Evaluation method for recycling performance of used refractory material

Abstract

The invention relates to the field of refractory materials, in particular to a method for evaluating the recycling performance of a used refractory material. The evaluation method comprises the following steps: detecting the content of soluble potassium and soluble sodium in the used refractory material for the used refractory material, and judging the reutilization performance of the used refractory material according to a detection result, when the sum of the contents of the soluble potassium and the soluble sodium is less than 0.4 wt%, judging that the used refractory material can be used as a raw material for preparing a refractory castable; and when the sum of the contents of the soluble potassium and the soluble sodium is 0.4-0.8 wt%, judging that the used refractory material can be used for preparing the refractory plastic material. The invention provides a method for simply, conveniently and efficiently evaluating the application and quality level of the used refractory material, and the method has important application value in the field of refractory material reutilization.

Description

Technical Field

[0001] The present invention relates to the field of refractory materials, in particular to a method for evaluating the reusability of used refractory materials. Background Art

[0002] As a non-renewable geological mineral resource, bauxite has shown a clear decline in reserves and quality after years of industrial mining. Due to the fundamental role of aluminum-based refractories in fields such as metallurgy and building materials, a significant contradiction is emerging between the raw material supply system and the needs of industrial development. Especially against the backdrop of expanding industry scale and accelerating product iteration, resource constraints continue to intensify. At the same time, fluctuations in the supply of raw bauxite ore often lead to drastic price fluctuations. This instability is directly transmitted to the refractory manufacturing process, significantly affecting the overall cost of the product.

[0003] In this case, the rational reuse of used refractory materials shows multiple values: from the resource dimension, it can effectively fill the gap in the raw material supply chain; at the economic level, it can smooth the impact of raw material price fluctuations on corporate 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] In order to solve the problems existing in the prior art, the present 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 reusability of used refractory materials, comprising: For the used refractory material, detecting the content of soluble potassium and soluble sodium in the used refractory material, and judging the recyclability of the used refractory material according to the detection results; When the sum of the contents of soluble potassium and soluble sodium is less than 0.4wt%, it is judged that the used refractory material can be used as a raw material for preparing refractory castables; when the sum of the contents of soluble potassium and soluble sodium is between 0.4~0.8wt%, it is judged that the used refractory material can be used to prepare refractory plastics.

[0006] The present invention is based on a large number of experimental studies and finds that the content of soluble potassium and sodium has a great influence on the amount of water added, fluidity and hardening time of monolithic refractory materials. Therefore, the soluble potassium and soluble sodium contents of the used refractory materials can be tested to determine whether the used refractory materials can be directly reused or need further performance evaluation.

[0007] In a second aspect, the present invention provides a method for recycling used refractory materials, comprising: For used refractory materials, the contents of soluble potassium and soluble sodium in the used refractory materials are detected. When the sum of the contents of soluble potassium and soluble sodium is less than 0.4wt%, 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 0.8wt%, the used refractory materials are used to prepare refractory plastics.

[0008] Furthermore, when the sum of the contents of soluble potassium and soluble sodium exceeds 0.8 wt %, further evaluation is required before use.

[0009] Furthermore, the contents of soluble potassium and soluble sodium are calculated by the following method: The potassium oxide and sodium oxide contents of the used refractory solid sample are measured, and a filter residue is obtained by water bathing and filtering, and the potassium oxide and sodium oxide contents of the filter residue are detected; and the soluble potassium and soluble sodium contents are calculated based on the potassium oxide and sodium oxide contents of the used refractory solid sample and the potassium oxide and sodium oxide contents of the filter residue.

[0010] Furthermore, the water bath comprises: water bath treatment at 35-50° C. for more than 24 hours.

[0011] Furthermore, the used refractory solid sample and the filter residue are processed to a particle size of less than 0.09 mm and then tested.

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

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

[0014] Furthermore, the soluble potassium and soluble sodium contents are measured by flame photometry to detect the contents of potassium oxide and sodium oxide, and the contents of soluble potassium and soluble sodium are converted according to the contents of potassium oxide and sodium oxide.

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

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

[0017] Furthermore, the mixing is performed by stirring pre-mixing for 1-2 minutes, followed by adding water and wet mixing for 2-3 minutes. The water content of the castable is 6-8%, and the castable is removed from the pot after it has satisfactory workability. The castable has a flow value of 120-150 mm after removing from the pot and a flow value of 115-145 mm after 15 minutes of addition of water.

[0018] Furthermore, the preparation method of the refractory plastic material comprises: The used refractory material is mixed with 80 bauxite, coke gemstone powder, refractory clay, pure calcium aluminate cement and an admixture to prepare a plastic material.

[0019] Furthermore, the mixing is performed by stirring pre-mixing for 1-2 minutes, then adding water and wet mixing for 3-5 minutes; and the plastic is removed from the pot when it has satisfactory construction performance. The amount of water added to the plastic is 7-8.5%, and the curing time is 7-9 hours.

[0020] In a third aspect, the present invention provides an application of the aforementioned method in improving the recycling rate of refractory materials.

[0021] The present invention has the following beneficial effects: Research conducted in the present invention has found that the content of soluble sodium and soluble potassium significantly affects the water addition, fluidity, and hardening time of used refractory materials, and can largely reflect the performance of used refractory materials. Therefore, the soluble sodium and soluble potassium content can be used to evaluate whether used refractory materials can be directly reused.

[0022] The method provided by the present invention can effectively improve the recycling rate of refractory materials, effectively reduce the production costs of enterprises, and has significant economic value. DETAILED DESCRIPTION

[0023] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0024] Unless otherwise specified, the experimental methods involved in the following examples are all conventional methods in the art. For example, reference can be made to experimental manuals in the art, or the conditions recommended by the manufacturer's instructions.

[0025] Unless otherwise specified, the experimental materials and reagents involved in the following examples can be obtained from commercial sources.

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

[0027] (2) Sample I was heated in a 40°C water bath with 500 ml of distilled water for 24 h, magnetically stirred for 10 min, and then filtered. The residue was then soaked in 500 ml of distilled water and magnetically stirred for 10 min, then filtered. This process was repeated three times. The resulting residue was dried at 110°C for 24 h and processed into Sample III with a particle size of less than 0.09 mm.

[0028] (3) Use flame photometry to detect the potassium oxide and sodium oxide contents of sample II and the potassium oxide and sodium oxide contents of sample III.

[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 post-use refractory material from the throat of a grate cooler at a cement plant was tested according to the aforementioned method, revealing a soluble potassium content (calculated as K₂O) of 0.24% and a soluble sodium content (calculated as Na₂O) of 0.11%. This post-use refractory material was used as raw material to prepare a castable, consisting of the following raw materials by weight: 58% post-use refractory material, 26% 80-grade alumina, 5% Al₂O₃ fine powder, 6% silica fume, 5% pure calcium aluminate cement, and 0.24% dispersant. The aggregate, powder, binder, and admixtures were premixed in a forced mixer for 1-2 minutes. An appropriate amount of water was then added and wet-mixed for 2-3 minutes. The castable was then released from the pot after achieving good workability. The water content of the castable was 6.8%, resulting in a flow value of 135mm out of the pot and a flow value of 130mm after 15 minutes. The curing time was 6 hours.

[0031] The performance test of the castable was carried out, and the test results were as follows: bulk density 2.64g / cm 3 The compressive strength at 110°C × 24h and 1100°C × 3h was 110 MPa and 122 MPa respectively, the flexural strength at 110°C × 24h and 1100°C × 3h was 15.2 MPa and 16.5 MPa respectively, the thermal shock stability (1100°C, water cooling) was greater than 15 times, and the alkali resistance was Class 1. These test results indicate that the castable is a qualified product.

[0032] Example 2 A high-alumina refractory material was used in the kiln hood of a cement plant. A 10 kg sample was taken and tested according to the above embodiment (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] This used refractory material is used as raw material to prepare a refractory plastic. The material is prepared with the following percentages by weight: 52% used refractory material, 20% 80 alumina, 10% pyrotechnic powder, 8% refractory clay, 10% pure calcium aluminate cement, 0.2% sodium tripolyphosphate, and 0.15% sodium hexametaphosphate. The aggregate, powder, binder, and admixtures are premixed in a forced mixer for 1-2 minutes. An appropriate amount of water is then added and wet-mixed for 3-5 minutes. The material is stirred into a mass and removed from the pan when it exhibits good workability. The water addition rate is 7.5%, and the curing time is 8 hours.

[0034] The performance test of the plastic was carried out, and the test results were as follows: volume density 2.60g / cm 3 , 110℃×24h and 1100℃×3h compressive strength are 106MPa and 119MPa respectively, 110℃×24h and 1100℃×3h flexural strength are 12.2MPa and 13.7MPa respectively, wear resistance value (1100℃×3h) 4.8cm 3 .

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

[0036] Example 3 A 10 kg sample of high-alumina refractory material used in the decomposition furnace at the kiln tail of a cement plant was taken and tested according to the above embodiment (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 those in Example 1. When 10% water was added to the castable, it still did not have fluidity.

[0038] The used refractory material was used as a raw material to prepare a refractory plastic material, and the raw material mass percentage and experimental mixing method were the same as those in Example 2. When the water content was 9%, the mixture did not form a lump and did not have the construction properties of ramming or smearing.

[0039] It can be concluded that used refractory materials with soluble potassium content + soluble sodium content = 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, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for evaluating the reusability of used refractory materials, characterized in that: include: For the used refractory material, detecting the content of soluble potassium and soluble sodium in the used refractory material, and judging the recyclability of the used refractory material according to the detection results; When the sum of the contents of soluble potassium and soluble sodium is less than 0.4wt%, it is judged that the used refractory material can be used as a raw material for preparing refractory castables; when the sum of the contents of soluble potassium and soluble sodium is between 0.4~0.8wt%, it is judged that the used refractory material can be used to prepare refractory plastics.

2. A method for recycling 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 detected. When the sum of the contents of soluble potassium and soluble sodium is less than 0.4wt%, 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 0.8wt%, the used refractory materials are used to prepare refractory plastics.

3. The method according to claim 1 or 2, characterized in that The contents of soluble potassium and soluble sodium are calculated by the following method: The potassium oxide and sodium oxide contents of the used refractory solid sample are measured, and a filter residue is obtained after water bathing, filtering and soaking to retain the residue, and the potassium oxide and sodium oxide contents of the filter residue are detected; the soluble potassium and soluble sodium contents are calculated based on the potassium oxide and sodium oxide contents of the used refractory solid sample and the potassium oxide and sodium oxide contents of the filter residue.

4. The method according to claim 3, characterized in that The water bath comprises: water bath treatment at 35-50° C. for more than 24 hours.

5. The method according to claim 3 or 4, characterized in that The used refractory solid sample and the filter residue are processed to a particle size of less than 0.09 mm and then tested.

6. The method according to any one of claims 1 to 5, characterized in that The concentrations of the soluble potassium and soluble sodium are detected by atomic absorption spectroscopy, spectrophotometry, broadband ultraviolet absorption spectroscopy or flame photometry, preferably flame photometry.

7. The method according to any one of claims 1 to 6, characterized in that The used refractory material is a high-alumina refractory material.

8. The method according to claim 1 or 2, characterized in that The preparation method of the refractory castable comprises: The used refractory material is mixed with 80 bauxite, silica powder, alumina, pure calcium aluminate cement and a dispersant to prepare a castable.

9. The method according to claim 1 or 2, characterized in that The preparation method of the refractory plastic material comprises: The used refractory material is mixed with 80 bauxite, coke gemstone powder, refractory clay, pure calcium aluminate cement and an admixture to prepare a plastic material.

10. Use of the method according to claim 1 in improving the recycling rate of refractory materials.