CN115820945A - Regulating agent for separating and enriching iron in iron and steel dust mud, method and application - Google Patents

Abstract

The invention provides a regulating agent for separating and enriching iron in iron and steel dust mud, a method and application thereof. The regulating agent comprises one or more of ferric chloride hexahydrate and ferric chloride trihydrate. The method for separating and enriching iron in the iron and steel dust comprises the following steps: mixing the iron and steel dust mud and a regulating agent to carry out hydrothermal reaction. Adding water into the reactant, centrifugally cleaning and separating to obtain an iron-enriched precipitate and a zinc-containing separation solution. Under the hydrothermal condition, crystal water in the regulating agent is separated and iron ions are hydrolyzed, hydrogen ions generated in the hydrolysis process can enable iron and steel dust mud to generate ore phase transformation to release internal zinc, nucleation and growth of hematite are accelerated by the existence of the regulating agent, iron elements are enriched in precipitates, other metal ions are retained in a solution, and separation and enrichment of the iron elements are realized. The regulating agent can realize effective separation of metal elements by a mineral phase hydrothermal method, thereby avoiding the problem of subsequent acid treatment and reducing pollution; and shortens the process flow.

Description

Regulating agent, method and application of iron separation and enrichment in iron and steel dust

technical field

The invention relates to the technical field of separation and recovery of iron and steel dust, in particular to a regulator, method and application of iron separation and enrichment in iron and steel dust.

Background technique

As the second most abundant metal in the earth's crust, iron is currently the most important metal material. Iron is widely used in pharmaceuticals, pesticides, powder metallurgy, thermal hydrogen generators, gel propellants, combustion activators, catalysts, water cleaning adsorbents, sintering activators, powder metallurgy products, various mechanical parts products, hard alloys Material products and other fields. Pure iron is used to make iron cores for generators and motors, reduced iron powder is used for powder metallurgy, and steel is used to make machines and tools. In addition, iron and its compounds are also used to make magnets, medicines, inks, pigments, abrasives, etc. Iron is also one of the essential trace elements needed by the human body, which shows the importance of iron.

Iron and steel is the foundation of industrial products, and the iron and steel smelting industry is an important basic industry of the national economy. However, in the process of processing and production, the iron and steel smelting industry not only needs to invest a lot of material resources and energy resources, but also discharges a lot of waste water, waste gas and solid waste. These wastes are harmful to the environment and pose a threat to human health. Among them, iron and steel smelting will produce a large amount of iron and steel dust, which is one of the main solid wastes faced by the smelting industry.

Iron and steel dust mainly comes from ironmaking, steelmaking, sintering, steel rolling and other links in the iron and steel smelting process. It contains a variety of alkali metals and heavy metal elements, and the recycling rate is low. The amount of iron and steel metallurgical dust generated is about 10% to 12% of the crude steel output. Assuming that my country's crude steel output in 2020 is 1.065 billion tons, the generated iron and steel smelting dust has reached 106.5 to 127.8 million tons. Zinc-containing dust is a typical iron-containing waste slag produced in the iron and steel smelting process. The production of zinc-containing dust is about 10% of crude steel production, and the annual output of zinc-containing dust in China is more than 80 million tons.

At present, the methods for dealing with zinc-containing dust in iron and steel plants mainly include fire method, wet method and combined method. The fire method is mainly used for low-zinc dust, among which the rotary hearth furnace and rotary kiln process are the most widely used. The roasted ore obtained by the rotary kiln process can be separated by magnetic separation to obtain a magnetically separated concentrate with high iron grade and low zinc content; the rotary hearth furnace process can obtain a roasted product with an iron grade of 56.71% and a Zn content of 0.07%. However, the rotary kiln is easy to form rings, and the operation requirements are high. Improper operation will cause nodules in one month, the operation rate is low, and the equipment investment is large, the operation cost is high, and the energy consumption is large. The elements in the rotary hearth furnace process dust are relatively complex, and subsequent treatment and recovery are difficult; and the process has high maintenance costs, high energy consumption, and low efficiency. In addition, the pyrotechnic process will also cause secondary pollution, which is poor in environmental protection. In the wet leaching process, the leaching rate of zinc ferrite spinel in iron and steel dust sludge is low, and a large amount of acid or alkali is required for leaching. The acid leaching process will produce a large amount of acid sludge, which is difficult for subsequent treatment.

Contents of the invention

The main purpose of the present invention is to provide a regulating agent, method and application of iron separation and enrichment in iron and steel dust to solve the technical problems of complicated iron and steel dust treatment process, less pollution and simple post-treatment.

To achieve the above object, the first aspect of the present invention provides a regulator for iron separation and enrichment in iron and steel dust, the regulator includes one or more of ferric chloride hexahydrate and ferric chloride trihydrate kind.

The second aspect of the present invention provides a method for iron separation and enrichment in iron and steel dust, comprising the following steps:

The iron and steel dust sludge is mixed with a regulating agent, and the hydrothermal reaction is carried out in a closed container, and the regulating agent includes one or more of ferric chloride hexahydrate and ferric chloride trihydrate.

The reactant was washed with water, and the precipitate was separated to obtain an iron-enriched precipitate.

According to the embodiment of the present application, the steps of washing the reactant with water, separating the precipitate, and obtaining the iron-enriched precipitate include:

The reactant was washed with water, and the precipitate was centrifuged to obtain an iron-enriched precipitate.

According to an embodiment of the present application, the reaction temperature of the hydrothermal reaction is 150°C to 200°C.

According to an embodiment of the present application, the reaction temperature of the hydrothermal reaction is 180-200°C.

According to the embodiment of the present application, the duration of the hydrothermal reaction is 2-20 hours.

According to the embodiment of the present application, the duration of the hydrothermal reaction is 4-10 hours.

According to the embodiment of the present application, the mass ratio of the regulating agent to the iron and steel dust is (1~2):1.

According to an embodiment of the present application, in the step of washing the reactant with water and separating the precipitate, the separated liquid phase is collected to obtain a zinc-containing separation liquid.

The third aspect of the present invention provides an application of the above-mentioned iron separation and enrichment method in steel dust sludge recovery.

The aforementioned regulating agent for iron separation and enrichment in iron and steel dust sludge includes one or more of ferric chloride hexahydrate and ferric chloride trihydrate. In the case of hydrothermal reaction, the crystal water in the regulating agent is detached and the iron ions are hydrolyzed, and the hydrogen ions generated in the hydrolysis process can make the steel dust sludge undergo mineral phase transformation and release the internal zinc, and the presence of the regulating agent accelerates redox. The nucleation and growth of iron ore enriches the iron element in the precipitate, while other metal ions remain in the solution, realizing the separation and enrichment of iron element. The regulating agent can realize the effective separation of metal elements through mineral phase hydrothermal method, avoid the problem of subsequent acid treatment, reduce pollution; and shorten the process flow.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained according to the structures shown in these drawings without creative effort.

Fig. 1 is a schematic flow diagram of a method for iron separation and enrichment in iron and steel dust sludge realized by mineral phase hydrothermal control method according to an embodiment of the present application;

Fig. 2 is the XRD pattern of the electric furnace dust sludge before the reaction and the iron-enriched precipitate after the reaction in Example 1, wherein: Fig. 2 (a) is the XRD pattern of the electric furnace dust sludge before the reaction, and Fig. 2 (b) is the iron after the reaction XRD pattern of enriched precipitate;

Fig. 3 is the scanning electron micrograph of the electric furnace dust sludge before the reaction and the iron-enriched precipitate after the reaction in Example 1, wherein: Fig. 3 (a) is the scanning electron micrograph of the electric furnace dust sludge before the reaction, and Fig. 3 (b) is after the reaction Scanning electron micrographs of iron-enriched precipitates;

Fig. 4 is the change diagram of iron and zinc element content in the electric furnace dust sludge and iron-enriched sediment before and after the reaction in the implementation 1;

Fig. 5 is the XRD pattern of the converter dust sludge before the reaction and the iron-enriched precipitate after the reaction in Comparative Example 1;

Fig. 6 is the XRD pattern of the converter dust sludge before the reaction and the iron-enriched precipitate after the reaction in Comparative Example 2.

The realization of the purpose of the present invention, functional characteristics and advantages will be further described with reference to the accompanying drawings in combination with the implementation modes.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the implementation manners in the present invention, all other implementation manners obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

It should be noted that all directional indications (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship, movement, etc. between the components in a certain posture (as shown in the drawings), If the specific posture changes, the directional indication also changes accordingly.

In addition, in the present invention, descriptions such as "first", "second" and so on are used for description purposes only, and should not be understood as indicating or implying their relative importance or implicitly indicating the quantity of indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of these features.

Moreover, the technical solutions of the various embodiments of the present invention can be combined with each other, but it must be based on the realization of those skilled in the art. When the combination of technical solutions is contradictory or cannot be realized, it should be considered as a combination of technical solutions. Does not exist, nor is it within the scope of protection required by the present invention.

The invention provides a regulating agent for iron separation and enrichment in iron and steel dust sludge. The regulating agent includes one or more of ferric chloride hexahydrate and ferric chloride trihydrate.

The iron and steel dust can be zinc-containing dust, for example, it can be one or more of electric furnace dust and converter dust. Both ferric chloride hexahydrate and ferric chloride trihydrate are in powder form during use.

The aforementioned regulating agent for iron separation and enrichment in iron and steel dust sludge includes one or more of ferric chloride hexahydrate and ferric chloride trihydrate. Under hydrothermal conditions, the crystallization water in the regulator is detached and the iron ions are hydrolyzed, and the hydrogen ions generated during the hydrolysis process can cause the steel dust to undergo a mineral phase transformation and release the internal zinc. At the same time, the presence of the regulator accelerates the hematite Nucleation and growth enrich the iron element in the precipitate, and other metal ions remain in the solution to realize the separation and enrichment of iron element.

In order to complete the separation and enrichment of metal ions in iron and steel dust, the present invention provides a method for iron and zinc separation and iron element enrichment in iron and steel dust by hydrothermal control of ore phase, comprising the following steps:

S100: mixing iron and steel dust with a regulator, and performing a hydrothermal reaction in an airtight container, where the regulator includes one or more of ferric chloride hexahydrate and ferric chloride trihydrate.

In this step, steel dust and regulator are mixed to obtain a reaction precursor. The mixing time for mixing steel dust and regulator can be 10-30 min. In this way, the iron and steel dust and the regulator are mixed evenly.

The airtight container can be opened and closed after the reaction precursor is loaded, for example, it can be a hydrothermal reactor. The hydrothermal reaction kettle is heated for hydrothermal reaction. In this process, the gas in the airtight container is heated and expanded, which will provide a reaction environment with a certain pressure for the reaction precursor.

Hydrothermal reaction refers to the general term for related chemical reactions in fluids such as water, aqueous solution or steam at a certain temperature and pressure.

Regarding the hydrothermal reaction, in one embodiment of the present application, during the heating reaction, the crystallization water in ferric chloride hexahydrate and ferric chloride trihydrate will form a small amount of free water (for ease of reference, it can be called produced water). Therefore, the reaction process can also be called hydrothermal reaction.

Specifically, referring to the above-mentioned analysis on regulators under hydrothermal conditions, based on the principle of hydrolysis of metal ions to produce acid, the hydrogen chloride (HCl) generated by the hydrolysis of ferric chloride will be dissolved in the generated water, thereby forming a high concentration of hydrogen ions (HCl) ⁺ ), the solution can react with ZnFe ₂ O ₄ , and at the same time, the formed Fe ³⁺ will also be hydrolyzed in the sealed system, as shown in the following equation.

_2FeCl3 + _3H2O = _{Fe2O3 +} 6HCl

ZnFe ₂ O ₄ + 8H ⁺ = Zn ²⁺ + 2Fe ³⁺ + 4H ₂ O

2Fe ³⁺ + 3H ₂ O = Fe ₂ O ₃ + 6H ⁺

Regarding the hydrothermal reaction, in one embodiment of the present application, a small amount of water can also be added to the reaction precursor to carry out the hydrothermal reaction.

S200: washing the reactant with water, separating the precipitate, and obtaining an iron-enriched precipitate.

After the steel dust and regulator undergo hydrothermal reaction, the reactants are in a certain wet state. Under hydrothermal conditions, the regulator is hydrolyzed to promote the mineral phase change of iron and steel dust, to realize the effective extraction of metal ions, and through the regulator to regulate the nucleation and growth behavior of metal ions, most of the iron is converted into Fe ₂ O ₃ , Other metal ions are still in ionic state. When water is added to the reactant, Fe ₂ O ₃ forms a precipitate, and other metal ions remain in the ionic state and remain in the solution.

When the precipitate is separated (eg centrifuged), it is an iron-rich precipitate. The separated liquid phase can be called zinc-containing separation liquid. This process can realize the effective separation of iron and zinc elements in iron and steel dust, and solve the technical problems that the resource utilization of iron and steel dust is difficult and heavy metals are difficult to efficiently separate and reuse. The iron-enriched precipitate can be washed and separated by adding water several times. The metal ions in the reaction solution adsorbed on the surface of the iron-rich precipitate are washed away. It can also be dried after cleaning.

Compared with the prior art, the present invention has the following advantages:

The invention can realize effective separation of iron and zinc elements from iron and steel dust, secondary utilization of hazardous waste, and improvement of utilization rate of resources. In the present invention, metal ions in iron and steel dust are effectively removed by adopting mineral phase hydrothermal method, and at the same time, effective nucleation and growth of hematite are successfully realized by the introduction of regulators. Compared with acid leaching treatment, the use of acid is reduced, and the problem of subsequent acid treatment is avoided; the effective separation of metal elements is realized by one-step mineral phase hydrothermal method, the process flow is shortened, and the effectiveness of separation and production are further ensured. In the absence of secondary sintering, under the joint action of hydrothermal conditions and regulators, the iron-containing precipitates grow in crystal form, and iron-containing precipitates with well-arranged crystal lattices are obtained, that is, iron-rich precipitates. The iron-enriched sediment is a sediment with high iron content, specifically hematite, which can be used for secondary use.

In some embodiments, the reaction temperature of the hydrothermal reaction is 150°C-200°C. Preferably 180-200°C. If the temperature is too low, it will be difficult to decompose the zinc ferrite in the steel dust.

In some embodiments, the duration of the hydrothermal reaction is 2-20 hours. Preferably 4-10h. If the time is too short, the zinc ferrite will not be completely decomposed and cannot be completely converted into hematite.

In some embodiments, the mass ratio of the regulating agent to the steel dust is (1~2):1. Insufficient dosage of regulator will lead to incomplete decomposition of zinc ferrite.

In the previous analysis process, it has been mentioned that zinc and other metal ions are mainly in solution, and this part of metal ions can also be used for secondary use. Therefore, in some embodiments, it also includes: in the step of washing the reactant with water and separating the precipitate, collecting the separated liquid phase to obtain a zinc-containing separation liquid.

The zinc-containing separation liquid contains other metal separation liquids, and metal ions can be recovered through treatment, thereby realizing the secondary utilization of resources.

The present invention also provides an application of the above iron separation and enrichment method in steel dust and sludge recycling.

In order to facilitate the further understanding of the above implementation, an example is given to illustrate:

Example 1

1. Fully mix electric furnace dust sludge (Fe52.4%, Zn7.96%) and ferric chloride hexahydrate at a ratio of 2:3 for 30 minutes to obtain a reaction precursor.

2. Put the reaction precursor in the reactor for hydrothermal reaction, the reaction temperature is 200 °C, and the reaction time is 10 h. After the reaction is finished, the iron-enriched precipitate and the zinc-containing separation liquid are obtained by washing several times. The XRD spectrum of the electric furnace dust sludge before the reaction and the iron-enriched precipitate after the reaction is shown in Figure 2. It can be seen that the electric furnace dust sludge is converted into hematite after the hydrothermal reaction, and the diffraction of zinc ferrite spinel The peak disappears. The scanning electron microscope images of the electric furnace dust sludge before the reaction and the iron-enriched precipitate after the reaction are shown in Figure 3. It can be seen that the product after the hydrothermal reaction is spherical hematite, and the particle distribution is more uniform.

3. Digest the electric furnace dust sludge before the reaction and the iron-enriched sediment after the reaction, and use ICP-OES to quantitatively test the iron and zinc elements in the sample. Changes in element content are shown in Figure 4. It can be seen that the electric furnace dust sludge before the reaction contains 52.4% iron and 7.96% zinc; the iron-enriched precipitate after the reaction contains 66.63% iron and 0.11% zinc. After hydrothermal treatment, the Fe content in the solid phase is close to the theoretical iron content value of hematite, and the separation rate of zinc reaches 98%.

Example 2

1. Fully mix the electric furnace dust and ferric chloride hexahydrate at a ratio of 1:2 for 10 minutes to obtain a reaction precursor.

2. Put the reaction precursor in the reactor for hydrothermal reaction, the reaction temperature is 200 °C, and the reaction time is 8 h. After the reaction is finished, the iron-enriched precipitate and the zinc-containing separation liquid are obtained by washing several times.

3. In this embodiment, the electric furnace dust sludge before the reaction contains 52.4% iron and 7.96% zinc; the iron-enriched precipitate after the reaction contains 66.75% iron and 0.06% zinc.

Example 3

1. Fully mix converter dust (Fe49.7%, Zn10.15%) and ferric chloride hexahydrate at a ratio of 2:3 for 30 minutes to obtain a reaction precursor.

2. Put the reaction precursor in the reactor for hydrothermal reaction, the reaction temperature is 180 °C, and the reaction time is 10 h. After the reaction is finished, the iron-enriched precipitate and the zinc-containing separation liquid are obtained by washing several times.

3. In this example, the converter dust before the reaction contains 49.7% iron and 10.15% zinc; the iron-enriched precipitate after the reaction contains 65.33% iron and 1.18% zinc.

Example 4

1. Fully mix the electric furnace dust and ferric chloride trihydrate in a ratio of 1:1 for 20 min to obtain a reaction precursor.

2. Put the reaction precursor in the reactor for hydrothermal reaction, the reaction temperature is 180 °C, and the reaction time is 4 h. After the reaction is finished, the iron-enriched precipitate and the zinc-containing separation liquid are obtained by washing several times.

3. In this embodiment, the electric furnace dust sludge before the reaction contains 52.4% iron and 7.96% zinc; the iron-enriched precipitate after the reaction contains 65.77% iron and 0.13% zinc.

Example 5

1. Fully mix the converter dust sludge of Example 3 with ferric chloride hexahydrate at a ratio of 2:3 for 20 min to obtain a reaction precursor.

2. Put the reaction precursor in the reactor for hydrothermal reaction, the reaction temperature is 200 °C, and the reaction time is 2 h. After the reaction is finished, the iron-enriched precipitate and the zinc-containing separation liquid are obtained by washing several times.

3. In this example, the converter dust before the reaction contains 49.7% iron and 10.15% zinc; the iron-enriched precipitate after the reaction contains 62.43% iron and 2.01% zinc.

Example 5

1. Fully mix the converter dust sludge of Example 3 with ferric chloride hexahydrate at a ratio of 2:3 for 20 min to obtain a reaction precursor.

2. Put the reaction precursor in the reactor for hydrothermal reaction, the reaction temperature is 150 °C, and the reaction time is 20 h. After the reaction is finished, the iron-enriched precipitate and the zinc-containing separation liquid are obtained by washing several times.

3. In this example, the converter dust before the reaction contains 49.7% iron and 10.15% zinc; the iron-enriched precipitate after the reaction contains 64.25% iron and 1.84% zinc.

Comparative example 1

1. Put 2 g of the converter dust sludge (Fe49.7 %, Zn10.15 %) of Example 3 in a reactor for hydrothermal reaction at a reaction temperature of 200 °C and a reaction time of 10 h. After the reaction is completed, solid-liquid separation is performed to obtain an iron-rich precipitate and a zinc-containing separation liquid.

2. The XRD spectra of the converter dust sludge before the reaction and the iron-enriched precipitate after the reaction are shown in Figure 5, and the phase of the substance remains unchanged before and after hydrothermal treatment.

Compared with Example 3, it can be seen that the iron-zinc separation of mineral phase transformation cannot be realized without adding a regulator.

Comparative example 2

1. Fully mix 2g of the electric furnace dust sludge (Fe52.4%, Zn7.96%) of Example 1 with ferric chloride hexahydrate at a ratio of 2:3 for 30 minutes to obtain a reaction precursor.

2. Put the reaction precursor in the reactor for hydrothermal reaction, the reaction temperature is 100 °C, and the reaction time is 10 h. After the reaction is finished, the iron-enriched precipitate and the zinc-containing separation liquid are obtained by washing several times. The XRD spectrum of the iron-enriched precipitate after the reaction is shown in Figure 6, and the phase changes little after hydrothermal treatment.

Compared with Example 1, it can be seen that zinc ferrite does not decompose under the condition of 100 °C, and the iron-zinc separation of mineral phase transformation cannot be realized.

Among the above-mentioned technical solutions of the present invention, the above are only preferred embodiments of the present invention, and therefore do not limit the patent scope of the present invention. Under the technical conception of the present invention, the equivalent structural transformations made by utilizing the description of the present invention and the contents of the accompanying drawings , or directly/indirectly used in other related technical fields are included in the patent protection scope of the present invention.

Claims (10)

1. A regulating agent for separating and enriching iron in iron and steel dust mud is characterized in that the regulating agent comprises one or more of ferric chloride hexahydrate and ferric chloride trihydrate.

2. A method for separating and enriching iron in iron and steel dust mud is characterized by comprising the following steps:

mixing the iron and steel dust mud with a regulating agent, and carrying out hydrothermal reaction in a closed container, wherein the regulating agent comprises one or more of ferric chloride hexahydrate and ferric chloride trihydrate;

and adding water to the reactant for washing, and separating the precipitate to obtain the iron-enriched precipitate.

3. The method for separating and enriching iron according to claim 2, wherein the step of washing the reactant with water and separating the precipitate to obtain the iron-enriched precipitate comprises:

and adding water to the reaction product for washing, and centrifugally separating the precipitate to obtain the iron-enriched precipitate.

4. The method for separating and enriching iron of claim 2, wherein the reaction temperature of the hydrothermal reaction is 150 ℃ to 200 ℃.

5. The method for iron separation and enrichment according to claim 4, wherein the reaction temperature of the hydrothermal reaction is 180 to 200 ℃.

6. The method for iron separation and enrichment according to claim 4, wherein the hydrothermal reaction is carried out for a period of 2 to 20 hours.

7. The method for iron separation and enrichment according to claim 6, wherein the hydrothermal reaction is carried out for a period of 4 to 10 hours.

8. The method for iron separation and enrichment according to claim 2, wherein the mass ratio of the control agent to the steel dust mud is (1 to 2): 1.

9. The method for separating and enriching iron according to any one of claims 2 to 8, wherein in the step of adding water to wash the reactant and separating the precipitate, the separated liquid phase is collected to obtain a zinc-containing separation solution.

10. Use of the method of any one of claims 2 to 9 for iron separation and enrichment in iron and steel sludge recovery.

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