Refractory plate based on copper smelting slag dressing tailings and preparation method of refractory plate

Abstract

The invention discloses a refractory plate based on copper smelting slag separation tailings and a preparation method thereof, and the refractory plate is obtained by pressing and sintering a mixture comprising 50 wt%-100 wt% of copper smelting slag separation tailings, 10 wt%-50 wt% of fly ash and 0 wt%-10 wt% of kaolin as a raw material. The preparation method comprises the following steps: grinding the copper smelting slag tailings into powder, and uniformly mixing the powder with the fly ash and the kaolin to obtain a mixture; adding a binder and water, uniformly mixing, carrying out compression molding, and drying to obtain a dry blank; and putting the dry blank into a resistance furnace, sintering the blank through stage heating, and naturally cooling to obtain the refractory plate. The prepared high-strength refractory plate has excellent high-temperature resistance and mechanical strength, a novel environment-friendly refractory material is provided for industries such as nonferrous metallurgy, ceramics and cement, and a new thought is provided for large-scale consumption and utilization of copper smelting slag tailings and fly ash.

Description

Technical Field

[0001] This invention belongs to the field of inorganic materials technology, and in particular relates to a refractory plate based on copper smelting slag tailings and its preparation method. Background Technology

[0002] With the continuous development of the non-ferrous metals industry, my country's refined copper production has shown a year-on-year increasing trend. In the pyrometallurgical copper smelting process, 2 to 3 tons of slag are generated for every ton of copper produced. After the valuable metals are extracted from this slag through mineral processing, the remaining large amount of copper smelting tailings still faces the challenge of large-scale disposal. In addition, my country's coal-fired power plants generate a large amount of fly ash every year, which has become one of the largest industrial wastes emitted in my country.

[0003] The stockpiling and disposal of copper smelting slag tailings and fly ash not only occupies a large amount of land resources but also easily generates dust pollution of the atmosphere. If discharged into water systems, it may cause river siltation, and the toxic chemicals it contains may also harm human health and ecosystems. Therefore, achieving efficient resource utilization of copper smelting slag tailings and fly ash is of great practical significance for promoting the green and sustainable development of my country's non-ferrous metals and power industries.

[0004] Currently, the resource utilization of copper smelting slag tailings is mainly concentrated in the building materials sector. Specific applications include using it as a raw material for cement clinker, replacing sand and gravel in concrete production, using it as aggregate in asphalt mixture production, and preparing non-fired black bricks. However, due to market fluctuations and sales radius limitations in the building materials industry, the annual amount of copper smelting slag tailings utilized through these methods is very limited. Furthermore, although there are reports of using copper smelting slag tailings as a raw material for ironmaking, the amount of tailings utilized by the ironmaking industry is also limited because the content of key elements often fails to meet the standards for raw materials entering the furnace at ironmaking plants.

[0005] Fly ash, rich in silicon and aluminum, shares some chemical similarities with ceramic materials, and is therefore often used as a low-cost substitute for ceramic and refractory raw materials. However, fly ash contains high levels of impurities and has poor compositional stability, which negatively impacts the high-temperature performance of ceramic products. In conclusion, achieving large-scale, high-value-added utilization of copper smelting slag tailings and fly ash is crucial for promoting the high-quality development of both the copper smelting and power industries.

[0006] Meanwhile, smelting workshops and pyrometallurgical workshops in smelters operate under harsh conditions of high temperature and corrosion for extended periods. Therefore, the selection and application of refractory materials for kiln linings are crucial for ensuring the stable operation of smelting equipment, improving production efficiency, and reducing maintenance costs. However, the non-ferrous metals industry currently faces challenges related to the stability of raw material supply for refractory materials. Traditional refractory materials rely heavily on natural ores (such as clay and magnesite), and the mining of these ores causes significant environmental damage. In recent years, these ores have been subject to strict national regulations, leading to drastic fluctuations in refractory material prices and introducing uncertainty into the stable production of the non-ferrous metals industry. Summary of the Invention

[0007] The technical problem this invention aims to solve is to overcome the shortcomings of existing technologies and provide a refractory plate based on copper smelting slag tailings and its preparation method. Using copper smelting slag tailings as the main raw material, combined with solid waste fly ash, a binder is added and the plate is pressed into shape. Then, it undergoes a two-stage high-temperature sintering process to obtain a high-strength, environmentally friendly refractory plate. The high-strength refractory plate prepared by this invention exhibits excellent high-temperature resistance and mechanical strength, with a solid waste content exceeding 90 wt%. This provides a new environmentally friendly refractory material for industries such as non-ferrous metallurgy, ceramics, and cement, and also offers a new approach for the large-scale utilization of copper smelting slag tailings and fly ash.

[0008] To solve the above-mentioned technical problems, the present invention provides a refractory plate based on copper smelting slag tailings. The refractory plate is obtained by pressing and sintering a mixture of 50 wt% to 100 wt% copper smelting slag tailings, 10 wt% to 50 wt% fly ash, and 0 wt% to 10 wt% kaolin.

[0009] Furthermore, in the aforementioned refractory plate, the iron content in the copper smelting slag tailings is 35 wt% to 40 wt%, the silicon content is 10 wt% to 20 wt%, and the aluminum content is 2 wt% to 5 wt%; the main crystalline phase composition is iron(III) oxide, ferrous silicate, and aluminum(III) oxide.

[0010] Furthermore, in the aforementioned refractory board, the fly ash contains 50 wt% to 55 wt% silicon, 30 wt% to 35 wt% aluminum, and 0 wt% to 5 wt% iron.

[0011] Furthermore, in the aforementioned refractory board, the kaolin contains 50 wt% to 55 wt% silicon and 40 wt% to 50 wt% aluminum.

[0012] Based on a general technical concept, the present invention also provides a method for preparing the aforementioned refractory board, the method comprising the following steps: S1. Grind the copper smelting slag tailings into powder, and mix it evenly with fly ash and kaolin to obtain a mixture; S2. Add 3 wt% of binder and 1.5 wt% of water by total mass to the mixture, mix evenly, press and shape, and dry to obtain a dry blank; S3. Place the dry blank into a resistance furnace, sinter the blank by staged heating, and obtain a refractory plate after natural cooling.

[0013] In the above preparation method, further, in step S2, the binder is industrial dextrin or pulp waste liquid.

[0014] In the above preparation method, the pressing pressure in step S2 is 120 MPa, and the holding time is 60 to 90 seconds.

[0015] In the above preparation method, the stage heating in S3 to sinter the green body specifically involves holding at 940℃ for 3 hours and then holding at 1200℃ for 3 hours.

[0016] Compared with the prior art, the advantages of the present invention are as follows: (1) This invention provides a refractory board based on copper smelting slag tailings, using smelting tailings discharged from copper smelters and fly ash discharged from coal-fired power plants as the main raw materials. The solid waste content in the composition exceeds 90 wt%, which not only solves the waste disposal problem in the copper smelting and power industries, but also provides a refractory board that can be used on a large scale in smelting enterprises and metal processing enterprises, with environmental and economic benefits. Furthermore, by adjusting the ratio of fly ash to copper smelting slag tailings and controlling the Al / Si ratio in the raw material composition, the formation of iron-aluminum spinel and mullite refractory crystal phases in the refractory board is controlled, which greatly improves the high temperature resistance of the refractory board. Its structure is dense with an apparent porosity of less than 10.0%, good compressive strength with a compressive strength greater than 140 MPa, and good high temperature resistance with a softening temperature of more than 1200℃ under a 0.2 MPa load. The performance indicators can meet the industry standard YB / T 5106-2009 PN-3 clay brick standard.

[0017] (2) This invention provides a method for preparing refractory plates based on copper smelting slag tailings. By adjusting and controlling the content of fly ash and kaolin, controlling the content of potassium and sodium elements in the green body, and controlling the formation of low melting point glass phase in the refractory plate under the premise of appropriately reducing the sintering temperature and promoting densification, the density and high temperature resistance of the refractory plate are greatly improved.

[0018] (3) This invention provides a method for preparing refractory plates based on copper smelting slag tailings. Copper smelting slag tailings and fly ash are used as the main raw materials. According to their different sintering properties, a segmented sintering process is adopted. In the first stage of sintering, by holding at 940℃ for 3 hours, the ferrous silicate in the copper smelting slag tailings is decomposed into ferrous oxide and silicon dioxide, preventing the low-melting-point ferrous silicate from melting and separating during high-temperature sintering. In the second stage of sintering, by holding at 1200℃ for 3 hours, the generated ferrous oxide and silicon dioxide react fully with the fly ash to achieve densification sintering. Detailed Implementation

[0019] The present invention will be further described below with reference to specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0020] The materials, reagents, and instruments used in the following examples are all commercially available. Unless otherwise specified, the experimental methods used in the following examples are conventional methods in the art.

[0021] The copper smelting tailings used in the following examples came from a copper smelter in Jiangxi Province. The iron content was 35 wt%–40 wt%, the silicon content was 10 wt%–20 wt%, and the aluminum content was 2 wt%–5 wt%. The main crystalline phases were iron(III) oxide, ferrous silicate, and aluminum(III) oxide. The fly ash used had a silicon content of 50 wt%–55 wt%, an aluminum content of 30 wt%–35 wt%, and an iron content of 0 wt%–5 wt%. The kaolin used had a silicon content of 50 wt%–55 wt% and an aluminum content of 40 wt%–50 wt%.

[0022] Example 1 A method for preparing refractory plates based on copper smelting slag tailings includes the following steps: (1) According to the copper smelting slag tailings 100wt% of the raw materials, and grind them into powder with a particle size of less than 0.074mm, add 3% of industrial dextrin and 1.5% of water by total mass, and mix evenly to obtain a plastic water-containing powder.

[0023] (2) Press the above-mentioned water-containing powder into a mold at a pressure of 120 MPa. After demolding, place it in an oven to dry for 24 hours to obtain a dry blank. (3) Place the dried billet into an electric resistance furnace and heat it from room temperature to 940 ℃ at a heating rate of 5 ℃ / min, hold it at that temperature for 3 h, then heat it to 1200 ℃ at a heating rate of 3 ℃ / min, and hold it at that temperature for 3 h. Remove it after cooling in the furnace.

[0024] Example 2 A method for preparing refractory plates based on copper smelting slag tailings includes the following steps: (1) The copper smelting slag tailings of 90wt% and kaolin of 10wt% were mixed and ground into powder with a particle size of less than 0.074mm. Then, 3% of industrial dextrin and 1.5% of water were added and mixed evenly to obtain a plastic water-containing powder.

[0025] (2) Press the above-mentioned water-containing powder into a mold at a pressure of 120 MPa. After demolding, place it in an oven to dry for 24 hours to obtain a dry blank. (3) Place the dried billet into an electric resistance furnace and heat it from room temperature to 940 ℃ at a heating rate of 5 ℃ / min, hold it at that temperature for 3 h, then heat it to 1200 ℃ at a heating rate of 3 ℃ / min, and hold it at that temperature for 3 h. Remove it after cooling in the furnace.

[0026] Example 3 A method for preparing refractory plates based on copper smelting slag tailings includes the following steps: (1) The following ingredients are prepared: 70wt% copper smelting slag tailings, 20wt% fly ash, and 10wt% kaolin. The mixture is ground to a particle size of less than 0.074mm. Then, 3% industrial dextrin and 1.5% water are added and mixed evenly to obtain a plastic water-containing powder.

[0027] (2) Press the above-mentioned water-containing powder into a mold at a pressure of 120 MPa. After demolding, place it in an oven to dry for 24 hours to obtain a dry blank. (3) Place the dried billet into an electric resistance furnace and heat it from room temperature to 940 ℃ at a heating rate of 5 ℃ / min, hold it at that temperature for 3 h, then heat it to 1200 ℃ at a heating rate of 3 ℃ / min, and hold it at that temperature for 3 h. Remove it after cooling in the furnace.

[0028] Example 4 A method for preparing refractory plates based on copper smelting slag tailings includes the following steps: (1) The ingredients are prepared according to the following proportions: 50wt% copper smelting slag tailings, 40wt% fly ash, and 10wt% kaolin. The mixture is ground to a particle size of less than 0.074mm. Then, 3% industrial dextrin and 1.5% water are added and mixed evenly to obtain a plastic water-containing powder.

[0029] (2) Press the above-mentioned water-containing powder into a mold at a pressure of 120 MPa. After demolding, place it in an oven to dry for 24 hours to obtain a dry blank. (3) Place the dried billet into an electric resistance furnace and heat it from room temperature to 940 ℃ at a heating rate of 5 ℃ / min, hold it at that temperature for 3 h, then heat it to 1200 ℃ at a heating rate of 3 ℃ / min, and hold it at that temperature for 3 h. Remove it after cooling in the furnace.

[0030] Example 5 A method for preparing refractory plates based on copper smelting slag tailings includes the following steps: (1) Prepare a mixture of 50wt% copper smelting slag tailings and 50wt% fly ash, grind it into powder with a particle size of less than 0.074mm, add 3% industrial dextrin and 1.5% water by total mass, mix evenly to obtain a plastic water-containing powder.

[0031] (2) Press the above-mentioned water-containing powder into a mold at a pressure of 120 MPa. After demolding, place it in an oven to dry for 24 hours to obtain a dry blank. (3) Place the dried billet into an electric resistance furnace and heat it from room temperature to 940 ℃ at a heating rate of 5 ℃ / min, hold it at that temperature for 3 h, then heat it to 1200 ℃ at a heating rate of 3 ℃ / min, and hold it at that temperature for 3 h. Remove it after cooling in the furnace.

[0032] The softening start temperature under 0.2 MPa load, room temperature compressive strength, and apparent porosity were tested for Examples 1 to 5. The softening start temperature under 0.2 MPa load was tested according to the industry standard YB / T 370-2016, the room temperature compressive strength was tested according to the national standard GB / T 5072-2023, and the apparent porosity was tested according to the national standard GB / T 2997-2015. The test results are shown in Table 1.

[0033] Table 1: Test Results of Refractory Board Performance

[0034] This invention uses copper smelting slag tailings, fly ash, and kaolin as the main raw materials. When only slag tailings are used as raw materials (Example 1), although two-stage sintering can be used to fully decompose the ferrous silicate in the copper smelting slag tailings into ferrous oxide and silicon dioxide at 940℃, and then a densified plate is obtained at high temperature, the Al / Si ratio in the copper smelting slag tailings is too low, and the fired plate lacks a high-temperature crystalline phase. Its softening temperature under 0.2MPa load is only 960℃, which cannot meet the national standard requirements. Example 2 adds 10wt% kaolin in addition to copper smelting slag tailings, which acts as a high-temperature binder and provides a small amount of Al element, increasing the compressive strength of the plate to 202.6MPa and the softening temperature under load to 1007℃. In Example 3, a portion of the copper smelting slag tailings was replaced with fly ash to provide aluminum. The fly ash, after high-temperature sintering, forms a mullite crystalline phase, which also helps improve the high-temperature performance of the refractory board. However, the addition of fly ash reduces the system density, leading to an increase in apparent porosity, thus reducing the room-temperature compressive strength of the board. The refractory board prepared using the formula in Example 4 achieved a softening temperature of 1206℃ under a 0.2MPa load, a room-temperature compressive strength of 147.5MPa, and an apparent porosity of 9.0%, meeting the specifications for PN-3 grade clay bricks in the industry standard YB / T 5106-2009. In Example 5, kaolin was removed, and only fly ash and copper smelting slag tailings were used as raw materials. The resulting board showed a significant decrease in all its properties, indicating that kaolin is necessary as a high-temperature binder.

[0035] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A refractory board based on copper smelting slag tailings, characterized in that, The refractory board is obtained by pressing and sintering a mixture of 50 wt% to 100 wt% copper smelting slag tailings, 10 wt% to 50 wt% fly ash, and 0 wt% to 10 wt% kaolin.

2. The refractory board according to claim 1, characterized in that, The copper smelting slag tailings contain 35 wt% to 40 wt% iron, 10 wt% to 20 wt% silicon, and 2 wt% to 5 wt% aluminum; the main crystalline phases are iron(III) oxide, ferrous silicate, and aluminum(III) oxide.

3. The refractory board according to claim 1, characterized in that, The fly ash contains 50 wt% to 55 wt% silicon, 30 wt% to 35 wt% aluminum, and 0 wt% to 5 wt% iron.

4. The refractory board according to claim 1, characterized in that, The kaolin contains 50wt% to 55wt% silicon and 40wt% to 50wt% aluminum.

5. A method for preparing the refractory board according to any one of claims 1 to 4, characterized in that, The preparation method includes the following steps: S1. Grind the copper smelting slag tailings into powder, and mix it evenly with fly ash and kaolin to obtain a mixture; S2. Add 3 wt% of binder and 1.5 wt% of water by total mass to the mixture, mix evenly, press and shape, and dry to obtain a dry blank; S3. Place the dry blank into a resistance furnace, sinter the blank by staged heating, and obtain a refractory plate after natural cooling.

6. The preparation method according to claim 5, characterized in that, In step S2, the binder is industrial dextrin or pulp waste liquid.

7. The preparation method according to claim 5, characterized in that, The pressing pressure in S2 is 120 MPa, and the holding time is 60 to 90 seconds.

8. The preparation method according to claim 5, characterized in that, The staged heating in S3 to sinter the billet specifically involves holding it at 940℃ for 3 hours and then holding it at 1200℃ for 3 hours.

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