Method for rapidly simulating weathering characteristics of coal gangue

Abstract

The invention discloses a method for rapidly simulating the weathering characteristic of coal gangue, and belongs to the technical field of solid waste treatment. The method comprises the following steps: 1) putting coal gangue into a tray with water permeable holes in the bottom, and then putting the tray into a water tank for 18 hours; (2) the obtained coal gangue is dried, the initial temperature is 40 DEG C, the coal gangue is heated to 80 DEG C within 3 h, heat preservation continues to be conducted for 3 h, and the coal gangue is cooled to the room temperature; (3) repeating the steps (1) and (2) for 10-60 days, and quickly simulating the weathering of the coal gangue; and (4) judging the weathering characteristic of the coal gangue under the natural condition by taking the unweathered coal gangue as a benchmark and selecting the crushing value growth rate, the mass loss rate and the mineral composition average difference value of the coal gangue subjected to rapid simulation weathering as characterization indexes. According to the method, the time required by coal gangue weathering research is greatly shortened, a reasonable basis is provided for indoor research of the coal gangue, reasonable application of the coal gangue is favorably realized, the emission and stockpiling pressure of the coal gangue is relieved, and the method has important application value.

Description

Technical Field

[0001] The invention belongs to the field of material engineering and environmental technology, and particularly relates to a method for rapidly simulating weathering characteristics of coal gangue. Background Art

[0002] Gangue is the carbon-containing rock discharged from coal mines during the production process of development and excavation, coal mining and coal washing. It has become one of the largest industrial solid wastes in my country. By 2017, the national gangue production reached 800 million tons. Shanxi is an important coal producing area in my country. According to statistics, about 120 million tons of gangue are discharged each year, and the cumulative stockpile volume reaches 1 billion tons. The accumulation of a large amount of gangue not only occupies a large amount of arable land, but also naturally produces a large amount of atmospheric pollutants, such as CO, CO2, SO2 and other harmful gases, which pollute the ecological environment. Gangue contains a large amount of silicon aluminum oxide. Processing gangue and replacing natural aggregates such as sand and stone is an effective way to recycle gangue resources.

[0003] Since coal gangue is easily weathered under natural conditions, and the physical and chemical properties of weathered coal gangue will deteriorate, but under natural conditions, it takes a long time and is difficult to operate to study the weathering characteristics of coal gangue. Therefore, a method to simulate the weathering characteristics of coal gangue under laboratory conditions is sought to provide an effective way for indoor research on coal gangue. Summary of the invention

[0004] The present invention proposes a simulation method for studying the weathering characteristics of coal gangue under natural conditions, and adopts crushing value, mass loss rate and mineral composition as characterization indicators, which can judge the weathering characteristics of coal gangue under natural conditions and realize indoor research on coal gangue.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A method for quickly simulating the weathering characteristics of coal gangue is provided, which specifically comprises the following steps:

[0007] 1) Place the coal gangue in a tray with water holes at the bottom and place it in a water tank for 18 hours;

[0008] 2) drying the coal gangue obtained in step 1), wherein the initial temperature is 40° C., heating to 80° C. within 3 h, keeping the temperature for 3 h, and cooling to room temperature;

[0009] 3) Repeat steps 1) and 2) for 10-60 days to quickly simulate the weathering of coal gangue;

[0010] 4) Taking unweathered coal gangue as the benchmark, the crushing value growth rate, mass loss rate and average difference of mineral composition of coal gangue after rapid simulation of weathering were selected as characterization indicators to judge the weathering characteristics of coal gangue under natural conditions.

[0011] According to the above scheme, in step 1), the particle size of the coal gangue is 4.75-19 mm.

[0012] According to the above scheme, in step 1), the water temperature of the water tank is 20-25°C.

[0013] According to the above scheme, in step 2), the coal gangue is dried in an oven.

[0014] According to the above scheme, in step 3), when the simulated weathering is carried out for 20 days, it corresponds to 1 year of natural weathering; when the simulated weathering is carried out for 40 days, it corresponds to 2 years of natural weathering; when the simulated weathering is carried out for 60 days, it corresponds to 4 years of natural weathering, at which time the coal gangue has been completely weathered.

[0015] According to the above scheme, in step 4), when the crushing value growth rate of the weathered coal gangue is less than 20%, the mass loss rate is less than 30%, and the average difference in mineral composition is less than 5%, it means that the coal gangue is not completely weathered in the natural state.

[0016] Provided is an application of the method for rapidly simulating weathering characteristics of coal gangue in determining the performance of coal gangue after natural weathering.

[0017] According to the above scheme, the weathering of coal gangue was quickly simulated by the above method, and three physical and chemical properties, namely the crushing value growth rate, mass loss rate and average difference in mineral composition, were used as characterization indicators to infer the performance of coal gangue after natural weathering.

[0018] Preferably, when the crushing value growth rate, mass loss rate and average difference in mineral composition of the coal gangue after natural weathering are no greater than the data of the rapid simulation of coal gangue weathering for 20 days, it means that the natural weathering time is no more than 1 year, and the crushing value, mass loss rate and mineral composition of the coal gangue when the weathering time is no more than 1 year are obtained.

[0019] Preferably, when the crushing value growth rate, mass loss rate and average difference in mineral composition after natural weathering are no greater than the data of rapid simulation of coal gangue weathering for 40 days, it means that the natural weathering time is no more than 2 years, and the crushing value, mass loss rate and mineral composition of the coal gangue when the weathering time is no more than 2 years are obtained.

[0020] Preferably, when the weathering of the coal gangue is rapidly simulated for 60 days, the crushing value, mass loss rate and mineral composition of the coal gangue when fully weathered are obtained.

[0021] According to the above scheme, the crushing value of coal gangue increases significantly within one year of natural weathering, increases slowly after 1 to 2 years of natural weathering, and increases rapidly until it is completely weathered after more than 2 years of natural weathering.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention conducts a rapid simulated weathering experiment on coal gangue to simulate the weathering of coal gangue under natural conditions, and uses three physical and chemical properties of crushing value, mass loss rate and mineral composition as characterization indicators to infer the performance of coal gangue, which greatly shortens the time required for the study of coal gangue weathering and provides a reasonable basis for indoor research on coal gangue, is conducive to the rational application of coal gangue, and alleviates the pressure of coal gangue discharge and storage, and has important application value. DETAILED DESCRIPTION

[0024] The specific embodiments are merely explanations of the present invention. The present invention will be further described below with reference to the specific implementation modes so that those skilled in the art can implement the invention with reference to the description. The protection scope of the present invention is not limited to the implementation modes of the present invention.

[0025] Example 1

[0026] This example conducts a rapid weathering experiment on coal gangue to simulate the weathering state of coal gangue under natural conditions:

[0027] The gangue was placed in a tray with water holes at the bottom and placed in a water tank for 18 hours. The water tank was connected to a water pipe in front and back. The volume of the water tank was 400mm×400mm. The obtained gangue was placed in an oven for drying for 6 hours. The initial temperature was 40℃, and the temperature was raised to 80℃ within 3 hours. The temperature was kept for 3 hours, cooled to room temperature, and then placed in a water tank. The cycle lasted for 20 days.

[0028] A comparative analysis was conducted on the coal gangue weathered for 20 days under simulated weathering and the coal gangue weathered for one year under natural conditions.

[0029] Step 1: Detect the crushing value and mineral composition of unweathered coal gangue.

[0030] Step 2: Detect the crushing value, mass loss rate and mineral composition of simulated weathered coal gangue and naturally weathered coal gangue.

[0031] The crushing values, mass loss rates and main mineral compositions of the three states of gangue obtained in this implementation are shown in Tables 1 and 2 below:

[0032] Table 1. Crushing values ​​and mass loss rates of three types of coal gangue

[0033] Crushing value / % Mass loss rate / % Unweathered coal gangue 26.4 / Simulated weathering 20d coal gangue 30.5 14.3 Natural weathering of coal gangue for one year 30.3 14.4

[0034] The difference in crushing value between simulated weathered gangue and naturally weathered gangue is 0.2%, and the difference in mass loss rate is 0.1%, indicating that simulated weathered gangue for 20 days can be used to simulate naturally weathered gangue for one year.

[0035] The changes in the crushing value of simulated weathering 20d coal gangue are as follows: the crushing value of simulated weathering 20d coal gangue is 30.5%, which is 4.1% higher than that of unweathered coal gangue, and the crushing value growth rate is 15.5%.

[0036] This indicates that after one year of natural weathering, the crushing value of coal gangue increases and its mechanical properties decrease, but it still meets the crushing value requirements for coarse aggregate in the base (≤35%) and subbase (≤40%) of secondary and below highways.

[0037] Table 2. Mass fraction of mineral components of three types of coal gangue (%)

[0038]

[0039] The main minerals in unweathered coal gangue and in simulated weathering and naturally weathered coal gangue are quartz, kaolinite, illite, pyrite, plagioclase, gypsum and calcite. The mineral composition after simulated weathering has not changed significantly, and the average difference in mineral composition is only 2.11%. At this time, the coal gangue is not completely weathered.

[0040] Example 2

[0041] This embodiment is the same as embodiment 1, except that the cycle time of the rapid simulation of weathered coal gangue is 40 days, and a comparative analysis is performed on the crushing value, mass loss rate and mineral composition of the coal gangue weathered naturally for two years.

[0042] The crushing values, mass loss rates and mineral compositions of the gangue in different states obtained in this embodiment are shown in Tables 3 and 4 below:

[0043] Table 3. Crushing values ​​and mass loss rates of three types of coal gangue

[0044] Crushing value / % Mass loss rate / % Unweathered coal gangue 26.4 / Simulated weathering 40d coal gangue 31.2 16.6 Natural weathering two years coal gangue 31.6 16.8

[0045] The difference in crushing value between simulated weathered gangue and naturally weathered gangue is 0.4%, and the difference in mass loss rate is 0.2%, which indicates that simulated weathered gangue for 40 days can be used to simulate gangue weathered for two years under natural conditions.

[0046] The changes in the crushing value of simulated weathering 40d coal gangue are as follows: the crushing value of simulated weathering 40d coal gangue is 31.2%, which is 4.8% higher than that of unweathered coal gangue, and the crushing value growth rate is 18.2%.

[0047] At this time, the weathered coal gangue can still meet the coarse aggregate crushing value requirements for the base (≤35%) and subbase (≤40%) of secondary and lower highways.

[0048] Table 4. Mass fraction of mineral components of three types of coal gangue (%)

[0049]

[0050] The main minerals in weathered coal gangue and in simulated weathering and naturally weathered coal gangue are quartz, kaolinite, illite, pyrite, plagioclase, gypsum and calcite. The mineral composition after simulated weathering has not changed significantly, and the average difference in mineral composition is 3.06%. At this time, the coal gangue is not completely weathered.

[0051] Example 3

[0052] This embodiment is the same as embodiment 1, except that the cycle time of the rapid simulation of weathered coal gangue is 60 days, and a comparative analysis is performed on the crushing value, mass loss rate and mineral composition of coal gangue that has been naturally weathered for four years.

[0053] The crushing values, mass loss rates and mineral compositions of the coal gangue in different states obtained in this embodiment are shown in Tables 5 and 6 below.

[0054] Table 5. Crushing values ​​and mass loss rates of three types of coal gangue

[0055] Crushing value / % Mass loss rate / % Unweathered coal gangue 26.4 / Simulated weathering 60d coal gangue 40.8 32.3％ Natural weathering of coal gangue for four years 42.0 30.6％

[0056] The difference in crushing value between simulated weathered coal gangue and naturally weathered coal gangue is 1.2%, and the difference in mass loss rate is 1.7%.

[0057] The changes in the crushing values ​​of simulated weathered 60d coal gangue and naturally weathered coal gangue are as follows:

[0058] The crushing value of simulated weathering 60d coal gangue is 40.8%, which is 14.4% higher than that of unweathered coal gangue, and the crushing value growth rate is 54.5%.

[0059] The crushing value of naturally weathered coal gangue is 42.0%, which is 15.6% higher than that of unweathered coal gangue, and the crushing value growth rate is 59.1%.

[0060] It can be clearly seen that the change in the crushing value of the weathered coal gangue in Example 3 is significantly greater than that in the previous two examples, wherein the crushing value growth rate exceeds 50%, and its mass loss rate also exceeds 30%. At this time, the coal gangue has been completely weathered and does not meet the crushing value requirements for coarse aggregate of the secondary and below highway base (≤35%) and subbase (≤40%).

[0061] Table 6. Mass fraction of three coal gangue mineral components (%)

[0062]

[0063] The main minerals in weathered coal gangue and in coal gangue with simulated 60d weathering and natural weathering are quartz, kaolinite, illite, pyrite, plagioclase, gypsum and calcite. However, the coal gangue has been completely weathered at this time, and the mineral composition of weathered coal gangue has changed significantly, with the average difference in mineral composition reaching 5.57%.

[0064] From the mineral composition and mass fraction of the gangue in Examples 1-3, it can be seen that as the weathering time increases, weathering destroys part of the mineral structure of the gangue, and water dissolves out, thereby reducing the clay mineral content in the weathered gangue aggregate. When the average difference in the mass fraction of the mineral components exceeds 5%, it means that the gangue has been completely weathered and is not suitable for use as a road base aggregate.

[0065] In Examples 1-3, the crushing values, mass loss rates and mineral composition differences of the naturally weathered gangue and the simulated weathered gangue are all within 5%, indicating that the gangue can be rapidly simulated for weathering for 20-60 days by the method of the present invention, and the weathering degree of the gangue under natural conditions within four years can be simulated. The weathering tendency of the gangue can be judged according to the numerical values ​​of the characterization indicators, and whether the weathered gangue can be used as aggregate can be judged.

[0066] Embodiment 4-6

[0067] Examples 4-6 are the same as Example 1, except that the cycle time for rapid simulation of weathered gangue is 10 days, 30 days and 50 days respectively. By comparing with unweathered gangue, the growth rate of crushing value, mass loss rate and average difference of main mineral composition of the state gangue at 10 days, 30 days and 50 days of simulated weathering are obtained, as shown in Table 1.

[0068] The growth rate of crushing value, mass loss rate and average difference of main mineral composition of simulated weathered gangue obtained in Examples 1-6 when circulated for 10-60 days are summarized and compared as shown in Table 7.

[0069] Table 7. Average difference in crushing value growth rate, mass loss rate and mineral composition of simulated weathered coal gangue

[0070] Cycle time 0d 10d 20d 30d 40d 50d 60d Crushing value growth rate / % / 9.5 15.5 16.7 18.2 34.8 54.5 Mass loss rate / % / 12.4 14.3 15.7 16.6 25.8 32.3 Average difference in mineral composition / % / 1.95 2.11 2.89 3.06 4.58 5.57

[0071] As shown in Table 7, within one year of natural weathering (i.e., 20 days of simulated weathering), the crushing value of coal gangue increases significantly, and within 1 to 2 years of natural weathering (i.e., 20-40 days of simulated weathering), the crushing value increases slowly, and after more than 2 years of natural weathering (i.e., more than 40 days of simulated weathering), the crushing value increases rapidly until it is completely weathered. This is conducive to studying the performance changes of coal gangue under weathering conditions.

[0072] At the same time, it can be known that when the simulated weathering time is 10-40 days, the crushing value growth rate of the simulated weathered coal gangue is less than 20%, the mass loss rate is less than 30%, and the average difference in mineral composition is less than 5%. At this time, the coal gangue is not completely weathered. When the simulated weathering time is 60 days, the crushing value growth rate, mass loss rate and average difference in mineral composition of the simulated weathered coal gangue all exceed the requirements of the present invention. At this time, the coal gangue has been completely weathered after 60 days of simulated weathering, and its performance has significantly decreased, and it is not suitable for application in the road base.

[0073] The disclosed embodiments and the above description enable professionals in the field to implement or use the present invention. Various modifications to the embodiments will be apparent to professionals in the field, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Parts not described in detail are prior art and are not described in detail herein. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and features disclosed herein.

Claims

1. A method for rapidly simulating the weathering characteristics of coal gangue, characterized in that: The specific steps include: 1) Place the coal gangue in a tray with water holes at the bottom and place it in a water tank for 18 hours; 2) drying the coal gangue obtained in step 1), wherein the initial temperature is 40° C., heating to 80° C. within 3 h, keeping the temperature for 3 h, and cooling to room temperature; 3) Repeat steps 1) and 2) for 10-60 days to quickly simulate the weathering of coal gangue; 4) Taking unweathered coal gangue as the benchmark, the crushing value growth rate, mass loss rate and average difference of mineral composition of coal gangue after rapid simulation of weathering were selected as characterization indicators to judge the weathering characteristics of coal gangue under natural conditions.

2. The method according to claim 1, characterized in that In the step 1), the particle size of the coal gangue is 4.75-19 mm.

3. The method according to claim 1, characterized in that In the step 1), the water temperature of the water tank is 20-25°C.

4. The method according to claim 1, characterized in that: In the step 3), when the simulated weathering is performed for 20 days, it corresponds to 1 year of natural weathering; when the simulated weathering is performed for 40 days, it corresponds to 2 years of natural weathering; when the simulated weathering is performed for 60 days, it corresponds to 4 years of natural weathering, at which time the coal gangue has been completely weathered.

5. The method according to claim 1, characterized in that In the step 4), when the crushing value growth rate of the weathered gangue is less than 20%, the mass loss rate is less than 30%, and the average difference in mineral composition is less than 5%, it means that the gangue is not completely weathered in the natural state.

6. Use of the method for rapidly simulating weathering characteristics of coal gangue as claimed in any one of claims 1 to 5 in determining the performance of coal gangue after natural weathering.

7. The use according to claim 6, characterized in that: The weathering of coal gangue is quickly simulated by the method described in any one of claims 1 to 5, and three physical and chemical properties, namely, the crushing value growth rate, the mass loss rate and the average difference in mineral composition, are used as characterization indicators to infer the performance of the coal gangue after natural weathering.

8. The use according to claim 7, characterized in that: When the crushing value growth rate, mass loss rate and average difference of mineral composition of coal gangue after natural weathering are not greater than the data of rapid simulation of coal gangue weathering for 20 days, it means that the natural weathering time is not more than 1 year, and the crushing value, mass loss rate and mineral composition of coal gangue when the weathering time is not more than 1 year are obtained; When the crushing value growth rate, mass loss rate and average difference of mineral composition after natural weathering are not greater than the data of 40 days of rapid simulation of coal gangue weathering, it means that the natural weathering time is not more than 2 years, and the crushing value, mass loss rate and mineral composition of coal gangue when the weathering time is not more than 2 years are obtained; When the weathering of coal gangue is rapidly simulated for 60 days, the crushing value, mass loss rate and mineral composition of the coal gangue when it is completely weathered are obtained.

9. The use according to claim 6, characterized in that: The crushing value of coal gangue increases significantly within one year of natural weathering. After 1 to 2 years of natural weathering, the crushing value increases slowly. After more than 2 years of natural weathering, the crushing value increases rapidly until it is completely weathered.

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