CN111303941A - Method for extracting montan wax from lignite - Google Patents

Abstract

The invention relates to the field of montan wax, and discloses a method for extracting montan wax from lignite. The method comprises: (1) leaching lignite particles with an organic solvent, and performing solid-liquid separation to obtain a wax-containing liquid; (1) the wax-containing liquid is cooled, and an accelerator is added to the wax-containing liquid in the cooling process, and after crystallization, filtration and separation are performed to obtain a montan wax product; wherein the accelerator is polyacrylate-g- Polyvinyl ester. The method of the present invention extracts high-purity montan wax through the simple process of leaching--leaching liquid-solid-liquid separation--cooling--input accelerator--crystallization precipitation, wherein the resin content can reach below 5% by weight.

Description

Method for extracting montan wax from lignite

technical field

The invention relates to a method for extracting montan wax from lignite.

Background technique

The main components of montan wax are pure wax, resin and pitch. The composition of montan wax extracted from coal formed under different coal-forming plants and coal-forming environments is also different. Asphalt is a high melting point component, which is viscous, difficult to flow, and difficult to diffuse after heating, resulting in increased viscosity and poor fluidity. Resin is a vegetable resin with properties similar to rosin, and it is also sticky. Too high resin content will make montan wax sticky, affect the co-solubility of montan wax and other additives, and reduce the physical and mechanical properties of montan wax. Especially when used in floor wax, shoe polish and other products, the resin will make the surface of the floor or leather shoes not smooth, not only difficult to wax, but also easy to adhere to dust. Generally speaking, pitch and resin in montan wax are harmful components, the less the content, the better the quality of montan wax. In the crude wax of German montan wax, the resin content is generally less than 15%, which can basically meet the needs of many industrial applications; while in the crude wax of montan wax in my country, the resin content is usually higher, reaching 20 to 40%.

At present, there are few existing technologies for producing high-purity montan wax. The method disclosed in CN101906320A uses compounded organic solvents, and utilizes the different solubility of organic solvents to different components to improve the quality of montan wax products, and the resin content can be lower than 16 %, products with bitumen content less than 6%.

The resin content in the montan wax obtained by the above method is still very high, therefore, there is an urgent need for a simple method that can extract higher purity montan wax from montan.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a method for extracting montan wax from lignite in order to overcome the problems of low purity of the obtained montan wax product existing in the prior art.

In order to achieve the above object, a first aspect of the present invention provides a method for extracting montan wax from lignite, the method comprising:

(1) leach the lignite particles with an organic solvent, and carry out solid-liquid separation to obtain a wax-containing liquid;

(2) cooling the wax-containing liquid in step (1), adding an accelerator to the wax-containing liquid during the cooling process, and filtering and separating after crystallization to obtain a montan wax product; wherein the accelerator is polyacrylic acid Ester-g-polyvinyl ester.

The method of the invention extracts high-purity montan wax from lignite through the simple process of leaching--separation of leaching liquid-solid-liquid--cooling--adding accelerator--crystallization precipitation, wherein the resin content can reach below 5% by weight , the process also saves the degreasing step of the traditional method, shortens the cooling crystallization time, and has a good application prospect.

Description of drawings

1 is a schematic diagram of an embodiment of the method of the present invention;

Detailed ways

The endpoints of ranges and any values disclosed herein are not limited to the precise ranges or values, which are to be understood to encompass values proximate to those ranges or values. For ranges of values, the endpoints of each range, the endpoints of each range and the individual point values, and the individual point values can be combined with each other to yield one or more new ranges of values that Ranges should be considered as specifically disclosed herein.

A first aspect of the present invention provides a method for extracting montan wax from lignite, the method comprising:

(1) leach the lignite particles with an organic solvent, and carry out solid-liquid separation to obtain a wax-containing liquid;

(2) cooling the wax-containing liquid in step (1), adding an accelerator to the wax-containing liquid during the cooling process, and filtering and separating after crystallization to obtain a montan wax product; wherein the accelerator is polyacrylic acid Ester-g-polyvinyl ester.

Figure 1 shows an embodiment of the method of the present invention. In the present invention, polyacrylate-g-polyvinyl ester is a graft copolymer of acrylate and vinyl ester, wherein polyacrylate is the main chain, and polyvinyl ester is grafted on the main chain. The general formula of the vinyl ester is R ₁ COOCH ₂ =CH ₂ , wherein R ₁ is a C ₁ -C ₈ alkyl group, and the general formula of the acrylate is CH ₂ =CH ₂ COOR ₂ , wherein R ₂ is C ₁ - _C8 alkyl.

In the present invention, the particle size of the lignite particles is less than 15 mm, preferably, the particle size of the lignite particles is less than 3 mm. Preferably, the lignite is crushed and sieved before extracting the montan wax. For example, the lignite may be added to a crusher for crushing treatment, and then sieved with a sieve with an aperture of 3 mm. The lignite particles with a particle size of less than 3mm are dried for later use, and the lignite particles larger than 3mm are returned to the previous pulverization step to be pulverized and sieved together with the raw lignite.

In a preferred embodiment of the method of the present invention, the lignite particles are first dried to a moisture content of 15-30% by weight, more preferably 25% by weight.

In the method of the present invention, the organic solvent may be a polar or non-polar solvent, a single solvent or a mixture of multiple solvents, for example, selected from toluene, petroleum ether, 6# solvent oil, n-hexane, cyclic One of hexane, ethanol, isopropanol, n-propanol, acetone, methyl ethyl ketone, methyl ethyl ketone, methyl formate, methyl acetate, ethyl formate, ethyl acetate, butyl acetate, propyl acetate one or more, preferably ethanol, ethyl acetate or acetone.

In the method of the present invention, in step (1), the leaching conditions include: the temperature is 70-100°C, and the time is 0.5-4h; preferably, the temperature is 80-100°C, and the time is 1- 3h. The leaching solution obtained after the leaching is carried out sedimentation and solid-liquid separation to obtain wax-containing liquid and dewaxed coal without solid impurities. During the whole process of sedimentation and solid-liquid separation, the temperature of the leaching solution was maintained above 50°C to prevent wax precipitation. Preferably, the solid-liquid separation is performed at a temperature of 50°C-100°C.

In the method of the present invention, in order to better realize that the montan wax crystallizes out without the resin precipitation during the cooling process, the concentration of the wax-containing liquid needs to be controlled within a suitable range, for example, the concentration of the montan wax in the wax-containing liquid is 30-200g/L, preferably 30-150g/L. Here, the concentration of montan wax in the wax-containing liquid should be understood as the ratio of the mass of the product obtained after the solvent contained in the wax-containing liquid is evaporated to the volume of the wax-containing liquid.

In step (2) of the method of the present invention, the wax-containing liquid is cooled and crystallized. The cooling crystallization conditions include: the temperature is -10°C to 30°C, and the duration is 10-90 minutes; preferably, the temperature is 0-25°C, and the duration is 10-60 minutes.

The inventor of the present invention found that adding an accelerator (polyacrylate-g-polyvinyl ester) in the process of cooling the wax-containing liquid can not only significantly shorten the cooling and crystallization time, but also effectively improve the purity and yield of the montan wax. Rate. The accelerator is selected from polymethyl acrylate-g-polyvinyl acetate, polyethyl acrylate-g-polyvinyl acetate, polybutyl acrylate-g-polyvinyl acetate, polypropyl acrylate-g-polyvinyl acetate. One or more of vinyl valerate, polybutyl acrylate-g-polyvinyl propionate and polybutyl acrylate-g-polyvinyl butyrate, preferably, the accelerator is polybutyl acrylate- g-polyvinyl butyrate.

According to the present invention, the addition amount of the accelerator affects the cooling crystallization time on the one hand, and to a certain extent, the larger the addition amount, the shorter the crystallization time, but the excessive addition amount also affects the quality of the obtained montan wax. Therefore, in a preferred embodiment of the method of the present invention, relative to 1 L of the wax-containing liquid, the addition amount of the accelerator is 0.1-5 g, such as 0.1, 0.2, 0.5, 0.6, 0.8 , 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5g, and any value in the range composed of any two of the above-mentioned values, preferably 0.5-1g.

According to the present invention, in a preferred embodiment, the particle size of the accelerator is less than 1 mm, more preferably, less than 0.2 mm.

According to the present invention, the accelerator can be prepared by the following method: carry out solution polymerization of acrylate monomer and initiator, then add vinyl ester monomer to the reaction system to carry out graft polymerization, and after the reaction is completed, spray-drying to obtain accelerator. The conditions for the solution polymerization include: the temperature is 90-110° C., the time is 1-3 hours; the solvent is at least one selected from the group consisting of No. 200 solvent oil, p-xylene, naphtha, and diesel oil. The initiator used is selected from benzoyl peroxide, lauroyl peroxide and the like.

In the method of the present invention, after the montan wax is crystallized out, the suspension containing the montan wax particles is filtered and separated to obtain wet wax particles and a filtrate, and the filtrate is a resin-containing degreasing solution.

The method of the present invention further comprises the step of drying the wet wax particles, and the montan wax product is obtained after drying. The drying conditions can be selected according to the prior art, for example, the drying conditions include: the temperature is 80-130°C, preferably 90-100°C. In one embodiment, the steam obtained in the drying process is condensed and returned to step (1) for leaching the lignite particles.

In an embodiment of the method of the present invention, the method further comprises recycling the filtrate obtained by filtering step (2) to step (1) for leaching the lignite particles.

According to the method of the present invention, after multiple cycles, when the filtrate, namely the degreasing liquid, reaches saturation (wherein the resin content is greater than 40% by weight), the cycle is stopped, the obtained filtrate is distilled, and the resin product can be obtained at the bottom of the tower, and the vapor at the top of the tower is cooled after cooling. , cycle to step (1) for leaching lignite particles.

The method of the invention extracts as much montan wax from lignite as possible by using organic solvent at higher leaching temperature, while at lower temperature, due to the different solubility of montan wax and resin in organic solvent, The montan wax can be crystallized out, while the resin remains in the organic solvent. At the same time, the accelerator is added during the cooling process, which significantly shortens the crystallization time and improves the purity and yield of the montan wax. The method of the present invention makes the resin content in the obtained montan wax relatively low, for example, can be lower than 5% by weight, or even less than 2% by weight.

The present invention will be described in detail below by means of examples.

Example 1

(1) Preparation of accelerator: 500 mL of No. 200 solvent oil and p-xylene were uniformly mixed at a volume ratio of 1:1, added to the reaction kettle, stirred continuously, and heated to 100°C. After the temperature was stabilized, 100 mL of a mixture of butyl acrylate and benzoyl peroxide with a volume ratio of 100:2 was added to the reaction kettle, and the reaction was carried out for 2 h. Then 100 mL of vinyl butyrate was added to the reaction kettle, and the reaction was carried out for 1 h. After the completion of the reaction, through spray drying, the accelerator polybutyl acrylate-g-polyvinyl butyrate was obtained, and the particle size was 0.1 mm.

(2) Extract montan wax: pulverize the lignite to a particle size of less than 3 mm, take 50 g of lignite particles (wherein the pure wax content is 3.74% by weight) and a mixed solution of 100 mL of toluene and ethyl acetate (wherein the volume ratio of toluene and ethyl acetate is 1:1) leaching reaction was carried out at 90°C, and the reaction time was 3h. After filtration, dewaxed coal and wax-containing liquid (montan wax concentration of 32 g/L) were obtained. The obtained wax-containing liquid (montan wax concentration is 32g/L) is placed in a water cooling device at 5°C, and 0.07g of accelerator (step (1) gained polybutylacrylate-g-polyvinyl butyrate) is added simultaneously, After cooling for 10 min, the filtrate containing resin and wet montan wax particles were obtained by filtration. The wet montan wax particles were dried to obtain 1.77 g of montan wax product. After distillation of the resin-containing filtrate, a resin product is obtained. According to "GB/T 2559-2005 Method for Determination of Montan Wax", the content of montan wax products and resin products was analyzed, and the results are shown in Table 1 below.

Example 2

(1) Prepare the accelerator with reference to the method described in step (1) of Example 1.

(2) Extraction of montan wax: pulverize the lignite to a particle size of less than 3 mm, take 50 g of lignite particles and 200 mL of cyclohexane for a leaching reaction at 80° C., the reaction time is 1 h. Dewaxed coal and wax-containing liquid are obtained after filtration. The wax-containing liquid (concentrated to 30ml, wherein the montan wax concentration is 100g/L) is placed in a water cooling device at 15°C, and 0.015g of accelerator is added simultaneously, and after low-temperature cooling for 60min, the filtrate containing resin and wet lignite are obtained by filtration. Wax particles. The wet montan wax particles are dried to obtain a montan wax product. After distillation of the resin-containing filtrate, a resin product is obtained. According to "GB/T 2559-2005 Method for Determination of Montan Wax", the content of montan wax products and resin products was analyzed, and the results are shown in Table 1 below.

Example 3

(1) Prepare the accelerator with reference to step (1) of Example 1.

(2) Extraction of montan wax: pulverize the lignite to a particle size of less than 3 mm, take 50 g of lignite particles and 250 mL of petroleum ether for a leaching reaction at 70° C. for a reaction time of 2 h. Dewaxed coal and wax-containing liquid are obtained after filtration. The wax-containing liquid (concentrated to 20ml, wherein the montan wax concentration is 146g/L) is placed in a water cooling device at 25°C, and 0.02g of accelerator is added simultaneously, and after low-temperature cooling for 30min, the filtrate and wet lignite containing resin are obtained by filtration. Wax particles. The wet montan wax particles are dried to obtain a montan wax product. After distillation of the resin-containing filtrate, a resin product is obtained. According to "GB/T 2559-2005 Method for Determination of Montan Wax", the content of montan wax products and resin products was analyzed, and the results are shown in Table 1 below.

Example 4

The montan wax was extracted with reference to the method described in Example 1, except that the amount of the accelerator used was 0.6 g, and the others were the same as in Example 1. According to "GB/T 2559-2005 Method for Determination of Montan Wax", the content of the obtained montan wax product and resin product is analyzed, and the results are shown in Table 1 below.

Example 5

The montan wax was extracted with reference to the method described in Example 1, except that the amount of the accelerator used was 0.008 g, and the others were the same as those in Example 1. According to "GB/T 2559-2005 Method for Determination of Montan Wax", the content of the obtained montan wax product and resin product is analyzed, and the results are shown in Table 1 below.

Example 6

The montan wax was extracted with reference to the method described in Example 1, except that the particle size of the accelerator used was 2 mm, and the others were the same as in Example 1. According to "GB/T 2559-2005 Method for Determination of Montan Wax", the content of the obtained montan wax product and resin product is analyzed, and the results are shown in Table 1 below.

Example 7

The montan wax was extracted with reference to the method described in Example 1, except that the accelerator used was prepared by the following method: 400 mL of No. 200 solvent oil was added to the reactor, stirred continuously, and heated to 110°C. After the temperature was stabilized, 100 mL of a mixture of butyl acrylate and benzoyl peroxide with a volume ratio of 100:2 was added to the reaction kettle, and the reaction was carried out for 2 h. Then 150 mL of vinyl propionate was added to the reaction kettle, and the reaction was carried out for 1 h. After completion of the reaction, spray drying was carried out to obtain the accelerator polybutyl acrylate-g-polyvinyl propionate with a particle size of 0.1 mm. Others are the same as in Example 1. According to "GB/T 2559-2005 Method for Determination of Montan Wax", the content of the obtained montan wax product and resin product is analyzed, and the results are shown in Table 1 below.

Example 8

The montan wax was extracted with reference to the method described in Example 1, except that the used accelerator was prepared by the following method: 500 mL of p-xylene was added to the reactor, stirred continuously, and heated to 90°C. After the temperature was stabilized, 80 mL of a mixed solution of ethyl acrylate and benzoyl peroxide with a volume ratio of 100:2 was added to the reaction kettle and reacted for 2 h. Then 100 mL of vinyl acetate was added to the reaction kettle, and the reaction was carried out for 2 h. After the reaction is completed, spray drying is carried out to obtain the accelerator polyethyl acrylate-g-polyvinyl acetate, and the particle size is 0.1 mm. Others are the same as in Example 1. According to "GB/T 2559-2005 Method for Determination of Montan Wax", the content of the obtained montan wax product and resin product is analyzed, and the results are shown in Table 1 below.

Example 9

(1) Preparation of accelerator: 500 mL of No. 200 solvent oil and naphtha were uniformly mixed according to a volume ratio of 1:1, added to the reaction kettle, stirred continuously, and heated to 100°C. After the temperature was stabilized, 100 mL of a mixture of propyl acrylate and benzoyl peroxide with a volume ratio of 100:1 was added to the reaction kettle, and the reaction was carried out for 1 h. Then 40 mL of vinyl valerate was added to the reaction kettle, and the reaction was carried out for 2 h. After the reaction is completed, spray drying is carried out to obtain the accelerator polypropyl acrylate-g-polyvinyl valerate, and the particle size is 0.15 mm.

(2) Extraction of montan wax: pulverize the lignite to a particle size of less than 3 mm, take 50 g of lignite particles and 200 mL of ethyl acetate for a leaching reaction at 70° C. for a reaction time of 4 h. Dewaxed coal and wax-containing liquid are obtained after filtration. The wax-containing liquid (concentrated to 104mL, wherein the montan wax concentration is 30g/L) is placed in a water cooling device at -10°C, and 0.625g of accelerator (step (1) gained polypropyl acrylate-g-polyacrylate) is added simultaneously. Vinyl valerate), cooled at low temperature for 80 min, filtered to obtain filtrate containing resin and wet montan wax particles. The wet montan wax particles are dried to obtain a montan wax product. After distillation of the resin-containing filtrate, a resin product is obtained. According to "GB/T 2559-2005 Method for Determination of Montan Wax", the content of montan wax products and resin products was analyzed, and the results are shown in Table 1 below.

Comparative Example 1

The montan wax was extracted with reference to Example 1, except that no accelerator was added during the cooling process, and the rest were the same as those in Example 1. According to "GB/T 2559-2005 Method for Determination of Montan Wax", the content of the obtained montan wax products and resin products was analyzed, and the results are shown in Table 1 below.

Comparative Example 2

The montan wax was extracted with reference to Example 1, except that palm wax powder was added in the cooling process, and the rest were the same as those in Example 1. According to "GB/T 2559-2005 Method for Determination of Montan Wax", the content of the obtained montan wax products and resin products was analyzed, and the results are shown in Table 1 below.

Comparative Example 3

The montan wax was extracted with reference to Example 1. The difference is that the obtained wax-containing liquid was evaporated under reduced pressure to obtain a montan wax product. According to "GB/T 2559-2005 Method for Determination of Montan Wax", the content of the obtained montan wax product was analyzed, and the results are shown in Table 1 below.

Table 1 Composition analysis of montan wax products

The component content data of montan wax products in Table 1 are all test data, and the sum of each component content is about 100%.

Here, the pure wax yield is calculated according to the following formula:

P% = (W _{product wax} × ω _{product wax, wax %} )/(W _coal × ω _{coal, wax %} ) × 100%

In the formula, P represents the wax yield, %

W _coal represents the mass of lignite, g

Omega _{coal, wax} indicates the content of pure wax in lignite, %

W _{product wax} indicates the mass of the montan wax product, g

Omega _{product wax, wax} indicates the content of pure wax in the montan wax product, %.

It can be seen from the results in Table 1 that the resin content in the montan wax product obtained in the embodiment of the present invention is as low as 1.12% by weight, the pure wax content is more than 95% by weight, and even as high as more than 98% by weight. The wax yield of the method reaches more than 80%, even more than 90%. The method of the invention obtains a montan wax product with lower resin content through the process of leaching--separation of leaching liquid-solid-liquid--cooling--injection of accelerator--crystallization precipitation, which saves the tedious degreasing step in the prior art , while shortening the cooling crystallization time.

Claims (10)

1. A method for extracting montan wax from lignite, the method comprising: (1) leach the lignite particles with an organic solvent, and carry out solid-liquid separation to obtain a wax-containing liquid; (2) cooling the wax-containing liquid described in step (1), adding an accelerator to the wax-containing liquid during the cooling process, and filtering and separating after crystallization to obtain a montan wax product; Wherein the accelerator is polyacrylate-g-polyvinyl ester. 2. method according to claim 1, wherein, in step (2), described accelerator is selected from polymethyl acrylate-g-polyvinyl acetate, polyethyl acrylate-g-polyvinyl acetate, Among polypropyl acrylate-g-polyvinyl valerate, polybutyl acrylate-g-polyvinyl acetate, polybutyl acrylate-g-polyvinyl propionate and polybutyl acrylate-g-polyvinyl butyrate One or more of, preferably, the accelerator is polybutyl acrylate-g-polyvinyl butyrate. 3. The method according to claim 1 or 2, wherein, in step (2), the addition amount of the accelerator is 0.1-5 g, preferably 0.5-1 g, relative to 1 L of the wax-containing liquid. 4. The method according to claim 1 or 2, wherein, in step (2), the particle size of the accelerator is less than 1 mm, preferably less than 0.2 mm. 5. The method according to claim 1 or 2, wherein the accelerator is prepared by the following method: carry out solution polymerization with acrylate monomer and initiator, then add vinyl ester monomer to the reaction system and carry out grafting Polymerization, after the reaction is completed, the accelerator is obtained by spray drying. 6. The method according to claim 1 or 2, wherein, in step (1), the organic solvent is selected from toluene, petroleum ether, 6# solvent oil, n-hexane, cyclohexane, ethanol, isopropanol , one or more of n-propanol, acetone, methyl ethyl ketone, methyl ethyl ketone, methyl formate, methyl acetate, ethyl formate, ethyl acetate, butyl acetate, propyl acetate, preferably, The organic solvent is ethanol, ethyl acetate or acetone. 7. The method according to claim 1 or 2, wherein, in step (1), the conditions of the leaching include: the temperature is 70-100°C, and the time is 0.5-4h; preferably, the temperature is 80-100°C 100 ℃, the time is 1-3h. 8. The method according to claim 1 or 2, wherein the concentration of montan wax in the wax-containing liquid is 30-200 g/L, preferably 30-150 g/L. 9. The method according to claim 1 or 2, wherein, in step (2), the conditions for crystallization by cooling include: the temperature is -10°C to 30°C, and the duration is 10-90min, preferably, the temperature is It is 0-25℃, and the duration is 10-60min. 10. The method according to claim 1 or 2, wherein the method further comprises recycling the filtrate obtained in step (2) to step (1) for leaching the lignite particles.

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