A method for enriching zinc in zinc-containing blast furnace dust and obtaining zinc concentrate

Abstract

The application discloses a method for enriching zinc in zinc-containing blast furnace dust and obtaining zinc concentrate, and comprises the following steps: crushing and drying zinc-containing blast furnace dust, screening the dust, and then obtaining crushed materials by airflow crushing and dispersing to restore the particle size distribution; the crushed materials are subjected to particle size classification treatment through N-stage airflow classification equipment in series, zinc-rich materials generated by each stage of airflow classification equipment are collected as zinc-rich raw materials, and zinc-lean materials generated by each stage of airflow classification equipment are used as the feed of the next stage of airflow classification equipment for further classification; the zinc-rich raw materials are added with water for slurry preparation, and then added with a flotation agent for flotation, so as to obtain carbon-rich zinc-lean material slurry and zinc concentrate slurry; and the zinc concentrate slurry is filtered to obtain artificial zinc concentrate. The method is convenient to operate, has good zinc enrichment effect, is green and environment-friendly, is easy to realize industrialization, can turn waste into treasure, and can obtain artificial zinc concentrate with high economic value.

Description

Technical Field

[0001] This invention relates to the field of secondary resource comprehensive recovery of blast furnace dust, specifically to a method for enriching zinc in zinc-containing blast furnace dust and obtaining zinc concentrate. Background Technology

[0002] Blast furnace dust is a byproduct of blast furnace ironmaking. It consists of coarse particles carried out with blast furnace gas and obtained through gravity dust removal, followed by fine particles obtained through bag filter dust removal. Blast furnace dust mainly contains iron, carbon, and zinc. Current disposal methods include stockpiling or landfilling, incorporation into sintering processes, use as an ingredient in cement and other building materials, and comprehensive recycling. Comprehensive recycling methods primarily involve mineral processing, pyrometallurgical processes, hydrometallurgical processes, or a combination of two or three of these methods, mainly involving the recovery of iron, carbon, and zinc.

[0003] Chinese patent CN110743714B discloses a method for enriching and recovering zinc from blast furnace gas mud. The method uses flotation to remove zinc. The original gas mud has a zinc grade of 10.50%. After flotation, the zinc grade of the zinc-rich material is 21.58%. The zinc content of this zinc-rich material is not high and cannot meet the standard for zinc concentrate. Summary of the Invention

[0004] The purpose of this invention is to provide a method for enriching zinc in zinc-containing blast furnace dust and obtaining zinc concentrate. This method is easy to operate, has a good zinc enrichment effect, is green and environmentally friendly, and is easy to industrialize. It can turn waste into treasure and obtain artificial zinc concentrate with high economic value.

[0005] To achieve the above-mentioned objectives, the present invention provides a method for enriching zinc in zinc-containing blast furnace dust and obtaining zinc concentrate, comprising the following steps:

[0006] Step (1): After crushing and drying the zinc-containing blast furnace dust, pass it through a screen. The material passing through the screen is then crushed and dispersed by airflow pulverization to obtain pulverized material.

[0007] Step (2): The pulverized material is subjected to particle size classification by passing it through N-stage air classifiers connected in series. The coarse particles produced by each stage of air classifier are zinc-poor material, and the fine particles produced by each stage of air classifier are zinc-rich material. The zinc-rich material produced by each stage of air classifier is collected as zinc-rich raw material, and the zinc-poor material produced by each stage of air classifier is used as feed for the next stage of air classifier for further classification; wherein, 1≤N≤20.

[0008] Step (3): Add the zinc-rich raw material to water and adjust the slurry, then add flotation agent for flotation to obtain carbon-rich and zinc-poor slurry and zinc concentrate slurry. Filter the zinc concentrate slurry to obtain artificial zinc concentrate.

[0009] In this invention, in step (2), the zinc-poor material obtained by the Nth-level grading equipment can be recycled as raw material for iron and carbon.

[0010] In this invention, the solid obtained after filtering the carbon-rich and zinc-poor slurry in step (3) can be recycled as a carbon raw material.

[0011] Generally, zinc-containing blast furnace dust refers to blast furnace gravity ash, blast furnace gas ash, blast furnace bag filter ash, TRT ash, or blast furnace gas sludge carried out with blast furnace gas during the blast furnace ironmaking process. Typically, the zinc content of blast furnace gravity ash or blast furnace gas ash is around 0.1% to 1.5%, while the zinc content of blast furnace bag filter ash, TRT ash, or blast furnace gas sludge is between 0.1% and 25%. The zinc content of the aforementioned raw materials that can be processed using the method of this application to obtain synthetic zinc concentrate must be ≥0.5%. Due to environmental protection requirements, except for blast furnace dust transported by tanker trucks which does not require water spraying for dust removal... For blast furnace dust transported by other methods, water is generally sprayed during the ash discharge process to prevent dust generation. Since the temperature of the blast furnace dust is typically around 200℃ and it contains soluble salts, the dust tends to clump after water spraying. Clumping alters the overall particle size distribution. Therefore, zinc-containing blast furnace dust exhibiting clumping is treated by crushing, drying, sieving, and air-jetting of the undersize material. This process restores the original particle size distribution while minimizing or preserving its original size distribution before water spraying, facilitating subsequent grading. The oversize material is returned to the previous crushing stage.

[0012] According to the present invention, a method for enriching zinc in zinc-containing blast furnace dust and obtaining zinc concentrate is preferably described in step (1), where the aperture of the sieve is 2 mm.

[0013] According to the method for enriching zinc in zinc-containing blast furnace dust and obtaining zinc concentrate according to the present invention, preferably, in step (1), when the air classifier is an air classifier, the frequency of the air classifier host is 30-80Hz, the frequency of the fan is 40-60Hz, and the air volume is 25-45m³ / h. 3 / min.

[0014] According to the present invention, a method for enriching zinc in zinc-containing blast furnace dust and obtaining zinc concentrate is preferably described in step (2), wherein the air classifier is a hydrocyclone or an air classifier.

[0015] According to the method for enriching zinc in zinc-containing blast furnace dust and obtaining zinc concentrate according to the present invention, preferably, in step (2), the particle size of each airflow classification stage is 13 μm.

[0016] In this invention, particles no larger than 13 μm are zinc-rich materials, and particles larger than 13 μm are zinc-poor materials. The classification level N increases with the zinc content of the zinc-containing blast furnace dust. When the zinc content of a certain grade of zinc-poor material is less than 0.5 wt%, the airflow classification can be stopped, that is, the zinc content of grade N zinc-poor material is less than 0.5 wt%.

[0017] According to the present invention, a method for enriching zinc in zinc-containing blast furnace dust and obtaining zinc concentrate is preferably described in step (2), when the air classifier is a hydrocyclone, the diameter of the hydrocyclone barrel is 25-150mm, the feed pressure is 0.04-0.1MPa, and the diameter of the hydrocyclone underflow outlet is not less than 6mm.

[0018] As a specific embodiment of the present invention, the diameter of the hydrocyclone barrel is 50-100mm; more preferably, the diameter of the hydrocyclone underflow outlet is 6-24mm.

[0019] According to the method for enriching zinc in zinc-containing blast furnace dust and obtaining zinc concentrate according to the present invention, preferably, in step (2), when the air classifier is an air classifier, the frequency of the air classifier host is 30-80Hz, the frequency of the fan is 40-60Hz, and the air volume is 25-45m³ / h. 3 / min.

[0020] According to the present invention, a method for enriching zinc in zinc-containing blast furnace dust and obtaining zinc concentrate is preferably described in step (3), after adding water to the zinc-rich raw material to make a slurry, the solid content is controlled to be 20wt%-35wt%.

[0021] According to the present invention, a method for enriching zinc in zinc-containing blast furnace dust and obtaining zinc concentrate is preferably described in step (3), wherein the flotation agent is a mixture of kerosene or No. 260 aviation kerosene and sodium dodecylbenzene sulfonate; wherein the mass percentage of kerosene or No. 260 aviation kerosene is 90%-99%, and the mass percentage of sodium dodecylbenzene sulfonate is 1%-10%.

[0022] According to the present invention, a method for enriching zinc in zinc-containing blast furnace dust and obtaining zinc concentrate is preferably described in step (3), wherein the ratio of flotation agent to zinc-rich raw material dry material is 100-200g:1000g, and the flotation agent is added at a rate of 5-20g / min.

[0023] In this invention, when adding flotation agent, it is necessary to add material, stir and aerate at the same time to enhance the foaming effect. At the same time, the generated foam is scraped off by the flotation machine until there is basically no foam. The foam obtained is carbon-rich and zinc-poor slurry, and the remaining tailings are zinc concentrate slurry. The filtrate obtained from both is returned to the slurry preparation process for reuse. The former can be recycled as carbon raw material after filtration, and the latter can be used to obtain high-zinc grade artificial zinc concentrate after filtration.

[0024] The beneficial effects of this invention are:

[0025] The present invention discloses a method for enriching zinc in zinc-containing blast furnace dust and obtaining zinc concentrate. The zinc-containing blast furnace dust is dispersed by airflow and a multi-stage airflow graded series treatment is adopted to obtain a zinc-rich mixture. After the zinc-rich mixture is slurryed, flotation decarbonization is used to further increase the zinc content in the zinc-rich mixture, thereby obtaining high-zinc grade artificial zinc concentrate.

[0026] This method is easy to operate, has a simple process flow, low production cost, good zinc enrichment effect, is green and environmentally friendly, and is easy to industrialize, and can obtain artificial zinc concentrate with high economic value. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples.

[0028] It should be noted that all uses of "first" and "second" in the embodiments of the present invention are for the purpose of distinguishing two entities or parameters with the same name but different names. It is clear that "first" and "second" are only for the convenience of expression and should not be construed as limiting the embodiments of the present invention. Subsequent embodiments will not explain this in detail.

[0029] Example 1

[0030] Example 1 describes a method for enriching zinc in zinc-containing blast furnace dust and obtaining zinc concentrate, comprising the following steps:

[0031] Step (1): The zinc-containing blast furnace dust with a zinc content of 4wt% is coarsely crushed and dried by a crusher, then passed through a 2mm sieve. The material over the sieve is returned for coarse crushing again, and the material under the sieve is dispersed by airflow to obtain pulverized material. The airflow dispersion equipment is an airflow pulverizer with an airflow rate of 0.6m³ / h. 3 / min, air pressure is 2Mpa.

[0032] Step (2) The pulverized material is subjected to particle size classification by a series of 6-stage air classifiers. The particle size of each stage of air classifier is 13μm. The coarse particles produced by each stage of air classifier are zinc-poor material, and the fine particles produced by each stage of air classifier are zinc-rich material. The zinc-rich material produced by each stage of air classifier is collected as zinc-rich raw material. The zinc-poor material produced by each stage of air classifier is used as feed for the next stage of air classifier for further classification. The zinc content of the zinc-poor material of the 6th stage is less than 0.5wt%. The zinc-poor material obtained by the 6-stage classification equipment can be recycled as raw material for iron and carbon.

[0033] Step (3): After adding the zinc-rich raw material to water to adjust the slurry, the solid content is controlled to be 30wt%. Then, flotation agent is added for flotation to obtain carbon-rich zinc-poor slurry and zinc concentrate slurry. The zinc concentrate slurry is filtered to obtain artificial zinc concentrate. The solid obtained after filtration of the carbon-rich zinc-poor slurry can be recycled as carbon raw material. When adding the flotation agent, the material is added while stirring and aerating to enhance the foaming effect. At the same time, the foam generated is scraped off by the flotation machine until there is basically no foam. The foam obtained is carbon-rich zinc-poor slurry, and the remaining tailings are zinc concentrate slurry. The flotation agent is a compound of kerosene and sodium dodecylbenzene sulfonate. The mass ratio of kerosene is 95%, the mass ratio of sodium dodecylbenzene sulfonate is 5%, the ratio of flotation agent to dry zinc-rich raw material is 150g:1000g, and the addition rate is 10g / min.

[0034] The zinc grade of the zinc concentrate obtained in Example 1 was found to be 57.6%.

[0035] Example 2

[0036] Example 2 describes a method for enriching zinc in zinc-containing blast furnace dust and obtaining zinc concentrate, comprising the following steps:

[0037] Step (1): The zinc-containing blast furnace dust with a zinc content of 10wt% is coarsely crushed and dried by a crusher, then passed through a 2mm sieve. The material over the sieve is returned for coarse crushing again, and the material under the sieve is dispersed by airflow to obtain pulverized material. The airflow dispersion equipment is an airflow pulverizer with an airflow rate of 0.6m³ / h. 3 / min, air pressure is 2Mpa.

[0038] Step (2) The pulverized material is subjected to particle size classification by an 8-stage air classifier connected in series. The particle size of each stage of air classification is 13μm. The coarse particles produced by each stage of air classification equipment are zinc-poor material, and the fine particles produced by each stage of air classification equipment are zinc-rich material. The zinc-rich material produced by each stage of air classification equipment is collected as zinc-rich raw material. The zinc-poor material produced by each stage of air classification equipment is used as feed for the next stage of air classification equipment for further classification. The zinc content of the zinc-poor material of the 8th stage is less than 0.5wt%. The zinc-poor material obtained by the 8-stage classification equipment can be recycled as raw material for iron and carbon.

[0039] Step (3): After adding the zinc-rich raw material to water to adjust the slurry, the solid content is controlled to be 30wt%. Then, flotation agent is added for flotation to obtain carbon-rich zinc-poor slurry and zinc concentrate slurry. The zinc concentrate slurry is filtered to obtain artificial zinc concentrate. The solid obtained after filtration of the carbon-rich zinc-poor slurry can be recycled as carbon raw material. When adding the flotation agent, the material is added while stirring and aerating to enhance the foaming effect. At the same time, the foam generated is scraped off by the flotation machine until there is basically no foam. The foam obtained is carbon-rich zinc-poor slurry, and the remaining tailings are zinc concentrate slurry. The flotation agent is a compound of kerosene and sodium dodecylbenzene sulfonate. The mass ratio of kerosene is 95%, the mass ratio of sodium dodecylbenzene sulfonate is 5%, the ratio of flotation agent to dry zinc-rich raw material is 150g:1000g, and the addition rate is 10g / min.

[0040] The zinc concentrate obtained in Example 2 was found to have a grade of 66.1%.

[0041] Comparative Example 1

[0042] Comparative Example 1: Zinc-containing blast furnace dust with a zinc content of 10 wt% was processed according to the scheme of Example 1 of Chinese Patent CN110743714B, and the grade of the obtained zinc-rich material was 21.58%.

[0043] It should be noted that the components or steps in the above embodiments can be interchanged, substituted, added, or deleted. Therefore, the combinations formed by these reasonable permutations and transformations should also fall within the protection scope of this invention, and the protection scope of this invention should not be limited to the above embodiments.

[0044] The above are exemplary embodiments disclosed in this invention. The order of the disclosed embodiments is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. However, it should be noted that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the disclosed embodiments of this invention (including the claims) is limited to these examples. Various changes and modifications can be made without departing from the scope defined by the claims. The functions, steps, and / or actions of the methods according to the disclosed embodiments described herein do not need to be performed in any particular order. Furthermore, although the elements disclosed in the embodiments of this invention may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular.

[0045] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of the different aspects of the invention as described above exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for enriching zinc in zinc-containing blast furnace dust and obtaining zinc concentrate, characterized in that, The steps include the following: Step (1): After spraying water, the zinc-containing blast furnace dust that has agglomerated is crushed, dried, and sieved. The undersize material is then subjected to air jet milling to obtain pulverized material. The air jet milling equipment is used for air jet milling, with an air flow rate of 0.4-0.75 m³ / h. 3 / min, air pressure is 1.5-2.8Mpa; Step (2): The pulverized material is subjected to particle size classification by passing it through an N-stage air classifier connected in series. The coarse particles produced by each stage of the air classifier are zinc-poor material, and the fine particles produced by each stage of the air classifier are zinc-rich material. The zinc-rich material produced by each stage of the air classifier is collected as zinc-rich raw material, and the zinc-poor material produced by each stage of the air classifier is used as feed for the next stage of the air classifier for further classification. Wherein, 1≤N≤20; the particle size of each stage of air classification is 13µm. Particles not larger than 13µm are zinc-rich material, and particles larger than 13µm are zinc-poor material. When the zinc content of the N-stage zinc-poor material is less than 0.5wt%, the air classification can be stopped. The zinc-poor material obtained by the N-stage classifier is recycled as raw material for iron and carbon. Step (3): Add the zinc-rich raw material to water and adjust the slurry to control the solid content to 20wt%-35wt%. Then add flotation agent for flotation. The flotation agent is a compound of kerosene and sodium dodecylbenzene sulfonate or a compound of No. 260 aviation kerosene and sodium dodecylbenzene sulfonate. The ratio of flotation agent to dry zinc-rich raw material is 100-200g:1000g. The flotation agent is added at a rate of 5-20g / min to obtain carbon-rich and zinc-poor slurry and zinc concentrate slurry. Filter the zinc concentrate slurry to obtain artificial zinc concentrate. After filtration, the solid obtained from the carbon-rich and zinc-poor slurry is recycled as carbon raw material.

2. The method for enriching zinc in zinc-containing blast furnace dust and obtaining zinc concentrate according to claim 1, characterized in that, In step (1), the aperture of the sieve is 2mm.

3. The method for enriching zinc in zinc-containing blast furnace dust and obtaining zinc concentrate according to claim 1, characterized in that, In step (2), the airflow classification device is a cyclone separator or an airflow classifier.

4. The method for enriching zinc in zinc-containing blast furnace dust and obtaining zinc concentrate according to claim 3, characterized in that, In step (2), when the airflow classification device is a hydrocyclone, the diameter of the hydrocyclone barrel is 25-150mm, the feed pressure is 0.04-0.1MPa, and the diameter of the hydrocyclone underflow outlet is not less than 6mm.

5. The method for enriching zinc in zinc-containing blast furnace dust and obtaining zinc concentrate according to claim 3, characterized in that, In step (2), when the airflow classification device is an airflow classifier, the frequency of the airflow classification host is 30~80Hz, the frequency of the fan is 40~60Hz, and the air volume is 25~45m³ / h. 3 / min.

6. The method for enriching zinc in zinc-containing blast furnace dust and obtaining zinc concentrate according to claim 1, characterized in that, In step (3), the mass percentage of kerosene or No. 260 aviation kerosene is 90%-99%, and the mass percentage of sodium dodecylbenzenesulfonate is 1%-10%.