A method for purifying natural flake graphite by selective flotation of modified water glass

Abstract

The present invention belongs to the technical field of mineral processing, and specifically, relates to a method for selectively flotating and purifying natural flake graphite by modified water glass. The present invention adopts different modified water glasses for different graphite ores for the first time, and obtains products with high fixed carbon content and high recovery rate through the combination of flotation processes. The present invention crushes and grinds the natural flake graphite ore to a set fineness, then mixes it with water to prepare a slurry, and adds a pH adjuster to adjust the pH of the slurry, then adds modified water glass according to a set amount, and then adds a collector and a frother in sequence, and finally performs aeration and scraping to obtain a flotation concentrate. The process of the present invention is simple and controllable, and the fixed carbon content of the product obtained from the roughing can be further improved after fine selection, which is convenient for industrial application.

Description

Technical Field

[0001] The invention belongs to the technical field of mineral processing, and in particular relates to a method for purifying natural flake graphite by selective flotation of modified water glass. Background Art

[0002] Graphite, a vital non-metallic strategic resource, possesses numerous irreplaceable advantages, including excellent electrical and thermal conductivity, corrosion resistance, and lubricity. Graphite is widely used in a variety of key industries, from high-tech electronics to traditional industrial sectors, playing a pivotal role in economic development and providing a solid foundation for sustainable economic development and technological advancement.

[0003] Natural graphite ore is primarily divided into flake graphite and microcrystalline graphite. Flake graphite is primarily used as a raw material for cutting-edge technologies such as batteries and atomic energy. However, with the continuous advancement of science and technology, high-grade flake graphite ore is becoming increasingly scarce. Furthermore, various countries have designated flake graphite as a strategic resource, restricting its export. Therefore, the development and utilization of low-grade flake graphite ore is particularly important. Low-grade flake graphite is characterized by low grade, fine particle size, and complex composition. Using only water glass as a modifier makes it difficult to achieve selective suppression, resulting in an inability to effectively recover useful minerals from the mineral resource and a waste of resources. To maximize the recovery of target minerals from the raw ore and improve flotation performance, alternative modifiers or water glass modification are necessary. The former not only incurs higher costs but also offers little improvement in selectivity when processing complex and difficult-to-separate ores. Modification of water glass, on the other hand, is less expensive and can significantly enhance selectivity.

[0004] Deng Jie published an article titled "Flotation separation of barite from calcite using acidified water glass as the depressant" in Colloids and Surfaces A: Physicochemical and Engineering Aspects. In the calcite flotation test, water glass and acidified water glass prepared from sodium silicate and sulfuric acid were used as depressants. Research has shown that using only water glass as a depressant does not produce ideal separation results. Using the same dosage of acidified water glass, the recovery of barite remains almost unchanged, but the recovery of calcite drops below 10%, effectively achieving the separation of barite and calcite. In his article "Selective flotation of ilmenite from olivine using the acidified water glass as a depressant" published in the International Journal of Mineral Processing, Yang Yaohui used water glass and oxalic acid-acidified water glass as depressants, respectively, to depress olivine and thereby flotate ilmenite. He found that compared with water glass, acidified water glass not only increased the recovery and grade of Ti concentrate by 7.74 percentage points and 3.82 percentage points, respectively, but also reduced depressant consumption by two-fifths. Feng Bo's article "The flotation separation of scheelite from calcite using acidified sodium silicate as a depressant" published in Minerals Engineering reported the flotation separation of calcite and scheelite using water glass and oxalic acid-acidified water glass as depressants, respectively. It was found that when using only water glass as a depressant, the recovery rates of both scheelite and calcite were around 80%, making it impossible to separate scheelite and calcite by flotation. When using acidified water glass as a depressant, the recovery rate of scheelite remained almost unchanged, but the recovery rate of calcite dropped to below 20%.

[0005] He Jingfeng published an article titled "Combined inhibitors of Fe 3+ ,Cu 2+ orAl 3+and sodiumsilicate on the flotation offluorite and quartz》The flotation offluorite and quartz was studied by using fluorite and quartz samples. 3 + 、Cu 2+ and Al 3+ The effect of separately salted water glass on fluorite flotation. Experimental results show that under optimal conditions, when Cu-water glass is used as a depressant, the fluorite recovery rate is 83.56%, while the quartz recovery rate is 6.09%, achieving efficient separation of fluorite and quartz. Wei Zhao's article, "Mechanism of Action of Al-Na2SiO3 Polymer Depressant in the Flotation Separation of Scheelite and Calcite," published in the Journal of the Chinese Society of Nonferrous Metals, uses Al-water glass, a mixture of sodium silicate and aluminum sulfate in a mass ratio of 2:1, as a depressant and a Pb-BHA complex as a collector to separate scheelite from calcite. The results show that using water glass alone as a depressant results in a certain degree of calcite enrichment. However, using Al-water glass as a depressant yields a concentrate with a scheelite recovery of 89.8% and a calcite recovery of 27%, achieving even better separation results.

[0006] Therefore, it can be seen that in the prior art, acidified modified water glass or salted modified water glass is generally used for flotation of calcite, ilmenite, scheelite, and fluorite. There are few reports on the use of modified water glass for flotation of natural flake graphite. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the present invention attempts for the first time to use different modified water glasses to float natural flake graphite.

[0008] Low-grade natural flake graphite (e.g., low-grade natural flake graphite ore with a fixed carbon content of 9% or less) is characterized by being poor, fine, and impure. Using waterglass as the sole modifier makes it difficult to achieve selective inhibition, resulting in an inability to effectively recover useful minerals from the mineral resource and a waste of resources. Using other modifiers instead incurs higher costs and, when processing complex and difficult-to-separate ores, lacks a significant improvement in the selective inhibition effect. The present invention provides a method for flotation purification of low-grade natural flake graphite using acidified modified waterglass, designed to enhance the selectivity of graphite against various impurities, more effectively inhibit gangue minerals, better enrich the flake graphite, and increase its fixed carbon content and recovery rate.

[0009] For natural flake graphite ores with a fixed carbon content of 35% or greater, traditional water glass has insufficient inhibitory effects in some cases. Using other inhibitors is costly and lacks significant improvement in selectivity when processing complex, refractory ores. This invention provides a method for flotation purification of natural flake graphite using salt-modified water glass. This method aims to enhance the selectivity of graphite against various impurities, more effectively suppress gangue minerals, better enrich the flake graphite, and increase its fixed carbon content and recovery rate.

[0010] The present invention provides a method for selectively flotating and purifying natural flake graphite by modified water glass, which includes the following schemes: Scheme 1

[0011] (1) crushing and grinding low-grade natural flake graphite ore with a fixed carbon content of less than or equal to 9% to obtain flake graphite ore powder;

[0012] (2) transferring the flake graphite ore powder obtained in step (1) to a flotation tank and mixing it with water at a pulp concentration of 10 wt.% to 22 wt.%, stirring to prepare a pulp;

[0013] (3) adding a pH adjuster to the slurry obtained in step (2) to adjust the pH of the slurry to 5 to 8, and stirring to obtain a slurry with adjusted pH;

[0014] (4) Adding acidified modified water glass in an amount of 700-1100 g / t to the slurry after pH adjustment and stirring. The amount here is calculated based on the water glass before modification;

[0015] (5) adding a collector in an amount of 270 to 420 g / t to the slurry containing the acidified modified water glass obtained in step (4) and stirring;

[0016] (6) adding a foaming agent in an amount of 200 to 390 g / t to the slurry obtained in step (5) and added with a collector, stirring, turning on the aeration switch, and then performing scraping flotation. The scraped foam is filtered and dried to obtain No. 1 flake graphite concentrate;

[0017] Option 2

[0018] (A) crushing and grinding natural flake graphite ore having a fixed carbon content of 35% or more to obtain flake graphite ore powder;

[0019] (B) transferring the flake graphite ore powder obtained in step (A) to a flotation tank and mixing it with water at a pulp concentration of 10 wt.% to 20 wt.%, stirring to prepare a pulp;

[0020] (C) adding a pH adjuster to the slurry obtained in step (B) to adjust the pH of the slurry to 9-11, and stirring;

[0021] (D) adding 600-900 g / t of salt-modified water glass to the pH-adjusted slurry obtained in step (C) and stirring, wherein the amount is calculated based on the water glass before modification;

[0022] (E) adding a collector in an amount of 360 to 540 g / t to the slurry containing the salted modified water glass obtained in step (D) and stirring;

[0023] (F) adding a foaming agent in an amount of 220 to 450 g / t to the slurry to which the collector is added obtained in step (E), stirring, turning on the aeration switch, and then performing scraping flotation. The scraped foam is filtered and dried to obtain No. 2 flake graphite concentrate.

[0024] Preferably, the present invention provides a method for selectively flotating and purifying natural flake graphite by modified water glass, wherein the first scheme comprises the following steps:

[0025] (1) Using a crusher to coarsely crush low-grade natural flake graphite ore with a fixed carbon content of less than or equal to 9% to 8-35 mm, accounting for more than 80%, to obtain a coarse crushed product, and then using a crushing and screening machine to finely crush to 0.1-3 mm, accounting for more than 80%, to obtain a fine crushed product, and using a sample preparation grinder to grind the fine crushed product for 3-5 minutes, and the grinding particle size is -200 mesh, accounting for more than 90%, to obtain flake graphite ore;

[0026] (2) transferring the flake graphite ore obtained in step (1) to a flotation tank and mixing it with water at a pulp concentration of 10 wt.% to 22 wt.%, and stirring for 1 to 3 minutes to prepare a pulp;

[0027] (3) adding a pH adjuster to the slurry obtained in step (2) to adjust the pH of the slurry to 5-8, and stirring for 2-5 minutes;

[0028] (4) After the acid and water glass are modified, the acidified modified water glass is added to the slurry after the pH is adjusted in an amount of 700-1100 g / t and stirred for 2-5 minutes. The amount here is calculated based on the water glass before modification;

[0029] (5) adding a collector at a dosage of 270-420 g / t to the slurry containing the acidified modified water glass and stirring for 2-5 minutes;

[0030] (6) Add a foaming agent in an amount of 200-390 g / t to the slurry to which the collector has been added. After stirring for 1-3 minutes, turn on the aeration switch and then scrape the foam for 4-7 minutes. The scraped foam is filtered and dried at 105° C. to obtain No. 1 flake graphite concentrate, and the rest is tailings.

[0031] Preferably, the present invention provides a method for selectively flotating and purifying natural flake graphite by modified water glass, wherein the second scheme comprises the following steps:

[0032] (A) crushing natural flake graphite ore having a fixed carbon content of 35% or more to 80% or more by using a crusher to obtain a coarse crushed product, then crushing it to 80% or more by using a crushing and screening machine to obtain a fine crushed product, and grinding the fine crushed product for 3 to 5 minutes by using a sample preparation mill to obtain a grinding particle size of -200 mesh or more, thereby obtaining flake graphite ore;

[0033] (B) transferring the flake graphite ore obtained in step (A) to a flotation tank and mixing it with water at a pulp concentration of 10 wt.% to 20 wt.%, and stirring for 1 to 3 minutes to prepare a pulp;

[0034] (C) adding a pH adjuster to the slurry obtained in step (B) to adjust the pH of the slurry to 9-11, and stirring for 2-5 minutes;

[0035] (D) After the salt and water glass are modified, 600 to 900 g / t of salt-modified water glass is added to the pH-adjusted slurry and stirred for 2 to 5 minutes. The amount here is calculated based on the water glass before modification.

[0036] (E) adding a collector in an amount of 360 to 540 g / t to the slurry containing the salted modified water glass and stirring for 2 to 5 minutes;

[0037] (F) Adding a foaming agent in an amount of 220-450 g / t to the ore pulp to which the collector has been added, stirring for 1-3 minutes, turning on the aeration switch, and then scraping the foam for 5-8 minutes. The scraped foam is filtered and dried at 105° C. to obtain No. 2 flake graphite concentrate, and the rest is tailings.

[0038] In Option 1, the quartz content in the low-grade natural flake graphite ore with a fixed carbon content of less than or equal to 9% is greater than 20wt%.

[0039] In Option 2, the quartz content in the natural flake graphite ore with a fixed carbon content greater than or equal to 35% is less than or equal to 20wt%.

[0040] In industrial applications, the crusher can be a jaw crusher, and the crushing and screening machine can be a roller crushing and screening machine.

[0041] The water used is preferably deionized water, and the flotation machine used can be an XFG5-35 hanging trough flotation machine. Of course, other bubbling flotation equipment can be used in the present invention.

[0042] The stirring process of Scheme 1 and Scheme 2 can be carried out by using a flotation machine impeller with a rotation speed of 1200-1900 r / min, including 1200-1800 r / min and 1400-1900 r / min.

[0043] The pH adjusters used were HCl and NaOH.

[0044] In the present invention, in scheme 1, the acid used for acidifying and modifying the water glass is at least one of sulfuric acid and oxalic acid, wherein the mass ratio of the acid to the water glass is 1:1 to 1:3.

[0045] The preparation method of the acidified modified water glass is as follows: first, determining the ratio of water glass and acid, then diluting the water glass solution and the acid solution respectively and stirring them uniformly, and ultrasonically treating them for 3 to 7 minutes under ultrasonic conditions of a frequency of 20 kHz and a power of 200 W during stirring, and then preparing a water glass standard solution and an acid standard solution respectively, and then mixing the water glass standard solution and the acid standard solution in a required ratio and stirring them uniformly, and ultrasonically treating them for 8 to 12 minutes under ultrasonic conditions of a frequency of 20 kHz and a power of 200 W during stirring, to finally obtain the acidified modified water glass solution.

[0046] In the present invention, in scheme 2, the salt used for salt-modified water glass is at least one of Al2(SO4)3, ZnSO4, AlCl3 and FeCl3, wherein the mass ratio of salt to water glass is 1:1 to 1:4.

[0047] The preparation method of the salt-modified water glass comprises the following steps: firstly determining the ratio of water glass and salt, then diluting the water glass solution and the salt solution respectively and stirring them uniformly, and ultrasonically treating them for 3 to 7 minutes under ultrasonic conditions of a frequency of 20 kHz and a power of 150 W during stirring, and then preparing a water glass standard solution and a salt water standard solution respectively, and then mixing the water glass standard solution and the salt water standard solution in a required ratio and stirring them uniformly, and ultrasonically treating them for 8 to 12 minutes under ultrasonic conditions of a frequency of 20 kHz and a power of 150 W during stirring, to finally obtain the salt-modified water glass solution.

[0048] The collector used is one of kerosene and diesel.

[0049] The foaming agent used is one of terpineol, methyl isobutyl carbinol and sec-octanol.

[0050] After turning on the air intake switch, the air intake volume is 30~80L / h, including 30~70L / h and 40~80L / h.

[0051] The obtained No. 1 flake graphite concentrate and No. 2 flake graphite concentrate are both graphite concentrates obtained by rough selection;

[0052] The fixed carbon content of the No. 1 graphite concentrate obtained by roughing is greater than or equal to 69%, and the fixed carbon content of the No. 1 graphite concentrate obtained after optimization is greater than or equal to 71%. The No. 1 graphite concentrate obtained by roughing is then beneficiated in 475g / t of acidified modified water glass, 145g / t of kerosene as a collector, and 150g / t of terpineol as a foaming agent. After three beneficiation cycles, the fixed carbon content of the graphite concentrate is increased to over 93.5%.

[0053] The fixed carbon content of the No. 2 graphite concentrate obtained from roughing is greater than or equal to 83%. After optimization, the fixed carbon content of the No. 2 graphite concentrate obtained from roughing is greater than or equal to 84%. The No. 2 graphite concentrate obtained from roughing is then subjected to concentrating in 400g / t of salt-modified water glass, 190g / t of kerosene as a collector, and 140g / t of terpineol as a foaming agent. After two rounds of concentrating, the fixed carbon content of the graphite concentrate is increased to greater than or equal to 95%.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] The present invention uses acid to perform acidification modification treatment on water glass. After the acid is added to the water glass solution, the hydrolysis of sodium silicate therein is promoted to move toward the direction of generating silicate colloids. The silicate colloids have strong activity and hydrophilicity, and are more selective in the process of inhibiting minerals. In addition, the modification process is supplemented with ultrasonic treatment of the water glass, so that the modified water glass molecules are smaller and have better dispersibility. In addition, the modified water glass has stronger selectivity for flake graphite ores and gangue minerals with high quartz content and low fixed carbon content, can better inhibit the floating of gangue minerals, and greatly improve the fixed carbon content of flake graphite flotation concentrate and its recovery rate.

[0056] The present invention uses salt to perform salt-modification treatment on water glass, and the modification process is supplemented by ultrasonic treatment of the water glass, so that the modified water glass molecules are smaller and have better dispersibility. In addition, the modified water glass has stronger selectivity for flake graphite ores and gangue minerals with less quartz content and higher fixed carbon content, can better inhibit the flotation of gangue minerals, and greatly improve the fixed carbon content of flake graphite flotation concentrate and its recovery rate.

[0057] The present invention adopts different modified water glasses for different graphite ores for the first time, and obtains products with high fixed carbon content and high recovery rate through the cooperation of flotation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 This is a flow chart of solution 1 of the present invention.

[0059] Figure 2 This is a flow chart of the second solution of the present invention. DETAILED DESCRIPTION

[0060] The following examples describe embodiments of the present invention in detail. However, those skilled in the art will appreciate that the following examples are intended to illustrate the present invention only and should not be construed as limiting the scope of the present invention. Where specific conditions are not specified in the examples, the experiments were performed under conventional conditions or those recommended by the manufacturer. Reagents and instruments used, for which the manufacturer is not indicated, are commercially available conventional products.

[0061] The specific embodiments of the present invention are further described below in conjunction with examples, but the present invention is not limited to the scope of the examples.

[0062] Example 1 of Scheme 1

[0063] The natural flake graphite ore produced in the Inner Mongolia mining area has impurities mainly consisting of mica and quartz (quartz content is about 55.34wt%), and its composition is shown in Table 1.

[0064] Table 1 Composition of natural flake graphite from a mining area in Inner Mongolia

[0065]

[0066] The natural flake graphite ore is first crushed by an XPC-100X60 jaw crusher to 8-35 mm, accounting for more than 80%, to obtain a coarse crushed product, and then finely crushed by an XPS-Ф250×150 roller crusher and screening machine to 0.1-3 mm, accounting for more than 80%, to obtain a fine crushed product, and the obtained fine crushed product is ground by a sample grinder for 4 minutes, and the grinding particle size is -200 mesh, accounting for more than 90%, to obtain flake graphite ore;

[0067] 1 ml of water glass and 1 ml of sulfuric acid (wherein the mass fraction of H2SO4 is 95-98%) are respectively diluted with deionized water, and then stirred uniformly. During stirring, ultrasonic treatment is performed for 5 minutes under ultrasonic conditions of a frequency of 20 kHz and a power of 200 W. Then, a water glass standard solution and a sulfuric acid standard solution are respectively prepared in a 50 ml volumetric flask. Then, the water glass standard solution and the sulfuric acid standard solution are mixed and stirred uniformly in a mass ratio of sulfuric acid: water glass = 1:3. During stirring, ultrasonic treatment is performed for 10 minutes under ultrasonic conditions of a frequency of 20 kHz and a power of 200 W to finally obtain an acidified modified water glass solution.

[0068] The flake graphite ore obtained by grinding is transferred to a flotation tank and mixed with water at a pulp concentration of 16 wt.%, and stirred for 3 minutes to prepare a pulp. A pH adjuster is added to the obtained pulp to adjust the pulp pH to 6, and stirred for 3 minutes;

[0069] Acidified modified water glass is added into the flotation tank at a dosage of 950 g / t of water glass before modification and stirred for 3 minutes; then kerosene as a collector is added at a dosage of 290 g / t and stirred for 3 minutes; then pine oil as a foaming agent is added at a dosage of 300 g / t. After stirring for 2 minutes, the aeration switch is turned on and the air intake is set to 40 L / h. Then, the foam is scraped for 6 minutes. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate, and the rest is tailings.

[0070] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product specifications obtained through continuous expansion tests were: a fixed carbon content of 74.38% and a recovery rate of 85.17%. This means that the fixed carbon content of the graphite concentrate obtained from the roughing process was 74.38%, and the graphite recovery rate was 85.17%.

[0071] The graphite concentrate obtained from roughing was refined in 475g / t of acidified modified water glass, 145g / t of collector kerosene and 150g / t of foaming agent terpineol. After three refinements, the fixed carbon content in the graphite concentrate increased to 94.81%.

[0072] Example 2 of Scheme 1

[0073] The natural flake graphite ore produced in a mining area in Henan Province has impurities mainly consisting of mica, quartz, feldspar and pyrite (quartz content is about 43.02 wt%). Its composition is shown in Table 2.

[0074] Table 2 Composition of natural flake graphite from a mining area in Henan

[0075]

[0076] The natural flake graphite ore is first crushed by an XPC-100X60 jaw crusher to 8-35 mm, accounting for more than 80%, to obtain a coarse crushed product, and then finely crushed by an XPS-Ф250×150 roller crusher and screening machine to 0.1-3 mm, accounting for more than 80%, to obtain a fine crushed product, and the obtained fine crushed product is ground by a sample preparation grinder for 3 minutes, and the grinding particle size is -200 mesh, accounting for more than 90%, to obtain flake graphite ore;

[0077] 1 ml of water glass and 1 ml of sulfuric acid were respectively diluted with deionized water, and then stirred uniformly. During stirring, ultrasonic treatment was performed for 5 minutes under ultrasonic conditions of a frequency of 20 kHz and a power of 200 W. Then, a water glass standard solution and a sulfuric acid standard solution were respectively prepared using 50 ml volumetric flasks. The water glass standard solution and the sulfuric acid standard solution were then mixed and stirred uniformly in a ratio of sulfuric acid: water glass = 1:2. During stirring, ultrasonic treatment was performed for 10 minutes under ultrasonic conditions of a frequency of 20 kHz and a power of 200 W to finally obtain an acidified modified water glass solution.

[0078] The flake graphite ore obtained by grinding is transferred to a flotation tank and mixed with water at a pulp concentration of 20 wt.%, and stirred for 3 minutes to prepare a pulp. A pH adjuster is added to the obtained pulp to adjust the pulp pH to 6.5, and stirred for 3 minutes;

[0079] Acidified modified water glass is added to the flotation tank at a dosage of 900 g / t of water glass before modification and stirred for 3 minutes; then 320 g / t of collector diesel is added and stirred for 3 minutes; then 330 g / t of foaming agent methyl isobutyl carbinol is added. After stirring for 2 minutes, the aeration switch is turned on and the air intake is set to 50 L / h. Then, the foam is scraped for 7 minutes. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate, and the rest is tailings.

[0080] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product indicators obtained through continuous expansion tests were: fixed carbon content of 71.91% and recovery rate of 86.32%. In other words, the fixed carbon content of the graphite concentrate obtained from the roughing was 71.91%, and the graphite recovery rate was 86.32%.

[0081] The graphite concentrate obtained by roughing is refined in 450g / t of acidified modified water glass, 160g / t of diesel as a collector, and 165g / t of methyl isobutyl carbinol as a foaming agent. After three rounds of refinement, the fixed carbon content in the graphite concentrate is increased to 93.99%.

[0082] Example 3 of Scheme 1

[0083] The natural flake graphite ore produced in a mining area in Henan Province has impurities mainly consisting of mica, quartz and feldspar (quartz content is 56.57 wt%). Its composition is shown in Table 3.

[0084] Table 3 Composition of natural flake graphite from a mining area in Henan

[0085]

[0086] The natural flake graphite ore is first crushed by an XPC-100X60 jaw crusher to 8-35 mm, accounting for more than 80%, to obtain a coarse crushed product, and then finely crushed by an XPS-Ф250×150 roller crusher and screening machine to 0.1-3 mm, accounting for more than 80%, to obtain a fine crushed product, and the obtained fine crushed product is ground by a sample preparation grinder for 3 minutes, and the grinding particle size is -200 mesh, accounting for more than 90%, to obtain flake graphite ore;

[0087] 1 ml of water glass and 1 ml of oxalic acid were respectively diluted with deionized water, and then stirred evenly. During stirring, they were ultrasonically treated for 5 minutes under an ultrasonic condition of a frequency of 20 kHz and a power of 200 W. Then, a water glass standard solution and an oxalic acid standard solution were respectively prepared in a 50 ml volumetric flask. Then, the water glass standard solution and the oxalic acid standard solution were mixed and stirred evenly in a ratio of oxalic acid: water glass = 1:3. During stirring, they were ultrasonically treated for 10 minutes under an ultrasonic condition of a frequency of 20 kHz and a power of 200 W to finally obtain an acidified modified water glass solution.

[0088] The flake graphite ore obtained by grinding was transferred to a flotation tank and mixed with water at a pulp concentration of 22 wt.%, and stirred for 3 minutes to prepare a pulp. A pH adjuster was added to the obtained pulp to adjust the pulp pH to 7.5, and stirred for 3 minutes;

[0089] Acidified modified water glass is added into the flotation tank at a dosage of 1100 g / t of water glass before modification and stirred for 3 minutes; then kerosene as a collector is added at a dosage of 270 g / t and stirred for 3 minutes; then 240 g / t of octanol as a foaming agent is added. After stirring for 2 minutes, the aeration switch is turned on and the air intake is set to 55 L / h. Then, the foam is scraped for 5 minutes. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate, and the rest is tailings.

[0090] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product indicators obtained through continuous expansion tests were: fixed carbon content of 69.27% ​​and recovery rate of 78.63%. In other words, the fixed carbon content of the graphite concentrate obtained from roughing was 69.27%, and the graphite recovery rate was 78.63%.

[0091] The graphite concentrate obtained by roughing is refined in 550g / t of acidified modified water glass, 135g / t of kerosene as a collector and 120g / t of octanol as a foaming agent. After four refinements, the fixed carbon content in the graphite concentrate is increased to 95.21%.

[0092] Comparative Example 1 of Scheme 1

[0093] Other conditions are the same as those in the roughing process of Example 1, except that the water glass is not subjected to acidification modification treatment:

[0094] The natural flake graphite ore is first crushed by an XPC-100X60 jaw crusher to 8-35 mm, accounting for more than 80%, to obtain a coarse crushed product, and then finely crushed by an XPS-Ф250×150 roller crusher and screening machine to 0.1-3 mm, accounting for more than 80%, to obtain a fine crushed product, and the obtained fine crushed product is ground by a sample grinder for 4 minutes, and the grinding particle size is -200 mesh, accounting for more than 90%, to obtain flake graphite ore;

[0095] The flake graphite ore obtained by grinding is transferred to a flotation tank and mixed with water at a pulp concentration of 16 wt.%, and stirred for 3 minutes to prepare a pulp. A pH adjuster is added to the obtained pulp to adjust the pulp pH to 6, and stirred for 3 minutes;

[0096] Add 950g / t of water glass into the flotation tank and stir for 3 minutes; then add 290g / t of collector kerosene and stir for 3 minutes; then add 300g / t of foaming agent pine oil. After stirring for 2 minutes, turn on the inflation switch, set the air intake to 40L / h, and then scrape and foam for 6 minutes. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate, and the rest is tailings.

[0097] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product obtained through continuous expansion tests showed a fixed carbon content of 49.43% and a recovery rate of 51.09%. This means that the fixed carbon content of the graphite concentrate obtained from the roughing process was 49.43%, and the graphite recovery rate was 51.09%.

[0098] Comparative Example 2 of Scheme 1

[0099] Other conditions are the same as those in Example 1, except that the ratio of acid to water glass in the modified water glass ratio is not within the protection range of the present invention of 1:1 to 1:3, that is:

[0100] The natural flake graphite ore is first crushed by an XPC-100X60 jaw crusher to 8-35 mm, accounting for more than 80%, to obtain a coarse crushed product, and then finely crushed by an XPS-Ф250×150 roller crusher and screening machine to 0.1-3 mm, accounting for more than 80%, to obtain a fine crushed product, and the obtained fine crushed product is ground by a sample grinder for 4 minutes, and the grinding particle size is -200 mesh, accounting for more than 90%, to obtain flake graphite ore;

[0101] 1 ml of water glass and 1 ml of sulfuric acid were respectively diluted with deionized water, and then stirred evenly. During stirring, ultrasonic treatment was performed for 5 minutes under ultrasonic conditions of a frequency of 20 kHz and a power of 200 W. Then, a water glass standard solution and a sulfuric acid standard solution were respectively prepared using 50 ml volumetric flasks. The water glass standard solution and the sulfuric acid standard solution were then mixed and stirred evenly in a ratio of sulfuric acid: water glass = 2:1. During stirring, ultrasonic treatment was performed for 10 minutes under ultrasonic conditions of a frequency of 20 kHz and a power of 200 W to finally obtain an acidified modified water glass solution.

[0102] The flake graphite ore obtained by grinding is transferred to a flotation tank and mixed with water at a pulp concentration of 16 wt.%, and stirred for 3 minutes to prepare a pulp. A pH adjuster is added to the obtained pulp to adjust the pulp pH to 6, and stirred for 3 minutes;

[0103] Acidified modified water glass is added into the flotation tank at a dosage of 950 g / t of water glass before modification and stirred for 3 minutes; then kerosene as a collector is added at a dosage of 290 g / t and stirred for 3 minutes; then pine oil as a foaming agent is added at a dosage of 300 g / t. After stirring for 2 minutes, the aeration switch is turned on and the air intake is set to 40 L / h. Then, the foam is scraped for 6 minutes. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate, and the rest is tailings.

[0104] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product obtained through continuous expansion tests showed a fixed carbon content of 47.35% and a recovery rate of 32.81%. This means that the fixed carbon content of the graphite concentrate obtained from the roughing process was 47.35%, and the graphite recovery rate was 32.81%.

[0105] Comparative Example 3 of Scheme 1

[0106] Other conditions are the same as those in Example 1, except that the amount of modified water glass is not within the protection range of the present invention, 700 to 1100 g / t, namely:

[0107] The natural flake graphite ore is first crushed by an XPC-100X60 jaw crusher to 8-35 mm, accounting for more than 80%, to obtain a coarse crushed product, and then finely crushed by an XPS-Ф250×150 roller crusher and screening machine to 0.1-3 mm, accounting for more than 80%, to obtain a fine crushed product, and the obtained fine crushed product is ground by a sample grinder for 4 minutes, and the grinding particle size is -200 mesh, accounting for more than 90%, to obtain flake graphite ore;

[0108] 1 ml of water glass and 1 ml of sulfuric acid were respectively diluted with deionized water, and then stirred uniformly. During stirring, ultrasonic treatment was performed for 5 minutes under ultrasonic conditions of a frequency of 20 kHz and a power of 200 W. Then, a water glass standard solution and a sulfuric acid standard solution were respectively prepared using 50 ml volumetric flasks. The water glass standard solution and the sulfuric acid standard solution were then mixed and stirred uniformly in a ratio of sulfuric acid: water glass = 1:3. During stirring, ultrasonic treatment was performed for 10 minutes under ultrasonic conditions of a frequency of 20 kHz and a power of 200 W to finally obtain an acidified modified water glass solution.

[0109] The flake graphite ore obtained by grinding is transferred to a flotation tank and mixed with water at a pulp concentration of 16 wt.%, and stirred for 3 minutes to prepare a pulp. A pH adjuster is added to the obtained pulp to adjust the pulp pH to 6, and stirred for 3 minutes;

[0110] Acidified modified water glass is added into the flotation tank at a dosage of 1300 g / t of water glass before modification and stirred for 3 minutes; then kerosene as a collector is added at a dosage of 290 g / t and stirred for 3 minutes; then pine oil as a foaming agent is added at a dosage of 300 g / t. After stirring for 2 minutes, the aeration switch is turned on and the air intake is set to 40 L / h. Then, the foam is scraped for 6 minutes. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate, and the rest is tailings.

[0111] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product specifications obtained through continuous expansion tests were: a fixed carbon content of 61.75% and a recovery rate of 56.31%. In other words, the fixed carbon content of the graphite concentrate obtained from the roughing was 61.75%, and the graphite recovery rate was 56.31%.

[0112] Comparative Example 4

[0113] Other conditions are the same as those in Example 1, except that:

[0114] 1 ml of water glass and 1 g of Al2(SO4)3 were diluted with deionized water, and then stirred respectively. During stirring, ultrasonic treatment was performed for 5 minutes under an ultrasonic condition of a frequency of 20 kHz and a power of 150 W. Then, a water glass standard solution and an aluminum sulfate standard solution were respectively prepared using a 50 ml volumetric flask. The water glass standard solution and the aluminum sulfate standard solution were then mixed and stirred in a ratio of aluminum sulfate: water glass = 1:2. During stirring, ultrasonic treatment was performed for 10 minutes under an ultrasonic condition of a frequency of 20 kHz and a power of 150 W to finally obtain a salinized modified water glass solution.

[0115] The flake graphite ore obtained by grinding is transferred to a flotation tank and mixed with water at a pulp concentration of 16 wt.%, and stirred for 3 minutes to prepare a pulp. A pH adjuster is added to the obtained pulp to adjust the pulp pH to 6, and stirred for 3 minutes;

[0116] The salt-modified water glass is added into the flotation tank at a dosage of 950 g / t of the water glass before modification and stirred for 3 minutes; then the collector kerosene is added at a dosage of 290 g / t and stirred for 3 minutes; then the foaming agent pine oil is added at a dosage of 300 g / t. After stirring for 2 minutes, the inflation switch is turned on and the air intake is set to 40 L / h. Then, the foam is scraped for 7 minutes. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate, and the rest is tailings.

[0117] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product obtained through continuous expansion tests showed a fixed carbon content of 58.20% and a recovery rate of 59.77%.

[0118] Solution 2 - Example 4

[0119] The natural flake graphite ore produced in the Hunan mining area has impurities mainly consisting of mica and albite (quartz content is 8.16wt%), and the fixed carbon content of the ore is 44.62%.

[0120] The natural flake graphite ore in the Hunan mining area is coarsely crushed by a crusher to 8-35 mm, accounting for more than 80%, to obtain a coarse crushed product, and then finely crushed by a crushing and screening machine to 0.1-3 mm, accounting for more than 80%, to obtain a fine crushed product, and the fine crushed product is ground by a sample grinder for 3 minutes, and the grinding particle size is -200 mesh, accounting for more than 80%, to obtain flake graphite ore;

[0121] 1 ml of water glass and 1 g of Al2(SO4)3 were diluted with deionized water respectively, and then stirred evenly. During stirring, ultrasonic treatment was performed for 5 minutes under ultrasonic conditions of 20 kHz and 150 W. Then, water glass standard solution and aluminum sulfate standard solution were prepared respectively in 50 ml volumetric flasks. Then, the water glass standard solution and aluminum sulfate standard solution were mixed and stirred evenly in a ratio of aluminum sulfate: water glass = 1:2. During stirring, ultrasonic treatment was performed for 10 minutes under ultrasonic conditions of 20 kHz and 150 W. Finally, a salt-modified water glass solution was obtained.

[0122] The flake graphite ore obtained by grinding is transferred to a flotation tank and mixed with water at a pulp concentration of 15 wt.%, and stirred for 3 minutes to prepare a pulp. A pH adjuster is added to the obtained pulp to adjust the pulp pH to 10, and stirred for 3 minutes;

[0123] The salt-modified water glass is added into the flotation tank at a dosage of 800 g / t of the water glass before modification and stirred for 3 minutes; then the collector kerosene is added at a dosage of 380 g / t and stirred for 3 minutes; then the foaming agent pine oil is added at a dosage of 280 g / t. After stirring for 2 minutes, the inflation switch is turned on and the air intake is set to 50 L / h. Then, the foam is scraped for 7 minutes. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate, and the rest is tailings.

[0124] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product indicators obtained through continuous expansion tests were: a fixed carbon content of 85.91% and a recovery rate of 83.34%. In other words, the fixed carbon content of the graphite concentrate obtained from the roughing was 85.91%, and the graphite recovery rate was 83.34%.

[0125] The graphite concentrate obtained from the roughing was refined in 400 g / t of salt-modified water glass, 190 g / t of collector kerosene and 140 g / t of foaming agent terpineol. After two rounds of refinement, the fixed carbon content in the graphite concentrate increased to 95.17%.

[0126] Option 2 - Example 5

[0127] The natural flake graphite ore produced in the Inner Mongolia mining area has impurities mainly consisting of mica, albite and pyrite (quartz content is 12.31wt%), and the fixed carbon content of the ore is 38.71%.

[0128] The natural flake graphite ore in the Inner Mongolia mining area is coarsely crushed by a crusher to 8-35 mm, accounting for more than 80%, to obtain a coarse crushed product, and then finely crushed by a crushing and screening machine to 0.1-3 mm, accounting for more than 80%, to obtain a fine crushed product, and the fine crushed product is ground by a sample preparation grinder for 3 minutes, and the grinding particle size is -200 mesh, accounting for more than 80%, to obtain flake graphite ore;

[0129] 1 ml of water glass and 1 g of AlCl3 were diluted with deionized water, and then stirred evenly. During stirring, ultrasonic treatment was performed for 5 minutes under an ultrasonic condition of 20 kHz and 150 W. Then, a water glass standard solution and an aluminum sulfate standard solution were prepared in a 50 ml volumetric flask. The water glass standard solution and the aluminum sulfate standard solution were mixed and stirred evenly in a ratio of aluminum chloride: water glass = 2:3. During stirring, ultrasonic treatment was performed for 10 minutes under an ultrasonic condition of 20 kHz and 150 W. Finally, a salt-modified water glass solution was obtained.

[0130] The flake graphite ore obtained by grinding is transferred to a flotation tank and mixed with water at a pulp concentration of 20 wt.%, and stirred for 3 minutes to prepare a pulp. A pH adjuster is added to the obtained pulp to adjust the pulp pH to 10, and stirred for 3 minutes;

[0131] The salt-modified water glass is added into the flotation tank at a dosage of 900 g / t of the water glass before modification and stirred for 3 minutes; then the collector diesel is added at a dosage of 360 g / t and stirred for 3 minutes; then the foaming agent pine oil is added at a dosage of 270 g / t. After stirring for 2 minutes, the inflation switch is turned on and the air intake is set to 60 L / h. Then, the foam is scraped for 7 minutes. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate, and the rest is tailings.

[0132] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product indicators obtained through continuous expansion tests were: fixed carbon content of 84.11% and recovery rate of 82.09%. In other words, the fixed carbon content of the graphite concentrate obtained from the roughing was 84.11%, and the graphite recovery rate was 82.09%.

[0133] The graphite concentrate obtained from roughing was refined in 450g / t of salt-modified water glass, 180g / t of collector kerosene and 135g / t of foaming agent terpineol. After three refinements, the fixed carbon content in the graphite concentrate increased to 95.60%.

[0134] Option 2 - Example 6

[0135] The natural flake graphite ore produced in the Henan mining area has impurities mainly consisting of mica, potassium feldspar and pyrite (quartz content is 6.97wt%), and the fixed carbon content of the ore is 49.03%.

[0136] The natural flake graphite ore in the Henan mining area is coarsely crushed by a crusher to 8-35 mm, accounting for more than 80%, to obtain a coarse crushed product, and then finely crushed by a crushing and screening machine to 0.1-3 mm, accounting for more than 80%, to obtain a fine crushed product, and the fine crushed product is ground by a sample preparation grinder for 3 minutes, and the grinding particle size is -200 mesh, accounting for more than 80%, to obtain flake graphite ore;

[0137] 1 ml of water glass and 1 g of ZnSO4 were diluted with deionized water, and then stirred evenly. During stirring, ultrasonic treatment was performed for 5 minutes under ultrasonic conditions of 20 kHz and 150 W. Then, a water glass standard solution and an aluminum sulfate standard solution were prepared in a 50 ml volumetric flask. The water glass standard solution and the aluminum sulfate standard solution were mixed and stirred evenly in a ratio of zinc sulfate: water glass = 1:3. During stirring, ultrasonic treatment was performed for 10 minutes under ultrasonic conditions of 20 kHz and 150 W. Finally, a salt-modified water glass solution was obtained.

[0138] The flake graphite ore obtained by grinding is transferred to a flotation tank and mixed with water at a pulp concentration of 18 wt.%, and stirred for 3 minutes to prepare a pulp. A pH adjuster is added to the obtained pulp to adjust the pulp pH to 9, and stirred for 3 minutes;

[0139] The salt-modified water glass is added into the flotation tank at a dosage of 820 g / t of the water glass before modification and stirred for 3 minutes; then the collector kerosene is added at a dosage of 340 g / t and stirred for 3 minutes; then the foaming agent octanol is added at a dosage of 260 g / t. After stirring for 2 minutes, the inflation switch is turned on and the air intake is set to 60 L / h. Then, the foam is scraped for 8 minutes. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate, and the rest is tailings.

[0140] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product indicators obtained through continuous expansion tests were: a fixed carbon content of 86.23% and a recovery rate of 83.07%. In other words, the fixed carbon content of the graphite concentrate obtained from the roughing was 86.23%, and the graphite recovery rate was 83.07%.

[0141] The graphite concentrate obtained from the roughing was refined in 410 g / t of salt-modified water glass, 170 g / t of kerosene as a collector, and 130 g / t of terpineol as a foaming agent. After two rounds of refinement, the fixed carbon content in the graphite concentrate increased to 96.12%.

[0142] Scheme 2-Comparative Example 5

[0143] Other conditions are the same as those in Example 4, except that the water glass is not subjected to salt modification treatment:

[0144] The natural flake graphite ore in the Hunan mining area is coarsely crushed by a crusher to 8-35 mm, accounting for more than 80%, to obtain a coarse crushed product, and then finely crushed by a crushing and screening machine to 0.1-3 mm, accounting for more than 80%, to obtain a fine crushed product, and the fine crushed product is ground by a sample grinder for 3 minutes, and the grinding particle size is -200 mesh, accounting for more than 80%, to obtain flake graphite ore;

[0145] The flake graphite ore obtained by grinding is transferred to a flotation tank and mixed with water at a pulp concentration of 15 wt.%, and stirred for 3 minutes to prepare a pulp. A pH adjuster is added to the obtained pulp to adjust the pulp pH to 10, and stirred for 3 minutes;

[0146] Water glass is added into the flotation tank at a dosage of 800 g / t before modification and stirred for 3 minutes; then kerosene as a collector is added at a dosage of 380 g / t and stirred for 3 minutes; then pine oil as a foaming agent is added at a dosage of 280 g / t. After stirring for 2 minutes, the aeration switch is turned on and the air intake is set to 50 L / h. Then, the foam is scraped for 7 minutes. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate, and the rest is tailings.

[0147] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product obtained through continuous expansion tests showed a fixed carbon content of 59.82% and a recovery rate of 52.10%. This means that the fixed carbon content of the graphite concentrate obtained from the roughing process was 59.82%, and the graphite recovery rate was 52.10%.

[0148] Scheme 2-Comparative Example 6

[0149] Other conditions are the same as those in Example 4, except that the ratio of salt to water glass in the modified water glass mixture is not within the protection range of the present invention of 1:1 to 1:4, namely:

[0150] The natural flake graphite ore in the Hunan mining area is coarsely crushed by a crusher to 8-35 mm, accounting for more than 80%, to obtain a coarse crushed product, and then finely crushed by a crushing and screening machine to 0.1-3 mm, accounting for more than 80%, to obtain a fine crushed product, and the fine crushed product is ground by a sample grinder for 3 minutes, and the grinding particle size is -200 mesh, accounting for more than 80%, to obtain flake graphite ore;

[0151] 1 ml of water glass and 1 g of Al2(SO4)3 were diluted with deionized water respectively, and then stirred evenly. During stirring, ultrasonic treatment was performed for 5 minutes under ultrasonic conditions of 20 kHz and 150 W. Then, water glass standard solution and aluminum sulfate standard solution were prepared respectively in 50 ml volumetric flasks. Then, the water glass standard solution and aluminum sulfate standard solution were mixed and stirred evenly in a ratio of aluminum sulfate: water glass = 3:1. During stirring, ultrasonic treatment was performed for 10 minutes under ultrasonic conditions of 20 kHz and 150 W. Finally, a salt-modified water glass solution was obtained.

[0152] The flake graphite ore obtained by grinding is transferred to a flotation tank and mixed with water at a pulp concentration of 15 wt.%, and stirred for 3 minutes to prepare a pulp. A pH adjuster is added to the obtained pulp to adjust the pulp pH to 10, and stirred for 3 minutes;

[0153] The salt-modified water glass is added into the flotation tank at a dosage of 800 g / t of the water glass before modification and stirred for 3 minutes; then the collector kerosene is added at a dosage of 380 g / t and stirred for 3 minutes; then the foaming agent pine oil is added at a dosage of 280 g / t. After stirring for 2 minutes, the inflation switch is turned on and the air intake is set to 50 L / h. Then, the foam is scraped for 7 minutes. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate, and the rest is tailings.

[0154] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product obtained through continuous expansion tests showed a fixed carbon content of 57.34% and a recovery rate of 54.62%.

[0155] Scheme 2-Comparative Example 7

[0156] Other conditions are the same as those in Example 4, except that the amount of modified water glass is not within the protection range of the present invention, 600 to 900 g / t, namely:

[0157] The natural flake graphite ore in the Hunan mining area is coarsely crushed by a crusher to 8-35 mm, accounting for more than 80%, to obtain a coarse crushed product, and then finely crushed by a crushing and screening machine to 0.1-3 mm, accounting for more than 80%, to obtain a fine crushed product, and the fine crushed product is ground by a sample grinder for 3 minutes, and the grinding particle size is -200 mesh, accounting for more than 80%, to obtain flake graphite ore;

[0158] 1 ml of water glass and 1 g of Al2(SO4)3 were diluted with deionized water respectively, and then stirred evenly. During stirring, ultrasonic treatment was performed for 5 minutes under ultrasonic conditions of 20 kHz and 150 W. Then, water glass standard solution and aluminum sulfate standard solution were prepared respectively in 50 ml volumetric flasks. Then, the water glass standard solution and aluminum sulfate standard solution were mixed and stirred evenly in a ratio of aluminum sulfate: water glass = 1:2. During stirring, ultrasonic treatment was performed for 10 minutes under ultrasonic conditions of 20 kHz and 150 W. Finally, a salt-modified water glass solution was obtained.

[0159] The flake graphite ore obtained by grinding is transferred to a flotation tank and mixed with water at a pulp concentration of 15 wt.%, and stirred for 3 minutes to prepare a pulp. A pH adjuster is added to the obtained pulp to adjust the pulp pH to 10, and stirred for 3 minutes;

[0160] The salt-modified water glass is added into the flotation tank at a dosage of 500 g / t of the water glass before modification and stirred for 3 minutes; then the collector kerosene is added at a dosage of 380 g / t and stirred for 3 minutes; then the foaming agent pine oil is added at a dosage of 280 g / t. After stirring for 2 minutes, the inflation switch is turned on and the air intake is set to 50 L / h. Then, the foam is scraped for 7 minutes. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate, and the rest is tailings.

[0161] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product obtained through continuous expansion tests showed a fixed carbon content of 56.83% and a recovery rate of 72.91%.

[0162] Comparative Example 8

[0163] The raw materials and other conditions were the same as in Example 4, except that:

[0164] 1 ml of water glass and 1 ml of sulfuric acid were respectively diluted with deionized water, and then stirred evenly. During stirring, ultrasonic treatment was performed for 5 minutes under ultrasonic conditions of a frequency of 20 kHz and a power of 200 W. Then, a water glass standard solution and a sulfuric acid standard solution were respectively prepared using 50 ml volumetric flasks. The water glass standard solution and the sulfuric acid standard solution were then mixed and stirred evenly in a ratio of sulfuric acid: water glass = 2:1. During stirring, ultrasonic treatment was performed for 10 minutes under ultrasonic conditions of a frequency of 20 kHz and a power of 200 W to finally obtain an acidified modified water glass solution.

[0165] The flake graphite ore obtained by grinding is transferred to a flotation tank and mixed with water at a pulp concentration of 15 wt.%, and stirred for 3 minutes to prepare a pulp. A pH adjuster is added to the obtained pulp to adjust the pulp pH to 10, and stirred for 3 minutes;

[0166] The acidified modified water glass solution is added to the flotation tank at a dosage of 800 g / t of water glass before modification and stirred for 3 minutes; then the collector kerosene is added at a dosage of 380 g / t and stirred for 3 minutes; then the foaming agent pine oil is added at a dosage of 280 g / t. After stirring for 2 minutes, the inflation switch is turned on and the air intake is set to 50 L / h. Then, the foam is scraped for 7 minutes. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate, and the rest is tailings.

[0167] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product obtained through continuous expansion tests showed a fixed carbon content of 78.63% and a recovery rate of 81.26%.

Claims

1. A method for purifying natural flake graphite by selective flotation of modified water glass, comprising the following scheme: Option 1 (1) Using a crusher to coarsely crush low-grade natural flake graphite ore with a fixed carbon content of 9% or less to 8-35 mm, accounting for more than 80%, to obtain a coarse crushed product, and then using a crushing and screening machine to finely crush to 0.1-3 mm, accounting for more than 80%, to obtain a fine crushed product, and using a sample preparation grinder to grind the fine crushed product for 3-5 minutes, with a grinding particle size of -200 mesh accounting for more than 90%, to obtain flake graphite ore; (2) transferring the flake graphite ore obtained in step (1) to a flotation tank and mixing it with water at a pulp concentration of 10 wt.% to 22 wt.%, and stirring for 1 to 3 minutes to prepare a pulp; (3) adding a pH adjuster to the slurry obtained in step (2) to adjust the pH of the slurry to 5-8, and stirring for 2-5 minutes; (4) After the acid and water glass are modified, the acidified modified water glass is added to the slurry after the pH is adjusted in an amount of 700 to 1100 g / t and stirred for 2 to 5 minutes. The amount here is calculated based on the water glass before modification. The acid used for the acidified modified water glass is at least one of sulfuric acid and oxalic acid, wherein the mass ratio of the acid to the water glass is 1:1 to 1:3; (5) Adding a collector at a dosage of 270-420 g / t to the slurry containing the acidified modified water glass and stirring for 2-5 minutes; (6) Adding a foaming agent in an amount of 200-390 g / t to the slurry to which the collector has been added, stirring for 1-3 minutes, turning on the aeration switch, and then scraping and foaming for 4-7 minutes. The scraped foam is filtered and dried at 105°C to obtain No. 1 flake graphite concentrate, and the rest is tailings; Option 2 (A) crushing natural flake graphite ore having a fixed carbon content of 35% or more to 80% or more of 8-35 mm using a crusher to obtain a coarse crushed product, and then crushing it to 0.1-3 mm using a crushing and screening machine to obtain a fine crushed product, and grinding the fine crushed product using a sample preparation mill for 3-5 minutes to obtain a grinding particle size of -200 mesh or more, thereby obtaining flake graphite ore; (B) transferring the flake graphite ore obtained in step (A) to a flotation tank and mixing it with water at a pulp concentration of 10 wt.% to 20 wt.%, and stirring for 1 to 3 minutes to prepare a pulp; (C) adding a pH adjuster to the slurry obtained in step (B) to adjust the pH of the slurry to 9-11, and stirring for 2-5 minutes; (D) After the salt and water glass are modified, 600 to 900 g / t of salt-modified water glass is added to the slurry after the pH adjustment, and stirred for 2 to 5 minutes. The amount used is calculated based on the water glass before modification. The salt used in the salt-modified water glass is at least one of Al2(SO4)3, ZnSO4, AlCl3 and FeCl3, wherein the mass ratio of salt to water glass is 1:1 to 1:4; (E) adding a collector in an amount of 360 to 540 g / t to the slurry containing the salted modified water glass, and stirring for 2 to 5 minutes; (F) Adding a foaming agent in an amount of 220-450 g / t to the ore pulp to which the collector has been added, stirring for 1-3 minutes, turning on the aeration switch, and then scraping the foam for 5-8 minutes. The scraped foam is filtered and dried at 105°C to obtain No. 2 flake graphite concentrate, and the rest is tailings.

2. The method for purifying natural flake graphite by selective flotation of modified water glass according to claim 1, wherein: In Option 1, the quartz content in the low-grade natural flake graphite ore with a fixed carbon content of 9% or less is greater than 20wt%; In Option 2, the quartz content in the natural flake graphite ore with a fixed carbon content greater than or equal to 35% is less than or equal to 20wt%.

3. The method for purifying natural flake graphite by selective flotation of modified water glass according to claim 1, wherein: The mixing process of Scheme 1 and Scheme 2 uses a flotation machine impeller for stirring, with a rotation speed of 1200-1900 r / min; The pH adjusters used were HCl and NaOH.

4. The method for purifying natural flake graphite by selective flotation of modified water glass according to claim 1, wherein: The collector used is one of kerosene and diesel; The foaming agent used is one of terpineol, methyl isobutyl carbinol and sec-octanol; After turning on the inflation switch, the air intake volume is 30~80L / h.

5. The method for purifying natural flake graphite by selective flotation of modified water glass according to claim 1, wherein: The obtained No. 1 flake graphite concentrate and No. 2 flake graphite concentrate are both graphite concentrates obtained by rough selection; The fixed carbon content of the No. 1 graphite concentrate obtained by roughing is greater than or equal to 69%, and the fixed carbon content of the No. 1 graphite concentrate obtained after optimization is greater than or equal to 71%. The No. 1 graphite concentrate obtained by roughing is subjected to beneficiation under the conditions of 475g / t of acidified modified water glass, 145g / t of kerosene as a collector, and 150g / t of terpineol as a foaming agent. After three beneficiation cycles, the fixed carbon content in the graphite concentrate is increased to more than 93.5%. The fixed carbon content of the No. 2 graphite concentrate obtained by roughing is greater than or equal to 83%. The fixed carbon content of the No. 2 graphite concentrate obtained after optimization is greater than or equal to 84%. The No. 2 graphite concentrate obtained by roughing is finely concentrated in 400g / t of salt-modified water glass, 190g / t of collector kerosene and 140g / t of foaming agent terpineol. After two rounds of fine concentration, the fixed carbon content in the graphite concentrate is increased to greater than or equal to 95%.

Images