Method for removing suspended matter and oil content in ammonia liquor, and polymer coagulant for ammonia liquor

Abstract

To provide a method for removing suspended matter and oil content in ammonia liquor containing coal-derived powder and tar, which enables the reduction of turbidity of the ammonia liquor and the formation and precipitation of agglomerates containing coal-derived powder and tar in the ammonia liquor.SOLUTION: A method for removing suspended matter and oil content in ammonia liquor comprises allowing a polymer coagulant to be present in ammonia liquor that contains suspended matter and oil content produced by washing and cooling coke oven gas with the ammonia liquor. The suspended matter contains coal-derived powder, and the oil content contains tar. The polymer coagulant has a cation colloid equivalent of 1.0 to 3.5 meq / g at pH 4.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for removing suspended solids and oil from ammonia water, and a polymer flocculant for ammonia water. [Background technology]

[0002] Iron is produced using iron ore, coal, and limestone as the main raw materials. Iron production at steelworks is generally carried out through a pig iron-making process in which sintered ore and coke are chemically reacted in a blast furnace to produce pig iron. Prior to this pig iron-making process, sintered ore is produced by baking iron ore and limestone. Coke is produced by carbonizing (steaming) coal in a coke oven.

[0003] The gas (coke oven gas, COG) generated during the carbonization of coal in a coke oven is first cooled to about 80°C in a piping system called a dry main by flashing, which involves spraying ammonia water (hereafter referred to as ammonia water) onto the coke oven gas.The gas is then separated into gas and liquid components, and after the gas components are cooled and hazardous substances that lead to air pollution are removed, they are used as energy in various processes within the steelworks, or by-products such as ammonium sulfate and diesel are refined from the gas and sold.

[0004] The liquid component contains coal tar (hereinafter simply referred to as "tar"), a by-product of coke production, condensed during the cooling of coke oven gas, along with ammonia water. The liquid component is sent to a tar decanter, where it is separated into an ammonia water layer and a tar layer by retention and sedimentation. The ammonia water in the upper layer of the tar decanter is circulated and reused for cooling (flushing) the coke oven gas. The tar deposited at the bottom of the tar decanter is removed, and after the solid sludge components are removed, it is shipped as a tar product or reused in the coal granulation process. For this reason, various studies have been conducted to date to efficiently separate the ammonia water and tar.

[0005] For example, Patent Document 1 discloses a method for removing slag from ammonia water in a coke oven, in which a lipophilic demulsifier is added to a tar decanter when tar generated from the coke oven is separated into tar and ammonia water in the tar decanter. Furthermore, Patent Document 2 discloses a demulsifier for coal tar-water separation, which contains a nonionic surfactant that is a polyether compound having an average molecular weight of 200 to 600,000, which is obtained by adding an alkylene oxide to a polyalkyleneimine having 7 to 200 nitrogen atoms. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-198986 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-230177 Summary of the Invention [Problem to be solved by the invention]

[0007] In the above-mentioned tar decanter, separation of the ammonia water and tar may become insufficient, resulting in the formation of a mixed layer (emulsion) of ammonia water and tar. When a mixed layer of ammonia water and tar is formed, the tar becomes mixed with the ammonia water circulated for flushing (circulating ammonia water), leading to contamination of the equipment, such as clogging of the flushing nozzle due to an increase in the oil and solid contents in the circulating ammonia water. Furthermore, insufficient separation of the ammonia water layer and the tar layer in the tar decanter leads to an increase in the water content of the tar layer. Therefore, there is a demand for a technology capable of breaking down emulsions containing ammonia water and tar or suppressing their formation, such as the technologies disclosed in Patent Documents 1 and 2.

[0008] Meanwhile, in recent years, there has been an increasing trend to use coal that has been dried in advance to reduce its moisture content before use in coke production, with the aim of making more effective use of coal resources, improving coke quality, coke productivity, energy conservation, and environmental friendliness. The moisture content of coal stored in a raw material yard is usually about 8 to 10 mass%, but one example is coal that has been dried in advance, separated into coarse coal and pulverized coal, and then agglomerated to reduce the moisture content to about 0 to 4 mass% (for example, DAPS coal and SCOPE coal, which will be described later).

[0009] When the moisture content of coal used in coke production is approximately 5% by mass or less, the pulverized coal adhering to the coal particle surface tends to generate dust, and even agglomeration treatment makes it difficult to completely prevent dust generation. Therefore, the presence of pulverized coal dust during the coke production process makes it easy for coal (pulverized coal) dust and / or coke dust to become mixed into the coke oven gas. As a result, the ammonia water generated by washing and cooling the coke oven gas with ammonia water contains coal powder and / or coke powder (hereinafter, these powders are collectively referred to as "coal-derived powder") and tar. In a tar decanter, the coal-derived powder is mixed into an emulsion containing ammonia water and tar. When an emulsion consisting of coal-derived powder, tar, and ammonia water is generated, even if an emulsifier such as that disclosed in Patent Documents 1 and 2 is added, the coal-derived powder remains dispersed in the ammonia water because it is mostly fine, causing the ammonia water to become cloudy, making it difficult to reduce the turbidity of the ammonia water.

[0010] Therefore, the present invention aims to provide a method for removing suspended solids and oils from ammonia water containing coal-derived powder and tar, which can reduce the turbidity of the ammonia water and form aggregates containing coal-derived powder and tar in the ammonia water, allowing them to settle. [Means for solving the problem]

[0011] That is, the present invention provides a method for removing suspended solids and oil from ammonia water, the method comprising adding a polymer flocculant to ammonia water containing suspended solids and oil, the suspended solids including coal-derived powder and the oil including tar, and the polymer flocculant having a cationic colloid equivalent value at pH 4 of 1.0 to 3.5 meq / g. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a method for removing suspended solids and oils from ammonia water that contains coal-derived powder and tar, which can reduce the turbidity of the ammonia water and form aggregates containing coal-derived powder and tar in the ammonia water and allow them to settle. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of a coke oven gas treatment process. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

[0015] A method for removing suspended solids and oils from ammonia water according to one embodiment of the present invention (hereinafter sometimes simply referred to as "the method") comprises adding a polymer flocculant to ammonia water containing suspended solids and oils, which is generated by washing and cooling coke oven gas with ammonia water. A polymer flocculant for ammonia water according to one embodiment of the present invention (hereinafter sometimes simply referred to as "polymer flocculant") is used in ammonia water containing suspended solids and oils, which is generated by washing and cooling coke oven gas with ammonia water. The suspended solids in the target ammonia water include coal-derived powder, and the oil in the ammonia water includes tar. The polymer flocculant added to the ammonia water has a cationic colloid equivalent value of 1.0 to 3.5 meq / g at pH 4.

[0016] This method treats ammonia water (ammonia water) containing at least coal-derived powder as suspended matter and tar as oil. Therefore, the "method for removing suspended matter and oil from ammonia water" in this disclosure means a method capable of removing at least coal-derived powder and tar from ammonia water.

[0017] In this method, by adding a polymer flocculant with a cationic colloid equivalent value of 1.0 to 3.5 meq / g at pH 4 to the ammonia water, aggregates containing suspended solids including coal-derived powder and oils including tar can be formed and precipitated in the ammonia water. This reduces the color and turbidity of the ammonia water. Furthermore, since the aggregates precipitated in the ammonia water can be easily removed, the coal-derived powder and tar can be removed from the ammonia water.

[0018] Therefore, when an emulsion containing coal-derived powder, tar, and ammonia water is generated in the ammonia water containing the polymer flocculant, the polymer flocculant can be used to break down (demulsify) the emulsion and separate the oil and water. It is also possible to suppress the generation of the emulsion in the ammonia water containing the polymer flocculant.

[0019] The ammonia water that is the subject of this method is ammonia water containing coal-derived powder and tar, which is generated by washing and cooling coke oven gas with ammonia water (hereinafter also referred to as "flushing"). Generally, ammonia water is circulated and used for flushing coke oven gas. In addition, ammonia water generally contains dissolved ammonia, ammonium salts, phenol, etc.

[0020] Tar in ammonia water is a by-product obtained by carbonizing coal in a coke oven when producing coke, and is condensed when the coke oven gas is cooled and contained in the ammonia water. An example of an oil component other than tar that may be contained in ammonia water generated by flashing coke oven gas is diesel oil, which is also produced as a by-product in the coal carbonization process.

[0021] As described above, the coal-derived powder in the ammonia solution is coal powder and / or coke powder, and is coal (pulverized coal) dust and / or coke dust that was contained in the coke oven gas. In recent years, there has been an increase in the use of pulverized coal, which has been dried in advance to reduce its moisture content, for use in coke production. As a result, pulverized coal adheres to the surface of coal particles, and the low moisture content of the pulverized coal makes it more likely to generate dust, which in turn makes it more likely for pulverized coal dust to become mixed into the coke oven gas. As a result, coal-derived powder is contained in the ammonia solution generated by flushing the coke oven gas.

[0022] Examples of pulverized coal that has been pre-dried to reduce its moisture content include controlled-moisture coal charging (CMC) technology and so-called DAPS coal and SCOPE coal. Controlled-moisture coal charging (CMC) technology involves controlling the moisture content of coal used in coke production to approximately 6% by mass using a controlled-moisture coal facility before charging it into a coke oven. Both DAPS and SCOPE coal are prepared by agglomerating the pulverized coal obtained after pre-drying and classifying the coal used in coke production, and adjusting the moisture content to approximately 4% by mass or less (0-4% by mass). DAPS and SCOPE coal were developed for the purposes of efficient use of coal resources, improving coke quality, coke productivity, energy conservation, and environmental friendliness, and their use has been increasing in recent years. Generally, caking coal, which has strong caking properties and is hard, is preferred as a raw material for coke. However, caking coal is difficult to obtain due to its limited production areas, low production volume, and low recoverable amount. For this reason, with regard to DAPS coal and SCOPE coal, the development of coal pre-treatment technologies has led to an increased use of non- or slightly caking coal (a general term for non-caking and slightly caking coals classified as low-rank coals), which are more readily available than caking coal and are often in powder form. The coal-derived powder in the ammonia solution preferably contains powder derived from at least one type of coal selected from the group consisting of DAPS coal and SCOPE coal. In coal moisture control (CMC) technology, coal with a moisture content of approximately 8 to 10% by mass stored in a raw material yard is adjusted to a moisture content of around 6% using a coal moisture control facility before being charged into a coke oven, thereby achieving a bulk density of approximately 680 to 700 kg / m when the coal moisture content is approximately 8 to 10% by mass. 3 to approximately 740-750 kg / m 3 It is possible to improve the bulk density to a level of 1000 kJ / m² and increase the proportion of non- or slightly caking coal used.

[0023] DAPS coal refers to coal produced by a DAPS (Dry-cleaned and Agglomerated Precompaction System) coal plant. In a DAPS (Dry-cleaned and Agglomerated Precompaction System) coal plant, raw coal is dried and classified into coarse coal and pulverized coal, and the pulverized coal is then formed into lumps to produce agglomerated coal. Finally, DAPS coal is produced as charging coal for charging into a coke oven, consisting of the coarse coal and the agglomerated coal. For example, a fluidized bed dryer / classifier is used for drying and classification. For forming into agglomerated coal, for example, a pressure-molding type agglomerator is used, and the coal is agglomerated at a temperature of about 60 to 200°C. Using a DAPS coal plant, raw coal with a moisture content of about 8 to 10% by mass can be used to produce charging coal with a moisture content of about 0 to 4% by mass, or even about 0 to 2% by mass, which is at a temperature of about 60 to 200°C when supplied to a coal charging car. In this disclosure, charging coal refers to coal as it is charged into a coke oven.

[0024] Additionally, SCOPE coal refers to coal produced by a SCOPE coal facility. SCOPE refers to SCOPE21 (Super Coke Oven for Productivity and Environmental enhancement toward the 21st century), a next-generation coke oven technology. In this disclosure, SCOPE coal facility refers to equipment that performs pre-treatment of coal to be charged into a coke oven, among the SCOPE technologies. In a SCOPE coal facility, after drying and classification of raw coal, similar to a DAPS coal facility, the coarse coal and pulverized coal are separately rapidly heated to approximately 330 to 380°C to improve caking properties. The pulverized coal is then hot-formed in a hot forming machine and mixed with the rapidly heated coarse coal to produce SCOPE coal as the charging coal for the coke oven. For example, a flash tower heater is used for the rapid heating treatment. The SCOPE coal facility can produce charging coal with a moisture content of approximately 0% by mass from raw coal with a moisture content of approximately 8 to 10% by mass, which has a temperature of approximately 180 to 200°C when supplied to the coal charging car.

[0025] The main suspended solids that make it difficult to reduce the turbidity of ammonia water are thought to be coal-derived particles with a number-based arithmetic mean diameter of 10 μm or less. Such fine coal-derived particles can be present, for example, in various facilities related to coke production in steelworks that handle the aforementioned DAPS or SCOPE coal. Specific examples of such facilities include a primary cooler 8, coke transport facilities such as a belt conveyor B for transporting coke, and a tar decanter 3, all of which are shown in Figure 1, which illustrates an example of a coke oven gas treatment process described below.

[0026] The primary cooler 8 is a facility used to cool the gas components of the coke oven gas generated from the coke oven 1. It is called a primary cooler because it is the first facility where the gas components are cooled. The gas components flow into the primary cooler 8, which has tubes through which seawater flows, and are cooled by the water in the tubes. Of the dust particles contained in the coke oven gas that has been flushed with ammonia water, some of the fine dust particles are sent to the primary cooler 8 along with the gas components.

[0027] Belt conveyor B is generally used as coke transport equipment. Coal steamed in coke oven 1 becomes coke, and after the coke leaves coke oven 1, it is transported to blast furnace 9 by belt conveyor B, which is also a coke transport equipment. The transport distance from coke oven 1 to blast furnace 9 can be as long as 1 km. Because coke has a low moisture content, dust can be generated during transport on belt conveyor B, and dust is particularly likely to be generated by the difference in height when changing belt conveyors B and the vibration of belt conveyor B itself.

[0028] As described above, the tar decanter 3 is a facility into which ammonia water (a liquid component containing suspended solids, oil, and ammonia water) generated by the flushing of coke oven gas flows and separates the ammonia water into ammonia water layer L1 and a tar layer L2. In the tar decanter 3, a turbid layer in which the ammonia water and the tar are not sufficiently separated, i.e., an emulsion L3 of ammonia water and tar, may form between the ammonia water layer L1 and the tar layer L2. As described in the examples below, when a simulated ammonia water sample mixed with coal fines adjusted to an arithmetic mean diameter on a number basis of 10 μm or less was mixed with tar, an emulsion layer was formed and turbidity was confirmed.

[0029] Therefore, from the viewpoint of easily realizing its technical significance, this method is more suitable for ammonia water containing coal-derived powder having a number-based arithmetic mean diameter of 10 μm or less as suspended matter. Furthermore, this method is even more suitable when the coal-derived powder includes powder derived from coal that has been dried to reduce its moisture content before being used to produce coke. Therefore, the coke oven gas is preferably a gas generated when charged coal containing coal that has been dried to reduce its moisture content before being used to produce coke is carbonized in a coke oven. The moisture content of coal that has been dried to reduce its moisture content before being used to produce coke (humidity-controlled coal) is preferably 0 to 8% by mass, more preferably 6% by mass or less, and even more preferably 4% by mass or less.

[0030] In the present disclosure, the number-based arithmetic mean diameter of coal-derived powder can be a value measured by the following particle size distribution measurement method. As a pretreatment for particle size distribution measurement, coal-derived powder is collected with water, the liquid is filtered through a polycarbonate membrane filter with a pore size of 0.2 μm, and the filter paper is dried under reduced pressure at room temperature. A light transmission image of the vacuum-dried filter paper is observed using a digital microscope (product name "VHX-6000", manufactured by Keyence Corporation). The image is binarized using software installed on the digital microscope to measure the equivalent circle diameter. Note that the image binarization process involves converting the brightness of each pixel in the image observed by the digital microscope into a relative value, setting an arbitrary threshold (e.g., around 223), and comparing the values ​​of each pixel. If the pixel value is greater than the threshold, it is converted to white, and if it is less than the threshold, it is converted to black. The equivalent circle diameter is the diameter of a circle having an area equal to the particle area. The circle-equivalent particle diameters Dp of at least 2,000 coal-derived powder particles are determined, and the number-based average diameter Da is calculated using the number of evaluated particles n and the following formula (1). The coal powder used in the examples described below was confirmed by sieving commercially available coal fine powder and then measuring the number-based arithmetic mean diameter using the above measurement method. Da=ΣnDp / Σn (1)

[0031] This method involves adding a polymer flocculant having a cationic colloid equivalent value of 1.0 to 3.5 meq / g at pH 4 to the above-mentioned ammonia water. The cationic colloid equivalent value of the polymer flocculant at pH 4 of 1.0 to 3.5 meq / g allows aggregates containing suspended solids including coal-derived powder and oils including tar to form and settle in the ammonia water. This reduces the turbidity of the ammonia water. The cationic colloid equivalent value of the polymer flocculant at pH 4 is preferably 1.1 to 3.4 meq / g, more preferably 1.2 to 3.3 meq / g, and even more preferably 2.1 to 3.1 meq / g.

[0032] Ammonia water contains ammonium (NH4 +) is present, and phenoxide ions are thought to be present in the tar. When an emulsion containing tar and ammonia water is generated, the phenoxide ions in the tar and the ammonium in the ammonia water electrostatically bond, and suspended solids including coal-derived powder are thought to be trapped in this emulsion. The presence of a polymer flocculant with a weak to medium charge and a cationic colloid equivalent value of 1.0 to 3.5 meq / g at pH 4 is thought to disrupt the emulsion. Then, aggregates containing suspended solids including coal-derived powder and oils including tar are formed and settle, which is thought to reduce the color and turbidity of the ammonia water layer.

[0033] The cationic colloid equivalent value (meq / g) of a polymer flocculant at pH 4 indicates the degree of cationicity of the polymer flocculant, with a higher value indicating stronger cationicity. In this disclosure, the cationic colloid equivalent value (meq / g) per 1 g of polymer flocculant is measured and calculated by colloid titration using a polymer flocculant aqueous solution adjusted to pH 4 as the test solution and a polyvinyl potassium sulfate solution as the standard polyanion as the titrant. Examples of indicators that can be used include toluidine blue. More specifically, values ​​can be measured and calculated by the colloid titration method described in the examples below. The colloid titration method described in the examples below is a test method based on the test method described in "Sewage Testing Methods, Vol. 1, 2012 Edition," pp. 737-739, published by the Japan Sewage Works Association.

[0034] The weight-average molecular weight of the polymer flocculant is preferably 4 million to 10 million, more preferably 4.5 million to 9 million, and even more preferably 5 million to 8 million. The weight-average molecular weight of the polymer flocculant is a value measured by GPC (gel permeation chromatography) using polystyrene standards.

[0035] The form of the polymer flocculant used in this method is not particularly limited and may be in liquid form, such as an aqueous solution, a water-in-oil (W / O) emulsion, a water-in-oil dispersion (W / O dispersion), or a dispersion in saltwater (O / W dispersion), or in powder form. From the perspective of ease of use and handling in ammonia water, it is preferable to use the polymer flocculant in liquid form. In this case, a liquid polymer flocculant product containing a liquid medium such as water and a polymer flocculant as an active ingredient can be used. The content of the polymer flocculant in the liquid polymer flocculant product is preferably 1 to 50 mass%, more preferably 5 to 45 mass%, and even more preferably 10 to 40 mass%, based on the total mass of the liquid polymer flocculant product. The content of the liquid medium such as water in the liquid polymer flocculant product is preferably 50 to 99 mass%, more preferably 55 to 95 mass%, and even more preferably 60 to 90 mass%, based on the total mass of the liquid polymer flocculant product.

[0036] Alternatively, a polymer flocculant solution containing a liquid medium such as water and a polymer flocculant as an active ingredient can be prepared by diluting the liquid polymer flocculant product (e.g., a commercially available product) with water. When using a W / O emulsion liquid polymer flocculant product, the content of the polymer flocculant in the polymer flocculant solution is preferably 0.01 to 0.5 mass%, more preferably 0.03 to 0.4 mass%, based on the total mass of the polymer flocculant solution. When using an O / W dispersion liquid polymer flocculant product, the content of the polymer flocculant in the polymer flocculant solution is preferably 0.005 to 1.0 mass%, more preferably 0.01 to 0.6 mass%, based on the total mass of the polymer flocculant solution. The liquid polymer flocculant product or polymer flocculant solution may contain one or more other components. Examples of other components include surfactants, preservatives, antioxidants, colorants, and antifoaming agents.

[0037] As the polymer flocculant, a polymer flocculant having a cationic group can be used. As the polymer flocculant having a cationic group, a cationic polymer flocculant and an amphoteric polymer flocculant can be mentioned. Among these, one polymer flocculant having the above-mentioned specific cationic colloid equivalent value can be used alone or in combination of two or more.

[0038] Suitable cationic polymer flocculants include homopolymers of cationic monomers, copolymers of two or more cationic monomers, and copolymers of cationic monomers and nonionic monomers copolymerizable with the cationic monomers. Preferred cationic monomers include, for example, dialkylaminoalkyl(meth)acrylates, dialkylaminoalkyl(meth)acrylamides, and their neutralized salts (neutralized salts with acids such as hydrochloric acid or sulfuric acid) and quaternary ammonium salts (quaternized compounds). The cationic polymer flocculant can contain one or more cationic monomers.

[0039] Examples of dialkylaminoalkyl (meth)acrylates include 2-(dimethylamino)ethyl (meth)acrylate and diethylaminoethyl (meth)acrylate. Examples of dialkylaminoalkyl (meth)acrylamides include N-[2-(dimethylamino)ethyl] (meth)acrylamide, N-[3-(dimethylamino)propyl] (meth)acrylamide, and N-[2-(diethylamino)ethyl] (meth)acrylamide. Examples of dialkylaminoalkyl (meth)acrylate quaternary ammonium salts include reaction products of dialkylaminoalkyl (meth)acrylates with quaternizing agents. Examples of dialkylaminoalkyl (meth)acrylamide quaternary ammonium salts include reaction products of dialkylaminoalkyl (meth)acrylamides with quaternizing agents. Examples of quaternizing agents include methyl chloride, ethyl chloride, benzyl chloride, methyl bromide, ethyl bromide, benzyl bromide, methyl iodide, and ethyl iodide.

[0040] In addition, examples of nonionic monomers copolymerizable with cationic monomers include (meth)acrylamide, N-methyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, acrylonitrile, styrene, vinyl acetate, alkyl (meth)acrylate, and hydroxyalkyl (meth)acrylate. One or more nonionic monomers can be used in the cationic polymer flocculant.

[0041] Suitable amphoteric polymer flocculants include copolymers of cationic monomers and anionic monomers, and copolymers of cationic monomers, anionic monomers, and nonionic monomers. Examples of cationic monomers and nonionic monomers include the cationic monomers and nonionic monomers listed above, respectively, and one or more of each can be used. Examples of anionic monomers include (meth)acrylic acid, itaconic acid, maleic acid, vinyl sulfonic acid, allyl sulfonic acid, styrene sulfonic acid, and alkali metal salts, alkaline earth metal salts, and ammonium salts thereof. Among these, (meth)acrylic acid and its alkali metal salts and ammonium salts are preferred. One or more anionic monomers can be used in the amphoteric polymer flocculant.

[0042] In the present disclosure, the term "(meth)acrylate" includes both "acrylate" and "methacrylate," the term "(meth)acrylamide" includes both "acrylamide" and "methacrylamide," the term "(meth)acrylic acid" includes both "acrylic acid" and "methacrylic acid," and the term "(meth)acryloyl" includes both "acryloyl" and "methacryloyl."

[0043] As the polymer flocculant, a cationic polymer flocculant that is a copolymer of the above-mentioned cationic monomer and nonionic monomer is preferred. Among these, a cationic polymer flocculant containing a structural unit derived from acrylamide and a structural unit derived from a monomer represented by the following general formula (1) is more preferred. Hereinafter, this cationic polymer flocculant may be referred to as a polyacrylamide-based cationic polymer flocculant. In this method, one or more of these polyacrylamide-based cationic polymer flocculants can be used as the polymer flocculant. Furthermore, the polyacrylamide-based cationic polymer flocculant can contain a structural unit derived from one or more of the monomers represented by general formula (1).

[0044] TIFF2025162269000001.tif53170 (R in general formula (1) 1 represents a hydrogen atom or a methyl group, and R 2 and R 3 each independently represents a methyl group or an ethyl group, R 4 represents a hydrogen atom, or a methyl group or an ethyl group which may be substituted with an aromatic group, and X represents a counter anion with the ammonium cation in general formula (1).

[0045] The monomer represented by general formula (1) is an aminoethyl (meth)acrylate-based monomer, which is one of the cationic monomers described above. 4 Examples of the aromatic group that may be substituted with an aromatic group in the methyl or ethyl group include a phenyl group, a tolyl group, a xylyl group, and a naphthyl group, and among these, a phenyl group is preferred. 4 Preferably, R represents a hydrogen atom, a methyl group, an ethyl group, or a benzyl group. 2 and R 3 represents a methyl group, and R 4represents a methyl group or a benzyl group. Examples of counter anions that can be taken by X in general formula (1) include chloride ion, bromide ion, carbonate ion, hydrogen carbonate ion, propionate ion, sulfate ion, hydrogen sulfate ion, and methyl sulfate ion. Among these, chloride ion or bromide ion is preferred, and chloride ion is more preferred.

[0046] Examples of the monomer represented by general formula (1) include dimethylaminoethyl (meth)acrylate methyl chloride quaternary salt, dimethylaminoethyl (meth)acrylate benzyl chloride quaternary salt, dimethylaminoethyl (meth)acrylate methyl sulfate quaternary salt, dimethylaminoethyl (meth)acrylate hydrochloride, and dimethylaminoethyl (meth)acrylate sulfate. Among these, at least one selected from the group consisting of dimethylaminoethyl acrylate methyl chloride quaternary salt (also known as [2-(acryloyloxy)ethyl]trimethylammonium chloride), dimethylaminoethyl methacrylate methyl chloride quaternary salt (also known as [2-(methacryloyloxy)ethyl]trimethylammonium chloride), and dimethylaminoethyl acrylate benzyl chloride quaternary salt (also known as [2-(acryloyloxy)ethyl]benzyldimethylammonium chloride) is more preferred.

[0047] In the polyacrylamide-based cationic polymer flocculant, the proportion of structural units derived from acrylamide is preferably higher than the proportion of structural units derived from the monomer represented by general formula (1). The proportion of structural units derived from acrylamide in the polyacrylamide-based cationic polymer flocculant to structural units derived from the monomer represented by general formula (1) is preferably the following molar ratio. That is, the molar ratio of structural units derived from acrylamide to structural units derived from the monomer represented by general formula (1) is preferably 95:5 to 65:35, more preferably 90:10 to 67:33, and even more preferably 85:15 to 70:30. When the polyacrylamide-based cationic polymer flocculant contains two or more structural units derived from the monomer represented by general formula (1), the molar ratio of structural units derived from the monomer represented by general formula (1) is the sum of the two or more structural units.

[0048] In this disclosure, the molar ratio can be calculated (approximately estimated) based on the cationic colloid equivalent value, weight-average molecular weight, and chemical structural formula of each structural unit (monomer) of the polyacrylamide-based cationic polymer flocculant. The following describes the polyacrylamide-based cationic polymer flocculant C6 (a copolymer of acrylamide and [2-(acryloyloxy)ethyl]trimethylammonium chloride; cationic colloid equivalent value 2.2 meq / g, weight-average molecular weight 10 million) used in the examples described below.

[0049] First, let X be the repeating unit of the structural unit derived from acrylamide, and Y be the repeating unit of [2-(acryloyloxy)ethyl]trimethylammonium. The charge indicated by the cationic colloid equivalent value is the N of the repeating unit Y. + Since this is the part, + The number of moles of repeating units Y (referred to as y) is present in the molecular weight, and from the measured value of the cationic colloid equivalent, y / 10 million = 2.2 × 10 -3From this, y = 22,000 can be calculated. Next, the atomic weights of H, C, N, and O are set to 1, 12, 14, and 16, respectively, and the molecular weights of acrylamide and [2-(acryloyloxy)ethyl]trimethylammonium are set to 71 and 158, respectively. Furthermore, if the number of repeating units X is set to x, then the weight-average molecular weight of polyacrylamide-based cationic polymer flocculant C6 is 10 million, so 71x + 158y = 10 million. Substituting the above y = 22,000 here, x becomes 91,887, and x:y = 81:19 is obtained. The ratio calculated in this way can be used as the molar ratio of structural units derived from acrylamide to structural units derived from the monomer represented by general formula (1) (in this example, [2-(acryloyloxy)ethyl]trimethylammonium). In addition, when the monomer represented by general formula (1) contains structural units derived from two or more monomers, such as the polyacrylamide-based cationic polymer flocculants C3, C5, C8, and C9 used in the examples described below, the above molar ratio is estimated using the arithmetic average value of the molecular weights of the structural units derived from the two or more monomers.

[0050] The molar ratio of structural units derived from acrylamide to structural units derived from the monomer represented by general formula (1) in each polyacrylamide-based cationic polymer flocculant used in the examples described below was determined as described above.

[0051] The above-mentioned polymer flocculant can be produced by a known method. For example, the above-mentioned monomer components and known polymerization initiators (e.g., azo-based initiators, peroxide-based initiators, etc.) are used to polymerize or copolymerize the monomer components by aqueous solution polymerization, water-in-oil emulsion polymerization, water-in-oil dispersion polymerization, dispersion polymerization in saltwater, etc. Then, the resulting mixture can be prepared in the form of an aqueous solution, water-in-oil emulsion, dispersion in saltwater, powder, etc., to produce a polymer flocculant product.

[0052] In this method, one method for adding the polymer flocculant to the ammonia water can be to add the polymer flocculant to the ammonia water containing suspended solids and oils generated by washing and cooling coke oven gas with the ammonia water. In this case, the polymer flocculant can be added to the ammonia water (ammonia water immediately before flowing into) that flows into a tar decanter or other equipment for separating the ammonia water layer from the tar layer, or to the ammonia water in the equipment that has flowed into the equipment. Another method for adding the polymer flocculant to the ammonia water can be to add the polymer flocculant to the ammonia water (circulating ammonia water) that has been separated from the tar in a tar decanter or other equipment and is flowing out of the equipment and heading to the flushing facility.

[0053] As described above, the aforementioned polymer flocculant can be added to the ammonia water before it flows into equipment such as a tar decanter, the ammonia water inside the equipment, or the ammonia water used for flushing (these are referred to as the target liquid). The polymer flocculant can also be added to multiple locations. By adding the polymer flocculant to the target liquid, aggregates containing suspended matter including coal-derived powder and oil containing tar can be formed and precipitated in the ammonia water containing suspended matter and oil generated by the flushing of coke oven gas. This reduces the color and turbidity of the ammonia water.

[0054] The amount of polymer flocculant added to the target liquid is preferably 0.1 to 1000 mg / L, more preferably 0.5 to 500 mg / L, and even more preferably 1 to 300 mg / L, from the viewpoint of turbidity reduction and flocculation ability by the polymer flocculant. When the above-mentioned liquid polymer flocculant product is used as the polymer flocculant, the amount added refers to the amount added in terms of the active ingredient (polymer flocculant).

[0055] Next, a specific embodiment of the present method will be described with reference to Fig. 1. Fig. 1 is a schematic flow diagram showing an example of a coke oven gas treatment process. The solid arrows in Fig. 1 mainly represent the flow of ammonia water circulated for flushing the coke oven gas. The dashed arrows in Fig. 1 mainly represent the flow of tar separated from the ammonia water, and the dashed-dotted arrows mainly represent the flow of ammonia water (excess ammonia water) separated from the tar.

[0056] High-temperature gas (coke oven gas) generated in a coke oven 1 (e.g., approximately 500–600°C) is cooled to approximately 80–85°C by spraying ammonia water onto the coke oven gas in a dry main 2, a type of piping system. This is called flushing with ammonia water. If the coke oven gas contains chlorine or hydrogen sulfide, the chlorine is collected as ammonium chloride and the hydrogen sulfide is collected as ammonium sulfide, and the coke oven gas is purified. During cooling, the tar in the coke oven gas is condensed, and the condensate and ammonia water are sent to a tar decanter 3. Meanwhile, the gas components in the coke oven gas are cooled to approximately 30–35°C in a primary cooler 8. The gas then passes through a desulfurization unit, an ammonia removal unit, and a diesel recovery unit, where hydrogen sulfide, hydrogen cyanide, ammonia, diesel, and other components are sequentially removed. The resulting refined coke oven gas can be used as fuel in the steelmaking process.

[0057] The ammonia water sent to the tar decanter 3, which contains suspended solids including coal-derived powder and oils including tar, is left to stand, and the tar settles and separates in the ammonia water in the tar decanter 3 while standing, separating into a supernatant ammonia water layer L1 and a tar layer L2 at the bottom. From the ammonia water layer L1 in the tar decanter 3, a portion of the ammonia water is circulated and sent for flushing, and a portion is sent to the ammonia water tank 4 as excess ammonia water. Furthermore, from the tar layer L2 in the tar decanter 3, tar deposited at the bottom is extracted and sent to the next process. In the next process, the water and sludge in the tar are removed in a sludge settling tank 5 and a super decanter (centrifuge) 6, and the resulting tar is sent to a tar tank 7 as product tar.

[0058] In this method, the aforementioned polymer flocculant can be added to the liquid W1 flowing into the tar decanter 3, the liquid in the tar decanter 3 that has flowed into the tar decanter 3, and the ammonia water (circulated ammonia water) W2 that has flowed out of the tar decanter 3 and is on its way to being flushed. This allows the aforementioned polymer flocculant to be present in the ammonia water containing suspended solids including coal-derived powder and oils including tar in the tar decanter 3, making it possible to form and settle aggregates containing coal-derived powder and tar in the ammonia water. As a result, the color and turbidity of the ammonia water can be reduced, and the aggregates that have settled in the ammonia water can be easily removed, thereby removing the coal-derived powder and tar from the ammonia water.

[0059] As a result of the above-described effects, if an emulsion L3 containing coal-derived powder, tar, and ammonia water is formed in the tar decanter 3 due to insufficient separation of the ammonia water layer L1 and the tar layer L2, the emulsion L3 can be broken down (demulsified) to separate the oil and water. The formation of the emulsion L3 can also be suppressed. Since the separation of the ammonia water layer L1 and the tar layer L2 can be promoted in the tar decanter 3, the moisture content of the tar layer L2 in the tar decanter 3 may also be reduced. Therefore, the tar with reduced moisture content in the tar decanter 3 can be sent to the subsequent process (sludge settling tank 5 or super decanter 6), allowing for more effective removal of moisture from the tar in the subsequent process. This also reduces the tar content in the ammonia water (circulated ammonia water) W2 flowing out of the tar decanter 3 and heading for flushing, potentially suppressing tar adhesion to equipment such as the flushing nozzle.

[0060] When the aforementioned polymer coagulant is added to the liquid W1 flowing into the tar decanter 3, a device, a mechanism, etc. for adding the polymer coagulant can be provided in the inlet pipe P1 to the tar decanter 3. Furthermore, when the aforementioned polymer coagulant is added to the ammonia water (circulating ammonia water) W2 flowing out of the tar decanter 3 and heading for flushing, a device, a mechanism, etc. for adding the polymer coagulant can be provided in the outlet pipe P2 from the tar decanter 3. Furthermore, when the aforementioned polymer coagulant is added to the liquid containing ammonia water and tar in the tar decanter 3, a device, a mechanism, etc. for adding the polymer coagulant can be provided in the tar decanter 3.

[0061] As described above in detail, one embodiment of the present invention can have the following configuration. [1] The process involves adding a polymer flocculant to ammonia water containing suspended solids and oil, which is generated by washing and cooling coke oven gas with ammonia water. the suspended matter comprises coal-derived powder; The oil contains tar, The method for removing suspended solids and oil from ammonia water, wherein the polymer flocculant has a cationic colloid equivalent value at pH 4 of 1.0 to 3.5 meq / g. [2] The method for removing suspended solids and oil from ammonia water according to [1] above, wherein the coal-derived powder has an arithmetic mean particle size based on the number of particles of 10 μm or less. [3] The method for removing suspended solids and oil from ammonia water according to [1] or [2] above, wherein the coal-derived powder comprises powder derived from coal that has been dried to reduce its moisture content before being used to manufacture coke. [4] A method for removing suspended solids and oil from ammonia water according to any one of [1] to [3] above, wherein the polymer flocculant contains a structural unit derived from acrylamide and a structural unit derived from the monomer represented by the general formula (1) above. [5] The method for removing suspended solids and oil in ammonia water according to any one of [1] to [4] above, wherein the polymer flocculant has a weight-average molecular weight of 4,000,000 to 10,000,000. [6] A method for removing suspended solids and oil from ammonia water according to any one of [1] to [5] above, wherein the coke oven gas is a gas generated when charged coal containing coal that has been dried to reduce its moisture content before being used to manufacture coke is carbonized in a coke oven. [7] A polymer flocculant used in ammonia water containing suspended solids and oils generated by washing and cooling coke oven gas with ammonia water, the suspended matter comprises coal-derived powder; The oil contains tar, The polymer flocculant for use in ammonia water has a cationic colloid equivalent value at pH 4 of 1.0 to 3.5 meq / g. [Example]

[0062] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

[0063] <Preparation of polymer flocculant> Anionic polymer flocculants A1 to A4 and cationic polymer flocculants C1 to C15 shown in Table 1 were used. Each polymer flocculant was a liquid polymer flocculant product with the form and active ingredient (polymer) concentration shown in Table 1. Each polymer flocculant is a copolymer containing structural units derived from the monomers indicated with a "○" in the abbreviation column (AAm, ABD, ATM, MTM, and AAc) under "Monomer Composition" in Table 1. Cationic polymer flocculants C1 to C15 are copolymers containing a structural unit (X) derived from acrylamide and a structural unit (Y) derived from a monomer represented by general formula (1). The molar ratio (X:Y) of these structural units is shown based on the approximate estimated value described above. The weight-average molecular weight (Mw) of each polymer flocculant was measured by GPC using polystyrene equivalents. The meanings of the monomer abbreviations are as follows:

[0064] AAm: acrylamide ABD: [2-(acryloyloxy)ethyl]benzyldimethylammonium chloride (in general formula (1), R 1 H, R 2 and R3 is CH3, R 4 is a benzyl group, X - Cl - (a compound in which ATM: [2-(acryloyloxy)ethyl]trimethylammonium chloride (in general formula (1), R 1 H, R 2 ~R 4 is CH3, X - Cl - (a compound in which MTM: [2-(methacryloyloxy)ethyl]trimethylammonium chloride (in general formula (1), R 1 ~R 4 is CH3, X - Cl - (a compound in which AAc: sodium acrylate

[0065] TIFF2025162269000002.tif134170

[0066] <Measurement of colloid equivalent value> The colloidal equivalent (meq / g) of each polymer flocculant was measured by the following procedure.

[0067] (Preparation of polymer flocculant solution / both cationic and anionic) For each polymer flocculant, the liquid polymer flocculant product was added to 200 mL of pure water and stirred for 30 minutes with a magnetic stirrer to prepare a polymer flocculant solution. The mass of the liquid polymer flocculant product used at this time was defined as s (g; approximate value: 0.1 g).

[0068] (Confirmation of the amount of active ingredient in polymer flocculants / for both cationic and anionic flocculants) Approximately 1.0 g of each liquid polymer flocculant product sample was weighed onto an aluminum dish and dried in a dryer at 105±5°C for 24 hours, after which the mass was measured. The mass before drying was designated M1, and the mass after drying was designated M2. The active ingredient (polymer flocculant) concentration c of each liquid polymer flocculant product was calculated using the following formula (2): Active ingredient concentration c (mass%) = M2 / M1×100 (2)

[0069] (Measurement of colloidal equivalent value of cationic polymer flocculant) For cationic polymer flocculants C1 to C15, the colloid (cationic colloid) equivalent value per 1 g of cationic polymer flocculant was measured as follows. 90 mL of pure water and 10 mL of polymer flocculant solution were placed in a 300 mL Erlenmeyer flask, stirred, and then 0.1 mol / L hydrochloric acid was added to adjust the pH to 4.0. This polymer flocculant aqueous solution was used as the test solution. A few drops of toluidine blue indicator solution were added to the test solution to turn it blue, and 2.5 mmol / L polyvinyl potassium sulfate solution (Fujifilm Wako Pure Chemical Industries, Ltd., "N / 400 PVSK solution" (for colloid titration), factor F = 1.00) was added dropwise. The endpoint was the point at which the test solution changed from blue to reddish purple and the reddish purple color persisted for approximately 10 seconds or more. The titer (a) of 2.5 mmol / L polyvinyl potassium sulfate solution required for this was determined. Separately, a similar procedure (blank test) was performed using 100 mL of pure water instead of the test solution, and the titer b (mL) of 2.5 mmol / L potassium polyvinyl sulfate solution required to reach the same end point was determined. The colloid equivalent (meq / g) per 1 g of cationic polymer flocculant (active ingredient) was calculated using the following formula (3). Colloid equivalent value (meq / g) ={(ab) / 2}×{10 / (s×c)}×F ···(3)

[0070] (Measurement of colloidal equivalent value of anionic polymer flocculants) For anionic polymer flocculants A1 to A4, the colloid (anionic colloid) equivalent value per gram of anionic polymer flocculant was measured as follows. 90 mL of pure water, 0.5 mL of 0.1 mol / L sodium hydroxide solution, and 5 mL of 5 mmol / L methyl glycol chitosan solution (Fujifilm Wako Pure Chemical Industries, Ltd.'s "N / 200 MeGch solution" for colloid titration, factor F = 1.00) were added to a 300 mL Erlenmeyer flask and stirred for at least 1 minute. Then, 10 mL of polymer flocculant solution was gradually added and stirred for at least 5 minutes. This was used as the test solution. A few drops of toluidine blue indicator were added to the test solution to turn it blue, and then 2.5 mmol / L polyvinyl potassium sulfate solution (Fujifilm Wako Pure Chemical Industries, Ltd.'s "N / 400 PVSK solution" for colloid titration, factor F = 1.00) was added dropwise. The endpoint was the point at which the test solution changed from blue to reddish purple and the reddish purple color remained for at least 10 seconds. The titer a (mL) of 2.5 mmol / L polyvinyl potassium sulfate solution required to achieve this was determined. Separately, a blank test was performed using 100 mL of pure water instead of the test solution, and the titer b (mL) of 2.5 mmol / L polyvinyl potassium sulfate solution required to reach the same endpoint was determined. The colloid equivalent (meq / g) per 1 g of anionic polymer flocculant (active ingredient) was calculated using the above formula (3).

[0071] For each polymer flocculant, the measured colloid equivalent value per 1 g of polymer flocculant (meq / g) is shown in Table 2. In the evaluations described below, for each polymer flocculant, a diluted solution was used in which the corresponding liquid polymer flocculant product was dissolved in pure water, and the content of the liquid polymer flocculant product was adjusted to 0.1 mass % (the content of the polymer flocculant in the polymer flocculant solution was 0.014 to 0.04 mass %).

[0072] <Examples and Comparative Examples> Considering the tar and ammonia generated in actual facilities that treat coke oven gas, a simulated tar sample (moisture content 15% by mass, coal tar 85% by mass) prepared by adjusting the moisture content of commercially available coal tar (manufactured by Alfa Aeser) to 15% by mass with pure water was used as the tar. Furthermore, commercially available coal (manufactured by Sanyo Kosho Co., Ltd.) was used as coal powder by adjusting its arithmetic mean particle size (number basis) to 10 μm or less using a sieving method. The pH at 25°C was adjusted to 9.5, and the ammonium (NH4 + ) concentration of 2200 mg / L, phenol concentration of 1600 mg / L, chloride ion (Cl - ) concentration of 1900 mg / L, sulfate ions (SO4 2- A simulated ammonia water sample prepared with a ammonium nitrate concentration of 370 mg / L and a coal fines concentration of 1000 mg / L was used as the ammonia water.

[0073] After the ammonia water and tar were kept at 70°C, 40 mL of ammonia water and 0.5 mL of tar were mixed in a 50 mL vial to form an emulsion layer. A polymer flocculant solution was added to the vial containing the emulsion layer, so that the polymer flocculant (active ingredient) shown in Table 2 was added in the amount shown in Table 2 (4.0 mg / L, 0.4 mg / L, or 40.0 mg / L) relative to the target solution containing ammonia water and tar. In Comparative Example 1, a test was conducted without adding a polymer flocculant to the vial containing the emulsion layer. The vial was then agitated by inverting it 30 times over a period of approximately 30 seconds, and then placed in a 70°C water bath for 30 minutes. The turbidity of the ammonia water in the vial was then measured at a wavelength of 610 nm using an absorption spectrophotometer (product name "DR900" manufactured by HACH).

[0074] (Turbidity of Ansu water) Using the measured values ​​of the turbidity of the ammonium hydroxide solution, the reduction rate (%) of the turbidity of the ammonium hydroxide solution was calculated using the following formula (4), with Comparative Example 1, which was a chemical-free condition, as the reference. Examples in which the reduction rate of the turbidity of the ammonium hydroxide solution was 50% or more were judged to have the effect of reducing the turbidity of the ammonium hydroxide solution, and are indicated by "○" in the evaluation column for "Turbidity of ammonium hydroxide solution" in Table 2. On the other hand, examples in which the reduction rate of the turbidity of the ammonium hydroxide solution was less than 50% were judged to have the effect of reducing the turbidity of the ammonium hydroxide solution, and are indicated by "×" in the evaluation column for "Turbidity of ammonium hydroxide solution" in Table 2. Turbidity reduction rate (%)=(Turbidity of Comparative Example 1−Turbidity) / Turbidity of Comparative Example 1 (4)

[0075] (presence or absence of aggregates) The state of the liquid in the vial was visually observed to check for the presence or absence of aggregates. The results are shown in Table 2. In the cases where aggregates were present, it was confirmed that aggregates had precipitated at the bottom of the vial. On the other hand, in the cases where aggregates were not present, no aggregates were confirmed to have precipitated at the bottom of the vial.

[0076] TIFF2025162269000003.tif201170

[0077] As shown in Table 2, in each example, the turbidity of the ammonia water containing coal fines and tar was reduced by adding a polymer flocculant with a cationic colloid equivalent value at pH 4 in the range of 1.0 to 3.5 meq / g, and aggregates were formed in the ammonia water and allowed to settle. In each example, the turbidity of the ammonia water was also sufficiently reduced, so it can be said that aggregates containing coal fines and tar were formed, and it was confirmed that the coal fines and tar could be easily removed from the ammonia water by removing the settled aggregates. [Explanation of symbols]

[0078] 1. Coke oven 2. Dried Maine 3 Tar decanter 4. Ammonia tank 5 Sludge settling tank 6 Super Decanter 7. Tar Tank 8 Primary Cooler 9 blast furnace

Claims

1. The method comprises adding a polymer flocculant to ammonia water containing suspended solids and oil, which is generated by washing and cooling coke oven gas with ammonia water, the suspended matter comprises coal-derived powder; The oil contains tar, The method for removing suspended solids and oil from ammonia water, wherein the polymer flocculant has a cationic colloid equivalent value at pH 4 of 1.0 to 3.5 meq / g.

2. 2. The method for removing suspended solids and oils from ammonia water according to claim 1, wherein the coal-derived powder has a number-based arithmetic mean diameter of 10 μm or less.

3. 3. The method for removing suspended solids and oil from ammonia water according to claim 2, wherein the coal-derived powder comprises coal-derived powder that has been dried to reduce its moisture content before being used to manufacture coke.

4. 2. The method for removing suspended solids and oil from ammonia water according to claim 1, wherein the polymer flocculant contains a structural unit derived from acrylamide and a structural unit derived from a monomer represented by the following general formula (1): (R in the general formula (1) １ represents a hydrogen atom or a methyl group, R ２ and R ３ each independently represents a methyl group or an ethyl group, R ４ represents a hydrogen atom, or a methyl group or ethyl group which may be substituted with an aromatic group, and X represents a counter anion with the ammonium cation in the general formula (1).

5. 2. The method for removing suspended solids and oils from ammonia water according to claim 1, wherein the weight average molecular weight of the polymer flocculant is 4,000,000 to 10,000,000.

6. 2. The method for removing suspended solids and oil from ammonia water according to claim 1, wherein the coke oven gas is a gas generated when charged coal containing coal that has been dried to reduce its moisture content before being used to manufacture coke is carbonized in a coke oven.

7. A polymer flocculant used in ammonia water containing suspended solids and oil, which is generated by washing and cooling coke oven gas with ammonia water, the suspended matter comprises coal-derived powder; The oil contains tar, The polymer flocculant for ammonia water has a cationic colloid equivalent value at pH 4 of 1.0 to 3.5 meq / g.

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