CN114410963A - Binder for pickling sludge and gravity ash cold-solidified pellets and preparation method thereof - Google Patents

Abstract

The invention discloses a binder for acid-washing sludge and gravity ash cooled agglomerated pellets and a preparation method thereof, wherein the binder comprises the following components in percentage by mass: 10-45% of bentonite and 55-90% of vegetable oil asphalt; the preparation method comprises mixing bentonite 10-45% and vegetable oil asphalt 55-90%, and grinding to obtain the composite binder. According to an ideal molecular theory model of the composite binder, vegetable oil asphalt which is rich in hydrophilic groups and has viscosity is selected as an organic component, and the proportion of the inorganic component and the organic component is scientifically regulated and controlled to prepare the composite binder. The composite binder has the advantages of improving the strength of the pellets, low cost, no pollution, no harm and the like on the premise of not influencing the grade of metals in the cold-bonded pellets. The composite binder and the metallurgical solid wastes are subjected to cold solidification pelletizing, so that the valuable elements in the metallurgical solid wastes are recycled, the vegetable oil asphalt with huge yield is absorbed, the resources can be further saved, the cost is reduced, and the effect is improved.

Description

Binder for pickling sludge and gravity ash cold-solidified pellets and preparation method thereof

technical field

The invention relates to the technical field of secondary resource utilization of pickling sludge in a metallurgical process, in particular to a binder for cold-solidified pellets of pickling sludge.

Background technique

With the rapid development of my country's metallurgical industry, the impact of dust and sludge produced in the production process of iron and steel enterprises on the environment has attracted more and more attention. After pickling and passivation of stainless steel, a large amount of pickling wastewater will be produced, which will become pickling sludge after neutralization and precipitation. Pickling sludge has the characteristics of high water content, high TFe, and high viscosity. Gravity dust removal is the coarser particles that are removed by the gravity dust collector by the waste gas discharged from the top of the blast furnace carrying a large amount of raw fuel dust and the particles produced by the intense reaction in the high temperature area. Gravity dust has the characteristics of high C content and large particles. Pickling sludge and gravity dust are good secondary metallurgical resources. Landfill treatment will not only increase space costs, cause environmental pollution, but also cannot recycle valuable elements in dust sludge.

At present, the main methods for the recycling of pickling sludge are: physical method, wet method, fire method, combined fire-wet method, pelletizing method and sintering method. The removal efficiency of harmful elements by physical method is low, and it is only used as a pretreatment process of wet method or fire method. The wet method has problems such as serious industrial pollution, large consumption of leaching agent, and cumbersome removal of impurities. The fire method has problems such as large fluctuation of metallization rate, poor product quality and high energy consumption. The sintering method has shortcomings such as limitations in the particle size of dust and sludge, difficult control of dust and sludge ingredients, and cyclic enrichment of harmful elements. The cold-solid pelletizing process in the pelletizing method has the advantages of uniform finished product size, simple process, low energy consumption, and simple equipment. Therefore, cold-solid pellets are generally used for resource recovery and utilization of dust sludge. The metallurgical dust and sludge are cold-consolidated and used in blast furnaces to realize resource recycling, which not only reduces environmental pollution, but also reduces energy consumption.

The cold consolidation molding process is to mix all kinds of dust generated in the metallurgical process, add a binder and mix it, press it into agglomerates with a certain shape, size, density and strength, and then go through the corresponding low temperature drying (<300 ℃). ) for consolidation to increase the strength of the agglomerate. The agglomerates can be used as raw materials for blast furnace smelting, coolants and slag-forming agents for converter smelting, and can also be used as raw materials for direct reduction and smelting reduction. The key to determining the quality of pellets in cold-set pellets is the binder. According to the main binder components, the binders can be divided into three categories: inorganic binders, organic binders and composite binders: Inorganic binders mainly include: bentonite, water glass, slaked lime, magnesium chloride hexahydrate Wait. Organic binders mainly include: polyvinyl alcohol, polyacrylamide, sodium carboxymethyl cellulose, sodium carboxymethyl starch, etc. The composite binder is composed of organic components and inorganic components, and has the advantages of both inorganic binders and organic binders, so it has become a current research hotspot. Bentonite has excellent performance, low cost and mature application, but its high burning residue rate seriously reduces the iron grade of pellets, increases the amount of slag smelted in blast furnace iron smelting, reduces blast furnace coefficient and increases fuel consumption; organic binders The bonding effect is good and the dosage is small, but its price is high and the application is immature. Therefore, most scholars currently conduct research on bentonite-based composite binders. Such as: humic acid modified bentonite composite binder, polyacrylamide modified bentonite composite binder and carboxymethyl cellulose nano modified bentonite composite binder.

Chinese patent document CN 110629021 A provides a binder for solidifying pellets of converter solid dust waste at room temperature. The process adopted in this patent introduces phosphorus elements that reduce the plasticity and toughness of steel, thus hindering the application of the technology. Promote the application. Chinese patent document CN 109134946 A provides a powdery material environmentally friendly binder and a preparation method thereof. The binder needs to be dried and pulverized twice in the preparation process, the preparation process is complicated, and there are large dust and high energy consumption. question. Chinese patent document CN 109971947 A provides a cold solidified pellet and its preparation and use method. The mixture of starch and water is used as a binder, which has problems such as high production cost, poor high temperature performance, etc., and it is difficult to achieve blast furnaces, converters and electric furnaces. temperature range. In view of the deficiencies of the above technologies, the present invention proposes a binder for pickling sludge and gravity ash cold-solidified pellets.

SUMMARY OF THE INVENTION

To achieve the above objects, the present invention utilizes an ideal molecular structure model PXY _n . In the present invention, the ideal model PXY _n includes a solid-philic group X that chemically interacts with the surface of the mineral powder, a hydrophilic group (Y) that enhances the hydrophilicity of the mineral surface; a frame with good thermal stability (P ) composition; suitable molecular weight (degree of polymerization n). For the ideal model of PXY _n , the HMO algorithm in quantum chemistry is used to study the group electronegativity, ionic bond fraction, CMC calculation and bond properties. It is further obtained that the carboxyl group (-COOH) is an ideal ore-philic group, and the hydroxyl group (-OH) is an ideal hydrophilic group. Based on this ideal model and the reality of the high cost of organic components in composite binders, considering that the vegetable oil asphalt with large yield and low price contains solid-philic carboxyl groups and hydrophilic groups of hydroxyl groups, the As the organic component of the composite binder, not only can good bonding performance be obtained, but also the cost of the composite binder can be reduced, so the binder according to the present invention selects vegetable oil pitch as one of the components of the binder.

Specifically, the present invention first provides a binder for acid-washed sludge and gravity ash cold-solidified pellets, the mass percentages of which are: bentonite 10-45% and vegetable oil pitch 55-90%.

Further, the mass percentage of bentonite is 40-45%, and the mass percentage of vegetable oil asphalt is 55-60%.

Further, vegetable oil pitch is a by-product of vegetable oil refining.

The invention also provides a method for preparing a binder for acid-washed sludge and gravity ash cold-solidified pellets. The binder is obtained after grinding.

The invention also provides acid-washed sludge and gravity ash cold-solidified pellets. The composition mass percentage of the pellets is: pickling sludge 78.3%-82.5%, gravity ash 15.7%-16.5%, binder 1% -6%; wherein, the mass percentage of the components of the binder is: bentonite 10-45%, vegetable oil pitch 55-90%.

Further, the water content of the pickling sludge is 0-5%, the sulfur element content is 0-5%, the zinc content in the gravity dust is 0-1%, the carbon content is 0-50%, and the Σ(Na) in the bentonite is 0-1%. ⁺ +K ⁺ )/Σ(Ca ²⁺ Mg ²⁺ )≥1.

The invention provides a method for preparing acid-washed sludge and gravity ash cold-solidified pellets. The acid-washed sludge and gravity dust-removing ash are mixed uniformly, and then a binder and water are added; 0.5%-8% of the mass of gravity ash, and the content of water is 3%-10%; after mixing and grinding, the pressure is 25MPa for cold pressing to obtain green balls; the green balls are dried to obtain balls; The mass percentage of the components of the binder is: bentonite 10-45%, vegetable oil pitch 55-90%.

Further, the pickling sludge and gravity dust are mixed in a ratio of 5:1 by mass.

Further, the dosage of the binder is 1%-6%, and the dosage of water is 8%.

Further, the mass percentage of bentonite in the binder is 40-45%, and the mass percentage of vegetable oil asphalt is 55-60%.

The special binder for acid-washed sludge and gravity ash cold-set pellets provided by the invention can effectively reduce the cost of the binder and improve the cold-set pellets when the acid-washed sludge and gravity ash are used to prepare cold-set pellets. It can fully improve the utilization rate of pickling sludge and reduce environmental pollution.

Using the binder, pickling sludge and gravity ash to prepare cold-set pellets has the following advantages:

(1) The size of the finished product is uniform, and no granulation treatment is required.

(2) The finished product after further processing has a larger angle of repose due to its special geometry when it is smelted into the furnace, which reduces material segregation.

(3) The briquetting equipment is simple, low in investment, easy to manage and low in energy consumption. It is an energy-saving and environmentally friendly agglomeration method.

The present invention is a composite binder of organic binder and inorganic binder, and has the advantages of both, the dosage is low, the raw material sources are wide, the production equipment and the environment are friendly, and the price is low.

The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings, so as to fully understand the purpose, characteristics and effects of the present invention.

Description of drawings

Fig. 1 is a process flow diagram of the present invention.

Detailed ways

The following describes several preferred embodiments of the present invention with reference to the accompanying drawings, so as to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned herein.

Fig. 1 is a process flow diagram of the present invention. In the embodiment of the present invention, the raw material pickling sludge, gravity dust, and bentonite are provided by a stainless steel factory, wherein the water content of the pickling sludge is about 55%, and the chemical components after drying are: TFe, Ni, Cr, S, Ca and Si were 18.4%, 0.57%, 3.13%, 4.67%, 16.97% and 2.09%, respectively; gravity dust removal: TFe, Cr, Zn, Ni, C, Si and Ca were 17.29%, 1.05%, 0.56%, 0.38%, 43.25%, 4.26% and 1.41%; Bentonite: TFe, Al, Si, K, Ca and Ti were 12.63%, 17.64%, 54.57%, 4.22%, 3.39% and 1.48%, respectively.

Example 1

1. Preparation of the binder

The content of bentonite is 40%, the content of vegetable oil asphalt is 60%, and the two are mixed and milled for 15-20 minutes to obtain a composite binder.

2. Preparation of acid-washed sludge and cold-solidified pellets of gravity dust removal ash

Mix the pickling sludge and gravity dust ash according to the ratio of 5:1, then add the above-mentioned binder. Cooling and standing for 5-10 minutes, then cold-pressing at a pressure of 25 MPa to obtain green balls, the mass of a single green ball is 2.5-3.0 g, and the green balls are dried at 120° C. for 2 hours to obtain balls. Among them, the distribution ratio of each group is shown in Table 1. The average drop strength of green balls was 9 times, and the average compressive strength of green balls was 66.4N. The average drop strength of the formed ball is 128 times, and the average compressive strength of the formed ball is 220.92N.

Table 1

name Pickling sludge Gravity dust removal binder water Proportion (%) 75 15 2 8

Example 2

1. Preparation of the binder

The content of bentonite is 45%, the content of vegetable oil asphalt is 55%, and the two are mixed and milled for 15-20 minutes.

2. Preparation of acid-washed sludge and cold-solidified pellets of gravity dust removal ash

Mix the pickling sludge and gravity dust ash according to the ratio of 5:1, then add the above-mentioned composite binder. , and then cool and stand for 5-10 minutes, and then cold-pressed at a pressure of 25MPa to obtain green balls. The mass of a single green ball is 2.5-3.0g, and the green balls are dried at 120 degrees Celsius for 2 hours to obtain balls. Among them, the distribution ratio of each group is shown in Table 2, the average falling strength of the green ball is 19 times, and the average compressive strength of the green ball is 79.8N. The average drop strength of the formed ball is 172 times, and the average compressive strength of the formed ball is 249.65N.

Table 2

name Pickling sludge Gravity dust removal binder water Proportion (%) 75 15 4 8

Example 3

1. Preparation of the binder

The content of bentonite is 45%, the content of vegetable oil asphalt is 55%, and the two are mixed and milled for 15-20 minutes.

2. Preparation of acid-washed sludge and cold-solidified pellets of gravity dust removal ash

Mix the pickling sludge and gravity dust ash according to the ratio of 5:1, then add the above-mentioned composite binder. , then cool and stand for 5-10 minutes, and then cold-pressed at a pressure of 25 MPa to obtain green balls. The mass of a single green ball is 2.5-3.0 g. The green balls are dried at 120 ° C for 2 hours to obtain balls. Among them, the distribution ratio of each group is shown in Table 3. The average drop strength of green balls was 27 times, and the average compressive strength of green balls was 89.5N. The average drop strength of the ball is 210 times, and the average compressive strength of the ball is 216.4N.

table 3

name Pickling sludge Gravity dust removal binder water Proportion (%) 72 14 6 8

The preferred embodiments of the present invention have been described in detail above. It should be understood that many modifications and changes can be made according to the concept of the present invention by those skilled in the art without creative efforts. Therefore, any technical solutions that can be obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the prior art according to the concept of the present invention shall fall within the protection scope determined by the claims.

Claims (10)

1. The binder for the acid-washed sludge and the gravity ash cooled agglomerated pellets is characterized by comprising the following components in percentage by mass: 10-45% of bentonite and 55-90% of vegetable oil asphalt.

2. The binder for acid-washed sludge and gravity ash cooled agglomerated pellets according to claim 1, wherein the bentonite accounts for 40-45% by mass, and the vegetable oil asphalt accounts for 55-60% by mass.

3. The binder for acid-washed sludge and gravity ash cooled agglomerated pellets of claim 1, wherein the vegetable oil pitch is a by-product of vegetable oil refining.

4. A preparation method of a binder for acid-washed sludge and gravity ash cooled agglomerated pellets is characterized in that the binder is obtained by mixing 10-45% of bentonite and 55-90% of vegetable oil asphalt and grinding the bentonite and the vegetable oil asphalt.

5. The acid-washed sludge and gravity ash cooled agglomerated pellets are characterized by comprising the following components in percentage by mass: 78.3-82.5% of acid-washing sludge, 15.7-16.5% of gravity ash and 1-6% of binder; wherein the binder comprises the following components in percentage by mass: 10-45% of bentonite and 55-90% of vegetable oil asphalt.

6. The acid-washed sludge and gravity ash cooled agglomerated pellets of claim 5, wherein the acid-washed sludge has a water content of 0-5%, a sulfur content of 0-5%, a zinc content of 0-1%, a carbon content of 0-50% in the gravity ash, and sigma (Na) in the bentonite clay⁺+K⁺)/Σ(Ca²⁺Mg²⁺)≥1。

7. A preparation method of acid-washed sludge and gravity ash cooled agglomerated pellets is characterized in that the acid-washed sludge and the gravity ash are uniformly mixed and then added with a binder and water; the mixing amount of the binder is 0.5-8% of the mass of the acid-washed sludge and the gravity ash, and the mixing amount of the water is 3-10%; cold press molding is carried out by adopting the pressure of 25MPa after mixing and grinding to obtain green balls with the granularity of 6.4-12.7 mm; drying the green balls at the temperature lower than 300 ℃ to obtain the green balls; wherein, the content of silicon dioxide in the ball is 0-5.5%, and TFe is not less than 55%; wherein the binder comprises the following components in percentage by mass: 10-45% of bentonite and 55-90% of vegetable oil asphalt.

8. The method for preparing acid-washed sludge and gravity ash cold-bonded pellets according to claim 7, wherein the acid-washed sludge and the gravity dedusting ash are mixed uniformly according to the mass ratio of 5: 1.

9. The method for preparing acid-washed sludge and gravity ash cold-bonded pellets as claimed in claim 7, wherein the mixing amount of the binder is 1% -6% and the mixing amount of the water is 8%.

10. The method for preparing acid-washed sludge and gravity ash cold-bonded pellets as claimed in claim 7, wherein the mass percentage of bentonite in the binder is 40-45%, and the mass percentage of vegetable oil asphalt is 55-60%.

Images