Method for resource utilization of laterite-nickel ore leaching residues

Abstract

The invention provides a method for resource utilization of laterite-nickel ore leaching residues, which comprises the following steps: mixing the laterite-nickel ore leaching residues with a first reducing agent, and carrying out reduction roasting treatment to obtain a sintered material; mixing the sintered material, a second reducing agent, a fluxing agent and a vulcanizing agent, and carrying out reduction smelting reaction to obtain a smelted material; and the smelted material is subjected to layered recovery, slag is obtained on the upper layer, a chromium-sulfur phase is obtained on the middle layer, and iron ingots are obtained on the lower layer. According to the method, the difficult problem of efficient separation of chromium and iron in the laterite-nickel slag is solved in a manner of pre-reduction and sulfur-adding reduction smelting, the chromium-sulfur phase and the slag capable of being used for building materials are synchronously recovered, the difficulty of sulfur in an iron ore concentrate process and the interference of chromium in smelting reduction are avoided, and the obtained product is high in additional value and low in cost. Solid wastes with environmental risks are converted into products with economic values, the development direction of circular economy and green metallurgy is met, and the method is a novel iron resource recovery thought.

Description

Technical Field

[0001] This invention belongs to the field of resource recycling technology and relates to a method for the resource utilization of laterite nickel ore leaching residue. Background Technology

[0002] After high-pressure acid leaching (HPAL) of laterite nickel ore, elements such as iron, chromium, magnesium, and silicon are enriched in the leaching residue in the form of sulfates or stable compounds. Current treatment methods primarily involve stockpiling or landfilling, which pose environmental risks (such as heavy metal leaching), land occupation, and resource waste. The mainstream resource recovery approach in existing technologies is the preparation of iron concentrate, but iron concentrate is not price-competitive. There are also attempts to use it in building materials (such as cement ingredients), but this method has low added value and cannot recover valuable metal elements. The leaching residue usually also contains chromium. Currently, a molten reduction method is used to separate iron from other impurities in the leaching residue, but because iron and chromium have similar properties, Fe-Cr separation is often difficult, resulting in ineffective Cr recovery.

[0003] CN117403057A discloses a method for treating acid leaching residue from laterite nickel ore. The method involves mixing and pressing the acid leaching residue, conditioning material, flux, and reducing agent, followed by roasting and magnetic separation to obtain iron concentrate and tailings. The iron concentrate has a total iron content of 83% and an iron recovery rate of 88%. The magnetic separation tailings are then mixed with active material and activator material and ground to obtain active material. However, the obtained iron concentrate still requires smelting for further recovery, making the process too lengthy. Furthermore, the chromium element in the leaching residue mainly exists as impurities in the iron concentrate, failing to achieve complete component recovery.

[0004] CN114774685A discloses a method for treating hydrometallurgical slag from limonite-type lateritic nickel ore. The method uses high-volatile lignite as a reducing agent and heating fuel, and performs magnetic roasting in a rotary kiln. The magnetically separated iron concentrate can be used as raw material for sintering and ironmaking, with an iron content reaching 64.3%. However, the iron concentrate recovered by this method has a low grade and low added value.

[0005] The above-described processing method is difficult to achieve full component recovery, and the resulting iron concentrate has low purity, resulting in poor practical application effects. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for the resource utilization of laterite nickel ore leaching slag. This invention solves the problem of efficient separation of chromium and iron in laterite nickel ore slag by first pre-reduction and then sulfur reduction smelting, and simultaneously recovers the chromium-sulfur phase and slag that can be used in building materials. It avoids the difficulties of sulfur in iron concentrate processes and the interference of chromium in smelting reduction, resulting in products with high added value. It transforms environmentally risky solid waste into economically valuable products, which is in line with the development direction of circular economy and green metallurgy. It is a new approach to iron resource recovery.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] This invention provides a method for the resource utilization of laterite nickel ore leaching residue, the method comprising the following steps:

[0009] The laterite nickel ore leaching residue is mixed with the first reducing agent and then subjected to reduction roasting to obtain sinter.

[0010] The sintering material, the second reducing agent, the fluxing agent and the vulcanizing agent are mixed and then subjected to a reduction smelting reaction to obtain the smelted material;

[0011] The smelting material is subjected to full component recovery to obtain slag, chromium-sulfur phase and iron ingot.

[0012] This invention uses a first reducing agent to remove impurities from laterite nickel ore, followed by reduction roasting to pre-reduce some of the trivalent iron to divalent iron or elemental iron and remove crystal water. This significantly increases the reactivity of the material in subsequent smelting, lowers the melting point of the sinter, and reduces the required smelting temperature and time. Then, a sulfiding agent is creatively introduced during the melting reaction. Utilizing the selective trapping effect of sulfur on chromium, an independent and easily separable chromium-sulfur phase with a density between molten iron and slag is generated. This solves the industry problem of difficult chromium recovery and pollution from laterite nickel ore leaching slag, allowing chromium to be separated from iron for independent recovery. The discharged chromium-sulfur phase is an excellent raw material for chromium extraction and can be sent to stainless steel plants or chromium salt plants to produce ferrochrome alloys or chemical-grade sodium chromate through oxidative roasting, with a value far exceeding that of waste disposal. The resulting slag can be used in cement building materials, achieving resource recycling and reuse.

[0013] This invention introduces a flux during the melting process to adjust the basicity, viscosity, and melting point of the slag, ensuring good stratification and separation of iron, chromium sulfides, and slag, while maintaining the slag's fluidity for easy discharge and subsequent utilization. The full-component recovery described in this invention involves stratified recovery of the material, yielding slag in the upper layer, chromium sulfide in the middle layer, and iron ingots in the lower layer.

[0014] Preferably, the laterite nickel ore leaching residue is pre-dried.

[0015] The present invention pre-dries the leaching residue of laterite nickel ore, which can remove excess moisture and reduce subsequent energy consumption.

[0016] Preferably, the drying temperature is 100℃~150℃, for example: 100℃, 110℃, 120℃, 130℃, 140℃ or 150℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0017] Preferably, the drying time is 5h to 10h, for example: 5h, 6h, 7h, 8h, 9h or 10h, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0018] Preferably, the first reducing agent includes any one or a combination of at least two of anthracite, lignite, or semi-coke. Typical but non-limiting combinations include combinations of anthracite and semi-coke, combinations of anthracite and lignite, or combinations of lignite and semi-coke.

[0019] This invention uses inexpensive anthracite, lignite, or semi-coke as a reducing agent for reduction roasting, which can remove crystal water and sulfur components, laying a good foundation for the subsequent reduction smelting to prepare qualified raw materials.

[0020] Preferably, the mass ratio of the laterite nickel ore leaching residue to the first reducing agent is (5~15):100, for example: 5:100, 8:100, 10:100, 12:100 or 15:100, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0021] Preferably, the temperature of the reduction calcination treatment is 900℃~1100℃, for example: 900℃, 950℃, 1000℃, 1050℃ or 1100℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0022] Preferably, the reduction calcination time is 2h to 4h, for example: 2h, 2.5h, 3h, 3.5h or 4h, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0023] Preferably, the atmosphere of the reduction roasting treatment includes nitrogen and / or argon.

[0024] Preferably, the second reducing agent comprises coke.

[0025] Preferably, the mass ratio of the sintering material to the second reducing agent is 100:(10~15), for example: 100:10, 100:11, 100:12, 100:13, 100:14 or 100:15, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0026] Preferably, the flux comprises calcium carbonate.

[0027] Preferably, the mass ratio of the sintering material to the flux is 100:(10~20), for example: 100:10, 100:12, 100:15, 100:18 or 100:20, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0028] Preferably, the sulfiding agent comprises pyrite (FeS2).

[0029] Preferably, the mass ratio of the sintering material to the vulcanizing agent is 100:(3~8), for example: 100:3, 100:4, 100:5, 100:6, 100:7 or 100:8, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0030] Preferably, the temperature of the reduction smelting reaction is 1550℃~1650℃, for example: 1550℃, 1580℃, 1600℃, 1620℃ or 1650℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0031] Preferably, the reduction smelting reaction time is 15 min to 45 min, for example: 15 min, 20 min, 30 min, 40 min or 45 min, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0032] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) This invention solves the problem of efficient separation of chromium and iron in laterite nickel slag by pre-reduction followed by sulfur reduction smelting, and simultaneously recovers the chromium-sulfur phase and the slag that can be used in building materials. It avoids the difficulties of sulfur in the iron concentrate process and the interference of chromium in the molten reduction. The product has high added value and transforms solid waste with environmental risks into products with economic value. It is in line with the development direction of circular economy and green metallurgy and is a new iron resource recycling idea.

[0035] (2) The method for resource utilization of laterite nickel ore leaching residue described in this invention can recover iron ingots with a grade of over 97.85% and an iron recovery rate of over 94.2%. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the process flow for the resource utilization of laterite nickel ore leaching residue provided in an embodiment of the present invention. Detailed Implementation

[0037] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0038] The "range" disclosed in this invention can be defined in the form of 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 the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning 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 specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" 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" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0039] In this invention, "a combination of at least two" refers to a quantity greater than or equal to two, unless otherwise specified. For example, "any combination of one or at least two" means one or more or more items. It can be understood that when referring to "a combination of at least two," it refers to any suitable combination of multiple items, that is, a combination of "at least two" items carried out in a manner that does not conflict with and enables the implementation of this invention.

[0040] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0041] The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0042] Those skilled in the art will understand that the order in which the steps are written in the methods of the various embodiments does not imply a strict execution order. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), meaning that step (c) can 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.

[0043] In this invention, open-ended technical features or solutions described using terms such as "comprising" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or exclude additional members. This can be considered as providing both technical features or solutions where "A is composed of a1, a2, and a3" or "A is selected from a1, a2, and a3," and technical features or solutions where "A includes not only a1, a2, and a3, but also other members."

[0044] In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" represents a group consisting of A, B, and "a combination of A and B". "Containing A and / or B" can mean "containing A, containing B, and containing A and B", or "containing A, containing B, or containing A and B", and can be appropriately understood according to the context.

[0045] In this invention, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on the quantity.

[0046] In this invention, "optional" means that something is optional, that is, it refers to any one of the two parallel solutions of "having" or "not having". If there are multiple "optional" options in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, then each "optional" option is independent.

[0047] In this invention, "room temperature" generally refers to 4℃~35℃, and can refer to 20℃±5℃. In some embodiments of this invention, room temperature refers to 20℃~30℃.

[0048] The main component composition of the laterite nickel ore leaching residue used in the embodiments and comparative examples of this invention is shown in Table 1 below:

[0049] Table 1

[0050]

[0051] Example 1

[0052] This embodiment provides a method for the resource utilization of laterite nickel ore leaching residue, and the process flow diagram of the method is shown below. Figure 1 As shown, the method includes the following steps:

[0053] Take 1 kg of laterite nickel ore raw material, put it in an oven at 120℃ and dry it for 8 hours. Then take it out and mix the laterite nickel ore leaching residue with anthracite coal at a mass ratio of 100:10. Then reduce and roast it at 1000℃ for 3 hours under nitrogen atmosphere to obtain sintered material.

[0054] Sintered material, coke, calcium carbonate and pyrite were mixed in a mass ratio of 100:12:15:5 and then smelted at 1650℃ for 30 minutes to obtain smelted material.

[0055] The smelted material is subjected to stratified recovery, with slag obtained in the upper layer, chromium-sulfur phase obtained in the middle layer, and iron ingot obtained in the lower layer.

[0056] Example 2

[0057] This embodiment provides a method for the resource utilization of laterite nickel ore leaching residue, and the process flow diagram of the method is shown below. Figure 1 As shown, the method includes the following steps:

[0058] Take 1 kg of laterite nickel ore raw material, put it in an oven at 150℃ and dry it for 5 hours. Then take it out and mix the laterite nickel ore leaching residue with lignite at a mass ratio of 100:15. Then reduce and roast it at 900℃ for 4 hours under nitrogen atmosphere to obtain sintered material.

[0059] Sintered material, coke, calcium carbonate and pyrite were mixed in a mass ratio of 100:15:20:8 and then smelted at 1550℃ for 45 minutes to obtain smelted material.

[0060] The smelted material is subjected to stratified recovery, with slag obtained in the upper layer, chromium-sulfur phase obtained in the middle layer, and iron ingot obtained in the lower layer.

[0061] Example 3

[0062] This embodiment provides a method for the resource utilization of laterite nickel ore leaching residue, and the process flow diagram of the method is shown below. Figure 1 As shown, the method includes the following steps:

[0063] Take 1 kg of laterite nickel ore raw material, put it in an oven at 100℃ and dry it for 10 hours. Then take it out and mix the laterite nickel ore leaching residue with semi-coke at a mass ratio of 100:10. Then reduce and roast it at 900℃ under nitrogen atmosphere for 4 hours to obtain sintered material.

[0064] Sintered material, coke, calcium carbonate and pyrite were mixed in a mass ratio of 100:15:20:3 and then smelted at 1600℃ for 30 minutes to obtain smelted material.

[0065] The smelted material is subjected to stratified recovery, with slag obtained in the upper layer, chromium-sulfur phase obtained in the middle layer, and iron ingot obtained in the lower layer.

[0066] Example 4

[0067] The only difference between this embodiment and Embodiment 1 is that the mass ratio of sintering material to coke is 100:20; all other conditions and parameters are exactly the same as in Embodiment 1.

[0068] Example 5

[0069] The only difference between this embodiment and Embodiment 1 is that the mass ratio of sintered material to coke is 100:8, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0070] Example 6

[0071] The only difference between this embodiment and Embodiment 1 is that the mass ratio of sintering material to calcium carbonate is 100:30; all other conditions and parameters are exactly the same as in Embodiment 1.

[0072] Example 7

[0073] The only difference between this embodiment and Embodiment 1 is that the mass ratio of sintering material to calcium carbonate is 100:5, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0074] Example 8

[0075] The only difference between this embodiment and Embodiment 1 is that the mass ratio of sinter to pyrite is 100:10; all other conditions and parameters are exactly the same as in Embodiment 1.

[0076] Example 9

[0077] The only difference between this embodiment and Embodiment 1 is that the mass ratio of sinter to pyrite is 100:1, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0078] Comparative Example 1

[0079] The only difference between this comparative example and Example 1 is that the reduction roasting treatment is not performed; all other conditions and parameters are exactly the same as in Example 1.

[0080] Comparative Example 2

[0081] The only difference between this comparative example and Example 1 is that pyrite is not added; all other conditions and parameters are exactly the same as in Example 1.

[0082] Comparative Example 3

[0083] The only difference between this comparative example and Example 1 is that calcium carbonate is not added; all other conditions and parameters are exactly the same as in Example 1.

[0084] Performance testing:

[0085] The iron ingot grade was determined and the iron recovery rate was calculated according to GB / T 6730.5-2007. The test results are shown in Table 2.

[0086] Table 2

[0087]

[0088] As can be seen from Table 2, as obtained from Examples 1-3, the method for resource utilization of laterite nickel ore leaching residue described in this invention can recover iron ingots with a grade of over 97.85% and an iron recovery rate of over 94.2%.

[0089] A comparison of Examples 1 and 4-5 shows that in the method for resource utilization of laterite nickel ore leaching slag described in this invention, the amount of the second reducing agent added affects the recovery effect. Controlling the mass ratio of sinter to the second reducing agent at 100:(10~15) results in a better recovery effect. If the amount of the second reducing agent added is too low, Fe reduction will be incomplete, and iron metal will be lost in the slag, affecting the Fe recovery rate and the smelting effect. If the amount of the second reducing agent added is too high, the fluidity of the slag will be reduced, affecting the separation of slag and iron, and metal will be mixed in the slag.

[0090] A comparison of Examples 1 and 6-7 shows that in the method for resource utilization of laterite nickel ore leaching slag described in this invention, the amount of flux added affects the recovery effect. Controlling the mass ratio of sinter to flux at 100:(10~20) results in a better recovery effect. If the amount of flux added is too low, the slag viscosity will be too high, resulting in poor fluidity, difficulty in slag-iron separation, slag inclusion in molten iron, and affecting the purity of iron. If the amount of flux added is too high, the slag will easily become thick, making it difficult to separate slag and iron.

[0091] Comparing Examples 1 and 8-9, it can be seen that in the method for resource utilization of laterite nickel ore leaching slag described in this invention, the amount of sulfiding agent added affects the recovery effect. Controlling the mass ratio of sintering material to sulfiding agent at 100:(3~8) results in a better recovery effect. If the amount of sulfiding agent added is too low, the elements are insufficient to capture all chromium and convert it into sulfides, which will cause some chromium to enter the molten iron and some to enter the slag in the form of Cr2O3, increasing the toxicity of the slag and wasting Cr resources. If the amount of sulfiding agent added is too high, it is easy to cause the sulfur content of the molten iron to exceed the standard, which will form iron-sulfur mainly composed of FeS, and the chromium-sulfur phase grade will decrease.

[0092] As can be seen from the comparison between Example 1 and Comparative Example 1, the present invention uses a first reducing agent to remove impurities from laterite nickel ore and then performs reduction roasting treatment, which pre-reduces some of the trivalent iron to divalent iron or elemental iron and removes the water of crystallization, thereby greatly improving the reactivity of the material in subsequent smelting, reducing the melting point of the sinter, and reducing the required smelting temperature and time.

[0093] As can be seen from the comparison between Example 1 and Comparative Example 2, the present invention creatively introduces a sulfiding agent during the melting reaction process, and utilizes the selective capture effect of sulfur on chromium to generate an independent and easily separable chromium-sulfur phase with a density between molten iron and slag. This solves the industry problem that chromium is difficult to recover from laterite nickel ore leaching slag and is prone to pollution, allowing chromium to be separated from iron and recovered independently.

[0094] As can be seen from the comparison between Example 1 and Comparative Example 3, the introduction of flux during the melting process in this invention can adjust the basicity, viscosity and melting point of the slag, ensure that iron, chromium sulfide and slag can be well separated into layers, and ensure the fluidity of the slag, which is convenient for discharge and subsequent utilization.

[0095] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for the resource utilization of laterite nickel ore leaching residue, characterized in that, The method includes the following steps: The laterite nickel ore leaching residue is mixed with the first reducing agent and then subjected to reduction roasting to obtain sinter. The sintering material, the second reducing agent, the fluxing agent and the vulcanizing agent are mixed and then subjected to a reduction smelting reaction to obtain the smelted material; The smelting material is subjected to full component recovery to obtain slag, chromium-sulfur phase and iron ingot.

2. The method as described in claim 1, characterized in that, The laterite nickel ore leaching residue is pre-dried.

3. The method as described in claim 2, characterized in that, The drying temperature is 100℃~150℃; Preferably, the drying process takes 5 to 10 hours.

4. The method according to any one of claims 1-3, characterized in that, The first reducing agent includes any one or a combination of at least two of anthracite, lignite, or semi-coke.

5. The method according to any one of claims 1-4, characterized in that, The mass ratio of the laterite nickel ore leaching residue to the first reducing agent is (5~15):

100.

6. The method according to any one of claims 1-5, characterized in that, The temperature of the reduction calcination treatment is 900℃~1100℃; Preferably, the reduction calcination time is 2h~4h; Preferably, the atmosphere of the reduction roasting treatment includes nitrogen and / or argon.

7. The method according to any one of claims 1-6, characterized in that, The second reducing agent includes coke; Preferably, the mass ratio of the sintering material to the second reducing agent is 100:(10~15).

8. The method according to any one of claims 1-7, characterized in that, The flux includes calcium carbonate; Preferably, the mass ratio of the sintering material to the flux is 100:(10~20).

9. The method according to any one of claims 1-8, characterized in that, The sulfiding agent includes pyrite; Preferably, the mass ratio of the sintering material to the vulcanizing agent is 100:(3~8).

10. The method according to any one of claims 1-9, characterized in that, The temperature of the reduction smelting reaction is 1550℃~1650℃; Preferably, the reduction smelting reaction takes 15 to 45 minutes.

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