Method for preparing nickel chloride by using ferro-nickel alloy

Abstract

The invention relates to the field of alloy separation and resource utilization, and provides a method for preparing nickel chloride from a nickel-iron alloy. The method comprises the following steps: contacting the ferro-nickel alloy with chlorine gas and auxiliary agent gas, and carrying out chloridizing roasting to obtain a volatile gas phase; wherein the molar ratio of the chlorine element of the chlorine to the nickel element in the nickel-iron alloy is (2-6): 1, the auxiliary gas at least comprises oxygen, and the molar ratio of the total amount of the oxygen element in the auxiliary gas to the iron element in the nickel-iron alloy is (1.6-2): 1; the temperature of the chloridizing roasting is 750 to 1000 DEG C; and collecting the volatile gas phase, and cooling to obtain nickel chloride. According to the method, chlorine is selectively chlorinated, nickel chloride is directly separated, and iron does not need to be chlorinated in the reaction, so that the use amount of chlorine is reduced. Moreover, nickel chloride is separated in the form of gas, the nickel element is easy and convenient to recycle, the purity is high, and recycling of the nickel element is facilitated.

Description

Technical Field

[0001] The invention relates to the field of alloy separation and resource utilization, and in particular to a method for preparing nickel chloride by utilizing nickel-iron alloy. 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] At present, the separation of nickel-iron alloy includes the following methods, such as chlorination and volatilization of iron and nickel, and separation based on the boiling point or boiling point difference of the chlorides of the two. Another example is that iron is chlorinated and volatilized, and nickel is retained in the slag for separation.

[0004] The above methods all have great limitations on the separation of nickel and require more chlorine. Summary of the invention

[0005] The main purpose of the present invention is to provide a method for preparing nickel chloride by using nickel-iron alloy, so as to solve the technical problems that nickel-iron alloy has great restrictions on the separation of nickel and requires more chlorine.

[0006] To achieve the above object, the present invention provides a method for preparing nickel chloride using nickel-iron alloy, comprising the following steps:

[0007] The nickel-iron alloy is contacted with chlorine gas and auxiliary gas, and chlorination roasting is performed to obtain a volatile gas phase. The molar ratio of the chlorine element in the chlorine gas to the nickel element in the nickel-iron alloy is 2 to 6:1, the auxiliary gas at least includes oxygen, and the molar ratio of the total amount of oxygen element in the auxiliary gas to the iron element in the nickel-iron alloy is 1.6 to 2:1. The temperature of the chlorination roasting is 750-1000°C.

[0008] The volatile gas phase is collected and cooled to obtain nickel chloride.

[0009] According to an embodiment of the present application, the auxiliary gas also includes carbon dioxide.

[0010] According to an embodiment of the present application, the molar ratio of the carbon dioxide to the oxygen is ≤1:20.

[0011] According to an embodiment of the present application, the temperature of the chlorination roasting is 800-950°C.

[0012] According to an embodiment of the present application, in the step of contacting the nickel-iron alloy with chlorine and auxiliary gas for chlorination roasting, the chlorine is preheated to 80-150° C. before contacting the nickel-iron alloy. The auxiliary gas is preheated to 300-600° C. before contacting the nickel-iron alloy.

[0013] According to an embodiment of the present application, in the step of contacting the nickel-iron alloy with chlorine, oxygen and carbon dioxide gases for chlorination roasting, the nickel-iron alloy is preheated to 600-900° C. under a protective gas atmosphere and then contacted with chlorine, oxygen and carbon dioxide gases.

[0014] According to an embodiment of the present application, the reaction time of the chlorination roasting is 1 to 4 hours.

[0015] According to an embodiment of the present application, the chlorination roasting is carried out under a pressure condition of -0.08 to -0.16 kPa.

[0016] According to an embodiment of the present application, in the step of collecting the volatile gas phase and cooling it, the cooling temperature is 100-200°C.

[0017] According to an embodiment of the present application, the method further includes collecting the roasting slag produced in the chlorination roasting step, wherein the roasting slag includes iron oxide.

[0018] In the above-mentioned method for preparing nickel chloride using nickel-iron alloy, a mixed gas of chlorine, oxygen and carbon dioxide is used for roasting, and by controlling the ratio of each gas and its reaction temperature, the iron element in the nickel-iron alloy is oxidized and converted into ferric oxide and left in the slag, and the nickel element is converted into nickel chloride and volatilized and separated, thereby preparing nickel chloride. This method selectively chlorinates the chlorine element and directly separates the nickel chloride, and it is not necessary to chlorinate the iron element simultaneously in the reaction, thereby reducing the usage of chlorine. Moreover, nickel chloride is separated in gaseous form, and compared with the mode in which the nickel element is separated from the iron element in a solid, the nickel element is simple and convenient to recycle, and the purity is higher, which is more conducive to the recycling of the nickel element. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] 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.

[0020] Figure 1 The present invention is a flowchart of a method for preparing nickel chloride using nickel-iron alloy according to an embodiment of the present application.

[0021] 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

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] The present invention provides a method for preparing nickel chloride using nickel-iron alloy. Figure 1 , including the following steps:

[0027] S100: contacting the nickel-iron alloy with chlorine gas and auxiliary gas, and performing chlorination roasting to obtain a volatile gas phase; wherein the molar ratio of the chlorine element in the chlorine gas to the nickel element in the nickel-iron alloy is 2-6:1, the auxiliary gas at least includes oxygen, and the molar ratio of the total amount of oxygen element in the auxiliary gas to the iron element in the nickel-iron alloy is 1.6-2:1; the temperature of the chlorination roasting is 750-1000°C.

[0028] The nickel-iron alloy of the embodiment of the present application is an alloy whose main components are nickel and iron, and is a smelting intermediate. In some embodiments, the nickel-iron alloy of the embodiment of the present application is a nickel-iron alloy obtained by pyrometallurgical smelting of laterite nickel ore, such as a nickel-iron alloy obtained by RK-EF method, 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. The following embodiments 1 to 4 all use this kind of nickel-iron alloy as raw material.

[0029] Table 1 Chemical composition of nickel-iron alloy (wt%)

[0030]

[0031] Theoretically, as can be seen from Table 2, iron is more likely to react with chlorine and oxygen, that is, iron is more active than nickel in chlorine and oxygen atmospheres, and nickel chloride is more difficult to be oxidized by oxygen to be converted into oxides and chlorine than ferric chloride, and iron oxide is difficult to be chlorinated (the reverse reaction of Formula 6), while nickel oxide can be chlorinated (the reverse reaction of Formula 5).

[0032] Table 2 Reaction Gibbs free energy changes

[0033]

[0034] Table 2 shows that: ① iron and nickel can both react with chlorine, ② but nickel chloride cannot react with oxygen to form nickel oxide, while ferric chloride can react with oxygen to form iron oxide and chlorine. According to ① and ②, it can be determined that in the presence of chlorine and oxygen, iron preferentially combines with oxygen to form iron oxide, and nickel preferentially combines with chlorine to form nickel chloride. Based on this, the present application proposes a method for preparing nickel chloride using nickel-iron alloy.

[0035] The present application proposes to use a mixed gas of chlorine and auxiliary gas as a chlorinating agent for chlorination roasting treatment of nickel-iron alloy, by controlling the ratio of each gas and its reaction conditions, the iron in the alloy is oxidized and converted into ferric oxide and left in the slag under the system, and nickel is converted into nickel chloride and volatilized. In this process, the ratio control of chlorine and oxygen in the roasting atmosphere is particularly important. In certain embodiments, the reaction system is maintained at a higher temperature by preheating means combined with the reaction heat release, so as to be more conducive to the conversion of the reaction.

[0036] The auxiliary gas may include only oxygen or other gases such as carbon dioxide. In either case, the molar ratio of the total amount of oxygen in the auxiliary gas to the iron in the nickel-iron alloy is 1.6-2:1.

[0037] Taking the auxiliary gas including oxygen and carbon dioxide as an example, the nickel-iron alloy is usually contacted with chlorine, oxygen and carbon dioxide in a reaction vessel, such as a reactor. Exemplarily, after the nickel-iron alloy is placed in the reactor, chlorine, oxygen and carbon dioxide are introduced into the reactor so that the nickel-iron alloy is in contact with the above-mentioned gases. Among them, chlorine, oxygen and carbon dioxide are introduced separately, or added at the same time, or some gases are pre-mixed and added. Exemplarily, oxygen and carbon dioxide are pre-mixed and added in a mixed manner, and chlorine is introduced alone.

[0038] The addition amounts of the nickel-iron alloy and the four gases, chlorine, oxygen and carbon dioxide, meet the following conditions: the addition amount of the mixed gas of oxygen and / or carbon dioxide is 1.6 to 2 times the number of iron atoms in the alloy in terms of the number of oxygen atoms in the mixed gas, the addition amount of chlorine is 2 to 6 times the number of nickel atoms in the alloy in terms of the number of chlorine atoms, and the chlorination roasting temperature is controlled to be 750 to 1000°C, such as 750°C, 760°C, 800°C, 830°C, 900°C, 953°C, and 1000°C.

[0039] In the chlorination roasting reaction, gaseous substances and solid substances are generated. The gaseous substances are volatile gas phases, and the main component is nickel chloride. The solid substances are roasting slag, and the roasting slag includes iron oxide. Therefore, the roasting slag can be used as a raw material for ironmaking after washing.

[0040] S200: collecting the volatile gas phase, cooling it, and obtaining nickel chloride.

[0041] The volatile gas phase is collected and cooled to obtain the nickel chloride product.

[0042] In the above-mentioned method for preparing nickel chloride using nickel-iron alloy, a mixed gas of chlorine, oxygen and carbon dioxide is used for roasting, and by controlling the ratio of each gas and the reaction temperature, the iron element in the nickel-iron alloy is oxidized to ferric oxide and remains in the slag, and the nickel element is converted into nickel chloride and volatilized and separated, thereby preparing nickel chloride. This method selectively chlorinates the chlorine element and directly separates the nickel chloride, and there is no need to chlorinate the iron element at the same time in the reaction, thereby reducing the amount of chlorine used.

[0043] Moreover, nickel chloride is separated in gaseous form, and compared with the way in which nickel is separated from iron in a solid, the present application directly recycles nickel with high value and high market capacity, and nickel recovery is simple and convenient, with high purity, which is more conducive to the recycling of nickel. In addition, since the content of nickel is generally lower than the content of iron in nickel-iron alloy, the chlorine required for this method of reaction is relatively small, which reduces production costs. In addition, the existing chlorination roasting process processes nickel-iron alloy process, if the chlorination volatilization of nickel is to be realized, it is mostly accompanied by the chlorination of iron and volatilization together, and then a complicated process is required to separate ferric chloride and nickel chloride.

[0044] In some embodiments, the molar ratio of the chlorine element in the chlorine gas to the nickel element in the nickel-iron alloy is 2-6:1, and the molar ratio of the oxygen element in the total amount of the oxygen and the carbon dioxide gas to the iron element in the nickel-iron alloy is 1.6-2:1.

[0045] Under this condition, the addition amount of chlorine, oxygen and carbon dioxide is more appropriate. The addition amount of chlorine is less under the basic conditions of chlorination roasting, which saves the use of chlorine and obtains nickel chloride with higher purity.

[0046] In some embodiments, the molar ratio of the carbon dioxide to the oxygen is ≤ 1:20. In other words, in general, the molar ratio of the carbon dioxide gas to the oxygen is 0:20-1:20.

[0047] Under this condition, the ratio of oxygen and carbon dioxide gas is more appropriate, and the obtained nickel chloride has higher purity.

[0048] In some more specific embodiments, when the auxiliary gas includes CO 2 When the reaction temperature of the chlorination roasting step is adjusted to above 800°C, Fe+CO 2 =FeO+CO reaction is more conducive to the selective chlorination of nickel.

[0049] In some embodiments, the chlorination roasting temperature is 800-950°C.

[0050] In some embodiments, in the step of contacting the nickel-iron alloy with chlorine and auxiliary gas for chlorination roasting, the chlorine is preheated to 80-150°C and then contacted with the nickel-iron alloy; the auxiliary gas is preheated to 300-600°C and then contacted with the nickel-iron alloy.

[0051] After the chlorine, oxygen and carbon dioxide gases are preheated, they are introduced into the reaction vessel, which reduces their influence on the reaction temperature. The reaction temperature of the reaction vessel is relatively easier to stably control, so that the reaction system is always maintained at a higher temperature, which is more conducive to the conversion of the reaction.

[0052] At the same time, because chlorine is highly corrosive, especially when the temperature is too high, the corrosiveness is even stronger. Therefore, it is not easy to preheat it to too high a temperature to avoid corrosion of the preheating container or the delivery pipeline. After the chlorine is preheated to 80-150℃, it is input into the reaction container. The reaction container is generally designed for the corrosiveness of chlorine, so the impact is relatively small.

[0053] In some embodiments, in the step of contacting the nickel-iron alloy with chlorine, oxygen and carbon dioxide gases for chlorination roasting, the nickel-iron alloy is preheated to 600-900° C. under a protective gas atmosphere and then contacted with chlorine, oxygen and carbon dioxide gases.

[0054] Under this condition, it is also beneficial to keep the reaction system at a higher temperature, which is more conducive to the conversion of the reaction. When preheating the nickel-iron alloy, nitrogen or argon is introduced into the furnace to achieve a protective gas atmosphere for the preheating.

[0055] In some embodiments, the reaction time of the chlorination roasting is 1 to 4 hours.

[0056] In some embodiments, the chlorination roasting is performed under a pressure of -0.08 to -0.16 kPa. Thus, the chlorination roasting is performed under a slightly negative pressure to prevent gas from escaping.

[0057] In some embodiments, see Figure 1 In the step of collecting the volatile gas phase and cooling, the cooling temperature is 100-200° C. Under this condition, a small amount of chlorine in the volatile gas phase is still in a gaseous state, and nickel chloride is solid and can be separated and purified.

[0058] In some embodiments, see Figure 1 , and also includes collecting the roasting slag produced in the chlorination roasting step, wherein the roasting slag includes iron oxide.

[0059] The technical solution of the present application is described below in conjunction with specific embodiments.

[0060] Embodiment 1:

[0061] The nickel-iron alloy is placed in a reaction furnace, nitrogen as a protective gas is introduced, and the temperature is raised to preheat 500°C. Chlorine is preheated to 90°C and oxygen is preheated to 550°C. The preheated oxygen is added in an amount of 1.7 times the number of iron atoms in the alloy according to the number of oxygen atoms, and chlorine is added in an amount of 3 times the number of nickel atoms in the alloy according to the number of chlorine atoms (the gas introduction time is 2h), the chlorination reaction temperature is controlled to 900°C, and the negative pressure in the furnace is maintained at -0.1kPa. After the roasting is completed, roasting slag and gaseous nickel chloride are obtained. The temperature of the temperature control condensation during the condensation and crystallization process of gaseous nickel chloride is controlled at 150°C to obtain a solid nickel chloride product. The roasting slag and solid nickel chloride products are analyzed and tested. The ferric oxide content in the roasting slag is 95.3% and the nickel content is 2.5%; the nickel chloride content of the solid nickel chloride product is 97.4%.

[0062] Embodiment 2:

[0063] Place the nickel-iron alloy in a reactor, introduce protective nitrogen gas, and preheat to 500°C. Preheat chlorine to 90°C, and add carbon dioxide and oxygen at a rate of CO 2 :O 2 The molar ratio is 1:20 and mixed, and preheated to 550°C. The preheated carbon dioxide and oxygen are added in an amount of 1.7 times the number of iron atoms in the alloy according to the number of oxygen atoms, and chlorine is added to the chlorination furnace in an amount of 3 times the number of nickel atoms in the alloy according to the number of chlorine atoms (the gas introduction time is 2h), the chlorination reaction temperature is controlled to 900°C, and the negative pressure in the furnace is maintained at -0.1kPa. After roasting, roasting slag and gaseous nickel chloride are obtained. The temperature of the temperature-controlled condensation during the condensation and crystallization process of gaseous nickel chloride is controlled at 150°C to obtain a solid nickel chloride product. The roasting slag and solid nickel chloride products are analyzed and tested. The ferric oxide content in the roasting slag is 96.1% and the nickel content is 1.8%; the nickel chloride content of the solid nickel chloride product is 98.1%.

[0064] Embodiment 3:

[0065] Place the nickel-iron alloy in a reactor, introduce protective nitrogen gas, and preheat to 500°C. Preheat chlorine to 90°C, and add carbon dioxide and oxygen at a rate of CO 2 :O 2 The molar ratio is 1:20 and mixed, and preheated to 550°C. The preheated carbon dioxide and oxygen are added in an amount of 1.8 times the number of iron atoms in the alloy according to the number of oxygen atoms, and chlorine is added to the chlorination furnace in an amount of 3 times the number of nickel atoms in the alloy according to the number of chlorine atoms (the gas introduction time is 2h), the chlorination reaction temperature is controlled to 1000°C, and the negative pressure in the furnace is maintained at -0.1kPa. After roasting, roasting slag and gaseous nickel chloride are obtained. The temperature of the temperature-controlled condensation during the condensation and crystallization process of gaseous nickel chloride is controlled at 150°C to obtain a solid nickel chloride product. The roasting slag and solid nickel chloride products are analyzed and tested. The ferric oxide content in the roasting slag is 97.6% and the nickel content is 1.3%; the nickel chloride content of the solid nickel chloride product is 98.7%.

[0066] Embodiment 4:

[0067] Place the nickel-iron alloy in a reactor, introduce protective nitrogen gas, and preheat to 500°C. Preheat chlorine to 90°C, and add carbon dioxide and oxygen at a rate of CO 2 :O 2The molar ratio is 1:20 and mixed, and preheated to 550°C. The preheated carbon dioxide and oxygen are added in an amount of 1.8 times the number of iron atoms in the alloy according to the number of oxygen atoms, and chlorine is added to the chlorination furnace in an amount of 3 times the number of nickel atoms in the alloy according to the number of chlorine atoms (the gas introduction time is 2h), the chlorination reaction temperature is controlled to 1000°C, and the negative pressure in the furnace is maintained at -0.1kPa. After roasting, roasting slag and gaseous nickel chloride are obtained. The temperature of the temperature-controlled condensation during the condensation and crystallization process of gaseous nickel chloride is controlled at 150°C to obtain a solid nickel chloride product. The roasting slag and solid nickel chloride products are analyzed and tested. The ferric oxide content in the roasting slag is 98.8% and the nickel content is 0.3%; the nickel chloride content of the solid nickel chloride product is 98.3%.

[0068] 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 preparing nickel chloride using nickel-iron alloy, characterized in that: The following steps are involved: The nickel-iron alloy is contacted with chlorine gas and auxiliary gas, and chlorination roasting is performed to obtain a volatile gas phase; wherein the molar ratio of the chlorine element in the chlorine gas to the nickel element in the nickel-iron alloy is 2-6:1, the auxiliary gas at least includes oxygen, and the molar ratio of the total amount of oxygen element in the auxiliary gas to the iron element in the nickel-iron alloy is 1.6-2:1; the temperature of the chlorination roasting is 750-1000°C; The volatile gas phase is collected and cooled to obtain nickel chloride.

2. The method for preparing nickel chloride using nickel-iron alloy according to claim 1, characterized in that: The auxiliary gas also includes carbon dioxide.

3. The method for preparing nickel chloride using nickel-iron alloy according to claim 2, characterized in that: The molar ratio of the carbon dioxide to the oxygen is ≤1:

20.

4. The method for preparing nickel chloride using nickel-iron alloy according to claim 1, characterized in that: The temperature of the chlorination roasting is 800-950°C.

5. The method for preparing nickel chloride using nickel-iron alloy according to claim 1, characterized in that: In the step of contacting the nickel-iron alloy with chlorine and auxiliary gas for chlorination roasting, the chlorine is preheated to 80-150° C. and then contacted with the nickel-iron alloy; the auxiliary gas is preheated to 300-600° C. and then contacted with the nickel-iron alloy.

6. The method for preparing nickel chloride using nickel-iron alloy according to claim 1, characterized in that: In the step of contacting the nickel-iron alloy with chlorine, oxygen and carbon dioxide gases for chlorination roasting, the nickel-iron alloy is preheated to 600-900° C. in an atmosphere of protective gas and then contacted with chlorine, oxygen and carbon dioxide gases.

7. The method for preparing nickel chloride using nickel-iron alloy according to claim 1, characterized in that: The reaction time of the chlorination roasting is 1 to 4 hours.

8. The method for preparing nickel chloride using nickel-iron alloy according to claim 1, characterized in that: The chlorination roasting is carried out under a pressure condition of -0.08 to -0.16 kPa.

9. The method for preparing nickel chloride using nickel-iron alloy according to claim 1, characterized in that: In the step of collecting the volatile gas phase and cooling it, the cooling temperature is 100-200°C.

10. The method for preparing nickel chloride using nickel-iron alloy according to any one of claims 1 to 9, characterized in that: The method also includes collecting roasting slag produced in the chlorination roasting step, wherein the roasting slag includes iron oxide.

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