then, 15 parts by mass of iron oxide scale, 30 parts by mass of blast furnace gas sludge and 40 parts by mass of dust removal ash were added to the primary mixed material, and stirred to obtain a secondary mixed material.

Then, the secondary mixed material is press-molded and dried to a moisture content of 1.2 wt % to prepare composite cold-pressed pellets for converter steelmaking.

The organic acid is acetic acid.

The composite cold-pressed pellets for converter steelmaking prepared in this example were tested, and the average compressive strength was 950N.

A comparative example, the preparation method of the comparative example is the same as the present embodiment except that there is no organic acid. The average compressive strength of the prepared composite cold-pressed pellets was 635N.

Example 2

A preparation method of composite cold-pressed pellets for converter steelmaking. The preparation method of the present embodiment is:

5 parts by mass of steel rolling sludge, 15 parts by mass of steelmaking sludge and 8 parts by mass of organic acid were mixed uniformly, and allowed to stand at 40° C. for 40 min to obtain a primary mixed material.

Then, 25 parts by mass of iron oxide scale, 15 parts by mass of blast furnace gas mud and 32 parts by mass of dust removal ash were added to the primary mixed material, and stirred to obtain a secondary mixed material.

Then, the secondary mixed material is press-molded and dried to a moisture content of 0.9 wt % to prepare composite cold-pressed pellets for converter steelmaking.

The organic acid is oxalic acid.

The composite cold-pressed pellets for converter steelmaking prepared in this example were tested, and the average compressive strength was 1275N.

A comparative example, the preparation method of the comparative example is the same as the present embodiment except that there is no organic acid. The average compressive strength of the prepared composite cold-pressed pellets was 456N.

Example 3

A preparation method of composite cold-pressed pellets for converter steelmaking. The preparation method of the present embodiment is:

15 parts by mass of steel rolling sludge, 7 parts by mass of steelmaking sludge and 5 parts by mass of organic acid were mixed uniformly, and allowed to stand at 60° C. for 20 minutes to obtain a primary mixed material.

Then, 20 parts by mass of iron oxide scale, 23 parts by mass of blast furnace gas sludge and 30 parts by mass of dust-removing ash are added to the primary mixed material, and stirred to obtain a secondary mixed material.

Then, the secondary mixed material is press-molded and dried to a moisture content of 0.8 wt % to prepare composite cold-pressed pellets for converter steelmaking.

The organic acid is citric acid.

The composite cold-pressed pellets for converter steelmaking prepared in this example have been tested, and the average compressive strength is 1745N.

A comparative example, the preparation method of the comparative example is the same as the present embodiment except that there is no organic acid. The average compressive strength of the prepared composite cold-pressed pellets was 542N.

The beneficial effects of this specific embodiment compared with the prior art are:

(1) This specific embodiment uses organic acid-modified steel rolling sludge and steelmaking sludge to replace the binder to prepare high-performance composite cold-pressed pellets, so that the rolling sludge and steelmaking sludge that are difficult for iron and steel enterprises to handle can be recycled, It solves the problems that steel rolling sludge and steelmaking sludge accumulate in the factory in large quantities, occupying land and polluting the environment, reducing environmental pollution.

(2) This specific embodiment uses organic acid to modify the rolling sludge and steelmaking sludge to replace the binder to prepare high-performance composite cold-pressed pellets without the addition of other binders and special equipment, which not only reduces the production complex The cost of cold-pressed pellets is high, and the prepared composite cold-pressed pellets for converter steelmaking have high compressive strength.

(3) In this specific embodiment, composite cold-pressed pellets are prepared by using steel rolling sludge, steelmaking sludge, iron oxide scale, blast furnace gas sludge and dust removal ash. , the process is simple and the scalability is strong.

Therefore, this specific embodiment has the characteristics of simple process, low production cost, no special requirements for equipment, and can reduce environmental pollution, and the prepared composite cold-pressed pellets for converter steelmaking have high compressive strength.

Claims (7)

1. A preparation method of composite cold-pressed pellets for converter steelmaking is characterized by comprising the following steps:

uniformly mixing 5-15 parts by mass of steel rolling oil sludge, 5-15 parts by mass of steel making sludge and 2-8 parts by mass of organic acid, and standing for 20-60 min at 20-60 ℃ to obtain a primary mixed material;

adding 15-25 parts by mass of iron scale, 15-30 parts by mass of blast furnace gas mud and 30-40 parts by mass of fly ash into the primary uniform mixture, and stirring to obtain a secondary uniform mixture;

and then pressing and molding the secondary mixed material, and drying until the moisture content is less than 2wt% to obtain the composite cold-pressed pellets.

2. The method for preparing the composite cold-pressed pellets for converter steelmaking according to claim 1, wherein the organic acid is one of acetic acid, oxalic acid and citric acid.

3. The method for preparing the composite cold-pressed pellets for converter steelmaking according to claim 1, wherein the steel rolling oil sludge is solid waste obtained by treating oily wastewater of steel rolling by a chemical method in a cold rolling process and a hot rolling process of a steel rolling mill.

4. The method for preparing the composite cold-pressed pellets for converter steelmaking according to claim 1, wherein the steelmaking sludge is sludge obtained by wet dedusting of a basic oxygen furnace.

5. The method for preparing the composite cold-pressed pellets for converter steelmaking according to claim 1, wherein the iron scale is iron-containing oxide generated on the surface of steel after a rolled piece is cooled rapidly in the rolling process of a steel mill.

6. The method for preparing the composite cold-pressed pellets for converter steelmaking according to claim 1, wherein the blast furnace gas sludge is sludge obtained by precipitation treatment after a wet dust removal system is adopted in a blast furnace ironmaking process.

7. The method for preparing the composite cold-pressed pellets for converter steelmaking according to claim 1, wherein the fly ash is gravity fly ash generated in sintering, ironmaking and steelmaking processes.