Composite dust suppression microcapsule for open-pit coal mine and preparation method thereof

Abstract

The invention discloses a composite dust suppression microcapsule for open-pit coal mines and a preparation method thereof. Arabic gum is used as a skeleton and acrylamide is used as a monomer. A gum Arabic-based super absorbent resin dust suppressant is synthesized by a free radical solution polymerization method. Then, paraffin oil is used as a core material and gelatin-modified Arabic gum dust suppressant is used as a wall material. The paraffin oil is coated by a complex coagulation method by means of the electrostatic condensation of the two, thereby synthesizing a composite dust suppression microcapsule. In view of the randomness and variability of coal dust, the microcapsule sustained-release technology is used to synthesize a composite dust suppression microcapsule by coating paraffin oil with gelatin-modified Arabic gum as a wall material, thereby realizing the functional integration optimization of a coagulation-type dust suppressant and a bonding-type dust suppressant.

Description

Technical Field

[0001] The invention relates to a composite dust suppression microcapsule for open-pit coal mines and a preparation method thereof, belonging to the technical field of dust suppressants. Background Art

[0002] A large amount of dust is generated during the production operation of open-pit mines, which has become the main factor restricting the safe production of coal mines in recent years. Mine dust, as an inevitable product of the coal production process, is one of the main causes of mine production disasters and an important factor endangering the occupational health of miners. The high concentration of dust at the underground production site of coal mines can reduce the labor productivity of miners and affect the quality and efficiency of mines. In severe cases, it can cause miners to die of pneumoconiosis that cannot be cured for a long time, or cause dust explosions, and even cause gas explosion accidents, resulting in major casualties and economic losses. Data from the environmental protection department show that dust pollution caused by open-pit coal mines, coal storage and coal transportation has caused serious ecological damage. In view of the inefficiency of traditional dust prevention and control technologies and their difficulty in adapting to new production needs and environmental protection requirements, reducing the spread of coal dust is related to the physical health and life safety of individual workers. Therefore, dust control in open-pit coal mines is urgent, and the research and development of new dust suppression materials is also imperative.

[0003] Microcapsule technology is widely used in the fields of food, clothing, construction, etc., but less used in the field of dust suppression. Microcapsule technology can encapsulate dust suppressants, thereby extending the dust suppression time and enhancing the dust suppression effect, so attempts are gradually being made. In the field of dust suppression in open-pit coal mines, the dust suppressants that are currently being studied more include inorganic salt solutions, surfactants, super absorbent resins and other types of dust suppressants. There are many types of dust suppressants, but the action time of dust suppressants has always been a problem that plagues the dust suppression effect. In actual applications, dust suppressants last for a short time after taking effect, and it is difficult to suppress dust for the next dusting, and chemical dust suppressants still have the disadvantage of harming the environment. Therefore, using microcapsule technology to develop a dust suppression microcapsule with a long action time and high dust suppression efficiency has become a new idea in the field of dust suppression in open-pit coal mines. Through the above analysis, the problems and defects of the existing technology are as follows:

[0004] (1) The current physical dust control technology still has many problems, such as great waste of water resources, high difficulty in operation, limited dust suppression area, and short effective dust suppression time.

[0005] (2) Compared with physical dust suppression, chemical dust suppression is more efficient and more targeted. However, current chemical dust suppressants fail to fully consider the characteristics of dust, and their dust suppression function is relatively single.

[0006] (3) In actual application, existing dust suppressants have problems such as short dust suppression time and low efficiency, and microcapsule technology is rarely used. Summary of the invention

[0007] In response to the above problems, the first purpose of the present invention is to provide a method for preparing composite dust suppression microcapsules for open-pit coal mines. The second purpose is to provide such composite dust suppression microcapsules for open-pit coal mines, so as to achieve functional integrated optimization of condensing dust suppressants and bonding dust suppressants and improve the dust suppression effect.

[0008] In order to achieve the above-mentioned first purpose, the technical solution of the present invention is: a method for preparing composite dust suppression microcapsules for open-pit coal mines, characterized in that: using gum arabic as the skeleton and acrylamide as the monomer, a gum arabic-based super absorbent resin dust suppressant is synthesized by free radical solution polymerization; then using paraffin oil as the core material and gelatin-modified gum arabic dust suppressant as the wall material, a complex coacervation method is used to coat the paraffin oil with the help of the electrostatic condensation effect of the two, thereby synthesizing composite dust suppression microcapsules.

[0009] The present invention firstly uses green and degradable gum arabic as raw material to synthesize a condensed super absorbent resin dust suppressant, strengthens the moisture absorption and water retention performance through grafting modification, and improves its ability to condense and agglomerate dust; secondly, the electrostatic coagulation of gelatin and gum arabic dust suppressant is used to form a stable complex coagulant, which is used as the microcapsule wall material, and then paraffin oil is coated to synthesize composite dust suppression microcapsules, realizing the functional integration optimization of condensed dust suppressant and adhesive dust suppressant. Based on the release kinetics research of dust suppression microcapsules and the dust suppression performance surface, adhesive dust suppressant and condensed dust suppressant have a synergistic dust suppression effect. Prepare according to the following steps:

[0010] Step 1, preparation of gum arabic based super absorbent dust suppressant, adding gum arabic into deionized water, then adding emulsifier, heating to 45°C and stirring fully, adding ammonium persulfate initiator, acrylamide monomer and N,N-methylenebisacrylamide crosslinker in sequence with a dropping funnel, reacting at 50-70°C for 3-10h; finally, washing the reaction solution with ethanol to remove unreacted monomer and water, drying to obtain gum arabic based super absorbent dust suppressant, crushing for standby use;

[0011] Step 2: Add gelatin to deionized water, heat to 45°C and stir until fully dissolved; mix glyceryl monostearate and Tween-80 in a certain mass ratio to obtain a composite emulsifier; then add the composite emulsifier and paraffin oil to the gelatin solution, mix well and stir at a high speed until a uniform and stable emulsion is formed;

[0012] Step 3, adding the dried and crushed gum arabic-based super absorbent dust suppressant into deionized water, stirring at high speed mechanically to form a uniform dust suppressant solution, and setting aside; heating the emulsion of step 2 at 30-60° C. and adding dropwise to the dust suppressant solution under stirring conditions, and continuing the reaction for 0.5-2h after the dropwise addition is completed to form a stable oil-in-water emulsion, and then adjusting the pH value of the solution to 3.5-4.5 with an acidic pH regulator;

[0013] Step 4: cool the solution to below 10°C with a cold water bath, add a curing agent, react for 0.5h, then adjust the pH value to 6.0-8.5 with an alkaline pH adjuster, continue to stir slowly for 0.5-3h, and then let stand for the microcapsules to settle;

[0014] Step 5: After filtering the microcapsule suspension, the obtained microcapsule product is repeatedly washed three times with anhydrous ethanol and deionized water, and freeze-dried to obtain composite dust suppression microcapsules for open-pit coal mines.

[0015] In the above scheme: the acidic pH regulator is citric acid, and the alkaline pH regulator is sodium bicarbonate.

[0016] In the above scheme: in the preparation process of the gum arabic-based super absorbent resin dust suppressant, the emulsifier is sorbitan fatty acid ester.

[0017] In the above scheme: in step 1, the mass of the emulsifier added is 8%-12% of the amount of gum arabic added, the amount of the initiator added is 2%-6% of the amount of gum arabic added, the amount of the acrylamide monomer added is 30%-60% of the amount of gum arabic added, and the amount of the crosslinker added is 2%-12% of the gum arabic added.

[0018] In the above scheme: during the synthesis of microcapsules, the curing agent is glutaraldehyde.

[0019] In the above scheme, the total amount of stearyl glyceryl and Tween-80 added is 4%-10% of the amount of gelatin added, and the amount of paraffin oil added is 50%-150% of the amount of gelatin added.

[0020] In the above scheme: in step 3, in the process of adding the emulsion to the dust suppressant solution using a constant pressure dropping funnel, in order to ensure the uniformity of the microcapsule size, the emulsion must be added within 0.5 hours and the stirring rate must be greater than 5000 rpm.

[0021] The pH of gelatin and gum arabic is adjusted to 3.5-4.5 to make the positive and negative charges of both equal. The necessary conditions for the synthesis of microcapsules by complex coacervation are that the charges of the related polymer ions are opposite and the number of ions in the mixture is exactly equal electrically. The combination of gelatin and gum arabic can meet the above requirements.

[0022] A composite dust suppression microcapsule for open-pit coal mine prepared by the preparation method of the composite dust suppression microcapsule for open-pit coal mine.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1) Use green and renewable gelatin and gum arabic as raw materials for preparing dust suppression microcapsule wall materials, and use electrostatic coagulation to form stable complex coagulants. The raw materials are simple, easy to obtain, green, environmentally friendly, and degradable, and will not cause secondary pollution to the environment.

[0025] (2) A gum arabic-based super absorbent resin dust suppressant was prepared by free radical polymerization. This type of resin mainly plays the role of condensing and agglomerating dust in the dust suppression process, and the moisture absorption and water retention function of the gum arabic-based super absorbent resin dust suppressant was enhanced by acrylic acid grafting modification.

[0026] (3) Paraffin oil is used as a bonding dust suppressant to play the role of bonding and covering dust during the dust suppression process.

[0027] (4) The present invention uses the condensing dust suppressant gelatin-modified gum arabic as the wall material, and introduces the adhesive dust suppressant paraffin oil as the core material through microencapsulation technology, thereby increasing the adhesion to dust, prolonging the moisture absorption and water retention time, and improving the coverage of the solidified layer.

[0028] (5) In view of the randomness and variability of coal dust, the present invention utilizes microcapsule sustained-release technology and uses gelatin-modified gum arabic as the wall material to encapsulate paraffin oil to synthesize composite dust suppression microcapsules, thereby achieving the functional integration optimization of condensing dust suppressants and bonding dust suppressants.

[0029] (6) The composite dust suppression microcapsules break through the single dust suppression mode of traditional dust suppressants and achieve high-efficiency and long-term dust suppression through the combination of dust suppression functions, dust suppression time and dust suppression efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the synergistic action mechanism of the composite dust suppression microcapsules of the present invention.

[0031] Figure 2 This is a flow chart for the preparation of composite dust suppression microcapsules.

[0032] Figure 3 This is the OM diagram of the composite dust suppression microcapsules in Example 1. DETAILED DESCRIPTION

[0033] The present invention will be further described below by way of embodiments and in conjunction with the accompanying drawings:

[0034] Example 1

[0035] A method for preparing dust suppression microcapsules for open-pit coal mines: first, weigh 2.0 g of gum arabic and dissolve it in 100 mL of deionized water, then add 0.20 g of anhydrous sorbitan fatty acid ester emulsifier, heat to 45° C. and stir thoroughly; use a dropping funnel to sequentially add ammonium persulfate initiator (0.10 g, 5 mL of deionized water), acrylamide monomer (1.0 g, 30 mL of deionized water) and N,N-methylenebisacrylamide crosslinking agent (0.20 g, 5 mL of deionized water), and react at 50° C. for 5 hours; finally, wash the reaction solution three times with ethanol to remove unreacted monomers and water, and dry it in a drying oven at 80° C. to obtain a gum arabic-based super absorbent resin dust suppressant, which is crushed for standby use.

[0036] Then, 2.0 g of gelatin was weighed and added to 100 mL of deionized water, the temperature was raised to 45° C. and stirred until fully dissolved, 0.10 g of glyceryl monostearate and 0.10 g of Tween-80 were weighed respectively, and dissolved in 20 mL of deionized water to obtain a composite emulsifier; then the composite emulsifier solution and 2.0 g of paraffin oil were added to the gelatin solution, mixed evenly, and stirred at a high speed until a uniform and stable emulsion was formed.

[0037] Next, add the dried and crushed gum arabic dust suppressant to 200mL deionized water, stir at high speed to form a uniform solution, and transfer to a 500mL three-necked flask. The above emulsion is transferred to a constant pressure funnel, heated at 40°C and added dropwise to the above dust suppressant solution under stirring conditions. The emulsion should be added dropwise within 0.5h, and the stirring rate is greater than 5000rpm. After the addition is completed, continue to react for 1.5h to form a stable water-in-oil emulsion, and then use citric acid (1mol / L) to adjust the pH of the above solution to 3.8. Subsequently, the above solution is cooled to below 10°C with a cold water bath, and glutaraldehyde curing agent (0.8g, 10mL deionized water) is added. After reacting for 0.5h, sodium bicarbonate (1mol / L) is used to adjust the pH to 7.5, continue to stir slowly for 1h, and stand for the microcapsules to settle. Finally, the microcapsule suspension was filtered, washed repeatedly with anhydrous ethanol and deionized water for three times, and freeze-dried to obtain composite dust suppression microcapsules for open-pit coal mines.

[0038] Example 2

[0039] A method for preparing dust suppression microcapsules for open-pit coal mines: first, weigh 2.0 g of gum arabic and dissolve it in 100 mL of deionized water, then add 0.16 g of anhydrous sorbitan fatty acid ester emulsifier, heat to 45° C. and stir thoroughly; use a dropping funnel to sequentially add ammonium persulfate initiator (0.04 g, 5 mL of deionized water), acrylamide monomer (0.6 g, 30 mL of deionized water) and N,N-methylenebisacrylamide crosslinking agent (0.04 g, 5 mL of deionized water), and react at 70° C. for 3 hours; finally, wash the reaction solution three times with ethanol to remove unreacted monomers and water, and dry it in a drying oven at 80° C. to obtain a gum arabic-based super absorbent resin dust suppressant, which is crushed for standby use.

[0040] Then, 2.0 g of gelatin was weighed and added to 200 mL of deionized water, and the temperature was raised to 45° C. and stirred until fully dissolved; 0.04 g of glyceryl monostearate and 0.04 g of Tween-80 were weighed respectively and dissolved in 20 mL of deionized water to obtain a composite emulsifier; then the composite emulsifier solution and 1.0 g of paraffin oil were added to the gelatin solution, mixed evenly, and stirred at a high speed until a uniform and stable emulsion was formed.

[0041] Next, the dried and crushed gum arabic dust suppressant was added to 200 mL of deionized water, stirred mechanically at high speed to form a uniform solution, and transferred to a 500 mL three-necked flask; the emulsion was transferred to a constant pressure funnel, heated at 60 ° C and added dropwise to the dust suppressant solution under stirring conditions, and the reaction was continued for 0.5 h after the dropwise addition was completed to form a stable water-in-oil emulsion, and then the pH of the solution was adjusted to 4.5 with citric acid (1 mol / L). Subsequently, the solution was cooled to below 10 ° C with a cold water bath, glutaraldehyde curing agent (1.0 g, 10 mL of deionized water) was added, and after reacting for 0.5 h, sodium bicarbonate (1 mol / L) was used to adjust the pH to 8.5, and continued to stir slowly for 1 h, and stood for the microcapsules to settle. Finally, the microcapsule suspension was filtered, washed repeatedly with anhydrous ethanol and deionized water for 3 times, and freeze-dried to obtain composite dust suppression microcapsules for open-pit coal mines.

[0042] Example 3

[0043] A method for preparing dust suppression microcapsules for open-pit coal mines: first, weigh 2.0 g of gum arabic and dissolve it in 100 mL of deionized water, then add 0.24 g of anhydrous sorbitan fatty acid ester emulsifier, heat to 45° C. and stir thoroughly; use a dropping funnel to sequentially add ammonium persulfate initiator (0.12 g, 5 mL of deionized water), acrylamide monomer (1.2 g, 30 mL of deionized water) and N,N-methylenebisacrylamide crosslinking agent (0.24 g, 5 mL of deionized water), and react at 50° C. for 10 hours; finally, wash the reaction solution three times with ethanol to remove unreacted monomers and water, and dry it in a drying oven at 80° C. to obtain a gum arabic-based super absorbent resin dust suppressant, which is crushed for standby use.

[0044] Then, 2 g of gelatin was weighed and added to 100 mL of deionized water, the temperature was raised to 45°C and stirred until fully dissolved; 0.05 g of glyceryl monostearate and 0.05 g of Tween-80 were weighed respectively and dissolved in 20 mL of deionized water to obtain a composite emulsifier; then the composite emulsifier solution and 3 g of paraffin oil were added to the gelatin solution, mixed evenly and stirred at high speed until a uniform and stable emulsion was formed.

[0045] Next, add the dried and crushed gum arabic dust suppressant to 200mL deionized water, stir at high speed to form a uniform solution, and transfer to a 500mL three-necked flask; transfer the emulsion to a constant pressure funnel, heat at 30°C and add dropwise to the dust suppressant solution under stirring conditions, continue to react for 2h after the addition is complete, form a stable water-in-oil emulsion, and then use citric acid (1mol / L) to adjust the pH of the solution to 4.0. Subsequently, cool the solution to below 10°C with a cold water bath, add glutaraldehyde curing agent (0.5g, 10mL deionized water), react for 0.5h, adjust the pH to 8.0 with sodium bicarbonate (1mol / L), continue to stir slowly for 1h, and let stand for microcapsule sedimentation. Finally, filter the microcapsule suspension, wash the obtained microcapsule product repeatedly with anhydrous ethanol and deionized water for 3 times, and freeze-dry the composite dust suppression microcapsules.

[0046] The technical effects of the present invention are described in detail below in conjunction with microcapsule performance tests:

[0047] The final product of Example 1 was mixed with water and sprayed on the surface of the coal dust in the culture dish, and the same mass of water was sprayed as a control. Using the tunnel simulation device of the State Key Laboratory of Shandong University of Science and Technology, using TDI8000-0750G-4T stepless inverter and SZ-11.2 axial flow fan, 5m / s, 6m / s, 7m / s, 8m / s, 9m / s, 10m / s, 11m / s, 12m / s different wind speeds were simulated, and the dust suppression effect was determined by calculating the mass loss rate after blowing for 20 minutes. The experimental results are shown in Table 1.

[0048] The final product of Example 2 was subjected to a water retention test. A certain mass of coal sample was placed in a culture dish, a certain mass of microcapsules were added, and a certain mass of water was added and placed for a period of time, then placed in an oven at 30°C for evaporation, and weighed every 0.5 hours to obtain the water loss weight of the microcapsules, and a water retention curve at 30°C was prepared. The experimental results are shown in Table 2.

[0049] The final product of Example 3 was subjected to a degradability test, and soil from the open-pit coal mine was taken and passed through a 20-mesh grading sieve to remove impurities for later use. The composite dust suppression microcapsules were mixed with soil and coal slag in a ratio of 1:1:1 and spread flat in a culture dish, which was stored under natural conditions, and the mass change was recorded. The degradation was calculated and analyzed, and the experimental results are shown in Table 3.

[0050] Table 1 Analysis of dust suppression efficiency of composite dust suppression microcapsules

[0051]

[0052] Table 2 Analysis of water retention performance of composite dust suppression microcapsules

[0053]

[0054] Table 3 Degradation performance analysis of composite dust suppression microcapsules

[0055]

[0056]

[0057] Table 1 shows the dust suppression effects of water and composite dust suppression microcapsule dust suppressant at different circulating wind speeds. When the wind speed is low, the composite dust suppression microcapsule dust suppressant can effectively control the loss of coal dust. It can be seen that the composite dust suppression microcapsule dust suppressant can effectively reduce the generation of dust in open-pit coal mines at low wind speeds. Water can play a certain dust suppression role, but it still produces mass loss at low wind speeds. The dust suppression effect of water is poor at low wind speeds. As the wind speed gradually increases, within the wind speed range of 7m / s-12m / s, the dust suppression effect of spraying dust suppression microcapsules is superior. The mass loss of microcapsule dust suppressant at a high wind speed of 12m / s is only 6.5%, which is significantly higher than the dust suppression effect of spraying water. In the sample sprayed with water, the mass loss of coal dust gradually increases at high wind speeds, and the dust suppression effect is poor. The mass loss reaches 43.7% at a wind speed of 12m / s.

[0058] Table 2 shows the mass loss of the composite dust suppression microcapsules after absorbing water on coal dust. The wall material of the microcapsules has a certain swelling capacity. The water evaporates slowly at room temperature. When the microcapsules are sprinkled in the coal powder, a part of the microcapsules after absorbing water and the slowly released paraffin oil can penetrate to the bottom of the coal cake and cannot experience wind erosion. Therefore, the water evaporates slowly. After 12 hours of wind erosion and drying at room temperature, the water loss mass is only 29.7g. This shows that the microcapsules have a certain water retention performance, which can effectively guarantee the action time and effect of the microcapsules.

[0059] Table 3 is the degradation rate of the composite dust suppression microcapsules. It can be seen from the table that the dust suppression microcapsules in the culture dish degrade at room temperature, gradually lose water and degrade within ten days after spraying, resulting in mass loss. After the 28th day, the biological decomposition is basically completed, and the degradation rate is about 32%. The composite dust suppression microcapsules for open-pit coal mines have a certain degree of degradability, which can reduce the impact on the surrounding environment of the open-pit coal mine while suppressing dust.

[0060] The present invention is not limited to the above-mentioned embodiments. Those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and purpose of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for preparing composite dust suppression microcapsules for open-pit coal mines, characterized in that: The Arabic gum is used as a skeleton and acrylamide is used as a monomer, and a Arabic gum-based super absorbent resin dust suppressant is synthesized by free radical solution polymerization; then, paraffin oil is used as a core material and gelatin-Arabic gum-based super absorbent resin dust suppressant is used as a wall material, and the paraffin oil is coated by a complex coacervation method by means of the electrostatic condensation of the two, thereby synthesizing a composite dust suppression microcapsule; the preparation is carried out according to the following steps: Step 1, preparation of gum arabic based super absorbent dust suppressant, adding gum arabic into deionized water, then adding emulsifier, heating to 45°C and stirring fully, adding ammonium persulfate initiator, acrylamide monomer and N,N-methylenebisacrylamide crosslinker in sequence with a dropping funnel, reacting at 50-70°C for 3-10 h; finally, washing the reaction solution with ethanol to remove unreacted monomer and water, drying to obtain gum arabic based super absorbent dust suppressant, crushing for standby use; Step 2: Add gelatin to deionized water, heat to 45°C and stir until fully dissolved; mix glyceryl monostearate and Tween-80 in a certain mass ratio to obtain a composite emulsifier; then add the composite emulsifier and paraffin oil to the gelatin solution, mix well and stir at a high speed until a uniform and stable emulsion is formed; Step 3, adding the dried and crushed gum arabic-based super absorbent dust suppressant into deionized water, stirring at high speed mechanically to form a uniform dust suppressant solution, and setting aside; heating the emulsion of step 2 at 30-60° C. and adding dropwise to the dust suppressant solution under stirring conditions, and continuing the reaction for 0.5-2 h after the dropwise addition is completed to form a stable oil-in-water emulsion, and then adjusting the pH value of the solution to 3.5-4.5 with an acidic pH regulator; Step 4: cool the solution to below 10°C with a cold water bath, add a curing agent, react for 0.5 h, then adjust the pH value to 6.0-8.5 with an alkaline pH adjuster, continue to stir slowly for 0.5-3 h, and then let stand for the microcapsules to settle; Step 5: After filtering the microcapsule suspension, the obtained microcapsule product is repeatedly washed three times with anhydrous ethanol and deionized water, and freeze-dried to obtain composite dust suppression microcapsules for open-pit coal mines.

2. The method for preparing the composite dust suppression microcapsules for open-pit coal mines according to claim 1, characterized in that: The acidic pH regulator is citric acid, and the alkaline pH regulator is sodium bicarbonate.

3. The method for preparing composite dust suppression microcapsules for open-pit coal mines according to claim 2, characterized in that: In the preparation process of the gum arabic-based super absorbent resin dust suppressant, the emulsifier is sorbitan fatty acid ester.

4. The method for preparing composite dust suppression microcapsules for open-pit coal mines according to claim 3, characterized in that: In step 1, the amount of emulsifier added is 8%-12% of the amount of gum arabic added, the amount of initiator added is 2%-6% of the amount of gum arabic added, the amount of acrylamide monomer added is 30%-60% of the amount of gum arabic added, and the amount of cross-linking agent added is 2%-12% of the amount of gum arabic added.

5. The method for preparing composite dust suppression microcapsules for open-pit coal mines according to claim 1, characterized in that: During the synthesis of microcapsules, the curing agent is glutaraldehyde.

6. The method for preparing composite dust suppression microcapsules for open-pit coal mines according to claim 5, characterized in that: The total amount of stearyl glyceryl and Tween-80 added is 4%-10% of the amount of gelatin added, and the amount of paraffin oil added is 50%-150% of the amount of gelatin added.

7. The method for preparing composite dust suppression microcapsules for open-pit coal mines according to claim 6, characterized in that: In step 3, in the process of adding the emulsion to the dust suppressant solution using a constant pressure dropping funnel, in order to ensure the uniformity of the microcapsule size, the emulsion must be added within 0.5 h and the stirring rate must be greater than 5000 rpm.

8. Composite dust suppression microcapsules for open-pit coal mines prepared by the method for preparing composite dust suppression microcapsules for open-pit coal mines according to any one of claims 1 to 7.

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