A method for fractional electroflotation separation of macerals in coal

Abstract

The present invention discloses a method for fractional electroflotation separation of macerals in coal, which includes: Step 1, providing a coal slurry; Step 2, placing the coal slurry in a modification pretreatment tank of an integrated electrochemically reduction modification - electrolytic flotation separation system; Step 3, adding an electrolyte solution into the electroflotation cell until the salt bridge is submerged; Step 4, starting the power supply, applying electricity to the modification pretreatment tank and the electroflotation cell to carry out a modification pretreatment reaction; Step 5, feeding the modified pretreatment system into a flotation preparation tank, adding flotation preparation additives to obtain a flotation preparation, and stirring the flotation preparation; Step 6, feeding the stirred system into the electroflotation cell for flotation separation. When using the method of the present invention for separating raw coal, the yield of the float and the inertinite content of the sink are significantly increased, the yield of the sink is significantly decreased, and the comprehensive separation efficiency is significantly improved. It has the characteristics of significantly improving the floatability of macerals in coal and enhancing the separation and enrichment effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal and rock separation, and particularly relates to a method for separating and grading coal macerals by electroflotation. Background Art

[0002] According to coal petrology, the organic macerals of coal can be divided into vitrinite, inertinite and exinite. The composition and content of coal macerals are one of the key factors affecting coal processing and conversion. The processing and conversion efficiencies of different macerals are different, and their industrial values and application directions are also different. Separating to obtain relatively enriched coal macerals is one of the ways to achieve efficient quality-based conversion of coal.

[0003] The flotation separation technology is one of the important methods for separating coal macerals. It separates based on the floatability differences of different macerals. Currently, the following difficulties mainly exist in this technology:

[0004] First, the stability of the flotation effect is poor. The floatability differences of various coal macerals are small, the variable range of separation conditions is narrow, it is difficult to control in the actual application process, and the separation effect is difficult to be stable.

[0005] Second, it is difficult to balance the recovery rate and the enrichment rate of macerals, that is, it is very difficult to improve the separation efficiency while ensuring the recovery rate.

[0006] Third, the dissociation of coal macerals is insufficient, resulting in the difficulty of improving the separation effect. The insufficient dissociation of macerals in coal particles during flotation is an important reason for the difficulty in improving the enrichment rate. Theoretically, the particle size for sufficient dissociation of macerals is -10μm, far exceeding the particle size lower limit of traditional flotation.

[0007] Therefore, solving the problems of small floatability differences of coal macerals and flotation of fine-grained coal is one of the key links to improve the separation effect of coal macerals. Providing a method that can effectively expand the floatability differences of macerals is the key to solving the current problems.

[0008] In addition to small floatability differences, another bottleneck problem in the separation of coal macerals lies in the flotation of ultrafine coal with a particle size range of <74μm. It is very difficult to effectively and selectively separate fine particles or ultrafine particles from ultrafine coal flotation by traditional foam flotation method, resulting in the fact that the separation effect of ultrafine coal flotation is often not very high. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to provide a method for separating raw coal by an integrated electrochemical reduction modification - electroflotation separation system including a modified pretreatment tank, a flotation preparation tank, an electroflotation tank and a power source, aiming at the deficiencies of the above - mentioned prior art. The yield of float and the inertinite content of sink are significantly increased, the yield of sink is significantly decreased, and the comprehensive separation efficiency is significantly improved. It has the characteristics of significantly improving the floatability of coal macerals and enhancing the separation and enrichment effect.

[0010] To solve the above - mentioned technical problems, the technical solution adopted by the present invention is: a method for fractional electroflotation separation of coal macerals, which is characterized by including:

[0011] Step 1: Add water to the raw coal to make a slurry and adjust the pH to 2.0 - 7.0 to obtain a coal slurry.

[0012] Step 2: Place the coal slurry obtained in Step 1 in the modified pretreatment tank of the integrated electrochemical reduction modification - electroflotation separation system; the integrated electrochemical reduction modification - electroflotation separation system includes a modified pretreatment tank, a flotation preparation tank, an electroflotation tank and a power source, and a salt bridge for electron exchange is connected between the modified pretreatment tank and the electroflotation tank.

[0013] Step 3: Add an electrolyte solution to the electroflotation tank until the salt bridge is submerged; the electrolyte in the electrolyte solution is potassium sulfate, sodium sulfate or sulfuric acid.

[0014] Step 4: Start the power source, apply electricity to the modified pretreatment tank and the electroflotation tank, and carry out a modified pretreatment reaction under the conditions of a voltage of 3V - 60V and a current of 1A - 10.5A.

[0015] Step 5: Feed the system after modified pretreatment into the flotation preparation tank, add flotation preparation additives to obtain a flotation preparation material, and stir the flotation preparation material.

[0016] Step 6: Feed the system after stirring in Step 5 into the electroflotation tank for flotation separation.

[0017] In the above - mentioned method for fractional electroflotation separation of coal macerals, in Step 1, the raw coal is raw coal crushed and ground to a particle size of <0.074mm, the concentration of the coal slurry is 10g / L - 70g / L, and the regulator used for adjusting the pH is sulfuric acid or sodium hydroxide.

[0018] In the above - mentioned method for fractional electroflotation separation of coal macerals, in Step 2, in the integrated electrochemical reduction modification - electroflotation separation system, the modified pretreatment tank is provided with a pretreatment tank feed inlet, a pretreatment tank discharge outlet and a pretreatment tank reflux inlet.

[0019] The flotation preparation tank is provided with a flotation preparation feed inlet and a flotation preparation discharge outlet;

[0020] The discharge outlet of the pretreatment tank is communicated with both the flotation preparation feed inlet and the pretreatment tank reflux inlet. A first valve is arranged on the pipeline connecting the discharge outlet of the pretreatment tank and the pretreatment tank reflux inlet, and a second valve is arranged on the pipeline connecting the discharge outlet of the pretreatment tank and the flotation preparation feed inlet;

[0021] The electroflotation cell is provided with an electroflotation feed inlet, an electroflotation float outlet and an electroflotation sediment outlet;

[0022] The flotation preparation discharge outlet is communicated with the electroflotation feed inlet;

[0023] A modified pretreatment electrode group is arranged in the modified pretreatment tank, and an electroflotation electrode group is arranged in the electroflotation cell.

[0024] For the above-mentioned method for fractional electroflotation separation of coal maceral components, it is characterized in that the discharge outlet of the pretreatment tank is located at the bottom of the modified pretreatment tank, the feed inlet of the pretreatment tank and the reflux inlet of the pretreatment tank are located at the upper side of the modified pretreatment tank, and the feed inlet of the pretreatment tank is higher than the reflux inlet of the pretreatment tank.

[0025] For the above-mentioned method for fractional electroflotation separation of coal maceral components, it is characterized in that the flotation preparation feed inlet is located at the upper part of the flotation preparation tank, and the flotation preparation discharge outlet is located at the lower part of the flotation preparation tank.

[0026] For the above-mentioned method for fractional electroflotation separation of coal maceral components, it is characterized in that the electroflotation sediment outlet is located at the lower part of the electroflotation cell, the electroflotation float outlet is located at the upper part of the electroflotation cell, and the electroflotation feed inlet is located at the upper side of the electroflotation cell.

[0027] For the above-mentioned method for fractional electroflotation separation of coal maceral components, it is characterized in that all the modified pretreatment electrodes in the modified pretreatment electrode group are flat electrodes, the material of the modified pretreatment electrodes is graphite, iron, aluminum or copper, and the number of the modified pretreatment electrodes is 2 to 20; all the electroflotation electrodes in the electroflotation electrode group are flat electrodes, the material of the electroflotation electrodes is graphite, nickel or titanium, and the number of the electroflotation electrodes is 2 to 20; the area of the modified pretreatment electrodes > the area of the electroflotation electrodes.

[0028] For the above-mentioned method for fractional electroflotation separation of coal maceral components, it is characterized in that in step three, the concentration of the electrolyte solution is 1 mol / L to 10 mol / L; in step four, the modified pretreatment time is 15 min to 180 min.

[0029] The above-mentioned method for fractional electroflotation separation of macerals in coal is characterized in that, in step five, the stirring rate of the stirring treatment is 60-120 r / min, and the stirring time is 5-30 min; in step five, the additives for flotation preparation include a pH regulator, a foaming agent, and a collector. The pH regulator is sulfuric acid or sodium hydroxide, the pH of the flotation preparation is 3.0-5.0, the foaming agent is polyethylene glycol, the addition amount of the foaming agent is 0-50 g per ton of raw coal, the collector is kerosene, oleic acid or dodecyl trimethyl ammonium bromide, and the addition amount of the collector is 100 g-1000 g per ton of raw coal.

[0030] The above-mentioned method for fractional electroflotation separation of macerals in coal is characterized in that, in step six, the flotation time is 10 min-60 min; the flotation separation in step six includes the overflow of the floating matter from the electroflotation cell and the discharge of the sinking matter from the electroflotation cell.

[0031] The present invention has the following advantages compared with the prior art:

[0032] 1. The method of the present invention for separating raw coal through an integrated electrochemical reduction modification - electrolytic flotation separation system including a modified pretreatment tank, a flotation preparation tank, an electroflotation cell, and a power supply significantly improves the yield of floating matter and the inertinite content of sinking matter, significantly reduces the yield of sinking matter, and significantly improves the overall separation efficiency. It has the characteristics of significantly improving the floatability of macerals in coal and enhancing the separation and enrichment effect.

[0033] 2. The method of the present invention modifies the oxygen-containing functional groups on the coal surface through modified pretreatment, changes its surface oxygen content and the composition of oxygen-containing functional groups, and then improves the wettability of coal, thereby significantly improving the floatability of macerals in coal.

[0034] 3. The method of the present invention specifically solves the problem of poor flotation effect of ultrafine coal. It effectively solves the defect that due to the small particle size of ultrafine coal particles, small inertial force, and the tendency to move along the liquid streamline around the bubbles, the probability of collision with the bubbles is relatively low. It has the characteristics of finer electroflotation bubbles and a higher probability of collision with ultrafine coal particles.

[0035] 4. In the system of the method of the present invention, the electrochemical anode and cathode are separated. The cathode is used for the electrochemical reduction modification pretreatment of the coal sample, and the anode is used to complete the electroflotation separation. The separation effect is easy to control.

[0036] 5. During the modified pretreatment of the coal slurry in the present invention, the electrochemical reduction modifies the coal slurry and electrolyzes water simultaneously. The high-purity hydrogen generated by the electrolysis of water can be recovered and collected. The system of the present invention can co-produce high-purity green hydrogen by-products.

[0037] 6. The process flow of the method of the present invention is relatively simple and is easy to be popularized and applied.

[0038] The following combines the drawings and embodiments to make a further detailed description of the technical solution of the present invention.

[0039] Explanation of the drawings

[0040] Figure 1 It is a schematic structural diagram of the integrated separation system of electrochemical reduction modification - electroflotation for Example 1.

[0041] Explanation of the reference numerals

[0042] 1 - Modified pretreatment tank; 11 - Inlet of the pretreatment tank; 12 - Outlet of the pretreatment tank;

[0043] 13 - Return inlet of the pretreatment tank; 14 - Modified pretreatment electrode group; 2 - Flotation preparation tank;

[0044] 21 - Inlet of the flotation preparation; 22 - Outlet of the flotation preparation; 3 - Electroflotation cell;

[0045] 31 - Inlet of the electroflotation; 32 - Outlet of the electroflotation float; 33 - Outlet of the electroflotation sediment;

[0046] 34 - Electroflotation electrode group; 4 - Power supply; 5 - Salt bridge;

[0047] 61 - First valve; 62 - Second valve. Detailed implementation manners

[0048] Example 1

[0049] This example provides an integrated separation system of electrochemical reduction modification - electroflotation. As Figure 1 shown, the integrated separation system of electrochemical reduction modification - electroflotation includes a modified pretreatment tank 1, a flotation preparation tank 2, an electroflotation cell 3 and a power supply 4;

[0050] A salt bridge 5 for electron exchange is connected between the modified pretreatment tank 1 and the electroflotation cell 3;

[0051] The modified pretreatment tank 1 is provided with an inlet 11 of the pretreatment tank, an outlet 12 of the pretreatment tank and a return inlet 13 of the pretreatment tank. The outlet 12 of the pretreatment tank is located at the bottom of the modified pretreatment tank 1. The inlet 11 of the pretreatment tank and the return inlet 13 of the pretreatment tank are located on the upper side of the modified pretreatment tank 1, and the inlet 11 of the pretreatment tank is higher than the return inlet 13 of the pretreatment tank;

[0052] The flotation preparation tank 2 is provided with a flotation preparation feed inlet 21 and a flotation preparation discharge outlet 22. The flotation preparation feed inlet 21 is located at the upper part of the flotation preparation tank 2, and the flotation preparation discharge outlet 22 is located at the lower part of the flotation preparation tank 2;

[0053] The pretreatment tank discharge outlet 12 is communicated with both the flotation preparation feed inlet 21 and the pretreatment tank reflux inlet 13. A first valve 61 is arranged on the pipeline connecting the pretreatment tank discharge outlet 12 and the pretreatment tank reflux inlet 13, and a second valve 62 is arranged on the pipeline connecting the pretreatment tank discharge outlet 12 and the flotation preparation feed inlet 21; The flow direction of the discharge from the modified pretreatment tank 1 is controlled by the first valve 61 and the second valve 62;

[0054] The electroflotation cell 3 is provided with an electroflotation feed inlet 31, an electroflotation float outlet 32 and an electroflotation sediment outlet 33. The electroflotation sediment outlet 33 is located at the lower part of the electroflotation cell 3, the electroflotation float outlet 32 is located at the upper part of the electroflotation cell 3, and the electroflotation feed inlet 31 is located at the upper side part of the electroflotation cell 3;

[0055] The flotation preparation discharge outlet 22 is communicated with the electroflotation feed inlet 31;

[0056] The modified pretreatment tank 1 is provided with a modified pretreatment electrode group 14. The modified pretreatment electrodes in the modified pretreatment electrode group 14 are all flat electrodes. The material of the modified pretreatment electrodes is graphite, iron, aluminum or copper, and the number of the modified pretreatment electrodes is 2 to 20;

[0057] The electroflotation cell 3 is internally provided with an electroflotation electrode group 34. The electroflotation electrodes in the electroflotation electrode group 34 are all flat electrodes. The material of the electroflotation electrodes is graphite, nickel or titanium, and the number of the electroflotation electrodes is 2 to 20;

[0058] The area of the modified pretreatment electrode > the area of the electroflotation electrode; The area of the modified pretreatment electrode is larger to ensure effective electrochemical modification treatment; The area of the electroflotation electrode is slightly smaller to generate bubbles;

[0059] The lower end of the salt bridge 5 is higher than the upper end of the electroflotation electrode, and the upper end of the salt bridge 5 is lower than the upper end of the modified pretreatment electrode;

[0060] The modified pretreatment electrode group 14 and the electroflotation electrode group 34 are respectively connected to the power supply 4.

[0061] Example 2

[0062] This example provides a method for the fractional electroflotation separation of coal macerals by using the electrochemical reduction modification - electroflotation integration separation system described in Example 1, including:

[0063] Step 1: Prepare coal slurry, specifically including: adjusting the pH of the raw coal to 7.0 with an adjuster after adding water to form a slurry to obtain the coal slurry; the raw coal is raw coal crushed and ground to a particle size of <0.074 mm; the concentration of the coal slurry is 10 g / L; the adjuster is sulfuric acid or sodium hydroxide;

[0064] Step 2: Place the coal slurry in Step 1 into the modified pretreatment tank 1; the material of the modified pretreatment electrode is graphite, and the number is 2; the material of the electroflotation electrode is graphite, and the number is 2;

[0065] Step 3: Add an electrolyte solution to the electroflotation cell 3 until the salt bridge 5 is submerged; the electrolyte in the electrolyte solution is sodium sulfate, and the concentration of the electrolyte solution is 1.0 mol / L;

[0066] Step 4: Start the power supply, apply electricity to the modified pretreatment tank 1 and the electroflotation cell 3, and carry out the modified pretreatment reaction under the conditions of a voltage of 40 V and a current of 1.2 A. During the reaction process, the first valve 61 of the modified pretreatment tank 1 remains open, and the second valve 62 remains closed; the modified pretreatment time is 15 min; the hydrogen generated during the modified pretreatment reaction can be collected through the gas outlet of the modified pretreatment tank 1;

[0067] Step 5: Close the first valve 61, open the second valve 62, introduce the system after modified pretreatment into the flotation preparation tank 2, and add flotation preparation additives to the system after modified pretreatment in the flotation preparation tank 2. The flotation preparation additives include a pH regulator and a collector to obtain a flotation preparation. At room temperature, stir the flotation preparation at a rotation speed of 60 r / min for 30 min; the pH regulator is sulfuric acid or sodium hydroxide, and the pH of the flotation preparation is 4.0; the collector is kerosene, and the addition amount of the collector is 100 g per ton of raw coal; the room temperature is 20 ± 5°C;

[0068] Step 6: Send the system after stirring in Step 5 into the electroflotation cell 3 for flotation separation; the floating matter overflows from the electroflotation floating matter outlet 32, and the sinking matter is discharged through the electroflotation sinking matter outlet 33. The flotation time can be 15 min; or according to the actual situation, after the system runs stably, continuous feeding and discharging methods can be adopted for operation.

[0069] Example 3

[0070] This example provides a method for fractional electroflotation separation of coal macerals using the electrochemical reduction modification - electroflotation integrated separation system described in Example 1, including:

[0071] Step 1: Prepare coal slurry, specifically including: adjusting the pH of the raw coal to 2.0 with an adjuster after adding water to form a slurry to obtain the coal slurry; the raw coal is the raw coal crushed and ground to a particle size of <0.074 mm; the concentration of the coal slurry is 70 g / L; the adjuster is sulfuric acid;

[0072] Step 2: Place the coal slurry described in Step 1 into the modified pretreatment tank 1; the material of the modified pretreatment electrode is aluminum, and the number is 10; the material of the electroflotation electrode is nickel, and the number is 15;

[0073] Step 3: Add an electrolyte solution to the electroflotation cell 3 until the salt bridge is submerged; the electrolyte in the electrolyte solution is potassium sulfate, and the concentration of the electrolyte solution is 10 mol / L;

[0074] Step 4: Start the power supply, apply electricity to the modified pretreatment tank 1 and the electroflotation cell 3, and carry out the modified pretreatment reaction under the conditions of a voltage of 60 V and a current of 10.5 A. During the reaction process, the first valve 61 of the modified pretreatment tank 1 remains open, and the second valve 62 remains closed; the modified pretreatment time is 40 min;

[0075] Step 5: Close the first valve 61, open the second valve 62, introduce the modified pretreatment system into the flotation preparation tank 2, and add flotation preparation additives to the modified pretreatment system in the flotation preparation tank 2. The flotation preparation additives include a pH regulator, a foaming agent, and a collector to obtain a flotation preparation. At room temperature, stir the flotation preparation at a rotation speed of 120 r / min for 5 min; the pH regulator is sulfuric acid or sodium hydroxide, the pH of the flotation preparation is 3.0, the foaming agent is polyethylene glycol, the addition amount of the foaming agent is 50 g per ton of raw coal; the collector is dodecyl trimethyl ammonium bromide, and the addition amount of the collector is 500 g per ton of raw coal; the molecular weight of the polyethylene glycol is 400;

[0076] Step 6: Send the system after stirring in Step 5 into the electroflotation cell 3 for flotation separation; the floating matter overflows from the electroflotation floating matter outlet 32, and the sinking matter is discharged through the electroflotation sinking matter outlet 33. The flotation time is 25 min.

[0077] Example 4

[0078] This example provides a method for fractional electroflotation separation of coal macerals using the electrochemical reduction modification - electroflotation integrated separation system described in Example 1, including:

[0079] Step 1: Prepare coal slurry, specifically including: adjusting the pH of the raw coal to 3.0 with an adjuster after adding water to form a slurry to obtain the coal slurry; the raw coal is the raw coal crushed and ground to a particle size of <0.074 mm; the concentration of the coal slurry is 50 g / L; the adjuster is sulfuric acid;

[0080] Step 2: Place the coal slurry described in Step 1 into the modified pretreatment tank 1; the material of the modified pretreatment electrode is iron, and the number is 20; the material of the electroflotation electrode is graphite, and the number is 20;

[0081] Step 3: Add an electrolyte solution to the electroflotation cell 3 until the salt bridge is submerged; the electrolyte in the electrolyte solution is sodium sulfate, and the concentration of the electrolyte solution is 2.5 mol / L;

[0082] Step 4: Start the power supply, apply electricity to the modified pretreatment tank 1 and the electroflotation cell 3, and carry out the modified pretreatment reaction under the conditions of a voltage of 3.0 V and a current of 1.0 A. During the reaction process, the first valve 61 of the modified pretreatment tank 1 remains open, and the second valve 62 remains closed; the modified pretreatment time is 180 min;

[0083] Step 5: Close the first valve 61, open the second valve 62, introduce the modified pretreatment system into the flotation preparation tank 2, and add flotation preparation additives to the modified pretreatment system in the flotation preparation tank 2. The flotation preparation additives include a pH regulator, a foaming agent, and a collector to obtain a flotation preparation. At room temperature, stir the flotation preparation at a rotation speed of 105 r / min for 15 min; the pH regulator is sulfuric acid or sodium hydroxide, the pH of the flotation preparation is 5.0, the foaming agent is polyethylene glycol, the addition amount of the foaming agent is 20 g per ton of raw coal; the collector is oleic acid, and the addition amount of the collector is 1000 g per ton of raw coal; the molecular weight of the polyethylene glycol is 400;

[0084] Step 6: Send the system stirred in Step 5 into the electroflotation cell 3 for flotation separation; the floating matter overflows from the electroflotation floating matter outlet 32, and the sinking matter is discharged through the electroflotation sinking matter outlet 33. The flotation time is 60 min.

[0085] Example 5

[0086] This example provides a method for fractional electroflotation separation of coal macerals using the electrochemically reduced modification - electroflotation integrated separation system described in Example 1, including:

[0087] Step 1: Prepare the coal slurry, specifically including: adding water to the raw coal for pulp making and then using an adjusting agent to adjust the pH to 5.0 to obtain the coal slurry; the raw coal is the raw coal crushed and ground to a particle size of <0.074 mm; the concentration of the coal slurry is 40 g / L; the adjusting agent is sulfuric acid;

[0088] Step 2: Place the coal slurry described in Step 1 into the modified pretreatment tank 1; the material of the modified pretreatment electrode is iron, and the number is 10; the material of the electroflotation electrode is graphite, and the number is 5;

[0089] Step 3: Add the electrolyte solution into the electroflotation cell 3 until the salt bridge is submerged; the electrolyte in the electrolyte solution is sulfuric acid, and the concentration of the electrolyte solution is 1 mol / L;

[0090] Step 4: Start the power supply, apply electricity to the modified pretreatment tank 1 and the electroflotation cell 3, and carry out the modified pretreatment reaction under the conditions of a voltage of 20 V and a current of 7.5 A. During the reaction process, the first valve 61 of the modified pretreatment tank 1 remains open, and the second valve 62 remains closed; the modified pretreatment time is 50 min;

[0091] Step 5: Close the first valve 61, open the second valve 62, introduce the system after modified pretreatment into the flotation preparation tank 2, and add flotation preparation additives to the system after modified pretreatment in the flotation preparation tank 2. The flotation preparation additives include a pH regulator, a foaming agent, and a collector to obtain the flotation preparation. Under room temperature conditions, stir the flotation preparation at a rotation speed of 80 r / min for 20 min; the pH regulator is sulfuric acid or sodium hydroxide, the pH of the flotation preparation is 3.0, the foaming agent is polyethylene glycol, the addition amount of the foaming agent is 30 g per ton of raw coal; the collector is kerosene, and the addition amount of the collector is 500 g per ton of raw coal; the molecular weight of the polyethylene glycol is 400;

[0092] Step 6: Feed the system after stirring in Step 5 into the electroflotation cell 3 for flotation separation; the floating matter overflows from the electroflotation floating matter outlet 32, and the sinking matter is discharged through the electroflotation sinking matter outlet 33. The flotation time is 10 min.

[0093] Comparative Example

[0094] This comparative example provides a method for directly performing electroflotation separation on raw coal without modified pretreatment, including:

[0095] Step 1: Prepare the coal slurry, specifically including: adding water to the raw coal for pulp making and then using an adjusting agent to adjust the pH to 7.0 to obtain the coal slurry; the raw coal is the raw coal crushed and ground to a particle size of <0.074 mm; the concentration of the coal slurry is 10 g / L; the adjusting agent is sulfuric acid or sodium hydroxide;

[0096] Step 2: Place the coal slurry described in Step 1 into the flotation preparation tank 2 in the integrated electrochemical reduction modification - electroflotation separation system of Example 1; the electroflotation electrodes are made of graphite, and the number is 2.

[0097] Step 3: Add a pH regulator, a foaming agent, and a collector into the flotation preparation tank 2 to obtain a flotation preparation. At room temperature, stir the flotation preparation at a speed of 80 r / min for 20 min; the pH regulator is sulfuric acid or sodium hydroxide, and the pH of the flotation preparation is 4.0; the foaming agent is polyethylene glycol, and the addition amount of the foaming agent is 50 g per ton of raw coal; the collector is kerosene, and the addition amount of the collector is 100 g per ton of raw coal.

[0098] Step 4: Feed the system after being stirred in Step 3 into the electroflotation tank 3. At the same time, add a 1 mol / L sulfuric acid solution into the modification pretreatment tank 1 until the solution completely submerges the electrodes. Start the power supply, adjust the voltage to 40 V, and the current to 1.2 A, and perform electroflotation separation for 15 min.

[0099] Effect evaluation

[0100] The properties of the products after classification electroflotation separation in Examples 2 - 5 are shown in Table 1. It can be seen from Table 1 that by using the method of the present invention for classification electroflotation separation, the comprehensive separation efficiency is significantly higher than that of the comparative example, the yield of the floated matter is significantly increased, and the microscopic component contents of the floated matter and the settled matter are improved to varying degrees, indicating that the method of the present invention can significantly improve the floatability of coal maceral microscopic components and improve the separation and enrichment effect. The microscopic component composition of the raw coal used in Examples 2 - 5 is as follows: vitrinite 56.2%, inertinite 40.1%, exinite 1.1%, mineral matter 2.6%, and the reflectance of vitrinite is 0.638.

[0101] Table 1 Properties of the products after electroflotation separation in Examples 2 - 5 and the comparative example

[0102]

[0103] *Comprehensive separation efficiency = yield of the floated matter × vitrinite content in the floated matter + yield of the settled matter × inertinite content in the settled matter

[0104] The above are only some embodiments of the present invention, and do not impose any limitations on the present invention. Any simple modification, change, and equivalent structural change made to the above embodiments according to the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for fractional electroflotation separation of macerals in coal and rock, characterized in that, Including: Step 1: Adjust the pH of the raw coal to 2.0 - 7.0 after adding water to form a slurry to obtain a coal slurry; Step 2: Place the coal slurry described in Step 1 into the modification pretreatment tank (1) of the integrated electrochemical reduction modification - electroflotation separation system; the integrated electrochemical reduction modification - electroflotation separation system includes a modification pretreatment tank (1), a flotation preparation tank (2), an electroflotation tank (3), and a power supply (4), and a salt bridge (5) for electron exchange is connected between the modification pretreatment tank (1) and the electroflotation tank (3); Step 3: Add an electrolyte solution to the electroflotation tank (3) until the salt bridge is submerged; the electrolyte in the electrolyte solution is potassium sulfate, sodium sulfate, or sulfuric acid; Step 4: Start the power supply, apply electricity to the modification pretreatment tank (1) and the electroflotation tank (3), and carry out a modification pretreatment reaction under the conditions of a voltage of 3V - 60V and a current of 1A - 10.5A; Step 5: Feed the system after modification pretreatment into the flotation preparation tank (2), add flotation preparation additives to obtain a flotation preparation material, and stir the flotation preparation material; Step 6: Feed the system after stirring in Step 5 into the electroflotation tank (3) for flotation separation.

2. The method for the fractional electroflotation separation of macerals of coal and rock according to claim 1, wherein, In Step 1, the raw coal is raw coal crushed and ground to a particle size of <0.074mm, the concentration of the coal slurry is 10g / L - 70g / L, and the regulator used to adjust the pH is sulfuric acid or sodium hydroxide.

3. A method for the fractional electroflotation separation of coal macerals according to claim 1 or 2, characterized in that, In Step 2, in the integrated electrochemical reduction modification - electroflotation separation system, a pretreatment tank feed inlet (11), a pretreatment tank discharge outlet (12), and a pretreatment tank reflux inlet (13) are provided on the modification pretreatment tank (1); A flotation preparation feed inlet (21) and a flotation preparation discharge outlet (22) are provided on the flotation preparation tank (2); The pretreatment tank discharge outlet (12) is connected to both the flotation preparation feed inlet (21) and the pretreatment tank reflux inlet (13). A first valve (61) is provided on the pipeline connecting the pretreatment tank discharge outlet (12) and the pretreatment tank reflux inlet (13), and a second valve (62) is provided on the pipeline connecting the pretreatment tank discharge outlet (12) and the flotation preparation feed inlet (21); An electroflotation feed inlet (31), an electroflotation float outlet (32), and an electroflotation sink outlet (33) are provided on the electroflotation tank (3); The flotation preparation discharge outlet (22) is connected to the electroflotation feed inlet (31); A modification pretreatment electrode group (14) is provided in the modification pretreatment tank (1), and an electroflotation electrode group (34) is provided in the electroflotation tank (3).

4. A method for the fractional electroflotation separation of macerals of coal and rock according to claim 3, characterized in that, The pretreatment tank discharge outlet (12) is located at the bottom of the modification pretreatment tank (1), and the pretreatment tank feed inlet (11) and the pretreatment tank reflux inlet (13) are located on the upper side of the modification pretreatment tank (1), and the pretreatment tank feed inlet (11) is higher than the pretreatment tank reflux inlet (13).

5. A method for the fractional electroflotation separation of macerals of coal and rock according to claim 3, characterized in that, The flotation preparation feed inlet (21) is located in the upper part of the flotation preparation tank (2), and the flotation preparation discharge outlet (22) is located in the lower part of the flotation preparation tank (2).

6. The method for the fractional electroflotation separation of coal macerals according to claim 3, wherein, The electroflotation sediment outlet (33) is located at the lower part of the electroflotation cell (3), the electroflotation float outlet (32) is located at the upper part of the electroflotation cell (3), and the electroflotation feed inlet (31) is located at the upper side part of the electroflotation cell (3).

7. A method for fractional electroflotation separation of macerals in coal and rock, according to claim 3, characterized in that In the modified pretreatment electrode group (14), the modified pretreatment electrodes are all flat electrodes. The material of the modified pretreatment electrodes is graphite, iron, aluminum or copper, and the number of the modified pretreatment electrodes is 2 to 20. In the electroflotation electrode group (34), the electroflotation electrodes are all flat electrodes. The material of the electroflotation electrodes is graphite, nickel or titanium, and the number of the electroflotation electrodes is 2 to 20. The area of the modified pretreatment electrodes > the area of the electroflotation electrodes.

8. A method for the fractional electroflotation separation of coal macerals according to claim 1, characterized in that, In step three, the concentration of the electrolyte solution is 1 mol / L to 10 mol / L. In step four, the modified pretreatment time is 15 min to 180 min.

9. The fractional electroflotation separation method of coal macerals according to claim 1, characterized in that, In step five, the stirring rate of the stirring treatment is 60 to 120 r / min, and the stirring time is 5 to 30 min. In step five, the flotation preparation additives include a pH regulator, a foaming agent and a collector. The pH regulator is sulfuric acid or sodium hydroxide, the pH of the flotation preparation is 3.0 to 5.0, the foaming agent is polyethylene glycol, the addition amount of the foaming agent is 0 to 50 g per ton of raw coal, the collector is kerosene, oleic acid or dodecyl trimethyl ammonium bromide, and the addition amount of the collector is 100 g to 1000 g per ton of raw coal.

10. A method for the fractional electroflotation separation of macerals of coal and rock according to claim 1, characterized in that, In step six, the flotation time is 10 min to 60 min. The flotation separation in step six includes that the floating matter overflows from the electroflotation cell (3), and the sinking matter is discharged from the electroflotation cell (3).

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