A method for mixing and briquetting long flame coal powder and tar residue and briquetted coal

Abstract

The application provides a method and briquettes suitable for long-flame coal powder and tar residue mixed briquetting, and belongs to the field of harmful solid waste recycling. The method comprises the following steps: 1, obtaining tar residue by fractional precipitation of coal tar; 2, mixing the tar residue in step 1 with long-flame coal to obtain a mixture; 3, pressing the mixture in step 2 into briquettes; in step 1, the fractional precipitation comprises primary precipitation and secondary precipitation; the lower precipitate in the secondary precipitation is the tar residue. The application uses long-flame coal powder and tar residue after pyrolysis of long-flame coal tar as raw materials, does not need to use additional binders, and can form briquettes by mixing and pressing, thereby realizing harmless treatment and recycling of the tar residue.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of harmful solid waste recycling, and particularly relates to a method for mixing and pressing long-flame coal powder and tar residue into briquettes and briquettes. BACKGROUND

[0002] A coal gas producer is a common heat source for glass, ceramics and metal casting, which uses lump coal as fuel to react with air, water vapor and other gases to produce coal gas containing combustible gases such as carbon monoxide and hydrogen. The coal gas producer has certain requirements for the particle size of the fuel. The coal powder (coal powder, coal particles or crushed coal) with a fine particle size has too small pores when stacked, which cannot meet the full contact with the gas, and problems such as slagging, unqualified gas production and heat production are prone to occur during application. Long-flame coal is a common raw material for coal gas producers due to its low cost, but due to its easy breakage and collision during storage, transportation and use, etc., a large amount of long-flame coal powder is left after screening, which is difficult to utilize in the coal gas producer, resulting in waste of resources and certain pressure on the storage and management of the enterprise in the long run.

[0003] In addition, the coal gas producer produces by-product coal tar during dry distillation, and the tar residue is the residue produced during the storage of coal tar or the dehydration and deslagging process, which has a certain heat value but is difficult to store and utilize. It occupies a large amount of storage space of the production enterprise during storage, which is a waste of resources. The existing treatment method is generally combustion treatment, but the combustion treatment requires complex pretreatment of the tar residue, otherwise the heat value is difficult to fully utilize, and even harmful gases may be produced to cause serious environmental pollution. SUMMARY

[0004] Therefore, the first object of the present application is to provide a method for mixing and pressing long-flame coal powder and tar residue into briquettes, which obtains suitable tar residue by fractional precipitation of coal tar, so that the long-flame coal powder can be cooperated with the tar residue to obtain briquettes with high falling strength and good heat value. The process is simple and has low requirements for equipment, and has the advantage of sustainable application.

[0005] The second object of the present application is to provide briquettes made from long-flame coal powder and tar residue recycling, which has the advantages of high falling strength and good heat value, and is more suitable for coal gas producers. At the same time, the by-products can be recycled in the original equipment, which has the advantages of low requirements for equipment and sustainable application.

[0006] The method for mixing and pressing long-flame coal powder and tar residue into briquettes of the present application is realized by the following scheme:

[0007] The application discloses a method for mixing and pressing briquettes of long-flame coal powder and tar residue, which comprises the following steps: step one, obtaining tar residue through fractional precipitation of coal tar; step two, mixing the tar residue obtained in step one with long-flame coal powder to obtain a mixture; and step three, pressing and forming the mixture obtained in step two; wherein in step one, the fractional precipitation comprises primary precipitation and secondary precipitation; in the primary precipitation, the coal tar is left to stand for 5-48 hours to obtain upper liquid a and lower precipitate b; in the secondary precipitation, the upper liquid a is left to stand for 7-60 days to obtain upper liquid a' and lower precipitate b', and the lower precipitate b' is the tar residue. The coal tar is first subjected to primary precipitation to separate the lower precipitate b with poor adhesion and calorific value from the coal tar, and then the tar residue with good adhesion and high calorific value is obtained through secondary precipitation, so that the briquettes can be pressed without additional use of adhesive when the tar residue is mixed with long-flame coal powder, the adaptability of the tar residue and long-flame coal powder is better, and the adhesion is better, the tar residue and long-flame coal powder can be applied to the production of coal gas in a coal gas producer after being pressed into briquettes of target size, and the calorific value of the long-flame coal powder and by-product tar residue which cannot be directly applied to the coal gas producer is fully utilized, the harmless treatment and recycling of the tar residue are realized. The tar residue is separated through fractional precipitation, the excellent adhesion effect of the tar residue is ensured, the by-product can be recycled in the original equipment after being pressed into briquettes, thus no additional treatment equipment is needed, the process is simple, the requirement for equipment is low, and the application is sustainable.

[0008] Preferably, the coal tar is coal tar produced after pyrolysis of long-flame coal, the standing time of the primary precipitation is 10-15 hours, and the standing time of the secondary precipitation is 40-50 days. The coal tar produced after pyrolysis of long-flame coal is used to make the adaptability of the coal tar and long-flame coal powder better, and the standing time of the coal tar is further optimized to ensure the separation effect of the tar residue and liquid components, so that the tar residue with excellent adhesion and high calorific value can be obtained, and the tar residue is combined with long-flame coal powder tightly, and the calorific value is stable, which is beneficial to ensuring the falling strength of the obtained briquettes and the stable gas production and heat production performance.

[0009] Preferably, in step two, the fineness R90 of the long flame coal powder is 5-20%. Step two can be crushing the long flame coal powder before mixing, and the fineness R90 of the long flame coal powder after crushing is controlled to be 5-20%. In the present application, the fineness R90 of 5-20% means that after crushing, the long flame coal powder is passed through a sieve with a particle size of 90 μm, and the weight percentage of the long flame coal powder passing through the sieve is 80-95%, and 5-20% of the long flame coal powder is left on the sieve. The long flame coal is relatively low in cost, but it is easy to break during storage. After screening, a large amount of long flame coal powder cannot be used in the coal gas generator. By using the method of the present application, the long flame coal powder is utilized, which not only saves resources, but also the briquettes obtained have excellent falling strength and calorific value performance, which is beneficial to subsequent reuse in the coal gas generator. Controlling the fineness of the long flame coal powder before mixing is beneficial to the full contact of the long flame coal powder with the binding components in the tar residue, improving the binding performance of the long flame coal powder and the tar residue, and the long flame coal powder with appropriate fineness can also play a supporting role in the prepared briquettes, thereby improving the mechanical strength of the briquettes and making the briquettes have more excellent crushing resistance, which can maintain appropriate size during transportation and application, and is beneficial to improving the quality of the coal gas in the coal gas generator.

[0010] Further, the fineness R90 of the long flame coal powder is 10-15%. Further controlling the fineness of the long flame coal powder after crushing is appropriate, which not only ensures the full contact of the long flame coal powder with the tar residue, but also is beneficial to the mutual connection and mutual support of the long flame coal powder particles and the tar residue in the briquettes, thereby improving the falling strength performance of the briquettes.

[0011] Preferably, in step two, the weight ratio of the long flame coal powder to the tar residue is (60-80):(20-40); and in step three, the pressure during pressing is 10-20 kN, and the temperature is 25-65℃. By controlling the weight ratio of the tar residue to the long flame coal powder, the present application ensures that the briquettes have appropriate calorific value, and the binding performance of the tar residue is fully utilized. Pressing at appropriate pressure (10-20 kN) and appropriate pressing temperature can further improve the binding strength of the obtained briquettes, which is beneficial to reducing the cost and the requirements for process operation and equipment.

[0012] Further, the weight ratio of the long flame coal powder to the tar residue is (65-75):(25-35). By further optimizing the ratio of the long flame coal powder to the tar residue, the present application further improves the calorific value of the briquettes, and does not affect the binding performance of the long flame coal powder due to the reduction of the content of the tar residue, so that the briquettes can have both high calorific value and falling strength performance, which is beneficial to the stability of gas production and heat production during subsequent application in the coal gas generator.

[0013] The technical scheme of the briquettes of the present application is as follows:

[0014] The briquette prepared by any one of the above methods. The briquette of the present application takes long flame coal powder and tar residue as raw materials, utilizes the binding property of the tar residue, does not need to use additional binders, and can be prepared by mixing and pressing with the long flame coal powder, so that the long flame coal powder and the byproduct tar residue which cannot be directly applied in the coal gas generator are fully utilized, the harmless treatment and resource recycling of the tar residue are realized; the briquette of the present application can be applied in the coal gas generator, realizes the recycling of the byproduct in the original equipment, so that additional treatment equipment is not needed, has the advantages of simple process, low requirement for equipment, and sustainable application.

[0015] Preferably, the falling strength of the briquette is ≥60%, and the calorific value is ≥6500kJ / m 3 In the present application, the falling strength (crushing strength) is the falling strength tested according to the falling strength test method for coal specified in GB / T 15459-2006, and the falling strength ≥60% means that the mass fraction of the lump coal with particle size greater than 25mm in the original lump coal sample is more than 60% after 3 times of falling tests according to the provisions of GB / T 15459-2006. The briquette of the present application has high falling strength and is not easy to break during transportation and use, which is beneficial to ensuring high gas production and heat production effect when applied in the coal gas generator, and the calorific value also meets the requirements of the coal gas generator, and will not affect the quality of the downstream product due to too high or too low calorific value.

[0016] The briquette of the present application has high falling strength and excellent calorific value, which can be directly applied in the coal gas generator, and the quality of the obtained coal gas is good. It can be seen that the present application scientifically and reasonably solves the waste generated during the operation of the coal gas generator, greatly reduces the pollution of the tar residue to the environment, and can directly recycle the waste in the original equipment without increasing additional treatment equipment, which is beneficial to reducing the treatment cost, and also has the advantages of simple process and low requirement for equipment; in addition, the finished briquette provided by the present application has good strength and hardness, can ensure good falling strength performance, and has sufficient calorific value, which is beneficial to ensuring the quality of the downstream product, and can achieve the purpose of reducing cost and increasing efficiency to optimize production. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is the real object diagram of the briquette prepared by Example 1 in the specific embodiment of the present application. DETAILED DESCRIPTION

[0018] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with specific examples. It should be understood that the specific examples described herein are only used to explain the present application and not used to limit the present application.

[0019] For simplicity, only some numerical ranges are explicitly recited herein. However, any lower limit can be combined with any upper limit to form a range not explicitly recited; and any lower limit can be combined with any other lower limit to form a range not explicitly recited, as can any upper limit with any other upper limit to form a range not explicitly recited. Moreover, although not explicitly recited, every point or individual value within a range is to be included as if explicitly written herein. Thus, every point or individual value can serve as its own lower limit or upper limit to combine with any other point or individual value or to combine with other lower or upper limits to form a range not explicitly recited.

[0020] The long flame coal powder produced by the long flame coal raw material used in the gas producer is broken during storage and transportation, which cannot be applied in the gas producer, resulting in waste of resources. In addition, the long flame coal produces by-product gas producer tar when applied in the gas producer. After the light components and tar residues of the gas producer tar are separated, the light components can be extracted for outsourcing treatment, but the tar residues are difficult to be effectively treated and utilized.

[0021] In order to solve the above problems, the present application provides a method for mixing and pressing long flame coal powder and tar residues, comprising the following steps: step one, obtaining tar residues by fractional precipitation of coal tar; step two, mixing the tar residues obtained in step one with long flame coal powder to obtain a mixture; step three, pressing and forming the mixture obtained in step two; wherein in step one, the fractional precipitation comprises primary precipitation and secondary precipitation; in the primary precipitation, the coal tar is allowed to stand for 5-48h to obtain an upper liquid a and a lower precipitate b; in the secondary precipitation, the upper liquid a is allowed to stand for 7-60 days to obtain an upper liquid a' and a lower precipitate b', and the lower precipitate b' is the tar residues.

[0022] In some exemplary embodiments, the time of the primary precipitation is selected from the range consisting of any two values selected from 5h, 10h, 15h, 20h, 25h, 30h, 35h, 40h, 45h, and 48h; and the time of the secondary precipitation is selected from the range consisting of any two values selected from 7 days, 10 days, 15 days, 20 days, 25 days, 30 days, 35 days, 40 days, 45 days, 50 days, 55 days, 58 days, and 60 days.

[0023] The coal tar in the present application refers to the tar produced in the process of preparing coal gas by using a coal gas producer. On one hand, the by-product of the coal gas producer can be directly recycled in the original equipment, which has the advantages of low requirement for the equipment and cost saving. On the other hand, the tar residue obtained by separating the tar has good combination performance with long flame coal powder, which is beneficial to improve the falling strength of the briquette and further promote the utilization effect of the briquette in the coal gas producer.

[0024] Exemplarily, the coal tar in the present application is produced in a two-stage coal gas producer. The temperature of the upper stage of the two-stage coal gas producer is 100-150°C, and the temperature of the lower stage is 400-600°C.

[0025] In some embodiments, the time for the first-stage precipitation is 10-15h, and the time for the second-stage precipitation is 15-45 days.

[0026] Exemplarily, the method for mixing and pressing briquette of long flame coal powder and tar residue in the present application comprises the following steps: batching, stirring, transporting, pressing, drying, screening and standby.

[0027] In some embodiments, the batching refers to taking long flame coal powder and tar residue raw materials according to the weight ratio of (60-80):(20-40). Exemplarily, the weight fraction of the long flame coal powder is selected from the range consisting of any two values selected from 60, 62, 64, 65, 66, 68, 70, 72, 74, 75, 76, 78 and 80, and the weight fraction of the tar residue is selected from the range consisting of any two values selected from 20, 22, 24, 25, 26, 28, 30, 32, 34, 35, 36, 38 and 40.

[0028] In some embodiments, in step two, the fineness R90 of the long flame coal powder is 5-20%.

[0029] Exemplarily, the fineness R90 of the long flame coal powder after crushing is selected from the range consisting of any two values selected from 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% and 20%.

[0030] In some embodiments, the drying is natural air drying, and the time for the natural air drying is 17-20h. The briquette obtained after the pressing and molding in the present application can be dried by air drying or drying equipment. The use of natural air drying can reduce the cost, and controlling the natural air drying time to be 17-20h is beneficial to improve the strength and hardness of the briquette.

[0031] Optionally, the briquette can be in the form of brick, sphere, oblate sphere, ellipsoid or cylinder.

[0032] In some embodiments, the briquettes have a diameter of 50-80 mm. The briquettes of the present application having a diameter of 50-80 mm can be spherical, oblate spherical, ellipsoidal or cylindrical. When the briquettes are ellipsoidal, the diameter refers to the longest axis of the ellipsoid. The suitable diameter is beneficial for the application in the gas producer.

[0033] In some embodiments, the briquettes can be used in a gas producer for the production of gas, and the downstream products can be prepared by indirect heat generation from the gas.

[0034] Optionally, the downstream product is alumina. The heat value of the briquettes obtained by controlling the ratio of the long flame coal powder and the tar residue is suitable, which is beneficial to improve the quality of the alumina product.

[0035] Embodiments

[0036] The technical solutions of the present application will be described below in conjunction with specific embodiments. The raw materials used in the following examples are all from ordinary commercial products, and the devices and equipment used are all purchased from conventional market channels.

[0037] Example 1

[0038] The method for mixing and pressing the long flame coal powder and the tar residue into briquettes in this embodiment comprises the following steps:

[0039] The long flame coal powder that cannot be directly used and is screened out by the gas producer is ground and crushed. The fineness R90 of the crushed long flame coal powder is 15%. The gas producer tar produced by the long flame coal is left to stand and settle in a first-stage settling tank for 12 h. The upper layer component is passed into a second-stage settling tank to stand and settle for 45 days. The lower layer sediment at the bottom of the second-stage settling tank is fished out and used as the tar residue in this embodiment. The crushed long flame coal powder and the tar residue are passed into a stirring device and are proportioned according to a weight ratio of 70:30 of the long flame coal powder to the tar residue. After being stirred uniformly, they are transported to a briquetting machine for pressing and molding. The pressing pressure is 12 kN, and the temperature is 30°C. The molded coal briquettes (i.e. the briquettes in this embodiment) are obtained. Then, the pressed coal briquettes are collected in a air-drying box for natural air-drying for 17 h.

[0040] The briquettes in this embodiment have a physical diagram as shown in Figure 1 The finished coal briquettes are oblate spherical and have a diameter of 60 mm.

[0041] Comparative Example 1

[0042] The method for mixing and pressing the long flame coal powder and the tar residue into briquettes in this comparative example is different from that in Example 1 only in that the gas producer tar produced by the long flame coal is left to stand and settle in a first-stage settling tank for 45.5 days. The upper layer liquid component is pumped out, and the lower layer sediment in the first-stage settling tank is fished out and used as the tar residue in this comparative example for subsequent pressing of the briquettes.

[0043] The briquettes obtained in Comparative Example 1 have defects such as cracking and breakage after drying, and have a low forming rate. The falling strength of the briquettes is only 35%, and the briquettes cannot be applied in a gas producer.

[0044] The method for mixing and pressing the briquettes in Examples 2 to 12 and Comparative Examples 2 to 4 is compared with that in Example 1, and the changed process parameters are shown in Table 1. Table 1 also shows the falling strength and calorific value of the briquettes obtained in each example, wherein the falling strength of the briquettes refers to that a briquette with a diameter of 60 mm is freely dropped from a height of 2 m onto a steel plate with a specified thickness, and then the lump coal with a particle size greater than 25 mm dropped onto the steel plate is dropped again, and the falling is repeated for 3 times. The mass fraction of the lump coal with a particle size greater than 25 mm after 3 times of dropping to the mass of the original briquette coal sample represents the falling strength of the briquettes.

[0045] Table 1

[0046]

[0047] As shown in Table 1, the falling strength of the briquettes obtained in Examples 1 to 12 reaches 60 to 83%, and the calorific value is 6500 to 7400 kJ / m 3 , which meets the application conditions of the gas producer. The briquettes obtained in Comparative Example 1 have a low forming rate, and the falling strength is only 35%, and the briquettes cannot be applied in the gas producer. In Comparative Examples 2 to 4, the coal powder of anthracite or non-caking coal or the coke tar of the gas producer is used as the raw material, and under the condition that other conditions are controlled to be the same, the falling strength of the briquettes obtained in Comparative Examples 2 to 4 is only 52 to 57%, which does not meet the application conditions of the gas producer, and the calorific value is 5900 to 6800 kJ / m 3 , which is greatly decreased compared with the falling strength and calorific value of Example 1.

[0048] Examples 1 to 5 control other conditions to be the same, and only the length of the classified sedimentation is changed. When the standing time of the first-stage sedimentation is 10 to 15 h, and the standing time of the second-stage sedimentation is 40 to 50 days, the falling strength of the briquettes obtained in Examples 1, 4 and 5 is 71 to 83%, and the calorific value reaches 6700 to 7300 kJ / m 3 , which is much higher than that of Examples 2 and 3, indicating that the application further screens the coke tar residue by controlling the standing time of the classified sedimentation, and the coke tar residue obtained has better bonding performance and calorific value, which is beneficial to improving the falling strength and calorific value of the briquettes. Especially in Example 1, the falling strength of the briquettes obtained in Example 1 is as high as 83%, and the calorific value is as high as 7300 kJ / m 3 , which has a very high recycling value.

[0049] Compared with example 1, the weight ratio of long flame coal powder and tar residue is adjusted in examples 6-9. According to the test results of the briquette performance, when the weight ratio of long flame coal powder and tar residue is (60-80):(20-40), the obtained briquette has a falling strength of 62-83% and a calorific value of 6500-7400 kJ / m 3 The comprehensive performance is excellent, and it is beneficial to application in the gas producer. As can be seen from examples 6 and 8, when the mass ratio of long flame coal powder is small, the falling strength of the obtained briquette changes little or decreases slightly, but the calorific performance decreases obviously. As can be seen from examples 7 and 9, when the mass ratio of long flame coal powder is further increased, the calorific performance of the obtained briquette slightly increases or changes little, but the falling strength decreases obviously. It can be seen that a suitable mass ratio is beneficial to achieving high falling strength and high calorific value. In the present application, the weight ratio of long flame coal powder and tar residue is controlled to be (65-75):(25-35), and the obtained briquette can have a falling strength of 69-83% and a calorific value of 6900-7300 kJ / m 3 , which is beneficial to higher utilization value.

[0050] Examples 10-12 only change the fineness of long flame coal powder compared with example 1. The falling strength of the obtained briquette can reach 60-78%. When the fineness R90 of long flame coal powder is finer (example 10, fineness R90 is 5%) or coarser (example 11, fineness R90 is 20%), the falling strength of the obtained briquette is 65-66%, which is lower than that of examples 1 and 12. It can be seen that the long flame coal powder with a fineness R90 of 10-15% used in the present application can further improve the falling strength of the briquette to 78-83%, showing excellent crushing resistance.

[0051] The above is only a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed in the present disclosure, which should be covered in the protection scope of the present disclosure. Therefore, equivalent changes made according to the claims of the present disclosure are still within the scope covered by the present disclosure.

Claims

1. A method for mixing and briquetting long flame coal fines with tar residue, characterized in that, The method comprises the following steps: Step one, fractionally precipitating coal tar to obtain tar residue; Step two, mixing the tar residue obtained in step one with long flame coal powder to obtain a mixture; the weight ratio of the long flame coal powder to the tar residue is (60-75):(25-40); the fineness R90 of the long flame coal powder is 10-15%; Step three, pressing and forming the mixture obtained in step two; In step one, the coal tar is furnace tar generated after pyrolysis of long flame coal; the fractionally precipitating comprises primary precipitation and secondary precipitation; In the primary precipitation, the coal tar is left to stand for 10-15 hours to obtain upper liquid a and lower precipitate b; In the secondary precipitation, the upper liquid a is left to stand for 40-50 days to obtain upper liquid a' and lower precipitate b'; the lower precipitate b' is the tar residue.

2. The method of claim 1, wherein, In step three, the pressure during pressing and forming is 10-20 kN, and the temperature is 25-65°C.

3. The method of claim 1, wherein, The weight ratio of the long flame coal powder to the tar residue is (65-75):(25-35).

4. A briquette prepared by the method of any one of claims 1-3.

5. The briquette according to claim 4, characterized in that, The briquettes have a falling strength of ≥60% and a calorific value of ≥6500 kJ / m 3 .

Images