Method for resource recovery of hematite

Abstract

The application provides a resourceful treatment method of hematite, comprising the following steps: a first leaching process, after the hematite is subjected to first acid leaching, first leaching residues and first leaching solution containing ferric ions and nickel ions are obtained through solid-liquid separation; a second leaching process, after the first leaching residues are subjected to second acid leaching, second leaching residues containing noble metals and second leaching solution containing ferric ions and nickel ions are obtained through solid-liquid separation; wherein the acid amount used in the first leaching process is less than the theoretical amount of acid required for leaching all the iron in the hematite, and the acid amount used in the second leaching process is greater than or equal to the theoretical amount of acid required for leaching all the iron in the first leaching residues. The resourceful treatment method provided in the application embodiment can control the acid amount required for leaching in stages, which is conducive to reducing acid consumption and regulating the pH value of the leaching solution, thereby reducing the cost, and at the same time, the iron, nickel and other types of elements in the hematite can be fully leached and separated.

Description

Technical Field

[0001] This application relates to the field of hematite processing technology, and in particular to a method for the resource-based processing of hematite. Background Technology

[0002] Hematite's main component is Fe2O3, and it may also contain nickel, precious metals, and other elements. Due to its high iron content, hematite is commonly used as a raw material for refining iron and other elements.

[0003] Currently, common hematite processing techniques include high-concentration acid-enhanced leaching, which directly extracts iron and other elements from the hematite. However, high-concentration acid-enhanced leaching often requires a large amount of acid, resulting in a high residual acid content in the leachate. Subsequent pH adjustments to the leachate are necessary to meet usage requirements, increasing acid consumption, process complexity, and overall cost. Summary of the Invention

[0004] This application provides a method for the resource utilization of hematite, which can fully leach various elements such as iron from hematite, and can also reduce acid consumption and lower costs.

[0005] This application provides a method for the resource utilization of hematite, comprising the following steps: a first leaching step, wherein the hematite is subjected to a first acid leaching, and then solid-liquid separation is performed to obtain a first leaching residue and a first leaching solution containing ferric ions and nickel ions; a second leaching step, wherein the first leaching residue is subjected to a second acid leaching, and then solid-liquid separation is performed to obtain a second leaching residue containing precious metals and a second leaching solution containing ferric ions and nickel ions; wherein the amount of acid used in the first leaching step is less than the theoretical amount of acid required to leach all the iron in the hematite, and the amount of acid used in the second leaching step is greater than or equal to the theoretical amount of acid required to leach all the iron in the first leaching residue.

[0006] The resource recovery method provided in this application involves leaching hematite with acid in a first leaching process, controlling the amount of acid used to be less than the theoretical amount required to leach all the iron in the hematite. This allows some iron, nickel, and other potentially contained elements in the hematite to be leached, resulting in a first leaching solution containing ferric ions and nickel ions. The remaining iron and nickel in the hematite enter the first leaching residue. Then, in a second leaching process, acid is added to leach the first leaching residue, controlling the amount of acid used to be greater than or equal to the theoretical amount required to leach all the iron in the first leaching residue. This allows as much of the iron, nickel, and other potentially contained elements in the first leaching residue as possible to be leached, resulting in a second leaching solution containing ferric ions and nickel ions. Precious metals and other elements that are difficult to leach from the hematite are enriched in the second leaching residue, thereby achieving the separation of iron, nickel, and precious metals from the hematite.

[0007] Therefore, according to the resource recovery method provided in the embodiments of this application, by leaching hematite in stages, the amount of acid required for leaching can be controlled in stages, which helps to reduce acid consumption and regulate the pH value of the leachate, thereby reducing costs. At the same time, it can fully leach and separate various elements such as iron and nickel from the hematite.

[0008] In some embodiments of this application, the amount of acid used in the first leaching process is 0.4 to 0.9 times the theoretical amount of acid required to leach all the iron from the hematite.

[0009] In some embodiments of this application, the amount of acid used in the second leaching process is 1.0 to 2.0 times the theoretical amount of acid required to leach all the iron from the first leaching residue.

[0010] In some embodiments of this application, the first leaching process includes: a pretreatment process, in which hematite is crushed and / or subjected to a first pulping process to obtain pretreated material; and a first acid leaching process, in which the pretreated material is subjected to a first acid leaching process, followed by solid-liquid separation to obtain a first leaching residue and a first leaching solution containing ferric ions and nickel ions.

[0011] In some embodiments of this application, the particle size of the crushed hematite is less than or equal to 80 mesh, preferably less than or equal to 150 mesh.

[0012] In some embodiments of this application, the first pulping process includes mixing water with hematite to form a pulp.

[0013] In some embodiments of this application, the acid used in the first acid leaching process includes at least one of sulfuric acid and hydrochloric acid, preferably sulfuric acid.

[0014] In some embodiments of this application, the acid leaching temperature of the first acid leaching process is 90°C-100°C.

[0015] In some embodiments of this application, the pickling time of the first pickling process is 8h-10h.

[0016] In some embodiments of this application, the pH value of the first leachate is 0-0.5.

[0017] In some embodiments of this application, the second leaching process includes: an intermediate treatment process, in which the first leaching residue is washed and / or subjected to a second pulping process to obtain an intermediate treated material; and a second acid leaching process, in which the intermediate treated material is subjected to a second acid leaching process, and then subjected to solid-liquid separation to obtain a second leaching residue containing precious metals and a second leaching solution containing ferric ions and nickel ions.

[0018] In some embodiments of this application, the washing process includes washing the first leaching residue with water to obtain a first washing liquid and a first washing residue, wherein the first washing residue is used as the intermediate processing material or is used as the intermediate processing material after undergoing the second pulping treatment.

[0019] In some embodiments of this application, the intermediate processing step further includes mixing the first washing solution with the first leachate to dilute the first leachate.

[0020] In some embodiments of this application, the volume of water used in the washing process is 30%-40% of the volume of the first leachate.

[0021] In some embodiments of this application, the second pulping process includes mixing water with the first leaching residue to form a pulp.

[0022] In some embodiments of this application, the acid used in the second acid leaching process is at least one of sulfuric acid and hydrochloric acid, preferably sulfuric acid.

[0023] In some embodiments of this application, the acid leaching temperature of the second acid leaching process is 70°C-100°C.

[0024] In some embodiments of this application, the pickling time of the second pickling process is 4h-8h.

[0025] In some embodiments of this application, the resource recovery method further includes a recycling process, in which the second leachate is recycled back to the first leaching process, such that the second leachate is mixed with the hematite for a first acid leaching.

[0026] In some embodiments of this application, the resource recovery method further includes a washing step, in which the second leaching residue is washed to obtain a second washing liquid and a second washing residue, and the second washing liquid is recycled back to the first leaching step, so that the second washing liquid is mixed with the hematite for a first acid leaching.

[0027] In some embodiments of this application, the washing process uses water washing.

[0028] In some embodiments of this application, the volume of water used in the washing process is 30%-40% of the volume of the second leachate.

[0029] In some embodiments of this application, the resource recovery method further includes a reduction and purification step, wherein the first leachate is mixed and reacted with a nickel intermediate, and then a purified liquid containing ferrous ions and nickel ions is obtained by solid-liquid separation.

[0030] In some embodiments of this application, the amount of nickel intermediate used is 1.2 to 1.8 times the theoretical amount required to completely reduce the ferric ions in the first leachate.

[0031] In some embodiments of this application, the mixing reaction temperature is 60°C-70°C.

[0032] In some embodiments of this application, the mixing reaction time is 2h-4h.

[0033] In some embodiments of this application, the pH value of the purification solution is 1.0-2.5.

[0034] In some embodiments of this application, the nickel intermediate includes nickel matte.

[0035] In some embodiments of this application, the nickel matte has a particle size of less than or equal to 100 mesh, preferably less than or equal to 200 mesh.

[0036] Additional technical solutions and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0038] Figure 1 A flowchart illustrating a method for resource recovery of hematite provided in some embodiments of this application;

[0039] Figure 2 A flowchart illustrating a method for resource recovery of hematite provided in some embodiments of this application;

[0040] Figure 3 A flowchart illustrating a method for resource recovery of hematite provided in some embodiments of this application;

[0041] Figure 4 A flowchart illustrating a method for resource recovery of hematite provided in some embodiments of this application;

[0042] Figure 5 A flowchart illustrating a method for resource recovery of hematite provided in some embodiments of this application;

[0043] Figure 6 A flowchart illustrating a method for resource recovery of hematite provided in some embodiments of this application. Detailed Implementation

[0044] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0045] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0046] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0047] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0048] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0049] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0050] In this application, hematite refers to an iron oxide mineral, the main component of which is Fe2O3. Exemplarily, in some embodiments, the source of hematite may be naturally occurring iron minerals directly from nature, or it may be hematite slag produced during the leaching and nickel extraction process using high-grade nickel matte as raw material.

[0051] Solid-liquid separation refers to the process of separating solids and liquids. The method for solid-liquid separation can be any method well known in the art for separating solids and liquids. For example, in some embodiments, solid-liquid separation can be performed by centrifugation, tilting, filtration, etc., and the solid-liquid separation described herein can be performed with reference to the above methods.

[0052] Precious metals refer to metallic elements such as gold, silver, and platinum group metals.

[0053] The theoretical amount of acid used refers to the amount of Fe2O3 obtained by leaching out all of it. 3+ The required amount of acid, and the reactions that occur during the leaching process include: Fe₂O₃ + 6H₂O + =2Fe 3+ +3H₂O, the theoretical amount of acid required can be calculated using this formula. Exemplarily, in some embodiments, the theoretical amount of acid required to leach all the iron from hematite or the first leaching residue refers to the amount of Fe₂O₃ obtained by leaching all the Fe₂O₃ from the hematite or the first leaching residue. 3+ The required amount of acid.

[0054] Pure water generally refers to water with an electrical conductivity of less than or equal to 10 μS / cm, total organic carbon of less than or equal to 20 mg / L, metal ions (Na, K, Ca, Mg, etc.) of less than or equal to 1000 μg / L, and other ions (Cl, NO3-) of less than or equal to 1000 μg / L. - Water with a concentration of less than or equal to 2000 μg / L.

[0055] Nickel intermediates refer to intermediate products produced during the nickel smelting process, which contain a certain amount of elements such as iron. For example, in some embodiments, the nickel intermediate can be nickel matte, which includes low-grade nickel matte and / or high-grade nickel matte.

[0056] Dry basis refers to the method of expressing the content of a certain component in a wet solid or wet gas based on a unit mass of anhydrous solid or dry gas.

[0057] Reference Figure 1 As shown in the embodiment of this application, a method for the resource utilization of hematite is provided, including the following steps:

[0058] S100, First leaching process: After the hematite is subjected to a first acid leaching, the first leaching residue and the first leaching solution containing ferric ions and nickel ions are obtained by solid-liquid separation.

[0059] S200, Second leaching process: After the first leaching residue undergoes a second acid leaching, solid-liquid separation is performed to obtain a second leaching residue containing precious metals and a second leaching solution containing ferric ions and nickel ions; wherein, the amount of acid used in the first leaching process is less than the theoretical amount of acid required to leach all the iron in the hematite, and the amount of acid used in the second leaching process is greater than or equal to the theoretical amount of acid required to leach all the iron in the first leaching residue.

[0060] The resource recovery method provided in this application involves leaching hematite with acid in a first leaching process, controlling the amount of acid used to be less than the theoretical amount required to leach all the iron in the hematite. This allows some iron, nickel, and other potentially contained elements in the hematite to be leached, resulting in a first leaching solution containing ferric ions and nickel ions. The remaining iron and nickel in the hematite enter the first leaching residue. Then, in a second leaching process, acid is added to leach the first leaching residue, controlling the amount of acid used to be greater than or equal to the theoretical amount required to leach all the iron in the first leaching residue. This allows as much of the iron, nickel, and other potentially contained elements in the first leaching residue as possible to be leached, resulting in a second leaching solution containing ferric ions and nickel ions. Precious metals and other elements that are difficult to leach from the hematite are enriched in the second leaching residue, thereby achieving the separation of iron, nickel, and precious metals from the hematite.

[0061] Therefore, according to the resource recovery method provided in the embodiments of this application, by leaching hematite in stages, the amount of acid required for leaching can be controlled in stages, which helps to reduce acid consumption and regulate the pH value of the leachate, thereby reducing costs. At the same time, it can fully leach and separate various elements such as iron and nickel from the hematite.

[0062] In some embodiments, the amount of acid used in the first leaching step is 0.4 to 0.9 times the theoretical amount of acid required to leach all the iron from the hematite. If the amount of acid used in the first leaching step is too large, the acid utilization rate will be low, the acid consumption will be large, and the cost will be high; if the amount of acid used in the first leaching step is too small, it will be difficult to meet the requirements for the initial leaching of hematite, affecting the leaching of elements such as iron and nickel. In the embodiments of this application, controlling the amount of acid used in the first leaching step within the above-mentioned suitable range can not only improve the acid utilization rate, but also effectively leach some of the iron, nickel, and other elements that may be contained in the hematite, thereby facilitating the separation of elements such as iron, nickel, and precious metals.

[0063] In some embodiments, the amount of acid used in the second leaching step is 1.0 to 2.0 times the theoretical amount of acid required to leach all the iron from the first leaching residue. If the amount of acid used in the second leaching step is too large, the acid consumption will be high and the residual acid content in the second leaching solution will be high. The pH value of the second leaching solution will then need to be neutralized and adjusted to meet usage requirements, resulting in higher costs. If the amount of acid used in the second leaching step is too small, the leaching of elements such as iron and nickel in the hematite will be insufficient. In the embodiments of this application, controlling the amount of acid used in the second leaching step within the above-mentioned suitable range can save acid, reduce costs, and fully leach some of the iron and nickel elements in the hematite, thereby facilitating the separation of products containing higher purity iron, nickel, and precious metals from the hematite.

[0064] Reference Figure 2 As shown, in some embodiments, the first leaching step includes:

[0065] S110, Pre-processing step, which involves crushing and / or first pulping of hematite to obtain pre-processed material.

[0066] S120, First acid leaching process: After the pre-treated material is subjected to first acid leaching, the first leaching residue and the first leaching solution containing ferric ions and nickel ions are obtained by solid-liquid separation.

[0067] In the embodiments of this application, crushing the hematite before the first acid leaching can reduce the particle size of the hematite. The first pulping treatment of the hematite can initially disperse the hematite into a slurry, which is conducive to the acid and hematite being mixed as evenly as possible, thereby improving the leaching effect.

[0068] For example, in some embodiments, the crushing process may be to convert hematite into powder with smaller particle size by methods such as stirring, extrusion, and grinding.

[0069] In some embodiments, the particle size of the crushed hematite is less than or equal to 80 mesh, preferably less than or equal to 150 mesh, which is beneficial for the full leaching of the hematite.

[0070] In some embodiments, the first pulping process includes mixing water with hematite to prepare a pulp. Exemplarily, the first pulping process may be preparing a pulp by mixing hematite with pure water.

[0071] In the first acid leaching process, the leaching rates of ferric ions and nickel ions in the first leaching solution can be adjusted to be within the range of 40%-90%, preferably 60%-90%, by adjusting appropriate process parameters. This can improve the utilization rate of acid and reduce leaching costs, while also improving the utilization rate of acid in the first leaching process.

[0072] In some embodiments, the acid used in the first acid leaching process includes at least one of sulfuric acid and hydrochloric acid, preferably sulfuric acid. Sulfuric acid and hydrochloric acid can effectively leach out various elements contained in hematite and minimize the introduction of anionic impurities, thus reducing impurity removal costs.

[0073] Specifically, taking 98% sulfuric acid used in the first acid leaching process as an example, the acid leaching reaction includes: Fe2O3 + 6H+ + =2Fe 3+ +3H₂O. If the amount of acid used in the first leaching process is to be controlled to be 0.4-0.9 times the theoretical amount required to leach all the iron from the hematite, then the amount of sulfuric acid used can be calculated using the following formula: V(98% sulfuric acid) / m 3 =m(Fe) / t÷56×1.5×(0.4-0.9)×98÷98%÷1.84.

[0074] In some embodiments, the acid leaching temperature of the first acid leaching process is 90℃-100℃. In some embodiments, the acid leaching time of the first acid leaching process is 8h-10h. The acid leaching temperature and time in this embodiment are within the above-mentioned suitable range, which can not only make full use of the acid added in the first acid leaching process, but also effectively leach out elements such as iron and nickel contained in hematite.

[0075] In some embodiments, the pH value of the first leachate is 0-0.5. If the pH value of the first leachate is too high, it indicates that the amount of acid used for leaching may be insufficient, resulting in incomplete leaching; if the pH value of the first leachate is too low, it indicates that the amount of acid used for leaching is excessive, leading to high acid consumption. This embodiment controls the amount of acid used for leaching to ensure that the pH value of the first leachate is within a suitable range, which is beneficial for complete leaching and can minimize acid consumption and reduce costs.

[0076] Reference Figure 3 As shown, in some embodiments, the second leaching step includes:

[0077] S210, Intermediate processing step, where the first leaching residue is washed and / or pulped to obtain intermediate processed material.

[0078] S220, Second acid leaching process: After the intermediate-treated material undergoes a second acid leaching, solid-liquid separation is performed to obtain a second leaching residue containing precious metals and a second leaching solution containing ferric ions and nickel ions.

[0079] In this embodiment, washing the first leaching residue before the second acid leaching removes soluble metal ions such as iron and nickel ions carried within it. This prevents these ions from entering the second acid leaching system and inhibiting the acid leaching reaction, thus facilitating the full leaching of various elements contained in the first leaching residue. Furthermore, performing a second slurry treatment on the first leaching residue before the second acid leaching disperses it into a slurry, which helps to ensure thorough mixing of the acid and the first leaching residue, thereby improving the leaching effect.

[0080] In some embodiments, the washing process includes washing the first leaching residue with water to obtain a first washing liquid and a first washing residue, wherein the first washing residue is used as an intermediate processing material or is used as an intermediate processing material after undergoing a second pulping treatment. Exemplarily, the washing process may involve washing the first leaching residue with pure water.

[0081] Since the first washing solution may contain small amounts of soluble metal ions such as iron and nickel ions, it can be mixed with the first leaching solution to fully recover the washed-off soluble metal ions. In some embodiments, the intermediate processing step further includes mixing the first washing solution with the first leaching solution to dilute the first leaching solution. In this embodiment, mixing the first washing solution with the first leaching solution not only dilutes the first leaching solution to facilitate further processing to obtain a product containing elements such as iron and nickel, but also fully recovers soluble metal ions such as iron and nickel ions to further improve the leaching rate of metal elements such as nickel and iron.

[0082] In some embodiments, the volume of water used for washing is 30%-40% of the volume of the first leachate. If the amount of water used for washing is too small, the washing will be insufficient; if the amount of water is too large, the mixture of the first washing solution and the first leachate will result in a low concentration of elements such as iron and nickel in the first leachate, which is not conducive to subsequent treatment of the first leachate to obtain a product containing elements such as iron and nickel.

[0083] In some embodiments, the second pulping process includes mixing water with the first leaching residue to form a pulp. Exemplarily, the second pulping process may involve mixing the first leaching residue with pure water to obtain a pulp.

[0084] In some embodiments, the acid used in the second acid leaching process is at least one of sulfuric acid and hydrochloric acid, preferably sulfuric acid. Sulfuric acid and hydrochloric acid can fully leach out various elements contained in the first leaching residue and can minimize the introduction of anionic impurities, thus reducing the cost of impurity removal.

[0085] In some embodiments, the acid leaching temperature of the second acid leaching process is 70℃-100℃. In some embodiments, the acid leaching time of the second acid leaching process is 4h-8h. In this embodiment, the acid leaching temperature and time are within the above-mentioned suitable range, which can not only make full use of the acid added in the second acid leaching process, but also effectively leach out elements such as iron and nickel contained in the first leaching residue.

[0086] Reference Figure 4 As shown, in some embodiments, the resource recovery method further includes:

[0087] S300, the recycling process, recycles the second leaching solution back to the first leaching process, so that the second leaching solution is mixed with hematite for the first acid leaching.

[0088] In this embodiment, hematite is first subjected to a first acid leaching, followed by a second acid leaching of the first leaching residue. The total leaching rate of iron and nickel can reach over 99%. Furthermore, the second leaching solution is recycled back to the first leaching process. On the one hand, the small amount of acid contained in the second leaching solution can be used as the base acid for the first acid leaching, thereby improving acid utilization, reducing acid consumption, and lowering costs. On the other hand, the iron, nickel, and other elements contained in the second leaching solution can be concentrated in the first leaching solution through the first leaching process, so as to facilitate the subsequent centralized treatment of the first leaching solution to obtain a product containing iron, nickel, and other elements.

[0089] Reference Figure 5 As shown, in some embodiments, the resource recovery method further includes:

[0090] S400, Washing process: The second leaching residue is washed to obtain a second washing solution and a second washing residue. The second washing solution is recycled back to the first leaching process, so that the second washing solution is mixed with hematite for the first acid leaching.

[0091] In this embodiment, washing the second leaching residue removes small amounts of soluble metal ions such as iron and nickel ions, resulting in a second leaching residue containing higher purity precious metals, which is beneficial for subsequent precious metal recovery. Furthermore, recycling the second washing solution back into the first leaching process allows the soluble metal ions such as iron and nickel contained in the second washing solution to accumulate in the first leaching solution, facilitating subsequent centralized treatment to obtain a product containing elements such as iron and nickel.

[0092] In some embodiments, the washing process uses water washing. Exemplarily, the washing process includes washing the second leaching residue with pure water.

[0093] In some embodiments, the volume of water used in the washing process is 30%-40% of the volume of the second leachate. This allows for the thorough removal of soluble metal ions carried by the second leachate residue and reduces the amount of water consumed in the washing process.

[0094] Reference Figure 6 As shown, in some embodiments, the resource recovery method further includes:

[0095] S500, reduction and purification process: after the first leaching solution is mixed and reacted with nickel intermediate, a purified solution containing ferrous ions and nickel ions is obtained by solid-liquid separation.

[0096] In this embodiment, a first leaching solution containing ferric and nickel ions is mixed and reacted with a nickel intermediate. The ferric ions are reduced to ferrous ions by reacting with reducing agents such as elemental iron contained in the nickel intermediate, thus obtaining a purified solution containing ferrous and nickel ions. This purified solution can be used in industrial applications requiring the supply of ferrous and nickel ions. Specifically, when sulfuric acid is used in the first and second acid leaching processes, the resulting purified solution is a ferrous nickel sulfate solution. This ferrous nickel sulfate solution can be used in the battery field, for example, as a raw material for preparing precursors for battery cathode materials.

[0097] In some embodiments, the amount of nickel intermediate used is 1.2 to 1.8 times the theoretical amount required to completely reduce ferric ions in the first leaching solution. If the amount of nickel intermediate used is too large, it results in waste; if the amount is too small, it is difficult to achieve sufficient reduction. In the embodiments of this application, the amount of nickel intermediate is controlled within the above-mentioned suitable range, which can both fully reduce ferric ions and minimize the consumption of nickel intermediate, thereby reducing costs.

[0098] In some embodiments, the mixing reaction temperature of the first leaching solution and the nickel intermediate is 60°C-70°C. In some embodiments, the mixing reaction time is 2-4 hours. In some embodiments, the pH value of the purified solution is 1.0-2.5. In some embodiments, the particle size of the nickel intermediate is less than or equal to 100 mesh, preferably less than or equal to 200 mesh. By controlling the reaction conditions of the mixing reaction within the above-mentioned suitable range, it is beneficial to fully convert ferric ions into ferrous ions, thereby obtaining a purified solution containing ferrous and nickel ions that meets the requirements.

[0099] For example, in some embodiments, the nickel intermediate can be low-grade nickel matte. Low-grade nickel matte, as an intermediate in the nickel smelting process, mainly consists of nickel, iron sulfides, and nickel-iron alloys, with extremely low impurity content, thus avoiding the introduction of excessive impurities during the reduction process. After the first leaching solution is mixed and reacted with the low-grade nickel matte, the elemental iron contained in the low-grade nickel matte can reduce the Fe in the first leaching solution. 3+ It also increases the concentration of ferrous ions, and the dissolution of low-grade nickel matte consumes H+. +This process generates nickel ions to increase the nickel ion concentration. Simultaneously, low-grade nickel matte can displace other impurity ions in the first leachate, such as copper and chromium ions, and form precipitates, thereby removing impurities such as Cu and Cr. This allows for the extraction and conversion of high-value ferrous nickel sulfate solution from hematite, and also extracts ferric nickel from the low-grade nickel matte, which is beneficial for obtaining a higher purity ferrous nickel sulfate solution.

[0100] Specifically, taking nickel intermediates such as low-grade nickel matte as an example, the mixing reaction includes: Fe + 2Fe 3+ =3Fe 2+ If the amount of low-grade nickel matte is to be controlled to be 1.2 to 1.8 times the theoretical amount required to reduce all ferric ions in the first leachate to ferrous ions, then the amount of low-grade nickel matte can be calculated using the following formula: Low-grade nickel matte mass m (kg) = Fe content of the first leachate (g / L) × Volume of the first leachate (m³) 3 )÷2×(1.2-1.8)÷Fe content of low nickel matte (%).

[0101] The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents and raw materials used in the embodiments are commercially available or synthesized by conventional methods, as are the instruments used in the embodiments.

[0102] The composition of hematite and low-grade nickel matte used in the following examples and comparative examples is shown in Table 1 below.

[0103] Table 1. Composition of hematite and low-grade nickel matte

[0104]

[0105]

[0106] In the following examples and comparative examples, the leaching rate and slag rate are calculated using the following methods:

[0107] The iron leaching rate of the first acid leaching process = the mass of iron in the first leaching solution / the mass of iron in the hematite.

[0108] The total iron leaching rate of the first and second acid leaching solutions = the sum of the mass of iron in the first and second leaching solutions / the mass of iron in the hematite.

[0109] Nickel leaching rate in the first acid leaching process = mass of nickel in the first leaching solution / mass of nickel in hematite;

[0110] The total nickel leaching rate of the first and second acid leaching solutions = the sum of the mass of nickel in the first and second leaching solutions / the mass of nickel in the hematite.

[0111] The residue ratio of the first leaching residue (dry basis) = dry basis mass of the first leaching residue / dry basis mass of hematite.

[0112] Total slag ratio of the first and second acid leaching (dry basis) = dry basis mass of the second leaching residue / dry basis mass of hematite.

[0113] Example 1

[0114] This embodiment provides a method for the resource utilization of hematite, including the following steps:

[0115] In the pretreatment process, hematite slag and low-grade nickel matte are placed separately in a vertical mill to crush and grind the materials, obtaining hematite powder (150 mesh) and low-grade nickel matte powder (100 mesh) for later use. 12m³ of [material name missing] is added to the first leaching tank. 3 Pure water was used as the base water, and 3 tons of dry hematite powder were added and slurryed for 15 minutes.

[0116] In the first acid leaching process, after pulping, the first leaching tank begins to heat up and 0.77m is added. 3 The first acid leaching was performed using 98% concentrated sulfuric acid. The amount of acid added was 0.4 times the theoretical amount required to leach all the iron from the hematite. The leaching reaction temperature was set at 95℃, and the reaction was carried out for 8 hours. After the reaction, the residue and the first leachate with a pH of 0.43 were obtained by pressure filtration. The residue rate (dry basis) of the first acid leaching process was 50.22%, and the leaching rates of Fe and Ni were 41.17% and 46.72%, respectively.

[0117] In the intermediate processing step, 4.5m is added to the first leaching residue. 3 The residue is washed online with pure water, and the filtrate (washed liquid) is added to the first leachate. The filter residue is then sent to the second leachate tank. 3.85m³ of [unspecified substance] is added to the second leachate tank. 3 Use pure water as the base water, add filter residue (moisture content 30%), and slurry for 15 minutes.

[0118] In the second acid leaching process, after pulping, the second leaching tank begins to heat up and 1.93m³ of solution is added. 3 The second acid leaching was carried out with 98% concentrated sulfuric acid. The amount of acid added was twice the theoretical amount required to leach all the iron from the first leaching residue. The leaching reaction temperature was set at 75℃ and the reaction was carried out for 4 hours. After the reaction was completed, the residue and the second leachate were obtained by pressure filtration.

[0119] In the recycling process, the second leachate is recycled back to be mixed with hematite to make a pulp and then subjected to the first acid leaching.

[0120] In the washing process, the second leaching residue is washed to obtain a second washing solution and a second washing residue. The second washing solution is recycled back to the first leaching process, allowing it to be mixed with hematite for the first acid leaching. 2.7 m³ of [acid leaching solution] is added to the second leaching residue. 3 The residue is washed online with pure water. The filtrate (washed liquid) is then combined with the second leaching solution and reused to mix with hematite for pulping and the first acid leaching. The filter residue (precious metal enrichment residue) is packaged and temporarily stored for further recovery and extraction of precious metals. The total residue ratio of the first and second acid leaching is 0.85% (dry basis), and the total leaching rates of Fe and Ni are 99.27% ​​and 99.79%, respectively.

[0121] In the reduction and purification process, 2170 kg of low-grade nickel matte powder was added to the first leaching solution. The amount of low-grade nickel matte powder added was 1.4 times the theoretical amount required to completely reduce the ferric ions in the first leaching solution. The reaction temperature was controlled at 65℃, and the reaction time was 3 hours. After the reaction, the solution was filtered to obtain a purified solution with a pH of 1.16. The composition of the purified solution (ferrous nickel sulfate solution) is shown in Table 2.

[0122] Example 2

[0123] This embodiment provides a method for the resource utilization of hematite, including the following steps:

[0124] In the pretreatment process, hematite slag and low-grade nickel matte are placed separately in a vertical mill to crush and grind the materials, obtaining hematite powder (120 mesh) and low-grade nickel matte powder (150 mesh) for later use. 12m³ of [material name missing] is added to the first leaching tank. 3 Bottom water (0.4m) 3 Pure water + 11.6m 3 The second leachate (from Example 1) was mixed with 3 tons of dry hematite powder and slurried for 15 minutes.

[0125] In the first acid leaching process, after pulping, the first leaching tank begins to heat up and 1.74m³ of solution is added. 3 The first acid leaching was performed using 98% concentrated sulfuric acid. The amount of acid added was 0.9 times the theoretical amount required to leach all the iron from the hematite. The leaching reaction temperature was set at 95℃, and the reaction was carried out for 8 hours. After the reaction, the residue and the first leachate with a pH of 0.09 were obtained by pressure filtration. The residue rate (dry basis) of the first acid leaching process was 9.89%, and the leaching rates of Fe and Ni were 88.66% and 89.85%, respectively.

[0126] In the intermediate processing step, 4.5m is added to the first leaching residue. 3 The residue is washed online with pure water, and the filtrate (washed liquid) is added to the first leachate. The filter residue is then sent to the second leachate tank. 0.85m³ of [amount missing] is added to the second leachate tank. 3 Use pure water as the base water, add filter residue (moisture content 30%), and slurry for 15 minutes.

[0127] In the second acid leaching process, after pulping, the second leaching tank begins to heat up and 0.38m³ of solution is added. 3 The second acid leaching was carried out with 98% concentrated sulfuric acid. The amount of acid added was 1.2 times the theoretical amount of acid required to leach all the iron from the first leaching residue. The leaching reaction temperature was set at 95℃ and the reaction was carried out for 8 hours. After the reaction was completed, the second leaching residue and the second leaching solution were obtained by pressure filtration.

[0128] In the recycling process, the second leachate is recycled back to be mixed with hematite to make a pulp and then subjected to the first acid leaching.

[0129] In the washing process, the second leaching residue is washed to obtain a second washing solution and a second washing residue. The second washing solution is recycled back to the first leaching process, allowing it to be mixed with hematite for the first acid leaching. 0.6 m³ of [acid leaching solution] is added to the second leaching residue. 3 The residue is washed online with pure water. The filtrate (washed liquid) is then combined with the second leaching solution and reused to mix with hematite for pulping and the first acid leaching. The filter residue (precious metal enrichment residue) is packaged and temporarily stored for further recovery and extraction of precious metals. The total residue ratio of the first and second acid leaching is 0.98% (dry basis), and the total leaching rates of Fe and Ni are 99.13% and 98.86%, respectively.

[0130] In the reduction and purification process, 2480 kg of low-grade nickel matte powder was added to the first leachate. The amount of low-grade nickel matte powder added was 1.6 times the theoretical amount required to completely reduce the ferric ions in the first leachate. The reaction temperature was controlled at 65℃, and the reaction time was 3 hours. After the reaction, the solution was filtered to obtain a purified solution with a pH of 1.75. The composition of the purified solution (ferrous nickel sulfate solution) is shown in Table 2.

[0131] Example 3

[0132] This embodiment provides a method for the resource utilization of hematite, including the following steps:

[0133] In the pretreatment process, hematite slag and low-grade nickel matte are placed separately in a vertical mill to crush and grind the materials, obtaining hematite powder (80 mesh) and low-grade nickel matte powder (200 mesh) for later use. 24m³ of [material name missing] is added to the first leaching tank. 3 Bottom water (0.8m) 3 Pure water + 23.2m 3 The second leachate (from Example 1) was mixed with 6 tons of dry hematite powder and pulped for 15 minutes.

[0134] In the first acid leaching process, after pulping, the first leaching tank begins to heat up and 2.7m³ of solution is added. 3The first acid leaching was performed using 98% concentrated sulfuric acid. The amount of acid added was 0.7 times the theoretical amount required to leach all the iron from the hematite. The leaching reaction temperature was set at 90℃, and the reaction was carried out for 9 hours. After the reaction, the residue and the first leachate with a pH of 0.25 were obtained by pressure filtration. The residue ratio (dry basis) of the first acid leaching process was 8.77%, and the leaching rates of Fe and Ni were 68.21% and 71.85%, respectively.

[0135] In the intermediate processing step, 9m is added to the first leaching residue. 3 The residue is washed online with pure water, and the filtrate (washed liquid) is added to the first leachate. The filter residue is then sent to the second leachate tank. 1.7 m³ of [unspecified substance] is added to the second leachate tank. 3 Use pure water as the base water, add filter residue (moisture content 30%), and slurry for 15 minutes.

[0136] In the second acid leaching process, after pulping, the second leaching tank begins to heat up and 1.74m³ of solution is added. 3 The second acid leaching was carried out with 98% concentrated sulfuric acid. The amount of acid added was 1.5 times the theoretical amount of acid required to leach all the iron from the first leaching residue. The leaching reaction temperature was set at 85℃ and the reaction was carried out for 6 hours. After the reaction was completed, the second leaching residue and the second leaching solution were obtained by pressure filtration.

[0137] In the recycling process, the second leachate is recycled back to be mixed with hematite to make a pulp and then subjected to the first acid leaching.

[0138] In the washing process, the second leaching residue is washed to obtain a second washing solution and a second washing residue. The second washing solution is recycled back to the first leaching process, allowing it to be mixed with hematite for the first acid leaching. 1.2 m³ of [acid leaching solution] is added to the second leaching residue. 3 The residue is washed online with pure water. The filtrate (washed liquid) is then combined with the second leaching solution and reused to mix with hematite for pulping and the first acid leaching. The filter residue (precious metal enrichment residue) is packaged and temporarily stored for further recovery and extraction of precious metals. The total residue ratio of the first and second acid leaching is 0.81% (dry basis), and the total leaching rates of Fe and Ni are 99.52% and 99.49%, respectively.

[0139] In the reduction and purification process, 5580 kg of low-grade nickel matte powder was added to the first leaching solution. The amount of low-grade nickel matte powder added was 1.8 times the theoretical amount required to completely reduce the ferric ions in the first leaching solution. The reaction temperature was controlled at 70℃, and the reaction time was 4 hours. After the reaction, the solution was filtered to obtain a purified solution with a pH of 2.38. The composition of the purified solution (ferrous nickel sulfate solution) is shown in Table 2.

[0140] Example 4

[0141] This embodiment provides a method for the resource utilization of hematite, including the following steps:

[0142] In the pretreatment process, hematite slag and low-grade nickel matte are placed separately in a vertical mill to crush and grind the materials, obtaining hematite powder (200 mesh) and low-grade nickel matte powder (300 mesh) for later use. 12m³ of [material name missing] is added to the first leaching tank. 3 Bottom water (0.4m) 3 Pure water + 11.6m 3 The second leachate (from Example 1) was mixed with 3 tons of dry hematite powder and slurried for 15 minutes.

[0143] In the first acid leaching process, after pulping, the first leaching tank begins to heat up and 1.16m³ of solution is added. 3 The first acid leaching was performed using 98% concentrated sulfuric acid. The amount of acid added was 0.6 times the theoretical amount required to leach all the iron from the hematite. The leaching reaction temperature was set at 98℃, and the reaction was carried out for 10 hours. After the reaction, the residue and the first leaching solution with a pH of 0.32 were obtained by pressure filtration. The residue ratio (dry basis) of the first acid leaching process was 11.26%, and the leaching rates of Fe and Ni were 56.84% and 65.53%, respectively.

[0144] In the intermediate processing step, 4.5m is added to the first leaching residue. 3 The residue is washed online with pure water, and the filtrate (washed liquid) is added to the first leachate. The filter residue is then sent to the second leachate tank. 0.85m³ of [amount missing] is added to the second leachate tank. 3 Use pure water as the base water, add filter residue (moisture content 30%), and slurry for 15 minutes.

[0145] In the second acid leaching process, after pulping, the second leaching tank begins to heat up and 1.31m³ of solution is added. 3 The second acid leaching was carried out with 98% concentrated sulfuric acid. The amount of acid added was 1.7 times the theoretical amount of acid required to leach all the iron from the first leaching residue. The leaching reaction temperature was set at 70℃ and the reaction was carried out for 6 hours. After the reaction was completed, the second leaching residue and the second leaching solution were obtained by pressure filtration.

[0146] In the recycling process, the second leachate is recycled back to be mixed with hematite to make a pulp and then subjected to the first acid leaching.

[0147] In the washing process, the second leaching residue is washed to obtain a second washing solution and a second washing residue. The second washing solution is recycled back to the first leaching process, allowing it to be mixed with hematite for the first acid leaching. 0.6 m³ of [acid leaching solution] is added to the second leaching residue. 3 The residue is washed online with pure water. The filtrate (washed liquid) is then combined with the second leaching solution and reused to mix with hematite for pulping and the first acid leaching. The filter residue (precious metal enrichment residue) is packaged and temporarily stored for further recovery and extraction of precious metals. The total residue ratio of the first and second acid leaching is 0.75% (dry basis), and the total leaching rates of Fe and Ni are 99.68% and 99.52%, respectively.

[0148] In the reduction and purification process, 1860 kg of low-grade nickel matte powder was added to the first leaching solution. The amount of low-grade nickel matte powder added was 1.2 times the theoretical amount required to completely reduce the ferric ions in the first leaching solution. The reaction temperature was controlled at 60℃, and the reaction time was 2 hours. After the reaction, the solution was filtered to obtain a purified solution with a pH of 1.05. The composition of the purified solution (ferrous nickel sulfate solution) is shown in Table 2.

[0149] Comparative Example 1

[0150] The difference from Example 1 is that the leaching uses a single leaching stage and a different reducing agent, specifically including the following steps:

[0151] In the pretreatment process, 12m³ of solution is added to the first leaching tank. 3 Pure water was used as the base water, and 3 tons of dry hematite powder were added and slurryed for 15 minutes.

[0152] In the acid leaching process, after pulping, the first leaching tank begins to heat up and 3.47m³ of solvent is added. 3 Acid leaching was performed using 98% concentrated sulfuric acid. The amount of acid added was 1.8 times the theoretical amount required to leach all the iron from the hematite. The leaching reaction temperature was set at 95℃, and the reaction was carried out for 8 hours. After the reaction was completed, the first leaching residue and a leachate with a pH of -0.95 (high residual acid) were obtained by pressure filtration. The Fe content of the leachate was 130.37 g / L, and the Ni content was 13.22 g / L.

[0153] In the washing process, the leaching residue is washed to obtain washing solution and washing residue. The washing solution is recycled back to the first leaching process, where it is mixed with hematite for acid leaching. The washing residue (precious metal enrichment residue) is packaged and temporarily stored for further recovery and extraction of precious metals. The total residue ratio is 1.15% (dry basis), and the total leaching rates of Fe and Ni are 97.14% and 99.66%, respectively.

[0154] In the reduction and purification process, the first leachate was transferred to a purification tank and diluted with pure water at a volume ratio of 1:1. After stirring for 15 minutes, 1.01 t of manganese powder (99.7% purity, the amount added being 1.1 times the theoretical amount of manganese powder required to completely reduce the ferric ions in the first leachate) was added. After the manganese powder was added, the reaction was carried out at room temperature for 2 hours. After the reaction, the solution was filtered to obtain a purified solution with a pH of 0.96. The composition of the purified solution is shown in Table 2.

[0155] Table 2. Composition of the purified liquid obtained in each embodiment and comparative example

[0156] Example 1 72.65 7.45 0.005 0.029 0.054 Example 2 92.62 10.41 0.002 0.025 0.035 Example 3 90.48 10.65 0.0005 0.015 0.02 Example 4 85.95 9.36 0.03 0.03 0.08 Comparative Example 1 60.13 6.47 0.004 0.0003 0.031

[0157] Referring to Tables 1 and 2, it can be seen from Examples 1 and 2 that, using the resource recovery method provided in this application, the recovery rates of iron and nickel in hematite can both reach over 99%, and precious metals in hematite can be effectively separated, with the total slag rate of leaching being less than 1%. Furthermore, by further processing the leachate, a purified solution containing ferrous and nickel ions can be obtained, which can be directly used as a raw material for producing battery cathode material precursors. In Comparative Example 1, hematite was treated under different reaction conditions than in the examples of this application, and the resulting purified solution had a significantly lower ferrous content than that of Examples 1-4, and the nickel content was also lower than that of Examples 1-4.

[0158] As can be seen, the embodiments of this application can selectively separate soluble metal elements such as iron and nickel and precious metals contained in hematite through two acid leaching processes, thereby realizing the resource utilization of hematite. Moreover, the auxiliary materials used in the resource utilization treatment method of this application are only acid and water, with low acid consumption, low treatment cost, and no wastewater or waste residue generated, which has good application prospects.

[0159] The technical features described above can be combined arbitrarily. Although not all possible combinations of these technical features are described, any combination of these technical features should be considered to be covered by this specification, provided that such combination does not contain contradictions.

[0160] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for the resource utilization of hematite, characterized in that, Includes the following steps: In the first leaching process, after the hematite undergoes a first acid leaching, solid-liquid separation is performed to obtain the first leaching residue and the first leaching solution containing ferric ions and nickel ions. In the second leaching process, the first leaching residue is subjected to a second acid leaching, and then solid-liquid separation is performed to obtain a second leaching residue containing precious metals and a second leaching solution containing ferric ions and nickel ions. The amount of acid used in the first leaching process is 0.4 to 0.9 times the theoretical amount of acid required to leach all the iron from the hematite. The amount of acid used in the second leaching process is 1.0 to 2.0 times the theoretical amount of acid required to leach all the iron from the first leaching residue.

2. The method for resource utilization of hematite according to claim 1, characterized in that, The first leaching process includes: The pre-processing step involves crushing and / or first pulping of hematite to obtain the pre-processed material. In the first acid leaching process, the pretreated material is subjected to a first acid leaching, followed by solid-liquid separation to obtain a first leaching residue and a first leaching solution containing ferric ions and nickel ions.

3. The method for resource utilization of hematite according to claim 2, characterized in that, The particle size of the crushed hematite is less than or equal to 80 mesh.

4. The resource utilization method for hematite according to claim 3, characterized in that, The particle size of the crushed hematite is less than or equal to 150 mesh.

5. The method for resource utilization of hematite according to claim 3, characterized in that, The method includes one or more of the following: (1) The first pulping process includes mixing water and hematite to form a pulp; (2) The acid used in the first acid leaching process includes at least one of sulfuric acid and hydrochloric acid; (3) The acid leaching temperature of the first acid leaching process is 90℃-100℃; (4) The pickling time of the first pickling process is 8h-10h; (5) The pH value of the first leachate is 0-0.

5.

6. The method for resource utilization of hematite according to claim 5, characterized in that, The acid used in the first acid leaching process is sulfuric acid.

7. The method for resource utilization of hematite according to claim 1, characterized in that, The second leaching process includes: The intermediate processing step involves washing the first leaching residue and / or performing a second pulping process to obtain the intermediate processed material. In the second acid leaching process, the intermediate-treated material is subjected to a second acid leaching, followed by solid-liquid separation to obtain a second leaching residue containing precious metals and a second leaching solution containing ferric ions and nickel ions.

8. The method for resource utilization of hematite according to claim 7, characterized in that, The washing process includes washing the first leaching residue with water to obtain a first washing liquid and a first washing residue, wherein the first washing residue is used as the intermediate processing material or is used as the intermediate processing material after undergoing the second pulping treatment.

9. The method for resource utilization of hematite according to claim 8, characterized in that, The method includes one or more of the following: (1) The intermediate processing step further includes mixing the first washing liquid with the first leachate to dilute the first leachate; (2) The volume of water used in the washing process is 30%-40% of the volume of the first leachate.

10. The method for resource utilization of hematite according to claim 7, characterized in that, The second pulping process includes mixing water with the first leaching residue to form a pulp.

11. The method for resource utilization of hematite according to claim 10, characterized in that, The method includes one or more of the following: (1) The acid used in the second acid leaching process is at least one of sulfuric acid and hydrochloric acid; (2) The acid leaching temperature of the second acid leaching process is 70℃-100℃; (3) The acid leaching time for the second acid leaching process is 4h-8h.

12. The method for resource utilization of hematite according to claim 11, characterized in that, The acid used in the second acid leaching process is sulfuric acid.

13. The method for resource utilization of hematite according to claim 1, characterized in that, The resource recovery method further includes: In the recycling process, the second leaching solution is recycled back to the first leaching process, so that the second leaching solution is mixed with the hematite for the first acid leaching.

14. The method for resource utilization of hematite according to claim 1, characterized in that, The resource recovery method further includes: In the washing process, the second leaching residue is washed to obtain a second washing solution and a second washing residue. The second washing solution is recycled back to the first leaching process, so that the second washing solution is mixed with the hematite for a first acid leaching.

15. The method for resource utilization of hematite according to claim 14, characterized in that, The method includes one or more of the following: (1) The washing process uses water washing; (2) The volume of water used in the washing process is 30%-40% of the volume of the second leachate.

16. The method for resource recovery of hematite according to any one of claims 1-15, characterized in that, The resource recovery method further includes: In the reduction and purification process, the first leaching solution is mixed and reacted with nickel intermediate, and then a purified solution containing ferrous ions and nickel ions is obtained through solid-liquid separation.

17. The method for resource utilization of hematite according to claim 16, characterized in that, The method includes one or more of the following: (1) The amount of nickel intermediate used is 1.2 to 1.8 times the theoretical amount required to completely reduce the ferric ions in the first leachate; (2) The mixing reaction temperature is 60℃-70℃; (3) The mixing reaction time is 2h-4h; (4) The pH value of the purified solution is 1.0~2.5; (5) The nickel intermediates include nickel matte; (6) The particle size of the nickel matte is less than or equal to 100 mesh.

18. The method for resource utilization of hematite according to claim 17, characterized in that, The nickel matte has a particle size of less than or equal to 200 mesh.

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