Method for separating and recovering iron from iron-containing lithium ore pickle liquor

Abstract

The invention provides a method for separating and recovering iron from an iron-containing lithium ore pickle liquor, and relates to the field of hydrometallurgy. The method comprises the following steps: mixing the iron-containing lithium ore pickle liquor with an oxidizing agent for reaction, and then adding an acidity regulator to regulate the acidity of the solution to a target value; extracting the solution by adopting an iron selective extraction agent to obtain an extraction loaded organic phase and raffinate, and removing impurities from the raffinate to prepare lithium carbonate; washing the extraction loaded organic phase and then performing back extraction to obtain back-extracted liquid; and mixing the back-extraction liquid with a neutralizer to obtain ferric salt slurry, and carrying out solid-liquid separation to obtain a ferric salt solution. According to the method, iron in the lithium ore pickle liquor is comprehensively recycled, impurity ions are not introduced, the loss rate of solution lithium is low, waste utilization can be achieved, waste residue emission is reduced, the process is simple, operation is stable, and the method is suitable for industrial large-scale production.

Description

Technical Field

[0001] The present application relates to the field of hydrometallurgy, and in particular to a method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore. Background Art

[0002] At present, lithium extraction from lithium ore resources mainly adopts sulfuric acid method and sulfate method. In particular, sulfuric acid method has high adaptability and maturity, is suitable for the treatment of most lithium ore resources, and has a high lithium leaching rate. However, during the treatment of lithium ore by sulfuric acid method, a large amount of impurities such as Fe and Al are leached into the solution, with contents of 0.1-20g / L and 1-50g / L respectively.

[0003] The Fe in the sulfuric acid leaching solution of lithium ore is usually removed as an impurity and is not recycled. The neutralization precipitation removal method is mainly used. By adding limestone, lime, alkali or ammonia, Fe is precipitated as iron hydroxide slag and stored without recycling. In addition, due to the strong adsorption of iron hydroxide slag in the conventional precipitation method, the Li loss rate during the precipitation process is 5-10%, which not only affects the recovery rate of lithium, but also increases the amount of solid waste emissions, affecting the environment. Summary of the invention

[0004] The purpose of this application is to provide a method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore to solve the above-mentioned problem.

[0005] To achieve the above objectives, this application adopts the following technical solutions:

[0006] A method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore, comprising:

[0007] The iron-containing lithium ore acid leaching solution is mixed with an oxidant to react, and then an acidity regulator is added to adjust the acidity of the solution to a target value;

[0008] The solution is extracted with an iron selective extractant to obtain an extracted loaded organic phase and a raffinate, and the raffinate is used to prepare lithium carbonate after impurities are removed;

[0009] The extracted loaded organic phase is washed and then stripped to obtain a stripped liquid;

[0010] The stripping liquid is mixed with a neutralizing agent to obtain an iron salt slurry, and an iron salt solution is obtained after solid-liquid separation.

[0011] Preferably, the iron-containing lithium ore acid leaching solution has a lithium content of 0.5-25 g / L, a total iron content of 0.5-20 g / L, a divalent iron content of 0.01-3 g / L, an aluminum content of 5-50 g / L, and a pH of 0.1-3.

[0012] Preferably, the method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore satisfies one or more of the following conditions:

[0013] (1) The oxidant includes one or more of persulfuric acid, hydrogen peroxide, sodium persulfate, air, oxygen, ozone, a mixture of sulfur dioxide and air, or a mixture of sulfur dioxide and oxygen;

[0014] (2) The amount of the oxidant added is 0.1-10 times the molar amount of the divalent iron in the iron-containing lithium ore acid leaching solution;

[0015] (3) The endpoint redox potential of the reaction is 550-700 mV.

[0016] Preferably, the method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore satisfies one or more of the following conditions:

[0017] (1) The acidity regulator includes one or more of sulfuric acid, hydrochloric acid, sodium hydroxide, ammonia, potassium hydroxide, and lithium hydroxide;

[0018] (2) The target value is 0.1-1.5.

[0019] Preferably, the method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore satisfies one or more of the following conditions:

[0020] (1) The iron selective extractant comprises one or more of di(2-ethylhexyl) phosphate, 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester, monoalkyl phosphoric acid, trioctyl / decylamine, and tributyl phosphate;

[0021] (2) the volume concentration of the iron selective extractant is 1-40%;

[0022] (3) The extraction temperature is 5-50°C, and the extraction flow ratio of organic phase: aqueous phase is (0.1-10):1;

[0023] (4) The extraction adopts multi-stage countercurrent extraction, and the number of stages is 2-10;

[0024] (5) adding a diluent during the extraction, wherein the diluent is 260# solvent kerosene;

[0025] (6) The total iron content in the raffinate obtained by the extraction is less than 0.05 g / L.

[0026] Preferably, the method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore satisfies one or more of the following conditions:

[0027] (1) The washing is carried out using sulfuric acid and / or hydrochloric acid at a concentration of 0.1-25 g / L;

[0028] (2) The washing is performed by countercurrent washing, and the number of stages is 1-5;

[0029] (3) The flow ratio of the washing organic phase: aqueous phase is (0.5-100):1.

[0030] Preferably, the method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore satisfies one or more of the following conditions:

[0031] (1) The stripping agent used in the stripping includes sulfuric acid and / or hydrochloric acid with a concentration of 10-200 g / L;

[0032] (2) The stripping temperature is 2-50° C., and the extraction flow ratio of organic phase: aqueous phase is (1-100):1;

[0033] (3) The stripping is performed by countercurrent stripping with the number of stages being 1 to 20.

[0034] Preferably, the method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore satisfies one or more of the following conditions:

[0035] (1) The neutralizing agent includes one or more of ferric hydroxide, ferric oxide, and basic ferric carbonate;

[0036] (2) The pH of the iron salt slurry is 0.2-2.9.

[0037] Preferably, the method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore satisfies one or more of the following conditions:

[0038] (1) The pore size of the filter device used for solid-liquid separation is 1-100 μm, and the material is one or more of polytetrafluoroethylene, polypropylene, and polyester;

[0039] (2) The suspended matter content in the iron salt solution does not exceed 5 g / L.

[0040] Preferably, clean water or a high-concentration iron salt solution is added to the iron salt solution to adjust the iron content in the iron salt solution to 100-250 g / L.

[0041] Compared with the prior art, the beneficial effects of this application include:

[0042] The present application provides a method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore, and uses an extraction method to separate and recover iron ions in the solution. Compared with the traditional precipitation method for removing iron, the discharge of waste iron slag in the lithium extraction process is avoided, and the loss of lithium in the iron separation process is reduced; the traditional method for removing iron and lithium has a loss rate of 5 to 10%, while the extraction method for separating iron has a lithium loss rate of less than 1%; the extraction method is used to separate iron ions in the solution, and iron salts that meet chemical industry standards can be prepared after washing and stripping, and compared with the traditional method of precipitating iron into waste slag, the waste utilization of iron in the solution can be realized. The method is simple to operate, the process is stable and efficient, and it can be applied to industrial-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope of the present application.

[0044] Figure 1 A schematic diagram of the process flow of a method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore provided in an embodiment. DETAILED DESCRIPTION

[0045] In order to better explain the technical solution provided by this application, before the embodiments, the technical solution is first described as a whole, as follows:

[0046] A method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore, comprising:

[0047] The iron-containing lithium ore acid leaching solution is mixed with an oxidant to react, and then an acidity regulator is added to adjust the acidity of the solution to a target value;

[0048] The solution is extracted with an iron selective extractant to obtain an extracted loaded organic phase and a raffinate, and the raffinate is used to prepare lithium carbonate after impurities are removed;

[0049] The extracted loaded organic phase is washed and then stripped to obtain a stripped liquid; the organic extractant is regenerated and recycled;

[0050] The stripping liquid is mixed with a neutralizing agent to obtain an iron salt slurry, and an iron salt solution is obtained after solid-liquid separation.

[0051] In an optional embodiment, the iron-containing lithium ore acid leaching solution has a lithium content of 0.5-25 g / L, a total iron content of 0.5-20 g / L, a divalent iron content of 0.01-3 g / L, an aluminum content of 5-50 g / L, and a pH of 0.1-3.

[0052] Optionally, in the iron-containing lithium ore acid leaching solution, the lithium content can be 0.5g / L, 1g / L, 5g / L, 10g / L, 15g / L, 20g / L, 25g / L or any value between 0.5-25g / L, the total iron content can be 0.5g / L, 1g / L, 5g / L, 10g / L, 15g / L, 20g / L or any value between 0.5-20g / L, and the divalent iron content can be 0.01g / L, 0.05g / L, 0.1g / L, 0. The content of the aqueous solution of the present invention can be 5g / L, 1g / L, 1.5g / L, 2g / L, 2.5g / L, 3g / L or any value between 0.01-3g / L, the aluminum content can be 5g / L, 10g / L, 15g / L, 20g / L, 25g / L, 30g / L, 35g / L, 40g / L, 45g / L, 50g / L or any value between 5-50g / L, and the pH can be 0.1, 0.5, 1, 1.5, 2, 2.5, 3 or any value between 0.1-3.

[0053] In an optional embodiment, the method for separating and recovering iron from an acid leachate of an iron-containing lithium ore satisfies one or more of the following conditions:

[0054] (1) The oxidant includes one or more of persulfuric acid, hydrogen peroxide, sodium persulfate, air, oxygen, ozone, a mixture of sulfur dioxide and air, or a mixture of sulfur dioxide and oxygen;

[0055] By using the above substances as oxidants, a small amount of divalent iron in the oxidation solution can be oxidized without introducing other impurity ions that affect lithium extraction.

[0056] (2) The amount of the oxidant added is 0.1-10 times the molar amount of the divalent iron in the iron-containing lithium ore acid leaching solution;

[0057] Optionally, the amount of the oxidant added may be 0.1 times, 1 times, 2 times, 3 times, 4 times, 5 times, 6 times, 7 times, 8 times, 9 times, 10 times or any value between 0.1 and 10 times the molar amount of divalent iron in the iron-containing lithium ore acid leaching solution;

[0058] (3) The endpoint redox potential of the reaction is 550-700 mV.

[0059] Optionally, the endpoint redox potential of the reaction may be 550 mV, 600 mV, 650 mV, 700 mV or any value between 550-700 mV.

[0060] The amount of oxidant added and the oxidation endpoint potential are limited in order to completely oxidize the divalent iron in the solution to trivalent iron, because the extractant used only selectively extracts trivalent iron and does not extract divalent iron. If there is no oxidation, or the oxidation is not thorough, the divalent iron is not extracted, and the total iron removal rate in the solution will be reduced, and the purpose of complete removal cannot be achieved.

[0061] In an optional embodiment, the method for separating and recovering iron from an acid leachate of an iron-containing lithium ore satisfies one or more of the following conditions:

[0062] (1) The acidity regulator includes one or more of sulfuric acid, hydrochloric acid, sodium hydroxide, ammonia, potassium hydroxide, and lithium hydroxide;

[0063] (2) The target value is 0.1-1.5.

[0064] Optionally, the target value may be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5 or any value between 0.1-1.5.

[0065] Iron extraction is the process of extracting iron under acidic conditions with a low pH value of the solution. If the pH value of the solution is not adjusted to an appropriate value, too high or too low acidity will be detrimental to the iron extraction rate. The pH value will affect the iron extraction rate.

[0066] In an optional embodiment, the method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore satisfies one or more of the following conditions:

[0067] (1) The iron selective extractant includes one or more of di(2-ethylhexyl) phosphate (P204), 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (P507), monoalkyl phosphoric acid (P538), trioctyl / decylamine (N235), and tributyl phosphate (TBP);

[0068] (2) the volume concentration of the iron selective extractant is 1-40%;

[0069] Optionally, the volume concentration of the iron selective extractant may be 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40% or any value between 1-40%;

[0070] (3) The extraction temperature is 5-50°C, and the extraction flow ratio of organic phase: aqueous phase is (0.1-10):1;

[0071] Optionally, the extraction temperature may be 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C or any value between 5-50°C, and the extraction flow ratio of organic phase:aqueous phase may be 0.1:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1 or any value between (0.1-10):1;

[0072] (4) The extraction adopts multi-stage countercurrent extraction, and the number of stages is 2-10;

[0073] Optionally, the number of extraction stages may be 2, 3, 4, 5, 6, 7, 8, 9, 10, or any value between 2 and 10;

[0074] (5) adding a diluent during the extraction, wherein the diluent is 260# solvent kerosene;

[0075] Under certain conditions, solvent extraction can completely remove, separate and recover iron from the solution without forming precipitated slag, and will not adsorb lithium to cause lithium loss, which is beneficial to the subsequent separation and recovery of aluminum in the solution.

[0076] (6) The total iron content in the raffinate obtained by the extraction is less than 0.05 g / L.

[0077] In an optional embodiment, the method for separating and recovering iron from an acid leachate of an iron-containing lithium ore satisfies one or more of the following conditions:

[0078] (1) The washing is carried out using sulfuric acid and / or hydrochloric acid at a concentration of 0.1-25 g / L;

[0079] Optionally, the concentration of the acid used for washing can be 0.1 g / L, 1 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L or any value between 0.1-25 g / L;

[0080] (2) The washing is performed by countercurrent washing, and the number of stages is 1-5;

[0081] Optionally, the washing level may be 1, 2, 3, 4, 5, or any value between 1 and 5;

[0082] (3) The flow ratio of the washing organic phase: aqueous phase is (0.5-100):1.

[0083] During the iron extraction process, the organic phase carries over and extracts a small amount of aluminum and lithium. A dilute acid solution is needed to wash off the aluminum and lithium carried over and extracted by the organic phase. This can reduce lithium loss on the one hand, and improve the purity of the iron salt obtained by stripping on the other hand, and reduce the impurity content in the iron salt.

[0084] Optionally, the wash flow ratio of organic phase:aqueous phase can be 0.5:1, 1:1, 5:1, 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, 100:1 or any value between (0.5-100):1.

[0085] In an optional embodiment, the method for separating and recovering iron from an acid leachate of an iron-containing lithium ore satisfies one or more of the following conditions:

[0086] (1) The stripping agent used in the stripping includes sulfuric acid and / or hydrochloric acid with a concentration of 10-200 g / L;

[0087] Optionally, the concentration of the stripping agent used in the stripping may be 10 g / L, 50 g / L, 100 g / L, 150 g / L, 200 g / L or any value between 10 and 200 g / L;

[0088] (2) The stripping temperature is 2-50° C., and the extraction flow ratio of organic phase: aqueous phase is (1-100):1;

[0089] Optionally, the back extraction temperature may be 2°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C or any value between 2-50°C, and the extraction flow ratio organic phase: aqueous phase may be 1:1, 5:1, 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, 100:1 or any value between (1-100):1;

[0090] (3) The stripping is performed by countercurrent stripping with the number of stages being 1 to 20.

[0091] Optionally, the number of back extraction stages can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or any value between 1 and 20;

[0092] The iron in the loaded organic phase is stripped under appropriate conditions to obtain a higher concentration of iron salt solution, and the organic phase is regenerated at the same time, so that the organic phase can be recycled and the operation consumption can be reduced.

[0093] In an optional embodiment, the method for separating and recovering iron from an acid leachate of an iron-containing lithium ore satisfies one or more of the following conditions:

[0094] (1) The neutralizing agent includes one or more of ferric hydroxide, ferric oxide, and basic ferric carbonate;

[0095] (2) The pH of the iron salt slurry is 0.2-2.9.

[0096] Optionally, the pH of the iron salt slurry may be 0.2, 0.5, 1.0, 1.5, 2.0, 2.5, 2.9 or any value between 0.2 and 2.9.

[0097] In an optional embodiment, the method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore satisfies one or more of the following conditions:

[0098] (1) The pore size of the filter device used for solid-liquid separation is 1-100 μm, and the material is one or more of polytetrafluoroethylene (PTFE), polypropylene (PP), and polyester (PET);

[0099] The filtering device is one of a horizontal filter press, a vertical filter press, a vacuum disc filter, a precision filter, a bag filter and / or a combination of any of them. The pore size and material referred to here refer to the parameters of the filter cloth in the aforementioned equipment.

[0100] Optionally, the pore size of the filter device used for the solid-liquid separation may be 1 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm or any value between 1 and 100 μm;

[0101] (2) The suspended matter content in the iron salt solution does not exceed 5 g / L.

[0102] Because in the process of neutralizing the residual acid in the iron salt solution, the amount of neutralizer added will be excessive, and there will be some insoluble matter, and the suspended matter content will be greater than 5g / L, which exceeds the requirements of the chemical industry standards for suspended matter in iron salt solutions. Therefore, certain filtering devices are used to reduce the suspended matter in the solution to a certain content to meet the product standard requirements.

[0103] In an optional embodiment, clean water or a high-concentration iron salt solution is added to the iron salt solution to adjust the iron content in the iron salt solution to 100-250 g / L.

[0104] After the above series of processes, in order to obtain an iron salt product with stable concentration, the concentration of the iron salt solution is adjusted. If the iron salt content exceeds the standard value too much, it can be diluted with clean water; if the iron salt content in the iron salt solution is lower than the standard value, some high-concentration iron salt solution is added for adjustment, thereby producing a product with stable iron salt concentration.

[0105] The embodiments of the present application will be described in detail below in conjunction with specific examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If specific conditions are not specified in the examples, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0106] Example 1

[0107] like Figure 1 As shown, this embodiment provides a method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore, which specifically comprises the following steps:

[0108] A clay-type lithium ore calcination-acid leaching solution is composed of 1.7 g / L lithium, 3.5 g / L total iron, 0.45 g / L divalent iron, 16.5 g / L aluminum, and a solution pH of 2.0; the molar amount of hydrogen peroxide added is 0.6 times the molar amount of divalent iron in the lithium ore acid leaching solution, and the end point solution redox potential is controlled to be 600 mV, and the divalent iron in the solution is completely oxidized to trivalent iron; sulfuric acid is then added to the solution to adjust the end point acidity pH of the solution to 1.0; the solution with adjusted acidity is subjected to three-stage countercurrent extraction of iron using an iron selective extractant with a volume content of 30% of trioctyl / decylamine (N235) and tributyl phosphate (TBP), and a volume content of 70% of diluent 260# solvent kerosene, the extraction temperature is 30°C, and the extraction flow ratio is organic phase / aqueous phase = 1; the loss rate of lithium in the solution during the iron extraction process is 0.25%, and the iron extraction rate is 99.8%, The total iron content in the raffinate is 0.007 g / L, and the raffinate is removed by a conventional method to prepare a lithium carbonate product; the extracted loaded organic phase is washed with a sulfuric acid solution with a concentration of 5 g / L for two-stage countercurrent washing, and the washing flow ratio is organic phase / aqueous phase=5; the loaded organic phase is countercurrently stripped for three stages with a 125 g / L sulfuric acid solution, and the stripping flow ratio is organic phase / aqueous phase=40, and the stripping temperature is 30°C; ferric hydroxide is added to the stripped solution obtained by stripping, and the pH value of the solution is adjusted to 2.5 to obtain an iron salt slurry; the iron salt slurry is filtered through a horizontal filter press with a filter cloth pore size of 20 microns and a filter cloth material of polypropylene (PP) to remove suspended matter in the solution that has not been completely reacted, so that the content of suspended matter in the filtered filtrate reaches 0.1 g / L; the filtered iron sulfate filtrate is added with clean water, and the iron content in the iron salt solution is slightly adjusted to 145 g / L, meeting the iron sulfate requirements of the chemical industry standard HG / T 4816-2015.

[0109] Example 2

[0110] This embodiment provides a method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore, which specifically comprises the following steps:

[0111] A calcined-acidified roasted-water leaching solution of a spodumene concentrate contains 20.5 g / L lithium, 2.6 g / L total iron, 0.30 g / L divalent iron, 12.8 g / L aluminum, and a solution pH of 2.3; persulfuric acid is added in a molar amount of 0.7 times the molar amount of divalent iron in the acid leaching solution of the spodumene concentrate, and the redox potential of the end point solution is controlled to be 650 mV, so that the divalent iron in the solution is completely oxidized to trivalent iron; sulfuric acid is then added to the solution to adjust the pH value of the end point acidity of the solution to 0.8; the solution with adjusted acidity is subjected to 4-stage countercurrent extraction of iron using an iron selective extractant having a volume content of 25% of di(2-ethylhexyl) phosphate (P204) and tributyl phosphate (TBP) and a volume content of 75% of diluent 260# solvent kerosene, the extraction temperature is 40°C, and the extraction flow ratio is organic phase / aqueous phase=0.8; the loss rate of lithium in the solution during the iron extraction process is 0.10%, and the iron The extraction rate is 99.85%, the total iron content in the raffinate is 0.004 g / L, and the raffinate is impurity-removed by a conventional method to prepare a lithium carbonate product; the extracted loaded organic phase is washed with a hydrochloric acid solution with a concentration of 10 g / L for 3-stage countercurrent washing, and the washing flow ratio is organic phase / aqueous phase=15; the loaded organic phase is countercurrently stripped with a 350 g / L hydrochloric acid solution for 5-stage stripping, and the stripping flow ratio is organic phase / aqueous phase=55, and the stripping temperature is 40°C; iron oxide is added to the stripped liquid obtained by stripping, and the pH value of the solution is adjusted to 0.5 to obtain an iron salt slurry; the iron salt slurry is filtered through a vertical filter press with a filter cloth pore size of 50 microns and a filter cloth material of polyester (PET) to remove suspended matter in the solution that has not been completely reacted, so that the suspended matter content in the filtered filtrate reaches 1 g / L; the ferric chloride filtrate obtained by filtering is added with ferric chloride solid, and the iron content in the iron salt solution is slightly adjusted to 185 g / L, meeting the chemical industry standard GB / T Ferric chloride requirements for 1621-2023.

[0112] Example 3

[0113] This embodiment provides a method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore, which specifically comprises the following steps:

[0114] A mixed lithium ore calcination-acid leaching solution, the composition is 10g / L lithium, 5.3g / L total iron, 0.65g / L divalent iron, 9g / L aluminum, the solution pH value is 0.5; sulfur dioxide (volume content 3%) and air mixed gas are added, the molar amount of sulfur dioxide in the mixed gas is 3 times the molar amount of divalent iron in the mixed lithium ore acid leaching solution, and the end point solution redox potential is controlled to 600mV, the divalent iron in the solution is completely oxidized to trivalent iron; then, sulfur dioxide (volume content 3%) and air mixed gas are added, the molar amount of sulfur dioxide in the mixed gas is 3 times the molar amount of divalent iron in the mixed lithium ore acid leaching solution, and the end point solution redox potential is controlled to 600mV, the divalent iron in the solution is completely oxidized to trivalent iron; then, sulfur dioxide (volume content 3%) and air mixed gas are added to the mixed gas ... the molar amount of sulfur dioxide in the mixed gas is 3 times the molar amount of divalent iron in the mixed lithium ore Sodium hydroxide was added to the solution to adjust the pH value of the solution to 1.2; the solution with adjusted acidity was extracted with iron selective extractant in 5-stage countercurrent with monoalkyl phosphoric acid (P538) and trioctyl / decylamine (N235) with a volume content of 20% and a diluent 260# solvent kerosene with a volume content of 80%, the extraction temperature was 45°C, and the extraction flow ratio was organic phase / aqueous phase = 2; the loss rate of lithium in the solution during the iron extraction process was 0.15%, and the iron extraction rate was 99.9 %, the total iron content in the raffinate is 0.005g / L, and the raffinate is impurity-removed by a conventional method to prepare a lithium carbonate product; the extracted loaded organic phase is washed with a hydrochloric acid solution with a concentration of 20g / L for 2-stage countercurrent washing, and the washing flow ratio is organic phase / aqueous phase=20; the loaded organic phase is countercurrently stripped with a 320g / L hydrochloric acid solution for 5-stage stripping, and the stripping flow ratio is organic phase / aqueous phase=45, and the stripping temperature is 45°C; basic iron carbonate is added to the stripped liquid obtained by stripping, and the pH value of the solution is adjusted to 1.0 to obtain an iron salt slurry; the iron salt slurry is filtered through a bag filter with a filter cloth pore size of 125 microns and a filter cloth material of polyester (PET) to remove suspended matter in the solution that has not been completely reacted, so that the suspended matter content in the filtered filtrate reaches 3g / L; the ferric chloride filtrate obtained by filtration is added to clean water, and the iron content in the iron salt solution is slightly adjusted to 185g / L, meeting the iron sulfate requirements of the chemical industry standard HG / T4816-2015.

[0115] Comparative Example 1

[0116] A clay-type lithium ore calcination-acid leaching solution, the composition is 1.7g / L lithium, 3.5g / L total iron, 0.45g / L divalent iron, 16.5g / L aluminum, the solution pH value is 2.0; the molar amount of hydrogen peroxide added is 0.3 times the molar amount of divalent iron in the lithium ore acid leaching solution, and the end point solution redox potential is controlled to be 300mV, and the divalent iron in the solution is partially oxidized to trivalent iron; then sulfuric acid is added to the solution to adjust the end point acidity pH value of the solution to 1.0; the solution with adjusted acidity is treated with trioctyl / decylamine (N2 35) and tributyl phosphate (TBP) with a volume content of 30%, and a diluent 260# solvent kerosene with a volume content of 70% by iron selective extractant 3-stage countercurrent extraction of iron, the extraction temperature is 30°C, and the extraction flow ratio is organic phase / aqueous phase = 1; the iron extraction rate in the solution is 92.9%, and the total iron content in the raffinate is 0.25 g / L, which does not achieve the purpose of completely separating iron. The raffinate needs to be further removed from the residual iron in the solution during the conventional method for removing impurities before the lithium carbonate product can be prepared, which is not conducive to the recovery of aluminum and lithium in the solution.

[0117] Comparative Example 2

[0118] The composition of a clay-type lithium ore calcination-acid leaching solution is 1.7 g / L lithium, 3.5 g / L total iron, 0.45 g / L divalent iron, 16.5 g / L aluminum, and the pH value of the solution is 2.0; the molar amount of hydrogen peroxide added is 0.6 times the molar amount of divalent iron in the lithium ore acid leaching solution, and the end point solution redox potential is controlled to be 600 mV, and the divalent iron in the solution is completely oxidized to trivalent iron; under the condition that the pH value of the solution is 2.0 and the pH value of the solution is not adjusted, the solution after oxidizing the divalent iron is treated with trioctyl / decylamine (N235 ) and tributyl phosphate (TBP) with a volume content of 30%, a diluent 260# solvent kerosene with a volume content of 70%, an iron selective extractant with a three-stage countercurrent extraction of iron, an extraction temperature of 30°C, and an extraction flow ratio of organic phase / aqueous phase = 1; the iron extraction rate in the solution is 65.6%, and the total iron content in the raffinate is 1.20 g / L. The solution does not achieve the purpose of completely separating iron. The raffinate needs to be further removed from the residual iron in the solution during the conventional method for removing impurities before the lithium carbonate product can be prepared, which is not conducive to the recovery of aluminum and lithium in the solution.

[0119] Comparative Example 3

[0120] A clay-type lithium ore calcination-acid leaching solution, the composition is 1.7g / L lithium, 3.5g / L total iron, 0.45g / L divalent iron, 16.5g / L aluminum, and the solution pH is 2.0; the molar amount of hydrogen peroxide added is 0.6 times the molar amount of divalent iron in the lithium ore acid leaching solution, and the end point solution redox potential is controlled to be 600mV, and the divalent iron in the solution is completely oxidized to trivalent iron; sulfuric acid is then added to the solution to adjust the end point acidity pH value of the solution to 1.0; the solution with adjusted acidity is treated with trioctyl / decylamine (N235) and tributyl phosphate (TBP) with a volume content of 30%, and a diluent 260# solvent kerosene with a volume content of 70% iron selectivity The extractant is used for three-stage countercurrent extraction of iron, the extraction temperature is 30°C, and the extraction flow ratio is organic phase / aqueous phase=1; the iron extraction rate in the solution is 99.8%, the total iron content in the raffinate is 0.007g / L, and the lithium carbonate product is prepared after impurities are removed by conventional methods; the extracted loaded organic phase is directly subjected to three-stage countercurrent stripping with 125g / L sulfuric acid solution without washing, the stripping flow ratio is organic phase / aqueous phase=40, and the stripping temperature is 30°C; although stripping can also obtain ferric sulfate solution, since the organic phase carries a small amount of aluminum and lithium in the solution during the extraction process, the aluminum and lithium contents in the ferric sulfate solution obtained by stripping are 22g / L and 0.2g / L respectively, which is not suitable for preparing ferric sulfate products of the chemical industry standard HG / T 4816-2015, and the total lithium loss rate in this process is 1.5%, which is higher than 0.25% of the added washing process.

[0121] Comparative Example 4

[0122] A clay-type lithium ore calcination-acid leaching solution, the composition is 1.7g / L lithium, 3.5g / L total iron, 0.45g / L divalent iron, 16.5g / L aluminum, and the solution pH is 2.0; the molar amount of hydrogen peroxide added is 0.6 times the molar amount of divalent iron in the lithium ore acid leaching solution, and the end point solution redox potential is controlled to be 600mV, and the divalent iron in the solution is completely oxidized to trivalent iron; sulfuric acid is then added to the solution to adjust the end point acidity pH value of the solution to 1.0; the solution with adjusted acidity is treated with trioctyl / decylamine (N235) and tributyl phosphate (TBP) with a volume content of 30%, and a diluent 260# solvent kerosene with a volume content of 70% iron selectivity The extractant extracts iron in three-stage countercurrent, the extraction temperature is 30°C, and the extraction flow ratio is organic phase / aqueous phase = 1; the loss rate of lithium in the solution during the iron extraction process is 0.25%, the iron extraction rate is 99.8%, and the total iron content in the raffinate is 0.007g / L. The lithium carbonate product is prepared after impurities are removed by conventional methods; the extracted loaded organic phase is washed with a sulfuric acid solution with a concentration of 5g / L for two-stage countercurrent washing, and the washing flow ratio is organic phase / aqueous phase = 5; the loaded organic phase is countercurrently stripped in three stages with a 125g / L sulfuric acid solution, the stripping flow ratio is organic phase / aqueous phase = 40, and the stripping temperature is 30°C; the sulfuric acid concentration in the stripped liquid obtained by stripping is 12g / L, which exceeds the chemical industry standard HG / T 4816-2015 has requirements for acid content in ferric sulfate solution, so it is necessary to add ferric hydroxide, ferric oxide or basic ferric carbonate, adjust the pH value of the solution to 2.5, and obtain an iron salt slurry, wherein the content of suspended solids of unreacted ferric hydroxide is 13g / L, which exceeds the requirements of chemical industry standard HG / T 4816-2015 for the content of water-insoluble substances in ferric sulfate solution; therefore, it is necessary to filter the unreacted suspended solids in the solution of the iron salt slurry using a horizontal filter press with a filter cloth pore size of 20 microns and a filter cloth material of polypropylene (PP), so that the suspended solid content in the filtered filtrate reaches 0.1g / L; the filtered ferric sulfate filtrate is added with clean water, and the iron content in the iron salt solution is slightly adjusted to 145g / L, meeting the requirements of chemical industry standard HG / T 4816-2015 for ferric sulfate.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore, characterized in that: include: The iron-containing lithium ore acid leaching solution is mixed with an oxidant to react, and then an acidity regulator is added to adjust the acidity of the solution to a target value; The solution is extracted with an iron selective extractant to obtain an extracted loaded organic phase and a raffinate, and the raffinate is used to prepare lithium carbonate after impurities are removed; The extracted loaded organic phase is washed and then stripped to obtain a stripped liquid; The stripping liquid is mixed with a neutralizing agent to obtain an iron salt slurry, and an iron salt solution is obtained after solid-liquid separation.

2. The method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore according to claim 1, characterized in that: The iron-containing lithium ore acid leaching solution has a lithium content of 0.5-25 g / L, a total iron content of 0.5-20 g / L, a divalent iron content of 0.01-3 g / L, an aluminum content of 5-50 g / L, and a pH of 0.1-3.

3. The method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore according to claim 1, characterized in that: One or more of the following conditions are met: (1) The oxidant includes one or more of persulfuric acid, hydrogen peroxide, sodium persulfate, air, oxygen, ozone, a mixture of sulfur dioxide and air, or a mixture of sulfur dioxide and oxygen; (2) The amount of the oxidant added is 0.1-10 times the molar amount of the divalent iron in the iron-containing lithium ore acid leaching solution; (3) The endpoint redox potential of the reaction is 550-700 mV.

4. The method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore according to claim 1, characterized in that: One or more of the following conditions are met: (1) The acidity regulator includes one or more of sulfuric acid, hydrochloric acid, sodium hydroxide, ammonia, potassium hydroxide, and lithium hydroxide; (2) The target value is 0.1-1.

5.

5. The method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore according to claim 1, characterized in that: One or more of the following conditions are met: (1) The iron selective extractant comprises one or more of di(2-ethylhexyl) phosphate, 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester, monoalkyl phosphoric acid, trioctyl / decylamine, and tributyl phosphate; (2) the volume concentration of the iron selective extractant is 1-40%; (3) The extraction temperature is 5-50°C, and the extraction flow ratio of organic phase: aqueous phase is (0.1-10):1; (4) The extraction adopts multi-stage countercurrent extraction, and the number of stages is 2-10; (5) adding a diluent during the extraction, wherein the diluent is 260# solvent kerosene; (6) The total iron content in the raffinate obtained by the extraction is less than 0.05 g / L.

6. The method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore according to claim 1, characterized in that: One or more of the following conditions are met: (1) The washing is carried out using sulfuric acid and / or hydrochloric acid at a concentration of 0.1-25 g / L; (2) The washing is performed by countercurrent washing, and the number of stages is 1-5; (3) The flow ratio of the washing organic phase: aqueous phase is (0.5-100):

1.

7. The method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore according to claim 1, characterized in that: One or more of the following conditions are met: (1) The stripping agent used in the stripping includes sulfuric acid and / or hydrochloric acid with a concentration of 10-200 g / L; (2) The stripping temperature is 2-50° C., and the extraction flow ratio of organic phase: aqueous phase is (1-100):1; (3) The stripping is performed by countercurrent stripping with the number of stages being 1 to 20.

8. The method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore according to claim 1, characterized in that: One or more of the following conditions are met: (1) The neutralizing agent includes one or more of ferric hydroxide, ferric oxide, and basic ferric carbonate; (2) The pH of the iron salt slurry is 0.2-2.

9.

9. The method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore according to claim 1, characterized in that: One or more of the following conditions are met: (1) The pore size of the filter device used for solid-liquid separation is 1-100 μm, and the material is one or more of polytetrafluoroethylene, polypropylene, and polyester; (2) The suspended matter content in the iron salt solution does not exceed 5 g / L.

10. The method for separating and recovering iron from an acid leaching solution of an iron-containing lithium ore according to any one of claims 1 to 9, characterized in that: The iron salt solution is added with clean water or a high-concentration iron salt solution to adjust the iron content in the iron salt solution to 100-250 g / L.

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