Method for converting niobium mineral in niobium rough concentrate into pyrochlore and method for producing niobium concentrate

Abstract

The invention discloses a method for converting niobium minerals in niobium rough concentrate into pyrochlore. The method comprises the following steps: (1) mixing the niobium rough concentrate with a modifier, a fluorine-containing reagent, a reducing agent and a binder, and carrying out compression molding; and (2) roasting the mixed blank for a set time, preserving heat, and quenching to obtain pyrochlore type rough concentrate. The method comprises the following steps: (1) carrying out magnetic separation on pyrochlore type rough concentrate; (2) performing heating and acid leaching on the magnetic separation tailings; and (3) carrying out flotation to obtain niobium concentrate. According to the method, iron components in the rough concentrate are reduced into magnetic iron minerals, niobium minerals are converted into non-magnetic pyrochlore, follow-up niobium-iron separation is facilitated, and the grade of niobium in the niobium concentrate obtained through production can be effectively improved; and the method is high in adaptability to niobium rough concentrate, is also applicable to alkaline or acidic niobium rough concentrate, is relatively small in gangue mineral change and low in conversion reaction temperature, and has the advantages of energy conservation and emission reduction compared with other regulation and control processes.

Description

Technical Field

[0001] The present invention relates to the technical field of metallurgy and ore dressing, and in particular to a method for converting niobium rough concentrate into pyrochlore and a method for producing niobium concentrate based on the method. Background Art

[0002] The Bayan Obo iron-niobium-rare earth polymetallic mine is the largest niobium resource base in my country. 2 O 5 The reserves are 2.14 million tons, and the prospective reserves are 6.6 million tons. Due to the variety of niobium-containing minerals, complex composition, fine distribution, and close symbiosis with other minerals, conventional mineral processing can only obtain Nb 2 O 5 Niobium concentrate with a grade of less than 5% cannot directly produce high-grade niobium (Nb 2 O 5 50%~60%) niobium concentrate.

[0003] The quality of ferroniobium products is positively correlated with the grade of niobium concentrate. For example, Patent 200710157964.7 discloses a method for producing low-grade ferroniobium from ferroniobium concentrate. 2 O 5 The niobium concentrate is used to prepare niobium iron containing 14.7% niobium. For example, Patent 96111328.6 discloses a two-step electric furnace smelting process for niobium concentrate to produce niobium iron. 2 O 5 Preparation of niobium iron from niobium concentrate containing 30.8% niobium; Patent 202211340668.1 discloses a method for smelting niobium iron alloy from niobium iron concentrate, with 45% Nb 2 O 5 The niobium concentrate is used to prepare ferroniobium containing 69.81% niobium.

[0004] Therefore, in order to obtain high-quality niobium iron alloy, high-grade niobium concentrate is required. 2 O 5The low grade is the key factor restricting its utilization. The main reason for the low grade of niobium concentrate is that there are many types of niobium minerals, mainly columbite, niobium-columbite, pyrochlore, which have similar properties and cannot be separated to obtain high-grade niobium concentrate. In recent years, the existing technology has begun to adopt the method of converting the niobium minerals in the niobium concentrate into a single niobium mineral with a high niobium grade (for example, ZL202110479866.5 and ZL202110481072.1 respectively disclose a method for converting niobium minerals in niobium concentrate into niobium-columbite and producing niobium concentrate, and a method for converting niobium minerals in niobium concentrate into sodium niobium ore and producing niobium concentrate), providing high-grade raw materials for subsequent mineral processing. However, the above method is not suitable for the Bayan Obo iron-niobium-rare earth polymetallic ore. Niobium and titanium in the Bayan Obo West Mine are mainly present in the form of weakly magnetic niobium-columbite and ilmenite, respectively. Direct sorting can enrich higher-grade niobium concentrate, but when the niobium concentrate Nb 2 O 5 After the grade reaches 15%, further improving the grade will lead to a significant drop in recovery rate. The reason is that the mineral composition of the niobium rough concentrate is mainly niobium iron ore and ilmenite with similar chemical properties. Traditional magnetic separation and flotation are difficult to effectively separate niobium and titanium. Therefore, how to design smelting and mineral processing technology for the Bayan Obo niobium mine with unique mineral composition to obtain high-grade niobium concentrate is a key factor in improving economic benefits and achieving full utilization of resources. Summary of the invention

[0005] The present invention provides a method for converting niobium minerals in niobium rough concentrate into pyrochlore to obtain pyrochlore-type rough concentrate, and a method for preparing niobium concentrate using the above-mentioned pyrochlore-type rough concentrate, so as to solve the technical problems that the existing Bayan Obo iron-niobium-rare earth polymetallic ore and minerals with similar compositions have low grade, are difficult to fully utilize, and have low economic value.

[0006] In order to solve the above technical problems, the technical solution proposed by the present invention is: A method for converting niobium minerals in niobium rough concentrate into pyrochlore comprises the following steps: (1) mixing the niobium crude concentrate with a modifier, a fluorine-containing reagent and a reducing agent, adding a binder and pressing to obtain a mixed material blank; (2) roasting the mixed green body at 700-950° C. for a set time under a protective atmosphere, and keeping the mixture warm for a certain time after roasting, so as to convert the niobium minerals in the niobium rough concentrate into pyrochlore, thereby obtaining a pyrochlore type rough concentrate.

[0007] The design idea of ​​the above technical solution is that after adding a reducing agent, a regulating agent and a fluorine-containing reagent to the niobium rough concentrate, it is roasted under the protection of an inert gas. After keeping warm for a certain period of time, not only the iron-containing components such as hematite / goethite / pyrite / columbite in the rough concentrate are reduced to magnetic iron minerals, but also a variety of typical niobium minerals such as columbite / columbite / calcite can be converted into a single, non-magnetic pyrochlore. The reaction formula is shown below. The pyrochlore beneficiation process is very mature and can be used to prepare high-grade and high-quality niobium products. Therefore, the present invention can increase the magnetic difference between niobium minerals and magnetic iron minerals, which is beneficial to the subsequent separation of niobium iron, and provides powerful conditions for the subsequent separation of pyrochlore-type rough concentrate: FeNb 2 O 6 +H 2 +NaF+CaO→NaCaNb 2 O 6 F+Fe+H 2 O↑; FeNb 2 O 6 +H 2 +CaF 2 →Ca 2 Nb 2 O 6 F+Fe+H 2 O↑; CaB 2 O 6 +NaF →NaCaNb 2 O 6 F; CaB 2 O 6 +CaF 2 →Ca 2 Nb 2 O 6 F; CeTiNbO 6 +NaF+O 2 →(Na,Ce)TiNbO 7 + F 2 ↑; CeTiNbO 6 +CaF 2 +O 2 →(Ca,Ce)TiNbO 7 + F 2 ↑.

[0008] As a further preferred embodiment of the above technical solution, in step (1), the niobium-containing minerals in the niobium rough concentrate include one or more of niobium iron ore, calcite, niobium ore and pyrochlore; Nb in the niobium rough concentrate2 O 5 The mass content is greater than 5%.

[0009] As a further preferred embodiment of the above technical solution, when Nb in the niobium rough concentrate is 2 O 5 When the mass content of Nb in the niobium rough concentrate is 5% to 15%, the mass ratio of the niobium rough concentrate, the reducing agent, the modifier and the fluorine-containing reagent is 100: (2 to 10): (5 to 30): (5 to 20); when the mass content of Nb in the niobium rough concentrate is 5% to 15%, the mass ratio of the niobium rough concentrate, the reducing agent, the modifier and the fluorine- 2 O 5 When the mass content of is greater than 15%, the mass ratio of the niobium rough concentrate, the reducing agent, the modifier and the fluorine-containing reagent is 100: (5-20): (5-30): (5-20).

[0010] As a further preferred embodiment of the above technical solution, when Nb in the niobium rough concentrate is 2 O 5 When the mass content of Nb is 5% to 15%, the roasting temperature in step (2) is 700 to 900°C, and the roasting time is greater than or equal to 30 minutes; Nb in the niobium crude concentrate 2 O 5 When the mass content of is greater than 15%, the roasting temperature in step (2) is 750-950°C, and the roasting time is greater than or equal to 30 minutes. For niobium rough concentrates of different grades, different component ratios and roasting parameters can be selected to achieve complete conversion of iron components in the rough concentrate and complete conversion of niobium minerals.

[0011] As a further preferred embodiment of the above technical solution, in step (2), the cooling is performed by a rapid cooling operation, and the rapid cooling operation is performed by decreasing the temperature to below 300° C. at a rate of 100-300° C. / min.

[0012] As a further preferred embodiment of the above technical solution, in step (2), the insulation operation time is 30 to 120 minutes.

[0013] As a further preferred embodiment of the above technical solution, the reducing agent includes at least one of petroleum coke, coal powder, coke, heavy oil, natural gas, water gas, carbon monoxide and hydrogen.

[0014] As a further preferred embodiment of the above technical solution, the modifier includes a calcium reagent and a sodium reagent, the calcium reagent includes at least one of limestone, fluorite, quicklime and dolomite; the sodium reagent includes at least one of sodium carbonate, sodium bicarbonate, sodium fluoride and sodium hydroxide.

[0015] As a further preferred embodiment of the above technical solution, in step (1), the binder includes at least one of PVA, water glass and clay; the mass of the binder is 1% to 5% of the sum of the mass of the niobium rough concentrate, the reducing agent, the regulating agent and the fluorine-containing reagent.

[0016] As a further preferred embodiment of the above technical solution, the pressure of the pressing molding in step (1) is 2-20 MPa.

[0017] As a further preferred embodiment of the above technical solution, the fluorine-containing reagent includes at least one of sodium fluoride, calcium fluoride, potassium fluoride and cryolite.

[0018] Based on the same technical concept, the present invention also provides a method for producing niobium concentrate, comprising the following steps: (1) magnetically separating a pyrochlore-type rough concentrate to obtain an ilmenite concentrate and tailings; the pyrochlore-type rough concentrate is obtained by the method for converting a niobium rough concentrate into pyrochlore as described in the above technical solution; (2) placing the tailings in a strong acid leaching solution and heating and leaching for a set time, separating the solid to obtain a niobium-containing concentrate; (3) flotation the niobium-containing concentrate to obtain the niobium concentrate.

[0019] As a further preferred embodiment of the above technical solution, the strong acid leaching solution includes at least one of hydrochloric acid, sulfuric acid and nitric acid.

[0020] As a further preferred embodiment of the above technical solution, the heating leaching operation adopts water bath heating, the water bath heating temperature is 65-95° C., and the heating leaching time is 15-60 min.

[0021] The present invention has the following beneficial effects: The present invention reduces the iron component in the rough concentrate into magnetic iron minerals, and converts the niobium minerals into single, non-magnetic pyrochlore, so as to widen the magnetic difference between the iron component and the niobium mineral, which is beneficial to the subsequent niobium-iron separation and can effectively improve the niobium grade in the produced niobium concentrate; and the present invention has strong adaptability to the niobium rough concentrate, and is also applicable to alkaline or acidic niobium rough concentrate, and the change of gangue minerals is small, and the conversion reaction temperature is low, which has the advantages of energy saving and emission reduction compared with other control processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A flow chart of the method for converting niobium rough concentrate into pyrochlore according to the present invention; Figure 2 This is a scanning electron microscope image of the pyrochlore type rough concentrate of Example 1; Figure 3 This is a scanning electron microscope image of the pyrochlore type rough concentrate of Example 2; Figure 4This is a scanning electron microscope image of the pyrochlore type rough concentrate of Example 3; Figure 5 The present invention is a flow chart of a method for converting niobium crude concentrate into pyrochlore and a method for preparing niobium concentrate according to Example 4. DETAILED DESCRIPTION

[0023] The present invention will be described in detail below with reference to the accompanying drawings and embodiments, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0024] Examples 1, 2 and 3 are all prepared from the preselected niobium-containing ore in Baiyunebo. 2 O 5 The main raw material is 9.95% niobium concentrate, and its chemical composition is shown in Table 1. The types of niobium-containing minerals include columbite, calcite, niobium-columbite and pyrochlore.

[0025] Table 1 Chemical composition of the niobium crude concentrate raw materials of Examples 1-3 (wt%)

[0026] Embodiment 1: The method of converting niobium rough concentrate into pyrochlore in this embodiment is as follows: Figure 1 As shown, the following steps are included: (1) Take 20g of niobium crude concentrate, add 2g of petroleum coke and 1.2g of NaF, mix thoroughly in a powder making machine, add 2mL of 5% PVA solution, and use a press and a mold to shape the mixture (pressing pressure is 20MPa) to obtain a cylindrical mixture blank with a diameter of Φ25mm; (2) After drying in the oven for 8 hours, the mixed body is placed in a tube furnace and heated with N 2 The product was roasted at 850℃ for 1.5h under protective gas and cooled in the furnace to obtain a pyrochlore type rough concentrate. Figure 2 As shown in the figure, most of the niobium minerals in the pyrochlore type coarse concentrate are transformed into large-grained pyrochlore grains with a small amount of cracks, and the grain size is 30~50μm, as shown in the energy spectrum points 3, 4, and 5. A small part of the niobium minerals are transformed into dense small-grained sodium niobite grains, and the grain size is 10~20μm, as shown in the energy spectrum points 1 and 2. Figure 2 shown.

[0027] Embodiment 2: The method of converting niobium rough concentrate into pyrochlore in this embodiment comprises the following steps: (1) Take 20g of niobium crude concentrate, add 2g of petroleum coke, 1.2g of NaF and 1.5g of CaO reagent, mix them thoroughly in a powder making machine, add 2mL of 5% PVA solution, and use a press and a mold to shape the mixture (pressing pressure is 20MPa) to obtain a cylindrical mixture blank with a diameter of Φ25mm; (2) After drying in the oven for 8 hours, the mixed body is placed in a tube furnace and heated with N 2 The product was roasted at 750℃ for 1.5h under protective gas and cooled in the furnace to obtain a pyrochlore type rough concentrate. Figure 3 80% of the niobium minerals are converted into large-grained pyrochlore grains with a small amount of cracks, and the grain size is 30~70μm, as shown in the energy spectrum points 3, 4, 5, 6, and 7; some pyrochlore centers are unconverted niobium iron ore, as shown in the energy spectrum points 1 and 2. Figure 3 shown.

[0028] Embodiment 3: The method of converting niobium rough concentrate into pyrochlore in this embodiment comprises the following steps: (1) Take 20g of niobium concentrate, add 2g of petroleum coke, 1.2g of NaF and 1.5g of CaF 2 The reagents were fully mixed by a powder making machine, and then 2 mL of 5% PVA solution was added. The mixture was molded by a press machine and a mold (the pressing pressure was 20 MPa) to obtain a cylindrical mixture blank with a diameter of Φ25 mm; (2) After drying in the oven for 8 hours, the mixed body is placed in a tube furnace and heated with N 2 The product was roasted at 880℃ for 1h under protective gas and cooled in the furnace to obtain a pyrochlore type rough concentrate. Figure 4 As shown in the figure, more than 95% of the niobium minerals are transformed into large-grained pyrochlore grains with a small amount of cracks, and the grain size is 30~50μm, as shown in the energy spectrum points 1~7. Figure 4 shown.

[0029] Examples 4, 5 and 6 are all prepared from the preselected niobium-containing ore of Bayan Obo. 2 O 5 The niobium crude concentrate with a grade of 15.36% is the main raw material, and its chemical composition is shown in Table 2. 93% of the niobium-containing minerals are niobite, and the rest are calcite and pyrochlore.

[0030] Table 2 Chemical composition of the niobium crude concentrate raw materials of Examples 4-6 (wt%)

[0031] Embodiment 4: The method for converting niobium crude concentrate into pyrochlore and the method for preparing niobium concentrate in this embodiment are as follows: Figure 5As shown, the following steps are included: (1) Take 50g of niobium crude concentrate, add 3g of petroleum coke, 2.5g of NaF and 5g of CaCO 3 , after being fully mixed by a powder making machine, 5 mL of 5% PVA solution was added, and the mixture was molded by a press machine and a mold (the pressing pressure was 5 MPa) to obtain a cylindrical mixture blank with a diameter of Φ50 mm; (2) After drying in the oven for 24 hours, the mixed body is placed in a tube furnace and heated with N 2 The pyrochlore type rough concentrate was obtained by roasting at 850°C for 1.5 h under protective gas conditions and then rapidly cooling in air (down to below 300°C at a rate of 100°C / min); (3) Separating the pyrochlore type rough concentrate by magnetic separation to obtain niobium-containing magnetic separation tailings; (4) placing the tailings in a solution containing hydrochloric acid, acid leaching for 25 minutes in a water bath at 80°C, cooling and filtering to separate the solid phase, and obtaining a niobium-containing concentrate; (5) The niobium concentrate was treated by flotation to obtain a niobium concentrate with a grade of 34.15%. The specific results are shown in Table 3.

[0032] Embodiment 5: The method for converting niobium crude concentrate into pyrochlore and the method for preparing niobium concentrate in this embodiment include the following steps: (1) Take 50g of niobium crude concentrate, add 3g of petroleum coke, 2.5g of NaF and 2.8g of CaCO 3 , after being fully mixed by a powder making machine, 5 mL of 5% PVA solution was added, and the mixture was molded by a press machine and a mold (the pressing pressure was 5 MPa) to obtain a cylindrical mixture blank with a diameter of Φ50 mm; (2) After drying in the oven for 24 hours, the mixed body is placed in a tube furnace and heated with N 2 The pyrochlore type rough concentrate was obtained by roasting at 800°C for 1.5h under protective gas conditions and then rapidly cooling in air (down to below 300°C at a rate of 300°C / min); (3) Separating the pyrochlore type rough concentrate by magnetic separation to obtain niobium-containing magnetic separation tailings; (4) placing the tailings in a solution containing sulfuric acid, acid leaching in a water bath at 70°C for 45 minutes, cooling and filtering to separate the solid phase, and obtaining a niobium-containing concentrate; (5) The niobium concentrate was treated by flotation to obtain a niobium concentrate with a grade of 26.32%. The specific results are shown in Table 3.

[0033] Embodiment 6: The method for converting niobium crude concentrate into pyrochlore and the method for preparing niobium concentrate in this embodiment include the following steps: (1) Take 50g of niobium crude concentrate, add 3g of petroleum coke, 2.5g of NaF and 3.5g of CaF, mix them thoroughly in a powder making machine, add 5mL of 5% PVA solution, and use a press and a mold to shape the mixture (pressing pressure is 5MPa) to obtain a cylindrical mixture blank with a diameter of Φ50mm; (2) After drying in the oven for 24 hours, the mixed body is placed in a tube furnace and heated with N 2 The pyrochlore type rough concentrate was obtained by roasting at 880°C for 1.5h under protective gas conditions and then rapidly cooling in air (reducing the temperature to below 300°C at a rate of 200°C / min). (3) Separating the pyrochlore type rough concentrate by magnetic separation to obtain niobium-containing magnetic separation tailings; (4) placing the tailings in a solution containing hydrochloric acid and sulfuric acid, acid leaching for 35 minutes in a water bath at 90°C, cooling and filtering to separate the solid phase, and obtaining a niobium-containing concentrate; (5) The niobium concentrate was treated by flotation to obtain a niobium concentrate with a grade of 41.23%. The specific results are shown in Table 3.

[0034] Table 3 Grade test results of niobium concentrate obtained in Examples 4-6 (%)

[0035] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. For those skilled in the art, improvements and changes obtained without departing from the technical concept of the present invention should also be regarded as the protection scope of the present invention.

[0036] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for converting niobium minerals in niobium rough concentrate into pyrochlore, characterized in that: The following steps are involved: (1) mixing the niobium crude concentrate with a modifier, a fluorine-containing reagent and a reducing agent, adding a binder and pressing to obtain a mixed material blank; (2) roasting the mixed green body at 700-950° C. for a set time under a protective atmosphere, and cooling after the roasting is completed, so that the niobium minerals in the niobium rough concentrate are converted into pyrochlore, thereby obtaining a pyrochlore-type rough concentrate.

2. The method for converting niobium rough concentrate into pyrochlore according to claim 1, characterized in that: In step (1), the niobium-containing minerals in the niobium rough concentrate include one or more of niobium iron ore, calcite, columbite and pyrochlore; and the mass content of Nb2O5 in the niobium rough concentrate is greater than 5%.

3. The method for converting niobium rough concentrate into pyrochlore according to claim 2, characterized in that: When the mass content of Nb2O5 in the niobium rough concentrate is 5%~15%, the mass ratio of the niobium rough concentrate, the reducing agent, the modifier and the fluorine-containing reagent is 100: (2~10): (5~30): (5~20); when the mass content of Nb2O5 in the niobium rough concentrate is greater than 15%, the mass ratio of the niobium rough concentrate, the reducing agent, the modifier and the fluorine-containing reagent is 100: (5~20): (5~30): (5~20).

4. The method for converting niobium crude concentrate into pyrochlore according to claim 3, characterized in that: When the mass content of Nb2O5 in the niobium rough concentrate is 5%~15%, the roasting temperature in step (2) is 700~900℃, and the roasting time is greater than or equal to 30min; when the mass content of Nb2O5 in the niobium rough concentrate is greater than 15%, the roasting temperature in step (2) is 750~950℃, and the roasting time is greater than or equal to 30min.

5. The method for converting niobium crude concentrate into pyrochlore according to claim 1, characterized in that: In step (2), the cooling is performed by rapid cooling, and the rapid cooling is performed by decreasing the temperature to below 300°C at a rate of 100-300°C / min.

6. The method for converting niobium rough concentrate into pyrochlore according to claim 1, characterized in that: In step (2), the heat preservation operation time is 30 to 120 minutes.

7. The method for converting niobium rough concentrate into pyrochlore according to any one of claims 1 to 6, characterized in that: The reducing agent includes at least one of petroleum coke, coal powder, coke, heavy oil, natural gas, water gas, carbon monoxide and hydrogen.

8. The method for converting niobium rough concentrate into pyrochlore according to any one of claims 1 to 6, characterized in that: The modifier includes a calcium reagent and / or a sodium reagent, wherein the calcium reagent includes at least one of limestone, fluorite, quicklime and dolomite; and the sodium reagent includes at least one of sodium carbonate, sodium bicarbonate, sodium fluoride and sodium hydroxide.

9. The method for converting niobium rough concentrate into pyrochlore according to any one of claims 1 to 6, characterized in that: In step (1), the binder comprises at least one of PVA, water glass and clay; the mass of the binder is 1% to 5% of the sum of the mass of the niobium rough concentrate, the reducing agent, the regulating agent and the fluorine-containing reagent.

10. The method for converting niobium rough concentrate into pyrochlore according to any one of claims 1 to 6, characterized in that: The pressure of the pressing molding in step (1) is 2-20 MPa.

11. The method for converting niobium rough concentrate into pyrochlore according to any one of claims 1 to 6, characterized in that: The fluorine-containing reagent includes at least one of sodium fluoride, calcium fluoride, potassium fluoride and cryolite.

12. A method for producing niobium concentrate, characterized in that: The following steps are involved: (1) magnetically separating a pyrochlore-type coarse concentrate to obtain an ilmenite concentrate and tailings; the pyrochlore-type coarse concentrate is obtained by the method according to any one of claims 1 to 11; (2) placing the tailings in a strong acid leaching solution and heating and leaching for a set time, separating the solid to obtain a niobium-containing concentrate; (3) flotation the niobium-containing concentrate to obtain the niobium concentrate.

13. The method for producing niobium concentrate according to claim 12, characterized in that: The strong acid leaching solution includes at least one of hydrochloric acid, sulfuric acid and nitric acid.

14. The method for producing niobium concentrate according to claim 12 or 13, characterized in that: The heating leaching operation adopts water bath heating, the water bath heating temperature is 65-95° C., and the heating leaching time is 15-60 minutes.

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