CN107843496B - Method for measuring firmness coefficient of structural soft coal - Google Patents
Method for measuring firmness coefficient of structural soft coal Download PDFInfo
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- CN107843496B CN107843496B CN201710946648.1A CN201710946648A CN107843496B CN 107843496 B CN107843496 B CN 107843496B CN 201710946648 A CN201710946648 A CN 201710946648A CN 107843496 B CN107843496 B CN 107843496B
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- 239000003245 coal Substances 0.000 title claims abstract description 213
- 238000000034 method Methods 0.000 title claims abstract description 50
- 238000005065 mining Methods 0.000 claims abstract description 14
- 238000009933 burial Methods 0.000 claims abstract description 11
- 239000004484 Briquette Substances 0.000 claims description 37
- 238000012360 testing method Methods 0.000 claims description 26
- 238000001035 drying Methods 0.000 claims description 14
- 238000004519 manufacturing process Methods 0.000 claims description 8
- 238000003825 pressing Methods 0.000 claims description 6
- 230000000052 comparative effect Effects 0.000 claims description 5
- 238000000465 moulding Methods 0.000 claims description 3
- 238000002360 preparation method Methods 0.000 claims description 2
- 238000005259 measurement Methods 0.000 abstract description 3
- 230000003247 decreasing effect Effects 0.000 abstract 1
- 238000011160 research Methods 0.000 description 3
- 239000011435 rock Substances 0.000 description 3
- 238000005070 sampling Methods 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000002817 coal dust Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 230000003116 impacting effect Effects 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/286—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q involving mechanical work, e.g. chopping, disintegrating, compacting, homogenising
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/30—Investigating strength properties of solid materials by application of mechanical stress by applying a single impulsive force, e.g. by falling weight
- G01N3/303—Investigating strength properties of solid materials by application of mechanical stress by applying a single impulsive force, e.g. by falling weight generated only by free-falling weight
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0014—Type of force applied
- G01N2203/0016—Tensile or compressive
- G01N2203/0019—Compressive
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/003—Generation of the force
- G01N2203/0032—Generation of the force using mechanical means
- G01N2203/0039—Hammer or pendulum
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Abstract
The invention discloses a method for measuring the firmness coefficient of structural soft coal, which comprises the following steps ofSelecting structural soft coal, recording the burial depth of the structural soft coal, and measuring the firmness coefficient f of the structural soft coal according to the coal firmness coefficient measuring method (GB/T23561.12-2010) of the national Standard
1According to different pressures applied to the buried depth of the coal bed, the soft coal is pressed into the formed coal, the pressure maintaining time is t, then the uniaxial compressive strength of the formed coal is measured, and the firmness coefficient f of the formed coal is calculated according to the uniaxial compressive strength
2If f is
1＝f
2When the pressure maintaining time is t
0If f is
1≠f
2Increasing or decreasing the pressure maintaining time t, and repeating the steps until f
1＝f
2When the pressure maintaining time is t
0Finally, when the firmness coefficients of other buried depths of the coal body in the same mining area are measured, the soft coal with the structure is pressed into the formed coal, wherein the pressure is obtained by calculation according to the buried depth, and the pressure maintaining time is t
0The uniaxial compressive strength of the molded coal was measured, and the firmness coefficient of the structural soft coal was calculated from the relationship between the firmness coefficient and the uniaxial compressive strength. The method is simple and convenient, and the measurement result meets the actual situation.
Description
Technical Field
The invention relates to a method for measuring the firmness coefficient of coal, in particular to a method for measuring the firmness coefficient of structural soft coal, and belongs to the field of mineral engineering.
Background
In order to study the geology of a coal seam in order to better serve mining, it is necessary to determine the mechanical parameters of the coal body. Currently, the firmness coefficient (also called Poisson coefficient) f of coal is used in China to evaluate the resistance of the coal to external force damage. The f-number is generally determined by the falling weight method. The drop hammer method considers that the work consumed by the crushing of coal is in proportion to the surface area increased by the crushed material, the constant related to the strength or the firmness of an object is related to the crushing ratio, and the firmness of the object can be expressed by the crushing ratio; when the firmness coefficient of coal is tested according to the national standard coal firmness coefficient measuring method (GB/T23561.12-2010), a pounding barrel, a metering barrel, a sample separating sieve, a small hammer and other instruments are needed, a heavy hammer is enabled to freely fall at a certain height to impact a sample, and then the value f is calculated according to the impact frequency n and the metering height l of coal dust under the sieve after impacting the sample by using the formula f which is 20 n/l; meanwhile, professor practicabo considers that: the value of the firmness factor f of coal or rock is 1/10 for the uniaxial compressive strength (in MPa) of rock or soil; the viewpoint is verified by a large number of field practices, has better engineering guidance significance, is convenient and accurate, and is widely applied to the field of geotechnical engineering.
In field practice, in the research on the occurrence state and the coal body property of a coal bed, multiple sampling is often required in different mining areas of the same mining area, and the firmness coefficient f of coal is respectively measured:
if the drop hammer method is adopted, the repeated labor amount is large due to more samples, more testing steps, longer testing time and complicated process, and the requirement on convenience is difficult to meet;
when the firmness coefficient of the coal is calculated by measuring the uniaxial compressive strength of the coal, the coal bed generates strain under the action of structural stress and formation pressure, so that the coal body structure is damaged in different degrees, the strength of the coal is low, the structural soft coal is a loose and crushed coal body with the coal body structure subjected to higher structural stress damage degree, the strength is extremely low, the yield of standard sample size (phi x H is 50mm x 100mm) specified by the international rock mechanics society is extremely low, and the uniaxial compressive strength is difficult to test, so that the relation between the uniaxial compressive strength of the structural soft coal and the firmness coefficient of the soft coal cannot be directly established.
Disclosure of Invention
The invention aims to provide a method for measuring the firmness coefficient of structural soft coal, which can calculate the firmness coefficient of the structural soft coal by measuring the uniaxial compressive strength of a molded coal, simplify the measuring steps and facilitate the popularization of engineering analogy.
In order to achieve the purpose, the invention adopts the technical scheme that: a method for determining the firmness factor of structural soft coal, comprising the steps of:
(1) selecting the structural soft coal: selecting a structural soft coal sample at one position in a coal seam, and simultaneously recording the burial depth H of the coal taking place;
(2) coefficient of firmness f of coal sample
1And (3) determination: measuring the firmness coefficient f of the coal sample obtained in the step (1) according to the coal firmness coefficient measuring method (GB/T23561.12-2010) of the national standard
1；
(3) Manufacturing the structural soft coal briquette:
a. and (3) calculating the forming pressure of a corresponding standard cylindrical sample by using a forming pressure formula, wherein the standard cylindrical sample dimension D multiplied by h is 50mm multiplied by 100mm, and the forming pressure formula is as follows: p ═ pi r
2Gamma H, wherein D is the diameter of the standard cylinder, H is the height of the standard cylinder, r is the radius of the standard cylinder, gamma is the volume weight of the overburden layer of the coal bed, and H is the buried depth of the coal sample;
b. pressing the crushed coal sample obtained in the step (1) into briquette with the size of a standard cylindrical test piece by using the molding pressure P calculated in the step, wherein the pressure maintaining time is t;
c. drying the molded coal;
(4) factor f of firmness of the briquettes
2And (3) determination: testing the uniaxial compressive strength P of the briquette test piece manufactured in the step (3)
0And calculating the firmness coefficient f2 of the briquette according to the relationship between the uniaxial compressive strength and the firmness coefficient;
(5) coefficient f of consistency of comparative coal sample
1And the factor f of firmness of the briquette
2Determining the dwell time t
0：
If f
1＝f
2The pressure maintaining time t for the briquette coal production in the step (3) is proved to be appropriate, the parameters are accurate, and the firmness of the briquette coal can reflect the firmness of the structural soft coal;
if f
1>f
2Repeating the step (3) and increasing the pressure maintaining time t, and then repeating the steps (4) to (5) until the result f is measured and calculated
1＝f
2Test piece of briquetteThe firmness reflects the firmness of the structural soft coal, and the dwell time t after adjustment in the above step (3) is t
0；
If f
1<f
2Repeating the step (3) and reducing the pressure maintaining time t, and then repeating the steps (4) to (5) until the result f is measured and calculated
1＝f
2The firmness of the molded coal specimen reflects the firmness of the structural soft coal, and the pressure maintaining time t after the adjustment in the step (3) is t
0；
(6) And (3) determining the firmness coefficients of other buried coal bodies in the same mining area: and (3) when measuring the firmness coefficients of other buried deep coal bodies in the same mining area, sequentially repeating the steps (1), (3) and (4), wherein the dwell time t in the step (3) is the dwell time t determined in the step (5)
0Finally obtaining the firmness coefficient f of the briquette
2Namely the firmness coefficient of the buried coal body.
Preferably, the selection and adjustment range of the pressure holding time t in the step (3) is 15min to 30 min.
In order to prevent the structure of the briquette from changing, preferably, in the step (3), the briquette is dried at a low temperature.
Preferably, the low-temperature drying adopts the temperature of 25-50 ℃ and the time of 12-36 h.
In order to make the mechanical test value of the obtained soft coal sample closer to the actual situation, the coal seam in the step (1) is preferably a newly exposed coal seam.
When the firmness coefficients of a plurality of test pieces are measured, only a one-time drop hammer method is needed, and the steps and the process are simpler and more convenient; meanwhile, compared with a method for directly measuring the uniaxial compressive strength of a standard test piece to measure the firmness coefficient, the method avoids the process of processing and manufacturing the standard test piece by using a complete coal sample, reduces the test difficulty and is convenient for engineering analogy and popularization; the briquette made of the structural soft coal has the advantages of strong formability, small fluctuation, simple process, easy determination of mechanical properties and the like, and can indirectly reflect the firmness of the structural soft coal, so the firmness coefficient of the coal body measured according to the method is closer to a true value.
Drawings
FIG. 1 is a flowchart of a method for measuring the firmness factor of soft coal according to the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
As shown in fig. 1, a method for measuring the firmness coefficient of structural soft coal includes the following steps:
(1) selecting the structural soft coal: selecting a structural soft coal sample at one position in a coal seam, and simultaneously recording the burial depth H of the coal taking place;
(2) coefficient of firmness f of coal sample
1And (3) determination: measuring the firmness coefficient f of the coal sample with complete lumpiness obtained in the step (1) according to the coal firmness coefficient measuring method (GB/T23561.12-2010) in the national Standard
1；
(3) Manufacturing the structural soft coal briquette:
a. and (3) calculating the forming pressure of a corresponding standard cylindrical sample by using a forming pressure formula, wherein the standard cylindrical sample dimension D multiplied by h is 50mm multiplied by 100mm, and the forming pressure formula is as follows: p ═ pi r
2Gamma H, wherein D is the diameter of the standard cylinder, H is the height of the standard cylinder, r is the radius of the standard cylinder, gamma is the volume weight of the overburden layer of the coal bed, and H is the buried depth of the coal sample;
b. pressing the crushed coal sample obtained in the step (1) into briquette with the size of a standard cylindrical test piece by using the molding pressure P calculated in the step, wherein the pressure maintaining time is t;
c. drying the molded coal;
(4) factor f of firmness of the briquettes
2And (3) determination: testing the uniaxial compressive strength P of the briquette test piece manufactured in the step (3)
0And calculating the firmness coefficient f of the briquette according to the relationship between the uniaxial compressive strength and the firmness coefficient
2；
(5) Coefficient f of consistency of comparative coal sample
1And the factor f of firmness of the briquette
2Determining the dwell time t
0：
If f
1＝f
2Proving the pressure maintaining time t for the briquette coal preparation in the step (3)
0Proper and accurate parameters, firm briquetteThe property can be reflected in the firmness of the structural soft coal, and the holding time t in the step (3) is t
0；
If f
1>f
2Repeating the step (3) and increasing the pressure maintaining time t, and then repeating the steps (4) to (5) until the result f is measured and calculated
1＝f
2The firmness of the molded coal specimen reflects the firmness of the structural soft coal, and the pressure maintaining time t in the step (3) is t
0；
If f
1<f
2Repeating the step (3) and reducing the pressure maintaining time t, and then repeating the steps (4) to (5) until the result f is measured and calculated
1＝f
2The firmness of the molded coal specimen reflects the firmness of the structural soft coal, and the pressure maintaining time t in the step (3) is t
0；
(6) And (3) determining the firmness coefficients of other buried coal bodies in the same mining area: and (3) when measuring the firmness coefficients of other buried deep coal bodies in the same mining area, sequentially repeating the steps (1), (3) and (4), wherein the dwell time t in the step (3) is the dwell time t determined in the step (5)
0Finally obtaining the firmness coefficient f of the briquette
2Namely the firmness coefficient of the buried coal body.
In practice, the pressure maintaining time t in the step (3) is short, the pressed molded coal is too soft and fragile to meet the experimental requirements, the strength of the pressed molded coal is not obviously increased after the pressure maintaining time t exceeds 30min, the pressure maintaining time t is within the range of 15min to 30min, and the finally measured firmness coefficient result can meet the requirements, so that the selection and adjustment range of the pressure maintaining time t is 15min to 30min, and the method is suitable.
When the molded coal is dried, because the moisture in the molded coal can be rapidly evaporated due to high temperature, and the interior of the molded coal is easily subjected to thermal expansion, the structure of the molded coal is finally changed and deviates from the real situation, preferably, in the step (3), the molded coal is dried in a low-temperature drying mode.
When the molded coal is dried, the drying time is longer at lower temperature, and the molded coal is easy to damage at high temperature; the drying time is short, incomplete drying can be caused, the molded coal is easy to be over-dried if the drying time is too long, according to experiments, the drying temperature is 25-50 ℃ and the drying time is 12-36 h, and the manufactured molded coal has good effect.
After the coal bed is exposed, the coal bed is contacted with air to generate slow oxidation reaction, so that the chemical structure of the coal bed is changed, and simultaneously, the internal physical structure of the coal bed is continuously changed after the coal bed is contacted with the air and water in the air; in order to make the mechanical test value of the obtained structural soft coal sample closer to the actual situation, when the coal sample is selected, the coal sample is selected from the newly exposed coal seam, that is, the coal seam in the step (1) is the newly exposed coal seam, and the newly exposed coal seam is closer to the state when the coal seam is not exposed because the time for contacting the air is shorter and the change is smaller.
When a plurality of test pieces are measured, only a one-time drop hammer method is needed, a large amount of repeated labor is avoided, and the steps and the process are simpler and more convenient; if the firmness coefficient is measured by directly measuring the uniaxial compressive strength of the standard test piece, a complete coal sample needs to be collected on site and then processed into the standard test piece by grinding or cutting and other methods, and the complete coal sample is difficult to take out of the structural soft coal sample, so that the firmness coefficient of the structural soft coal is measured by the method, the process of manufacturing the standard test piece by using the complete coal sample is avoided, the test difficulty is reduced, and the engineering analogy and popularization are facilitated; the briquette made of the structural soft coal has the advantages of strong seed formability, small fluctuation, simple process, easy determination of mechanical properties and the like, and can indirectly reflect the firmness of the structural soft coal, so the firmness coefficient of the coal body measured according to the method is closer to a true value.
The following are examples according to the above embodiments:
example 1:
(1) selecting the structural soft coal: taking a first coal mine as a research object, taking the coal seam of the first coal mine as structural soft coal, and selecting a structural soft coal sample in a newly exposed coal seam in a mining area with the coal mine buried depth of 800 m; recording the buried depth H as 800 m;
(2) coefficient of firmness f of coal sample
1And (3) determination: selecting the coal sample with complete lumpiness obtained in the step (1), and measuring the firmness coefficient f of the coal sample according to the method for measuring the firmness coefficient of coal (GB/T23561.12-2010) in the national Standard
1＝0.4；
(3) Manufacturing the structural soft coal briquette:
a. and (3) calculating the forming pressure of the corresponding sample with the standard cylinder size by using a forming pressure formula, wherein the forming pressure formula is as follows: p ═ pi r
2Gammah, wherein gamma measures 25kN/m
3If P is 39.25 kN;
b. pressing the crushed coal sample obtained in the step (1) into briquette with standard cylindrical test piece size (D × h is 50mm × 100mm), wherein the adopted pressure is 39.25kN, and the pressure maintaining time is 20 min;
c. drying the molded coal for 36 hours at the temperature of 25 ℃;
(4) factor f of firmness of the briquettes
2And (3) determination: the uniaxial compressive strength of the briquette is measured to be 4MPa, and according to a formula f ═ R/10, wherein R is the uniaxial compressive strength, the firmness coefficient f of the briquette is calculated
2＝0.4；
(5) Coefficient f of consistency of comparative coal sample
1And the factor f of firmness of the briquette
2Discovery f
1＝f
2From which the dwell time t can be determined
0＝20min；
(6) The firmness coefficients of the coal bodies in different burial depths of the mining area are measured: and (3) sampling the coal seam with the burial depth of 600m, repeating the step (3), wherein the pressure of the pressed molded coal is 29.4kN, the pressure maintaining time is still 20min, other parameters are unchanged, repeating the step (4) after pressing the molded coal, and finally measuring that the firmness coefficient f' of the coal seam with the burial depth of 600m is 0.32.
In order to verify the accuracy of the method for determining the firmness factor of the constructed soft coal, which is provided by the invention, the firmness factor f of the coal seam sample with the mine burial depth of 600m in the step (6) is measured again according to the coal firmness factor determination method (GB/T23561.12-2010) in the national standard
1'-0.30 ≈ f', which proves that the measured result of the present invention is close to the true value.
Example 2:
(1) selecting the structural soft coal: b, taking a coal mine B as a research object, taking the coal mine layer as structural soft coal, and selecting a structural soft coal sample in a newly exposed coal layer in a mining area with the coal mine buried depth of 600 m; recording the buried depth H as 600 m;
(2) coefficient of firmness f of coal sample
1And (3) determination: selecting the coal sample with complete lumpiness obtained in the step (1), and measuring the firmness coefficient f of the coal sample according to the method for measuring the firmness coefficient of coal (GB/T23561.12-2010) in the national Standard
1＝0.2；
(3) Manufacturing the structural soft coal briquette:
a. and (3) calculating the forming pressure of the corresponding sample with the standard cylinder size by using a forming pressure formula, wherein the forming pressure formula is as follows: p ═ pi r
2Gammah, wherein gamma measures 25kN/m
3，If P is 29.4 kN;
b. pressing the crushed coal sample obtained in the step (1) into briquette with standard cylindrical test piece size (D × h is 50mm × 100mm), wherein the adopted pressure is 29.4kN, and the pressure maintaining time is 20 min;
c. drying the molded coal for 12 hours at the temperature of 50 ℃;
(4) factor f of firmness of the briquettes
2And (3) determination: the uniaxial compressive strength of the briquette is measured to be 1.5MPa, and according to the formula f ═ R/10, wherein R is the uniaxial compressive strength, the firmness coefficient f of the briquette is calculated
2＝0.15；
(5) Coefficient f of consistency of comparative coal sample
1And the factor f of firmness of the briquette
2Discovery f
1＞f
2Repeating the steps (4) to (5) wherein the dwell time is increased to 25min and as a result f is measured
2＝0.2＝f
1Thus determining the pressure maintaining time of the coal mine manufactured molded coal to be 25 min;
(6) the firmness coefficients of the coal bodies in different burial depths of the mining area are measured: and (3) sampling the coal seam with the buried depth of 1000m, repeating the step (3), wherein the pressure of the pressed molded coal is 49kN, the pressure maintaining time is still 25min, other parameters are unchanged, and after the molded coal is pressed, repeating the step (4), and finally measuring that the coal seam firmness coefficient f' with the buried depth of 1000m of the coal mine is 0.5, namely the coal seam firmness coefficient with the buried depth of 1000m of the coal mine is 0.5.
To verify the accuracy of the method for determining the firmness coefficient of soft coal proposed by the present invention, the sample of the coal seam with the mine burial depth of 1000m in step (6) was examinedThe coal bed firmness coefficient f is measured again according to the method for measuring the coal firmness coefficient (GB/T23561.12-2010) in the national standard
1'-0.53 ≈ f', the results prove that the results measured by the present invention are close to the true values.
When the firmness coefficient of the coal body is measured for coal seams with different burial depths of other coal mines, the measurement can be carried out according to the steps, the method is simple, convenient and fast, easy to implement and convenient to popularize, and the measurement result meets the actual situation.
Claims (5)
1. A method for measuring a firmness coefficient of structural soft coal, comprising: the method comprises the following steps:
(1) selecting the structural soft coal: selecting a structural soft coal sample at one position in a coal seam, and simultaneously recording the burial depth H of the coal taking place;
(2) coefficient of firmness f of coal sample
1And (3) determination: measuring the firmness coefficient f of the coal sample obtained in the step (1) according to the coal firmness coefficient measuring method (GB/T23561.12-2010) of the national standard
1；
(3) Manufacturing the structural soft coal briquette:
a. and (3) calculating the forming pressure of a corresponding standard cylindrical sample by using a forming pressure formula, wherein the size D multiplied by h of the standard cylindrical sample is 50mm multiplied by 100mm, and the forming pressure formula is as follows: p ═ pi r
2Gamma H, wherein D is the diameter of the standard cylinder, H is the height of the standard cylinder, r is the radius of the standard cylinder, gamma is the volume weight of the overburden layer of the coal bed, and H is the buried depth of the coal sample;
b. pressing the crushed coal sample obtained in the step (1) into briquette with the size of a standard cylindrical test piece by using the molding pressure P calculated in the step, wherein the pressure maintaining time is t;
c. drying the molded coal;
(4) factor f of firmness of the briquettes
2And (3) determination: testing the uniaxial compressive strength P of the briquette test piece manufactured in the step (3)
0And calculating the firmness coefficient f of the briquette according to the relationship between the uniaxial compressive strength and the firmness coefficient
2；
(5) Coefficient f of consistency of comparative coal sample
1And the factor f of firmness of the briquette
2Determining the dwell time t
0：
If f
1＝f
2The pressure maintaining time t for the briquette coal preparation in the step (3) is proved to be appropriate, the parameters are accurate, the firmness of the briquette coal can reflect the firmness of the structural soft coal, and the pressure maintaining time t in the step (3) is t
0；
If f
1>f
2Repeating the step (3) and increasing the pressure maintaining time t, and then repeating the steps (4) to (5) until the result f is measured and calculated
1＝f
2The firmness of the molded coal specimen reflects the firmness of the structural soft coal, and the pressure maintaining time t after the adjustment in the step (3) is t
0；
If f
1<f
2Repeating the step (3) and reducing the pressure maintaining time t, and then repeating the steps (4) to (5) until the result f is measured and calculated
1＝f
2The firmness of the molded coal specimen reflects the firmness of the structural soft coal, and the pressure maintaining time t after the adjustment in the step (3) is t
0；
(6) And (3) determining the firmness coefficients of other buried coal bodies in the same mining area: and (3) when measuring the firmness coefficients of other buried deep coal bodies in the same mining area, sequentially repeating the steps (1), (3) and (4), wherein the dwell time t in the step (3) is the dwell time t determined in the step (5)
0Finally obtaining the firmness coefficient f of the briquette
2Namely the firmness coefficient of the buried coal body.
2. The method of claim 1, wherein the method comprises: the selection and adjustment range of the pressure maintaining time t in the step (3) is 15-30 min.
3. The method of claim 1, wherein the method comprises: in the step (3), the molded coal is dried at low temperature.
4. The method of claim 3, wherein the method comprises: the low-temperature drying adopts the temperature of 25-50 ℃ and the time of 12-36 h.
5. The method for determining the firmness factor of a structural soft coal according to any one of claims 1 to 4, wherein: and (2) the coal seam in the step (1) is a newly exposed coal seam.
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