Synergist for rare earth flotation collecting agent and method for carrying out rare earth flotation by utilizing synergist

Abstract

The invention provides a synergist for a rare earth flotation collector and a method for carrying out rare earth flotation by using the synergist. The synergist comprises the following raw material components: isodecanol polyoxyethylene ether and octylphenol polyoxyethylene ether, and the raw material components are proportioned according to a proper weight ratio; the synergist can enhance the mineral separation efficiency of the hydroxamic acid collecting agent on rare earth minerals so as to improve the recovery rate of the rare earth minerals, and meanwhile, the synergist has the characteristics of being simple in formula, free of pungent smell, easy to implement and the like. The synergist disclosed by the invention is formed by compounding two medicaments, and the raw materials of the medicaments are industrial-grade products and are wide in source and easy to obtain. The synergist has no collecting effect, original flotation conditions do not need to be changed when the synergist and a collecting agent are used in a combined mode or in a mixed mode, the adding amount of the synergist is 5%-12% of the using amount of the collecting agent, the flotation index can be remarkably improved, and the subsequent process and return water recycling are not affected.

Description

Technical Field

[0001] The invention belongs to the technical field of rare earth flotation, and in particular relates to a synergist used as a rare earth flotation collector and a method for performing rare earth flotation using the synergist. Background Art

[0002] Although my country has relatively rich rare earth resources, most of them are low-grade rare earths and difficult-to-select rare earths. Flotation is often used to obtain high-grade rare earths from low-grade rare earths. Flotation has stronger adaptability to ores and higher mineral processing efficiency, so it is widely used in actual production. Hydroxamic acid collectors were developed in the 1980s and are currently the most mainstream rare earth flotation collectors. The hydroxamic acid collectors currently used for rare earth flotation mainly include: C7-C9 alkyl hydroxamic acid, 2-hydroxy-3-naphthohydroxamic acid (H205), 1-hydroxy-2-naphthohydroxamic acid (H203), salicylic hydroxamic acid (L102), cycloalkyl hydroxamic acid, benzohydroxamic acid, etc., as well as composite reagents of various different hydroxamic acids. Hydroxamic acid rare earth collectors have good rare earth selectivity, but they also have poor low temperature resistance, poor water solubility, poor foaming ability, and poor collection ability. In the flotation process, a large amount of use, slurry heating, or the use of foaming agent No. 2 oil is often required to achieve the rare earth flotation process. This leads to low mineral processing efficiency or excessively high production costs. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a synergist for rare earth flotation collectors and a method for rare earth flotation using the synergist. The synergist of the present invention can form a co-adsorption effect with a hydroxamic acid collector on the surface of the mineral, thereby increasing the collection capacity of rare earth minerals; forming a colloidal solution for hydroxamic acid collector molecules that are poorly soluble in water, thereby increasing their solubility; changing the surface tension of the ore pulp, increasing the foam stability and adjusting the foam size during the flotation process; thereby helping to enhance the flotation efficiency of the hydroxamic acid collector for rare earth minerals. At the same time, the synergist of the present invention also has the characteristics of simple formula, wide source, no irritating odor, and easy implementation. The technical solution of the present invention is: A synergist for a rare earth flotation collector, the raw material components of which include isomeric decanol polyoxyethylene ether and octylphenol polyoxyethylene ether. It is further preferred that the raw material components of the synergist for rare earth flotation collector include 8-10 parts by weight of isomeric decanol polyoxyethylene ether and 0-2 parts by weight of octylphenol polyoxyethylene ether. The polymerization degree of the isomeric decanol polyoxyethylene ether is 5-9, and the polymerization degree of the octylphenol polyoxyethylene ether is 10-13. The purity of the isomeric decanol polyoxyethylene ether and octylphenol polyoxyethylene ether is 70%-98%. The isomeric decanol polyoxyethylene ether is one or a mixture of several of E-1005, E-1006, E-1007 and E-1009. The octylphenol polyoxyethylene ether is OP-10 and / or OP-13. A method for rare earth flotation using the synergist comprises the following steps: (1) adding water glass, a collector and a synergist to the rare earth ore in sequence, and performing rough separation to obtain a concentrated ore and tailings; (2) adding water glass, a collector and a synergist to the concentrated ore 1 in sequence, and after the first concentration, obtaining the concentrated ore 2 and the medium ore 1; (3) Sodium silicate, a collector and a synergist are sequentially added to the concentrated ore 2, and after a second concentration, rare earth concentrate and middling ore 2 are obtained. In steps (1) to (3), the dosage of the synergist is 5% to 12% of the dosage of the collector; The collector is one of benzohydroxamic acid, salicylic hydroxamic acid and octyl hydroxamic acid or a mixture of several of them. In steps (1) to (3), the synergist and the collector are first mixed evenly and then added into the flotation process. In step (1), the amount of water glass added is 1500 g / t, the amount of collector added is 500-1000 g / t, and the amount of synergist added is 50-120 g / t; In step (2), the amount of water glass added is 200 g / t, the amount of collector added is 250-500 g / t, and the amount of synergist added is 25-60 g / t; In step (3), the amount of water glass added is 50 g / t, the amount of collector added is 100-200 g / t, and the amount of synergist added is 10-24 g / t. The inventors of the present application have found in long-term research that a synergist is prepared by using isomeric decanol polyoxyethylene ether and octylphenol polyoxyethylene ether in a specific weight ratio (8-10 parts by weight of isomeric decanol polyoxyethylene ether and 0-2 parts by weight of octylphenol polyoxyethylene ether); firstly, the synergist can effectively reduce the surface tension of the collector in the solution, so that it can be more evenly dispersed in the slurry, thereby effectively improving the contact opportunity between the collector and the mineral surface and enhancing the beneficiation efficiency of hydroxamic acid collectors for rare earth minerals; secondly, the synergist is co-adsorbed on the mineral surface with the collector by utilizing its own hydrogen bonding effect, thereby increasing the hydrophobicity of the mineral surface and reducing the dosage of the agent; in addition, the HLB value of the synergist is about 15, which can form more and more stable micro-nano bubbles in the slurry solution, which is conducive to the flotation of fine-grained minerals, thereby improving the recovery rate of rare earth minerals. The beneficial effects of the present invention are: The invention provides a synergist for a rare earth flotation collector. The raw material components include isomeric decanol polyoxyethylene ether and octylphenol polyoxyethylene ether in an appropriate weight ratio. The prepared synergist can form a co-adsorption effect with a hydroxamic acid collector on the surface of a mineral, thereby increasing the collection capacity of rare earth minerals; forming a colloidal solution for hydroxamic acid collector molecules that are poorly soluble in water, thereby increasing their solubility; changing the surface tension of the ore pulp, increasing the foam stability and adjusting the foam size during the flotation process; thereby helping to enhance the flotation efficiency of the hydroxamic acid collector for rare earth minerals. The synergist of the invention is compounded from two agents, and the used agent raw materials are industrial-grade products. The raw material sources are wide and easy to obtain, the formula is simple, there is no irritating smell, and it is easy to implement. The synergist of the present invention has no collecting effect by itself. When used in combination or mixed with a collector, there is no need to change the original flotation conditions. The amount of the synergist added is 5%-12% of the collector amount, which can significantly improve the flotation index without affecting the subsequent process and the reuse of returned water. In addition, the synergist of the present invention is used in rare earth flotation process with significant effect and has obvious technical and economic advantages. BRIEF DESCRIPTION OF THE DRAWINGS In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work. Figure 1a Shown is a flotation flow chart used in Examples 1-3 of the present invention; Figure 1b Shown is the flotation flow chart used in Examples 4-6 of the present invention; Figure 2 Shown is the flotation flow chart used in Comparative Examples 1-3 of the present invention. DETAILED DESCRIPTION To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention. The above technical solution is described in detail below in conjunction with specific examples. All reagents in the following examples are commercially available products unless otherwise specified. The rare earth ore of the present invention is a rare earth ore in Inner Mongolia, and the REO grade of the rare earth ore is 6.18%, wherein the content of rare earth minerals such as fluorocarbon cerium ore and monazite is 8.59%, the content of iron-containing minerals such as magnetite / hematite, ilmenite and pyrite is 16.89%, the content of (iron-containing) silicate minerals such as amphibole, mica and quartz is 11.53%, and the content of calcium-barium gangue minerals such as fluorite, dolomite, calcite, apatite and barite reaches 41.06%. Example 1 The present embodiment provides a synergist for a rare earth flotation collector, wherein the raw material composition is: isomeric decanol polyoxyethylene ether (E-1005, with a polymerization degree of 5 and a purity of 90%) and octylphenol polyoxyethylene ether (OP-10, with a polymerization degree of 10 and a purity of 80%) uniformly mixed in a mass ratio of 8:2. Further, this embodiment also includes a method for rare earth flotation using the synergist, first grinding the rare earth ore to -0.074mm mass ratio of 92%, the flotation temperature is 60 ° C, the pulp concentration is 75%, the pulp pH value is 6.8, and then the following steps are performed (such as Figure 1a shown): (1) adding water glass, benzohydroxamic acid and a synergist (specific amounts are shown in Table 1) to the rare earth ore in sequence, stirring for 2 minutes, and then performing roughing to obtain a concentrated ore and tailings; (2) adding water glass, benzohydroxamic acid and a synergist (specific amounts are shown in Table 1) to the selected ore 1 in sequence, stirring for 2 minutes, and then performing the first selection to obtain the selected ore 2 and the medium ore 1; (3) Sodium silicate, benzohydroxamic acid and a synergist (specific amounts are shown in Table 1) were added to the selected ore 2 in sequence, and after stirring for 2 minutes, a second selection was performed to obtain a rare earth concentrate and a middling ore 2. The one-rough-two-fine open circuit test of this embodiment yielded a rare earth concentrate with an REO grade of 52.34% and an operating recovery rate of 55.16%. Example 2 The present embodiment provides a synergist for a rare earth flotation collector, wherein the raw material composition is: isomeric decanol polyoxyethylene ether (E-1005, with a degree of polymerization of 5 and a purity of 90) and octylphenol polyoxyethylene ether (OP-10, with a degree of polymerization of 10 and a purity of 80) uniformly mixed in a mass ratio of 9:1. Further, this embodiment also includes a method for rare earth flotation using the synergist, first grinding the rare earth ore to -0.074mm mass ratio of 92%, the flotation temperature is 55 ° C, the pulp concentration is 72%, the pulp pH value is 6.8, and then the following steps are performed (such as Figure 1a shown): (1) adding water glass, salicylic hydroxamic acid and a synergist (specific amounts are shown in Table 1) to the rare earth ore in sequence, stirring for 3 minutes, and then performing roughing to obtain a concentrated ore and tailings; (2) adding water glass, salicylic hydroxamic acid and a synergist (specific amounts are shown in Table 1) to the selected ore 1 in sequence, stirring for 3 minutes, and then performing the first selection to obtain the selected ore 2 and the medium ore 1; (3) Sodium silicate, salicylic hydroxamic acid and a synergist (specific amounts are shown in Table 1) were added to the selected ore 2 in sequence, and after stirring for 3 minutes, a second selection was performed to obtain a rare earth concentrate and a middling ore 2. The one-rough-two-fine open circuit test of this embodiment yielded a rare earth concentrate with an REO grade of 51.23% and an operating recovery rate of 52.36%. Example 3 This embodiment provides a synergist for a rare earth flotation collector, the raw material composition of which is: isomeric decanol polyoxyethylene ether (E-1009, degree of polymerization is 9, purity is 90%). Further, this embodiment also includes a method for rare earth flotation using the synergist, first grinding the rare earth ore to -0.074mm mass ratio of 92%, the flotation temperature is 60 ° C, the pulp concentration is 75%, the pulp pH value is 6.8, and then the following steps are performed (such as Figure 1a shown): (1) adding water glass, octyl hydroxamic acid and a synergist (specific amounts are shown in Table 1) to the rare earth ore in sequence, stirring for 2 minutes, and then performing roughing to obtain a concentrated ore and tailings; (2) adding water glass, octyl hydroxamic acid and a synergist (specific amounts are shown in Table 1) to the selected ore 1 in sequence, stirring for 2 minutes, and then performing the first selection to obtain the selected ore 2 and the medium ore 1; (3) Water glass, octyl hydroxamic acid and a synergist (specific amounts are shown in Table 1) were added to the selected ore 2 in sequence, and after stirring for 2 minutes, a second selection was performed to obtain a rare earth concentrate and a middling ore 2. The one-coarse and two-fine open circuit test of this embodiment obtained a rare earth concentrate with an REO grade of 50.17% and an operating recovery rate of 50.36%. Example 4 The present embodiment provides a synergist for a rare earth flotation collector, wherein the raw material composition is: isomeric decanol polyoxyethylene ether (E-1009, with a polymerization degree of 9 and a purity of 90%) and octylphenol polyoxyethylene ether (OP-13, with a polymerization degree of 13 and a purity of 80%) uniformly mixed in a mass ratio of 9:1. Further, this embodiment also includes a method for rare earth flotation using the synergist, first grinding the rare earth ore to -0.074mm mass ratio of 92%, the flotation temperature is 60 ° C, the pulp concentration is 74%, the pulp pH value is 7.2, and then the following steps are performed (such as Figure 1b shown): (1) firstly, benzohydroxamic acid and a synergist are uniformly mixed to obtain a composite collector, then water glass and a composite collector are sequentially added to the rare earth ore (specific amounts are shown in Table 1), stirred for 3 minutes, and then roughly separated to obtain a selected ore and tailings; (2) First, benzohydroxamic acid and a synergist are uniformly mixed to obtain a composite collector, and then water glass and a composite collector are sequentially added to the selected ore 1 (specific amounts are shown in Table 1), and after stirring for 3 minutes, the first selection is performed to obtain the selected ore 2 and the medium ore 1; (3) Benzohydroxamic acid and the synergist were first mixed uniformly to obtain a composite collector, and water glass and the composite collector were added to the selected ore 2 in sequence (specific amounts are shown in Table 1), and after stirring for 3 minutes, a second concentration was performed to obtain a rare earth concentrate and a middling ore 2. The one-rough-two-fine open circuit test of this embodiment yielded a rare earth concentrate with an REO grade of 54.68% and an operating recovery rate of 52.66%. Example 5 The present embodiment provides a synergist for a rare earth flotation collector, wherein the raw material composition is: isomeric decanol polyoxyethylene ether (E-1006, with a polymerization degree of 6 and a purity of 90%) and octylphenol polyoxyethylene ether (OP-13, with a polymerization degree of 13 and a purity of 80%) uniformly mixed in a mass ratio of 9:1. Further, this embodiment also includes a method for rare earth flotation using the synergist, first grinding the rare earth ore to -0.074mm mass ratio of 92%, the flotation temperature is 60 ° C, the pulp concentration is 73%, the pulp pH value is 7.2, and then the following steps are performed (such as Figure 1b shown): (1) First, salicylic acid and a synergist are uniformly mixed to obtain a composite collector, and then water glass and a composite collector are sequentially added to the rare earth ore (specific amounts are shown in Table 1), and after stirring for 2 minutes, rough separation is performed to obtain a selected ore and tailings; (2) First, salicylic acid and a synergist are mixed uniformly to obtain a compound collector, and then water glass and a compound collector are added to the selected ore 1 in sequence (specific amounts are shown in Table 1), and after stirring for 2 minutes, the first selection is performed to obtain the selected ore 2 and the medium ore 1; (3) First, salicylic acid and a synergist are mixed uniformly to obtain a composite collector, and water glass and a composite collector are added to the selected ore 2 in sequence (specific amounts are shown in Table 1), and after stirring for 2 minutes, a second selection is performed to obtain a rare earth concentrate and a middling ore 2. The one-coarse and two-fine open circuit test of this embodiment obtained a rare earth concentrate with an REO grade of 51.17% and an operating recovery rate of 53.06%. Example 6 The present embodiment provides a synergist for a rare earth flotation collector, wherein the raw material composition is: isomeric decanol polyoxyethylene ether (E-1007, with a polymerization degree of 7 and a purity of 90%) and octylphenol polyoxyethylene ether (OP-10, with a polymerization degree of 10 and a purity of 80%) uniformly mixed in a mass ratio of 9:1. Further, this embodiment also includes a method for rare earth flotation using the synergist, first grinding the rare earth ore to -0.074mm mass ratio of 92%, the flotation temperature is 60 ° C, the pulp concentration is 75%, the pulp pH value is 6.8, and then the following steps are performed (such as Figure 1b shown): (1) First, octyl hydroxamic acid and a synergist are uniformly mixed to obtain a composite collector, and then water glass and a composite collector are sequentially added to the rare earth ore (specific amounts are shown in Table 1), and after stirring for 2 minutes, rough separation is performed to obtain a selected ore and tailings; (2) First, octyl hydroxamic acid and a synergist are uniformly mixed to obtain a composite collector, and then water glass and a composite collector are sequentially added to the selected ore 1 (specific amounts are shown in Table 1), and after stirring for 2 minutes, the first selection is performed to obtain the selected ore 2 and the medium ore 1; (3) Octyl hydroxamic acid and the synergist were first mixed uniformly to obtain a composite collector, and water glass and the composite collector were added to the selected ore 2 in sequence (specific amounts are shown in Table 1), and after stirring for 3 minutes, a second concentration was performed to obtain a rare earth concentrate and a middling ore 2. The one-rough-two-fine open circuit test of this embodiment yielded a rare earth concentrate with an REO grade of 54.72% and an operating recovery rate of 50.36%. Table 1-Specific dosage of reagents in each treatment process in Example 1-6 one coarse and two fine open circuit test Comparative Example 1 This comparative example provides a method for rare earth flotation. No synergist is added. First, the rare earth ore is ground to -0.074 mm, with a mass ratio of 92%. The flotation temperature is 60°C, the pulp concentration is 75%, and the pulp pH value is 6.8. Then, the following steps are performed (such as Figure 2 shown): (1) adding water glass, benzohydroxamic acid and No. 2 oil (specific amounts are shown in Table 2) to the rare earth ore in sequence, stirring for 2 minutes, and then performing roughing to obtain a concentrated ore and tailings; (2) adding water glass, benzohydroxamic acid and No. 2 oil (specific amounts are shown in Table 2) to the selected ore 1 in sequence, stirring for 2 minutes, and then performing the first selection to obtain the selected ore 2 and the medium ore 1; (3) Water glass and benzohydroxamic acid (specific amounts are shown in Table 2) were added to the selected ore 2 in sequence, and after stirring for 3 minutes, a second selection was performed to obtain a rare earth concentrate and a middling ore 2. Through the one-rough and two-fine open-circuit test of this comparative example, a rare earth concentrate with an REO grade of 45.68% and an operating recovery rate of 42.36% was obtained. Comparative Example 2 This comparative example provides a method for rare earth flotation. No synergist is added. First, the rare earth ore is ground to -0.074 mm with a mass ratio of 92%. The flotation temperature is 60°C, the pulp concentration is 73%, and the pulp pH value is 7.2. Then, the following steps are performed (such as Figure 2 shown): (1) adding water glass, salicylic hydroxamic acid and No. 2 oil (specific amounts are shown in Table 2) to the rare earth ore in sequence, stirring for 2 minutes, and then performing roughing to obtain a selected ore and tailings; (2) adding water glass, salicylic hydroxamic acid and No. 2 oil (specific amounts are shown in Table 2) to the selected ore 1 in sequence, stirring for 2 minutes, and then performing the first selection to obtain the selected ore 2 and the medium ore 1; (3) Water glass and salicylic hydroxamic acid (specific amounts are shown in Table 2) were added to the selected ore 2 in sequence, and after stirring for 3 minutes, a second selection was performed to obtain a rare earth concentrate and a middling ore 2. Through the one-rough-two-fine open circuit test of this comparative example, a rare earth concentrate with an REO grade of 43.22% and an operating recovery rate of 47.41% was obtained. Comparative Example 3 This comparative example provides a method for rare earth flotation. No synergist is added. First, the rare earth ore is ground to -0.074 mm with a mass ratio of 92%. The flotation temperature is 60°C, the pulp concentration is 72%, and the pulp pH value is 6.8. Then, the following steps are performed (such as Figure 2 shown): (1) adding water glass, octyl hydroxamic acid and No. 2 oil (specific amounts are shown in Table 2) to the rare earth ore in sequence, stirring for 2 minutes, and then performing roughing to obtain a selected ore and tailings; (2) adding water glass, octyl hydroxamic acid and No. 2 oil (specific amounts are shown in Table 2) to the selected ore 1 in sequence, stirring for 2 minutes, and then performing the first selection to obtain the selected ore 2 and the medium ore 1; (3) Water glass and octyl hydroxamic acid (specific amounts are shown in Table 2) were added to the selected ore 2 in sequence, and after stirring for 3 minutes, a second selection was performed to obtain a rare earth concentrate and a middling ore 2. Through the one-rough and two-fine open-circuit test of this comparative example, a rare earth concentrate with an REO grade of 44.29% and an operating recovery rate of 44.92% was obtained. Table 2-Specific dosage of reagents in each treatment process in comparative example 1-3 one coarse two fine open circuit test Comparative Example 4 The difference between this comparative example and Example 1 is that the synergist is composed of octylphenol polyoxyethylene ether (OP-10, with a degree of polymerization of 10 and a purity of 80%). The synergist of this example was used to carry out a one-coarse and two-fine open circuit test on a rare earth ore according to the same flotation method and material dosage as in Example 1, and a rare earth concentrate with a REO grade of 48.84% and an operating recovery rate of 47.13% was obtained. Comparative Example 5 The difference between this comparative example and Example 1 is that the synergist is composed of octylphenol polyoxyethylene ether (OP-13, with a degree of polymerization of 13 and a purity of 80%). The synergist of this embodiment was used to carry out a one-coarse and two-fine open circuit test on rare earth ore according to the same flotation method and material dosage as in Example 1, and a rare earth concentrate with a REO grade of 49.61% and an operating recovery rate of 48.32% was obtained. It can be seen from the data of Comparative Examples 4 and 5 that, compared with the use of isomeric decanol polyoxyethylene ether and octylphenol polyoxyethylene ether as a synergist or the use of isomeric decanol polyoxyethylene ether as a synergist, the flotation efficiency of octylphenol polyoxyethylene ether alone as a synergist is lower. Furthermore, the inventors of the present application have found in long-term research that in actual production, the amount of foam when octylphenol polyoxyethylene ether is used alone as a synergist is too large, resulting in inconvenient operation and blocked processes. The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A synergist for a rare earth flotation collector, characterized in that: The raw material components include isomeric decanol polyoxyethylene ether and octylphenol polyoxyethylene ether.

2. The synergist for rare earth flotation collector according to claim 1, characterized in that: The raw material components include 8-10 parts by weight of isomeric decanol polyoxyethylene ether and 0-2 parts by weight of octylphenol polyoxyethylene ether.

3. The synergist for rare earth flotation collector according to claim 1, characterized in that: The polymerization degree of the isomeric decanol polyoxyethylene ether is 5-9, and the polymerization degree of the octylphenol polyoxyethylene ether is 10-13.

4. The synergist for rare earth flotation collector according to claim 1, characterized in that: The purity of the isomeric decanol polyoxyethylene ether and octylphenol polyoxyethylene ether is 70%-98%.

5. The synergist for rare earth flotation collector according to claim 1, characterized in that: The isomeric decanol polyoxyethylene ether is one or a mixture of several of E-1005, E-1006, E-1007 and E-1009.

6. The synergist for rare earth flotation collector according to claim 1, characterized in that: The polyoxyethylene phenol ether is OP-10 and / or OP-13.

7. A method for rare earth flotation using the synergist according to any one of claims 1 to 6, characterized in that: The steps include: (1) adding water glass, a collector and a synergist to the rare earth ore in sequence, and performing rough separation to obtain a concentrated ore and tailings; (2) adding water glass, a collector and a synergist to the concentrated ore 1 in sequence, and after the first concentration, obtaining the concentrated ore 2 and the medium ore 1; (3) Sodium silicate, a collector and a synergist are sequentially added to the concentrated ore 2, and after a second concentration, rare earth concentrate and middling ore 2 are obtained.

8. The method for rare earth flotation using a synergist according to claim 7, characterized in that: In steps (1) to (3), the dosage of the synergist is 5% to 12% of the dosage of the collector; The collector is one of benzohydroxamic acid, salicylic hydroxamic acid and octyl hydroxamic acid or a mixture of several of them.

9. The method for rare earth flotation using a synergist according to claim 7, characterized in that: In steps (1) to (3), the synergist and the collector are first mixed evenly and then added into the flotation process.

10. The method for rare earth flotation using a synergist according to claim 7, characterized in that: In step (1), the amount of water glass added is 1500 g / t, the amount of collector added is 500-1000 g / t, and the amount of synergist added is 50-120 g / t; In step (2), the amount of water glass added is 200 g / t, the amount of collector added is 250-500 g / t, and the amount of synergist added is 25-60 g / t; In step (3), the amount of water glass added is 50 g / t, the amount of collector added is 100-200 g / t, and the amount of synergist added is 10-24 g / t.

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