Method for preparing light ceramic granules from cyanide tailings with a reducing additive

Abstract

The application discloses a method for preparing light ceramsite by using cyanide tailings and reducing additives, and belongs to the technical field of solid waste resource utilization. The method comprises the following steps: (1) weighing high-silicon tailings 50-70 parts, rice husk 10-20 parts, cyanide tailings 5-15 parts, metallurgical furnace ash 5-10 parts, sawdust 3-8 parts, binder 4-6 parts and deionized water 40 parts; (2) crushing the high-silicon tailings, cyanide tailings and metallurgical furnace ash by using a crusher, mixing uniformly, adding the rice husk and sawdust, mixing uniformly, adding the deionized water and binder, stirring into a mud ball, and granulating the mud ball by using a disc granulator to obtain green balls; and (3) drying the green balls to obtain green bodies, and then pre-calcining and calcining the green bodies to obtain the light ceramsite. The application realizes harmless and resource utilization of various solid wastes, and the prepared light ceramsite has high cylinder compressive strength and porosity.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization technology, specifically to a method for preparing lightweight ceramsite using cyanide tailings as a synergistic reducing agent. Background Technology

[0002] Tailings are solid waste generated during mineral resource mining and processing. Traditional treatment methods (such as landfill and stockpiling) pose problems such as land occupation and environmental pollution, and are difficult to utilize effectively. Currently, expanded clay aggregate (ECA), as a new type of material, has the characteristics of being lightweight, high-strength, and having good thermal and sound insulation properties, and is widely used in many fields such as building materials, horticulture, agriculture, petrochemicals, and water treatment. Traditional ECA production relies on non-renewable resources such as clay, shale, and zeolite, which are costly and have limited resources. Since the chemical composition of some industrial solid wastes is similar to that of traditional ECA raw materials, meeting the requirements for ECA preparation, it can serve as an alternative material. In existing ECA preparation technologies, tailings aggregates into spheres under the influence of moisture, but easily disintegrates after drying, resulting in unstable product quality; in addition, there are problems such as low strength.

[0003] Chinese invention patent CN112430066A discloses a lightweight high-strength ceramsite, its preparation method, and its uses. The preparation method of the lightweight high-strength ceramsite includes the following steps: (1) mixing the vanadium extraction tailings from sodium roasting of coal shale with aluminum-containing auxiliary materials to obtain a mixed material; (2) granulating and roasting the mixed material obtained in step (1) to obtain lightweight high-strength ceramsite. This invention achieves effective fixation of alkali metals in the vanadium extraction tailings from sodium roasting of coal shale by controlling the ratio of raw materials and auxiliary materials and the roasting process parameters, and prepares lightweight high-strength ceramsite with low bulk density, but with low porosity. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method for preparing lightweight ceramsite using cyanide tailings as a synergistic reducing agent.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for preparing lightweight ceramsite using cyanide tailings as a synergistic reducing agent includes the following steps:

[0007] (1) Weigh out the following by weight: 50-70 parts of high-silica tailings, 10-20 parts of rice husks, 5-15 parts of cyanide tailings, 5-10 parts of metallurgical furnace ash, 3-8 parts of sawdust, 4-6 parts of binder, and 40 parts of deionized water.

[0008] (2) Use a crusher to crush and sieve the high-silica tailings, cyanide tailings and metallurgical furnace ash, and mix them evenly; add rice husks and sawdust and mix evenly; add deionized water and binder and stir into mud; use a disc granulator to granulate to obtain raw material balls;

[0009] (3) The raw material balls are dried to obtain the green embryo; then, after pre-calcination and calcination, lightweight ceramic granules are obtained.

[0010] The adhesive is prepared by the following method:

[0011] S1: Amino-terminated silicone oil reacts with 1-chloro-6-hydroxyhexane to form a hydroxyl compound; the reaction equation is shown below.

[0012] .

[0013] S2: The hydroxyl compound reacts with succinic anhydride to form a carboxyl compound; the reaction equation is shown below.

[0014] .

[0015] S3: Carboxyl compounds react with chitosan to form an adhesive. In this reaction, the carboxyl groups of the carboxyl compounds undergo an amidation reaction with the amino groups of chitosan.

[0016] In step S1, the mass ratio of the terminal amino silicone oil to 1-chloro-6-hydroxyhexane is 10:(6-7).

[0017] In step S2, the mass ratio of the hydroxyl compound to succinic anhydride is 10:(2.8-3.2).

[0018] In step S3, the mass ratio of the carboxyl compound to chitosan is (15-20).

[0019] In step S1, the reaction solvent used is anhydrous tetrahydrofuran.

[0020] In step S2, the reaction solvent used is DMF.

[0021] In step (3), the drying temperature is 100-110℃ and the time is 4-6h.

[0022] In step (3), the pre-calcination temperature is 200-300℃ and the time is 1-2h; the calcination temperature is 700-900℃ and the time is 1-3h.

[0023] Due to the adoption of the above technical solutions, the beneficial effects of the present invention include:

[0024] This invention utilizes lightweight ceramsite prepared from various solid wastes, exhibiting excellent compressive strength. Rice husks and sawdust, after high-temperature calcination, generate numerous pores, demonstrating promising application potential in building materials and thermal insulation. The introduction of transition metal oxides (such as FeO and MnO) as nucleating agents through metallurgical furnace ash accelerates silicate network formation and shortens sintering time. Furthermore, the addition of a novel binder reduces pulverization, making it less prone to breakage or deformation during transfer, thereby improving the yield of calcined and formed granules. Detailed Implementation

[0025] The following description, in conjunction with specific embodiments, provides further details, but the present invention is not limited to these embodiments.

[0026] Example 1: Preparation of adhesive:

[0027] S1: Add 800 ml of anhydrous tetrahydrofuran (THF), 100 g of amino-terminated silicone oil, 60 g of 1-chloro-6-hydroxyhexane, and 80 g of triethylamine to a reaction flask, stir and mix well, heat to reflux for 6 h, cool to room temperature, wash three times with saturated brine (200 ml each time), and distill under reduced pressure at 50 °C for 3 h to obtain the hydroxyl compound;

[0028] S2: Add 300ml DMF, 50g hydroxy compound and 3g sodium propionate to a reaction flask, heat to 80℃ under nitrogen protection, add 14g succinic anhydride in batches (divided into 4 batches, with an interval of 10min between each batch), react for 8h, cool to room temperature, and distill under reduced pressure at 70℃ for 2h to obtain carboxyl compound.

[0029] S3: Add 990ml of deionized water, 10ml of acetic acid, and 60g of chitosan to a reaction flask, stir to dissolve, and prepare a chitosan solution; add 100ml of anhydrous DMSO and 4g of carboxyl compound to a reaction vessel, stir for 20min, then add 2g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 1.5g of N-hydroxysuccinimide, stir for 2h to activate the carboxyl groups, and add the carboxyl group dropwise to the chitosan solution. After the addition is completed in 30min, raise the temperature to 60℃, stir and react for 8h, cool to room temperature, add 1500ml of anhydrous ethanol to precipitate the solid, filter, wash with 200ml of anhydrous ethanol, and dry under vacuum at 50℃ for 12h to obtain the binder.

[0030] Example 2: Preparation of adhesive:

[0031] S1: Add 800ml of anhydrous THF, 100g of amino-terminated silicone oil, 65g of 1-chloro-6-hydroxyhexane, and 80g of triethylamine to a reaction flask, stir and mix well, heat to reflux for 7h, cool to room temperature, wash three times with saturated brine (200ml each time), and distill under reduced pressure at 50℃ for 3h to obtain the hydroxy compound.

[0032] S2: Add 300ml DMF, 50g hydroxy compound and 3g sodium propionate to a reaction flask, heat to 90℃ under nitrogen protection, add 15g succinic anhydride in batches (divided into 4 batches, 10min interval between each batch), react for 7h, cool to room temperature, and distill under reduced pressure at 40℃ for 2h to obtain carboxyl compound.

[0033] S3: Add 990ml of deionized water, 10ml of acetic acid, and 72g of chitosan to a reaction flask, stir to dissolve, and prepare a chitosan solution; add 100ml of anhydrous DMSO and 4g of carboxyl compound to a reaction vessel, stir for 20min, then add 2g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 1.5g of N-hydroxysuccinimide, stir for 2h to activate the carboxyl groups, and add the carboxyl group dropwise to the chitosan solution. After the addition is completed in 30min, the system is heated to 65℃ and stirred for 7h. After cooling to room temperature, add 1500ml of anhydrous ethanol to precipitate the solid, filter, wash with 200ml of anhydrous ethanol, and dry under vacuum at 50℃ for 12h to obtain the binder.

[0034] Example 3: Preparation of the adhesive:

[0035] S1: Add 800ml of anhydrous THF, 100g of amino-terminated silicone oil, 70g of 1-chloro-6-hydroxyhexane, and 80g of triethylamine to a reaction flask, stir and mix well, heat to reflux for 8 hours, cool to room temperature, wash three times with saturated brine (200ml each time), and distill under reduced pressure at 50℃ for 3 hours to obtain the hydroxyl compound.

[0036] S2: Add 300ml DMF, 50g hydroxy compound and 3g sodium propionate to a reaction flask, heat to 100℃ under nitrogen protection, add 16g succinic anhydride in batches (divided into 4 batches, with an interval of 10min between each batch), react for 6h, cool to room temperature, and distill under reduced pressure at 40℃ for 2h to obtain carboxyl compound.

[0037] S3: Add 990ml of deionized water, 10ml of acetic acid, and 80g of chitosan to a reaction flask, stir to dissolve, and prepare a chitosan solution; add 100ml of anhydrous DMSO and 4g of carboxyl compound to a reaction vessel, stir for 20min, then add 2g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 1.5g of N-hydroxysuccinimide, stir for 2h to activate the carboxyl groups, and add the carboxyl group dropwise to the chitosan solution. After the addition is completed in 30min, the system is heated to 70℃ and stirred for 6h. After cooling to room temperature, add 1500ml of anhydrous ethanol to precipitate the solid, filter, wash with 200ml of anhydrous ethanol, and dry under vacuum at 50℃ for 12h to obtain the binder.

[0038] Example 4: Preparation of lightweight ceramsite:

[0039] (1) Weigh out: 500g of high silica tailings, 100g of rice husks, 50g of cyanide tailings, 50g of metallurgical furnace ash, 30g of sawdust, 40g of binder (prepared in Example 1), and 400g of deionized water.

[0040] (2) Use a crusher to crush the above-mentioned high-silica tailings, cyanide tailings and metallurgical furnace ash respectively, and use a 200-mesh sieve for sieving. Add rice husks and sawdust and stir at 300 r / min for 30 min to mix evenly. Add deionized water and binder, and continue stirring for 1 h to form mud. Use a disc granulator to granulate (25 r / min, 47° tilt angle) for 20 min and then scoop out to obtain raw material balls with a particle size range of 5-10 mm.

[0041] (3) Place the raw material balls in a forced-air drying oven and dry at 100℃ for 6 hours to obtain the green pellets. Then place them in a high-temperature furnace and pre-calcine at 200℃ for 2 hours at a rate of 5℃ / min. Then calcine at 700℃ for 3 hours at a rate of 5℃ / min. Allow them to cool naturally to room temperature to obtain lightweight ceramsite.

[0042] Example 5: Preparation of lightweight ceramsite:

[0043] (1) Weigh out: 600g of high silica tailings, 150g of rice husks, 100g of cyanide tailings, 80g of metallurgical furnace ash, 60g of sawdust, 50g of binder (prepared in Example 2), and 400g of deionized water.

[0044] (2) Use a crusher to crush the above-mentioned high-silica tailings, cyanide tailings and metallurgical furnace ash respectively, and use a 200-mesh sieve for sieving. Add rice husks and sawdust and stir at 300 r / min for 30 min to mix evenly. Add deionized water and binder, and continue stirring for 1 h to form mud. Use a disc granulator to granulate (25 r / min, 47° tilt angle) for 20 min and then scoop out to obtain raw material balls with a particle size range of 5-10 mm.

[0045] (3) Place the raw material balls in a forced-air drying oven and dry at 105℃ for 5 hours to obtain the green pellets. Then place them in a high-temperature furnace and pre-calcine at 250℃ for 1.5 hours at a rate of 5℃ / min. Then calcine at 800℃ for 2 hours at a rate of 5℃ / min. Allow them to cool naturally to room temperature to obtain lightweight ceramsite.

[0046] Example 6: Preparation of lightweight ceramsite:

[0047] (1) Weigh out: 700g of high silica tailings, 200g of rice husks, 150g of cyanide tailings, 100g of metallurgical furnace ash, 80g of sawdust, 60g of binder (prepared in Example 3), and 400g of deionized water;

[0048] (2) Use a crusher to crush the above-mentioned high-silica tailings, cyanide tailings and metallurgical furnace ash respectively, and use a 200-mesh sieve for sieving. Add rice husks and sawdust and stir at 300 r / min for 30 min to mix evenly. Add deionized water and binder, and continue stirring for 1 h to form mud. Use a disc granulator to granulate (25 r / min, 47° tilt angle) for 20 min and then scoop out to obtain raw material balls with a particle size range of 5-10 mm.

[0049] (3) Place the raw material balls in a forced-air drying oven and dry at 110℃ for 4 hours to obtain the green pellets. Then place them in a high-temperature furnace and pre-calcine at 300℃ for 1 hour at a rate of 5℃ / min. Then calcine at 900℃ for 1 hour at a rate of 5℃ / min. Finally, allow them to cool naturally to room temperature to obtain lightweight ceramsite.

[0050] Comparative Example 1

[0051] The raw materials and preparation method of the lightweight ceramsite are basically the same as those in Example 5. The difference is that the binder added to the components (prepared in Example 2) is replaced with an equal weight of amino-terminated silicone oil.

[0052] Comparative Example 2

[0053] The raw materials and preparation method of the lightweight ceramsite are basically the same as those in Example 5, except that the binder added to the components (prepared in Example 2) is replaced with an equal weight of chitosan.

[0054] Comparative Example 3

[0055] The raw materials and preparation method of lightweight ceramsite are basically the same as in Example 5, except that the binder added to the components (prepared in Example 2) is replaced with an equal weight of a binder prepared by the following method:

[0056] S1: Add 300ml DMF, 50g amino-terminated silicone oil and 3g sodium propionate to a reaction flask, heat to 90℃ under nitrogen protection, add 15g succinic anhydride in batches (divided into 4 batches, with an interval of 10min between each batch), react for 7h, cool to room temperature, and distill under reduced pressure at 40℃ for 2h to obtain intermediate 1.

[0057] S2: Add 990ml of deionized water, 10ml of acetic acid, and 72g of chitosan to a reaction flask, stir to dissolve, and prepare a chitosan solution; add 100ml of anhydrous DMSO and 4g of intermediate 1 to a reaction vessel, stir for 20min, then add 2g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 1.5g of N-hydroxysuccinimide, stir for 2h to activate the carboxyl groups, and add the carboxyl group dropwise to the chitosan solution. After the addition is completed in 30min, the system is heated to 65℃ and stirred for 7h. After cooling to room temperature, add 1500ml of anhydrous ethanol to precipitate the solid, filter, wash with 200ml of anhydrous ethanol, and dry under vacuum at 50℃ for 12h to obtain the binder.

[0058] Comparative Example 4

[0059] The raw materials and preparation method of lightweight ceramsite are basically the same as in Example 5, except that the binder added to the components (prepared in Example 2) is replaced with an equal weight of a binder prepared by the following method:

[0060] The preparation method of the adhesive is basically the same as that in Example 2, except that the amino-terminated silicone oil in step S1 is replaced with 6g of ethylenediamine.

[0061] Comparative Example 5

[0062] The raw materials and preparation method of lightweight ceramsite are basically the same as in Example 5, except that the binder added to the components (prepared in Example 2) is replaced with an equal weight of a binder prepared by the following method:

[0063] The preparation method of the adhesive is basically the same as that in Example 2, except that the amount of 1-chloro-6-hydroxyhexane added in step S1 is replaced with 30g.

[0064] The amino-terminated silicone oil used in this application is Cheersil 8110, with an amino content of 2 mmol / g, and is produced by Suzhou Qitian New Materials Co., Ltd.; the chitosan has a number-average molecular weight of 10K and is produced by Shanghai Maokang Biotechnology Co., Ltd.; the sawdust is poplar sawdust with a mesh size of 80-100 mesh; the rice husks are obtained by crushing and passing through an 80-100 mesh sieve; the high-silica tailings contain 68.3 wt% SiO2, 13.95 wt% Al2O3, 3.54 wt% CaO, 1.43 wt% MgO, 0.85 wt% K2O, 0.41 wt% Na2O, and 0.208 wt% TiO2, and are produced by Zhaoyuan Zhonghuan Technology Co., Ltd.; the cyanide tailings have a moisture content of 19.8% and an Fe element content of [missing information]. The metallurgical furnace ash contains 43.29 wt% Si, 6.28 wt% S, 45.72 wt% Al, 1.56 wt% Ca, 0.68 wt% K, 0.26 wt% Na, 1.15 wt% Mg, and is produced by Shandong Jindu Smelting Co., Ltd. The metallurgical furnace ash contains 25.1 wt% FeO, 4.5 wt% SiO2, 8.5 wt% CaO, 15.6 wt% MnO, 1.4 wt% MgO, 34.5 wt% Fe2O3, and 9.2 wt% Fe3O4, and is also produced by Shandong Jindu Smelting Co., Ltd.

[0065] The green embryos prepared in step (3) of Examples 4-6 and Comparative Examples 1-5 were subjected to a pulverization rate test: 100g of green embryo sample was accurately weighed and recorded as m0, and then placed in a tray and vibrated in a vibrating sieve machine (amplitude of 5mm, frequency of 50Hz, sieve mesh of 80 mesh) for 2h. The residual particles were taken out and accurately weighed and recorded as m1. The pulverization rate was calculated as follows: (m0-m1) / m0×100%, and the results are shown in Table 1.

[0066] The apparent density, porosity, and cylinder compressive strength of the lightweight ceramsite prepared in Examples 4-6 and Comparative Examples 1-5 were tested, and the results are shown in Table 1.

[0067] The apparent density test was conducted according to GB / T 17431.2-2010: 500g of lightweight ceramsite was sieved through a 2.36mm sieve. The residue was dried to constant weight, and m=150g was accurately weighed. The ceramsite was then pressed into deionized water using a round metal plate with a handle and soaked for 1 hour. It was then poured onto a 2.36mm sieve and filtered for 1 minute. The ceramsite was then poured onto a wrung-out damp towel, held at both ends to form a trough, and rolled back and forth on the towel 10 times. The ceramsite was then poured into a 1L graduated cylinder, and 500ml of deionized water was added. The ceramsite was then weighed using a round metal plate (with a known volume of V).r Submerge it completely in water and read the water level V on the measuring tube. t Calculate the apparent density ρ = m × 1000 / (V t -V r -500).

[0068] Porosity test: Lightweight ceramsite was cut open from the center with a cutting machine, Al2O3 powder was sprinkled on the cut surface, and the surface was smoothed with a blade. The image was taken with a high-definition digital camera, and the area S0 of Al2O3 and the area S of the cut surface were analyzed using ImageJ software. The porosity was calculated as: ψ=S0 / S×100%.

[0069] The compressive strength test is conducted according to GB / T 17431.2-2010: 5-10mm lightweight ceramsite is sieved and placed in a pressure-bearing cylinder with a bottom, up to the top of the cylinder opening. The cylinder is placed on a concrete testing vibration table and vibrated at 50Hz for 3 seconds. The sample is then placed up to the top of the cylinder opening and vibrated at 50Hz for 5 seconds. The sample is then leveled to the cylinder opening by scraping (or patching). A guide cylinder and a stamping die are then installed. p 1. Apply a uniform load at a rate of 300 N per second. When the die penetration depth reaches 20 mm, record the pressure value. p 2; Calculate the cylinder compressive strength f = ( p 2- p 1) / F, where F is the pressure-bearing area.

[0070] Table 1 Performance Test Data

[0071]

[0072] As can be seen from Examples 4, 5 and 6 in Table 1, the lightweight ceramsite prepared by the present invention has a low green pulverization rate and is not easily broken or deformed during drying and transfer. The calcined lightweight ceramsite has good apparent density, high compressive strength and porosity, and has good application potential in building materials, thermal insulation and other fields.

[0073] The hydrophilic groups (such as hydroxyl and amino groups) in the binder prepared in this invention can form strong interactions with the polar groups (such as silanol groups) on the surface of tailings particles. These interactions, combined with the four-arm structure, flexible silicone oil segments, and alkyl segments, form a three-dimensional network framework structure, reducing the pulverization rate of the green pellet and making it less prone to breakage and deformation during drying and transfer, thus ensuring a high success rate in calcination molding. During the calcination stage, the organic components in the binder (such as chitosan segments) decompose upon heating, generating a large amount of gas (such as CO2 and H2O), which escapes from the ceramic matrix, forming numerous pores and increasing porosity. The silicone oil segments can be converted into inorganic silicon-oxygen structures, preventing premature merging, rupture, or collapse of pores during gas expansion, and enhancing the strength of the ceramic matrix.

[0074] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. However, any modifications, alterations, and variations made by those skilled in the art without departing from the scope of the present invention based on the disclosed technical content are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A method for preparing lightweight ceramsite using cyanide tailings and a synergistic reducing agent, characterized in that, Includes the following steps: (1) Weigh out the following by weight: 50-70 parts of high-silica tailings, 10-20 parts of rice husks, 5-15 parts of cyanide tailings, 5-10 parts of metallurgical furnace ash, 3-8 parts of sawdust, 4-6 parts of binder, and 40 parts of deionized water. (2) Use a crusher to crush and sieve the high-silica tailings, cyanide tailings and metallurgical furnace ash, and mix them evenly; add rice husks and sawdust and mix evenly; add deionized water and binder and stir into mud; use a disc granulator to granulate to obtain raw material balls; (3) The raw material pellets are dried to obtain a green embryo; then, after pre-calcination and calcination, lightweight ceramsite is obtained; The adhesive is prepared by the following method: S1: Amino-terminated silicone oil reacts with 1-chloro-6-hydroxyhexane to form a hydroxyl compound. S2: Hydroxy compounds react with succinic anhydride to form carboxyl compounds. S3: Carboxyl compounds react with chitosan to form an adhesive; In step S1, the mass ratio of the terminal amino silicone oil to 1-chloro-6-hydroxyhexane is 10:(6-7); in step S2, the mass ratio of the hydroxy compound to succinic anhydride is 10:(2.8-3.2); in step S3, the mass ratio of the carboxyl compound to chitosan is 1:(15-20).

2. The method for preparing lightweight ceramsite using cyanide tailings as a synergistic reducing agent according to claim 1, characterized in that, In step S1, the reaction solvent used is anhydrous tetrahydrofuran.

3. The method for preparing lightweight ceramsite using cyanide tailings as a synergistic reducing agent according to claim 1, characterized in that, In step S2, the reaction solvent used is DMF.

4. The method for preparing lightweight ceramsite using cyanide tailings as a synergistic reducing agent according to claim 1, characterized in that, In step (3), the drying temperature is 100-110℃ and the time is 4-6h.

5. The method for preparing lightweight ceramsite using cyanide tailings as a synergistic reducing agent according to claim 1, characterized in that, In step (3), the pre-calcination temperature is 200-300℃ and the time is 1-2h.

6. The method for preparing lightweight ceramsite using cyanide tailings as a synergistic reducing agent according to claim 1, characterized in that, In step (3), the calcination temperature is 700-900℃ and the time is 1-3h.

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