Acrylic acid (CO)polymer, method for producing same and use

Abstract

The invention relates to an acrylic acid (co)polymer having a degree of hydrolysis of from 50% to 100% and a percentage ratio of high molecular weight fraction to low molecular weight fraction in a range of from 5 to 9, and further relates to a method for producing said acrylic acid (co)polymer, and to the use thereof in the field of drilling fluids as an additive for improving the fluid loss control capability of such fluids, and in the field of mineral processing as a flocculant for thickening tailings slurries during beneficiation by flotation. The invention makes it possible to reduce dilling fluid filtrate loss in the field of oil extraction, and to increase the recovery of valuable materials in the field of mineral processing.

Description

[0001] (CO) POLYMER OF ACRYLIC ACID, METHOD OF ITS PRODUCTION AND APPLICATION

[0002] Field of technology to which the invention relates The present invention relates to a (co)polymer of acrylic acid, a method for producing it and its use in drilling mud segments as an additive for improving their filtration capacity and in the mining and processing segment as a flocculant for thickening flotation tailings.

[0003] State of the art

[0004] Acrylic acid (AA) polymer products such as homo- and copolymers are used in a wide range of applications from pharmaceuticals to oil production due to the wide range of properties these products possess.

[0005] The variability of the properties of (co)polymers of AC is primarily due to their molecular weight, which can vary from 1,000 to 5,000,000 g / mol. For example, low-molecular-weight products with a weight of up to 10,000 g / mol can be used as scale inhibitors in water supply systems, as they are capable of binding to hardness salts in water; medium-molecular-weight products with a weight of, for example, 100,000 g / mol can be used as viscosity reducers for various media; and high-molecular-weight (co)polymers with a weight of 1,000,000 g / mol can be used as water absorbents and sorbents in medicine, personal hygiene products, etc.

[0006] In the oil production process, acrylic (co)polymers can be used as components that change the viscosity of drilling fluids, as well as increase the temperature and salt resistance of the solution.

[0007] Acrylic (co)polymers are also important components in oil production, where they are used as additives that improve the properties of drilling fluids. These (co)polymers are used as components that enhance the temperature and salt resistance of drilling fluids, as thinners and thickeners, and as filtration rate reducers.

[0008] Today, numerous additives are known that can reduce filtrate recovery, such as modified starches or cellulose, as well as their derivatives. Filtrate recovery with these additives is reduced by increasing the viscosity of the drilling fluid, which in turn significantly limits their applicability to water-flooded formations.

[0009] The uniqueness of the use of acrylic (co) polymers in drilling fluids lies in the ability of the polymer to create a flexible and dense filtration film on the walls of the formation, which does not allow the solution or "filtrate" to enter the formation, thereby reducing its loss and reducing water consumption, but without increasing the viscosity of the solution if this is not necessary.

[0010] Another unique property of acrylic products is their ability to act as flocculants—substances capable of forming large aggregates of small particles of the dispersed phase into flakes, thereby accelerating the separation of impurities from water and forming a large, dense sediment.

[0011] The applications of such substances can be varied, from the treatment of wastewater, which can contain significant amounts of suspended solids, which often take a long time to settle, to the extraction of precious metals, coal, etc.

[0012] At mining and processing plants (MPP), an important task is the formation of a concentrate from waste (tailings) obtained as a result of the extraction of valuable components. (Co)polymers of acrylic acid as a flocculant increase the efficiency of thickening by 2-4 times, and sometimes by 10 times and make it possible to obtain more concentrate and clarified recycled water, which can be repeatedly used in the technological process. The closest to the present solution is the invention known from EA 044955, which discloses a water-soluble polymer of acrylamide or a copolymer of acrylamide and acrylic acid, which is characterized by an average molecular weight of at least 0.5 million daltons (500,000 g / mol) and which can be used in the oil and gas industry, water purification, sludge dewatering, and the mining industry.

[0013] The main disadvantage of this known invention is that the polymer is presented in the form of an aqueous dispersion, which makes it inconvenient to use, for example, for drilling fluids due to the need to transport and load a large volume of the component at its low concentration.

[0014] The second important disadvantage is the need to add to the aqueous dispersion a mixture of at least one sulfuric acid salt and at least one phosphoric acid salt in strictly defined proportions, since only in the presence of this additive does the dispersion acquire its universal properties.

[0015] The development of an acrylic acid (co)polymer with universal properties appears to be the most feasible for the two segments described above. Such a product will reduce energy costs for the production of high-molecular-weight and high-viscosity components that require more stringent production and drying conditions.

[0016] Disclosure of invention

[0017] The present invention was based on the task of obtaining (co)polymers of acrylic acid that could be used in various segments due to their universal properties, for example, as an additive to drilling fluids or as a flocculant in the mining and processing segment.

[0018] The technical result of the present invention consists in reducing the filtrate recovery of drilling fluids in the oil production segment and thickening tailings pulps in the mining and processing segment.

[0019] Brief description of the drawings

[0020] To explain the technical solutions that reveal the essence of the present invention, Figs. 1 and 2 are attached to the description.

[0021] Fig. 1 shows a chromatogram reflecting the molecular weight distribution of the acrylic acid polymer obtained in Examples 1-5, 9.

[0022] Fig. 2 shows a chromatogram reflecting the molecular weight distribution of the acrylic acid copolymer obtained in Examples 6-8.

[0023] Detailed description of the invention

[0024] Various embodiments of the invention are given below.

[0025] The object of the invention is (co)polymers of acrylic acid with a degree of hydrolysis ranging from 50 to 100% and with a percentage ratio of high molecular weight fraction to low molecular weight fraction in the range from 5 to 9.

[0026] In a preferred embodiment, the degree of hydrolysis (co) of the acrylic acid polymers is from 55 to 99%, more preferably from 60 to 95%.

[0027] The percentage ratio of high molecular weight fraction to low molecular weight fraction is preferably in the range of 5.5 to 7.5, more preferably from 6 to 7.

[0028] The (co)polymers proposed in the invention, which are optionally copolymers of acrylic acid with monomers selected from the group of α,β-ethylenically unsaturated monomers suitable for radical polymerization. The corresponding monomers are selected from the group of amides of α,β-ethylenically unsaturated monocarboxylic and dicarboxylic acids with amino alcohols with 2-30 carbon atoms having a primary or secondary amino group, primary amides of α,β-ethylenically unsaturated monocarboxylic acids and their N-alkyl and N,N-dialkyl derivatives, N-vinyl lactams, N-vinyl amide compounds with an open chain, esters of allyl alcohol with monocarboxylic acids with 1-30 carbon atoms, esters of α,β-ethylenically unsaturated monocarboxylic and dicarboxylic acids with amino alcohols, amides of α,β-ethylenically unsaturated monocarboxylic and dicarboxylic acids with diamines having at least one primary or secondary amino group, N,N-diallylamines, N, N-diallyl-N-alkylamines, nitrogen heterocycles,substituted with vinyl and allyl, vinyl ethers, monoolefins with 2-8 carbon atoms, non-aromatic hydrocarbons with at least two conjugated double bonds, polyether (meth) acrylates, monomers with urea groups and mixtures thereof.,

[0029] Examples of suitable primary amides of a, p-ethylenically unsaturated monocarboxylic acids and their N-alkyl and N, N-dialkyl derivatives include acrylic acid amide, methacrylic acid amide, methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N-(n-butyl) (meth) acrylamide, N-(tert-butyl) (meth) acrylamide, N-(n-octyl) (meth) acrylamide, N-(1, 1, 3, 3-tetramethylbutyl) (meth) acrylamide, N-ethylhexyl (meth) acrylamide, N-(n-nonyl) (meth) acrylamide, N-(n-decyl) (meth) acrylamide, N-(n-undecyl) (meth) acrylamide, N-tridecyl-(meth)acrylamide, N-myristyl (meth)acrylamide, N-pentadecyl (meth)-acrylamide, N-palmityl (meth)acrylamide, N-heptadecyl (meth)acrylamide, N-nonadecyl (meth)acrylamide, N-arachininyl (meth)acrylamide, N-behenyl (meth)acrylamide, N-lignoceryl (meth)acrylamide, N-cerotinyl (meth)acrylamide, N-melissinyl (meth)acrylamide, N-palmitoleinyl (meth)acrylamide, N-oleyl (meth)acrylamide, N-linolyl (meth)acrylamide,N-linolenyl (meth) acrylamide, N-stearyl (meth) acrylamide, N-lauryl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, morpholinyl (meth) acrylamide. The (co)polymers according to the invention are preferably a polymer of acrylic acid or a copolymer of acrylic acid with acrylamide.

[0030] The comonomer content does not exceed 50 mass % based on the total monomer content.

[0031] The comonomer content preferably does not exceed 30 mass % based on the total monomer content.

[0032] The high molecular weight fraction according to the invention is a fraction with a molecular weight of from 100,000 g / mol, preferably from 100,000 to 1,000,000 g / mol, more preferably from 100,000 to 900,000 g / mol.

[0033] The low molecular weight fraction according to the invention is a fraction with a molecular weight of up to 100,000 g / mol.

[0034] The second object of the invention is a method for obtaining

[0035] (co) polymers of acrylic acid. This method of obtaining

[0036] (co) of acrylic acid polymers in an aqueous medium is distinguished by the fact that it involves the following stages:

[0037] I) loading water, acrylic acid, optionally one or two monomers and an initiator with stirring,

[0038] II) optionally re-loading one or two monomers followed by loading of the initiator with stirring,

[0039] III) optionally re-adding the initiator,

[0040] IV) after completion of the reaction, adding the main compound to the aqueous solution,

[0041] V) optionally drying the resulting solution.

[0042] The loading of water, acrylic acid, optionally one or two monomers and initiator can be carried out sequentially or simultaneously.

[0043] Acrylic acid can be in an acidic, non-neutralized form.

[0044] Any initiator used for (co)polymerization of acrylic monomers can be used as an initiator, for example, inorganic and organic peroxide compounds such as sodium persulfate, potassium persulfate, ammonium persulfate, hydrogen peroxide, di-tertiary butyl peroxide, cumene hydroperoxide, benzoyl peroxide, sodium thiosulfate, sodium hydrosulfite, etc.

[0045] In a preferred embodiment, sodium, potassium, or ammonium persulfates are used as the initiator. In a more preferred embodiment, sodium persulfate is used.

[0046] The initiator can be supplied in dry or solution form.

[0047] The initiator is added to the reaction medium in two, or optionally three, stages, in an amount of 0.7 to 1.0% of the total monomer mass. In the first stage, the initiator is added in an amount of 0.25 to 0.5% of the total monomer mass, and in the second and optionally third stages, the remaining amount is added. Adding the initiator in the specified amounts in the first stage allows for the production of a (co)polymer with reduced viscosity, which dries more quickly during the drying stage.

[0048] The method proposed in the invention is carried out in a periodic or semi-periodic mode.

[0049] According to the invention, in stages I) and II), the reaction mass is heated to a temperature of 50-90°C, preferably 65-75°C, after which self-heating of the mass occurs.

[0050] The process is carried out at atmospheric pressure, but it can also be carried out at reduced or increased pressure.

[0051] According to the invention, in stages I) and II), the reaction mass is stirred for 1-10 hours, preferably 1-5 hours.

[0052] Optionally, before carrying out stage II) the mixture is cooled to 25-30°C.

[0053] Upon completion of the reaction, a basic compound is added to adjust the pH of the product to 3-9, preferably 5-7. Aqueous solutions with a concentration of 30-50 wt.% are preferably used as the basic compound. This range is optimal in terms of minimizing the formation of by-products, since adding a smaller amount of the basic compound will increase the amount of water in the final product.

[0054] Sodium or potassium hydroxides, ammonia or amines, preferably triethanolamine, are used as the main compound.

[0055] The (co) acrylic acid polymer obtained by the above-described method has a weight average molecular weight in the range of 100,000 to 900,000 g / mol, preferably 400,000 to 800,000 g / mol, most preferably 600,000 to 700,000 g / mol.

[0056] Obtaining solutions with a molecular weight greater than 900,000 g / mol will increase viscosity and decrease the product's solubility in water, making it difficult to use in drilling fluids due to uneven distribution. Molecular weight values ​​below 100,000 g / mol will increase filtrate recovery and reduce flocculation properties.

[0057] The drying stage can produce various product forms depending on the required parameters. The product can be converted into powder, granules, fibers, etc.

[0058] Drying can be carried out by various methods, such as spray drying, roller drying or paddle drying.

[0059] Another object of the invention is the use of the above-mentioned (co)polymer of acrylic acid in the drilling fluid segment as an additive for reducing fluid loss.

[0060] The object of the invention is further the use of the above-mentioned (co)polymer of acrylic acid in the mining and processing segment as a flocculant for thickening tailings pulps of flotation enrichment.

[0061] Acrylic polymers are added to drilling fluids as a component that reduces their filtration into the formation, in an amount of 0.1 to 1.0 mass%. The consumption of flocculants for thickening tailings pulps is usually 10-50 g / t.

[0062] Implementation of the invention

[0063] 1. Determination of molecular weight characteristics of acrylic acid-based polymers by gel permeation chromatography

[0064] The method is applicable to polyacrylic acid with an average molecular weight from 2000 to 1,000,000 g / mol.

[0065] Materials, reagents and auxiliary equipment:

[0066] - distilled water;

[0067] - sodium chloride (NaCl);

[0068] - a set of calibration standards of polyacrylic acid PSS Standards Kit in the molecular weight range from 2000 to 1,000,000 g / mol.

[0069] Preparation of eluent

[0070] For the buffer solution, a 2.9 g sample of sodium chloride is dissolved in 1 liter of distilled water.

[0071] Parameters for instrument calibration and chromatographic analysis

[0072] PLaquagel-OH MIXED-M analytical column, 300 mm long, 7.5 mm internal diameter, 8 µm particle size

[0073] No. 0006541038-67 (if peaks broaden and results differ from previous ones, the column must be replaced).

[0074] Measurements are performed in an isocratic eluent feed mode with the following chromatograph operating parameters:

[0075] - solvent feed rate 1.0 ml / min;

[0076] - column thermostat temperature 35°C;

[0077] - refractometer cell temperature 40 °C;

[0078] - chromatography time 15 min;

[0079] - volume of injected sample 80 µl.

[0080] Construction of a calibration curve PSS Standards Kit acid calibration standards are prepared at a concentration of 0.15-0.2 mg / ml, which corresponds to approximately 1 mg of standard per 6 ml of distilled water.

[0081] To construct a calibration curve, each of the diluted solutions is chromatographed at least twice.

[0082] Next, using the instrument’s software, a calibration dependence is constructed (to construct a calibration graph, you can use a 2nd or 3rd degree polynomial or a linear dependence, check the calibration using the SOKOLAN SR-10 reference sample (3000-3100) for low-molecular polyacrylates and the SP-101 reference (450000-520000) for high-molecular polyacrylates and copolymers, as well as by processing standard samples).

[0083] Taking measurements

[0084] When taking measurements, the following operations are performed.

[0085] The chromatograph is turned on in accordance with the operating manual and brought into operating mode.

[0086] A sample of polyacrylic acid weighing approximately 10 mg is weighed on an electronic scale to the second decimal place and transferred to a conical flask to prepare a solution.

[0087] The sample must be collected with a clean instrument. Using a dispenser, add 10 ml of distilled water to the flask, place it on a magnetic stirrer, and stir until the sample is completely dissolved (at least 15 minutes). Transfer the sample solution to the vial using a disposable syringe, simultaneously filtering it through a nylon filter with a 0.45 µm mesh size. Place the vial containing the sample in the instrument's autosampler.

[0088] For each sample, 2 samples are prepared for analysis.

[0089] A solvent, which is water (an “empty” vial), is placed in a separate vial and placed in the autosampler in front of the vials with the sample.

[0090] The peak intensities of samples, standards, and references should be within the same range from 1500 to 3500. The ratio of mass ranges is determined using a cumulative curve. Specific mass intervals are selected for sample comparison. Thus, the high-molecular-weight fraction according to the invention is a fraction with a molecular weight of 100,000 g / mol, preferably from 100,000 to 1,000,000 g / mol, more preferably from 100,000 to 700,000 g / mol, and the low-molecular-weight fraction is a fraction with a molecular weight of less than 100,000 g / mol.

[0091] 2. Determination of the degree of hydrolysis

[0092] The method is based on direct titration of carboxyl groups of acrylamide polymer in an aqueous solution with alkali [Bondarenko A.V., "Experimental support of pilot industrial work to substantiate polymer flooding technology under conditions of high mineralization of formation and injected waters", dissertation, Moscow, 2017, 154 p.]. Measurement range is 1-32%.

[0093] Equipment, reagents and materials:

[0094] - analytical scales with a weighing accuracy of 0.0001 g;

[0095] - paddle mixer for highly viscous media;

[0096] - titration unit according to GOST 29251-91;

[0097] - magnetic stirrer;

[0098] - pH meter with a measurement error of 0.05;

[0099] - cylinder 1-3-100-2 according to GOST 1770;

[0100] - glass B-1-150 according to GOST 25336;

[0101] - burettes 1-5-1-10, 1-3-2-25-01 according to GOST 29251;

[0102] - 0.1 molar solution of NS, prepared from a standard titer according to GOST 25794.1-83;

[0103] - 0.05 molar NaOH solution prepared according to GOST 25794. 1-83;

[0104] - distilled water according to GOST 6709.

[0105] For analysis, a polymer solution with a concentration of 0.05-0.1% in distilled water is used. The polymer weight is calculated taking into account the mass fraction of the main substance according to

[0106] S-R

[0107] formula t = - ,

[0108]

[0109] Where

[0110] C – polymer concentration in solution, %;

[0111] P is the mass of the polymer solution required for analysis, g;

[0112] W is the mass fraction of the main substance in the polymer, % .

[0113] The calculated polymer sample is weighed on an analytical balance to three decimal places. Distilled water is poured into a beaker in the volume required for the analysis, minus the mass of the polymer sample. The beaker is placed under a paddle stirrer and stirred at a speed sufficient to create a vortex. The polymer sample is poured evenly onto the rim of the funnel and dissolved until completely homogenized, visually assessing the dissolution by the absence of polymer globules and the uniformity of the solution. A 200 cm sample is used for analysis. 3Polymer solution. The hydrogen ion activity is measured and adjusted to pH 3.8 with hydrochloric acid. Potentiometric titration is then performed with sodium hydroxide solution to pH 7.5. The volume of NaOH solution used to titrate the polymer solution is measured. A control measurement is simultaneously performed on a blank sample with an identical volume of distilled water, following the same procedures as with the working polymer sample.

[0114] The degree of polymer hydrolysis in percent is calculated using the formula:

[0115] (7 - 70) ■ C ■ 71 ■ 10“ 3

[0116] a = ■ 100 [ %],

[0117] tp — (V — V o ) ■ C ■ 23 ■ IO' 3

[0118] Where

[0119] V and V o - volumes of NaOH solution used for titration of the working and blank samples, respectively, ml;

[0120] m is the mass of the polymer sample contained in the solution taken for titration, g;

[0121] C is the exact molar concentration of NaOH solution, mol / l;

[0122] 71 - molar mass of the acrylamide unit, g / mol;

[0123] 23 - gram-molecular mass of sodium, g / mol;

[0124] 1SG 3 - conversion factor from cm 3 in dm 3 The result of the analysis is the arithmetic mean of two parallel measurements, the discrepancy between which does not exceed 0.5%. The degree of rounding of the measurement result is 0.1%.

[0125] 3. Filtration properties of drilling fluids Filtration properties were determined according to GOST 33213-2014 (ISO 10414-1: 2008) "Monitoring of drilling fluid parameters under field conditions". The following clay solution was used in the study: water - 336 g, sodium bicarbonate -1 g, PBMB clay powder - 14 g, calcium carbonate MK-10 - 40 g. The products from examples 1-6 were added to the clay solution in an amount of 0.2 wt. % . Thermostating was carried out in a roller furnace at a temperature of 110 ° C for 16 hours. When measuring the filtration properties in a saline solution, a saturated sodium chloride solution was used.

[0126] Below, the present invention is explained in more detail using examples, which merely illustrate the invention but do not limit its scope.

[0127] Example 1 (according to the invention): Synthesis of an acrylic acid homopolymer

[0128] The synthesis is carried out in a 2000 ml glass flask. 720 g of distilled water, 80 g of acrylic acid, and 0.21 g of sodium persulfate in the form of a 35% aqueous solution are added to it. The mixture is heated to 75°C with stirring, after which self-heating occurs. The reaction mixture is maintained at a temperature of 75-80°C with vigorous stirring. After 1 hour, the reaction mass is cooled to 25-30°C, an additional 80 g of acrylic acid and 0.21 g of sodium persulfate in the form of a 35% aqueous solution are added, and the mixture is heated to 75°C with stirring, after which self-heating occurs. The reaction mixture is maintained at a temperature of 75-80°C. After 1 hour, 0.21 g of sodium persulfate in the form of a 35% aqueous solution is added. The reaction mixture is then maintained for another 1 hour at a temperature of 75-80°C. It is then neutralized to a pH of 8.0-8.5 with an aqueous solution of sodium hydroxide.After drying in a screw dryer, 215 g of straw-colored powder with a residual water content of 2.6 wt. % is obtained.

[0129] Example 2 (according to the invention): Synthesis of an acrylic acid homopolymer

[0130] The synthesis is carried out in a 2000 ml glass flask. 720 g of distilled water, 80 g of acrylic acid, and 0.21 g of sodium persulfate in the form of a 35% aqueous solution are added to it. The mixture is heated to 75°C with stirring, after which self-heating occurs. The reaction mixture is maintained at a temperature of 75-80°C with vigorous stirring. After 1 hour, the reaction mass is cooled to 25-30°C, an additional 80 g of acrylic acid and 0.35 g of sodium persulfate in the form of a 35% aqueous solution are added, and the mixture is heated to 75°C with stirring, after which self-heating occurs. The reaction mixture is maintained at a temperature of 75-80°C. After 1 hour, 0.42 g of sodium persulfate in the form of a 35% aqueous solution is added. The reaction mixture is then maintained for another 1 hour at a temperature of 75-80°C. It is then neutralized to a pH of 5.5-6.0 with an aqueous solution of sodium hydroxide.After drying in a screw dryer, 217 g of straw-colored powder with a residual water content of 3.5 wt. % is obtained.

[0131] Example 3 (according to the invention): Synthesis of an acrylic acid homopolymer

[0132] The synthesis is carried out in a 2000 ml glass flask. 720 g of distilled water, 80 g of acrylic acid, and 0.21 g of sodium persulfate in the form of a 35% aqueous solution are added to it. The mixture is heated to 75°C with stirring, after which self-heating occurs. The reaction mixture is maintained at a temperature of 75-80°C with vigorous stirring. After 1 hour, the reaction mass is cooled to 25-30°C, an additional 80 g of acrylic acid and 0.30 g of sodium persulfate in the form of a 35% aqueous solution are added, and the mixture is heated to 75°C with stirring, after which self-heating occurs. The reaction mixture is maintained at a temperature of 75-80°C. After 1 hour, 0.21 g of sodium persulfate in the form of a 35% aqueous solution is added. The reaction mixture is then maintained for another 1 hour at a temperature of 75-80°C. It is then neutralized to a pH of 7.0-7.5 with an aqueous solution of sodium hydroxide.After drying in a screw dryer, 218 g of straw-colored powder with a residual water content of 3.9 wt. % is obtained.

[0133] Example 4 (according to the invention): Synthesis of an acrylic acid homopolymer

[0134] The synthesis is carried out in a 2000 ml glass flask. 720 g of distilled water, 80 g of acrylic acid, and 0.21 g of sodium persulfate in the form of a 35% aqueous solution are added to it. The mixture is heated to 75°C with stirring, after which self-heating occurs. The reaction mixture is maintained at a temperature of 75-80°C with vigorous stirring. After 1 hour, the reaction mass is cooled to 25-30°C, an additional 80 g of acrylic acid and 0.21 g of sodium persulfate in the form of a 35% aqueous solution are added, and the mixture is heated to 75°C with stirring, after which self-heating occurs. The reaction mixture is maintained at a temperature of 75-80°C. After 1 hour, 0.21 g of sodium persulfate in the form of a 35% aqueous solution is added. The reaction mixture is then maintained for another 1 hour at a temperature of 75-80°C. It is then neutralized to a pH of 5.0-5.5 with an aqueous solution of sodium hydroxide.In this way, 990 g of a viscous liquid of straw color with a content of the main substance of 19.2 mass % is obtained. Example 5 (according to the invention): Synthesis of a homopolymer of acrylic acid.

[0135] The synthesis is carried out in a 2000 ml glass flask. 720 g of distilled water, 80 g of acrylic acid and 0.21 g of sodium persulfate in the form of a 35% aqueous solution are added to it. The mixture is heated to 75 °C with stirring, after which self-heating occurs. The reaction mixture is maintained at a temperature of 75-80 °C and vigorously stirred. After 1 hour, the reaction mass is cooled to 25-30 °C, an additional 80 g of acrylic acid and 0.21 g of sodium persulfate in the form of a 35% aqueous solution are added and the mixture is heated to 75 °C with stirring, after which self-heating occurs. The reaction mixture is maintained at a temperature of 75-80 °C. After 1 hour, 0.21 g of sodium persulfate in the form of a 35% aqueous solution is added. The reaction mixture is then maintained for another 1 hour at 75-80°C. It is then neutralized to a pH of 8.0-8.5 with an aqueous solution of sodium hydroxide.In this way, 1050 g of a viscous liquid of straw color with a content of the main substance of 19.8 mass % is obtained.

[0136] Example 6 (according to the invention): Synthesis of acrylic acid copolymer

[0137] The synthesis is carried out in a 2000 ml glass flask. 900 g of distilled water, 70 g of acrylic acid, 30 g of acrylamide and 0.26 g of sodium persulfate in the form of a 35% aqueous solution are added to it. The mixture is heated to 75 °C with stirring, after which self-heating occurs. The reaction mixture is maintained at a temperature of 75-80 °C and vigorously stirred. After 1 hour, the reaction mass is cooled to 25-30 °C, an additional 42 g of acrylic acid, 18 g of acrylamide and 0.15 g of sodium persulfate in the form of a 35% aqueous solution are added and the mixture is heated to 75 °C with stirring, after which self-heating occurs. The reaction mixture is maintained at a temperature of 75-80 °C. After 1 hour, 0.41 g of sodium persulfate, based on the monomer mass, is added as a 35% aqueous solution. The reaction mixture is then maintained for another 1 hour at 75-80°C.

[0138] Next, it is neutralized to a pH of 5.0-5.5 with an aqueous solution of sodium hydroxide. After drying in a screw dryer, 261 g of straw-colored powder with a residual water content of 4.9 wt. % is obtained.

[0139] Example 7 (according to the invention): Synthesis of acrylic acid copolymer

[0140] The synthesis is carried out in a 2000 ml glass flask. 900 g of distilled water, 70 g of acrylic acid, 30 g of acrylamide and 0.26 g of sodium persulfate in the form of a 35% aqueous solution are added to it. The mixture is heated to 75 °C with stirring, after which self-heating occurs. The reaction mixture is maintained at a temperature of 75-80 °C and vigorously stirred. After 1 hour, the reaction mass is cooled to 25-30 °C, an additional 42 g of acrylic acid, 18 g of acrylamide and 0.15 g of sodium persulfate in the form of a 35% aqueous solution are added and the mixture is heated to 75 °C with stirring, after which self-heating occurs. The reaction mixture is maintained at a temperature of 75-80 °C. After 1 hour, 0.30 g of sodium persulfate, based on the monomer mass, is added as a 35% aqueous solution. The reaction mixture is then maintained for another 1 hour at 75-80°C.

[0141] Next, it is neutralized to a pH of 6.0-6.5 with an aqueous solution of sodium hydroxide. After drying in a screw dryer, 256 g of straw-colored powder with a residual water content of 2.8 wt. % is obtained.

[0142] Example 8 (according to the invention): Synthesis of acrylic acid copolymer

[0143] The synthesis is carried out in a 2000 ml glass flask. 900 g of distilled water, 70 g of acrylic acid, 30 g of acrylamide and 0.26 g of sodium persulfate in the form of a 35% aqueous solution are added to it. The mixture is heated to 75 °C with stirring, after which self-heating occurs. The reaction mixture is maintained at a temperature of 75-80 °C and vigorously stirred. After 1 hour, the reaction mass is cooled to 25-30 °C, an additional 42 g of acrylic acid, 18 g of acrylamide and 0.15 g of sodium persulfate in the form of a 35% aqueous solution are added and the mixture is heated to 75 °C with stirring, after which self-heating occurs. The reaction mixture is maintained at a temperature of 75-80 °C. After 1 hour, 0.41 g of sodium persulfate, based on the monomer mass, is added as a 35% aqueous solution. The reaction mixture is then maintained for another 1 hour at 75-80°C.

[0144] Next, neutralize to pH 5.0-5.5 with an aqueous solution of sodium hydroxide. In this way, 1160 g of a viscous liquid of straw color with an active substance content of 15.7 wt. % is obtained.

[0145] Example 9 (according to the invention): Synthesis of an acrylic acid homopolymer

[0146] The synthesis is carried out in a 2000 ml glass flask. 720 g of distilled water, 80 g of acrylic acid and 0.21 g of sodium persulfate in the form of a 35% aqueous solution are charged into it. The mixture is heated to 75 °C with stirring, after which self-heating occurs. The reaction mixture is maintained at a temperature of 75-80 °C and vigorously stirred. After 1 hour, 0.21 g of sodium persulfate in the form of a 35% aqueous solution are added. After this, the reaction mass is maintained for another hour at a temperature of 75-80 °C. Then it is neutralized to pH 7.5-8.0 with an aqueous solution of sodium hydroxide. After drying in a spray drier, 108 g of straw-colored powder with a residual water content of 2.9 wt. % are obtained.

[0147] The analytical data of the products obtained in the above examples are presented in Table 1. Table 1: Analytical data of the products obtained in examples 1-9

[0148] Sample Quantity Weight-average Degree Percentage comonomer molecular hydrolysis ratio mass % mass of high-molecular fraction to low-molecular fraction Example 1 0 610000 98.9 5.5 Example 2 0 532000 56.1 8.0 Example 3 0 560000 77.3 6.3 Example 4 0 600000 61.5 5.6 Example 5 0 615000 97.2 5.5 Example 6 30 640000 65.5 6.1 Example 7 30 664000 88.4 7.0 Example 8 30 650000 69.7 7.5

[0149]

[0150] Example 9 0 570000 90, 1 7, 3

[0151] Example 10: Application of the products obtained in Examples 1-9 in the drilling fluids segment

[0152] Determination of the filtration properties of drilling fluids The filtration properties of drilling fluids were determined in accordance with the above-described method. The results are presented in Table 2. SP-101 and GEOSPAN P were used as comparison samples. Table 2: Results of determining the filtration capacity

[0153] s

[0154] Sample Filtration, cm

[0155] Before thermostatting After thermostatting (T=110°C) Fresh NaCl solution Fresh NaCl solution solution

[0156] 7 , 5 30 7 , 5 30 7 , 5 30 7 , 5 30 min min min min min min min min Base 9 , 7 19 , 0 - - 9 , 0 18 , 3 - - solution

[0157] Example 1 3 , 3 7 , 4 14 , 0 22 , 0 3 , 2 7 , 6 33 , 0 43 , 5 Example 2 3 , 5 7 , 3 16 , 3 21 , 8 3 , 1 7 , 4 35 , 1 39 , 2 Example 3 3 , 8 8 , 0 17 , 9 31 , 8 3 , 4 7 , 6 38 , 8 41 , 9 Example 4 3 , 4 7 , 5 15 , 5 23 , 0 3 , 3 7 , 5 32 , 4 43 , 1 Example 5 3 , 5 7 , 4 13 , 9 22 , 7 3 , 2 7 , 1 31 , 0 42 , 7 Example 6 4 , 1 9 , 1 3 , 0 5 , 5 3 , 8 8 , 0 14 , 0 31 , 0 Example 7 3 , 4 7 , 5 3 , 5 4 , 8 3 , 3 7 , 8 14 , 9 25 , 8 Example 8 3 , 7 7 , 7 3 , 1 6 , 3 3, 1 7 , 6 18 , 0 36 , 0 Example 9 3 , 6 7 , 8 13 , 8 26, 1 3 , 5 7 , 9 35 , 6 48 , 7 SP- 101 4 , 0 8 , 1 7 , 5 15, 2 3 , 7 8 , 0 18 , 0 32 , 5

[0158]

[0159] GEOSPAN P 3, 9, 9, 8, 3, 8, 9, 6, 3, 6, 8, 3, 22, 6, 42, 8

[0160] From the data presented in Table 2 it follows that in fresh solutions the obtained samples reduce filtration into the formation at the level of the used reducers SP-101 and GEOSPAN P. The samples obtained in Examples 6 and 7 have greater salt resistance and heat resistance.

[0161] Example 11: Application of the products obtained in Examples 1-9 in the mining and processing segment

[0162] Flocculant tests of samples were performed on tailings pulps from flotation enrichment of ores at the Shanuch and Malomyr deposits. The concentration of the working solutions of the test samples was 0.5%. The density of all test pulps was 20%.

[0163] The pulp and reagent were poured into a graduated cylinder at a specified dose, thoroughly mixed, and placed on a horizontal surface. At specified intervals, the purity of the clarified liquid was assessed according to the categories "absolutely clear," "clean," "turbid," "dirty," and "very dirty."

[0164] On both pulps, the samples obtained in Examples 1-9 demonstrated flocculation properties.

[0165] A study of the tailings pulp from flotation enrichment of ore from both deposits revealed the following. Reagents from Examples 1-5 and 9 began to exhibit weak flocculation starting at a flow rate of 20 g / t, and a clean overflow was obtained at a flow rate of 50-60 g / t. Reagents from Examples 6-8, on the other hand, began to exhibit weak flocculation starting at a flow rate of 10 g / t, and a clean overflow was obtained at a flow rate of 40-50 g / t.

[0166] For comparison, the consumption of anionic high-molecular-weight flocculant for this type of ore is 30-40 g / t. However, it should be noted that the cost of such flocculant exceeds the cost of the tested product samples by 1.5-2.0 times.

Claims

CLAUSES OF THE INVENTION 1. (Co)polymer of acrylic acid with a degree of hydrolysis ranging from 50 to 100% and with a percentage ratio of high molecular weight fraction to low molecular weight fraction in the range of 5 to 9.

2. (Co)polymer according to claim 1, wherein the degree of hydrolysis is from 55 to 99%, more preferably from 60 to 95%.

3. (Co)polymer according to claim 1, in which the percentage ratio of high molecular weight fraction to low molecular weight fraction is in the range from 5.5 to 7.5, more preferably from 6 to 7.

4. (Co)polymer according to claim 1, which is a copolymer of acrylic acid with a monomer selected from the group of α,β-ethylenically unsaturated monomers suitable for radical polymerization.

5. (Co)polymer according to claim 1, which is a copolymer of acrylic acid with a monomer selected from the group of amides of α,β-ethylenically unsaturated monocarboxylic and dicarboxylic acids with amino alcohols with 2-30 carbon atoms having a primary or secondary amino group, primary amides of α,β-ethylenically unsaturated monocarboxylic acids and their N-alkyl and N,N-dialkyl derivatives, N-vinyl lactams, open-chain N-vinyl amide compounds, esters of allyl alcohol with monocarboxylic acids with 1-30 carbon atoms, esters of α,β-ethylenically unsaturated monocarboxylic and dicarboxylic acids with amino alcohols, amides of α,β-ethylenically unsaturated monocarboxylic and dicarboxylic acids with diamines having at least one primary or secondary amino group, N, N-diallylamines, N, N-diallyl-N-alkylamines, nitrogen heterocycles substituted with vinyl and allyl, vinyl ethers, monoolefins with 2-8 carbon atoms,non-aromatic hydrocarbons with at least two conjugated double bonds, polyether (meth) acrylates, monomers with urea groups and mixtures thereof., 6. The (co)polymer of claim 1, which is a copolymer of acrylic acid with a monomer selected from the group of primary amides of α,β-ethylenically unsaturated monocarboxylic acids and their N-alkyl and N,N-dialkyl derivatives, which are acrylic acid amide, methacrylic acid amide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N-(n-butyl) (meth) acrylamide, N-(tert-butyl) (meth) acrylamide, N-(n-octyl) (meth) acrylamide, N-(1,1,3,3-tetramethylbutyl) (meth) acrylamide, N-ethylhexyl (meth) acrylamide, N-(n-nonyl) (meth) acrylamide, N- (N-decyl) (meth) acrylamide, N- (n-undecyl) (meth) acrylamide, N-tridecyl- (meth) acrylamide, N-myristyl (meth) acrylamide, N-pentadecyl (meth) -acrylamide, N-palmityl (meth) acrylamide, N-heptadecyl (meth) acrylamide, N-nonadecyl (meth) acrylamide, N-arachininyl (meth) acrylamide, N-behenyl (meth) acrylamide, N-lignoceryl (meth) acrylamide, N-cerotinyl (meth) acrylamide, N-melissinyl (meth) acrylamide,N-palmitoleinyl (meth) acrylamide, N-oleyl (meth) acrylamide, N-linolyl (meth) acrylamide, N-linolenyl (meth) acrylamide, N-stearyl (meth) acrylamide, N-lauryl (meth) acrylamide, N,N-dimethyl (meth) acrylamide, N,N-diethyl (meth) acrylamide, morpholinyl (meth) acrylamide., 7. The (co)polymer of claim 1, which is a polymer of acrylic acid or a copolymer of acrylic acid with acrylamide.

8. The (co)polymer of claim 1, in which the comonomer content does not exceed 50 mass % based on the total monomer content.

9. (Co)polymer according to claim 1, wherein the comonomer content preferably does not exceed 30 mass % based on the total monomer content.

10. (Co)polymer according to claim 1, wherein the high molecular weight fraction is a fraction with a molecular weight of from 100,000 g / mol, preferably from 100,000 to 1,000,000 g / mol, more preferably from 100,000 to 900,000 g / mol.

11. (Co)polymer according to claim 1, wherein the low molecular weight fraction is a fraction with a molecular weight of up to 100,000 g / mol.

12. (Co) polymer according to claim 1 which has a weight average molecular weight in the range of from 100,000 to 900,000 g / mol, preferably from 400,000 to 800,000 g / mol, most preferably from 600,000 to 700,000 g / mol.

13. A method for producing a (co)polymer of acrylic acid according to any of paragraphs 1-12 in an aqueous medium, characterized in that it involves performing the following steps: I) loading water, acrylic acid, optionally one or two monomers and an initiator with stirring to obtain a reaction mass, II) optionally re-loading one or two monomers followed by loading of the initiator with stirring, III) optionally re-adding the initiator, IV) after completion of the reaction, adding the main compound to the aqueous solution; V) optionally drying the resulting solution.

14. The method according to claim 13, characterized in that the loading of water, acrylic acid, optionally one or two monomers and an initiator is carried out sequentially or simultaneously.

15. The method according to claim 13, characterized in that the acrylic acid is presented in an acidic, non-neutralized form.

16. The method according to claim 13, characterized in that inorganic or organic peroxide compounds are used as the initiator, preferably sodium persulfate, potassium persulfate, ammonium persulfate, hydrogen peroxide, di-tertiary butyl peroxide, cumene hydroperoxide, benzoyl peroxide, sodium thiosulfate, sodium hydrosulfite.

17. The method according to claim 13, characterized in that sodium, potassium or ammonium persulfates, preferably sodium persulfate, are used as the initiator.

18. The method according to paragraph 13, characterized in that the initiator is supplied in dry or solution form.

19. The method according to claim 13, characterized in that the initiator is fed into the reaction mass in two, optionally three stages in an amount of 0.7 to 1.0% of the total mass of the monomers, wherein at the initial moment of time the initiator is added in an amount of 0.25 to 0.5 mass % of the total mass of the monomers, and in the second and optionally third stages - the remaining amount, which makes it possible to obtain a (co)polymer having a reduced viscosity.

20. The method according to claim 13, which is carried out in a periodic or semi-periodic mode.

21. The method according to claim 13, characterized in that in stages I) and II) the reaction mass is heated to a temperature of 50-90°C, preferably 65-75°C, after which self-heating of the mass occurs.

22. The method according to paragraph 13, which is carried out at atmospheric pressure or at reduced or increased pressure.

23. The method according to claim 13, characterized in that in stages I) and II) the reaction mass is stirred for 1-10 hours, preferably 1-5 hours.

24. The method according to claim 13, characterized in that before carrying out stage II), the mixture is cooled to 25-30 °C.

25. The method according to claim 13, characterized in that, upon completion of the reaction, a basic compound is added to bring the pH value of the product to 3-9, preferably 5-7.

26. The method according to paragraph 13, characterized in that aqueous solutions with a concentration of 30-50 mass % are used as the main compound.

27. The method according to claim 13, characterized in that sodium or potassium hydroxides, ammonia or amines, preferably triethanolamine, are used as the main compound.

28. The method according to claim 13, characterized in that drying is possible using various methods, and preferably spray drying, roller drying, or drying in paddle dryers is carried out.

29. Use of a (co)polymer of acrylic acid according to any one of claims 1-12 in the drilling fluids segment as an additive for reducing fluid loss.

30. The use of a (co)polymer of acrylic acid according to any of paragraphs 1-12 in the mining and processing segment as a flocculant for thickening tailings from flotation enrichment.

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