Unfired ceramsite soilless culture mixed substrate and preparation method thereof
By combining unfired ceramsite from sand tailings, perlite, and coconut coir, a soilless cultivation substrate suitable for plant growth was prepared, solving the problems of low utilization rate and environmental pollution of sand tailings, and realizing resource utilization and performance improvement.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ANHUI UNIVERSITY OF ARCHITECTURE
- Filing Date
- 2026-03-12
- Publication Date
- 2026-05-12
Smart Images
Figure CN122004103A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of solid waste resource utilization technology, and in particular to a soilless cultivation mixed substrate made of non-fired ceramsite and its preparation method. Background Technology
[0002] Tailings (ST) mainly originate from waste generated during ore mining, beneficiation, and smelting processes, especially in the mining of metal, non-metal, and coal mines, where they are produced in large quantities. Tailings can be used for soil improvement, building materials, road fillers, and other applications. Some companies and research institutions are also exploring new technologies to improve the utilization rate of tailings.
[0003] Soilless cultivation refers to the method of cultivating crops without natural soil, using nutrient solutions or solid substrates with added nutrient solutions. This includes hydroponics, aeroponics, and substrate cultivation. Commonly used substrate materials are divided into two categories: organic materials, including peat, rice husks, coconut husks, bagasse, sawdust, bark, and compost; and inorganic materials, including sand, gravel, perlite, vermiculite, slag, polystyrene foam granules, and agricultural rock wool. Organic substrates have large porosity, are loose and breathable, and have good water absorption and retention properties; however, their quality is not stable. Inorganic substrates are stable and uniform in quality, resistant to decomposition, and have large porosity; however, their cation exchange capacity is relatively small, resulting in weaker buffering capacity.
[0004] Combining the resource utilization of low-pollution sand tailings with soilless cultivation substrates, using sand tailings ceramsite as a substrate or soil amendment, can improve the resource utilization rate of sand tailings and achieve rational utilization of waste. On the other hand, it can improve substrate performance and reduce planting costs and environmental pollution caused by solid waste. Therefore, developing a soilless cultivation substrate prepared using sand tailings has significant environmental benefits and economic value. Summary of the Invention
[0005] The purpose of this invention is to solve the problems existing in the prior art, and to propose a soilless cultivation mixed substrate for non-fired ceramsite and its preparation method.
[0006] To achieve the above objectives, the present invention adopts the following technical solution: A soilless cultivation substrate made from non-fired expanded clay pebbles, the substrate comprising the following components: Tailings sand, unfired ceramsite, perlite, vermiculite, and coconut coir; The tailings-free ceramsite is a non-fired porous ceramsite prepared by disc granulation using tailings as the main raw material.
[0007] As a preferred embodiment, the mass percentages of the tailings unfired ceramsite, perlite, vermiculite, and coconut coir are 5:1:2:2; The mass percentage of the unfired ceramsite containing sand tailings is 45%–55%, perlite is 8%–12%, vermiculite is 18%–22%, and coconut coir is 18%–22%, with the sum of the mass percentages of each component being 100%.
[0008] As a preferred embodiment, the mixed matrix is composed of unfired ceramsite from sand tailings, perlite, and vermiculite; The mass percentages of the tailings unfired ceramsite, perlite, and vermiculite are 5:2:3; The mass percentage of the unfired ceramsite from the tailings is 45%–55%, perlite is 18%–22%, vermiculite is 28%–32%, and the sum of the mass percentages of all components is 100%.
[0009] As a preferred embodiment, the mixed matrix has the following physicochemical properties: The bulk density is 0.15–0.55 g / cm³; The total porosity is 45%–75%; Water absorption rate ≥35%; The pH value of the leachate is 5.5–8.0; The EC value of the leachate is 300–2000 μS / cm; The TDS value of the leachate is ≤600mg / L.
[0010] As a preferred embodiment, the mixed matrix has the following preferred physicochemical properties: The bulk density is 0.2–0.5 g / cm³; Water absorption rate ≥40%; The pH value of the leachate is 6.0–7.5; The EC value of the leachate is 600–1500 μS / cm; Leachate TDS value ≤500mg / L; The mixed matrix without coconut coir has an extract COD value ≤100mg / L and a TOC value ≤50mg / L.
[0011] A method for preparing a soilless cultivation substrate using non-fired ceramsite includes the following steps: S1. Preparation of non-fired ceramsite from sand tailings: Sand tailings and inorganic binder are mixed at a mass percentage of 100:(5~20), and 15%~30% water is added. The raw balls of non-fired ceramsite from sand tailings are prepared by disc granulation. After curing, the finished product of non-fired ceramsite from sand tailings is obtained. S2. Pretreatment of matrix raw materials: Sieve perlite and vermiculite separately; soak and dehydrate coconut coir until the moisture content is ≤20%; S3. Mixing: Mix the unfired ceramsite from the tailings sand of step S1 with the perlite, vermiculite and coconut coir treated in step S2 in a set ratio to obtain the mixed matrix.
[0012] As a preferred embodiment, in step S1, the inorganic binder is one or more of ordinary Portland cement, slag cement, or fly ash. The mass percentage of tailings sand to inorganic binder is 100:(8-15); The process parameters for the disc granulation method are: disc tilt angle 40°~60°, rotation speed 15~45r / min, and granulation time 10~40min; The curing method is either natural curing for 3 to 28 days or steam curing at 40 to 80°C for 4 to 24 hours. The unfired ceramsite of the tailings sand has a particle size of 3-15 mm, a bulk density of 0.6-1.2 g / cm³, a particle porosity of 30%-60%, and a water absorption rate of 15%-40%.
[0013] As a preferred embodiment, in step S2: The perlite has a particle size of 2–6 mm; The vermiculite has a particle size of 1–4 mm; The coconut coir has a fiber length of 5–20 mm and a moisture content of ≤15%.
[0014] As a preferred embodiment, the mixing ratio in step S3 is either 5:1:2:2 for unfired ceramsite tailings:perlite:vermiculite:coconut coir, or 5:2:3 for unfired ceramsite tailings:perlite:vermiculite.
[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention prepares industrial waste sand tailings into non-fired ceramsite, thereby realizing the resource utilization of waste, reducing the occupation of land resources and environmental pollution caused by tailings stockpiling, and using a non-fired process to prepare ceramsite, which does not require high-temperature sintering, has low energy consumption, and no waste gas emissions, meeting the requirements of green environmental protection.
[0016] 2. The mixed substrate prepared by this invention has a suitable bulk density (0.2-0.5 g / cm³), high water absorption rate (≥40%), suitable pH value (6.0-7.5) and EC value (600-1500 μS / cm), which can meet the growth needs of different plants. The sand tailings ceramsite is loose and porous inside, and can adsorb excess salt into the internal pores during use. The substrate can be reused by simple washing, reducing planting costs. Attached Figure Description
[0017] Figure 1 Photographs of the appearance of the four matrix raw materials used in this invention; wherein (a) is 5-9mm sand tailings ceramsite, (b) is 3-5mm perlite, (c) is 1-3mm vermiculite, and (d) is coconut coir; Figure 2 This is a bar chart showing the physical property test results of the four matrix raw materials used in this invention; Figure 3 The bar chart shows the physical property test results of the five groups of mixed matrices of this invention. Figure 4 The results are as follows: pH values of the leachate from each matrix of the present invention; (a) represents the pH value of the raw material, (b) represents the trend of pH value of the raw material over time, and (c) represents the pH values of the five mixed matrices. Figure 5 The EC values of the leachates from each matrix of this invention are as follows: (a) represents the EC value of the raw materials, and (b) represents the EC values of the five mixed matrices. Figure 6 The results are as follows: COD values of the leachate from each matrix of the present invention are shown; (a) represents the COD value of the raw material, and (b) represents the COD values of the five mixed matrices. Figure 7 The results show the TOC values of the leachates from each matrix of this invention; where (a) is the TOC value of the raw materials and (b) is the TOC value of the five mixed matrices. Figure 8 The results show the TDS values of the leachates from each matrix of this invention; where (a) is the TDS value of the raw materials and (b) is the TDS value of the five mixed matrices. Figure 9 The results are the UV275 values of the leachates of each matrix in this invention; where (a) is the UV275 value of the raw material and (b) is the UV275 value of the five mixed matrices. Detailed Implementation
[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0019] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.
[0020] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.
[0021] Example, refer to Figures 1 to 9 A soilless cultivation substrate made from non-fired ceramsite and its preparation method are disclosed. The substrate comprises the following components: Tailings sand, unfired ceramsite, perlite, vermiculite, and coconut coir; Tailings sand non-fired ceramsite is a non-fired porous ceramsite made from tailings sand as the main raw material through a disc granulation method.
[0022] Tailings (ST): waste products from ore mining and beneficiation processes; Non-fired ceramsite made from sand tailings (SC): Based on previous research, it is produced by using sand tailings as raw material through disc granulation.
[0023] Test method: Bulk density, apparent density, porosity, and water absorption: determined according to relevant industry standard methods; pH value: The matrix leachate was measured using a pH meter; EC value: Measured using a conductivity meter for the matrix leachate; COD: determined by the potassium dichromate method; TOC: Measured using a TOC analyzer; TDS: Measured using a TDS meter; UV275: Absorbance was measured at a wavelength of 275 nm using a UV spectrophotometer.
[0024] The mass percentages of unfired ceramsite, perlite, vermiculite, and coconut coir are 5:1:2:2; The mass percentage of the unfired ceramsite containing sand tailings is 45%–55%, perlite is 8%–12%, vermiculite is 18%–22%, and coconut coir is 18%–22%, with the sum of the mass percentages of each component being 100%.
[0025] The mixed matrix consists of unfired ceramsite from sand tailings, perlite, and vermiculite, and contains no coconut coir. The mass percentages of the unfired ceramsite from sand tailings, perlite, and vermiculite are 5:2:3; the mass percentages of the unfired ceramsite from sand tailings are 45%–55%, perlite is 18%–22%, and vermiculite is 28%–32%, with the sum of the mass percentages of all components being 100%.
[0026] The mixed matrix has the following physicochemical properties: bulk density of 0.15–0.55 g / cm³; total porosity of 45%–75%; water absorption rate ≥35%; leachate pH of 5.5–8.0; leachate EC of 300–2000 μS / cm; and leachate TDS of ≤600 mg / L.
[0027] The mixed matrix has the following preferred physicochemical properties: bulk density of 0.2-0.5 g / cm³; water absorption rate ≥40%; leachate pH of 6.0-7.5; leachate EC of 600-1500 μS / cm; leachate TDS of ≤500 mg / L; and for mixed matrices without coconut coir, leachate COD of ≤100 mg / L and TOC of ≤50 mg / L.
[0028] S1. Preparation of non-fired ceramsite from sand tailings: Sand tailings and inorganic binder are mixed at a mass percentage of 100:(5~20), and 15%~30% water is added. The raw balls of non-fired ceramsite from sand tailings are prepared by disc granulation. After curing, the finished product of non-fired ceramsite from sand tailings is obtained. S2. Pretreatment of matrix raw materials: Sieve perlite and vermiculite separately; soak and dehydrate coconut coir until the moisture content is ≤20%; S3. Mixing: Mix the unfired ceramsite from the tailings sand of step S1 with the perlite, vermiculite and coconut coir treated in step S2 in a set ratio to obtain the mixed matrix.
[0029] As a preferred option, in step S1, the inorganic binder is one or more of ordinary Portland cement, slag cement or fly ash. The mass percentage of tailings sand to inorganic binder is 100:(8-15); The process parameters for the disc granulation method are: disc inclination angle 40°~60°, rotation speed 15~45r / min, and granulation time 10~40min; Curing can be either natural curing for 3–28 days or steam curing at 40–80℃ for 4–24 hours. The particle size of the unfired ceramsite made from sand tailings is 3-15mm, the bulk density is 0.6-1.2g / cm³, the particle porosity is 30%-60%, and the water absorption rate is 15%-40%.
[0030] Example 1: Preparation of non-fired ceramsite from tailings sand; The tailings sand and ordinary silicate cement are mixed at a mass ratio of 100:10, and 20% water is added. After stirring evenly, the mixture is fed into a disc granulator. The disc is tilted at 50°, the rotation speed is 30 r / min, and the granulation time is 25 min to prepare raw pellets of non-fired ceramsite from the tailings sand. The raw pellets are cured under natural conditions for 7 days to obtain the finished product of non-fired ceramsite from the tailings sand.
[0031] Tests showed that the prepared non-fired ceramsite particles had a particle size of 5-9 mm, a bulk density of 0.85 g / cm³, an apparent density of 1.65 g / cm³, a particle porosity of 48%, a water absorption rate of 26%, a leachate pH of 8.5, an EC value of 320 μS / cm, and a TDS value of 180 mg / L.
[0032] Group Tailings ceramsite / % Perlite / % vermiculite / % Coconut coir / % G1 50 10 20 20 G2 50 10 40 0 G3 50 20 30 0 G4 50 30 20 0 G5 50 40 10 0 Table 1 Mass ratio of mixed matrix According to the mass ratio shown in Table 1, the tailings unfired ceramsite, perlite (3-5mm), vermiculite (1-3mm) and coconut coir (soaked and dehydrated to a moisture content of 15%) prepared in Example 1 were weighed and put into the mixing equipment and mixed thoroughly to obtain five groups of mixed matrices.
[0033] The physical properties of the five prepared mixed matrices were tested, and the results are as follows: Figure 3 As shown, the bulk density of the five substrate groups ranged from 0.15 to 0.45 g / cm³, the total porosity from 50% to 70%, and the water absorption rate from 35% to 60%. Among them, group G1 (5:1:2:2) had a bulk density of 0.35 g / cm³, a total porosity of 62%, and a water absorption rate of 55%, exhibiting moderate density suitable for seedling cultivation and new root growth. Group G3 (5:2:3) had a bulk density of 0.2 g / cm³, a total porosity of 68%, and a water absorption rate of 48%, demonstrating loose substrate with good aeration, suitable for seedling cultivation. All five substrate groups exhibited good aeration and water retention capabilities, superior to ordinary soil (water absorption rate approximately 30%).
[0034] The chemical properties of the five prepared mixed matrices were tested: like Figure 4 As shown, the pH test results are as follows: Groups G2-G5, consisting of non-metallic mineral-based substrates (without coconut coir), maintained a stable pH of 7.0-7.5, exhibiting a slightly alkaline state; Group G1, with the addition of coconut coir, showed a slightly acidic pH in its leachate (approximately 6.5). Most plants thrive in soils with a pH between 6.0 and 7.5, and a slightly acidic environment is beneficial for root nutrient absorption and disease and pest prevention. Therefore, coconut coir can adjust the pH of non-metallic mineral-based soilless cultivation substrates, making the substrate more suitable for plant growth.
[0035] like Figure 5 As shown in the figure, the EC value test results are as follows: the suitable EC value for plants is usually 600-1500 μS / cm. The EC value of group G1 is about 850 μS / cm, which is within the suitable range; the EC values of groups G2-G5 are lower (300-500 μS / cm), and soluble fertilizers need to be added when using them for plant cultivation.
[0036] like Figure 6-7 As shown, the COD and TOC test results are as follows: the COD value of the inorganic matrix (G2-G5) is ≤80mg / L and the TOC value is ≤40mg / L, which has less pollution to the plant water and is suitable for seedling cultivation and plant root growth; the COD and TOC values of the G1 group are higher because the coconut coir is rich in soluble organic matter.
[0037] like Figure 8As shown, the TDS test results are as follows: the TDS values of the five mixed matrices are all ≤450mg / L, which is a suitable matrix formula for plant growth. The ceramsite is loose and porous inside, and some soluble salts are precipitated inside the ceramsite when water evaporates, which can be separated from other matrices and thus improve the salinization of the matrix.
[0038] It is worth noting that high TDS is a major cause of substrate salinization or alkalinity. While water evaporates from the substrate or is absorbed by plants, dissolved salts remain in the substrate and gradually accumulate. Over time, the salt concentration in the substrate solution increases. This leads to changes in soil structure (high concentrations of ions disperse soil colloids, disrupting aggregate structure, resulting in substrate compaction, reduced aeration, and decreased permeability) and increases substrate osmotic pressure (when the salt concentration in the substrate solution is higher than that inside plant root cells, water is difficult for roots to absorb, and root cells may even lose water), thus affecting plant growth.
[0039] like Figure 9 As shown, the UV275 test results (based on ultraviolet transmittance and conductivity, mainly used to detect the content of organic pollutants in water. By measuring the ultraviolet transmittance and conductivity of water and combining temperature correction, the chemical oxygen demand, total organic carbon, and total dissolved solids in the water are calculated) show that the UV275 trend is consistent with indicators such as COD and TOC, and can be used as a comprehensive water quality evaluation standard.
[0040] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A soilless cultivation substrate made from non-fired expanded clay pebbles, characterized in that, The mixed matrix comprises the following components: Tailings sand, unfired ceramsite, perlite, vermiculite, and coconut coir; The tailings-free ceramsite is a non-fired porous ceramsite prepared by disc granulation using tailings as the main raw material.
2. The soilless cultivation substrate for non-fired expanded clay pellets according to claim 1, characterized in that, The mass percentages of the tailings unfired ceramsite, perlite, vermiculite, and coconut coir are 5:1:2:2; The mass percentage of the unfired ceramsite containing sand tailings is 45%–55%, perlite is 8%–12%, vermiculite is 18%–22%, and coconut coir is 18%–22%, with the sum of the mass percentages of each component being 100%.
3. The soilless cultivation substrate for non-fired ceramsite as described in claim 2, characterized in that, The mixed matrix consists of unfired ceramsite from sand tailings, perlite, and vermiculite, and does not contain coconut coir; The mass percentages of the tailings unfired ceramsite, perlite, and vermiculite are 5:2:3; The mass percentage of the unfired ceramsite from the tailings is 45%–55%, perlite is 18%–22%, vermiculite is 28%–32%, and the sum of the mass percentages of all components is 100%.
4. The soilless cultivation substrate for non-fired expanded clay pellets according to claim 3, characterized in that, The mixed matrix has the following physicochemical properties: The bulk density is 0.15–0.55 g / cm³; The total porosity is 45%–75%; Water absorption rate ≥35%; The pH value of the leachate is 5.5–8.0; The EC value of the leachate is 300–2000 μS / cm; The TDS value of the leachate is ≤600mg / L.
5. The soilless cultivation substrate for non-fired ceramsite as described in claim 3, characterized in that, The mixed matrix has the following preferred physicochemical properties: The bulk density is 0.2–0.5 g / cm³; Water absorption rate ≥40%; The pH value of the leachate is 6.0–7.5; The EC value of the leachate is 600–1500 μS / cm; Leachate TDS value ≤500mg / L; The mixed matrix without coconut coir has an extract COD value ≤100mg / L and a TOC value ≤50mg / L.
6. A method for preparing a soilless cultivation substrate for non-fired ceramsite as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Preparation of non-fired ceramsite from sand tailings: Sand tailings and inorganic binder are mixed at a mass percentage of 100:(5~20), and 15%~30% water is added. The raw balls of non-fired ceramsite from sand tailings are prepared by disc granulation. After curing, the finished product of non-fired ceramsite from sand tailings is obtained. S2. Pretreatment of matrix raw materials: Sieve perlite and vermiculite separately; soak and dehydrate coconut coir until the moisture content is ≤20%; S3. Mixing: Mix the unfired ceramsite from the tailings sand of step S1 with the perlite, vermiculite and coconut coir treated in step S2 in a set ratio to obtain the mixed matrix.
7. The method for preparing a soilless cultivation mixed substrate using non-fired ceramsite according to claim 6, characterized in that, In step S1, the inorganic binder is at least one of ordinary Portland cement, slag cement or fly ash. The mass percentage of tailings sand to inorganic binder is 100:(8-15); The process parameters for the disc granulation method are: disc tilt angle 40°~60°, rotation speed 15~45r / min, and granulation time 10~40min; The curing method is either natural curing for 3 to 28 days or steam curing at 40 to 80°C for 4 to 24 hours. The unfired ceramsite of the tailings sand has a particle size of 3-15 mm, a bulk density of 0.6-1.2 g / cm³, a particle porosity of 30%-60%, and a water absorption rate of 15%-40%.
8. The method for preparing a soilless cultivation mixed substrate using non-fired ceramsite according to claim 1, characterized in that, In step S2: The perlite has a particle size of 2–6 mm; The vermiculite has a particle size of 1–4 mm; The coconut coir has a fiber length of 5–20 mm and a moisture content of ≤15%.
9. The method for preparing a soilless cultivation mixed substrate using non-fired ceramsite according to claim 1, characterized in that, The mixing ratio in step S3 is either 5:1:2:2 for unfired ceramsite from sand tailings:perlite:vermiculite:coconut coir, or 5:2:3 for unfired ceramsite from sand tailings:perlite:vermiculite.