Method for determining gangue slurry particle size and concentration based on conveying distance

Abstract

The application discloses a method for determining gangue slurry particle size and concentration based on conveying distance, and is implemented according to the following steps: step 1, conveying time is calculated according to the farthest conveying distance and critical flow velocity; step 2, bleeding rate long-time change experiments of different concentrations and different upper limit particle sizes are carried out according to step 1, and the upper limit particle size and the slurry concentration range are determined; step 3, slump degree and spread degree experiments are carried out according to the upper limit particle size and the slurry concentration range determined in step 2, and the self-flow gradient is calculated; step 4, if the self-flow gradient meets the fluidity requirement, the slurry concentration range is the final concentration range; if the self-flow gradient does not meet the fluidity requirement, the upper limit particle size is reduced, and step 3 is repeated until the concentration meeting the fluidity requirement at the particle size appears, and the concentration is taken as the final concentration range. The method for determining gangue slurry particle size and concentration based on conveying distance reduces the energy consumption of gangue crushing and slurry preparation, reduces the operation cost of the slurry filling system, and improves the popularization applicability of the technology.

Description

Technical Field

[0001] This invention belongs to the field of coal mine gangue slurry filling technology, and relates to a method for determining the particle size and concentration of gangue slurry based on the conveying distance. Background Technology

[0002] With the continuous advancement of ecological civilization construction, gangue slurry backfilling, as a large-scale, efficient, and low-cost gangue disposal method, is being increasingly promoted. During the application of this technology, ensuring the stable long-distance transport of the slurry and its diffusion performance within the goaf directly affects the stability and efficiency of the backfilling system. Previous studies have shown that smaller particle sizes result in higher slurry stability and less segregation; higher concentrations also lead to higher slurry stability and less segregation. However, increased slurry stability also leads to increased transport resistance and limited diffusion distance within the goaf, affecting the backfilling effect.

[0003] In engineering design, to ensure stable system operation, the particle size and concentration parameters are set relatively conservatively, based on static conditions, without considering factors such as time and conveying distance. Therefore, to further reduce system costs based on specific filling conditions, this invention proposes to include conveying distance and time as factors influencing the determination of particle size and concentration parameters, thereby further optimizing the particle size and gradation of the gangue slurry. Summary of the Invention

[0004] The purpose of this invention is to provide a method for determining the particle size and concentration of gangue slurry based on the conveying distance, which has the advantages of reducing energy consumption in crushing and slurry preparation and reducing the operating cost of slurry filling.

[0005] The technical solution adopted in this invention is a method for determining the particle size and concentration of gangue slurry based on the conveying distance, which is implemented according to the following steps:

[0006] Step 1: Calculate the conveying time t based on the farthest conveying distance and critical flow velocity;

[0007] Step 2: Based on Step 1, conduct long-term experiments on the changes in bleeding rate under different concentrations and upper limit particle sizes to determine the upper limit particle size and the pulping concentration range under each upper limit particle size.

[0008] Step 3: Conduct slump and spread tests based on the upper limit particle size and the pulp concentration range under each upper limit particle size determined in Step 2, and calculate the self-flowing slope;

[0009] Step 4: If the self-flowing slope meets the fluidity requirements, the pulp concentration range is the final concentration range; if the self-flowing slope does not meet the fluidity requirements, the upper limit particle size is reduced and step 3 is repeated until a concentration that meets the fluidity requirements at that particle size is obtained, which is taken as the final concentration range.

[0010] The invention is further characterized by:

[0011] Step 1 is as follows:

[0012] Step 1.1: Take the farthest filling position of the gangue slurry filling system as the farthest conveying distance L under this filling condition. max ;

[0013] Step 1.2: Calculate the minimum flow velocity V of the gangue slurry based on the characteristics of the conveyed material and the operating conditions. min ;

[0014] Step 1.3, based on the furthest conveying distance L max and critical flow velocity V min Calculate the transport time t, then: t = L max / V min .

[0015] The minimum flow velocity V of the gangue slurry in step 1.2 min The calculation formula is as follows:

[0016]

[0017] Among them, V min ρ is the critical flow velocity, expressed in m / s. s Density of gangue powder, in kg / m³ 3 ;ρ h This is the density of water, expressed in kg / m³. 3 C QV is the flow rate and volume concentration of the solid-liquid two-phase flow; D is the pipe diameter in meters.

[0018] Step 2 is as follows:

[0019] Step 2.1: The test duration is not less than 1.3t, the test concentration range is 60% to 80%, the change gradient is 5%, and the upper limit particle size range is 0.6mm to 5mm. Conduct a long-term experiment on the change of water seepage rate.

[0020] Step 2.2: Based on the experimental results of the bleeding rate obtained in Step 2.1, analyze the variation law of the bleeding rate, and determine the upper limit particle size and the pulp concentration range under each upper limit particle size according to the bleeding rate index.

[0021] The bleeding rate index in step 2.2 is: when the bleeding rate is not greater than 4%, the gangue slurry is considered to be in a stable state at that moment.

[0022] The gravity flow slope in step 3 is:

[0023]

[0024] Where i is the gravity slope, λ is the slump, and μ is the spread.

[0025] The fluidity requirement in step 4 is: the gravity flow slope is no greater than 0.4.

[0026] The beneficial effects of this invention are:

[0027] This invention provides a method for determining the particle size and concentration of gangue slurry based on the conveying distance. By optimizing the particle size composition and concentration range of gangue slurry according to the conveying distance under specific working conditions, it can avoid waste due to excessive crushing of gangue. Under the premise of ensuring conveying and filling requirements, it can maximize the upper limit particle size of gangue, reduce the crushing ratio of gangue, facilitate equipment selection and improve system stability, reduce the energy consumption of gangue crushing and slurry preparation, reduce the operating cost of the slurry filling system, and improve the applicability of this technology. Attached Figure Description

[0028] Figure 1 This is a flowchart of the method for determining the particle size and concentration of gangue slurry based on the conveying distance according to the present invention. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0030] Example 1

[0031] This invention relates to a method for determining the particle size and concentration of gangue slurry based on conveying distance, such as... Figure 1 As shown, please follow these steps:

[0032] Step 1: Calculate the conveying time t based on the farthest conveying distance and critical flow velocity;

[0033] Step 2: Based on Step 1, conduct long-term experiments on the changes in bleeding rate under different concentrations and upper limit particle sizes to determine the upper limit particle size and the pulping concentration range under each upper limit particle size.

[0034] Step 3: Conduct slump and spread tests based on the upper limit particle size and the pulp concentration range under each upper limit particle size determined in Step 2, and calculate the self-flowing slope;

[0035] Step 4: If the self-flowing slope meets the fluidity requirements, the pulp concentration range is the final concentration range; if the self-flowing slope does not meet the fluidity requirements, the upper limit particle size is reduced and step 3 is repeated until a concentration that meets the fluidity requirements at that particle size is obtained, which is taken as the final concentration range.

[0036] Example 2

[0037] This invention relates to a method for determining the particle size and concentration of gangue slurry based on conveying distance, such as... Figure 1 As shown, please follow these steps:

[0038] Step 1: Calculate the conveying time t based on the farthest conveying distance and critical flow velocity;

[0039] Step 1 is as follows:

[0040] Step 1.1: Take the farthest filling position of the gangue slurry filling system as the farthest conveying distance L under this filling condition. max ;

[0041] Step 1.2: Calculate the minimum flow velocity V of the gangue slurry based on the characteristics of the conveyed material and the operating conditions. min ;

[0042] Specifically, in step 1.2, the minimum flow velocity V of the gangue slurry... min The calculation formula is as follows:

[0043]

[0044] Among them, V min ρ is the critical flow velocity, expressed in m / s. s Density of gangue powder, in kg / m³ 3 ;ρ h This is the density of water, expressed in kg / m³. 3 C QV is the flow rate and volume concentration of the solid-liquid two-phase flow; D is the pipe diameter in meters.

[0045] Step 1.3: Based on the aforementioned maximum conveying distance L max and critical flow velocity V min Calculate the transport time t, then: t = L max / V min ;

[0046] Step 2: Based on Step 1, conduct long-term experiments on the changes in bleeding rate under different concentrations and upper limit particle sizes to determine the upper limit particle size and the pulping concentration range under each upper limit particle size.

[0047] Step 2 is as follows:

[0048] Step 2.1: The test duration is not less than 1.3t, the test concentration range is 60% to 80%, the change gradient is 5%, and the upper limit particle size range is 0.6mm to 5mm. That is, when the upper limit particle size is set to 5mm, the particle size in the gangue slurry is not greater than 5mm, so as to carry out the long-term change experiment of the bleeding rate.

[0049] Step 2.2: Based on the experimental results of the bleeding rate obtained in Step 2.1, analyze the variation law of the bleeding rate, and determine the upper limit particle size and the pulp concentration range under each upper limit particle size according to the bleeding rate index.

[0050] The bleeding rate index in step 2.2 is: when the bleeding rate is not greater than 4%, the gangue slurry is considered to be in a stable state at that moment;

[0051] Step 3: Conduct slump and spread tests based on the upper limit particle size and pulp concentration range determined in Step 2, and calculate the self-flowing slope;

[0052] The gravity flow slope in step 3 is:

[0053]

[0054] Where i is the gravity slope, λ is the slump, and μ is the spread.

[0055] Step 4: According to Step 3: If the self-flowing slope meets the fluidity requirements, the pulp concentration range is the final concentration range; if the self-flowing slope does not meet the fluidity requirements, the upper limit particle size is reduced and Step 3 is repeated until a concentration that meets the fluidity requirements at that particle size is obtained, which is taken as the final concentration range.

[0056] The fluidity requirement in step 4 is: the gravity flow slope is no greater than 0.4.

[0057] Example 3

[0058] Taking a coal mine gangue slurry backfilling system as an example, the system has a backfilling capacity of 1 million tons per year. According to the mine's continuity plan, the maximum conveying distance of the system within 10 years is 6 km. Based on the characteristics of the conveyed material and the test data of the loop pipe, the critical flow velocity is determined to be 1.5 m / s. According to conventional design, in order to ensure the stable operation of the system, the particle size and concentration parameters are selected relatively conservatively based on static conditions, with an upper limit particle size of 1.25 mm. Currently, a single crushing unit cannot reach the system capacity of 1 million tons per year, and the crushed particle size cannot meet the requirements. A ball mill needs to be selected, but the system consumes a lot of energy, the crushing cost is high, and long-term operation will place a heavy burden on the enterprise.

[0059] Therefore, the method of determining the particle size and concentration of gangue slurry based on the conveying distance of this invention can be used to optimize the particle size and concentration under this working condition, specifically including the following steps:

[0060] Step 1: Calculate the conveying time t based on the farthest conveying distance and critical flow velocity;

[0061] The furthest filling location of the gangue slurry filling system within 10 years is taken as the furthest transportation distance L under this filling condition. max =6km;

[0062] The minimum flow velocity V of the gangue slurry was calculated based on the characteristics of the conveyed material and the operating conditions. min =1.5m / s;

[0063] According to the aforementioned maximum conveying distance L max and critical flow velocity V min Calculate the transport time t, then: t = L max / V min =67min;

[0064] Step 2: Based on Step 1, conduct long-term experiments on the changes in bleeding rate under different concentrations and upper limit particle sizes to determine the upper limit particle size and the pulping concentration range under each upper limit particle size.

[0065] The test duration is no less than 87 minutes, the test concentration range is 60% to 80%, the change gradient is 5%, and the upper limit particle size is set to 5 mm, 3 mm, 2.5 mm, 1.25 mm and 0.6 mm respectively to conduct a long-term experiment on the change of water seepage rate.

[0066] The experimental results of the obtained water exudation rate are shown in Table 1:

[0067] Table 1 Results of the water seepage rate experiment

[0068]

[0069]

[0070]

[0071] The variation law of bleeding rate was analyzed. Based on the experimental results of long-term changes in bleeding rate of gangue slurry with different concentrations and upper limit particle sizes, when the bleeding rate is less than 4%, the gangue slurry is considered to be in a stable state at that time. Bleeding rate tests were conducted with different concentrations according to the upper limit particle size gradients of 5mm, 3mm, 2.5mm, 1.25mm, and 0.6mm. If the test time reaches 1.3t at this particle size, no concentration can maintain the stability of the slurry, and there is a concentration in the next gradient that can maintain the stability of the slurry, then the next gradient particle size is the upper limit particle size for this conveying distance. The slurry concentration range of each particle size gradient below this upper limit particle size can be determined based on the result that the bleeding rate is less than 4% under the condition of 1.3t time. Therefore, based on the bleeding rate index, the upper limit particle size is determined to be 5mm, and the slurry concentration range is 80%.

[0072] Step 3: Conduct slump and spread tests at 80% concentrations based on the determined upper limit particle size; the test results for 80% concentration are a slump of 240cm and a spread of 200cm, and the gravity flow slope is calculated to be 0.6 based on the slump and spread.

[0073] Step 4: The self-flowing slope result is greater than 0.4. The slurry under this particle size concentration does not meet the fluidity requirements. Therefore, the upper limit particle size is lowered to 3mm. When the particle size is 3mm, the slurry concentration range is 70%–80%. Step 3 is repeated to conduct slump and spread tests at different concentrations of 70%–80%. The test results for 70% concentration are 280cm slump and 185cm spread; the test results for 75% concentration are 260cm slump and 230cm spread; and the test results for 80% concentration are 100cm slump and 140cm spread. Based on the slump and spread, the calculated self-flowing slopes are 0.22, 0.35, and 2.86, respectively. Concentrations of 70% and 75% meet the slurry fluidity requirements. Therefore, the final determined concentration range is 70%–75%.

Claims

1. A method for determining the particle size and concentration of gangue slurry based on conveying distance, characterized in that, The specific steps are as follows: Step 1: Calculate the conveying time t based on the farthest conveying distance and critical flow velocity; Step 2: Based on Step 1, conduct long-term experiments on the changes in bleeding rate under different concentrations and upper limit particle sizes to determine the upper limit particle size and the pulping concentration range under each upper limit particle size. Step 3: Conduct slump and spread tests based on the upper limit particle size and the pulp concentration range under each upper limit particle size determined in Step 2, and calculate the self-flowing slope; Step 4: If the self-flowing slope meets the fluidity requirements, the pulp concentration range is the final concentration range; if the self-flowing slope does not meet the fluidity requirements, the upper limit particle size is reduced and Step 3 is repeated until a concentration that meets the fluidity requirements at that particle size is obtained, which is taken as the final concentration range. Step 1 specifically involves: Step 1.1: Take the farthest filling position of the gangue slurry filling system as the farthest conveying distance L under this filling condition. max ; Step 1.2: Calculate the minimum flow velocity V of the gangue slurry based on the characteristics of the conveyed material and the operating conditions. min ; Step 1.3: Based on the aforementioned maximum conveying distance L max and critical flow velocity V min Calculate the transport time t, then: t = L max / V min ; In step 1.2, the minimum flow velocity V of the gangue slurry min The calculation formula is as follows: V min = ； Among them, V min The critical velocity is expressed in m / s. ρ s Density of gangue powder, in kg / m³ 3 ; ρ h This is the density of water, expressed in kg / m³. 3 ; C QV The volumetric concentration at which the flow rate is measured in a solid-liquid two-phase flow. D This refers to the pipe diameter, in meters (m). Step 2 specifically involves: Step 2.1: The test duration shall not be less than 1.3t, the test concentration range shall be 60%~80%, the change gradient shall be 5%, and the upper limit of the particle size shall be 0.6mm~5mm. Conduct a long-term experiment on the change of the water seepage rate. Step 2.2: Based on the experimental results of the bleeding rate obtained in Step 2.1, analyze the variation law of the bleeding rate, and determine the upper limit particle size and the pulp concentration range under each upper limit particle size according to the bleeding rate index. The gravity flow slope in step 3 is: i= ； Where i is the gravity flow slope. Slump For scalability.

2. The method for determining the particle size and concentration of gangue slurry based on the conveying distance according to claim 1, characterized in that, The bleeding rate index in step 2.2 is: when the bleeding rate is not greater than 4%, the gangue slurry is considered to be in a stable state at that moment.

3. The method for determining the particle size and concentration of gangue slurry based on the conveying distance according to claim 1, characterized in that, The fluidity requirement in step 4 is that the gravity flow slope is no greater than 0.4.

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