Method for adjusting process for extracting zinc and reducing iron from rotary kiln

Abstract

The invention provides a method for adjusting a process for extracting zinc-reduced iron from a rotary kiln, which mainly adjusts parameters of the process for extracting zinc-reduced iron from the rotary kiln according to the zinc content of a mixture, so that when the mass content of zinc in the mixture is less than 1%, the metallization ratio of iron-containing kiln slag is not less than 80%, and the metallization ratio of iron-containing kiln slag is not less than 80%. When the mass fraction of zinc in the mixture is greater than or equal to 1%, the mass content of zinc oxide in the secondary zinc oxide is not less than 20%, so that when the mass content of zinc in the mixture in the process of extracting zinc and reducing iron by the rotary kiln is relatively high, the fly ash obtained by mainly extracting zinc can be directly returned to be sintered and utilized; and when the mass content of zinc in the mixture is low, the iron-containing kiln slag mainly obtained by iron extraction can be directly returned to ironmaking for utilization, so that the technical problem of production loss caused by low economic value of a rotary kiln production line is avoided, and the economic benefit of the rotary kiln production line is finally improved.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy and chemical industry, and in particular to a method for regulating a rotary kiln for zinc extraction and iron reduction. Background Art

[0002] During the long production process of steel enterprises, a large amount of iron-containing zinc dust is generated, which contains valuable elements such as iron and carbon, as well as zinc and other elements that are harmful to the smelting process. For a long time, the iron-containing zinc dust has been directly sintered and reused. Due to the high content of metal zinc, it causes damage to the blast furnace lining, nodules in the furnace, corrosion of the gas pipeline, etc., which seriously affects the smooth production and service life of the blast furnace. At present, the domestic iron-containing zinc dust mainly adopts the rotary hearth furnace and rotary kiln process. Among them, the rotary kiln process has become the first choice of private steel enterprises due to its advantages such as short process flow, low equipment failure rate and low investment.

[0003] With the commissioning of rotary kilns, the zinc content of dust ash produced by steel enterprises will drop to less than 1% in 2 to 3 years. At this time, the dust ash produced can be directly returned to sintering for use. If production continues, it will cause losses due to the low zinc content of dust ash. Therefore, the rotary kiln has to stop production, resulting in a waste of social resources. Summary of the invention

[0004] The object of the present invention is to provide a method for regulating a rotary kiln zinc reduction iron process, so as to improve the technical problem in the prior art that after the rotary kiln is put into operation, dust removal may cause low zinc content and lead to production line shutdown.

[0005] In order to solve the above technical problems, the present invention provides a method for adjusting the process of zinc extraction and iron reduction in a rotary kiln, comprising: S10, mixing iron-containing zinc-containing dust mud, a reducing agent and water to obtain a mixture; S20, adding the mixed material into a rotary kiln for calcination treatment, obtaining iron-containing kiln slag after water quenching, and collecting it through a rotary kiln cooler or a dust collector to obtain secondary zinc oxide; Among them, in step S20: when the mass content of zinc in the mixture is less than 1%, the metallization rate of the iron-containing kiln slag is not less than 80%; when the mass fraction of zinc in the mixture is greater than or equal to 1%, the mass content of zinc oxide in the secondary zinc oxide is not less than 20%.

[0006] Preferably, in step S10: the mass ratio of the reducing agent to the iron-containing and zinc-containing dust is (0.1-0.3):1; the reducing agent includes at least one of coal powder and coke powder.

[0007] Preferably, in step S10: the moisture content of the mixture is 10% to 12%.

[0008] Preferably, before performing step S20, the process further includes: pelletizing the mixed material to obtain green pellets.

[0009] Preferably, the particle size of the green balls is 8 mm to 16 mm, the number of times the green balls can withstand the impact of a 500 mm drop test without breaking is greater than or equal to 5 times, and the compressive strength of the green balls is ≥12N.

[0010] Preferably, in step S20: when the zinc content of the mixture is less than 1%, the C / O ratio of the mixture is 1.4-1.6, the temperature of the rotary kiln is 1150°C-1350°C, and the reaction residence time of the mixture in the rotary kiln is 8-10h.

[0011] Preferably, the metallization rate of the iron-containing kiln slag is 80% to 95%, and the mass content of zinc oxide in the secondary zinc oxide is 5% to 15%.

[0012] Preferably, in step S20: when the zinc content of the mixture is greater than or equal to 1%, the C / O ratio of the mixture is 1.2-1.4, the temperature of the rotary kiln is 950°C-1150°C, and the reaction residence time of the mixture in the rotary kiln is 3-4h.

[0013] Preferably, the metallization rate of the iron-containing kiln slag is 40% to 60%, and the mass content of zinc oxide in the secondary zinc oxide is 20% to 65%.

[0014] Preferably, in step S20: the temperature of the rotary kiln is adjusted by the amount of gas in the kiln head burner, and the reaction residence time of the mixture in the rotary kiln is controlled by adjusting the rotation speed of the rotary kiln.

[0015] The beneficial effect of the present invention is as follows: Different from the prior art, the present invention provides a method for adjusting the rotary kiln zinc extraction and iron reduction process, which mainly adjusts the parameters of the rotary kiln zinc extraction and iron reduction process according to the zinc content in the mixture, so that when the mass content of zinc in the mixture is less than 1%, the metallization rate of the iron-containing slag is not less than 80%, and when the mass fraction of zinc in the mixture is greater than or equal to 1%, the mass content of zinc oxide in the secondary zinc oxide is not less than 20%, so that when the mass content of zinc in the mixture is relatively high, the dust removal ash obtained by mainly extracting zinc in the rotary kiln zinc extraction and iron reduction process can be directly returned to sintering for utilization, and when the mass content of zinc in the mixture is relatively low, the iron-containing slag obtained by mainly extracting iron can be directly returned to ironmaking for utilization, thereby avoiding the technical problem of production losses caused by low economic value of the rotary kiln production line, and ultimately improving the economic benefits of the rotary kiln production line. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A flow chart of a method for regulating a rotary kiln for zinc extraction and iron reduction process provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0017] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] The purpose of the present invention is to overcome the above technical deficiencies, provide a method for adjusting the rotary kiln zinc reduction iron process, and solve the technical problem of the prior art that after the rotary kiln is put into operation, dust removal will cause low zinc content and lead to production line shutdown.

[0019] See also Figure 1 , Figure 1 A flow chart of a method for adjusting a rotary kiln for zinc extraction and iron reduction process provided in an embodiment of the present invention; wherein the method for adjusting a rotary kiln for zinc extraction and iron reduction process specifically comprises: S10, mixing iron-containing zinc-containing dust mud, a reducing agent and water to obtain a mixture.

[0020] Specifically, step S10 also includes: Firstly, iron-containing and zinc-containing dust mud, a reducing agent and water are weighed according to the proportions and the powders are mixed evenly to obtain a mixture.

[0021] Preferably, in step S10: the mass ratio of the reducing agent to the iron-containing zinc-containing dust sludge is (0.1-0.3):1; wherein, in the treatment process of the iron-containing zinc-containing dust sludge, a certain proportion of the reducing agent can effectively promote the reduction of metal oxides.

[0022] Preferably, the iron- and zinc-containing dust sludge includes at least one of ironmaking dust removal ash, gas ash and sewage sedimentation sludge; and the reducing agent includes at least one of coal powder and coke powder.

[0023] Preferably, in step S10: the moisture content of the mixture is 10% to 12%; within this moisture content range, the viscosity and plasticity of the material are more suitable, which is conducive to forming pellets with stable structure and good strength. If the moisture content is too low, the material is difficult to bond and form; if it is too high, the pellets may be too wet and easy to break or deform during subsequent processing.

[0024] Secondly, the mixture is pelletized to obtain green balls; the green balls have regular shapes and appropriate particle sizes, which can provide better gas flow channels and improve ventilation and heat transfer conditions in the kiln during the subsequent rotary kiln processing, thereby improving reaction efficiency. At the same time, the balled materials can be heated and reacted more evenly in the kiln, reducing processing time and improving production efficiency.

[0025] Specifically, the particle size of the green ball is 8mm to 16mm, the number of times the green ball can withstand the impact of a 500mm drop test without breaking is greater than or equal to 5 times, and the compressive strength of the green ball is ≥12N.

[0026] Furthermore, the particle size range of 8mm to 16mm can be evenly heated and reacted in the rotary kiln, avoiding excessive reaction due to too small particle size or insufficient reaction due to too large particle size; the number of times the green balls can withstand the impact of a 500mm drop test without breaking is greater than or equal to 5 times, and the compressive strength is ≥12N, mainly to ensure that the green balls have sufficient strength and stability.

[0027] S20, adding the mixed material into a rotary kiln for calcination treatment, obtaining iron-containing kiln slag after water quenching, and collecting it through a rotary kiln cooler or a dust collector to obtain secondary zinc oxide.

[0028] Specifically, step S20 also includes: First, the green balls are put into the kiln from the kiln tail for calcination, and the temperature in the kiln and the material residence time are controlled by the kiln head burner and the rotary kiln speed to obtain high-temperature kiln slag and zinc vapor.

[0029] Secondly, after roasting, the high-temperature slag is quenched with water to obtain iron-containing slag, and the zinc vapor enters the flue gas treatment system of the rotary kiln, is oxidized and cooled by air, and is collected through the rotary kiln's surface cooler or dust collector to obtain secondary zinc oxide.

[0030] Specifically, when the mass content of zinc in the mixture is less than 1%, the metallization rate of the iron-containing kiln slag is not less than 80%; when the mass fraction of zinc in the mixture is greater than or equal to 1%, the mass content of zinc oxide in the secondary zinc oxide is not less than 20%.

[0031] In the first embodiment, when the zinc content of the mixture is less than 1%, the C / O ratio of the mixture is adjusted to 1.4-1.6 by adjusting the carbon content, the temperature of the rotary kiln is adjusted to 1150°C-1350°C by adjusting the gas volume of the kiln head burner, and the reaction residence time of the mixture in the rotary kiln is adjusted to 8-10 hours by adjusting the rotation speed of the rotary kiln; at this time, the rotary kiln production is mainly based on iron extraction, the metallization rate of the iron-containing kiln slag is 80%-95%, and the mass content of zinc oxide in the secondary zinc oxide is 5%-15%.

[0032] Specifically, a higher carbon-oxygen ratio helps to provide a more sufficient reducing environment, promote the reduction of iron oxides, and increase the metallization rate of iron; a high temperature of 1150°C~1350°C is conducive to the full reduction reaction of iron oxides, so that iron can be better reduced to a metallic state; a longer residence time can make the reduction reaction more thorough, thereby achieving a higher metallization rate of iron-containing slag.

[0033] In the second embodiment, when the zinc content of the mixture is greater than or equal to 1%, the C / O ratio of the mixture is adjusted to 1.2-1.4 by adjusting the carbon content, the temperature of the rotary kiln is adjusted to 950°C-1150°C by adjusting the gas volume of the kiln head burner, and the reaction residence time of the mixture in the rotary kiln is adjusted to 3-4h by adjusting the rotation speed of the rotary kiln; at this time, the rotary kiln production is mainly based on zinc extraction, the metallization rate of the iron-containing kiln slag is 40%-60%, and the mass content of zinc oxide in the secondary zinc oxide is 20%-65%.

[0034] Specifically, a relatively low carbon-oxygen ratio may be more conducive to the volatilization and recovery of zinc; a temperature of 950°C to 1150°C may help control the volatilization rate and reaction process of zinc and improve the quality of secondary zinc oxide; a shorter residence time may be because at a higher zinc content, better zinc recovery effects can be achieved in a shorter time while avoiding excessive reaction leading to other problems.

[0035] The technical solution of the present application is now further described in detail in conjunction with specific embodiments.

[0036] Embodiment 1: The specific steps of the method for adjusting the rotary kiln zinc reduction process provided in Example 1 of the present invention are as follows: Step 1: weigh and mix the iron-containing and zinc-containing dust mud, coke powder and water in a proportion, wherein the zinc content of the mixture is less than 1%, the water content of the mixture is 10% to 12%, and the carbon content is adjusted so that the C / O ratio is 1.4 to 1.6; Step 2: Balling the mixture to a particle size of 8 to 16 mm, wherein the green ball strength drop (500 mm) strength is ≥ 5 times / ball, and the compressive strength is ≥ 12N / ball; Step three, the green balls are put into the kiln from the kiln tail for calcination, and the kiln temperature is controlled at 1150℃~1350℃ and the material reaction stay time is 8~10h through the kiln head burner and the rotary kiln speed.

[0037] The production of the method for adjusting the rotary kiln zinc extraction and iron reduction process provided in Example 1 of the present invention is mainly based on iron extraction, the metallization rate of the iron-containing kiln slag is 80% to 95%, and the mass content of zinc oxide in the secondary zinc oxide is 5% to 15%.

[0038] Embodiment 2: The specific steps of the method for adjusting the rotary kiln zinc reduction iron process provided in Example 2 of the present invention are as follows: Step 1: weigh and mix the iron-containing and zinc-containing dust mud, coke powder and water according to the ratio, wherein the zinc content of the mixture is greater than or equal to 1%, the water content of the mixture is 10% to 12%, and the carbon content is adjusted so that the C / O ratio is 1.2 to 1.4; Step 2: Balling the mixture to a particle size of 8 to 16 mm, wherein the green ball strength drop (500 mm) strength is ≥ 5 times / ball, and the compressive strength is ≥ 12N / ball; Step three, the green balls are put into the kiln from the kiln tail for calcination, and the kiln temperature is controlled at 950℃~1150℃ and the material reaction stay time is 3~4h through the kiln head burner and the rotary kiln speed.

[0039] The production method of regulating the rotary kiln zinc extraction and iron reduction process provided in Example 2 of the present invention is mainly based on zinc extraction, the metallization rate of the iron-containing kiln slag is 40% to 60%, and the mass content of zinc oxide in the secondary zinc oxide is 20% to 65%.

[0040] In summary, the present invention adjusts the rotary kiln production process. When the raw material contains zinc greater than or equal to 1%, the production is mainly based on zinc extraction, the kiln slag metallization rate is 40% to 60%, and the secondary zinc oxide quality is 20% to 65%. The kiln slag is recycled for ironmaking, and the secondary zinc oxide has a high grade and high economic value. When the raw material contains zinc less than 1%, the production is mainly based on iron extraction, the kiln slag metallization rate is 80% to 95%, and the secondary zinc oxide quality is 5% to 15%. The kiln slag is recycled for steelmaking, and the secondary zinc oxide has a low grade, and zinc is extracted by selling it or re-entering the rotary kiln. It should be noted that the above embodiments all belong to the same inventive concept, and the descriptions of each embodiment have different focuses. For details not described in individual embodiments, reference can be made to the descriptions in other embodiments.

[0041] The above embodiments only express the implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for adjusting a rotary kiln for zinc reduction and iron extraction, characterized in that: include: S10, mixing iron-containing zinc-containing dust mud, a reducing agent and water to obtain a mixture; S20, adding the mixed material into a rotary kiln for calcination treatment, obtaining iron-containing kiln slag after water quenching, and collecting it through a surface cooler or a dust collector of the rotary kiln to obtain secondary zinc oxide; Wherein, in the step S20: when the mass content of zinc in the mixture is less than 1%, the metallization rate of the iron-containing kiln slag is not less than 80%; when the mass fraction of zinc in the mixture is greater than or equal to 1%, the mass content of zinc oxide in the secondary zinc oxide is not less than 20%.

2. The method for adjusting the rotary kiln zinc reduction iron process according to claim 1, characterized in that: In the step S10: the mass ratio of the reducing agent to the iron-containing and zinc-containing dust is (0.1-0.3):1; the reducing agent includes at least one of coal powder and coke powder.

3. The method for adjusting the rotary kiln zinc reduction iron process according to claim 1, characterized in that: In the step S10, the moisture content of the mixture is 10% to 12%.

4. The method for adjusting the rotary kiln zinc reduction iron process according to claim 1, characterized in that: Before performing the step S20, the method further includes: pelletizing the mixed material to obtain green balls.

5. The method for adjusting the rotary kiln zinc reduction iron process according to claim 4, characterized in that: The particle size of the green ball is 8mm-16mm, the number of times the green ball can withstand the impact of a 500mm drop test without breaking is greater than or equal to 5 times, and the compressive strength of the green ball is ≥12N.

6. The method for adjusting the rotary kiln zinc reduction iron process according to claim 1, characterized in that: In the step S20: when the zinc content of the mixture is less than 1%, the C / O ratio of the mixture is 1.4-1.6, the temperature of the rotary kiln is 1150° C.-1350° C., and the reaction residence time of the mixture in the rotary kiln is 8-10 hours.

7. The method for adjusting the rotary kiln zinc reduction iron process according to claim 6, characterized in that: The metallization rate of the iron-containing kiln slag is 80% to 95%, and the mass content of zinc oxide in the secondary zinc oxide is 5% to 15%.

8. The method for adjusting the rotary kiln zinc reduction iron process according to claim 1, characterized in that: In the step S20: when the zinc content of the mixture is greater than or equal to 1%, the C / O ratio of the mixture is 1.2-1.4, the temperature of the rotary kiln is 950° C.-1150° C., and the reaction residence time of the mixture in the rotary kiln is 3-4 hours.

9. The method for adjusting the rotary kiln zinc reduction process according to claim 8, characterized in that: The metallization rate of the iron-containing kiln slag is 40% to 60%, and the mass content of zinc oxide in the secondary zinc oxide is 20% to 65%.

10. The method for adjusting the rotary kiln zinc reduction iron process according to claim 6 or 8, characterized in that: In the step S20: the temperature of the rotary kiln is adjusted by the amount of gas in the kiln head burner, and the reaction residence time of the mixed material in the rotary kiln is controlled by adjusting the rotation speed of the rotary kiln.

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