Method for prolonging ring forming period in dezincification rotary kiln

Abstract

The invention belongs to the technical field of dezincification rotary kilns, and particularly relates to a method for prolonging the ring forming period in a dezincification rotary kiln. The total content of total iron, SiO2 and CaO in the zinc-containing dust and mud mixture is controlled within 50% of the total mass of the zinc-containing dust and mud mixture, and the mass ratio of the total iron to the SiO2 to the CaO is (3-4.8): (1-1.5): 1; and controlling the standard deviation of total iron, the standard deviation of SiO2 and the standard deviation of CaO in the zinc-containing dust and mud mixture to be within a set threshold value. By adopting the method disclosed by the invention, a large amount of fayalite and hematite can be prevented from being generated when the zinc-containing dust and mud mixture is treated, so that ring formation in the rotary kiln is prevented, the ring formation period of the dezincification rotary kiln is further prolonged, the ring formation period of the dezincification rotary kiln for treating the zinc-containing dust and mud mixture is prolonged to 11-12 months from 3-6 months, and the yield of the dezincification rotary kiln is improved. The influence on production is reduced, the operation rate is improved, and meanwhile the production cost of the rotary kiln is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of dezincification rotary kilns, and in particular relates to a method for prolonging a ring-forming period in a dezincification rotary kiln. Background Art

[0002] The rotary kiln process has many advantages, but the ring formation problem in the rotary kiln has always been a pain point and difficulty in the rotary kiln process, especially the ring formation problem of the rotary kiln used to treat solid waste is more serious. It is very difficult to completely solve this problem. There are many reasons for the ring formation of the rotary kiln. For example, the high content of SiO2 in the raw materials will form low-melting iron silicate with FeO. At the same time, the local temperature of the rotary kiln is too high. These low-melting materials are easy to soften and adhere to the furnace wall at high temperature, forming kiln skin and even ring formation. At present, the main measures taken to prevent the ring formation of the rotary kiln are to improve the quality of raw materials, improve the temperature monitoring of the rotary kiln body, and reduce the temperature of the high-temperature section of the rotary kiln.

[0003] In terms of improving the quality of raw materials and reducing the ringing of rotary kilns, Chinese patent 202211294285.5 discloses a method for controlling the ringing of a rotary kiln of a metallurgical zinc-containing dust sludge mixture. The method mixes a metallurgical zinc-containing dust sludge mixture and a magnesium-containing material in a certain proportion, and the amount of the magnesium-containing material does not exceed 5%. The mixture is fed into a rotary kiln, and the mixture is dried, preheated, heated, and calcined in the rotary kiln. After the magnesium-containing material is decomposed at high temperature in the rotary kiln, the MgO content in the magnesium-containing material is greater than 40%. This method mainly increases the melting point of the eutectic from the original 1200°C to 1400°C by adding magnesium-containing raw materials. Therefore, the eutectic produced inside the rotary kiln is not melted and basically does not adhere to the wall of the rotary kiln, so that the ringing problem can be effectively controlled, ensuring that the rotary kiln has a longer stable operation period. Although this method is effective, the amount of magnesium-containing material added is large and the cost is high, which reduces the processing capacity of the rotary kiln for other raw materials, and the patent is not enforceable.

[0004] Chinese patent 202310812170.9 discloses a method for preparing reaction pellets for kiln-process phosphoric acid process. This method can effectively reduce the volatilization amount of SiF4 by controlling the molar ratio of CaO / SiO2 in the ingredients and accurately adjusting the proportion of the total mass of (MgO+Al2O3) in the ingredients to the total ingredient content, so that the prepared reaction pellets for the kiln-process phosphoric acid process have a higher melting point and strength, thereby effectively solving the problem of easy ring formation in traditional high-silicon ingredient rotary kilns and avoiding the problem of excessively high reduction temperature required for high-calcium ingredients. However, this method is mainly aimed at improving the kiln-process phosphoric acid process. Whether it can solve the problem of easy ring formation in rotary kilns and to what extent it can be solved remains to be studied. Summary of the invention

[0005] The purpose of the present invention is to address the defect that the existing solutions for the ring formation of rotary kilns are not very feasible, and thus a method for extending the ring formation period in a dezincifying rotary kiln is proposed. The method of the present invention reasonably regulates the contents of TFe, SiO2 and CaO in the zinc-containing dust sludge mixture, and at the same time strengthens the mixing effect of the zinc-containing dust sludge mixture by reducing the standard deviation of the main chemical components such as TFe, SiO2 and CaO in the zinc-containing dust sludge mixture, thereby extending the ring formation period of the dezincifying rotary kiln. The method is simple to operate, does not require the addition of additional auxiliary agents, and does not require real-time monitoring of the temperature of the rotary kiln body. It is highly feasible and saves a lot of manpower and material resources. In addition, the use of this method to treat the zinc-containing dust sludge mixture can reduce the impact on production and improve the operating rate, greatly reducing the production cost of the rotary kiln.

[0006] The present invention proposes a method for extending the ring formation period in a dezincifying rotary kiln, the method comprising: controlling the total content of total iron, SiO2 and CaO in a zinc-containing dust sludge mixture to be within 50% of the total mass of the zinc-containing dust sludge mixture, the mass ratio of the total iron, SiO2 and CaO being 3-4.8:1-1.5:1; and controlling the standard deviation of the total iron, the standard deviation of SiO2 and the standard deviation of CaO in the zinc-containing dust sludge mixture to be within a set threshold value.

[0007] Preferably, based on the total mass of the zinc-containing dust sludge mixture as 100 mass%, the total iron content is ≤30 mass%, the SiO2 content is ≤10 mass%, and the CaO content is ≤10 mass%. More preferably, based on the total mass of the zinc-containing dust sludge mixture as 100 mass%, the total iron content is 25-28 mass%, the SiO2 content is 8-9 mass%, and the CaO content is 6-7.5 mass%. Further preferably, based on the total mass of the zinc-containing dust sludge mixture as 100 mass%, the total iron content is 27.85 mass%, the SiO2 content is 8.87 mass%, and the CaO content is 7.16 mass%.

[0008] Preferably, the standard deviation of total iron in the zinc-containing dust sludge mixture is ≤0.30%, the standard deviation of SiO2 in the zinc-containing dust sludge mixture is ≤0.20%, and the standard deviation of CaO in the zinc-containing dust sludge mixture is ≤0.20%. More preferably, the standard deviation of total iron in the zinc-containing dust sludge mixture is 0.25-0.27%, the standard deviation of SiO2 in the zinc-containing dust sludge mixture is 0.16-0.18%, and the standard deviation of CaO in the zinc-containing dust sludge mixture is 0.17-0.19%. Further preferably, the standard deviation of total iron in the zinc-containing dust sludge mixture is 0.26%, the standard deviation of SiO2 in the zinc-containing dust sludge mixture is 0.17%, and the standard deviation of CaO in the zinc-containing dust sludge mixture is 0.18%.

[0009] Preferably, the method further comprises using high-alumina bricks with an Al2O3 content of ≥80% in the high-temperature zone of the rotary kiln. More preferably, the volume density of the high-alumina bricks is 2.80-3.00 g / cm 3 , the room temperature compressive strength is 80-100MPa. Further preferably, the Al2O3 content of the high alumina brick is 82.3%, and the volume density is 2.85g / cm 3 , the compressive strength at room temperature is 99.40MPa.

[0010] The method for extending the ring formation period in a dezincification rotary kiln described in the present invention has at least the following beneficial effects:

[0011] (1) In the present invention, since the products of rotary kiln ring formation are mainly fayalite and ferromanganese olivine produced by the combination of FeO, SiO2 and CaO, the generation of rotary kiln ring formation products can be reduced by reasonably controlling the contents of total iron, SiO2 and CaO in the zinc-containing dust sludge mixture within a certain range, thereby extending the rotary kiln ring formation period; at the same time, the standard deviations of total iron, SiO2 and CaO in the zinc-containing dust sludge mixture are accurately controlled respectively, and by limiting the standard deviations of the three within the deviation of the optimal mixing effect of the zinc-containing dust sludge mixture, it is possible to prevent the generation of a large amount of fayalite and ferromanganese olivine when processing the zinc-containing dust sludge mixture, thereby preventing the generation of ring formation in the rotary kiln;

[0012] (2) Under the preferred conditions, the TFe (total iron) content in the zinc-containing dust sludge mixture is controlled to be ≤30%, the SiO2 content is ≤10%, and the CaO content is ≤10%, and the standard deviation of TFe in the zinc-containing dust sludge mixture is ≤0.30%, the standard deviation of SiO2 is ≤0.20%, and the standard deviation of CaO is ≤0.20%. At the same time, the use of new wear-resistant high-alumina bricks with an Al2O3 content of ≥80% in the high-temperature zone of the rotary kiln can reduce the amount of iron olivine and calcium iron olivine generated, and enhance the ability to resist the erosion of iron olivine and calcium iron olivine, thereby extending the ring formation period of the dezincification rotary kiln;

[0013] (3) In a more preferred case, the content of TFe in the zinc dust sludge mixture is controlled to be 27.85%, the content of SiO2 is 8.87%, and the content of CaO is 7.16%. The standard deviation of TFe, SiO2 and CaO in the zinc dust sludge mixture is reduced to 0.26%, 0.17% and 0.18%, respectively. The Al2O3 content in the high temperature zone of the rotary kiln is 82.3%, and the bulk density is 2.85 g / cm 3 The new wear-resistant high-alumina brick with a room temperature compressive strength of 99.4MPa can extend the ring-forming period of the dezincification rotary kiln for treating zinc-containing dust and mud mixture from March to June to November to December, reducing the impact on production and improving the operating rate, while reducing the production cost of the rotary kiln. DETAILED DESCRIPTION

[0014] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0015] The present invention proposes a method for extending the ring formation period in a dezincifying rotary kiln, the method comprising: controlling the total content of total iron, SiO2 and CaO in a zinc-containing dust sludge mixture to be within 50% of the total mass of the zinc-containing dust sludge mixture, the mass ratio of the total iron, SiO2 and CaO being 3-4.8:1-1.5:1; and controlling the standard deviation of the total iron, the standard deviation of SiO2 and the standard deviation of CaO in the zinc-containing dust sludge mixture to be within a set threshold value.

[0016] In a specific embodiment of the method of the present invention, the zinc-containing dust mud mixture is gas mud and / or gas ash.

[0017] In a specific embodiment of the method of the present invention, in order to reduce the amount of materials in the rotary kiln slag that are likely to cause rotary kiln ringing, such as fayalite and calcium-ferrous olivine, the total content of total iron, SiO2 and CaO in the zinc-containing dust mixture is controlled within 50% of the total mass of the zinc-containing dust mixture, for example, the total content of total iron, SiO2 and CaO is 50%, 48%, 45%, 43.88%, 40%, 30%, 20% or 10%.

[0018] In a specific embodiment of the method of the present invention, in order to effectively reduce the amount of fayalite and calcium-ferrous olivine generated and prevent the formation of ring products in the dezincification rotary kiln, in the zinc-containing dust and mud mixture, the mass ratio of total iron, SiO2 and CaO is 3-4.8:1-1.5:1, for example, it can be 3:1:1, 3.89:1.24:1, 3:1.17:1, 4:1.5:1, 3.89:1.24:1 or 4.8:1.5:1.

[0019] In a preferred embodiment of the method of the present invention, based on the total mass of the zinc-containing dust and sludge mixture as 100 mass%, the total iron content is ≤30 mass%. When the total iron content is >30 mass%, the amount of materials such as fayalite and calcium-ferrous olivine in the rotary kiln slag that are prone to cause rotary kiln ringing will increase; the SiO2 content is ≤10 mass%. When the SiO2 content is >10 mass%, the amount of materials such as fayalite and calcium-ferrous olivine in the rotary kiln slag that are prone to cause rotary kiln ringing will increase; the CaO content is ≤10 mass%. When the CaO content is >10 mass%, the amount of materials such as calcium-ferrous olivine in the rotary kiln slag that are prone to cause rotary kiln ringing will increase. In order to reduce the production of fayalite and calcium-ferrous olivine, slow down the production of ring-forming products in the dezincification rotary kiln, further extend the ring-forming period of the dezincification rotary kiln, and extend the ring-forming period of the dezincification rotary kiln for treating zinc-containing dust and mud mixture from March to June to November to December, in a more preferred case, based on the total mass of the zinc-containing dust and mud mixture as 100 mass%, the total iron content is 25-28 mass%, for example, 25 mass%, 26 mass%, 27.85 mass% or 28 mass%; the SiO2 content is 8-9 mass%, for example, 8 mass%, 8.87 mass% or 9 mass%; the CaO content is 6-7.5 mass%, for example, 6 mass%, 7.16 mass% or 7.5 mass%. In a further preferred case, based on the total mass of the zinc-containing dust sludge mixture being 100 mass %, the total iron content is 27.85 mass %, the SiO2 content is 8.87 mass %, and the CaO content is 7.16 mass %.

[0020] In a specific embodiment of the method of the present invention, the standard deviation of total iron in the zinc-containing dust sludge mixture is controlled to be ≤0.30%. When the standard deviation of total iron is >0.30%, it indicates that the mixture is unevenly mixed, which may easily lead to a local total iron content greater than 30% by mass in the rotary kiln, thereby generating a large amount of ferroitite and calcium-ferroitite, resulting in ring formation in the rotary kiln; the standard deviation of SiO2 in the zinc-containing dust sludge mixture is controlled to be ≤0.20%. When the standard deviation of SiO2 is >0.20%, it indicates that the mixture is unevenly mixed, which may easily lead to a local SiO 2 is greater than 10% by mass, thereby generating a large amount of fayalite and olivine, resulting in ring formation in the rotary kiln; the standard deviation of CaO in the zinc-containing dust and sludge mixture is controlled to be ≤0.20%. When the standard deviation of CaO is >0.20%, it indicates that the mixture is unevenly mixed, which can easily lead to a local CaO content greater than 10% by mass in the rotary kiln, thereby generating a large amount of fayalite and olivine, resulting in ring formation in the rotary kiln; in this article, standard deviation is a statistic that measures the degree of discreteness of a data set, and it is the arithmetic square root of the variance.

[0021] The smaller the standard deviation, the less these values ​​deviate from the average value, that is, the better the mixing effect of the material, and vice versa. To enhance the mixing effect of zinc-containing dust and mud mixtures, you can use a strong mixer or increase the mixing times. If the standard deviation of TFe, SiO2, CaO, etc. is large, it means that the mixture is not mixed evenly, which can easily lead to a local TFe content greater than 30%, a SiO2 content greater than 10%, and a CaO content greater than 10% in the rotary kiln, thereby generating a large amount of fayalite and calcium-ferroolitic olivine, resulting in ring formation in the rotary kiln.

[0022] In a preferred case, the contents of total iron, SiO2 and CaO in the zinc-containing dust sludge mixture are reasonably regulated within a certain range, and the standard deviations of total iron, SiO2 and CaO are controlled at the same time, so that the mixing effect of the zinc-containing dust sludge mixture is optimized, thereby reducing the amount of ring-forming products in the dezincification rotary kiln and extending the ring-forming period of the dezincification rotary kiln to 11-12 months. The standard deviation of total iron in the zinc-containing dust sludge mixture is 0.25-0.27%, for example, 0.25%, 0.26% or 0.27%; the standard deviation of SiO2 in the zinc-containing dust sludge mixture is 0.16-0.18%, for example, 0.16%, 0.17% or 0.18%; the standard deviation of CaO in the zinc-containing dust sludge mixture is 0.17-0.19%, for example, 0.17%, 0.18% or 0.19%. In a more preferred embodiment, the standard deviation of total iron in the zinc dust mixture is 0.26%, the standard deviation of SiO2 in the zinc dust mixture is 0.17%, and the standard deviation of CaO in the zinc dust mixture is 0.18%.

[0023] In a specific embodiment of the method described in the present invention, the method also includes using high-alumina bricks with an Al2O3 content of ≥80% in the high-temperature zone of the rotary kiln. The higher the Al2O3 content in the high-alumina bricks, the stronger its ability to resist erosion by ferroolitic acid and calcium-ferroic acid olivine, and the lower the probability of ring formation, thereby effectively extending the ring formation period of the dezincification rotary kiln.

[0024] In a preferred embodiment of the method of the present invention, the volume density of the high alumina brick is 2.80-3.00 g / cm 3 When the volume density of high alumina brick is less than 2.80g / cm 3 When the volume density of high alumina brick is greater than 3.00g / cm 3 At the same time, the wear resistance and thermal insulation of high alumina bricks are poor.

[0025] In a preferred embodiment of the method of the present invention, the room temperature compressive strength of the high alumina brick is 80-100MPa. When the room temperature compressive strength of the high alumina brick is less than 80MPa, the high alumina brick is easily tumbled and dropped by the slag in the kiln, causing cracks or fragments in the brick, which makes it easy to be corroded by iron olivine and calcium iron olivine to form rings. When the room temperature compressive strength of the high alumina brick is greater than 100MPa, the production cost is too high and the cost performance is low. In this article, the room temperature compressive strength refers to the result of heating the high alumina brick to room temperature (25°C) for a pressure test, and the result is called the room temperature compressive strength. In a more preferred case, the Al2O3 content of the high alumina brick is 82.3%, and the volume density is 2.85g / cm 3 , the compressive strength at room temperature is 99.4MPa.

[0026] In actual operation, for the treatment of rotary kiln ring formation, if it is discovered early and the position is accurately determined, the following measures can be taken: (1) reciprocating the position of the combustion zone to burn the ring; (2) using wind to implement local sudden cooling of the ring to cause it to shrink unevenly and fall off naturally.

[0027] The experimental methods or test methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials are obtained from conventional commercial channels or prepared by conventional methods unless otherwise specified.

[0028] The dezincification rotary kiln in the following embodiments and comparative examples processes zinc-containing dust and mud mixtures with a processing capacity of 300,000 tons / year and about 900 tons / day, wherein the main raw material of the zinc-containing dust and mud mixture is a mixture of gas mud and gas ash.

[0029] Example 1

[0030] The content of TFe in the zinc-containing dust sludge mixture is controlled to be 27.85%, the content of SiO2 is 8.87%, and the content of CaO is 7.16%. By mixing the single raw materials and mixing the mixture in three steps, the standard deviation of TFe is controlled to be 0.26%, the standard deviation of SiO2 is 0.17%, and the standard deviation of CaO is 0.18%.

[0031] The volume density of the new wear-resistant high-alumina brick used in the high-temperature zone of the rotary kiln is 2.85g / cm 3 , Al2O3 content is 82.3%, and the room temperature compressive strength is 99.4MPa;

[0032] According to testing, the ring formation period of the rotary kiln can be extended to 11 months, that is, the kiln only needs to be stopped for maintenance once a year, for about 30 days each time, and the annual rotary kiln operation rate can exceed 90%.

[0033] Example 2

[0034] The content of TFe in the zinc dust sludge mixture is controlled to be 21.6%, the content of SiO2 is 8.4%, and the content of CaO is 7.2%. By mixing the single raw materials and mixing the mixture in three steps, the standard deviation of TFe is controlled to be 0.28%, the standard deviation of SiO2 is 0.18%, and the standard deviation of CaO is 0.19%.

[0035] The volume density of the new wear-resistant high-alumina brick used in the high-temperature zone of the rotary kiln is 2.80g / cm 3 , Al2O3 content is 80%, and the room temperature compressive strength is 80MPa;

[0036] According to testing, the ring formation period of the rotary kiln can be extended to about 10 months, and the annual rotary kiln operation rate can exceed 85%.

[0037] Example 3

[0038] The content of TFe in the zinc dust sludge mixture is controlled to be 18.4%, the content of SiO2 is 6.9%, and the content of CaO is 4.6%. By mixing the single raw materials and mixing the mixture in three steps, the standard deviation of TFe is controlled to be 0.28%, the standard deviation of SiO2 is 0.18%, and the standard deviation of CaO is 0.19%.

[0039] The volume density of the new wear-resistant high-alumina brick used in the high-temperature zone of the rotary kiln is 2.85g / cm 3 , Al2O3 content is 82.3%, and the room temperature compressive strength is 99.4MPa;

[0040] According to testing, the ring formation period of the rotary kiln can be extended to 11 months, that is, the kiln only needs to be stopped for maintenance once a year, for about 30 days each time, and the annual rotary kiln operation rate can exceed 90%.

[0041] Example 4

[0042] The content of TFe in the zinc-containing dust sludge mixture is controlled to be 27.85%, the content of SiO2 is 8.87%, and the content of CaO is 7.16%. By mixing the single raw materials and mixing the mixture in three steps, the standard deviation of TFe is controlled to be 0.26%, the standard deviation of SiO2 is 0.17%, and the standard deviation of CaO is 0.18%.

[0043] The high temperature zone of the rotary kiln adopts a new type of wear-resistant high-alumina brick with a volume density of 2.0g / cm 3 , Al2O3 content is 60%, and the room temperature compressive strength is 70MPa;

[0044] According to testing, the ring formation period of the rotary kiln can be extended to 7 months, and the annual rotary kiln operation rate is less than 80%.

[0045] Example 5

[0046] The content of TFe in the zinc-containing dust sludge mixture is controlled to be 20%, the content of SiO2 is controlled to be 15%, and the content of CaO is controlled to be 15%. By mixing the single raw materials and the mixture through three mixing steps, the standard deviation of TFe is controlled to be 0.26%, the standard deviation of SiO2 is controlled to be 0.17%, and the standard deviation of CaO is controlled to be 0.18%;

[0047] The high temperature zone of the rotary kiln adopts a new type of wear-resistant high-alumina brick with a volume density of 2.0g / cm 3 , Al2O3 content is 60%, and the room temperature compressive strength is 70MPa;

[0048] According to testing, the ring formation period of the rotary kiln can be extended to about 8 months, and the annual rotary kiln operation rate is less than 80%.

[0049] Comparative Example 1

[0050] The content of TFe in the zinc dust sludge mixture is controlled to be 30%, the content of SiO2 is controlled to be 15%, and the content of CaO is controlled to be 10%. By mixing the single raw materials and the mixture through three mixing steps, the standard deviation of TFe is controlled to be 0.5%, the standard deviation of SiO2 is controlled to be 0.3%, and the standard deviation of CaO is controlled to be 0.3%;

[0051] The volume density of the new wear-resistant high-alumina brick used in the high-temperature zone of the rotary kiln is 2.85g / cm 3 , Al2O3 content is 82.3%, and the room temperature compressive strength is 99.4MPa;

[0052] According to testing, the ring formation cycle of the rotary kiln is 5 months, and the kiln needs to be stopped for maintenance twice a year. The annual operating rate of the rotary kiln is only about 70%.

[0053] Comparative Example 2

[0054] The content of TFe in the zinc dust sludge mixture is controlled to be 10%, the content of SiO2 is controlled to be 30%, and the content of CaO is controlled to be 10%. By mixing the single raw materials and mixing the mixture in three steps, the standard deviation of TFe is controlled to be 0.5%, the standard deviation of SiO2 is controlled to be 0.3%, and the standard deviation of CaO is controlled to be 0.3%;

[0055] The volume density of the new wear-resistant high-alumina brick used in the high-temperature zone of the rotary kiln is 2.85g / cm 3 , Al2O3 content is 82.3%, and the room temperature compressive strength is 99.4MPa;

[0056] According to testing, the ring formation period of the rotary kiln is about 6 months, and the annual rotary kiln operation rate is less than 75%.

[0057] It can be seen from the results of Examples 1-5 and Comparative Examples 1-2 that the method of the present invention can be used to treat zinc-containing dust sludge mixtures, which can reduce the amount of fayalite and olivine, and enhance the ability to resist the erosion of fayalite and olivine, thereby extending the ring-forming period of the dezincification rotary kiln. When the content of TFe, the content of SiO2 and the content of CaO in the zinc-containing dust sludge mixture are controlled within a certain range, and the standard deviation of TFe, SiO2 and CaO when mixed is accurately controlled, and at the same time, a new type of wear-resistant high-alumina brick with a certain Al2O3 content, bulk density and room-temperature compressive strength is used in the high-temperature zone of the rotary kiln, the ring-forming period of the dezincification rotary kiln for treating zinc-containing dust sludge mixtures can be extended from March to June to November to December, thereby reducing the impact on production, improving the operating rate, and reducing the production cost of the rotary kiln.

[0058] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for extending the ring formation period in a dezincification rotary kiln, characterized in that: The method comprises: controlling the total content of total iron, SiO2 and CaO in a zinc-containing dust sludge mixture to be within 50% of the total mass of the zinc-containing dust sludge mixture, wherein the mass ratio of the total iron, SiO2 and CaO is 3-4.8:1-1.5:1; and controlling the standard deviation of the total iron, the standard deviation of SiO2 and the standard deviation of CaO in the zinc-containing dust sludge mixture to be within a set threshold value.

2. The method for prolonging the ring formation period in a dezincification rotary kiln according to claim 1, characterized in that: Taking the total mass of the zinc-containing dust sludge mixture as 100 mass %, the total iron content is ≤30 mass %, the SiO2 content is ≤10 mass %, and the CaO content is ≤10 mass %.

3. The method for prolonging the ring formation period in a dezincification rotary kiln according to claim 1, characterized in that: The standard deviation of total iron in the zinc-containing dust sludge mixture is ≤0.30%, the standard deviation of SiO2 in the zinc-containing dust sludge mixture is ≤0.20%, and the standard deviation of CaO in the zinc-containing dust sludge mixture is ≤0.20%.

4. The method for prolonging the ring formation period in a dezincification rotary kiln according to claim 2, characterized in that: Taking the total mass of the zinc-containing dust sludge mixture as 100 mass %, the total iron content is 25-28 mass %, the SiO2 content is 8-9 mass %, and the CaO content is 6-7.5 mass %.

5. The method for prolonging the ring formation period in a dezincification rotary kiln according to claim 4, characterized in that: Taking the total mass of the zinc-containing dust sludge mixture as 100 mass %, the total iron content is 27.85 mass %, the SiO2 content is 8.87 mass %, and the CaO content is 7.16 mass %.

6. The method for prolonging the ring formation period in a dezincification rotary kiln according to claim 3, characterized in that: The standard deviation of total iron in the zinc dust sludge mixture is 0.25-0.27%, the standard deviation of SiO2 in the zinc dust sludge mixture is 0.16-0.18%, and the standard deviation of CaO in the zinc dust sludge mixture is 0.17-0.19%.

7. The method for prolonging the ring formation period in a dezincification rotary kiln according to claim 6, characterized in that: The standard deviation of total iron in the zinc dust mixture is 0.26%, the standard deviation of SiO2 in the zinc dust mixture is 0.17%, and the standard deviation of CaO in the zinc dust mixture is 0.18%.

8. The method for prolonging the ring formation period in a dezincification rotary kiln according to claim 1, characterized in that: The method also includes using high-alumina bricks with an Al2O3 content of ≥80% in the high-temperature zone of the rotary kiln.

9. The method for prolonging the ring formation period in a dezincification rotary kiln according to claim 8, characterized in that: The volume density of the high alumina brick is 2.80-3.00 g / cm 3 , the compressive strength at room temperature is 80-100MPa.

10. The method for prolonging the ring formation period in a dezincification rotary kiln according to claim 9, characterized in that: The Al2O3 content of the high alumina brick is 82.3% and the volume density is 2.85g / cm 3 , the compressive strength at room temperature is 99.4MPa.