Tailing-based soil improvement water permeable brick and preparation method thereof

Abstract

The invention provides a tailing-based soil improvement water permeable brick and a preparation method thereof, and relates to the field of solid waste recycling. The tailing-based soil improvement water permeable brick comprises a surface layer and a base layer, the base layer comprises a core layer and a shell layer arranged on the surface of the core layer; the surface layer comprises the following raw materials: tailings, cement, a binder solution, pigment and water in a mass ratio of (60-80): (33-72): (4-26): (2-12): (7-16); the shell layer comprises the following raw materials: tailings, cement, a binder solution, an adsorbent and water in a mass ratio of (60-80): (36-76): (5-30): (20-30): (8-18); the core layer comprises the following raw materials: tailings, potassium feldspar, a transforming agent, a binder solution, cement and water in a mass ratio of (60-80): (20-40): (50-80): (7-40): (19-48): (10-24). The tailing-based soil improvement water permeable brick has the characteristic of lasting improvement effect, and can be widely applied to the fields of soil remediation, garden construction, urban landscaping and the like.

Description

Technical Field

[0001] The present application relates to the field of solid waste recycling, and in particular to a tailings-based soil improved permeable brick and a preparation method thereof. Background Art

[0002] Tailings, as solid waste from the mineral processing industry, are one of the world's largest sources of industrial solid waste. The preparation of building materials from tailings is an important direction of the comprehensive utilization of tailings. It not only solves the problem of tailings disposal, alleviates the environmental risks and safety hazards brought by tailings storage, but also promotes resource recycling and achieves sustainable development.

[0003] Permeable bricks are a kind of building material with good water permeability. They can make the accumulated water after rainfall quickly infiltrate through the pores, reduce surface runoff, and are widely used in the construction of sponge cities, effectively alleviating the problem of urban waterlogging after heavy rains. In recent years, the research on the preparation of permeable bricks from tailings has attracted the attention of scholars.

[0004] At present, permeable brick products prepared from tailings are still mainly used as basic building materials such as decoration and load-bearing, with a single application scenario and low product added value. Compared with permeable brick products prepared from conventional raw materials, they have no performance advantages. At the same time, with the decline of the real estate industry, the market demand for building bricks and tiles is low, resulting in a narrowing sales radius, compressed profit margins and deteriorating market prospects for permeable brick products prepared from tailings raw materials. There is an urgent need to enrich the functionality of tailings-based permeable brick products, increase product added value, and thereby expand market sales.

[0005] Tailings contain valuable elements such as Si, Ca, Mg, K, P, and Fe. After processing, they have the functions of promoting plant growth, improving acidic soil, and regulating heavy metal pollution. If we can give full play to its own endowment advantages while preparing permeable bricks from tailings and make full use of the valuable elements in them to improve the soil environment, the functions of tailings-based permeable bricks can be further enriched.

[0006] Based on this, there is an urgent need to provide a technical solution that fully utilizes the advantages of tailings endowment and improves the added value and functionality of tailings-based permeable brick products. Summary of the invention

[0007] The purpose of this application is to provide a tailings-based soil improved permeable brick and a preparation method thereof to solve the above-mentioned problems.

[0008] To achieve the above objectives, the present application provides, in a first aspect, a tailings-based soil improved permeable brick, comprising a surface layer and a base layer; The base layer comprises a core layer and a shell layer arranged on the surface of the core layer; The raw materials of the surface layer include tailings, cement, binder solution, pigment and water in a mass ratio of 60-80:33-72:4-26:2-12:7-16; The raw materials of the shell layer include tailings, cement, binder solution, adsorbent and water in a mass ratio of 60-80:36-76:5-30:20-30:8-18; The raw materials of the core layer include tailings, potassium feldspar, a conversion agent, a binder solution, cement and water in a mass ratio of 60-80:20-40:50-80:7-40:19-48:10-24.

[0009] Optionally, the tailings-based soil improvement permeable brick meets at least one of the following conditions: A. the adsorbent comprises one or more of rice husk charcoal, attapulgite and humic acid; B. the conversion agent comprises one or more of calcium carbonate, desulfurized gypsum and dolomite; C. The binder solution includes one or more of a sodium lignin sulfonate aqueous solution, a calcium lignin sulfonate aqueous solution, an ammonium chloride aqueous solution and a sodium carboxymethyl cellulose aqueous solution.

[0010] Optionally, the tailings-based soil improvement permeable brick meets at least one of the following conditions: A. The adsorbent comprises the rice husk charcoal, the attapulgite and the humic acid, wherein the mass ratio of the rice husk charcoal, the attapulgite and the humic acid is 60-80:20-40:0-10; B. The conversion agent comprises the calcium carbonate, the desulfurized gypsum and the dolomite, wherein the mass ratio of the calcium carbonate, the desulfurized gypsum and the dolomite is 50-60:20-30:20-30.

[0011] C. The binder solution includes one or more of the sodium lignin sulfonate aqueous solution, the calcium lignin sulfonate aqueous solution, the ammonium chloride aqueous solution and the sodium carboxymethyl cellulose aqueous solution, wherein the solution concentration is 5%-10%.

[0012] Optionally, the SiO in the tailings 2 The content of K is greater than 30%, 2 O content is greater than 5%, Cr content is less than 250 mg / kg, Cd content is less than 20 mg / kg, Pb content is less than 400 mg / kg, As content is less than 100 mg / kg, Hg content is less than 10 mg / kg, and Tl content is less than 5 mg / kg.

[0013] Optionally, the particle sizes of the pigment, the tailings, the cement, the potassium feldspar and the conversion agent are each independently less than or equal to 0.074 mm.

[0014] The second aspect of the present application provides a method for preparing the tailings-based soil improved permeable brick, comprising: Mixing the tailings and cement to obtain a first homogenized raw material and a second homogenized raw material; The first homogenized raw material and the adsorbent are first granulated, wherein the adsorbent is disposed on the surface of the first homogenized raw material, and then first cured to obtain a shell material; The second homogenized raw material and the pigment are subjected to a second granulation, wherein the pigment is disposed on the surface of the second homogenized raw material, and then subjected to a second curing to obtain a surface layer material; The tailings, potassium feldspar and conversion agent are mixed, and the third granulation and roasting are performed to obtain the core layer material; Mixing cement and water to obtain cement slurry, and mixing the core layer material, the shell layer material and the surface layer material with the cement slurry respectively to obtain a core layer material-cement slurry mixture, a shell layer material-cement slurry mixture and a surface layer material-cement slurry mixture; The core layer material-cement slurry mixture, the shell layer material-cement slurry mixture and the surface layer material-cement slurry mixture are sequentially stacked and formed in a mold, and a third curing is performed to obtain tailings-based soil improved permeable bricks; When the first granulation, the second granulation and the third granulation are performed, a binder solution is also sprayed.

[0015] Optionally, the method for preparing the tailings-based soil improved permeable brick meets at least one of the following conditions: A. The disc speeds of the first granulation, the second granulation and the third granulation are independently 20 r / min-40 r / min, and the granulation time is independently 5 min-10 min; B. The time of the first curing and the second curing is independently 12h-24h; C. The calcination temperature is 1100°C-1200°C and the calcination time is 30min-60min; D. The third curing period shall not be less than 28 days.

[0016] Optionally, the particle size of the shell material is 8mm-10mm; The particle size of the surface layer material is 1mm-3mm; The particle size of the core layer material is 3mm-5mm.

[0017] Optionally, the method for preparing the tailings-based soil improved permeable brick meets at least one of the following conditions: A. When preparing the homogenized raw material, the mass ratio of the tailings to the cement is 60-80:20-40; B. When preparing the shell material-cement slurry mixture, the mass ratio of the shell material, the cement and the water is 100:15-20:8-10; C. When preparing the core material-cement slurry mixture, the mass ratio of the core material, the cement and the water is 100:15-20:8-10; D. When preparing the surface material-cement slurry mixture, the mass ratio of the surface material, the cement and the water is 100:15-20:8-10.

[0018] Optionally, the sequentially stacking and forming in a mold includes: First, spread the shell material-cement slurry mixture all over the bottom and four walls of the mold, then fill the core layer material-cement slurry mixture into it, and then lay the shell material-cement slurry mixture and the surface material-cement slurry mixture in sequence on the core layer material-cement slurry mixture.

[0019] Compared with the prior art, the beneficial effects of this application include: The tailings-based soil improvement permeable bricks provided in the present application, while having the excellent mechanical properties and permeability of traditional building materials permeable bricks, use tailings building materials products in the field of soil improvement, further tapping the advantages of tailings in natural endowment characteristics, and have the functions of providing nutrients, improving acidic soil and fixing heavy metals, and through the "surface layer-shell layer-core layer" structure, the slow release of valuable components is achieved, and the improvement effect is long-lasting. It can be widely used in soil remediation, garden construction, urban greening and other fields.

[0020] The present application provides a method for preparing tailings-based soil-improved permeable bricks, and core layer materials, shell layer materials and surface layer materials with various functions are prepared: the core layer material contains a certain amount of effective silicon, effective potassium, effective calcium and effective magnesium elements that can be absorbed by plants, which can be slowly released under soil environment and long-term water immersion conditions, and play a role in supplementing soil nutrients and increasing the pH value of acidic soil; the shell layer material has a filler composed of cement and tailings inside, which plays a role as a skeleton, and the adsorbent on the surface gradually falls off in water immersion and soil environment, and plays a role in adsorbing heavy metals in the soil. At the same time, the shell layer material avoids direct contact between the core layer material and the surrounding environment, reduces the release rate of valuable elements, effectively prolongs the duration of soil improvement, and improves the utilization rate of valuable elements; pigments are added to the surface layer material during the preparation process, so the surface layer can also play a decorative role. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope of the present application.

[0022] Figure 1 Schematic diagram of the structure of permeable bricks for tailings-based soil improvement; Figure 2This is a physical picture of the tailings-based soil improved permeable brick prepared in Example 1; Figure 3 This is a physical picture of the shell material prepared in Example 1; Figure 4 This is a physical picture of the surface material prepared in Example 1; Figure 5 This is a physical picture of the core layer material prepared in Example 1; Figure 6 A schematic flow chart of the method for preparing tailings-based soil-improved permeable bricks provided in Example 1. DETAILED DESCRIPTION

[0023] As used herein: "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0024] The conjunction "consisting of excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed-ended so that it does not include materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0025] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described in this article, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0026] In these examples, parts and percentages are by mass unless otherwise indicated.

[0027] "Mass parts" refers to the basic unit of measurement for expressing the mass ratio of multiple components. 1 part can represent any unit mass, such as 1g or 2.689g. If we say that the mass parts of component A are a parts and the mass parts of component B are b parts, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it means that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number, indicating a multiple factor). It should not be misunderstood that, unlike the mass parts, the sum of the mass parts of all components is not limited to 100 parts.

[0028] "And / or" is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0029] In a first aspect, the present application provides a tailings-based soil improved permeable brick, comprising a surface layer and a base layer; The base layer comprises a core layer and a shell layer arranged on the surface of the core layer; It should be noted that the structure of the tailings-based soil improvement permeable brick is as follows: Figure 1 As shown, the shell layer completely covers the core layer, avoiding direct contact between the core layer and the surrounding environment; illustratively, the core layer in the cross-section of the tailings-based soil improved permeable brick can be any shape such as square, rectangular, circular, etc., and the shell layer can be set according to the shape of the core layer or actual conditions; in some embodiments, the thickness ratio of the surface layer, the core layer and the shell layer is 5-20:30-50:30-70, but the thickness ratio of the surface layer, the core layer and the shell layer can be set according to actual needs.

[0030] The raw materials of the surface layer include tailings, cement, binder solution, pigment and water in a mass ratio of 60-80:33-72:4-26:2-12:7-16; Optionally, the mass ratio of tailings, cement, binder solution, pigment and water in the surface layer raw material can be 60:33:4:2:7, 70:33:4:2:7, 80:33:4:2:7, 60:50:4:2:7, 60:72:4:2:7, 60:33:10:2:7, 60:33:26:2:7, 60:33:4:12:7, 60:33:4:2:16 or any value between 60-80:33-72:4-26:2-12:7-16; The raw materials of the shell layer include tailings, cement, binder solution, adsorbent and water in a mass ratio of 60-80:36-76:5-30:20-30:8-18; Optionally, the mass ratio of tailings, cement, binder solution, adsorbent and water in the shell raw material can be 60:36:5:20:8, 70:36:5:20:8, 80:36:5:20:8, 60:72:5:20:8, 60:36:30:30:18 or any value between 60-80:36-76:5-30:20-30:8-18; The raw materials of the core layer include tailings, potassium feldspar, conversion agent, binder solution, cement and water in a mass ratio of 60-80:20-40:50-80:7-40:19-48:10-24.

[0031] Optionally, the mass ratio of tailings, potassium feldspar, conversion agent, binder solution, cement and water in the core layer raw material can be 60:20:50:7:19:10, 70:20:50:7:19:10, 80:20:50:7:19:10, 60:30:50:7:19:10, 60:40:50:7:19:10, 60:20:70:7:19:10, 60: 20:80:7:19:10, 60:20:50:20:19:10, 60:20:50:40:19:10, 60:20:50:7:48:10, 60:20:50:7:19:24, 80:40:80:40:48:24 or any value between 60-80:20-40:50-80:7-40:19-48:10-24.

[0032] It should be noted that among the raw materials of the core layer, the tailings mainly provide silicon, and the potassium feldspar mainly provides potassium. The converter converts the silicon and potassium in the tailings and potassium feldspar from an inert state that cannot be absorbed by plants into an effective state that can be absorbed by plants during the high-temperature process, and also provides calcium and magnesium elements. The binder is used to increase the strength of the core layer material to prevent particle damage during transportation, drying and high temperature. Cement and water are used to prepare cement slurry. After the core layer material and cement slurry are evenly mixed, they are stacked and cured to obtain a complete core layer.

[0033] In some embodiments, the tailings-based soil improved permeable brick meets at least one of the following conditions: A. the adsorbent comprises one or more of rice husk charcoal, attapulgite and humic acid; B. the conversion agent comprises one or more of calcium carbonate, desulfurized gypsum and dolomite; C. The binder is one or more of a sodium lignin sulfonate aqueous solution, a calcium lignin sulfonate aqueous solution, an ammonium chloride aqueous solution and a sodium carboxymethyl cellulose aqueous solution.

[0034] In some embodiments, cement includes, but is not limited to, ordinary Portland cement type 42.5.

[0035] In some embodiments, the tailings-based soil improved permeable brick meets at least one of the following conditions: A. The adsorbent comprises the rice husk charcoal, the attapulgite and the humic acid, wherein the mass ratio of the rice husk charcoal, the attapulgite and the humic acid is 60-80:20-40:0-10; Optionally, in the raw material components of the adsorbent, the mass ratio of rice husk charcoal, attapulgite and humic acid can be 60:20:0, 70:20:0, 80:20:0, 60:30:0, 60:40:0, 60:20:5, 60:20:10 or any value between 60-80:20-40:0-10; It should be noted that when the adsorbent includes rice husk charcoal, attapulgite and humic acid in a mass ratio of 60-80:20-40:0-10, the heavy metal immobilization effect is better. The high porosity structure of rice husk charcoal provides physical adsorption sites, the layered chain structure of attapulgite provides ion exchange sites, and humic acid contains functional groups such as carboxyl and hydroxyl, which can chelate heavy metals to form stable complexes. The combination of the three can cover more heavy metal types and improve the heavy metal immobilization effect.

[0036] B. The conversion agent comprises the calcium carbonate, the desulfurized gypsum and the dolomite, wherein the mass ratio of the calcium carbonate, the desulfurized gypsum and the dolomite is 50-60:20-30:20-30.

[0037] Optionally, in the raw material components of the conversion agent, the mass ratio of calcium carbonate, desulfurized gypsum and dolomite can be 50:20:20, 55:20:20, 60:20:20, 50:30:20, 50:20:30 or any value between 50-60:20-30:20-30.

[0038] It should be noted that when the conversion agent includes calcium carbonate, desulfurized gypsum and dolomite in a mass ratio of 50-60:20-30:20-30, the conversion efficiency of silicon and potassium in tailings and potassium feldspar is high, and the raw material cost is low. Calcium carbonate, desulfurized gypsum and dolomite can react with tailings and potassium feldspar under high temperature conditions to convert inert silicon and potassium into effective states. At the same time, calcium carbonate mainly provides effective calcium elements, and dolomite mainly provides effective magnesium elements. Desulfurized gypsum as industrial solid waste can replace part of calcium carbonate, provide effective calcium elements, and reduce production costs. However, the conversion effect of desulfurized gypsum on tailings and potassium feldspar is not as good as that of calcium carbonate, so the amount added should not be too high.

[0039] C. The binder solution includes the sodium lignin sulfonate aqueous solution, the calcium lignin sulfonate aqueous solution, the ammonium chloride aqueous solution and the sodium carboxymethyl cellulose aqueous solution, wherein the binder solution concentration is 5%-10%.

[0040] Optionally, the concentration of the binder solution may be 5%, 6%, 7% or any value between 5% and 10%.

[0041] It should be noted that when the concentration of the binder solution is 5%-10%, the particle strength of the material after granulation can be effectively improved. Too low a concentration will lead to insufficient bonding, while too high a concentration will affect the fluidity of the solution, the material is easy to agglomerate, and the cost is high.

[0042] In some embodiments, the SiO in the tailings 2 The content of K is greater than 30%, 2 O content is greater than 5%, Cr content is less than 250 mg / kg, Cd content is less than 20 mg / kg, Pb content is less than 400 mg / kg, As content is less than 100 mg / kg, Hg content is less than 10 mg / kg, and Tl content is less than 5 mg / kg.

[0043] Optionally, SiO in tailings 2 The content of K can be 31%, 34%, 40%, 45% or any value greater than 30%. 2 The O content may be 6%, 7%, 8%, 10% or any value greater than 5%, the Cr content may be 10 mg / kg, 20 mg / kg, 50 mg / kg, 100 mg / kg, 200 mg / kg, 240 mg / kg or any value less than 250 mg / kg, the Cd content may be 1 mg / kg, 5 mg / kg, 10 mg / kg, 15 mg / kg, 19 mg / kg or any value less than 20 mg / kg, and the Pb content may be 10 mg / kg, 20 mg / kg, 50 mg / kg, 100 mg / kg, 200 mg / kg / kg, 300mg / kg, 390mg / kg or any value less than 400mg / kg, the As content can be 10mg / kg, 20mg / kg, 50mg / kg, 90mg / kg or any value less than 100mg / kg, the Hg content can be 1mg / kg, 2mg / kg, 4mg / kg, 5mg / kg, 9mg / kg or any value less than 10mg / kg, and the Tl content can be 1mg / kg, 2mg / kg, 3mg / kg, 4mg / kg, 4.5mg / kg or any value less than 5mg / kg.

[0044] It should be noted that SiO in tailings 2 and K 2When the O content is lower than the above value, the effective silicon and potassium content in the core material is low, affecting the soil improvement effect. When the Cr, Cd, Pb, As, Hg, and Tl content in the tailings exceeds the above value, the heavy metal content in the core material is high, and heavy metal dissolution may occur during subsequent applications, affecting the soil improvement effect.

[0045] In some embodiments, the particle sizes of the pigment, the tailings, the cement, the potassium feldspar, and the conversion agent are each independently less than or equal to 0.074 mm.

[0046] Optionally, the particle sizes of the tailings, cement, pigment, potassium feldspar and conversion agent can be independently 0.01 mm, 0.02 mm, 0.05 mm, 0.074 mm or any value less than or equal to 0.074 mm.

[0047] It should be noted that, as the main raw material for granulation, tailings with a particle size of less than 0.074mm can effectively reduce the gaps between particles, ensure that the tailings particles are fully mixed with other raw materials, and avoid stratification or agglomeration caused by particle size differences; cement particle size less than 0.074mm can increase the specific surface area and accelerate the hydration reaction; pigment particle size less than 0.074mm can ensure uniform color distribution and prevent color difference caused by coarse particle aggregation; potassium feldspar and converter particle size less than 0.074mm can ensure full reaction between material particles under high temperature conditions and improve the conversion efficiency of silicon and potassium elements; The second aspect of the present application provides a method for preparing the tailings-based soil improved permeable brick, comprising: Mixing tailings and cement to obtain a first homogenized raw material and a second homogenized raw material; The first homogenized raw material and the adsorbent are first granulated, wherein the adsorbent is disposed on the surface of the first homogenized raw material, and then first cured to obtain a shell material; The second homogenized raw material and the pigment are subjected to a second granulation, wherein the pigment is disposed on the surface of the second homogenized raw material, and then subjected to a second curing to obtain a surface layer material; The tailings, potassium feldspar and the conversion agent are mixed, and the third granulation and roasting are performed to obtain the core layer material; Mixing cement and water to obtain cement slurry, and mixing the core layer material, the shell layer material and the surface layer material with the cement slurry respectively to obtain a core layer material-cement slurry mixture, a shell layer material-cement slurry mixture and a surface layer material-cement slurry mixture; The core layer material-cement slurry mixture, the shell layer material-cement slurry mixture and the surface layer material-cement slurry mixture are sequentially stacked and formed in a mold, and a third curing is performed to obtain tailings-based soil improved permeable bricks; When the first granulation, the second granulation and the third granulation are performed, a binder solution is also sprayed.

[0048] In some embodiments, the first granulation and the second granulation are performed by a layered granulation method.

[0049] Exemplarily, the first homogenized raw material and the adsorbent are first granulated by a layered granulation method, so that the adsorbent wraps the homogenized raw material to form an outer adsorbent-inner homogenized raw material structure, and the binder solution is evenly sprayed during granulation, and then a first curing is performed to obtain a shell material.

[0050] Exemplarily, the second homogenized raw material and the pigment are subjected to a second granulation by a layered granulation method, so that the pigment wraps the homogenized raw material to form a structure of outer pigment-inner homogenized raw material, and the binder solution is evenly sprayed during granulation, followed by a second curing to obtain a surface layer material.

[0051] In some embodiments, the method for preparing tailings-based soil improved permeable bricks meets at least one of the following conditions: A. The disc speeds of the first granulation, the second granulation and the third granulation are independently 20 r / min-40 r / min, and the granulation time is independently 5 min-10 min; Optionally, the disc speeds of the first granulation, the second granulation and the third granulation can be independently 20r / min, 25r / min, 30r / min, 35r / min, 40r / min or any value between 20r / min-40r / min, and the granulation time can be independently 5min, 6min, 7min, 8min, 9min, 10min or any value between 5min-10min; B. The time of the first curing and the second curing are independently 12h-24h; Optionally, the time of the first curing and the second curing can be independently 12h, 16h, 20h, 24h or any value between 12h and 24h; C. The calcination temperature is 1100°C-1200°C and the calcination time is 30min-60min; Optionally, the calcination temperature may be 1100°C, 1150°C, 1200°C or any value between 1100°C and 1200°C, and the calcination time may be 30min, 40min, 50min, 60min or any value between 30min and 60min; It should be noted that roasting can effectively promote the reaction between tailings, potassium feldspar and converters, converting the inert silicon and potassium elements in tailings and potassium feldspar into effective states that can be absorbed by plants; at the same time, the low-melting-point substances in the raw materials melt under high temperature conditions to form a liquid phase that fills between the grains, and forms a consolidated layer after cooling, which significantly improves the mechanical bonding force between the particles, thereby improving the strength of the core layer material and the tailings-based soil-improved permeable bricks.

[0052] D. The third curing period is no less than 28 days.

[0053] Optionally, the third curing time may be 28 days, 30 days, 32 days, or any value not less than 28 days; In some embodiments, the particle size of the shell material is 8 mm-10 mm; Optionally, the particle size of the shell material may be 8 mm, 9 mm, 10 mm or any value between 8 mm and 10 mm; The particle size of the surface layer material is 1mm-3mm; Optionally, the particle size of the surface layer material may be 1 mm, 2 mm, 3 mm or any value between 1 mm and 3 mm; The particle size of the core layer material is 3mm-5mm.

[0054] Optionally, the particle size of the core layer material may be 3 mm, 4 mm, 5 mm or any value between 3 mm and 5 mm.

[0055] It should be noted that the particle size of the surface layer material is 1-3mm, which can intercept large particles of pollutants (such as gravel, leaves) on the one hand, prevent deep pores from being blocked, and extend the service life of permeable bricks, and on the other hand, slow down the flow rate of rainwater while ensuring the permeability coefficient, and promote uniform infiltration of rainwater; the particle size of the core layer material is 3-5mm, and the particle size of the shell layer material is 8-10mm. The particle size is coarser than the surface layer material. On the one hand, it can increase the permeability coefficient and allow rainwater to quickly penetrate into the foundation or drainage system. On the other hand, the coarse particle skeleton structure has high strength, which improves the load capacity of permeable bricks.

[0056] In some embodiments, the method for preparing tailings-based soil improved permeable bricks meets at least one of the following conditions: A. When preparing the homogenized raw material, the mass ratio of the tailings to the cement is 60-80:20-40; Optionally, when preparing the homogenized raw material particles, the mass ratio of tailings to cement can be 60:20, 60:30, 60:40, 70:20, 80:20, 80:40 or any value between 60-80:20-40; B. When preparing the shell material-cement slurry mixture, the mass ratio of the shell material, the cement and the water is 100:15-20:8-10; Optionally, when preparing the shell material-cement slurry mixture, the mass ratio of the shell material, cement and water can be 100:15:8, 100:17:9, 100:20:10 or any value between 100:15-20:8-10; C. When preparing the core material-cement slurry mixture, the mass ratio of the core material, cement and water is 100:15-20:8-10; Optionally, when preparing the core material-cement slurry mixture, the mass ratio of the shell material, cement and water can be 100:15:8, 100:17:9, 100:20:10 or any value between 100:15-20:8-10; D. When preparing the surface material-cement slurry mixture, the mass ratio of the surface material, cement and water is 100:15-20:8-10.

[0057] Optionally, when preparing the surface material-cement slurry mixture, the mass ratio of the shell material, cement and water can be 100:15:8, 100:17:9, 100:20:10 or any value between 100:15-20:8-10.

[0058] In some embodiments, the sequentially stacking and forming in the mold includes: First, spread the shell material-cement slurry mixture all over the bottom and four walls of the mold, then fill the core layer material-cement slurry mixture into it, and then lay the shell material-cement slurry mixture and the surface material-cement slurry mixture in sequence on the core layer material-cement slurry mixture.

[0059] The embodiments of the present application will be described in detail below in conjunction with specific examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If specific conditions are not specified in the examples, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0060] Example 1 This embodiment provides a tailings-based soil improvement permeable brick, which is composed of a surface layer and a base layer, wherein the base layer includes a core layer and a shell layer arranged on the surface of the core layer. The specific structure is as follows Figure 1 As shown, the actual Figure 2 As shown; The raw materials of the surface layer are tailings, cement, binder solution, pigment and water in a mass ratio of 80:44:11:10:12; the raw materials of the shell layer are tailings, cement, binder solution, adsorbent and water in a mass ratio of 80:46:12:20:13; the raw materials of the core layer are tailings, potassium feldspar, conversion agent, binder solution, cement and water in a mass ratio of 60:20:50:12:26:13; The adsorbent is rice husk charcoal, attapulgite and humic acid in a mass ratio of 60:30:10; the conversion agent is calcium carbonate, desulfurized gypsum and dolomite in a mass ratio of 50:20:30; the binder solution is a 5% concentration of sodium lignin sulfonate aqueous solution; the cement is ordinary Portland cement 42.5 type, and the pigment is red iron oxide; The tailings used are copper tailings, in which SiO 2 The content is 62.97%, K 2 The O content is 6.71%, the Cr content is 52.47 mg / kg, the Cd content is 10.67 mg / kg, the Pb content is 74.12 mg / kg, the As content is 15.80 mg / kg, the Hg content is 0.02 mg / kg, and the Tl content is 0.01 mg / kg.

[0061] The present application also provides a method for preparing tailings-based soil improved permeable bricks, the specific steps of which are as follows: (1) Preparation of shell material: weigh tailings, cement, adsorbent and binder solution in a mass ratio of 80:20:20:12, mix tailings and cement evenly to obtain homogenized raw material, granulate the homogenized raw material and adsorbent in a disc pelletizer, the disc pelletizer speed is 30r / min, the granulation time is 8min, and the layered granulation method is adopted in the granulation process, first add the homogenized raw material, and finally add the adsorbent, so that the adsorbent wraps the homogenized raw material to form an external adsorbent-internal homogenized raw material structure, spray the binder solution evenly during granulation, control the particle size to 8mm, and briefly cure for 24h to obtain the shell material; the actual shell material is as follows: Figure 3 As shown; (2) Preparation of surface material: weigh tailings, cement, pigment and binder solution in a mass ratio of 80:20:10:11, mix tailings and cement evenly to obtain homogenized raw material, granulate the homogenized raw material and pigment in a disc pelletizer, the disc pelletizer speed is 30r / min, the granulation time is 5min, and the layered granulation method is adopted in the granulation process, first add the homogenized raw material, and finally add the pigment, so that the pigment wraps the homogenized raw material to form an outer pigment-inner homogenized raw material structure, spray the binder solution evenly during granulation, control the particle size to 3mm, and briefly cure for 24h to obtain the surface material; the actual surface material is as follows Figure 4 As shown; (3) Preparation of core material: weigh tailings, potassium feldspar, converter, and binder solution in a mass ratio of 60:20:50:12, mix the tailings, potassium feldspar, and converter evenly, and use a disc pelletizer to granulate. The disc pelletizer speed is 30r / min, and the granulation time is 6min. Spray the binder solution evenly during the granulation process to control the particle size to 5mm. After drying, place the particles in a muffle furnace for roasting at a temperature of 1200℃ for 40min. After cooling, the core material is obtained. The actual core material is as shown in Figure 5 As shown; (4) Mold forming: Weigh cement, shell material, core material, surface material and water in a mass ratio of 15:50:35:15:7.5, first mix the cement and water evenly to make cement slurry, then divide the cement slurry into three parts according to the mass ratio of shell material, core material and surface material (50:35:15), and mix the weighed shell material, core material and surface material with the corresponding cement slurry respectively to obtain a shell material-cement slurry mixture, a core material-cement slurry mixture and a surface material-cement slurry mixture, which are then stacked and formed.

[0062] First, the shell material-cement slurry mixture is spread over the bottom and four walls of a mold with a size of 10cm×10cm×10cm, and then the core material-cement slurry mixture is filled therein, and finally the shell material-cement slurry mixture and the surface material-cement slurry mixture are spread on the upper layer, and then the mold is placed in a curing room for curing for 28 days to obtain tailings-based soil improved permeable bricks. The process of the preparation method is as follows: Figure 6 shown.

[0063] (5) Test: According to GB / T 25993-2023 Permeable Pavement Bricks and Permeable Pavement Slabs, the permeability coefficient of permeable bricks is 2.37×10 -2 cm / s, flexural strength 3.2MPa, with good water permeability and mechanical properties. At the same time, the prepared tailings-based soil improved permeable bricks were placed in acidic soil for cultivation. During the cultivation process, the soil moisture content was maintained at 15%. According to the change in quality, a certain amount of water was added to the surface layer every three days. The changes in the physical and chemical properties of the test soil within 180 days are shown in Table 1.

[0064] Table 1 Changes in soil physical and chemical properties

[0065] As can be seen from Table 1, within 180 days, the contents of effective silicon, effective calcium, effective potassium and effective magnesium in the soil were significantly increased, the pH increased, and the content of effective heavy metals decreased, indicating that the tailings-based soil improved permeable bricks prepared by this method have the effects of improving acidic soil, supplementing nutrients, and solidifying heavy metals, and the improvement effect lasts for a long time.

[0066] Example 2 The difference from Example 1 is that the mass ratio of rice husk charcoal, attapulgite and humic acid in the adsorbent is changed to 70:25:5.

[0067] According to GB / T 25993-2023 Permeable Pavement Bricks and Permeable Pavement Panels, the permeability coefficient of permeable bricks is 2.31×10 -2 cm / s, and the flexural strength is 3.2 MPa, which has good water permeability and mechanical properties. The soil culture test was carried out according to the method in Example 1, and the test results are shown in Table 2.

[0068] Table 2 Changes in soil physical and chemical properties

[0069] As can be seen from Table 2, within 180 days, the contents of effective silicon, effective calcium, effective potassium and effective magnesium in the soil increased significantly, the pH increased, and the content of effective heavy metals decreased, indicating that the tailings-based soil improved permeable bricks still have a good soil improvement effect under this adsorbent ratio.

[0070] Example 3 The difference from Example 1 is that the mass ratio of calcium carbonate, desulfurized gypsum and dolomite in the conversion agent is changed to 60:20:20.

[0071] According to GB / T 25993-2023 Permeable Pavement Bricks and Permeable Road Slabs, tailings-based soil improved permeable bricks were tested, and the permeability coefficient was 2.31×10 -2 cm / s, and the flexural strength is 3.4 MPa, which has good water permeability and mechanical properties. The soil culture test was carried out according to the method in Example 1, and the test results are shown in Table 3.

[0072] Table 3 Changes in soil physical and chemical properties

[0073] It can be seen from Table 3 that within 180 days, the contents of effective silicon, effective calcium, effective potassium and effective magnesium in the soil increased significantly, the pH increased, and the content of effective heavy metals decreased, indicating that the tailings-based soil improved permeable bricks still have a good soil improvement effect under this conversion agent ratio.

[0074] Example 4 The difference from Example 1 is that the copper tailings used are replaced with gold tailings: wherein SiO 2 The content is 55.64%, K 2 The O content is 5.73%, the Cr content is 35.29 mg / kg, the Cd content is 3.50 mg / kg, the Pb content is 94.12 mg / kg, the As content is 45.73 mg / kg, the Hg content is 0.17 mg / kg, and the Tl content is 0.21 mg / kg.

[0075] According to GB / T 25993-2023 Permeable Pavement Bricks and Permeable Road Slabs, tailings-based soil improved permeable bricks were tested, and the permeability coefficient was 2.42×10 -2 cm / s, and the flexural strength is 3.0 MPa, which has good water permeability and mechanical properties. The soil culture test was carried out according to the method in Example 1, and the test results are shown in Table 4.

[0076] Table 4 Changes in soil physical and chemical properties

[0077] It can be seen from Table 4 that the tailings-based soil improvement permeable bricks have obvious soil improvement effects. Within 180 days, the contents of effective silicon, effective calcium, effective potassium and effective magnesium in the soil were significantly increased, the pH increased, the content of effective heavy metals decreased, and the improvement effect lasted for a long time.

[0078] Comparative Example 1 The difference from Example 1 is that no core layer is provided, and the permeable brick is only composed of an upper surface layer and a lower shell layer.

[0079] According to GB / T 25993-2023 Permeable Pavement Bricks and Permeable Road Slabs, tailings-based soil improved permeable bricks were tested, and the permeability coefficient was 2.32×10 -2 cm / s, and the flexural strength is 3.4 MPa. Compared with Example 1, the water permeability coefficient and flexural strength do not change much. Soil cultivation test was carried out according to the method in Example 1, and the test results are shown in Table 5.

[0080] Table 5 Changes in soil physical and chemical properties

[0081] It can be seen from Table 5 that compared with Example 1, and without setting the core layer, since the surface layer material and the shell layer material basically do not contain effective silicon, effective calcium, effective potassium and effective magnesium, the effective silicon, effective calcium, effective potassium and effective magnesium in the soil basically do not increase after a period of cultivation. As the proportion of the shell layer material increases, the heavy metal solidification effect is improved.

[0082] Comparative Example 2 The difference from Example 1 is that no shell layer is provided, and the permeable brick is only composed of an upper surface layer and a lower core layer.

[0083] According to GB / T 25993-2023 Permeable Pavement Bricks and Permeable Road Slabs, tailings-based soil improved permeable bricks were tested, and the permeability coefficient was 2.12×10 -2 cm / s, and the flexural strength is 2.5 MPa. Compared with Example 1, the water permeability and flexural strength are reduced. The soil culture test was carried out according to the method in Example 1, and the test results are shown in Table 6.

[0084] Table 6 Changes in soil physical and chemical properties

[0085] As shown in Table 6, without the shell layer, the release rate of the valuable components in the core layer increased significantly, causing the pH value and the effective element content to increase significantly in a short period of time, but the plants could not fully utilize these valuable elements in a short period of time, resulting in the leaching of valuable components and the risk of soil salinization. In addition, the heavy metal fixation effect decreased significantly without the shell layer.

[0086] Comparative Example 3 The difference from Example 1 is that the raw materials of the shell layer and the core layer are replaced.

[0087] According to GB / T 25993-2023 Permeable Pavement Bricks and Permeable Road Slabs, tailings-based soil improved permeable bricks were tested, and the permeability coefficient was 2.30×10 -2 cm / s, and the flexural strength is 3.0 MPa. Soil culture test was carried out according to the method in Example 1, and the test results are shown in Table 7.

[0088] Table 7 Changes in soil physical and chemical properties

[0089] It can be seen that compared with Example 1, after the core layer material and the shell layer material are interchanged, the shell layer material lacks a coating layer, and the release rate of the valuable components is greatly increased, so that the pH value and the effective element content are greatly increased in a short time, and the plants cannot fully utilize these valuable elements in a short time, resulting in the loss of valuable components and the risk of soil salinization. In addition, the heavy metal fixation effect is reduced.

[0090] Comparative Example 4 The difference from Example 1 is that no calcination is performed when preparing the core layer material.

[0091] According to GB / T 25993-2023 Permeable Pavement Bricks and Permeable Road Slabs, tailings-based soil improved permeable bricks were tested, and the permeability coefficient was 2.30×10 -2 cm / s, and the flexural strength is 1.4 MPa, which is significantly lower than that in Example 1. The prepared tailings-based soil improved permeable bricks were tested for the changes in the physical and chemical properties of the soil for 180 days, and the test results are shown in Table 8.

[0092] Table 8 Changes in soil physical and chemical properties

[0093] It can be seen that compared with Example 1, the content of effective silicon and effective potassium in the soil did not change significantly when the core layer material was not roasted. This is because the silicon and potassium elements in the tailings and potassium feldspar have not been activated by roasting and are still in an inert state.

[0094] Comparative Example 5 The difference from Example 1 is that during the preparation of the shell material, the particle size is controlled to be 15 mm.

[0095] According to GB / T 25993-2023 Permeable Pavement Bricks and Permeable Road Slabs, tailings-based soil improved permeable bricks were tested, and the permeability coefficient was 3.27×10 -2 cm / s, and the flexural strength is 0.7MPa. It can be seen that compared with Example 1, the strength of the permeable brick decreases significantly when the shell material particle size increases to 15mm. This is because the shell material particles are too large, the contact area between the particles is small, and the cement slurry bonding points are insufficient. At the same time, the large gap between the particles leads to an excessively high permeability rate, which is easy to cause surface runoff during heavy rain.

[0096] Comparative Example 6 The difference from Example 1 is that during the preparation of the surface layer material, the particle size is controlled to be 0.5 mm.

[0097] According to GB / T 25993-2023 Permeable Pavement Bricks and Permeable Road Slabs, tailings-based soil improved permeable bricks were tested, and the permeability coefficient was 0.81×10 -2 cm / s, and the flexural strength is 3.1 MPa. It can be seen that compared with Example 1, the water permeability coefficient of the permeable brick decreases significantly when the surface layer particle size is smaller.

[0098] Comparative Example 7 The difference from Example 1 is that during the preparation of the core layer material, the particle size is controlled to be 1 mm.

[0099] According to GB / T 25993-2023 Permeable Pavement Bricks and Permeable Road Slabs, tailings-based soil improved permeable bricks were tested, and the permeability coefficient was 0.97×10 -2 cm / s, and the flexural strength is 2.8MPa. Compared with Example 1, the water permeability coefficient decreases significantly after the core layer particle size is reduced to 1mm, which is due to the increase in contact points between core layer particles, the decrease in pore size and the deterioration of connectivity.

[0100] Comparative Example 8 The difference from Example 1 is that the copper tailings used are replaced with lead-zinc tailings: SiO 2 The content is 42.66%, K 2 O content is 2.06%, Cr content is 85.07mg / kg, Cd content is 69.60mg / kg, Pb content is 715.66mg / kg, As content is 90.96mg / kg, Hg content is 0.28mg / kg, Tl content is 0.21mg / kg. 2 The O content is lower than the limit requirement, and the Cd and Pb contents exceed the limit requirements.

[0101] According to GB / T 25993-2023 Permeable Pavement Bricks and Permeable Road Slabs, tailings-based soil improved permeable bricks were tested, and the permeability coefficient was 2.28×10 -2 cm / s, and the flexural strength is 3.2 MPa. Soil culture test was carried out according to the method in Example 1, and the test results are shown in Table 9.

[0102] Table 9 Changes in soil physical and chemical properties

[0103] It can be seen from Table 9 that compared with Example 1, the increase in soil available potassium is smaller, the fixation effect of soil heavy metals is worse, and even the content of available Cd and Pb increases. 2 O content is lower than the limit value and heavy metal content is higher than the limit value, which is not suitable for preparing tailings-based soil improved permeable bricks.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application 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 replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0105] In addition, those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the above claims, any one of the claimed embodiments may be used in any combination. The information disclosed in this background technology section is intended only to deepen the understanding of the overall background technology of the present application and should not be regarded as an admission or in any form of implication that the information constitutes prior art known to those skilled in the art.

Claims

1. A tailings-based soil improvement permeable brick, characterized in that: Including surface layer and base layer; The base layer comprises a core layer and a shell layer arranged on the surface of the core layer; The raw materials of the surface layer include tailings, cement, binder solution, pigment and water in a mass ratio of 60-80:33-72:4-26:2-12:7-16; The raw materials of the shell layer include tailings, cement, binder solution, adsorbent and water in a mass ratio of 60-80:36-76:5-30:20-30:8-18; The raw materials of the core layer include tailings, potassium feldspar, a conversion agent, a binder solution, cement and water in a mass ratio of 60-80:20-40:50-80:7-40:19-48:10-24.

2. The tailings-based soil improvement permeable brick according to claim 1, characterized in that: At least one of the following conditions is met: A. the adsorbent comprises one or more of rice husk charcoal, attapulgite and humic acid; B. the conversion agent comprises one or more of calcium carbonate, desulfurized gypsum and dolomite; C. The binder solution includes one or more of a sodium lignin sulfonate aqueous solution, a calcium lignin sulfonate aqueous solution, an ammonium chloride aqueous solution and a sodium carboxymethyl cellulose aqueous solution.

3. The tailings-based soil improvement permeable brick according to claim 2, characterized in that: At least one of the following conditions is met: A. The adsorbent comprises the rice husk charcoal, the attapulgite and the humic acid, wherein the mass ratio of the rice husk charcoal, the attapulgite and the humic acid is 60-80:20-40:0-10; B. The conversion agent comprises the calcium carbonate, the desulfurized gypsum and the dolomite, wherein the mass ratio of the calcium carbonate, the desulfurized gypsum and the dolomite is 50-60:20-30:20-30; C. The concentration of the binder solution is 5%-10%.

4. The tailings-based soil improvement permeable brick according to claim 1, characterized in that: The SiO2 content in the tailings is greater than 30%, the K2O content is greater than 5%, the Cr content is less than 250 mg / kg, the Cd content is less than 20 mg / kg, the Pb content is less than 400 mg / kg, the As content is less than 100 mg / kg, the Hg content is less than 10 mg / kg, and the Tl content is less than 5 mg / kg.

5. The tailings-based soil improvement permeable brick according to any one of claims 1 to 4, characterized in that: The particle sizes of the pigment, the tailings, the cement, the potassium feldspar and the conversion agent are independently less than or equal to 0.074 mm.

6. A method for preparing the tailings-based soil improvement permeable brick according to any one of claims 1 to 5, characterized in that: include: Mixing the tailings and cement to obtain a first homogenized raw material and a second homogenized raw material; The first homogenized raw material and the adsorbent are first granulated, wherein the adsorbent is disposed on the surface of the first homogenized raw material, and then first cured to obtain a shell material; The second homogenized raw material and the pigment are subjected to a second granulation, wherein the pigment is disposed on the surface of the second homogenized raw material, and then subjected to a second curing to obtain a surface layer material; The tailings, potassium feldspar and the conversion agent are mixed, and the third granulation and roasting are performed to obtain the core layer material; Mixing cement and water to obtain cement slurry, and mixing the core layer material, the shell layer material and the surface layer material with the cement slurry respectively to obtain a core layer material-cement slurry mixture, a shell layer material-cement slurry mixture and a surface layer material-cement slurry mixture; The core layer material-cement slurry mixture, the shell layer material-cement slurry mixture and the surface layer material-cement slurry mixture are sequentially stacked and formed in a mold, and a third curing is performed to obtain tailings-based soil improved permeable bricks; When the first granulation, the second granulation and the third granulation are performed, a binder solution is also sprayed.

7. The method for preparing tailings-based soil improved permeable bricks according to claim 6, characterized in that: At least one of the following conditions is met: A. The disc speeds of the first granulation, the second granulation and the third granulation are independently 20 r / min-40 r / min, and the granulation time is independently 5 min-10 min; B. The time of the first curing and the second curing are independently 12h-24h; C. The calcination temperature is 1100°C-1200°C and the calcination time is 30min-60min; D. The third curing period shall not be less than 28 days.

8. The method for preparing tailings-based soil improved permeable bricks according to claim 6, characterized in that: The particle size of the shell material is 8mm-10mm; The particle size of the surface layer material is 1mm-3mm; The particle size of the core layer material is 3mm-5mm.

9. The method for preparing tailings-based soil improved permeable bricks according to claim 6, characterized in that: At least one of the following conditions is met: A. When preparing the homogenized raw material, the mass ratio of the tailings to the cement is 60-80:20-40; B. When preparing the shell material-cement slurry mixture, the mass ratio of the shell material, the cement and the water is 100:15-20:8-10; C. When preparing the core material-cement slurry mixture, the mass ratio of the core material, the cement and the water is 100:15-20:8-10; D. When preparing the surface material-cement slurry mixture, the mass ratio of the surface material, the cement and the water is 100:15-20:8-10.

10. The method for preparing tailings-based soil improvement permeable brick according to any one of claims 6 to 9, characterized in that: The sequentially stacking and forming in the mold comprises: First, spread the shell material-cement slurry mixture all over the bottom and four walls of the mold, then fill the core layer material-cement slurry mixture into it, and then lay the shell material-cement slurry mixture and the surface material-cement slurry mixture in sequence on the core layer material-cement slurry mixture.

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