Method for separating and recovering nickel and iron from nickel-iron material

Abstract

The present disclosure belongs to the field of resource recovery. The present disclosure provides a method for separating and recovering nickel and iron from a nickel-iron material. The method comprises: carrying out acid leaching on a nickel-iron material, adjusting a leachate to remove chromium and aluminum impurities, adding a reducing agent to the impurity-removed solution to reduce iron ions, and then using a resin to adsorb nickel ions from the solution to obtain a saturated resin and an iron-containing solution, thereby realizing the separation of nickel from iron; and desorbing the saturated resin having adsorbed the nickel ions to obtain a nickel-containing solution, wherein the nickel-containing solution and the iron-containing solution can undergo subsequent treatment to obtain nickel and iron products. Compared with a conventional recovery process, the present disclosure involves using the resin, so that not only is the nickel concentration enriched, thereby separating iron from nickel in a high-selectivity manner, but also a complex impurity removal and purification process is omitted, and the resin can be recycled after being desorbed, so that the technological process is greatly economized, and the recovery cost is reduced.

Description

A method for separating and recovering ferronickel from ferronickel material Technical Field

[0001] The present invention relates to a method for separating and recovering ferronickel from ferronickel material. Background Art

[0002] Laterite nickel ore is an important nickel metal resource.

[0003] Currently, there are two main methods for recovering laterite nickel ore: pyrometallurgy and hydrometallurgy. The direct hydrometallurgical method, such as the direct pressure acid leaching of laterite nickel ore in CN101525690A and CN104651609A, is suitable for processing low-grade laterite nickel ore, but the nickel recovery cost is relatively high. The reduction roasting-magnetic separation process, such as the one in CN103233114A, is effective in recovering nickel, and features low energy consumption and a simple process. Therefore, it is currently one of the mainstream methods for recovering metals from laterite nickel ore.

[0004] The reduction roasting-magnetic separation process mainly reduces valuable metal oxides such as nickel and iron in laterite nickel ore into a highly magnetic metal phase, and then obtains nickel-iron material through magnetic separation. For example, in CN103233114A, the laterite nickel ore can be processed to obtain metallic nickel with a purity of 95% to 97%, metallic iron with a purity of 94% to 96%, and a nickel-iron alloy with nickel accounting for 10% to 13% and iron accounting for 71% to 79%. It can be seen that the nickel-iron material obtained by the reduction roasting-magnetic separation process still needs to be further processed to enhance the separation and recovery effect of nickel and iron resources.

[0005] Currently, the primary process for recovering ferronickel from ferronickel material involves wet leaching, impurity removal, and subsequent precipitation of ferric phosphate, followed by nickel recovery. This method is ineffective for separating ferronickel and ferro-nickel, requires complex impurity removal steps, consumes a large amount of auxiliary materials, and carries the risk of introducing new impurities, often resulting in substandard product parameters.

[0006] Therefore, the industry currently needs a nickel-iron material recycling method with good nickel-iron separation effect, simple process and lower cost.

[0007] Summary of the Invention

[0008] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0009] In view of the problems existing in the prior art, the purpose of the present disclosure is to provide a method for separating and recovering nickel iron from nickel iron material, wherein the method involves acid leaching the nickel iron material, adjusting the leachate to remove chromium and aluminum impurities, adding a reducing agent to the impurity removal liquid to reduce iron ions, and then subjecting the solution to resin adsorption of nickel ions to obtain saturated resin and iron-containing solution, thereby achieving separation of nickel and iron. After desorption and desorption of the saturated resin adsorbed with nickel ions, a nickel-containing solution can be obtained, and the nickel-containing solution and the iron-containing solution can be subsequently processed to obtain nickel and iron products. Compared with traditional recovery processes, the present disclosure uses resin not only to enrich the nickel concentration, but also to highly selectively separate iron and nickel, and omits the complex impurity removal and purification process. The resin can be regenerated and recycled after desorption, thereby greatly saving the process flow and reducing the recovery cost.

[0010] To achieve this goal, the present disclosure adopts the following technical solutions:

[0011] In a first aspect, the present disclosure provides a method for separating and recovering ferronickel from a ferronickel material, the method comprising the following steps:

[0012] The nickel-iron material is subjected to acid leaching to dissolve nickel and iron to obtain a leachate and a leach residue;

[0013] The leachate is adjusted to remove chromium and aluminum impurities to obtain a decontaminated liquid and decontaminated slag;

[0014] Mixing a reducing agent with the impurity removal liquid to reduce the iron ions to obtain a reducing atmosphere liquid;

[0015] The reducing atmosphere liquid is subjected to resin adsorption to adsorb nickel ions to obtain a saturated resin and an iron-containing solution;

[0016] The saturated resin is desorbed to desorb nickel ions to obtain a nickel-containing solution.

[0017] Considering that nickel-iron materials contain a large amount of non-nickel-iron impurity metals, such as chromium and aluminum, the method described in the present disclosure first adjusts the acid leaching solution and increases the pH to precipitate chromium and aluminum impurities for removal until the content is reduced to within the qualified range to obtain a de-impurity solution; then, a reducing agent is added to reduce the trivalent iron ions in the solution to divalent iron ions and prevent the divalent iron ions from being oxidized again. By removing the trivalent iron ions, the loss of iron elements caused by the adsorption of iron ions can be avoided in the subsequent resin adsorption, and the damage to the resin caused by the adsorption of iron ions can be avoided; therefore, when the resulting reducing atmosphere liquid is subjected to resin adsorption, the separation effect of nickel and iron can be guaranteed, and a saturated resin with high nickel content and purity, as well as an iron-containing solution with high iron content and purity can be obtained; after desorption of the saturated resin, a nickel-containing solution with high nickel content and purity can be obtained; the iron-containing solution and the nickel-containing solution can be further processed into iron salt and nickel salt products. Compared with traditional recycling processes, the method separates iron and nickel with high selectivity and omits complex impurity removal and purification steps. The resin can be regenerated and recycled after desorption, thus greatly saving process flow and reducing recycling costs.

[0018] The nickel-iron material disclosed in the present invention is a nickel-iron alloy, and its component content fluctuates due to different laterite nickel ore production areas and recovery processes. The mass content of the main metals is Ni: 8% to 25%, Fe: 70% to 90%, Co: 0.1% to 1%, Cr: 0.01% to 0.2%, Si: 0.05% to 0.5%, and Al: 0.05% to 0.5%.

[0019] The following are optional technical solutions of the present disclosure, but are not intended to limit the technical solutions provided by the present disclosure. Through the following technical solutions, the technical objectives and beneficial effects of the present disclosure can be better achieved and realized.

[0020] As an optional technical solution of the present disclosure, the acid used for the acid leaching includes any one of sulfuric acid, hydrochloric acid, nitric acid or phosphoric acid, or a combination of at least two of them. Typical but non-limiting examples of the combination include a combination of sulfuric acid and hydrochloric acid, a combination of sulfuric acid and nitric acid, a combination of sulfuric acid and phosphoric acid, a combination of hydrochloric acid and nitric acid, a combination of hydrochloric acid and phosphoric acid, or a combination of phosphoric acid and nitric acid.

[0021] In one embodiment, the amount of acid added for the acid leaching is 1 to 2 times the theoretical reaction amount of nickel and iron in the nickel-iron material, for example, 1 times, 1.1 times, 1.2 times, 1.3 times, 1.4 times, 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times or 2 times, etc., but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0022] In one embodiment, the acid leaching time is 0.5 to 4 hours, for example, 0.5 hours, 0.8 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours or 4 hours, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0023] The purpose of acid leaching is to dissolve nickel and iron. There are no specific requirements for the type of acid used; any acid that can dissolve nickel and iron is suitable, and the type of acid does not affect the formation of ferric phosphate. Excessive acid can increase the acidity of the leachate, increasing the alkali consumption required for the subsequent adjustment. From an economic perspective, an acid dosage of 1.0 times the theoretical amount is recommended. Elemental leaching is not difficult; generally, an acid dosage of 1.2 times the theoretical amount has no significant effect on improving the leaching rate.

[0024] As an optional technical solution disclosed in the present invention, the pH value range of the adjustment is 2.5 to 6.5, for example, 2.5, 2.8, 3.1, 3.4, 3.7, 4, 4.3, 4.6, 4.9, 5.2, 5.5, 5.8, 6, 6.3 or 6.5, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0025] In one embodiment, the alkali used for the adjustment includes any one of sodium hydroxide, sodium carbonate, nickel carbonate, nickel hydroxide, calcium hydroxide or calcium carbonate, or a combination of at least two thereof. Typical but non-limiting examples of the combination include a combination of sodium hydroxide and sodium carbonate, a combination of sodium hydroxide and nickel carbonate, a combination of sodium hydroxide and nickel hydroxide, a combination of sodium hydroxide and calcium hydroxide, a combination of sodium carbonate and calcium carbonate, a combination of sodium carbonate and nickel carbonate, a combination of sodium carbonate and nickel hydroxide, a combination of nickel carbonate and calcium carbonate, a combination of nickel hydroxide and calcium carbonate, or a combination of sodium carbonate and calcium hydroxide.

[0026] The purpose of adjusting the pH is to remove impurities, precipitating Cr and Al impurities in the leachate as hydroxides, thereby reducing the risk of impurities in subsequent products. The type of alkali does not affect the impurity removal effect. From the perspective of not introducing new elements, nickel carbonate and nickel hydroxide are suitable alkalis. During acid leaching, if phosphoric acid is used, chromium will form chromium phosphate and precipitate completely at a pH of around 3, while Al will precipitate completely at a pH of around 5. Therefore, a further optional pH range is 4.5-5.5. If the pH is too low, there will be no precipitation effect, while if the pH is too high, the precipitation loss of the main metals (iron and nickel) will increase.

[0027] As an optional technical solution of the present invention, the amount of the reducing agent is 5 to 100 mmol / L, for example, 5 mmol / L, 10 mmol / L, 15 mmol / L, 20 mmol / L, 25 mmol / L, 30 mmol / L, 35 mmol / L, 40 mmol / L, 45 mmol / L, 50 mmol / L, 55 mmol / L, 60 mmol / L, 65 mmol / L, 70 mmol / L, 75 mmol / L, 80 mmol / L, 85 mmol / L, 90 mmol / L, 95 mmol / L or 100 mmol / L, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0028] In one embodiment, the reducing agent includes any one of sodium sulfite, potassium iodide, hydroxylamine hydrochloride, thiourea, ethylene glycol or iron powder, or a combination of at least two thereof. Typical but non-limiting examples of the combination include a combination of sodium sulfite and potassium iodide, a combination of sodium sulfite and hydroxylamine hydrochloride, a combination of sodium sulfite and thiourea, a combination of sodium sulfite and ethylene glycol, a combination of sodium sulfite and iron powder, a combination of potassium iodide and hydroxylamine hydrochloride, a combination of potassium iodide and thiourea, a combination of potassium iodide and ethylene glycol, a combination of potassium iodide and iron powder, a combination of hydroxylamine hydrochloride and thiourea, a combination of hydroxylamine hydrochloride and ethylene glycol, a combination of hydroxylamine hydrochloride and iron powder, a combination of thiourea and ethylene glycol, a combination of thiourea and iron powder, or a combination of ethylene glycol and iron powder.

[0029] The purpose of adding the reducing agent is to prevent the oxidation of divalent iron to trivalent iron. If the resin adsorbs trivalent iron, it will affect the resin on the one hand and cause iron loss on the other hand.

[0030] In one embodiment, the method further comprises: subjecting the leached residue and the impurity-removed residue to secondary acid leaching, and returning the solution directly or after impurity removal to the acid leaching process for reuse.

[0031] As an optional technical solution of the present disclosure, the resin adsorption uses at least four resin columns in a series structure.

[0032] The present invention adopts a resin series adsorption method to ensure that the tail liquid is qualified and the working exchange capacity of the resin is increased. For the adsorption of the solution obtained after leaching of the nickel-ferronickel material, at least four resin columns need to be connected in series to ensure the adsorption effect.

[0033] In one embodiment, the volume filling amount of the resin in the resin column is 70% to 90%, for example, 70%, 72%, 74%, 76%, 78%, 80%, 82%, 84%, 86%, 88% or 90%, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0034] In one embodiment, the injection rate of the reducing atmosphere liquid into the resin is 2 to 8 BV / h, for example, 2BV / h, 2.5BV / h, 3BV / h, 3.5BV / h, 4BV / h, 4.5BV / h, 5BV / h, 5.5BV / h, 6BV / h, 6.5BV / h, 7BV / h, 7.5BV / h or 8BV / h, etc., but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0035] Under the condition of fixed liquid inlet volume, controlling the injection rate of reducing atmosphere liquid at a slower rate is beneficial to improving the adsorption effect of resin on solution.

[0036] In one embodiment, during the resin adsorption process, when the nickel concentration in the solution produced by the tail column is ≥2 mg / L, the first column is removed to obtain the saturated resin, and a new tail column is added to continue the adsorption.

[0037] As an optional technical solution of the present disclosure, the resin adsorption uses ion exchange resin.

[0038] The ion exchange resin includes a chelating resin, which can be selected from at least one of aminophosphoric acid type, aminocarboxylic acid type, iminodiacetic acid type, phenylhydrazine type, and pyridine methylamine type chelating resins, and can further be selected from aminophosphoric acid type chelating resins.

[0039] In one embodiment, the regeneration ions in the ion exchange resin include any one or a combination of at least two of hydrogen ions, sodium ions, calcium ions or magnesium ions. Typical but non-limiting examples of the combination include a combination of hydrogen ions and sodium ions, a combination of hydrogen ions and calcium ions, a combination of hydrogen ions and magnesium ions, a combination of sodium ions and calcium ions, a combination of sodium ions and magnesium ions, or a combination of magnesium ions and calcium ions.

[0040] In one embodiment, the ion exchange resin is manufactured by polymerization reaction using styrene and polystyrene as raw materials.

[0041] In one embodiment, the ion exchange resin has a three-dimensional network structure and has functional exchange groups.

[0042] As an optional technical solution of the present disclosure, the desorption uses at least three resin columns loaded with the saturated resin in a series structure.

[0043] In one embodiment, the saturated resin is washed with water before desorption to wash away the stock solution in the resin to prevent impurities in the stock solution from entering the desorption liquid (nickel-containing solution) and affecting the quality of the desorption liquid. The washing water in this process can be reused for the acid leaching.

[0044] In one embodiment, during the washing, the rate of injection of water into the saturated resin is 2 to 5 BV / h, for example, 2 BV / h, 2.5 BV / h, 3 BV / h, 3.5 BV / h, 4 BV / h, 4.5 BV / h or 5 BV / h, and the amount used is 1 to 3 BV, for example, 1 BV, 1.2 BV, 1.4 BV, 1.6 BV, 1.8 BV, 2 BV, 2.2 BV, 2.4 BV, 2.6 BV, 2.8 BV or 3 BV, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0045] In one embodiment, the desorption uses an acid solution; the acid solution includes a sulfuric acid solution and / or a hydrochloric acid solution.

[0046] Using sulfuric acid for desorption will produce a nickel sulfate solution, using hydrochloric acid for desorption will produce a nickel chloride solution, and so on. The type and acid composition of the acid solution used for desorption can be selected and changed according to the target product to be obtained.

[0047] In one embodiment, the concentration of the acid solution is 1 to 5 mol / L, for example, 1 mol / L, 1.4 mol / L, 1.8 mol / L, 2.2 mol / L, 2.6 mol / L, 3 mol / L, 3.4 mol / L, 3.8 mol / L, 4.2 mol / L, 4.6 mol / L or 5 mol / L, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0048] The lower the acid concentration in the acid solution during desorption, such as the low sulfuric acid concentration, the lower the nickel sulfate concentration in the obtained desorption solution (nickel-containing solution), and the greater the energy consumption of subsequent evaporation and crystallization.

[0049] In one embodiment, during the desorption, the injection rate of the acid solution into the saturated resin is 0.5 to 2 BV / h, for example, 0.5 BV / h, 0.8 BV / h, 1 BV / h, 1.2 BV / h, 1.4 BV / h, 1.6 BV / h, 1.8 BV / h or 2 BV / h, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0050] In one embodiment, the saturated resin is desorbed and reused as regenerated resin for the resin adsorption.

[0051] In one embodiment, the washed resin obtained after washing the regenerated resin is reused in the resin adsorption, and the washing water is reused in the acid leaching.

[0052] As an optional technical solution of the present disclosure, the method further includes mixing an oxidant and a phosphorus source with the iron-containing solution, reacting the mixture to obtain ferric phosphate and an acid solution.

[0053] In one embodiment, the phosphorus source includes phosphoric acid and / or a soluble phosphate, and the soluble phosphate includes at least one of sodium dihydrogen phosphate, ferric dihydrogen phosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate.

[0054] In one embodiment, the amount of the oxidant used is 1 to 2 times the theoretical amount used to oxidize ferrous iron to ferric iron.

[0055] In one embodiment, the amount of the phosphorus source is 0.8 to 1.5 times the theoretical amount of precipitated ferric phosphate.

[0056] In one embodiment, the reaction time is 0.5 to 12 h, for example, 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, 6 h, 6.5 h, 7 h, 7.5 h, 8 h, 8.5 h, 9 h, 9.5 h, 10 h, 10.5 h, 11 h, 11.5 h or 12 h, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0057] The reaction time can be further selected to be 6 to 8 hours. If the time is insufficient, the yield and purity of ferric phosphate will be affected. If the time is too long, there will be no obvious improvement effect, which is not conducive to improving production efficiency.

[0058] In one embodiment, the acid solution is reused in the acid leaching.

[0059] In one embodiment, the oxidant includes any one of hydrogen peroxide, oxygen, chlorine, hypochlorous acid or nitric acid, or a combination of at least two thereof. Typical but non-limiting examples of the combination include a combination of hydrogen peroxide and oxygen, a combination of hydrogen peroxide and chlorine, a combination of hydrogen peroxide and hypochlorous acid, or a combination of hydrogen peroxide and nitric acid.

[0060] As an optional technical solution of the present disclosure, the method further includes evaporating and crystallizing the nickel-containing solution to obtain a nickel salt.

[0061] As an optional technical solution of the present disclosure, the method includes:

[0062] Using an acid including any one or a combination of at least two of sulfuric acid, hydrochloric acid, nitric acid or phosphoric acid, acid leaching the nickel-ferronickel material for 0.5 to 4 hours, controlling the amount of acid added for the acid leaching to be 1 to 2 times the theoretical reaction amount of nickel and iron in the nickel-ferronickel material, dissolving the nickel and iron to obtain a leachate and a leach residue;

[0063] Using an alkali including any one of sodium hydroxide, sodium carbonate, nickel carbonate, nickel hydroxide, calcium hydroxide or calcium carbonate, or a combination of at least two thereof, the leachate is adjusted to a pH value of 2.5 to 5.5 to remove chromium and aluminum impurities, thereby obtaining a decontaminated liquid and decontaminated slag;

[0064] Using a reducing agent including any one or a combination of at least two of sodium sulfite, potassium iodide, hydroxylamine hydrochloride, thiourea, ethylene glycol, or iron powder, mixing the reducing agent with the impurity removal liquid to reduce iron ions to obtain a reducing atmosphere liquid;

[0065] An ion exchange resin is produced by polymerization reaction using styrene and polystyrene as raw materials. The ion exchange resin has a three-dimensional network structure and functional exchange groups. The regeneration ions contained include any one of hydrogen ions, sodium ions, calcium ions, or magnesium ions, or a combination of at least two. The ion exchange resin is filled into four resin columns in a series structure, with the volume filling amount controlled to be 70% to 90%.

[0066] The reducing atmosphere liquid is subjected to resin adsorption to adsorb nickel ions, and the injection rate of the reducing atmosphere liquid into the resin is controlled to be 2 to 8 BV / h. During the resin adsorption process, when the nickel concentration in the solution produced by the tail column is ≥2 mg / L, the first column is removed to obtain the saturated resin, and a new tail column is added to continue adsorption, and the resulting adsorption residual liquid is an iron-containing solution;

[0067] Three resin columns loaded with the saturated resin are connected in series, washed with water, and the injection rate of water into the saturated resin is controlled to be 2-5 BV / h, and the amount is 1-3 BV; then, a sulfuric acid solution is used for desorption to desorb nickel ions, and the concentration of the sulfuric acid solution is 1-5 mol / L. The injection rate of the sulfuric acid solution into the saturated resin is controlled to be 0.5-2 BV / h, and the amount is 1-2.5 BV to obtain a nickel-containing solution; and the regenerated resin after desorption is reused for the resin adsorption;

[0068] using any one of hydrogen peroxide, oxygen, chlorine, hypochlorous acid, or nitric acid, or a combination of at least two thereof as an oxidant, mixing the oxidant and phosphoric acid with the iron-containing solution, and reacting for 0.5 to 8 hours to obtain iron phosphate and an acid solution, and reusing the acid solution for the acid leaching;

[0069] The nickel-containing solution is evaporated and crystallized to obtain nickel sulfate.

[0070] The ferric phosphate and the evaporated crystallized nickel salt obtained by the preparation method disclosed in the present invention both contain crystal water and can be further subjected to heat treatment to obtain anhydrous products.

[0071] Compared with the existing technical solutions, the present disclosure has at least the following beneficial effects:

[0072] Compared with traditional recovery processes, the method disclosed herein utilizes the high selectivity of resin to separate nickel and iron, and can selectively extract nickel and iron. The method removes chromium and aluminum impurities in the acid leaching solution to within an acceptable range, and uses a reducing agent to maintain the valence of iron ions, thereby avoiding the adsorption of chromium, aluminum, and iron ions during subsequent resin adsorption. After desorption, a nickel-containing solution free of chromium, aluminum, and iron ions can be obtained; the nickel-containing solution can be further processed into a nickel salt product, and the adsorption residual liquid is an iron-containing solution, which can be further processed into an iron phosphate product; the use of resin adsorption in the present disclosure not only enriches the nickel concentration, but also omits the complex impurity removal and purification process. The saturated resin has a regeneration function after desorption and can be recycled, thus greatly saving process flow and reducing recovery costs.

[0073] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] The accompanying drawings are used to provide a further understanding of the technical solution of this article and constitute a part of the specification. Together with the embodiments of this application, they are used to explain the technical solution of this article and do not constitute a limitation on the technical solution of this article.

[0075] FIG1 is a schematic flow diagram of the method for separating and recovering ferronickel from ferronickel material in Example 1. DETAILED DESCRIPTION

[0076] The technical solution of the present disclosure is further illustrated below through specific implementation methods.

[0077] It should be apparent to those skilled in the art that the embodiments are only intended to help understand the present disclosure and should not be considered as specific limitations of the present disclosure.

[0078] Example 1

[0079] This embodiment provides a method for separating and recovering ferronickel from a ferronickel material. The ferronickel material is obtained from a laterite nickel ore recovery process and, calculated by mass fraction, comprises Ni: 9%, Fe: 87%, Co: 0.5%, Cr: 0.15%, Si: 0.2%, and Al: 0.22%. The method flow diagram is shown in FIG1 . The method comprises:

[0080] The nickel-iron material is acid-leached for 2.5 hours using sulfuric acid, wherein the amount of acid added for the acid leaching is controlled to be 1.2 times the theoretical reaction amount of nickel and iron in the nickel-iron material, and the nickel and iron are dissolved to obtain a leachate and a leach residue;

[0081] The leachate is adjusted using nickel hydroxide to adjust the pH value to 4.5 to remove chromium and aluminum impurities, thereby obtaining a decontaminated liquid and decontaminated slag;

[0082] Sodium sulfite and iron powder are used as reducing agents, and the addition amount is controlled to be 25 mmol / L. The reducing agent is mixed with the impurity removal liquid to reduce the iron ions to obtain a reducing atmosphere liquid;

[0083] The ion exchange resin is filled into five resin columns in a series structure, the resin columns have a size of 6cm*20cm, and the volume filling amount of the resin in each resin column is controlled to be 80%; the reducing atmosphere liquid is subjected to resin adsorption to adsorb nickel ions, and the injection rate of the reducing atmosphere liquid into the resin is controlled to be 5BV / h. During the resin adsorption process, when the nickel concentration in the solution produced by the tail column is ≥2mg / L, the first column is removed to obtain the saturated resin, and a new tail column is added to continue adsorption, and the resulting adsorbed residual liquid is an iron-containing solution;

[0084] Three resin columns loaded with the saturated resin are connected in series, washed with water, and the washing water can be reused in the acid leaching, and the injection rate of water into the saturated resin is controlled to be 3BV / h, and the amount is 3BV; then, a sulfuric acid solution is used for desorption to desorb nickel ions, and the concentration of the sulfuric acid solution is 4 mol / L. The injection rate of the sulfuric acid solution into the saturated resin is controlled to be 1BV / h, and the amount is 1.5BV to obtain a nickel-containing solution; the regenerated resin after desorption is washed to obtain a washed resin, which is then reused for the resin adsorption, and the washing water can be reused in the acid leaching;

[0085] Using hydrogen peroxide as an oxidant, mixing the oxidant and phosphoric acid with the iron-containing solution, reacting for 7 hours to obtain iron phosphate and an acid solution, and reusing the acid solution for the acid leaching;

[0086] The nickel-containing solution is evaporated and crystallized to obtain nickel sulfate.

[0087] Example 2

[0088] This embodiment provides a method for separating and recovering ferronickel from a ferronickel material, wherein the ferronickel material is obtained from a laterite nickel ore recovery process and comprises, by mass fraction, 14% Ni, 82% Fe, 0.4% Co, 0.15% Cr, 0.12% Si, and 0.22% Al. The method comprises:

[0089] The nickel-iron material is acid-leached using sulfuric acid, hydrochloric acid, and nitric acid for 1 hour, wherein the amount of acid added for the acid leaching is controlled to be 1.5 times the theoretical reaction amount of nickel and iron in the nickel-iron material, dissolving the nickel and iron to obtain a leachate and a leach residue;

[0090] The leachate is adjusted with sodium carbonate to a pH value of 5.5 to remove chromium and aluminum impurities, thereby obtaining a decontaminated liquid and decontaminated slag;

[0091] Thiourea is used as a reducing agent, and the addition amount is controlled to be 100 mmol / L. The reducing agent is mixed with the impurity removal liquid to reduce the iron ions to obtain a reducing atmosphere liquid;

[0092] Ion exchange resin is filled into four resin columns in a series structure, the resin columns have a size of 6cm*20cm, and the volume filling amount of the resin in each resin column is controlled to be 90%; the reducing atmosphere liquid is subjected to resin adsorption to adsorb nickel ions, and the injection rate of the reducing atmosphere liquid into the resin is controlled to be 8BV / h. During the resin adsorption process, when the nickel concentration in the solution produced by the tail column is ≥2mg / L, the first column is removed to obtain the saturated resin, a new tail column is added, and adsorption is continued, and the resulting adsorbed residual liquid is an iron-containing solution;

[0093] Three resin columns loaded with the saturated resin are connected in series and washed with water. The washing water can be reused in the acid leaching. The injection rate of water into the saturated resin is controlled to be 5BV / h and the amount is 3BV. Sulfuric acid solution is then used for desorption to desorb nickel ions. The concentration of the sulfuric acid solution is 5 mol / L. The injection rate of the sulfuric acid solution into the saturated resin is controlled to be 0.5BV / h and the amount is 1BV to obtain a nickel-containing solution. The regenerated resin after desorption is washed to obtain a washed resin, which is then reused in the resin adsorption. The washing water can be reused in the acid leaching.

[0094] Using hydrogen peroxide and nitric acid as oxidants, mixing the oxidants and phosphoric acid with the iron-containing solution, reacting for 8 hours to obtain iron phosphate and an acid solution, and reusing the acid solution for the acid leaching;

[0095] The nickel-containing solution is evaporated and crystallized to obtain nickel sulfate.

[0096] Example 3

[0097] This embodiment provides a method for separating and recovering ferronickel from a ferronickel material, wherein the ferronickel material is obtained from a laterite nickel ore recovery process and comprises, by mass fraction, 22% Ni, 74% Fe, 0.36% Co, 0.18% Cr, 0.2% Si, and 0.12% Al. The method comprises:

[0098] The nickel-iron material is acid-leached for 4 hours using hydrochloric acid and phosphoric acid, wherein the amount of acid used for acid leaching is controlled to be twice the theoretical reaction amount of nickel and iron in the nickel-iron material, dissolving the nickel and iron to obtain a leachate and a leach residue;

[0099] The leachate is adjusted with sodium hydroxide and calcium hydroxide to a pH value of 2.5 to remove chromium and aluminum impurities, thereby obtaining a decontaminated liquid and decontaminated slag;

[0100] Hydroxylamine hydrochloride and ethylene glycol were used as reducing agents, and the addition amount was controlled to be 5 mmol / L. The reducing agents were mixed with the impurity removal liquid to reduce the iron ions to obtain a reducing atmosphere liquid;

[0101] The ion exchange resin is filled into five resin columns in a series structure, the resin columns have a size of 6cm*20cm, and the volume filling amount of the resin in each resin column is controlled to be 70%; the reducing atmosphere liquid is subjected to resin adsorption to adsorb nickel ions, and the injection rate of the reducing atmosphere liquid into the resin is controlled to be 2BV / h. During the resin adsorption process, when the nickel concentration in the solution produced by the tail column is ≥2mg / L, the first column is removed to obtain the saturated resin, and a new tail column is added to continue adsorption, and the resulting adsorbed residual liquid is an iron-containing solution;

[0102] Three resin columns loaded with the saturated resin are connected in series, washed with water, and the washing water can be reused in the acid leaching, and the injection rate of water into the saturated resin is controlled to be 2BV / h, and the amount is 1BV; then, a sulfuric acid solution is used for desorption to desorb nickel ions, and the concentration of the sulfuric acid solution is 2.5 mol / L. The injection rate of the sulfuric acid solution into the saturated resin is controlled to be 1.5BV / h, and the amount is 2BV to obtain a nickel-containing solution; the regenerated resin after desorption is washed to obtain a washed resin, which is then reused for the resin adsorption, and the washing water can be reused in the acid leaching;

[0103] Using chlorine and oxygen as oxidants, mixing the oxidants and phosphoric acid with the iron-containing solution, reacting for 1 hour to obtain iron phosphate and an acid solution, and reusing the acid solution for acid leaching;

[0104] The nickel-containing solution is evaporated and crystallized to obtain nickel sulfate.

[0105] Example 4

[0106] This embodiment provides a method for separating and recovering ferronickel from ferronickel material. When adjusting the pH value, the method controls the pH value to 2. Except for the above, other conditions are exactly the same as those in Example 1.

[0107] Example 5

[0108] This embodiment provides a method for separating and recovering ferronickel from ferronickel material. When adjusting the pH value, the method controls the pH value to 2.5. Except for the above, other conditions are exactly the same as those in Example 1.

[0109] Example 6

[0110] This embodiment provides a method for separating and recovering ferronickel from ferronickel material. When adjusting the pH value, the method controls the pH value to be 5.5. Except for the above, other conditions are exactly the same as those in Example 1.

[0111] Example 7

[0112] This embodiment provides a method for separating and recovering ferronickel from ferronickel material. When adjusting the pH value, the method controls the pH value to be 6.5. Except for the above, other conditions are exactly the same as those in Example 1.

[0113] Example 8

[0114] This embodiment provides a method for separating and recovering nickel iron from nickel iron material, wherein the method uses potassium iodide as a reducing agent. Except for the above, other conditions are exactly the same as those in Example 1.

[0115] Example 9

[0116] This embodiment provides a method for separating and recovering nickel iron from nickel iron material, wherein the method uses hydroxylamine hydrochloride as a reducing agent. Except for the above, other conditions are exactly the same as those in Example 1.

[0117] Example 10

[0118] This embodiment provides a method for separating and recovering ferronickel from ferronickel material, wherein ethylene glycol is used as a reducing agent. Except for the above, other conditions are exactly the same as those in Example 1.

[0119] Example 11

[0120] This embodiment provides a method for separating and recovering ferronickel from ferronickel material. In the method, the number of resin columns in series structure is adjusted from five to three. Except for the above, other conditions are exactly the same as those in Example 1.

[0121] Example 12

[0122] This embodiment provides a method for separating and recovering ferronickel from ferronickel material. In the method, the number of resin columns in series structure is adjusted from five to four. Except for the above, other conditions are exactly the same as those in Example 1.

[0123] Example 13

[0124] This embodiment provides a method for separating and recovering ferronickel from ferronickel material. In the method, the number of resin columns in series structure is adjusted from five to six. Except for the above, other conditions are exactly the same as those in Example 1.

[0125] Comparative Example 1

[0126] This comparative example provides a method for separating and recovering ferronickel from ferronickel material. The method does not perform value adjustment, and directly uses the acid leaching solution as the leaching solution for subsequent steps. Except for the above, other conditions are exactly the same as those in Example 1.

[0127] Comparative Example 2

[0128] This comparative example provides a method for separating and recovering ferronickel from ferronickel material. The method does not use a reducing agent and directly uses the impurity removal liquid as a reducing atmosphere liquid for subsequent steps. Except for the above, other conditions are exactly the same as those in Example 1.

[0129] Comparative Example 3

[0130] This comparative example provides a method for separating and recovering ferronickel from ferronickel material. The method does not perform resin adsorption, and directly uses the impurity removal liquid as the iron-containing solution for subsequent steps to generate ferric phosphate. The filtrate after precipitation of the ferric phosphate is then evaporated and crystallized to obtain nickel sulfate.

[0131] The purity of the ferric phosphate and nickel sulfate products obtained in the examples and comparative examples was tested and the recovery rates of iron and nickel were calculated as follows:

[0132] Recovery rate calculation formula:

[0133] Where: R—nickel / iron recovery rate, %; w0—nickel / iron content in nickel-iron material, %; w e —Nickel / iron content in nickel sulfate / ferric phosphate product, %; m0—Nickel-iron material mass used for leaching, g; m e —Mass of nickel sulfate / ferric phosphate product obtained, g.

[0134] Product purity calculation formula:

[0135] Where: P—purity of nickel sulfate / ferric phosphate product, %; w e —Nickel / iron content in the nickel sulfate / ferric phosphate product, %; M1—Relative atomic mass of nickel / iron, g / mol; M2—Relative molecular mass of nickel sulfate hexahydrate / ferric phosphate dihydrate, g / mol. In the experiment, nickel concentration was determined using an inductively coupled plasma optical emission spectrometer (ICAP-7200, Thermo Fisher Scientific, USA), and iron concentration was determined using potassium dichromate titration.

[0136] The results are recorded in Table 1.

[0137] Table 1

[0138] As can be seen from Table 1:

[0139] Example 1 has the best effect, with the purity of nickel sulfate and ferric phosphate products reaching more than 99%, the nickel recovery rate reaching 98.8%, and the iron recovery rate reaching 95.2%. The nickel loss is mainly entrained in the impurity removal slag, and the iron loss is partly in the liquid after the ferric phosphate is precipitated in addition to the impurity removal slag; in Example 2, since the leaching time is 1 hour, there is still some nickel and iron in the leaching slag, resulting in a decrease in the nickel and iron recovery rates compared with Example 1; in Example 3, the reaction time for the ferric phosphate precipitation stage is 1 hour, and the insufficient reaction time results in a low iron recovery rate.

[0140] The pH of Example 4 was 2, and the impurity removal effect was poor, which affected the purity of the nickel sulfate and ferric phosphate products. The pH of Example 5 was 2.5, and the chromium and aluminum impurities in the leachate were only partially precipitated, which also affected the product purity. As the adjusted pH value increased, the impurities could be basically completely removed, but the loss of the main metal in the leachate also increased. Therefore, the recovery rates of Examples 6 and 7 decreased to varying degrees with different pH values.

[0141] In Examples 8-10, different reducing agents were used before resin adsorption, and a small amount of ferric iron was reduced to ferrous iron.

[0142] From the results of Examples 11-13, it can be seen that the preferred standard for the number of resin columns connected in series in the present disclosure needs to ensure that the number of series connections can ensure that the nickel content in the adsorption tail liquid does not exceed the standard and the first column is adsorbed as saturated as possible. Generally speaking, the higher the nickel content in the nickel-iron liquid, the more resin columns are preferably connected in series; if the nickel concentration in the solution is high and there are fewer adsorption columns in series, the adsorption efficiency is low, which will increase the loss of the main metal during the adsorption process and affect the recovery rate. In Examples 11 and 12, due to insufficient adsorption columns in series, the efficiency of resin extraction of nickel is low, which affects the recovery rate of nickel and iron; Example 13 uses 6 columns in series to achieve the same effect as Example 1.

[0143] In Comparative Example 1, no adjustment was performed, resulting in an increase in product impurities, affecting the purity; in Comparative Example 2, no reducing agent was used, resulting in the resin adsorbing trivalent iron, affecting the purity of nickel sulfate and the iron recovery rate; in Comparative Example 3, iron phosphate was directly precipitated without resin nickel extraction, which affected the purity of iron phosphate and the recovery rate of nickel sulfate.

Claims

1. A method for separating and recovering nickel and iron from nickel-iron materials, comprising the following steps: Leach the nickel-iron materials with acid to dissolve nickel and iron, obtaining a leachate and a leach residue; Adjust the value of the leachate to remove chromium and aluminum impurities, obtaining a purified solution and a purification residue; Mix a reducing agent with the purified solution to reduce iron ions, obtaining a reducing atmosphere solution; Perform resin adsorption on the reducing atmosphere solution to adsorb nickel ions, obtaining a saturated resin and an iron-containing solution; Desorb the saturated resin to desorb nickel ions, obtaining a nickel-containing solution.

2. The method according to claim 1, wherein, The acid used in the acid leaching includes any one or a combination of at least two of sulfuric acid, hydrochloric acid, nitric acid, or phosphoric acid.

3. The method according to claim 1 or 2, wherein, The addition amount of the acid used in the acid leaching is 1 to 2 times the theoretical reaction amount of nickel and iron in the nickel-iron materials.

4. The method according to any one of claims 1-3, wherein, The pH value range for the value adjustment is 2.5 to 6.

5.

5. The method according to any one of claims 1-4, wherein, The base used for the value adjustment includes any one or a combination of at least two of sodium hydroxide, sodium carbonate, nickel carbonate, nickel hydroxide, calcium hydroxide, or calcium carbonate.

6. The method according to any one of claims 1-5, wherein, The dosage of the reducing agent is 5 to 100 mmol / L.

7. The method according to any one of claims 1-6, wherein, The reducing agent includes any one or a combination of at least two of sodium sulfite, potassium iodide, hydroxylamine hydrochloride, thiourea, ethylene glycol, or iron powder.

8. The method according to any one of claims 1-7, wherein, The resin adsorption uses at least four resin columns in a series structure.

9. The method according to any one of claims 1-8, wherein, The feeding rate of the reducing atmosphere solution into the resin is 2 to 8 BV / h.

10. The method according to any one of claims 1-9, wherein, During the resin adsorption process, when the concentration of nickel in the solution produced by the tail column is ≥ 2 mg / L, remove the head column to obtain the saturated resin, add a new tail column, and continue the adsorption.

11. The method according to any one of claims 1-10, wherein, The resin adsorption uses ion exchange resin.

12. The method according to claim 11, wherein, The ion exchange resin includes chelating resin, preferably at least one of amino phosphoric acid type, amino carboxylic acid type, iminodiacetic acid type, phenylhydrazine type, or pyridine methylamine type chelating resin.

13. The method according to any one of claims 1-12, wherein, The desorption uses at least three resin columns loaded with the saturated resin in a series structure; Optionally, the saturated resin is washed with water before desorption; Optionally, the acid used for desorption includes hydrochloric acid and / or sulfuric acid; Optionally, the concentration of the acid used for desorption is 1 to 5 mol / L; Optionally, the regenerated resin obtained after desorbing the saturated resin is reused for the resin adsorption.

14. The method according to any one of claims 1-13, wherein, The method further includes mixing an oxidant and a phosphorus source with the iron-containing solution and reacting them to obtain iron phosphate and an acid solution; Optionally, the reaction time is 0.5 to 12 h; Optionally, the acid solution is recycled for the acid leaching; Optionally, the oxidant includes any one or a combination of at least two of hydrogen peroxide, oxygen, chlorine, hypochlorous acid, or nitric acid.

15. The method according to any one of claims 1-14, wherein, the method further includes evaporating and crystallizing the nickel-containing solution to obtain a nickel salt.

16. The method according to any one of claims 1-15, wherein, the method includes: using an acid including any one or a combination of at least two of sulfuric acid, hydrochloric acid, nitric acid, or phosphoric acid to perform acid leaching on the nickel-iron material for 0.5 to 4 h, controlling the addition amount of the acid used in the acid leaching to be 1 to 2 times the theoretical reaction amount of nickel and iron in the nickel-iron material, dissolving nickel and iron to obtain a leaching solution and a leaching residue; using a base including any one or a combination of at least two of sodium hydroxide, sodium carbonate, nickel carbonate, nickel hydroxide, calcium hydroxide, or calcium carbonate to adjust the value of the leaching solution, adjusting the pH value to 2.5 to 5.5, removing chromium and aluminum impurities to obtain a purified solution and a purification residue; using a reducing agent including any one or a combination of at least two of sodium sulfite, potassium iodide, hydroxylamine hydrochloride, thiourea, ethylene glycol, or iron powder, mixing the reducing agent with the purified solution, controlling the dosage of the reducing agent to be 5 to 100 mmol / L, reducing iron ions to obtain a reducing atmosphere solution; using an ion exchange resin manufactured by a polymerization reaction using styrene and polystyrene as raw materials, the ion exchange resin having a three-dimensional network structure and having functional exchange groups, and the regeneration ions contained therein including any one or a combination of at least two of hydrogen ions, sodium ions, calcium ions, or magnesium ions; filling the ion exchange resin in four resin columns in series, controlling the volume filling amount to be 70% to 90%; performing resin adsorption on the reducing atmosphere solution to adsorb nickel ions, controlling the feeding rate of the reducing atmosphere solution into the resin to be 2 to 8 BV / h, and during the resin adsorption process, when the concentration of nickel in the solution produced by the tail column ≥ 2 mg / L, removing the head column to obtain the saturated resin, adding a new tail column, and continuing the adsorption, and the obtained adsorption residual solution is an iron-containing solution; connecting three resin columns loaded with the saturated resin in series, washing with water, controlling the feeding rate of water into the saturated resin to be 2 to 5 BV / h, and the dosage to be 1 to 3 BV; then performing desorption with a sulfuric acid solution to desorb nickel ions, the concentration of the sulfuric acid solution being 1 to 5 mol / L, controlling the feeding rate of the sulfuric acid solution into the saturated resin to be 0.5 to 2 BV / h, and the dosage to be 1 to 2.5 BV, to obtain a nickel-containing solution; recycling the regenerated resin after desorption for the resin adsorption; Using any one or a combination of at least two of hydrogen peroxide, oxygen, chlorine, hypochlorous acid or nitric acid as an oxidant, mixing the oxidant and phosphoric acid with the iron-containing solution, and reacting for 0.5 to 12 h to obtain iron phosphate and an acid solution, and recycling the acid solution to the acid leaching; Evaporating and crystallizing the nickel-containing solution to obtain nickel sulfate.

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