Solid waste-based heavy metal stabilizer as well as preparation method and application thereof

Abstract

The invention discloses a solid waste-based heavy metal stabilizer as well as a preparation method and application thereof, and relates to the related technical field of oil-based rock debris. According to the invention, through the design of the solid waste-based heavy metal stabilizer and the design of the overall proportion for heavy metals and harmful substances in the oil-based rock debris, the harmful substances can be cured, a stable structure is formed through chemical reaction, and the curing treatment greatly improves the mechanical properties and environmental safety of the material; in the mixing and reaction process of the oil-based rock debris and the heavy metal stabilizer, the formed cement makes the pore filling of the whole mixture more compact and reduces the connectivity, so that the permeability is improved, the risk of environmental pollution is reduced, and the solid waste-based heavy metal stabilizer takes the steel slag as the main raw material, so that the cost is lower, and the solid waste-based heavy metal stabilizer is suitable for industrial production. The heavy metal stabilizing effect is better than that of common materials such as cement.

Description

Technical Field

[0001] The present invention relates to the technical field related to oil-based rock cuttings, and in particular to a solid waste-based heavy metal stabilizer and a preparation method and application thereof. Background Art

[0002] Oil-based rock cuttings refer to solid waste generated by the use of drilling fluid (usually oil-based drilling fluid) during oil drilling. These wastes mainly come from rock fragments generated when the drill bit cuts the formation and the mixture formed after the reaction of drilling fluid and formation rock. The composition of oil-based rock cuttings is complex, mainly including drill cuttings, mud and sand, organic components in oil-based drilling fluid (such as base oil, emulsifier, organic additives, etc.) and a small amount of heavy metal elements.

[0003] The organic components and heavy metal elements in oil-based rock cuttings are potentially harmful to the environment and ecology. If they are directly discharged or piled up without treatment, the oil pollution in the oil-based rock cuttings will seep into the soil, pollute the groundwater, and affect plant growth; at the same time, heavy metal elements will also enter the human body through the food chain, posing a threat to human health. In addition, the stacking of oil-based rock cuttings will occupy a large amount of land resources and increase the cost of environmental governance.

[0004] At present, the treatment methods for oil-based rock cuttings at home and abroad mainly include two ways: harmless treatment and resource utilization. Harmless treatment mainly includes incineration, pyrolysis, solidification and stabilization technologies, aiming to reduce the pollution and harmfulness of oil-based rock cuttings; resource utilization mainly uses technical means to extract useful components in oil-based rock cuttings, such as base oil, heavy metals, etc., to achieve waste reduction, resource utilization and harmlessness.

[0005] Resource utilization technology is a hot topic in the current research field of oil-based rock cuttings processing. By adopting physical, chemical or biological methods, valuable components such as base oil and emulsifiers can be extracted from oil-based rock cuttings to achieve resource utilization of waste. In addition, oil-based rock cuttings can also be used as raw materials for building materials, roadbed materials, etc., further broadening its application field;

[0006] Currently commonly used heavy metal stabilizers generally have the problems of limited stabilization effect and high cost. Summary of the invention

[0007] The object of the present invention is to provide a solid waste-based heavy metal stabilizer and a preparation method and application thereof, so as to solve the technical problems raised in the background technology.

[0008] To achieve the above object, the present invention provides the following technical solution: a solid waste-based heavy metal stabilizer, comprising at least slurry, slag and fly ash;

[0009] The slurry accounts for 50% to 60%, the slag accounts for 20% to 30%, the fly ash accounts for 20% to 30%, and the rest is acid-base regulator.

[0010] Furthermore, the slurry includes activated carbon powder, steel slag powder and water, and the pH value of the slurry is adjusted by concentrated sulfuric acid.

[0011] A method for preparing a solid waste-based heavy metal stabilizer comprises at least the following steps:

[0012] S1: The steel slag raw material is subjected to a heat-stifling treatment to expand the steel slag, so that the residue and the metal can be separated better;

[0013] S2: Use jaw crusher to initially crush the steel slag;

[0014] S3: Grind the steel slag into 1-5 μm by using a steel slag grinder;

[0015] S4: Mix the activated carbon powder and steel slag powder, introduce nitrogen protection, heat to 400°C, and react for 1 hour;

[0016] S5: The powder after the reaction in S4 is mixed with water to a slurry state, and then concentrated sulfuric acid is added dropwise to react until the pH value of the slurry is between 6 and 7, and the mixture is allowed to stand for 4 to 6 hours;

[0017] S6: Mix the slurry with slag and fly ash, add cement clinker powder to adjust the pH value, and adjust the pH value to between 9 and 10 to prepare a solid waste-based heavy metal stabilizer.

[0018] The invention discloses an application of a solid waste-based heavy metal stabilizer, wherein the solid waste-based heavy metal stabilizer is added into oil-based rock cuttings at a dosage of 10% to 20% to achieve the purpose of stabilizing heavy metals.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The present invention adopts the design of solid waste-based heavy metal stabilizer, and targets heavy metals and harmful substances in oil-based rock cuttings. Through the design of overall proportion, it can not only solidify harmful substances, but also form a stable structure through chemical reaction. This solidification treatment greatly improves the mechanical properties and environmental safety of the material. In addition, during the mixing and reaction process of the oil-based rock cuttings with the heavy metal stabilizer, the cement formed makes the pore filling of the entire mixture more dense and the connectivity is reduced, thereby improving its permeability and reducing the risk of environmental pollution.

[0021] 2. The solid waste-based heavy metal stabilizer in the present invention uses steel slag as the main raw material, which has a lower cost and a better heavy metal stabilization effect than common materials such as cement. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0023] Figure 1 XRD microscopic detection of the present invention. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0025] Embodiment 1:

[0026] For disclosing a solid waste-based heavy metal stabilizer;

[0027] A solid waste-based heavy metal stabilizer, comprising at least slurry, slag and fly ash;

[0028] The proportion of slurry is 50% to 60%, the proportion of slag is 20% to 30%, the proportion of fly ash is 20% to 30%, and the rest is acid-base regulator.

[0029] The slurry includes activated carbon powder, steel slag powder and water, and the pH value of the slurry is adjusted by using concentrated sulfuric acid.

[0030] Embodiment 2:

[0031] On the basis of Example 1, a preparation method of a solid waste-based heavy metal stabilizer is further disclosed;

[0032] A method for preparing a solid waste-based heavy metal stabilizer comprises at least the following steps:

[0033] S1: The steel slag raw material is subjected to a heat-stifling treatment to expand the steel slag, so that the residue and the metal can be separated better;

[0034] S2: Use jaw crusher to initially crush the steel slag;

[0035] S3: Grind the steel slag into 1-5 μm by using a steel slag grinder;

[0036] S4: Mix the activated carbon powder and steel slag powder, introduce nitrogen protection, heat to 400°C, and react for 1 hour;

[0037] S5: The powder after the reaction in S4 is mixed with water to a slurry state, and then concentrated sulfuric acid is added dropwise to react until the pH value of the slurry is between 6 and 7, and the mixture is allowed to stand for 4 to 6 hours;

[0038] S6: Mix the slurry with slag and fly ash, add cement clinker powder to adjust the pH value, and adjust the pH value to between 9 and 10 to prepare a solid waste-based heavy metal stabilizer.

[0039] Embodiment three:

[0040] A specific application is disclosed based on the above-mentioned embodiment 2;

[0041] The invention discloses an application of a solid waste-based heavy metal stabilizer, wherein the solid waste-based heavy metal stabilizer is added into oil-based rock cuttings at a dosage of 10% to 20% to achieve the purpose of stabilizing heavy metals.

[0042] Based on the above three embodiments, the following comparative experiments are proposed:

[0043] Comparative experiment 1:

[0044] First, the performance of a solid waste-based heavy metal stabilizer is compared with that of P042.5 cement. The experiment is a national standard experiment, so the inspection process is explained in detail.

[0045] Comparison of technical performance indicators between heavy metal stabilizers and cement

[0046]

[0047]

[0048] From the above comparison, it can be clearly seen that heavy metal stabilizers have higher compression resistance.

[0049] Comparative experiment 2:

[0050] Comparison of heavy metal leaching from oil-based rock cuttings by solid waste-based heavy metal stabilizer and cement, using solidification experiment, this experiment uses ceramsite process for solidification;

[0051] The ceramsite curing process is as follows:

[0052] 1. Raw material ratio and mixing:

[0053] Obtain heavy metal stabilizer and oil-based rock cuttings, grind the materials to a particle size of 0.075 mm, and control the total mass to 50 g to form a uniform powder.

[0054] 2. Add water and stir:

[0055] 15 g of distilled water was added to the above powder so that the total mass ratio of water to the solid mixture was 3:13.

[0056] Stir thoroughly for about 8 minutes, until the mixture is slurry-like, making sure the ingredients are evenly distributed.

[0057] 3. Modeling and initial curing:

[0058] Shape the paste into spherical pellets about 6 cm in diameter.

[0059] The spherical particles are wrapped in a plastic mold to prevent the water from evaporating too quickly, and placed in a constant temperature box for 24 hours of constant temperature curing.

[0060] 4. Post-maintenance:

[0061] After the spherical particles are taken out of the plastic mold, they are put back into the constant temperature box for further curing for 4-7 days to enhance the physical properties of the expanded clay, including its strength and durability.

[0062] During the entire post-curing stage, the interior of the incubator maintains a constant temperature of 98% humidity and 20±5 degrees Celsius.

[0063] After the curing was completed, the expanded clay specimens were obtained.

[0064] The experimental steps of heavy metal leaching are as follows:

[0065] The first step is to soak in acetic acid. The process is standard. After getting the soaking solution;

[0066] Then use the AAS test to determine the heavy metal content in the solution. The AAS test is a national standard. During the measurement, since the content of some heavy metals is relatively small, the leaching concentrations of the two heavy metals with the highest content are shown below.

[0067]

[0068] Further explain the principle of heavy metal stabilizer in this case:

[0069] Heavy metal solidification mechanism

[0070] The heavy metal stabilizer and ordinary cement (a common method of selecting as a curing agent) in the present invention are used as passivating agents to solidify heavy metals, which is mainly divided into two parts: adsorption and replacement of heavy metal ions.

[0071] What is characterized here are two situations that exist simultaneously when heavy metal stabilizers and cement are used as passivators to stabilize heavy metals. The heavy metal stabilizer in the present invention is special compared to cement. The special feature is that more calcium sulfonate is generated in the hydration reaction, and the calcium-silicon ratio is lower, so that the heavy metal stabilizer is better for solidifying heavy metals in oil-based rock cuttings.

[0072] 1. Calcium sulfate has a stabilizing effect on heavy metal ions

[0073] As a crystalline calcium sulfoaluminate hydrate mineral, ettringite usually exhibits a trigonal crystal system with a needle-like or columnar structure. The columnar structure of ettringite not only contributes to the formation of a high surface area, but also enriches the internal columnar channels, significantly enhancing the adsorption capacity and ion exchange capacity of cement. In the core of the columnar crystals, the main structure consists of alumina octahedra connected by intra-column hydrogen bonds and ionic bonds formed by calcium ions and hydroxide networks. The pores between the columns are formed by van der Waals forces and electrostatic interactions. The microstructure of ettringite consists of a large number of small and large pores. This unique pore structure effectively adsorbs and stabilizes heavy metal ions and prevents them from migrating in the environment. The dense pore filling of ettringite enhances its ability to fix heavy metal ions. The formation of ettringite is affected by temperature and pH and requires precise control. Once formed, ettringite can maintain its heavy metal stabilization function even under poor environmental conditions. In addition, the ettringite formed during cement hydration has high expansibility, which enhances the structural strength of the curing framework.

[0074] [Al(OH)6] in ettringite 3- The octahedral structure has high surface energy and strong electrostatic charge, which significantly enhances the heavy metal stabilizer of oil-based cuttings to Pb 2+ and Ni 2+ Ion adsorption capacity. The structure of ettringite further improves the adsorption efficiency of heavy metal ions through its strong dipole-dipole hydrogen bonding interactions. The high surface area of ​​ettringite provides numerous active sites, which are conducive to the effective adsorption of heavy metal ions. Through surface adsorption, ettringite can neutralize the negative charge on the crystal surface and promote the easy entry of heavy metal ions into its core structure or intercolumnar channels. This mechanism is crucial for the removal of heavy metal ions in environmental remediation.

[0075] The crystal structure of ettringite can effectively encapsulate heavy metal ions during its formation. In the lattice of ettringite, heavy metal ions such as Pb 2+ and Ni 2+ Can replace the Ca 2+ In addition, when charge imbalance occurs inside the crystal, Al 3+ It can also be replaced by these heavy metal ions, thereby further adjusting and stabilizing the lattice structure. The ion substitution mechanism not only helps to fix the heavy metal ions, but also significantly enhances the solidification effect of ettringite on heavy metal ions.

[0076] 2. Cement hydration reaction will generate CSH structure. The generated CSH structure has a lower calcium-silicon ratio than traditional cement, and a lower calcium-silicon ratio has a stronger ability to attract heavy metals;

[0077] The ability of CSH structure to repair heavy metals is closely related to the calcium-silicon ratio. As the calcium-silicon ratio in CSH increases, the content of exchangeable cations decreases, which directly affects its ability to stabilize heavy metals. The stabilization mechanism of CSH structure for heavy metal ions mainly involves precipitation and ion exchange processes.

[0078] In a low calcium-silicon ratio environment, ion exchange is considered to be the main mechanism for CSH to treat heavy metals and plays a key role. 2+ It exists freely between layers or on the surface and is not specifically attached to the silicate tetrahedron, thus increasing the hydrated Ca 2+ The amount of hydrated Ca 2+ Located mainly at exchangeable sites, it is stabilized by chemical adsorption with silicic acid chains to form metal-oxygen-silicon bonds, thus enhancing the Pb 2+ and Ni 2+ In addition, the dense microstructure of CSH with a low calcium-silicon ratio significantly reduces the permeability to heavy metal ions, helping to prevent their migration and diffusion.

[0079] Under low Ca / Si ratio conditions, CSH exhibits higher chemical stability by forming solid solutions or precipitates to encapsulate and stabilize heavy metal ions. 2+ The concentration of Pb increases, promoting 2+ The ions react to form insoluble compounds Ca[Pb(OH)3]2, thus effectively removing heavy metal ions from the environment. 2+ The Si-O-Ni-O-Si structure is formed by replacing the deprotonated negatively charged silanol groups. The Si-O-Ni-O-Si structure not only stabilizes the Ni 2+ , and other heavy metal ions are fixed by chemical binding, which is more stable than physical adsorption, thereby fixing heavy metals for a long time.

[0080] CSH with a low calcium-silicon ratio reduces the solubility of heavy metal ions in the pore fluid and reduces the concentration of soluble calcium ions, thereby alleviating heavy metal pollution in the environment. In addition, the low alkalinity of CSH with a low calcium-silicon ratio helps reduce the solubility of certain heavy metals, especially those that form soluble complexes under high pH conditions, further reducing the environmental risks of these metals.

[0081] In order to further supplement the above conclusions, XRD microscopic examination was performed, see Figure 1 ;

[0082] Qualitative information about the mineral phases was determined using XRD analysis data, and the exact content of each crystal was quantified. It was found that the content of ettringite in the oil-based cuttings was significantly increased after mixing with the metal stabilizer. The heavy metal stabilizer provided a higher sulfate content, which promoted the formation of insoluble sulfate precipitation of heavy metal ions in the oil-based cuttings. Therefore, the solidification of heavy metals by ettringite was enhanced, and this factor was beneficial to solidification. This finding is consistent with the theory that ettringite significantly solidifies heavy metals. The test results also revealed the increased content of calcite, calcium hydroxide, and barium sulfate in the heavy metal stabilizer of the oil-based cuttings, indicating the formation of more heavy metal compound precipitation. These results not only confirm the occurrence of chemical reactions, but also show that these components play a key role in the heavy metal solidification process, especially in adjusting the pH value of the solidification system and controlling the microenvironment, which is consistent with the solidification mechanism of low calcium-silicon ratio.

[0083] Of course, for more application scenarios, the following two practical application directions are proposed:

[0084] Use of solid waste-based heavy metal stabilizers in cement mixing piles

[0085] Cement mixing pile overview:

[0086] Cement mixing piles are a foundation reinforcement method that mixes cement with foundation soil on site to form a cement-soil cylinder, thereby improving the bearing capacity and stability of the foundation. This method is widely used in construction, roads, ports and other projects to enhance the overall performance of the foundation.

[0087] Material performance requirements for cement mixing piles:

[0088] The production of high-quality cement mixing piles needs to meet the following basic material performance requirements:

[0089] 1. Compressive strength: The cement mixing pile material must have sufficient compressive strength to withstand the load of the superstructure and ensure the stability of the foundation.

[0090] 2. Shear strength: The material needs to have good shear strength to improve the bonding between the pile and the surrounding soil and prevent slippage.

[0091] Durability: The material should have excellent durability and be able to resist erosion by water, chemicals and the effects of freeze-thaw cycles for a long time to ensure the long-term stability of the pile.

[0092] 3. Low shrinkage: The material should have low shrinkage to prevent the pile from undergoing significant volume changes during the hardening process, which would affect its bonding with the surrounding soil.

[0093] 4. Good rheological properties: The material should have good rheological properties to facilitate on-site mixing and piling, ensuring that the material can fully penetrate and be evenly distributed in the foundation soil.

[0094] The solid waste-based heavy metal stabilizer of the present invention has the following performance advantages:

[0095] 1. High compressive strength: By adopting the properties of raw materials, cement mixing piles prepared with heavy metal stabilizers have higher compressive strength, which significantly improves the bearing capacity of the foundation compared to traditional cement.

[0096] 2. Excellent shear strength: The active ingredients in heavy metal stabilizers, such as SiO2 and Al2O3, fully react with the foundation soil to form a high-strength structure, which enhances the bonding strength between the pile and the surrounding soil and prevents slippage.

[0097] 3. Excellent durability: This heavy metal stabilizer forms a stable crystalline structure during preparation, which can resist the erosion of water and chemicals and the influence of freeze-thaw cycles for a long time, ensuring the long-term stability and durability of the pile.

[0098] 4. Low shrinkage: This material has low shrinkage and will not undergo significant volume changes during the hardening process, thus ensuring good bonding between the pile and the surrounding soil and avoiding cracks and strength reduction due to shrinkage.

[0099] 5. Good rheological properties: During the mixing process, this heavy metal stabilizer has excellent rheological properties, can fully penetrate and evenly distribute in the foundation soil, forming a uniform pile structure, ensuring construction quality and pile performance.

[0100] Use of solid waste-based heavy metal stabilizers in rural simple roads

[0101] Overview of rural simple pavement:

[0102] Rural simple pavement refers to an economical and practical road form built in rural areas, usually used to connect villages and farmlands, towns, etc. Its construction requires low cost and simple construction, as well as good bearing capacity and durability to meet the transportation needs of rural areas.

[0103] Material performance requirements for rural simple pavement:

[0104] 1. Compressive strength: The pavement material must have sufficient compressive strength to withstand vehicle loads and ensure the stability of the pavement.

[0105] 2. Crack resistance: The material needs to have good crack resistance to prevent cracks from appearing on the road surface during use.

[0106] 3. Wear resistance: The material should have excellent wear resistance and be able to resist vehicle crushing and wear for a long time to ensure the long-term service life of the road surface.

[0107] 4. Durability: The material should have excellent durability and be able to resist erosion by water, chemicals and the effects of freeze-thaw cycles for a long time to ensure the long-term service life of the road surface.

[0108] 5. Low cost and easy construction: The materials should be low cost and easy to construct to adapt to the economic and technical conditions of rural areas.

[0109] The performance advantages of the heavy metal stabilizer of the present invention are:

[0110] 1. High compressive strength: Heavy metal stabilizers have high compressive strength and can withstand vehicle loads on rural roads to ensure road stability.

[0111] 2. Excellent crack resistance: This heavy metal stabilizer forms a uniform structure during the construction process and has good crack resistance. It can effectively prevent cracks from appearing on the road surface during use and extend the service life of the road surface.

[0112] 3. Excellent wear resistance: This material forms a dense structure after preparation, has excellent wear resistance, can resist vehicle rolling and wear for a long time, and ensure the long-term service life of the road surface.

[0113] 4. Durability: This heavy metal stabilizer forms a stable crystalline structure during the calcination process, which can resist the erosion of water and chemicals and the influence of freeze-thaw cycles for a long time, ensuring the long-term stability and durability of the road surface.

[0114] 5. Low cost and easy construction: By utilizing a large amount of cheap industrial waste as raw materials, the cost of this heavy metal stabilizer is relatively low, and the construction process is simple, which is suitable for the economic and technical conditions of rural areas.

[0115] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A solid waste-based heavy metal stabilizer, characterized in that: Includes at least slurry, slag and fly ash; The slurry accounts for 50% to 60%, the slag accounts for 20% to 30%, the fly ash accounts for 20% to 30%, and the rest is acid-base regulator.

2. The solid waste-based heavy metal stabilizer according to claim 1, characterized in that: The slurry comprises activated carbon powder, steel slag powder and water, and the pH value of the slurry is adjusted by using concentrated sulfuric acid.

3. A method for preparing a solid waste-based heavy metal stabilizer, used for the solid waste-based heavy metal stabilizer according to any one of claims 1 to 2, characterized in that: At least the following steps are included: S1: The steel slag raw material is subjected to a heat treatment to expand the steel slag, so that the residue and the metal can be separated better; S2: Use jaw crusher to initially crush the steel slag; S3: Grind the steel slag into 1-5 μm by using a steel slag grinder; S4: Mix the activated carbon powder and steel slag powder, introduce nitrogen protection, heat to 400°C, and react for 1 hour; S5: The powder after the reaction in S4 is mixed with water to a slurry state, and then concentrated sulfuric acid is added dropwise to react until the pH value of the slurry is between 6 and 7, and the mixture is allowed to stand for 4 to 6 hours; S6: Mix the slurry with slag and fly ash, add cement clinker powder to adjust the pH value, and adjust the pH value to between 9 and 10 to prepare a solid waste-based heavy metal stabilizer.

4. An application of a solid waste-based heavy metal stabilizer, characterized in that: The solid waste-based heavy metal stabilizer prepared in claim 3 is added into oil-based rock cuttings at a dosage of 10% to 20% to achieve the purpose of stabilizing heavy metals.

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