A polystyrene nanoparticle emulsion reinforced iron ore desilication process by reverse flotation

Abstract

The present application aims at providing a polystyrene nanoparticle emulsion reinforced iron ore reverse flotation desilication process, belonging to the technical field of flotation, and adding polystyrene nanoparticles as a reinforcing agent in the reverse flotation process of iron ore, the polystyrene nanoparticles can enhance the surface hydrophobicity of quartz mineral by targeted adsorption on the surface of quartz mineral, and can effectively inhibit the non-specific adsorption of collector molecules on the surface of iron ore, effectively reducing the entrainment risk of target minerals. As an auxiliary carrier of flotation reagents, polystyrene nanoparticles can promote the stable adsorption of collectors on the surface of quartz minerals.

Description

Technical Field

[0001] This invention belongs to the field of flotation technology, specifically relating to a polystyrene nanoparticle emulsion-enhanced reverse flotation desilication process for iron ore. Background Technology

[0002] Iron ore reverse flotation processes mainly include anion reverse flotation and cationic reverse flotation, both of which are widely used in the desilication process of iron ore reverse flotation. A common cationic reverse flotation process involves adding iron ore depressants and silica mineral activators under weakly acidic to weakly alkaline conditions, using cationic amines as collectors for the silica minerals, thereby achieving the flotation separation of iron ore and silica minerals.

[0003] Although cationic reverse flotation has proven highly effective in desilication of iron ore, several challenges remain in actual production. Firstly, the poor selectivity of cationic collectors allows iron ore to easily mix into the froth phase during separation, leading to fluctuations in concentrate grade and iron loss. Secondly, the combined collecting and frothing properties of cationic collectors result in high-viscosity, poor-flowability froth, increasing the operational difficulty of subsequent processes.

[0004] On the other hand, with the continuous improvement of mechanization in ore mining, the iron ore currently obtained is characterized by fine particle size and complex associated mineral composition. In actual mineral flotation processes, due to the small mass, large specific surface area, and high surface energy of fine mineral particles, the number of particles per unit volume, specific surface energy, and surface charge all increase dramatically as the particle size decreases. This leads to the adsorption of large amounts of flotation reagents, resulting in high reagent consumption and high separation costs. Furthermore, because fine mineral particles have low kinetic energy, they have a low probability of adhering to air bubbles during interfacial flotation, thus failing to effectively adhere to air bubbles and achieve flotation. Summary of the Invention

[0005] This invention addresses the problems of poor flotation selectivity, limited separation efficiency, high flotation foam viscosity, difficult operation, sensitivity to ore slime, and limited adaptability in existing iron ore cationic reverse flotation processes. It provides a polystyrene nanoparticle emulsion-enhanced iron ore reverse flotation desilication process.

[0006] The present invention adopts the following technical solution:

[0007] A polystyrene nanoparticle emulsion-enhanced iron ore reverse flotation desilication process includes the following steps:

[0008] S1. Formulation of polystyrene nanoparticle emulsion:

[0009] a. Dissolve the emulsifier cetyltrimethylammonium bromide in deionized water according to the specified ratio. After it is fully dissolved, add the monomer styrene and stir at room temperature for 24 hours to ensure that the emulsifier is fully emulsified.

[0010] b. Inject nitrogen gas, add the initiator azobisisobutyramidine hydrochloride under nitrogen atmosphere protection, heat to 75°C and keep the temperature constant. After 0.5 h, turn off the nitrogen gas and continue stirring for 24 h. After the reaction is completed, cool to room temperature to obtain polystyrene nanoparticle emulsion.

[0011] S2. Preparation of dodecylamine solution as flotation collector:

[0012] a. Weigh dodecylamine into a beaker containing water, place it in a water bath and heat to 60°C with stirring to obtain a dodecylamine solution;

[0013] b. Weigh acetic acid into a beaker and dilute it with water to obtain an acetic acid solution;

[0014] c. Pour the acetic acid solution into the dodecylamine solution, add water to 500 mL, and heat and stir at 60°C until the solution is clear and transparent without any flocculent matter;

[0015] S3, Iron ore reverse flotation desilication:

[0016] a. Add slurry to the flotation machine, add distilled water and stir for 2 minutes, then add HCl to the slurry solution to adjust the pH of the slurry to 6.5;

[0017] b. Add the inhibitor corn starch to the slurry solution and stir well;

[0018] c. After stirring evenly for 3 minutes, add the activator calcium oxide to the slurry solution;

[0019] d. After stirring evenly for 3 minutes, add polystyrene nanoparticle emulsion to the slurry solution;

[0020] d. After stirring evenly for 3 minutes, add the collector dodecylamine solution to the slurry solution;

[0021] e. After stirring evenly for 3 minutes, add the frother octanol to the slurry solution, stir for 10 seconds, open the air inlet valve of the flotation machine, and simultaneously carry out a 3-minute flotation skimming operation, which is the roughing process.

[0022] f. The foam product obtained from the rough selection is added to calcium oxide and dodecylamine solution successively, and then fine selection is performed. The product in the rough selection tank is then swept.

[0023] Further, in S1, the mass ratio of deionized water, hexadecyltrimethylammonium bromide, styrene, and azobisisobutyramidine hydrochloride is 100:0.2:10:0.1.

[0024] Furthermore, in S2, the molar ratio of dodecylamine to acetic acid is 1:1, and the mass concentration of acetic acid is 98%.

[0025] Furthermore, in step S2, the mass ratio of dodecylamine to water is 1:100.

[0026] Furthermore, in step S2, the mass ratio of acetic acid to water is 1:65.27 in the step of preparing the acetic acid solution.

[0027] Furthermore, in S3, the slurry concentration is 40%.

[0028] Furthermore, in S3, the ratio of corn starch to iron ore is: 400g of corn starch per ton of iron ore;

[0029] The ratio of calcium oxide to iron ore is: 500g of calcium oxide per ton of iron ore.

[0030] The ratio of polystyrene nanoparticle emulsion to iron ore shown is: 700g of polystyrene nanoparticle emulsion per ton of iron ore.

[0031] The ratio of dodecylamine solution to iron ore is: 70g of dodecylamine solution per ton of iron ore;

[0032] The ratio of foaming agent to iron ore is 14g of foaming agent per ton of iron ore.

[0033] Furthermore, in S3, the ratio of calcium oxide added during the refining process to iron ore is 250g of calcium oxide per ton of iron ore, and the ratio of dodecylamine solution added during the refining process to iron ore is 35g of dodecylamine solution per ton of iron ore.

[0034] The foam product obtained from the beneficiation process is used as the final concentrate. The scavenging process includes scavenging one and scavenging two. The tailings from the beneficiation process and the foam product from scavenging one are returned to the roughing process. The tailings from scavenging one enter the scavenging two process. The foam product from scavenging two is returned to the scavenging one process. The tailings from scavenging two are used as the final tailings product.

[0035] The beneficial effects of this invention are as follows:

[0036] This invention enhances the desilication effect of iron ore reverse flotation by adding polystyrene nanoparticles as a reinforcing agent to the iron ore reverse flotation process.

[0037] Polystyrene nanoparticles can enhance the hydrophobic properties of quartz minerals by targeted adsorption, while effectively inhibiting the non-specific adsorption of collector molecules on iron ore surfaces, thus effectively reducing the risk of entrainment of target minerals.

[0038] Polystyrene nanoparticles, as auxiliary carriers for flotation reagents, can promote the stable adsorption of collectors on the surface of quartz minerals. Attached Figure Description

[0039] Figure 1 Flowchart of pure quartz mineral flotation;

[0040] Figure 2 This is the flotation rate curve of pure quartz mineral in the experimental example of this invention;

[0041] Figure 3 The diagram shows the change in hydrophobicity of pure quartz mineral after treatment with different reagents in the experimental examples of this invention. In the diagram, a represents no reagent treatment; b represents treatment with dodecylamine; and c represents treatment with a combination of polystyrene emulsion and dodecylamine.

[0042] Figure 4 This is a flow chart of the iron ore reverse flotation process in Embodiment 2 of the present invention. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, specific embodiments of the invention are described in detail, but are not limited thereto. Unless otherwise specified, the raw materials used in the embodiments are all commercially available products; and unless otherwise specified, the methods used are methods commonly used in the art.

[0044] Example 1

[0045] Preparation of nanoparticle solutions:

[0046] a. Take 0.2g of emulsifier cetyltrimethylammonium bromide in 100g of deionized water, and after it is fully dissolved, add 10g of monomer styrene and stir at room temperature for 24h to allow the emulsifier to be fully emulsified;

[0047] b. Inject nitrogen gas, add the initiator azobisisobutyramidine hydrochloride under nitrogen atmosphere protection, heat to 75°C and keep the temperature constant. After 0.5 h, turn off the nitrogen gas and continue stirring for 24 h. After the reaction is completed, cool to room temperature to obtain polystyrene nanoparticle emulsion.

[0048] Preparation of dodecylamine solution as flotation collector:

[0049] Because dodecylamine is poorly soluble in deionized water as a flocculent substance, and for experimental purposes, it is usually necessary to prepare it as a salt with acidic reagents. The preparation process for dodecylamine and acetic acid in a 1:1 molar ratio to form acetate is as follows:

[0050] 1) To further promote the dissolution process of dodecylamine, 0.4634 g of dodecylamine was weighed and placed in a beaker containing 463 mL of water, and then heated to 60 °C and stirred in a water bath.

[0051] 2) Since it is difficult to measure 98% acetic acid by volume, in order to ensure the accuracy of the experiment, the mass was converted to 0.1532g. The cleaned beaker was placed on the analytical balance to remove the tare and add 10 mL of water to dilute it.

[0052] 3) Pour the acetic acid solution into a beaker containing dodecylamine and add water to 500 mL, and keep heating at 60°C while stirring until the solution is clear and transparent without any flocculent matter.

[0053] 4) The prepared dodecylamine solution can be used multiple times, but it needs to be heated and stirred before use to ensure the accuracy of the test.

[0054] Experimental Example

[0055] To verify the feasibility of polystyrene nanoparticles in the reverse flotation desilication of iron ore, they were first applied to the flotation experiment of pure quartz minerals.

[0056] The experimental procedure is as follows:

[0057] Single-mineral flotation experiments were conducted using an XFD-II type 500mL aerated hanging-cell flotation machine, with the rotor speed set at 1900 r / min. Each flotation operation used 25g of mineral, which was added to distilled water and stirred for 2 minutes. Then, a 70g / t dodecylamine collector solution was added to the slurry surface (in the verification experiment, a 700g / t nanoparticle solution was added first, stirred thoroughly for 3 minutes, and then the dodecylamine was added). After 1 minute, a 14g / t frother (2-octanol) was added to the slurry surface. After stirring for 10 seconds, the air inlet valve was opened, and froth scraping began simultaneously. Froth products were scraped in batches at 30s, 60s, 120s, and 180s. After 3 minutes of flotation, the froth product and the product in the cell were filtered, dried, and weighed separately. The yield of the froth product was the flotation recovery rate. The specific flotation process is as follows: Figure 1 As shown.

[0058] Experimental results are as follows Figure 2 As shown, by Figure 2It can be seen that the recovery rate increases with time and eventually reaches a maximum under different test conditions. Without the addition of polystyrene nanoparticle solution and dodecylamine during the flotation process, the final flotation recovery rate is only 2.68%. However, when only one of the polystyrene nanoparticle solution or dodecylamine is added as a collector, the flotation recovery rates increase to 10.24% and 17.37%, respectively. This indicates that both can produce a certain promoting effect when used alone as collectors in the flotation of pure quartz minerals. When polystyrene nanoparticle solution is added and thoroughly stirred before adding dodecylamine, the final recovery rate can increase to 35.16%, showing a very significant improvement in flotation efficiency. Furthermore, although both polystyrene nanoparticle solution and dodecylamine can be used as collectors individually, the final results show that the promoting effect of in-situ construction of polystyrene nanoparticles on the adsorption of dodecylamine is not a simple additive relationship between the two.

[0059] Contact angle is one of the most intuitive ways to evaluate the hydrophobicity of minerals. A larger contact angle indicates a more hydrophobic mineral surface and better buoyancy. To more intuitively compare the changes in hydrophobicity of pure quartz minerals and those treated with different agents, contact angles were measured as follows: Figure 3 As shown, when the quartz flotation sample is not treated with reagents ( Figure 3 a) The measured contact angle was only 4°, after treatment with dodecylamine ( Figure 3 b) The contact angle increased to 25°, while the quartz sample treated with polystyrene emulsion first and then with dodecylamine agent ( Figure 3 c) The contact angle can be increased to 45°, indicating that the in-situ construction of polystyrene nanoparticles on the quartz surface will promote the adsorption behavior of dodecylamine. As the contact angle increases, it indicates that its hydrophobicity also gradually increases, which is consistent with the results in the above flotation test.

[0060] Example 2

[0061] Iron ore reverse flotation desiliconization

[0062] Iron ore reverse flotation desilication experiments were conducted using an XFD-II type 500mL aerated hanging tank flotation machine, with the rotor speed set at 1900 r / min. First, to ensure a uniform and stable flotation pulp concentration of 40%, distilled water was added and stirred for 2 minutes. Then, HCl was added to the pulp solution to fix the pH at 6.5. Next, corn starch, an inhibitor, was added to the pulp at an optimal dosage of 400 g / t to reduce the hydrophobic properties of the iron ore surface, preventing it from being captured by flotation bubbles and remaining in the pulp. After thorough stirring for 3 minutes, calcium oxide, an activator, was added to the pulp at an optimal dosage of 500 g / t to activate the quartz mineral surface, laying the foundation for subsequent adsorption and modification of reagent molecules on its surface. After thorough mixing for 3 minutes, polystyrene nanoparticle emulsion was added to the slurry at an optimal dosage of 700 g / t. After further thorough mixing for 3 minutes, dodecylamine solution, a collector, was added to the slurry at an optimal dosage of 70 g / t. This solution acts directionally on the surface of the quartz minerals, enhancing their hydrophobicity and facilitating subsequent adhesion and capture of air bubbles, allowing them to float to the top of the slurry for enrichment and recovery. After thorough mixing for 3 minutes, 2-octanol, a frother, was added to the slurry at an optimal dosage of 14 g / t. After thorough mixing for 10 seconds, the flotation machine's air inlet valve was opened, and a 3-minute flotation skimming operation was performed simultaneously.

[0063] The ratio of calcium oxide to iron ore added during the subsequent refining process is 250g per ton of iron ore; the ratio of dodecylamine solution added during the refining process to iron ore is 35g per ton of iron ore. The froth product obtained from the refining process is used as the final concentrate. The tailings from the refining process and the froth product from scavenging stage one are returned to the roughing stage. The tailings from scavenging stage one enter the scavenging stage two process, and the froth product from scavenging stage two is returned to the scavenging stage one process. The tailings from scavenging stage two are used as the final tailings product. After the experiment, the remaining product in the tank and the froth product are respectively subjected to vacuum filtration and drying treatment.

[0064] Comparative Example

[0065] The comparative experiment, which corresponds to the iron ore reverse flotation desilication test in Example 2 above, did not include polystyrene nanoparticle emulsion, and the remaining steps were kept consistent with the conditions in Example 2.

[0066] The experimental results of Example 2 and the comparative example are shown in Tables 1 and 2.

[0067] Table 1. Results of closed-circuit flotation experiments using dodecylamine as the collector in the comparative example.

[0068]

[0069] Table 2. Closed-circuit flotation experiment results in Example 2 using polystyrene nanoparticle emulsion and dodecylamine as collectors.

[0070]

[0071] Table 1 shows that the reverse flotation process, consisting of one roughing, one cleaning, two scavenging operations, and middlings sequential return, yields an iron concentrate with an iron grade of 58.04%, a recovery rate of 83.36%, and an SiO2 content of 8.26% for a strong magnetic separation concentrate with HCl as a modifier, corn starch as a depressant, and calcium oxide as an activator, when using only dodecylamine as the collector at a dosage of 70 g / t. Table 2 shows that adding PS nanoparticles first, followed by dodecylamine, yields an iron concentrate with a higher iron content. For an iron concentrate with a grade of 61.59%, a recovery rate of 86.33%, and a SiO2 content of 3.75%, the flotation performance obtained when both PS nanoparticles and dodecylamine were used as collectors was better than that obtained when only dodecylamine was used as a collector. The concentrate grade increased by 3.55%, the concentrate recovery rate increased by 2.97%, the tailings grade decreased by 4.10%, and the tailings recovery rate decreased by 2.97%. This indicates that nanoparticles also have the effect of promoting the collection of quartz by dodecylamine in the actual ore sample flotation system, thereby promoting the reverse flotation of iron ore and achieving the goal of "increasing iron and reducing silicon".

[0072] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. The above embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A polystyrene nanoparticle emulsion-enhanced iron ore reverse flotation desilication process, characterized in that: Includes the following steps: S1. Preparation of polystyrene nanoparticle emulsion: a. Dissolve the emulsifier cetyltrimethylammonium bromide in deionized water according to the specified ratio. After it is fully dissolved, add the monomer styrene and stir at room temperature for 24 hours to ensure that the emulsifier is fully emulsified. b. Inject nitrogen gas, add the initiator azobisisobutyramidine hydrochloride under nitrogen atmosphere protection, heat to 75°C and keep the temperature constant. After 0.5 h, turn off the nitrogen gas and continue stirring for 24 h. After the reaction is completed, cool to room temperature to obtain polystyrene nanoparticle emulsion. S2. Preparation of dodecylamine solution as flotation collector: a. Weigh dodecylamine into a beaker containing water, place it in a water bath and heat to 60°C with stirring to obtain a dodecylamine solution; b. Weigh acetic acid into a beaker and dilute it with water to obtain an acetic acid solution; c. Pour the acetic acid solution into the dodecylamine solution, add water to 500 mL, and heat and stir at 60°C until the solution is clear and transparent without any flocculent matter; S3, Iron ore reverse flotation desilication: a. Add slurry to the flotation machine, add distilled water and stir for 2 minutes, then add HCl to the slurry solution to adjust the pH of the slurry to 6.5; b. Add the inhibitor corn starch to the slurry solution and stir well; c. After stirring evenly for 3 minutes, add the activator calcium oxide to the slurry solution; d. After stirring evenly for 3 minutes, add polystyrene nanoparticle emulsion to the slurry solution; d. After stirring evenly for 3 minutes, add the collector dodecylamine solution to the slurry solution; e. After stirring evenly for 3 minutes, add the frother octanol to the slurry solution, stir for 10 seconds, open the air inlet valve of the flotation machine, and simultaneously carry out a 3-minute flotation skimming operation, which is the roughing process. f. The foam product obtained from the rough selection is added to calcium oxide and dodecylamine solution successively, and then fine selection is performed. The product in the rough selection tank is then swept.

2. The polystyrene nanoparticle emulsion-enhanced iron ore reverse flotation desilication process according to claim 1, characterized in that: In S1, the mass ratio of deionized water, hexadecyltrimethylammonium bromide, styrene, and azobisisobutyramidine hydrochloride is 100:0.2:10:0.

1.

3. The polystyrene nanoparticle emulsion-enhanced iron ore reverse flotation desilication process according to claim 1, characterized in that: In S2, the molar ratio of dodecylamine to acetic acid is 1:1, and the mass concentration of acetic acid is 98%.

4. The polystyrene nanoparticle emulsion-enhanced iron ore reverse flotation desilication process according to claim 1, characterized in that: In step S2, the mass ratio of dodecylamine to water is 1:100 in the step of preparing the dodecylamine solution.

5. The polystyrene nanoparticle emulsion-enhanced iron ore reverse flotation desilication process according to claim 1, characterized in that: In step S2, the mass ratio of acetic acid to water in the step of preparing the acetic acid solution is 1:65.

27.

6. The polystyrene nanoparticle emulsion-enhanced iron ore reverse flotation desilication process according to claim 1, characterized in that: In S3, the slurry concentration is 40%.

7. The polystyrene nanoparticle emulsion-enhanced iron ore reverse flotation desilication process according to claim 1, characterized in that: In S3, the ratio of corn starch to iron ore is: 400g of corn starch per ton of iron ore. The ratio of calcium oxide to iron ore is: 500g of calcium oxide per ton of iron ore. The ratio of polystyrene nanoparticle emulsion to iron ore shown is: 700g of polystyrene nanoparticle emulsion per ton of iron ore. The ratio of dodecylamine solution to iron ore is: 70g of dodecylamine solution per ton of iron ore; The ratio of foaming agent to iron ore is 14g of foaming agent per ton of iron ore.

8. The polystyrene nanoparticle emulsion-enhanced iron ore reverse flotation desilication process according to claim 1, characterized in that: In S3, the ratio of calcium oxide added during the refining process to iron ore is: 250g of calcium oxide per ton of iron ore; the ratio of dodecylamine solution added during the refining process to iron ore is: 35g of dodecylamine solution per ton of iron ore.

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