Coal water slurry and method for preparing the same

Abstract

The application discloses a kind of coal-water slurry and its preparation method, the coal-water slurry of the application includes the following components: superfine coal slurry, coal powder, additive and water;The superfine coal slurry is prepared by mixing flotation clean coal with additive and water, and is prepared by superfine grinding;The average particle size of the superfine coal slurry is 10-20 μm, and the dry basis concentration is 35-50 wt%;The particle size of the coal powder is 0.2-2.5 mm.The coal-water slurry of the application makes full use of the advantages of high water content and fine particle size of flotation clean coal, and prepares superfine coal slurry with an average particle size of 10-20 μm by superfine grinding, and mixes with coal powder with a particle size of 0.2-2.5 mm, realizes the intermittent grading of coal-water slurry particles, effectively improves the concentration of coal-water slurry, and solves the difficulties of coal slime treatment in the coal industry, and has great market application prospect.

Description

Technical Field

[0001] This invention relates to the field of coal chemical technology, specifically to a coal-water slurry and its preparation method. Background Technology

[0002] Coal-water slurry is a liquid mixture prepared from coal, water, and additives of different particle sizes through shearing and other methods, and can be used as a gasification feedstock. Slurry concentration is a key performance indicator in the coal-water slurry production process; a low slurry concentration will reduce the gasification efficiency of the coal-water slurry.

[0003] Currently, most domestic enterprises use single-bar / ball milling processes (first-generation slurry technology) for their coal-water slurry preparation systems. While this process is simple, it suffers from problems such as unreasonable particle size distribution, generally low slurry concentration, and poor flowability and stability. The second-generation staged grinding coal-water slurry preparation technology, which is gradually becoming mainstream, combines coarse and fine mills to optimize particle size distribution and improve slurry concentration. Therefore, increasing slurry concentration and thereby enhancing the efficiency and economy of coal-water slurry gasification is a crucial research direction for the development of the coal-water slurry industry.

[0004] The main challenge in coal preparation for thermal coal is the treatment and utilization of coal slime. Flotation is the most effective and widely used method. However, the flotation clean coal has characteristics such as fine particle size and high moisture content. There are still many problems with treatment methods such as blending and selling or burning for power generation. For example, it can lead to a decline in product quality and may also aggravate the emission of pollutants such as smoke and sulfur dioxide. Large-scale storage or transportation can cause wind dust and black water pollution. How to make comprehensive use of coal and achieve efficient and clean utilization has become an urgent technical problem for the coal industry. Summary of the Invention

[0005] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention propose a method for preparing a coal-water slurry using multiple raw materials, including flotation clean coal and pulverized coal.

[0006] The coal-water slurry of this invention comprises the following components: ultrafine coal slurry, coal powder, additives, and water; the ultrafine coal slurry is prepared by mixing flotation clean coal with additives and water, and then ultrafine grinding; the average particle size of the ultrafine coal slurry is 10-20 μm, and the dry basis concentration is 35-50 wt%; the particle size of the coal powder is 0.2-2.5 mm.

[0007] The coal-water slurry of this invention fully utilizes the advantages of high water content and fine particle size of the flotation clean coal. It is prepared by ultra-fine grinding to obtain an ultra-fine coal slurry with an average particle size of 10-20 μm, and mixed with coal powder with a particle size of 0.2-2.5 mm. This achieves discontinuous gradation of the coal-water slurry particles, effectively increases the concentration of the coal-water slurry, and realizes the resource utilization of the flotation clean coal, which has great market application prospects.

[0008] In some embodiments, the dry basis mass ratio of the ultrafine coal slurry to the coal powder is (20-40):(60-80).

[0009] Preferably, the mass ratio is (30-40):(60-70).

[0010] In some embodiments, the concentration of the coal-water slurry is 65–68 wt%.

[0011] In some embodiments, the amount of additive used in the coal-water slurry is 0.1 to 0.5% of the sum of the dry basis mass of the ultrafine coal slurry and the coal powder.

[0012] In some embodiments, the amount of additives used in the ultrafine coal slurry is 0.1 to 0.5% of the dry basis mass of the flotation clean coal.

[0013] In some embodiments, the dry basis concentration of the ultrafine coal slurry is 40–45 wt%.

[0014] In some embodiments, the flotation clean coal is clean coal separated from coal slime in a coal preparation plant by flotation technology, and then dewatered by a filter press. The moisture content is 28-35%, the ash content is ≤10%, and more than 60% of the particles have a diameter of ≤45μm.

[0015] In some embodiments, the raw coal for flotation clean coal is a low- or medium-rank coal.

[0016] In some embodiments, the raw coal for the pulverized coal is a low- or medium-rank coal.

[0017] In some embodiments, the additive is one or more of lignin sulfonate, humate, or naphthalene sulfonate formaldehyde condensate.

[0018] This invention also provides a method for preparing the above-mentioned coal-water slurry, comprising the following steps:

[0019] (1) Crush the raw coal to obtain coal powder with a particle size of 0.2 to 2.5 mm;

[0020] (2) Mix the flotation clean coal with additives and water, homogenize it, and then grind it into ultrafine particles to obtain an ultrafine coal slurry with an average particle size of 10-20 μm and a dry basis mass percentage concentration of 35-50%.

[0021] (3) The ingredients are prepared according to the dry basis mass ratio of ultrafine coal slurry to coal powder of (20-40): (60-80). After mixing the ultrafine coal slurry, coal powder, additives and water, the mixture is homogenized to obtain the coal-water slurry.

[0022] In some embodiments, the particle size of the raw coal in step (1) is ≤60mm; the raw coal is crushed in two stages, the output particle size of the first stage crushing is ≤10mm, and the output particle size of the second stage crushing is 0.2~2.5mm.

[0023] In some embodiments, the stirring rate of the homogenization process in step (2) is 50-80 rpm, using single or double stirring.

[0024] In some embodiments, the stirring rate of the homogenization process in step (3) is 60 to 100 rpm, using single or double stirring.

[0025] The present invention also provides the application of the above-mentioned coal-water slurry in the preparation of gasified coal-water slurry.

[0026] The present invention has the following beneficial effects:

[0027] (1) The coal-water slurry of the present invention makes full use of the advantages of high water content and fine particle size of the flotation clean coal itself. The ultrafine coal slurry with an average particle size of 10 to 20 μm is prepared by ultrafine grinding and mixed with coal powder with a particle size of 0.2 to 2.5 mm. This achieves discontinuous gradation of coal-water slurry particles. Since the discontinuous gradation of the present invention has a moderate particle ratio, the fine particles fill the pores of the coarse particles, effectively increasing the concentration of coal-water slurry.

[0028] (2) The present invention uses flotation clean coal for the preparation of coal-water slurry, which solves the dilemma of coal slime being difficult to treat and reuse in the coal industry and has huge market application prospects.

[0029] (3) The process flow of the present invention is simple and is a continuous production process. The overall energy consumption of the present invention is low. It can realize continuous and stable production of coal sorting and coal-water slurry preparation. The high-concentration finished coal-water slurry prepared is of excellent quality and has a wide range of uses. It can be used as coal-water slurry for gasification and can greatly improve gasification efficiency. Attached Figure Description

[0030] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0031] Figure 1 This is a schematic flowchart of the method for preparing coal-water slurry products according to an embodiment of the present invention.

[0032] Figure 2This is a particle size distribution model diagram of coal-water slurry according to an embodiment of the present invention. Detailed Implementation

[0033] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0034] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0035] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0036] The coal-water slurry of this invention comprises the following components: ultrafine coal slurry, coal powder, additives, and water; the ultrafine coal slurry is prepared by mixing flotation clean coal with additives and water, and then grinding it into ultrafine particles; the average particle size of the ultrafine coal slurry is 10-20 μm, and the dry basis concentration is 35-50 wt%; the particle size of the coal powder is 0.2-2.5 mm.

[0037] The coal-water slurry of this invention fully utilizes the advantages of high water content and fine particle size of the flotation clean coal. Ultrafine coal slurry with an average particle size of 10–20 μm is prepared through ultrafine grinding and mixed with coal powder with a particle size of 0.2–2.5 mm, achieving discontinuous gradation of the coal-water slurry particles (e.g., ...). Figure 2 The particle size distribution diagram shown effectively increases the concentration of coal-water slurry and realizes the resource utilization of flotation clean coal, which has huge market application prospects.

[0038] In some embodiments, the dry basis mass ratio of ultrafine coal slurry to coal powder is (20-40):(60-80), preferably (30-40):(60-70). Non-limiting examples include dry basis mass ratios of 20:80, 22:78, 25:75, 28:72, 35:65, 40:60, etc.

[0039] In some embodiments, the concentration of the coal-water slurry is 65–68 wt%.

[0040] In some embodiments, the amount of additive used in the coal-water slurry is 0.1% to 0.5% of the sum of the dry basis mass of the ultrafine coal slurry and the coal powder. Non-limiting examples include: 0.1%, 0.2%, 0.25%, 0.3%, 0.45%, 0.5%, etc.

[0041] In some embodiments, the additive in the ultrafine coal slurry is used at a rate of 0.1% to 0.5% of the dry weight of the flotation clean coal. Non-limiting examples include: 0.1%, 0.2%, 0.25%, 0.3%, 0.45%, 0.5%, etc.

[0042] In some embodiments, the dry basis concentration of the ultrafine coal slurry is 35-50 wt%, preferably 40-45 wt%. Non-limiting examples include 35 wt%, 38 wt%, 40 wt%, 42 wt%, 45 wt%, 47 wt%, 50 wt%, etc.

[0043] In some embodiments, flotation clean coal is clean coal separated from coal slime in a coal preparation plant by flotation technology, and then dewatered by a filter press. The moisture content is 28-35%, the ash content is ≤10%, and more than 60% of the particles have a diameter of ≤45μm.

[0044] In some embodiments, the feed coal for flotation clean coal is a low-rank or medium-rank coal. Examples of low-rank coal, without limitation, include long-flame coal and non-caking coal; examples of medium-rank coal, without limitation, include gas coal and bituminous coal.

[0045] In some embodiments, the raw coal for pulverized coal is a low-rank or medium-rank coal. Examples of low-rank coal, without limitation, include long-flame coal and non-caking coal; examples of medium-rank coal, without limitation, include gas coal and coking coal.

[0046] In some embodiments, the additive is one or more combinations of lignin sulfonate, humate, or naphthalene sulfonate formaldehyde condensate; the lignin sulfonate includes ammonium lignin sulfonate and / or sodium lignin sulfonate; the humate includes sodium humate and / or magnesium humate. Non-limiting examples include sodium lignin sulfonate, ammonium lignin sulfonate, sodium naphthalene sulfonate formaldehyde condensate, sodium humate, or combinations thereof, such as combinations of sodium naphthalene sulfonate formaldehyde condensate and ammonium lignin sulfonate, combinations of ammonium lignin sulfonate and magnesium humate, combinations of sodium naphthalene sulfonate formaldehyde condensate and sodium humate, etc.

[0047] like Figure 1 As shown, this embodiment of the invention also provides a method for preparing the above-mentioned coal-water slurry, comprising the following steps:

[0048] (1) Crush the raw coal to obtain coal powder with a particle size of 0.2 to 2.5 mm;

[0049] (2) Mix the flotation clean coal with additives and water, homogenize it, and then grind it into ultrafine particles to obtain an ultrafine coal slurry with an average particle size of 10-20 μm and a dry basis mass percentage concentration of 35-50%.

[0050] (3) The ingredients are prepared according to the dry basis mass ratio of ultrafine coal slurry to coal powder of (20-40): (60-80). After mixing the ultrafine coal slurry, coal powder, additives and water, the mixture is homogenized to obtain the coal-water slurry.

[0051] In some embodiments, the particle size of the raw coal in step (1) is ≤60mm; the raw coal is subjected to two-stage crushing, with the output particle size of the first stage crushing being ≤10mm and the output particle size of the second stage crushing being 0.2~2.5mm. Non-limiting examples include: the output particle size of the second stage crushing can be: 0.3~1mm, 0.35~1.2mm, 0.5~1.5mm, 0.4~1.2mm, 0.4~2mm, 0.25~2.4mm, etc.

[0052] In some embodiments, the stirring rate of the homogenization process in step (2) is 50 to 80 rpm, using single or double stirring.

[0053] In some embodiments, the stirring rate of the homogenization process in step (3) is 60 to 100 rpm, using single or double stirring.

[0054] The present invention also provides the application of the above-mentioned coal-water slurry in the preparation of gasified coal-water slurry.

[0055] In the embodiments and comparative examples of this invention, the test method for water separation rate is as follows: the coal-water slurry is placed in a 250ml beaker and left to stand for 24 hours. The percentage of the water in the upper layer accounts for the total mass of the coal-water slurry. Water separation rate = mass of water separation / total mass of coal-water slurry × 100%.

[0056] In this embodiment of the invention, the rheological properties of the coal-water slurry were tested as follows: apparent viscosity was tested using the GB / T18856.4 test method, and flowability was tested using the visual inspection method.

[0057] The flotation clean coal used in Examples 1-9 of this invention is flotation clean coal from the Buertai Coal Preparation Plant of Guoneng Shendong Coal Group, with total water Mt = 35%, dry basis ash Ad = 10%, and dry basis volatile matter Var = 35%.

[0058] The raw coal used in Examples 1-3 and Comparative Example 1 of this invention was a blended coal with a total water content (Mt) of 17% and a dry basis ash content (A). d =8%, dry basis volatile matter V d =32%.

[0059] The raw coal used in Examples 4-6 was Yangta coal, with a total water content (Mt) of 19% and an air-dried ash content (A). ad =6%, air-dried basis volatile matter V ad =34%.

[0060] The raw coal used in Examples 7-9 was Xiwang coal, with a total water content (Mt) of 12% and an air-dried ash content (A). ad =7%, air-dried basis volatile matter V ad =35%.

[0061] Example 1

[0062] A method for preparing coal-water slurry includes the following steps:

[0063] (1) The mixed coal (particle size ≤ 60 mm) is crushed in two stages. The output particle size of the first stage crushing is ≤ 10 mm, and the output particle size of the second stage crushing is 0.3 to 1 mm; coal powder with a particle size of 0.3 to 1 mm is obtained.

[0064] (2) Mix flotation clean coal with sodium lignosulfonate and water, homogenize at a stirring rate of 70 rpm, and then grind ultrafinely to obtain an ultrafine coal slurry with an average particle size of 15 μm and a dry basis mass percentage concentration of 45%.

[0065] (3) The ingredients are prepared according to the dry basis mass ratio of ultrafine coal slurry to coal powder of 25:75, and the amount of sodium lignosulfonate is 0.2% of the sum of the dry basis mass of ultrafine coal slurry and coal powder. After mixing ultrafine coal slurry, coal powder, sodium lignosulfonate and water, the mixture is homogenized at a stirring speed of 80 rpm to obtain the coal-water slurry.

[0066] The concentration of the coal-water slurry prepared in this embodiment is 65.62 wt%.

[0067] In this embodiment, the water separation rate of the coal-water slurry is 3%.

[0068] In this embodiment, the apparent viscosity of the coal-water slurry is 1020 mPa·s, and the fluidity is B.

[0069] Example 2

[0070] A method for preparing coal-water slurry includes the following steps:

[0071] (1) The mixed coal (particle size ≤ 60 mm) is crushed in two stages. The output particle size of the first stage crushing is ≤ 10 mm, and the output particle size of the second stage crushing is 0.3 to 1.5 mm; coal powder with a particle size of 0.3 to 1.5 mm is obtained.

[0072] (2) Mix the flotation clean coal with sodium lignosulfonate and water, and homogenize it at a stirring speed of 70 rpm. Then, grind it into ultrafine coal to obtain an ultrafine coal slurry with an average particle size of 20 μm and a dry basis mass percentage concentration of 46%.

[0073] (3) The ingredients are prepared according to the dry basis mass ratio of ultrafine coal slurry to coal powder of 30:70, and the amount of sodium lignosulfonate additive is 0.2% of the sum of the dry basis mass of ultrafine coal slurry and coal powder. After mixing ultrafine coal slurry, coal powder, sodium lignosulfonate and water, the mixture is homogenized at a stirring speed of 80 rpm to obtain the coal-water slurry.

[0074] The concentration of the coal-water slurry prepared in this embodiment is 66.54 wt%.

[0075] In this embodiment, the water separation rate of the coal-water slurry is 2.6%;

[0076] In this embodiment, the apparent viscosity of the coal-water slurry is 1075 mPa·s, and the fluidity is B+.

[0077] Example 3

[0078] A method for preparing coal-water slurry includes the following steps:

[0079] (1) The mixed coal (particle size ≤ 60 mm) is crushed in two stages. The output particle size of the first stage crushing is ≤ 10 mm, and the output particle size of the second stage crushing is 0.3 to 1 mm; coal powder with a particle size of 0.3 to 1 mm is obtained.

[0080] (2) Mix flotation clean coal with sodium naphthalene sulfonate formaldehyde condensate (NNO) and water, homogenize at a stirring rate of 80 rpm, and then grind into ultrafine particles to obtain an ultrafine coal slurry with an average particle size of 15 μm and a dry basis mass percentage concentration of 45%.

[0081] (3) The ingredients are prepared according to the dry basis mass ratio of ultrafine coal slurry to coal powder of 35:65. The amount of the additive sodium naphthalene sulfonate formaldehyde condensate is 0.2% of the sum of the dry basis mass of ultrafine coal slurry and coal powder. After mixing ultrafine coal slurry, coal powder, sodium naphthalene sulfonate formaldehyde condensate and water, the mixture is homogenized at a stirring speed of 90 rpm to obtain the coal-water slurry.

[0082] The concentration of the coal-water slurry prepared in this embodiment is 66.92 wt%.

[0083] In this embodiment, the water separation rate of the coal-water slurry is 2.1%;

[0084] In this embodiment, the apparent viscosity of the coal-water slurry is 1139 mPa·s, and the fluidity is B+.

[0085] Example 4

[0086] A method for preparing coal-water slurry includes the following steps:

[0087] (1) Yangta coal (particle size ≤ 60 mm) is crushed in two stages. The output particle size of the first stage crushing is ≤ 10 mm, and the output particle size of the second stage crushing is 0.32 to 1.5 mm; coal powder with a particle size of 0.32 to 1.5 mm is obtained.

[0088] (2) Mix the flotation clean coal with sodium naphthalene sulfonate formaldehyde condensate and water, and homogenize it at a stirring speed of 60 rpm. Then, grind it into ultrafine coal to obtain an ultrafine coal slurry with an average particle size of 20 μm and a dry basis mass percentage concentration of 42%.

[0089] (3) The ingredients are prepared according to the dry basis mass ratio of ultrafine coal slurry to coal powder of 30:70. The amount of the additive sodium naphthalene sulfonate formaldehyde condensate is 0.25% of the sum of the dry basis mass of ultrafine coal slurry and coal powder. After mixing ultrafine coal slurry, coal powder, sodium naphthalene sulfonate formaldehyde condensate and water, the mixture is homogenized at a stirring speed of 76 rpm to obtain the coal-water slurry.

[0090] The concentration of the coal-water slurry prepared in this embodiment is 66.51 wt%.

[0091] In this embodiment, the water separation rate of the coal-water slurry is 2.7%;

[0092] In this embodiment, the apparent viscosity of the coal-water slurry is 1135 mPa·s, and the fluidity is B+.

[0093] Example 5

[0094] A method for preparing coal-water slurry includes the following steps:

[0095] (1) Yangta coal (particle size ≤ 60 mm) is crushed in two stages. The output particle size of the first stage crushing is ≤ 10 mm, and the output particle size of the second stage crushing is 0.35 to 1.5 mm; coal powder with a particle size of 0.35 to 1.5 mm is obtained.

[0096] (2) Mix flotation clean coal with sodium naphthalene sulfonate formaldehyde condensate (NNO) and water, homogenize at a stirring speed of 60 rpm, and then grind into ultrafine particles to obtain an ultrafine coal slurry with an average particle size of 20 μm and a dry basis mass percentage concentration of 40%.

[0097] (3) The ingredients are prepared according to the dry basis mass ratio of ultrafine coal slurry to coal powder of 30:70. The amount of the additive sodium naphthalene sulfonate formaldehyde condensate is 0.25% of the sum of the dry basis mass of ultrafine coal slurry and coal powder. After mixing ultrafine coal slurry, coal powder, sodium naphthalene sulfonate formaldehyde condensate and water, the mixture is homogenized at a stirring speed of 76 rpm to obtain the coal-water slurry.

[0098] The concentration of the coal-water slurry prepared in this embodiment is 66.87 wt%.

[0099] In this embodiment, the water separation rate of the coal-water slurry is 3%.

[0100] In this embodiment, the apparent viscosity of the coal-water slurry is 1054 mPa·s, and the fluidity is B+.

[0101] Example 6

[0102] A method for preparing coal-water slurry includes the following steps:

[0103] (1) Yangta coal (particle size ≤ 60 mm) is crushed in two stages. The output particle size of the first stage crushing is ≤ 10 mm, and the output particle size of the second stage crushing is 0.3 to 1.5 mm; coal powder with a particle size of 0.3 to 1.5 mm is obtained.

[0104] (2) Mix flotation clean coal with sodium naphthalene sulfonate formaldehyde condensate (NNO) and water, homogenize at a stirring speed of 60 rpm, and then grind into ultrafine particles to obtain an ultrafine coal slurry with an average particle size of 20 μm and a dry basis mass percentage concentration of 42%.

[0105] (3) The ingredients are prepared according to the dry basis mass ratio of ultrafine coal slurry to coal powder of 40:60. The amount of the additive sodium naphthalene sulfonate formaldehyde condensate is 0.25% of the sum of the dry basis mass of ultrafine coal slurry and coal powder. After mixing ultrafine coal slurry, coal powder, sodium naphthalene sulfonate formaldehyde condensate and water, the mixture is homogenized at a stirring speed of 90 rpm to obtain the coal-water slurry.

[0106] The concentration of the coal-water slurry prepared in this embodiment is 66.2 wt%.

[0107] In this embodiment, the water separation rate of the coal-water slurry is 1.9%;

[0108] In this embodiment, the apparent viscosity of the coal-water slurry is 1241 mPa·s, and the fluidity is B+.

[0109] Example 7

[0110] A method for preparing coal-water slurry includes the following steps:

[0111] (1) The Xiwang coal (particle size ≤ 60 mm) is crushed in two stages. The output particle size of the first stage crushing is ≤ 10 mm, and the output particle size of the second stage crushing is 0.25 to 2.4 mm; coal powder with a particle size of 0.25 to 2.4 mm is obtained.

[0112] (2) Mix the flotation clean coal with additives and water, homogenize it at a stirring rate of 76 rpm, and then grind it into ultrafine particles to obtain an ultrafine coal slurry with an average particle size of 18 μm and a dry basis mass percentage concentration of 44%.

[0113] (3) The ingredients are prepared according to the dry basis mass ratio of ultrafine coal slurry to coal powder of 40:60, and the amount of additive is 0.3% of the sum of the dry basis mass of ultrafine coal slurry and coal powder. After mixing ultrafine coal slurry, coal powder, additive and water, the mixture is homogenized at a stirring speed of 100 rpm to obtain the coal-water slurry.

[0114] In this embodiment, the additives used in steps (2) and (3) are: sodium naphthalene sulfonate formaldehyde condensate and sodium lignin sulfonate compounded in a mass ratio of 7:3.

[0115] The concentration of the coal-water slurry prepared in this embodiment is 67.86 wt%.

[0116] In this embodiment, the water separation rate of the coal-water slurry is 2.6%;

[0117] In this embodiment, the apparent viscosity of the coal-water slurry is 1346 mPa·s, and the fluidity is B+.

[0118] Example 8

[0119] A method for preparing coal-water slurry includes the following steps:

[0120] (1) The Xiwang coal (particle size ≤ 60 mm) is crushed in two stages. The output particle size of the first stage crushing is ≤ 10 mm, and the output particle size of the second stage crushing is 0.25 to 2.4 mm; coal powder with a particle size of 0.25 to 2.4 mm is obtained.

[0121] (2) Mix the flotation clean coal with additives and water, and homogenize it at a stirring rate of 76 rpm. Then, grind it into ultrafine coal to obtain an ultrafine coal slurry with an average particle size of 12 μm and a dry basis mass percentage concentration of 38%.

[0122] (3) The ingredients are prepared according to the dry basis mass ratio of ultrafine coal slurry to coal powder of 40:60, and the amount of additive is 0.3% of the sum of the dry basis mass of ultrafine coal slurry and coal powder. After mixing ultrafine coal slurry, coal powder, additive and water, the mixture is homogenized at a stirring speed of 100 rpm to obtain the coal-water slurry.

[0123] In this embodiment, the additives used in steps (2) and (3) are: sodium naphthalene sulfonate formaldehyde condensate (NNO) and sodium lignin sulfonate in a mass ratio of 8:2.

[0124] The concentration of the coal-water slurry prepared in this embodiment is 67.94 wt%.

[0125] In this embodiment, the water separation rate of the coal-water slurry is 2.1%;

[0126] In this embodiment, the apparent viscosity of the coal-water slurry is 1392 mPa·s, and the fluidity is B+.

[0127] Example 9

[0128] A method for preparing coal-water slurry includes the following steps:

[0129] (1) The Xiwang coal (particle size ≤ 60 mm) is crushed in two stages. The output particle size of the first stage crushing is ≤ 10 mm, and the output particle size of the second stage crushing is 0.25 to 2.4 mm; coal powder with a particle size of 0.25 to 2.4 mm is obtained.

[0130] (2) Mix the flotation clean coal with additives and water, homogenize it at a stirring rate of 76 rpm, and then grind it into ultrafine particles to obtain an ultrafine coal slurry with an average particle size of 18 μm and a dry basis mass percentage concentration of 44%.

[0131] (3) The ingredients are prepared according to the dry basis mass ratio of ultrafine coal slurry to coal powder of 22:78, and the amount of additive is 0.3% of the sum of the dry basis mass of ultrafine coal slurry and coal powder. After mixing ultrafine coal slurry, coal powder, additive and water, the mixture is homogenized at a stirring speed of 100 rpm to obtain the coal-water slurry.

[0132] In this embodiment, the additives used in steps (2) and (3) are: sodium naphthalene sulfonate formaldehyde condensate and sodium lignin sulfonate compounded in a mass ratio of 7:3.

[0133] The concentration of the coal-water slurry prepared in this embodiment is 66.52 wt%.

[0134] In this embodiment, the water separation rate of the coal-water slurry is 2.9%;

[0135] In this embodiment, the apparent viscosity of the coal-water slurry is 1034 mPa·s, and the fluidity is B.

[0136] Comparative Example 1

[0137] A method for preparing coal-water slurry includes the following steps:

[0138] (1) Crush the Shenyun coal into coal powder with a particle size ≤60mm;

[0139] (2) The coal powder and sodium lignosulfonate described in step (1) are mixed with water at a dry basis mass ratio of 100:0.2 and transported to a rod mill. The coal slurry is mixed and ground by the impact and crushing action between the steel rods in the rod mill. The coal-water slurry ground to a certain particle size flows out from the outlet of the rod mill.

[0140] (3) The coal-water slurry prepared in step (2) is homogenized at a stirring rate of 80 rpm to obtain qualified coal-water slurry.

[0141] The concentration of the coal-water slurry prepared in this comparative example was 59.86%.

[0142] The water separation rate of the coal-water slurry in this comparative example is 6.2%;

[0143] The apparent viscosity of the coal-water slurry in this comparative example is 968 mPa·s, and its fluidity is B-.

[0144] As can be seen from Examples 1-9 and Comparative Example 1, this invention fully utilizes the advantages of high moisture content and fine particle size of the flotation clean coal itself. Ultrafine coal slurry with an average particle size of 10-20 μm is prepared through ultrafine grinding and mixed with coal powder with a particle size of 0.2-2.5 mm, achieving discontinuous gradation of the coal-water slurry particles and effectively increasing the concentration of the coal-water slurry. Furthermore, the prepared coal-water slurry exhibits excellent fluidity and stability, making it suitable as a coal-water slurry for gasification and significantly improving gasification efficiency.

[0145] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0146] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A coal-water slurry, characterized in that, The mixture comprises the following components: ultrafine coal slurry, coal powder, additive 1, and water; the ultrafine coal slurry is prepared by mixing flotation clean coal with additive 2 and water, and then grinding them into ultrafine particles; the average particle size of the ultrafine coal slurry is 10~20μm, and the dry basis concentration is 35~50wt%; the particle size of the coal powder is 0.2~2.5mm, and the concentration of the coal-water slurry is 65~68wt%.

2. The coal-water slurry according to claim 1, characterized in that, The dry basis mass ratio of the ultrafine coal slurry to the coal powder is (20~40):(60~80).

3. The coal-water slurry according to claim 1, characterized in that, In the coal-water slurry, the amount of additive 1 is 0.1 to 0.5% of the sum of the dry basis mass of the ultrafine coal slurry and the coal powder; in the ultrafine coal slurry, the amount of additive 2 is 0.1 to 0.5% of the dry basis mass of the flotation clean coal.

4. The coal-water slurry according to claim 3, characterized in that, Additive 1 is one or more of lignin sulfonate, humate or naphthalene sulfonate formaldehyde condensate; additive 2 is one or more of lignin sulfonate, humate or naphthalene sulfonate formaldehyde condensate.

5. The coal-water slurry according to claim 1, characterized in that, The dry basis concentration of the ultrafine coal slurry is 40~45 wt%.

6. The coal-water slurry according to claim 1, characterized in that, The flotation clean coal is clean coal separated from coal slime in a coal preparation plant through flotation technology, and then dewatered by a filter press. It has a moisture content of 28-35%, an ash content of ≤10%, and a particle size of ≤45μm for more than 60% of the coal.

7. The method for preparing coal-water slurry according to any one of claims 1 to 6, characterized in that, Includes the following steps: (1) Crush the raw coal to obtain coal powder with a particle size of 0.2~2.5mm; (2) Mix the flotation clean coal with additive 2 and water, homogenize it, and then grind it into ultrafine particles to obtain an ultrafine coal slurry with an average particle size of 10~20μm and a dry basis mass percentage concentration of 35~50%. (3) The ingredients are prepared according to the dry basis mass ratio of ultrafine coal slurry to coal powder of (20~40): (60~80). After mixing ultrafine coal slurry, coal powder, additive 1 and water, the mixture is homogenized to obtain the coal-water slurry.

8. The method for preparing coal-water slurry according to claim 7, characterized in that, In step (1), the particle size of the raw coal is ≤60mm; the raw coal is crushed in two stages, with the output particle size of the first stage crushing being ≤10mm and the output particle size of the second stage crushing being 0.2~2.5mm.

9. The method for preparing coal-water slurry according to claim 7, characterized in that, The stirring rate of the homogenization process in step (2) is 50~80 rpm; the stirring rate of the homogenization process in step (3) is 60~100 rpm.

10. The use of the coal-water slurry according to any one of claims 1 to 6 in the preparation of gasified coal-water slurry.

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