Short-process flotation whitening method for phosphogypsum

Abstract

The invention discloses an ardealite short-process flotation whitening method which comprises the following steps: S1, adding water into ardealite to form ore pulp, then adding a cation collecting agent, uniformly mixing, and then adding micro-nano bubbles to form to-be-floated ore pulp; and S2, the to-be-floated ore pulp formed in the step S1 is subjected to reverse flotation, and ardealite concentrate is obtained. According to the method, the micro-nano bubbles and the flotation technology are organically combined, hydrophobic and potential modification is conducted on the surfaces of the carbon-containing impurity particles through the cation collecting agent, the micro-nano bubbles can be adsorbed on the surfaces of the carbon-containing impurity particles through the electrostatic interaction, the carbon-containing impurity particles are promoted to form larger-size agglomerates, and therefore the apparent size of the carbon-containing impurity particles is increased. And the apparent size of the particles is increased to promote collision and adhesion with bubbles, so that the selectivity and recovery rate of the phosphogypsum are improved, and high-precision separation and whitening of the phosphogypsum are realized.

Description

Technical Field

[0001] The invention relates to the technical field of non-metallic mineral flotation, and in particular to a short-process flotation whitening method for phosphogypsum. Background Art

[0002] Phosphogypsum is an industrial byproduct produced in the process of making phosphoric acid from phosphate ore and is a valuable resource for gypsum regeneration. Due to the presence of coloring impurities (including organic matter and carbon black) with carbon as the main component in phosphogypsum, the whiteness of phosphogypsum is low and the color is gray or gray-black, which seriously limits its high-value application in building materials. The large accumulation of phosphogypsum not only causes serious waste of resources, but also causes serious environmental pollution. Therefore, the coloring impurities of phosphogypsum are a practical problem that urgently needs to be solved.

[0003] At present, the commonly used method for purifying carbon impurities in phosphogypsum whitening is flotation removal. Among the existing flotation methods, the commonly used method is to add desiliconization collectors and deorganic matter collectors after phosphogypsum slurrying, and then perform positive flotation to obtain phosphogypsum concentrate, and perform two positive and two reverse four-stage flotation. This scheme uses two collectors for step-by-step treatment in the process of removing silicon and organic carbon from phosphogypsum, which increases the processing cost. Such a long process flotation not only consumes a lot of manpower, material resources, space and other costs, but also is not conducive to continuous production and reduces production efficiency, which seriously affects the recycling of phosphogypsum in my country.

[0004] Therefore, there is an urgent need to develop a flotation process with a simple process flow, low energy consumption, wide applicability and high efficiency for removing carbon-containing impurities in phosphogypsum, so as to improve the recovery rate of phosphogypsum and obtain high-quality phosphorus-content products, shorten the entire phosphogypsum production and treatment process flow, reduce costs and realize the high-value comprehensive utilization of phosphogypsum. Summary of the invention

[0005] In view of the problem of long process of current phosphogypsum whitening method, the present invention provides a short-process flotation whitening method for phosphogypsum, which can prepare phosphogypsum with high recovery rate and high whiteness, and simplifies the flotation process, which can effectively reduce the flotation whitening cost of phosphogypsum and improve the recycling efficiency of phosphogypsum.

[0006] In order to achieve the above object, the present invention provides a short-process flotation whitening method for phosphogypsum, which comprises the following steps:

[0007] S1. Add water to phosphogypsum to form a slurry, then add a cationic collector and mix evenly, and then add micro-nano bubbles to form a slurry to be floated;

[0008] S2. Reverse flotation is performed on the ore pulp to be floated formed in step S1 to obtain phosphogypsum concentrate.

[0009] In the above method, the micro-nano bubble technology is organically combined with the flotation technology, and the cationic collector performs hydrophobic and potential modification on the surface of the carbon-containing impurity particles, and the micro-nano bubbles can be adsorbed on the surface of the carbon-containing impurity particles through electrostatic action, promoting the carbon-containing impurity particles to form larger-sized agglomerates, thereby increasing the apparent size of the carbon-containing impurity particles. The increase in the apparent size of the particles can promote collision and adhesion with the bubbles, thereby improving the selectivity and recovery rate of phosphogypsum, and achieving high-precision sorting and whitening of phosphogypsum.

[0010] Specifically, in step S1, the CaSO4·2H2O content in the phosphogypsum is 85-92%, the whiteness of the phosphogypsum is 20-40%, and the particle size distribution is 50-55% below 75 μm and 45-50% above 75 μm.

[0011] Preferably, in step S1, the volume ratio of the ore pulp to the added micro-nano bubbles is 6:(4-9).

[0012] Preferably, in step S1, the mixing is firstly adding water to the phosphogypsum to mix the slurry for 1 to 3 minutes, and then adding the collector to mix the slurry for 1 to 3 minutes.

[0013] Preferably, in step S1, the cationic collector is any one of dodecylamine, tetradecylamine and octadecylamine, and the amount used is 100-600 g relative to 1 ton of dry phosphogypsum sample.

[0014] Preferably, in step S1, the micro-nano bubbles are air micro-nano bubbles, the zeta potential of the air micro-nano bubbles is -20 to -17 mV, and the particle size is 200 to 400 nm. The micro-nano bubble generator used in the present invention is a device for preparing micro-nano bubbles using a venturi tube.

[0015] In the above scheme, any one of the cationic surfactants selected from the group consisting of dodecylamine, tetradecylamine and octadecylamine is used to treat the surface of phosphogypsum. On the one hand, due to the unique hydrophilic and hydrophobic groups of the cationic surfactants of dodecylamine, tetradecylamine and octadecylamine, the hydrophilic ends thereof produce hydrogen bonds with the oxygen-containing functional groups on the surface of the dyeing impurities, thereby hydrophobically modifying the dyeing impurities. In addition, part of the surfactant diffuses into the water, causing its thermodynamic stability to be destroyed, thereby reducing the surface tension of the water and greatly increasing the foaming ability of the pulp. On the other hand, since the dyeing impurities are graphite with a negative surface potential, the cationic surfactants of dodecylamine, tetradecylamine and octadecylamine hydrophobically modify the surface of the graphite impurities so that the surface of the impurities presents a positive charge, and then air micro-nano bubbles are used to agglomerate and float the modified impurity particles. Since the air micro-nano bubbles present a negative charge and specifically electrostatically adsorb the positively charged impurity particles, the agglomeration of the micro-nano bubbles is strengthened, so that the impurities are better captured and floated by large bubbles, thereby optimizing the traditional flotation process and obtaining a better flotation whitening effect.

[0016] Specifically, in step S2, the reverse flotation time is 4 to 6 minutes.

[0017] Specifically, in step S2, the phosphogypsum concentrate is obtained by concentration, filtration and drying after reverse flotation; the drying temperature is 100-110°C.

[0018] The accurate matching of micro-nano bubbles with flotation technology in the present invention is the key to improving the flotation separation effect of phosphogypsum.

[0019] Through the above technical solution, the present invention achieves the following beneficial effects:

[0020] 1. The present invention uses micro-nano bubbles and flotation technology to treat phosphogypsum, which can achieve high-precision sorting of phosphogypsum, significantly improve the whiteness of phosphogypsum, and improve the recovery rate of concentrate. Its process is reasonable, the operation is simple, the flotation efficiency is high, and the amount of flotation reagents used is reduced, the operating cost is low, and the economic benefits are significant, which makes a useful exploration for the development of efficient and economical phosphogypsum flotation technology. The flotation whitening method of the present invention has been successfully applied to the flotation separation of phosphogypsum, improving the economic benefits of phosphogypsum flotation purification.

[0021] 2. The cationic collectors of the present invention, such as dodecylamine, tetradecylamine or octadecylamine, can hydrophobically and electrically modify the surface of carbon-containing impurity particles, and thus electrostatic action is conducive to the adsorption of air micro-nano bubbles on the surface of carbon-containing impurity particles, promoting the formation of larger-sized agglomerates of carbon-containing impurity particles, and improving the flotation recovery rate of phosphogypsum. In addition, the cationic surfactants of dodecylamine, tetradecylamine or octadecylamine have excellent foaming properties, do not need to add a foaming agent, have a small amount of comprehensive reagents, and have a simple process. They are excellent whitening collectors for phosphogypsum flotation, and can achieve efficient and selective capture and separation of phosphogypsum under conditions of lower reagent dosage. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a mechanism diagram of the phosphogypsum flotation whitening method according to an embodiment of the present invention;

[0023] Figure 2 It is a process flow chart of the phosphogypsum flotation whitening method according to an embodiment of the present invention;

[0024] Figure 3 1 is the XRD analysis diagram of the phosphogypsum used in the examples and comparative examples of the present invention. DETAILED DESCRIPTION

[0025] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific implementation described herein is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0026] The mechanism diagram of the phosphogypsum flotation whitening method according to the embodiment of the present invention is as follows: Figure 1 As shown in the figure, the micro-nano bubble technology is organically combined with the flotation technology. The cationic collector performs hydrophobic and potential modification on the surface of carbon-containing impurity particles. The micro-nano bubbles can be adsorbed on the surface of carbon-containing impurity particles through electrostatic action, promoting the carbon-containing impurity particles to form larger agglomerates, thereby increasing the apparent size of the carbon-containing impurity particles. The increase in the apparent size of the particles can promote collision and adhesion with the bubbles, thereby improving the selectivity and recovery rate of phosphogypsum, and achieving high-precision sorting and whitening of phosphogypsum.

[0027] The process flow chart of the phosphogypsum flotation whitening method according to the embodiment of the present invention is as follows: Figure 2 As shown, water is added to the phosphogypsum and the slurry is adjusted to a high concentration with a collector, and then micro-nano bubble water is added for flotation to obtain phosphogypsum concentrate and tailings.

[0028] XRD (X-ray diffraction) is used to analyze phosphogypsum to determine the phases in phosphogypsum, such as Figure 3 The XRD spectrum shows that the main phase in the phosphogypsum sample is dihydrate gypsum (CaSO4·2H2O), which contains a small amount of calcium sulfate (CaSO4) and quartz (SiO2). The main chemical composition analysis of phosphogypsum is shown in Table 1.

[0029] Table 1 Analysis of the main chemical components of phosphogypsum (wt.%)

[0030]

[0031] In the following examples and comparative examples, the CaSO4·2H2O content of the phosphogypsum used is 88.65%, the whiteness is 31.0%; the particle size distribution is -75 μm accounting for 52.36%, and +75 μm accounting for 47.64%. The water cavitation bubble generator used is a ZJC-NM series experimental micro-nano bubble generator.

[0032] Example 1

[0033] To prepare air micro-nano bubbles, the micro-nano bubble generator was circulated for 6 min and then allowed to stand for 2 min. A 1.0L XFD hanging tank flotation machine was used with a spindle speed of 1800 rpm and an air volume of 0.1 m 3 / min. Weigh 300g of phosphogypsum and pour it into the flotation tank, add tap water to mix the pulp for 2min to form 400mL of ore pulp, then add collector dodecylamine to mix the pulp at high concentration for 2min, the amount of collector dodecylamine is 600g / t (relative to the weight of phosphogypsum), then add 600mL of air micro-nano bubbles to continue mixing the pulp for 2min to form the ore pulp to be floated, wait for 30s and then inflate and scrape the foam, the scraping time is 6min, the scraped foam and the residue at the bottom of the tank are the phosphogypsum flotation tailings and concentrate, which are filtered, dried and weighed respectively, and the yield is calculated and the recovery rate and whiteness of the phosphogypsum are statistically analyzed.

[0034] Example 2

[0035] To prepare air micro-nano bubbles, the micro-nano bubble generator was circulated for 6 min and then allowed to stand for 2 min. A 1.0L XFD hanging tank flotation machine was used with a spindle speed of 1800 rpm and an air volume of 0.1 m 3 / min. Weigh 300g of phosphogypsum and pour it into the flotation tank, add tap water to mix the pulp for 3min to form 500mL of ore pulp, then add the collector tetradecylamine to mix the pulp at high concentration for 3min, the amount of the collector tetradecylamine is 300g / t (relative to the weight of phosphogypsum), then add 500mL of air micro-nano bubbles to continue mixing the pulp for 3min to form the ore pulp to be floated, wait for 30s and then inflate and scrape the foam, the scraping time is 5min, the scraped foam and the residue at the bottom of the tank are the phosphogypsum flotation tailings and concentrate, which are filtered, dried and weighed respectively, and the yield is calculated and the recovery rate and whiteness of the phosphogypsum are statistically analyzed.

[0036] Example 3

[0037] To prepare air micro-nano bubbles, the micro-nano bubble generator was circulated for 6 min and then allowed to stand for 2 min. A 1.0L XFD hanging tank flotation machine was used with a spindle speed of 1800 rpm and an air volume of 0.1 m 3 / min. Weigh 300g of phosphogypsum and pour it into the flotation tank, add tap water to mix the pulp for 1min to form 600mL of ore pulp, then add the collector octadecylamine to mix the pulp at high concentration for 1min, the amount of collector octadecylamine is 100g / t (relative to the weight of phosphogypsum), then add 400mL of air micro-nano bubbles to continue mixing the pulp for 2min to form the ore pulp to be floated, wait for 30s and then inflate and scrape the foam, the scraping time is 4min, the scraped foam and the residue at the bottom of the tank are the phosphogypsum flotation tailings and concentrate, which are filtered, dried and weighed respectively, and the yield is calculated and the recovery rate and whiteness of the phosphogypsum are statistically analyzed.

[0038] Comparative Example 1

[0039] Other conditions were the same as in Example 1, except that dodecylamine collector was not used, and conventional kerosene collector was used.

[0040] Comparative Example 2

[0041] Other conditions were the same as in Example 1, except that no air micro-nano bubbles were added.

[0042] Comparative Example 3

[0043] Other conditions were the same as in Example 1, except that no dodecylamine collector was added.

[0044] The flotation results of the above examples and comparative examples are shown in Table 2.

[0045] Table 2 Phosphogypsum flotation results

[0046]

[0047] From Table 2, we can conclude that:

[0048] (1) It can be seen from Example 1 and Comparative Example 1 that the dodecylamine collector has excellent flotation performance for phosphogypsum. Compared with conventional kerosene collectors, the yield, whiteness and recovery rate of phosphogypsum are increased by 30.36%, 24.10% and 30.66% respectively. Dodecylamine not only has a good whitening effect on the reverse flotation of phosphogypsum, but also has a high yield and high recovery rate, indicating that it has excellent selectivity. In addition, it has excellent self-foaming performance, does not require the addition of a foaming agent, has a small amount of comprehensive reagents, and has a simple process. It is an excellent whitening collector for reverse flotation of phosphogypsum.

[0049] (2) It can be seen from Example 1 and Comparative Example 2 that the addition of air micro-nano bubbles has a better flotation effect on phosphogypsum. Compared with the case where no air micro-nano bubbles are added, the yield, whiteness and recovery rate of phosphogypsum are increased by 22.21%, 18.25% and 20.66% respectively. Air micro-nano bubbles can promote the agglomeration of carbon-containing impurity particles and enhance the flotation effect. The addition of air micro-nano bubbles not only significantly improves the whitening effect of phosphogypsum flotation, but also the high yield and high recovery rate indicate that it has better selectivity, which enhances the flotation effect while reducing the amount of reagents used and saving costs.

[0050] (3) It can be seen from Example 1 and Comparative Example 3 that the collector dodecylamine combined with air micro-nano bubble technology has a better flotation effect on phosphogypsum. Compared with the case without adding the collector dodecylamine, the yield, whiteness and recovery rate of phosphogypsum were increased by 43.63%, 30% and 43.04% respectively. This is because dodecylamine, as a collector, fully modifies the phosphogypsum mineral, hydrophobizes and modifies the carbon-containing impurity particles in potential, and can adsorb air micro-nano bubbles on the surface of the carbon-containing impurity particles through electrostatic action, thereby promoting the formation of larger-sized agglomerates, making the flotation effect significantly improved compared with Comparative Example 3, and greatly improving the recovery rate and whiteness of phosphogypsum.

[0051] In summary, the method of the embodiment of the present invention increases the yield, whiteness and recovery rate of phosphogypsum compared with the comparative example, and the flotation effect is significantly improved. Therefore, the combination of the air micro-nano bubbles of the present invention and the cationic collector can synergistically enhance the flotation effect of phosphogypsum, and the sorting efficiency is significantly improved. At the same time, the flotation whitening method of the present invention has a simple process, is easy to operate, uses less reagents, reduces the flotation cost of phosphogypsum, and can improve the economic benefits of phosphogypsum flotation purification.

[0052] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A short-process flotation whitening method for phosphogypsum, characterized in that: The following steps are involved: S1. Add water to phosphogypsum to form a slurry, then add a cationic collector and mix evenly, and then add micro-nano bubbles to form a slurry to be floated; S2. Reverse flotation is performed on the ore pulp to be floated formed in step S1 to obtain phosphogypsum concentrate.

2. The method according to claim 1, characterized in that In step S1, the CaSO4·2H2O content in the phosphogypsum is 85-92%, the whiteness of the phosphogypsum is 20-40%, and the particle size distribution is 50-55% below 75 μm and 45-50% above 75 μm.

3. The method according to claim 1, characterized in that In step S1, the volume ratio of the ore pulp to the added micro-nano bubbles is 6:(4-9).

4. The method according to claim 1, characterized in that: In step S1, the mixing is firstly adding water to the phosphogypsum to mix the slurry for 1 to 3 minutes, and then adding the collector to mix the slurry for 1 to 3 minutes.

5. The method according to claim 1, characterized in that In step S1, the cationic collector is any one of dodecylamine, tetradecylamine and octadecylamine, and the amount used is 100-600 g relative to 1 ton of dry phosphogypsum sample.

6. The method according to claim 1, characterized in that In step S1, the micro-nano bubbles are air micro-nano bubbles, and the zeta potential of the air micro-nano bubbles is -20 to -17 mV, and the particle size is 200 to 400 nm.

7. The method according to claim 1, characterized in that In step S2, the reverse flotation time is 4 to 6 minutes.

8. The method according to claim 1, characterized in that In step S2, the phosphogypsum concentrate is obtained by concentration, filtration and drying after reverse flotation; the drying temperature is 100-110°C.

Images