Method for manufacturing nickel matte

Abstract

An aspect of the present invention provides a method for manufacturing nickel matte, which uses sodium sulfate (Na2SO4) or calcium sulfate (CaSO4), instead of elemental sulfur, as a sulfurizing agent, whereby the method exhibits improved efficiency and easier temperature control compared to conventional processes.

Description

Method for manufacturing nickel mat

[0001] The present invention relates to a method for manufacturing a nickel mat.

[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 nickel matte that can improve nickel recovery rate and nickel production amount.

[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 manufacturing a nickel mat according to one aspect of the present invention may include the steps of: preparing a molten metal alloy containing nickel (Ni) and iron (Fe); adding at least one of sodium sulfate (Na2SO4) and calcium sulfate (CaSO4) to the molten metal alloy to obtain an intermediate mat containing nickel, iron, and sulfur (S); and adding a sulfurized fuel and oxygen to the intermediate mat to obtain a nickel mat (Ni3S2).

[0007] The above-mentioned sulfur fuel may be at least one of sulfur (S), sodium sulfate and calcium sulfate.

[0008] The above-described sulfur fuel and the oxygen can be injected into the intermediate mat no more than twice.

[0009] When sodium sulfate is added in the step of obtaining the intermediate mat described above, the sodium sulfate may be added to the metal mother alloy molten metal in an amount of more than 15 wt% and less than 40 wt% based on the weight of the metal mother alloy molten metal.

[0010] The above-described metal alloy molten metal may contain 50 wt% or more of iron.

[0011] The above-mentioned sodium sulfate can be used in an amount of 1.1 to 2.3 tons per ton of nickel contained in the above-mentioned metal alloy molten metal.

[0012] The nickel recovery rate of the above-described intermediate mat may be 90 wt% or more.

[0013] The present invention can provide a de-ironization reaction with easy temperature control compared to existing processes by using sodium sulfate (Na2SO4) or calcium sulfate (CaSO4) instead of sulfur (S) as a sulfide raw material in the production of nickel matte.

[0014] When the method for manufacturing a nickel mat of the present invention is used, the number of de-ironization processes can be shortened, thereby increasing process efficiency.

[0015] In addition, in this case, sodium sulfate or calcium sulfate (CaSO4), 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 for manufacturing nickel mat using conventional sulfur (S) and a process for manufacturing nickel mat using sodium sulfate (Na2SO4).

[0018] Figure 3 is a schematic diagram showing a simplified nickel matte manufacturing process using conventional sulfur and a nickel matte manufacturing process using sodium sulfate.

[0019] Figure 4 is a graph in which the weight ratio of sodium sulfate / molten metal added during the manufacture of the intermediate mat is plotted on the x-axis, and the concentration of nickel and nickel recovery rate in the intermediate mat are plotted 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 of the existing process, the inventors of the present invention, through thermodynamic calculations and repeated experiments, have discovered that when an intermediate mat is manufactured using sodium sulfate (Na2SO4) or calcium sulfate (CaSO4) instead of the existing sulfur (S), and when this is used to manufacture nickel mat, the number of de-ironization steps in the overall nickel mat manufacturing process can be reduced. Furthermore, in the above-described case, the nickel recovery rate and nickel production volume can be improved.

[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 intermediate mat or nickel mat. Based on these thermodynamic calculation results, the inventors of the present invention invented the nickel mat manufacturing method described below.

[0032] That is, a method for manufacturing a nickel mat according to one embodiment of the present invention may include the steps of preparing a molten metal alloy containing nickel (Ni) and iron (Fe); adding at least one of sodium sulfate (Na2SO4) and calcium sulfate (CaSO4) to the molten metal alloy to obtain an intermediate mat containing nickel, iron, and sulfur (S); and adding sulfur fuel and oxygen to the intermediate mat to obtain a nickel mat (Ni3S2).

[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 iron (Fe) of 50 wt% or more based on the total weight thereof. That is, according to one embodiment of the present invention, an intermediate mat having a reduced iron content and an increased nickel content can be obtained from a molten metal master alloy having a high iron content. In addition, according to one embodiment of the present invention, by producing a nickel mat from such an intermediate mat, the nickel recovery rate and nickel production rate can be improved. In another embodiment, the molten metal master alloy may contain iron of 60 wt% or more, and in another example, it may contain iron of 70 wt% or more. On the other hand, when the iron content of the molten metal master alloy exceeds 90 wt%, the de-ironization reaction time may increase, which may cause a problem of reduced efficiency in producing a nickel mat. Therefore, the molten metal master alloy according to one embodiment of the present invention may contain iron of 90 wt% or less. According to another embodiment, the iron content of the molten metal master alloy may be 80 wt% or less or 75 wt% or less.

[0035] 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 low 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 10 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 is reduced. Therefore, the molten metal master alloy according to one embodiment of the present invention 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.

[0036] According to one example of the present invention, after preparing the above-described metal master alloy molten metal, an intermediate mat can be obtained by adding at least one of sodium sulfate (Na2SO4) and calcium sulfate (CaSO4) to the metal master alloy molten metal.

[0037] Through the above steps, the nickel component in the molten metal alloy can be concentrated in the intermediate mat in the form of nickel 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].

[0038] [Reaction Formula 3]

[0039]

[0040] That is, as described above, when conventional sulfur is added, only a sulfurization reaction occurs, whereas when the intermediate mat of the present invention is obtained using sodium sulfate, an oxidation reaction of iron may occur simultaneously while the sulfurization reaction of nickel occurs. Accordingly, the method for manufacturing a nickel mat according to an example of the present invention can shorten the number of de-ironization processes by manufacturing a nickel mat using the intermediate mat described above, thereby improving process efficiency. The manufacturing process of the intermediate mat using conventional sulfur and the manufacturing process of the intermediate mat using sodium sulfate described above are schematically illustrated in FIG. 2-(A) and FIG. 2-(B), respectively. The sulfidation / de-ironization complex reaction of Fig. 2-(B) 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 of Fig. 2-(A) which is an exothermic reaction (ΔH=-6,358.1 MJ / ton-Ni) and thus requires the use of a refrigerant.

[0041] In addition, when sodium sulfate is added in the step of obtaining the intermediate mat according to an example of the present invention, the sodium sulfate may be more than 15 wt% and less than 40 wt% based on the weight of the molten metal master alloy. In other words, one embodiment of the present invention can increase the nickel recovery rate by including the sodium sulfate more than 15 wt% based on the weight of the molten metal master alloy. In another embodiment, the sodium sulfate may be included in an amount of 20 wt% or more based on the weight of the molten metal master alloy. 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, in one embodiment of the present invention, the upper limit of the sodium sulfate content may be 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 molten metal master alloy, and in another embodiment, it may be included in an amount of 30 wt% or less.

[0042] Meanwhile, according to a non-limiting example of the present invention, the nickel content of the intermediate mat obtained by adding sodium sulfate (Na2SO4) or calcium sulfate (CaSO4) to the above-described molten metal may be 20 to 70 wt% based on the total weight of the intermediate mat. In addition, according to one embodiment, the iron content of the intermediate mat may be 4.0 to 75 wt% based on the total weight of the intermediate mat, and the sulfur content of the intermediate mat may be 0.50 to 30 wt% based on the total weight of the intermediate mat. 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%.

[0043] A method for manufacturing a nickel mat according to an example of the present invention can increase the nickel recovery rate of the intermediate mat by adding sodium sulfate or calcium sulfate (CaSO4) instead of sulfur to the molten metal. In this case, the nickel recovery rate can be derived by the following equation.

[0044]

[0045] More specifically, the nickel recovery rate of the intermediate mat according to one example of the present invention may be 90 wt% or more. According to another example, the nickel recovery rate of the intermediate mat may be 95 wt% or more or 98 wt% or more.

[0046] Thereafter, the method for manufacturing a nickel mat according to an example of the present invention may include a step of obtaining a nickel mat (Ni3S2) by adding sulfur fuel and oxygen to the intermediate mat obtained as described above. At this time, the sulfur fuel may be at least one of sulfur (S), sodium sulfate, and calcium sulfate.

[0047] When sulfur fuel and oxygen are injected in this way, a de-ironization reaction of the intermediate mat can be induced, and as a result, a high-purity nickel mat can be obtained.

[0048] Figures 3-(A) and 3-(B) are schematic diagrams illustrating a de-fertilization process for an intermediate mat manufactured by adding conventional sulfur and a de-fertilization process for an intermediate mat according to an example of the present invention manufactured by adding sodium sulfate, respectively. As shown in these drawings, when manufacturing a nickel mat using the intermediate mat of the present invention, the number of de-fertilization processes can be drastically reduced compared to the conventional process, thereby shortening the time required for the de-fertilization reaction.

[0049] More specifically, during the nickel mat manufacturing process according to an example of the present invention, the sulfurized fuel and the oxygen may be injected into the intermediate mat no more than twice. However, in order to provide a high-purity nickel mat, the sulfurized fuel and the oxygen must be injected at least once, and therefore, the sulfurized fuel and the oxygen may be injected into the intermediate mat once or twice.

[0050] In summary, the method for manufacturing nickel matte according to an example of the present invention, unlike conventional methods, utilizes sodium sulfate or calcium sulfate (CaSO4) as a nickel sulfide raw material, thereby inducing a sulfidation / desulfidation complex reaction, thereby providing the advantage of easy temperature control. When utilizing the method for manufacturing nickel matte according to an example of the present invention described above, the number of desulfidation processes can be reduced, thereby increasing process efficiency.

[0051] In addition, the present invention is economically advantageous in that it reduces disposal costs by consuming sodium sulfate or calcium sulfate (CaSO4), which are discarded as byproducts, as a sulfide raw material in the nickel matte manufacturing process. As a more specific example, the sodium sulfate may be used in an amount of 1.1 to 2.3 tons per ton of nickel contained in the metal master alloy molten metal.

[0052] 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.

[0053] (1) Invention example - Method for manufacturing nickel mat using sodium sulfate-injected intermediate mat

[0054] First, a molten metal master alloy of 80 wt% Fe-20 wt% Ni was prepared. After preparing the molten metal master alloy in this manner, the temperature was maintained at 1300°C. Thereafter, sodium sulfate powder was continuously added while stirring the molten metal master alloy. As sodium sulfate was added, a sulfidation / de-ironization complex reaction was performed, and the components of the intermediate mat produced thereby are as shown in Table 1 below. At this time, the composition in Table 1 is the weight % based on the total weight of the intermediate mat. Then, the composition of the intermediate mat slag produced by adding sodium sulfate is shown in Table 2 below based on the total weight of the intermediate mat slag. At this time, the composition (weight %) of the intermediate mat and intermediate mat slag in Tables 1 and 2 below was measured through inductively coupled plasma-optical spectroscopy (ICP-OES).

[0055] Composition of intermediate matte with weight ratio of molten Na2SO4 / mother 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

[0056] ClassificationNa2SO4 / Master alloy weight ratioIntermediate matte slag 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

[0057] According to 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 intermediate matte and intermediate matte slag produced due to 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. In addition, the nickel-based production amount after the de-ironization process was calculated and is also shown in Table 3 below.

[0058]

[0059] Distinction Na2SO4 / Metal molten metal weight ratio Nickel concentration in intermediate matte (wt%) Ratio of iron to nickel content in intermediate matte Nickel recovery Ni production S0 0 18% 4.3-22,571 t-Ni / yr S1 0.227% 2.7198% 33,184 t-Ni / yr S2 0.332% 2.0899% 41,147 t-Ni / yr S3 0.447% 1.0989% 96,048 t-Ni / yr S4 0.559% 0.7287% S5 0.8566% 0.0847%

[0060] In addition, Fig. 4 is a graph in which the weight ratio of sodium sulfate / molten metal shown in Table 3 above is on the x-axis and the concentration of nickel in the intermediate mat and the nickel recovery rate are on the y-axis.

[0061] Next, sulfur and oxygen were added to the intermediate mat S2 obtained according to the above-described method to obtain a nickel mat. The composition of the obtained nickel mat is as shown in Table 4 below.

[0062] Nickel matte composition (weight%)FeNiCoSM032.2%67%0.94%0.83%M1 (0.5h)28.9154.191.914.60M2 (1h)16.3666.122.114.70M3 (2h)3.7475.371.319.40

[0063] (2) Comparative example - Method for manufacturing nickel mat using sulfur-injected intermediate mat

[0064] First, pig iron, nickel, and solid sulfur were melted in an induction furnace to prepare a nickel intermediate mat. After the intermediate mat was manufactured, the temperature of the molten metal was maintained at 1200°C to 1300°C, and the components of the intermediate mat at this time are as shown in M0 of Table 5 below. Thereafter, while stirring the intermediate mat, ferronickel (FeNi) (Fe = 78-82% and Ni = 18-22%) and solid sulfur (S) powder were continuously added. The components of the nickel mat in which ferronickel was added and a sulfurization reaction was performed are as shown in M1 of Table 5 below. At this time, the weight ratio of the added ferronickel (FeNi), solid sulfur (S) powder, and intermediate mat was 0.2875: 0.2875: 1. The contents in Table 5 are the weight% of each component based on the total weight of the intermediate mat or nickel mat. Thereafter, the de-ironization reaction was induced by introducing air (21% O2-78% N2) and silica (SiO2) at a flow rate of 5 L / min for 4 hours. The air was introduced through a lance. Thereafter, the compositions of the nickel matte measured every hour are as shown in Table 5, M2, M3, M4, and M5, respectively. The weight percentages of each component of the final nickel matte slag based on the total weight of the nickel matte slag are shown in Table 6 below.

[0065] Nickel mat composition (wt%)FeNiCoSM029.8251.311.915.40M1 (0h)38.7644.591.613.90M2 (1h)32.8250.191.813.80M3 (1.5h)28.9154.191.914.60M4 (3h)16.3666.122.114.70M5 (4h)3.7475.371.319.40

[0066] FeOFe2O3SiO2MgONa2ONiOCoOSNickel matte slag composition (wt%) 36.512.521.643.00-15.433.031.78

[0067] (3) Experimental results

[0068] In the invention, nickel was sulfided and concentrated in the intermediate mat in the form of Ni3S2 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. In addition, the invention produced a nickel mat containing a high concentration of nickel by additionally adding sulfur and oxygen to the intermediate mat.

[0069] In addition, in the case of a comparative example, a nickel mat containing a high concentration of nickel was manufactured by additionally adding oxygen to the intermediate mat obtained by adding solid sulfur.

[0070] As shown in Table 3, when sodium sulfate of more than 15 wt% and less than 40 wt% was added to the molten metal as proposed in the present invention, the nickel recovery rate of the intermediate mat was high at 98% and 99%, respectively, whereas in the case of the intermediate mat to which sodium sulfate of 40 wt% or more was added, such a high nickel recovery rate could not be secured.

[0071] In addition, looking at Tables 4 and 5, when a high-concentration nickel mat having a nickel content of 70% or more is manufactured using an intermediate mat to which sodium sulfate of more than 15 wt% and less than 40 wt% is added, the de-ironization reaction time is only 2 hours. However, it can be confirmed that 4 hours were required for the de-ironization reaction when a high-concentration nickel mat was manufactured using the intermediate mat of the comparative example, even though the initial nickel content of the intermediate mat of the comparative example was higher than that of the intermediate mat of the invention example.

[0072] That is, the present invention can induce a sulfidation / de-ironization complex reaction by using sodium sulfate (Na2SO4) instead of the existing sulfur (S) in the manufacturing process of the intermediate mat, and as a result, the burden of de-ironization that may occur when manufacturing a nickel mat using the intermediate mat can be reduced, thereby increasing process efficiency.

Claims

1. A step of preparing a molten metal alloy containing nickel (Ni) and iron (Fe); A step of adding at least one of sodium sulfate (Na2SO4) and calcium sulfate (CaSO4) to the above metal alloy molten metal to obtain an intermediate mat containing nickel, iron, and sulfur (S); and A method for producing nickel mat, comprising the step of injecting sulfur fuel and oxygen into the intermediate mat to obtain nickel mat (Ni3S2).

2. In paragraph 1, A method for producing nickel matte wherein the above sulfur fuel is at least one of sulfur (S), sodium sulfate and calcium sulfate.

3. In paragraph 1, A method for manufacturing a nickel mat, wherein the above sulfur fuel and the above oxygen are injected into the intermediate mat twice or less.

4. In paragraph 1, A method for manufacturing a nickel mat, wherein when sodium sulfate is added in the step of obtaining the intermediate mat, the sodium sulfate is added to the metal mother alloy molten metal in an amount of more than 15 wt% and less than 40 wt% based on the weight of the metal mother alloy molten metal.

5. In paragraph 1, A method for producing a nickel matte, wherein the above metal alloy molten metal contains iron in an amount of 50 wt% or more and 90 wt% or less.

6. In paragraph 4, A method for manufacturing nickel matte, wherein the sodium sulfate is used in an amount of 1.1 to 2.3 tons per ton of nickel contained in the metal alloy molten metal.

7. In clauses 1 to 6, A method for manufacturing a nickel mat, wherein the nickel recovery rate of the intermediate mat is 90 wt% or more.

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