CN110898999A - Coal tar-based coal slime flotation reagent and preparation method thereof - Google Patents

Abstract

The invention discloses a coal tar-based coal slime flotation reagent which comprises the following substances in parts by weight: 10-90 parts of nonpolar hydrocarbon oil, 10-85 parts of coal tar, 0.5-2 parts of sorbitan fatty acid ester, 0.5-2 parts of polyethylene glycol and 0.5-1 part of propyl acetate. The above-mentioned materials are mixed, stirred, heated and stirred again, and after the above-mentioned processes are circulated for 1-10 times, it is stood still for 0.5-48 hr to obtain upper layer dilute liquor so as to obtain the invented coal slime flotation agent. According to the invention, the nonpolar hydrocarbon oil and the coal tar are mixed, so that the recovery rate of combustible bodies in the coal slime can be greatly improved, and the flotation effect is improved.

Description

Coal tar-based coal slime flotation reagent and preparation method thereof

Technical Field

The invention relates to a coal slime flotation reagent and a preparation method thereof, in particular to a coal tar-based coal slime flotation reagent and a preparation method thereof.

Background

China is a country rich in coal and little in oil, and coal is used as the most main fossil energy source in China. Although the consumption of other primary energy (oil and natural gas) is gradually increased along with the economic development, the energy storage characteristics of rich coal, poor oil and less gas in China and the obvious cost advantage of coal determine that the dominant position of coal in a primary energy consumption structure cannot be changed in a long time in the future. Coal is a mixture of organic and inorganic materials and therefore needs to be sorted before use. With the rapid development of national economy, the energy demand is continuously increased, coal with medium and high quality is exploited in large quantities, and the reserves are reduced day by day, however, the reserves are large, and the low-rank coal and the oxidized coal which are easy to obtain are not well utilized because of difficult effective separation.

The high-efficiency coal sorting technology is an important precondition for realizing clean and high-efficiency utilization of coal resources. Coal slime is a byproduct generated in the coal mining and sorting process, and accounts for 12-18% of the selected raw coal. Along with the continuous enhancement of the mechanization degree in the mining and washing processes, the coal slime content in the raw coal is continuously improved, the separation task is continuously increased, and the coal slime also has the characteristics of fineness, impurity, poverty and difficulty. Among them, flotation is the most mature and effective method for sorting coal smaller than 0.5mm at present, and is widely used for industrial production. In flotation, fine particle coal (< 0.5 mm) is often sorted using flotation machines and flotation columns. Generally, coal has a natural hydrophobicity, but this degree of hydrophobicity is not sufficient to float effectively, and a non-polar hydrocarbon oil such as diesel oil is often required as a collector to further increase the floatability of the coal particles. However, the separation and recovery of fine coal is affected by many factors such as the nature of the raw coal, the particle size of the coal, the degree of oxidation of the coal, and the like.

However, for coal slime difficult to float, such as low-grade/oxidized coal, coking middlings and the like, the surface of the coal slime often contains a large number of active groups, the groups are strong in hydrophilicity and poor in floatability, and traditional hydrocarbon oil is not easy to adhere to or spread on the surface of the coal slime, so that the coal slime flotation effect is still poor under the condition of high medicament dosage. In order to solve the technical problem, the current research mainly focuses on developing efficient flotation reagents or reagent combination methods, surface modification and the like to improve the hydrophobicity and selectivity of the surface of the difficultly floated coal. The method specifically comprises the technical means of adding various surfactants in the flotation process, ore grinding pretreatment, heating and pressurizing pretreatment, microwave or ultrasonic pretreatment, high-shear slurry mixing and the like. Although the above means can improve the flotation effect of the difficult-to-float coal, the cost of surface modification is high, and industrialization is difficult. Coal tar is a product of coal dry distillation, and is a substance obtained by thermal decomposition of coal at high temperature (i.e., high energy input), and is easily adhered to coal particles at low temperature/normal temperature. The coal tar contains a large amount of aromatic compounds, most of which are polycyclic and fused ring compounds with or without side chains and heterocyclic compounds containing oxygen, sulfur and nitrogen, and contains a small amount of aliphatic hydrocarbon, naphthenic hydrocarbon and unsaturated hydrocarbon, and the aromatic compounds, the polycyclic and fused ring compounds and the heterocyclic compounds can be effectively adhered to the nonpolar area of the coal particles and can be adhered to the polar area of the coal particles through large pi bonds or hydrogen bonds. In the past researches, researchers found that the yield of clean coal or coal ash refined carbon can be improved by simply treated emulsified coal tar and modified low-temperature coal tar, and the students analyzed the influence of fraction-washing oil of the coal tar or coal tar added into lignite to mix and grind coal slime for flotation. In addition, a few scholars directly apply coal tar to coal slime flotation, but the methods cannot greatly improve the recovery rate of combustible bodies in clean coal, and the coal tar or wash oil is directly applied to flotation, so that the cost is high, a large amount of coal tar is lost in the application process, and the environmental pollution is caused. Coal tar is used as a mixture with high viscosity, is extremely difficult to disperse in ore pulp, contains a large amount of substances which are useless for coal slime flotation, and can form a large amount of waste of coal tar resources if the coal tar is not treated. Therefore, the invention extracts the substances in the coal tar by the nonpolar hydrocarbon oil, utilizes the synergistic effect of the two substances or is matched with the sorbitan fatty acid ester, the polyethylene glycol and the propyl acetate to be taken as the auxiliary components in the invention, can improve the stability of the ore pulp, enhance the foamability of the ore pulp and the dispersibility of the medicament in the ore pulp, finally realize the great improvement of the yield of the coal slime flotation clean coal, and greatly increase the recovery rate of combustible bodies.

Disclosure of Invention

In view of the above analysis, the present invention aims to overcome the defects in the prior art, and provides a coal tar-based coal slurry flotation reagent and a preparation method thereof, which are used for upgrading clean coal, overcome the defects of the traditional technology for recovering clean coal by flotation of nonpolar hydrocarbon oil in coal slurry, and further provide an idea for solving the problems that the existing coal shortage and low-rank/oxidized coal resources cannot be effectively recovered and reused.

The purpose of the invention is mainly realized by the following technical scheme:

the coal tar-based coal slime (fine coal) flotation reagent is composed of the following substances in parts by weight: 10-90 parts of nonpolar hydrocarbon oil and 10-85 parts of coal tar;

the non-polar hydrocarbon oil includes: non-polar hydrocarbon oil collectors such as kerosene, modified kerosene, diesel oil, fuel oil, natural gas condensate and the like;

the coal tar comprises: low temperature coal tar, medium temperature coal tar, and high temperature coal tar.

The further improvement scheme is that the coal tar-based coal slime flotation reagent further comprises 0.5-2 parts of sorbitan fatty acid ester, 0.5-2 parts of polyethylene glycol and 0.5-1 part of propyl acetate.

The invention discloses a preparation method of a coal tar-based coal slime flotation reagent, which comprises the following steps:

mixing nonpolar hydrocarbon oil, coal tar, sorbitan fatty acid ester, polyethylene glycol and propyl acetate in proportion, stirring, heating, stirring again, circulating for 1-10 times, standing for 0.5-48 hours, and taking upper layer dilute solution as coal slime flotation agent;

heating, wherein the heating temperature is 40-200 ℃; the stirring time or the re-stirring time is 1-30 minutes.

In the flotation reagent disclosed by the invention, the nonpolar hydrocarbon oil is used as a solvent for extracting effective components in coal tar, has a hydrophobic effect on a nonpolar region on the surface of the coal slime, and has no obvious modification effect on a polar region on the surface of the coal slime. And a large amount of aromatic compounds in the coal tar can be adhered to polar and nonpolar areas of the coal particles through large pi bonds or hydrogen bonds, so that the surface hydrophobicity of the coal particles is effectively improved. Through stirring and heating the nonpolar hydrocarbon oil and the coal tar for multiple times, components which are beneficial to coal slime flotation in the coal tar are intensively extracted, finally, the hydrophobicity of the surfaces of coal particles can be effectively improved through the synergistic effect of a mixed reagent of the nonpolar hydrocarbon oil and the coal tar, the stability and the foamability of flotation foam and the dispersibility of the reagent in ore pulp can be enhanced through sorbitan fatty acid ester, polyethylene glycol and propyl acetate, the yield of clean coal for coal slime flotation is greatly improved, and the recovery rate of combustible bodies is increased.

Detailed Description

The present invention will be described in further detail with reference to examples.

Example 1

The coal tar-based coal slime flotation reagent is prepared by mixing 10 parts by weight of kerosene and 90 parts by weight of low-temperature coal tar. Mixing kerosene and low-temperature coal tar in proportion, stirring, heating and stirring again, circulating for 10 times in this way, standing for 0.5 hour, and taking upper-layer dilute solution as a coal slime flotation agent; the heating temperature is 100 ℃; the stirring time and the re-stirring time were both 20 minutes.

Example 2

The coal tar-based coal slime flotation reagent is prepared from 90 parts by weight of modified kerosene, 10 parts by weight of medium-temperature coal tar, 0.5 part by weight of sorbitan fatty acid ester, 2 parts by weight of polyethylene glycol and 1 part by weight of propyl acetate. Stirring, heating and stirring again, circulating for 8 times, standing for 24 hours, and taking the supernatant liquid as a coal slime flotation agent. The heating temperature is 150 ℃; the stirring time and the re-stirring time were both 1 minute.

The coal tar-based coal slime flotation reagent prepared by the embodiment is used for fine-grained coal slime flotation, and the specific flotation process flow is as follows:

1. adding fine coal slime (raw material) with the particle size of below 0.5mm into a flotation tank, adding tap water for size mixing, and stirring for 1-3 min;

2. adding a collecting agent into the ore pulp obtained in the step 1, stirring for 1-3min, adding a foaming agent, and stirring for 0.5-1 min;

3. and (3) filling air bubbles into the ore pulp in the step (2) for flotation. The flotation time is 3-5min, and the particles floated by the foam and the particles remained in the ore pulp are respectively collected to be used as final clean coal and tailing coal products.

4. And (3) the fine-grain coal slime in the step (1) is non-sticky coal.

5. The collecting agent in the step 2 is the novel collecting agent prepared by the invention, and compared with pure nonpolar hydrocarbon oil, the using amounts of the collecting agent and the pure nonpolar hydrocarbon oil are respectively 500 g/t, 1000g/t, 1500 g/t and 2000g/t of dry coal slime.

6. The foaming agent in the step 2 is secondary octanol, and the dosage is 150 g/t.

7. In the step 3, when different chemical dosages are used, compared with the traditional nonpolar hydrocarbon oil collector, the yield of the obtained clean coal is respectively increased by 23.52%, 53.64%, 58.21% and 51.46% under the condition that the ash content of the clean coal is not changed.

Example 3

Essentially the same as in example 2, except that:

the raw materials are mixed according to 50 parts by weight of diesel oil, 50 parts by weight of high-temperature coal tar, 2 parts by weight of sorbitan fatty acid ester, 0.5 part by weight of polyethylene glycol and 0.5 part by weight of propyl acetate. And (3) stirring, heating and stirring again, circulating for 5 times, standing for 48 hours, and taking the supernatant dilute solution as a coal slime flotation agent. The heating temperature is 60 ℃; the stirring time and the re-stirring time were both 5 minutes.

The coal tar-based coal slurry flotation reagent prepared in the embodiment is basically the same as that prepared in the embodiment 2 when used for fine-grained coal slurry flotation, except that:

1. the fine-grained coal slime in the embodiment is long-flame coal.

2. The use amounts of the collectors in the embodiment are 5000, 7000, 9000 and 11000g/t of dry coal slime respectively.

3. The amount of blowing agent used in this example was 1000 g/t.

4. In the embodiment, when the dosages of different reagents are used, the yield of the clean coal obtained by the collector prepared by the method is respectively increased by 8.18%, 13.01%, 21.45% and 24.35% compared with that of the clean coal obtained by the traditional nonpolar hydrocarbon oil collector; the ash content of the clean coal is respectively reduced by 2.01 percent, 4.35 percent, 1.99 percent and 2.10 percent.

Example 4

Essentially the same as in example 2, except that:

the raw materials are mixed according to 40 weight parts of fuel oil, 85 weight parts of high-temperature coal tar, 1 weight part of sorbitan fatty acid ester, 1 weight part of polyethylene glycol and 0.8 weight part of propyl acetate. And (3) stirring, heating and stirring again, circulating for 3 times, standing for 36 hours, and taking supernatant dilute solution as a coal slime flotation agent. The heating temperature is 40 ℃; the stirring time and the re-stirring time were both 30 minutes.

The coal tar-based coal slurry flotation reagent prepared in the embodiment is basically the same as that prepared in the embodiment 2 when used for fine-grained coal slurry flotation, except that:

1. the fine coal slime in the embodiment is coking coal.

2. The use amounts of the collecting agents in the embodiment are respectively 200, 500 and 800g/t of dry coal slime.

3. The amount of blowing agent used in this example was 50 g/t.

In the embodiment, when the dosages of different reagents are used, the yield of the clean coal obtained by the collector prepared by the method is increased by 2.44%, 3.11% and 4.28% respectively compared with that of the clean coal obtained by the traditional nonpolar hydrocarbon oil collector; the ash content of the clean coal changes from-0.21%, -1.35%, + 0.99%.

Example 5

Essentially the same as in example 2, except that:

the raw materials are prepared according to 50 parts by weight of natural gas condensed oil, 60 parts by weight of high-temperature coal tar, 1 part by weight of sorbitan fatty acid ester, 1 part by weight of polyethylene glycol and 0.8 part by weight of propyl acetate. Stirring, heating and standing for 12 hours, and taking supernatant dilute solution as a coal slime flotation agent. The heating temperature is 200 ℃; the stirring time and the re-stirring time were both 15 minutes.

The coal tar-based coal slurry flotation reagent prepared in the embodiment is basically the same as that prepared in the embodiment 2 when used for fine-grained coal slurry flotation, except that:

1. the fine coal slime in this embodiment is gas coal.

2. The use amounts of the collecting agents in the embodiment are 300 g/t, 600 g/t and 900g/t respectively.

3. The amount of blowing agent used in this example was 100 g/t.

In the embodiment, when the dosages of different reagents are used, the yield of the clean coal obtained by the collector prepared by the method is increased by 5.33%, 8.21% and 10.59% respectively compared with that of the clean coal obtained by the traditional nonpolar hydrocarbon oil collector; the ash content of the clean coal changes from-0.54%, +0.28%, + 1.55%.

Claims (5)

1. A fine coal flotation reagent, characterized in that: the flotation reagent comprises the following substances in parts by weight: 10-90 parts of nonpolar hydrocarbon oil and 10-85 parts of coal tar.

2. The fine coal flotation reagent of claim 1, wherein: the nonpolar hydrocarbon oil is kerosene, modified kerosene, diesel oil, fuel oil or natural gas condensed oil.

3. The fine coal flotation reagent of claim 1, wherein: the coal tar is low-temperature coal tar, medium-temperature coal tar or high-temperature coal tar.

4. A fine coal flotation reagent according to claim 1, 2 or 3, wherein: contains 0.5-2 parts of sorbitan fatty acid ester, 0.5-2 parts of polyethylene glycol and 0.5-1 part of propyl acetate.

5. A method of preparing a fine coal flotation reagent as claimed in any one of claims 1 to 4, comprising the steps of:

mixing nonpolar hydrocarbon oil, coal tar, sorbitan fatty acid ester, polyethylene glycol and propyl acetate in proportion, stirring, heating, stirring again, circulating for 1-10 times, standing for 0.5-48 hours, and taking upper layer dilute solution as coal slime flotation agent;

the heating temperature is 40-200 ℃; the stirring time or the re-stirring time is 1-30 minutes.