Graphite flotation process capable of improving flotation efficiency

Abstract

The invention discloses a graphite flotation process capable of improving flotation efficiency, and relates to the technical field of graphite flotation, and the graphite flotation process comprises the following steps: step 1, raw ore pretreatment and classified ore grinding, step 2, roughing operation, step 3, scavenging and middling treatment, and step 4, multi-stage regrinding concentration. According to the graphite flotation process capable of improving the flotation efficiency, the dissociation degree of graphite monomers below 5 microns is improved to 92% or above through the classified ore grinding-ultrasonic synergistic dissociation technology, the gas-solid collision efficiency is enhanced in cooperation with a microbubble flotation machine, the concentrate grade is improved by 1-2% compared with the prior art, and the recovery rate is improved by 2-3%; and the problem of low flotation efficiency caused by insufficient dissociation of micro-fine particle graphite is effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of art traceability, and specifically to a graphite flotation process that can improve flotation efficiency. Background Art

[0002] Graphite has many excellent properties such as good high-temperature resistance, thermal shock resistance, thermal conductivity, electrical conductivity, lubricity, plasticity, and chemical stability, and is widely used in industrial fields such as metallurgy, machinery, electrical appliances, chemical industry, textiles, and national defense. However, China's graphite industry faces problems such as chaotic mining order and serious resource waste; backward mining and beneficiation processes, overcapacity, and serious pollution; and the sustainable and stable supply of graphite resources plays an important role in the country's sustainable development.

[0003] The invention with the publication number CN108745656A discloses a method for improving the flotation efficiency of fine-grained graphite, which includes the following steps: (1) using a mill to grind the raw microcrystalline graphite ore, with a grinding concentration of 30%-35% and a grinding fineness of: -0.074mm accounting for 75%-85%; (2) sequentially adding an inhibitor and a collector to the pulp for rough selection of graphite to obtain a rough concentrate and a rough tailing; the rough concentrate is reground, and after regrinding, an inhibitor and a collector are sequentially added for cleaning to obtain a concentrate product.

[0004] As shown in the above invention, the existing method uses a multi-stage vertical mill process, which can promote the dissociation of fine-grained microcrystalline graphite, ensure the grade and recovery rate of graphite concentrate, and has less reagent consumption. However, the existing method uses a multi-stage vertical mill process. Although the dissociation efficiency is improved compared with the traditional process, the monomer dissociation degree of ultra-fine graphite with a particle size of 1-5μm is insufficient, resulting in a large number of locked particles still existing in the rough concentrate, and multiple cleaning operations are required to improve the grade, resulting in a long process. In addition, the surface adsorption capacity of the collector for particles with a particle size of less than 1μm is limited, and the flotation recovery rate is easily limited due to poor particle dispersion. Moreover, the inhibition effect of the existing inhibitor on mica and carbonate gangue is significantly affected by the pH fluctuation of the pulp, and no differential formula is designed for complex gangue such as feldspar and quartz. For example, when the mica content in the raw ore exceeds 15% or there are multiple types of gangue symbiosis, it is necessary to significantly increase the reagent consumption, resulting in increased costs and possibly affecting the surface activity of graphite, causing a decrease in the adsorption efficiency of the collector during cleaning. Summary of the Invention

[0005] In view of the deficiencies of the prior art, the present invention provides a graphite flotation process that can improve flotation efficiency, and solves the existing problems.

[0006] To achieve the above objectives, the present invention is realized through the following technical solutions: A graphite flotation process that can improve flotation efficiency, including the following steps:

[0007] Step 1. Pretreatment of raw ore and classification grinding: Use a vertical mill for the first-stage grinding of microcrystalline graphite raw ore. The grinding concentration is 30%-35%, and the grinding fineness is controlled to be 75%-85% passing through 0.074mm. After grinding, the pulp is separated by a spiral classifier. The coarse fraction is returned to the vertical mill for re-grinding, and the fine fraction enters the roughing process.

[0008] Step 2. Roughing operation: Add an inhibitor and a collector to the classified fine-fraction pulp in sequence for roughing. The inhibitor is composed of 15-25g of water glass with a modulus of 2.8-3.5, 1g of sodium hexametaphosphate, 0.4-0.6g of carboxymethyl cellulose, and 70-100g of water, and the addition amount is 400-800g / ton of raw ore. The collector is composed of 2-5g of fatty acid methyl ester, 1g of α-olefin, 5-15g of propanol, and 200-400g of water, and the addition amount is 90-180g / ton of raw ore. The roughing obtains roughing concentrate and roughing tailings.

[0009] Step 3. Scavenging and middlings treatment: Add a collector to the roughing tailings for scavenging. The dosage of the scavenging collector is 30-60g / ton of raw ore. The scavenging concentrate and the cleaning tailings are mixed and returned to the raw ore grinding process, and are subjected to roughing together with the new feed.

[0010] Step 4. Multi-stage re-grinding and cleaning: The roughing concentrate is re-ground, and then an inhibitor and a collector are added in sequence for cleaning. Before the first cleaning, the re-grinding fineness is 75%-90% passing through 0.023mm, the dosage of the inhibitor is 40-80g / ton of raw ore, and the dosage of the collector is 10-30g / ton of raw ore. Before the second cleaning, the re-grinding fineness is 80%-92% passing through 0.018mm, and the dosage of the reagent is 20%-30% less than that of the previous cleaning. Before the third cleaning, the re-grinding fineness is 84%-93% passing through 0.018mm, forming a stepped fineness and reagent gradient addition.

[0011] Preferably, the α-olefin is a straight-chain α-olefin with 8-10 carbon atoms, and the fatty acid methyl ester has the molecular formula C7H 12 O4, and forms a stable collector system with α-olefin through propanol as a dispersant.

[0012] Preferably, the water glass with a modulus of 2.8-3.5, sodium hexametaphosphate, and carboxymethyl cellulose in the inhibitor form a synergistic inhibition effect through compounding.

[0013] Preferably, the roughing operation uses an air-agitated flotation machine, with an air inflow of 0.6-1.0m 3 / (m 2 ·min), a stirring speed of 1200-1800r / min, and a flotation time of 3-5min to achieve the preliminary separation of fine-grained graphite and gangue.

[0014] Preferably, in the beneficiation operation, the pulp after each regrinding needs to be adjusted, and the pulp adjustment time is 2 - 3 min, so that the inhibitor and the collector are evenly dispersed in the pulp, improving the adsorption efficiency of the reagent on the graphite surface.

[0015] Preferably, in the three - stage beneficiation operation, the dosage of the inhibitor in the first - stage beneficiation is 60 - 80 g / ton of raw ore, and the dosage of the collector is 20 - 30 g / ton of raw ore; the dosage of the inhibitor in the second - stage beneficiation is 40 - 60 g / ton of raw ore, and the dosage of the collector is 10 - 20 g / ton of raw ore; the dosage of the inhibitor in the third - stage beneficiation is 30 - 50 g / ton of raw ore, and the dosage of the collector is 5 - 15 g / ton of raw ore, forming a decreasing gradient of reagent dosage.

[0016] Preferably, the vertical mill adopts a closed - circuit grinding process, and sodium carbonate with a mass concentration of 0.1% - 0.3% is added as a grinding aid during the grinding process to improve the dissociation efficiency of graphite and gangue.

[0017] Preferably, during the flotation process, the pH value of the pulp is controlled at 8.0 - 9.5, and it is adjusted by adding a sodium hydroxide or hydrochloric acid solution with a mass concentration of 1% - 3% to ensure the optimal action environment of the inhibitor and the collector.

[0018] Preferably, the scavenging operation uses a shallow - trough flotation machine, the flotation time is 2 - 3 min, and the air - inflow rate is 0.5 - 0.8 m 3 / (m 2 ·min), focusing on recovering the fine - grained graphite that is not fully dissociated in the rougher tailings.

[0019] Preferably, after the concentrate product is dehydrated by a thickener, it is dried by a pneumatic dryer, the drying temperature is 80 - 100 °C, and the drying time is 15 - 20 min, finally obtaining a graphite concentrate with a fixed - carbon content of ≥90%.

[0020] Beneficial effects

[0021] The present invention provides a graphite flotation process that can improve flotation efficiency. Compared with the prior art, it has the following beneficial effects:

[0022] 1. This graphite flotation process that can improve flotation efficiency, through the classification grinding - ultrasonic synergistic dissociation technology, improves the monomer dissociation degree of graphite below 5 μm to more than 92%. Combined with a micro - bubble flotation machine to enhance the gas - solid collision efficiency, the concentrate grade is increased by 1 - 2 percentage points compared with the prior art, and the recovery rate is increased by 2 - 3 percentage points, effectively solving the problem of low flotation efficiency caused by insufficient dissociation of fine - grained graphite.

[0023] 2. The graphite flotation process that can improve flotation efficiency, through an amphiphilic collector system and a nano-composite inhibitor, by means of π-π conjugate adsorption and a dual inhibition mechanism of "electrostatic repulsion + steric hindrance", reduces the collector dosage by 40% and the inhibitor dosage by 30%. At the same time, the stepped cleaning reagent gradient system combined with the pulse aeration technology stably controls the number of cleaning times at 3 times, reduces the energy consumption by 30%, and reduces the beneficiation cost by more than 25%, achieving green and efficient beneficiation while ensuring the separation index. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic process flow diagram of the present invention.

[0025] Figure 2 It is a schematic diagram of the action mechanism of the amphiphilic collector of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0027] Refer to Figure 1-2 , the present invention provides the following two technical solutions:

[0028] The first embodiment: A graphite flotation process that can improve flotation efficiency, including the following steps:

[0029] Step 1. Pretreatment of raw ore and classification grinding: Use a vertical mill to perform the first-stage grinding on the microcrystalline graphite raw ore. The vertical mill adopts a closed-circuit grinding process. During the grinding process, sodium carbonate with a mass concentration of 0.1%-0.3% is added as a grinding aid to improve the dissociation efficiency of graphite and gangue. The grinding concentration is 30%-35%, and the grinding fineness is controlled to be 75%-85% of 0.074mm. After grinding, the pulp is separated by a spiral classifier. The coarse-grained fraction is returned to the vertical mill for re-grinding, and the fine-grained fraction enters the roughing process.

[0030] Step 2. Roughing operation: Add an inhibitor and a collector to the classified fine-grained pulp in sequence for roughing. Use an aeration and agitation flotation machine with an aeration volume of 0.6-1.0m 3 / (m 2· min), stirring speed 1200 - 1800 r / min, flotation time 3 - 5 min, to achieve the preliminary separation of fine-grained graphite and gangue. During the flotation process, the pulp pH value is controlled at 8.0 - 9.5, adjusted by adding sodium hydroxide or hydrochloric acid solution with a mass concentration of 1% - 3% to ensure the optimal action environment of the inhibitor and the collector. The inhibitor consists of 15 - 25 g of water glass with a modulus of 2.8 - 3.5, 1 g of sodium hexametaphosphate, 0.4 - 0.6 g of carboxymethyl cellulose, and 70 - 100 g of water, and the addition amount is 400 - 800 g / ton of raw ore; the water glass with a modulus of 2.8 - 3.5, sodium hexametaphosphate, and carboxymethyl cellulose in the inhibitor form a synergistic inhibitory effect through compounding. The collector consists of 2 - 5 g of fatty acid methyl ester, 1 g of α-olefin, 5 - 15 g of propanol, and 200 - 400 g of water. The α-olefin is a straight-chain α-olefin with 8 - 10 carbon atoms, and the molecular formula of the fatty acid methyl ester is C7H 12 O4, and forms a stable collector system with α-olefin through propanol as a dispersant, with an addition amount of 90 - 180 g / ton of raw ore. The rough concentrate and rough tailings are obtained by rough selection.

[0031] Step 3. Scavenging and middlings treatment: The rough tailings are added with a collector for scavenging. The dosage of the scavenging collector is 30 - 60 g / ton of raw ore. The scavenging concentrate and the cleaning tailings are mixed and returned to the raw ore grinding process, and are subjected to rough selection together with the newly fed ore. The scavenging operation uses a shallow tank flotation machine, with a flotation time of 2 - 3 min and an air inflow of 0.5 - 0.8 m 3 / (m 2 · min), focusing on recovering the fine-grained graphite that is not fully dissociated in the rough tailings.

[0032] Step 4: Multi-stage regrinding and cleaning: The rougher concentrate is reground, and inhibitors and collectors are added in sequence for cleaning; before the first cleaning, the regrinding fineness is 75%-90% of 0.023mm, the inhibitor dosage is 40-80g / ton of raw ore, and the collector dosage is 10-30g / ton of raw ore; before the second cleaning, the regrinding fineness is 80%-92% of 0.018mm, and the dosage of the reagent is reduced by 20%-30% compared with the previous cleaning; before the third cleaning, the regrinding fineness is 84%-93% of 0.018mm, forming a stepped fineness and reagent gradient addition. During the three cleaning operations, for the first cleaning, the inhibitor dosage is 60-80g / ton of raw ore, and the collector dosage is 20-30g / ton of raw ore; for the second cleaning, the inhibitor dosage is 40-60g / ton of raw ore, and the collector dosage is 10-20g / ton of raw ore; for the third cleaning, the inhibitor dosage is 30-50g / ton of raw ore, and the collector dosage is 5-15g / ton of raw ore, forming a decreasing gradient of reagent dosage. After each regrinding, the pulp needs to be adjusted, and the adjusting time is 2-3min to evenly disperse the inhibitor and collector in the pulp and improve the adsorption efficiency of the reagent on the graphite surface. After the concentrate product is dehydrated by a thickener, it is dried by an air dryer, the drying temperature is 80-100°C, and the drying time is 15-20min. Finally, graphite concentrate with a fixed carbon content of ≥90% is obtained.

[0033] The second implementation mode: Example

[0034] Example 1: Separation of microcrystalline graphite ore in Chenzhou, Hunan

[0035] Properties of raw ore

[0036] The fixed carbon content is 68.5%, and the graphite below 5μm accounts for 82%. The gangue minerals are mainly mica (content 11.8%) and carbonate (content 4.2%). The ore structure is complex, and the embedding relationship between graphite and gangue minerals is close.

[0037] Process steps

[0038] Pretreatment and classification grinding of raw ore

[0039] The raw ore is ground in the first stage by a vertical mill, and the grinding concentration is set at 32%. To improve the grinding efficiency, sodium carbonate with a mass concentration of 0.2% is added as a grinding aid during the grinding process. By continuously adjusting the grinding time and parameters, the grinding fineness reaches 80% of -0.074mm.

[0040] The pulp after grinding enters a spiral classifier for separation. The coarse fraction (+0.074mm) is returned to the vertical mill through a pipeline for continuous grinding, forming a closed-circuit grinding process to ensure the full dissociation of graphite and gangue. The fine fraction (0.074mm) pulp is transported to the rougher operation through a chute.

[0041] Rougher operation

[0042] The classified fine-grained pulp is introduced into an aerated agitation flotation machine. First, an inhibitor is added at an addition rate of 600 g / ton of raw ore. The inhibitor consists of 20 g of water glass with a modulus of 3.2, 1 g of sodium hexametaphosphate, 0.5 g of carboxymethyl cellulose, and 80 g of water. After the inhibitor is added, the flotation machine is started and agitated for 2 minutes to fully disperse the inhibitor in the pulp and inhibit the floating of gangue minerals.

[0043] Next, a collector is added at an addition rate of 130 g / ton of raw ore. The collector consists of 3 g of fatty acid methyl ester, 1 g of α-olefin (a straight-chain α-olefin with 9 carbon atoms), 10 g of propanol, and 300 g of water. The aeration rate of the flotation machine is adjusted to 0.8 m 3 / (m 2 ·min), the agitation speed is 1500 r / min, and a flotation operation is carried out for 4 minutes to obtain rougher concentrate and rougher tailings.

[0044] Scavenging and middlings treatment

[0045] The rougher tailings enter a shallow-tank flotation machine for scavenging, and a collector is added at a dosage of 45 g / ton of raw ore. During the scavenging process, the aeration rate is controlled at 0.6 m 3 / (m 2 ·min), and the flotation time is 2.5 minutes to recover as much as possible the fine-grained graphite not selected in the rougher tailings to obtain scavenged concentrate.

[0046] The scavenged concentrate and the cleaner tailings are mixed through a pipeline and returned to the raw ore grinding process to be roughed together with the new feed to realize the recycling of middlings.

[0047] Multi-stage regrinding and cleaning

[0048] First cleaning: The rougher concentrate enters a ball mill for regrinding. By controlling the grinding time of the ball mill and the steel ball ratio, the regrinding fineness reaches 80% passing 0.023 mm. The regrinded pulp enters a conditioning tank and is conditioned for 2 minutes to fully disperse the reagents in the pulp. Then, an inhibitor is added at a dosage of 70 g / ton of raw ore, and a collector is added at a dosage of 25 g / ton of raw ore for the first cleaning operation.

[0049] Second cleaning: The first-cleaned concentrate enters the ball mill for regrinding again to increase the fineness to 85% passing 0.018 mm. After conditioning for 2 minutes, 50 g / ton of raw ore of inhibitor and 15 g / ton of raw ore of collector are added for the second cleaning.

[0050] Third cleaning: The second-cleaned concentrate is continuously regrinded to 90% passing 0.018 mm. After conditioning for 2 minutes, 40 g / ton of raw ore of inhibitor and 10 g / ton of raw ore of collector are added to complete the third cleaning operation.

[0051] During the whole beneficiation process, the pH value of the pulp was controlled between 8.5 and 9.0 by adding a sodium hydroxide solution with a mass concentration of 2%.

[0052] Concentrate dewatering and drying

[0053] The concentrate product obtained after three times of beneficiation was transported through a pipeline to a thickener for preliminary dewatering to remove most of the water. Then the dewatered concentrate was sent to a flash dryer and dried at a temperature of 90 °C for 18 minutes to obtain the final graphite concentrate product.

[0054] Indicators

[0055] After the above process treatment, the fixed carbon content of the finally obtained graphite concentrate reached 91.5%, and the recovery rate was 90.8%. Compared with the existing technology, the concentrate grade increased by 1.2 percentage points, the recovery rate increased by 3.5 percentage points, and the dosage of reagents decreased by 28%.

[0056] Example 2: Separation of low-grade graphite ore in Xichuan

[0057] Properties of raw ore

[0058] The fixed carbon content was 52.3%, the proportion of graphite below 5 μm was as high as 88%, the mica content in gangue minerals was 14.5%, and the carbonate content was 5.5%. The ore grade was low and the graphite particle size was fine, making the separation difficult.

[0059] Process steps

[0060] Pretreatment and classification grinding of raw ore

[0061] The vertical mill was used for the first-stage grinding of the raw ore. The grinding concentration was 30%, and sodium carbonate with a mass concentration of 0.15% was added as a grinding aid. The grinding fineness was controlled to be 78% passing through 0.074 mm.

[0062] The coarse fraction separated by the spiral classifier was returned to the vertical mill for re-grinding, and the fine fraction pulp entered the roughing process.

[0063] Roughing operation

[0064] In an air-agitated flotation machine, an inhibitor (22 g of water glass with a modulus of 3.0, 1 g of sodium hexametaphosphate, 0.45 g of carboxymethyl cellulose, and 90 g of water) was added at 700 g per ton of raw ore and stirred for 2.5 minutes.

[0065] Then a collector (4 g of fatty acid methyl ester, 1 g of α-olefin (linear α-olefin with 8 carbon atoms), 12 g of propanol, and 350 g of water) was added at 150 g per ton of raw ore, and the air inflow rate was 0.9 m 3 / (m 2·min), with a stirring speed of 1600 r / min and a flotation time of 4.5 minutes to obtain rougher concentrate and rougher tailings.

[0066] Scavenging and Middlings Treatment

[0067] The rougher tailings are scavenged by a shallow-cell flotation machine with a collector dosage of 50 g / ton of raw ore and an air inflow of 0.7 m 3 / (m 2 ·min), and the scavenged concentrate is obtained with a flotation time of 2 minutes.

[0068] The scavenged concentrate and the cleaner tailings are mixed and returned to the raw ore grinding process.

[0069] Multi-stage Regrinding and Cleaning

[0070] First cleaning: The rougher concentrate is reground to 82% passing 0.023 mm, the pulp is conditioned for 2 minutes, with an inhibitor dosage of 75 g / ton of raw ore and a collector dosage of 28 g / ton of raw ore.

[0071] Second cleaning: The concentrate from the first cleaning is reground to 87% passing 0.018 mm, the pulp is conditioned for 2 minutes, with an inhibitor dosage of 55 g / ton of raw ore and a collector dosage of 18 g / ton of raw ore.

[0072] Third cleaning: The concentrate from the second cleaning is reground to 92% passing 0.018 mm, the pulp is conditioned for 2 minutes, with an inhibitor dosage of 45 g / ton of raw ore and a collector dosage of 12 g / ton of raw ore.

[0073] During the cleaning process, the pH value of the pulp is controlled between 8.2 - 8.8 with a 1.5% sodium hydroxide solution by mass concentration.

[0074] Concentrate Dewatering and Drying

[0075] The concentrate is preliminarily dewatered by a thickener and then sent to a flash dryer for drying at 85°C for 20 minutes to obtain the final product.

[0076] Indicators

[0077] The fixed carbon content of the final graphite concentrate reaches 90.2%, and the recovery rate is 89.3%. Compared with the existing technology, the concentrate grade is increased by 0.9 percentage points, the recovery rate is increased by 2.8 percentage points, and the reagent dosage is reduced by 25%.

[0078] Example 3: Separation of a Graphite Mine in Heilongjiang

[0079] Properties of Raw Ore

[0080] The fixed carbon content is 65.7%, graphite below 5 μm accounts for 78%, gangue minerals are mainly feldspar (content 10.2%) and quartz (content 7.8%), and the dissemination relationship between graphite and gangue is relatively complex.

[0081] Process steps

[0082] Pretreatment of raw ore and classification grinding

[0083] Grinding with a vertical mill, grinding concentration 34%, adding a grinding aid of sodium carbonate with a mass concentration of 0.25%, and the grinding fineness is 82% passing through 0.074mm.

[0084] Separation by a spiral classifier, the coarse fraction is returned for regrinding, and the fine fraction enters rough selection.

[0085] Rough selection operation

[0086] In an air-agitated flotation machine, add an inhibitor (18g of water glass with a modulus of 3.4, 1g of sodium hexametaphosphate, 0.55g of carboxymethyl cellulose and 75g of water) at 500g / ton of raw ore, and stir for 1.5 minutes.

[0087] Add a collector (2.5g of fatty acid methyl ester, 1g of α-olefin (linear α-olefin with 10 carbon atoms), 8g of propanol and 250g of water) at 110g / ton of raw ore, the air inflow rate is 0.7m 3 / (m 2 ·min), the stirring speed is 1400r / min, and flotation is carried out for 3 minutes to obtain rough selection concentrate and rough selection tailings.

[0088] Scavenging and middlings treatment

[0089] Scavenging in a shallow tank flotation machine, the collector dosage is 35g / ton of raw ore, the air inflow rate is 0.55m 3 / (m 2 ·min), the flotation time is 1.5 minutes, and scavenging concentrate is obtained.

[0090] The scavenging concentrate and the cleaning tailings are mixed and returned to the raw ore grinding process.

[0091] Multi-stage regrinding and cleaning

[0092] First cleaning: The rough selection concentrate is regrinded to 78% passing through 0.023mm, the pulp is adjusted for 2 minutes, the inhibitor dosage is 65g / ton of raw ore, and the collector dosage is 22g / ton of raw ore.

[0093] Second cleaning: The first cleaning concentrate is regrinded to 83% passing through 0.018mm, the pulp is adjusted for 2 minutes, the inhibitor dosage is 45g / ton of raw ore, and the collector dosage is 13g / ton of raw ore.

[0094] Third cleaning: The second cleaning concentrate is regrinded to 88% passing through 0.018mm, the pulp is adjusted for 2 minutes, the inhibitor dosage is 35g / ton of raw ore, and the collector dosage is 8g / ton of raw ore.

[0095] During the beneficiation process, the pH value of the pulp is controlled between 8.8 and 9.2 with a sodium hydroxide solution having a mass concentration of 2.5%.

[0096] Concentrate dewatering and drying

[0097] After the concentrate is dewatered by a thickener, it is dried in a flash dryer at 95°C for 16 minutes to obtain the final graphite concentrate.

[0098] Indicators

[0099] The fixed carbon content of the final graphite concentrate reaches 91.0%, and the recovery rate is 90.1%. Compared with the prior art, the concentrate grade is increased by 1.1 percentage points, the recovery rate is increased by 3.2 percentage points, and the dosage of reagents is reduced by 30%.

[0100] The following table is a data comparison table of the above embodiments

[0101]

[0102] Through the process innovation of "grading grinding for enhanced dissociation - precise regulation with composite reagents - closed-loop recycling of middlings", the present invention realizes the efficient separation of fine-grained graphite, significantly outperforms the prior art in key indicators such as concentrate grade, recovery rate, and reagent consumption, and has wide adaptability to ores with different grades and different gangue types, with significant economic and environmental benefits.

[0103] Meanwhile, the content not described in detail in this specification belongs to the prior art well-known to those skilled in the art, and the model parameters of each electrical appliance are not specifically limited, and conventional equipment can be used.

[0104] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprises", "comprising" or any other variation thereof is intended to cover a non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device.

[0105] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made therein without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A graphite flotation process that can improve flotation efficiency, characterized in that, The following steps are involved: Step 1: Pretreatment of raw ore and graded grinding: Use vertical mill to grind the raw microcrystalline graphite ore in the first stage, the grinding concentration is 30%-35%, and the grinding fineness is controlled to be 0.074mm, accounting for 75%-85%; after grinding, the slurry is separated by spiral classifier, the coarse particles are returned to the vertical mill for re-grinding, and the fine particles enter the roughing process; Step 2, roughing operation: adding an inhibitor and a collector to the classified fine-grained slurry in sequence for roughing, wherein the inhibitor is composed of 15-25g of water glass with a modulus of 2.8-3.5, 1g of sodium hexametaphosphate, 0.4-0.6g of carboxymethyl cellulose and 70-100g of water, and the addition amount is 400-800g / ton of raw ore; the collector is composed of 2-5g of fatty acid methyl ester, 1g of α-olefin, 5-15g of propanol and 200-400g of water, and the addition amount is 90-180g / ton of raw ore, and roughing concentrate and roughing tailings are obtained by roughing; Step 3: Scavenging and middling treatment: Add collector to rougher tailings for scavenging, the amount of scavenging collector is 30-60g / ton of raw ore, the scavenged concentrate is mixed with the selected tailings and returned to the raw ore grinding process, and roughed together with the new feed ore; Step 4, multi-stage regrinding and concentration: the rough concentrate is regrinded, and after regrinding, inhibitors and collectors are added in sequence for concentration; the regrinding fineness before the first concentration is 0.023mm, accounting for 75%-90%, the inhibitor dosage is 40-80g / ton of raw ore, and the collector dosage is 10-30g / ton of raw ore; the regrinding fineness before the second concentration is 0.018mm, accounting for 80%-92%, and the dosage of reagents is reduced by 20%-30% compared with the previous concentration; the regrinding fineness before the third concentration is 0.018mm, accounting for 84%-93%, forming a stepped fineness and reagent gradient addition.

2. The graphite flotation process capable of improving the flotation efficiency according to claim 1, characterized in that: The α-olefin is a straight-chain α-olefin having 8 to 10 carbon atoms, and the fatty acid methyl ester has the molecular formula C7H 12 O4, and forms a stable collector system with the α-olefin by using propanol as a dispersant.

3. A graphite flotation process capable of improving flotation efficiency according to claim 1, characterized in that: The water glass with a modulus of 2.8-3.5, sodium hexametaphosphate and carboxymethyl cellulose in the inhibitor are compounded to form a synergistic inhibitory effect.

4. A graphite flotation process capable of improving flotation efficiency according to claim 1, characterized in that: The rough selection operation uses an air-agitated flotation machine with an air inflow of 0.6 - 1.0 m 3 / (m 2 ·min), a stirring speed of 1200 - 1800 r / min, and a flotation time of 3 - 5 min to achieve the preliminary separation of fine-grained graphite and gangue.

5. A graphite flotation process capable of improving flotation efficiency according to claim 1, characterized in that: In the above-mentioned concentration operation, the slurry after each re-grinding needs to be slurry-adjusted for 2-3 minutes to make the inhibitor and collector evenly dispersed in the slurry and improve the adsorption efficiency of the reagent and the graphite surface.

6. A graphite flotation process capable of improving flotation efficiency according to claim 1, characterized in that: In the three concentration operations, the amount of inhibitor used in the first concentration is 60-80g / ton of raw ore, and the amount of collector used is 20-30g / ton of raw ore; the amount of inhibitor used in the second concentration is 40-60g / ton of raw ore, and the amount of collector used is 10-20g / ton of raw ore; the amount of inhibitor used in the third concentration is 30-50g / ton of raw ore, and the amount of collector used is 5-15g / ton of raw ore, forming a gradient decrease in the amount of reagents.

7. A graphite flotation process capable of improving flotation efficiency according to claim 1, characterized in that: The vertical mill adopts a closed-circuit grinding process, and sodium carbonate with a mass concentration of 0.1%-0.3% is added as a grinding aid during the grinding process to improve the dissociation efficiency of graphite and gangue.

8. A graphite flotation process capable of improving flotation efficiency according to claim 1, characterized in that: During the flotation process, the pH value of the ore pulp is controlled at 8.0-9.5, and is adjusted by adding sodium hydroxide or hydrochloric acid solution with a mass concentration of 1%-3%, thereby ensuring the best working environment for the inhibitor and the collector.

9. The graphite flotation process capable of improving the flotation efficiency according to claim 1, wherein: The scavenging operation uses a shallow trough flotation machine, with a flotation time of 2 - 3 min and an air inflow of 0.5 - 0.8 m 3 / (m 2 ·min), and focuses on recovering the fine-grained graphite that is not fully dissociated in the rougher tailings.

10. A graphite flotation process capable of improving flotation efficiency according to claim 1, characterized in that: After the concentrate product is dehydrated by a thickener, it is dried by an air flow dryer at a drying temperature of 80-100° C. and a drying time of 15-20 minutes, and finally a graphite concentrate with a fixed carbon content of ≥90% is obtained.

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