Railway ballast wet screening-final coal jigging combined separation process

Abstract

This invention provides a combined wet screening and jigging process for railway ballast, relating to the field of solid waste sorting, processing, and recycling. The combined wet screening and jigging process for railway ballast includes: S1) performing a first-stage wet screening on the ballast to obtain a first-screen oversize and a first-screen undersize; S2) performing a second-stage wet screening on the first-screen undersize to obtain a second-screen oversize and a second-screen undersize; S3) using jigging at the final coal level to separate the second-screen oversize to obtain aggregate and clean coal; S4) dewatering the aggregate to obtain dewatered aggregate and coal slurry, and dewatering the clean coal to obtain dewatered clean coal and coal slurry. This process solves the problem of resource utilization difficulties caused by the mixture of rock particles and coal particles in the solid waste ballast generated by railway ballast in existing technologies, achieving efficient separation of rock particles and coal components, and realizing the resource utilization of railway ballast solid waste.

Description

Technical Field

[0001] This invention relates to the field of solid waste sorting, processing and recycling technology, specifically to a combined sorting process of railway ballast wet screening and final coal jigging. Background Technology

[0002] National coal transport railways are primarily constructed with ballasted tracks made of hard rocks such as granite and basalt. Over the years, these hard rocks often break down into substandard gravel. With the accumulation of this substandard gravel and coal dust spilled from coal trains, the railway ballast gradually hardens and loses its elasticity, increasing the risk of accidents. Therefore, railway maintenance departments regularly conduct cleaning and screening operations on the railway lines. During these operations, millions of tons of solid waste—ballast—are generated annually. This ballast is mostly a mixture of fine-grained rock particles, coal particles, and clay. The rock particles often have a thick layer of clay adhering to their surfaces, which would be hazardous if used as building materials. The rock particle size is typically between 0-30 mm, and the coal particle size is typically between 0-15 mm. Currently, ballast is generally disposed of through landfill. Domestic research on the comprehensive utilization of this ballast is still in its infancy. With increasingly stringent environmental protection requirements for railways and considerations for railway operational safety, it is necessary to utilize railway ballast for resource recovery. Therefore, it is essential to propose a scientific and effective method for separating coal and rock particles from the ballast to achieve resource reuse. Thus, a method to solve at least one of the aforementioned problems is urgently needed. Summary of the Invention

[0003] The purpose of this invention is to provide a combined wet screening and jigging process for railway ballast soil cleaning, which solves the problem of resource utilization difficulties caused by the mixing of rock particles and coal particles in the solid waste ballast soil generated by railway cleaning in the prior art.

[0004] To achieve the above objectives, the present invention provides a combined separation process for railway ballast wet screening and final coal jigging, wherein the combined separation process includes:

[0005] S1) Perform Class I wet screening on the ballast soil to obtain the first oversize and the first undersize, wherein the particle size of the first oversize is greater than or equal to the Class I wet screening particle size, and the particle size of the first undersize is less than the Class I wet screening particle size.

[0006] S2) Perform a second-stage wet sieving on the first undersize to obtain a second oversize and a second undersize, wherein the particle size of the second oversize is greater than or equal to the particle size of the second-stage wet sieving, and the particle size of the second undersize is less than the particle size of the second-stage wet sieving.

[0007] S3) The material on the second screen is separated by jigging at the end of the coal grade to obtain stone and clean coal;

[0008] S4) Perform dewatering treatment on the stone to obtain dewatered stone and coal slurry water, and perform dewatering treatment on the clean coal to obtain dewatered clean coal and coal slurry water.

[0009] Specifically, the air pressure and air volume of the air used in the final coal jigging separation are preset air pressure and preset air volume; the water volume used in the final coal jigging separation is preset water volume.

[0010] Specifically, the preset air pressure is between 0.029 and 1.8 MPa, and the preset air volume is between 2 and 5 m³ / s. 3 The preset water volume is between 40-160 m³ / min. 3 Between / min.

[0011] Specifically, in step S4), the stone is dewatered to obtain dewatered stone and coal slurry, including:

[0012] The material is dewatered by bucket elevator to obtain dewatered material and coal slurry.

[0013] Specifically, the combined separation process of railway ballast wet screening and final coal jigging further includes: performing a third-stage screening on the dewatered stone to obtain oversize and undersize material, wherein the particle size of the oversize material is greater than or equal to the third-stage screening particle size, and the particle size of the undersize material is less than the third-stage screening particle size.

[0014] Specifically, the particle size of the third-stage sieve is 4.75 mm.

[0015] Specifically, in step S4), the clean coal is dewatered to obtain dewatered clean coal and coal slurry, including:

[0016] The clean coal is pre-dehydrated and screened using an arc screen to obtain pre-dehydrated clean coal and coal slurry.

[0017] The pre-dehydrated clean coal is dehydrated and screened using a dewatering screen to obtain secondary dehydrated clean coal and coal slurry.

[0018] Centrifugal dewatering machine is used to dewater secondary dewatered clean coal to obtain dewatered clean coal and coal slurry.

[0019] Specifically, the combined sorting process of railway ballast wet screening and final coal jigging further includes: performing concentration and pressure filtration treatment on the coal slurry water and the second undersize material to obtain coal slurry.

[0020] Specifically, the process of concentrating and filtration the coal slurry water and the second undersize material to obtain coal slurry includes:

[0021] The coal slurry and the second undersize are concentrated using a thickener to obtain a concentrated coal slurry mixture.

[0022] The concentrated coal-water mixture is filtered by a filter press to remove water from the mixture, thereby obtaining coal slime.

[0023] Specifically, the particle size of the first-stage wet screening is 15 mm, and the particle size of the second-stage wet screening is 0.5 mm.

[0024] The railway ballast wet screening-jigging combined separation process provided by this invention separates coal particles and rock particles in ballast through a large-volume, long-line, multi-stage screening-jigging combined separation process, ultimately obtaining dewatered clean coal and dewatered aggregate. This facilitates the reuse of coal and rock particles and improves resource utilization. In the process of separating coal and rock particles from ballast, a first-stage wet screening is used to obtain a first-screen oversize with a particle size greater than or equal to the first-stage wet screening particle size and a first-screen undersize with a particle size smaller than the first-stage wet screening particle size. Then, the first-screen undersize undergoes a second-stage wet screening to obtain a second-screen oversize with a particle size greater than or equal to the second-stage wet screening particle size and a second-screen undersize with a particle size smaller than the second-stage wet screening particle size. Finally, the second-screen oversize is further processed by final-stage jigging to obtain aggregate and clean coal. The particle sizes of the first-stage wet screening and the second-stage wet screening can be set according to the particle sizes of the rock and coal particles. When using the first-stage wet screening and the second-stage wet screening to screen the ballast and the first undersize material, the water used in the wet screening process can wash away the clay adhering to the surface of the coal and rock particles in the ballast, and at the same time, it can also play a role in dust reduction. After obtaining the stone and clean coal through multi-stage screening, the stone and clean coal are dewatered to obtain dewatered stone and dewatered clean coal for subsequent use. This solves the problem of resource utilization caused by the mixture of rock and coal particles in the solid waste ballast generated by railway cleaning in the existing technology. It realizes the resource reuse of railway cleaning solid waste, improves resource utilization rate, saves energy, and improves the stability and efficiency of sorting by classifying and screening rock and coal particles.

[0025] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0026] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0027] Figure 1 This is a flowchart of the combined sorting process of wet screening of ballast soil and jigging of final coal grade provided in an embodiment of the present invention. Detailed Implementation

[0028] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0029] Figure 1 This is a flowchart of the combined process of wet screening of ballast soil and jigging of final coal grades in railway engineering. Figure 1 As shown, this invention provides a combined process for wet screening of railway ballast and jigging of final coal grades. The combined process includes:

[0030] S1) Perform Class I wet screening on the ballast soil to obtain the first oversize and the first undersize, wherein the particle size of the first oversize is greater than or equal to the Class I wet screening particle size, and the particle size of the first undersize is less than the Class I wet screening particle size.

[0031] S2) Perform a second-stage wet sieving on the first undersize to obtain a second oversize and a second undersize, wherein the particle size of the second oversize is greater than or equal to the particle size of the second-stage wet sieving, and the particle size of the second undersize is less than the particle size of the second-stage wet sieving.

[0032] S3) The material on the second screen is separated by jigging at the end of the coal grade to obtain stone and clean coal;

[0033] S4) Perform dewatering treatment on the stone to obtain dewatered stone and coal slurry water, and perform dewatering treatment on the clean coal to obtain dewatered clean coal and coal slurry water.

[0034] The railway ballast wet screening-final coal jigging combined separation process provided by this invention separates coal particles and rock particles in ballast. It employs multi-stage wet screening and final coal jigging to separate the ballast. First, a first-stage wet screening is performed on the ballast. The water used in this first-stage wet screening continuously washes away the clay adhering to the surfaces of the rock and coal particles, thereby improving the quality of the final screened rock and coal particles. After the first-stage wet screening, a first-stage oversize with a particle size greater than or equal to the first-stage wet screening particle size and a first-stage undersize with a particle size smaller than the first-stage wet screening particle size are obtained. Then, a second-stage wet screening is performed on the first-stage undersize. The water used in the second-stage wet screening further washes the first-stage undersize. The coal and rock particles in the undersize are separated into two oversize and two undersize particles after the first undersize is screened. Then, the second oversize is further separated by final coal jigging to obtain slag and clean coal. After dewatering, the slag and clean coal can be used to obtain dewatered slag and dewatered clean coal for subsequent use. The coal slurry water is recycled through a coal slurry water treatment system. This solves the problem of resource reuse caused by the mixing of rock and coal particles in the ballast soil generated by railway cleaning in the existing technology. It realizes the low-cost resource reuse of railway solid waste ballast soil, improves resource utilization rate, saves energy, and improves the stability and efficiency of the separation by classifying and screening rock and coal particles.

[0035] In one embodiment, a screening machine is used to perform Class I wet screening of ballast. The screening machine has a first screen on which the ballast is placed for screening. During the screening process, circulating water is introduced into the screening machine to wash the ballast, thereby washing away the clay adhering to the rock particles and coal particles. The amount of water introduced into the screening machine is between 0.29 and 3.49 m³. 3 Between [a certain speed] / min, as the ballast placed on the first screen moves with the screen, rock particles and coal particles of different sizes are separated. The sieve aperture of the first screen is set according to the particle size of the screened rock and coal particles. Based on actual conditions, the particle size of the rock particles in the ballast is between 0-30mm, and the particle size of the coal particles is between 0-15mm. Therefore, the sieve aperture of the first screen corresponds to the particle size setting of the first-stage wet screening process. The particle size of the first-stage wet screening process is between 15mm and 30mm. Preferably, the first-stage wet screening process... The particle size of the first sieve is 15mm. Therefore, the sieve aperture of the first sieve is set to 15mm. When screening the ballast, the particle size of the first sieve material is greater than or equal to 15mm. Based on the known particle size of rock particles, the first sieve material is rock particles. After dewatering, the first sieve material becomes coarse aggregate that can be used as building material stone. The coarse aggregate is then used in construction. The first sieve material with surface clay removed is safer and more reliable for use in construction.

[0036] The first-stage wet screening particle size is 15mm. Therefore, the particle size of the first undersize material is less than 15mm. This first undersize material contains coal particles and rock particles smaller than 15mm. A second screening machine is used to perform a second-stage wet screening on the first undersize material. The screen in this second screening machine is set as a second screen, and the aperture of the second screen is set according to the particle size of the second-stage wet screening, which is between 0.5mm and 15mm. Preferably, the particle size of the second-stage wet screening is 0.5mm, and the aperture of the second screen is set to 0.5mm. In this way, the second oversize material and the second undersize material are separated by the second screen. While performing the second-stage wet screening on the first undersize material, water is fed into the screening machine to wash the coal particles and rock particles in the first undersize material again. The rock particles are further washed to remove clay from the surfaces of both coal and rock particles. The particle size of the second undersize is less than 0.5 mm, while the particle size of the second oversize is between 0.5 mm and 15 mm. The smaller particle size of the second undersize makes it easier to process; therefore, it can be directly fed into a thickener for concentration. The second oversize consists of a mixture of rock and coal particles with a particle size between 0.5 mm and 15 mm. To further separate the rock and coal particles in the second oversize, a fine coal jigging machine is used for jigging separation. Since the rock and coal particles in the second oversize have different densities, the air pressure used in the fine coal jigging separation is between 0.029 and 1.8 MPa, and the air volume is between 2 and 5 m³ / s. 3 During the final coal jigging process, the water consumption ranges from 40-160 t / h. The water is uniformly agitated by air-driven jigging, efficiently separating rock and coal particles from the second screen oversize. The separated rock particles are the raw material, and the separated coal particles are the clean coal. Figure 1 As shown in the flowchart, in the screening process, "+" represents the material on the screen and "-" represents the material under the screen.

[0037] After separating clean coal and aggregate by jigging the fine coal, the clean coal and aggregate are dewatered to obtain dewatered aggregate and dewatered clean coal that are easier to use.

[0038] In another embodiment, a screening machine is provided, with screens arranged in layers. The screens in each layer have different aperture sizes; for example, the upper screen has an aperture size of 15mm, and the lower screen has an aperture size of 0.5mm. The upper screen filters out the first oversize and the first undersize, with the oversize particles having a diameter greater than or equal to 15mm. The undersize falls onto the lower screen for further screening, where the lower screen separates the second oversize and the second undersize. The second oversize remains on the lower screen, with a particle size between 0.5mm and 15mm. The undersize, with a particle size less than 0.5mm, passes through the lower screen. The second oversize is then separated into fine coal and aggregate using a jigging machine.

[0039] The particle size of the aggregate separated by the final coal jigging separation is between 0.5mm and 15mm. Specifically, in step S4), to facilitate the application of the aggregate, the aggregate undergoes dewatering treatment to obtain dewatered aggregate and coal slurry, including:

[0040] The material is dewatered by bucket elevator to obtain dewatered material and coal slurry.

[0041] The combined process of wet screening of ballast soil and jigging of final coal grade in railway ballast further includes: performing a third-stage screening on the dewatered stone to obtain oversize and undersize particles. The particle size of the oversize particles is greater than or equal to the third-stage screening particle size, and the particle size of the undersize particles is smaller than the third-stage screening particle size. The third-stage screening particle size is between 4.75 mm and 15 mm, preferably 4.75 mm.

[0042] After the coal jigging machine separates the aggregate, it is lifted by a bucket elevator. During the lifting process, the aggregate is dewatered. The dewatered aggregate undergoes a third-stage screening, specifically a screening machine. A third screen is installed in the screening machine, with its mesh size set to 4.75mm according to the particle size of the third-stage screening. This results in aggregate with a particle size between 4.75mm and 15mm for the oversize and between 0.5mm and 4.75mm for the undersize. The larger oversize aggregate is mixed with the 15mm-30mm oversize aggregate and used as coarse aggregate in construction. The smaller undersize aggregate is used as fine aggregate. This further screening of the aggregate meets the quality requirements of the construction industry for both coarse and fine aggregate products. The screening machines mentioned in this application include, but are not limited to, linear vibrating screens, tension screens, and circular vibrating screens.

[0043] After the fine coal is separated by the jigging machine, in order to dewater the fine coal, step S4) involves performing a dewatering treatment on the fine coal to obtain dewatered clean coal and coal slurry, including:

[0044] The clean coal is pre-dehydrated and screened using an arc screen to obtain pre-dehydrated clean coal and coal slurry.

[0045] The pre-dehydrated clean coal is dehydrated and screened using a dewatering screen to obtain secondary dehydrated clean coal and coal slurry.

[0046] Centrifugal dewatering machine is used to dewater secondary dewatered clean coal to obtain dewatered clean coal and coal slurry.

[0047] Arc screens, dewatering screens, and centrifugal dewatering machines are used to dewater clean coal. Graded dewatering not only improves the efficiency of obtaining dewatered clean coal, but is also more economical and practical. Horizontal or vertical centrifugal dewatering machines can be selected.

[0048] In addition to dewatering clean coal, a large amount of coal slurry is also produced after dewatering. In order to avoid waste and improve resource utilization, the railway cleaning ballast wet screening-final coal jigging combined separation process further includes: performing concentration and pressure filtration treatment on the coal slurry and the second undersize material to obtain coal slurry.

[0049] The process of concentrating and filtration the coal slurry water and the second undersize material to obtain coal slurry includes:

[0050] The coal slurry and the second undersize are concentrated using a thickener to obtain a concentrated coal slurry mixture.

[0051] The concentrated coal-water mixture is filtered by a filter press to remove water from the mixture, thereby obtaining coal slime.

[0052] Coal slurry and the smaller-sized second-screen undersize material are concentrated and filtered together to produce coal slurry for subsequent boiler combustion. Because the mixture of coal slurry and the second-screen undersize material has a very high water content, direct dehydration is inefficient. Therefore, before filtration, the coal slurry and the second-screen undersize material are concentrated. Concentration can be performed using high-efficiency thickeners, inclined plate thickeners, or rake thickeners. After concentration, a concentrated coal-water mixture is produced, with a significantly reduced water content. A filter press is then used to filter out the excess water, yielding coal slurry. This not only makes efficient use of the second-screen undersize material but also allows for deep utilization of the dehydrated coal slurry, greatly improving resource utilization. The water pressed out by the filter press is recycled back into a storage container, which provides water for subsequent stages of wet screening (Level I, Level II, and final coal jigging).

[0053] The railway ballast wet screening-final coal jigging combined separation process provided by this invention separates coal particles and rock particles in ballast through graded screening, ultimately obtaining dewatered clean coal and dewatered aggregate, thus facilitating the reuse of coal and rock particles and improving resource utilization. In the process of separating coal and rock particles in ballast, a first-stage wet screening is used to obtain a first-screen oversize with a particle size greater than or equal to the first-stage wet screening particle size and a first-screen undersize with a particle size smaller than the first-stage wet screening particle size. Then, the first-screen undersize undergoes a second-stage wet screening to obtain a second-screen oversize with a particle size greater than or equal to the second-stage wet screening particle size and a second-screen undersize with a particle size smaller than the second-stage wet screening particle size. Finally, the second-screen oversize is separated by final coal jigging to obtain aggregate and clean coal. The first-stage wet screening particle size... The particle size of the Class I and Class II wet screening can be set according to the particle size of the rock and coal particles. When using Class I and Class II wet screening to screen ballast and the first undersize material, the water used in the wet screening process can wash away the clay adhering to the surface of the coal and rock particles in the ballast, and at the same time play a role in dust reduction. After obtaining the stone and clean coal through multi-stage screening, the stone and clean coal are dewatered to obtain dewatered stone and dewatered clean coal for subsequent use. This solves the problem of resource utilization caused by the mixture of rock and coal particles in the solid waste ballast generated by railway cleaning in the existing technology. It realizes the resource reuse of railway cleaning solid waste, improves resource utilization rate, saves energy, and improves the stability and efficiency of sorting by classifying and screening rock and coal particles.

[0054] The optional embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above embodiments. Within the scope of the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical solutions of the embodiments of the present invention, and these simple modifications all fall within the protection scope of the embodiments of the present invention.

[0055] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not describe the various possible combinations separately.

[0056] Furthermore, various different implementations of the present invention can be combined arbitrarily, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed in the present invention.

Claims

1. A combined process for wet screening of ballast soil and jigging of final coal grade in railway engineering, characterized in that, The railway ballast wet screening-final coal jigging combined separation process includes: S1) Perform Class I wet screening on the ballast soil to obtain the first oversize and the first undersize, wherein the particle size of the first oversize is greater than or equal to the Class I wet screening particle size, and the particle size of the first undersize is less than the Class I wet screening particle size. S2) Perform a second-stage wet sieving on the first undersize to obtain a second oversize and a second undersize, wherein the particle size of the second oversize is greater than or equal to the particle size of the second-stage wet sieving, and the particle size of the second undersize is less than the particle size of the second-stage wet sieving. S3) The material on the second screen is separated by jigging at the end of the coal grade to obtain stone and clean coal; S4) Perform dewatering treatment on the stone to obtain dewatered stone and coal slurry water, and perform dewatering treatment on the clean coal to obtain dewatered clean coal and coal slurry water.

2. The combined separation process of railway ballast wet screening and final coal jigging according to claim 1, characterized in that, The air pressure and air volume used in the final coal jigging separation are preset air pressure and preset air volume; The water volume used in the final coal jigging process is a preset amount.

3. The combined sorting process of railway ballast wet screening and final coal jigging according to claim 2, characterized in that, The preset air pressure is between 0.029 and 1.8 MPa, and the preset air volume is between 2 and 5 m³ / s. 3 The preset water volume is between 40-160 m³ / min. 3 Between / min.

4. The combined sorting process of railway ballast wet screening and final coal jigging according to claim 1, characterized in that, In step S4), the stone is dewatered to obtain dewatered stone and coal slurry, including: The material is dewatered by bucket elevator to obtain dewatered material and coal slurry.

5. The combined separation process of railway ballast wet screening and final coal jigging according to claim 1, characterized in that, The combined sorting process of wet screening of ballast soil and jigging of final coal grade further includes: performing a third-stage screening on the dewatered stone to obtain oversize and undersize material, wherein the particle size of the oversize material is greater than or equal to the third-stage screening particle size, and the particle size of the undersize material is less than the third-stage screening particle size.

6. The combined separation process of railway ballast wet screening and final coal jigging according to claim 5, characterized in that, The particle size of the third-stage sieve is 4.75 mm.

7. The combined separation process of railway ballast wet screening and final coal jigging according to claim 1, characterized in that, In step S4), the clean coal is dewatered to obtain dewatered clean coal and coal slurry, including: The clean coal is pre-dehydrated and screened using an arc screen to obtain pre-dehydrated clean coal and coal slurry. The pre-dehydrated clean coal is dehydrated and screened using a dewatering screen to obtain secondary dehydrated clean coal and coal slurry. Centrifugal dewatering machine is used to dewater secondary dewatered clean coal to obtain dewatered clean coal and coal slurry.

8. The combined separation process of railway ballast wet screening and final coal jigging according to claim 1, characterized in that, The combined sorting process of railway ballast wet screening and final coal jigging also includes: performing concentration and pressure filtration treatment on the coal slurry water and the second undersize material to obtain coal slurry.

9. The combined separation process of railway ballast wet screening and final coal jigging according to claim 8, characterized in that, The process of concentrating and filtration the coal slurry water and the second undersize material to obtain coal slurry includes: The coal slurry and the second undersize are concentrated using a thickener to obtain a concentrated coal slurry mixture. The concentrated coal-water mixture is filtered by a filter press to remove water from the mixture, thereby obtaining coal slime.

10. The combined separation process of railway ballast wet screening and final coal jigging according to claim 1, characterized in that, The particle size of the first-stage wet sieve is 15 mm, and the particle size of the second-stage wet sieve is 0.5 mm.

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