Method for preparing high matte nickel from low-grade limonite type laterite-nickel ore
By setting a reasonable feeding sequence and temperature range in the electric furnace, and using carbon dioxide, sulfur, and air to adjust the composition of molten iron, the smelting problem of low-grade limonite-type laterite nickel ore was solved, and the preparation of high-grade nickel matte was achieved, simplifying the process and reducing costs.
Patent Information
- Application Number
- CN202511561176.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-29
- Publication Date
- 2026-01-09
AI Technical Summary
Existing technologies make it difficult to effectively utilize low-grade limonite-type laterite nickel ore to prepare high-grade nickel matte, especially during blast furnace smelting due to the high position of the softening zone, poor permeability, low iron temperature, and poor slag viscosity and flowability, which makes preparation difficult.
By setting a reasonable feeding sequence and temperature range, and using carbon dioxide, sulfur and air to adjust the composition of molten iron, low-grade laterite nickel ore is smelted into high-grade nickel matte in the same electric furnace. First, iron and nickel are reduced to elemental form, then elemental iron is oxidized by carbon dioxide, and finally ferrous oxide is removed by silica slag formation. Lime is used to lower the melting point of the slag and improve its fluidity.
It has achieved the smelting of high-grade limonite-type laterite nickel ore into high-grade matte in the same electric furnace. The process is simple, easy to operate, highly adaptable to raw materials, and has low production costs. It can also successfully produce slag and iron under high aluminum content conditions.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of metal smelting technology and relates to a method for preparing high-grade nickel matte from low-grade limonite-type laterite nickel ore. Background Technology
[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.
[0003] High-grade nickel matte is an important intermediate product in the nickel metal smelting process and one of the key raw materials for nickel sulfate used in new energy batteries. High-grade nickel matte is mainly produced by pyrometallurgical smelting of nickel sulfide ore and laterite nickel ore. Laterite nickel ore is the main raw material for the preparation of high-grade nickel matte due to its larger reserves.
[0004] Lateritic nickel ore can be classified into three types based on nickel grade and ore depth: limonite type, transitional type, and humic type. Among these three types, limonite type lateritic nickel ore has the largest reserves, but its nickel grade is relatively low, approximately 0.8% to 1.5%. Currently, the raw materials used in pyrometallurgical processes are mainly high-grade lateritic nickel ore with a nickel content of 1.2% to 1.8%. For low-grade limonite type lateritic nickel ore with a nickel content of 0.8% to 1%, especially the high-alumina type, the softening zone is located higher during blast furnace smelting, resulting in poor permeability of the upper furnace charge, low iron temperature, sticky slag, and very poor fluidity, making it difficult to produce high-grade matte. Summary of the Invention
[0005] To address the aforementioned technical problems, this invention provides a method for preparing high-grade nickel matte from low-grade limonite-type laterite nickel ore. By setting a reasonable feeding sequence and temperature range, and especially by introducing carbon dioxide to adjust the composition of molten iron to high-nickel iron, high-grade nickel matte can be prepared from low-grade laterite nickel ore. The entire process is completed in the same electric furnace, making the process simple and easy to operate.
[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A method for preparing high-grade nickel matte from low-grade limonite-type laterite nickel ore includes the following steps: S1. Mix low-grade limonite-type laterite nickel ore with a reducing agent and heat to 900℃~1150℃, smelt for 0.5h~1h to obtain reduced material; S2. Add lime and continuously purge carbon dioxide for 2-4 hours; then raise the temperature to 1400℃-1700℃ and release the slag. S3. Add silica, spray sulfur into the bottom of the molten liquid and continue to introduce air, smelt for 0.5h~1h and then release the slag. S4. Add silica, continuously circulate air, smelt for 5-7 hours, then release the molten metal to obtain high-grade nickel matte. The low-grade limonite-type laterite nickel ore has a Ni grade of 0.8% to 1%.
[0007] The beneficial effects of this invention are as follows: 1. This invention proposes a method for smelting high-grade matte from low-grade limonite-type laterite nickel ore. First, a reducing agent is used to reduce most of the iron and nickel from oxides to elemental forms. Then, carbon dioxide, sulfur, and air are used to sequentially convert the elemental iron into oxides, sulfides, and ferrous oxide, accompanied by silica slag removal. The remaining matte phase becomes high-grade matte. The carbon dioxide introduced during the process only oxidizes elemental iron, not elemental nickel, thus resulting in high-nickel iron in the molten iron, ultimately yielding high-grade matte. Lime is used to react with SiO2 and Al2O3 to generate low-melting-point slag. Combined with a smelting temperature higher than that of a blast furnace, the slag fluidity is improved, allowing for smooth slag and iron tapping even under conditions of high Al2O3 content.
[0008] 2. The entire smelting process of this invention can be carried out in the same electric furnace. The process equipment is simple, the operation is convenient, the raw materials are highly adaptable, and the production cost is low. It has good application prospects and promotion significance. Detailed Implementation
[0009] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.
[0010] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0011] The following low-grade limonite-type laterite nickel ore masses are calculated on a dry basis.
[0012] Sulfur, hydrogen, and carbon dioxide are industrial-grade products, which can be purchased commercially through regular channels.
[0013] One or more embodiments of the present invention provide a method for preparing high-grade nickel matte from low-grade limonite-type laterite nickel ore, comprising the steps of: S1. Mix low-grade limonite-type laterite nickel ore with a reducing agent and heat to 900℃~1150℃, smelt for 0.5h~1h to obtain reduced material; S2. While maintaining the temperature of 900~1150℃ from step S1, add lime and continuously purge carbon dioxide for 2h~4h; then raise the temperature to 1400℃~1700℃ and release the slag. S3. Add silica, spray sulfur into the bottom of the molten liquid and continuously introduce air. After smelting for 0.5h~1h, a matte phase is formed, and the slag is discharged. S4. Add silica to the matte phase, continuously circulate air, and smelt for 5-7 hours before releasing the matte phase to obtain high-grade nickel matte. The low-grade limonite-type laterite nickel ore has a Ni grade of 0.8% to 1%.
[0014] In the above process, low-grade limonite-type laterite nickel ore is added to the furnace along with a reducing agent. Through smelting, most of the nickel and iron are reduced from oxides to metallic elements. Then, carbon dioxide is used to convert the elemental iron into oxides, which enter the slag, while the elemental nickel remains in the remaining iron phase. Sulfur is used to convert the elemental nickel and iron in the iron phase into sulfides. The iron sulfides further react with air to form ferrous oxide, which is then removed by slag formation with silica. After that, oxidizing air further promotes the conversion of ferrous oxide. Finally, the matte phase is released to obtain high-grade nickel matte.
[0015] Optionally, in S1, the reducing agent is a carbonaceous reducing agent or a gaseous reducing agent. The carbonaceous reducing agent is one or more of coke, semi-coke, and coal, and the gaseous reducing agent includes one or more of hydrogen and carbon monoxide. Its function is to convert nickel and iron in low-grade limonite-type laterite nickel ore into elemental substances.
[0016] Optionally, when the reducing agent is a carbonaceous reducing agent, the mass ratio of low-grade limonite-type lateritic nickel ore to the reducing agent is 100:(15~30); the low-grade limonite-type lateritic nickel ore and the carbonaceous reducing agent are mixed and added into the smelting furnace.
[0017] Optionally, when the reducing agent is a gaseous reducing agent, the flow rate of the reducing agent is 1.5 parts / h to 4 parts / h per 100 parts of low-grade limonite-type lateritic nickel ore; and it is mixed by blowing it into the furnace from below the low-grade limonite-type lateritic nickel ore.
[0018] Optionally, in S2, the carbon dioxide flow rate is 5 parts / h to 22 parts / h per 100 parts of low-grade limonite-type laterite nickel ore; the elemental iron is oxidized into oxides as much as possible and enters the slag phase, while the elemental nickel is not oxidized and remains in the iron phase in elemental form, so the nickel content in the iron phase gradually increases.
[0019] Optionally, in S2, the mass ratio of low-grade limonite-type laterite nickel ore to lime is 100:(0.07~0.12); the role of lime is to lower the melting point of slag, giving it suitable viscosity and good fluidity. The lime is added by feeding solid lime material into the top of the electric furnace.
[0020] Optionally, in S3, the sulfur is liquid sulfur, and the mass ratio of low-grade limonite-type laterite nickel ore to liquid sulfur is 100:(1~2); the sulfur converts elemental nickel and elemental iron into sulfides to form a matte phase; blowing it in liquid form can effectively promote the uniformity of the reaction.
[0021] Optionally, in S3, the air flow rate is 8 to 20 parts per 100 parts of low-grade limonite-type laterite nickel ore; the air reacts with the iron sulfide in the matte phase, converting it into ferrous oxide, which is then removed by the slag.
[0022] Optionally, in S3, the mass ratio of low-grade limonite-type laterite nickel ore to silica is 100:(2~4); the role of silica is to form slag and promote the removal of ferrous oxide; the method of adding silica is to add solid silica material at the top of the electric furnace.
[0023] Optionally, in S4, the air flow rate is 0.5 parts / h to 2 parts / h per 100 parts of low-grade limonite-type laterite nickel ore; this promotes the conversion of iron in the matte phase into ferrous oxide as much as possible and facilitates the transfer of iron to the slag.
[0024] Optionally, in S4, the mass ratio of low-grade limonite-type laterite nickel ore to silica is 100:(0.5~1.2); the role of silica is to form slag and promote the removal of ferrous oxide; the method of adding silica is to add solid silica material at the top of the electric furnace.
[0025] The present invention will be further described below with reference to specific embodiments.
[0026] Example 1 The coke composition used in this embodiment is shown in Table 1, the lime composition is shown in Table 2, the silica composition is shown in Table 3, and the low-grade limonite-type laterite nickel ore (dry basis) composition is shown in Table 4; wherein, the Ni content of the low-grade limonite-type laterite nickel ore is 0.85%.
[0027] Table 1. Coke Composition Table
[0028] Table 2 Lime Composition Table
[0029] Table 3 Silica Composition Table
[0030] Table 4. Composition of low-grade limonite-type laterite nickel ore from Example 1
[0031] In this embodiment, an electric furnace is selected as the smelting equipment. Four graphite electrodes are inserted into the outer cavity of the electric furnace. When the electrodes are energized, they heat up and then heat the furnace charge through the furnace lining by means of heat conduction.
[0032] The preparation method includes the following steps: S1. Using coke as a carbonaceous reducing agent, 100 parts of low-grade limonite-type laterite nickel ore and 16.67 parts of coke were transported to the top charging platform buffer silo of the electric furnace via a trolley. They were then unloaded into the top charging silo by a figure-eight conveyor belt and added into the furnace through the charging pipe. The temperature was controlled at 950℃ by energizing the electrodes and smelted for 0.8 hours to obtain the reduced material. The composition of the reduced material at this time is shown in Table 5.
[0033] Table 5 Composition of Reducing Materials
[0034] S2. Maintain the temperature of 950℃ from step S1, add 0.09 parts of lime to the reducing material at the top of the electric furnace, and continuously smelt carbon dioxide gas at a flow rate of 11.09 parts / h for 3 hours. Then raise the temperature to 1550℃ and release the slag. At this time, the composition of the molten metal in the furnace, i.e., the molten iron, is shown in Table 6, which is high-nickel iron.
[0035] Table 6. Molten Metal Composition Table
[0036] S3. Add 3.18 parts of silica to the top of the electric furnace, spray 1.44 parts of liquid sulfur into the bottom of the molten liquid, and then continuously introduce air at a flow rate of 9.47 parts / h. This step is an exothermic reaction and can shut off the heating electrode. After smelting for 1 hour, a matte phase is formed, and the slag is released. The composition of the matte phase at this time is shown in Table 7.
[0037] Table 7. Sulfonium Phase Composition Table
[0038] S4. Add 0.75 parts of silica to the matte phase at the top of the electric furnace and continuously introduce air at a flow rate of 1.35 parts / h. This step is an exothermic reaction and can shut off the heating electrode. After smelting for 5 hours, release the molten iron (matte phase) to obtain high-grade nickel matte.
[0039] The mass fractions of elements in the high-grade nickel matte obtained in this embodiment were determined to be: Ni 66.29%; Fe 6.12%; S 27.59%.
[0040] Example 2 The composition of low-grade limonite-type lateritic nickel ore (dry basis) is shown in Table 8. The Ni grade of low-grade limonite-type lateritic nickel ore is 0.95%.
[0041] Table 8. Composition of low-grade limonite-type laterite nickel ore in Example 2
[0042] In this embodiment, an electric furnace is selected as the smelting equipment. Six silicon molybdenum electrodes are inserted into the outer cavity of the electric furnace. When the electrodes are energized, they heat up and then heat the furnace charge through the furnace lining by means of heat conduction.
[0043] The preparation method includes the following steps: S1. Using hydrogen as a gaseous reducing agent, 100 parts of low-grade limonite-type laterite nickel ore are transported by a belt conveyor system to the top charging platform buffer bin of the electric furnace, and then transported by belt to the material distribution trolley, unloaded into the top hopper, and added into the furnace through the material pipe; the electrodes are energized to control the temperature at 950℃, and hydrogen is continuously introduced at a flow rate of 3.24 parts / h for smelting for 1 hour to obtain the reduced material; S2. Maintain the temperature of 950℃ from step S1, add 0.07 parts of lime to the reducing material at the top of the electric furnace, and continuously introduce carbon dioxide gas at a flow rate of 6.81 parts / h. Smelt for 4 hours, then heat to 1650℃ and release the slag. S3. Add 3.25 parts of silica to the top of the electric furnace, spray 1.51 parts of liquid sulfur into the bottom of the molten liquid, and continuously introduce air at a flow rate of 18.82 parts / h. After smelting for 0.5 hours, a matte phase is formed, and the slag is discharged. S4. Add 0.80 parts of silica to the matte phase at the top of the electric furnace, and continuously introduce air at a flow rate of 1.15 parts / h. After smelting for 6 hours, release the molten iron (matte phase) to obtain high-grade nickel matte.
[0044] The mass fractions of elements in the high-grade nickel matte obtained in this embodiment were determined to be: Ni 70.68%; Fe 2.31%; S 27.01%.
[0045] Example 3 The coal composition used in this embodiment is shown in Table 9. The composition of the low-grade limonite-type laterite nickel ore (dry basis) in this embodiment is shown in Table 10. The Ni content of the low-grade limonite-type laterite nickel ore is 0.80%.
[0046] Table 9 Coal Composition Table
[0047] Table 10 Composition of low-grade limonite-type laterite nickel ore in Example 3
[0048] In this embodiment, an electric furnace is selected as the smelting equipment. Four silicon-carbon electrodes are inserted into the outer cavity of the electric furnace. When the electrodes are energized, they heat up and then heat the furnace charge through the furnace lining by means of heat conduction.
[0049] The preparation method includes the following steps: S1. Coal is selected as the carbonaceous reducing agent. 100 parts of low-grade limonite-type laterite nickel ore and 23.95 parts of coal are transported to the top charging platform buffer bin of the electric furnace by a belt conveyor system. Then, they are unloaded into the top charging bin by a figure-eight belt and added into the furnace through the material pipe. The temperature is controlled at 1100℃ by energizing the electrodes and smelting for 0.5 hours to obtain the reduced material. S2. Maintain the temperature of 1100℃ from step S1, add 0.11 parts of lime to the reducing material at the top of the electric furnace, and continuously introduce carbon dioxide gas at a flow rate of 13.81 parts / h. Smelt for 2 hours, then heat to 1400℃ to melt and release the slag. S3. Add 3.30 parts of silica to the top of the electric furnace, spray 1.42 parts of liquid sulfur into the bottom of the molten liquid, and continuously introduce air at a flow rate of 11.98 parts / h. After smelting for 0.8h, a matte phase is formed, and the slag is discharged. S4. Add 0.74 parts of silica to the matte phase at the top of the electric furnace, continuously introduce air at a flow rate of 1.18 parts / h, and release the molten iron (matte phase) after smelting for 5.5 hours to obtain high-grade nickel matte.
[0050] The mass fractions of elements in the high-grade nickel matte obtained in this embodiment were determined to be: Ni 59.80%, Fe 11.75%, and S 28.45%.
[0051] Comparative Example 1 In the existing technology, the pyrometallurgical process used for limonite-type laterite nickel ore is the blast furnace method. However, since the limonite in Example 1 has an Al2O3 content as high as 7.37%, the slag in the blast furnace is sticky, making it difficult to raise the furnace temperature to 1500℃ or above, which is lower than the furnace temperature of about 1700℃ that can be achieved by electric furnace, making it very difficult to tap the slag and iron.
[0052] Comparative Example 2 If 100 parts of low-grade limonite-type lateritic nickel ore from Example 1 are used for smelting in an electric furnace, the low-grade limonite-type lateritic nickel ore is mixed with coke and heated to 950°C for 0.8 hours to obtain reduced material. Then, maintaining the temperature at 950°C, lime is added to the reduced material, and after smelting for 4 hours, the temperature is raised to 1550°C for successful tapping. The tapped iron is then placed in a first converter, with 4.87 parts of sulfur and 16.50 parts of silica added, and air is continuously introduced at a rate of 59.73 parts / hour. After 0.8 hours, matte is tapped, and then placed in a second converter for blowing, with 3.71 parts of silica added and air continuously introduced at a rate of 5.38 parts / hour. After 6 hours, matte is tapped, yielding low-grade nickel matte containing 34.39% Ni, 33.80% Fe, and 31.81% S. This is because the lack of carbon dioxide prevents an increase in the nickel content of the tapped iron, thus only low-grade nickel matte can be obtained, not high-grade nickel matte. In addition, the number of devices has also increased compared to the previous embodiment.
[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for preparing high-grade nickel matte from low-grade limonite-type laterite nickel ore, characterized in that, Including the following steps: S1. Mix low-grade limonite-type laterite nickel ore with a reducing agent and heat to 900℃~1150℃, smelt for 0.5h~1h to obtain reduced material; S2. Add lime and continuously purge carbon dioxide for 2-4 hours; then raise the temperature to 1400℃-1700℃ and release the slag. S3. Add silica, spray sulfur into the bottom of the molten liquid and continue to introduce air, smelt for 0.5h~1h and then release the slag. S4. Add silica, continuously circulate air, smelt for 5-7 hours, then release the molten metal to obtain high-grade nickel matte. The low-grade limonite-type laterite nickel ore has a Ni grade of 0.8% to 1%.
2. The method for preparing high-grade nickel matte from low-grade limonite-type laterite nickel ore as described in claim 1, characterized in that, In S1, the reducing agent is a carbonaceous reducing agent or a gaseous reducing agent. The carbonaceous reducing agent is one or more of coke, semi-coke, and coal, and the gaseous reducing agent includes one or more of hydrogen and carbon monoxide.
3. The method for preparing high-grade nickel matte from low-grade limonite-type laterite nickel ore as described in claim 2, characterized in that, When the reducing agent is a carbonaceous reducing agent, the mass ratio of low-grade limonite-type laterite nickel ore to the reducing agent is 100:(15~30). Alternatively, when the reducing agent is a gaseous reducing agent, the flow rate of the reducing agent should be 1.5 parts / h to 4 parts / h per 100 parts of low-grade limonite-type laterite nickel ore.
4. The method for preparing high-grade nickel matte from low-grade limonite-type laterite nickel ore as described in claim 1, characterized in that, In S2, the carbon dioxide flow rate is 5 parts / h to 22 parts / h per 100 parts of low-grade limonite-type laterite nickel ore.
5. The method for preparing high-grade nickel matte from low-grade limonite-type laterite nickel ore as described in claim 1, characterized in that, In S2, the mass ratio of low-grade limonite-type laterite nickel ore to lime is 100:(0.07~0.12).
6. The method for preparing high-grade nickel matte from low-grade limonite-type laterite nickel ore as described in claim 1, characterized in that, In S3, the mass ratio of low-grade limonite-type laterite nickel ore to silica is 100:(2~4).
7. The method for preparing high-grade nickel matte from low-grade limonite-type laterite nickel ore as described in claim 1, characterized in that, Optionally, in S3, the sulfur is liquid sulfur, and the mass ratio of low-grade limonite-type laterite nickel ore to liquid sulfur is 100:(1~2).
8. The method for preparing high-grade nickel matte from low-grade limonite-type laterite nickel ore as described in claim 1, characterized in that, In S3, the air flow rate is 8 to 20 parts per 100 parts of low-grade limonite-type laterite nickel ore.
9. The method for preparing high-grade nickel matte from low-grade limonite-type laterite nickel ore as described in claim 1, characterized in that, In S4, the mass ratio of low-grade limonite-type laterite nickel ore to silica is 100:(0.5~1.2).
10. The method for preparing high-grade nickel matte from low-grade limonite-type laterite nickel ore as described in claim 1, characterized in that, In S4, the air flow rate is 0.5 parts / h to 2 parts / h per 100 parts of low-grade limonite-type laterite nickel ore.