Additive for controlling rare earth enrichment in reduction process of rare earth-containing phosphorite and use method thereof

Abstract

The invention provides an additive for controlling rare earth enrichment in the reduction process of rare earth-containing phosphorite and a use method, and belongs to the technical field of mineral processing. The additive comprises the following components in parts by mass: not less than 40 parts of vulcanizing agent and not more than 60 parts of stabilizer. When in use, firstly, the rare earth-containing phosphorite, the silica, the reducing agent and the additive are uniformly mixed according to a certain proportion to complete proportioning; then putting the uniformly mixed material into a reduction device, and reducing at a certain temperature to finish the reduction process; and finally, discharging the reduced slag, and cooling to normal temperature. According to the method, the trend of the rare earth in the reduction process of the rare earth-containing phosphorite can be controlled, the rare earth elements are enriched in the sulfide phase, the rare earth is enriched while the elemental yellow phosphorus is produced, the current situation that the rare earth in the yellow phosphorus slag is difficult to recycle is expected to be changed, and meanwhile, the method has the characteristics of easily available raw materials, simplicity in implementation and the like, and has important industrial application value.

Description

Technical Field

[0001] The invention relates to the technical field of mineral processing, and in particular to an additive for controlling rare earth enrichment in the reduction process of rare earth-containing phosphate ore and a use method thereof. Background Art

[0002] Rare earths have become an indispensable key element for transforming traditional industries and developing emerging industries due to their unique magnetic, optical and electrical properties. Rare earths exist in nature mainly in the form of independent minerals, and also in the form of adsorbed clay minerals, in the form of ionic compounds in mineral lattices, or as impurity elements in minerals in an isomorphous manner. Rare earth phosphate deposits usually have a high content of heavy rare earths, have great development value, and are an important reserve of rare earth resources.

[0003] Thermal process is one of the important methods for treating phosphate ore. In this process, phosphate ore, silica and coke are mixed in a certain proportion and added to an electric furnace. Under high temperature conditions, the phosphate ore is reduced to generate phosphorus gas, which is passed into a scrubber to recover phosphorus, while the rare earth elements in the phosphate ore are retained in the slag phase. At present, there is little research on the migration law of rare earth elements in the thermal reduction process, and more research is aimed at the recovery of valuable elements such as rare earths in the slag phase.

[0004] Existing studies have shown that rare earth elements are evenly distributed in the slag phase. To recover the rare earth in the slag phase, a large amount of acid is needed to dissolve the slag phase, so that the rare earth ions enter the solution, and then the rare earth elements are recovered through extraction, precipitation and ion exchange processes. Therefore, this process has the disadvantages of high acid consumption, complex process and low economic benefits. Summary of the invention

[0005] The present invention provides an additive for controlling rare earth enrichment in the reduction process of rare earth-containing phosphate ore and a method for using the additive. The additive of the present invention can enrich the rare earth in the slag phase in the sulfide phase, which is beneficial to the subsequent recovery and utilization of the rare earth elements.

[0006] In order to solve the above-mentioned invention object, the technical solution provided by the present invention is as follows:

[0007] An additive for controlling the enrichment trend of rare earth in the reduction process of rare earth-containing phosphate ore, comprising, by mass, no less than 40 parts of a sulfiding agent and no more than 60 parts of a stabilizer, wherein the sulfiding agent is a sulfate and the stabilizer is a salt or mineral containing manganese. The additive can be obtained by uniformly mixing the sulfiding agent and the stabilizer.

[0008] As mentioned above, the role of the vulcanizing agent is to provide a sulfur source for the system, while the role of the stabilizer is to maintain a certain stability of the vulcanized phase.

[0009] The method for using the additive comprises the following steps:

[0010] S1. Batching: Mix phosphate rock, silica, reducing agent and additives in proportion;

[0011] S2, reduction: the materials mixed uniformly in step S1 are placed in a reduction device for moderate reduction. Under high temperature and strong reducing atmosphere, sulfate in the vulcanizing agent is converted into sulfur ions, enters the slag phase, and combines with rare earth ions and calcium ions (or cations provided by the stabilizer) in the slag phase, and then precipitates from the slag phase to form a rare earth-rich sulfide phase, and phosphorus is reduced to a single substance, and phosphorus volatilizes in the form of gas, and the gas is passed into a scrubber to recover phosphorus;

[0012] S3, slag cooling: the slag after reduction in step S2 is discharged from the reduction device and cooled to room temperature, and the rare earth in the obtained slag is enriched in the sulfide phase.

[0013] The phosphate rock in step S1 is phosphate ore or concentrate or middlings produced by phosphate beneficiation, and the P2O5 content in the phosphate rock is greater than 20%, the total amount of rare earth oxides is greater than 0.05%, and the Fe2O3 content is less than 5%.

[0014] In the step S1, the SiO2 content of the silica is greater than 90%, the silica particle size is between 1 mm and 30 mm, and the content is greater than 90%, and the added amount is 5% to 40% of the mass of the phosphate rock.

[0015] In step S1, the reducing agent is one of coke, anthracite or bituminous coal, the fixed carbon content in the reducing agent is greater than 60%, the reducing agent particle size is between 0.5mm-15mm and the content is greater than 90%, and the added amount is 10%-30% of the mass of the phosphate rock.

[0016] The amount of the additive in step S1 is 2%-20% of the mass of the phosphate rock.

[0017] The reduction device in step S2 is an electric furnace.

[0018] In step S2, the reduction temperature is 1350° C.-1550° C., and the reduction time is 30 min-180 min.

[0019] Preferably, in step S2, the reduction temperature is 1400° C.-1500° C., and the reduction time is 60 min-120 min.

[0020] The cooling method in step S3 is one of water cooling, natural cooling or programmed cooling.

[0021] In step S3, the sulfide phase is one or more sulfides, and the rare earth exists in the sulfide in an isomorphous or other form.

[0022] Compared with the prior art, the above technical solution has at least the following beneficial effects:

[0023] The above scheme uses additives to control the enrichment of rare earths during the reduction of rare earth phosphate ore. The additives used are common and easily available industrial products or natural minerals, and the raw materials are widely available. The additives can enrich the rare earths in the sulfide phase during the reduction of rare earth phosphate ore, which is expected to change the current situation that rare earths in the slag phase are difficult to recycle, and is of great significance to the development of rare earth phosphate ore. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. 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 creative work.

[0025] Figure 1 A flow chart of the method for using the additive for controlling rare earth enrichment in the reduction process of rare earth-containing phosphate ore according to the present invention;

[0026] Figure 2 This is a SEM image of the slag phase obtained when calcium sulfate is used as an additive in an embodiment of the present invention;

[0027] Figure 3 This is a SEM image of the slag phase when calcium sulfate and manganese carbonate are additives in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0030] The invention provides an additive for controlling rare earth enrichment in phosphate ore and a use method thereof.

[0031] The additive is composed of no less than 40 parts of a vulcanizing agent and no more than 60 parts of a stabilizer by mass, wherein the vulcanizing agent is a sulfate and the stabilizer is a manganese-containing salt or mineral.

[0032] like Figure 1 The method for using the additive comprises the following steps:

[0033] S1. Batching: Mix phosphate rock, silica, reducing agent and additives in proportion;

[0034] S2, reduction: placing the material mixed evenly in step S1 in a reduction device for moderate reduction, during which phosphorus volatilizes in the form of gas, and passing the gas into a scrubber to recover phosphorus;

[0035] S3, slag cooling: the slag after reduction in step S2 is discharged from the reduction device and cooled to room temperature, and the rare earth in the obtained slag is enriched in the sulfide phase.

[0036] This will be described below with reference to specific embodiments.

[0037] Example 1

[0038] The phosphate rock used in this embodiment is a typical rare earth-containing phosphate rock. The multi-element analysis of the raw material is shown in Table 1, and the rare earth distribution analysis results are shown in Table 2. It can be seen from the table that the main rare earth elements contained in the raw material are yttrium, lanthanum, neodymium and cerium.

[0039] Table 1 Multi-element analysis results of Zhijin phosphate ore

[0040]

[0041] Table 2 Rare earth distribution analysis results of Zhijin phosphate ore (wt%)

[0042]

[0043] Follow these steps:

[0044] S1. Ingredients: Mix Zhijin phosphate rock, silica, coke (reducing agent) and CaSO4 (additive) in proportion, wherein the addition amount of silica, coke and CaSO4 is 20%, 20% and 5% of the mass of the phosphate rock respectively.

[0045] S2. Reduction: The mixed materials are placed in an electric furnace for reduction at 1400°C for 120 minutes. Under the high temperature and strong reducing atmosphere, the sulfate groups in the calcium sulfate are deoxidized and transformed into sulfur anions, which enter the slag and then combine with the calcium ions and rare earth ions in the slag to form a rare earth-rich calcium sulfide phase. Phosphorus volatilizes in the form of gas, and the gas is passed into a scrubber to recover phosphorus.

[0046] S3. Slag cooling: The slag after reduction is discharged from the reduction device, isolated from the air and naturally cooled to room temperature. The rare earth in the obtained slag is enriched in the sulfide phase.

[0047] Figure 2This is the SEM image of the slag phase when calcium sulfate is used as the sulfiding agent. The EDS results of points 1-9 in the figure are shown in Table 3. From the SEM and EDS point analysis results, it can be seen that the bright white area in the figure is mainly composed of calcium and sulfur elements, and the white area (points 7, 8) and the gray area (points 5, 6) are mainly composed of calcium, silicon, aluminum, magnesium and oxygen, which indicates that the bright white area is calcium sulfide, and the white area and the gray area are silicate substances. In the bright white area, the average contents of lanthanum and cerium are 1.17% and 0.50% respectively, while in the white area (points 7, 8) and the gray area (points 5, 6), the average contents of lanthanum and cerium are less than 0.01%, which indicates that the rare earth elements lanthanum and cerium are significantly enriched in the sulfide phase.

[0048] Table 3 Figure 2 EDS analysis results of each point in

[0049]

[0050] Example 2

[0051] The Zhijin phosphate ore in Example 1 was used as the raw material. During the batching stage, the types and amounts of silica, coke and sulfiding agent were kept unchanged, and 3% manganese carbonate was added as a stabilizer.

[0052] Reduction stage: The mixed materials are placed in an electric furnace for reduction at 1400℃ for 120min. Under high temperature and strong reducing atmosphere, manganese carbonate decomposes into manganese oxide and enters into the slag. Sulfate in calcium sulfate is deoxidized and converted into sulfur anions and also enters into the slag. In the presence of manganese ions, sulfur ions combine with manganese ions and rare earth ions to form a rare earth-rich manganese sulfide phase. During this period, phosphorus volatilizes in the form of gas, and the gas is passed into the scrubber to recover phosphorus.

[0053] Slag cooling: The slag after reduction is discharged from the reduction device, isolated from the air and naturally cooled to room temperature. The rare earth in the obtained slag is enriched in the manganese sulfide phase.

[0054] Figure 3 This is the SEM image of the slag phase when calcium sulfate is used as the sulfiding agent and manganese carbonate is used as the stabilizer. The EDS results of points 1-9 in the figure are shown in Table 4. The bright white area in the figure is mainly composed of calcium, manganese and sulfur elements, and the white area (points 6, 7, 8) and the gray area (point 5) are mainly composed of calcium, silicon, aluminum, magnesium and oxygen, which indicates that the bright white area is calcium manganese sulfide, and the white area and the gray area are silicate substances. In the bright white area, the average contents of lanthanum and cerium are 0.37% and 0.19% respectively, while in the white area (points 6, 7, 8) and the gray area (point 5), the average contents of lanthanum and cerium are 0.008% and 0.015%, which indicates that the rare earth elements lanthanum and cerium are significantly enriched in the sulfide phase.

[0055] Table 4 Figure 3 EDS analysis results of each point in

[0056]

[0057] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. An additive for controlling rare earth enrichment in the reduction process of rare earth-containing phosphate ore, characterized in that: It is composed of no less than 40 parts of a sulfiding agent and no more than 60 parts of a stabilizer by mass, wherein the sulfiding agent is a sulfate, the stabilizer is a manganese-containing salt or mineral, and the purity of the stabilizer is required to be greater than 70%.

2. The method for using the additive for controlling rare earth enrichment in the reduction process of rare earth-containing phosphate ore according to claim 1, characterized in that: The steps include: S1. Batching: Mix phosphate rock, silica, reducing agent and additives in proportion; S2, reduction: placing the material mixed evenly in step S1 in a reduction device for moderate reduction, during which phosphorus volatilizes in the form of gas, and passing the gas into a scrubber to recover phosphorus; S3, slag cooling: the slag after reduction in step S2 is discharged from the reduction device and cooled to room temperature, and the rare earth in the obtained slag is enriched in the sulfide phase.

3. The method for using the additive for controlling rare earth enrichment in the reduction process of rare earth-containing phosphate ore according to claim 2, characterized in that: The phosphate rock in step S1 is phosphate ore or concentrate or middlings produced by phosphate beneficiation, and the P2O5 content in the phosphate rock is greater than 20%, the total amount of rare earth oxides is greater than 0.05%, and the Fe2O3 content is less than 5%.

4. The method for using the additive for controlling rare earth enrichment in the reduction process of rare earth-containing phosphate ore according to claim 2, characterized in that: In step S1, the amount of silica used is 5%-40% of the mass of the phosphate rock, the amount of the reducing agent used is 10%-30% of the mass of the phosphate rock, and the amount of the additive used is 2%-20% of the mass of the phosphate rock.

5. The method for using the additive for controlling rare earth enrichment in the reduction process of rare earth-containing phosphate ore according to claim 2, characterized in that: In step S1, the reducing agent is one of coke, anthracite and bituminous coal. The fixed carbon content in the reducing agent is greater than 60%, and the content of particles with a size between 0.5 mm and 15 mm is greater than 90%.

6. The method for using the additive for controlling rare earth enrichment in the reduction process of rare earth-containing phosphate ore according to claim 2, characterized in that: The reduction device in step S2 is an electric furnace.

7. The method for using the additive for controlling rare earth enrichment in the reduction process of rare earth-containing phosphate ore according to claim 2, characterized in that: In step S2, the reduction temperature is 1350° C.-1550° C., and the reduction time is 30 min-180 min.

8. The method for using the additive for controlling rare earth enrichment in the reduction process of rare earth-containing phosphate ore according to claim 2, characterized in that: The cooling method in step S3 is one of water cooling, natural cooling or programmed cooling.

9. The method for using the additive for controlling rare earth enrichment in the reduction process of rare earth-containing phosphate ore according to claim 2, characterized in that: In step S3, the sulfidation phase is one or more sulfides.

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