System for co-producing lignite wax, fulvic acid and humic acid

Abstract

The system comprises an extraction unit, an activation reaction device, an alkali dissolution device and an acidification device which are connected in sequence, a first circulation pipeline is further arranged between the acidification device and the top of the activation reaction device, and the circulation pipeline is arranged to convey a nitric acid solution to the activation reaction device; the extraction unit comprises an extraction liquid separation device, a second recycling pipeline is arranged between the extraction liquid separation device and the activation reaction device, and first extraction liquid obtained by the extraction liquid separation device is conveyed to the activation reaction device through the second recycling pipeline. According to the system for co-producing lignite wax, fulvic acid and humic acid, nitric acid and an extraction solvent in the acidification device are pumped to the activation reaction device, so that cyclic utilization of nitric acid is realized, the process cost is reduced, and the yield of fulvic acid and humic acid is improved.

Description

Technical Field

[0001] The utility model relates to the field of coal chemical industry, in particular to a system for co-producing lignite wax, fulvic acid and humic acid. Background Art

[0002] Baoqing lignite, formed during a relatively short geological period and with a shallow degree of metamorphism, is rich in humic acid, lignite wax, and fulvic acid. The key to improving economic efficiency lies in extracting these three components, achieving their combined production.

[0003] Currently, there are few studies on the co-production of the three, which is a blank area in technical research. The extraction of lignite wax, humic acid and fulvic acid mainly has the following problems:

[0004] ① Lignite wax is viscous and wraps around the surface of lignite, inhibiting the extraction of fulvic acid and humic acid;

[0005] ② A large amount of nitric acid solution is used during the activation and acid precipitation process;

[0006] ③ The extraction rate of lignite wax, fulvic acid and humic acid is relatively low and the process is complicated, which restricts the development of the industry.

[0007] Patent CN112625745B proposes a microwave extraction process for lignite wax, comprising the following steps: (1) lignite wax extraction: lignite is passed through a wet grinder, crushed with water, and then classified. A fine pulp is prepared for standby use, and the coarse pulp is adjusted with tap water to adjust the pulp concentration. Ammonium chloride is then added and stirred to dissolve. The flow rate is adjusted and microwave extraction is performed. The extracted pulp is hot filtered, the filter residue is dried, and the filtrate is subjected to wax and liquid separation. The lignite wax is completely solidified and floats on the liquid to obtain a lignite wax product, and the liquid is recycled; (2) humic acid extraction: the fine pulp is extracted with humic acid, the solid-liquid ratio is adjusted, sodium hydroxide is added to adjust the pH, the flow rate is adjusted, and humic acid is extracted with microwaves. After extraction, the pulp is filtered, the filter residue is reused, the filtrate is acidified, and precipitation is performed. The solution is yellow humic acid, and the precipitate is brown-black humic acid. The filtrate is filtered, and the filtrate is concentrated, dried, and crushed to obtain a yellow humic acid product. The filter residue is dried to obtain brown-black humic acid. This patent proposes first extracting lignite wax by microwave hydrolysis, and then extracting humic acid by alkali dissolution and adjusting the pH in combination with microwave extraction. This method requires adding multiple microwave extractors, which increases equipment investment.

[0008] Patent CN101434868B discloses a method for extracting lignite wax from lignite, which comprises the following steps: (1) crushing: crushing the lump lignite into a powder with a particle size of 2-8 mm; (2) granulating: making lignite particles with a diameter of 2-8 mm from fine dust lignite with a particle size of less than 2 mm; (3) drying: drying the lignite particles containing 40% water to control the water content in the particles to 14-16%; (4) continuous extraction: the dried lignite particles are transported to the material grid of the continuous extractor, and an organic solvent is added at the same time for immersion. The amount of organic solvent added is 200mg / L. The weight ratio of lignite to lignite is (1-1.4):1, the lignite continuous extractor is loaded and operated at a speed of 1-4 hours per week, the organic solvent is sprayed and soaked in a countercurrent cycle, and the material undergoes a dynamic process of infiltration, soaking, washing, and drying in the continuous extractor to achieve continuous extraction of lignite wax from lignite, and the solvent rich in lignite wax is evaporated and separated, and the lignite particles containing organic solvent are transported to the desolventizing and recovery section; (5) Evaporation separation: the organic solvent rich in lignite wax is filtered through a dynamic mixing filter, and then subjected to three-effect evaporation separation, and after 50% of the organic solvent is removed by a single-effect rising film evaporation separator, , pumped to the second-effect falling film evaporation separator to remove 80% of the organic solvent, and then pumped to the third-effect falling film evaporation separator to remove 95% of the organic solvent. After separation, the lignite wax containing 5% of the organic solvent is transported to the vacuum concentration section; (6) Vacuum concentration: the lignite wax from the evaporation separation section is sent to the vacuum concentration tank, and the lignite wax is heated to evaporate and concentrate under vacuum, and concentrated to a lignite wax concentration of more than 95%. The organic solvent residue and part of the entrained water are further distilled from the lignite wax, and enter the condensation system through the cyclone separator, and the residual solvent and water in the lignite wax are removed. The finished lignite wax is transported to the granulation and packaging section; (7) Desolventization and Recovery: After the lignite wax is extracted, the lignite particles are transported to a multi-layer continuous desolventization dryer. The material is in a tumbling state in the dryer. First, indirect steam heating is used to remove most of the organic solvent, and then direct steam blowing is used to remove the solvent to meet the residual solvent standard. Finally, indirect steam heating and drying are used again. The lignite particles from the desolventization dryer are transported to the humic acid extraction workshop to extract humic acid; (8) Solvent Recovery: The organic solvent evaporated from each section is cooled by the condenser and then enters the workshop solvent turnover tank for recycling. This patent proposes a method for extracting lignite wax and humic acid, but the entire process is complicated.

[0009] The prior art does not provide a solution to the above technical problems. Utility Model Content

[0010] The main purpose of the utility model is to provide a system for co-producing lignite wax, fulvic acid and humic acid.

[0011] In order to achieve the above-mentioned objectives, the utility model provides a system for co-producing lignite wax, fulvic acid and humic acid, comprising an extraction unit, an activation reaction device, an alkali dissolution device and an acid precipitation device connected in sequence, a first circulation pipeline is also provided between the acid precipitation device and the top of the activation reaction device, the circulation pipeline is configured to transport nitric acid solution to the activation reaction device, the extraction unit comprises an extract separation device, a second recycling pipeline is provided between the extract separation device and the activation reaction device, and the first extract obtained by the extract separation device is transported to the activation reaction device via the second recycling pipeline.

[0012] Preferably, the activation reaction device adopts a fixed bed reactor, a first outlet is provided at the bottom of the fixed bed reactor, the solution containing fulvic acid obtained by the spray reaction flows out from the first outlet, a second outlet is provided at the fixed bed layer position of the fixed bed reactor, and the second outlet is connected to the alkali dissolution device.

[0013] Preferably, a first spray assembly and a second spray assembly are respectively provided at the top and the bottom of the activation reaction device, and the solution flowing out of the bottom outlet of the activation reaction device is sprayed again by the second spray assembly.

[0014] Preferably, the method further comprises a mixing device, wherein the first extract and the nitric acid solution in the circulation pipeline are mixed by the mixing device and then fed into the activation reaction device.

[0015] Preferably, the mixing device is connected to the first spray assembly.

[0016] Preferably, a gas buffer tank is further included, and an outlet is provided at the top of the activation reaction device, and the top outlet is connected to the gas buffer tank.

[0017] Preferably, the gas buffer tank is connected to the top of the mixing device.

[0018] Preferably, a first circulation pump is provided on the circulation pipeline.

[0019] Preferably, a pH value detection device is provided in the mixing device.

[0020] Preferably, a valve is provided on the pipeline between the gas buffer tank and the mixing device.

[0021] The system for co-producing lignite wax, fulvic acid and humic acid proposed in the utility model achieves the following technical effects:

[0022] 1. This application pumps the solution in the acid precipitation device to the activation reaction unit to improve the utilization rate of nitric acid and reduce process costs.

[0023] 2. Two sets of spraying components are provided in the activation reaction device to realize the circulating spraying of nitric acid solution and improve the conversion rate of fulvic acid and humic acid in the dry process.

[0024] 3. The extractant components obtained by extraction and separation are pumped into the activation reaction device to improve the conversion rate of fulvic acid and humic acid and improve the utilization rate of the extractant.

[0025] 4. By collecting NOx in the activation reaction device and passing part of the NOx into the mixing device, the acidity and pressure of the circulating nitric acid are adjusted to further improve the conversion rate of fulvic acid and humic acid. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings constituting part of the present invention are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0027] Figure 1 A schematic diagram of the system structure for co-producing lignite wax, fulvic acid, and humic acid is shown;

[0028] The above drawings include the following reference numerals:

[0029] 120. Extraction device; 140. Extraction liquid separation device; 200. Activation reaction device; 300. Alkaline dissolution device; 400. Acid precipitation device; 240. First spray assembly; 220. Second spray assembly; 500. Gas buffer tank; 700. Mixing device; 570. Valve. DETAILED DESCRIPTION

[0030] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0031] The present invention is described in further detail below with reference to specific embodiments. These embodiments are not to be construed as limiting the scope of protection claimed by the present invention. The term "including" when used indicates the presence of a feature, but does not exclude the presence or addition of one or more other features; the terms "lateral", "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for ease of description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be construed as limiting the present invention; in addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be construed as indicating or implying relative importance.

[0032] In this description, it should be noted that, unless otherwise specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they can refer to fixed connections, removable connections, or integral connections; they can refer to direct connections, indirect connections through an intermediary, or internal connections between two components. Those skilled in the art will understand the specific meanings of these terms in this utility model based on the specific circumstances. Furthermore, in the description of this utility model, unless otherwise specified, "plurality" means two or more.

[0033] The present application proposes a system for the co-production of lignite wax, fulvic acid and humic acid, which is used to improve the utilization value of lignite and enhance the economic benefits of the industry. Specifically, it comprises an extraction unit, an activation reaction device 200, an alkali dissolution device 300 and an acid precipitation device 400 connected in sequence. Among them, the extraction unit is used to extract lignite wax from lignite, and transport the first solid phase substance remaining after extraction to the activation reaction device 200. The activation reaction unit is configured to activate the first solid phase substance to generate fulvic acid and a second solid phase substance. The alkali dissolution device 300 and the acid precipitation device 400 are configured to dissolve and precipitate the second solid phase substance, that is, first reacting humic acid with an alkaline solution to generate humate, and then precipitating it under acidic conditions.

[0034] The activation reaction device 200 activates the first solid phase material with a nitric acid solution having a nitric acid concentration of 20-30%. In addition to generating fulvic acid, the activation reaction device 200 also generates humic acid, which exists in a solid form in the second solid phase material.

[0035] The alkaline solution in the alkaline dissolution device 300 is potassium hydroxide or sodium hydroxide solution with a molar concentration of 2 to 4 mol·L -1 The amount of alkaline solution added is 2% to 8% of the second solid phase material. The acid solution in the acid precipitation device 400 uses 10 to 30% nitric acid, and the internal reaction temperature is 60 to 80°C.

[0036] Cogeneration systems require large quantities of nitric acid solution, resulting in high process costs and environmental pollution. To address this issue, the present application proposes installing a first circulation line between the acid precipitation unit 400 and the top of the activation reaction unit 200. The first circulation line is configured to transport nitric acid solution to the activation reaction unit 200, thereby achieving nitric acid recycling. Furthermore, to reduce nitric acid consumption in the activation reaction unit, a dry process is employed in the activation reaction unit, controlling the mass ratio of nitric acid solution to the first solid phase material to between 1:2 and 1:4. Furthermore, a first spray assembly 240 is provided on the top side of the activation reaction unit 200 to ensure more uniform contact between the nitric acid solution and the first solid phase material. To improve the utilization rate of the spray liquid, the present application proposes installing a second spray assembly 220 at the bottom of the activation reaction unit. The liquid phase obtained at the bottom outlet of the activation reaction unit is recirculated to the activation reaction unit 200 by the second spray assembly 220, spraying the lignite from the bottom of the fixed bed to promote the lignite reaction and recycle the nitric acid reaction liquid. After a period of reaction, the obtained liquid phase reaction material is discharged from the outlet, and subsequently concentrated and dried to obtain humic acid.

[0037] To facilitate product separation, the activation reaction device uses a fixed-bed reactor. The fulvic acid obtained by the spray reaction flows out from the bottom outlet of the activation reaction device 200, and the second solid phase material remaining in the fixed bed is sent to the alkaline dissolution device 300. The pore size of the bed of the fixed bed reactor in this application is 2-3 mm.

[0038] In this application, a combination of 1,4-dioxane and methanol is used as an extractant, with the mass ratio of 1,4-dioxane to methanol being 1:3 to 1:8, and the extraction temperature being 30 to 60°C. Using methanol as the main extractant component reduces the amount of 1,4-dioxane used. Methanol is a low-toxic liquid and can also reduce the cost of the extraction process. 1,4-dioxane is miscible with methanol and the water content in lignite, which is different from the currently commonly used benzene, ether, and n-alkane extractants. Therefore, using 1,4-dioxane as an extractant reduces the limit on the water content in lignite. The water content can be controlled to 10 to 20% through simple drying. This eliminates the need for complex processes for the water content in lignite, reducing process costs. Experimental results show that using 1,4-dioxane and methanol as a mixed extractant can ensure the extraction rate of lignite wax.

[0039] The present applicants have also discovered that the separated 1,4-dioxane and water can be used as additives for extracting fulvic acid and humic acid. By adding a mixed solution of 1,4-dioxane and water to the nitric acid reaction solution, the extraction rate of fulvic acid and humic acid can be significantly increased. 1,4-dioxane, as an active agent, can dissolve residual wax or resinous substances adhering to the first solid phase residue, facilitating the entry of nitric acid into the particles of the first solid phase residue, increasing the conversion rate of fulvic acid and humic acid, and shortening the oxidation time.

[0040] To this end, the present application provides an extractant recycling unit, comprising an extraction device 120 and an extract separation device 140. The extract separation device 140 is configured to obtain a first extract and pump the first extract to the activation reaction device 200. The present application does not specifically limit the type and structure of the extract separation device, nor the separation method; such methods may include negative pressure distillation, membrane evaporation, etc. The primary components of the first extract are 1,4-dioxane and methanol.

[0041] In addition, the present application also proposes adding a mixing device 700 to the system. The first extract and the nitric acid solution in the circulation pipeline are mixed by the mixing device 700 and then sent to the activation reaction device 200. Since the two are mixed in advance, the reaction with the first solid substance is promoted.

[0042] During the recycling process, the concentration of nitric acid in the acid precipitation device will decrease, resulting in a conversion rate in the activation reaction device. For this reason, the present application proposes to increase a gas buffer tank 500, and the activation reaction device 200 is provided with a top outlet, and the top outlet is connected to the gas buffer tank 500; the gas buffer tank 500 is connected to the top of the mixing device 700. By collecting the NOx produced in the activation reaction device 200 and passing the NOx into the mixing device, on the one hand, the acidity of the nitric acid solution can be increased, and on the other hand, a power source can be provided for spraying. In addition, a valve is provided at the outlet of the gas buffer tank 500, and a pH value detection device (not shown in the figure) is provided in the mixing device 700 for detecting the pH value of nitric acid in the mixing device 700. When the pH value is lower than 2, the valve is opened to pass NOx into the mixing device 700.

[0043] In addition, the system is also provided with auxiliary equipment, such as a first circulation pump 420 and various valves.

[0044] Example 1

[0045] The lignite is dried and pulverized to a moisture content of 10-20% and a particle size of approximately 5 mm. 100 g of lignite and 300 g of an extractant (60 g of 1,4-dioxane and 240 g of methanol) are placed in an extraction unit 120. Extraction is performed at 60°C for 4 hours with a stirring rate of 200 rpm. After extraction, the mixture is allowed to stand and filtered to obtain a lignite wax solution and a first solid phase. The first solid phase is then transferred to the fixed bed of an activation reaction unit.

[0046] The lignite wax liquid is first fed into a cooling device set at 10°C, where the lignite wax solidifies. The lignite wax and extraction solvent are then separated through a filtration device and weighed. The extraction solvent is then fed into a distillation device for staged distillation. The process conditions are: a first-stage distillation temperature of 60°C and a pressure of 0.08 MPa; a second-stage distillation temperature of 90°C and a pressure of 0.08 MPa. In the first stage of distillation, methanol is distilled off, while in the second stage, 1,4-dioxane and water are simultaneously distilled off. The first extract is then condensed to obtain the first extract.

[0047] The first solid-phase material is fed into the activation reaction unit 200. The first circulation pump pumps the nitric acid solution from the acid precipitation unit 400 to the mixing unit 700, where it is mixed with the first extract and then fed back into the activation reaction unit 200 to react with the first solid-phase material on the fixed bed. The ratio of the first solid-phase material to the nitric acid solution is 2:1, and the weight ratio of the nitric acid solution to 1,4-dioxane is 4:3. The reaction temperature of the activation reaction unit 200 is controlled at 60°C, and the reaction time is 5 hours. After the reaction is completed, the liquid flows out of the bottom outlet of the activation reaction unit and is concentrated and dried to obtain fulvic acid, which is then weighed after drying.

[0048] The second solid phase material on the fixed bed is fed into the alkali dissolving device 300, in which 2 mol·L -1 The sodium hydroxide solution is added, the ratio of the added amount of the alkaline solution to the second solid phase material is 2:1, the reaction temperature is set to 60°C, the reaction is carried out for 1 hour, and the mixture is allowed to stand and then centrifuged or filtered to obtain a supernatant.

[0049] The supernatant was fed to an acid precipitation device, in which nitric acid solution was added at a concentration of 20%. The solution was allowed to stand for 1 hour to allow the humic acid precipitate to precipitate. The precipitate was dried at 50°C to obtain humic acid solids, which were then weighed after drying.

[0050] The yields of the three substances obtained after the initial cycle reaction all reach more than 85%.

[0051] After a period of operation, the yields of fulvic acid and humic acid decreased, and the pH detection device in the mixing device 700 showed an increase in pH. Opening valve 570 and introducing NOx into the mixing device, the yields of fulvic acid and humic acid showed an increasing trend.

[0052] Example 2

[0053] The lignite is dried and pulverized to a moisture content of 10-20% and a particle size of approximately 5 mm. 100 g of lignite and 300 g of an extractant (60 g of 1,4-dioxane and 240 g of methanol) are placed in an extraction unit 120. Extraction is performed at 60°C for 4 hours with a stirring rate of 200 rpm. After extraction, the mixture is allowed to stand and filtered to obtain a lignite wax solution and a first solid phase. The first solid phase is then transferred to the fixed bed of an activation reaction unit.

[0054] The first solid-phase material is fed into the activation reaction unit 200. A first circulation pump pumps the nitric acid solution from the acid precipitation unit 400 into the activation reaction unit 200, where it reacts with the first solid-phase material on the fixed bed. The ratio of the first solid-phase material to the nitric acid solution is 2:1. The reaction temperature in the activation reaction unit 200 is controlled at 60°C, and the reaction time is 5 hours. After the reaction is completed, the liquid flows out of the bottom outlet of the activation reaction unit and is concentrated and dried to obtain fulvic acid, which is then weighed after drying.

[0055] The second solid phase material on the fixed bed is fed into the alkali dissolving device 300, in which 2 mol·L -1 The sodium hydroxide solution is added, the ratio of the added amount of the alkaline solution to the second solid phase material is 2:1, the reaction temperature is set to 60°C, the reaction is carried out for 1 hour, and the mixture is allowed to stand and then centrifuged or filtered to obtain a supernatant.

[0056] The supernatant was fed to an acid precipitation device, in which nitric acid solution was added at a concentration of 20%. The solution was allowed to stand for 1 hour to allow the humic acid precipitate to precipitate. The precipitate was dried at 50°C to obtain humic acid solids, which were then weighed after drying.

[0057] The yield calculated by weighing showed that the yield of Example 2 was less than 70%. It can be seen that adding 1,4-dioxane during the activation reaction can increase the yield of fulvic acid and humic acid.

[0058] In summary, the system for co-producing lignite wax, fulvic acid and humic acid proposed in the present invention achieves the following technical effects:

[0059] 1. This application pumps the solution in the acid precipitation device to the activation reaction unit to improve the utilization rate of nitric acid and reduce process costs.

[0060] 2. Two sets of spraying components are provided in the activation reaction device to realize the circulating spraying of nitric acid solution and improve the conversion rate of fulvic acid and humic acid in the dry process.

[0061] 3. The extractant components obtained by extraction and separation are pumped into the activation reaction device to improve the conversion rate of fulvic acid and humic acid and improve the utilization rate of the extractant.

[0062] 4. By collecting NOx in the activation reaction device and passing part of the NOx into the mixing device, the acidity and pressure of the circulating nitric acid are adjusted to further improve the conversion rate of fulvic acid and humic acid.

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A system for co-producing lignite wax, fulvic acid and humic acid, characterized in that: The invention comprises an extraction unit, an activation reaction device (200), an alkali dissolution device (300) and an acid precipitation device (400) which are connected in sequence. A first circulation pipeline is further provided between the acid precipitation device (400) and the top of the activation reaction device (200). The circulation pipeline is configured to transport nitric acid solution to the activation reaction device (200). The extraction unit comprises an extract separation device (140). A second recycling pipeline is provided between the extract separation device (140) and the activation reaction device (200). The first extract obtained by the extract separation device (140) is transported to the activation reaction device (200) via the second recycling pipeline.

2. The system for co-producing lignite wax, fulvic acid and humic acid according to claim 1, characterized in that: The activation reaction device (200) adopts a fixed bed reactor, and a first outlet is provided at the bottom of the fixed bed reactor. The solution containing fulvic acid obtained by the spray reaction flows out from the first outlet. A second outlet is provided at the fixed bed layer position of the fixed bed reactor, and the second outlet is connected to the alkali dissolution device (300).

3. The system for co-producing lignite wax, fulvic acid and humic acid according to claim 2, characterized in that: A first spray assembly (240) and a second spray assembly (220) are respectively provided at the top and bottom of the activation reaction device (200), and the solution flowing out of the bottom outlet of the activation reaction device (200) is sprayed again by the second spray assembly (220).

4. The system for co-producing lignite wax, fulvic acid and humic acid according to claim 3, characterized in that: The invention also comprises a mixing device (700), wherein the first extract and the nitric acid solution in the circulation pipeline are mixed by the mixing device (700) and then fed into the activation reaction device (200).

5. The system for co-producing lignite wax, fulvic acid and humic acid according to claim 4, characterized in that: The mixing device (700) is connected to the first spraying assembly (240).

6. The system for co-producing lignite wax, fulvic acid and humic acid according to claim 5, characterized in that: It also includes a gas buffer tank (500), and the top of the activation reaction device (200) is provided with an outlet, and the outlet on the top is connected to the gas buffer tank (500).

7. The system for co-producing lignite wax, fulvic acid and humic acid according to claim 6, characterized in that: The gas buffer tank (500) is connected to the top of the mixing device (700).

8. The system for co-producing montan wax, fulvic acid and humic acid according to any one of claims 1 to 7, characterized in that: A first circulation pump (420) is provided on the circulation pipeline.

9. The system for co-producing montan wax, fulvic acid and humic acid according to any one of claims 4 to 7, characterized in that: The mixing device (700) is provided with a pH value detection device.

10. The system for co-producing lignite wax, fulvic acid and humic acid according to claim 7, characterized in that: A valve (570) is provided on the pipeline between the gas buffer tank (500) and the mixing device (700).

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