A method for leaching niobium, titanium and iron from niobium-containing rough concentrate with oxalic acid

Abstract

The present invention relates to a method for leaching niobium, titanium and iron from niobium-containing rough concentrate with oxalic acid, belonging to the field of metallurgical technology. The method includes mixing the niobium-containing rough concentrate powder with an oxalic acid solution, heating and stirring for leaching; after the leached pulp is subjected to solid-liquid separation treatment, a leaching solution containing niobium, titanium and iron is obtained. The present invention uses an oxalic acid solution as a leaching agent, realizing clean and efficient extraction of niobium, titanium and iron resources from niobium-containing rough concentrate, enabling efficient leaching of niobium, titanium and iron elements. The niobium leaching rate can reach over 95%, the titanium leaching rate reaches over 85%, and the iron leaching rate reaches over 65%. Rare earths are retained in the leaching residue in the form of rare earth oxalates and can be used as raw materials for further extraction of rare earths.

Description

Technical Field

[0001] The present invention relates to the technical field of metallurgy, and particularly relates to a method for leaching niobium, titanium, and iron from niobium-containing rough concentrate with oxalic acid. Background Art

[0002] Niobium is a typical strategic rare high-melting-point metal, which has the characteristics of high temperature resistance, corrosion resistance, wear resistance, anti-deformation, and good thermal conductivity. It is widely used in fields such as steel, aerospace, atomic energy, superconductivity, and electronic information. Especially in new materials in the military industry, nuclear energy, and aerospace fields, it is one of the key materials indispensable in modern industry and cutting-edge technologies.

[0003] The Bayan Obo ore is a multi-metal associated ore containing important elements such as rare earth, niobium, titanium, and iron. Due to the large variety of niobium minerals, fine dissemination size, and low niobium grade in the ore deposit, niobium in the Bayan Obo ore generally presents the characteristics of "poor, fine, miscellaneous, and scattered". At the same time, the special property of the co-occurrence (association) of iron, niobium, titanium, and rare earth ore phases restricts the comprehensive recovery and utilization of valuable elements. Therefore, it is difficult to effectively recover Bayan Obo niobium minerals, and the utilization rate of niobium and titanium resources is almost zero. Therefore, researching and developing extraction technologies suitable for valuable components such as niobium, titanium, rare earth, and iron in low-grade niobium ores has important research value and strategic significance.

[0004] In recent years, with the progress of beneficiation processes, it is currently possible to select niobium concentrate with a Nb 2 O 5 grade of 1-6% from the Bayan Obo associated ore. As described in the patent CN202210633274.9, "A method for selecting niobium concentrate with a niobium pentoxide grade of more than 4% from Bayan Obo ore", through the flotation of rare earth minerals and fluorite minerals - desulfurization flotation - deironing flotation - niobium selection, one roughing and three cleaning flotation processes can effectively increase the niobium concentrate grade to more than 4%.

[0005] The traditional methods for decomposing niobium minerals mainly include inorganic acid decomposition method, alkali decomposition method, chlorination decomposition method, etc. The inorganic acid decomposition method mainly includes hydrofluoric acid decomposition method, sulfuric acid decomposition method, etc. After extraction separation, washing, drying, roasting and other post-treatments, niobium oxide products are obtained. Patent CN201911259902.6 discloses "A method for comprehensively recovering uranium, niobium and titanium from pyrochlore", and proposes a process for preparing niobium pentoxide products by "leaching niobium in pyrochlore with sulfuric acid and hydrofluoric acid - extraction - washing - stripping - precipitation - calcination". Patent CN202110431837.1 discloses "A method for preparing niobium pentoxide from low-grade niobium ore", and proposes a process for preparing niobium pentoxide products by "heavy medium cyclone pre-concentration - sulfation roasting - sulfuric acid leaching - high-temperature autoclaving for niobium precipitation - oxalic acid thermal dissolution - evaporation crystallization - calcination". Patent CN201310300542.6 discloses "A method for extracting niobium from Bayan Obo tailings", using niobium concentrate as raw material, through alkali roasting - hydrochloric acid leaching - re-leaching with inorganic acid - filtration to obtain niobium-containing acid leaching solution, and the inorganic acids used in the process are hydrofluoric acid and sulfuric acid.

[0006] The above-mentioned schemes all use inorganic acids to decompose niobium minerals. Although the hydrofluoric acid decomposition method is very effective for low-grade niobium ore, due to the high toxicity and volatility of the hydrofluoric acid medium, a large amount of dangerous fluorine-containing waste gas and fluorine-containing wastewater are easily generated, and the environmental pollution is very serious. Although the sulfuric acid leaching method can replace hydrofluoric acid and avoid problems such as high volatility, the sulfuric acid concentration used in the sulfuric acid leaching method is high, the leaching temperature is high, and alkali or acid roasting is required in the early stage. The roasting temperature involved in the roasting process is high, and the energy consumption cost, equipment cost and operation cost are quite high, and the process flow is long. In addition, strong acid leaching seriously corrodes the equipment and the operation process is dangerous. From the above, although the leaching rate of niobium can reach more than 95% by using inorganic acids to decompose niobium minerals, the decomposition of minerals by inorganic acids will cause serious environmental pollution and high-temperature roasting is required in the early stage. Therefore, there are problems such as long process flow, high energy consumption and complex operation. Summary of the Invention

[0007] (1) Technical problems to be solved

[0008] In view of the above-mentioned disadvantages and deficiencies of the prior art, the present invention provides a clean and environmentally friendly method for extracting niobium, titanium, and iron from niobium-containing rough concentrate, which solves various technical problems such as environmental pollution caused by the decomposition of minerals with inorganic acids. Since oxalic acid has good complexing properties and can form complexes with various high-valent metal cations, it can be used as a leaching agent for niobium, titanium, and iron in niobium-containing rough concentrate. In addition, oxalic acid only contains clean elements such as H, C, and O. Its source is extensive in biomass and can be extracted by bacterial fermentation. It can be removed by various methods such as ultraviolet decomposition when entering the environment, and will not cause environmental pollution and equipment corrosion. Therefore, using oxalic acid as a leaching agent can leach elements such as niobium, titanium, and iron in minerals under normal pressure, with the advantages of environmental friendliness, safety, and easy operation.

[0009] (II) Technical Solution

[0010] To achieve the above object, the main technical solutions adopted by the present invention include:

[0011] In the first aspect, the present invention provides a method for extracting niobium, titanium, and iron from niobium-containing rough concentrate with oxalic acid. The method includes mixing niobium-containing rough concentrate powder with oxalic acid solution, heating and stirring for leaching; after the leached pulp is subjected to solid-liquid separation treatment, a leaching solution containing niobium, titanium, and iron is obtained.

[0012] Optionally, the method includes the following steps:

[0013] (1) Using niobium-containing rough concentrate as raw material, crushing, grinding, and drying it;

[0014] (2) Preparing an oxalic acid solution as a leaching agent;

[0015] (3) Mixing the niobium-containing rough concentrate powder obtained in step (1) with the oxalic acid solution obtained in step (2), heating and stirring for leaching; after the leached pulp is filtered and washed, a leaching solution containing niobium, titanium, and iron is obtained.

[0016] Optionally, the niobium-containing rough concentrate includes Bayan Obo niobium concentrate, and the Bayan Obo niobium concentrate is obtained by beneficiating Bayan Obo ore.

[0017] Optionally, the niobium-containing rough concentrate contains niobium element, titanium element, iron element, and rare earth element.

[0018] Optionally, the composition of the niobium-containing rough concentrate by mass percentage includes: T.Fe 0 - 50%, Nb 2 O 5 1 - 10%, TiO 2 1 - 15%, REO 1 - 20%, SiO 2 5 - 30%, CaO 2 - 15%, F 2 - 15%.

[0019] Optionally, after being ground and dried, the niobium-containing rough concentrate is mixed with an oxalic acid solution.

[0020] Optionally, the amount of the niobium-containing rough concentrate ground to a particle size less than or equal to 74 μm (passing through a 200-mesh sieve after grinding) is not less than 90 wt% of the total ore amount. By grinding and sieving, the specific surface area of the concentrate powder is increased, the reaction activity is improved, and the metal elements that can complex with oxalic acid and are wrapped by the ore particles are stripped out to improve the leaching efficiency.

[0021] Optionally, the concentration of the oxalic acid solution is 0.5 - 6 mol / L.

[0022] Optionally, the liquid-solid ratio of the oxalic acid solution to the niobium-containing rough concentrate is 10 - 30 mL / g.

[0023] Optionally, the heating temperature is 60 - 110 °C, the leaching time is 1 - 8 h, and the stirring speed is 100 - 1000 r / min.

[0024] Optionally, the leaching process is carried out under normal pressure, with a small risk coefficient.

[0025] Optionally, the separation treatment includes filtering and washing the pulp to separate the leaching solution and the leaching residue; the leaching residue is rare earth retained in the form of rare earth oxalate and can be used as a raw material for further extraction of rare earth.

[0026] In the above technical solution, the concentration of the oxalic acid solution, the liquid-solid ratio of the oxalic acid solution to the niobium-containing rough concentrate during the leaching process, and the leaching time are determined according to the leaching rates of niobium, titanium, and iron. On the premise of ensuring high leaching rates of niobium, titanium, and iron, an oxalic acid solution with a concentration of 0.5 - 6 mol / L is beneficial for the leaching of niobium, titanium, and iron by oxalic acid, with a fast leaching speed and low process cost. If the concentration of the oxalic acid solution is too low, the minerals cannot be fully decomposed, seriously affecting the leaching rates of niobium, titanium, and iron; if the oxalic acid concentration is too high, it will cause waste and increase the process cost.

[0027] In the above technical solution, the leaching temperature is determined according to the leaching rates of niobium, titanium, and iron. On the premise of ensuring high leaching rates of niobium, titanium, and iron, considering from the kinetic perspective, the reaction temperature should be increased as much as possible to accelerate the reaction rate, but too high a temperature will cause high energy consumption and destroy the complexation of oxalic acid with metal niobium, titanium, and iron ions, affecting the leaching rates of niobium, titanium, and iron. Therefore, in order to minimize the process cost and improve the leaching rates of niobium, titanium, and iron, the leaching temperature is preferably 60 - 110 °C. Further, by stirring, the reactants can be fully mixed, heated evenly, and the reaction time can be shortened. However, if the stirring speed is too fast, the solid-liquid separation will occur due to different linear velocities of the solid and liquid, resulting in incomplete reaction. If the stirring speed is too slow, the reactants will not be in sufficient contact and heated unevenly, reducing the reaction rate. Therefore, the stirring speed is preferably 100 - 1000 r / min.

[0028] The present invention provides a method for leaching niobium, titanium, and iron from niobium-containing rough concentrate with oxalic acid. This method uses an oxalic acid solution as the leaching agent. By virtue of the strong complexing ability of oxalic acid, it complexes with niobium, titanium, and iron ions to form ionic complexes, enabling niobium, titanium, and iron in the mineral to enter the leaching solution in the form of complexes, while rare earths are retained in the leaching residue in the form of rare earth oxalates. Meanwhile, compared with the process of decomposing niobium minerals with traditional inorganic acids (such as hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid, etc.), this method has low energy consumption, little pollution, and low corrosiveness to equipment during the leaching process. It realizes the efficient and green extraction of valuable metal elements in niobium-containing rough concentrate, optimizes the working environment, and solves the problem of serious pollution in the traditional inorganic acid decomposition process. Therefore, the present invention provides a new green metallurgy technology for developing niobium ore. In addition, this method does not require high-temperature roasting with alkali or acid in the early stage, has a simple process, and low energy consumption.

[0029] (III) Beneficial Effects

[0030] The beneficial effects of the present invention are as follows:

[0031] 1. The present invention uses an oxalic acid solution as the leaching agent, achieving clean and efficient extraction of niobium, titanium, and iron resources from niobium-containing rough concentrate. It can achieve efficient leaching of niobium, titanium, and iron elements. The niobium leaching rate can reach over 95%, the titanium leaching rate reaches over 85%, and the iron leaching rate reaches over 65%. Rare earths are retained in the leaching residue in the form of rare earth oxalates and can be used as raw materials for further rare earth extraction.

[0032] 2. The present invention does not require pretreatment such as roasting. Direct acid leaching of the ore powder with an oxalic acid solution can achieve efficient leaching of niobium, titanium, and iron elements, solving the problems of high temperature, high energy consumption, complex process flow, and high cost caused by multiple high-temperature alkali or salt roasting in the existing process technology.

[0033] 3. Compared with the existing process and patents, the present invention has a short process flow, simple equipment, convenient operation, safety and environmental protection. It effectively avoids the environmental hazards brought by the decomposition of niobium minerals with inorganic acids, especially avoids the serious corrosion of equipment and the surrounding environment by fluorine-containing inorganic acids, has great environmental benefits, and meets the requirements of current green metallurgy for clean production. Description of the Drawings

[0034] Figure 1 It is a process flow diagram for leaching niobium, titanium, and iron from niobium-containing rough concentrate with oxalic acid. Detailed Embodiments

[0035] The following elaborates on the preferred embodiments of the present invention in detail, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making the protection scope of the present invention more clearly defined.

[0036] The method for leaching niobium, titanium, and iron from niobium rough concentrate by oxalic acid proposed in the embodiment of the present invention uses oxalic acid as the leaching agent to leach the ground and dried niobium rough concentrate in oxalic acid, and separates to obtain the leaching solution containing niobium, titanium, and iron and the leaching residue. The method of the present invention has high leaching rates of niobium, titanium, and iron, and the rare earths are retained in the leaching residue in the form of rare earth oxalates, which can be used as raw materials for further extraction of rare earths.

[0037] The niobium rough concentrate containing niobium, titanium, iron, and rare earths used in the embodiment of the present invention is obtained by ore dressing from Bayan Obo ore. The ore dressing method is a common means in the art. The composition of the niobium rough concentrate containing niobium, titanium, iron, and rare earths includes by mass percentage: T.Fe 0 - 50%, Nb 2 O 5 1 - 10%, TiO 2 1 - 15%, REO 1 - 20%, SiO 2 5 - 30%, CaO 2 - 15%, F 2 - 15%.

[0038] The oxalic acid used in the embodiment of the present invention is a commercially available product.

[0039] Example 1

[0040] (1) Using the niobium rough concentrate containing niobium, titanium, iron, and rare earths as raw materials, grind it to a particle size of less than 74 μm with the ore amount not less than 90 wt% of the total ore amount, and dry it at 110 °C.

[0041] (2) Prepare an oxalic acid solution with a concentration of 0.5 mol / L as the leaching agent.

[0042] (3) Take 20 g of the niobium rough concentrate obtained in step (1), add the oxalic acid solution with a concentration of 0.5 mol / L obtained in step (2) according to a liquid-solid ratio of 30 ml / g, heat to 60 °C, stir at a speed of 100 r / min, leach for 8 h. After the leached pulp is filtered and washed with distilled water, a leaching solution containing niobium, titanium, and iron and a leaching residue retaining rare earth elements in the form of rare earth oxalates are obtained. The leaching residue can be used as a raw material for further extraction of rare earths.

[0043] After analysis, the leaching rate of niobium reaches 92.6%, the leaching rate of titanium reaches 83.2%, and the leaching rate of iron reaches 71.5%.

[0044] Example 2

[0045] (1) Using the niobium rough concentrate containing niobium, titanium, iron, and rare earths as raw materials, grind it to a particle size of less than 74 μm with the ore amount not less than 90 wt% of the total ore amount, and dry it at 110 °C.

[0046] (2) Prepare an oxalic acid solution with a concentration of 1 mol / L as the leaching agent.

[0047] (3) Take 20 g of the niobium-containing rough concentrate obtained in step (1), add the oxalic acid solution with a concentration of 1 mol / L obtained in step (2) according to a liquid-solid ratio of 30 ml / g, heat to 80 °C, with a stirring speed of 500 r / min, leach for 6 h. After the leached pulp is filtered and washed with distilled water, a leachate containing niobium, titanium, and iron is obtained, and a leach residue retaining rare earth elements in the form of rare earth oxalates. The leach residue can be used as a raw material for further extraction of rare earths.

[0048] After analysis, the leaching rate of niobium reached 94.3%, the leaching rate of titanium reached 86.4%, and the leaching rate of iron reached 72.3%.

[0049] Example 3

[0050] (1) Using the niobium-containing rough concentrate containing niobium, titanium, iron, and rare earths as raw materials, grind it until the amount of ore with a particle size below 74 μm is not less than 90 wt% of the total ore amount, and dry it at 110 °C.

[0051] (2) Prepare an oxalic acid solution with a concentration of 2 mol / L as the leaching agent.

[0052] (3) Take 20 g of the niobium-containing rough concentrate obtained in step (1), add the oxalic acid solution with a concentration of 2 mol / L obtained in step (2) according to a liquid-solid ratio of 20 ml / g, heat to 95 °C, with a stirring speed of 600 r / min, leach for 4 h. After the leached pulp is filtered and washed with distilled water, a leachate containing niobium, titanium, and iron is obtained, and a leach residue retaining rare earth elements in the form of rare earth oxalates. The leach residue can be used as a raw material for further extraction of rare earths.

[0053] After analysis, the leaching rate of niobium reached 98.8%, the leaching rate of titanium reached 93.4%, and the leaching rate of iron reached 87.4%.

[0054] Example 4

[0055] (1) Using the niobium-containing rough concentrate containing niobium, titanium, iron, and rare earths as raw materials, grind it until the amount of ore with a particle size below 74 μm is not less than 90 wt% of the total ore amount, and dry it at 110 °C.

[0056] (2) Prepare an oxalic acid solution with a concentration of 4 mol / L as the leaching agent.

[0057] (3) Take 20 g of the niobium-containing rough concentrate obtained in step (1), add the oxalic acid solution with a concentration of 4 mol / L obtained in step (2) according to a liquid-solid ratio of 15 ml / g, heat to 95 °C, stir at a speed of 600 r / min, leach for 3 h. After the leached pulp is filtered and washed with distilled water, a leachate containing niobium, titanium, and iron, and a leached residue retaining rare earth elements in the form of rare earth oxalates are obtained. The leached residue can be used as a raw material for further extraction of rare earths.

[0058] After analysis, the leaching rate of niobium reached 97.5%, the leaching rate of titanium reached 92.5%, and the leaching rate of iron reached 86.3%.

[0059] Example 5

[0060] (1) Using the niobium-containing rough concentrate containing niobium, titanium, iron, and rare earths as raw materials, grind it until the amount of ore with a particle size below 74 μm is not less than 90 wt% of the total ore amount, and dry it at 110 °C.

[0061] (2) Prepare an oxalic acid solution with a concentration of 6 mol / L as the leaching agent.

[0062] (3) Take 20 g of the niobium-containing rough concentrate obtained in step (1), add the oxalic acid solution with a concentration of 6 mol / L obtained in step (2) according to a liquid-solid ratio of 10 ml / g, heat to 105 °C, stir at a speed of 1000 r / min, leach for 1 h. After the leached pulp is filtered and washed with distilled water, a leachate containing niobium, titanium, and iron, and a leached residue retaining rare earth elements in the form of rare earth oxalates are obtained. The leached residue can be used as a raw material for further extraction of rare earths.

[0063] After analysis, the leaching rate of niobium reached 95.8%, the leaching rate of titanium reached 87.2%, and the leaching rate of iron reached 81.3%.

[0064] Comparative Example 1

[0065] In this comparative example, tartaric acid was used as the leaching agent, and the other steps were referred to Example 3.

[0066] After analysis, the leaching rate of niobium reached 43.2%, the leaching rate of titanium reached 36.7%, and the leaching rate of iron reached 30.6%.

[0067] Comparative Example 2

[0068] In this comparative example, sulfuric acid was used as the leaching agent, and the other steps were referred to Example 3.

[0069] After analysis, the leaching rate of niobium reached 54.6%, the leaching rate of titanium reached 48.6%, and the leaching rate of iron reached 43.5%.

[0070] Comparative Example 3

[0071] (1) Using niobium-containing crude concentrate containing niobium, titanium, iron, and rare earth as raw materials, roasting at a temperature of 500 °C for 3 h according to the mass ratio of sodium hydroxide to niobium-containing crude concentrate of 1:1.

[0072] (2) Prepare an oxalic acid solution with a concentration of 2 mol / L as the leaching agent.

[0073] (3) Take 20 g of the roasted niobium-containing crude concentrate obtained in step (1), add the 2 mol / L oxalic acid solution obtained in step (2) according to a liquid-solid ratio of 20 mL / g, heat to 95 °C, stir at a speed of 600 r / min, leach for 4 h. After the leached pulp is filtered and washed with distilled water, a leaching solution containing niobium, titanium, and iron is separated.

[0074] After analysis, the leaching rate of niobium reached 81.4%, the leaching rate of titanium reached 73.5%, and the leaching rate of iron reached 65.3%. In Comparative Example 3 above, through high-temperature alkaline roasting pretreatment, it can play the role of activation and decomposition, destroy the structure of the mineral, and is beneficial to the release of valuable components in the mineral during leaching. However, roasting causes problems such as high temperature, high energy consumption, complex process flow, and high cost, and the alkaline substances added during the roasting process will neutralize a large amount of oxalic acid during the acid leaching process, reducing the concentration of the oxalic acid solution, thus affecting the leaching effect. Compared with Comparative Example 3, the present invention directly acid-leaches the ore powder with an oxalic acid solution, and can achieve the efficient leaching of niobium, titanium, and iron elements, having the advantages of simple process flow, low energy consumption, less acid-base consumption, safety and environmental protection, etc.

[0075] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for leaching niobium, titanium, and iron from niobium-containing rough concentrate with oxalic acid, characterized in that, the method includes mixing niobium-containing rough concentrate powder with oxalic acid solution, heating and stirring for leaching; after the leached pulp is subjected to solid-liquid separation treatment, a leaching solution containing niobium, titanium, and iron is obtained; the separation treatment includes filtering and washing the pulp to separate the leaching solution and the leaching residue; the niobium-containing rough concentrate contains niobium element, titanium element, iron element, and rare earth element; The composition of the niobium-containing rough concentrate includes, by mass percentage: T.Fe 0-50%, Nb 2 O 5 1-10%, TiO 2 1-15%, REO 1-20%, SiO 2 5-30%, CaO 2-15%, F 2-15%; the concentration of the oxalic acid solution is 0.5 - 6 mol / L; the liquid-solid ratio of the oxalic acid solution to the niobium-containing rough concentrate is 10 - 30 mL / g; the heating temperature is 60 - 110 °C, the leaching time is 1 - 8 h, and the leaching residue is rare earth retained in the form of rare earth oxalate.

2. The method for leaching niobium, titanium, and iron from niobium-containing rough concentrate with oxalic acid according to claim 1, characterized in that, the niobium-containing rough concentrate is mixed with oxalic acid solution after being ground and dried.

3. The method for leaching niobium, titanium, and iron from niobium-containing rough concentrate with oxalic acid according to claim 2, characterized in that, the amount of the niobium-containing rough concentrate ground to a particle size less than or equal to 74 μm is not less than 90 wt% of the total ore amount.

4. The method for leaching niobium, titanium, and iron from niobium-containing rough concentrate with oxalic acid according to claim 1, characterized in that, the stirring speed is 100 - 1000 r / min.

5. The method for leaching niobium, titanium, and iron from niobium-containing rough concentrate with oxalic acid according to claim 1, characterized in that, the leaching process is carried out under normal pressure.

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