Coal gangue multi-layer synchronous sorting method and sorting system

Abstract

The present application belongs to the technical field of coal and gangue sorting, and particularly relates to a coal-gangue multi-layer synchronous sorting method and a sorting system. The coal-gangue sorting method actually comprises the following steps: S1. grading of raw coal; S2. X-ray intensity penetration test; S3. division of a sortable particle size range; and S4. actual sorting and completion of coal and gangue discrimination. The present application can realize multi-layer synchronous sorting operation of coal and gangue by using a single source, greatly improves the sorting efficiency, reduces the equipment cost, directly uses the current of X-ray ionized air as the sorting basis, and effectively guarantees the sorting precision.

Description

Technical Field

[0001] This invention belongs to the field of coal and gangue sorting technology, specifically relating to a multi-layer synchronous sorting method and system for coal and gangue. Background Technology

[0002] In coal production, raw coal refers to coal directly mined from coalfields without any processing. Raw coal contains impurities such as coal, gangue, anchor bolts, and iron blocks, with gangue forming during the coal formation process. Gangue is characterized by high density, low calorific value, and contains a large amount of heavy metals. Its presence in coal reduces combustion efficiency, and its combustion products exacerbate environmental pollution. Therefore, it is necessary to pre-sort out gangue from raw coal. Based on this, the characteristics of specific objects are identified by the different attenuation levels of X-rays as they penetrate objects with different physical properties, resulting in different grayscale values. This has led to the development of intelligent X-ray coal and gangue sorting machines. The specific working process and structure of the current X-ray coal gangue separator are described in existing technologies such as Chinese Patent Publication No. "CN112588609" entitled "Coal Gangue Separation Method, Device and Electronic Equipment" and Chinese Patent Publication No. "CN117288783B" entitled "X-ray Based Coal Gangue Separation Method, Computer Equipment and Storage Medium", and are widely used in the current coal and gangue separation process. However, with the widespread use of X-ray coal and gangue sorting machines, some problems remain unresolved: First, the sorting method relies on the attenuation of X-ray images, which is easily affected by the thickness of the coal and gangue. Since the attenuation of coal and gangue of different thicknesses may be the same, it is impossible to accurately distinguish between coal and gangue in such cases. Second, the X-ray detectors required for the sorting process must undergo pulse current, A / D conversion, and digital signal processing before being converted into an image. This multiple conversion of data information obviously further reduces the sorting accuracy and affects the high precision of the sorting work. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a multi-layer synchronous sorting method for coal gangue. This invention can realize multi-layer synchronous sorting of coal gangue using a single radiation source, which not only greatly improves the sorting efficiency and reduces equipment costs, but also directly uses the current of X-ray ionization of air as the sorting basis, so the sorting accuracy can be effectively guaranteed.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A multi-layer synchronous sorting method for coal gangue, characterized by comprising the following steps:

[0006] S1. Grading of raw coal feed:

[0007] The raw coal was graded to obtain four particle size grades of coal and gangue: [50mm, 25mm], (25mm, 13mm], (13mm, 6mm], and (6mm, 3mm].

[0008] S2. X-ray intensity penetration test:

[0009] The maximum and minimum coal size of each particle size class, as well as the minimum gangue size of the maximum gangue size of each particle size class, were obtained. X-ray penetration tests were performed on each of them, and the corresponding average X-ray absorption was recorded.

[0010] S3. Define the range of sortable particle sizes:

[0011] The average X-ray absorption range when passing through gangue with a particle size of [50mm, 25mm] is recorded as [b1, b2]; similarly, the range for gangue with a particle size of (25mm, 13mm) is [b3, b4], for gangue with a particle size of [13mm, 6mm] is [b5, b6], and for gangue with a particle size of (6mm, 3mm) is [b7, b8]. The number of sorting layers is determined by the following formula:

[0012] When 1-b2>b4 and 1-b2-b4<b6, [50mm,25mm] and (25mm,13mm] use the same source for double-layer sorting;

[0013] When 1-b2-b4>b6 and 1-b2-b4-b6<b8, then [50mm,25mm], (25mm,13mm], and (13mm,6mm] use the same source for three-layer sorting.

[0014] When 1-b2-b4-b6>b8, all particle sizes use the same source for four-layer sorting.

[0015] Along the X-ray emission path of a single source, the particle size of the raw coal to be separated on each X-ray unit used for corresponding layer separation gradually decreases. At this time, the attenuation value of the X-ray after penetration of the previous X-ray unit is used as the initial emission value of the X-ray of the next X-ray unit.

[0016] S4. Perform actual sorting and distinguish between coal and gangue:

[0017] The raw coal to be sorted that meets the particle size requirements is placed into the corresponding X-ray unit. The actual X-ray absorption of the raw coal to be sorted at each X-ray unit is obtained, and the actual X-ray absorption is compared with the average X-ray absorption of the corresponding particle size in step S2 to distinguish between coal and gangue in each X-ray unit.

[0018] Preferably, in step S2, the formula for calculating the average X-ray absorption b is:

[0019]

[0020] In the formula:

[0021] n is the quantity of coal or gangue;

[0022] U1 is the average voltage pulse generated by X-rays passing through the ionization chamber after passing through the belt during the time period when coal or gangue moves through the X-ray area on the conveyor belt;

[0023] U0 is the average value of the voltage pulse generated by the X-ray passing through the ionization chamber before it passes through the belt.

[0024] Preferably, in step S4, the formula for calculating the actual X-ray absorption C of the raw coal to be sorted is:

[0025]

[0026] In the formula:

[0027] t0 is the starting time of the current fluctuation function when the raw coal to be sorted enters the X-ray region, and t1 is the ending time of the fluctuation.

[0028] f(w) is the current fluctuation function recorded by the current sensor in the ionization chamber after the X-rays pass through the raw coal to be sorted, and g(w) is the current fluctuation function before the X-rays pass through the raw coal to be sorted.

[0029] Preferably, when distinguishing coal and gangue in each layer of X-ray unit, the actual X-ray absorption of the raw coal to be sorted in the current layer of X-ray unit is compared with the average X-ray absorption range of coal and gangue of the corresponding particle size class in the current layer of X-ray unit to determine whether it falls into the range.

[0030] Preferably, if the actual X-ray absorption of the raw coal to be sorted in the current layer of X-ray unit does not fall within the average X-ray absorption range of the coal and gangue of the corresponding particle size class in the current layer of X-ray unit, the materials cannot be distinguished; at this time, the X-ray intensity of the radiation source is reduced, and step S4 is repeated until the discrimination result is obtained.

[0031] Preferably, the sorting system employs a multi-layer synchronous sorting method for coal gangue, characterized in that: it includes a set of radiation sources, with two or more layers of radiation units arranged sequentially along the radiation emission path of the radiation sources, each layer of radiation unit including a collimator, a voltage sensor and a belt arranged sequentially along the radiation emission path of the radiation sources; the belt is equipped with baffles for confining the raw coal to be sorted within the radiation area.

[0032] Preferably, a sorting kit consists of a set of radiation sources and ray units arranged sequentially along the emission path of the radiation sources. There are two or more sorting kits arranged sequentially along the belt width direction.

[0033] The beneficial effects of this invention are as follows:

[0034] Unlike traditional X-ray detector-based coal and gangue sorting methods, this invention utilizes X-rays to penetrate coal or gangue, achieving sorting through the current generated by the ionization of air by the X-rays. This sorting method eliminates the need for A / D conversion or multiple conversion strategies, effectively determining the X-ray absorption amount solely based on parameters such as the current fluctuation function. It is also unaffected by the thickness of the coal and gangue, thus achieving effective differentiation between the two materials. Furthermore, by designing a multi-layer coal and gangue sorting structure without requiring multiple signal conversions, the accuracy of the current fluctuation function ensures sorting precision while simultaneously improving sorting efficiency, maximizing energy utilization.

[0035] Thus, this invention enables multi-layer synchronous sorting of coal gangue using a single radiation source, which not only greatly improves sorting efficiency and reduces equipment costs, but also directly uses the current of X-ray ionization of air as the sorting basis, effectively ensuring sorting accuracy. Attached Figure Description

[0036] Figure 1 A schematic diagram of one embodiment of a sorting system;

[0037] Figure 2 This is a flowchart illustrating the workflow of the present invention.

[0038] Figure 3 This is a current fluctuation diagram in Example 1 when no raw coal to be sorted passes through;

[0039] Figure 4 This is a current fluctuation diagram of the raw coal to be sorted passing through in Example 1.

[0040] The actual correspondence between the reference numerals and component names in this invention is as follows:

[0041] 10-Source;

[0042] 20 - X-ray unit; 21 - collimator; 22 - voltage sensor; 23 - belt; 23a - baffle. Detailed Implementation

[0043] For ease of understanding, this section combines... Figure 1-4 The specific structure and operation of the present invention are further described below:

[0044] like Figure 1-2As shown, the coal gangue separation method of the present invention actually includes the following steps:

[0045] S1. Grading of raw coal feed;

[0046] S2. X-ray intensity penetration test;

[0047] S3. Define the range of sortable particle sizes;

[0048] S4. Perform actual sorting and complete the identification of coal and gangue.

[0049] Furthermore, the specific workflow of this invention includes:

[0050] 1) Before actual sorting, the raw coal is graded to obtain coal and gangue of four particle size grades: [50mm, 25mm], (25mm, 13mm], (13mm, 6mm], and (6mm, 3mm].

[0051] 2) The raw coal after the above classification is separated into gangue and coal of the largest and smallest particle sizes. X-ray transmission is performed on conveyor belt 23, and the voltage generated by the X-rays passing through the ionization chamber before and after passing through the ionization chamber is recorded. Then, the following calculations are performed:

[0052]

[0053] In the formula:

[0054] b represents the average X-ray absorption;

[0055] n is the quantity of coal or gangue;

[0056] U1 is the average value of the voltage pulse generated by X-rays passing through the ionization chamber after passing through the belt 23 during the time period when coal or gangue moves through the X-ray area on the belt 23;

[0057] U0 is the average value of the voltage pulse generated by the X-ray passing through the ionization chamber before passing through belt 23.

[0058] 3) Define the range of sortable particle sizes:

[0059] The total average X-ray absorption range when passing through the [50mm, 25mm] particle size class is recorded as [b1, b2]. Correspondingly, (25mm, 13mm) is [b3, b4], [13mm, 6mm] is [b5, b6], and (6mm, 3mm] is [b7, b8]. Of course, considering that the maximum value of the average X-ray absorption of gangue is necessarily greater than that of coal of the same particle size class, the average X-ray absorption range when passing through gangue of the corresponding particle size class can also be directly used to list the corresponding range values.

[0060] At this point, when 1-b2 > b4 and 1-b2-b4 < b6, [50mm, 25mm] and (25mm, 13mm] use the same source 10 for double-layer sorting; when 1-b2-b4 > b6 and 1-b2-b4-b6 < b8, then [50mm, 25mm], (25mm, 13mm], and (13mm, 6mm] use the same source 10 for triple-layer sorting; and so on.

[0061] 4) During the actual sorting process, calculate the current obtained by the ionization chamber when X-rays pass through the first layer of ray unit 20: At this time, the formula for calculating the actual X-ray absorption C of the raw coal to be sorted is:

[0062]

[0063] In the formula:

[0064] t0 is the starting time of the current fluctuation function when the raw coal to be sorted enters the X-ray region, and t1 is the ending time of the fluctuation.

[0065] f(w) is the current fluctuation function recorded by the current sensor in the ionization chamber after the X-rays pass through the raw coal to be sorted, and g(w) is the current fluctuation function before the X-rays pass through the raw coal to be sorted.

[0066] Subsequently, the current obtained in the ionization chamber of the next layer of X-ray unit 20 is calculated, and this process is repeated to complete the identification of coal gangue. Then, the attenuation value of the X-rays after penetration of the previous layer of X-ray unit 20 is used as the initial emission value of the X-rays of the next layer of X-ray unit 20, and the actual X-ray absorption of the raw coal to be sorted in the next layer of X-ray unit 20 is calculated in the same way.

[0067] Finally, after calculating the actual X-ray absorption of each piece of coal or gangue, compare it with the range of actual X-ray absorption established in step 3). Specifically, further differentiate the defined range. When the range established in step 3) represents the total actual X-ray absorption of coal and gangue (i.e., coal and gangue are recorded simultaneously), separate them. Specifically, within the range [b1,b2], coal [50mm, 25mm] and gangue [50mm, 25mm] are separated. Of course, if the actual X-ray absorption of coal and gangue is already recorded separately, the corresponding range data can be directly used here. Subsequently, compare the actual X-ray absorption of each piece of coal or gangue obtained at each layer of X-ray unit 20 with the average X-ray absorption of the corresponding particle size. Separate the coal, gangue, and even indistinguishable materials at each layer of X-ray unit 20. Finally, place the indistinguishable materials into the next round of equipment with lower X-ray intensity for further separation.

[0068] In actual design of sorting systems, such as Figure 1As shown, a structure can be formed in which multiple layers of ray units 20 are arranged sequentially from top to bottom. At the same time, along the ray emission path of a single ray source 10, two or more layers of ray units 20 are arranged sequentially. Each layer of ray unit 20 includes a collimator 21, a voltage sensor 22 and a belt 23 arranged sequentially along the ray emission path of the ray source 10. The belt 23 is equipped with baffles 23a for confining the raw coal to be sorted within the ray area.

[0069] Example 1

[0070] To facilitate understanding of the present invention, the following is combined with Figure 1 and Figure 3-4 The actual workflow of this invention is described as follows:

[0071] 1) Before actual sorting, the raw coal is graded to obtain coal and gangue in particle size ranges of [50mm, 25mm], (25mm, 13mm], (13mm, 6mm], and (6mm, 3mm].

[0072] 2) Taking raw coal of [50mm, 25mm] as an example, 100 pieces of coal and 100 pieces of gangue of 50mm and 25mm respectively are placed on conveyor belt 23. The radiation source 10 emits X-rays with an energy of 160kV. After passing through the collimator 21 of the first layer of radiation unit 20, the X-rays become parallel beams. They pass through the air and are ionized. At this time, the voltage sensor 22 records the ionization voltage. Then, the X-rays pass through the coal or gangue and are attenuated. The attenuated X-rays pass through the collimator 21 of the second layer of radiation unit 20 and are recorded by the voltage sensor 22 at the second layer of radiation unit 20. The average X-ray absorption of coal and gangue of the corresponding particle size is calculated, and the statistical results are shown in Table 1.

[0073] Table 1

[0074]

[0075] 3) The total average X-ray absorption range when passing through the [50mm, 25mm] particle size range is recorded as [0.32, 0.58]. Similarly, it is [0.16, 0.28] for (25mm, 13mm), [0.08, 0.12] for (13mm, 6mm), and [0.01, 0.05] for (6mm, 3mm). Because 1 - 0.58 > 0.28, and 1 - 0.58 - 0.28 > 0.12, and 1 - 0.58 - 0.28 - 0.12 < 0.05, three-layer sorting of [50mm, 25mm], (25mm, 13mm], and (13mm, 6mm] can be performed in one step. The sorting system selected is... Figure 1 The three-layer structure is shown.

[0076] Of course, this section records the average X-ray absorption of gangue passing through a particle size range of [50 mm, 25 mm].

[0077] The measurement range is [0.51, 0.58], (25mm, 13mm) is [0.22, 0.28], (13mm, 6mm) is [0.11, 0.12], and (6mm, 3mm) is [0.04, 0.05], and the above number of layers can be obtained in the same way.

[0078] 4) During the actual sorting of the first layer, any piece of coal or gangue passing through the radiation area will cause a change in the voltage of the voltage sensor 22, resulting in fluctuating current. At this time, in the actual test of the first layer radiation unit 20, a piece of raw coal with a particle size range of [50mm, 25mm] passes through the radiation area of ​​the 160kV energy source 10. The current fluctuations that occur before and after passing through are as follows: Figure 3 and Figure 4 As shown. At this time, t0 is 0.28s and t1 is 0.58s. Therefore, the C of the raw coal to be sorted at the first ray unit 20 is calculated to be 0.45. Similarly, a piece of raw coal with a particle size range of (25mm, 13mm) passes through the second ray unit 20, and the C of the raw coal to be sorted at this location is calculated to be 0.24. A piece of raw coal with a particle size range of (13mm, 6mm) passes through the third layer, and the C of the raw coal to be sorted at this location is calculated to be 0.09.

[0079] Referring to Table 1 above, it can be seen that the actual X-ray absorption values ​​of the raw coal to be sorted in the particle size range [50mm, 25mm] at the first X-ray unit 20 fall within the range of [0.32, 0.46] in Table 1, indicating it is coal. The actual X-ray absorption values ​​of the raw coal to be sorted in the particle size range (25mm, 13mm) at the second X-ray unit 20 fall within the range of [0.22, 0.28] in Table 1, indicating it is gangue. The actual X-ray absorption values ​​of the raw coal to be sorted in the particle size range (13mm, 6mm) at the third X-ray unit 20 fall within the range of [0.08, 0.1] in Table 1, indicating it is coal. The test results are consistent with the actual situation, and the detection accuracy can be significantly guaranteed.

[0080] Of course, those skilled in the art will recognize that the present invention is not limited to the details of the exemplary embodiments described above, but also includes the same or similar methods that can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description.

[0081] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0082] All technical parts not described in detail in this invention are publicly known technologies.

Claims

1. A multi-layer synchronous sorting method for coal gangue, characterized in that... Includes the following steps: S1. Grading of raw coal feed: The raw coal was graded to obtain four particle size grades of coal and gangue: [50mm, 25mm], (25mm, 13mm], (13mm, 6mm], and (6mm, 3mm]. S2. X-ray intensity penetration test: The maximum and minimum coal size of each particle size class, as well as the minimum gangue size of the maximum gangue size of each particle size class, were obtained. X-ray penetration tests were performed on each of them, and the corresponding average X-ray absorption was recorded. S3. Define the range of sortable particle sizes: The average X-ray absorption range when passing through gangue with a particle size of [50mm, 25mm] is recorded as [b1, b2]; similarly, the range for gangue with a particle size of (25mm, 13mm) is [b3, b4], for gangue with a particle size of [13mm, 6mm] is [b5, b6], and for gangue with a particle size of (6mm, 3mm) is [b7, b8]. The number of sorting layers is determined by the following formula: When 1-b2>b4 and 1-b2-b4<b6, [50mm,25mm] and (25mm,13mm] use the same source (10) for double-layer sorting; When 1-b2-b4>b6 and 1-b2-b4-b6<b8, then [50mm,25mm], (25mm,13mm], and (13mm,6mm] use the same source (10) for three-layer sorting; When 1-b2-b4-b6>b8, all particle sizes use the same source (10) for four-layer sorting; Along the radiation emission path of a single radiation source (10), the particle size of the raw coal to be separated on each radiation unit (20) used for corresponding layer separation gradually decreases. At this time, the attenuation value of the X-rays after penetration of the previous radiation unit (20) is used as the initial emission value of the X-rays of the next radiation unit (20). S4. Perform actual sorting and distinguish between coal and gangue: The raw coal to be sorted that meets the particle size requirements is placed into the corresponding X-ray unit (20), and the actual X-ray absorption of the raw coal to be sorted at each X-ray unit (20) is obtained. The actual X-ray absorption is then compared with the average X-ray absorption of the corresponding particle size in step S2 to distinguish between coal and gangue in each X-ray unit (20).

2. The method for multi-layer synchronous separation of coal gangue according to claim 1, characterized in that: In step S2, the formula for calculating the average X-ray absorption b is: In the formula: n is the quantity of coal or gangue; U1 is the average value of the voltage pulse generated by X-rays passing through the ionization chamber after passing through the belt (23) during the time period when coal or gangue moves through the X-ray area on the belt (23); U0 is the average value of the voltage pulse generated by the X-ray passing through the ionization chamber before passing through the belt (23).

3. A multi-layer synchronous coal gangue sorting method according to claim 1 or 2, characterized in that: In step S4, the formula for calculating the actual X-ray absorption C of the raw coal to be sorted is: In the formula: t0 is the starting time of the current fluctuation function when the raw coal to be sorted enters the X-ray region, and t1 is the ending time of the fluctuation. f(w) is the current fluctuation function recorded by the current sensor in the ionization chamber after the X-rays pass through the raw coal to be sorted, and g(w) is the current fluctuation function before the X-rays pass through the raw coal to be sorted.

4. The method for multi-layer synchronous separation of coal gangue according to claim 3, characterized in that: When distinguishing coal and gangue in each layer of X-ray unit (20), the actual X-ray absorption of the raw coal to be sorted in the current layer of X-ray unit (20) is compared with the average X-ray absorption range of coal and gangue of the corresponding particle size in the current layer of X-ray unit (20) to determine whether it falls into the range.

5. The method for multi-layer synchronous separation of coal gangue according to claim 4, characterized in that: If the actual X-ray absorption of the raw coal to be sorted in the current layer X-ray unit (20) does not fall within the range of the average X-ray absorption of coal and gangue of the corresponding particle size class in the current layer X-ray unit (20), the materials cannot be distinguished. At this time, the X-ray intensity of the radiation source (10) is reduced, and step S4 is repeated until the discrimination result is obtained.

6. A sorting system, wherein the sorting system applies the multi-layer synchronous sorting method for coal gangue as described in claim 1, characterized in that: It includes a set of radiation sources (10), and two or more layers of radiation units (20) are arranged sequentially along the radiation emission path of the radiation sources (10). Each layer of radiation unit (20) includes a collimator (21), a voltage sensor (22) and a belt (23) arranged sequentially along the radiation emission path of the radiation sources (10). The belt (23) is equipped with baffles (23a) for confining the raw coal to be sorted in the radiation area.

7. The sorting system according to claim 6, characterized in that: A sorting kit consists of a set of radiation sources (10) and radiation units (20) arranged sequentially along the emission path of the radiation sources (10). There are two or more sorting kits arranged sequentially along the bandwidth of the belt (23).

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