Method for producing clay-containing slurry

Abstract

To provide a method for producing clay-comprising slurry capable of easily producing clay-comprising slurry having suitable viscosity in accordance with applications by the improvement of thickener effect.SOLUTION: A method for producing clay-containing slurry has a process where plural components including (A) water [hereinafter, referred to as a component (A)], (B) a swellable clay mineral [hereinafter, referred to as a component (B)] and (C) a powdery thickener [hereinafter, referred to as a component (C)] are mixed, in which the component (A) and the component (B) are mixed so as to be a mixture, and thereafter, the mixture is mixed with the component (C).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a clay-containing slurry. [Background technology]

[0002] In recent years, efforts have been made to develop environmentally friendly infrastructure from an ESG perspective in order to achieve the SDGs. One example of this is the use of pile drilling fluid when driving precast concrete piles, which serve as support piles for structures.

[0003] When driving precast concrete piles, the ground to be driven is drilled in advance, and then the concrete pile is inserted. However, in gravel ground, the workability is reduced due to blockage caused by ground collapse. Therefore, a pile drilling fluid made of clay mineral slurry is used as an agent to prevent the hole wall from collapsing.

[0004] Clay minerals are composed of layers of silicate, and swell by retaining and binding solvents or dispersants within the layers. When a slurry containing water and clay minerals is used as a pile drilling fluid, it acts to prevent the collapse of sand and gravel (hole wall protection).

[0005] Many industrial products used in the form of aqueous solutions or slurries use various types of additives to improve their physical properties. For example, in order to modify the rheology of an aqueous solution or slurry, it is sometimes desirable to appropriately adjust the viscosity depending on the purpose and application. Conventionally, methods for adjusting the viscosity of an aqueous solution or slurry have been adopted, such as adding a thickener or a viscosity reducer, performing heating or cooling, or adjusting the electrolyte concentration. It is also known that surfactants affect the viscosity, elasticity, and thickening properties of aqueous solutions and slurries (Patent Documents 1 and 2). Patent Document 3 discloses the use of a rheology modifier characterized by the combined use of two different amphoteric surfactants in a slurry composition containing an inorganic powder such as bentonite. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2014-502602 [Patent Document 2] Japanese Patent Application Publication No. 8-133805 [Patent Document 3] Japanese Patent Publication No. 2020-76022 Summary of the Invention [Problem to be solved by the invention]

[0007] Clay mineral slurries are used, for example, as pile drilling fluid. Pile drilling fluids are used when excavating gravel ground, which is prone to collapse, due to their excellent ability to protect hole walls. However, when used in gravel ground with large voids, in particular, there are many cases where the fluid leaks from the ground and contaminates groundwater (lost water). Generally, the higher the viscosity of slurries used as pile drilling fluids, the greater their effectiveness in preventing lost water. Therefore, a method for effectively thickening such slurries is sometimes desired.

[0008] The present invention provides a method for producing a clay-containing slurry that improves the effect of a thickener and that can easily produce a clay-containing slurry having a viscosity appropriate for the intended use. [Means for solving the problem]

[0009] The present invention provides a method for producing a clay-containing slurry by mixing a plurality of components including (A) water (hereinafter referred to as component (A)), (B) a swelling clay mineral (hereinafter referred to as component (B)), and (C) a powdery thickener (hereinafter referred to as component (C)), mixing the component (A) and the component (B) to form a mixture, and then mixing the component (C) with the mixture; The present invention relates to a method for producing a clay-containing slurry. [Effects of the Invention]

[0010] According to the present invention, there is provided a method for producing a clay-containing slurry that improves the effect of a thickener and that can easily produce a clay-containing slurry having a viscosity appropriate for the application. DETAILED DESCRIPTION OF THE INVENTION

[0011] In recent years, the SDGs have been advocated to realize a sustainable society. This invention can improve chemical economy by improving water leakage prevention and prevent water pollution, and is thought to be a technology that can contribute to SDGs 6, 7, 8, 9, 11, 12, 13, and 14, for example.

[0012] As mentioned above, it is considered desirable to thicken clay-containing slurries, such as those used as drilling fluids, in order to improve the effect of preventing water loss from the ground. When using a thickener for this purpose, the inventors have unexpectedly found that using the thickener in powder form and premixing water with a clay mineral before adding the powdered thickener improves the thickening effect and water loss prevention. The present invention is based on this finding. The mechanism by which the thickening effect and further the water loss prevention effect are improved by the present invention is not entirely clear, but is presumed to be as follows. Because clay minerals are layered and porous, they swell when they come into contact with water, trapping water within their structure and preventing water loss. Clay minerals and thickeners become electrically charged in water and tend to aggregate, but in the present invention, the clay mineral is first swollen with water and then the thickener is used in powder form, thereby suppressing electrostatic aggregation between the clay mineral and the thickener and allowing them to disperse uniformly. At this point, the clay mineral is sufficiently swollen. From these facts, it is believed that in the present invention, the thickening effect due to the swelling of the clay mineral and the thickening effect due to the thickener are effectively exerted, improving the viscosity of the slurry and ultimately improving water loss prevention.

[0013] First, the components used in the method for producing a clay-containing slurry of the present invention will be described. In the present invention, a plurality of components including water (component A), a swelling clay mineral (component B), and a powdered thickener (component C) are mixed together.

[0014] The water of component (A) can be tap water, river water, lake water, groundwater, or the like.

[0015] The swelling clay mineral of component (B) may be selected from layered silicates. Examples of swelling clay minerals of component (B) include kaolinite, smectite, clay, talc, montmorillonite, illite, glauconite, chlorite, sericite, zeolite, and bentonite. In the present invention, "swelling" refers to the swelling volume (cm) per 1 g of clay mineral, measured according to the bentonite test method specified in the 15th edition of the Japanese Pharmacopoeia. 3 ) is the swelling force expressed as 20cm 3 / g or more.

[0016] The powder thickener of component (C) contains two or more compounds represented by the following general formula (1), hereinafter also referred to as compound (1), wherein X in the general formula (1) is different in the two or more compounds, and at least one of the two or more compounds is different from R of X in the general formula (1). 1a or R 1b Examples of the powder thickener include a compound in which the alkyl group is an alkenyl group.

[0017] [ka]

[0018] [Wherein X is R 1a or R 1b -[CONH-CH2CH2CH2] n R is a group represented by the formula 1a R is an alkyl group having 14 to 22 carbon atoms or an alkenyl group having 14 to 22 carbon atoms. 1b is an alkyl group having 13 to 21 carbon atoms or an alkenyl group having 13 to 21 carbon atoms. n is an integer of 1 to 3. 2 and R 3 are each independently an alkyl group having 1 to 4 carbon atoms or -(C2H4O) p H. p is the average number of moles added, and R 2 and R 3 The sum of these is a number between 0 and 5.

[0019] Regarding the compound (1), when X in the general formula (1) is different, for example, when there are two kinds of compound (1), the following embodiments can be mentioned. In the following embodiments, R of at least one of the two kinds of compound (1) is different. 1a or R 1b is an alkenyl group. (i) One R 1a or R 1b is an alkyl group, and the other R 1a or R 1b is an alkenyl group. (ii) One R 1a or R 1b The number of carbon atoms in the other R 1a or R 1b The carbon numbers are different. (iii) One of the Xs is R 1a and the other X is R 1b -[CONH-CH2CH2CH2] n -It is. (iv) Both X and R 1b -[CONH-CH2CH2CH2] n - and one n is different from the other n. (v) A combination of (i) to (iv) above.

[0020] In the general formula (1), X is R 1a or R 1b -[CONH-CH2CH2CH2] n - is a group represented by the formula: R 1a is an alkyl group having 14 to 22 carbon atoms or an alkenyl group having 14 to 22 carbon atoms. R 1a When is an alkenyl group, it preferably has 18 or more carbon atoms and preferably 22 or less carbon atoms. R 1a When is an alkyl group, it preferably has 16 or more carbon atoms and preferably has 22 or less carbon atoms. R 1b is an alkyl group having 13 to 21 carbon atoms or an alkenyl group having 13 to 21 carbon atoms. R 1b When is an alkenyl group, it preferably has 17 or more carbon atoms and preferably 21 or less carbon atoms. R 1b When is an alkyl group, it preferably has 15 or more carbon atoms and preferably 21 or less carbon atoms. n is preferably 0 or 1. R 2 and R 3 are each independently preferably an alkyl group having 1 to 2 carbon atoms or -(C2H4O) p It is a group represented by H. p is preferably a number between 0 and 3.

[0021] Component (C) contains two or more, preferably five or less, more preferably two, compounds (1) in which X in general formula (1) is different. At least one of the two or more compounds (1) contained in component (C) is a compound in which X in general formula (1) is different from R. 1a or R 1b is an alkenyl group having 14 to 22 carbon atoms, that is, R in X in general formula (1) 1a an alkenyl group having 14 to 22 carbon atoms as R 1b It is a compound containing an alkenyl group having 13 to 21 carbon atoms as the alkyl group.

[0022] In the present invention, there are two types of compound (1), and at least one of the two types of compound (1), including the above (i) to (v), is a compound in which X in the general formula (1) is R 1a and an alkenyl group compound having from 14 to 22 carbon atoms. That is, the powder thickener contains, as component (C), two compounds represented by the general formula (1), wherein X in the general formula (1) of the two compounds is different, and at least one of the two compounds is a compound in which X in the general formula (1) is R 1a and R 1a is an alkenyl group compound.

[0023] The component (C) of the present invention is a compound represented by the general formula (1) in which X is R 1a or R1b -[CONH-CH2CH2CH2] n - (wherein R 1a is an alkenyl group having 14 to 22 carbon atoms, and R 1b is an alkenyl group having from 13 to 21 carbon atoms), and a compound (1b) in which X in the general formula (1) is different from that of compound (1a). Specifically, examples of the powder thickener include a compound (1a) represented by the following general formula (1a) and a compound (1b) represented by the following general formula (1b).

[0024] [ka]

[0025] [During the ceremony, n1 and n2 each independently represent an integer of 0 or more and 3 or less. R 11a When n1 is 0, it is an alkenyl group having 14 to 22 carbon atoms, and when n1 is 1 to 3, it is an alkenyl group having 13 to 21 carbon atoms. R 11b When n2 is 0, it is an alkyl group having 14 to 22 carbon atoms or an alkenyl group having 14 to 22 carbon atoms, and when n2 is 1 to 3, it is an alkyl group having 13 to 21 carbon atoms or an alkenyl group having 13 to 21 carbon atoms. However, if n1 and n2 are the same number, R 11b The alkenyl group in R 11a is an alkenyl group different from R 2 and R 3 are each independently an alkyl group having 1 to 4 carbon atoms or -(C2H4O) p H. p is the average number of moles added, and R 2 and R 3 The sum of these is a number between 0 and 5.

[0026] In general formula (1a), R 11aThe number of carbon atoms is preferably 17 or more and preferably 22 or less. In the general formula (1a), n1 is preferably 0 or 1, and more preferably 0.

[0027] In the general formula (1b), n2 is 0 and R 11b When is an alkyl group, R 11b The number of carbon atoms is preferably 16 or more and preferably 22 or less. In the general formula (1b), n2 is 0 and R 11b When is an alkenyl group, R 11b The number of carbon atoms is preferably 18 or more and preferably 22 or less. In the general formula (1b), n2 is 1 to 3 and R 11b When is an alkyl group, R 11b The number of carbon atoms is preferably 15 or more and preferably 21 or less. In the general formula (1b), n2 is 1 to 3 and R 11b When is an alkenyl group, R 11b The number of carbon atoms is preferably 17 or more and preferably 21 or less. In general formula (1b), R 11b is preferably an alkyl group. In the general formula (1b), n2 is preferably 0 or 1.

[0028] In general formula (1a) or (1b), R 2 and R 3 are each independently preferably an alkyl group having 1 or 2 carbon atoms or -(C2H4O) p It is a group represented by H, and more preferably an alkyl group having 1 or 2 carbon atoms. In the general formula (1a) or (1b), p is preferably a number of 0 or more and 3 or less. If n1 and n2 are the same number, R 11b The alkenyl group in R 11a is an alkenyl group different from

[0029] A preferred example of the component (C) of the present invention is a powder thickener containing a compound (11a) represented by the following general formula (11a) and a compound (1b) represented by the following general formula (1b).

[0030] [ka]

[0031] [During the ceremony, n2 is an integer between 0 and 3 inclusive. R 11a is an alkenyl group having 14 to 22 carbon atoms. R 11b When n2 is 0, it is an alkyl group having 14 to 22 carbon atoms or an alkenyl group having 14 to 22 carbon atoms, and when n2 is 1 to 3, it is an alkyl group having 13 to 21 carbon atoms or an alkenyl group having 13 to 21 carbon atoms. However, if n1 and n2 are the same number, R 11b The alkenyl group in R 11a is an alkenyl group different from R 2 and R 3 are each independently an alkyl group having 1 to 4 carbon atoms or -(C2H4O) p H. p is the average number of moles added, and R 2 and R 3 The sum of these is a number between 0 and 5.

[0032] The compound (11a) represented by the general formula (11a) corresponds to the compound in which n1 is 0 in the general formula (1a). 11a , R 2 and R 3 The preferred embodiments of the compound (1b) are the same as those of the general formula (1a). In this combination, the preferred embodiments of the compound (1b) are the same as those of the general formula (1a).

[0033] In the component (C), the mass ratio of compound (1b) / compound (1a) is preferably 5 / 95 or more, more preferably 25 / 75 or more, even more preferably 40 / 60 or more, and is preferably 95 / 5 or less, more preferably 75 / 25 or less, even more preferably 60 / 40 or less.

[0034] In the component (C), the mass ratio of compound (1b) / compound (11a) is preferably 5 / 95 or more, more preferably 25 / 75 or more, even more preferably 40 / 60 or more, and is preferably 95 / 5 or less, more preferably 75 / 25 or less, even more preferably 60 / 40 or less.

[0035] Component (C) contains compound (1) in an amount of preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and preferably 90% by mass or less, more preferably 70% by mass or less, even more preferably 55% by mass or less, and even more preferably 50% by mass or less.

[0036] When compound (1) is obtained as a liquid containing the compound, this liquid may be supported on a suitable carrier and powdered.

[0037] Component (C) may contain a non-hydraulic inorganic powder, which is a preferred component from the viewpoint of effective anti-caking properties of component (C). Examples of non-hydraulic inorganic powders include one or more selected from amorphous silica, calcium hydroxide, calcium carbonate, silica stone, blast furnace slag, fly ash, and silica fume, and one or more selected from amorphous silica, calcium carbonate, and blast furnace slag are preferred. The component (C) may contain a non-hydraulic inorganic powder in an amount of, for example, 10% by mass or more and 50% by mass or less.

[0038] Component (C) may contain a water-soluble polymer compound. A water-soluble polymer compound is a preferred component from the viewpoint of maintaining the combined effect of components (B) and (C) when component (C) containing compound (1) is used. With regard to the water-soluble polymer compound of component (C), "water-soluble" means that 1 g or more of the compound dissolves in 100 g of water at 20°C. Examples of the water-soluble polymer include cationic polymer compounds such as polyalkylene glycol, polyvinyl alcohol which may be saponified, polyvinylpyrrolidone, polyamidepolyamine / epichlorohydrin condensates, dimethylamine / ammonia / epichlorohydrin condensates, dimethylamine / trimethylamine / epichlorohydrin condensates, vinylpyrrolidone / quaternized dimethylaminoethyl methacrylate copolymers, quaternized polyethyleneimines to which a polyoxyalkylene group may be added, and vinylpyrrolidone / alkylaminoacrylate copolymers, and these may be used alone or in combination of two or more. The weight average molecular weight of the water-soluble polymer compound may be, for example, 500 or more and 500,000 or less. The component (C) can contain a water-soluble polymer compound in an amount of, for example, 10% by mass or more and 50% by mass or less.

[0039] Component (C) may contain an anionic aromatic compound. An anionic aromatic compound is a preferred component from the viewpoint of efficiently exhibiting the thickening effect when using component (C) containing compound (1). Examples of anionic aromatic compounds include salicylic acid, p-toluenesulfonic acid, sulfosalicylic acid, benzoic acid, m-sulfobenzoic acid, p-sulfobenzoic acid, 4-sulfophthalic acid, 5-sulfoisophthalic acid, p-phenolsulfonic acid, m-xylene-4-sulfonic acid, cumenesulfonic acid, methylsalicylic acid, styrenesulfonic acid, and chlorobenzoic acid. These may form salts. Two or more anionic aromatic compounds may be used. The anionic aromatic compound is preferably one or more compounds selected from sulfonic acids having an aromatic ring, carboxylic acids having an aromatic ring, and salts thereof. The salt is preferably an alkali metal salt such as a sodium salt. The component (C) may contain an anionic aromatic compound in an amount of, for example, 0.5% by mass or more and 30% by mass or less.

[0040] The average particle size of component (C) is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, and preferably 500 μm or less, more preferably 250 μm or less, even more preferably 100 μm or less. This average particle size was measured and calculated as the median diameter (D50; μm) using a laser diffraction / scattering particle size distribution analyzer LA-300 (manufactured by Horiba, Ltd.) and ethanol (95) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as the dispersion medium.

[0041] The bulk density of component (C) is preferably 0.01 g / cm 3 More preferably, 0.03 g / cm 3 More preferably, 0.05 g / cm 3 or more, and preferably 0.50 g / cm 3 or less, more preferably 0.30 g / cm 3 More preferably, 0.10 g / cm or less 3 The bulk density is as follows: This bulk density is measured by the cylinder method described in JIS K 6220.

[0042] In the method for producing a clay-containing slurry of the present invention, first, component (A) and component (B) are mixed to obtain a mixture. From the viewpoint of preventing water leakage, the mass ratio (A) / (B) of the amount of component (A) mixed to the amount of component (B) mixed is preferably 5 or more, more preferably 10 or more, even more preferably 15 or more, and is preferably 100 or less, more preferably 70 or less, even more preferably 40 or less.

[0043] In the method for producing a clay-containing slurry of the present invention, the mixture of components (A) and (B) is then mixed with component (C). In the present invention, by mixing component (C) in powder form with the mixture, the effect of the thickener is improved, and a clay-containing slurry with an appropriate viscosity depending on the application can be easily produced.

[0044] In the present invention, for example, after component (B) has been swollen by component (A), component (C) can be mixed into the mixture. The swelling of component (B) can be measured by measuring the particle size distribution using a laser diffraction / scattering particle size distribution analyzer LA-300 (manufactured by Horiba, Ltd.) and ion-exchanged water, which is component (A), as a dispersion medium, and calculating the arithmetic mean volume (μm 3 ) can be judged as being 1.1 times or more as a swelling ratio based on the following formula. Swelling ratio = arithmetic mean volume 2 minutes after adding component (B) / arithmetic mean volume immediately after adding component (B)

[0045] In the present invention, for example, component (C) can be mixed into the mixture after 1 minute or more, further 2 minutes or more, and then 10 minutes or less, further 5 minutes or less have elapsed since mixing component (A) and component (B). In this case, the elapsed time can be determined from the time when component (A) first comes into contact with component (B).

[0046] In the present invention, the (C) component is mixed in an amount of preferably 0.025 parts by mass or more, more preferably 0.050 parts by mass or more, even more preferably 0.100 parts by mass or more, and preferably 10.0 parts by mass or less, more preferably 5.0 parts by mass or less, even more preferably 2.5 parts by mass or less, per 100 parts by mass of the (A) component.

[0047] When component (C) is a powder thickener containing compound (1), component (C) is mixed in an amount of preferably 0.25 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1.0 part by mass or more, and preferably 10.0 parts by mass or less, more preferably 5.0 parts by mass or less, even more preferably 2.5 parts by mass or less, per 100 parts by mass of component (A).

[0048] When component (C) is a powder thickener containing compound (1), component (C) is mixed so that the amount of compound (1) in component (C) is preferably 0.05 parts by mass or more, more preferably 0.10 parts by mass or more, even more preferably 0.20 parts by mass or more, and preferably 10.0 parts by mass or less, more preferably 5.0 parts by mass or less, even more preferably 2.0 parts by mass or less, per 100 parts by mass of component (A).

[0049] In the present invention, components other than the components (A) to (C) can also be used. In the present invention, a pH adjuster (D) (hereinafter referred to as component (D)) can be mixed. That is, the multiple components mixed in the production method of the present invention may further contain component (D). Note that component (D) is a component that is mixed separately from components (A) to (C). Examples of component (D) include metal hydroxides such as calcium hydroxide, sodium hydroxide, and potassium hydroxide, metal oxides such as calcium oxide, and organic compounds having an amino group such as alkanolamines.

[0050] Furthermore, in the present invention, as long as the effects of the present invention are not impaired, a component that functions as a pH adjuster in water, such as a substance that releases a component that becomes an alkaline or acidic agent, can be used as component (D) separately from components (A) to (C). For example, cement known as a hydraulic powder can be used as the alkaline agent. Examples of cement include ordinary Portland cement, high-early-strength Portland cement, ultra-high-early-strength Portland cement, sulfate-resistant Portland cement, low-heat Portland cement, white Portland cement, and ecocement (e.g., JIS R5214). When cement is used as component (D), it is preferably mixed in an amount of at least 10 parts by mass, more preferably at least 30 parts by mass, even more preferably at least 50 parts by mass, and preferably at most 200 parts by mass, more preferably at most 150 parts by mass, and even more preferably at most 100 parts by mass, per 100 parts by mass of component (B).

[0051] In the present invention, it is preferable to first mix component (A) and component (B) among the multiple components used to prepare the clay-containing slurry to obtain a mixture, and then mix the remaining components, i.e., component (C) and optional components as necessary, with the mixture. It is also preferable to first mix the entire amounts of components (A) and (B) used to prepare the slurry.

[0052] The clay-containing slurry produced according to the present invention may have a viscosity at 20°C of, for example, 50 mPa·s or more, even 100 mPa·s or more, even 150 mPa·s or more, and 2,000 mPa·s or less, even 1,500 mPa·s or less, even 1,000 mPa·s or less.

[0053] The clay-containing slurry produced by the present invention can be used for various purposes, taking into consideration the type and properties of the clay. The clay-containing slurry produced by the present invention is suitable as a drilling fluid. Therefore, the present invention may be a method for producing a drilling fluid. The drilling fluid here may be used as a drilling stabilization fluid, a pile periphery fixing fluid, etc. [Example]

[0054] <Example 1 and Comparative Example 1> (1) Materials used The following components (A) to (C) and (D) were used.

[0055] <Component (A): Water> Tap water (Wakayama City, Wakayama Prefecture)

[0056] <(B) Component: Clay Minerals> Kunigel GS (Kunimine Industries Co., Ltd.)

[0057] <Component (C): Powdered thickener> The following compound (1), non-hydraulic inorganic powder, water-soluble polymer, and aromatic sulfonate were used in amounts shown in Tables 1 and 2 per 100 parts by mass of component (A), and mixed in a coffee mill GCM-56 (Device Style Holdings) for 1 minute until the powder became homogeneous, and then passed through a sieve with 600 μm openings. [Compound (1)] Amphoteric surfactant 1: oleyldimethylamine oxide (in general formula (1a), R 11a : Alkenyl group with 18 carbon atoms (oleyl group), n1: 0, R 2 : Methyl group, R 3 : methyl group) Amphoteric surfactant 2: oleic acid amidopropyl dimethylamine oxide (in general formula (1a), R 11a : Alkenyl group having 17 carbon atoms, n1:1, R 2 : Methyl group, R 3 : methyl group) [Non-hydraulic inorganic powder] Non-hydraulic inorganic powder 1: Nipsil NS-K (manufactured by Tosoh Silica Corporation) Non-hydraulic inorganic powder 2: Esment 4000 (manufactured by Nippon Steel Blast Furnace Cement Co., Ltd.) [Water-soluble polymer] Water-soluble polymer 1: Polyethylene glycol 4,000 (Fujifilm Wako Pure Chemical Industries, Ltd.) Water-soluble polymer 2: Poly(ethylene oxide), average MV 200,000, powder, manufactured by Merck KGaA [Aromatic sulfonates] Sodium meta-xylene sulfonate, SXS-Y (manufactured by Itochu Chemical Frontier Corporation)

[0058] <Component (D): pH adjuster> Ordinary Portland cement (specific gravity 3.16, manufactured by Taiheiyo Cement Corporation)

[0059] (2) Preparation of clay-containing slurry The components (A) and (B) were placed in a 2000 mL disposable cup in the parts by weight listed in Table 1, and mixed and stirred for 2 minutes at 950 rpm using a hand mixer MK-H4-W (Panasonic Corporation) to prepare a mixture. The powdered components (C) and, if necessary, (D) were added to this mixture in the parts by weight listed in Table 1, and further mixed and stirred for 1 minute at 950 rpm to prepare the clay-containing slurries of the examples. The mixing method used in the examples is indicated as "sequential" in the table. In Comparative Examples 1-15, a liquid containing compound (1) and water was used as component (C), and the mixture was mixed in the same "sequential" manner as in the examples. The clay-containing slurry of the comparative example was prepared by adding components (A), (B), (C), and optionally (D) all at once in the parts by weight shown in Table 2 to a 2000 mL disposable cup and mixing and stirring at a rotation speed of 950 rpm for 3 minutes. The mixing method of the comparative example is indicated as "all at once" in the table.

[0060] (3) Water loss test method for clay-containing slurry A 50 mL dropping funnel was filled with 45 g of No. 3 silica sand with the stopcock sealed, and 25 mL of the clay-containing slurry prepared by the method described in (2) was poured into it from the top, and the liquid level H0 (mL) before the start of the water loss test was recorded. The dropping funnel's stopcock was then opened, and the liquid level H10 (mL) 10 minutes after the start of the water loss test was recorded, and the residual rate (%) was calculated using the following formula as an index of water loss prevention. The results are shown in Tables 1 and 2. Survival rate (%)=(H10 / H0)×100 H10: Liquid level 10 minutes after the start of the water loss test (mL) H0: Liquid level before the start of the water loss test (mL)

[0061] [Table 1]

[0062] [Table 2]

[0063] *1 Parts by weight per 100 parts by weight of component (A) *2 Parts by mass per 100 parts by mass of the total of components (A), (B), and (D). *3 Component (C) was added and mixed in liquid form.

[0064] The results in the table show that when using the same composition and thickener, producing a clay-containing slurry using the mixing method of the Examples results in a higher residual rate than the Comparative Examples, resulting in excellent water leakage prevention. This is thought to be because, by mixing components (A) and (B) first, component (B) swells sufficiently, while component (C) effectively thickens the reduced free water. The residual rate values ​​in the table show that the Examples are significantly higher than the Comparative Examples, and even a difference of a few percent would be recognized as a significant difference by those skilled in the art.

Claims

1. A method for producing a clay-containing slurry, comprising mixing a plurality of components including (A) water (hereinafter referred to as component (A)), (B) a swelling clay mineral (hereinafter referred to as component (B)), and (C) a powdered thickener (hereinafter referred to as component (C)), the mass ratio (A) / (B) of the amount of the component (A) mixed to the amount of the component (B) mixed is 15 or more and 100 or less; The component (C) contains two types of compounds represented by the following general formula (1) in a mass ratio of 5 / 95 or more and 95 / 5 or less, the two types of compounds having different Xs in the general formula (1), and at least one of the two types of compounds is a compound in which R 1a or R 1b of X in the general formula (1) is an alkenyl group; 【Chemistry 1】 [In the formula, X is R 1a or a group represented by R 1b -[CONH-CH 2 CH 2 CH 2 ] n -. R 1a is an alkyl group having 14 to 22 carbon atoms or an alkenyl group having 14 to 22 carbon atoms. R 1b is an alkyl group having 13 to 21 carbon atoms or an alkenyl group having 13 to 21 carbon atoms. n is an integer of 1 to 3. R 2 and R 3 are each independently an alkyl group having 1 to 4 carbon atoms or a group represented by -(C 2 H 4 O) pH. p is the average number of moles added, and the total of R 2 and R 3 is a number of 0 to 5.] Component (A) and component (B) are mixed to form a mixture, and after component (B) has swelled with component (A), component (C) is mixed into the mixture. Method for producing clay-containing slurry for pile drilling fluid.

2. The method for producing a clay-containing slurry for pile drilling fluid according to claim 1 , wherein the plurality of components further comprises (D) a pH adjuster.

3. 3. The method for producing a clay-containing slurry for pile drilling fluid according to claim 1 or 2, wherein component (C) is mixed with the mixture after 1 minute or more and 10 minutes or less have elapsed since component (A) and component (B) were mixed.

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