Cold-pressed solid agglomerate for the production of iron-nickel alloys, manufacturing process of the same, and, production process of an iron-nickel alloy

Abstract

The present invention relates to a cold-pressed solid agglomerate for producing iron-nickel alloys, the manufacturing process thereof, and a process for producing iron-nickel alloys. The present invention features a cold-pressed solid agglomerate with the following mass proportions: 80 to 95% by mass of laterite ore; 3 to 10% by mass of at least one binder; and 2 to 10% by mass of a carbon source. The agglomerate manufacturing process comprises the steps of (i) mixing the laterite ore with at least one binder and a carbon source; and (ii) cold pressing the mixture to form the agglomerate. The process of producing an iron-nickel alloy comprises the steps of (i) mixing the laterite ore with at least one binder and a carbon source; (ii) cold pressing the mixture to form an agglomerate; (iii) pre-reducing the solid agglomerate in a furnace with a controlled atmosphere; and (iv) melting the pre-reduced solid agglomerate in a furnace with a controlled atmosphere.

Description

Cold-pressed solid agglomerate for the production of ferro-nickel alloys, manufacturing process thereof, and production process of an ferro-nickel alloy. FIELD OF THE INVENTION

[0001] The present invention relates to iron-nickel alloys. More specifically, the present invention relates to a process for producing an iron-nickel alloy from a cold-pressed solid agglomerate. FUNDAMENTALS OF THE INVENTION

[0002] The cold agglomeration process is a method used to compact fine materials (powder or granules), forming briquettes without the need to apply heat. This technique is used in industry to transform mineral and metallurgical raw materials into high-density briquettes, which can be easier to handle, store, and transport.

[0003] Briquettes, or solid agglomerates, are a viable and sustainable option for supplying the necessary metallic charge in the production of metal alloys, contributing to the production of high-quality alloys and reducing material waste. They can be used as raw material in metallurgical furnaces for alloy production, and can be manufactured from various materials depending on their application, such as: scrap metal, coal, coke fines, or iron ore.

[0004] Lateritic nickel ore is typically formed from limonite, gamierite, and sometimes magnesium silicate. This ore originates from the weathering of ultramafic or ultrabasic rocks, where nickel, due to its Ni ion, is present. 2+ , it can replace Fe ions. 2+ and Mg 2+ in the crystalline network of these minerals.

[0005] Within lateritic ore, there are zones with different concentrations of nickel, depending on the depth and climatic conditions of the environment in which they are found. These zones are classified as: limonitic zone, intermediate zone and saprolitic zone, the latter being the deepest and with the highest concentration of the metal, exceeding 3% of the total mass.

[0006] Most of the nickel produced in the world comes from pyrometallurgical routes, one of which is the production of ferronickel by the RKEF (Rotary Kill Electric Furnace) process, used to treat saprolitic lateritic ore. Due to the high iron content and low nickel content in limonitic fractions, this ore is not used as a raw material for the process, as it would produce an alloy with a low content of the metal.

[0007] Nickel has a high carbothermic reduction capacity, meaning that in the presence of carbon it is reduced more easily than iron oxide, for example. Therefore, when making self-reducing mixtures with different levels of carbon, there will be less Fe formation, an increase in the FeO content in the slag, and greater incorporation of nickel into the alloy. The reduction reactions of nickel oxide by solid carbon are shown below: NiO+C=Ni+CO (1) 2NiO+C=2Ni+CO2(2)

[0008] The relative proportion of the products CO and CO2 depends on the equilibrium of the system. Thus, reactions (1) and (2) occur simultaneously, indicating that NiO reacts with C to form Ni, CO, and CO2.

[0009] The existing ferro-nickel alloy production processes on the market generally do not employ pre-reduced solid agglomerates in their process, nor do they consider catalytic elements in the agglomerate mixture. Furthermore, the combination of raw materials used, as well as the types of furnaces employed in the melting of the raw material, do not generate good efficiency in the production process as a whole.

[0010] The invention now proposed solves the problems of the prior art described above in a simple and efficient way. SUMMARY OF THE INVENTION

[0011] The present invention has as its first objective to provide a cold-pressed solid agglomerate for the production of ferro-nickel alloys and a manufacturing process for the same that employs lateritic ore and a carbonaceous source in its composition.

[0012] The present invention has a second objective: to provide a process for producing an iron-nickel alloy from a cold-pressed solid agglomerate that utilizes an efficient combination of the composition of the solid agglomerate, the type of furnace used, and the pre-reduction and melting stages of the raw material.

[0013] In order to achieve the objectives described above, the present invention provides a cold-pressed solid agglomerate for the production of ferro-nickel alloys comprising 80 to 95% by mass of lateritic ore, 3 to 10% by mass of at least one binder, and 2 to 10% by mass of a carbonaceous source.

[0014] The present invention further provides a process for manufacturing a cold-pressed solid agglomerate for the production of ferro-nickel alloys, the process comprising the steps of (i) mixing 80 to 95% by mass of lateritic ore, 3 to 10% by mass of at least one binder and 2 to 10% by mass of a carbonaceous source; and (ii) cold-pressing the lateritic ore, the at least one binder and the carbonaceous source to form a solid agglomerate.

[0015] Finally, the present invention provides a process for producing an iron-nickel alloy from a cold-pressed solid agglomerate, the process comprising the steps of (i) mixing 80 to 95% by mass of lateritic ore, 3 to 10% by mass of at least one binder and 2 to 10% by mass of a carbonaceous source; (ii) cold-pressing the lateritic ore, the at least one binder and the carbonaceous source to form a solid agglomerate; (iii) pre-reducing the solid agglomerate in a furnace with a controlled atmosphere; and (iv) melting the pre-reduced solid agglomerate in a furnace with a controlled atmosphere. BRIEF DESCRIPTION OF THE FIGURES

[0016] The detailed description presented below refers to the attached figures and their respective reference numbers.

[0017] Figure 1 shows an Ellingham diagram with the incorporation of nickel through the C / Fe ratio, as used in the present invention.

[0018] Figure 2 shows the result of the agglomerate manufacturing process and a flowchart of the ferro-nickel alloy production process of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] First, it should be noted that the description that follows will be based on a preferred embodiment of the invention. As will become evident to anyone skilled in the art, however, the invention is not limited to this particular embodiment.

[0020] The cold agglomeration process is a method used to compact fine materials (powder or granules), forming briquettes without the need to apply heat. It should be noted that the particle size for briquetting must be below 6.3 mm.

[0021] The present invention provides a cold-pressed solid agglomerate for the production of ferro-nickel alloys. The cold-pressed solid agglomerate of the present invention comprises a mixture which, in turn, comprises the following mass proportions: 80 to 95% by mass of lateritic ore; 3 to 10% by mass of at least one binder; 2 to 10% by mass of a carbonaceous source.

[0022] The carbonaceous source is used to maximize the incorporation of nickel into the alloy. The carbonaceous source is at least one of the following: charcoal, coal, anthracite, or other carbon sources. The increased incorporation of nickel can be explained by... the C / Fe ratio of this mineral, as can be seen in the Ellingham diagram shown in Figure 1.

[0023] More preferably, the lateritic ore used belongs to the saprolitic zone, as this zone has a high nickel content compared to other mineral zones.

[0024] Preferably, at least one binder can be starch or bentonite. More preferably, at least one binder can be replaced by 4.5% to 6% organic starch, using the reagents in the following mass proportions: Water: 83 to 87.5%; Starch: 12 to 16%; Sodium Hydroxide: 0.5 to 1%.

[0025] The present invention provides a process for manufacturing a cold-pressed solid agglomerate for the production of ferro-nickel alloys. The process for manufacturing the cold-pressed solid agglomerate according to the present invention comprises the steps of (i) mixing lateritic ore with at least one binder and a carbonaceous source; and (ii) cold-pressing the mixture to form an agglomerate.

[0026] The mixing stage of the manufacturing process of the present invention comprises a mixture which, in turn, comprises the following mass proportions: 80 to 95% by mass of lateritic ore; 3 to 10% by mass of at least one binder; 2 to 10% by mass of a carbonaceous source.

[0027] Preferably, the manufacturing process of the cold-pressed solid agglomerate of the present invention comprises a drying step of the lateritic ore, prior to the cold-pressing step of the mixture, so that the lateritic ore reaches a maximum moisture content of 10%.

[0028] Preferably, the particleboard manufacturing process The cold-pressed solid of the present invention comprises a step of separating the lateritic ore with a 5 mm sieve before the drying step, in order to achieve particle size adjustment of the raw material.

[0029] Preferably, after the pressing stage, the manufacturing process of the cold-pressed solid particleboard of the present invention comprises a stage of drying the solid particleboard at a temperature of 100 to 120°C for 3 to 5 hours.

[0030] The present invention further provides a process for producing an iron-nickel alloy from a cold-pressed solid agglomerate. The process for producing an iron-nickel alloy from a cold-pressed solid agglomerate, according to the present invention, comprises the steps of (i) mixing lateritic ore with at least one binder and a carbonaceous source; (ii) cold-pressing the mixture to form a solid agglomerate; (iii) pre-reducing the solid agglomerate in a furnace with a controlled atmosphere; and (iv) melting the pre-reduced solid agglomerate in a furnace with a controlled atmosphere.

[0031] The step of mixing the lateritic ore with at least one binder and a carbonaceous source in the production process of the ferro-nickel alloy of the present invention comprises a mixture which, in turn, comprises the following mass proportions: 80 to 95% by mass of lateritic ore; 3 to 10% by mass of at least one binder; 2 to 10% by mass of a carbonaceous source.

[0032] Preferably, the production process of the ferro-nickel alloy according to the present invention comprises a drying step of the lateritic ore before the cold pressing step of the mixture, so that the lateritic ore reaches up to 10% moisture.

[0033] Additionally, before the cold pressing stage of the lateritic ore, at least one binder and a carbon source are needed to form a In the solid agglomerate, the production process of a ferro-nickel alloy of the present invention preferably comprises a step of separating the lateritic ore with a 5 mm sieve before the drying step, in order to perform the granulometric adjustment of the raw material.

[0034] Preferably, after the pressing stage, the manufacturing process of the cold-pressed solid particleboard of the present invention comprises a stage of drying the solid particleboard at a temperature of 100 to 120°C for 3 to 5 hours.

[0035] Preferably, the step of pre-reducing the solid agglomerate in a controlled atmosphere furnace of the present invention comprises pre-reducing the solid agglomerate in a furnace with an oxidative-reducing atmosphere, such as an induction furnace, at a temperature between 1000°C and 1200°C for 25 to 70 min. More preferably, the pre-reducing step is carried out between 1000°C and 1100°C for 55 to 70 min or between 1100°C and 1200°C for 25 to 40 min.

[0036] Optionally, the step of pre-reducing the solid agglomerate in a controlled atmosphere furnace of the present invention can occur in a rotary kiln, type RK (Rotary Kiln), at a temperature of 1050°C to 1450°C for 30 to 60 min.

[0037] Preferably, a temperature of 1200°C is recommended because it is high enough to initiate the carbothermic reduction reaction of nickel in the solid agglomerate, but not so high as to cause problems with the melting of the solid agglomerates or excessive wear of the furnace. Furthermore, a temperature of 1200°C is capable of achieving an efficient reduction rate for most applications. A temperature of 1050°C is recommended in some cases where the reduction rate is not as critical or when the furnace used is not capable of reaching higher temperatures. Reduction at 1050°C requires a longer reaction time, but may be more suitable for some processes.

[0038] The step of melting the pre-reduced solid agglomerate into a The controlled atmosphere furnace of the present invention comprises carrying out the melting process at a temperature starting from 1400°C. The optimum melting temperature is 1450°C, where the incorporation levels of iron and nickel are higher.

[0039] Optionally, the pre-reducing and melting stages of the pre-reduced solid agglomerate can be carried out in the same batch in an induction furnace at higher temperatures, from 1450°C to 1500°C. In this way, one stage is carried out subsequently to the other in the same induction furnace, reducing production time.

[0040] In order to test the quality of the solid agglomerates and the ferro-nickel alloy produced from them, three formulations were developed for the composition of cold-pressed solid agglomerates for the production of ferro-nickel alloys, which are presented in Table 1 below: Table 1

[0041] Table 2 below shows the results obtained for the reduction of saprolitic ore and the iron-nickel (Fe / Ni) ratio of the alloy.

[0042] Melting tests show that to increase the nickel content in pig iron, the iron incorporation in the alloy must be decreased. The C / O ratio of the solid slurry must be reduced to decrease the degree of metallization. When metallization is low, iron incorporation is reduced and the nickel content is high. To improve iron incorporation, the basicity of the solid slurry must be increased. According to the tests, to increase nickel incorporation in the alloy, the amount of reducing agent in the solid slurry must be decreased until it is sufficient to reduce only the nickel and not the iron. Example in Table 3, where the "optimal" reducing agent content in the agglomerate was 8%, thus decreasing the incorporation of iron in the alloy.

[0043] Tests show that the nickel content in the alloy is inversely related to the carbon content of the solid agglomerate due to lower iron incorporation. The lower the iron incorporation, the higher the nickel incorporation. To increase iron incorporation, the basicity must be adjusted accordingly. 0.6 to 1.0.

[0044] Table 3 below shows the results obtained by relating the percentage of nickel in the alloy to the carbon content of the agglomerate. Table 3

[0045] Table 4 below shows the results obtained by relating the degree of metallization to the reducing agent content in the agglomerate. Table 4

[0046] Tests showed that when melting occurs inside an induction furnace, it produces slag containing the unreduced constituents: SiO2, FeO, SiO2, and MgO, and the ferro-nickel alloy contains between 20% and 40% nickel. It is worth noting that, at the end, the alloy obtained may undergo refining and purification processes to remove phosphorus and sulfur before being sent to special steel production units.

[0047] Numerous variations within the scope of protection of this application are permitted. Therefore, it is reinforced that the present invention is not limited to the particular configurations / embodiments described above.

Claims

CLAIMS 1. Cold-pressed solid agglomerate for the production of iron-nickel alloys, characterized by comprising: 80 to 95% by mass of lateritic ore; 3 to 10% by mass of at least one binder; 2 to 10% by mass of a carbon source.

2. Agglomerate, according to claim 1, characterized in that the at least one binder is at least one of: starch; betonite.

3. Agglomerate, according to claim 1 or 2, characterized in that the lateritic ore is an ore originating from the saprolitic zone.

4. Process for manufacturing a cold-pressed solid agglomerate for the production of iron-nickel alloys, characterized by comprising the steps of: mixing 80 to 95% by mass of lateritic ore, 3 to 10% by mass of at least one binder and 2 to 10% by mass of a carbon source; and cold-pressing the lateritic ore, the at least one binder and the carbon source to form a solid agglomerate.

5. Process, according to claim 4, characterized by additionally comprising a step of drying the lateritic ore to 10% moisture before the mixing step.

6. Process, according to claim 5, characterized by additionally comprising a step of separating the lateritic ore with a 5 mm sieve before the drying step.

7. Process according to any one of claims 4 to 6, characterized in that it additionally comprises a drying step of the solid agglomerate after the cold pressing stage of the mixture.

8. Process according to any one of claims 4 to 7, characterized in that it comprises, after the pressing step, an additional step of drying the solid agglomerate at a temperature of 100 to 120°C for 3 to 5h.

9. Process for producing an iron-nickel alloy from a cold-pressed solid agglomerate, characterized by comprising the steps of: mixing 80 to 95% by mass of lateritic ore, 3 to 10% by mass of at least one binder and 2 to 10% by mass of a carbon source; and cold-pressing the lateritic ore, the at least one binder and the carbon source to form a solid agglomerate; pre-reducing the solid agglomerate in a controlled atmosphere furnace; and melting the pre-reduced solid agglomerate in a controlled atmosphere furnace.

10. Process according to claim 9, characterized in that the step of pre-reducing the solid agglomerate in a controlled atmosphere furnace is carried out in an induction furnace or in a rotary kiln RK.

11. Process according to claim 9 or 10, characterized in that the step of pre-reducing the solid agglomerate in a controlled atmosphere furnace is carried out at a temperature between 1000°C and 1450°C for 25 to 70 min.

12. Process according to any one of claims 9 to 11, characterized in that the step of melting the pre-reduced solid agglomerate is carried out at a temperature greater than or equal to 1400°C.

13. Process, according to claim 9, characterized in that the steps of pre-reducing and melting the pre-reduced solid agglomerate are carried out in the same batch in an induction furnace at temperatures of 1450°C to 1500°C.

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