Method for evaluating reusability of refractory after use

Abstract

The present application relates to the field of refractory materials, and particularly relates to a method for evaluating the reusing performance of used refractory materials. The method comprises: detecting the contents of soluble potassium and soluble sodium in the used refractory materials, and judging the reusing performance of the used refractory materials according to the detection results; when the sum of the contents of the soluble potassium and the soluble sodium is less than 0.4wt%, it is judged that the used refractory materials can be used as raw materials to prepare refractory castables; when the sum of the contents of the soluble potassium and the soluble sodium is between 0.4wt% and 0.8wt%, it is judged that the used refractory materials can be used to prepare refractory plastic materials. The present application provides a method for simply and efficiently evaluating the application and quality level of used refractory materials, which has important application value in the field of refractory material reuse.

Description

Technical Field

[0001] This invention relates to the field of refractory materials, and more particularly to a method for evaluating the reuse performance of used refractory materials. Background Technology

[0002] As a non-renewable geological mineral resource, bauxite has experienced a significant decline in both reserves and quality after years of industrial mining. Given the fundamental role of aluminum-based refractories in metallurgy and building materials, a prominent contradiction is emerging between the raw material supply system and the demands of industrial development. This is particularly true against the backdrop of expanding industry scale and accelerated product iteration, leading to increasing pressure from resource constraints. Simultaneously, fluctuations in the supply of bauxite ore often cause drastic price fluctuations, which directly impact refractory material manufacturing, significantly affecting the overall cost of products.

[0003] In this context, the rational reuse of used refractory materials demonstrates multiple values: from a resource perspective, it can effectively supplement the gap in the raw material supply chain; from an economic perspective, it can mitigate the impact of raw material price fluctuations on enterprise production costs; more importantly, this recycling model breaks through the linear consumption characteristics of the traditional model, significantly improves resource utilization, and opens up a new path for the sustainable development of the manufacturing industry. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a method for evaluating the reuse performance of used refractory materials.

[0005] In a first aspect, the present invention provides a method for evaluating the reuse performance of used refractory materials, comprising: For used refractory materials, the content of soluble potassium and soluble sodium in the used refractory materials is tested, and the reuse performance of the used refractory materials is judged based on the test results. When the sum of the contents of soluble potassium and soluble sodium is less than 0.4 wt%, the used refractory material is determined to be usable as a raw material for preparing refractory castables; when the sum of the contents of soluble potassium and soluble sodium is between 0.4 and 0.8 wt%, the used refractory material is determined to be usable for preparing refractory plastics.

[0006] Based on extensive experimental research, this invention has found that the content of soluble potassium and sodium has a significant impact on the amount of water added, fluidity, and hardening time of unshaped refractories. Therefore, by detecting the content of soluble potassium and soluble sodium in used refractories, it can be determined whether the used refractories can be directly reused or whether further performance evaluation is required.

[0007] Secondly, the present invention provides a method for reusing used refractory materials, comprising: For used refractory materials, the content of soluble potassium and soluble sodium in the used refractory materials is tested. When the sum of the contents of soluble potassium and soluble sodium is less than 0.4 wt%, the used refractory materials are used as raw materials to prepare refractory castables; when the sum of the contents of soluble potassium and soluble sodium is between 0.4 and 0.8 wt%, the used refractory materials are used to prepare refractory plastics.

[0008] Furthermore, if the combined content of the soluble potassium and soluble sodium exceeds 0.8 wt%, further evaluation is required before utilization.

[0009] Furthermore, the contents of the soluble potassium and soluble sodium are calculated using the following method: The contents of potassium oxide and sodium oxide in the solid sample of the used refractory material were measured. After water bath and filtration, filter residue was obtained, and the contents of potassium oxide and sodium oxide in the filter residue were detected. The contents of soluble potassium and soluble sodium were calculated based on the contents of potassium oxide and sodium oxide in the solid sample of the used refractory material and the contents of potassium oxide and sodium oxide in the filter residue.

[0010] Furthermore, the water bath includes: water bath treatment at 35~50℃ for more than 24 hours.

[0011] Furthermore, both the used refractory material solid sample and the filter residue were processed to a particle size of less than 0.09 mm before testing.

[0012] Furthermore, the method for processing the used solid refractory material samples is as follows: The used refractory material was crushed to below 6.7 mm and reduced to 150-250 g using the quartering method; it was also crushed to below 0.5 mm and reduced to 75-125 g using the quartering method. Samples with a particle size less than 0.09 mm were taken for testing.

[0013] Furthermore, the contents of the soluble potassium and soluble sodium are detected by atomic absorption spectrometry, spectrophotometry, broadband ultraviolet absorption spectrometry, or flame photometry, preferably by flame photometry.

[0014] Furthermore, the contents of soluble potassium and soluble sodium are determined by flame photometry, and the contents of soluble potassium and soluble sodium are calculated from the contents of potassium oxide and sodium oxide.

[0015] Furthermore, the used refractory material includes high-alumina refractory materials.

[0016] Furthermore, the preparation method of the refractory castable includes: The used refractory material is mixed with 80 alumina, silica powder, alumina, pure calcium aluminate cement and dispersant to prepare a castable.

[0017] Furthermore, the mixing process involves pre-mixing with stirring for 1-2 minutes, followed by wet mixing with water for 2-3 minutes; the amount of water added to the castable is 6-8%, and the castable is discharged from the boiler after achieving satisfactory workability. The castable with 6-8% water added has a discharge flow value of 120-150mm and a flow value of 115-145mm after 15 minutes.

[0018] Furthermore, the method for preparing the refractory plastic includes: The used refractory material is mixed with 80 alumina, coke powder, refractory clay, pure calcium aluminate cement and additives to prepare a plastic.

[0019] Furthermore, the mixing process involves pre-mixing with stirring for 1-2 minutes, followed by wet mixing with water for 3-5 minutes; the mixture is then removed from the heat after achieving satisfactory workability. The water content for the plastic is 7-8.5%, and the hardening time is 7-9 hours.

[0020] Thirdly, the present invention provides the application of the aforementioned method in improving the reusability of refractory materials.

[0021] The present invention has the following beneficial effects: This invention has revealed that the content of soluble sodium and soluble potassium has a significant impact on the water addition, flowability, and hardening time of used refractory materials, and can largely reflect the performance of the used refractory materials. Therefore, the suitability of used refractory materials for direct reuse can be evaluated by detecting the content of soluble sodium and soluble potassium.

[0022] The method provided by this invention can effectively improve the reuse rate of refractory materials, effectively reduce enterprise production costs, and has significant economic value. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0024] Unless otherwise specified, the experimental methods involved in the following embodiments are conventional methods in the art. For example, you can refer to the experimental manual in the art or follow the conditions recommended in the manufacturer's instructions.

[0025] Unless otherwise specified, all experimental materials and reagents used in the following examples are commercially available.

[0026] Example 1 1. Detection Method (1) The laboratory sample is crushed to below 6.7 mm, reduced to 200 g by quartering, and then crushed to below 0.5 mm. The sample is reduced to 100 g by quartering to form sample I. The sample for testing is processed to form sample II with a particle size of less than 0.09 mm.

[0027] (2) Sample I was heated in a 40°C water bath with 500ml of distilled water for 24 hours, magnetically stirred for 10 minutes, and then filtered. The filter residue was then soaked in 500ml of distilled water and magnetically stirred for 10 minutes before being filtered again. The above steps were repeated once, for a total of 3 filtrations. The resulting filter residue was dried at 110°C for 24 hours and then processed into Sample III with a particle size of less than 0.09mm.

[0028] (3) The potassium oxide and sodium oxide contents of sample II and sample III were determined by flame photometry.

[0029] Soluble potassium and sodium content = Potassium oxide / sodium oxide content in sample II - Potassium oxide / sodium oxide content in sample III.

[0030] 2. Detection Object A 10kg sample of high-alumina recycled refractory material from the throat of a cement plant's grate cooler was tested according to the above-described method. The soluble potassium content (calculated as K₂O) was 0.24%, and the soluble sodium content (calculated as Na₂O) was 0.11%. Using this recycled refractory material as raw material, a castable was prepared from the following raw materials by mass percentage: 58% recycled refractory material, 26% 80% alumina, 5% Al₂O₃ micro powder, 6% silica fume, 5% pure calcium aluminate cement, and 0.24% dispersant. The aggregates, powders, binders, and admixtures were premixed in a forced mixer for 1-2 minutes, followed by wet mixing with an appropriate amount of water for 2-3 minutes. The castable was then discharged from the boiler after achieving good workability. The water content of the castable was 6.8%, the flow value at discharge was 135mm, the flow value at 15 minutes was 130mm, and the hardening time was 6 hours.

[0031] The performance of this castable was tested, and the results are as follows: bulk density 2.64 g / cm³. 3 The compressive strength at 110℃×24h and 1100℃×3h is 110MPa and 122MPa respectively; the flexural strength at 110℃×24h and 1100℃×3h is 15.2MPa and 16.5MPa respectively; the thermal shock resistance (1100℃, water cooling) is greater than 15 cycles; and the alkali resistance is Grade 1. These test results indicate that the castable is a qualified product.

[0032] Example 2 A cement plant used high-alumina refractory material for its kiln head cover. A 10 kg sample was taken and tested according to the above-mentioned implementation method (the same testing method as in Example 1). The soluble potassium content (calculated as K2O) was 0.38% and the soluble sodium content (calculated as Na2O) was 0.26%.

[0033] Refractory plastics were prepared using the used refractory material as raw material, consisting of the following raw materials in the indicated weight percentages: 52% used refractory material, 20% 80% alumina, 10% calcined bauxite powder, 8% refractory clay, 10% pure calcium aluminate cement, 0.2% sodium tripolyphosphate, and 0.15% sodium hexametaphosphate. The aggregates, powders, binders, and additives were premixed in a forced mixer for 1-2 minutes. Then, an appropriate amount of water was added and wet-mixed for 3-5 minutes until the material formed a dough with good workability. The water content was 7.5%, and the hardening time was 8 hours.

[0034] The properties of this plastic were tested, and the results are as follows: bulk density 2.60 g / cm³. 3 The compressive strengths at 110℃×24h and 1100℃×3h are 106MPa and 119MPa, respectively; the flexural strengths at 110℃×24h and 1100℃×3h are 12.2MPa and 13.7MPa, respectively; and the abrasion resistance (1100℃×3h) is 4.8cm. 3 .

[0035] The test results show that the prepared refractory plastic is a qualified product and meets the requirements for practical application.

[0036] Example 3 A 10kg sample of high-alumina refractory material used in the kiln tail decomposition furnace of a cement plant was tested according to the above-described implementation method (the same testing method as in Example 1). The soluble potassium content (calculated as K2O) was 0.65%, and the soluble sodium content (calculated as Na2O) was 0.3%.

[0037] The used refractory material was used as a raw material to prepare a castable, and the raw material mass percentage and experimental mixing method were the same as in Example 1. When the castable contained 10% water, it still did not have fluidity.

[0038] Refractory plastics were prepared using the used refractory material as a raw material, with the same raw material mass percentage and experimental mixing method as in Example 2. When 9% water was added, the mixture did not form clumps and did not have the properties for tamping or spreading.

[0039] Therefore, it can be concluded that used refractory materials with a soluble potassium content plus a soluble sodium content of 0.95% are difficult to reuse directly.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for evaluating the reuse performance of used refractory materials, characterized in that, include: For used refractory materials, the content of soluble potassium and soluble sodium in the used refractory materials is tested, and the reuse performance of the used refractory materials is judged based on the test results. When the content of soluble potassium is 0.24 wt% and the content of soluble sodium is 0.11 wt%, the used refractory material is determined to be usable as a raw material for preparing refractory castables; when the content of soluble potassium is 0.38 wt% and the content of soluble sodium is 0.26 wt%, the used refractory material is determined to be usable for preparing refractory plastics. The refractory castable is prepared from the following raw materials in the indicated mass percentages: The composition of the refractory material is 58%, 80% alumina 26%, Al2O3 micro powder 5%, silica micro powder 6%, pure calcium aluminate cement 5%, and dispersant 0.24%. The refractory plastic is prepared from the following raw materials in the indicated weight percentages: 52% used refractory material, 20% 80 alumina, 10% calcined bauxite powder, 8% refractory clay, 10% pure calcium aluminate cement, 0.2% sodium tripolyphosphate, and 0.15% sodium hexametaphosphate. The refractory material used after application is a high-alumina refractory material.

2. A method for reusing used refractory materials, characterized in that, include: For used refractory materials, the contents of soluble potassium and soluble sodium in the used refractory materials are tested. When the content of soluble potassium is 0.24 wt% and the content of soluble sodium is 0.11 wt%, the used refractory materials are used as raw materials to prepare refractory castables; when the content of soluble potassium is 0.38 wt% and the content of soluble sodium is 0.26 wt%, the used refractory materials are used to prepare refractory plastics. The refractory castable is prepared from the following raw materials in the indicated mass percentages: The composition of the refractory material is 58%, 80% alumina 26%, Al2O3 micro powder 5%, silica micro powder 6%, pure calcium aluminate cement 5%, and dispersant 0.24%. The refractory plastic is prepared from the following raw materials in the indicated weight percentages: 52% used refractory material, 20% 80 alumina, 10% calcined bauxite powder, 8% refractory clay, 10% pure calcium aluminate cement, 0.2% sodium tripolyphosphate, and 0.15% sodium hexametaphosphate. The refractory material used after application is a high-alumina refractory material.

3. The method according to claim 1 or 2, characterized in that, The contents of soluble potassium and soluble sodium were calculated using the following method: The potassium oxide and sodium oxide contents of the used refractory solid sample were measured. After water bath, filtration and soaking to obtain filter residue, the potassium oxide and sodium oxide contents of the filter residue were detected. The contents of soluble potassium and soluble sodium were calculated based on the potassium oxide and sodium oxide contents of the used refractory solid sample and the filter residue.

4. The method according to claim 3, characterized in that, The water bath includes water bath treatment at 35~50℃ for more than 24 hours.

5. The method according to claim 3, characterized in that, Both the used refractory material solid sample and the filter residue were processed to a particle size of less than 0.09 mm before testing.

6. The method according to claim 1 or 2, characterized in that, The concentrations of the soluble potassium and soluble sodium were determined using atomic absorption spectrometry, spectrophotometry, broadband ultraviolet absorption spectrometry, or flame photometry.

7. The application of the method of claim 1 in improving the reusability of refractory materials.