Method for removing magnesium from phosphate ore by reverse flotation and application thereof

Abstract

The application discloses a method for removing magnesium from phosphate ore by reverse flotation and application, and comprises the following steps: S1, crushing, screening, grading and grinding calcium-magnesium-containing phosphate ore to obtain phosphate ore powder; S2, adding water to the phosphate ore powder to adjust the slurry, and then adjusting the pH value to 4.5-9.0 to obtain a mineral slurry; S3, adding an inhibitor solution and a collector solution into the mineral slurry in sequence, and performing flotation to remove impurities to obtain tailings and phosphate concentrate; the inhibitor solution is a fulvic acid and / or fulvic acid salt solution; the application has the advantages of no phosphorus, no pollution, small dosage, mild applicable pH range, no corrosion damage to the flotation equipment and the like by using the inhibitor fulvic acid or the salt thereof to perform the flotation, and the removal of impurities of the calcium-magnesium-containing phosphate ore can be realized only by using the short process of the reverse flotation, and the flotation and impurity removal effect is good.

Description

Technical Field

[0001] This invention relates to the field of mineral processing technology, and in particular to a method and application of reverse flotation for magnesium removal from phosphate rock. Background Technology

[0002] In addition to the target phosphate minerals, low- and medium-grade phosphate rocks often contain a certain proportion of (calcium) magnesium and siliceous gangues. These gangue minerals have a significant impact on the subsequent wet-process phosphoric acid production process. Excessive magnesium impurities significantly increase sulfuric acid consumption in the wet-process phosphoric acid production, reducing product quality and negatively impacting phosphate chemical production. Therefore, the development and research of phosphate rock demagnesification technology is particularly important. Dolomite is the most abundant calcium-magnesium gangue mineral in phosphate rock. However, the surface properties of dolomite and the target phosphate minerals are quite similar, resulting in poor selectivity and low separation efficiency of commonly used fatty acid collectors. This makes it impossible to effectively separate the target phosphate minerals from dolomite, seriously affecting the efficient development and utilization of low- and medium-grade phosphate rock resources.

[0003] Flotation is commonly used for the removal of impurities from phosphate rock, and efficient flotation reagents play a crucial role in this process. High-selectivity inhibition and removal of impurities has always been the focus of phosphate ore beneficiation and purification technology.

[0004] Therefore, it is essential to provide an efficient method for removing impurities from phosphate rock by reverse flotation. Summary of the Invention

[0005] In view of this, this application provides a method and application for reverse flotation demagnesification of phosphate rock, which is used to solve the problem of how to achieve efficient reverse flotation demagnesification of phosphate rock.

[0006] To achieve the above technical objectives, this application adopts the following technical solution:

[0007] In a first aspect, this application provides a method for magnesium removal by reverse flotation of phosphate rock, comprising the following steps:

[0008] S1. The calcium-magnesium phosphate ore is crushed, screened, classified, and ground to obtain phosphate rock powder;

[0009] S2. After adding water to the phosphate rock powder to form a slurry, adjust the pH value to 4.5-9.0 to obtain the slurry;

[0010] S3. Add inhibitor solution and collector solution to the slurry in sequence, and carry out flotation to remove impurities, to obtain tailings and phosphate concentrate; the inhibitor solution is fulvic acid and / or fulvic acid salt solution.

[0011] Preferably, in step S1, the proportion of particles with a particle size ≤74μm in the phosphate rock powder is 70-95wt%.

[0012] Preferably, in step S2, the concentration of the slurry is 20-36 wt%.

[0013] Preferably, in step S3, the collector includes sodium oleate.

[0014] Preferably, in step S3, the concentration of the inhibitor solution is 0.01-0.2wt%, and the ratio of the inhibitor to the slurry is 20-30mg:1L.

[0015] Preferably, in step S3, the concentration of the collector solution is 1-4 wt%, and the ratio of collector to slurry is 40-200 mg: 1 L.

[0016] Preferably, in step S3, after adding the inhibitor solution, the collector solution is added after an interval of 2-4 minutes.

[0017] Preferably, the process also includes filtering and drying the tailings.

[0018] Secondly, this application provides a phosphate concentrate in which the P2O5 grade is 34.58-37.89% and the MgO grade is ≤0.95%.

[0019] Thirdly, this application provides an application in the field of phosphate rock beneficiation and purification.

[0020] The beneficial effects of this application are as follows:

[0021] This invention uses fulvic acid or its salts as inhibitors for flotation, which has the advantages of being phosphorus-free, pollution-free, requiring small amounts, having a mild applicable pH range, and causing no corrosion damage to flotation equipment. It can achieve the deimpurification treatment of calcium magnesium phosphate ore through a short reverse flotation process, which has significant advantages over the forward-reverse and reverse-forward flotation processes, and greatly reduces equipment investment and operating costs. Attached Figure Description

[0022] Figure 1 This is a process flow diagram for this application. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0024] This application provides a method for magnesium removal by reverse flotation of phosphate rock, comprising the following steps:

[0025] S1. The calcium-magnesium phosphate ore is crushed, screened, classified, and ground to obtain phosphate rock powder;

[0026] S2. After adding water to the phosphate rock powder to form a slurry, adjust the pH value to 4.5-9.0 to obtain the slurry;

[0027] S3. Add inhibitor solution and collector solution to the slurry in sequence, and carry out flotation to remove impurities, to obtain tailings and phosphate concentrate; the inhibitor solution is fulvic acid and / or fulvic acid salt solution.

[0028] Fulvic acid is a multiphase, amorphous aliphatic aromatic organic acid compound synthesized by microorganisms from plant residues. Its structure contains numerous active groups such as phenolic hydroxyl and carboxyl groups, allowing it to interact with oxides, metal ions such as calcium and magnesium, and organic matter, including toxic and harmful substances. When the inhibitor of this application adsorbs onto the surface of a mineral, it reduces the surface hydrophobicity and hinders the action of the collector on the mineral surface, thereby inhibiting the mineral's flotation. Furthermore, fulvic acid or its salts are phosphorus-free, non-toxic, and environmentally friendly agents that effectively control the migration and transformation of various organic pollutants and heavy metals in water. This selectively inhibits the flotation of target phosphate minerals, widens the difference in flotation behavior between phosphate minerals and dolomite, and enables reverse flotation to remove dolomite impurities, resulting in a flotation phosphate concentrate product.

[0029] Furthermore, the inhibitor of this application exhibits a strong selective inhibitory effect on the target phosphate minerals in phosphate rock, while having no significant effect on dolomite, a calcium-magnesium carbonate mineral. By using the inhibitor of this application, efficient flotation and impurity removal of calcium-magnesium phosphate rock can be achieved. The main principle is that, compared to the calcium and magnesium atoms exposed on the surface of dolomite, the calcium atoms exposed on the surface of phosphate minerals tend to be located further away from the crystal lattice center. The inhibitor structure contains a large number of active groups such as hydroxyl and carboxyl groups, which more easily form stable chelate components with the calcium atoms exposed on the surface of phosphate minerals and are strongly adsorbed onto the surface of phosphate minerals. The attraction between the hydrophilic groups and water molecules is enhanced, strengthening the hydrophilicity of the phosphate mineral surface. Therefore, the floatability of phosphate minerals decreases, and flotation is inhibited, while dolomite maintains good floatability and its flotation is unaffected. Ultimately, this expands the difference in flotation behavior between phosphate minerals and dolomite.

[0030] In some embodiments, in step S1, the proportion of particles with a particle size ≤74μm in the phosphate rock powder is 70-95wt%.

[0031] In some embodiments, in step S2, the concentration of the slurry is 20-36 wt%.

[0032] In some embodiments, in step S3, the collector includes sodium oleate.

[0033] In some embodiments, in step S3, the concentration of the inhibitor solution is 0.01-0.2 wt%, and the ratio of the inhibitor to the slurry is 20-30 mg: 1 L.

[0034] In some embodiments, in step S3, the concentration of the collector solution is 1-4 wt%, and the ratio of collector to slurry is 40-200 mg: 1 L.

[0035] In some embodiments, in step S3, after adding the inhibitor solution, the collector solution is added after an interval of 2-4 minutes.

[0036] In some embodiments, the tailings are further filtered and dried.

[0037] This application provides a phosphate concentrate in which the P2O5 grade is 34.58-37.89% and the MgO grade is ≤0.95%.

[0038] Thirdly, this application provides an application in the field of phosphate rock beneficiation and purification.

[0039] This application utilizes the addition of fulvic acid or its salts as inhibitors to selectively suppress the flotation of apatite, effectively widening the floatability difference between phosphate minerals and gangue minerals such as dolomite and calcite in phosphate rock. This allows for the separation of phosphate minerals from dolomite and calcite through reverse flotation, removing calcium and magnesium impurities and improving the quality of the flotation phosphate concentrate. Fulvic acid or its salts can function under relatively mild pulp conditions, significantly reducing the adverse effects of traditional inorganic acid inhibitors. This simplifies existing phosphate rock flotation processes, enabling the removal of impurities from low-grade phosphate rock containing calcium and magnesium through a single reverse flotation process. Furthermore, the inhibitor fulvic acid or its salts possess significant chemical structural advantages, exhibiting low cost, non-toxicity, non-polluting properties, high dispersion, and biodegradability.

[0040] The following specific embodiments further illustrate this solution.

[0041] Example 1

[0042] A method for magnesium removal by reverse flotation of phosphate rock includes the following steps:

[0043] S1. Crushing and Grinding: A jaw crusher is used to crush and screen calcium magnesium phosphate ore (chemical composition includes P2O5 26.14%, MgO 4.99%, CaO 40.73%, Al2O3 2.17%, Fe2O3 1.49%, SiO2 7.81%, K2O 0.93%) to obtain powder with a particle size of less than 2mm. The crushed powder is then added to a ceramic ball mill and ground until the particle size of less than 74μm accounts for 80% of the powder, which is phosphate rock powder.

[0044] S2. Mechanical slurry preparation: Phosphate rock powder is mixed evenly with ultrapure water at room temperature (25℃) to obtain a mixture with a mass concentration of 33%. The mixture is fed into the flotation machine, and stirring is started to prepare the slurry for 2 minutes. Then, 0.5% HCl aqueous solution is added to the slurry to adjust the pH value to 5.5. Stirring is continued for another 2 minutes to obtain the slurry.

[0045] S3. Flotation and impurity removal: Add 0.1wt% and 15mg of fulvic acid solution to each liter of slurry, and after a 3-minute interval, add 2wt% and 100mg of sodium oleate solution as a collector. After sufficient action, aerate and scrape the froth. The flotation froth product obtained is tailings, and the product in the tank is phosphate concentrate.

[0046] Example 2

[0047] A method for magnesium removal by reverse flotation of phosphate rock includes the following steps:

[0048] S1. Crushing and Grinding: A jaw crusher is used to crush and screen the calcium-magnesium phosphate ore (chemical composition includes P2O5 21.02%, MgO 9.85%, CaO 41.27%, Al2O3 2.17%, Fe2O3 1.03%, SiO2 4.27%, K2O 0.15%) to obtain powder with a particle size of less than 2mm. The crushed powder is then added to a ceramic ball mill and ground until the particle size of the powder is less than 74μm, which is the phosphate rock powder.

[0049] S2. Mechanical slurry preparation: Phosphate rock powder is mixed evenly with ultrapure water at room temperature (25℃) to obtain a mixture with a mass concentration of 33%. The mixture is fed into the flotation machine, and stirring is started to prepare the slurry for 2 minutes. Then, 0.5% HCl aqueous solution is added to the slurry to adjust the pH value to 5.0. Stirring is continued for another 2 minutes to obtain the slurry.

[0050] S3. Flotation and impurity removal: Add 0.1wt% and 30mg of fulvic acid solution to each liter of slurry, and after a 3-minute interval, add 2wt% and 120mg of sodium oleate solution as a collector. After sufficient action, aerate and scrape the froth. The flotation froth product obtained is tailings, and the product in the tank is phosphate concentrate.

[0051] Comparative Example 1

[0052] A method for magnesium removal by reverse flotation of phosphate rock is the same as that in Example 1, except that fulvic acid solution is not added in step S3.

[0053] Comparative Example 2

[0054] A method for magnesium removal by reverse flotation of phosphate rock is the same as in Example 1, except that in step S3, the fulvic acid solution is replaced with a phosphoric acid solution.

[0055] Comparative Example 3

[0056] A method for magnesium removal by reverse flotation of phosphate rock is the same as in Example 2, except that fulvic acid solution is not added in step S3.

[0057] Comparative Example 4

[0058] A method for magnesium removal by reverse flotation of phosphate rock is the same as in Example 2, except that in step S3, the fulvic acid solution is replaced with a phosphoric acid solution.

[0059] Testing and Evaluation

[0060] The physical parameters of the phosphate concentrate products obtained from Examples 1-2 and Comparative Examples 1-4 were tested, and the results are shown in Table 1.

[0061] Table 1. Test results of phosphate concentrate

[0062]

[0063] Comparative Examples 1 and 2, without using the inhibitor of this invention or using conventional inhibitors, yielded phosphate concentrates with significantly lower P2O5 grades and higher MgO content, resulting in a P2O5 recovery rate that was approximately 20-27 percentage points lower. Comparative Examples 3 and 4, also without using the inhibitor of this invention or using conventional inhibitors, yielded phosphate concentrates with significantly lower P2O5 grades and higher MgO content, resulting in a P2O5 recovery rate that was approximately 10-24 percentage points lower. This indicates that the fulvic acid-based flotation inhibitor of this invention can significantly improve the removal of calcium and magnesium impurities in phosphate ore reverse flotation, thereby increasing the grade and recovery rate of the phosphate concentrate.

[0064] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for magnesium removal by reverse flotation of phosphate rock, characterized in that, Includes the following steps: S1. The calcium-magnesium phosphate ore is crushed, screened, classified, and ground to obtain phosphate rock powder; S2. After adding water to the phosphate rock powder to form a slurry, adjust the pH value to 4.5-9.0 to obtain the slurry; S3. Add inhibitor solution and collector solution to the slurry in sequence, and perform flotation to remove impurities, to obtain tailings and phosphate concentrate; The inhibitor solution is a fulvic acid and / or fulvic acid salt solution; In step S3, the concentration of the inhibitor solution is 0.01-0.2 wt%, and the ratio of the inhibitor to the slurry is 20-30 mg: 1 L. In step S3, the concentration of the collector solution is 1-4 wt%, and the ratio of the collector to the slurry is 40-200 mg: 1 L; In step S3, after adding the inhibitor solution, the collector solution is added after an interval of 2-4 minutes.

2. The method for demagnesification of phosphate rock by reverse flotation according to claim 1, characterized in that, In step S1, the proportion of particles with a particle size ≤74μm in the phosphate rock powder is 70-95wt%.

3. The method for demagnesification of phosphate rock by reverse flotation according to claim 1, characterized in that, In step S2, the concentration of the slurry is 20-36 wt%.

4. The method for demagnesification of phosphate rock by reverse flotation according to claim 1, characterized in that, In step S3, the collector includes sodium oleate.

5. The method for demagnesification of phosphate rock by reverse flotation according to claim 1, characterized in that, It also includes filtering and drying the tailings.

6. A phosphate concentrate obtained by the method according to any one of claims 1-5, characterized in that, The phosphate concentrate has a P2O5 grade of 34.58-37.89% and an MgO grade of ≤0.95%.

7. The application of the method as described in any one of claims 1-5 in the field of phosphate rock beneficiation and purification.

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