Cementing material prepared from mine filter cake as well as preparation method and application of cementing material

Abstract

The invention belongs to the technical field of cementing materials, and provides a cementing material prepared from mine filter cakes as well as a preparation method and application of the cementing material. The preparation method comprises the following steps: S1, mixing a mine filter cake and an alkali activator, and reacting to obtain a hydration product with gelling performance; s2, mixing the hydration product with gelling performance with a modifier, and performing modification reaction to obtain a modified hydration product; s3, mixing the modified hydration product with a stabilizer, and performing stabilization reaction to obtain a gelatinized crude product; and S4, sequentially carrying out molding treatment and maintenance treatment on the gelling crude product to obtain the gelling material. According to the method, the soil heavy metal is treated by utilizing the cementing material prepared from the mine filter cake, so that the problem of waste treatment is solved, the treatment efficiency is improved, the treatment cost is reduced, good environmental compatibility and popularization and application prospects are achieved, and remarkable social, economic and environmental benefits are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of cementitious materials, and in particular to a cementitious material prepared by using a mine filter cake, and a preparation method and application thereof. Background Art

[0002] Mine filter cake is a kind of solid waste produced by mines during ore processing and other processes. In the process of mining and ore processing to produce building materials, water washing and other processes are usually used to separate useful components and impurities in the ore, which will produce a large amount of wastewater. These wastewaters contain a large number of solid particles, including suspended matter such as ore powder and soil. Add flocculant polyacrylamide to the wastewater. Polyacrylamide is a linear polymer with the characteristics of flocculation and adhesion. The active groups on its molecular chain adsorb on the surface of fine particles in the wastewater, play a connecting role between particles, make fine particles form larger flocs, accelerate the precipitation rate of solid particles, and thus achieve preliminary separation of solid and liquid. The mixture after flocculation and precipitation is sent to the frame filter press. The frame filter press consists of filter frame, filter plate, clamping device, feeding and discharging system and other parts. During operation, the mixture is pressed into the filter chamber formed between the filter plate and the filter cloth. Under the action of pressure, the liquid is discharged through the filter cloth, and the solid particles are retained in the filter chamber. As the solid particles continue to accumulate, they are gradually compressed into a cake shape, achieving further dehydration and solidification, and finally forming a mining filter cake with a water content of 30-40%.

[0003] At present, a large number of mine filter cakes are handled by stockpiling. Filter cake stockpiling is a common way of dry stacking tailings, that is, the filter cake obtained by concentrated tailings paste, filter pressing or filtration is transported to the tailings yard by car or other transportation methods, and stored in the area formed by valleys or mountainside or plain embankments. However, there are many problems with mine filter cake stockpiling, such as occupying a large amount of land, causing waste of resources, and possibly polluting soil, water and air, and posing safety hazards such as landslides and mud-rock flows. Therefore, how to develop new ways to utilize mine filter cakes has become a problem that people in this field need to solve urgently. Summary of the invention

[0004] In view of this, the present invention provides a cementitious material prepared using mine filter cake, and a preparation method and application thereof, the purpose of which is to solve the problems of low mine filter cake utilization, high processing cost and poor soil heavy metal pollution control effect in the prior art.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] The present invention provides a method for preparing a gelling material using a mine filter cake, comprising the following steps:

[0007] S1, mixing the mine filter cake and the alkali activator and reacting them to obtain a hydration product with gelling properties;

[0008] S2, mixing the hydration product having gelling properties with a modifier and performing a modification reaction to obtain a modified hydration product;

[0009] S3, mixing the modified hydration product and the stabilizer and performing a stabilization reaction to obtain a gelled crude product;

[0010] S4. The raw gelled product is subjected to molding and curing treatments in sequence to obtain a gelled material.

[0011] Furthermore, in the step S1, the water content of the mine filter cake is 30-40%; and the alkaline activator includes potassium hydroxide solution or sodium hydroxide solution.

[0012] Furthermore, in step S1, the mass ratio of the mine filter cake to the alkali activator is 1:0.1-0.5; the reaction temperature is 20-60°C, and the reaction time is 60-120 min.

[0013] Furthermore, in step S2, the modifier includes sodium metasilicate and / or potassium metasilicate; the amount of the modifier is 5-15% of the mass of the mine filter cake.

[0014] Furthermore, in step S2, the temperature of the modification reaction is 30 to 70° C., and the time of the modification reaction is 30 to 180 min.

[0015] Furthermore, in step S3, the stabilizer includes polyvinyl alcohol and / or carboxymethyl cellulose; the amount of the stabilizer is 2-10% of the mass of the mine filter cake.

[0016] Furthermore, in step S3, the temperature of the stabilization reaction is 25 to 65° C., and the time of the stabilization reaction is 60 to 180 minutes.

[0017] Furthermore, in step S4, the pressure of the molding process is 10 to 20 MPa, and the molding process time is 5 to 10 minutes;

[0018] The temperature of the curing treatment is 20-30° C., the humidity of the curing treatment is 90-95%, and the time of the curing treatment is 7-14 days.

[0019] The invention provides a gelling material prepared by the preparation method.

[0020] The present invention also provides the use of the above-mentioned gelling material in soil heavy metal adsorption. The gelling material is used in soil contaminated by heavy metals to reduce the content of heavy metals in the soil and reduce the absorption of heavy metals by plants.

[0021] It can be seen from the above technical solution that compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1. Significantly improved resource utilization: The present invention makes full use of industrial waste, mine filter cake, and converts it into a material with gelling properties, greatly improving resource utilization. Mine filter cake is usually regarded as waste, with high processing costs and a burden on the environment. Through this method, not only the discharge of waste is reduced, but also waste is turned into treasure, and the recycling of resources is realized, which is in line with the development concept of green environmental protection.

[0023] 2. Significantly reduced environmental impact: During the preparation process, the present invention reduces the high-temperature firing process in the production of traditional cementitious materials, thereby significantly reducing energy consumption and carbon dioxide emissions. In addition, the use of mine filter cakes as raw materials reduces the storage and treatment of waste and effectively reduces environmental pollution. According to statistics, every ton of mine filter cakes used can reduce carbon dioxide emissions by about 0.5 tons, which has significant environmental benefits.

[0024] 3. Excellent adsorption performance: The gelling material prepared by the present invention has good soil heavy metal adsorption performance. The mine filter cake contains a large amount of active ingredients such as silicates and aluminates. After being excited by an alkali activator, the generated gelling material has a large specific surface area and rich pore structure, which can effectively adsorb heavy metal ions in the soil and significantly improve the soil environmental quality. Compared with traditional adsorption materials, the present gelling material has significantly improved adsorption efficiency and adsorption capacity.

[0025] 4. Simplified production process and reduced cost: The preparation process of the present invention is relatively simple, mainly including the steps of mixing, reaction, molding and curing, and is easy to operate and easy to industrialize. In the prior art, the preparation of cementitious materials often requires complicated process flow and expensive equipment investment, while the present invention reduces production costs and improves production efficiency by optimizing the process flow.

[0026] 5. Stable product performance: The present invention introduces modifiers and stabilizers to prepare a gelling material with good physical and chemical stability. The modifier can improve the mechanical properties and durability of the gelling material, and the stabilizer can effectively prevent the performance degradation of the gelling material during storage and use. Compared with existing gelling materials, the performance of this product is more stable during long-term use and has a longer service life. DETAILED DESCRIPTION

[0027] The present invention provides a method for preparing a gelling material using a mine filter cake, comprising the following steps:

[0028] S1, mixing the mine filter cake and the alkali activator and reacting them to obtain a hydration product with gelling properties;

[0029] S2, mixing the hydration product having gelling properties with a modifier and performing a modification reaction to obtain a modified hydration product;

[0030] S3, mixing the modified hydration product and the stabilizer and performing a stabilization reaction to obtain a gelled crude product;

[0031] S4. The raw gelled product is subjected to molding and curing treatments in sequence to obtain a gelled material.

[0032] In the present invention, in step S1, the water content of the mine filter cake is 30-40%, preferably 32-38%, and more preferably 34-36%; the alkaline activator includes potassium hydroxide solution or sodium hydroxide solution, the mass concentration of the potassium hydroxide solution is preferably 5-10%, and the mass concentration of the sodium hydroxide solution is preferably 5-10%.

[0033] In the present invention, in step S1, the mass ratio of the mine filter cake to the alkali activator is 1:0.1-0.5, preferably 1:0.2-0.4, and more preferably 1:0.3; the reaction temperature is 20-60°C, preferably 30-50°C, and more preferably 40°C; the reaction time is 60-120min, preferably 70-110min, and more preferably 80-100min.

[0034] In the present invention, in step S2, the modifier includes sodium metasilicate and / or potassium metasilicate; the amount of the modifier is 5-15% of the mass of the mine filter cake, preferably 8-12%, and more preferably 10%.

[0035] In the present invention, in step S2, the temperature of the modification reaction is 30-70°C, preferably 40-60°C, and more preferably 50°C; the time of the modification reaction is 30-180 min, preferably 50-150 min, and more preferably 80-120 min.

[0036] In the present invention, in step S3, the stabilizer includes polyvinyl alcohol and / or carboxymethyl cellulose; the amount of the stabilizer is 2-10% of the mass of the mine filter cake, preferably 3-8%, and more preferably 5%.

[0037] In the present invention, in step S3, the temperature of the stabilization reaction is 25 to 65°C, preferably 30 to 60°C, and more preferably 40 to 50°C; the time of the stabilization reaction is 60 to 180 min, preferably 80 to 150 min, and more preferably 100 to 120 min.

[0038] In the present invention, in step S4, the pressure of the molding process is 10 to 20 MPa, preferably 12 to 18 MPa, and more preferably 14 to 16 MPa; the time of the molding process is 5 to 10 min, preferably 6 to 9 min, and more preferably 7 to 8 min;

[0039] The temperature of the curing treatment is 20-30° C., preferably 22-28° C., and more preferably 24-26° C.; the humidity of the curing treatment is 90-95%, and the curing treatment time is 7-14 days.

[0040] The invention provides a gelling material prepared by the preparation method.

[0041] The invention also provides application of the gelling material in adsorption of heavy metals in soil.

[0042] In the present invention, the silicate and aluminate in the mine filter cake usually have a relatively stable crystal structure. When the alkali activator is added, the alkali metal ions (such as Na + , K + ) reacts with the surface of the crystal to break the chemical bonds inside the crystal. Taking silicate minerals as an example, the bridging oxygen bonds between silicon oxygen tetrahedrons (SiO4) will break under the action of alkali; for aluminates, structures such as aluminum oxygen octahedrons (AlO6) will also be affected, causing the crystal structure to gradually become loose, creating conditions for the subsequent dissolution of active ingredients. After the crystal structure is destroyed, active ingredients such as silicon (Si) and aluminum (Al) are released from the crystal structure and enter the solution. In the high pH environment of the alkaline solution, silicon is released in the form of silicate ions (SiO3 2- ) or more complex polysilicate ions, while aluminum exists as aluminate ions (AlO2 - ) and other forms. For example, under the action of alkaline activators such as sodium silicate, the calcium silicate minerals in the filter cake will react, causing silicon to dissolve into the solution in the form of silicate ions. The dissolved active ingredients such as silicon and aluminum have high chemical activity in the solution, and they will further react with ions in the alkaline activator and water molecules. Silicon and aluminum ions will connect with each other through hydroxyl (-OH) bridging to form a three-dimensional network or chain-like amorphous gel structure. In this process, the alkali metal ions in the alkaline activator play a role in balancing the charge and promoting the formation of gel. The amorphous gel finally formed has good gelling properties and adhesion, such as the common sodium aluminosilicate hydrate (NASH) and calcium aluminosilicate hydrate (CASH) gels.

[0043] The modified cementitious material has a unique chemical structure and a large specific surface area. It can efficiently adsorb and fix a variety of heavy metal ions such as cadmium, lead, and copper through complexation, electrostatic adsorption, ion exchange, etc., stabilize the heavy metal ions in the soil, and reduce their mobility and bioavailability in the soil. It can also form a stable solidified structure or wrapping layer around the heavy metal ions, effectively blocking the dissolution of heavy metals by the external environment, significantly reducing the risk of heavy metal leaching under conditions such as rainwater leaching and groundwater infiltration, and reducing its secondary pollution to the soil and groundwater.

[0044] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0045] Example 1

[0046] The mine filter cake is mixed with a sodium hydroxide solution with a mass concentration of 8% in a mass ratio of 1:0.3, and after being evenly mixed, it is placed in a reaction container and reacted at 40°C for 90 minutes to ensure that the alkaline activator fully activates the active ingredients in the mine filter cake to obtain a hydration product with gelling properties.

[0047] 8% of the mass of the sodium metasilicate from the mine filter cake is taken, and the sodium metasilicate and the hydration product having gelling properties are mixed and reacted at 60° C. for 100 min to obtain a modified hydration product;

[0048] Take 3% of the mass of the mine filter cake polyvinyl alcohol, mix the polyvinyl alcohol and the modified hydration product, and react at 50°C for 120 minutes to obtain a gelled crude product.

[0049] The crude gelled product was poured into a mold, a pressure of 15 MPa was applied, and the pressure was maintained for 8 minutes. The molded crude gelled product was then placed in an environment with a humidity of 90% and a temperature of 25°C for curing for 10 days to obtain a gelled material.

[0050] Example 2

[0051] The mine filter cake is mixed with a sodium hydroxide solution with a mass concentration of 10% in a mass ratio of 1:0.2, and after being evenly mixed, it is placed in a reaction container and reacted at 50°C for 80 minutes to ensure that the alkaline activator fully activates the active ingredients in the mine filter cake to obtain a hydration product with gelling properties.

[0052] 10% of the mass of the mine filter cake is taken of potassium metasilicate, and the potassium metasilicate and the hydration product having gelling properties are mixed and reacted at 50° C. for 120 minutes to obtain a modified hydration product;

[0053] Take 6% of the mass of the mine filter cake polyvinyl alcohol, mix the polyvinyl alcohol and the modified hydration product, and react at 40°C for 130 minutes to obtain a gelled crude product.

[0054] The crude gelled product was poured into a mold, a pressure of 15 MPa was applied, and the pressure was maintained for 8 minutes. The molded crude gelled product was then placed in an environment with a humidity of 90% and a temperature of 25°C for curing for 12 days to obtain a gelled material.

[0055] Example 3

[0056] The mine filter cake is mixed with a sodium hydroxide solution with a mass concentration of 5% in a mass ratio of 1:0.4, and after being evenly mixed, it is placed in a reaction container and reacted at 30°C for 120 minutes to ensure that the alkaline activator fully activates the active ingredients in the mine filter cake to obtain a hydration product with gelling properties.

[0057] 12% of the mass of the sodium metasilicate from the mine filter cake is taken, and the sodium metasilicate and the hydration product having gelling properties are mixed and reacted at 55° C. for 95 minutes to obtain a modified hydration product;

[0058] Take 7% of the mass of the mine filter cake polyvinyl alcohol, mix the polyvinyl alcohol and the modified hydration product, and react at 35°C for 150 minutes to obtain a gelled crude product.

[0059] The crude gelled product was poured into a mold, a pressure of 15 MPa was applied, and the pressure was maintained for 8 minutes. The molded crude gelled product was then placed in an environment with a humidity of 90% and a temperature of 25°C for curing for 10 days to obtain a gelled material.

[0060] Example 4

[0061] The mine filter cake is mixed with a potassium hydroxide solution with a mass concentration of 8% at a mass ratio of 1:0.5, and after being evenly mixed, it is placed in a reaction container and reacted at 60°C for 70 minutes to ensure that the alkaline activator fully activates the active ingredients in the mine filter cake to obtain a hydration product with gelling properties.

[0062] 9% potassium metasilicate by mass of the mine filter cake is taken, the potassium metasilicate is mixed with a hydration product having gelling properties, and then reacted at 60° C. for 90 minutes to obtain a modified hydration product;

[0063] Take 6% carboxymethyl cellulose of the mass of the mine filter cake, mix the carboxymethyl cellulose and the modified hydration product, and react at 45°C for 110 minutes to obtain a gelled crude product.

[0064] The crude gelled product was poured into a mold, a pressure of 15 MPa was applied, and the pressure was maintained for 8 minutes. The molded crude gelled product was then placed in an environment with a humidity of 90% and a temperature of 25°C for curing for 12 days to obtain a gelled material.

[0065] Example 5

[0066] The mine filter cake is mixed with a potassium hydroxide solution with a mass concentration of 7% in a mass ratio of 1:0.1, and after being evenly mixed, it is placed in a reaction container and reacted at 60° C. for 90 minutes to ensure that the alkaline activator fully activates the active ingredients in the mine filter cake to obtain a hydration product with gelling properties.

[0067] 14% of the mass of the potassium metasilicate from the mine filter cake is taken, the potassium metasilicate is mixed with the hydration product having gelling properties, and then reacted at 55° C. for 85 minutes to obtain a modified hydration product;

[0068] Take 7% carboxymethyl cellulose of the mass of the mine filter cake, mix the carboxymethyl cellulose and the modified hydration product, and react at 40°C for 140 minutes to obtain a gelled crude product.

[0069] The crude gelled product was poured into a mold, a pressure of 15 MPa was applied, and the pressure was maintained for 8 minutes. The molded crude gelled product was then placed in an environment with a humidity of 90% and a temperature of 25°C for curing for 12 days to obtain a gelled material.

[0070] Comparative Example 1

[0071] The same as Example 1, except that no modifier is added for modification.

[0072] Performance Testing

[0073] The heavy metal contaminated soils treated in Examples 1 to 5 and Comparative Example 1 are heavy metal contaminated soils from the same region, which are close but not adjacent. The heavy metal content in the heavy metal contaminated soils before and after the use of cementitious materials for restoration was detected by atomic fluorescence spectroscopy. The results are shown in Table 1.

[0074] Table 1 Remediation results of heavy metals in soil

[0075] category Hg(mg / kg) Cr(mg / kg) Pb(mg / kg) Cd(mg / kg) As (mg / kg) Initial content 10.58 106.42 186.32 6.19 1.17 Example 1 1.16 52.37 33.54 1.74 0.45 Example 2 1.24 54.38 35.42 1.96 0.52 Example 3 1.19 55.13 34.65 2.03 0.54 Example 4 1.28 52.96 35.17 1.94 0.48 Example 5 1.41 54.47 36.14 2.08 0.55 Comparative Example 1 9.76 101.26 185.62 5.78 1.12

[0076] As can be seen from Table 1, the gelling material prepared by the present invention has good soil heavy metal adsorption performance, can effectively adsorb heavy metal ions in the soil, and significantly improve the soil environmental quality.

[0077] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a gelling material using a mine filter cake, characterized in that: The following steps are involved: S1, mixing the mine filter cake and the alkali activator and reacting them to obtain a hydration product with gelling properties; S2, mixing the hydration product having gelling properties with a modifier and performing a modification reaction to obtain a modified hydration product; S3, mixing the modified hydration product and the stabilizer and performing a stabilization reaction to obtain a gelled crude product; S4. The raw gelled product is subjected to molding and curing treatments in sequence to obtain a gelled material.

2. The preparation method according to claim 1, characterized in that: In the step S1, the water content of the mine filter cake is 30-40%; the alkaline activator includes potassium hydroxide solution or sodium hydroxide solution.

3. The preparation method according to claim 2, characterized in that: In the step S1, the mass ratio of the mine filter cake to the alkali activator is 1:0.1-0.5; the reaction temperature is 20-60°C, and the reaction time is 60-120 minutes.

4. The preparation method according to any one of claims 1 to 3, characterized in that: In the step S2, the modifier includes sodium metasilicate and / or potassium metasilicate; the amount of the modifier is 5-15% of the mass of the mine filter cake.

5. The preparation method according to claim 4, characterized in that: In the step S2, the temperature of the modification reaction is 30-70° C., and the time of the modification reaction is 30-180 min.

6. The preparation method according to claim 3, characterized in that: In step S3, the stabilizer includes polyvinyl alcohol and / or carboxymethyl cellulose; the amount of the stabilizer is 2-10% of the mass of the mine filter cake.

7. The preparation method according to claim 2, 3 or 6, characterized in that: In the step S3, the temperature of the stabilization reaction is 25 to 65° C., and the time of the stabilization reaction is 60 to 180 minutes.

8. The preparation method according to claim 7, characterized in that: In step S4, the pressure of the molding process is 10-20 MPa, and the molding process time is 5-10 min; The temperature of the curing treatment is 20-30° C., the humidity of the curing treatment is 90-95%, and the time of the curing treatment is 7-14 days.

9. The gelling material prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the gelling material according to claim 9 in adsorption of heavy metals in soil.