A kind of micro-fine graphite flotation process

Abstract

The present invention discloses a low-grade micro-fine graphite flotation process, comprising the following steps: the raw ore is subjected to a grinding-roughing process after coarse crushing, medium crushing and fine crushing to obtain a coarse concentrate and a roughing tailing; the coarse concentrate is subjected to a re-grinding-double-selection process, which is repeated at least four times to obtain a graphite concentrate product; wherein a modified composite agent is added during the roughing operation; and the grade of the raw ore is not higher than 12%. By adopting the technical solution of the present invention, the flotation agent is modified to be a composite flotation agent, and the modified composite collector is in more sufficient contact with the micro-fine graphite, reducing the foam viscosity, and achieving a fixed carbon content of 96% and a recovery rate of 90% for the graphite concentrate product.

Description

Technical Field

[0001] The invention relates to the technical field of graphite purification in non-metallic minerals, and in particular to a micro-grain graphite flotation process method. Background Art

[0002] Graphite is a strategic mineral resource in my country. Due to its unique crystal structure, it has many excellent physical and chemical properties, such as excellent electrical and thermal conductivity, thermal shock resistance, plasticity, easy machining, lubricity, high temperature resistance, corrosion resistance and chemical stability. It is widely used in important sectors of the national economy such as refractory, environmental protection, metallurgy, machinery, chemical industry, electronics, etc. At present, with the annual increase in graphite consumption and demand, easy-to-select large flake graphite can no longer meet people's demand for graphite materials. The development of difficult-to-select fine-grained graphite and cryptocrystalline graphite has received more and more attention. High-purity fine-grained graphite is widely used in conductive coatings, lubricating coatings, powder metallurgy, lubricating oils, greases, civil nuclear power, aerospace, strategic power jamming weapons and smoke shielding weapons. Fine-grained graphite ore resources are widely distributed in my country, with large reserves, but due to the great difficulty of beneficiation of this type of graphite resources, the quality of existing products is not high, and there are not many developments and utilizations.

[0003] Different from crystalline graphite, the embedded particle size of fine-grained graphite is very fine, and the crystal particle size is far below the lower limit of the mineral flotation particle size. The flotation effect is poor, and the graphite is very slippery and difficult to grind, which makes it difficult to dissociate the graphite. The embedded particle size of graphite in difficult-to-select fine-grained graphite ores is usually 2-20 microns, the graphite flakes are fine, and the crystallinity is poor. The flotation recovery of fine-grained graphite has become a major problem in the field of graphite beneficiation, so the research on the flotation technology of fine-grained graphite has attracted more and more attention. The difficulty in flotation of fine-grained minerals is caused by their own characteristics such as fine particle size and large specific surface area. As the particle size decreases, the flotation behavior of mineral particles will change fundamentally. Fine-grained minerals have small mass and low momentum, resulting in a small probability of collision and adhesion between the collector and the bubbles, poor selectivity, and low flotation rate and recovery rate. At the same time, fine-grained minerals have a large specific surface area and severe non-selective adsorption of reagents, resulting in a large consumption of reagents. In addition, the symbiotic minerals are more susceptible to mudification during the ultrafine grinding process, which reduces the grade of the concentrate.

[0004] The existing technology usually adopts the process of adding flotation reagents combined with grinding-roughing-regrinding-cleaning, which usually requires 8 grinding-9 flotation processes to flotate fine graphite, but the flotation efficiency is often not high. The main reason is that the small particle size of fine graphite leads to poor binding strength with macromolecular oil reagents. In order to improve the flotation efficiency, a large amount of flotation reagents are often needed in the flotation process, which further leads to serious mud inclusion problems, resulting in low grade and recovery rate of fine graphite products.

[0005] At present, for fine-grained graphite, the roughing grinding fineness is usually 70-90% of -200 mesh, through a roughing process, the coarse concentrate is re-grinded in six to seven stages, and the eight to nine stages are finely refined, and the medium ore is returned upward in sequence. The conventional flotation process often consumes 5-10 times the usual reagents, and the carbon content of the flotation concentrate is less than 90%, and the carbon recovery rate is only 50-70%. Chinese invention patent CN108745656A discloses a method for improving the flotation efficiency of fine-grained graphite. The patent uses a graphite ore with a microcrystalline graphite content of 50-75%, and the crystals of graphite are 1 to 5 microns. Inhibitors and collectors are added to the pulp in sequence to perform roughing of graphite to obtain roughing concentrate and roughing tailings; the roughing concentrate is re-grinded, and inhibitors and collectors are added in sequence after re-grinding to perform fine selection to obtain concentrate products. The patent is aimed at high-grade fine-grained graphite. When the technical solution is used to float low-grade graphite ore, especially fine-grained graphite with a grade of less than 12%, the flotation effect is not ideal, and the flotation efficiency is far from reaching the technical effect of the patent. Obviously, there is no efficient flotation method for low-grade fine-grained graphite flotation. Summary of the invention

[0006] The purpose of the present invention is to provide a low-grade fine-grained graphite flotation process method, to optimize the process for low-grade fine-grained graphite ore, to ultrasonically modify the collector by adding a modifier, to convert the collector macromolecules into small molecules, to enhance the selective adsorption of the agent on the fine-grained graphite particles, to reduce the addition amount of the collector agent, and to improve the flotation recovery rate.

[0007] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a low-grade fine-grained graphite flotation process, comprising the following steps: the raw ore is subjected to a grinding-roughing process after coarse crushing, medium crushing and fine crushing to obtain a coarse concentrate and a roughing tailing; the coarse concentrate is subjected to a regrinding-twice concentration process, which is repeated at least four times to obtain a graphite concentrate product; wherein an emulsion-like modified composite agent is added in the roughing operation; the grade of the raw ore is not higher than 12%; the fixed carbon content of the graphite concentrate product is 96%, and the recovery rate is 90%.

[0008] Furthermore, the modified composite agent includes a modifier, a collector and water; the modifier includes one or more of emulsifiers OP-10, Tween 80, emulsifier NP-7, and LAE-9; the collector is diesel and 2# oil; the collector and water are configured in proportion and then the modifier is added, and ultrasonic modification is performed at 40-70°C for 30-60 minutes to form an emulsion solution.

[0009] Furthermore, in the composite modifier, the mass ratio of diesel: 2# oil: the modifier: water is 1:0.5-1:0.5-3:95-98.

[0010] Furthermore, in the modified composite agent, the collector content is 250-500 g / t; the concentration of diesel + 2# oil is 10-20 g / L.

[0011] Furthermore, in the roughing process, the grinding concentration of the first stage of rough grinding is 50-60wt%, and the grinding fineness of -200 mesh accounts for 80-95%.

[0012] Furthermore, the coarse concentrate is re-grinded by a vertical sand mill, and a dispersant is added in the vertical sand mill. The dispersant is sodium hexametaphosphate, and the addition amount is 20-100 g / t.

[0013] Furthermore, in the above-mentioned concentration operation, an ultrasonic device is provided in the flotation tank, and the frequency of the ultrasonic generator is ≥25KHz.

[0014] Furthermore, the roughing tailings are supplemented with flotation reagents for a scavenging, and the amount of scavenging reagents used is 50-100 g / t, to obtain middlings 1 and tailings 1.

[0015] Furthermore, the selected coarse ore is subjected to four-stage regrinding-two-stage concentrating processes to obtain a graphite concentrate product; the following steps are included in sequence:

[0016] Stage I regrinding - concentrating 1 - concentrating 2, to obtain middling 2, middling 3 and coarse concentrate; the fineness of stage I regrinding is D 90 =25μm, D 50 =16μm; the amount of sodium hexametaphosphate added in the vertical sand mill is 50-100g / t;

[0017] The second stage re-grinding-concentration 3-concentration 4 obtains the middling ore 4, middling ore 5 and coarse concentrate; the fineness of the second stage re-grinding is D 90 =23μm, D 50 =13μm,

[0018] The third stage re-grinding-concentration 5-concentration 6 obtains the intermediate ore 6, intermediate ore 7 and coarse concentrate; the amount of sodium hexametaphosphate added is 20-40g / t; the third stage re-grinding fineness is D 90 =18μm, D 50 =12μm;

[0019] The fourth stage regrinding-concentration 7-concentration 8 obtains the middling ore 8, middling ore 9 and concentrate products; the fineness of the fourth stage regrinding is D 90 =15μm, D 50 =8μm;

[0020] The intermediate ore 1, the intermediate ore 2 and the intermediate ore 3 are combined for intermediate ore regrinding, and the fineness of the intermediate ore regrinding is D 90 =25μm, D 50=15μm; the slurry obtained by grinding the middling ore again is subjected to a fine scavenging process to obtain a middling ore 10 and a tailing 2, the amount of the collector is 50-100g / t, and the tailing 2 is combined with the tailing 1 to obtain the final total tailing;

[0021] The middling ore 4 is returned to the roughing operation; the middling ore 5, the middling ore 6, and the middling ore 10 are combined and returned to the concentrating operation 1; the middling ore 7, the middling ore 8, and the middling ore 9 are combined and returned to the concentrating operation 3.

[0022] In view of the above technical solution, the method of adding a modifier to the collector adopts ultrasonic modification to emulsify the collector and the modifier to form an emulsion, convert the collector macromolecules into small molecules, and improve the adsorption of the collector to fine-grained graphite, that is, to improve the binding strength between the fine-grained graphite flakes and the flotation reagent, improve the flotation efficiency, and thus improve the recovery rate. At the same time, adding a dispersant to the regrinding mill and adding an ultrasonic device to the concentrating flotation tank strengthens the dispersion and cleaning effect of the concentrating operation graphite and the ore mud, reduces the amount of mud entrained in the foam, and improves the concentrate grade.

[0023] Through the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0024] 1. By adopting the technical solution of the present invention, the flotation reagent is ultrasonically modified to prepare an emulsion-like composite flotation reagent. The modified composite collector is emulsified from macromolecules to form small molecules, so that the contact with the fine-grained graphite is more sufficient, the foam viscosity is reduced, the reagent dosage is small, and the recovery rate can reach 90%.

[0025] 2. The technical solution of the present invention is adopted, by adding dispersants in the concentration and regrinding operation, adding ultrasonic devices in the concentration flotation equipment, increasing the number of flotation stages after regrinding, and synergizing dispersants and ultrasonic cleaning to strengthen the hydrophilicity of the surface of fine-grained ore mud, so as to achieve the separation of gangue ore mud and graphite, quickly improve the product grade, greatly reduce the number of regrinding stages, and reduce the ore dressing cost.

[0026] 3. The technical solution of the present invention is adopted to combine the scavenged ore and the primary regrinding ore for concentrated regrinding and re-selection, and the re-selected tailings are directly discarded, which can avoid a large amount of fine gangue ore slime returning to the flotation process, can quickly improve the product grade, greatly reduce the impact of fine ore slime on the entire flotation process, achieve early discarding of tailings, and the entire flotation process is easier to operate, and can take into account both product quality and recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Graphite flotation process flow chart of Example 1 of the present invention. DETAILED DESCRIPTION

[0028] The invention discloses a flotation process for low-grade fine-grained graphite. The raw ore is subjected to coarse crushing, medium crushing and fine crushing, and then subjected to a grinding-roughing process to obtain a coarse concentrate and a roughing tailing. The coarse concentrate is subjected to a regrinding-twice concentrating process, which is repeated at least four times to obtain a graphite concentrate product.

[0029] Among them, an emulsion-like modified composite agent is added in the roughing operation; the grade of the original ore is not higher than 12%; the fixed carbon content of the graphite concentrate product is 96%, and the recovery rate is 90%.

[0030] Furthermore, the modified composite agent includes a modifier, a collector and water; the modifier includes one or more of emulsifiers OP-10, Tween 80, emulsifier NP-7, and LAE-9; the collector is diesel and 2# oil; the collector and water are configured in proportion and then the modifier is added, and ultrasonic modification is performed at 40-70° C. for 30-60 minutes to form an emulsion solution.

[0031] Furthermore, in the modified composite agent, the mass ratio of diesel: 2# oil: modifier: water is 1:0.5~1:0.5~3:95~98; the total concentration of diesel and 2# oil is 10-20g / L, the amount of collector added is 250-500g / t; the concentration of diesel + 2# oil is 10-20g / L.

[0032] Furthermore, in the roughing process, the grinding concentration of the rough grinding is 50-60wt%, and the grinding fineness -200 mesh accounts for 80-95%; the pulp concentration in the roughing process is 20-35wt%.

[0033] The coarse concentrate is re-grinded by a vertical sand mill, and a dispersant is added in the vertical sand mill. The dispersant is sodium hexametaphosphate, and the addition amount is 20-100g / t. Sodium hexametaphosphate is used as a dispersant to improve the surface hydrophilicity of fine-grained ore mud, and with the help of an ultrasonic cleaning device, the gangue ore mud and graphite are separated, and the product grade is quickly improved.

[0034] Further, the coarse concentrate is subjected to four-stage regrinding and two-stage concentration processes to obtain a graphite concentrate product; the following steps are included in sequence:

[0035] Stage I regrinding - concentrating 1 - concentrating 2, to obtain middling 2, middling 3 and coarse concentrate; the fineness of stage I regrinding is D 90 =25μm, D 50 =16μm; the amount of sodium hexametaphosphate added in the vertical sand mill is 50-100g / t;

[0036] Ⅱ stage regrinding - concentrating 3 - concentrating 4, to obtain medium ore 4, medium ore 5 and coarse concentrate; the amount of sodium hexametaphosphate added is 40-80g / t; the fineness of Ⅱ stage regrinding is D 90 =23μm, D 50 =13μm,

[0037] Stage III regrinding - concentrating 5 - concentrating 6, to obtain middling 6, middling 7 and coarse concentrate; the amount of sodium hexametaphosphate added is 20-40g / t; the regrinding fineness of stage III is D 90 =18μm, D 50 =12μm;

[0038] Stage IV regrinding - concentrating 7 - concentrating 8, to obtain middling 8, middling 9 and concentrate products; the fineness of stage IV regrinding is D 90 =15μm, D 50 =8μm;

[0039] Middlings 1, 2 and 3 are combined for regrinding, and the fineness of regrinding is D 90 =25μm, D 50 =15μm; the slurry obtained by grinding the middling ore is subjected to fine scavenging process to obtain middling ore 10 and tailings 2, the amount of collector used is 50-100g / t, and the tailings 2 and tailings 1 are combined to obtain the final total tailings;

[0040] Middling ore 4 is returned to the roughing operation; middling ore 5, middling ore 6 and middling ore 10 are combined and returned to the concentrating operation 1; middling ore 7, middling ore 8 and middling ore 9 are combined and returned to the concentrating operation 3.

[0041] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in combination with the specific content of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.

[0042] Example 1

[0043] The raw ore used in this embodiment is fine-grained graphite from Northeast China, with a raw ore grade of 6% and a graphite embedding particle size of 2-20 μm.

[0044] See also Figure 1 The raw ore is subjected to coarse crushing, medium crushing and fine crushing, and then subjected to a roughing grinding process to obtain a roughing concentrate and a roughing tailing; the roughing grinding concentration is 50-60wt%, and the roughing grinding fineness is -200 mesh, accounting for 80-95%. Preferably, a modified composite agent is added in the roughing operation.

[0045] The modified composite agent includes a modifier and a collector; the modifier is one or more of emulsifiers OP-10, Tween 80, emulsifier NP-7, and LAE-9; the collector is diesel and 2# oil, and the amount of the collector added is 250g / t. Furthermore, in the modified composite agent, the mass ratio of diesel: 2# oil: modifier: water is 1:1:1:97; and the total concentration of diesel and 2# oil is 10g / L.

[0046] The collector and water are prepared in proportion, and then the modifier is added, and the modified composite agent is formed by ultrasonic modification at 40-70°C for 30 minutes.

[0047] Furthermore, a flotation agent is added to the rough tailings for a scavenging process to obtain a middling ore 1 and a tailing 1, and the amount of the scavenging agent used is 50-100 g / t.

[0048] The rougher concentrate is ground and a vertical sand mill is used to grind the concentrate to obtain the selected pulp. Sodium hexametaphosphate is added to the vertical sand mill. The rougher concentrate is then subjected to four stages of fine grinding and eight rounds of fine grinding to obtain graphite concentrate products. The fine separation process uses a flotation cell and an ultrasonic device, and the frequency of the ultrasonic generator is ≥25KHz.

[0049] Specifically, the four-stage concentrating grinding-eight-stage concentrating process includes:

[0050] (1) Stage I regrinding - concentrating 1 - concentrating 2, to obtain middling 2, middling 3 and coarse concentrate; the fineness of stage I regrinding is D 90 =25μm, D 50 =16μm; the amount of sodium hexametaphosphate added in the vertical sand mill is 50-100g / t;

[0051] (2) Stage II regrinding - concentrating 3 - concentrating 4, to obtain middling 4, middling 5 and coarse concentrate; the fineness of the stage II regrinding is D 90 =23μm, D 50 =13μm,

[0052] (3) regrinding in stage III - concentrating 5 - concentrating 6, obtaining medium ore 6, medium ore 7 and coarse concentrate; the amount of sodium hexametaphosphate added is 20-40g / t; the regrinding fineness in stage III is D 90 =18μm, D 50 =12μm;

[0053] (4) Stage IV regrinding - concentrating 7 - concentrating 8, to obtain middlings 8, middlings 9 and concentrate products; the fineness of the stage IV regrinding is D 90 =15μm, D 50 =8μm;

[0054] After the middlings 1, 2 and 3 are combined, they are regrinded. The regrinding fineness is D 90 =25μm, D 50 =15μm; further, the slurry obtained by regrinding the middling ore is added with a collector for fine scavenging process to obtain middling ore 10 and tailings 2, the amount of collector used is 50-100g / t, and tailings 2 are combined with tailings 1 to obtain the final total tailings; wherein, the collector can be the same collector as the roughing collector.

[0055] Middlings 4 are returned to the roughing operation and combined with the slurry obtained from the roughing grinding to carry out the roughing process; middlings 5, 6 and 10 are combined and returned to the slurry obtained from the re-grinding of stage I for the concentration 1 operation; middlings 7, 8 and 9 are combined and returned to the slurry obtained from the re-grinding of stage II for the concentration 3 operation.

[0056] Through the process of mineral processing, a concentrate yield of 5.63%, a concentrate fixed carbon grade of 96.20% and a recovery rate of 90.34% were obtained.

[0057] Example 2

[0058] The difference between this embodiment and embodiment 1 is that the ratio of the modified composite agent is diesel: 2# oil: modifier: water in a mass ratio of 1:1:0.5:97.5. Through the process flow, a concentrate yield of 5.54%, a concentrate fixed carbon grade of 95.90%, and a recovery rate of 88.55% are obtained.

[0059] Example 3

[0060] The difference between this embodiment and embodiment 1 is that the ratio of the modified composite agent added in the roughing grinding is 1:1:3:95 of diesel:2# oil:modifier:water. Through the process of mineral processing, the concentrate yield is 5.65%, the fixed carbon grade of the concentrate is 95.86%, and the recovery rate is 90.26%.

[0061] Example 4

[0062] The difference between this embodiment and embodiment 1 is that the amount of collector added in the modified composite agent (diesel and 2# oil) is 500 g / t, and the total concentration is 10 g / L.

[0063] Through the process of mineral processing, a concentrate yield of 5.70%, a concentrate fixed carbon grade of 95.65% and a recovery rate of 90.86% were obtained.

[0064] Example 5

[0065] The difference between this embodiment and embodiment 1 is that the amount of collector added in the modified composite agent (diesel and 2# oil) is 250 g / t, and the total concentration is 20 g / L.

[0066] Through the process of mineral processing, a concentrate yield of 5.42%, a concentrate fixed carbon grade of 96.30% and a recovery rate of 86.99% were obtained.

[0067] Example 6

[0068] The difference between this embodiment and embodiment 1 is that the modification condition of the modified composite agent is ultrasonic modification at 40-70° C. for 60 minutes.

[0069] Through the process of mineral processing, a concentrate yield of 5.65%, a concentrate fixed carbon grade of 96.90% and a recovery rate of 91.24% were obtained.

[0070] Example 7

[0071] The difference between this embodiment and embodiment 1 is that the modifier in the modified composite agent is Tween 80 and emulsifier NP-7.

[0072] Through the process of mineral processing, a concentrate yield of 5.59%, a concentrate fixed carbon grade of 96.15% and a recovery rate of 89.57% were obtained.

[0073] Example 8

[0074] The difference between this embodiment and embodiment 1 is that the modifiers in the modified composite agent are OP-10 and LAE-9.

[0075] Through the process of mineral processing, a concentrate yield of 5.65%, a concentrate fixed carbon grade of 96.20% and a recovery rate of 90.58% were obtained.

[0076] Example 9

[0077] The difference between this embodiment and embodiment 1 is that the modifier in the modified composite agent is emulsifier OP-10.

[0078] Through the process of mineral processing, a concentrate yield of 5.70%, a concentrate fixed carbon grade of 96.18% and a recovery rate of 91.37% were obtained.

[0079] Example 10

[0080] A fine-grained graphite from Henan was selected as the raw ore, with a grade of 8.6% and a graphite particle size of 2-30 μm. The technical solution of Example 1 was used for flotation.

[0081] Through this process, a concentrate yield of 8.12%, a concentrate fixed carbon grade of 95.45% and a recovery rate of 90.12% were obtained.

[0082] Comparative Example 1

[0083] The difference from Example 1 is that no modifier is added, and the collector is directly added without modifying the collector. The other steps are the same.

[0084] Through the process of mineral processing, a concentrate yield of 4.83%, a concentrate fixed carbon grade of 85.34% and a recovery rate of 68.69% were obtained.

[0085] Comparative Example 2

[0086] The difference from Example 1 is that the ratio of the modified composite agent added in the roughing grinding is 1:1:0.2:97.8 of diesel:2# oil:modifier:water. Through the process of mineral processing, the concentrate yield is 5.30%, the fixed carbon grade of the concentrate is 91.25%, and the recovery rate is 80.60%.

[0087] Comparative Example 3

[0088] The difference from Example 1 is that in the modified composite agent, the collector (diesel and 2# oil), the modifier and water are directly mixed in the same mass ratio as in the example, without ultrasonic modification.

[0089] Through the process of mineral processing, a concentrate yield of 5.05%, a concentrate fixed carbon grade of 92.38% and a recovery rate of 77.75% were obtained.

[0090] Comparative Example 4

[0091] The difference between this comparative example and Example 1 is that sodium hexametaphosphate is not added; through the process flow, a concentrate yield of 5.85%, a concentrate fixed carbon grade of 93.57%, and a recovery rate of 91.23% are obtained.

[0092] The difference between this embodiment and Example 1 is that in the concentrating operation, no ultrasonic device is provided in the flotation tank.

[0093] Through the process of mineral processing, a concentrate yield of 5.86%, a concentrate fixed carbon grade of 93.93% and a recovery rate of 91.73% were obtained.

[0094] It can be seen from the results of the embodiments and the control examples that adding a modifier to the collector can greatly improve the recovery rate of the concentrate. Since the collector will produce a large amount of foam, and for fine-grained graphite, especially low-grade fine-grained graphite, its particle size is small, the macromolecular foam formed by the ordinary collector has a low force on the fine-grained graphite sheet. In order to improve the collection effect, a high recovery rate is often achieved by increasing the amount of the collector. However, due to the large amount of collector added, a large amount of highly viscous foam layers are generated in the flotation tank, which is easy to be entrained with mud, resulting in the concentrate grade not being able to achieve the expected, and it is necessary to increase the number of grinding and selection stages to further improve the recovery rate. The present invention adds a modifier to the collector to form an emulsion-like solution by ultrasonic modification, and the modified collector macromolecules are converted into small molecules, increasing the binding effect of the collector and fine-grained graphite, and improving selectivity. At the same time, an ultrasonic device is installed in the flotation tank to reduce the amount of foam entrainment, thereby further improving the concentrate grade.

[0095] Furthermore, by using an ultrasonic cleaning device in the concentration stage, assisted by the dispersant sodium hexametaphosphate added in the grinding, the two work synergistically and jointly strengthen the hydrophilicity of the surface of the fine-grained ore mud, thereby achieving the separation of the gangue ore mud and graphite, and rapidly improving the product grade.

[0096] The technical solution of the present invention greatly reduces the number of concentration stages, especially the number of grinding times. On the one hand, it simplifies the process flow and reduces energy consumption. On the other hand, in the low-stage concentration process stage, the fixed carbon content of the concentrate product that can be obtained is ≥96%, and the recovery rate is ≥90%, which provides a new idea for the mining of low-grade fine-grained graphite.

[0097] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A low-grade fine-grain graphite flotation process, characterized in that: The following steps are involved: The raw ore is subjected to a grinding-roughing process after coarse crushing, medium crushing and fine crushing to obtain a coarse concentrate and a roughing tailing; the coarse concentrate is subjected to a regrinding-twice concentrating process, which is repeated at least four times to obtain a graphite concentrate product; Wherein, a modified composite agent in the form of an emulsion is added during the roughing operation; The grade of the raw ore is not higher than 12%; The graphite concentrate product has a fixed carbon content of 96% and a recovery rate of 90%; The modified composite reagent comprises a modifier, a collector and water; The modifier includes one or more of emulsifier OP-10, Tween 80, emulsifier NP-7, and LAE-9; The collector is diesel and 2# oil; The collector and water are prepared in proportion, and then the modifier is added, and ultrasonic modification is performed at 40-70° C. for 30-60 minutes to form an emulsion solution; In the modified composite agent, the mass ratio of diesel: 2# oil: the modifier: water is 1:0.5~1:0.5~3:95~98; The coarse concentrate is regrinded by a vertical sand mill, and a dispersant is added in the vertical sand mill; The dispersant is sodium hexametaphosphate; The coarse concentrate is subjected to four-stage regrinding and two-stage concentration processes to obtain a graphite concentrate product; the process comprises: Stage I regrinding - concentrating 1 - concentrating 2, to obtain medium ore 2, medium ore 3 and coarse concentrate; the fineness of the stage I regrinding is D90=25μm, D50=16μm; the amount of sodium hexametaphosphate added in the vertical sand mill is 50-100g / t; Stage II regrinding - concentrating 3 - concentrating 4, to obtain middling 4, middling 5 and coarse concentrate; the amount of sodium hexametaphosphate added is 40-80g / t; the fineness of the stage II regrinding is D90=23μm, D50=13μm; Stage III regrinding-concentrating 5-concentrating 6, to obtain middling 6, middling 7 and coarse concentrate; the amount of sodium hexametaphosphate added is 20-40g / t; the regrinding fineness of stage III is D90=18μm, D50=12μm; Stage IV regrinding - concentrating 7 - concentrating 8, to obtain middlings 8, middlings 9 and concentrate products; the fineness of the stage IV regrinding is D90 = 15 μm, D50 = 8 μm; Adding flotation reagent to the roughing tailings for a scavenging, the flotation reagent dosage is 50-100 g / t, and obtaining a middling ore 1 and a tailing 1; The middling ore 1, the middling ore 2 and the middling ore 3 are combined for middling regrinding, and the fineness of the middling ore regrinding is D90=25μm, D50=15μm; the slurry obtained by the middling regrinding is subjected to a fine scavenging process to obtain a middling ore 10 and tailings 2, the amount of the collector is 50-100g / t, and the tailings 2 are combined with the tailings 1 to obtain the final total tailings; The intermediate ore 4 is returned to the roughing operation; the intermediate ore 5, intermediate ore 6, and intermediate ore 10 are combined and returned to the concentrating operation 1; the intermediate ore 7, intermediate ore 8, and intermediate ore 9 are combined and returned to the concentrating operation 3; In the above-mentioned beneficiation process, an ultrasonic device is provided in the flotation tank.

2. The low-grade fine-grain graphite flotation process according to claim 1, characterized in that: In the modified composite agent, the collector content is 250-500 g / t; the concentration of diesel + 2# oil is 10-20 g / L.

3. The low-grade fine-grain graphite flotation process according to claim 1, characterized in that: In the roughing process, the grinding concentration of the rough grinding is 50-60wt%, and the grinding fineness of -200 mesh accounts for 80-95%.

4. The low-grade fine-grain graphite flotation process according to claim 1, characterized in that: The frequency of the ultrasonic generator of the ultrasonic device is ≥25KHz.

Images