Method for preparing low grade nickel matte

Abstract

One aspect of the present invention provides a method for preparing low grade nickel matte, the method using sodium sulfate (Na2SO4) instead of sulfur as a sulfide raw material, thereby having temperature control easier than that of a conventional method, and enabling efficiency to increase during the manufacture of nickel matte.

Description

Manufacturing method of raw materials for manufacturing nickel matte

[0001] The present invention relates to a method for producing a raw material for producing nickel matte.

[0002] Typically, the nickel matte manufacturing process involves a sulfidation process and a de-ironization process. The sulfidation process typically utilizes sulfur (S), which sulfides the nickel within ferronickel into nickel sulfide (Ni3S2), concentrating the nickel in the matte layer. Meanwhile, the de-ironization process oxidizes the iron within ferronickel (FeNi) to iron (II) oxide and removes the slag layer containing iron (II) oxide.

[0003] However, the existing nickel matte manufacturing process using sulfur has several process-related problems, such as requiring multiple stages of de-ironization and requiring temperature control throughout the process due to the physical properties of liquid sulfur.

[0004] One aspect of the present invention is to provide a method for producing a raw material for producing nickel matte, which can improve nickel recovery rate and nickel production amount during the production of nickel matte.

[0005] The objectives of the present invention are not limited to the above-described scope. Those skilled in the art will have no difficulty understanding the additional objectives of the present invention from the overall content of this specification.

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

[0007] In the step of obtaining the raw material for manufacturing the nickel mat described above, the sodium sulfate may be added in an amount of more than 15% by weight and less than 40% by weight based on the total weight of the metal alloy molten metal.

[0008] The metal alloy melt described above may contain less than 50 wt% nickel.

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

[0010] The above-described raw material may contain 20 to 70 wt% of nickel based on the total weight of the raw material.

[0011] The above-described raw material may contain 4.0 to 75 wt% of iron based on the total weight of the raw material.

[0012] The weight ratio of iron to nickel contained in the above-described raw material may be from 0.050 to 2.8.

[0013] The present invention can provide a de-ironization reaction with easy temperature control compared to existing processes by using sodium sulfate (Na2SO4) instead of sulfur (S) as a sulfide raw material when manufacturing a raw material for manufacturing nickel matte.

[0014] When using the raw material for manufacturing nickel mat of the present invention, nickel mat can be manufactured by reducing the number of subsequent separate de-ironization processes, thereby increasing process efficiency.

[0015] In addition, in this case, sodium sulfate, which is discarded as a by-product, can be used as sulfur fuel, which saves disposal costs, making it economically advantageous.

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

[0017] Figure 2 is a schematic diagram showing a simplified process of a raw material for manufacturing nickel matte using existing sulfur (S) and a process of a raw material for manufacturing nickel matte using sodium sulfate (Na2SO4).

[0018] Figure 3 is a schematic diagram showing a simplified de-ironization process using conventional sulfur and a de-ironization process using sodium sulfate.

[0019] Figure 4 is a graph in which the weight ratio of sodium sulfate / metal alloy melt is on the x-axis and the concentration of nickel in the raw material and the nickel recovery rate are on the y-axis in an example of the present invention.

[0020] Hereinafter, preferred embodiments of the present invention will be described. However, the embodiments of the present invention may be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below.

[0021] In this specification, the term "including" is used to indicate that other components may be included rather than excluding other components unless specifically stated to the contrary.

[0022] Additionally, unless otherwise specifically provided in the specification of the present invention, the % unit means weight%.

[0023] As mentioned above, the nickel matte manufacturing process generally involves a sulfurization process using sulfur (S) and a de-ironization process. In this case, the reaction formula within the sulfurization process using sulfur (S) is as shown in [Reaction Formula 1] below, and the reaction formula within the de-ironization process is as shown in [Reaction Formula 2] below.

[0024] [Reaction Formula 1]

[0025]

[0026] [Reaction Formula 2]

[0027]

[0028] However, since the nickel matte manufacturing process using sulfur goes through several stages of de-ironization, there are problems with very low flexibility in operation control, such as heat and material balance imbalance and damage to refractory materials during long-term tempering operations.

[0029] In addition, since liquid sulfur requires temperature control between 130°C and 150°C, considering its melting point and high-temperature viscosity, problems such as reduced fluidity within the process may also arise.

[0030] To address these problems with existing processes, the inventors of the present invention, through thermodynamic calculations and repeated experiments, discovered that when sodium sulfate (Na2SO4) is used as a raw material for manufacturing nickel matte instead of sulfur (S), the number of de-ironization steps in the overall nickel matte manufacturing process can be reduced. Furthermore, the aforementioned process can improve nickel recovery and nickel production.

[0031] Figure 1 shows the results of thermodynamic calculations of component changes during nickel sulfidation. At this time, Figure 1-(A) shows the case where liquid sulfur (S) was used, and Figure 1-(B) shows the case where sodium sulfate (Na2SO4) was used. According to this, when liquid sulfur was used, the nickel after the sulfidation reaction was only 10 wt%, but when sodium sulfate was used, the nickel after the sulfidation reaction was 70 wt%, and it can be seen that when sodium sulfate was used, a relatively high content of nickel can be concentrated in the raw material for manufacturing nickel matte. Based on these thermodynamic calculation results, the inventors of the present invention invented a method for manufacturing a raw material for manufacturing nickel matte, which will be described below.

[0032] That is, a method for manufacturing a raw material for manufacturing nickel matte according to one embodiment of the present invention may include a step of preparing a molten metal alloy containing nickel (Ni) and iron (Fe); and a step of adding sodium sulfate (Na2SO4) to the molten metal to obtain a raw material for manufacturing nickel matte (Ni3S2), wherein the raw material may contain nickel, iron, and sulfur (S).

[0033] According to one embodiment of the present invention, the molten metal master alloy may be obtained by melting an iron and nickel alloy. As an example, the molten metal master alloy may be derived from a ferronickel process. The ferronickel process refers to a process for producing a ferronickel alloy through dry refining from nickel oxide ore. The material derived from the ferronickel process may be a melt as an intermediate product or a melt as a final product during the ferronickel process, or may be a mixture of the two. However, the present invention is not limited thereto.

[0034] According to one embodiment of the present invention, the molten metal master alloy may contain nickel in an amount of 10 wt% or more and less than 50 wt%. That is, according to one embodiment of the present invention, a raw material for manufacturing nickel matte may be provided by increasing the nickel content from a molten metal master alloy having a nickel content of less than 50 wt%. In addition, according to one embodiment of the present invention, by manufacturing a nickel matte from such a raw material, a nickel matte having improved nickel recovery rate and nickel production rate may be obtained. In another embodiment, the molten metal master alloy may contain nickel in an amount of less than 40%, and in another embodiment, it may contain nickel in an amount of less than 30%. On the other hand, when the nickel content of the molten metal master alloy is less than 20 wt%, the de-ironization reaction time may increase, and thus, a problem may occur in which the efficiency of manufacturing a raw material for manufacturing nickel matte may be reduced. Therefore, according to one embodiment of the present invention, the molten metal master alloy may contain nickel in an amount of 10 wt% or more. According to another embodiment, the nickel content of the metal alloy melt may be 20 wt% or more or 25 wt% or more.

[0035] According to one example of the present invention, after preparing the above-described metal alloy molten metal, sodium sulfate (Na2SO4) is added to the molten metal to obtain a raw material for manufacturing nickel matte (Ni3S2).

[0036] Through the above steps, the nickel component in the molten metal alloy can be concentrated in the raw material for manufacturing nickel matte in the form of nickel(II) sulfide (Ni3S2) through a sulfurization reaction with sodium sulfate, and the iron component in the molten metal alloy can be oxidized to iron(II) oxide (FeO). The reaction formula of this sulfurization / de-ironization complex reaction is as follows [Reaction Formula 3].

[0037] [Reaction Formula 3]

[0038] That is, as described above, when conventional sulfur is added, only a sulfidation reaction occurs, whereas when the raw material for manufacturing nickel mat of the present invention is obtained using sodium sulfate, an oxidation reaction of iron may occur simultaneously during the sulfidation reaction of nickel. Accordingly, the method for manufacturing a raw material for manufacturing nickel mat according to an example of the present invention can shorten the separate de-ironization process during the subsequent nickel mat manufacturing, thereby improving process efficiency.

[0039] In addition, according to one example of the present invention, the sodium sulfate added to the molten metal may be more than 15 wt% and less than 40 wt% based on the weight of the metal master alloy molten metal. In other words, one embodiment of the present invention can increase the nickel recovery rate by including the sodium sulfate in an amount exceeding 15 wt% based on the weight of the metal master alloy molten metal. In another embodiment, the sodium sulfate may be included in an amount of 20 wt% or more based on the weight of the metal master alloy molten metal. On the other hand, when the sodium sulfate is included excessively, the de-ironization reaction may be accelerated, which may cause a problem of a decrease in the nickel recovery rate. Therefore, one embodiment of the present invention may set the upper limit of the sodium sulfate content to 40 wt%. In another embodiment, the sodium sulfate may be included in an amount of 35 wt% or less based on the weight of the metal master alloy molten metal, and in another embodiment, it may be included in an amount of 30% or less.

[0040] The manufacturing process of the raw material for manufacturing nickel matte using the existing sulfur described above and the manufacturing process of the raw material for manufacturing nickel matte using sodium sulfate are schematically illustrated in Fig. 2-(A) and Fig. 2-(B), respectively.

[0041] In addition, FIG. 3-(A) and FIG. 3-(B) are schematic diagrams showing a simplified de-ironization process using conventional sulfur and a de-ironization process using sodium sulfate, respectively. As shown in these drawings, the manufacturing process of a raw material for manufacturing nickel matte using sodium sulfate of the present invention can reduce the de-ironization time by providing a simplified de-ironization process compared to the conventional process using sulfur.

[0042] In addition, this sulfidation / de-ironization complex reaction has the advantage of easy temperature control as it is an endothermic reaction (ΔH= 6,119.8 MJ / ton-Ni), unlike the existing process using sulfur which is an exothermic reaction (ΔH=-6,358.1 MJ / ton-Ni) and requires the use of a refrigerant.

[0043] Meanwhile, according to a non-limiting example of the present invention, the nickel content of the raw material for manufacturing nickel matte (Ni3S2) obtained by adding sodium sulfate (Na2SO4) to the above-described molten metal may be 20 to 70 wt% based on the total weight of the raw material. In addition, according to one embodiment, the iron content of the raw material may be 4.0 to 75 wt% based on the total weight of the raw material, and the sulfur content of the raw material may be 0.50 to 30 wt% based on the total weight of the raw material. As another example, the nickel content of the raw material may be 27 to 66 wt% based on the total weight of the raw material, the iron content may be 4.0 to 74 wt%, and the sulfur content may be 0.5 to 27 wt%.

[0044] Additionally, as a non-limiting example, the iron to nickel content ratio contained in the raw material may be from 0.050 to 2.8, and as another example, from 1.0 to 2.75.

[0045] One example of the present invention, unlike conventional methods, utilizes sodium sulfate as a nickel sulfide raw material, thereby inducing a sulfidation / desulfidation complex reaction, thereby providing a method for producing a raw material for nickel matte with easy temperature control. When producing nickel matte using the raw material according to the above-described example of the present invention, the number of separate desulfidation processes can be reduced, thereby increasing process efficiency.

[0046] In addition, the present invention is economically advantageous in that it can reduce disposal costs by consuming sodium sulfate, which is discarded as a by-product, as a sulfide raw material in the nickel matte manufacturing process.

[0047] Hereinafter, the present invention will be described in more detail through examples. However, it should be noted that the following examples are intended only to illustrate and further illustrate the present invention and are not intended to limit the scope of the invention. This is because the scope of the invention is determined by the matters set forth in the patent claims and matters reasonably inferred therefrom.

[0048] (1) Invention example - Method for manufacturing raw materials for manufacturing nickel mat using sodium sulfate

[0049] First, a master alloy molten metal of 80 wt% Fe-20 wt% Ni was prepared. After preparing the master alloy molten metal in this way, the temperature was maintained at 1300°C. Thereafter, sodium sulfate powder was continuously added while stirring the molten metal. As sodium sulfate was added, a sulfidation / de-ironization complex reaction was performed, and the components of the raw materials for manufacturing nickel matte thus produced are as shown in Table 1 below. In this case, the composition in Table 1 is the weight% based on the total weight of the raw materials. Then, the composition of the slag produced by adding sodium sulfate is shown in Table 2 below based on the total weight of the slag. In this case, the composition (weight%) of the raw materials and slag in Tables 1 and 2 below was measured through inductively coupled plasma-optical spectroscopy (ICP-OES).

[0050] Composition of raw materials for manufacturing nickel matte by weight ratio of molten Na2SO4 / metal base alloy (wt%)S / NiFe / NiFeNiCoMgSiNaSM10.273.1270.80.010.0130.0070.810.032.71M20.36732.20.940.0090.007<0.0010.830.032.08M30.451.34 7.21.290.0050.0080.0680.700.011.09M40.542.458.71.60.0020.043 0.1641.240.020.72M50.854.99660.53<0.0010.0320.76926.60.400.08

[0051] ClassificationNa2SO4 / Metal alloy molten metal weight ratioSlag composition (wt%)FeOFe2O3SiO2MgONa2ONiOCoOSS10.244.709.283.590.5113.680.670.046.03S20.32.104.730.750.1133.830.13<0.018.71S30.448.4013.201.901.5411.381.810.1120.20S40.542.708.502.630.2513.682.160.167.98S50.8518.1030.501.701.7415.9510.770.398.40

[0052] Through the complex sulfidation / de-ironization reaction of sodium sulfate (Na2SO4), nickel (Ni) was sulfided and concentrated in the alloy in the form of nickel sulfide (Ni3S2), and iron (Fe) was oxidized and separated in the form of slag. The raw material for manufacturing nickel matte and the slag produced by the selective oxidation of iron (Fe) could be easily separated. At this time, the nickel recovery rate was calculated by the following equation and is shown in Table 3 below.

[0053]

[0054] Nickel concentration in raw material for nickel mat production (wt%) by weight of molten metal alloy Nickel recovery rate (S00) (before injection) 18% 4.3-S 10.227% 2.7198% S 20.332% 2.0899% S 30.447% 1.0989% S 40.559% 0.7287% S 50.8566% 0.0847%

[0055] In addition, Fig. 4 is a graph in which the weight ratio of sodium sulfate / metal alloy molten metal shown in Table 3 above is on the x-axis and the concentration of nickel in the raw material and the nickel recovery rate are on the y-axis.

[0056] (2) Comparative example - Method for manufacturing raw materials for manufacturing sulfur-injected nickel mat

[0057] First, a master alloy molten metal of 80 wt% Fe-20 wt% Ni was used. After the master alloy molten metal was prepared in this manner, the temperature was maintained at 1300°C. Thereafter, solid sulfur (S) powder was continuously added while stirring the molten metal. The components of the raw materials for producing nickel matte in which the solid sulfur powder was added and the sulfurization reaction was performed are shown in Table 4 below. At this time, the weight ratio of the added solid sulfur powder and the metal master alloy molten metal was 2:5. The composition in Table 4 is the weight% based on the total weight of the raw materials. The weight% of each component of the final slag based on the total weight of the slag is shown in Table 5 below.

[0058] Composition of raw materials for manufacturing nickel matte (wt%)FeNiS57.114.826.8

[0059] Slag composition (wt%)FeONiOS60.5814.1525.26

[0060] Due to the sulfidation reaction of solid sulfur, Ni and Fe were sulfided and concentrated in the alloy as Ni3S2 and FeS, respectively. Fe was oxidized due to atmospheric reaction and separated in the form of slag. Due to the lack of de-ironization reaction, raw materials for nickel matte production were mixed with slag.

[0061] At this time, the amount of iron removed through oxidation was 15%. In addition, the nickel recovery rate and sulfur sulfidation efficiency were calculated by the following formula and were 67% and 50%, respectively.

[0062]

[0063]

[0064] (3) Experimental results

[0065] In the case of the invention example, nickel was sulfided and concentrated in the form of Ni3S2 in the raw material for manufacturing nickel matte through a complex sulfidation / de-ironization reaction caused by the addition of sodium sulfate, and iron was oxidized and separated in the form of slag.

[0066] In addition, in the case of the comparative example, nickel was sulfurized and concentrated in the form of Ni3S2 in the raw material for manufacturing nickel matte through a sulfurization reaction caused by the introduction of solid sulfur, and iron was oxidized and separated in the form of slag.

[0067] However, when sodium sulfate exceeding 15 wt% and less than 40 wt% was added, the nickel recovery rate was as high as 98% and 99%, respectively, by the sulfidation / de-ironization complex reaction, whereas when sodium sulfate exceeding 40 wt% was added or solid sulfur was used as the sulfidation raw material as in the existing process, such a high nickel recovery rate could not be secured.

[0068] That is, the present invention can provide a raw material for manufacturing nickel matte having an improved nickel recovery rate by adding an appropriate amount of sodium sulfate to a metal alloy molten metal, and when manufacturing nickel matte using such a raw material, the number of separate de-ironization processes can be reduced, thereby increasing process efficiency.

Claims

1. A step of preparing a molten metal alloy containing nickel (Ni) and iron (Fe); and It includes a step of adding sodium sulfate (Na2SO4) to the above molten metal to obtain a raw material for manufacturing nickel matte (Ni3S2). The above raw materials are a method for manufacturing a nickel matte, the raw materials including nickel, iron and sulfur (S).

2. In paragraph 1, A method for producing a raw material for manufacturing nickel matte, wherein in the step of obtaining the raw material for manufacturing the above nickel matte, the sodium sulfate is added in an amount of more than 15 wt% and less than 40 wt% based on the total weight of the metal base alloy molten metal.

3. In paragraph 1, A method for manufacturing a raw material for manufacturing nickel matte, wherein the above metal alloy molten metal contains nickel in an amount of 10 wt% or more and less than 50 wt% based on the total weight of the metal alloy.

4. In paragraph 1, A method for producing a raw material for manufacturing nickel matte, wherein the raw material contains 0.50 to 30 wt% of sulfur based on the total weight of the raw material.

5. In paragraph 1, A method for producing a raw material for manufacturing a nickel mat, wherein the raw material contains 20 to 70 wt% of nickel based on the total weight of the raw material.

6. In paragraph 1, A method for producing a raw material for manufacturing nickel matte, wherein the raw material contains 4.0 to 75 wt% of iron based on the total weight of the raw material.

7. In paragraph 1, A method for manufacturing a raw material for manufacturing nickel matte, wherein the weight ratio of iron to nickel contained in the raw material is 0.050 to 2.8.

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