Method for separating nickel and iron by chloridizing and roasting nickel-iron alloy fused salt and application

Abstract

The invention provides a method for separating nickel and iron through nickel-iron alloy fused salt chloridizing roasting and application. The method comprises the following steps that mixed salt is fused to obtain mixed fused salt, and the mixed salt comprises FeCl2, FeCl3, NiCl2 and CaCl2; the ferro-nickel alloy is immersed in the mixed molten salt, chlorine is introduced, chloridizing roasting is carried out, and a volatile gas phase is obtained; wherein the reaction temperature ranges from 650 DEG C to 900 DEG C, and the reaction time ranges from 60 min to 200 min; and carrying out first condensation on the volatile gas phase to obtain a ferric trichloride product. According to the method for separating nickel and iron through chloridizing roasting of the nickel-iron alloy molten salt, the appropriate compound is selected and molten to obtain the mixed molten salt, so that the melting point of the mixed molten salt is low. Wherein due to the existence of FeCl2, FeCl3 and NiCl2, the effects of strengthening the chlorination process and improving selective chlorination can be achieved, and therefore the utilization rate of chlorine is increased.

Description

Technical Field

[0001] The invention relates to the field of nickel smelting, and in particular to a method and application of separating nickel and iron by chlorination roasting of nickel-iron alloy molten salt. Background Art

[0002] Laterite nickel ore is currently the main raw material for nickel smelting. Nickel-iron alloy is the product of reduction smelting of laterite nickel ore, and its iron content is often as high as 70% or more. In recent years, with the increase in power battery consumption and the weakening of nickel consumption in the stainless steel field, it is particularly important to develop an efficient and short-process process for separating nickel and iron in nickel-iron alloy.

[0003] In some separation methods, separation is performed by introducing chlorine gas, roasting, and condensing. However, the above method has a relatively low utilization rate of chlorine gas. Summary of the invention

[0004] The main purpose of the present invention is to provide a method and application of separating nickel and iron by chlorination roasting of nickel-iron alloy molten salt, so as to solve the technical problem of relatively low utilization rate of chlorine in the existing separation method.

[0005] To achieve the above object, the present invention provides a method for separating nickel and iron by chlorination roasting of nickel-iron alloy molten salt, comprising the following steps:

[0006] The mixed salt is melted to obtain a mixed molten salt, wherein the mixed salt includes FeCl2, FeCl3, NiCl2, and CaCl2, and the molar ratio of FeCl2, FeCl3, NiCl2 and CaCl2 is 10:(2-1):(1-0.3):(0.1-0.05).

[0007] The nickel-iron alloy is immersed in a mixed molten salt and chlorine gas is introduced to perform chlorination roasting to obtain a volatile gas phase. The reaction temperature is 650-900°C and the reaction time is 60-200 minutes.

[0008] The volatile gas phase is subjected to a first condensation to obtain a ferric chloride product.

[0009] According to the implementation manner of the present application, the amount of chlorine added is calculated as 2-4 kg of chlorine per kg of alloy, and the volume concentration of the chlorine is 10-60%.

[0010] According to an embodiment of the present application, in the step of condensing the volatile gas phase to obtain the ferric chloride product, the temperature of the first condensation is 100-300°C.

[0011] According to an embodiment of the present application, the step of melting the mixed salt to obtain the mixed molten salt comprises:

[0012] The mixed salt is heated to 600-850° C. to melt, thereby obtaining a mixed molten salt.

[0013] According to an embodiment of the present application, the molar ratio of FeCl2, FeCl3, NiCl2 and CaCl2 is 10:2:1:0.8.

[0014] According to the implementation mode of the present application, it also includes:

[0015] The molten salt phase obtained by chlorination roasting is recycled as a mixed molten salt, and the molten salt phase can be recycled 1 to 3 times.

[0016] According to an embodiment of the present application, when the number of cycles of the molten salt phase is 3, it also includes:

[0017] The molten salt phase is subjected to reduced pressure distillation to obtain a distillate, wherein the distillation pressure is 2-5 kPa, the distillation temperature is 400-600° C., and the distillation time is 30-90 min.

[0018] The distillate is subjected to a second condensation to obtain iron chloride.

[0019] The iron chloride and nickel chloride are mixed to obtain a mixed salt.

[0020] According to an embodiment of the present application, the temperature of the second condensation is 100-200°C.

[0021] According to an embodiment of the present application, the method further includes extracting nickel from the residue obtained by vacuum distillation.

[0022] The present application also provides the application of the above-mentioned method for separating nickel and iron by chlorination roasting of nickel-iron alloy molten salt in nickel smelting.

[0023] In the above-mentioned method of separating nickel and iron by chlorination roasting of nickel-iron alloy molten salt, a suitable compound is selected to melt to obtain a mixed molten salt, so that the melting point of the mixed molten salt is relatively low. Wherein, the presence of FeCl2, FeCl3, and NiCl2 can play a role in strengthening the chlorination process and improving the utilization rate of chlorine. Moreover, the addition of calcium chloride can effectively reduce the content of ferrous chloride and nickelous chloride in ferric chloride obtained by volatilization and condensation, thereby improving the purity of the ferric chloride product. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0025] Figure 1 It is the multivariate liquidus projection diagram of the present application;

[0026] Figure 2 The present invention is a flow chart of a method for separating nickel and iron by chlorination roasting of a nickel-iron alloy molten salt according to an embodiment of the present application.

[0027] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] It should be noted that all directional indications (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0030] In addition, in the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0031] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0032] A method for separating nickel and iron by chlorination roasting of nickel-iron alloy molten salt, comprising the following steps:

[0033] S100: Melting the mixed salt to obtain a mixed molten salt, wherein the mixed salt includes FeCl2, FeCl3, NiCl2, and CaCl2, and the molar ratio of FeCl2, FeCl3, NiCl2, and CaCl2 is 10:(2-1):(1-0.3):(0.1-0.05).

[0034] The present application provides a method for separating nickel and iron by chlorination roasting of ferronickel alloy molten salt, which is to convert the direct chlorination process (gas-solid reaction) of ferronickel alloy into a gas-liquid-solid three-phase reaction by constructing a mixed molten salt phase in the chlorination process, and then condense to obtain a ferric chloride product. In some embodiments, the molten salt phase obtained by the chlorination process is recycled by vacuum distillation to realize the molten salt. The principle mainly involved is as follows:

[0035] Using the melting point characteristics of the substances, the melting points of the substances are FeCl2-674℃, FeCl3-306℃, NiCl2-1001℃, CaCl2-772℃, and the multi-component liquidus line projection diagram of the main substances in the mixed molten salt is as follows: Figure 1 shown.

[0036] Taking point A as an example, according to the color of the line on the right, it can be estimated that the melting point of point A is about 600°C. The composition of this point is approximately: FeCl2-30%, NiCl2-20%, FeCl3-50%.

[0037] The advantages of the mixed molten salt phase composed of this component are:

[0038] 1. By using low melting point substances such as FeCl3 and FeCl2, molten salt with lower temperature can be obtained; at the same time, in the chlorination process, due to the presence of FeCl2, FeCl3 and NiCl2, the chlorination process can be strengthened and the selective chlorination can be improved. The main process involved in the chlorination of nickel-iron alloy is Ni-Fe+Cl2→NiCl2+FeCl3, in which the chlorination of iron has a step-by-step reaction process of Fe→FeCl2→FeCl3.

[0039] Therefore, the process of molten salt chlorination of nickel-iron alloy by using the molten salt of the present invention is as follows: when nickel-iron alloy and chlorine are added to the molten salt, in the initial stage of the reaction, due to the presence of FeCl2 in the molten salt, the introduced chlorine (FeCl2+Cl2→FeCl3) can be quickly absorbed, thereby greatly improving the utilization rate of chlorine and avoiding chlorine leakage. As the reaction proceeds, the FeCl3 content in the molten salt increases, and at this time, there are multiple reactions of FeCl3+Ni-Fe→FeCl2+NiCl2, FeCl2+Cl2→FeCl3, and Fe+Cl2→FeCl3, with both the generation of ferrous chloride and the consumption of ferrous chloride to convert into FeCl3.

[0040] 2. In the initial stage of the reaction, due to the addition of nickel chloride, there is Ni-Fe+NiCl2→FeCl2+2Ni. Through this replacement reaction, the chlorination of iron in the nickel-iron alloy is promoted to ferrous chloride and the nickel in the nickel-iron alloy particles is converted into elemental nickel particles, thereby accelerating the consumption of chlorine (FeCl2+Cl2=FeCl3, Ni+Cl2=NiCl2).

[0041] 3. In addition, it was found during the experiment that the addition of calcium chloride can effectively reduce the content of ferrous chloride and nickel chloride in ferric chloride obtained by volatilization and condensation. The addition of calcium chloride may affect the melting point, viscosity, and phase composition of the molten salt, thereby playing the above role.

[0042] 4. At the same time, the molten salt is used for chlorination. After the chlorination is completed, the ferrous chloride and ferric chloride in the molten salt phase can be volatilized by vacuum distillation to obtain nickel-rich slag. The volatile gas phase is condensed to obtain iron chloride, which can be returned for use.

[0043] In step S100, the mixed salt only needs to contain FeCl2, FeCl3, NiCl2, and CaCl2 in a required molar ratio, and it is not required to directly mix the four simple substances of FeCl2, FeCl3, NiCl2, and CaCl2, that is, the mixed salt can be obtained by mixing the mixture with the mixture, or the mixture or the simple substance. For example, iron chloride (including FeCl2, FeCl3, CaCl2) and nickel chloride are mixed in proportion to obtain a mixture. Then the mixed salt is heated and melted to obtain a mixed molten salt.

[0044] S200: immersing the nickel-iron alloy in a mixed molten salt and introducing chlorine gas to perform chlorination roasting to obtain a volatile gas phase, wherein the reaction temperature is 650-900° C. and the reaction time is 60-200 min.

[0045] The nickel-iron alloy is immersed in the mixed molten salt, such as the liquid level of the mixed molten salt is 5-10cm higher than the nickel-iron alloy surface. The nickel-iron alloy of the present application embodiment is an alloy whose main components are nickel and iron, which is a smelting intermediate. In some embodiments, the nickel-iron alloy of the present application embodiment is a nickel-iron alloy obtained by pyrometallurgical smelting laterite nickel ore, such as the nickel-iron alloy obtained by RKEF method, rotary kiln direct reduction-magnetic separation process, rotary hearth furnace-melting furnace process. In some specific embodiments, the composition of the nickel-iron alloy is as shown in Table 1.

[0046] Table 1: Chemical composition of nickel-iron alloy (wt%)

[0047]

[0048] Chlorination roasting obtains a volatile gas phase and a molten salt phase. Referring to the above analysis on the role of the mixed molten salt, the component of the volatile gas phase is ferric chloride. The nickel in the nickel-iron alloy also enters the molten salt phase. CaCl2 also enters the molten salt phase, so the components of the molten salt phase are FeCl2, CaCl2, NiCl2, and CaCl2. The molten salt phase includes the main components of the mixed molten salt, which can be recycled and reused as needed.

[0049] The reaction temperature of chlorination roasting is 650-900℃, and the reaction time is 60-200min. The mixed molten salt itself has a relatively high temperature, so the temperature of the mixed molten salt can be fully utilized in chlorination roasting, and the chlorination roasting reaction temperature can be maintained at 650-900℃ by appropriate heating.

[0050] S300: performing a first condensation on the volatile gas phase to obtain a ferric chloride product.

[0051] In this step, the volatile gas phase is temperature-controlled and condensed to obtain the ferric chloride product, that is, the volatile gas phase is condensed to a temperature below the melting point of ferric chloride.

[0052] In the above-mentioned method of separating nickel and iron by chlorination roasting of nickel-iron alloy molten salt, a suitable compound is selected to melt to obtain a mixed molten salt, so that the melting point of the mixed molten salt is relatively low. Wherein, the presence of FeCl2, FeCl3, and NiCl2 can play a role in strengthening the chlorination process and improving selective chlorination, thereby providing the utilization rate of chlorine. Moreover, the addition of calcium chloride can effectively reduce the content of ferrous chloride and nickel chloride in ferric chloride obtained by volatilization and condensation. Thereby improving the purity of the ferric chloride product.

[0053] In some embodiments, the amount of chlorine added is calculated as 2-4 kg of chlorine per kg of alloy, and the volume concentration of chlorine is 10-60%.

[0054] This condition can provide chlorine gas of appropriate concentration and volume to meet the chlorine gas dosage requirement in chlorination roasting.

[0055] In some embodiments, in the step of condensing the volatile gas phase to obtain the ferric chloride product, the temperature of the first condensation is 100-300°C.

[0056] The melting point of FeCl3 is 306℃. Condensing the volatile gas phase to 100-300℃ can better condense the ferric chloride product.

[0057] In some embodiments, the step of melting the mixed salt to obtain the mixed molten salt comprises:

[0058] The mixed salt is heated to 600-850° C. to melt, thereby obtaining a mixed molten salt.

[0059] The mixed salt is melted at a relatively low temperature, reducing energy consumption.

[0060] In some embodiments, it also includes:

[0061] S400: The molten salt phase obtained by chlorination roasting is recycled as a mixed molten salt.

[0062] For the sake of convenience, the molten salt phase obtained by first chlorination roasting of the nickel-iron alloy and the mixed molten salt is called the first molten salt phase. The composition of the first molten salt phase meets the molar ratio requirements of FeCl2, FeCl3, NiCl2 and CaCl2. The first molten salt phase can be used as a mixed molten salt again, and this process is 1 cycle. According to actual conditions, the molten salt phase can be recycled 1 to 2 times.

[0063] In some embodiments, it also includes:

[0064] S410: performing reduced pressure distillation on the molten salt phase to obtain a distillate, wherein the distillation pressure is 2-5 kPa, the distillation temperature is 40-600° C., and the distillation time is 30-90 min.

[0065] When the molten salt phase is circulated and cannot be further circulated as a mixed molten salt, steps S410 to S430 may be performed.

[0066] In this step, the vacuum distillation is mainly used to separate nickel and iron in the molten salt, nickel chloride is used as distillation slag (crude nickel product), and iron chloride (FeCl2, FeCl3) is volatilized as distillate during the distillation process.

[0067] S420: The distillate is subjected to a second condensation to obtain iron chloride.

[0068] It is condensed by condensation to obtain solid iron chloride which is then returned for use.

[0069] S430: Mix the iron chloride and nickel chloride to obtain a mixed salt.

[0070] Since iron chloride lacks nickel chloride, nickel chloride must be supplemented to achieve the required mixed salt composition.

[0071] In some embodiments, the temperature of the second condensation is 100-400°C.

[0072] In some embodiments, the method further comprises extracting nickel from the residue obtained by vacuum distillation.

[0073] The residue obtained by vacuum distillation is mainly nickel chloride and ferrous chloride, in which the nickel content is relatively high, and nickel can be extracted.

[0074] The present application also provides the application of the above-mentioned method for separating nickel and iron by chlorination roasting of nickel-iron alloy molten salt in nickel smelting.

[0075] For example, laterite nickel ore is first reduced to obtain nickel-iron alloy, and the nickel-iron alloy is then separated from nickel and iron by the above-mentioned method of separating nickel and iron by chlorination roasting of nickel-iron alloy molten salt.

[0076] Embodiment 1:

[0077] (1) Prepare 1 kg of mixed salt in a molar ratio of FeCl2:FeCl3:NiCl2:CaCl2=10:2:1:0.8, mix thoroughly, and heat to melt it into molten salt.

[0078] (2) 300 g of nickel-iron alloy was added to molten salt, and 3 kg of chlorine gas was introduced into the molten salt according to the ratio of 1 kg of alloy, the volume concentration of chlorine gas was 30%, and the temperature was controlled at 650° C. during the chlorination process, and the reaction time was 120 min to obtain a volatile gas phase and a molten salt phase.

[0079] (3) The volatile gas phase is condensed by temperature control, and the temperature of the temperature control condensation is controlled at 100° C. to obtain a ferric chloride product. The ferric chloride is analyzed and tested, and the volatility of iron in the nickel-iron alloy is calculated to be 97.3%. The purity of the obtained ferric chloride is as high as 99.9%, and the nickel content cannot be detected.

[0080] Embodiment 2:

[0081] (1) Prepare 1 kg of mixed salt in a molar ratio of FeCl2:FeCl3:NiCl2:CaCl2=10:1:0.3:0.05, mix thoroughly, and heat to melt it into molten salt.

[0082] (2) 300 g of nickel-iron alloy was added to molten salt, and 3 kg of chlorine gas was introduced into the molten salt according to the ratio of 1 kg of alloy, the volume concentration of chlorine gas was 25%, the temperature was controlled at 730° C. during the chlorination process, and the reaction time was 90 min to obtain a volatile gas phase and a molten salt phase.

[0083] (3) The volatile gas phase is condensed under temperature control at 150° C. to obtain a ferric chloride product. The ferric chloride is analyzed and tested, and the volatility of iron in the nickel-iron alloy is calculated to be 99.4%. The purity of the obtained ferric chloride is as high as 99.9%, and the nickel content is 25 ppm.

[0084] Embodiment 3:

[0085] (1) Prepare 1 kg of mixed salt in a molar ratio of FeCl2:FeCl3:NiCl2:CaCl2=10:2:1:0.1, mix thoroughly, and heat to melt it into molten salt.

[0086] (2) 300 g of nickel-iron alloy was added to molten salt, and 3 kg of chlorine gas was introduced into the molten salt according to the ratio of 1 kg of alloy, the volume concentration of chlorine gas was 25%, the temperature was controlled at 730° C. during the chlorination process, and the reaction time was 90 min to obtain a volatile gas phase and a molten salt phase.

[0087] (3) The volatile gas phase is subjected to temperature-controlled condensation, and the temperature of the temperature-controlled condensation is controlled at 150° C. to obtain a ferric chloride product. The ferric chloride is analyzed and tested, and the volatility of iron in the nickel-iron alloy is calculated to be 99.4%. The purity of the obtained ferric chloride is as high as 99.9%, and the nickel content is not measured.

[0088] Embodiment 4:

[0089] (1) Prepare 1 kg of mixed salt in a molar ratio of FeCl2:FeCl3:NiCl2:CaCl2=10:2:1:0.8, mix thoroughly, and heat to melt it into molten salt.

[0090] (2) 300 g of nickel-iron alloy was added to molten salt, and 3 kg of chlorine gas was introduced into the molten salt according to the ratio of 1 kg of alloy, the volume concentration of chlorine gas was 25%, the temperature was controlled at 700° C. during the chlorination process, and the reaction time was 90 min to obtain a volatile gas phase and a molten salt phase.

[0091] (3) The volatile gas phase is subjected to temperature-controlled condensation, and the temperature of the temperature-controlled condensation is controlled at 150° C. to obtain a ferric chloride product. The ferric chloride is analyzed and tested, and the volatility of iron in the nickel-iron alloy is calculated to be 99.4%. The purity of the obtained ferric chloride is as high as 99.9%, and the nickel content is not measured.

[0092] (4) the molten salt obtained in step (3) is continued to be heated and melted, and then 300g of nickel-iron alloy is added to the molten salt, 3kg of chlorine is passed into 1kg of alloy, and the volume concentration of chlorine is 25%. The temperature is controlled to be 730°C during the chlorination process, and the reaction time is 90min to obtain a volatile gas phase and a molten salt phase. The volatile gas phase is subjected to temperature control condensation, and the temperature control condensation temperature is controlled at 150°C to obtain a ferric chloride product. Ferric chloride is analyzed and detected, and the volatility of iron in the nickel-iron alloy is calculated to be 99.7%, and the obtained ferric chloride purity is up to 99.9%, and the content of nickel is 3ppm.

[0093] (5) the molten salt obtained in step (4) is continued to be heated and melted, and then 300g of nickel-iron alloy is added to the molten salt, 3kg of chlorine is passed into 1kg of alloy, and the volume concentration of chlorine is 25%. The temperature is controlled to be 730°C during the chlorination process, and the reaction time is 90min to obtain a volatile gas phase and a molten salt phase. The volatile gas phase is subjected to temperature control condensation, and the temperature control condensation temperature is controlled at 150°C to obtain a ferric chloride product. Ferric chloride is analyzed and detected, and the volatility of iron in the nickel-iron alloy is calculated to be 98.5%, and the obtained ferric chloride purity is up to 99.9%, and the content of nickel is 40ppm.

[0094] (6) The molten salt in step (5) is subjected to vacuum distillation; the distillation pressure is controlled at 3.8 kPa, the distillation temperature is controlled at 550° C., and the distillation time is controlled at 80 min. The condensation temperature of the volatiles volatilized by vacuum distillation is controlled at 150° C., and the obtained condensate is mainly composed of FeCl3, wherein the contents of FeCl3 and FeCl2 are 93.4% and 4.9% respectively. The NiCl2 content in the vacuum distillation residue is 94.7%.

[0095] Comparative Example 1:

[0096] (1) Prepare 1 kg of mixed salt in a molar ratio of FeCl2:FeCl3:NiCl2=10:2:1, mix thoroughly, and heat to melt it into molten salt.

[0097] (2) 300 g of nickel-iron alloy was added to molten salt, and 3 kg of chlorine gas was introduced into the molten salt according to the ratio of 1 kg of alloy, the volume concentration of chlorine gas was 25%, the temperature was controlled at 730° C. during the chlorination process, and the reaction time was 90 min to obtain a volatile gas phase and a molten salt phase.

[0098] (3) The volatile gas phase is condensed by temperature control, and the temperature of the temperature control condensation is controlled at 150° C. to obtain a ferric chloride product. The ferric chloride is analyzed and tested, and the volatility of iron in the nickel-iron alloy is calculated to be 98.1%, the purity of the obtained ferric chloride is 99.1%, and the nickel content is 0.3%.

[0099] Comparative Example 2:

[0100] 1kg of nickel-iron alloy was added into a horizontal tube furnace (quartz tube was used as furnace tube), the roasting temperature was 650°C, and the amount of chlorine introduced was 3.5 times the mass of the nickel-iron alloy in the horizontal tube furnace, so that the iron in the alloy was directly volatilized (stopped after no obvious volatiles were found in the reaction zone, and the time was 193min), and then the volatile gas phase was condensed, and the condensation temperature was controlled at 100°C. The chlorinated slag in the chlorination furnace was analyzed and tested, indicating that the chlorination volatility of the iron in the alloy was 87.49%. The ferric chloride product collected by condensation was tested, and the purity of ferric chloride was 97.90%.

[0101] Comparative Example 3:

[0102] (1) Prepare 1 kg of mixed salt in a molar ratio of FeCl2:FeCl3=10:1, mix thoroughly, and heat to melt it into molten salt.

[0103] (2) 300 g of nickel-iron alloy was added to molten salt, 3 kg of chlorine was introduced into the molten salt according to the ratio of 1 kg of alloy, the volume concentration of chlorine was 25%, the temperature was controlled at 650° C., the reaction time was 120 min, and a volatile gas phase and a molten salt phase were obtained. The volatility of iron in the nickel-iron alloy was calculated to be 93.5%.

[0104] The purity of the ferric chloride in the above Examples 1 to 4 is as high as 99.9%, which is higher than the purity of the ferric chloride in Comparative Example 1, and the nickel content is also significantly lower than the nickel content in Comparative Example 1. It can be seen that the addition of calcium chloride can effectively reduce the content of ferrous chloride and nickel chloride in the ferric chloride obtained by volatilization and condensation, and the method for separating nickel and iron by chlorination roasting of nickel-iron alloy molten salt of the present application can improve the purity of the ferric chloride product.

[0105] The chlorine gas feed amount of the above embodiments 1 to 4 is 0.5 times less than the chlorine gas feed amount of comparative example 2, and the method for separating nickel and iron by chlorination roasting of nickel-iron alloy molten salt of the present application can improve the utilization rate of chlorine gas.

[0106] The volatilization rate of iron in the nickel-iron alloys of the above-mentioned Examples 1 to 4 is higher than that in the nickel-iron alloy of Comparative Example 3. It can be seen that the addition of ferric chloride in the molten salt phase can increase the volatilization rate of iron, and the method of separating nickel and iron by chlorination roasting of nickel-iron alloy molten salt of the present application can increase the volatilization rate of iron.

[0107] The above technical solutions of the present invention are only preferred embodiments of the present invention, and the patent scope of the present invention is not limited thereto. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied 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 by chlorination roasting of nickel-iron alloy molten salt, characterized in that: The following steps are involved: Melting the mixed salt to obtain a mixed molten salt, wherein the mixed salt includes FeCl2, FeCl3, NiCl2, and CaCl2, and the molar ratio of FeCl2, FeCl3, NiCl2, and CaCl2 is 10:(2-1):(1-0.3):(0.1-0.05); The nickel-iron alloy is immersed in a mixed molten salt and chlorine gas is introduced to perform chlorination roasting to obtain a volatile gas phase; wherein the reaction temperature is 650-900° C. and the reaction time is 60-200 min; The volatile gas phase is subjected to a first condensation to obtain a ferric chloride product.

2. The method according to claim 1, characterized in that The amount of chlorine added is calculated as 2-4 kg of chlorine per kg of alloy, and the volume concentration of the chlorine is 10-60%.

3. The method according to claim 1, characterized in that In the step of condensing the volatile gas phase to obtain the ferric chloride product, the temperature of the first condensation is 100-300°C.

4. The method according to claim 1, characterized in that The step of melting the mixed salt to obtain the mixed molten salt comprises: The mixed salt is heated to 600-850° C. to melt, thereby obtaining a mixed molten salt.

5. The method according to claim 1, characterized in that The molar ratio of FeCl2, FeCl3, NiCl2 and CaCl2 is 10:2:1:0.

8.

6. The method according to claim 1, characterized in that Also includes: The molten salt phase obtained by chlorination roasting is recycled as mixed molten salt.

7. The method according to claim 6, characterized in that Also includes: The molten salt phase is subjected to reduced pressure distillation to obtain a distillate, wherein the distillation pressure is 2-5 kPa, the distillation temperature is 400-600° C., and the distillation time is 30-90 min; The distillate is subjected to a second condensation to obtain iron chloride; The iron chloride and nickel chloride are mixed to obtain a mixed salt.

8. The method according to claim 7, characterized in that The temperature of the second condensation is 100-400°C.

9. The method according to claim 7, characterized in that: The method also includes extracting nickel from the residue obtained by the reduced pressure distillation.

10. Use of the method for separating nickel and iron by chlorination roasting of nickel-iron alloy molten salt according to any one of claims 1 to 9 in nickel smelting.

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