A method for separating iron-bearing silicate gangue minerals by reverse flotation using a chelating collector.

Abstract

This invention relates to the field of reverse flotation technology, specifically to a method for separating iron-bearing silicate gangue minerals using a chelating collector. The reagent combination primarily involves selecting one of the following chelating collectors—benzotriazole, N-nitrosophenylammonium, or 1-naphthylhydroxyxamic acid—as a pretreatment agent for flotation adsorption under suitable pH conditions. Subsequently, inhibitors and collectors are added, followed by reverse flotation. This invention addresses the difficulty in separating iron-bearing silicate ores with similar physicochemical properties. By specifically adsorbing elements such as magnesium and sodium in iron-bearing silicates through the reagent combination, the inhibitor's effect on iron ore and iron-bearing silicates differs. This improves gangue recovery without affecting iron ore recovery, enhancing the separation efficiency between minerals. Compared to conventional flotation processes, this method yields higher-grade iron concentrate, achieving highly efficient separation between iron-bearing silicate gangue minerals and iron ore.

Description

Technical Field

[0001] This invention relates to the field of reverse flotation technology, specifically to a method for separating iron-containing silicate gangue minerals by reverse flotation using a chelating collector. Background Technology

[0002] Iron and steel are important resources for national industrial construction and social development. Iron and steel products are widely used in aerospace, metallurgy, chemical industry and other fields. As my country's industrial production demands for iron ore resources increase, easily beneficiated iron ore resources are being exploited in large quantities, and difficult-to-beneficiate iron ore is gradually becoming the main type of iron ore mining today. Therefore, it is crucial to improve the comprehensive utilization rate of my country's iron ore resources.

[0003] Hematite and specular hematite are common iron oxide minerals that often occur in nature alongside silicate gangue minerals (chlorite, aegirine, etc.). These two minerals have similar densities and specific magnetic susceptibility, making it difficult to achieve ideal separation using traditional magnetic separation and gravity separation methods. During flotation, both iron ore and iron-bearing silicate gangue release Fe ions, causing flotation reagents to adsorb both minerals simultaneously, hindering effective separation and significantly reducing the grade of the iron concentrate. Therefore, pre-adsorption of iron-bearing silicate gangue with reagents can improve gangue recovery without affecting iron ore recovery, making it an effective means to promote the flotation separation of the two minerals.

[0004] Chinese invention patent CN202110653078 discloses a flotation reagent and method for improving the separation efficiency of ilmenite from its gangue. It synthesizes a variety of novel compounds containing benzene rings and phosphate groups, which are used as flotation collectors for ilmenite. Compared with commonly used collectors such as oleic acid and fatty acids, the benzene rings and phosphate groups of these compounds enhance the intramolecular synergistic collecting effect, further improving the separation efficiency of ilmenite from its associated gangue and effectively increasing the grade of ilmenite concentrate.

[0005] Chinese invention patent CN202111418550.1 discloses a flotation separation method for iron-containing silicate gangue minerals. This method, under a preferred pH of 9-10, adds tridemorpholine before the flotation experiment. This reagent exhibits good adsorption effects on gangue minerals. Further flotation experiments are then conducted, and the separation of iron ore and gangue is achieved through the combined action of inhibitors and collectors, effectively improving the separation efficiency. While the above patents all relate to flotation separation technology for gangue minerals, developing new reagents is costly, and the actual production pulp environment is more complex. How to use green and safe reagents to further achieve efficient separation of iron ore and iron-containing silicates and rapidly apply them to actual production is one of the important problems to be solved in the industry.

[0006] In view of the above-mentioned defects, the inventors of this invention have finally obtained this invention after a long period of research and practice. Summary of the Invention

[0007] The purpose of this invention is to solve the problems of high cost in developing new reagents and more complex actual production pulp environment in existing flotation separation methods for iron-containing silicate gangue minerals, and to provide a method for separating iron-containing silicate gangue minerals by reverse flotation using a chelating collector.

[0008] To achieve the above objectives, this invention discloses a method for separating iron-containing silicate gangue minerals by reverse flotation using a chelating collector, comprising the following steps:

[0009] S1, crush and sort iron ore and iron-containing silicate mineral samples, and grind them to a particle size range of -0.074 to +0.044 μm as flotation samples;

[0010] S2 involves mixing minerals with water to form a slurry, and using a pH adjuster to control the pH of the magma to 6–8.

[0011] S3, mix the slurry with the chelating collector and stir thoroughly;

[0012] S4, continue to add inhibitor to the slurry obtained in step S3, and add collector after stirring evenly;

[0013] S5, the slurry obtained in step S4 is subjected to single mineral flotation, and the product in the flotation cell and the froth product are filtered, dried and the recovery rate is calculated.

[0014] In step S1, the iron-containing silicate minerals are chlorite and aegirine, and the iron ore is specular hematite.

[0015] In step S2, the pH adjuster is hydrochloric acid and sodium hydroxide, wherein the concentration of hydrochloric acid is 1 mol / L and the concentration of sodium hydroxide is 0.1 mol / L.

[0016] In step S3, the chelating collector is any one of benzotriazole, N-nitrosophenylhydrazine, and 1-naphthylhydroxyoxime, with the following structural formula:

[0017]

[0018] In step S3, the amount of chelating collector used is 0-60 mg / L.

[0019] In step S3, the amount of chelating collector used is 6-15 mg / L.

[0020] In step S4, the inhibitor is starch or dextrin, and the dosage of the inhibitor is 0-120 mg / L. In step S4, the collector is dodecylamine, and the dosage of the collector is 0-50 mg / L.

[0021] In step S4, the inhibitor is starch or dextrin, and the dosage of the inhibitor is 30 mg / L. In step S4, the collector is dodecylamine, and the dosage of the collector is 30 mg / L.

[0022] The stirring time in steps S3 and S4 is 2 to 3 minutes.

[0023] The flotation time in step S5 is 4 to 5 minutes.

[0024] This invention applies chelating collectors to the pre-flotation adsorption of gangue minerals. Since iron-bearing silicate gangues, such as chlorite and aegirine, contain minor elements like magnesium, aluminum, and sodium, adding a chelating collector before the flotation test can pre-form targeted adsorption with these minor element sites in the gangue, generating cyclic chelates. These cyclic chelates create steric hindrance and hinder subsequent dextrin adsorption on the gangue. However, because the chelating collector has few non-polar hydrocarbon groups, its collecting capacity is limited. Therefore, after adding dodecylamine, the chelating collector combines with dodecylamine under electrostatic attraction, enhancing the floatability of the iron-bearing silicate gangue. Due to the simple structure and single elemental composition of specular hematite, the adsorption capacity of the chelating collector is lower than that of dextrin. This makes it easier for the chelating collector to escape competitive adsorption, allowing a large amount of dextrin to adsorb onto the surface of specular hematite, increasing its hydrophilicity and causing selective inhibition of specular hematite. This widens the recovery gap between the two minerals, thus enabling the separation of iron ore and iron-bearing silicate gangue through reverse flotation, improving the grade of iron concentrate, and achieving a breakthrough application of chelating collectors.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. Compared with the conventional flotation process, the reverse flotation separation method provided by this invention adds a chelating collector before the conventional flotation process, which is used as a pre-adsorption agent. Based on the specific adsorption of magnesium, aluminum and sodium element sites by the chelating collector, a multi-element chelate ring structure is formed with the element sites, forming steric hindrance and effectively weakening the inhibitory effect on gangue. At the same time, through the excellent collection efficiency of dodecylamine, the recovery rate difference of iron silicate minerals can be effectively improved, further improving the grade of the obtained iron concentrate, and realizing the efficient separation of iron ore and iron silicate minerals.

[0027] 2. In this invention, dextrin, a small molecule organic compound, is selected as an inhibitor for flotation experiments. Dextrin and starch have similar inhibitory abilities on iron and can significantly improve the hydrophilicity of iron ore. However, since dextrin itself does not have long molecular chains, it cannot mask or shield the surface of layered iron-containing silicate minerals. It has weak adsorption on silicate minerals and its selective inhibition of iron atoms is better than that of starch.

[0028] 3. The addition of chelating collectors in this invention does not affect the inhibition of dextrin on iron ore. The reverse flotation method improves the grade and separation efficiency of iron concentrate, thereby further improving production efficiency. Attached Figure Description

[0029] Figure 1 These are schematic diagrams of the flotation process for a single mineral in Examples 1-6 and Comparative Examples 1-2 of the present invention;

[0030] Figure 2 The optimal dosage curves for the chelating collector (benzotriazole) on specular hematite, chlorite, and aegirine are shown.

[0031] Figure 3 The effect of pulp pH on the flotation effect of chlorite, aegirine and specular hematite;

[0032] Figure 4 The effect of inhibiting the dosage of starch (a) and dextrin (b) at pH=7 on the flotation effect of chlorite, aegirine, and specular hematite;

[0033] Figure 5 The optimal dosage curve for the chelating collector (N-nitrosophenylammonium) in flotation is shown.

[0034] Figure 6 The optimal pH curve for flotation of the chelating collector (N-nitrosophenylammonium);

[0035] Figure 7 The optimal dosage and pH curve for the chelating collector (1-naphthoic acid) in flotation are shown.

[0036] Figure 8 This is a schematic diagram of the flotation process for binary mixed ores in Examples 5 and 6. Detailed Implementation

[0037] The above-mentioned and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings.

[0038] The chlorite and specular hematite samples were taken from the Lilou iron mine in Huoqiu County, Anhui Province, and the aegirine sample was taken from the Bayan Obo mining area in Inner Mongolia. The Fe grade of the specular hematite ore was 59.47%.

[0039] Example 1

[0040] To verify the separation effect of the flotation reagents of the present invention in various component slurries, a combination of conventional flotation reagents and a pre-adsorption reagent combination was used. The specific steps of this embodiment are as follows:

[0041] Take 200g of chlorite and specular hematite, crush them by ball mill and dry screen them to a particle size range of -0.074 to +0.044μm. After washing and drying, put 2g of chlorite or specular hematite into a flotation cell and mix them evenly with water to make a slurry.

[0042] Add a pH adjuster to the optimal pH in the slurry. After stirring for 2 minutes, add benzotriazole first and stir evenly. Then add the inhibitors dextrin and dodecylamine and stir for 2 minutes each. The dosage of the inhibitor is 30 mg / L and the dosage of the collector dodecylamine is 30 mg / L. After stirring and aerating for 1 minute, scrape the concentrate that floats to the surface with the foam and continue for 5 minutes. After the end, dry the concentrate and tailings separately and weigh them.

[0043] To determine the optimal dosage of benzotriazole and the optimal pH of the pulp, based on the above experimental conditions, the initial experimental pH was adjusted to 7, and flotation tests were conducted at dosages of 3 mg / L, 6 mg / L, 9 mg / L, 15 mg / L, and 30 mg / L. After fixing the optimal dosage, flotation tests were performed at the optimal pH. Figure 2 The results show that the optimal dosage of the chelating collector benzotriazole in the chlorite and specular hematite system is 9 mg / L, and the optimal pH value is 8. At this point, the recovery rate can reach about 70%.

[0044] Example 2

[0045] The reverse flotation method for iron-containing silicates provided in Example 2 differs from that in Example 1 in that another iron-containing silicate mineral, nepheline, is selected as one of the main minerals in the flotation experiment, and its optimal dosage and pH are chosen. The other steps are basically the same as in Example 1 and will not be repeated here. The experimental results are as follows: Figure 2 As shown in Figure 3.

[0046] The optimal dosage of the chelating collector benzotriazole in the nepheline and specular hematite flotation system is 15 mg / L, and the optimal pH value is 8. At this value, the nepheline recovery rate can reach 85.45%, and the specular hematite recovery rate is 18.9%.

[0047] Comparative Example 1

[0048] To compare the differences between the present invention and conventional flotation, a conventional flotation experiment was conducted using starch as a depressant and dodecylamine as a collector. The specific steps of this comparative example are as follows:

[0049] Take 200g of chlorite and specular hematite, crush them by ball mill and dry screen them to a particle size range of -0.074 to +0.044μm. After washing and drying, put 2g of chlorite or specular hematite into a flotation cell and mix them evenly with water to make a slurry.

[0050] Add a pH adjuster to adjust the pH to 7 in the slurry. After stirring for 2 minutes, add the inhibitor starch and dodecylamine and stir for 2 minutes each. Increase the amount of inhibitor from 10 mg / L to 120 mg / L. Fix the amount of collector dodecylamine at 30 mg / L. After stirring and aerating for 1 minute, scrape the concentrate that floats to the surface with the foam. Continue for 5 minutes. After the end, dry the concentrate and tailings separately and weigh them.

[0051] Comparative Example 2

[0052] To compare the differences between the present invention and conventional flotation, conventional flotation tests were conducted using dextrin as an inhibitor and dodecylamine as a collector. The specific steps of this comparative example are as follows:

[0053] Take 200g of chlorite and specular hematite, crush them by ball mill and dry screen them to a particle size range of -0.074 to +0.044μm. After washing and drying, put 2g of chlorite or specular hematite into a flotation cell and mix them evenly with water to make a slurry.

[0054] Add a pH adjuster to adjust the pH to 7 in the slurry. After stirring for 1 minute, add the inhibitors dextrin and dodecylamine and stir for 1 minute each. Increase the dosage of the inhibitor from 10 mg / L to 120 mg / L. Fix the dosage of the collector dodecylamine at 30 mg / L. After stirring and aerating for 1 minute, scrape the concentrate that floats to the surface with the foam. Continue for 3 minutes. After the end, dry the concentrate and tailings separately and weigh them.

[0055] The results of conventional flotation experiments and the optimal recovery rates are as follows: Figure 4 As shown, and the experimental results demonstrate that dextrin has a stronger selective inhibitory effect on specular hematite than starch, dextrin is more suitable as an inhibitor in the experimental system of this invention. The optimal dosage is 30 mg / L, at which point the recovery rate of chlorite is 25.22%; the recovery rate of aegirine is 19.85%; and the recovery rate of specular hematite is 10.2%.

[0056] Depend on Figures 2 to 4The results showed that starch exhibited a strong inhibitory effect on all tested minerals before the addition of the chelating collector, while dextrin showed selective inhibition of specular hematite, indicating that the inhibitor dextrin is more suitable as the system inhibitor of this invention. The addition of the chelating collector (benzotriazole) in this invention can further expand the difference in recovery rates between specular hematite and other iron-bearing silicate minerals, and the small-molecule inhibitor dextrin can still maintain excellent inhibition of specular hematite in this system, with better results than starch. Under the optimal dosage of the complete pre-adsorbed reagent system, the recovery rates of chlorite and aegirine can reach 88.69% and 85.45%, respectively. Compared with conventional flotation methods, this can increase the recovery rate of iron-bearing silicate gangues (chlorite and aegirine) by about 50-60%, while the recovery rate of specular hematite is less than 20%. This proves that benzotriazole exhibits excellent selective adsorption through chelation of specific element sites, and its application in the reverse flotation of iron-bearing silicates can achieve excellent separation results.

[0057] Example 3

[0058] The reverse flotation method for iron-containing silicates provided in this embodiment differs from that in Example 1 in that it uses another chelating collector, N-nitrosophenylammonium, to conduct experiments on the optimal dosage and pH for the flotation of chlorite, nepheline, and specular hematite. Otherwise, the results are the same as in Example 1. Figure 5 and Figure 6 .

[0059] Example 4

[0060] The reverse flotation method for iron-containing silicates provided in this embodiment differs from that in Example 1 in that the optimal dosage and pH of another chelating collector, 1-naphthoic acid, were tested for flotation of chlorite, nepheline, and specular hematite. Other aspects are the same as in Example 1, and the results are as follows: Figure 7 As shown.

[0061] Depend on Figures 5-7 It can be seen that adding chelating collectors to this system has no significant effect on the recovery rate of specular hematite, but can significantly improve the recovery rate of gangue. This indicates that the reagent system of the present invention can significantly improve the separation selectivity of concentrate and gangue in the mixed minerals of chlorite and specular hematite, and further improve the grade of concentrate in flotation.

[0062] Example 5

[0063] To verify the separation effect of the pre-adsorption reagent system in the present invention on multi-component mixed minerals, 200g of chlorite and specular hematite samples were taken, crushed by ball mill and dry sieved to a particle size range of -0.074 to +0.044μm. After washing and drying, chlorite and specular hematite were placed in a flotation cell at a mass ratio of 3:2 (total 2g of mineral sample) and mixed evenly with water to prepare a slurry.

[0064] Add a pH adjuster to adjust the pH to 8 in the slurry. After stirring for 2 minutes, add benzotriazole first and stir evenly. Then add the inhibitor dextrin and the collector dodecylamine and stir for 2 minutes respectively. After stirring and aerating for 1 minute, scrape the concentrate that floats to the surface with the foam and continue for 5 minutes. After the end, dry the concentrate and tailings separately and weigh them. The concentrate grade and recovery rate are shown in Table 3.

[0065] Single-mineral experiments showed that benzotriazole had the best recovery efficiency for both gangues. Therefore, benzotriazole was selected as the main reagent for subsequent mixed ore experiments at a dosage of 9 mg / L, dodecylamine was used as the collector at a dosage of 30 mg / L, and the inhibitor was used at a dosage of 30 mg / L. Preferably, based on the results of single-mineral experiments, dextrin, a small molecule inhibitor, was selected as the inhibitor for subsequent mixed ore flotation.

[0066] Table 1. Iron grade and recovery rate of binary mixed minerals (chlorite, specularite) under different reagent combinations.

[0067]

[0068] As shown in Table 5, the iron recovery rate of the concentrate can reach 82.99% after the addition of benzotriazole, and a concentrate with a grade of 50.3% is obtained. This indicates that the reagent system of the present invention can significantly improve the separation selectivity of concentrate and gangue in the mixed minerals of chlorite and specular hematite, and further improve the grade of the concentrate from flotation.

[0069] Example 6

[0070] To verify the separation effect of the pre-adsorption reagent system in multi-component mixed minerals, 200g of aegirine and specular hematite samples were taken, crushed by ball mill and dry sieved to a particle size range of -0.074 to +0.044μm. After washing and drying, aegirine and specular hematite were placed in a flotation cell at a mass ratio of 3:2 (total 2g of mineral sample) and mixed evenly with water to prepare a slurry.

[0071] Add a pH adjuster to adjust the pH to 8 in the slurry. After stirring for 2 minutes, add benzotriazole first and stir evenly. Then add the inhibitor dextrin and the collector dodecylamine and stir for 2 minutes respectively. After stirring and aerating for 1 minute, scrape the concentrate that floats to the surface with the foam and continue for 5 minutes. After the end, dry the concentrate and tailings separately and weigh them. The concentrate grade and recovery rate are shown in Table 4.

[0072] The dosage of the chelating collector benzotriazole was 15 mg / L, the dosage of the collector dodecylamine was 30 mg / L, and the dosage of the inhibitor dextrin was 30 mg / L.

[0073] Table 2. Iron grade and recovery rate of binary mixed minerals (nepheline and specularite) under different reagent combinations.

[0074]

[0075] At this point, an iron concentrate with a recovery rate of 78.25% and a grade of 48.28% can be obtained, indicating that the flotation method of the present invention is applicable to two iron-containing silicate systems and achieves the effect of effectively separating gangue and iron ore.

[0076] In summary, the reverse flotation separation method for iron-bearing silicate gangue minerals designed in this invention adds a pre-adsorption step of chelating collectors compared to conventional flotation. By combining the pre-adsorption of gangue with the inhibition of iron ore by inhibitors, the gangue recovery rate can be improved without affecting the iron ore recovery rate. This effectively improves the grade and recovery rate of mixed mineral iron concentrate, and provides a new approach to solving the problem of difficult separation of iron ore and iron-bearing silicate gangue.

[0077] The above description is merely a preferred embodiment of the present invention and is illustrative rather than restrictive. Those skilled in the art will understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, all of which will fall within the protection scope of the present invention.

Claims

1. A method for separating iron-bearing silicate gangue minerals by reverse flotation using a chelating collector, characterized in that, Includes the following steps: S1, crush and sort iron ore and iron-containing silicate mineral samples, and grind them to a particle size range of -0.074 to +0.044 μm as flotation samples; S2, minerals are mixed with water to form a slurry, and the pH value of the magma is controlled to be 6~8 by a pH adjuster; S3, mix the slurry with the chelating collector and stir thoroughly; S4, continue to add inhibitor to the slurry obtained in step S3, and add collector after stirring evenly; S5, the slurry obtained in step S4 is subjected to single mineral flotation, and the product in the tank after flotation and the froth product are filtered, dried and the recovery rate is calculated. In step S1, the iron-containing silicate minerals are chlorite and aegirine, and the iron ore is specular hematite. The chelating collector in step S3 is any one of benzotriazole, N-nitrosophenylammonium, and 1-naphthooxime acid; In step S4, the inhibitor is starch or dextrin, and the dosage of the inhibitor is 0-120 mg / L. In step S4, the collector is dodecylamine, and the dosage of the collector is 0-50 mg / L.

2. The method for separating iron-bearing silicate gangue minerals by reverse flotation using a chelating collector as described in claim 1, characterized in that, In step S2, the pH adjuster is hydrochloric acid and sodium hydroxide, wherein the concentration of hydrochloric acid is 1 mol / L and the concentration of sodium hydroxide is 0.1 mol / L.

3. The method for separating iron-bearing silicate gangue minerals by reverse flotation using a chelating collector as described in claim 1, characterized in that, In step S3, the amount of chelating collector used is 0~60 mg / L.

4. The method for separating iron-bearing silicate gangue minerals by reverse flotation using a chelating collector as described in claim 1, characterized in that, In step S3, the amount of chelating collector used is 6~15 mg / L.

5. The method for separating iron-bearing silicate gangue minerals by reverse flotation using a chelating collector as described in claim 1, characterized in that, In step S4, the inhibitor is starch or dextrin, and the dosage of the inhibitor is 30 mg / L. In step S4, the collector is dodecylamine, and the dosage of the collector is 30 mg / L.

6. The method for separating iron-bearing silicate gangue minerals by reverse flotation using a chelating collector as described in claim 1, characterized in that, The stirring time in steps S3 and S4 is 2-3 minutes.

7. The method for separating iron-bearing silicate gangue minerals by reverse flotation using a chelating collector as described in claim 1, characterized in that, The flotation time in step S5 is 4-5 minutes.

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