A method for removing iron in hydrometallurgy

Abstract

The present invention provides a method for iron removal in hydrometallurgy, belonging to the technical field of hydrometallurgy. The iron removal method provided by the present invention controls the formation rate of hematite by adding a precipitant in a high-pressure reaction and adopts a specific washing process, which is beneficial to improving the purity of hematite slag and reducing the loss of rare earth caused by inclusion. No new impurities are introduced during the iron removal process using the hematite method in the present invention, reducing the subsequent impurity removal difficulty and cost and improving the comprehensive recovery benefit. At the same time, the iron slag obtained by iron removal using the hematite method has a crystal structure and good filtration performance. The obtained iron slag is iron red powder, improving the utilization rate of iron and increasing economic benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrometallurgy, and particularly relates to a method for removing iron in hydrometallurgy. Background Art

[0002] Hydrometallurgy is an important metallurgical process system for metal extraction and separation through an aqueous solution medium. Compared with traditional pyrometallurgy, it has unique advantages in the treatment of complex minerals with low energy consumption, refined metal separation, and comprehensive utilization of resources. The core process of this technology is leaching-purification-precipitation, and the main processes include: acid / alkali leaching of minerals (dissolving target metal ions), solution purification (removing impurity ions), and precipitation extraction of target metal compounds. Among them, the deep removal of impurity iron runs through the key stage of the purification of mixed rare earth solutions, directly affecting the purity of subsequent rare earth products and the process economy.

[0003] In the prior art, the common methods for removing iron in the field of hydrometallurgy mainly include neutralization hydrolysis method, jarosite method, goethite method, and hematite method. The industrial common method for removing iron in rare earth hydrometallurgy is the neutralization hydrolysis method, and the industrial application and research of the jarosite method, goethite method, and hematite method are very few.

[0004] Among the above methods, the iron slag obtained by the neutralization hydrolysis method contains a large amount of rare earth elements and radioactive thorium elements, which not only causes serious rare earth losses, but also radioactive waste slag is the main source of environmental pollution. The jarosite method for iron removal is that at a certain acidity and temperature, ferric sulfate and alkali metal or ammonium ions react with each other for a certain time to form insoluble jarosite compounds MeFe(SO4)2(OH)6, where Me represents a monovalent ion, such as K + 、Na + 、NH 4+ etc. It can be seen from the chemical formula that the cations introduced in the process of iron removal by the jarosite method will become new impurities in the rare earth chloride solution, causing great difficulties to the subsequent separation of rare earth elements and the preparation of rare earth oxides. The goethite method requires that the Fe 3+ <1g / L in the feed liquid to be de-ironed. In the case of greater than 1g / L, the obtained iron slag will be mixed with a large amount of rare earth elements, resulting in a large loss of rare earth. The goethite method reported in current research uses reducing Fe 3+ to Fe 2+ , and then using an oxidant to control the Fe 3+ concentration in the feed liquid to achieve the purpose of iron removal by the goethite method. This not only increases the process cost but also increases the process difficulty, which is neither economical nor practical. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for removing iron in hydrometallurgy, which has the advantages of high iron removal rate, low loss rate of metal elements, and no introduction of other new impurities.

[0006] To achieve the above-mentioned invention object, the present invention provides the following technical solutions:

[0007] The present invention provides a method for iron removal in hydrometallurgy, comprising the following steps:

[0008] Mix the metal chloride material liquid to be treated with a precipitant, conduct a first high-pressure reaction, and after the reaction ends, perform solid-liquid separation to obtain the iron-removed material liquid 1 and hematite slag 1;

[0009] Mix the iron-removed material liquid 1 with a precipitant, conduct a second high-pressure reaction, and after the reaction ends, perform solid-liquid separation to obtain the iron-removed material liquid 2 and hematite slag 2;

[0010] Combine the hematite slag 1 and hematite slag 2 to obtain hematite slag 3;

[0011] Mix the hematite slag 3 with a hydrochloric acid solution for washing to obtain hematite slag 4 and washing liquid.

[0012] In the present invention, the metal chloride material liquid to be treated refers to a solution or slurry containing metal chlorides formed during metal smelting, chemical production or resource recovery processes, which needs to be further separated, purified or regenerated through specific processes. In the present invention, it especially refers to iron removal treatment.

[0013] Preferably, the precipitant is selected from one or more of hydroxide precipitants, sulfide precipitants, iron vitriol double salt precipitants, ammonia water, urea, ammonium bicarbonate or active magnesium oxide.

[0014] Preferably, the hydroxide precipitants include buffer-type hydroxides and rare earth hydroxides. The buffer-type hydroxides include aluminum hydroxide, magnesium hydroxide, zinc hydroxide or calcium hydroxide; the rare earth hydroxides include cerium hydroxide, lanthanum hydroxide, praseodymium hydroxide, neodymium hydroxide, samarium hydroxide, lanthanum cerium hydroxide, cerium praseodymium hydroxide or cerium neodymium hydroxide.

[0015] Preferably, the sulfide precipitants include sodium sulfide, hydrogen sulfide or sodium hydrosulfide;

[0016] The iron vitriol double salt precipitants include jarosite, natrojarosite or ammonium jarosite.

[0017] Preferably, the temperatures of the first high-pressure reaction and the second high-pressure reaction are independently selected from 150 - 250 °C;

[0018] And / or, the pressures of the first high-pressure reaction and the second high-pressure reaction are independently selected from 0 - 5 Mpa;

[0019] And / or, the reaction times of the first high-pressure reaction and the second high-pressure reaction are independently selected from 1 - 3 h.

[0020] Preferably, the content of ferric ions in the metal chloride material liquid to be treated is below 200 g / L.

[0021] Preferably, the metal chloride material liquid to be treated is a rare earth chloride material liquid to be de-ironed.

[0022] Preferably, the total content of rare earth oxides in the rare earth chloride material liquid to be de-ironed is 0 - 500 g / L.

[0023] Preferably, the equipment used for the washing is a Venturi micro-reactor;

[0024] and / or, the temperature of the washing is 40 - 80 °C;

[0025] and / or, the time of the washing is 0.5 - 2 h.

[0026] Preferably, the washing liquid further includes being concentrated and then applied to other iron removal methods.

[0027] Advantages of the present invention:

[0028] The iron removal method provided by the present invention controls the formation rate of hematite by adding a precipitant in a high-pressure reaction and adopts a specific washing process, which is beneficial to improving the purity of the hematite slag and reducing the loss of rare earth caused by inclusion. No new impurities are introduced during the iron removal process using the hematite method in the present invention, reducing the subsequent impurity removal difficulty and cost and improving the comprehensive recovery efficiency. At the same time, the iron slag obtained by the iron removal using the hematite method has a crystal structure and good filtration performance. The obtained iron slag is iron red powder, improving the utilization rate of iron and increasing economic benefits. Description of the Drawings

[0029] Figure 1 is the process flow chart of the iron removal process provided by the embodiment of the present invention;

[0030] Figure 2 is the scanning electron microscope image of the hematite obtained by the present invention;

[0031] Figure 3 is the XRD (X-ray diffraction) pattern of the hematite obtained by the present invention. Detailed Embodiments

[0032] The present invention provides an iron removal method in hydrometallurgy, including the following steps: mixing the metal chloride material liquid to be treated with a precipitant, performing a first high-pressure reaction, separating the solid and liquid after the reaction ends to obtain the iron-removed material liquid 1 and hematite slag 1; mixing the iron-removed material liquid 1 with a precipitant, performing a second high-pressure reaction, separating the solid and liquid after the reaction ends to obtain the iron-removed material liquid 2 and hematite slag 2; combining the hematite slag 1 and hematite slag 2 to obtain hematite slag 3; mixing the hematite slag 3 with a hydrochloric acid solution for washing to obtain hematite slag 4 and a washing liquid.

[0033] In the present invention, the metal chloride material liquid to be treated refers to a solution or slurry containing metal chlorides formed during metal smelting, chemical production or resource recovery processes, which needs to be further separated, purified or regenerated through specific processes. In the present invention, it especially refers to the iron removal treatment; preferably, the content of ferric ions in the metal chloride material liquid to be treated is below 200 g / L.

[0034] In the present invention, the precipitant is preferably selected from one or more of hydroxide precipitants, sulfide precipitants, iron alum double salt precipitants, ammonia water, urea, ammonium bicarbonate or active magnesium oxide. Preferably, the hydroxide precipitants include buffer hydroxides and rare earth hydroxides. The buffer hydroxides include aluminum hydroxide, magnesium hydroxide, zinc hydroxide or calcium hydroxide; the rare earth hydroxides include cerium hydroxide, lanthanum hydroxide, praseodymium hydroxide, neodymium hydroxide, samarium hydroxide, lanthanum cerium hydroxide, cerium praseodymium hydroxide or cerium neodymium hydroxide. Preferably, the sulfide precipitants include sodium sulfide, hydrogen sulfide or sodium hydrosulfide; the iron alum double salt precipitants include jarosite, natrojarosite or ammonium jarosite.

[0035] In the present invention, more preferably, the metal chloride material liquid to be treated is a rare earth chloride material liquid to be de-ironed, and the total content of rare earth oxides in the rare earth chloride material liquid to be de-ironed is 0 - 500 g / L. At this time, the precipitant is selected from rare earth hydroxides or ammonia water, etc.

[0036] In the present invention, preferably, the temperatures of the first high-pressure reaction and the second high-pressure reaction are independently selected from 150 - 250 °C; the pressures of the first high-pressure reaction and the second high-pressure reaction are independently selected from 0 - 5 Mpa; the times of the first high-pressure reaction and the second high-pressure reaction are independently selected from 1 - 3 h. Preferably, the equipment used for washing is a Venturi microreactor; and / or, the temperature of the washing is 40 - 80 °C; and / or, the time of the washing is 0.5 - 2 h.

[0037] Preferably, the washing liquid also includes being concentrated and then applied to other iron removal methods, and more preferably, after concentration, it is mixed with other rare earth chloride material liquids to be de-ironed.

[0038] The technical solutions provided by the present invention will be described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0039] Example 1

[0040] The Fe in the material liquid used in this example 3+The concentration of Fe is 40 g / L, the concentration of REO is 300 g / L, and the precipitant used is ammonia water. The theoretical amount (0.53 mol NH4OH) of the precipitant and the rare earth chloride solution to be de-ironed are added into a pressurized reactor, and the reaction is carried out under the conditions of 200 °C, 2 h, and 1.2 MPa. The pH during the reaction process is adjusted by the added precipitant NH4OH, and its essence is to provide OH by the precipitant - to consume Fe 3+ generated when Fe hydrolyzes to Fe2O3 + , and it is controlled between 0 and 3. After the reaction, it returns to room temperature, and solid-liquid separation is carried out to obtain hematite slag 1 and de-ironed solution 1; the de-ironed solution 1 and the theoretical amount of the precipitant (measure the content of Fe in solution 1 3+ , and the amount of the precipitant NH4OH is 3 times the amount of Fe 3+ ions, measured in moles) are added into a high-pressure reactor, and the reaction is carried out under the conditions of 200 °C, 2 h, and 1.2 MPa. After the reaction, it returns to room temperature, and solid-liquid separation is carried out to obtain hematite slag 2 and de-ironed solution 2; hematite slag 1 and hematite slag 2 are combined to obtain hematite slag 3. 0.1 mol / L hydrochloric acid and hematite slag are used for washing with a liquid-solid ratio of 1:1, and a Venturi micro-reactor is used as the washing equipment. The washing time is 0.5 h, the washing temperature is 60 °C. After washing, solid-liquid separation is carried out to obtain hematite slag 4 and the washing solution. The washing solution is concentrated and returned to the rare earth chloride solution to be de-ironed. The de-ironing results are shown in Table 1

[0041] Example 2

[0042] In the solution used in this example, the concentration of Fe 3+ is 60 g / L, the concentration of REO is 200 g / L, and the precipitant used is cerium hydroxide. The theoretical amount (0.27 mol Ce(OH)3) of the precipitant and the rare earth chloride solution to be de-ironed are added into a pressurized reactor, and the reaction is carried out under the conditions of 220 °C, 2 h, and 1.4 MPa. After the reaction, it returns to room temperature, and solid-liquid separation is carried out to obtain hematite slag 1 and de-ironed solution 1; the de-ironed solution 1 and the theoretical amount of the precipitant (measure the content of Fe in solution 1 3+ , and the amount of the precipitant Ce(OH)3) is 1 times the amount of Fe 3+ ions, measured in moles) are added into a high-pressure reactor, and the reaction is carried out under the conditions of 220 °C, 2 h, and 1.4 MPa. After the reaction, it returns to room temperature, and solid-liquid separation is carried out to obtain hematite slag 2 and de-ironed solution 2; hematite slag 1 and hematite slag 2 are combined to obtain hematite slag 3. 0.2 mol / L hydrochloric acid and hematite slag are used for washing with a liquid-solid ratio of 1:1, and a Venturi micro-reactor is used as the washing equipment. The washing time is 1 h, the washing temperature is 70 °C. After washing, solid-liquid separation is carried out to obtain hematite slag 4 and the washing solution. The washing solution is concentrated and returned to the rare earth chloride solution to be de-ironed. The de-ironing results are shown in Table 1

[0043] Example 3

[0044] The Fe in the feed solution used in this example 3+ The content of precipitant was 80 g / L, the content of REO was 200 g / L, the precipitant was lanthanum hydroxide, and the theoretical amount (0.36 mol La(OH)3) of precipitant and the rare earth chloride feed liquid to be deironed were added into a pressure reactor, and reacted at 210°C, 1.5 h, and 1.3 MPa. After the reaction, the mixture was returned to room temperature for solid-liquid separation to obtain hematite slag 1 and deironed feed liquid 1. The deironed feed liquid 1 was mixed with the theoretical amount of precipitant (the content of Fe in feed liquid 1 was measured). 3+ The content of the precipitant La (OH)3) is 1 times that of Fe 3+ ions, measured in moles) were added to a high-pressure reactor, reacted at 210°C, 1.5h, 1.3MPa, and returned to room temperature for solid-liquid separation to obtain hematite slag 2 and deironing feed 2; hematite slag 1 and hematite slag 2 were combined to obtain hematite slag 3, and 0.15 mol / L hydrochloric acid was used to wash the hematite slag at a liquid-solid ratio of 1:1 using a Venturi microreactor as a washing device. The washing time was 1 h and the washing temperature was 70°C. After the washing, solid-liquid separation was obtained to obtain hematite slag 4 and washing liquid, and the washing liquid was concentrated and returned to the deironing rare earth chloride feed liquid. The deironing results are shown in Table 1:

[0045] Table 1 Parameter settings and results of the embodiment

[0046]

[0047] As can be seen from Table 1, the iron removal method of the present invention can achieve an iron removal rate of more than 95%, while the loss rate of rare earth is less than 1.7%. Therefore, the present invention has the characteristics of high iron removal rate and low rare earth loss rate.

[0048] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for removing iron in hydrometallurgy, characterized in that, It includes the following steps: Mix the metal chloride material liquid to be processed with a precipitant, conduct a first high-pressure reaction, and after the reaction ends, separate the solid and liquid to obtain the iron-removed material liquid 1 and hematite slag 1; Mix the iron-removed material liquid 1 with a precipitant, conduct a second high-pressure reaction, and after the reaction ends, separate the solid and liquid to obtain the iron-removed material liquid 2 and hematite slag 2; Combine the hematite slag 1 and hematite slag 2 to obtain hematite slag 3; Mix the hematite slag 3 with a hydrochloric acid solution for washing to obtain hematite slag 4 and washing solution; The precipitant is selected from one or more of hydroxide precipitants, sulfide precipitants, complex iron vitriol precipitants, ammonia water, urea, ammonium bicarbonate or active magnesium oxide; The sulfide precipitants include sodium sulfide, hydrogen sulfide or sodium bisulfide; The complex iron vitriol precipitants include jarosite, natrojarosite or ammonium jarosite; The temperatures of the first high-pressure reaction and the second high-pressure reaction are independently selected from 150 to 250 °C; The pressures of the first high-pressure reaction and the second high-pressure reaction are independently selected from 1.2 to 5 Mpa; The reaction times of the first high-pressure reaction and the second high-pressure reaction are independently selected from 1 to 3 h.

2. The iron removal method according to claim 1, wherein The hydroxide precipitants include buffer-type hydroxides and rare earth hydroxides. The buffer-type hydroxides include aluminum hydroxide, magnesium hydroxide, zinc hydroxide or calcium hydroxide; the rare earth hydroxides include cerium hydroxide, lanthanum hydroxide, praseodymium hydroxide, neodymium hydroxide, samarium hydroxide, lanthanum cerium hydroxide, cerium praseodymium hydroxide or cerium neodymium hydroxide.

3. The iron removal method according to claim 1, characterized in that, The content of ferric iron ions in the metal chloride material liquid to be processed is below 200 g / L.

4. The iron removal method according to any one of claims 1 to 3, characterized in that, The metal chloride material liquid to be processed is a rare earth chloride material liquid to be iron-removed.

5. The iron removal method according to claim 1, characterized in that, The equipment used for the washing is a Venturi microreactor; The temperature of the washing is 40 to 80 °C; The time of the washing is 0.5 to 2 h.

6. The iron removal method according to claim 1, characterized in that, The washing solution also includes being concentrated and then participating in other iron-removing methods for application.

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