Process for producing raw material for nickel-matrix material

Abstract

An aspect of the present application provides a method of preparing a raw material for preparing a nickel matte, the method using sodium sulfate (Na2SO4) instead of sulfur as a sulfuration raw material, thereby making temperature control easier and improving efficiency in preparing a nickel matte, compared to a conventional process.

Description

Technical Field

[0001] This invention relates to a method for preparing raw materials for nickel matte. Background Technology

[0002] The general process for preparing nickel matte involves two steps: sulfidation and de-ironization. Sulfidation typically uses sulfur (S) to convert nickel in ferronickel into nickel sulfide (Ni3S2), thus enriching the nickel in the matte layer. De-ironization, on the other hand, involves oxidizing the iron in ferronickel (FeNi) to iron oxide (II) and removing the slag layer containing iron oxide (II).

[0003] However, this existing nickel matte preparation process using sulfur has many technical problems, such as the need for multi-step iron removal processes, or the need for temperature control of the entire process due to the physical properties of liquid sulfur. Summary of the Invention

[0004] (a) Technical problems to be solved One aspect of the present invention is to provide a method for preparing raw materials for nickel matte preparation, which can improve the nickel recovery rate and nickel yield during the preparation of nickel matte.

[0005] The technical problem addressed by this invention is not limited to the above description. Those skilled in the art will readily understand the additional technical problems of this invention from the overall content of this specification.

[0006] (II) Technical Solution A method for preparing raw materials for nickel matte according to one aspect of the present invention may include: a step of preparing a molten metal master alloy containing nickel (Ni) and iron (Fe); and a step of adding sodium sulfate (Na2SO4) to the molten metal to obtain raw materials for preparing nickel matte (Ni3S2), wherein the raw materials may contain nickel, iron and sulfur (S).

[0007] In the above steps for obtaining raw materials for nickel matte preparation, the amount of sodium sulfate added, based on the total weight of the molten metal of the master alloy, can be greater than 15% by weight and less than 40% by weight.

[0008] The molten metal of the aforementioned master alloy may contain less than 50% by weight of nickel.

[0009] The above-mentioned raw materials may contain 0.50% to 30% sulfur based on the total weight of the raw materials.

[0010] The aforementioned raw materials may contain 20% to 70% nickel based on the total weight of the raw materials.

[0011] The aforementioned raw materials may contain 4.0% to 75% iron based on the total weight of the raw materials.

[0012] The weight ratio of iron to nickel in the above raw materials can be from 0.050 to 2.8.

[0013] (III) Beneficial Effects In preparing raw materials for nickel matte, this invention uses sodium sulfate (Na2SO4) instead of sulfur (S) as the sulfidation raw material, thereby providing a de-ironization reaction that is easier to control in terms of temperature compared to existing processes.

[0014] When using the raw materials for nickel matte preparation according to the present invention, the number of subsequent separate iron removal processes can be reduced to prepare nickel matte, thereby improving process efficiency.

[0015] Furthermore, in this case, sodium sulfate, which is a waste byproduct, can be used as a sulfidation raw material, thereby saving waste costs and thus being economically advantageous. Attached Figure Description

[0016] Figure 1 This shows the thermodynamic calculation results of the compositional changes during the nickel sulfidation reaction.

[0017] Figure 2 This is a simplified schematic diagram illustrating existing processes for preparing nickel matte using sulfur (S) as a raw material and processes for preparing nickel matte using sodium sulfate (Na2SO4) as a raw material.

[0018] Figure 3 This is a simplified schematic diagram illustrating existing iron removal processes using sulfur and those using sodium sulfate.

[0019] Figure 4 This is a graph in which the weight ratio of sodium sulfate to molten metal of the master alloy is used as the x-axis, and the concentration of nickel in the raw material and the nickel recovery rate are used as the y-axis. Best practice

[0020] The preferred embodiments of the present invention will now be described. However, the embodiments of the present invention can be modified in many other ways, and the scope of the present invention is not limited to the embodiments described below.

[0021] In this specification, unless otherwise specifically stated to the contrary, the terms "comprising" or "including" mean that other constituent elements may be included, rather than excluding other constituent elements.

[0022] Furthermore, in the specification of this invention, unless otherwise specified, the unit % represents weight.

[0023] As mentioned above, the nickel matte preparation process typically requires a sulfurization process using sulfur (S) and a de-ironization process. In this case, the reaction formula in the sulfurization process using sulfur (S) is as follows [Reaction Formula 1], and the reaction formula in the de-ironization process is as follows [Reaction Formula 2].

[0024] [Reaction Formula 1] [Reaction 2] However, this nickel matte preparation process using sulfur requires multiple iron removal steps, resulting in very poor operational control flexibility during long-term blowing operations, such as imbalance of heat and material balance and damage to refractory materials.

[0025] Furthermore, considering the melting point and high-temperature viscosity of liquid sulfur, it is important to control the temperature between 130°C and 150°C, which may also lead to a decrease in fluidity during the process.

[0026] To address the problems of existing processes, the inventors of this invention discovered through thermodynamic calculations and repeated experiments that using sodium sulfate (Na₂SO₄) instead of sulfur (S) as a raw material for nickel matte preparation can reduce the number of iron removal processes in the overall nickel matte preparation process. Furthermore, under these conditions, the nickel recovery rate and nickel production output can be improved.

[0027] Figure 1 This shows the thermodynamic calculation results illustrating the compositional changes during the nickel sulfidation reaction. At this point, Figure 1 -(A) is the case where liquid sulfur (S) is used. Figure 1 -(B) represents the case using sodium sulfate (Na2SO4). Therefore, when using liquid sulfur, the nickel content after the sulfidation reaction is only 10% by weight, while when using sodium sulfate, the nickel content is 70% by weight. This indicates that the relatively high nickel content when using sodium sulfate can be enriched in the raw material for nickel matte preparation. Based on this thermodynamic calculation result, the inventors of this invention have invented a method for preparing the raw material for nickel matte preparation as described below.

[0028] That is, a method for preparing raw materials for nickel matte according to one embodiment of the present invention may include: a step of preparing a molten metal master alloy containing nickel (Ni) and iron (Fe); and a step of adding sodium sulfate (Na2SO4) to the molten metal to obtain raw materials for preparing nickel matte (Ni3S2), wherein the raw materials may contain nickel, iron and sulfur (S).

[0029] According to one embodiment of the present invention, the molten metal master alloy can be obtained by molten iron and nickel alloy. As an example, this molten metal master alloy can originate from the ferronickel process. The ferronickel process refers to the process of preparing ferronickel alloys through dry smelting of nickel oxide ore. Originating from the ferronickel process can refer to the melt as an intermediate product or the melt as a final product in the ferronickel process, or it can be a mixture of both. However, it is not necessarily limited to this.

[0030] According to one embodiment of the present invention, the molten metal master alloy may contain 10% by weight or more and less than 50% by weight of nickel. That is, one embodiment of the present invention can provide raw materials for nickel matte preparation by increasing the nickel content from molten metal master alloy with a nickel content of less than 50% by weight. Furthermore, in one example of the present invention, nickel matte with improved nickel recovery rate and nickel production can be obtained by preparing nickel matte from such raw materials. In another embodiment, the molten metal master alloy may contain less than 40% nickel, and in yet another example, it may contain less than 30% nickel. On the other hand, when the nickel content of the molten metal master alloy is less than 20% by weight, the deferrore reaction time increases, resulting in a decrease in efficiency when preparing raw materials for nickel matte preparation. Therefore, according to one embodiment of the present invention, the molten metal master alloy may contain 10% by weight or more of nickel. According to another embodiment, the nickel content of the molten metal master alloy may be 20% by weight or more or 25% by weight or more.

[0031] According to one embodiment of the present invention, after preparing the above-mentioned molten metal master alloy, sodium sulfate (Na2SO4) can be added to the molten metal to obtain raw materials for the preparation of nickel matte (Ni3S2).

[0032] Through the aforementioned steps, the nickel component in the molten metal of the master alloy can undergo a sulfidation reaction with sodium sulfate, thereby enriching it in the raw material for nickel matte preparation as nickel(II) sulfide (Ni3S2), and the iron component in the molten metal of the master alloy can be oxidized to iron(II) oxide (FeO). The reaction formula for this sulfidation / de-ironization composite reaction is shown in [Reaction Formula 3] below.

[0033] [Reaction 3] That is, as mentioned above, existing methods of adding sulfur only produce a sulfidation reaction, while when sodium sulfate is used to obtain the raw material for preparing nickel matte according to the present invention, the sulfidation reaction of nickel can be accompanied by an iron oxidation reaction. Therefore, the method for preparing the raw material for preparing nickel matte according to an example of the present invention can shorten the separate iron removal process in the subsequent preparation of nickel matte, thereby improving process efficiency.

[0034] Furthermore, according to one embodiment of the present invention, the amount of sodium sulfate added to the molten metal, based on the weight of the molten metal master alloy, can be greater than 15% by weight and less than 40% by weight. In other words, in one embodiment of the present invention, by having a sodium sulfate content based on the weight of the molten metal master alloy greater than 15% by weight, the nickel recovery rate can be improved. As another embodiment, the sodium sulfate content based on the weight of the molten metal master alloy can be 20% by weight or more. On the other hand, when the sodium sulfate is excessively included, it will accelerate the deferrore reaction, which may actually reduce the nickel recovery rate. Therefore, in one embodiment of the present invention, the upper limit of the sodium sulfate content can be set to 40% by weight. As another embodiment, the sodium sulfate content based on the weight of the molten metal master alloy can be 35% or less, and as yet another embodiment, it can be 30% or less.

[0035] The existing preparation processes for nickel matte using sulfur and sodium sulfate are simplified and shown below. Figure 2 -(A) and Figure 2 -(B)

[0036] also, Figure 3 -(A) and Figure 3 - (B) are simplified schematic diagrams illustrating existing de-ironization processes using sulfur and sodium sulfate, respectively. As shown in these diagrams, compared to existing processes using sulfur, the preparation process of nickel matte raw materials using sodium sulfate according to the present invention provides a simplified de-ironization process, thereby shortening the de-ironization time.

[0037] Moreover, existing processes using sulfur are exothermic reactions (ΔH=-6358.1MJ / ton-Ni) that require the use of coolants. In contrast, this sulfidation / deferroinization composite reaction is endothermic (ΔH=6119.8MJ / ton-Ni), which has the advantage of easy temperature control.

[0038] Furthermore, according to a non-limiting example of the present invention, the nickel content of the raw material for preparing nickel matte (Ni3S2) obtained by adding sodium sulfate (Na2SO4) to the molten metal described above is from 20% to 70% by weight based on the total weight of the raw material. In addition, according to one embodiment, the iron content of the raw material can be from 4.0% to 75% by weight based on the total weight of the raw material, and the sulfur content of the raw material can be from 0.50% to 30% by weight based on the total weight of the raw material. As another example, the nickel content of the raw material can be from 27% to 66% by weight based on the total weight of the raw material, the iron content can be from 4.0% to 74% by weight, and the sulfur content can be from 0.5% to 27% by weight.

[0039] Furthermore, according to one non-limiting example, the iron to nickel content ratio contained in the raw material may be from 0.050 to 2.8, and according to another example, it may be from 1.0 to 2.75.

[0040] Unlike existing methods, one embodiment of the present invention uses sodium sulfate as a sulfidation feedstock for nickel to induce a sulfidation / de-ironization composite reaction, thereby providing a method for preparing raw materials for nickel matte that is easy to control at temperature. When preparing nickel matte using the raw materials described above according to an embodiment of the present invention, the number of separate de-ironization processes can be reduced, thereby improving process efficiency.

[0041] Furthermore, by using the sodium sulfate, which is a waste byproduct, as a sulfidation raw material in the nickel matte preparation process, the present invention can save waste costs and is therefore economically advantageous.

[0042] The present invention will now be described in more detail through embodiments. However, it should be noted that the following embodiments are merely illustrative of the invention for more detailed explanation and are not intended to limit the scope of the invention. This is because the scope of the invention is determined by the matters recorded in the claims and those reasonably deduced therefrom. Detailed Implementation

[0043] (1) Invention Example - Method for preparing raw materials for nickel matte with added sodium sulfate First, a master alloy molten metal of 80 wt% Fe and 20 wt% Ni was prepared. After preparing this master alloy molten metal, the temperature was maintained at 1300°C. Then, sodium sulfate powder was continuously added while stirring the molten metal. With the addition of sodium sulfate, a sulfidation / deferroinization reaction was carried out, and the composition of the raw material for preparing nickel matte was shown in Table 1 below. At this time, the composition in Table 1 is based on the total weight of the raw material as a percentage by weight. Then, the composition of the slag generated by adding sodium sulfate is shown in Table 2 below based on the total weight of the slag. At this time, the composition (weight %) of the raw material and slag in Tables 1 and 2 below was measured by inductively coupled plasma mass spectrometry (ICP-OES).

[0044] [Table 1] [Table 2] Through a combined sulfidation / deferromonization reaction with sodium sulfate (Na2SO4), nickel (Ni) is sulfided and enriched in the alloy as nickel sulfide (Ni3S2), while iron (Fe) is oxidized and separated as slag. Due to the selective oxidation of iron (Fe), the raw materials and slag for nickel matte preparation can be easily separated. The nickel recovery rate is then calculated using the following formula and is shown in Table 3 below.

[0045] [Table 3] also, Figure 4 The graph uses the weight ratio of sodium sulfate / metal master alloy molten metal shown in Table 3 as the x-axis and the concentration of nickel in the raw material and the nickel recovery rate as the y-axis.

[0046] (2) Comparative Example - Preparation Method of Raw Material for Nickel Mat with Sulfur Addition First, a master alloy molten metal of 80 wt% Fe and 20 wt% Ni was used. After preparing this master alloy molten metal, the temperature was maintained at 1300°C. Then, solid sulfur (S) powder was continuously added while stirring the molten metal. The composition of the raw materials for preparing nickel matte with added solid sulfur powder and sulfidation reaction is shown in Table 4 below. At this time, the weight ratio of the added solid sulfur powder to the metal master alloy molten metal was 2:5. The composition in Table 4 is based on the total weight of the raw materials as a percentage by weight. The weight percentage of each component of the final slag based on the total weight of the slag is shown in Table 5 below.

[0047] [Table 4] [Table 5] Based on the sulfidation reaction of solid sulfur, Ni and Fe are sulfided and enriched in the alloy as Ni3S2 and FeS, respectively. Fe is oxidized due to reactions in the atmosphere, thus some of it is separated as slag. Insufficient iron removal reaction leads to the contamination of raw materials and slag in nickel matte preparation.

[0048] At this point, 15% of the iron was removed by oxidation. Furthermore, the nickel recovery rate and the sulfur sulfidation efficiency were calculated as 67% and 50%, respectively.

[0049] (3) Experimental Results In the case of the invention, through the sulfidation / de-ironization complex reaction caused by the addition of sodium sulfate, nickel is sulfided and enriched in the raw material for nickel matte preparation in the form of Ni3S2, while iron is oxidized and separated in the form of slag.

[0050] Furthermore, in the comparative example, through a sulfidation reaction caused by the addition of solid sulfur, nickel was sulfided and enriched in the raw material for nickel matte preparation in the form of Ni3S2, while iron was oxidized and separated in the form of slag.

[0051] However, when more than 15% by weight and less than 40% by weight of sodium sulfate are added, the nickel recovery rate is high, at 98% and 99% respectively, through the sulfidation / deferroinization composite reaction. On the other hand, when more than 40% by weight of sodium sulfate is added, or when solid sulfur is used as the sulfidation raw material as in existing processes, such a high nickel recovery rate cannot be guaranteed.

[0052] That is, by adding an appropriate amount of sodium sulfate to the molten metal of the metal master alloy, the present invention can provide a raw material for nickel matte preparation with improved nickel recovery rate, and when using this raw material to prepare nickel matte, the number of separate de-ironization processes can be reduced, thereby improving process efficiency.

Claims

1. A method for preparing a raw material for nickel matte, comprising: The steps for preparing a molten metal master alloy containing nickel (Ni) and iron (Fe); as well as The step of adding sodium sulfate (Na2SO4) to the molten metal to obtain raw materials for the preparation of nickel matte (Ni3S2) The raw materials include nickel, iron, and sulfur (S).

2. The method for preparing raw materials for nickel matte according to claim 1, wherein, In the step of obtaining raw materials for nickel matte preparation, the amount of sodium sulfate added is greater than 15% by weight and less than 40% by weight, based on the total weight of the molten metal of the master alloy.

3. The method for preparing raw materials for nickel matte according to claim 1, wherein, The molten metal of the master alloy contains more than 10% by weight and less than 50% by weight of nickel relative to its total weight.

4. The method for preparing raw materials for nickel matte according to claim 1, wherein, The raw material contains 0.50% to 30% sulfur by weight based on the total weight of the raw material.

5. The method for preparing raw materials for nickel matte according to claim 1, wherein, The raw material contains 20% to 70% nickel based on its total weight.

6. The method for preparing raw materials for nickel matte according to claim 1, wherein, The raw material contains 4.0% to 75% iron based on the total weight of the raw material.

7. The method for preparing raw materials for nickel matte according to claim 1, wherein, The raw material contains iron to nickel in a weight ratio of 0.050 to 2.8.

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