Coal gasification fine slag residual carbon flotation recovery collector and application thereof

Abstract

This invention discloses a flotation collector for recovering residual carbon from coal gasification fine slag and its application, belonging to the field of solid waste resource utilization and mineral flotation technology. The residual carbon flotation collector is composed of liquid paraffin and kerosene in a mass ratio of (1:9) to (7:3). This invention also provides a matching flotation method. Under the conditions of an optimal mass ratio of liquid paraffin and kerosene of 3:7 and a reagent dosage of 8 kg / t, the flotation concentrate yield of coal gasification fine slag can reach 48.44%, the residual carbon recovery rate can reach 62.60%, and the carbon ash separation efficiency can be improved to 23%, which is 3 times better than the flotation effect of a single kerosene collector. The residual carbon flotation collector of this invention has a simple formula, controllable cost, high flotation efficiency, and good selectivity, which provides important help in solving the problems of poor adaptability and low recovery rate of traditional collectors to oxidized porous coal gasification fine slag. The flotation concentrate can be used as secondary fuel, and the tailings can be used as building materials for resource utilization, which has significant economic, environmental and social benefits.

Description

Technical Field

[0001] This invention relates to the field of industrial solid waste resource utilization and mineral flotation separation technology, specifically to a flotation collector for recovering residual carbon from coal gasification fine slag and its application. Background Technology

[0002] Coal gasification slag is a large-scale industrial solid waste generated during the coal gasification process. In my country alone, the annual emissions exceed 30 million tons. Its stockpiling and landfilling not only occupy a large amount of land resources, but also easily cause soil, water and air pollution, bringing serious environmental risks. At the same time, coal gasification slag contains 15%-40% unburned residual carbon particles (residual carbon), which has high resource recovery value. The recovered residual carbon products can be used as secondary power fuel, and the tailings after decarbonization can be used to prepare building materials, silicon-based materials, etc., realizing the full-scale and resource-based utilization of solid waste.

[0003] Flotation is currently the most mainstream and cost-effective technology for decarbonization and recovery of fine coal gasification slag. Its core is to selectively enhance the hydrophobicity of residual carbon particles through collectors, causing them to adhere to air bubbles and float, thus achieving separation from hydrophilic gangue minerals. Currently, traditional non-polar hydrocarbon oils such as kerosene are commonly used as collectors in industry, but they have significant technical drawbacks: kerosene has low viscosity and high volatility, and the oil film formed on the rough and porous oxidized surface of coal gasification slag is thin and unstable, easily falling off under fluid shear force, and cannot completely cover the hydrophilic groups such as hydroxyl and carboxyl groups on the surface, resulting in poor collection performance, high reagent consumption, and low concentrate recovery rate. While long-chain alkane oils such as liquid paraffin can form more stable hydrophobic oil films, their high viscosity and poor interfacial activity make it difficult to disperse and spread evenly on the surface of fine coal gasification slag, resulting in extremely poor flotation performance when used alone.

[0004] While existing research has explored composite collectors for the flotation of fine coal gasification slag, there is still a significant gap in research on the compound system of liquid paraffin and kerosene binary nonpolar oil. Summary of the Invention

[0005] To solve or partially solve the problems existing in related technologies, the primary objective of this invention is to provide a collector for the flotation recovery of residual carbon in coal gasification fine slag, wherein the residual carbon flotation recovery collector is composed of liquid paraffin and kerosene.

[0006] Preferably, the liquid paraffin of the present invention is analytical grade liquid paraffin, with a kinematic viscosity greater than 36 mmHg at room temperature. 2 / s; the kerosene is industrial grade kerosene with a kinematic viscosity of 1.3-4 mm at 20°C. 2 / s.

[0007] Preferably, the mass ratio of liquid paraffin to kerosene in this invention is (1:9)-(7:3).

[0008] As a further preferred embodiment of the present invention, the optimal mass ratio of the liquid paraffin and kerosene is 3:7.

[0009] Another objective of this invention is to propose the application of a collector for the flotation recovery of residual carbon in coal gasification fine slag, the specific steps of which are as follows: (1) Preparation of slurry: The coal gasification fine slag raw material is mixed with water, placed in a flotation cell, stirred and adjusted to obtain slurry.

[0010] (2) Collector preparation: Add the residual carbon flotation recovery collector to the slurry of step (1), stir, so that the residual carbon flotation recovery collector is fully dispersed in the slurry and selectively adsorbed on the surface of the residual carbon particles.

[0011] (3) Foaming agent conditioning: Add foaming agent to the slurry after step (2) and stir.

[0012] (4) Flotation froth removal: Air is introduced into the slurry after step (3) for aeration flotation. The froth product obtained after flotation froth removal is the flotation concentrate. The remaining product in the flotation cell is the flotation tailings. Excess water is removed by vacuum filtration, and then dried to obtain dry concentrate and tailings products. After sealing and storage, they are used for subsequent testing and utilization.

[0013] Preferably, the air-dried fixed carbon content of the coal gasification fine slag raw material in step (1) of the present invention is 35.85%; D 50 The particle size is 54 μm.

[0014] Preferably, the stirring and slurry preparation conditions in step (1) of the present invention are 1800-2000 r / min for 2-7 min; the concentration of the resulting slurry is 50-70 g / L.

[0015] Preferably, in step (2) of the present invention, the amount of collector added for residual carbon flotation recovery is 0.8-8 kg / t; the stirring conditions are 1800-2000 r / min for 1-4 min.

[0016] Preferably, the foaming agent in step (3) of the present invention is methyl isobutyl methanol, and the dosage is 6-10 kg / t; the stirring conditions are 1800-2000 r / min for 10 s-1 min.

[0017] Preferably, the air introduced into the slurry in step (4) of the present invention is compressed air, and the air volume is 2.0 m³. 3 / (m 2 (·min); stirring is carried out during the flotation process at a speed of 1800-2000 r / min; the flotation skimming time is 1-5 min; the drying conditions are 90-100℃ to constant weight.

[0018] Beneficial effects of this invention: (1) The formula of the residual carbon flotation recovery collector of the present invention is simple. The raw materials are all commonly used reagents in the flotation industry. They are widely available, cost-controllable, green and environmentally friendly. They do not require complicated synthesis and preparation processes and are easy to promote and apply in the industry. The synergistic effect of the two is significant after compounding, which effectively improves the technical bottleneck of unstable oil film of single kerosene and poor dispersibility of single liquid paraffin, and enhances the collection performance and selectivity of residual carbon in coal gasification fine slag.

[0019] (2) The flotation method of the present invention is simple and the parameters are controllable. When using the residual carbon flotation recovery collector described in the present invention and under optimal process conditions, compared with using kerosene alone as a collector, the yield of coal gasification fine slag flotation concentrate can be increased from 30.51% to 48.44%; the residual carbon recovery rate can be increased from 35.34% to 62.60%; and the carbon ash separation efficiency can be increased from 7.6% to 23%, which is 3 times higher than that of kerosene alone, and the flotation effect is significant.

[0020] (3) This invention has significant economic and environmental benefits. The loss on ignition of the flotation concentrate can reach 51.89%, and the calorific value is about 15.5-17.1 MJ / kg, which is comparable to low-rank thermal coal and can be directly used as secondary fuel. The high-ash tailings are rich in oxides such as silicon, aluminum, and calcium, which meet the requirements of building material raw materials and can be used as cement additives, non-fired brick aggregates, roadbed filling materials, etc., realizing the full resource utilization of coal gasification fine slag. Based on the annual processing of 1 million tons of coal gasification fine slag, the annual net profit can reach about RMB 235.51 million, with significant economic benefits. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the preparation process of the collector for flotation recovery of residual carbon in coal gasification fine slag involved in this invention.

[0022] Figure 2 This is a comparison chart of the flotation results of residual carbon in coal gasification fine slag under different residual carbon flotation recovery collector systems involved in this invention; wherein Figure 2 (a) The concentrate yield of residual carbon flotation in coal gasification fine slag under different residual carbon flotation recovery collector systems; Figure 2 (b) represents the loss on ignition of residual carbon in coal gasification fine slag under different residual carbon flotation recovery collector systems.

[0023] Figure 3 This is a comparison chart of the flotation parameters of Embodiment 2 and Comparative Example 1 of the present invention. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings, but the scope of protection of the present invention is not limited to the content described.

[0025] In this embodiment of the invention, a kinematic viscosity greater than 36 mm at room temperature is selected. 2 Liquid paraffin at 20°C has a kinematic viscosity of 1.3-4 mm / s. 2 Kerosene per second, its preparation process is as follows: Figure 1 As shown; the coal gasification fine slag used was purchased from Shaanxi Jingyi Chemical Group, located in the High-tech Industrial Development Zone of Shenmu City, Shaanxi Province; the moisture, ash, volatile matter, and fixed carbon content of the sample, measured in a muffle furnace on an air-dried basis, were 1.71%, 59.85%, 2.59%, and 35.85%, respectively; the D of the coal gasification fine slag... 50 The particle size is 54 μm.

[0026] Example 1 This embodiment provides a flotation collector for recovering residual carbon from coal gasification fine slag, wherein the mass ratio of liquid paraffin to kerosene is 1:9; the supporting flotation method includes the following steps: (1) Weigh 25g of air-dried coal gasification fine slag raw material, add it to the flotation cell, inject deionized water until the total volume of the slurry is 500mL, control the slurry concentration to 50g / L, and stir at 1800r / min for 7min to adjust the slurry.

[0027] (2) Add the residual carbon flotation recovery collector to the slurry at amounts of 0.8, 2.4, 4 and 8 kg / t, respectively, and stir at 1800 r / min for 4 min.

[0028] (3) Add 6 kg / t of foaming agent methyl isobutyl methanol (MIBC, CAS: 108-11-2) to the slurry and stir at 1800 r / min for 1 min.

[0029] (4) Maintain a stirring speed of 1800 r / min, introduce compressed air, and control the air volume to be 2.0 m³. 3 / (m 2 (·min), start flotation and continuously scrape the foam for 5 minutes. The scraped foam product is the concentrate, and the product in the tank is the tailings.

[0030] (5) Post-processing of products: The concentrate and tailings were vacuum filtered separately and dried in a 100℃ forced-air drying oven to constant weight. The flotation indexes were calculated, and the concentrate yield and loss on ignition of the concentrate obtained by flotation recovery of the collector from the residual carbon were as follows: Figure 2 (a) and Figure 2 As shown in (b); the flotation index results of the concentrate obtained by flotation recovery of residual carbon at a dosage of 8 kg / t are shown in Table 1.

[0031] Example 2 This embodiment provides a flotation collector for recovering residual carbon from coal gasification fine slag, wherein the mass ratio of liquid paraffin to kerosene is 3:7; the accompanying flotation method includes the following steps: (1) Weigh 30g of air-dried coal gasification fine slag raw material, add it to the flotation cell, inject deionized water until the total volume of the slurry is 500mL, control the slurry concentration to 60g / L, and stir at 1900r / min for 5min to adjust the slurry.

[0032] (2) Add the residual carbon flotation recovery collector to the slurry at a dosage of 0.8, 2.4, 4 and 8 kg / t, and stir at 1900 r / min for 2 min.

[0033] (3) Add foaming agent MIBC to the slurry at a dosage of 8 kg / t and stir at 1900 r / min for 30 s.

[0034] (4) Maintain a stirring speed of 1900 r / min, introduce compressed air, and control the air volume to be 2.0 m³. 3 / (m 2 (min), start flotation and continuously scrape the foam for 3 minutes. The scraped foam product is the concentrate, and the product in the tank is the tailings.

[0035] (5) Post-processing of products: The concentrate and tailings were vacuum filtered separately and dried in a 90℃ forced-air drying oven to constant weight. The flotation indexes were calculated, and the concentrate yield and loss on ignition of the concentrate obtained by flotation recovery of the collector from the residual carbon were as follows: Figure 2 (a) and Figure 2 (b) shows the flotation parameters of the obtained concentrate, as shown in Tables 1 and 2. Figure 3 As shown.

[0036] Example 3 This embodiment provides a flotation collector for recovering residual carbon from coal gasification fine slag, wherein the mass ratio of liquid paraffin to kerosene is 5:5; the accompanying flotation method includes the following steps: (1) Weigh 35g of air-dried coal gasification fine slag raw material, add it to the flotation cell, inject deionized water until the total volume of the slurry is 500mL, control the slurry concentration to 70g / L, and stir at 2000r / min for 2min to adjust the slurry.

[0037] (2) Add the residual carbon flotation recovery collector to the slurry at amounts of 0.8, 2.4, 4 and 8 kg / t, respectively, and stir at 2000 r / min for 2 min.

[0038] (3) Add foaming agent MIBC to the slurry at a dosage of 10 kg / t and stir at 2000 r / min for 10 s.

[0039] (4) Maintain a stirring speed of 2000 r / min, introduce compressed air, and control the air volume to be 2.0 m³. 3 / (m 2 (·min), start flotation and continuously scrape the foam for 1min. The scraped foam product is the concentrate, and the product in the tank is the tailings.

[0040] (5) Post-processing of products: The concentrate and tailings were vacuum filtered separately and dried in a 95℃ forced-air drying oven to constant weight. The flotation index was calculated, and the concentrate yield and loss on ignition of the concentrate obtained by flotation recovery of the collector from the residual carbon were as follows: Figure 2 (a) and Figure 2 As shown in (b); the flotation index results of the concentrate obtained by flotation recovery of residual carbon at a dosage of 8 kg / t are shown in Table 1.

[0041] Example 4 This embodiment provides a flotation collector for recovering residual carbon from coal gasification fine slag, wherein the mass ratio of liquid paraffin to kerosene is 7:3; the accompanying flotation method includes the following steps: (1) Weigh 30g of air-dried coal gasification fine slag raw material, add it to the flotation cell, inject deionized water until the total volume of the slurry is 500mL, control the slurry concentration to 60g / L, and stir at 1900r / min for 5min to adjust the slurry.

[0042] (2) Add the residual carbon flotation recovery collector to the slurry at amounts of 0.8, 2.4, 4 and 8 kg / t, respectively, and stir at 1900 r / min for 1 min.

[0043] (3) Add foaming agent MIBC to the slurry at a dosage of 8 kg / t and stir at 1900 r / min for 30 s.

[0044] (4) Maintain a stirring speed of 1900 r / min, introduce compressed air, and control the air volume to be 2.0 m³. 3 / (m 2 (min), start flotation and continuously scrape the foam for 3 minutes. The scraped foam product is the concentrate, and the product in the tank is the tailings.

[0045] (5) Post-processing of products: The concentrate and tailings were vacuum filtered separately and dried in a 100℃ forced-air drying oven to constant weight. The flotation indexes were calculated, and the concentrate yield and loss on ignition of the concentrate obtained by flotation recovery of the collector from the residual carbon were as follows: Figure 2 (a) and Figure 2 As shown in (b); the flotation index results of the concentrate obtained by flotation recovery of residual carbon at a dosage of 8 kg / t are shown in Table 1.

[0046] Comparative Example 1 This comparative example uses a kinematic viscosity of 1.3-4 mm at 20°C. 2 Using single kerosene as the collector, the dosages were 0.8, 2.4, 4, and 8 kg / t, respectively. The remaining flotation steps and process parameters were completely consistent with Example 2. The concentrate yield and loss on ignition of the concentrate obtained by flotation recovery of the collector from residual carbon are as follows: Figure 2 (a) and Figure 2As shown in (b), the flotation parameters of the concentrate obtained by flotation recovery of collector with residual carbon at a dosage of 8 kg / t are shown in Table 1. A comparison of the flotation parameters of the concentrate obtained by flotation recovery of collector with 8 kg / t residual carbon and that obtained by flotation recovery of collector from kerosene alone is shown in Table 1. Figure 3 As shown.

[0047] Comparative Example 2 This comparative example uses a kinematic viscosity greater than 36 mmHg at room temperature. 2 Using single liquid paraffin as the collector, the dosages were 0.8, 2.4, 4, and 8 kg / t, respectively. The remaining flotation steps and process parameters were completely consistent with Example 2. The concentrate yield and loss on ignition of the concentrate obtained by flotation recovery of residual carbon with collector dosages of 0.8, 2, and 4 kg / t are as follows: Figure 2 (a) and Figure 2 As shown in (b), the flotation index results of the concentrate obtained by flotation recovery of residual carbon with a collector dosage of 8 kg / t are shown in Table 1.

[0048] Table 1 Comparison of flotation recovery effects of residual carbon in coal gasification fine slag under different collector ratios (collector dosage 8 kg / t) As shown in Table 1, the flotation effects of single kerosene and single liquid paraffin are both poor. However, the flotation collector for coal gasification fine slag of the present invention can significantly improve the residual carbon recovery index. Among them, the optimal ratio of liquid paraffin to kerosene is 3:7, which achieves the highest residual carbon recovery rate and carbon-ash separation efficiency. Moreover, the concentrate yield, residual carbon recovery rate, and carbon-ash separation efficiency are increased by 17.93%, 27.26%, and 15.40% respectively compared with single kerosene. This indicates that the compound collector of the present invention has a significant synergistic effect. This is because the collector of the present invention forms a stable hydrophobic oil film on the surface of residual carbon, which masks the hydrophilic groups on its surface and significantly improves the hydrophobicity difference between carbon and ash particles, thereby achieving efficient flotation recovery of residual carbon in coal gasification fine slag.

[0049] Table 2 Comparison of residual carbon recovery effects from coal gasification slag under different collector dosages (ratio 3:7) As shown in Table 2, with the increase of the amount of compound collector, all flotation indicators show an upward trend. Taking into account both flotation effect and reagent cost, the present invention determines the optimal collector dosage to be 8 kg / t.

[0050] Example 5 This embodiment is based on the optimal reagent ratio and process parameters of Example 2 for industrial-scale application and economic benefit calculation. A standard flotation production line is constructed with an annual processing capacity of 1 million tons of coal gasification fine slag as the calculation benchmark. The calorific value of the flotation concentrate measured under the optimal ratio can reach 15.5-17.1 MJ / kg, which meets the quality requirements of industrial secondary fuel. The chemical composition of the flotation tailings is mainly silicon dioxide, containing compounds of iron, magnesium and calcium, which meets the relevant national standards for building material raw materials. The specific calculation results are shown in Table 3.

[0051] Table 3. Economic Benefit Analysis under Optimal Dosage of Flotation Collector Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A flotation collector for recovering residual carbon from fine coal gasification slag, characterized in that, The residual carbon flotation recovery collector is a compound of liquid paraffin and kerosene.

2. The flotation collector for recovering residual carbon from coal gasification fine slag according to claim 1, characterized in that, The mass ratio of liquid paraffin to kerosene is (1:9)-(7:3).

3. The application of the collector for recovering residual carbon from coal gasification fine slag as described in claim 1 in the flotation of residual carbon.

4. The application of the collector for recovering residual carbon from coal gasification fine slag according to claim 3 in the flotation of residual carbon, characterized in that, Includes the following steps: (1) Preparation of slurry: The coal gasification fine slag raw material is mixed with water and stirred to prepare the slurry; (2) Collector preparation: Add the residual carbon flotation recovery collector to the slurry from step (1) and stir; (3) Foaming agent conditioning: Add foaming agent to the slurry treated in step (2) and stir; (4) Flotation and foam removal: Air is introduced into the slurry after step (3) for aeration flotation. The froth product obtained after flotation and foam removal is the flotation concentrate. After filtration and drying, the dry concentrate product is obtained.

5. The application of the collector for residual carbon recovery flotation in coal gasification fine slag according to claim 4, characterized in that, The stirring and slurry preparation conditions in step (1) are 1800-2000 r / min for 2-7 min; the concentration of the resulting slurry is 50-70 g / L.

6. The application of the collector for residual carbon recovery flotation in coal gasification fine slag according to claim 4, characterized in that, In step (2), the amount of collector added for residual carbon flotation recovery is 0.8-8 kg / t; the stirring conditions are 1800-2000 r / min for 1-4 min.

7. The application of the collector for residual carbon recovery flotation in coal gasification fine slag according to claim 4, characterized in that, The foaming agent in step (3) is methyl isobutyl methanol, and the dosage is 6-10 kg / t; the stirring conditions are 1800-2000 r / min for 10 s-1 min.

8. The application of the collector for residual carbon recovery flotation in coal gasification fine slag according to claim 4, characterized in that, In step (4), the air volume introduced into the slurry is 2.0 m³. 3 / (m 2 (·min); stirring is carried out during the flotation process at a speed of 1800-2000 r / min; the flotation skimming time is 1-5 min; the drying conditions are 90-100℃ to constant weight.

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