Method for metallurgical iron removal by utilizing Venturi reactor

Abstract

The invention provides a method for metallurgical iron removal by using a Venturi reactor, and belongs to the technical field of hydrometallurgy. According to the method for metallurgical iron removal by using the Venturi reactor, the speed of conversion from Fe < 2 + > to Fe < 3 + > can be increased in the oxidation, precipitation and washing processes, the energy required by formation and growth of goethite crystal nucleuses is reduced, and the washing effect of non-iron ions in the goethite slag is enhanced. Therefore, the method provided by the invention not only is favorable for improving the purity of goethite, but also can reduce the loss caused by inclusion of rare earth. New impurities are not introduced in the iron removal process of the goethite method, the follow-up impurity removal difficulty and cost are reduced, the comprehensive recovery efficiency is improved, meanwhile, a reaction device needed by the goethite method is simple, reaction conditions are mild, and industrial application is easy to achieve.

Description

Technical Field

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

[0002] Common iron removal methods in the field of hydrometallurgy involve neutralization hydrolysis method, jarosite process, goethite process, and hematite process. In the current field of rare earth metallurgy, the efficient separation of rare earth elements and iron elements in rare earth liquor is an urgent problem to be solved in current industrial production and also a current research hotspot.

[0003] For the separation of rare earth and iron, the commonly used industrial method is the neutralization hydrolysis method (magnesium oxide is commonly used as a precipitant in the sulfuric acid system, and ammonium bicarbonate is commonly used as a precipitant in the hydrochloric acid system) to remove iron impurities in rare earth liquor. The commonly used iron removal methods in hydrometallurgy include: jarosite process, goethite process, and hematite process, etc. In the jarosite process, ferric ions in the sulfuric acid system are removed in the form of MeFe 3 (SO 4 ) 2 (OH) 6 , where Me represents a monovalent ion, such as K + , Na + , NH 4+ , etc. In the goethite process, ferric ions in the reaction liquor are removed in the form of FeOOH, and in the hematite process, ferric ions in the reaction liquor are removed in the form of Fe 2 O 3 . It is not difficult to see from the chemical formula that the jarosite process is suitable for the sulfate system, while the goethite process and the hematite process are not restricted by the solution system. However, the reaction of the hematite process requires the support of a high-temperature and high-pressure environment to dehydrate the generated Fe(OH) 3 to generate Fe 2 O 3 . Therefore, the hematite process not only has strict requirements for reaction equipment but also requires high temperature and high pressure, and is an iron removal method with high safety and cost. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for removing iron in metallurgy by using a Venturi reactor, which not only helps to improve the purity of goethite but also can reduce the loss of rare earth caused by inclusion.

[0005] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions: The present invention provides a method for removing iron in metallurgy by using a Venturi reactor, comprising the following steps: Mixing the metal chloride material liquor to be treated with an oxidant, flowing through a Venturi reactor, and performing an oxidation reaction to obtain an oxidized liquor; Mix the oxidized feed liquid with a precipitant, flow it through a Venturi reactor for precipitation reaction, and filter after the reaction to obtain goethite slag 1 and the iron-removed feed liquid; Mix goethite slag 1 with hydrochloric acid solution for washing to obtain goethite slag 2 and a filtrate.

[0006] Preferably, in the oxidation reaction, ferrous ions in the metal chloride feed liquid to be treated are completely oxidized to ferric ions.

[0007] Preferably, the oxidant is selected from one or more of oxygen, ozone or hydrogen peroxide.

[0008] Preferably, the precipitant is selected from one or more of hydroxide precipitants, sulfide precipitants, complex iron vitriol precipitants, ammonia water, urea, ammonium bicarbonate or activated 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; The sulfide precipitants include sodium sulfide, hydrogen sulfide or sodium bisulfide; The complex iron vitriol precipitants include jarosite, natrojarosite or ammonium jarosite.

[0010] Preferably, the molar ratio of the oxidant to ferrous ions in the metal chloride feed liquid to be treated is 2.5 - 4:1.

[0011] Preferably, the molar ratio of the precipitant to ferric ions in the oxidized feed liquid is 3 - 3.6:1.

[0012] Preferably, the temperature of the precipitation reaction is 70 - 90 °C and the time is 0.5 - 1.5 h.

[0013] Preferably, the pH of the hydrochloric acid solution is 3.5 - 4.5; and / or, the liquid-solid ratio of the mixture of goethite slag 1 and hydrochloric acid solution is 1 - 3:1; and / or, the temperature of the washing is 40 - 80 °C; and / or, the time of the washing is 0.5 - 2 h.

[0014] Preferably, the metal chloride feed liquid to be treated is a rare earth chloride feed liquid to be de-ironed.

[0015] Advantages of the present invention: The method for removing iron in metallurgy using a Venturi reactor provided by the present invention can utilize the changes in fluid velocity and pressure, as well as the turbulent kinetic energy and cavitation generated during the reaction, during the processes of oxidation, precipitation, and washing, to increase Fe 2+ to Fe 3+ conversion rate, and reduce the energy required for the formation and growth of goethite crystal nuclei, enhancing the washing effect of non-iron ions in the goethite slag. Therefore, the method provided by the present invention not only helps to improve the purity of goethite, but also can reduce the loss of rare earths caused by inclusion. In the iron removal process using the goethite method adopted by the present invention, no new impurities are introduced, reducing the subsequent impurity removal difficulty and cost, improving the comprehensive recovery efficiency. At the same time, the reaction device required by the goethite method proposed by the present invention is simple, the reaction conditions are mild, and it is easy to realize industrial application. Description of the Drawings

[0016] Figure 1 is a process flow chart; Figure 2 is a schematic diagram of the reaction device; Figure 3 is a scanning electron microscope image of goethite; Figure 4 is an XRD (X-ray diffraction) pattern of goethite. Detailed Embodiments

[0017] The present invention provides a method for removing iron in metallurgy using a Venturi reactor, which includes the following steps: Mix the metal chloride material liquid to be treated with an oxidant, and flow it through the Venturi reactor to carry out an oxidation reaction to obtain an oxidized material liquid; Mix the oxidized material liquid with a precipitant, and flow it through the Venturi reactor to carry out a precipitation reaction. After the reaction ends, filter to obtain goethite slag 1 and an iron-removed material liquid; Mix goethite slag 1 with hydrochloric acid solution for washing to obtain goethite slag 2 and a filtrate.

[0018] In the present invention, preferably, the oxidation reaction completely oxidizes the divalent iron ions in the metal chloride material liquid to be treated into trivalent iron ions. Preferably, the oxidant is selected from one or more of oxygen, ozone, or hydrogen peroxide. Preferably, the molar ratio of the oxidant to the divalent iron ions in the metal chloride material liquid to be treated is 2.5 - 4:4.

[0019] In the present invention, the oxidation reaction equation of the divalent iron ions is as follows: (1) (2) (3) Among them, the dosage of the oxidant is 2.5 to 4 times the theoretical equivalent of the reaction equation. For example, as shown in reaction equation (1), taking the oxidant oxygen as an example, 4 mol of divalent iron ions require 1 mol of oxygen in terms of theoretical equivalent, and 2.5 to 4 times the theoretical equivalent is required, that is, 2.5 mol to 4 mol of oxygen.

[0020] In the present invention, preferably, the precipitant is selected from one or more of hydroxide precipitants, sulfide precipitants, ferric alum double salt precipitants, ammonia water, urea, ammonium bicarbonate or activated magnesium oxide. Preferably, the hydroxide precipitants include buffer hydroxides and rare earth hydroxides, and 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; the sulfide precipitants include sodium sulfide, hydrogen sulfide or sodium hydrosulfide; the ferric alum double salt precipitants include jarosite, natrojarosite or ammonium jarosite. Preferably, the molar ratio of the precipitant to ferric iron ions in the oxidized feed liquid is 3 to 3.6:1. Preferably, the temperature of the precipitation reaction is 70 to 90 °C, and the time is 0.5 to 1.5 h.

[0021] The reaction chemical formula of the precipitant and ferric iron ions in the rare earth chloride feed liquid is as follows: (4) (5) (6) The dosage of the precipitant is 1.0 to 1.2 times the theoretical equivalent of the chemical reaction formula. As shown in chemical reaction equations (4) to (6), taking the precipitant ammonia water as an example, 1 mol of ammonium bicarbonate decomposes into 1 mol of ammonia water, and 1 mol of ferric iron ions requires 3 mol of ammonia water. Therefore, the amount of ammonia water required for 1 mol of ferric iron ions is 1.0 to 1.2 times the theoretical equivalent, that is, 3 mol to 3.6 mol of ammonia water.

[0022] In the present invention, preferably, the pH of the hydrochloric acid solution is 3.5 to 4.5; and / or, the liquid-solid ratio of the goethite slag 1 mixed with the hydrochloric acid solution is 1 to 3:1; and / or, the temperature of the washing is 40 to 80 °C; and / or, the time of the washing is 0.5 to 2 h. Preferably, the metal chloride feed liquid to be treated is the rare earth chloride feed liquid to be de-ironed.

[0023] 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.

[0024] Example 1 In this example, the TFe in the raw materials used is 40 g / L (where Fe 2+ is 28 g / L), the REO is 300 g / L, the oxidant used is oxygen, and its dosage is 2.5 - 4.0 times the theoretical amount (0.15 mol). The precipitant used is ammonia water, and its dosage is 1.0 - 1.2 times the theoretical amount (0.64 mol of NH 4 OH). First, the rare earth chloride solution to be oxidized and oxygen are passed through a Venturi reactor in parallel. The reaction conditions are 40 °C, 2 h, and the acidity value of the rare earth chloride solution to be oxidized is pH = 2. After the oxidation reaction is completed, the oxidized rare earth chloride solution and ammonia water are passed through a Venturi reactor in parallel. The reaction conditions are that the precipitation reaction temperature is 85 °C, the reaction time is 1 h. After the precipitation reaction is completed, solid-liquid separation is carried out. The filter residue obtained from the solid-liquid separation is mixed with a hydrochloric acid solution with pH = 4 and passed through a Venturi reactor. The reaction conditions are that the washing temperature is 60 °C, the washing time is 1 h, and the liquid-solid ratio is 1:1. After washing, solid-liquid separation is carried out to obtain goethite slag and washing liquid. The washing liquid is concentrated and returned to the rare earth chloride solution to be de-ironed. The de-ironing results are shown in Table 1.

[0025] Example 2 In this example, the TFe in the raw materials used is 50 g / L (where Fe 2+ is 28 g / L), the REO is 200 g / L, the oxidant used is ozone, and its dosage is 2.5 - 4.0 times the theoretical amount (0.1 mol of ozone), and the washing liquid is a hydrochloric acid solution with pH = 4.5. The precipitant used is ammonium bicarbonate, and its dosage is 1.0 - 1.2 times the theoretical amount (0.96 mol of NH 4 HCO 3 ). The oxidation reaction temperature is 50 °C, the oxidation time is 3.5 h, the acidity value of the rare earth chloride solution to be oxidized is pH = 1.5, the precipitation reaction temperature is 90 °C, the reaction time is 0.5 h, the washing temperature is 70 °C, the washing time is 1 h, and the liquid-solid ratio is 1:1. The entire processes of oxidation, precipitation, and washing are the same as those in Example 1. After washing, solid-liquid separation is carried out to obtain goethite slag and washing liquid. The washing liquid is concentrated and returned to the rare earth chloride solution to be de-ironed. The de-ironing results are shown in Table 1.

[0026] Example 3 In this example, the TFe in the raw materials used is 70 g / L (where Fe 2+ is 28 g / L), the REO is 250 g / L, the oxidant used is hydrogen peroxide, and its dosage is 2.5 - 4.0 times the theoretical amount (0.3 mol of H 2 O 2 ), and the washing liquid is a hydrochloric acid solution with pH = 3.5. The precipitant used is ammonia water, and its dosage is 1.0 - 1.2 times the theoretical amount (1.35 mol of NH4 OH). The oxidation reaction temperature is 35 °C, the oxidation time is 5 h, the acidity value of the rare earth chloride solution to be oxidized is pH = 2.0, the precipitation reaction temperature is 80 °C, the reaction time is 1.5 h, the washing temperature is 55 °C, the washing time is 1.5 h, and the liquid-solid ratio is 2:1. After washing, solid-liquid separation is carried out to obtain goethite slag and washing liquid. The washing liquid is concentrated and then returned to the rare earth chloride solution to be de-ironed. The de-ironing results are shown in Table 1.

[0027] Table 1 Parameter settings and results of the examples

[0028] As can be seen from Table 1, through the de-ironing method of the present invention, a de-ironing rate of more than 97% can be obtained, and the loss rate of rare earth is less than 1.6%. Therefore, the present invention has the characteristics of high de-ironing rate and low rare earth loss rate.

[0029] The above is only the preferred embodiment 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 metallurgical iron removal using a Venturi reactor, characterized in that: The following steps are involved: The metal chloride material liquid to be treated is mixed with an oxidant, and the mixture is passed through a venturi reactor to undergo an oxidation reaction to obtain an oxidized material liquid; The oxidized feed liquid is mixed with a precipitant, and passed through a Venturi reactor to undergo a precipitation reaction. After the reaction is completed, the precipitate is filtered to obtain goethite slag 1 and a deironed feed liquid; The goethite slag 1 is mixed with a hydrochloric acid solution for washing to obtain goethite slag 2 and a filtrate.

2. The method for metallurgical iron removal using a Venturi reactor according to claim 1, characterized in that: The oxidation reaction completely oxidizes the divalent iron ions in the metal chloride liquid to be treated into trivalent iron ions.

3. The method for metallurgical iron removal using a Venturi reactor according to claim 2, characterized in that: The oxidant is selected from one or more of oxygen, ozone or hydrogen peroxide.

4. The method for metallurgical iron removal using a Venturi reactor 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.

5. The method for metallurgical iron removal using a Venturi reactor according to claim 4, characterized in that: The hydroxide precipitant includes buffered hydroxide and rare earth hydroxide, wherein 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; 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.

6. The method for metallurgical iron removal using a Venturi reactor according to claim 3, characterized in that: The molar ratio of the oxidant to the divalent iron ions in the metal chloride liquid to be treated is 2.5-4:

1.

7. The method for metallurgical iron removal using a Venturi reactor according to claim 4, characterized in that: The molar ratio of the precipitant to the trivalent iron ions in the oxidized feed solution is 3-3.6:

1.

8. The method for metallurgical iron removal using a Venturi reactor according to claim 1, characterized in that: The temperature of the precipitation reaction is 70-90° C. and the time is 0.5-1.5 h.

9. The method for metallurgical iron removal using a Venturi reactor according to claim 1, characterized in that: The pH of the hydrochloric acid solution is 3.5-4.5; And / or, the liquid-to-solid ratio of the goethite slag 1 mixed with the hydrochloric acid solution is 1-3:1; And / or, the washing temperature is 40-80°C; And / or, the washing time is 0.5~2h.

10. The method for metallurgical iron removal using a Venturi reactor according to any one of claims 1 to 9, characterized in that: The metal chloride material liquid to be treated is a rare earth chloride material liquid to be de-ironized.

Images