A method for solidifying water-based drilling mud based on alkali-activated copper slag-based cementitious material with pre-reaction strategy

Abstract

This invention relates to the field of solidified water-based drilling mud technology, specifically a method for solidifying water-based drilling mud using an alkali-activated copper slag-based cementitious material based on a pre-reaction strategy. The method includes the following steps: S1. Mixing copper slag and granulated fly ash blast furnace slag for 3-5 minutes to obtain a precursor mixture; S2. Adding a modifier / activator to the precursor mixture and stirring for 3-5 minutes, allowing it to stand for pre-reaction to obtain a cementitious material; S3. Mixing the cementitious material with water-based drilling mud for 5-8 minutes and pouring it into a mold, followed by standard curing to complete the solidification of the water-based drilling mud. This invention significantly improves the alkali-activated reaction efficiency and the mechanical properties of the solidified body through the synergistic effect of the modifier / activator, metal ion modifier, and auxiliary modifier. It achieves spatiotemporal decoupling of the alkali-activated reaction process from the mud interference environment, effectively overcoming fundamental defects in traditional processes such as activator dilution, particle shielding, and reaction path interference.

Description

Technical Field

[0001] This invention relates to the field of solidified water-based drilling mud technology, specifically a method for solidifying water-based drilling mud using alkali-activated copper slag-based cementitious materials based on a pre-reaction strategy. Background Technology

[0002] Alkali activated materials (AAMs) can fully utilize solid waste as precursors, significantly reducing carbon emissions while exhibiting high strength and excellent chemical durability. They are considered ideal candidates to replace ordinary silicate cement in the field of solidification / stabilization (S / S) technology, and have shown great potential in solidifying various industrial wastes and contaminated soils.

[0003] However, existing research largely focuses on the solidification treatment of materials with low water content. When applied to water-based drilling mud (WDM) with high water content (typically >40%) and rich in clay minerals such as montmorillonite, the traditional process usually involves "directly adding a dry precursor mixture and an alkaline activator to the water-based drilling mud slurry." This process has the following fundamental drawbacks: (1) Activator dilution: The large amount of free water in the mud drastically reduces the effective alkali concentration, weakening the dissolution and reaction kinetics of the precursor; (2) Particle adsorption and shielding: Clay minerals have high specific surface area and cation exchange capacity, which can irreversibly adsorb activator components and encapsulate precursor particles, hindering their further reaction; (3) Interference with reaction pathway: The complex chemical environment in the mud may trigger non-target side reactions, consume alkaline components, and interfere with the expected alkaline-activated reaction pathway.

[0004] The combined effect of these factors leads to insufficient dissolution of the precursor, preventing the formation of a complete and robust gel network, resulting in a solidified body with low strength and poor stability. The core of the solution lies in how to separate the critical initial stage of alkali-activated material gel network formation from the disruptive water-based drilling mud environment in time or space, that is, to achieve "reaction process decoupling".

[0005] Currently, there is a lack of research on achieving the aforementioned "decoupling" and systematically optimizing its process parameters. In particular, the exploration of the mechanism by which adjusting the binder addition process (e.g., the "pre-reaction" strategy) affects the solidification performance of high water-cut water-based drilling mud remains a blank area. Therefore, developing an alkali-activated material and process method that can effectively decouple the reaction process and is suitable for the solidification of high water-cut water-based drilling mud has significant technical value and application prospects. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for solidifying water-based drilling mud using alkali-activated copper slag-based cementitious materials based on a pre-reaction strategy.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A method for solidifying water-based drilling mud using alkali-activated copper slag-based cementitious materials based on a pre-reaction strategy includes the following steps: S1. By weight, mix 60-70 parts copper slag, 13-15 parts fly ash, and 13-15 parts granulated blast furnace slag, and stir at a speed of 150-200 r / min for 3-5 min to obtain the precursor mixture. S2. Add 30-40 parts of modified activator to the precursor mixture obtained in step S1, stir at a speed of 200-300 r / min for 3-5 min, and let stand for 10-15 min for pre-reaction to obtain modified CASH gel. S3. Mix the modified CASH gel obtained in step S2 with 850-1000 parts of water-based drilling mud, stir at a speed of 200-300 r / min for 5-8 minutes, pour into a mold, and complete the solidification of the water-based drilling mud after standard curing. The preparation of the modified activator includes the following steps: S21. By mass, ultrasonically disperse 1.5-2 parts of silica fume in 5-7 parts of deionized water to obtain a silica fume dispersion; S22. Mix 30-40 parts of sodium silicate solution, 5-8 parts of metal ion modifier and silica fume dispersion obtained in step S21, and stir in a water bath at 40-50℃ for 3-5 minutes to obtain preliminary modified solution; S23. Add 5-8 parts of auxiliary modifier and 0.2-0.3 parts of polycarboxylate superplasticizer to the preliminary modified liquid obtained in step S22, and stir at a speed of 300-400 r / min for 5-8 min to obtain the modified activator.

[0008] Preferably, the preparation of the metal ion modifier includes the following steps: S221. By mass, add 1.5-2 parts sodium sulfate, 1.2-1.5 parts aluminum sulfate and 0.5-0.8 parts magnesium sulfate to 8-10 parts deionized water, and stir for 5-8 minutes in a water bath at 40°C to obtain a metal ion mixture. S222. Add 0.3-0.5 parts of triethanolamine and 2-3 parts of calcium hydroxide to the metal ion mixture obtained in step S221, and stir at a speed of 300-400 r / min for 10-15 min to finally obtain the metal ion modifier.

[0009] Preferably, the preparation of the auxiliary modifier includes the following steps: S231. By mass, add 1.6-2 parts of calcium dihydrogen phosphate to 8-10 parts of deionized water, and stir at 200-300 r / min for 3-5 min in a water bath at 40℃ to obtain a solution; S232. Add 0.4-0.6 parts of triethanolamine, 0.4-0.6 parts of triisopropanolamine and 0.3-0.4 parts of sodium gluconate to the solution obtained in step S231, and stir at 300-400 r / min for 5-8 min to obtain the auxiliary modifier.

[0010] Preferably, the standard maintenance temperature is 18-22℃, the humidity is ≥95%, and the maintenance period is 28 days.

[0011] Preferably, the ultrasonic dispersion frequency is 40kHz and the time is 10-15min.

[0012] Preferably, the modulus of the sodium silicate solution is 1.3.

[0013] Preferably, the stirring speed in step S22 is 250-300 r / min.

[0014] Preferably, the stirring speed in step S221 is 200-300 r / min.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention significantly improves the efficiency of alkali activation reaction and the mechanical properties of solidified body through the synergistic effect of modified activators, metal ion modifiers and auxiliary modifiers, realizes the spatiotemporal decoupling of alkali activation reaction process and mud interference environment, and effectively overcomes the fundamental defects of traditional process such as activator dilution, particle shielding and reaction path interference.

[0016] 2. This invention significantly improves the microstructure and durability of the solidified body through the synergistic regulation of multiple metal ions and organic additives. It achieves efficient synergistic utilization of multi-source industrial solid waste such as copper slag, fly ash, and slag, significantly reducing material costs and environmental impact, and conforming to the dual technological orientation of green and low-carbon development and solid waste resource utilization. Attached Figure Description

[0017] Figure 1 This is a process flow diagram of the method for solidifying water-based drilling mud using alkali-activated copper slag-based cementitious materials based on a pre-reaction strategy according to the present invention. Figure 2 This is a process flow diagram for preparing the modified activator of the present invention; Figure 3 This is a flow chart of the preparation process of the metal ion modifier of the present invention; Figure 4 This is a process flow diagram for preparing the auxiliary modifier of the present invention; Figure 5 This is a microscopic image of the solidified body after solidification of water-based drilling mud in Embodiment 1 of the present invention. Detailed Implementation

[0018] The present invention will now be clearly and completely described in conjunction with embodiments thereof. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. 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] Please see Figures 1-5 The present invention provides a technical solution: Example 1 A method for solidifying water-based drilling mud using alkali-activated copper slag-based cementitious materials based on a pre-reaction strategy: Before preparing the solidified drilling mud, metal ion modifiers, auxiliary modifiers, and modifier activators are prepared: The preparation of metal ion modifiers includes the following steps: S221. Add 1.5g sodium sulfate, 1.2g aluminum sulfate and 0.5g magnesium sulfate to 8g deionized water, and stir at 200r / min for 5min in a 40℃ water bath to obtain a metal ion mixture. S222. Add 0.3g of triethanolamine and 2g of calcium hydroxide to the metal ion mixture obtained in step S221, and stir at 300r / min for 10min to finally obtain the metal ion modifier.

[0020] The preparation of the auxiliary modifier includes the following steps: S231. Add 1.6g of calcium dihydrogen phosphate to 8g of deionized water and stir at 200r / min for 3min in a water bath at 40℃ to obtain a solution; S232. Add 0.4g triethanolamine, 0.4g triisopropanolamine and 0.3g sodium gluconate to the solution obtained in step S231, and stir at 300r / min for 5min to obtain the auxiliary modifier.

[0021] The preparation of the modified activator includes the following steps: S21. Disperse 1.5g of silica fume ultrasonically (ultrasonic frequency 40kHz, time 10min) in 5g of deionized water to obtain silica fume dispersion; S22. Mix 30g sodium silicate solution (modulus 1.3), 5g metal ion modifier and silica fume dispersion obtained in step S21, and stir at 250r / min for 3min in a water bath at 40℃ to obtain preliminary modified solution; S23. Add 5g of auxiliary modifier and 0.2g of polycarboxylate superplasticizer to the preliminary modified liquid obtained in step S22, and stir at 300r / min for 5min to obtain the modified activator.

[0022] S1. Mix 60g copper slag, 13g fly ash and 13g granulated blast furnace slag, and stir at 150r / min for 3min to obtain precursor mixture; S2. Add 30g of modified activator to the precursor mixture obtained in step S1, stir at 200r / min for 3min, let stand for 10min for pre-reaction to obtain modified CASH gel. S3. Mix the modified CASH gel obtained in step S2 with 850g of water-based drilling mud, stir at 200r / min for 5min, pour into a mold (50×50×50mm), and solidify the water-based drilling mud after standard curing (temperature 18℃, humidity 95%, curing age 28 days).

[0023] Example 2 A method for solidifying water-based drilling mud using alkali-activated copper slag-based cementitious materials based on a pre-reaction strategy: Before preparing the solidified drilling mud, metal ion modifiers, auxiliary modifiers, and modifier activators are prepared: The preparation of metal ion modifiers includes the following steps: S221. Add 2g sodium sulfate, 1.5g aluminum sulfate and 0.8g magnesium sulfate to 10g deionized water, and stir at 300r / min for 8min in a 40℃ water bath to obtain a metal ion mixture. S222. Add 0.5g of triethanolamine and 3g of calcium hydroxide to the metal ion mixture obtained in step S221, and stir at 400r / min for 15min to finally obtain the metal ion modifier.

[0024] The preparation of the auxiliary modifier includes the following steps: S231. Add 2g of calcium dihydrogen phosphate to 10g of deionized water and stir at 300r / min for 5min in a water bath at 40℃ to obtain a solution; S232. Add 0.6g triethanolamine, 0.6g triisopropanolamine and 0.4g sodium gluconate to the solution obtained in step S231, and stir at 400r / min for 8min to obtain the auxiliary modifier.

[0025] The preparation of the modified activator includes the following steps: S21. Disperse 2g of silica fume ultrasonically (ultrasonic frequency 40kHz, time 15min) in 7g of deionized water to obtain silica fume dispersion; S22. Mix 40g sodium silicate solution (modulus 1.3), 8g metal ion modifier and silica fume dispersion obtained in step S21, and stir at 300r / min for 5min in a water bath at 50℃ to obtain preliminary modified solution; S23. Add 8g of auxiliary modifier and 0.3g of polycarboxylate superplasticizer to the preliminary modified liquid obtained in step S22, and stir at 400r / min for 8min to obtain the modified activator.

[0026] S1. Mix 70g copper slag, 15g fly ash and 15g granulated blast furnace slag, and stir at 200r / min for 5min to obtain precursor mixture; S2. Add 40g of modified activator to the precursor mixture obtained in step S1, stir at 300r / min for 5min, let stand for 15min for pre-reaction to obtain modified CASH gel. S3. Mix the modified CASH gel obtained in step S2 with 1000g of water-based drilling mud, stir at 300r / min for 8min, pour into a mold (50×50×50mm), and solidify the water-based drilling mud after standard curing (temperature 22℃, humidity 96%, curing age 28 days).

[0027] Example 3 A method for solidifying water-based drilling mud using alkali-activated copper slag-based cementitious materials based on a pre-reaction strategy: Before preparing the solidified drilling mud, metal ion modifiers, auxiliary modifiers, and modifier activators are prepared: The preparation of metal ion modifiers includes the following steps: S221. Add 1.6g sodium sulfate, 1.3g aluminum sulfate and 0.6g magnesium sulfate to 9g deionized water, and stir at 250r / min for 6min in a 40℃ water bath to obtain a metal ion mixture. S222. Add 0.4g of triethanolamine and 2.5g of calcium hydroxide to the metal ion mixture obtained in step S221, and stir at 350r / min for 11min to finally obtain the metal ion modifier.

[0028] The preparation of the auxiliary modifier includes the following steps: S231. Add 1.7g of calcium dihydrogen phosphate to 9g of deionized water and stir at 250r / min for 4min in a water bath at 40℃ to obtain a solution; S232. Add 0.5g triethanolamine, 0.5g triisopropanolamine and 0.35g sodium gluconate to the solution obtained in step S231, and stir at 350r / min for 6min to obtain the auxiliary modifier.

[0029] The preparation of the modified activator includes the following steps: S21. Disperse 1.6g of silica fume ultrasonically (ultrasonic frequency 40kHz, time 11min) in 6g of deionized water to obtain silica fume dispersion; S22. Mix 32g sodium silicate solution (modulus 1.3), 6g metal ion modifier and silica fume dispersion obtained in step S21, and stir at 260r / min for 4min in a water bath at 42℃ to obtain preliminary modified solution; S23. Add 6g of auxiliary modifier and 0.25g of polycarboxylate superplasticizer to the preliminary modified liquid obtained in step S22, and stir at 350r / min for 6min to obtain the modified activator.

[0030] S1. Mix 62g of copper slag, 14g of fly ash, and 14g of granulated blast furnace slag, and stir at 160r / min for 4min to obtain the precursor mixture; S2. Add 32g of modified activator to the precursor mixture obtained in step S1, stir at 220r / min for 4min, and let stand for 11min for pre-reaction to obtain modified CASH gel. S3. Mix the modified CASH gel obtained in step S2 with 900g of water-based drilling mud, stir at 220r / min for 6min, pour into a mold (50×50×50mm), and solidify the water-based drilling mud after standard curing (temperature 20℃, humidity 97%, curing age 28 days).

[0031] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that no metal ion modifier was added in this comparative example; the other steps are exactly the same in Comparative Example 1 and Example 1.

[0032] Comparative Example 2 The only difference between Comparative Example 2 and Example 1 is that no auxiliary modifier was added in this comparative example; the other steps are exactly the same in Comparative Example 2 and Example 1.

[0033] Comparative Example 3 The only difference between Comparative Example 3 and Example 1 is that the modified activator in this comparative example is replaced with a sodium silicate solution with a modulus of 1.3. The remaining steps are exactly the same in Comparative Example 3 and Example 1.

[0034] Performance testing: This invention presents a microscopic image analysis of the solidified body after the water-based drilling mud has solidified. Figure 5 This is a microscopic image of the solidified body after solidification of water-based drilling mud in Example 1 of the present invention. In the precursor mixture, copper slag mainly releases Fe. 3+ (Under strongly alkaline conditions, Fe) 2+ Oxidized to Fe 3+ ) and trace amounts of Ca 2+ And Al 3+ Granulated blast furnace slag, as a highly efficient calcium source, rapidly releases a large amount of Ca. 2+ Fly ash, as the primary source of aluminum and a secondary source of silicon, has a relatively slow dissolution rate, which delays condensation and modulates reaction kinetics.

[0035] Under alkaline conditions, dissolved active silicon undergoes a condensation reaction and reacts with Ca. 2+ This process combines to form early-stage CASH gel nuclei. Under the action of the modified activator of this invention, a modified CASH gel is generated. Simultaneously, Fe... 3+ The modified CASH gel participates in the reaction through two pathways: firstly, it acts as a network forger, incorporating into the aluminosilicate network to enhance the degree of gel polymerization; secondly, it exists as a nano-sized Fe(OH)3 precipitate. At this point, the system forms an initial CASH gel network with moderate strength, without excessive consumption of free water or loss of workability due to over-reaction. During curing, the continuous formation of the modified CASH gel ultimately achieves an increase in unconfined compressive strength and effective heavy metal fixation.

[0036] The unconfined compressive strength of the cured drilling mud obtained in Examples 1-3 and Comparative Examples 1-3 was tested according to GB / T 17671-1999 "Test Method for Strength of Cement Mortar". The density of the water-based drilling mud used for curing in this invention is 1.2-1.5 g / cm³. 3 The drilling mud contained 45-65% water, 15-25% montmorillonite, and the remainder consisted of filtration loss reducers, diluents, shale inhibitors, lubricants, inorganic salts, and drill cuttings. Its liquid limit was 55-75%, and its plastic limit was 25-35%. Using a universal testing machine, the solidified drilling mud obtained in Examples 1-3 and Comparative Examples 1-3 was placed at the center of the testing machine's pressure plate. The loading speed was 0.5 mm / min, and the maximum destructive load was recorded. The compressive strength was calculated using the formula: f = P / A, where f is the compressive strength (MPa), P is the destructive load (N), and A is the pressure-bearing area (mm²). 2 ).

[0037] The moisture content of the solidified drilling mud obtained in Examples 1-3 and Comparative Examples 1-3 was tested according to GB / T 50123-2019 "Standard for Geotechnical Testing Methods". 50g of the central portion of the solidified drilling mud obtained in Examples 1-3 and Comparative Examples 1-3 was weighed and its wet weight (m) was recorded. w Place in a 105℃ oven and dry until constant weight, then weigh the dry weight m. d Moisture content w = (m w -m d ) / m d ×100%. The results are shown in Table 1 below: Table 1 Results of compressive strength and moisture content tests According to HJ / T 299-2007 "Solid Waste Leaching Toxicity Leaching Method - Sulfuric Acid and Nitric Acid Method", a solution was prepared to test the heavy metal leaching concentration of the solidified drilling mud obtained in Example 1. The final results were compared with the limits in GB 5085.3-2007 "Identification Standard for Hazardous Wastes", and the results are shown in Table 2 below: Table 2 Results of heavy metal leaching concentration test As shown in Table 1, the solidified drilling mud obtained in the example exhibits superior performance in unconfined compressive strength and water content compared to the comparative example. This demonstrates that the synergistic effect of the modified activator, metal ion modifier, and auxiliary modifier significantly improves the alkali-activated reaction efficiency and the mechanical properties of the solidified body, proving the synergistic effect among the three. Meanwhile, Table 2 shows that the heavy metal leaching concentration of the solidified drilling mud obtained by this invention is far below the national standard, indicating excellent environmental safety. The solidified drilling mud prepared by this invention meets environmental safety standards, is suitable for the solidification treatment of high-water-content water-based drilling mud, and has promising engineering application prospects.

[0038] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for solidifying water-based drilling mud using alkali-activated copper slag-based cementitious materials based on a pre-reaction strategy, characterized in that, Includes the following steps: S1. By weight, mix 60-70 parts copper slag, 13-15 parts fly ash, and 13-15 parts granulated blast furnace slag, and stir at a speed of 150-200 r / min for 3-5 min to obtain the precursor mixture. S2. Add 30-40 parts of modified activator to the precursor mixture obtained in step S1, stir at a speed of 200-300 r / min for 3-5 min, and let stand for 10-15 min for pre-reaction to obtain modified CASH gel. S3. Mix the modified CASH gel obtained in step S2 with 850-1000 parts of water-based drilling mud, stir at a speed of 200-300 r / min for 5-8 minutes, pour into a mold, and complete the solidification of the water-based drilling mud after standard curing. The preparation of the modified activator includes the following steps: S21. By mass, ultrasonically disperse 1.5-2 parts of silica fume in 5-7 parts of deionized water to obtain a silica fume dispersion; S22. Mix 30-40 parts of sodium silicate solution, 5-8 parts of metal ion modifier and silica fume dispersion obtained in step S21, and stir in a water bath at 40-50℃ for 3-5 minutes to obtain preliminary modified solution; S23. Add 5-8 parts of auxiliary modifier and 0.2-0.3 parts of polycarboxylate superplasticizer to the preliminary modified liquid obtained in step S22, and stir at a speed of 300-400 r / min for 5-8 min to obtain the modified activator.

2. The method for solidifying water-based drilling mud using alkali-activated copper slag-based cementitious materials based on a pre-reaction strategy, as described in claim 1, is characterized in that... The preparation of the metal ion modifier includes the following steps: S221. By mass, add 1.5-2 parts sodium sulfate, 1.2-1.5 parts aluminum sulfate and 0.5-0.8 parts magnesium sulfate to 8-10 parts deionized water, and stir for 5-8 minutes in a water bath at 40°C to obtain a metal ion mixture. S222. Add 0.3-0.5 parts of triethanolamine and 2-3 parts of calcium hydroxide to the metal ion mixture obtained in step S221, and stir at a speed of 300-400 r / min for 10-15 min to finally obtain the metal ion modifier.

3. The method for solidifying water-based drilling mud using alkali-activated copper slag-based cementitious materials based on a pre-reaction strategy, as described in claim 1, is characterized in that... The preparation of the auxiliary modifier includes the following steps: S231. By mass, add 1.6-2 parts of calcium dihydrogen phosphate to 8-10 parts of deionized water, and stir at 200-300 r / min for 3-5 min in a water bath at 40℃ to obtain a solution; S232. Add 0.4-0.6 parts of triethanolamine, 0.4-0.6 parts of triisopropanolamine and 0.3-0.4 parts of sodium gluconate to the solution obtained in step S231, and stir at 300-400 r / min for 5-8 min to obtain the auxiliary modifier.

4. The method for solidifying water-based drilling mud using alkali-activated copper slag-based cementitious materials based on a pre-reaction strategy, as described in claim 1, is characterized in that... The standard curing temperature is 18-22℃, the humidity is ≥95%, and the curing period is 28 days.

5. The method for solidifying water-based drilling mud using alkali-activated copper slag-based cementitious materials based on a pre-reaction strategy, as described in claim 1, is characterized in that... The ultrasonic dispersion is performed at a frequency of 40 kHz for a duration of 10-15 min.

6. The method for solidifying water-based drilling mud using alkali-activated copper slag-based cementitious materials based on a pre-reaction strategy, as described in claim 1, is characterized in that... The modulus of the sodium silicate solution is 1.

3.

7. The method for solidifying water-based drilling mud using alkali-activated copper slag-based cementitious materials based on a pre-reaction strategy, as described in claim 1, is characterized in that... The stirring speed in step S22 is 250-300 r / min.

8. The method for solidifying water-based drilling mud using alkali-activated copper slag-based cementitious materials based on a pre-reaction strategy, as described in claim 2, is characterized in that... The stirring speed in step S221 is 200-300 r / min.

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