1. A method of extracting montan wax, comprising:

step S1: mixing lignite with an organic solvent, carrying out extraction treatment, and carrying out solid-liquid separation to obtain a wax-rich liquid;

step S2: filtering the wax-rich liquid to obtain filtered wax-rich liquid;

step S3: carrying out primary nanofiltration treatment on the filtered wax-rich liquid to obtain concentrated wax-rich liquid;

step S4: crystallizing the concentrated wax-rich liquid, and carrying out solid-liquid separation to obtain a solid phase and a filtrate;

step S5: and carrying out first desolventizing treatment on the solid phase to obtain the montan wax.

2. The method of claim 1, further comprising:

step S6: performing secondary nanofiltration treatment on the filtrate obtained in the step S4 to obtain a concentrated solution after secondary nanofiltration;

step S7: crystallizing the concentrated solution after the secondary nanofiltration, and carrying out solid-liquid separation to obtain a solid phase and a filtrate;

step S8: the solid phase obtained in step S7 is subjected to a second desolventizing treatment to obtain a resin.

3. The method according to claim 1 or 2, wherein the method further comprises subjecting the lignite extracted in the step S1 to a third desolventizing treatment, and cooling and humidifying the third desolventized lignite for other use, wherein preferably the temperature of the cooled and humidified lignite is 20-60 ℃, preferably 40-50 ℃, and the humidity is 20-30% of the water content.

4. The method according to any one of claims 1 to 3, wherein the recovered organic solvent from the first desolventizing treatment, the recovered organic solvent from the second desolventizing treatment, the recovered organic solvent from the third desolventizing treatment and the recovered organic solvent from the first nanofiltration and the recovered organic solvent from the second nanofiltration are combined and recycled to step S1 for use.

5. The method according to any one of claims 1 to 4, wherein in step S1, the lignite has a particle size of 1-6mm and a water content of 20-30%; and/or

The extraction temperature is 50-100 ℃, preferably 75-85 ℃; the time is 2-4 h; and/or

In the extraction, the mass ratio of the organic solvent to the lignite is 1-2: 1; and/or

The organic solvent is at least one selected from C6-C20 aromatic hydrocarbon, C1-C20 aliphatic hydrocarbon, C3-C20 naphthenic hydrocarbon, C1-C20 chlorinated hydrocarbon, C1-C20 alcohol and C2-C20 carboxylic ester; preferably, the organic solvent is selected from at least one of C6-C10 aromatic hydrocarbons, C1-C10 aliphatic hydrocarbons, C3-C10 cycloalkanes, C1-C10 chlorinated hydrocarbons, C1-C10 alcohols and C2-C10 carboxylic acid esters, more preferably, the molecular weight of the organic solvent is less than 150; further preferably, the C6-C20 aromatic hydrocarbon is selected from at least one of benzene, toluene and xylene; the C1-C20 aliphatic hydrocarbon is selected from at least one of petroleum ether, gasoline and n-hexane; the C3-C20 cycloalkane is selected from cyclohexane; the C1-C20 chlorinated hydrocarbon is selected from at least one of dichloroethylene, trichloroethylene, carbon tetrachloride and dichlorohexane; the C1-C20 alcohol is selected from at least one of methanol, ethanol, propanol, n-butanol and tert-butanol; the C2-C20 carboxylic ester is selected from at least one of ethyl acetate and butyl acetate.

6. The method according to any one of claims 1 to 5, wherein the filtration process in step S2 is a two-stage filtration, preferably the first stage filtration is a hydrocyclone filtration and the second stage filtration is a bag filter or a multi-tube bundle filter.

7. The method according to any of claims 1-6, wherein in step S3, the conditions of the primary nanofiltration comprise: the temperature is 30-80 ℃, preferably 40-60 ℃, and the pressure is 2-4.5 MPaG; and/or the nanofiltration membrane of the primary nanofiltration is selected from organic polymer nanofiltration membranes, preferably at least one of polyimide and polyacrylonitrile; or the molecular weight cut-off of the nanofiltration membrane of the first-stage nanofiltration is 300-800; and/or the concentration multiple of the concentrated wax-rich liquid is 1 to 3 times, preferably 1.2 to 2 times; and/or

In step S6, the conditions of the secondary nanofiltration include: the temperature is 30-80 ℃, preferably 40-60 ℃, and the pressure is 2-4.5 MPaG; and/or the molecular weight cut-off of the nanofiltration membrane of the secondary nanofiltration is 300-800; and/or the concentration multiple of the concentrated solution after the secondary nanofiltration is 1 to 3 times, and preferably 1.2 to 2 times.

8. The method according to any one of claims 1 to 7, wherein in step S4, the crystallization is cooling crystallization, preferably the cooling crystallization temperature is 15-25 ℃, preferably 18-22 ℃; and/or

In step S5, the first desolventizing treatment removes the organic solvent by evaporation; and/or

In step S8, the second desolventizing treatment removes the organic solvent by evaporation; and/or

The third desolventizing treatment removes the organic solvent by evaporation.

9. Montan wax obtained according to the method of any one of claims 1-8.

10. Use of a montan wax obtained according to the method of any one of claims 1 to 8 or a montan wax according to claim 9 in electric machines, precision casting, printing, paper making, textile and household chemicals.

Background

The montan wax is a mineral wax containing wax, resin and bitumen, which is extracted from annual light coal such as lignite or peat by using an organic solvent, and has different compositions of different coal-forming plants and the montan wax extracted from coal in a coal-forming environment. The montan wax has good physical and chemical properties: high melting point, hard and brittle texture, good moisture resistance, good chemical stability, high mechanical strength, bright surface like mirror, good insulativity, etc. The montan wax can be fused with other waxes, such as paraffin wax, beeswax, stearic acid and ceresin to form a stable tissue structure, and the melting point of the fused product is improved. Therefore, montan wax is widely used in various industrial fields, and is generally used as a high-end wax additive product in industries such as motors, precision casting, printing, paper making, textile, and daily chemicals. In particular, montan wax belongs to a plant source, is non-toxic and non-carcinogenic, and is increasingly applied to biological pharmacy in recent years. The montan wax is characterized in that any one of the synthetic wax and the natural wax cannot replace the existing synthetic wax or the natural wax.

The montan wax is a mixture mainly composed of resin, wax, bitumen and the like, and the content of the resin is required to be not more than 20% in the montan wax standard. In the crude wax of montan wax in China, the resin content is generally higher by 20 to 50 percent. Too high a resin content may cause stickiness of the montan wax, affect co-solubility of the montan wax with other additives, and reduce physical properties and mechanical properties of the montan wax. At present, the crude wax is obtained by extracting with an extractant, but the resin content in the crude wax is usually higher than 20%, so that the crude wax needs to be subjected to resin removal in a resin removal process to obtain a qualified montan wax product.

The typical extraction method of the montan wax currently applied is as follows: pulverizing lignite, granulating, drying, and extracting montan wax in an extractor. The solid phase from the extractor is sent to a desolventizer to be evaporated and recover the organic solvent for recycling, and the lignite granules with the solvent removed from the desolventizer can be further utilized. Evaporating and concentrating the liquid-phase wax-containing solvent from the extractor to recover the organic solvent for recycling, and performing vacuum concentration on the wax-containing solvent after most of the organic solvent is removed to obtain the montan wax.

The extracting agent which can be applied to the extraction of the montan wax comprises the following components: aromatic hydrocarbons such as benzene, toluene, xylene, etc.; hydrocarbons including aliphatic hydrocarbons and cycloalkanes such as petroleum ether, gasoline, n-hexane, cyclohexane, etc.; chlorinated hydrocarbons such as dichloroethylene, trichloroethylene, carbon tetrachloride, dichlorohexane and the like; alcohols such as methanol, ethanol, propanol, n-butanol, t-butanol, etc.; esters such as ethyl acetate, butyl acetate, and the like. The solvent can be used as a montan wax extracting agent alone or in combination.

In the existing lignite wax extraction process, after extracting lignite wax, an extracting agent is required to be heated, vaporized, condensed and recycled when being recycled, so that the energy consumption is high; when the liquid-phase wax-containing solvent from the extractor is subjected to multi-stage evaporation concentration and vacuum concentration, the montan wax is easy to crack and decompose in the process, the product quality is influenced, and the product yield is reduced; in addition, in the extraction process of the montan wax by using the ester solvent as the extractant, the solvent is decomposed due to repeated heating, the solvent loss is large, and the generated acid substances can corrode equipment.

Disclosure of Invention

In view of the above, in order to overcome the drawbacks of the prior art, the present invention aims to provide a method for extracting montan wax.

The invention provides a method for extracting montan wax, which comprises the following steps:

step S1: mixing lignite with an organic solvent, carrying out extraction treatment, and carrying out solid-liquid separation to obtain a wax-rich liquid;

step S2: filtering the wax-rich liquid to obtain filtered wax-rich liquid;

step S3: carrying out primary nanofiltration treatment on the filtered wax-rich liquid to obtain concentrated wax-rich liquid;

step S4: crystallizing the concentrated wax-rich liquid, and carrying out solid-liquid separation to obtain a solid phase and a filtrate;

step S5: and carrying out first desolventizing treatment on the solid phase to obtain the montan wax.

According to some embodiments of the invention, the lignite has a particle size of 1-6mm and a water content of 20-30%.

According to some embodiments of the present invention, in step S1, the wax-rich liquid contains components such as montan wax, bitumen and resin.

According to some embodiments of the invention, in step S2, the filtering is a two-stage filtering, wherein the large-particle lignite is removed in the first stage filtering, and the filtrate is subjected to a secondary filtering to remove fine-particle pulverized coal, so as to meet the requirement of the lignite wax product on ash content.

According to some embodiments of the present invention, in step S3, the first-stage nanofiltration is performed by using nanofiltration membranes to separate substances with different molecular weights, the molecular weight of the organic solvent used is usually less than 150, and the molecular weight of the components such as montan wax, bitumen and resin in the raw montan wax is between 300-500, so that the organic solvent can be recycled through the nanofiltration membranes, thereby achieving concentration of the wax-rich liquid, wherein the concentration ratio can reach 1-3 times.

According to some embodiments of the present invention, in step S4, the solubility of montan wax decreases with decreasing temperature, and the resin does not crystallize out at a lower temperature, and the montan wax is crystallized out by separating the montan wax and the resin according to their solubility in the solvent and decreasing the temperature of the concentrated solution.

According to some embodiments of the invention, the montan wax product obtained by the method is not subjected to high-temperature cooking, and the product quality is good.

According to some embodiments of the invention, the method further comprises:

step S6: performing secondary nanofiltration treatment on the filtrate obtained in the step S4 to obtain a concentrated solution after secondary nanofiltration;

step S7: crystallizing the concentrated solution after the secondary nanofiltration, and carrying out solid-liquid separation to obtain a solid phase and a filtrate;

step S8: the solid phase obtained in step S7 is subjected to a second desolventizing treatment to obtain a resin.

According to some embodiments of the present invention, the filtrate obtained in step S4 mainly contains resin as a component, and the organic solvent can be recycled through the nanofiltration membrane in the secondary nanofiltration device, so as to realize further concentration of the crystallized filtrate.

According to some embodiments of the present invention, the method further includes subjecting the lignite extracted in step S1 to a third desolventizing treatment, and cooling and conditioning the third desolventized lignite for further use.

According to some embodiments of the invention, the temperature of the cooled conditioned lignite is between 20 and 60 ℃.

According to a preferred embodiment of the present invention, the temperature of the cooled and conditioned lignite is 40 to 50 ℃.

According to some embodiments of the invention, the moisture content of the cooled and conditioned lignite is 20% to 30%.

According to some embodiments of the present invention, the organic solvent recovered by the first desolventizing treatment, the organic solvent recovered by the second desolventizing treatment, the organic solvent recovered by the third desolventizing treatment, the organic solvent recovered by the primary nanofiltration and the organic solvent recovered by the secondary nanofiltration are collected and recycled to step S1 for use.

According to some embodiments of the present invention, in step S1, the lignite has a particle size of 1-6mm and a water content of 20-30%.

According to some embodiments of the invention, the temperature of the extraction in step S1 is 60-100 ℃.

According to a preferred embodiment of the present invention, the temperature of the extraction is 75-85 ℃ in step S1.

According to some embodiments of the invention, in step S1, the extraction time is 2-4 h.

According to some embodiments of the invention, in the step S1, the mass ratio of the organic solvent to the lignite is 1-2: 1.

according to some embodiments of the invention, in step S1, the organic solvent is selected from at least one of C6-C20 aromatic hydrocarbons, C1-C20 aliphatic hydrocarbons, C3-C20 cycloalkanes, C1-C20 chlorinated hydrocarbons, C1-C20 alcohols, and C2-C20 carboxylic acid esters.

According to a preferred embodiment of the present invention, in step S1, the organic solvent is at least one selected from the group consisting of C6-C10 aromatic hydrocarbons, C1-C10 aliphatic hydrocarbons, C3-C10 cycloalkanes, C1-C10 chlorinated hydrocarbons, C1-C10 alcohols, and C2-C20 carboxylic acid esters.

According to a preferred embodiment of the invention, the molecular weight of the organic solvent is less than 150.

According to some embodiments of the invention, the C6-C20 aromatic hydrocarbon is selected from at least one of benzene, toluene, and xylene.

According to some embodiments of the invention, the C1-C20 aliphatic hydrocarbon is selected from at least one of petroleum ether, gasoline, and n-hexane.

According to some embodiments of the invention, the C3-C20 cycloalkane is selected from cyclohexane.

According to some embodiments of the invention, the C1-C20 chlorinated hydrocarbon is selected from at least one of dichloroethylene, trichloroethylene, carbon tetrachloride and dichlorohexane.

According to some embodiments of the invention, the C1-C20 alcohol is selected from at least one of methanol, ethanol, propanol, n-butanol and tert-butanol.

According to some embodiments of the invention, the C2-C20 carboxylic acid ester is selected from at least one of ethyl acetate and butyl acetate.

According to some embodiments of the invention, in step S2, the filtering process is a two-stage filtering.

According to a preferred embodiment of the present invention, in step S2, the primary filtration is performed by using a hydrocyclone. And the wax-rich liquid from the first-stage filtration extractor is pressurized to 0.2-0.3MPaG by a pump and sent into a hydrocyclone separator, large-particle coal powder in the wax-rich liquid is separated out, and the wax-rich liquid from the hydrocyclone separator enters a buffer tank for temporary storage.

According to some embodiments of the invention, in step S2, the secondary filtration is performed by using a bag filter or a multi-tube bundle filter. The second-stage filtering equipment adopts a bag filter or a multi-tube cluster filter and other precise filters, the wax-rich liquid after the first-stage filtration is pressurized to 0.2-0.3MPaG by a pump and then sent into the second-stage filter for precise filtration to further remove the coal powder, so that the coal powder content in the wax-rich liquid is less than 400ppm to meet the ash content requirement of the montan wax product.

According to some embodiments of the invention, the primary filtration removes coal dust with a particle size of 0.2-1mm from the wax-rich liquid; and removing coal dust with the particle size of less than 0.2mm in the wax-rich liquid by secondary filtration.

According to some embodiments of the invention, in step S3, the conditions of the primary nanofiltration include: the temperature is 30-80 deg.C and the pressure is 2-4.5 MPaG.

According to a preferred embodiment of the present invention, the temperature of the primary nanofiltration is 40 to 60 ℃ in step S3.

According to some embodiments of the present invention, in step S3, the molecular weight cut-off of the nanofiltration membrane of the first-stage nanofiltration is 300-800.

According to some embodiments of the invention, in step S3, the concentrated wax-rich liquid is concentrated by a factor of 1 to 3.

According to a preferred embodiment of the present invention, in step S3, the concentration ratio of the concentrated wax-rich liquid is 1.2 to 2.

According to some embodiments of the invention, in step S6, the conditions of the secondary nanofiltration include: the temperature is 30-80 deg.C and the pressure is 2-4.5 MPaG.

According to a preferred embodiment of the present invention, the temperature of the secondary nanofiltration is 40 to 60 ℃ in step S6.

According to some embodiments of the present invention, in step S6, the molecular weight cut-off of the nanofiltration membrane of the secondary nanofiltration is 300-800.

According to some embodiments of the present invention, in step S6, the concentration factor of the concentrated solution after the secondary nanofiltration is 1 to 3 times.

According to a preferred embodiment of the present invention, in step S6, the concentration ratio of the concentrated solution after the secondary nanofiltration is 1.2 to 2.

According to some embodiments of the invention, in step S4, the crystallization is a cooling crystallization.

According to a preferred embodiment of the invention, the temperature of the cooling crystallization is between 15 and 25 ℃.

According to a further preferred embodiment of the present invention, the temperature of the cooling crystallization is 18 to 22 ℃.

According to some embodiments of the invention, in step S5, the first desolventizing treatment removes the organic solvent by evaporation.

According to some embodiments of the invention, in step S8, the second desolventizing treatment removes the organic solvent by evaporation.

According to some embodiments of the invention, the third desolventizing treatment removes the organic solvent by evaporation.

According to the embodiment of extracting the lignite wax provided by the invention, the dried lignite granules enter the extractor to be contacted with the extracting agent for extracting the lignite wax, the solid phase from the extractor is sent to the desolventizer to be evaporated and recover the organic solvent for recycling, and the desolventized lignite granules from the desolventizer can be further utilized. Filtering the liquid-phase wax-containing solvent from the extractor to remove coal dust, then entering a primary nanofiltration device for lignite wax concentration, separating out part of the solvent for recycling, cooling and crystallizing the concentrated solution to separate out lignite wax, further desolventizing the crystallized solution through a solid-liquid separation to obtain a lignite wax product, further concentrating the resin-containing liquid phase through secondary nanofiltration, separating out part of the solvent for recycling, and evaporating and desolventizing the concentrated solution to obtain a resin product.

In a second aspect, the present invention provides a montan wax obtained according to the method of the first aspect.

In a third aspect, the present invention provides a use of the montan wax obtained according to the method of the first aspect or the montan wax according to the second aspect in electric machines, precision casting, printing, papermaking, textile and household chemicals.

The lignite wax prepared by the extraction method of lignite wax has high yield and light color, and the lignite wax product can meet the first-level wax index requirement. And the extraction method of the montan wax reduces the energy consumption of steam and cooling water, and the process can save a large amount of steam consumption operating cost every year.

Drawings

Fig. 1 is a schematic view of a montan wax extraction process according to an embodiment of the present invention.

Detailed Description

The present invention will be further described with reference to the following examples.

The technical solutions in the embodiments of the present invention will be described clearly and completely below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. The examples are intended to be illustrative of the invention and not limiting.

The contents of the components of the montan wax resin and the bitumen in MT/T239 and 2006 montan wax technical conditions are shown in Table 1.

TABLE 1

Example 1

Conveying lignite meeting the requirements of particle size (1-6mm) and water content (20-30%) into an extractor, simultaneously adding an organic solvent as an extracting agent to extract lignite wax, wherein the used organic solvent is butyl acetate, the mass ratio of the organic solvent to the lignite is 1.5:1, and extracting at a certain temperature and for a certain time, wherein the extraction temperature is 80 ℃ and the extraction time is 3 hours, so that a wax-rich liquid containing the components of the lignite wax, the bitumen, the resin and the like in the organic solvent is formed.

The coal after extraction and wax extraction enters a third desolventizing processor to be heated and evaporated to remove the organic solvent in the coal, the gas-phase organic solvent is condensed and recycled, and the coal after desolventizing is cooled to 45 ℃ and is subjected to moisture adjustment to obtain water content of 25% for other use.

The wax-rich liquid from the extractor enters a filtering device, the filtering is divided into two stages, the first-stage filtering device adopts an FX750 series hydrocyclone separator of the flying tide company, the wax-rich liquid from the extractor is pressurized to 0.2-0.3MPaG by a pump and sent into the hydrocyclone separator, large-particle lignite is removed in the first-stage filtering device, the wax-rich liquid after the first-stage filtering is pressurized to 0.2-0.3MPaG by the pump and enters a second-stage filtering device for fine filtering to remove fine-particle pulverized coal so as to meet the requirement of the lignite wax product on the ash content, and the second-stage filtering device can use an SF bag filter of Shanghai cijie environmental protection science and technology GJCJ.

The wax-rich liquid after two-stage filtration enters a first-stage nanofiltration device, the first-stage nanofiltration membrane is a Puramem Selective 8040 nanofiltration membrane of the winning company, the nanofiltration membrane can intercept molecular weight of 300-; when the operating pressure is higher than 4.5MPaG, membrane backwashing is automatically carried out, the concentration is 1.5 times, the concentration of the crude montan wax is 4 percent, wherein 50 percent of the crude montan wax is resin, the concentration of the crude montan wax in the first-stage nanofiltration device is concentrated from 4 percent to 10 percent, 62.5 percent of solvent in the first-stage nanofiltration device permeates the nanofiltration membrane to be directly recycled, the concentration of the crude montan wax is concentrated to 10 percent, the crystallization operation is suitable to be carried out, and compared with the conventional evaporation process, the nanofiltration concentration process saves a large amount of steam and cooling water consumption.

The different solubilities of the montan wax and the resin in the solvent are utilized to carry out crystallization separation, and the concentrated solution is cooled to 20 ℃ to separate out the montan wax crystals. And filtering the crystallization liquid, further evaporating the solid phase to remove residual solvent to obtain a montan wax product, and condensing the gas phase of the solvent for recycling.

The filtrate of the crystallized liquid enters a secondary nanofiltration device, the filtrate of the crystallized liquid mainly contains resin, and an organic solvent can pass through a nanofiltration membrane to be recycled in the secondary nanofiltration device, so that the filtrate of the crystallized liquid is further concentrated, the operating temperature of the secondary nanofiltration is 50 ℃, and the initial operating pressure is 3.0 MPaG; when the operation pressure is more than 4.5MPaG, membrane backwashing is automatically carried out, the concentration is 2 times, the concentration of the resin in the primary nanofiltration filtrate is 5.3 percent, the resin is concentrated to 16 percent in the secondary nanofiltration device, the secondary nanofiltration membrane is a Puramem Selective 8040 nanofiltration membrane of a winning and developing company, and 26 percent (accounting for the total solvent amount) of the solvent in the secondary nanofiltration device is directly recycled through the nanofiltration membrane.

Through the two-stage nanofiltration device, 88.5 percent of the total solvent amount is recycled through the nanofiltration device, thereby avoiding the consumption of a large amount of steam and cooling water by evaporation. Evaporating and desolventizing the secondary nanofiltration concentrated solution to obtain a resin product, and condensing desolventized gas phase for recycling. In the process, the solvent recovered by the third desolventizing treatment, the solvent recovered by the first-stage nanofiltration, the solvent recovered by the second-stage nanofiltration, the solvent recovered by the first desolventizing treatment and the solvent recovered by the resin desolventizing treatment are gathered together and are circulated back to the extractor for extracting the montan wax. The montan wax product prepared by the process of the invention is detected to have the quality index reaching or exceeding the national quality standard, which is shown in table 2. The amount of steam and recycle water consumed by the process unit producing 2000 tons of montan wax is shown in table 3.

TABLE 2 montan wax extraction index

Index (I)	Montan wax
		Yield of	6.6％
Colour(s)	Dark brown
		Melting Point	83.2
Acid value	40
		Saponification number	102
Resin composition	16.7％
		Asphalt	4.2％

TABLE 3 steam and Cooling Water consumption

	Steam, t/h	Circulating water, t/h
			Consumption of	7.7	390

Example 2

Only differs from the embodiment 1 in that the operation temperature of the first-stage nanofiltration is 30 ℃, and the membrane backwashing is automatically carried out when the operation pressure is more than 4.5 MPaG; the operating temperature of the secondary nanofiltration is 30 ℃, and the membrane backwashing is automatically carried out when the operating pressure is more than 4.5 MPaG. The montan wax product prepared by the process of the invention is detected to have the quality index reaching or exceeding the national quality standard, and the table 4 shows. When the nanofiltration operation temperature is reduced, the filtrate becomes viscous, the viscosity is increased, the nanofiltration operation is not facilitated, the backwashing frequency of the system is increased, and the nanofiltration operation cost is increased. Although the yield of the montan wax is increased, the content of impurities such as resin and bitumen in the montan wax product is increased, and the quality of the product is deteriorated.

Example 3

Only differs from the embodiment 1 in that the operation temperature of the first-stage nanofiltration is 70 ℃, and the membrane backwashing is automatically carried out when the operation pressure is more than 4.5 MPaG; the operating temperature of the secondary nanofiltration is 70 ℃, and the membrane backwashing is automatically carried out when the operating pressure is more than 4.5 MPaG. The montan wax product prepared by the process of the invention is detected to have the quality index reaching or exceeding the national quality standard, and the table 4 shows. When the nanofiltration operation temperature is increased, the nanofiltration operation is facilitated, but the nanofiltration membrane is made of organic polymers such as polyimide, polyacrylonitrile and the like, and the service life of the nanofiltration membrane is shortened due to the high nanofiltration operation temperature. Under the condition, the yield of the montan wax is increased, and meanwhile, the content of impurities such as resin, bitumen and the like in the montan wax product is reduced, and the product quality is better.

Example 4

Only differs from the embodiment 1 in that the operation temperature of the first-stage nanofiltration is 20 ℃, and the membrane backwashing is automatically carried out when the operation pressure is more than 4.5 MPaG; the operating temperature of the secondary nanofiltration is 20 ℃, and the membrane backwashing is automatically carried out when the operating pressure is more than 4.5 MPaG. The montan wax product prepared by the process of the invention is detected to have the quality index reaching or exceeding the national quality standard, and the table 4 shows.

Example 5

Only differs from the embodiment 1 in that the operation temperature of the first-stage nanofiltration is 40 ℃, and the membrane backwashing is automatically carried out when the operation pressure is more than 4.5 MPaG; the operating temperature of the secondary nanofiltration is 40 ℃, and the membrane backwashing is automatically carried out when the operating pressure is more than 4.5 MPaG. The montan wax product prepared by the process of the invention is detected to have the quality index reaching or exceeding the national quality standard, and the table 4 shows.

Example 6

Only differs from the embodiment 1 in that the operation temperature of the first-stage nanofiltration is 60 ℃, and the membrane backwashing is automatically carried out when the operation pressure is more than 4.5 MPaG; the operating temperature of the secondary nanofiltration is 60 ℃, and the membrane backwashing is automatically carried out when the operating pressure is more than 4.5 MPaG. The montan wax product prepared by the process of the invention is detected to have the quality index reaching or exceeding the national quality standard, and the table 4 shows.

Example 7

Only differs from the embodiment 1 in that the initial pressure of the first nanofiltration operation is 2MPaG, and the membrane backwashing is automatically carried out when the operation pressure is more than 4.5 MPaG; the initial pressure of the secondary nanofiltration operation is 2MPaG, and the membrane backwashing is automatically carried out when the operation pressure is more than 4.5 MPaG. The montan wax product prepared by the process of the invention is detected to have the quality index reaching or exceeding the national quality standard, and the table 4 shows.

Example 8

Only differs from the embodiment 1 in that the initial pressure of the first nanofiltration operation is 4MPaG, and the membrane backwashing is automatically carried out when the operation pressure is more than 4.5 MPaG; the initial pressure of the secondary nanofiltration operation is 4MPaG, and the membrane backwashing is automatically carried out when the operation pressure is more than 4.5 MPaG. The montan wax product prepared by the process of the invention is detected to have the quality index reaching or exceeding the national quality standard, and the table 4 shows.

Example 9

Only differs from the embodiment 1 in that the concentration multiple of the first-stage nanofiltration operation is 0.5 times, and the membrane backwashing is automatically carried out when the operation pressure is more than 4.5 MPaG; the concentration multiple of the secondary nanofiltration operation is 0.5 times, and the membrane backwashing is automatically carried out when the operation pressure is more than 4.5 MPaG. The montan wax product prepared by the process of the invention is detected to have the quality index reaching or exceeding the national quality standard, and the table 4 shows.

Example 10

Only differs from the embodiment 1 in that the concentration multiple of the first-stage nanofiltration operation is 1.5 times, and the membrane backwashing is automatically carried out when the operation pressure is more than 4.5 MPaG; the concentration multiple of the secondary nanofiltration operation is 1.5 times, and the membrane backwashing is automatically carried out when the operation pressure is more than 4.5 MPaG. The montan wax product prepared by the process of the invention is detected to have the quality index reaching or exceeding the national quality standard, and the table 4 shows.

Example 11

Only differs from the embodiment 1 in that the concentration multiple of the first-stage nanofiltration operation is 2 times, and the membrane backwashing is automatically carried out when the operation pressure is more than 4.5 MPaG; the concentration multiple of the secondary nanofiltration operation is 2 times, and the membrane backwashing is automatically carried out when the operation pressure is more than 4.5 MPaG. The montan wax product prepared by the process of the invention is detected to have the quality index reaching or exceeding the national quality standard, and the table 4 shows.

Example 12

Only differs from the embodiment 1 in that the concentration multiple of the first-stage nanofiltration operation is 3 times, and the membrane backwashing is automatically carried out when the operation pressure is more than 4.5 MPaG; the concentration multiple of the secondary nanofiltration operation is 3 times, and the membrane backwashing is automatically carried out when the operation pressure is more than 4.5 MPaG. The montan wax product prepared by the process of the invention is detected to have the quality index reaching or exceeding the national quality standard, and the table 4 shows.

TABLE 4 montan wax extraction index

Comparative example 1:

the method comprises the steps of adopting a conventional process flow, conveying lignite meeting the requirements of particle size (1-6mm) and water content (20-30%) into an extractor, simultaneously adding an organic solvent as an extracting agent to extract lignite wax, wherein the used organic solvent is butyl acetate, the mass ratio of the organic solvent to the lignite is 1.5:1, extracting at a certain temperature and for a certain time, the extraction temperature is 80 ℃, and the extraction time is 3 hours, so as to form a wax-rich liquid containing the components of the lignite wax, the bitumen, the resin and the like in the organic solvent.

The coal after extraction and wax extraction enters a third desolventizing processor to be heated and evaporated to remove the organic solvent in the coal, the gas-phase organic solvent is condensed and recycled, and the coal after desolventizing is cooled to 45 ℃ and is subjected to moisture adjustment to obtain water content of 25% for other use.

The wax-rich liquid from the extractor enters a filtering device, the filtering is divided into two stages, the first-stage filtering device adopts an FX750 series hydrocyclone separator of the flying tide company, the wax-rich liquid from the extractor is pressurized to 0.2-0.3MPaG by a pump and sent into the hydrocyclone separator, large-particle lignite is removed in the first-stage filtering device, the wax-rich liquid after the first-stage filtering is pressurized to 0.2-0.3MPaG by the pump and enters a second-stage filtering device for fine filtering to remove fine-particle pulverized coal so as to meet the requirement of the lignite wax product on the ash content, and the second-stage filtering device adopts a self-cleaning CAC cluster type filtering system of the flying tide company or a CJSF bag type filter of Shanghai cijie environmental protection technology Limited.

The wax-rich liquid after two-stage filtration enters evaporation concentration equipment, the concentration of the evaporated and concentrated crude lignite wax is concentrated from 4% to 10%, solvent steam is condensed and recycled, and the concentrated liquid is cooled and crystallized. The different solubilities of the montan wax and the resin in the solvent are utilized to carry out crystallization separation, and the concentrated solution is cooled to 20 ℃ to separate out the montan wax crystals. And filtering the crystallization liquid, further removing residual solvent from a solid phase to obtain a montan wax product, and condensing a solvent gas phase for recycling.

The filtrate of the crystal liquid enters a secondary evaporation concentration device, the filtrate of the crystal liquid mainly contains resin which is concentrated by 2 times, the concentration of the resin of the filtrate of the crystal liquid is 5.3 percent and is concentrated to 16 percent in the secondary evaporation concentration device, and the solvent steam is condensed and recycled.

With a two-stage evaporative concentration device, a large amount of solvent is heated and condensed. And evaporating and desolventizing the secondary concentrated solution to obtain a resin product, and condensing desolventized gas phase for recycling. In the process, the solvent recovered by the third desolventizing treatment, the solvent recovered by the first-stage evaporation, the solvent recovered by the second-stage evaporation, the solvent recovered by the first desolventizing treatment and the solvent recovered by the resin desolventizing treatment are gathered together and circulated back to the extractor for extracting the montan wax. The quality indexes of the montan wax products prepared by the process are shown in Table 5 after detection. The amount of steam and recycle water consumed by the process unit producing 2000 tons of montan wax is shown in table 6.

TABLE 5 montan wax extraction index

Index (I)	Montan wax
		Yield of	6.0％
Colour(s)	Dark brown color
		Melting Point	81.2
Acid value	52
		Saponification number	125
Resin composition	18.5％
		Asphalt	4.4％

TABLE 6 steam and Cooling Water consumption

	Steam, t/h	Circulating water, t/h
			Consumption of	11.9	560

As can be seen from the comparison of tables 2 and 5, the yield of the montan wax prepared by the montan wax extraction method is 0.6 percent higher, the color of the product is light, and the montan wax product can meet the index requirements of the first-grade wax. In the comparative example, a small amount of decomposition of the montan wax is caused in the multi-stage evaporation process, so that the acid value is high, the melting point is slightly reduced, and the montan wax product can meet the index requirement of the second-stage wax.

As can be seen from a comparison of tables 3 and 6, the energy consumption of steam and cooling water is reduced by 35% by using the extraction method of montan wax according to the present invention, and the energy consumption of steam and cooling water is reduced by about 85% in the process of concentrating the wax-rich liquid to obtain montan wax products and resin products, and the process according to the present invention can save the steam consumption operation cost by 363 ten thousand yuan per year, calculated as 150 yuan/ton of steam.

It should be noted that the above-mentioned embodiments are only for explaining the present invention, and do not constitute any limitation to the present invention. The present invention has been described with reference to exemplary embodiments, but the words which have been used herein are words of description and illustration, rather than words of limitation. The invention can be modified, as prescribed, within the scope of the claims and without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather extends to all other methods and applications having the same functionality.