Modified immature soil material based on copper tailings and preparation method of modified immature soil material

Abstract

The invention discloses a modified raw soil material based on copper tailings and a preparation method thereof, and belongs to the technical field of building materials. The performance of a traditional raw soil material is optimized by using an alkali activator solution (prepared from a sodium hydroxide solution and a sodium silicate solution), copper tailings, sodium carboxymethyl cellulose, ceramic fragments and the like, and the reasonable adding amounts of the materials are as follows: 10% of copper tailings, 2% of sodium hydroxide, 4% of sodium silicate, 4% of sodium carboxymethyl cellulose, 4% of ceramic fragments and 0.6% of straw. The mechanical property, the water resistance and the like of the modified immature soil material are obviously improved, the copper tailings can be subjected to reduction, recycling and harmless utilization, the immature soil material has better regeneration value and environmental benefits, and the prepared immature soil material can be effectively applied to the fields of immature soil building reinforcement, cultural relic and ancient building restoration, civil engineering and the like.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a modified raw soil material based on copper tailings and its preparation method. Background Technology

[0002] Raw earth is a type of building material made primarily from unprocessed soil. It does not require firing and can usually be used in construction by simply mixing it with other materials. As one of the oldest building materials, raw earth is widely used around the world. However, raw earth has disadvantages such as poor mechanical properties and poor water resistance, which seriously affect the service life of raw earth buildings.

[0003] Copper tailings have small particle sizes and contain a certain amount of harmful heavy metals (such as lead and cadmium). When tailings are exposed in the open, these heavy metals can easily seep into the soil under rainy conditions, and cause dust pollution under dry conditions. In addition, tailings ponds occupy large areas of land, pollute soil and groundwater, and pose a potential threat of tailings dam collapse. How to reduce, recover, and harmlessly utilize copper tailings has become an urgent problem to be solved.

[0004] Therefore, utilizing copper tailings to modify raw soil can not only transform waste industrial materials into valuable building materials and realize the reuse of waste, but also help reduce environmental pollution and promote the sustainable development of the construction industry. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a modified raw soil material based on copper tailings and its preparation method.

[0006] In a first aspect, the present invention provides a modified raw soil material based on copper tailings, wherein the modified raw soil material is prepared by an alkaline activator solution and a mixed raw soil, wherein the mixed raw soil raw materials include undisturbed raw soil, copper tailings, sodium carboxymethyl cellulose, ceramic fragments and rice straw, and the alkaline activator solution raw materials include sodium hydroxide solution and sodium silicate solution.

[0007] Optionally, the moisture content of the undisturbed soil is 13%-23%, preferably 15%.

[0008] Optionally, in the modified raw soil material, the percentage content of each component is as follows: copper tailings 8%-12%, sodium hydroxide 1.8%-2.5%, sodium silicate 3.5%-4.3%, sodium carboxymethyl cellulose 3.8%-4.1%, ceramic fragments 3.6%-4.2%, rice straw 0.53%-0.65%, with the balance being undisturbed raw soil. All percentages are by mass, and the sum of the mass percentages of each component is 100%. The preferred mass percentages of each component in the modified raw soil material are: copper tailings preferably 10%, sodium hydroxide preferably 2%, sodium silicate preferably 4%, sodium carboxymethyl cellulose preferably 4%, ceramic fragments preferably 4%, rice straw preferably 0.6%, with the balance being undisturbed raw soil. Furthermore, the undisturbed raw soil, copper tailings, ceramic fragments, and rice straw are all commercially available products or industrial waste.

[0009] Optionally, the alkaline activator solution is prepared from a 45% sodium hydroxide solution and a 60% sodium silicate solution.

[0010] Optionally, the mass ratio of the alkali activator solution to the mixed raw soil is 0.056-0.073, preferably 0.064.

[0011] Optionally, the mass percentage content of each component in the copper tailings is as follows: silicon dioxide 40%-60%, alumina 5%-20%, iron oxide 5%-20%, copper 0.1%-2%, sulfur 1%-5%, and the remainder being permissible impurities with no impact. The preferred mass percentage of each component in the copper tailings is as follows: silicon dioxide preferably 55%, alumina preferably 17%, iron oxide preferably 14.7%, copper preferably 1.3%, and sulfur preferably 3%.

[0012] Optionally, the mass percentage of each component in the ceramic fragment is: 65%-75% silicon dioxide, 19%-25% aluminum oxide, and the remainder being permissible impurities with no impact. The preferred mass percentage of each component in the ceramic fragment is: preferably 72% silicon dioxide and preferably 23% aluminum oxide.

[0013] Optionally, the percentage content of each component in the straw is: cellulose 40%-49%, hemicellulose 23%-28%, wood ash 12%-16%, and the remainder are permissible impurities that have no effect. The preferred mass percentage of each component in the straw is: cellulose preferably 42%, hemicellulose preferably 25%, and wood ash preferably 14%.

[0014] Secondly, the present invention provides a method for preparing modified raw soil material based on copper tailings, for preparing the modified raw soil material described in any of the above-mentioned embodiments, comprising the following steps:

[0015] (1) Pretreatment of copper tailings: Grind the copper tailings, heat and mix them evenly, and cool them to obtain powdered copper tailings in order to fully activate the activity of copper tailings. The heating temperature is 100℃-110℃, and the preferred heating temperature is 105℃.

[0016] (2) Preparation of mixed raw soil and alkali activator: Weigh out raw soil, copper tailings (pretreated powdered copper tailings), sodium carboxymethyl cellulose, ceramic fragments, rice straw, sodium silicate and sodium hydroxide according to the following proportions: copper tailings 8%-12%, sodium hydroxide 1.8%-2.5%, sodium silicate 3.5%-4.3%, sodium carboxymethyl cellulose 3.8%-4.1%, ceramic fragments 3.6%-4.2%, rice straw 0.53%-0.65%, and the remainder is raw soil. All percentages mentioned above are by mass. Then mix the raw soil, copper tailings, sodium carboxymethyl cellulose, ceramic fragments and rice straw evenly to obtain mixed raw soil. Dissolve sodium silicate in water to prepare a 45% sodium silicate solution and dissolve sodium hydroxide in water to prepare a 60% sodium hydroxide solution. Then mix the sodium silicate solution and sodium hydroxide solution evenly and cool to obtain the alkali activator solution.

[0017] (3) Add the alkali activator solution to the mixed raw soil, stir and mix evenly, and press it into shape under a pressure of 13MPa-18MPa to obtain a specimen, wherein the pressure is preferably 16MPa, and the mass ratio of the alkali activator to the mixed raw soil is 0.056-0.073.

[0018] (4) The specimens are placed in a curing box and cured at a curing temperature of 50℃-70℃ for 25d-30d to obtain modified raw soil material. The curing temperature is preferably 60℃ and the curing days are preferably 28d.

[0019] The present invention has the following advantages:

[0020] (1) The raw soil specimen prepared by this invention, after 28 days of curing, has a compressive strength of 14.08 MPa, which is 2.64 times higher than that of the plain soil specimen. The water resistance index is 16.93, the thermal conductivity is 1.12, and the specimen has good integrity after destruction. It can improve both the compressive strength, water resistance, and thermal properties of raw soil materials, thus overcoming the shortcomings of traditional raw soil materials that are prone to brittle fracture.

[0021] (2) The modified raw earth material obtained by the formula disclosed in this invention can improve the seismic performance (28-day compressive strength is 2.64 times higher than that of the original raw earth) and environmental performance (thermal conductivity is 1.12, which is lower than the optimal mechanical performance of the specimen modified by only adding alkali activator - copper tailings) when used in raw earth buildings.

[0022] (3) The raw materials used in this invention are widely available and inexpensive, making it easy to mass-produce the products. They are green and environmentally friendly, and will not cause harm to the environment after use, thus enabling sustainable development. Attached Figure Description

[0023] Figure 1 shows the mechanical properties of undisturbed soil specimens at different moisture contents at 7d and 28d. Figure 1 includes Figure 1(a) and Figure 1(b), where Figure 1(a) is the compressive strength curve at 7d and 28d, and Figure 1(b) is the flexural strength curve at 7d and 28d.

[0024] Figure 2 shows the bar charts of mechanical properties of modified raw soil with different amounts of alkali activator solution and copper tailings at 7d and 28d. Figure 2 includes Figure 2(a) and Figure 2(b), where Figure 2(a) is the bar chart of compressive strength at 7d and 28d, and Figure 2(b) is the bar chart of flexural strength at 7d and 28d.

[0025] Figure 3 shows the compressive failure morphology of the raw soil specimen modified by alkali activator-copper tailings. Figure 3 includes Figure 3(a) and Figure 3(b), where Figure 3(a) shows the failure morphology at the initial loading stage and Figure 3(b) shows the failure morphology at the ultimate bearing capacity.

[0026] Figure 4 shows the mechanical properties of modified raw soil with different dosages of alkali activator, copper tailings, sodium carboxymethyl cellulose, ceramic fragments, and rice straw at 7 days and 28 days. Figure 4 includes Figure 4(a) and Figure 4(b), where Figure 4(a) is the bar chart of compressive strength of the modified specimen with comprehensive compound admixture, and Figure 4(b) is the bar chart of flexural strength of the modified specimen with comprehensive compound admixture.

[0027] Figure 5 shows the compressive failure morphology of modified raw soil specimens with alkali activator, copper tailings, sodium carboxymethyl cellulose, ceramic fragments, and rice straw as a composite admixture group. Figure 5 includes Figure 5(a) and Figure 5(b), where Figure 5(a) shows the failure morphology of the composite admixture group at the initial loading stage, and Figure 5(b) shows the failure morphology of the composite admixture group at the ultimate bearing capacity. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0029] In a first aspect, the present invention provides a modified raw soil material based on copper tailings, wherein the modified raw soil material is prepared by an alkaline activator solution and a mixed raw soil, wherein the mixed raw soil raw materials include undisturbed raw soil, copper tailings, sodium carboxymethyl cellulose, ceramic fragments and rice straw, and the alkaline activator solution raw materials include sodium hydroxide solution and sodium silicate solution.

[0030] Furthermore, the moisture content of the undisturbed soil is 13%-23%, preferably 15%.

[0031] Further, in the modified raw soil material, the percentage content of each component is as follows: copper tailings 8%-12%, sodium hydroxide 1.8%-2.5%, sodium silicate 3.5%-4.3%, sodium carboxymethyl cellulose 3.8%-4.1%, ceramic fragments 3.6%-4.2%, rice straw 0.53%-0.65%, and the balance is undisturbed raw soil. All percentages are mass percentages, and the sum of the mass percentages of each component is 100%. The preferred mass percentages of each component in the modified raw soil material are: copper tailings preferably 10%, sodium hydroxide preferably 2%, sodium silicate preferably 4%, sodium carboxymethyl cellulose preferably 4%, ceramic fragments preferably 4%, rice straw preferably 0.6%, and the balance is undisturbed raw soil.

[0032] Furthermore, the alkaline activator solution is prepared from a 45% sodium hydroxide solution and a 60% sodium silicate solution.

[0033] Furthermore, the mass ratio of the alkali activator solution to the mixed raw soil is 0.056-0.073, preferably 0.064.

[0034] Furthermore, the mass percentage content of each component in the copper tailings is as follows: silicon dioxide 40%-60%, alumina 5%-20%, iron oxide 5%-20%, copper 0.1%-2%, sulfur 1%-5%, and the remainder are permissible impurities with no impact. The preferred mass percentage of each component in the copper tailings is as follows: silicon dioxide preferably 55%, alumina preferably 17%, iron oxide preferably 14.7%, copper preferably 1.3%, and sulfur preferably 3%.

[0035] Furthermore, the mass percentage of each component in the ceramic fragment is: 65%-75% silicon dioxide, 19%-25% aluminum oxide, and the remainder is an acceptable impurity component with no impact. The preferred mass percentage of each component in the ceramic fragment is: preferably 72% silicon dioxide and preferably 23% aluminum oxide.

[0036] Furthermore, the percentage content of each component in the straw is as follows: cellulose 40%-49%, hemicellulose 23%-28%, wood ash 12%-16%, and the remainder are permissible impurities that have no effect. The preferred mass percentage of each component in the straw is as follows: cellulose is preferably 42%, hemicellulose is preferably 25%, and wood ash is preferably 14%.

[0037] Secondly, the present invention provides a method for preparing modified raw soil material based on copper tailings, for preparing the modified raw soil material described in any of the above-mentioned embodiments, comprising the following steps:

[0038] (1) Pretreatment of copper tailings: Grind the copper tailings, heat and mix them evenly, and cool them to obtain powdered copper tailings in order to fully activate the activity of copper tailings. The heating temperature is 100℃-110℃, and the preferred heating temperature is 105℃.

[0039] (2) Preparation of mixed raw soil and alkali activator: Weigh out raw soil, copper tailings (pretreated powdered copper tailings), sodium carboxymethyl cellulose, ceramic fragments, rice straw, sodium silicate and sodium hydroxide according to the following proportions: copper tailings 8%-12%, sodium hydroxide 1.8%-2.5%, sodium silicate 3.5%-4.3%, sodium carboxymethyl cellulose 3.8%-4.1%, ceramic fragments 3.6%-4.2%, rice straw 0.53%-0.65%, and the remainder is raw soil. All percentages mentioned above are by mass. Then mix the raw soil, copper tailings, sodium carboxymethyl cellulose, ceramic fragments and rice straw evenly to obtain mixed raw soil. Dissolve sodium silicate in water to prepare a sodium silicate solution with a mass concentration of 45%, and dissolve sodium hydroxide in water to prepare a sodium hydroxide solution with a mass concentration of 60%. Then mix the sodium silicate solution and sodium hydroxide solution evenly, cool, and obtain the alkali activator solution.

[0040] (3) Add the alkali activator solution to the mixed raw soil, stir and mix evenly, and press it into shape under a pressure of 13MPa-18MPa to obtain a specimen, wherein the pressure is preferably 16MPa, and the mass ratio of the alkali activator to the mixed raw soil is 0.056-0.073.

[0041] (4) Place the specimen in a curing box (the curing box is a commercially available conventional product) and prepare modified raw soil material at a curing temperature of 50℃-70℃ and a curing period of 25d-30d. The curing temperature is preferably 60℃ and the curing period is preferably 28d.

[0042] Example 1: Experimental group 1, undisturbed soil group (undisturbed soil is commercially available product or industrial waste), includes undisturbed soil specimens with moisture contents of 13%, 15%, 17%, 19%, 21%, and 23%. Figure 1 shows the mechanical property curves of undisturbed soil at different moisture contents after 7 days and 28 days. As can be seen from the figure, the optimum moisture content is 15%. At the optimum moisture content, the compressive strength of undisturbed soil at 7 days and 28 days is 3.95 MPa and 5.6 MPa, respectively, and the flexural strength at 7 days and 28 days is 0.59 MPa and 0.73 MPa, respectively.

[0043] Example 2: Experimental Group 2 (Alkali Activator-Copper Tailings Modification Group, including undisturbed raw soil (abbreviated as raw soil in the table), alkali activator (sodium hydroxide + sodium silicate), and copper tailings (copper tailings are commercially available products or industrial waste). A three-factor, three-level orthogonal design was used, where the three factors are copper tailings content (factor A), NaOH content (factor B), and Na2SiO3 (factor C). The three levels of factor A are: A1 = 5%, A2 = 10%, and A3 = 20%; the three levels of factor B are: B1 = 1%, B2 = 2%, and B3 = 4%; and the three levels of factor C are: C1 = 1%, C2 = 2%, and C3 = 4%. The proportions of the experimental admixtures are shown in Table 1. This example is named SCA.

[0044] Experimental group 2 consists of 9 examples, detailed in Table 1.

[0045] Table 1 Alkali Activator-Copper Tailings Mixing Ratio

[0046]

[0047] Figure 2 shows the bar charts of mechanical properties of modified virgin soil with different dosages of alkali activator and copper tailings at 7d and 28d. As can be seen from Figure 2, SCA5 has the best mechanical properties. As shown in Figure 2(a), its compressive strength at 7d and 28d is increased by 4.92MPa and 7.6MPa, respectively, compared with the virgin soil. As shown in Figure 2(b), its flexural strength at 7d and 28d is increased by 0.33MPa and 0.56MPa, respectively, compared with the virgin soil.

[0048] Figure 3 shows the compressive failure morphology of the modified raw soil specimen with alkali activator and copper tailings. During the initial pressurization process, no cracks appeared on the specimen surface. When the load approached the ultimate bearing capacity (Figure 3(a)), micro-cracks first appeared on both sides of the specimen, and a few small soil clumps fell off. As the pressure continued to increase, large pieces began to fall off on both sides, and cracks began to appear at the bottom of the specimen and quickly penetrated through it, reducing the specimen's bearing capacity and reaching the end-of-load condition. The raw soil specimen did not exhibit large-scale crushing during failure, and the compressive failure morphology was columnar (Figure 3(b)). The increased density of the modified soil increased the interparticle forces, and the hoop effect caused tensile stress in the weak central area of ​​the modified raw soil material, leading to cracking on both sides of the specimen.

[0049] The mean value ki (where i represents the various levels of the factor, such as 1, 2, and 3) obtained through range analysis can reveal the specific impact of different levels of each factor on the experimental index. A larger range R indicates a more significant impact of the factor on the experimental index. Table 2 shows the range analysis of compressive strength in orthogonal experiments. The order of importance of the factors affecting compressive strength at 7 days is as follows:

[0050] The order of factors influencing compressive strength at 28 days is: copper tailings > NaOH > Na2SiO3, and the optimal combination is A2B2C3.

[0051] Table 2. Analysis of the Range of Compressive Strength in Orthogonal Experiments

[0052]

[0053] Table 3 shows the range analysis of flexural strength. The order of influence of the factors affecting flexural strength at 7 days is copper tailings > NaOH > Na2SiO3, and the optimal combination scheme is A2B2C2. The order of influence of the factors affecting flexural strength at 28 days is NaOH > copper tailings > Na2SiO3, and the optimal combination scheme is A2B2C3.

[0054] Table 3. Analysis of the range of flexural strength

[0055]

[0056] The optimal mix design obtained through range analysis was experimentally verified. Based on the optimal mix ratio (10% copper tailings, 2% NaOH, 4% Na₂SiO₃) for 28-day compressive and flexural strengths, specimen SCA10 was prepared. The compressive and flexural strengths are shown in Table 4. Compared to the mechanically optimal orthogonal mix ratio SCA5, SCA10 exhibits higher 7-day, 28-day, and 28-day compressive and flexural strengths, indicating superior mechanical properties. Therefore, SCA10 is considered the optimal mix design for alkali-activated copper tailings modified soil.

[0057] Table 4 Mechanical Properties of SCA10

[0058]

[0059] Table 5 shows the results of immersion tests on undisturbed soil and alkali-activated copper tailings modified specimens. The table shows that the water resistance of the undisturbed soil modified with alkali-activated copper tailings is significantly improved. Among them, SCA2, SCA4, SCA5, SCA7, SCA8, and SCA10 show significant improvements in water resistance, with SCA4 having the highest water resistance index of 11.11.

[0060] Table 5. Immersion Test Results of Original Soil and Alkali-Activated Copper Tailings Modified Specimens

[0061]

[0062] Table 6 shows the thermal conductivity and thermal conductivity ratio of the alkali activator-copper tailings modified specimens. As can be seen from the table, there is no obvious pattern in the thermal conductivity compared to the undisturbed soil, but SCA4, SCA5, and SCA10 show significant increases, increasing by 37.1%, 46.7%, and 41.4%, respectively. The change in thermal conductivity is mainly due to the internal geopolymerization reaction, which produces geopolymer cementitious materials that bind the soil particles, increasing the density and macroscopically manifesting as an increase in thermal conductivity.

[0063] Table 6 Thermal properties of copper tailings modified with alkali activator

[0064]

[0065]

[0066] Example 3: To improve the thermal conductivity of alkali activator-copper tailings modified raw soil, we designed Experiment 3 based on the optimal ratio of Experiment 2.

[0067] Experimental group 3 (defined as the comprehensive compounding group, including virgin soil, alkali activator, copper tailings, sodium carboxymethyl cellulose, ceramic fragments, and rice straw, using a 3-factor, 3-level orthogonal design scheme, where the 3 factors are sodium carboxymethyl cellulose content (factor E), ceramic fragment content (factor G), and rice straw content (factor H), with the 3 levels of factor E being E1 = 2%, E2 = 3%, and E3 = 4%, the 3 levels of factor G being G1 = 4%, G2 = 6%, and G3 = 8%, and the 3 levels of factor H being H1 = 0.4%, H2 = 0.6%, and H3 = 0.8%, and the example was named F)

[0068] Experimental group 3 consists of 9 examples, detailed in Table 7.

[0069] Table 7. Mixing Proportions for Comprehensive Modification and Blending of Solid Waste

[0070]

[0071] Figure 4 shows the compressive and flexural strengths of the composite modified specimens. As shown in Figure 4(a), the 28-day compressive strength of the composite modified group F7 is the highest, reaching 14.08 MPa, which is 2.64 times higher than that of the plain soil specimen. As shown in Figure 4(b), the 7-day flexural strength of the composite modified groups is higher than that of the optimal working condition SCA10 for alkali activator-copper tailings modification. Among them, F4 and F7 reach the maximum of 1.25 MPa, which is 111.9% higher than that of the original soil and 35.9% higher than that of SCA10. Except for the composite modified group F1, the 28-day flexural strength of all other groups is higher than that of SCA10, with F4 reaching the highest of 1.48 MPa.

[0072] Figure 5 shows the failure morphology of specimen F7 from the solid waste composite admixture group under pressure after 28 days. During the initial pressurization process, no cracks appeared on the specimen surface. When the load approached the ultimate bearing capacity (Figure 5(a)), vertical cracks first appeared at the bottom of the specimen. As the pressure continued to increase, the cracks extended upwards and developed into diagonal cracks, eventually reaching the ultimate bearing capacity before loading ceased. After removing the loose soil clumps, the main body of the specimen after failure was exposed; its main body was relatively intact and hourglass-shaped (Figure 5(b)).

[0073] The range analysis of compressive strength in orthogonal experiments is shown in Table 8. The mean value ki obtained through range analysis (where i represents the various levels of the factor, such as 1, 2, and 3) reveals the specific impact of different levels of each factor on the experimental indicators. A larger range R indicates a more significant impact of the factor on the experimental indicators. The table shows that the order of influence of factors on 7-day compressive strength is: sodium carboxymethyl cellulose > ceramic fragments > straw. With increasing sodium carboxymethyl cellulose content, the 7-day compressive strength of the modified specimen increases, and the optimal combination is E3G2H3. For 28-day compressive strength, the order of influence of factors is: sodium carboxymethyl cellulose > ceramic fragments > straw, and the optimal combination is E3G1H2.

[0074] Table 8. Analysis of the Range of Compressive Strength

[0075]

[0076] The range analysis of flexural strength in orthogonal experiments is shown in Table 9. The order of influencing factors on flexural strength at 7 days is: sodium carboxymethyl cellulose > rice straw > ceramic fragments, with the optimal combination being E3G2H3. At 28 days, the order of influencing factors on flexural strength is: rice straw > sodium carboxymethyl cellulose > ceramic fragments, with the optimal combination being E2G1H3.

[0077] Table 9. Analysis of the Range of Flexural Strength

[0078]

[0079] According to the orthogonal analysis, the optimal working condition for compressive strength is E3G1H2 (i.e., F7) and the optimal working condition for flexural strength is E2G1H3 (i.e., F4). The 28-day flexural strengths of F4 and F7 are similar, while the compressive strength of F7 is significantly higher than that of F4. Therefore, F7 is selected as the optimal working condition for mechanical strength.

[0080] Table 10 shows the results of the immersion test of the composite group. It can be clearly seen that the water resistance of the composite group is significantly improved. The incorporation of sodium carboxymethyl cellulose has made a great contribution. From the perspective of water resistance, the content of carboxymethyl cellulose is better at 3% than at 4%, and 2% is the worst. The water resistance index of the group with the best mechanical properties, F7, is 16.93.

[0081] Table 10 Results of Immersion Tests for the Composite Blend Group

[0082]

[0083] Table 11 shows the thermal parameters of the composite blend groups. As can be seen from the table, the thermal conductivity of the composite modified groups, which incorporate sodium carboxymethyl cellulose, ceramic fragments, and straw into SCA10, is reduced. Except for F4 and F7, the thermal conductivity of the composite modified groups is lower than that of the undisturbed soil. The thermal conductivity of F4 and F7 is also lower than that of SCA10, which has the best mechanical properties when modified only with alkali activator-copper tailings. The thermal conductivity of the group with the best mechanical properties, F7, is 1.12.

[0084] Table 11 Thermal parameters of the composite blend group

[0085]

[0086] Experimental group 2 showed that the mechanical properties of the modified raw soil with activator and copper tailings were significantly improved. Range analysis revealed the optimal mix ratio to be 10% copper tailings, 2% NaOH, and 4% Na₂SiO₃. Compared to the undisturbed soil, the 28-day compressive strength and flexural strength increased by 7.6 MPa and 0.56 MPa, respectively. Furthermore, the incorporation of alkali activator and copper tailings significantly improved the water resistance of the raw soil material, with SCA2, SCA4, and SCA5 exhibiting water resistance times exceeding 1 hour. However, under certain operating conditions in the alkali activator-modified group, the thermal conductivity of the raw soil increased, resulting in poorer thermal insulation performance.

[0087] As seen in Experiment 3, adding 4% sodium carboxymethyl cellulose, 4% ceramic fragments, and 0.6% rice straw to the optimal mix ratio of 10% copper tailings, 2% sodium hydroxide, and 4% sodium silicate in Experiment 1 significantly improved the compressive and flexural strength, increased the water resistance index, decreased the thermal conductivity, and significantly enhanced the overall performance of the modified raw soil. Considering mechanical properties, water resistance, and thermal properties, the optimal mix ratio for the modified raw soil is: 10% copper tailings, 2% sodium hydroxide, 4% sodium silicate, 4% sodium carboxymethyl cellulose, 4% ceramic fragments, and 0.6% rice straw. All percentages are by mass.

[0088] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included within the scope of the technical solution of the present invention.

Claims

1. A modified raw soil material based on copper tailings, characterized in that: The modified raw soil material is prepared from an alkali activator solution and mixed raw soil. The mixed raw soil raw materials include undisturbed raw soil, copper tailings, sodium carboxymethyl cellulose, ceramic fragments, and rice straw. The alkali activator solution raw materials include sodium hydroxide solution and sodium silicate solution.

2. The modified raw soil material based on copper tailings according to claim 1, characterized in that, The moisture content of the original soil is 13%-23%.

3. The modified raw soil material based on copper tailings according to claim 1, characterized in that, The modified raw soil material contains the following percentages of each component: copper tailings 8%-12%, sodium hydroxide 1.8%-2.5%, sodium silicate 3.5%-4.3%, sodium carboxymethyl cellulose 3.8%-4.1%, ceramic fragments 3.6%-4.2%, rice straw 0.53%-0.65%, with the remainder being undisturbed raw soil. All percentages are by mass.

4. The modified raw soil material based on copper tailings according to claim 1, characterized in that, The alkaline activator solution is prepared from a 45% sodium hydroxide solution and a 60% sodium silicate solution.

5. The modified raw soil material based on copper tailings according to claim 1, characterized in that: The mass ratio of the alkali activator solution to the mixed raw soil is 0.056-0.

073.

6. The modified raw soil material based on copper tailings according to claim 1, characterized in that, The mass percentage content of each component in the copper tailings is as follows: silicon dioxide 40%-60%, aluminum oxide 5%-20%, iron oxide 5%-20%, copper 0.1%-2%, and sulfur 1%-5%.

7. The modified raw soil material based on copper tailings according to claim 1, characterized in that, The mass percentage content of each component in the ceramic fragment is: silicon dioxide 65%-75%, aluminum oxide 19%-25%.

8. The modified raw soil material based on copper tailings according to claim 1, characterized in that, The mass percentage content of each component in the straw is as follows: cellulose 40%-49%, hemicellulose 23%-28%, and wood ash 12%-16%.

9. A method for preparing modified raw soil material based on copper tailings according to any one of claims 1-8, characterized in that, Includes the following steps: (1) Pretreatment of copper tailings: Grind the copper tailings, heat and mix them evenly, and cool them to obtain powdered copper tailings, wherein the heating temperature is 100℃-110℃. (2) Preparation of mixed raw soil and alkali activator solution: Weigh out raw soil, copper tailings, sodium carboxymethyl cellulose, ceramic fragments, rice straw, sodium silicate and sodium hydroxide according to the proportion. Mix the raw soil, copper tailings, sodium carboxymethyl cellulose, ceramic fragments and rice straw evenly to obtain mixed raw soil. Dissolve sodium silicate in water to prepare sodium silicate solution, and then dissolve sodium hydroxide in water to prepare sodium hydroxide solution. Then mix the sodium silicate solution and sodium hydroxide solution evenly, cool, and obtain alkali activator solution. (3) Add the alkali activator solution to the mixed raw soil, stir and mix evenly, and press it into shape under a pressure of 13MPa-18MPa to obtain the specimen; (4) The specimens were placed in a curing chamber and the modified raw soil material was prepared at a curing temperature of 50℃-70℃ and a curing period of 25d-30d.

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