Iron removal method in hydrometallurgy

Abstract

The invention provides an iron removal method in hydrometallurgy, and belongs to the technical field of hydrometallurgy. According to the iron removal method provided by the invention, the precipitant is added in the high-pressure reaction to control the forming speed of the hematite, and a specific washing process is adopted, so that the purity of the hematite slag is favorably improved, and the loss caused by inclusion of rare earth is reduced. New impurities are not introduced in the hematite method iron removal process, the follow-up impurity removal difficulty and cost are reduced, and comprehensive recovery benefits are improved. And meanwhile, iron slag obtained by removing iron through a hematite method is of a crystal structure, and the filtering performance is good. The obtained iron slag is iron oxide red powder, the utilization rate of iron is increased, and economic benefits are increased.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrometallurgy, and particularly to a method for iron removal 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 treating complex minerals with low energy consumption, fine metal separation, and comprehensive resource utilization. This technology takes leaching - purification - precipitation as the core process, and the main processes include: acid / alkali leaching of minerals (to dissolve target metal ions), solution purification (to remove impurity ions), and precipitation extraction of target metal compounds. Among them, the deep removal of impurity iron runs through the key stage of mixed rare earth solution purification, directly affecting the purity of subsequent rare earth products and the process economy.

[0003] In the prior art, the common iron removal methods in the field of hydrometallurgy mainly include neutralization hydrolysis method, jarosite method, goethite method, and hematite method. For rare earth hydrometallurgy, the commonly used industrial iron removal method is the neutralization hydrolysis method, and the industrial applications 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 the radioactive waste slag is the main source of environmental pollution. The jarosite method for iron removal is that at a certain acidity and temperature, after ferric sulfate and alkali metal or ammonium ions react with each other for a certain time, insoluble jarosite - type compounds MeFe(SO 4 ) 2 (OH) 6 are formed, 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 iron removal process by the jarosite method will become new impurities in the rare earth chloride solution, causing great difficulties for subsequent rare earth element separation and the preparation of rare earth oxides. The goethite method requires that the Fe 3+ in the feed liquid to be iron - removed is <1g / L. 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 amount of rare earth losses. The currently reported goethite method in the research reduces Fe 3+ to Fe 2+ , and then uses 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 object of the present invention is to provide a method for iron removal 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] In order to achieve the above object of the invention, the present invention provides the following technical solutions: The present invention provides a method for iron removal in hydrometallurgy, comprising the following steps: Mix the metal chloride material liquid to be treated with a precipitant, conduct a first high-pressure reaction, and after the reaction is completed, perform solid-liquid separation 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 is completed, perform solid-liquid separation 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 hematite slag 3 with hydrochloric acid solution for washing to obtain hematite slag 4 and washing liquid.

[0007] In the present invention, the metal chloride material liquid to be treated refers to a solution or slurry containing metal chlorides formed in the processes of metal smelting, chemical production or resource recovery, which needs to be further separated, purified or regenerated through specific processes. In the present invention, it especially refers to the iron removal treatment.

[0008] 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.

[0009] 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.

[0010] Preferably, the sulfide precipitants include sodium sulfide, hydrogen sulfide or sodium hydrosulfide; The iron vitriol double salt precipitants include jarosite, natrojarosite or ammonium jarosite.

[0011] Preferably, the temperature of the first high-pressure reaction and the second high-pressure reaction are independently selected from 150 - 250 °C; And / or, the pressure of the first high-pressure reaction and the second high-pressure reaction are independently selected from 0 - 5 Mpa; And / or, the time of the first high-pressure reaction and the second high-pressure reaction are independently selected from 1 - 3 h.

[0012] Preferably, the content of ferric ions in the metal chloride material liquid to be treated is below 200 g / L.

[0013] Preferably, the metal chloride material liquid to be treated is a rare earth chloride material liquid to be deironed.

[0014] Preferably, the total content of rare earth oxides in the rare earth chloride material liquid to be deironed is 0 - 500 g / L.

[0015] 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.

[0016] Preferably, the washing liquid also includes being concentrated and then applied to other iron removal methods.

[0017] Advantages of the present invention: 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 of 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

[0018] Figure 1 is the process flow chart of the iron removal process provided by the embodiment of the present invention; Figure 2 is the scanning electron microscope image of the hematite obtained by the present invention; Figure 3 is the XRD (X-ray diffraction) pattern of the hematite obtained by the present invention. Detailed implementation manners

[0019] 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.

[0020] 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 iron ions in the metal chloride material liquid to be treated is below 200 g / L.

[0021] In the present invention, the precipitant is preferably selected from one or more of hydroxide precipitants, sulfide precipitants, complex iron vitriol 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 complex iron vitriol precipitants include jarosite, natrojarosite or ammonium jarosite.

[0022] 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 rare earth oxide content of 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.

[0023] 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.

[0024] Preferably, the washing liquid also includes being concentrated and then participating in other iron removal methods, and more preferably, after concentration, it is mixed with other rare earth chloride material liquids to be de-ironed.

[0025] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0026] Example 1 The Fe in the material liquid used in this example 3+ is 40 g / L, REO is 300 g / L, the precipitant used is ammonia water, and the theoretical amount (0.53 mol NH 4The precipitant (NH₃OH) and the rare earth chloride solution to be de-ironed are added into a pressure 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 adding the precipitant NH₃OH, and its essence is to provide OH⁻ by the precipitant to consume the H⁺ generated when Fe³⁺ hydrolyzes to Fe(OH)₃, so that it is controlled between 0 and 3. After the reaction, it is cooled 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 precipitant (measuring the content of Fe³⁺ in solution 1, the amount of precipitant NH₃OH is 3 times the amount of Fe³⁺ ions, in molar measurement) 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 is cooled 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, and the washing temperature is 60 °C. After washing, solid-liquid separation is carried out to obtain hematite slag 4 and 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 4 OH⁻ to consume the H⁺ generated when Fe³⁺ hydrolyzes to Fe(OH)₃ - ³⁺ 3+ ³⁺ 2 ₃ 3 ⁺ + ⁺, so that it is controlled between 0 and 3. After the reaction, it is cooled 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 precipitant (measuring the content of Fe³⁺ in solution 1, the amount of precipitant NH₃OH is 3 times the amount of Fe³⁺ ions, in molar measurement) 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 is cooled 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, and the washing temperature is 60 °C. After washing, solid-liquid separation is carried out to obtain hematite slag 4 and 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 3+ ³⁺ 4 ₃ 3+ ³⁺ Example 2 In the solution used in this example, Fe³⁺ is 60 g / L and REO is 200 g / L. The precipitant used is cerium hydroxide, and 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 pressure reactor, and the reaction is carried out under the conditions of 220 °C, 2 h, and 1.4 MPa. After the reaction, it is cooled 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 precipitant (measuring the content of Fe³⁺ in solution 1, the amount of precipitant Ce(OH)₃ is 1 times the amount of Fe³⁺ ions, in molar measurement) 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 is cooled 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, and the washing temperature is 70 °C. After washing, solid-liquid separation is carried out to obtain hematite slag 4 and 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 3+ ³⁺ 3 ₃ 3+ ³⁺ 3 ₃ 3+ ³⁺ Example 3 The Fe content in the feed liquid used in this embodiment 3+ is 80 g / L, and the REO is 200 g / L. The precipitant used is lanthanum hydroxide. The theoretical amount (0.36 mol La(OH) 3 ) of the precipitant and the rare earth chloride feed liquid to be de-ironed are added into a pressurized reactor together, and the reaction is carried out under the conditions of 210 °C, 1.5 h, and 1.3 MPa. After the reaction is completed, it returns to room temperature for solid-liquid separation to obtain hematite slag 1 and de-ironed feed liquid 1; the de-ironed feed liquid 1 and the theoretical amount of precipitant (measure the Fe 3+ content in the feed liquid 1, and the amount of the precipitant La(OH) 3 ) is 1 times the amount of Fe 3+ ions, measured in moles) are added into a high-pressure reactor together, and the reaction is carried out under the conditions of 210 °C, 1.5 h, and 1.3 MPa. After the reaction is completed, it returns to room temperature for solid-liquid separation to obtain hematite slag 2 and de-ironed feed liquid 2; hematite slag 1 and hematite slag 2 are combined to obtain hematite slag 3. 0.15 mol / L hydrochloric acid is used to wash the hematite slag 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, and the washing temperature is 70 °C. After the washing is completed, 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 feed liquid to be de-ironed. The de-ironing results are shown in Table 1: Table 1 Parameter settings and results of the embodiment

[0027] As can be seen from Table 1, through the de-ironing method of the present invention, a de-ironing rate of more than 95% can be obtained, and the loss rate of rare earth is less than 1.7%. Therefore, the present invention has the characteristics of high de-ironing rate and low rare earth loss rate.

[0028] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for removing iron in hydrometallurgy, characterized in that: The following steps are involved: The metal chloride material liquid to be treated is mixed with a precipitant, and a first high-pressure reaction is carried out. After the reaction is completed, the solid and liquid are separated to obtain a deironed material liquid 1 and a hematite slag 1; The deironed liquid 1 is mixed with a precipitant, and subjected to a second high-pressure reaction. After the reaction is completed, the solid and liquid are separated to obtain the deironed liquid 2 and the hematite slag 2; Combining the hematite slag 1 and the hematite slag 2 to obtain hematite slag 3; The hematite slag 3 is mixed with a hydrochloric acid solution for washing to obtain hematite slag 4 and a washing solution.

2. The iron removal method according to claim 1, characterized in that: The precipitant is selected from one or more of hydroxide precipitants, sulfide precipitants, iron alum double salt precipitants, ammonia water, urea, ammonium bicarbonate or active magnesium oxide.

3. The iron removal method according to claim 2, characterized in that: The hydroxide precipitant includes buffered hydroxides and rare earth hydroxides. The buffered hydroxide includes aluminum hydroxide, magnesium hydroxide, zinc hydroxide or calcium hydroxide; the rare earth hydroxide includes cerium hydroxide, lanthanum hydroxide, praseodymium hydroxide, neodymium hydroxide, samarium hydroxide, lanthanum cerium hydroxide, cerium praseodymium hydroxide or cerium neodymium hydroxide.

4. The iron removal method according to claim 2, characterized in that: The sulfide precipitant includes sodium sulfide, hydrogen sulfide or sodium hydrosulfide; The ferroaluminate double salt precipitant includes yellow jarosite, yellow sodium jarosite or yellow ammonium jarosite.

5. The iron removal method according to claim 1, characterized in that: The temperature of the first high pressure reaction and the second high pressure reaction are independently selected from 150 to 250° C.; And / or, the pressure of the first high pressure reaction and the second high pressure reaction are independently selected from 0 to 5 MPa; And / or, the time of the first high pressure reaction and the second high pressure reaction is independently selected from 1 to 3 hours.

6. The iron removal method according to claim 1, characterized in that: The content of trivalent iron ions in the metal chloride liquid to be treated is below 200 g / L.

7. The iron removal method according to any one of claims 1 to 6, characterized in that: The metal chloride material liquid to be treated is a rare earth chloride material liquid to be de-ironized.

8. The iron removal method according to claim 7, characterized in that: The total rare earth oxide content of the rare earth chloride solution to be deironized is 0-500 g / L.

9. The iron removal method according to claim 1, characterized in that: The equipment used for the washing is a Venturi microreactor; And / or, the washing temperature is 40-80°C; And / or, the washing time is 0.5~2h.

10. The iron removal method according to claim 1, characterized in that: The washing liquid can also be used in other iron removal methods after being concentrated.

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