Method and device for separating nickel and iron from nickel-iron alloy

Abstract

The present invention provides a method and device for separating nickel and iron from a nickel-iron alloy. The method comprises the following steps: roasting the nickel-iron alloy in a chlorine-containing atmosphere to obtain a roasting residue and an iron- and nickel-containing vapor phase, wherein the roasting temperature is 900-1200°C, and the roasting duration is 60-180 min; performing multi-stage condensation on the iron- and nickel-containing vapor phase, and collecting a solid phase obtained from first-stage condensation to obtain a nickel chloride product; and collecting a solid phase obtained from second-stage condensation to obtain an iron chloride product, wherein the second-stage condensation follows the first-stage condensation, and the condensation temperature of the second-stage condensation is 100-200°C. In the method for separating nickel and iron from a nickel-iron alloy, during roasting, highly selective volatilization of iron and nickel is achieved by controlling the roasting temperature and the roasting atmosphere, while impurities retain in the residue. Subsequently, by performing staged temperature-controlled condensation on the vapor phase obtained by roasting, high-purity nickel chloride and iron chloride products can be obtained separately.

Description

Method and apparatus for separating nickel and iron from nickel-iron alloy

[0001] Cross-references to related applications

[0002] This application is based on and claims priority to Chinese Patent Application No. 202410981952.X, filed on July 22, 2024, entitled “Method and Apparatus for Separating Nickel-Iron Alloy”, the full text of which is incorporated herein by reference as a part of this application. [Technical Field]

[0003] This invention relates to the field of alloy separation and resource utilization, and in particular to a method and apparatus for separating nickel from ferronickel alloys. [Background Technology]

[0004] Nickel is an important strategic metal. With the increasing scarcity of high-quality sulfide nickel ore, abundant laterite nickel ore has become an important raw material for nickel extraction. Pyrometallurgical processes for laterite nickel ore have advantages such as simple operation procedures and wide utilization of raw materials, making them one of the main processes for the development and utilization of laterite nickel ore. Examples include the RK-EF process (Rotary Klin Electric Furnace), rotary kiln direct reduction-magnetic separation process, and rotary hearth furnace-smelting furnace process. However, the products obtained by the above processes are nickel-iron alloys, and there is an urgent need to conduct research on the separation of nickel and iron in nickel-iron alloys to obtain nickel salts and iron salts as raw materials for the production of power batteries.

[0005] Conventional nickel-iron separation processes often employ wet leaching, which typically involves cumbersome leaching, impurity removal, and precipitation processes before the product can be prepared. [Summary of the Invention]

[0006] The main objective of this invention is to provide a method and apparatus for separating nickel from iron alloys, thereby solving the technical problem that the separation process using wet leaching requires cumbersome leaching, impurity removal, and precipitation processes.

[0007] To achieve the above objectives, the present invention provides a method for separating nickel from iron alloy, comprising the following steps:

[0008] The nickel-iron alloy was calcined in an atmosphere containing chlorine to obtain calcined slag and a nickel-iron gas phase. The calcination temperature was 900℃-1200℃ and the calcination time was 60-180min.

[0009] A nickel-containing gas phase is subjected to multi-stage condensation, and the solid phase obtained from the first stage of condensation is collected to obtain nickel chloride product. In the multi-stage condensation, each subsequent stage condenses the condensed gas phase obtained from the previous stage, and the condensation temperature of the subsequent stage is lower than that of the previous stage. The first stage of condensation is one of the multiple stages of condensation. The condensation temperature of the first stage is 450-700℃.

[0010] The solid phase obtained from the second-stage condensation is collected to obtain ferric chloride product. The second-stage condensation is one of the multiple-stage condensation processes and occurs after the first-stage condensation. The condensation temperature of the second-stage condensation is 100-200℃.

[0011] In some embodiments of the present invention, in the atmosphere containing chlorine, the chlorine gas satisfies the condition that 1 kg of nickel-iron alloy contains 2-5 kg ​​of chlorine gas.

[0012] In some embodiments of the present invention, the chlorine-containing atmosphere also includes oxygen, wherein the oxygen satisfies the condition that 1 kg of nickel-iron alloy contains 0-300 g of oxygen.

[0013] In some embodiments of the present invention, it further includes:

[0014] The solid phase obtained from the intermediate stage condensation is used to obtain iron-containing nickel chloride. The intermediate stage condensation is one of the multiple stages of condensation and is located between the first stage condensation and the second stage condensation. The condensation temperature of the intermediate stage condensation is 320-450℃.

[0015] In some embodiments of the present invention, it further includes:

[0016] Nickel chloride powder is added during the intermediate condensation process.

[0017] In some embodiments of the present invention, the amount of nickel chloride powder added is 10-20g of nickel chloride powder per 1kg of nickel-iron alloy.

[0018] In some embodiments of the present invention, it further includes:

[0019] The iron-containing nickel chloride was used as a raw material for nickel-iron alloy and was calcined again in an atmosphere containing chlorine.

[0020] In some embodiments of the present invention, the number of stages of the multi-stage condensation is ≥3.

[0021] In some embodiments of the present invention, the average particle size of the nickel-iron alloy is ≤5cm.

[0022] This application also provides an apparatus for separating nickel and iron from a nickel-iron alloy, comprising:

[0023] A calcining furnace is used to calcine nickel-iron alloys in an atmosphere containing chlorine to obtain calcined slag and a gaseous phase containing iron and nickel. The calcination temperature is 900℃-1200℃ and the calcination time is 60-180min.

[0024] A multi-stage condensation mechanism, connected to the calcining furnace, receives the iron-nickel-containing gas phase and performs multi-stage condensation on it. Each subsequent stage of the multi-stage condensation mechanism condenses the condensed gas phase obtained from the preceding stage, and the condensation temperature of the subsequent stage is lower than that of the preceding stage. The multi-stage condensation mechanism includes a first-stage condensation mechanism and a second-stage condensation mechanism, with the second-stage condensation mechanism located after the first-stage condensation mechanism. The condensation temperature of the first-stage condensation mechanism is 450-700℃. The condensation temperature of the second-stage condensation mechanism is 100-200℃.

[0025] The first collection mechanism is connected to a condensation mechanism and is used to collect the solid phase obtained by the condensation mechanism to obtain nickel chloride product.

[0026] The second collection mechanism is connected to the second-stage condensation mechanism and is used to collect the solid phase obtained by the second-stage condensation mechanism to obtain ferric chloride product.

[0027] In the aforementioned method for separating nickel from ferroalloys, the selective volatilization of iron and nickel is achieved by controlling the roasting temperature and atmosphere during the roasting process, while impurities are retained in the slag. Subsequent staged temperature-controlled condensation of the gaseous phase obtained from roasting yields high-purity nickel chloride and ferrochloride products. This method for separating nickel from ferroalloys features a short process flow and produces high-purity products. [Attached Image Description]

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0029] Figure 1 is a flowchart of the separation of nickel and iron from nickel-iron alloy according to an embodiment of this application.

[0030] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings.

Detailed Implementation Methods

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] It should be noted that all directional indicators (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0033] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0034] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0035] This invention provides a method for separating nickel from iron alloy, as shown in Figure 1, comprising the following steps:

[0036] S100: Nickel-iron alloy is roasted in an atmosphere containing chlorine to obtain roasted slag and iron-nickel gas phase. The roasting temperature is 900℃-1200℃ and the roasting time is 60-180min.

[0037] This invention provides a method for separating nickel and iron from nickel-iron alloys by high-temperature chlorination volatilization roasting. The method involves converting nickel and iron in the alloy into gaseous nickel chloride and iron chloride through chlorination roasting, followed by controlled-temperature segmented condensation to obtain nickel chloride and iron chloride products.

[0038] The key lies in achieving efficient and selective volatilization of nickel-iron chloride by controlling the chlorination roasting temperature and atmosphere (boiling points of each chloride: FeCl3 -316℃, FeCl2 -1023℃, NiCl2 -973℃). Nickel chloride and ferric chloride have significantly different boiling points, while ferrous chloride and nickel chloride have similar boiling points. Therefore, during the roasting process, controlling the chlorination roasting temperature and atmosphere minimizes or eliminates the formation of ferrous chloride (in fact, almost no ferrous chloride is detected). Otherwise, because ferrous chloride and nickel chloride have similar boiling points, nickel chloride would have a higher iron content, affecting the purity of the nickel chloride product. After roasting, utilizing the differences in the boiling points of the chlorides, the resulting gas phase is condensed in stages with controlled temperature to obtain nickel chloride and ferric chloride products separately.

[0039] The nickel-iron alloys in this application are alloys whose main components are nickel and iron, and are smelting intermediates. In some embodiments, the nickel-iron alloys in this application are nickel-iron alloys obtained by pyrometallurgical smelting of laterite nickel ore, such as those obtained by the RK-EF process, rotary kiln direct reduction-magnetic separation process, and rotary hearth furnace-melting furnace process. In some specific embodiments, the composition of the nickel-iron alloy is shown in Table 1.

[0040] Table 1: Chemical composition (wt%) of nickel-iron alloys

[0041] Nickel-iron alloys are calcined in a chlorine-containing atmosphere. For example, the alloy is added to a calcining furnace, and chlorine gas is introduced into the furnace for high-temperature chlorination and volatilization calcination, causing the iron and nickel to volatilize, resulting in calcined slag and a gaseous phase containing iron and nickel. The calcination temperature is 900℃-1200℃, and the calcination time is 60-180 minutes. Under these conditions, the nickel-iron alloy is converted into gaseous nickel chloride and ferric chloride, with almost no ferrous chloride forming.

[0042] The principle of the chlorination roasting process is as follows:

[0043] Ni-Fe+Cl2(g)→FeCl3(g)+NiCl2(g);

[0044] Controlled atmosphere prevents silicon, cadmium, and aluminum from volatilizing: Si + Cl₂ → SiCl₄(g), SiCl₄ + O₂ → SiO₂ + Cl₂(g); Al + Cl₂(g) → AlCl₃(g), AlCl₃(g) + O₂(g) → Al₂O₃(s); Cr + Cl₂ → CrCl₃(g), CrCl₃ + O₂ → Cr₂O₃(s) + Cl₂(g). SiO₂, Al₂O₃, and Cr₂O₃ have boiling points of 2230℃, 2980℃, and 4000℃ respectively, therefore they do not volatilize.

[0045] In some specific embodiments, the calcination temperature is 850℃-1000℃.

[0046] In some specific embodiments, the roasting time is 60-120 minutes.

[0047] S200: A multi-stage condensation process is performed on an iron-nickel-containing gas phase. The solid phase obtained from one stage of condensation is collected to obtain nickel chloride product. In this multi-stage condensation, each subsequent stage condenses the condensed gas phase obtained from the previous stage, and the condensation temperature of the subsequent stage is lower than that of the previous stage. The first stage of condensation is one of the multiple stages of condensation. The condensation temperature of the first stage is 450-700℃.

[0048] The iron-nickel-containing gaseous phase, along with the condensed gaseous phase obtained after one or more condensation stages, undergoes a process where, during condensation, substances containing these gases that reach below their boiling points precipitate as solids. Substances that do not reach below their boiling points remain in the gaseous phase. The gaseous phase remaining after condensation is called the condensed gaseous phase.

[0049] The main substances in the iron-nickel gas phase are ferric chloride and nickel chloride. Therefore, the multi-stage condenser must have at least two stages, although it can have more, such as 3, 4, 5, 9, or even more. The first stage of condensation is mainly for recovering nickel chloride and is not necessarily required to be the first stage of the multi-stage condenser; it can also be located in the second, third, or other stages. However, in some embodiments, the first stage of condensation is located at the beginning of the multi-stage condenser.

[0050] The condensation temperature of the first stage of condensation is 450-700℃. Nickel chloride reaches below its boiling point, while ferric chloride does not, and the following reaction occurs.

[0051] A condensation process:

[0052] FeCl3(g)+NiCl2(g)→FeCl3(g)+NiCl2(s).

[0053] This step yields nickel chloride products with a high purity, exceeding 95%.

[0054] S300: Collect the solid phase obtained from the second-stage condensation to obtain ferric chloride product. The second-stage condensation is one of the multiple-stage condensations and occurs after the first-stage condensation. The condensation temperature of the second-stage condensation is 100-200℃.

[0055] Accordingly, the second-stage condensation mainly involves the condensation and recovery of ferric chloride, and it is not necessarily required to be located in the second stage of a multi-stage condensation. It can also be located in the second or third stage of a multi-stage condensation. Of course, it can also be located in the second stage. In some embodiments, the first-stage condensation is located in the second stage of a multi-stage condensation.

[0056] The second-stage condensation is one of the multiple-stage condensation processes and occurs after the first-stage condensation. For example, there are no other condensation operations between the second-stage condensation and the first-stage condensation.

[0057] For example, there may be other refrigeration operations between the two-stage condensation and the first-stage condensation, such as one or more refrigeration operations between them.

[0058] The condensation temperature of the two-stage condensation is 100-200℃, and the ferric chloride reaches below its boiling point. At this temperature, the following reaction occurs.

[0059] Two-stage condensation process:

[0060] FeCl3(g) → FeCl3(s)

[0061] This step yields a ferric chloride product with a high purity, exceeding 99%.

[0062] In the aforementioned method for separating nickel from ferroalloys, the selective volatilization of iron and nickel is achieved by controlling the roasting temperature and atmosphere during the roasting process, while impurities are retained in the slag. Subsequent staged temperature-controlled condensation of the gaseous phase obtained from roasting yields high-purity nickel chloride and ferrochloride products. This method for separating nickel from ferroalloys features a short process flow and produces high-purity products.

[0063] According to an embodiment of this application, in the atmosphere containing chlorine, the chlorine gas satisfies the condition that 1 kg of nickel-iron alloy contains 2-5 kg ​​of chlorine gas.

[0064] Under these conditions, the selective volatilization of iron and nickel is more favorable, resulting in less ferrous chloride and higher purity ferric chloride and nickel chloride.

[0065] In some specific embodiments, chlorine gas is used to satisfy the condition that 1 kg of nickel-iron alloy contains 2 to 2 kg of chlorine gas.

[0066] According to an embodiment of this application, the atmosphere containing chlorine also includes oxygen, wherein the oxygen satisfies the condition that 1 kg of nickel-iron alloy contains 0-300 g of oxygen.

[0067] Under these conditions, the selective volatilization of iron and nickel is more favorable, resulting in less ferrous chloride and higher purity ferric chloride and nickel chloride. In some specific embodiments, the oxygen content satisfies the condition that 1 kg of nickel-iron alloy contains 0-300 g of oxygen.

[0068] Oxygen inhibits the volatilization of impurities, and the separation of nickel and iron, as well as the purity of ferric chloride, are better in the presence of oxygen. It's understandable that oxygen is not essential; the separation of nickel and iron can be achieved without oxygen.

[0069] According to an embodiment of this application, it further includes:

[0070] The solid phase obtained from the intermediate stage condensation is used to obtain iron-containing nickel chloride. The intermediate stage condensation is one of the multiple stages of condensation and is located between the first stage condensation and the second stage condensation. The condensation temperature of the intermediate stage condensation is 320-450℃.

[0071] In this embodiment, intermediate condensation is carried out in the first and second stages of condensation, and the condensation temperature of the intermediate stage is 320-450℃.

[0072] Intermediate condensation process:

[0073] FeCl3(g)+NiCl2(g)+NiCl2(s)→FeCl3(g)+NiCl2(s)+FeCl3(s, trace).

[0074] During this condensation process, nickel chloride containing trace amounts of ferric chloride is obtained, i.e., ferric nickel chloride. In this way, nickel chloride is basically condensed into a solid in both the first and intermediate condensation stages, and the condensed gas phase obtained in the intermediate condensation stage is mainly ferric chloride gas. Thus, the purity of the ferric chloride product obtained from the two-stage condensation is further improved.

[0075] According to an embodiment of this application, it further includes:

[0076] Nickel chloride powder is added during the intermediate condensation process.

[0077] In this embodiment, nickel chloride powder, such as that obtained from the first stage of condensation, is added to the condenser corresponding to the intermediate stage of condensation during the condensation process. The nickel chloride powder acts as a seed crystal, which facilitates the precipitation of nickel chloride during condensation, resulting in a faster precipitation rate and a higher degree of precipitation. This improves the efficiency of condensation and the purity of the subsequent ferric chloride.

[0078] According to the embodiments of this application, the amount of nickel chloride powder added is 10-20g of nickel chloride powder per 1kg of nickel-iron alloy.

[0079] Under these conditions, the precipitation rate of nickel chloride during the condensation process can be improved, which is beneficial to improving the condensation efficiency and the purity of subsequent ferric chloride.

[0080] According to an embodiment of this application, it further includes:

[0081] The iron-containing nickel chloride was used as a raw material for nickel-iron alloy and was calcined again in an atmosphere containing chlorine.

[0082] Iron-containing nickel chloride has a relatively high purity. If higher purity is desired, iron-containing nickel chloride can be returned to S100 as raw material for chlorination roasting.

[0083] In some embodiments, nitrogen is used to replace the air in the roasting furnace and multi-stage condenser before roasting.

[0084] According to an embodiment of this application, the number of stages in the multi-stage condensation is ≥3.

[0085] As previously described, this applies to the case where the number of condensation stages is two.

[0086] In some embodiments, the number of stages in the multi-stage condensation is three. For example, multi-stage condensation may include a first-stage condensation, an intermediate-stage condensation, and a second-stage condensation performed sequentially.

[0087] In other embodiments, the number of condensation stages is greater than three. That is, the iron- and nickel-containing gas phase obtained from high-temperature chlorination roasting is separated into iron and nickel through more condensation steps, thereby further improving the purity of nickel chloride and ferric chloride products.

[0088] According to the embodiments of this application, the average particle size of the nickel-iron alloy is ≤5cm. Controlling the particle size of the nickel-iron alloy to below 5cm increases its specific surface area, which is beneficial for its full reaction and selective and efficient chlorination roasting followed by volatilization.

[0089] To more clearly describe the technical solution of this application, a more specific embodiment will be used for illustration.

[0090] This invention provides a method for separating nickel from iron alloy, comprising the following steps:

[0091] The nickel-iron alloy was calcined in an atmosphere containing chlorine to obtain calcined slag and a nickel-iron gas phase. The calcination temperature was 900℃-1200℃ and the calcination time was 60-180min.

[0092] The iron-nickel-containing gas phase is subjected to a first-stage condensation to obtain nickel chloride product and condensed gas phase; the condensation temperature of the first-stage condensation is 450-700℃.

[0093] The condensed gas phase obtained from the first stage of condensation is subjected to intermediate stage condensation to obtain nickel chloride containing iron and condensed gas phase; the condensation temperature of the intermediate stage condensation is 320-450℃.

[0094] The condensed gas phase obtained from the intermediate condensation is subjected to a second-stage condensation to obtain ferric chloride; the condensation temperature of the second-stage condensation is 100-200℃.

[0095] This application also provides an apparatus for separating nickel and iron from a nickel-iron alloy, comprising:

[0096] A calcining furnace is used to calcine nickel-iron alloys in an atmosphere containing chlorine to obtain calcined slag and a gaseous phase containing iron and nickel. The calcination temperature is 900℃-1200℃ and the calcination time is 60-180min.

[0097] A multi-stage condensation mechanism, connected to the calcining furnace, receives the iron-nickel-containing gas phase and performs multi-stage condensation on it. Each subsequent stage of the multi-stage condensation mechanism condenses the condensed gas phase obtained from the preceding stage, and the condensation temperature of the subsequent stage is lower than that of the preceding stage. The multi-stage condensation mechanism includes a first-stage condensation mechanism and a second-stage condensation mechanism, with the second-stage condensation mechanism located after the first-stage condensation mechanism. The condensation temperature of the first-stage condensation mechanism is 450-700℃. The condensation temperature of the second-stage condensation mechanism is 100-200℃.

[0098] The first collection mechanism is connected to a condensation mechanism and is used to collect the solid phase obtained by the condensation mechanism to obtain nickel chloride product. The first collection mechanism can be located below the condensation mechanism and receive the nickel chloride product by gravity.

[0099] The second collection mechanism, connected to the second-stage condensation mechanism, is used to collect the solid phase obtained by the second-stage condensation mechanism to obtain ferric chloride product. The second collection mechanism can be located below the second-stage condensation mechanism to receive nickel chloride product by gravity.

[0100] The apparatus for separating nickel from ferroalloys corresponds to the method described above and is used to implement the aforementioned method. When selecting methods from different embodiments, the apparatus for separating nickel from ferroalloys in cold rolling wastewater can be appropriately adjusted. The apparatus for separating nickel from ferroalloys corresponds to the method and has corresponding beneficial effects, which will not be elaborated further.

[0101] The composition of the nickel-iron alloy used in the following examples is shown in Table 1.

[0102] Table 1: Chemical composition (wt%) of nickel-iron alloys

[0103] Example 1:

[0104] (1) Add 500g of nickel-iron alloy iron particles with a particle size of 1-2cm into the calcination furnace, and then purge the air in the equipment with nitrogen for 30 minutes.

[0105] (2) Chlorine and oxygen were introduced into the roasting furnace for high-temperature chlorination and volatilization roasting. The amount of chlorine added was 2.2 kg per kg of alloy, and the amount of oxygen added was 100 g per kg of alloy. The high-temperature chlorination and volatilization roasting temperature was 1000℃, and the roasting time was 120 min. After roasting, roasted slag and a gaseous phase containing iron and nickel were obtained. The volatilization rates of nickel, iron, silicon, cadmium, and aluminum were analyzed and calculated to be 99.85%, 99.61%, 1.37%, 0.41%, and 0.20%, respectively.

[0106] (3) The iron- and nickel-containing gas phase is subjected to a first-stage condensation treatment, with the condensation temperature controlled at 600℃. After condensation, nickel chloride and a first-stage condensed gas phase are obtained. Using the mass difference method, the mass of the nickel chloride product obtained in this step is measured to be 248.73g, and the purity of the nickel chloride product is 99.3% (based on nickel chloride content).

[0107] (4) The first-stage condensed gas phase is subjected to a second-stage condensation process, with the second-stage condensation temperature controlled at 350℃. During the condensation process, 20g of nickel chloride powder obtained from the first-stage condensation (pre-coated on the tube wall) is added to the condenser. After condensation, nickel chloride containing a small amount of iron and a second-stage condensed gas phase containing iron are obtained. Using the mass difference method, the mass of the solid product received in this step is measured to be 53.07g, and the purity of the nickel chloride product is 90.44% (based on nickel chloride content).

[0108] (5) The two-stage condensed gas phase was subjected to three-stage condensation treatment, and the temperature of the three-stage condensation was controlled at 120℃ to obtain 1008.05g of ferric chloride product with a purity of 99.47%.

[0109] Example 2:

[0110] (1) Add 500g of nickel-iron alloy iron particles with a particle size of 1-2cm into the calcination furnace, and then purge the air in the equipment with nitrogen for 30 minutes.

[0111] (2) Chlorine and oxygen were introduced into the roasting furnace for high-temperature chlorination and volatilization roasting. The amount of chlorine added was 2.2 kg per kg of alloy, and the amount of oxygen added was 200 g per kg of alloy. The high-temperature chlorination and volatilization roasting temperature was 1000℃, and the roasting time was 120 min. After roasting, roasted slag and a gaseous phase containing iron and nickel were obtained. The volatilization rates of nickel, iron, silicon, cadmium, and aluminum were analyzed and calculated to be 99.05%, 98.73%, 0.72%, 0.06%, and 0.07%, respectively.

[0112] (3) The iron- and nickel-containing gas phase is subjected to a first-stage condensation treatment, with the condensation temperature controlled at 600℃. After condensation, nickel chloride and a first-stage condensed gas phase are obtained. Using the mass difference method, the mass of the nickel chloride product obtained in this step is measured to be 245.39g, and the purity of the nickel chloride product is 99.7% (based on nickel chloride content).

[0113] (4) The first-stage condensed gas phase was subjected to a second-stage condensation treatment, with the second-stage condensation temperature controlled at 400℃. During the condensation process, 20g of nickel chloride powder obtained from the first-stage condensation was added to the condenser. After condensation, nickel chloride containing a small amount of iron and a second-stage condensed gas phase containing iron were obtained. Using the mass difference method, the mass of the solid product received in this step was measured to be 52.37g, and the purity of the nickel chloride product was 97.38% (based on nickel chloride content).

[0114] (5) The two-stage condensed gas phase was subjected to three-stage condensation treatment, and the temperature of the three-stage condensation was controlled at 120℃ to obtain 1005.91g of ferric chloride product with a purity of 99.68%.

[0115] Example 3:

[0116] (1) Add 500g of nickel-iron alloy iron particles with a particle size of 1-2cm into the calcination furnace, and then purge the air in the equipment with nitrogen for 30 minutes.

[0117] (2) Chlorine and oxygen were introduced into the roasting furnace for high-temperature chlorination and volatilization roasting. The amount of chlorine added was 2.8 kg per kg of alloy, and the amount of oxygen added was 150 g per kg of alloy. The high-temperature chlorination and volatilization roasting temperature was 950℃, and the roasting time was 120 min. After roasting, roasted slag and a gaseous phase containing iron and nickel were obtained. The volatilization rates of nickel, iron, silicon, cadmium, and aluminum were analyzed and calculated to be 95.48%, 94.07%, 0.91%, 0.37%, and 0.14%, respectively.

[0118] (3) The iron- and nickel-containing gas phase is subjected to a first-stage condensation treatment, with the condensation temperature controlled at 500℃. After condensation, nickel chloride and a first-stage condensed gas phase are obtained. Using the mass difference method, the mass of the nickel chloride product obtained in this step is measured to be 254.11g, and the purity of the nickel chloride product is 97.46% (based on nickel chloride content).

[0119] (4) The first-stage condensed gas phase was subjected to a second-stage condensation process, with the second-stage condensation temperature controlled at 400℃. During the condensation process, 18g of nickel chloride powder obtained from the first-stage condensation was added to the condenser. After condensation, nickel chloride containing a small amount of iron and a second-stage condensed gas phase containing iron were obtained. Using the mass difference method, the mass of the solid product received in this step was measured to be 36.75g, and the purity of the nickel chloride product was 73.22% (based on nickel chloride content).

[0120] (5) The two-stage condensed gas phase was subjected to three-stage condensation treatment, and the temperature of the three-stage condensation was controlled at 200℃ to obtain 968.54g of ferric chloride product with a purity of 99.03%.

[0121] Example 4:

[0122] (1) Add 500g of nickel-iron alloy iron particles with a particle size of 1-2cm into the calcination furnace, and then purge the air in the equipment with nitrogen for 30 minutes.

[0123] (2) Chlorine and oxygen were introduced into the roasting furnace for high-temperature chlorination and volatilization roasting. The amount of chlorine added was 2.8 kg per 1 kg alloy. The high-temperature chlorination and volatilization roasting temperature was 950℃, and the roasting time was 120 min. After roasting, roasted slag and a gaseous phase containing iron and nickel were obtained. The volatilization rates of nickel, iron, silicon, cadmium, and aluminum were analyzed and calculated to be 95.48%, 94.07%, 8.39%, 89.34%, and 92.47%, respectively.

[0124] (3) The iron- and nickel-containing gas phase is subjected to a first-stage condensation treatment, with the condensation temperature controlled at 500℃. After condensation, nickel chloride and a first-stage condensed gas phase are obtained. Using the mass difference method, the mass of the nickel chloride product obtained in this step is measured to be 253.97g, and the purity of the nickel chloride product is 97.93% (based on nickel chloride content).

[0125] (4) The first-stage condensed gas phase was subjected to a second-stage condensation process, with the second-stage condensation temperature controlled at 400℃. During the condensation process, 20g of nickel chloride powder obtained from the first-stage condensation was added to the condenser. After condensation, nickel chloride containing a small amount of iron and a second-stage condensed gas phase containing iron were obtained. Using the mass difference method, the mass of the solid product received in this step was measured to be 40.73g, and the purity of the nickel chloride product was 69.31% (based on nickel chloride content).

[0126] (5) The two-stage condensed gas phase was subjected to three-stage condensation treatment, and the temperature of the three-stage condensation was controlled at 200℃ to obtain 972.03g of ferric chloride product with a purity of 98.37%.

[0127] Example 5:

[0128] (1) Add 500g of nickel-iron alloy iron particles with a particle size of 1-2cm into the calcination furnace, and then purge the air in the equipment with nitrogen for 30 minutes.

[0129] (2) Chlorine and oxygen were introduced into the roasting furnace for high-temperature chlorination and volatilization roasting. The amount of chlorine added was 2.2 kg per kg of alloy, and the amount of oxygen added was 300 g per kg of alloy. The high-temperature chlorination and volatilization roasting temperature was 1150℃, and the roasting time was 120 min. After roasting, roasted slag and a gaseous phase containing iron and nickel were obtained. The volatilization rates of nickel, iron, silicon, cadmium, and aluminum were analyzed and calculated to be 99.99%, 100%, 0.04%, 0.03%, and 0.05%, respectively.

[0130] (3) The iron- and nickel-containing gas phase is subjected to a first-stage condensation treatment, with the condensation temperature controlled at 600℃. After condensation, nickel chloride and a first-stage condensed gas phase are obtained. Using the mass difference method, the mass of the nickel chloride product obtained in this step is measured to be 250.17g, and the purity of the nickel chloride product is 99.09% (based on nickel chloride content).

[0131] (4) The first-stage condensed gas phase was subjected to a second-stage condensation process, with the second-stage condensation temperature controlled at 400℃. During the condensation process, 16g of nickel chloride powder obtained from the first-stage condensation was added to the condenser. After condensation, nickel chloride containing a small amount of iron and a second-stage condensed gas phase containing iron were obtained. Using the mass difference method, the mass of the solid product received in this step was measured to be 49.93g, and the purity of the nickel chloride product was 90.01% (based on nickel chloride content).

[0132] (5) The two-stage condensed gas phase was subjected to three-stage condensation treatment, and the temperature of the three-stage condensation was controlled at 120℃ to obtain 1012.61g of ferric chloride product with a purity of 99.03%.

[0133] Example 6:

[0134] (1) Add 500g of nickel-iron alloy iron particles with a particle size of 1-2cm into the calcination furnace, and then purge the air in the equipment with nitrogen for 30 minutes.

[0135] (2) Chlorine and oxygen were introduced into the roasting furnace for high-temperature chlorination and volatilization roasting. The amount of chlorine added was 2.2 kg per 1 kg of alloy, and the amount of oxygen added was 100 g per 1 kg of alloy. The high-temperature chlorination and volatilization roasting temperature was 1000℃, and the roasting time was 120 min. After roasting, roasted slag and a gaseous phase containing iron and nickel were obtained. The volatilization rates of nickel, iron, silicon, cadmium, and aluminum were analyzed and calculated to be 99.63%, 99.87%, 1.61%, 0.38%, and 0.27%, respectively.

[0136] (3) The iron- and nickel-containing gas phase is subjected to a first-stage condensation treatment, with the condensation temperature controlled at 600℃. After condensation, nickel chloride and a first-stage condensed gas phase are obtained. Using the mass difference method, the mass of the nickel chloride product obtained in this step is measured to be 249.08g, and the purity of the nickel chloride product is 99.14% (based on nickel chloride content).

[0137] (4) The first-stage condensed gas phase is subjected to a second-stage condensation treatment, with the second-stage condensation temperature controlled at 350℃. After condensation, nickel chloride containing a small amount of iron and a second-stage condensed gas phase containing iron are obtained. Using the mass difference method, the mass of the solid product received in this step is measured to be 19.21g, and the purity of the nickel chloride product is 89.12% (based on nickel chloride content).

[0138] (5) The two-stage condensed gas phase was subjected to three-stage condensation treatment, and the temperature of the three-stage condensation was controlled at 120℃ to obtain 1015.07g of ferric chloride product with a purity of 98.42%.

[0139] Compared to other embodiments, in Embodiment 6, since nickel chloride is not added in the second stage of condensation, there is no nickel chloride as a crystal nucleus in the second stage of condensation, which weakens the nickel capture effect in the second stage, and the iron purity in the ferric chloride entering the third stage is slightly reduced.

[0140] Comparative Example 1

[0141] (1) Add 500g of nickel-iron alloy iron particles with a particle size of 1-2cm into the calcination furnace, and then purge the air in the equipment with nitrogen for 30 minutes.

[0142] (2) Chlorine and oxygen were introduced into the roasting furnace for high-temperature chlorination and volatilization roasting. The amount of chlorine added was 2.2 kg per 1 kg of alloy, and the amount of oxygen added was 100 g per 1 kg of alloy. The high-temperature chlorination and volatilization roasting temperature was 600℃, and the roasting time was 120 min. After roasting, roasted slag and a gaseous phase containing iron and nickel were obtained. The volatilization rates of nickel, iron, silicon, cadmium, and aluminum were analyzed and calculated to be 0.52%, 94.36%, 0.21%, 0.03%, and 0.11%, respectively.

[0143] (3) The iron- and nickel-containing gas phase was subjected to a first-stage condensation treatment, with the condensation temperature controlled at 600℃. After condensation, nickel chloride and a first-stage condensed gas phase were obtained. Using the mass difference method, the mass of the nickel chloride product received in this step was measured to be 2.07g, and the purity of nickel chloride was 91.30% (after washing and dissolving the small amount with water, the elemental concentration in the water was measured to calculate the amount of nickel collected). Since there was essentially no nickel chloride, ferric chloride was directly recovered by subsequent condensation.

[0144] (4) The first-stage condensed gas phase was subjected to a second-stage condensation treatment, and the second-stage condensation temperature was controlled at 120℃ to obtain 1017.30g of ferric chloride product with a purity of 99.19%.

[0145] Comparative Example 2:

[0146] (1) Add 500g of nickel-iron alloy iron particles with a particle size of 1-2cm into the calcination furnace, and then purge the air in the equipment with nitrogen for 30 minutes.

[0147] (2) Chlorine and oxygen were introduced into the roasting furnace for high-temperature chlorination and volatilization roasting. The amount of chlorine added was 2.2 kg per 1 kg of alloy, and the amount of oxygen added was 500 g per 1 kg of alloy. The high-temperature chlorination and volatilization roasting temperature was 1000℃, and the roasting time was 120 min. After roasting, roasted slag and a gaseous phase containing iron and nickel were obtained. The volatilization rates of nickel, iron, silicon, cadmium, and aluminum were analyzed and calculated to be 78.43%, 83.79%, 0.02%, 0.13%, and 0.09%, respectively.

[0148] In Comparative Example 2, the high oxygen content caused some iron and nickel to oxidize. Ferric oxide and nickel oxide were difficult to volatilize by chlorination and formed an oxide film that hindered the reaction.

[0149] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for separating nickel and iron from a nickel-iron alloy, characterized by, The method comprises the following steps: roasting the nickel-iron alloy in an atmosphere containing chlorine to obtain roasted slag and iron-nickel gas phase, wherein the roasting temperature is 900-1200℃, and the roasting time is 60-180min; carrying out multi-stage condensation on the iron-nickel gas phase, collecting the solid phase obtained in the first stage of condensation to obtain nickel chloride product; wherein in the multi-stage condensation, the condensation of the next stage is carried out on the condensed gas phase obtained in the previous stage, and the condensation temperature of the next stage is lower than that of the previous stage; the first stage of condensation is one of the stages in the multi-stage condensation; the condensation temperature of the first stage is 450-700℃; collecting the solid phase obtained in the second stage of condensation to obtain iron chloride product; wherein the second stage of condensation is one of the stages in the multi-stage condensation and is located after the first stage of condensation; the condensation temperature of the second stage is 100-200℃.

2. The method of separating nickel from ferronickel according to claim 1, characterized in that, In the atmosphere containing chlorine, the chlorine satisfies the condition of 2-5kg of chlorine per 1kg of nickel-iron alloy.

3. The method of separating nickel from ferronickel according to claim 2, characterized in that, The atmosphere containing chlorine also contains oxygen, and the oxygen satisfies the condition of 0-300g of oxygen per 1kg of nickel-iron alloy.

4. The method of separating nickel from ferronickel according to claim 1, characterized in that, Further comprising: collecting the solid phase obtained in the intermediate stage of condensation to obtain iron-containing nickel chloride, wherein the intermediate stage of condensation is one of the stages in the multi-stage condensation and is located between the first stage of condensation and the second stage of condensation; the condensation temperature of the intermediate stage is 320-450℃.

5. The method of separating nickel from ferronickel according to claim 4, characterized in that, Further comprising: adding nickel chloride powder in the intermediate stage of condensation.

6. The method of separating nickel from ferronickel according to claim 5, characterized in that, The amount of added nickel chloride powder is 10-20g per 1kg of nickel-iron alloy.

7. The method of separating nickel from ferronickel according to claim 4, characterized in that, Further comprising: re-roasting the iron-containing nickel chloride as the raw material of the nickel-iron alloy in an atmosphere containing chlorine.

8. The method of separating nickel from ferronickel according to claim 1, characterized in that, The number of stages in the multi-stage condensation is ≥3.

9. The method of separating nickel from ferronickel according to claim 1, characterized in that, The average particle size of the nickel-iron alloy is ≤5cm.

10. An apparatus for separating nickel and iron from a nickel-iron alloy, characterized by comprising: The method comprises: a roasting furnace for roasting the nickel-iron alloy in an atmosphere containing chlorine to obtain roasted slag and iron-nickel gas phase, wherein the roasting temperature is 900-1200℃, and the roasting time is 60-180min; a multi-stage condensation mechanism in communication with the roasting furnace, receiving the iron-nickel gas phase and carrying out multi-stage condensation on the iron-nickel gas phase; the condensed gas phase obtained by the previous stage of the multi-stage condensation mechanism is condensed by the next stage of the multi-stage condensation mechanism, and the condensation temperature of the next stage is lower than that of the previous stage; wherein the multi-stage condensation mechanism comprises a first stage of condensation mechanism and a second stage of condensation mechanism, and the second stage of condensation mechanism is located after the first stage of condensation mechanism; the condensation temperature of the first stage of condensation mechanism is 450-700℃; and the condensation temperature of the second stage of condensation mechanism is 100-200℃; a first collection mechanism in communication with the first stage of condensation mechanism, for collecting the solid phase obtained by the first stage of condensation mechanism to obtain nickel chloride product; a second collection mechanism in communication with the second stage of condensation mechanism, for collecting the solid phase obtained by the second stage of condensation mechanism to obtain iron chloride product.

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