Beneficiation method of fine-grained disseminated lean iron ore

Abstract

This invention discloses a beneficiation method for fine-grained disseminated lean iron ore. First, the fine-grained disseminated lean iron ore is pre-selected to obtain ore to be ground. Then, the ore is ball-milled with the aid of nano-surfactants. Next, a flocculant is added for desliming. Finally, a collector is added for flotation, concentration, and filtration to obtain iron concentrate. The beneficiation method of this invention is simple, achieves efficient utilization of fine-grained disseminated lean iron ore, improves grade, and has a high recovery rate.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing technology, specifically relating to a mineral processing method for finely disseminated lean iron ore. Background Technology

[0002] With the continuous development of the industrial economy, the demand for steel has increased accordingly, and iron ore is the main raw material for steel production. Large-scale steel production has led to a surge in demand for iron ore, exacerbating the already acute shortage. Therefore, the in-depth development and utilization of iron ore resources is key to alleviating the current iron ore shortage.

[0003] In recent years, reserves of rich iron ore and easily beneficiated lean iron ore have become increasingly scarce, while reserves of difficult-to-benefit fine-grained disseminated lean iron ore have become relatively abundant, making them a key target for iron ore resource development. However, fine-grained disseminated lean iron ore is characterized by its small mass, large specific surface area, and low specific magnetic susceptibility, making it difficult to effectively recover using traditional beneficiation methods, resulting in significant slurry loss and high beneficiation difficulty. Effective development of difficult-to-benefit fine-grained disseminated lean iron ore could undoubtedly greatly alleviate the current predicament of iron ore shortage.

[0004] In the mineral processing stage, to make rational use of refractory iron ores characterized by low grade, fine particle size, and complex coexistence, the ore needs to undergo crushing, fine grinding, desliming, and flotation. Specifically, the purpose of fine grinding is to liberate the valuable minerals, thus providing a good foundation for subsequent beneficiation operations. It can be said that the fine grinding process directly determines the degree of liberation of the valuable minerals. However, the secondary and primary slime generated during fine grinding can severely deteriorate the flotation concentrate indicators. Therefore, appropriate fine grinding and desliming processes before flotation are crucial.

[0005] Most existing fine grinding processes are achieved through vertical stirred mills or ball mills. The former has problems such as low single-unit processing capacity and high equipment price, while the latter has problems such as unsuitable length-to-diameter ratio of ball mill, unreasonable grinding media, and unsuitable classification equipment, resulting in poor monomer dissociation and unsatisfactory mineral processing indicators.

[0006] Most existing desliming processes are achieved through hydrocyclones, which are effective for removing low-density, fine-particle-size slime. However, the desliming effect of hydrocyclones is prone to fluctuation and is easily affected by factors such as feed concentration and pressure.

[0007] Overall, existing fine grinding and desliming technologies have poor liberation properties for iron ore and cannot effectively remove ore slime, thus failing to provide qualified raw materials for subsequent flotation operations and hindering the effective development and utilization of finely disseminated lean iron ore.

[0008] Patent application CN104399578B discloses a pre-selection method for low-grade hematite-containing waste rock. The method involves crushing the raw waste rock (18-23% iron content) to 40-0mm using coarse and medium crushing operations, followed by pre-selection using a permanent magnet dry high-intensity magnetic separator. The magnetic field strength on the surface of the separator's cylinder is 0.8-1.0T. By controlling the cylinder surface linear velocity, separation baffle distance, and material layer thickness, coarse tailings with an iron content <14.0% are removed. The resulting coarse concentrate is then ground to 10-0mm using a high-pressure roller mill and pre-selected using an electromagnetic pulsating high-gradient coarse wet high-intensity magnetic separator, where fine tailings with an iron content ≤11% are removed. The coarse concentrate obtained from the electromagnetic pulsating high-gradient coarse wet high-intensity magnetic separator is fed into the main plant's grinding and beneficiation process. However, the final product obtained using this patented technology still has a relatively low grade.

[0009] Patent application CN102886301A discloses a method for beneficiating hematite. This method effectively beneficiates low-grade hematite by controlling the particle size of the ore powder, the type of magnetic separator, and especially by using multi-stage magnetic separation with different magnetic field intensities. The resulting iron concentrate has a grade below 60% and a recovery rate of approximately 60%. However, the beneficiation effect of this patented technology is generally mediocre. Summary of the Invention

[0010] To address the shortcomings of existing technologies, the present invention aims to provide a beneficiation method for finely disseminated lean iron ore, thereby improving grade and increasing recovery rate.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] A beneficiation method for finely grained, disseminated lean iron ore, comprising the following specific steps:

[0013] (1) First, the fine-grained disseminated lean iron ore is pre-selected to obtain the ore to be ground. Then, the ore to be ground is ball-milled under the grinding aid of nano surfactants.

[0014] (2) Then add flocculant for sludge removal;

[0015] (3) Finally, a collector is added, and flotation, concentration, and filtration are carried out to obtain iron concentrate;

[0016] The nano-surfactant is obtained by loading nano-octadecylamine citrate onto a coal tar residue nanomatrix; the flocculant is obtained by mixing sodium polyacrylate, ammonium humate and sodium hexametaphosphate in equal mass; and the collector is obtained by compounding nano-silica and pine oil.

[0017] Preferably, the fine-grained, low-grade iron ore has an iron content of 18-20% and its main component is hematite.

[0018] Preferably, the nano-surfactant is prepared by the following method, based on parts by weight: first, 2-3 parts of citric acid and 1 part of octadecylamine are mixed evenly and reacted with microwave to obtain nano-octadecylamine citrate; then, 20-25 parts of coal tar residue are thermally polymerized under an inert gas atmosphere to obtain coal tar residue nano matrix; then, the nano-octadecylamine citrate and the coal tar residue nano matrix are evenly dispersed in 120-130 parts of water, the supernatant is collected by centrifugation and dried to obtain the final product.

[0019] Further preferred microwave reaction process conditions are: frequency 2-3 GHz, power 800-1000 W, and reaction time 40-50 minutes.

[0020] Further preferably, the inert gas is argon or helium.

[0021] Further preferred, the process conditions for thermal polymerization are: heating to 550-650℃ at a rate of 2-3℃ / min, and thermal polymerization reaction for 2-3 hours.

[0022] Further preferred centrifugation conditions are: centrifugation at 60,000–70,000 r / min for 10–15 minutes.

[0023] Preferably, the collector is prepared by the following method, by weight: 1 part of nano silica and 0.1 to 0.2 parts of octylphenol polyoxyethylene ether are added to 5 to 7 parts of pine oil, ultrasonically vibrated at 500 to 600 W for 30 to 40 minutes, transferred to a ball mill, and ball milled for 6 to 7 hours using steel balls with a diameter of 0.020 mm and a material-to-ball ratio of 1:1.

[0024] Preferably, in step (1), the specific method of pre-selection is as follows: first, the fine-grained disseminated lean iron ore is initially crushed to 40-45mm, then high-pressure roller milled to 5-7mm, and a wet strong magnetic separator is used with a magnetic field strength of 0.8-1T, a pulse frequency of 500-600 times / min, and a linear speed of 2-2.2 rpm to remove the fine tailings with an iron grade of less than 12%, thus obtaining the ore to be ground.

[0025] More preferably, the gap between the rollers in the high-pressure roller mill is 10–15 mm.

[0026] Preferably, in step (1), the specific method of ball milling is as follows: water is added to the ore to be milled to adjust it to a slurry with a mass concentration of 55-65%, then nano surfactants are added to the slurry, and ball milling is carried out by a wet overflow ball mill, using steel balls with diameters of 35mm, 25mm, and 20mm, with a mass ratio of 2:3:5, a material-to-ball ratio of 0.8, and a media filling rate of 40-45%; ball milling is carried out until the average particle size is -15μm.

[0027] More preferably, the amount of nano-surfactant used is 0.8 to 1‰ of the slurry mass.

[0028] Preferably, in step (2), water is added to adjust the mass concentration of the slurry to 13-15%, 1-2 mol / L sodium hydroxide solution is used to control the pH of the slurry to 9-10, flocculant is added, and the mixture is stirred for 2-3 minutes to achieve desliming through a hydrocyclone.

[0029] More preferably, the amount of flocculant used is 0.08 to 0.1‰ of the mass of the slurry after water adjustment.

[0030] Further preferably, the diameter of the hydrocyclone feed inlet is 60–90 mm.

[0031] Preferably, in step (3), water is added to adjust the mass concentration of the slurry to 8-10%, 1-2 mol / L hydrochloric acid solution is used to adjust the pH of the slurry to 7, collector is added and stirred for 2-3 minutes, and flotation is carried out using a flotation machine with a stirring speed of 1800-2000 r / min for 2-3 minutes.

[0032] More preferably, the amount of collector used is 0.2 to 0.3‰ of the mass of the slurry after water adjustment.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] This invention discloses a beneficiation method for fine-grained disseminated lean iron ore. First, the fine-grained disseminated lean iron ore is pre-selected to obtain ore to be ground. Then, the ore is ball-milled with the aid of nano-surfactants. Next, a flocculant is added for desliming. Finally, a collector is added for flotation, concentration, and filtration to obtain iron concentrate. The beneficiation method of this invention is simple, achieves efficient utilization of fine-grained disseminated lean iron ore, improves grade, and has a high recovery rate.

[0035] This invention employs a low-cost ball milling process, incorporating a nano-surfactant during the milling process to aid grinding. The nano-surfactant is prepared by the following method: first, citric acid and octadecylamine are mixed uniformly and reacted via microwave to obtain nano-octadecylamine citrate; then, coal tar residue is thermally polymerized under an inert gas atmosphere to obtain a coal tar residue nanomatrix; finally, the nano-octadecylamine citrate and the coal tar residue nanomatrix are uniformly dispersed in water, the supernatant is collected by centrifugation, and dried to obtain the final product. This nano-surfactant adjusts the surface charge distribution of particles during ball milling, improves slurry flowability, promotes ball milling, reduces ball milling energy consumption, and improves ball milling efficiency.

[0036] After ball milling, a flocculant is added for desliming. The flocculant is a mixture of sodium polyacrylate, ammonium humate, and sodium hexametaphosphate in equal mass. Through the synergistic effect of sodium polyacrylate, ammonium humate, and sodium hexametaphosphate, the effective removal of sludge is achieved.

[0037] After desliming, a collector is added for flotation. The collector is a compound of nano-silica and pine oil, prepared as follows: nano-silica and octylphenol polyoxyethylene ether are added to pine oil, ultrasonically vibrated, and then transferred to a ball mill for ball milling. Pine oil itself has good collecting properties; when compounded with nano-silica, it promotes adsorption on the particle surface, enhancing the collecting effect. Detailed Implementation

[0038] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not 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 effort are within the scope of protection of the present invention.

[0039] Unless otherwise specified, all products in this invention were purchased through market channels.

[0040] The fine-grained disseminated lean iron ore in the following examples and comparative examples was mined from the same iron ore surface deposit, and its main component was hematite with an iron grade of 18%.

[0041] Example 1

[0042] A beneficiation method for finely grained, disseminated lean iron ore, comprising the following specific steps:

[0043] (1) First, the fine-grained disseminated lean iron ore is pre-selected to obtain the ore to be ground. Then, the ore to be ground is ball-milled under the grinding aid of nano surfactants.

[0044] (2) Then add flocculant (sodium polyacrylate, ammonium humate and sodium hexametaphosphate mixed by mass) to carry out sludge removal treatment;

[0045] (3) Finally, a collector is added, and flotation, concentration, and filtration are carried out to obtain iron concentrate;

[0046] The nano surfactant was prepared by the following method: 2 kg of citric acid and 1 kg of octadecylamine were mixed evenly and reacted with microwave to obtain nano octadecylamine citrate. Then, 20 kg of coal tar residue was thermally polymerized under a helium atmosphere to obtain coal tar residue nano matrix. The nano octadecylamine citrate and coal tar residue nano matrix were then evenly dispersed in 120 kg of water, centrifuged to obtain the supernatant, and dried to obtain the final product.

[0047] The microwave reaction process conditions are: frequency 2GHz, power 800W, and reaction time 40 minutes.

[0048] The process conditions for thermal polymerization are as follows: the temperature is increased to 550℃ at a rate of 2℃ / min, and the thermal polymerization reaction is carried out for 2 hours.

[0049] The centrifugation process conditions are: centrifugation at 60,000 r / min for 10 minutes.

[0050] The collector is prepared by the following method: 1 kg of nano silica and 0.1 kg of octylphenol polyoxyethylene ether are added to 5 kg of pine oil and ultrasonically vibrated at 500 W for 30 minutes. The mixture is then transferred to a ball mill and ball milled for 6 hours using steel balls with a diameter of 0.020 mm and a material-to-ball ratio of 1:1.

[0051] In step (1), the specific method for pre-selection is as follows: First, the fine-grained disseminated lean iron ore is initially crushed to 40mm, then ground to 5mm using a high-pressure roller mill. A wet high-intensity magnetic separator is then used with a magnetic field strength of 0.8T, a pulse stroke rate of 500 times / min, and a linear speed of 2 revolutions / min. Fine tailings with an iron grade of less than 12% are removed, thus obtaining the ore to be ground. The gap between the rollers of the high-pressure roller mill is 10mm.

[0052] In step (1), the specific method of ball milling is as follows: water is added to the ore to be milled to adjust the slurry to a mass concentration of 55%. Then, nano-surfactants are added to the slurry, and ball milling is carried out using a wet overflow ball mill. Steel balls with diameters of 35mm, 25mm, and 20mm are used, with a mass ratio of 2:3:5, a material-to-ball ratio of 0.8, and a media filling rate of 40%. The ball milling is carried out until the average particle size is 15μm. The amount of nano-surfactants used is 0.8‰ of the slurry mass.

[0053] In step (2), water is added to adjust the slurry concentration to 13%, and a 1 mol / L sodium hydroxide solution is used to control the slurry pH to 9. Flocculant is added, and the mixture is stirred for 2 minutes. Desliming is then achieved using a hydrocyclone. The amount of flocculant used is 0.08‰ of the slurry mass after water adjustment. The hydrocyclone feed inlet diameter is 60 mm.

[0054] In step (3), water is added to adjust the mass concentration of the slurry to 8%, and 1 mol / L hydrochloric acid solution is used to adjust the pH of the slurry to 7. After adding the collector, the mixture is stirred for 2 minutes, and then flotation is performed using a flotation machine with a stirring speed of 1800 r / min for 2 minutes. The amount of collector used is 0.2‰ of the mass of the slurry after water adjustment.

[0055] Example 2

[0056] A beneficiation method for finely grained, disseminated lean iron ore, comprising the following specific steps:

[0057] (1) First, the fine-grained disseminated lean iron ore is pre-selected to obtain the ore to be ground. Then, the ore to be ground is ball-milled under the grinding aid of nano surfactants.

[0058] (2) Then add flocculant (sodium polyacrylate, ammonium humate and sodium hexametaphosphate mixed by mass) to carry out sludge removal treatment;

[0059] (3) Finally, a collector is added, and flotation, concentration, and filtration are carried out to obtain iron concentrate;

[0060] The nano surfactant was prepared by the following method: 3 kg of citric acid and 1 kg of octadecylamine were mixed evenly and reacted with microwave to obtain nano octadecylamine citrate. Then, 25 kg of coal tar residue was thermally polymerized under a helium atmosphere to obtain coal tar residue nano matrix. The nano octadecylamine citrate and coal tar residue nano matrix were then evenly dispersed in 130 kg of water, centrifuged to obtain the supernatant, and dried to obtain the final product.

[0061] The microwave reaction process conditions are: frequency 3 GHz, power 1000 W, and reaction time 50 minutes.

[0062] The process conditions for thermal polymerization are as follows: heating to 650℃ at a rate of 3℃ / min, and thermal polymerization reaction for 3 hours.

[0063] The centrifugation process conditions are: 70,000 r / min for 15 minutes.

[0064] The collector is prepared by the following method: 1 kg of nano silica and 0.2 kg of octylphenol polyoxyethylene ether are added to 7 kg of pine oil and ultrasonically vibrated at 600 W for 40 minutes. The mixture is then transferred to a ball mill and ball milled for 7 hours using steel balls with a diameter of 0.020 mm and a material-to-ball ratio of 1:1.

[0065] In step (1), the specific method for pre-selection is as follows: First, the fine-grained disseminated lean iron ore is initially crushed to 45mm, then ground to 7mm using a high-pressure roller mill. A wet high-intensity magnetic separator is then used with a magnetic field strength of 1T, a pulse stroke rate of 600 times / min, and a linear velocity of 2.2 rpm. Fine tailings with an iron grade of less than 12% are removed, thus obtaining the ore to be ground. The gap between the rollers of the high-pressure roller mill is 15mm.

[0066] In step (1), the specific method of ball milling is as follows: water is added to the ore to be milled to adjust the slurry to a mass concentration of 65%. Then, nano-surfactants are added to the slurry, and ball milling is carried out using a wet overflow ball mill. Steel balls with diameters of 35mm, 25mm, and 20mm are used, with a mass ratio of 2:3:5, a material-to-ball ratio of 0.8, and a media filling rate of 45%. The ball milling is carried out until the average particle size is 20μm. The amount of nano-surfactants used is 1‰ of the slurry mass.

[0067] In step (2), water is added to adjust the slurry concentration to 15%, and a 2 mol / L sodium hydroxide solution is used to control the slurry pH to 10. Flocculant is added, and the mixture is stirred for 3 minutes. Desliming is then achieved using a hydrocyclone. The amount of flocculant used is 0.1‰ of the slurry mass after water adjustment. The hydrocyclone feed inlet diameter is 90 mm.

[0068] In step (3), water is added to adjust the mass concentration of the slurry to 10%, and 2 mol / L hydrochloric acid solution is used to adjust the pH of the slurry to 7. After adding the collector, the mixture is stirred for 3 minutes, and then flotation is performed using a flotation machine with a stirring speed of 2000 r / min for 3 minutes. The amount of collector used is 0.3‰ of the mass of the slurry after water adjustment.

[0069] Example 3

[0070] A beneficiation method for finely grained, disseminated lean iron ore, comprising the following specific steps:

[0071] (1) First, the fine-grained disseminated lean iron ore is pre-selected to obtain the ore to be ground. Then, the ore to be ground is ball-milled under the grinding aid of nano surfactants.

[0072] (2) Then add flocculant (sodium polyacrylate, ammonium humate and sodium hexametaphosphate mixed by mass) to carry out sludge removal treatment;

[0073] (3) Finally, a collector is added, and flotation, concentration, and filtration are carried out to obtain iron concentrate;

[0074] The nano surfactant was prepared by the following method: First, 2 kg of citric acid and 1 kg of octadecylamine were mixed evenly and reacted with microwave to obtain nano octadecylamine citrate. Then, 25 kg of coal tar residue was thermally polymerized under a helium atmosphere to obtain coal tar residue nano matrix. Then, the nano octadecylamine citrate and the coal tar residue nano matrix were evenly dispersed in 120 kg of water, centrifuged to obtain the supernatant, and dried to obtain the final product.

[0075] The microwave reaction process conditions are: frequency 3GHz, power 800W, and reaction time 50 minutes.

[0076] The process conditions for thermal polymerization are: heating to 650℃ at a rate of 2℃ / min, and thermal polymerization reaction for 2 hours.

[0077] The centrifugation process conditions are: 70,000 r / min for 10 minutes.

[0078] The collector is prepared by the following method: 1 kg of nano silica and 0.2 kg of octylphenol polyoxyethylene ether are added to 5 kg of pine oil and ultrasonically vibrated at 600 W for 30 minutes. The mixture is then transferred to a ball mill and milled for 7 hours using steel balls with a diameter of 0.020 mm and a material-to-ball ratio of 1:1.

[0079] In step (1), the specific method for pre-selection is as follows: First, the fine-grained disseminated lean iron ore is initially crushed to 40mm, then ground to 7mm using a high-pressure roller mill. A wet high-intensity magnetic separator is then used, with a magnetic field strength of 0.8T, a pulse frequency of 600 times / min, and a linear speed of 2 revolutions / min. Fine tailings with an iron grade of less than 12% are removed, thus obtaining the ore to be ground. The gap between the rollers of the high-pressure roller mill is 15mm.

[0080] In step (1), the specific method of ball milling is as follows: water is added to the ore to be milled to adjust the slurry to a mass concentration of 55%. Then, nano-surfactants are added to the slurry, and ball milling is carried out using a wet overflow ball mill. Steel balls with diameters of 35mm, 25mm, and 20mm are used, with a mass ratio of 2:3:5, a material-to-ball ratio of 0.8, and a media filling rate of 45%. The ball milling is carried out until the average particle size is 15μm. The amount of nano-surfactants used is 1‰ of the slurry mass.

[0081] In step (2), water is added to adjust the slurry concentration to 13%, and a 2 mol / L sodium hydroxide solution is used to control the slurry pH to 9. Flocculant is added, and the mixture is stirred for 3 minutes. Desliming is then achieved using a hydrocyclone. The amount of flocculant used is 0.08‰ of the slurry mass after water adjustment. The hydrocyclone feed inlet diameter is 90 mm.

[0082] In step (3), water is added to adjust the mass concentration of the slurry to 8%, and 2 mol / L hydrochloric acid solution is used to adjust the pH of the slurry to 7. After adding the collector, the mixture is stirred for 2 minutes, and then flotation is performed using a flotation machine with a stirring speed of 2000 r / min for 2 minutes. The amount of collector used is 0.3‰ of the mass of the slurry after water adjustment.

[0083] Example 4

[0084] A beneficiation method for finely grained, disseminated lean iron ore, comprising the following specific steps:

[0085] (1) First, the fine-grained disseminated lean iron ore is pre-selected to obtain the ore to be ground, and then the ore to be ground is ball-milled.

[0086] (2) Then add flocculant (sodium polyacrylate, ammonium humate and sodium hexametaphosphate mixed by mass) to carry out sludge removal treatment;

[0087] (3) Finally, a collector is added, and flotation, concentration, and filtration are carried out to obtain iron concentrate;

[0088] The collector is prepared by the following method: 1 kg of nano silica and 0.15 kg of octylphenol polyoxyethylene ether are added to 6 kg of pine oil and ultrasonically vibrated at 600 W for 35 minutes. The mixture is then transferred to a ball mill and ball milled for 6.5 hours using steel balls with a diameter of 0.020 mm and a material-to-ball ratio of 1:1.

[0089] In step (1), the specific method for pre-selection is as follows: First, the fine-grained disseminated lean iron ore is initially crushed to 42mm, then ground to 6mm using a high-pressure roller mill. A wet high-intensity magnetic separator is then used with a magnetic field strength of 0.9T, a pulse frequency of 600 times / min, and a linear velocity of 2.2 rpm. Fine tailings with an iron grade of less than 12% are removed, thus obtaining the ore to be ground. The gap between the rollers of the high-pressure roller mill is 12mm.

[0090] In step (1), the specific method of ball milling is as follows: water is added to the ore to be milled to adjust the slurry to a mass concentration of 60%, and ball milling is carried out using a wet overflow ball mill. Steel balls with diameters of 35mm, 25mm, and 20mm are used, with a mass ratio of 2:3:5, a material-to-ball ratio of 0.8, and a media filling rate of 42%. The ball milling is carried out until the average particle size is 18μm. The amount of nano-surfactant used is 0.9‰ of the slurry mass.

[0091] In step (2), water is added to adjust the slurry concentration to 14%, and a 1.5 mol / L sodium hydroxide solution is used to control the slurry pH to 9. Flocculant is added, and the mixture is stirred for 3 minutes. Desliming is then achieved using a hydrocyclone. The amount of flocculant used is 0.09‰ of the slurry mass after water adjustment. The hydrocyclone feed inlet diameter is 80 mm.

[0092] In step (3), water is added to adjust the mass concentration of the slurry to 9%, and 1.5 mol / L hydrochloric acid solution is used to adjust the pH of the slurry to 7. After adding the collector, the mixture is stirred for 2 minutes, and then flotation is performed using a flotation machine at a stirring speed of 1900 r / min for 3 minutes. The amount of collector used is 0.25‰ of the mass of the slurry after water adjustment.

[0093] Comparative Example

[0094] A beneficiation method for finely grained, disseminated lean iron ore, comprising the following specific steps:

[0095] (1) First, the fine-grained disseminated lean iron ore is pre-selected to obtain the ore to be ground. Then, the ore to be ground is ball-milled under the grinding aid of nano surfactants.

[0096] (2) Then add flocculant (sodium polyacrylate, ammonium humate and sodium hexametaphosphate mixed by mass) to carry out sludge removal treatment;

[0097] (3) Finally, a collector is added, and flotation, concentration, and filtration are carried out to obtain iron concentrate;

[0098] The nano surfactant was prepared by the following method: 2 kg of citric acid and 1 kg of octadecylamine were mixed evenly and reacted with microwave to obtain nano octadecylamine citrate. Then, 20 kg of coal tar residue was thermally polymerized under a helium atmosphere to obtain coal tar residue nano matrix. The nano octadecylamine citrate and coal tar residue nano matrix were then evenly dispersed in 120 kg of water, centrifuged to obtain the supernatant, and dried to obtain the final product.

[0099] The microwave reaction process conditions are: frequency 2GHz, power 800W, and reaction time 40 minutes.

[0100] The process conditions for thermal polymerization are as follows: the temperature is increased to 550℃ at a rate of 2℃ / min, and the thermal polymerization reaction is carried out for 2 hours.

[0101] The centrifugation process conditions are: centrifugation at 60,000 r / min for 10 minutes.

[0102] The collector is prepared by the following method: 1 kg of nano silica and 0.1 kg of octylphenol polyoxyethylene ether are added to 5 kg of pine oil and ultrasonically vibrated at 500 W for 30 minutes. The mixture is then transferred to a ball mill and ball milled for 6 hours using steel balls with a diameter of 0.020 mm and a material-to-ball ratio of 1:1.

[0103] In step (1), the specific method for pre-selection is as follows: First, the fine-grained disseminated lean iron ore is initially crushed to 40mm, then ground to 5mm using a high-pressure roller mill. A wet high-intensity magnetic separator is then used with a magnetic field strength of 0.8T, a pulse stroke rate of 500 times / min, and a linear speed of 2 revolutions / min. Fine tailings with an iron grade of less than 12% are removed, thus obtaining the ore to be ground. The gap between the rollers of the high-pressure roller mill is 10mm.

[0104] In step (1), the specific method of ball milling is as follows: water is added to the ore to be milled to adjust the slurry to a mass concentration of 55%, then nano-surfactants are added to the slurry, and ball milling is carried out using a wet overflow ball mill. Steel balls with diameters of 35mm, 25mm, and 20mm are used, with a mass ratio of 2:3:5, a material-to-ball ratio of 0.8, and a media filling rate of 40%. The ball milling time is the same as in Example 1.

[0105] In step (2), water is added to adjust the slurry concentration to 13%, and a 1 mol / L sodium hydroxide solution is used to control the slurry pH to 9. Flocculant is added, and the mixture is stirred for 2 minutes. Desliming is then achieved using a hydrocyclone. The amount of flocculant used is 0.08‰ of the slurry mass after water adjustment. The hydrocyclone feed inlet diameter is 60 mm.

[0106] In step (3), water is added to adjust the mass concentration of the slurry to 8%, and 1 mol / L hydrochloric acid solution is used to adjust the pH of the slurry to 7. After adding the collector, the mixture is stirred for 2 minutes, and then flotation is performed using a flotation machine with a stirring speed of 1800 r / min for 2 minutes. The amount of collector used is 0.2‰ of the mass of the slurry after water adjustment.

[0107] The iron grade in the iron concentrates obtained in Examples 1-4 and the comparative example was tested according to GB / T6730.73-2016 "Determination of Total Iron Content in Iron Ore by EDTA Photometric Titration".

[0108] The recovery rate is calculated using the following formula: Recovery rate = Iron concentrate mass × Iron concentrate grade / (Original lean iron ore mass × Original lean iron ore grade) × 100%.

[0109] The results of the investigation are shown in Table 1.

[0110] Table 1. Results of the investigation on mineral processing methods

[0111] Iron concentrate grade (%) Recovery rate (%) Example 1 68.92 89.36 Example 2 68.99 89.29 Example 3 69.05 89.27 Example 4 69.15 89.25 Comparative Example 59.87 82.11

[0112] As can be seen from Table 1, the mineral processing methods in Examples 1 to 4 have high recovery rates and high iron concentrate grades.

[0113] The comparative example showed that no nano-surfactant was added during ball milling, resulting in a significantly lower recovery rate and lower iron concentrate grade. This indicates that nano-surfactant directly affects the ball milling effect, which in turn affects the beneficiation effect. The reduction in iron concentrate grade is accompanied by a large amount of loss, leading to a significant decrease in recovery rate.

[0114] The present invention has been illustrated through the above embodiments, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of individual raw materials in the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A beneficiation method for finely grained, disseminated lean iron ore, characterized in that, The specific steps are as follows: (1) First, the fine-grained disseminated lean iron ore is pre-selected to obtain the ore to be ground. Then, the ore to be ground is ball-milled under the grinding aid of nano surfactants. (2) Then add flocculant and carry out sludge removal treatment; (3) Finally, a collector is added, and flotation, concentration, and filtration are carried out to obtain iron concentrate; The nano surfactant is obtained by loading nano-octadecylamine citrate onto a coal tar residue nano matrix; the flocculant is obtained by mixing sodium polyacrylate, ammonium humate and sodium hexametaphosphate in equal mass; and the collector is obtained by compounding nano-silica and pine oil. The nano-surfactant is prepared by the following method, by weight: 2-3 parts of citric acid and 1 part of octadecylamine are mixed evenly and reacted with microwave to obtain nano-octadecylamine citrate. Then, 20-25 parts of coal tar residue are thermally polymerized under an inert gas atmosphere to obtain coal tar residue nano matrix. Then, the nano-octadecylamine citrate and the coal tar residue nano matrix are evenly dispersed in 120-130 parts of water, the supernatant is collected by centrifugation and dried to obtain the final product. The process conditions for microwave reaction are: frequency 2-3 GHz, power 800-1000 W, and reaction time 40-50 minutes; The inert gas is argon or helium; The process conditions for thermal polymerization are: heating to 550-650℃ at a rate of 2-3℃ / min, and thermal polymerization reaction for 2-3 hours; The centrifugation process conditions are: centrifugation at 60,000–70,000 r / min for 10–15 minutes.

2. The beneficiation method for fine-grained disseminated lean iron ore according to claim 1, characterized in that, The fine-grained, intercalated lean iron ore has an iron grade of 18-20% and its main component is hematite.

3. The beneficiation method for fine-grained disseminated lean iron ore according to claim 1, characterized in that, The collector is prepared by the following method, by weight: 1 part of nano silica and 0.1 to 0.2 parts of octylphenol polyoxyethylene ether are added to 5 to 7 parts of pine oil, ultrasonically vibrated at 500 to 600 W for 30 to 40 minutes, transferred to a ball mill, and ball milled for 6 to 7 hours using steel balls with a diameter of 0.020 mm and a material-to-ball ratio of 1:

1.

4. The beneficiation method for finely grained, disseminated lean iron ore according to claim 1, characterized in that, In step (1), the specific method of pre-selection is as follows: first, the fine-grained disseminated lean iron ore is initially crushed to 40-45mm, then high-pressure roller milled to 5-7mm, and a wet strong magnetic separator is used with a magnetic field strength of 0.8-1T, a pulse frequency of 500-600 times / min, and a linear speed of 2-2.2 rpm to remove the fine tailings with an iron grade of less than 12%, thus obtaining the ore to be ground.

5. The beneficiation method for fine-grained disseminated lean iron ore according to claim 4, characterized in that, The gap between the rollers in a high-pressure roller mill is 10–15 mm.

6. The beneficiation method for fine-grained disseminated lean iron ore according to claim 1, characterized in that, In step (1), the specific method of ball milling is as follows: water is added to the ore to be milled to adjust it to a slurry with a mass concentration of 55-65%. Then, nano surfactants are added to the slurry and ball milling is carried out using a wet overflow ball mill. Steel balls with diameters of 35mm, 25mm, and 20mm are used, with a mass ratio of 2:3:5, a material-to-ball ratio of 0.8, and a media filling rate of 40-45%. The ball milling is carried out until the average particle size is -15μm.

7. The beneficiation method for finely grained, disseminated lean iron ore according to claim 1, characterized in that, In step (2), water is added to adjust the mass concentration of the slurry to 13-15%, and 1-2 mol / L sodium hydroxide solution is used to control the pH of the slurry to 9-10. Flocculant is added, and the mixture is stirred for 2-3 minutes. Desliming is achieved through a hydrocyclone.

8. The beneficiation method for finely grained, disseminated lean iron ore according to claim 1, characterized in that, In step (3), water is added to adjust the mass concentration of the slurry to 8-10%, and 1-2 mol / L hydrochloric acid solution is used to adjust the pH of the slurry to 7. After adding the collector, the mixture is stirred for 2-3 minutes and then floated using a flotation machine with a stirring speed of 1800-2000 r / min for 2-3 minutes.