Method for producing nickel-matrix material

Abstract

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

Description

Technical Field

[0001] This invention relates to a method for preparing 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 provides a method for preparing nickel matte that can selectively oxidize the iron in molten alloy metal and ferronickel (FeNi) as initial raw materials, and can sulfide and enrich the nickel.

[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 entirety of this specification.

[0006] (II) Technical Solution One aspect of the present invention provides a method for preparing nickel matte, the method comprising: preparing an alloy molten metal containing nickel; and adding ferronickel (FeNi) and sodium sulfate (Na2SO4) to the alloy molten metal to enrich nickel and sulfur.

[0007] The molten alloy metal may contain more than 50.0% by weight of nickel.

[0008] The amount of ferronickel added can be more than 15.0% by weight and less than 35.0% by weight relative to the total weight of the alloy molten metal, and the amount of sodium sulfate added can be more than 5.0% by weight and less than 15.0% by weight relative to the total weight of the alloy molten metal.

[0009] The molten metal of the alloy can be derived from the nickel-iron process.

[0010] The nickel content of the prepared nickel matte can be 55.0% by weight or more relative to the total weight of the nickel matte, and the sulfur content can be 10.0% by weight or more relative to the total weight of the nickel matte.

[0011] In addition, the nickel matte preparation method of the present invention may further include the step of adding oxygen (O2) to the molten alloy metal.

[0012] The oxygen can be introduced using at least one of a lance or a tuyere.

[0013] Furthermore, in the nickel matte preparation method of the present invention, a slagging agent is added simultaneously with the oxygen.

[0014] The slag-forming agent may contain silicon dioxide (SiO2).

[0015] The step of preparing the alloy molten metal can be carried out in a temperature range of 0°C to 300°C higher than the melting point of the alloy molten metal, and the step of enriching nickel and sulfur can be carried out in a temperature range of 0°C to 300°C higher than the melting point of the alloy molten metal.

[0016] Another aspect of the present invention provides a nickel matte comprising: more than 55.0% by weight of nickel, more than 10.0% by weight of sulfur relative to the total weight of the nickel matte, and further comprising sodium.

[0017] The sodium content may be less than 0.10% by weight relative to the total weight of nickel matte.

[0018] The A value of the nickel matte, derived from the following [relationship 1], can be 50.0 or higher.

[0019] [Relation 1] (In [Equation 1], [Ni], [S], and [Na] represent the weight percentages of nickel, sulfur, and sodium contained in the nickel matte relative to the total weight of the nickel matte.) (III) Beneficial Effects In the preparation of nickel matte, this invention uses sodium sulfate (Na2SO4) instead of sulfur (S) as the sulfidation raw material, thereby providing a deferrore reaction with easier temperature control compared to existing processes.

[0020] As mentioned above, using sodium sulfate instead of sulfur can shorten the iron removal time and thus improve process efficiency.

[0021] Furthermore, in this case, sodium sulfate, which is a waste byproduct, can be used as a sulfidized fuel, thereby saving waste costs and thus being economically advantageous. Attached Figure Description

[0022] Figure 1 This shows the thermodynamic calculation results of the compositional changes during the nickel sulfidation reaction.

[0023] Figure 2This is a simplified schematic diagram illustrating existing nickel matte preparation processes using sulfur (S) and sodium sulfate (Na2SO4).

[0024] Figure 3 This is a simplified schematic diagram illustrating existing iron removal processes using sulfur and those using sodium sulfate.

[0025] Figure 4 The graphs show the changes in the nickel matte composition over time in the inventive example and the comparative example, respectively.

[0026] Figure 5 The graphs show the nickel recovery rate and sulfur sulfidation efficiency based on the iron removal reaction in the invention example and the comparative example, respectively. Best practice

[0027] 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.

[0028] 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.

[0029] Furthermore, in the specification of this invention, unless otherwise specified, the unit % represents weight.

[0030] 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].

[0031] [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.

[0032] 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.

[0033] To address the problems of the existing process, the inventors of this invention designed a nickel matte preparation process that uses sodium sulfate (Na2SO4) instead of sulfur (S) through thermodynamic calculations and repeated experiments.

[0034] 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 can be enriched in nickel matte when using sodium sulfate. Based on this thermodynamic calculation, the inventors of this invention have developed the nickel matte preparation process described below.

[0035] That is, the nickel matte preparation process according to one embodiment of the present invention may include the steps of preparing an alloy molten metal containing nickel; and the steps of adding ferronickel (FeNi) and sodium sulfate (Na2SO4) to the alloy molten metal to enrich nickel and sulfur.

[0036] According to one embodiment of the invention, the alloy molten metal can be obtained by molten iron and nickel alloy. As an example, this alloy molten metal 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 molten material as an intermediate product or as a final product during the ferronickel process, or it can be a mixture of both. However, it is not necessarily limited to this.

[0037] According to one embodiment of the invention, the molten alloy metal may contain 50.0% by weight or more of nickel. When the nickel content of the molten alloy metal is less than 50.0% by weight, the deferrore reaction time may increase, resulting in a decrease in the efficiency of the nickel matte preparation process. According to another embodiment, the nickel content of the molten alloy metal may be 70.0% by weight or more.

[0038] The amount of ferronickel added can be more than 15.0% by weight and less than 35.0% by weight relative to the total weight of the alloy molten metal, and the amount of sodium sulfate added can be more than 5.0% by weight and less than 15.0% by weight relative to the total weight of the alloy molten metal.

[0039] Furthermore, the step of preparing the molten alloy metal can be carried out at a temperature range of 0°C to 300°C higher than the melting point of the molten alloy metal. This is to melt the molten alloy metal by heating, thereby improving its fluidity. As another embodiment, the step of preparing the molten alloy metal can be carried out at a temperature range of 100°C to 200°C higher than the melting point of the molten alloy metal.

[0040] According to one embodiment of the present invention, the nickel matte preparation process may include the step of adding ferronickel (FeNi) and sodium sulfate (Na2SO4) to the alloy molten metal after preparation to enrich nickel and sulfur.

[0041] At this point, ferronickel can function as a raw material for nickel. Through the aforementioned steps, the nickel component in the molten alloy metal and the ferronickel can undergo a sulfidation reaction with sodium sulfate, enriching the nickel matte layer in the form of nickel(II) sulfide (Ni3S2), while the iron component in the molten alloy metal and the ferronickel can be oxidized to iron(II) oxide (FeO). The reaction formula for this sulfidation / deferroic composite reaction is shown in [Reaction Formula 3] below.

[0042] [Reaction 3] That is, as mentioned above, in existing nickel matte preparation processes using sulfur, only a sulfidation reaction occurs upon the addition of sulfur. However, in the nickel matte preparation process of the present invention using sodium sulfate, the sulfidation reaction of nickel can be accompanied by an iron oxidation reaction. Therefore, the nickel matte preparation process of the present invention can reduce the burden of the subsequent iron removal reaction, thereby improving process efficiency.

[0043] The existing nickel matte preparation processes using sulfur and sodium sulfate are simplified and illustrated below. Figure 2 -(A) and Figure 2 -(B)

[0044] 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 figures, the nickel matte preparation process using sodium sulfate of the present invention provides a simplified de-ironization process compared to existing processes using sulfur, thereby shortening the de-ironization time.

[0045] 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.

[0046] Furthermore, after the aforementioned steps of enriching nickel and sulfur, the nickel content of the nickel matte can be 55.0% by weight or more, and the sulfur content can be 10.0% by weight or more. As another embodiment, the nickel content of the nickel matte can be 70.0% by weight or more, and the sulfur content can be 20.0% by weight or more.

[0047] Furthermore, the nickel and sulfur enrichment step can be carried out at a temperature range of 0°C to 300°C higher than the melting point of the molten alloy metal. This is to improve the reaction efficiency of the sulfidation and deferroplating reactions by heating. As another embodiment, the nickel and sulfur enrichment step can be carried out at a temperature range of 100°C to 200°C higher than the melting point of the molten alloy metal.

[0048] In addition, according to another embodiment of the nickel matte preparation process of the present invention, after adding sodium sulfate as described above, oxygen (O2) can be further added to the molten alloy metal.

[0049] By further adding oxygen, the present invention can induce a sequential iron removal reaction after the sulfidation / iron removal composite reaction. The reaction formula at this time is as follows [Reaction Formula 2].

[0050] [Reaction 2] At this point, the oxygen can be added using at least one of the spray gun and the air vent.

[0051] In addition, a slagging agent can be added simultaneously with the oxygen. This slagging agent can lower the melting point and viscosity of the slag. The slagging agent is not limited to this, but can be silicon dioxide (SiO2).

[0052] As described above, unlike existing processes that use sulfur, the nickel matte preparation process of the present invention uses sodium sulfate to induce a sulfidation / deferroic reaction. Therefore, the present invention provides a nickel matte preparation process with high efficiency and easily controllable temperature.

[0053] 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.

[0054] The nickel matte of the present invention will now be described in detail.

[0055] As described above, according to one embodiment of the present invention, nickel matte may contain more than 55.0% by weight of nickel and more than 10.0% by weight of sulfur relative to the total weight of nickel matte.

[0056] Furthermore, since the present invention uses sodium sulfate instead of sulfur as the sulfidation raw material, the nickel matte according to one embodiment of the present invention may further contain sodium.

[0057] Sodium is included as an unavoidable impurity during the preparation process of the present invention. Therefore, according to one embodiment of the present invention, the nickel matte may contain less than 0.10% by weight of sodium relative to its total weight. When the sodium content is greater than 0.10% by weight, it may create a burden on impurity removal in the refining process. As another embodiment, the sodium content may be less than 0.75% by weight, and as yet another embodiment, it may be less than 0.50% by weight. On the other hand, the less sodium contained in the nickel matte of the present invention, the higher the purity of the nickel matte can be provided. Therefore, the present invention does not particularly limit the lower limit of sodium content. However, considering that nickel is inevitably included in the preparation process of the nickel matte of the present invention, the lower limit of sodium content in the nickel matte of the present invention may be set to 0.01%.

[0058] Furthermore, according to one embodiment of the present invention, the A value of the nickel matte derived from the following [relationship 1] can be 50.0 or higher.

[0059] [Relation 1] (In the above [relationship 1], [Ni], [S] and [Na] represent the weights of nickel, sulfur and sodium contained in nickel matte relative to the total weight of nickel matte, respectively). By setting the A value to 50.0 or higher, this invention provides nickel matte with low sodium content (as an impurity) while being enriched with high concentrations of nickel and sulfur. In another embodiment, the A value can be 100.0 or higher, and in yet another embodiment, it can be 250.0 or higher. Detailed Implementation

[0060] (1) Invention Example - Preparation process of nickel matte with sodium sulfate First, pig iron, nickel, and solid sulfur are melted in an induction furnace to prepare the alloy molten metal. After preparing the alloy molten metal, its temperature is maintained between 1250°C and 1350°C. At this time, the composition of the alloy molten metal is as shown in M0 of Table 1 below. Then, while stirring the alloy molten metal, ferronickel (FeNi) (Fe=78-82% and Ni=18-22%) and sodium sulfate (Na2SO4) powder are continuously added. The composition of the alloy molten metal undergoing the sulfidation / deferroicing composite reaction with the addition of ferronickel is as shown in M1 of Table 1 below. At this time, the weight ratio of the added ferronickel (FeNi), sodium sulfate (Na2SO4) powder, and alloy molten metal is 0.2875:0.1075:1. The compositions in Table 1 are based on the total weight of nickel matte as weight percent. Then, air (21% O2-78% N2) and silicon dioxide (SiO2) are added at a flow rate of 5 L / min for 3 hours to induce the deferroicing reaction. Air was introduced at this point via a spray gun. Subsequently, the composition of the nickel matte measured every hour is shown in Table 1 as M2, M3, and M4, respectively. Furthermore, the weight percentage of each component of the final slag, based on the total weight of the slag, is shown in Table 2 below. Figure 4 -(A) is a diagrammatic representation of Table 1, showing the changes in the composition of nickel matte according to the sulfidation / de-ironization complex reaction and the de-ironization reaction in the invention example.

[0061] [Table 1] [Table 2] (2) Comparative Example - Preparation Process of Nickel Matte with Sulfur Addition First, pig iron, nickel, and solid sulfur are melted in an induction furnace to prepare an alloy molten metal. After preparing the alloy molten metal, the temperature of the molten metal is maintained at 1200°C to 1300°C, and the composition of the alloy molten metal is shown as M0 in Table 3 below. Then, while stirring the alloy molten metal, ferronickel (FeNi) (Fe=78-82% and Ni=18-22%) and solid sulfur (S) powder are continuously added. The composition of the alloy molten metal undergoing the sulfidation reaction with the addition of ferronickel is shown as M1 in Table 3 below. At this time, the weight ratio of the added ferronickel (FeNi), solid sulfur (S) powder, and alloy molten metal is 0.2875:0.2875:1. The contents in Table 3 are the weight percent of each component based on the total weight of nickel matte. Then, air (21% O2-78% N2) and silicon dioxide (SiO2) are added at a flow rate of 5 L / min for 4 hours to induce the deferroiron reaction. At this time, the air is added through a spray gun. Subsequently, the composition of the nickel matte measured every hour is shown as M2, M3, M4, and M5 in Table 3. The weight percentage of each component of the final slag, based on the total weight of the slag, is shown in Table 4 below. Figure 4-(B) is presented in the form of a graph in Table 3, showing the changes in matte composition of the comparative examples based on the sulfidation and deferroation reactions.

[0062] [Table 3] [Table 4] (3) Experimental Results In the case of the invention, through the sulfidation / de-ironization complex reaction caused by the addition of sodium sulfate and the de-ironization reaction caused by the addition of oxygen, nickel is sulfided and enriched in nickel matte in the form of Ni3S2, while iron is oxidized and separated in the form of slag.

[0063] Furthermore, in the comparative example, through a sulfidation reaction caused by the addition of solid sulfur and a deironization reaction caused by the addition of oxygen, nickel was sulfided and enriched in nickel matte in the form of Ni3S2, while iron was oxidized and separated in the form of slag.

[0064] The invention example using sodium sulfate reduces the burden of the subsequent iron removal reaction through the sulfidation / removal composite reaction, thereby simplifying the iron removal process. Therefore, compared to the comparative example, the invention example produces nickel matte with the nickel content desired by the present invention in a relatively short time.

[0065] also, Figure 5 -(A) and Figure 5 -(B) are graphs showing the nickel recovery rate and sulfur sulfidation efficiency according to the iron removal reaction in the inventive example and the comparative example, respectively. The x-axis here represents the weight percentage of iron (Fe) in the nickel matte. The nickel recovery rate and sulfur sulfidation efficiency are derived from the following formula.

[0066] As can be seen from the chart, in the invention example with the addition of sodium sulfate, the nickel recovery rate and sulfur sulfidation efficiency did not decrease significantly according to the iron removal reaction, and were 95% and 93%, respectively. On the other hand, in the comparative example with the addition of solid sulfur, as the iron removal reaction time increased, the content of nickel and sulfur in slag form increased, as shown in Table 4, thereby reducing the nickel recovery rate and sulfur sulfidation efficiency to 91% and 76%, respectively.

[0067] The experimental results above confirm that the present invention uses sodium sulfate (Na2SO4) to replace the existing sulfur (S), thereby shortening the iron removal time and providing a highly efficient nickel matte preparation process.

Claims

1. A method for preparing nickel matte, comprising: The steps for preparing molten alloy metal containing nickel; as well as The step of adding ferronickel (FeNi) and sodium sulfate (Na2SO4) to the molten alloy metal to enrich nickel and sulfur.

2. The method for preparing nickel matte according to claim 1, wherein, The molten alloy metal contains more than 50.0% by weight of nickel.

3. The method for preparing nickel matte according to claim 1, wherein, The amount of nickel-iron added is more than 15.0% by weight and less than 35.0% by weight relative to the total weight of the alloy molten metal.

4. The method for preparing nickel matte according to claim 1, wherein, The amount of sodium sulfate added is more than 5.0% by weight and less than 15.0% by weight relative to the total weight of the alloy molten metal.

5. The method for preparing nickel matte according to claim 1, wherein, The molten metal of the alloy originates from the nickel-iron process.

6. The method for preparing nickel matte according to claim 1, wherein, The prepared nickel matte has a nickel content of 55.0% by weight or more relative to the total weight of the nickel matte, and a sulfur content of 10.0% by weight or more relative to the total weight of the nickel matte.

7. The method for preparing nickel matte according to claim 1, wherein, The preparation method further includes the step of adding oxygen (O2) to the molten alloy metal.

8. The method for preparing nickel matte according to claim 7, wherein, The oxygen is introduced using at least one of a spray gun and an air vent.

9. The method for preparing nickel matte according to claim 7, wherein, A slagging agent is added simultaneously with the oxygen.

10. The method for preparing nickel matte according to claim 9, wherein, The slag-forming agent contains silicon dioxide (SiO2).

11. The method for preparing nickel matte according to claim 1, wherein, The step of preparing the alloy molten metal is carried out in a temperature range of 0°C to 300°C above the melting point of the alloy molten metal, and the step of enriching nickel and sulfur is carried out in a temperature range of 0°C to 300°C above the melting point of the alloy molten metal.

12. A nickel matte comprising: nickel of 55.0% by weight or more and sulfur of 10.0% by weight or more relative to the total weight of the nickel matte. It also contains sodium.

13. The nickel matte according to claim 12, wherein, The sodium content is less than 0.10% by weight relative to the total weight of nickel matte.

14. The nickel matte according to claim 12, wherein, The nickel matte has an A value of 50.0 or higher, derived from the following [relationship 1]. [Relation 1] In the above [relationship 1], [Ni], [S] and [Na] represent the weights of nickel, sulfur and sodium contained in nickel matte relative to the total weight of nickel matte, respectively.

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