Method for producing stainless steel mother liquor through low-carbon melting based on nickel-chromium mineral synergy

Abstract

The invention belongs to the technical field of ferrous metallurgy, and particularly relates to a nickel-chromium mineral synergy-based low-carbon melting production method of stainless steel mother liquor, which comprises the following steps: S1, obtaining first nickel laterite ore, second nickel laterite ore, first chromium ore and second chromium ore; s2, the first laterite-nickel ore and the first chromium ore are mixed to obtain first mixed ore, and the first mixed ore, the second laterite-nickel ore and the second chromium ore are subjected to hydrogen pre-reduction to obtain first pre-reduced mixed ore, second pre-reduced laterite-nickel ore and second pre-reduced chromium ore; and S3, the first pre-reduced mixed ore is subjected to carbon blending and heating, a molten pool is obtained, heat preservation is conducted, stainless steel mother liquor is obtained, and second pre-reduced laterite-nickel ore and second pre-reduced chromium ore are added in batches in the heat preservation process. According to the method, the batch ore adding process is combined under the collaborative smelting reduction condition, and collaborative regulation and control of components of the stainless steel mother liquor and the smelting process are achieved.

Description

Technical Field

[0001] This application relates to the field of iron and steel metallurgy technology, specifically, to a method for producing stainless steel mother liquor by low-carbon melting based on the synergistic effect of nickel-chromium minerals. Background Technology

[0002] Stainless steel is a type of corrosion-resistant structural material with chromium and nickel as the main alloying elements. Its performance is highly dependent on the effective utilization rate of alloying elements and the stability of the smelting process. Currently, stainless steel production typically employs a process route of separately smelting ferronickel and ferrochrome, followed by remelting or converter adjustments to adjust the composition. This model is relatively mature in industry, but it has gradually revealed significant shortcomings in terms of energy consumption, resource utilization efficiency, and process synergy. While existing nickel-chromium co-smelting technologies can achieve energy integration and pollution control through raw material ratio optimization, this operation method, which involves one-time mixed ore addition, centralized pre-reduction, and smelting separation, still has certain problems. The problem lies in the lack of effective matching between the reduction behavior of metal oxides and the evolution of slag composition during the smelting process. When ferrochrome ore and laterite nickel ore are smelted at high temperatures, the different dissolution and reduction efficiencies of Cr2O3 at different locations in the slag can easily induce abrupt changes in slag viscosity and the formation of difficult-to-dissolve reduced phases, thereby limiting the migration of chromium to the metallic phase. This is detrimental to the stable increase of Cr content in the stainless steel mother liquor and the process control in co-melting reduction smelting.

[0003] From an overall process perspective, the synergistic melting and reduction process of nickel-chromium minerals has largely solved the problem of overlapping energy consumption and carbon emissions during smelting. However, with increasingly stringent environmental emission standards and ever-increasing requirements for low-carbon metallurgy, simply introducing new processes is no longer sufficient to meet the needs of industry development. Therefore, there is an urgent need for a new green technology route that can synergistically regulate the reduction behavior of chromium and nickel, the slag system, and reaction kinetics during the smelting process. Summary of the Invention

[0004] To solve the above-mentioned technical problems, this application provides a method for producing stainless steel mother liquor by low-carbon melting based on the synergistic effect of nickel and chromium minerals, comprising the following steps: S1, obtaining laterite nickel ore and chromium ore as raw materials, wherein the laterite nickel ore includes first laterite nickel ore and second laterite nickel ore, and the chromium ore includes first chromium ore and second chromium ore, wherein the mass ratio of the laterite nickel ore and the chromium ore is x, the mass ratio of the first laterite nickel ore and the second laterite nickel ore is y, and the mass ratio of the first chromium ore and the second chromium ore is y; S2, mixing the first laterite nickel ore and the first chromium ore to obtain the first... A mixed ore, the first mixed ore, the second laterite nickel ore and the second chromium ore are subjected to hydrogen pre-reduction to obtain a first pre-reduced mixed ore, a second pre-reduced laterite nickel ore and a second pre-reduced chromium ore; S3, the first pre-reduced mixed ore is carbonized and heated to obtain a molten pool, and the heat is maintained to obtain stainless steel mother liquor. The heat maintenance process also includes: dividing the second pre-reduced laterite nickel ore into z parts by mass and dividing the second pre-reduced chromium ore into z parts by mass, and adding them to the molten pool in the order of 1 part of second pre-reduced chromium ore and 1 part of second pre-reduced laterite nickel ore.

[0005] As a preferred embodiment of the method for producing stainless steel mother liquor by low-carbon melting based on the synergistic effect of nickel and chromium minerals as described in this application, in step S1, the laterite nickel ore and the chromium ore have a mesh size ≥ 200 mesh. By mass percentage, the composition of the laterite nickel ore includes: MgO: 10%-30%, SiO2: 20%-40%, NiO: 3%-5%, Fe2O3: 30%-40%, with the remainder being unavoidable impurities; the composition of the chromium ore includes: MgO: 5%-20%, Al2O3: 8%-20%, Cr2O3: 30%-55%, Fe2O3: 25%-35%, with the remainder being unavoidable impurities.

[0006] As a preferred embodiment of the method for producing stainless steel mother liquor by low-carbon melting based on nickel-chromium mineral synergy described in this application, in step S1, x is 2:1 and y is (1-3):1.

[0007] In a preferred embodiment of the method for producing stainless steel mother liquor by low-carbon melting based on nickel-chromium mineral synergy described in this application, z in step S3 is 1-2.

[0008] As a preferred embodiment of the method for producing stainless steel mother liquor based on low-carbon melting with nickel-chromium mineral synergy described in this application, in step S2, the hydrogen pre-reduction method specifically involves heating the first mixed ore, the second laterite nickel ore, and the second chromium ore to 900-1150℃, holding them at that temperature for 50-70 minutes in a hydrogen atmosphere, and then slowly cooling them to room temperature in the furnace to obtain the first pre-reduced mixed ore, the second pre-reduced laterite nickel ore, and the second pre-reduced chromium ore. The hydrogen flow rate is 400-600 mL / min.

[0009] As a preferred embodiment of the method for producing stainless steel mother liquor by low-carbon melting based on nickel-chromium mineral synergy described in this application, the holding temperature in step S3 is 1500-1650℃.

[0010] As a preferred embodiment of the method for producing stainless steel mother liquor based on low-carbon melting with nickel-chromium mineral synergy described in this application, in step S3, the MgO / SiO2 ratio of the slag in the stainless steel mother liquor is 0.4-0.7.

[0011] As a preferred embodiment of the method for producing stainless steel mother liquor based on low-carbon melting with nickel-chromium mineral synergy described in this application, in step S3, the Cr content in the stainless steel mother liquor is ≥13%.

[0012] As a preferred embodiment of the method for producing stainless steel mother liquor based on low-carbon melting with nickel-chromium mineral synergy described in this application, in step S3, the Ni content in the stainless steel mother liquor is ≥4%.

[0013] The beneficial effects of this application are as follows: This application proposes a method for producing stainless steel mother liquor through low-carbon melting based on the synergistic effect of nickel-chromium minerals. To address the aforementioned technical problems, this application proposes to transform the carbon reduction of minerals at 900-1150℃ into hydrogen reduction, thereby improving the pre-reduction effect of the target element while achieving carbon reduction. The minerals are added in stages instead of in a single batch, which maintains the Cr2O3 concentration in the molten pool within a controllable range during the reduction melting process, regulates the composition of the slag system, and inhibits the rapid formation of the spinel phase under high MgO and high Al2O3 conditions, avoiding a sudden increase in slag viscosity and melting temperature. Simultaneously, the batch addition of minerals allows the slag system to gradually complete composition adjustment and structural reconstruction during continuous reduction, which is beneficial for maintaining good slag-iron separation conditions, thereby promoting the continuous migration of chromium to the metallic phase and increasing the final Cr content in the stainless steel mother liquor.

[0014] This application achieves synergistic control over the composition of stainless steel mother liquor and the smelting process by introducing hydrogen pre-reduction to enhance the hydrogen energy of nickel and chromium ores and combining it with a batch ore addition process under synergistic molten reduction conditions. Hydrogen pre-reduction effectively reduces the difficulty of reducing metal oxides in the minerals, decreases dependence on carbonaceous reducing agents at high temperatures, thereby reducing smelting temperature, power consumption per ton of steel, and overall system energy consumption, and significantly reducing coke consumption and CO2 emission intensity. The batch ore addition method stabilizes the molten pool reaction, optimizes slag formation and oxygen potential conditions, promotes the full reduction of Ni and Cr elements and their stable entry into the metallic phase, which is particularly beneficial for increasing the Cr content in the stainless steel mother liquor, while inhibiting the formation of Cr(VI) in the slag, reducing environmental risks. The synergistic effect of hydrogen energy enhancement and batch ore addition enables this application to achieve energy saving and carbon reduction goals while improving alloy quality. Furthermore, this technical approach has good process adaptability and portability, and can be extended to the smelting processes of other multi-component alloys, demonstrating significant engineering application value and promising prospects. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0016] Figure 1 This is a SEM-EDS line scan of sample 2 from Example 1 of this application; Figure 2 This is a SEM-EDS line scan of sample 3 from Example 1 of this application; Figure 3 This is a graph showing the distribution of Ni and Cr content in sample 3 of Examples 1-2 and Comparative Examples 1-2 of this application as a function of batches of ore added. Figure 4 This is a distribution diagram of the slag composition of the test sample 3 in Examples 1-2 and Comparative Examples 1-2 in the MgO-Al2O3-SiO2 phase diagram; Figure 5 This is a SEM image of the test sample 3 of Comparative Example 1 and Examples 1-2 in this application.

[0017] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0018] The technical solutions in the embodiments will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0019] This application provides a method for producing stainless steel mother liquor by low-carbon melting based on nickel-chromium mineral synergy, comprising the following steps: S1. Obtain laterite nickel ore and chromium ore as raw materials. The laterite nickel ore includes first laterite nickel ore and second laterite nickel ore. The chromium ore includes first chromium ore and second chromium ore. The mass ratio of the laterite nickel ore to the chromium ore is x. The mass ratio of the first laterite nickel ore to the second laterite nickel ore is y. The mass ratio of the first chromium ore to the second chromium ore is y. The laterite nickel ore and the chromite have a mesh size ≥ 200 mesh. By mass percentage, the composition of the laterite nickel ore includes: MgO: 10%-30%, SiO2: 20%-40%, NiO: 3%-5%, Fe2O3: 30%-40%, with the remainder being unavoidable impurities; the composition of the chromite includes: MgO: 5%-20%, Al2O3: 8%-20%, Cr2O3: 30%-55%, Fe2O3: 25%-35%, with the remainder being unavoidable impurities; x is 2:1, y is (1-3):1.

[0020] S2. Mix the first laterite nickel ore and the first chromium ore to obtain a first mixed ore, and pre-reduce the first mixed ore, the second laterite nickel ore and the second chromium ore with hydrogen to obtain a first pre-reduced mixed ore, a second pre-reduced laterite nickel ore and a second pre-reduced chromium ore. The hydrogen pre-reduction method is as follows: the first mixed ore, the second laterite nickel ore and the second chromium ore are heated to 900-1150℃ and kept at that temperature for 50-70 minutes in a hydrogen atmosphere, and then slowly cooled to room temperature in the furnace to obtain the first pre-reduced mixed ore, the second pre-reduced laterite nickel ore and the second pre-reduced chromium ore, wherein the hydrogen flow rate is 400-600 mL / min. S3. The first pre-reduced mixed ore is carbonized and heated to obtain a molten pool, and then kept at the temperature to obtain stainless steel mother liquor. The temperature keeping process further includes: dividing the second pre-reduced laterite nickel ore into z parts by mass and dividing the second pre-reduced chromium ore into z parts by mass, and adding them to the molten pool in the order of 1 part of the second pre-reduced chromium ore and 1 part of the second pre-reduced laterite nickel ore. The order of adding 1 part of the second pre-reduced chromium ore and 1 part of the second pre-reduced laterite nickel ore is set as one batch of ore addition. Wherein, z is 1-2; the heat preservation temperature is 1500-1650℃; the MgO / SiO2 ratio of the slag in the stainless steel mother liquor is 0.4-0.7; the Cr content in the stainless steel mother liquor is ≥13%; and the Ni content in the stainless steel mother liquor is ≥4%.

[0021] The technical solution of this application will be further described below with reference to specific embodiments.

[0022] Example 1 S1. Obtain laterite nickel ore and chromium ore as raw materials. The laterite nickel ore includes first laterite nickel ore and second laterite nickel ore, and the chromium ore includes first chromium ore and second chromium ore. The mass ratio of laterite nickel ore to chromium ore is 2:1, the mass ratio of first laterite nickel ore to second laterite nickel ore is 3:1, and the mass ratio of first chromium ore to second chromium ore is 3:1. Obtain laterite nickel ore and chromium ore by crushing and screening to make their particle size >200 mesh. By mass percentage, the composition of laterite nickel ore includes: MgO: 21.4%, SiO2: 35.4%, NiO: 3.09%, Fe2O3: 33.6%, with the remainder being unavoidable impurities; the composition of chromium ore includes: MgO: 9.7%, Al2O3: 12.9%, Cr2O3: 39.3%, Fe2O3: 29%, with the remainder being unavoidable impurities. S2. The first laterite nickel ore and the first chromium ore were placed in a ball mill jar and ball-milled for 4 hours. After mixing, they were mixed and pressed under a pressure of 20 MPa to obtain the first mixed block. The first mixed block, the second laterite nickel ore and the second chromium ore were placed separately in a corundum crucible and heated to 1000℃ in a silicon molybdenum rod resistance furnace. The temperature was held for 60 minutes while hydrogen pre-reduction was carried out. After cooling in the furnace, the first pre-reduced mixed block, the second pre-reduced laterite nickel ore and the second pre-reduced chromium ore were obtained. Sample 1 was extracted from the first pre-reduced mixed block and tested. The hydrogen flow rate was 500 mL / min.

[0023] S3. The first pre-reduced mixture is carbonized, heated, and kept at a constant temperature to obtain stainless steel mother liquor. The holding process further includes adding 1 part of second pre-reduced chromite ore and 1 part of second pre-reduced laterite nickel ore to the molten pool in sequence. Specifically, the first pre-reduced mixture is carbonized and placed in a high-temperature furnace and held at 1600℃ for 60 minutes to form an initial molten pool and complete the basic melting process. After the initial molten pool is stably formed, the second pre-reduced chromite ore is added and kept at a constant temperature for 20 minutes, and sample 2 is extracted for testing. Then, the second pre-reduced laterite nickel ore is added and kept at a constant temperature for 20 minutes. After the ore addition is completed, sample 3 is extracted for testing. Adding 1 part of second pre-reduced chromite ore and 1 part of second pre-reduced laterite nickel ore in sequence constitutes one ore addition batch, for a total of 1 ore addition batch.

[0024] The test sample 1 was ground into powder with a mesh size greater than 200 for metallization rate and yield testing. The results showed that the metallization rate of Fe exceeded 80%, and the yields of Fe and Ni elements were both above 90%, thus achieving the preliminary pre-reduction enrichment of Ni and Fe.

[0025] Metallographic samples were prepared by longitudinally sectioning samples 2 and 3. SEM images of the bottom of the samples were taken under an electron microscope. EDS line scan analysis was performed on the chromite particles in samples 2 and 3 to determine the thickness of the chromite boundary layer based on elemental variations. (See also: [link to relevant documentation]) Figure 1 , Figure 2 , Figure 1 This is a SEM-EDS line scan of sample 2 from Example 1 of this application; Figure 2 This is a SEM-EDS line scan of sample 3 from Example 1 of this application; please refer to [link / reference]. Figure 5 , Figure 5 These are SEM images of test sample 3 from Comparative Example 1 and Examples 1-2 in this application. Figure 5 Image (b) shows the SEM image of sample 3 from Example 1. The results show that 20 minutes after the addition of chromite, a distinct boundary layer with a thickness of 9.12 μm began to form around the chromite. After 20 minutes of dissolution and reduction, lateritic nickel ore was added, and the boundary layer around the chromite particles increased from 5.05 μm to 14.17 μm. This indicates that batch-wise addition of ore has a practical promoting effect on the dissolution of chromite.

[0026] For ICP testing of sample 3 to determine the Cr and Ni content in the metal, please refer to [link to relevant documentation]. Figure 3 , Figure 3 This is a graph showing the distribution of Ni and Cr content in sample 3 of Examples 1-2 and Comparative Examples 1-2 of this application as a function of batches of ore added. Figure 3 This indicates that as the number of ore addition batches increased from 0 to 1, the Cr content in the stainless steel alloy mother liquor increased from 8.7% to 13%, while the Ni content remained at around 5%. This improved the Cr content in the stainless steel mother liquor to a certain extent, while maintaining the Ni content at >4%.

[0027] For XRF analysis of the slag composition of sample 3, please refer to [link to relevant documentation]. Figure 4 , Figure 4 This is a distribution diagram of the slag composition of the test sample 3 in Examples 1-2 and Comparative Examples 1-2 in the MgO-Al2O3-SiO2 phase diagram; Figure 4This indicates that as the number of ore addition batches increases from 0 to 1, the melting point of the slag composition decreases significantly. Furthermore, with the continuous addition of minerals, the MgO / SiO2 ratio of the slag remains stable between 0.5 and 0.6. At the same time, this can greatly improve the solubility and reduction of chromite and increase the Cr content in the stainless steel mother liquor.

[0028] Example 2 S1. Obtain laterite nickel ore and chromium ore as raw materials. The laterite nickel ore includes first laterite nickel ore and second laterite nickel ore, and the chromium ore includes first chromium ore and second chromium ore. The mass ratio of laterite nickel ore to chromium ore is 2:1, the mass ratio of first laterite nickel ore to second laterite nickel ore is 1:1, and the mass ratio of first chromium ore to second chromium ore is 1:1. Obtain laterite nickel ore and chromium ore by crushing and screening to make their particle size >200 mesh. By mass percentage, the composition of laterite nickel ore includes: MgO: 21.4%, SiO2: 35.4%, NiO: 3.09%, Fe2O3: 33.6%, with the remainder being unavoidable impurities; the composition of chromium ore includes: MgO: 9.7%, Al2O3: 12.9%, Cr2O3: 39.3%, Fe2O3: 29%, with the remainder being unavoidable impurities. S2. The first laterite nickel ore and the first chromium ore were placed in a ball mill jar and ball-milled for 4 hours. After mixing, they were mixed and pressed under a pressure of 20 MPa to obtain the first mixed block. The first mixed block, the second laterite nickel ore and the second chromium ore were placed separately in a corundum crucible and heated to 1000℃ in a silicon molybdenum rod resistance furnace. The temperature was held for 60 minutes while hydrogen pre-reduction was carried out. After cooling in the furnace, the first pre-reduced mixed block, the second pre-reduced laterite nickel ore and the second pre-reduced chromium ore were obtained. Sample 1 was extracted from the first pre-reduced mixed block and tested. The hydrogen flow rate was 500 mL / min.

[0029] S3. The first pre-reduced mixed block is carbonized, heated, and kept at a constant temperature to obtain stainless steel mother liquor. Specifically, the first pre-reduced mixed block is carbonized and placed in a high-temperature furnace and kept at 1600℃ for 60 minutes to form an initial molten pool and complete the basic melting process. The second pre-reduced laterite nickel ore and the second pre-reduced chromium ore are divided into two equal parts by mass. After the initial molten pool is stably formed, they are added to the molten pool in the order of 1 part of the second pre-reduced chromium ore and 1 part of the second pre-reduced laterite nickel ore. Among them, the first part of the second pre-reduced chromium ore is added, kept at a constant temperature for 20 minutes, and sample 2 is extracted for testing. Then the first part of the second pre-reduced laterite nickel ore is added and kept at a constant temperature for 20 minutes. Then the second part of the second pre-reduced chromium ore is added and kept at a constant temperature for 20 minutes. After the ore addition is completed, sample 3 is extracted for testing. The order of adding 1 part of the second pre-reduced chromium ore and 1 part of the second pre-reduced laterite nickel ore is set as 1 ore addition batch, and a total of 2 ore addition batches are made.

[0030] The test sample 1 was ground into powder with a mesh size greater than 200 for metallization rate and yield testing. The results showed that the metallization rate of Fe exceeded 80%, and the yields of Fe and Ni elements were both above 90%, thus achieving the preliminary pre-reduction enrichment of Ni and Fe.

[0031] Sample 3 was longitudinally sectioned to prepare a metallographic sample. SEM images of the bottom of the sample were taken under an electron microscope. (See attached image.) Figure 5 , Figure 5 These are SEM images of test sample 3 from Comparative Example 1 and Examples 1-2 in this application. Figure 5 Image (c) is the SEM image of sample 3 in Example 2. The Cr content in the slag is increasing continuously, which indicates that the increasing number of minerals in batches has a real promoting effect on the dissolution of chromite.

[0032] For ICP testing of sample 3 to determine the Cr and Ni content in the metal, please refer to [link to relevant documentation]. Figure 3 , Figure 3 This is a graph showing the distribution of Ni and Cr content in sample 3 of Examples 1-2 and Comparative Examples 1-2 of this application as a function of batches of ore added. Figure 3 This indicates that as the number of ore addition batches increased from 0 to 2, the Cr content in the stainless steel alloy mother liquor increased from 8.7% to 16.6%, while the Ni content remained at around 5%. This significantly increased the Cr content in the mother liquor while maintaining the Ni content at >4%.

[0033] For XRF analysis of the slag composition of sample 3, please refer to [link to relevant documentation]. Figure 4 , Figure 4 This is a distribution diagram of the slag composition of the test sample 3 in Examples 1-2 and Comparative Examples 1-2 in the MgO-Al2O3-SiO2 phase diagram; Figure 4 This indicates that as the number of ore addition batches increases from 0 to 2, the melting point of the slag composition decreases significantly. Furthermore, with the continuous addition of minerals, the MgO / SiO2 ratio of the slag remains stable between 0.5 and 0.6. At the same time, this can greatly improve the solubility and reduction of chromite and increase the Cr content in the stainless steel mother liquor.

[0034] Comparative Example 1 Unlike Example 2, this comparative example did not use a batch addition method to prepare the stainless steel mother liquor. Instead, all laterite nickel ore and chromium ore were directly mixed, pressed, pre-reduced, carbonized, heated, and held at a specific temperature to obtain the stainless steel mother liquor. Sample 3 was extracted from the stainless steel mother liquor for testing. Sample 3 was longitudinally sectioned to prepare a metallographic sample, and SEM images of the bottom of the sample were taken under an electron microscope. Please refer to... Figure 5 , Figure 5 These are SEM images of test sample 3 from Comparative Example 1 and Examples 1-2 in this application. Figure 5In Figure (a), the SEM image of sample 3 in Comparative Example 1 shows that the chromite particles in sample 3 in Comparative Example 1 did not form an obvious boundary layer, indicating that the chromite was not fully dissolved.

[0035] For ICP testing of sample 3 to determine the Cr and Ni content in the metal, please refer to [link to relevant documentation]. Figure 3 , Figure 3 This is a graph showing the distribution of Ni and Cr content in sample 3 of Examples 1-2 and Comparative Examples 1-2 of this application as a function of batches of ore added. Figure 3 This indicates that when ore is not added in batches, the Cr content in the stainless steel mother liquor is 8.7%, which is significantly lower than 13% and 16.6% in Examples 1 and 2, respectively, and the increase in Cr content is limited.

[0036] For XRF analysis of the slag composition of sample 3, please refer to [link to relevant documentation]. Figure 4 , Figure 4 This is a distribution diagram of the slag composition of the test sample 3 in Examples 1-2 and Comparative Examples 1-2 in the MgO-Al2O3-SiO2 phase diagram; Figure 4 This indicates that when ore is not added in batches, the slag composition remains unchanged at the melting point of the slag system, and the MgO / SiO2 ratio of the slag remains stable between 0.5 and 0.6.

[0037] Comparative Example 2 S1. Obtain laterite nickel ore and chromium ore as raw materials. The laterite nickel ore includes first laterite nickel ore and second laterite nickel ore, and the chromium ore includes first chromium ore and second chromium ore. The mass ratio of laterite nickel ore to chromium ore is 2:1, the mass ratio of first laterite nickel ore to second laterite nickel ore is 1:3, and the mass ratio of first chromium ore to second chromium ore is 1:3. Obtain laterite nickel ore and chromium ore by crushing and screening to make their particle size >200 mesh. By mass percentage, the composition of laterite nickel ore includes: MgO: 21.4%, SiO2: 35.4%, NiO: 3.09%, Fe2O3: 33.6%, with the remainder being unavoidable impurities; the composition of chromium ore includes: MgO: 9.7%, Al2O3: 12.9%, Cr2O3: 39.3%, Fe2O3: 29%, with the remainder being unavoidable impurities. S2. The first laterite nickel ore and the first chromium ore were placed in a ball mill jar and ball-milled for 4 hours. After mixing, they were mixed and pressed under a pressure of 20 MPa to obtain the first mixed block. The first mixed block, the second laterite nickel ore and the second chromium ore were placed separately in a corundum crucible and heated to 1000℃ in a silicon molybdenum rod resistance furnace. The temperature was held for 60 minutes while hydrogen pre-reduction was carried out. After cooling in the furnace, the first pre-reduced mixed block, the second pre-reduced laterite nickel ore and the second pre-reduced chromium ore were obtained. Sample 1 was extracted from the first pre-reduced mixed block and tested. The hydrogen flow rate was 500 mL / min.

[0038] S3. The first pre-reduced mixture is carbonized, heated, and held at a certain temperature to obtain stainless steel mother liquor. Specifically, the first pre-reduced mixture is carbonized and placed in a high-temperature furnace at 1600℃ for 60 minutes to form an initial molten pool and complete the basic melting process. The second pre-reduced laterite nickel ore and the second pre-reduced chromium ore are divided into three equal parts by mass. After the initial molten pool has stabilized, they are added to the molten pool in the order of 1 part of the second pre-reduced chromium ore and 1 part of the second pre-reduced laterite nickel ore. The first part of the second pre-reduced chromium ore is added and held at a certain temperature. Sample 2 was taken for testing after 20 minutes. Then, the first part of the second pre-reduced laterite nickel ore was added and kept warm for 20 minutes. Then, the second part of the second pre-reduced chromium ore was added and kept warm for 20 minutes. Then, the second part of the second pre-reduced laterite nickel ore was added and kept warm for 20 minutes. Then, the third part of the second pre-reduced chromium ore was added and kept warm for 20 minutes. Then, the third part of the second pre-reduced laterite nickel ore was added and kept warm for 20 minutes. After the ore addition was completed, sample 3 was taken for testing. It was set that adding 1 part of the second pre-reduced chromium ore and 1 part of the second pre-reduced laterite nickel ore in sequence constitutes 1 ore addition batch, and a total of 3 ore addition batches were made.

[0039] The test sample 1 was ground into powder with a mesh size greater than 200 for metallization rate and yield testing. The results showed that the metallization rate of Fe exceeded 80%, and the yields of Fe and Ni elements were both above 90%, thus achieving the preliminary pre-reduction enrichment of Ni and Fe.

[0040] For ICP testing of sample 3 to determine the Cr and Ni content in the metal, please refer to [link to relevant documentation]. Figure 3 , Figure 3 This is a graph showing the distribution of Ni and Cr content in sample 3 of Examples 1-2 and Comparative Examples 1-2 of this application as a function of batches of ore added. Figure 3 This indicates that as the number of ore addition batches increased from 2 to 3, the Cr content in the stainless steel alloy mother liquor decreased from 16.6% to 5%, while the Ni content remained at around 5%. This is sufficient to show that more ore addition batches do not necessarily lead to a higher Cr content in the alloy, and that there are certain limits to the composition of the slag.

[0041] For XRF analysis of the slag composition of sample 3, please refer to [link to relevant documentation]. Figure 4 , Figure 4 This is a distribution diagram of the slag composition of the test sample 3 in Examples 1-2 and Comparative Examples 1-2 in the MgO-Al2O3-SiO2 phase diagram; Figure 4 This indicates that as the number of ore addition batches increased from 2 to 3, the melting point of the slag components in the slag system increased significantly, and with the continuous addition of minerals, the MgO / SiO2 ratio of the slag became unstable, rising to 0.82.

[0042] from Figure 4It can be seen that the MgO / SiO2 ratio of the slag in Comparative Example 1 and Examples 1-2 of Sample 3 remained between 0.5 and 0.6. Furthermore, the melting point of the slag in Sample 3 of Examples 1 and 2 continuously decreased, and the slag phase gradually changed from the insoluble spinel phase to the forsterite phase. However, when the number of ore addition batches increased to 3, the melting point of the slag increased significantly, and the MgO / SiO2 ratio also increased to 0.82. The phase changed to the spinel phase, leading to slag instability and deterioration. This severely affected the dissolution and reduction of chromite, thereby inhibiting the reduction of Cr2O3 and significantly reducing the Cr content in the alloy.

[0043] As can be seen from the above examples and comparative examples: Example 2, combined with Comparative Example 1, demonstrates that through high-temperature melting and reduction of nickel-chromium minerals and analysis using methods such as SEM, XRF, and ICP, an optimized batch addition of nickel-chromium minerals was proposed. By using suitable slag to dissolve the chromium ore, the dynamic structure of the slag system is maintained, avoiding the problem of high Cr2O3 concentration caused by single-batch mixing. This significantly broadens the reducible window of Cr2O3, improves the solubility of Cr2O3, and enhances the migration efficiency of Cr into the alloy. Example 2, combined with Comparative Example 2, shows that as the number of ore addition batches increases to three, the Cr content in the stainless steel alloy mother liquor decreases from 16.6% to 5%, while the Ni content remains basically maintained at around 5%. This sufficiently demonstrates that more ore addition batches do not necessarily lead to a higher Cr content in the alloy. The slag composition has certain limitations. After three ore addition batches, the slag system deteriorates, severely affecting the dissolution and reduction of chromium ore, thereby inhibiting the reduction of Cr2O3 and significantly reducing the Cr content in the alloy. Combined with Examples 1-2 and Comparative Examples 1-2, it is shown that this application provides a novel method for hydrogen pre-reduction and batch ore addition, which can reduce carbon emissions during the smelting process to a certain extent, increase the Cr and Ni content and recovery rate in stainless steel mother liquor, optimize the slag system, and reduce energy loss, thus achieving energy integration and pollution control.

[0044] This application proposes a method for producing stainless steel mother liquor through low-carbon melting based on the synergistic effect of nickel-chromium minerals. To address the aforementioned technical problems, this application proposes to transform the carbon reduction of minerals at 900-1150℃ into hydrogen reduction, thereby improving the pre-reduction effect of the target element while achieving carbon reduction. The minerals are added in stages instead of in a single batch, which maintains the Cr2O3 concentration in the molten pool within a controllable range during the reduction melting process, regulates the composition of the slag system, and inhibits the rapid formation of the spinel phase under high MgO and high Al2O3 conditions, avoiding a sudden increase in slag viscosity and melting temperature. Simultaneously, the batch addition of minerals allows the slag system to gradually complete composition adjustment and structural reconstruction during continuous reduction, which is beneficial for maintaining good slag-iron separation conditions, thereby promoting the continuous migration of chromium to the metallic phase and increasing the final Cr content in the stainless steel mother liquor.

[0045] This application achieves synergistic control over the composition of stainless steel mother liquor and the smelting process by introducing hydrogen pre-reduction to enhance the hydrogen energy of nickel and chromium ores and combining it with a batch ore addition process under synergistic molten reduction conditions. Hydrogen pre-reduction effectively reduces the difficulty of reducing metal oxides in the minerals, decreases dependence on carbonaceous reducing agents at high temperatures, thereby reducing smelting temperature, power consumption per ton of steel, and overall system energy consumption, and significantly reducing coke consumption and CO2 emission intensity. The batch ore addition method stabilizes the molten pool reaction, optimizes slag formation and oxygen potential conditions, promotes the full reduction of Ni and Cr elements and their stable entry into the metallic phase, which is particularly beneficial for increasing the Cr content in the stainless steel mother liquor, while inhibiting the formation of Cr(VI) in the slag, reducing environmental risks. The synergistic effect of hydrogen energy enhancement and batch ore addition enables this application to achieve energy saving and carbon reduction goals while improving alloy quality. Furthermore, this technical approach has good process adaptability and portability, and can be extended to the smelting processes of other multi-component alloys, demonstrating significant engineering application value and promising prospects.

[0046] The above description is only a preferred embodiment of this application and does not limit the patent scope of this application. All equivalent structural transformations made using the content of this application's specification under the inventive concept of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A method for producing stainless steel mother liquor by low-carbon melting based on the synergistic effect of nickel-chromium minerals, characterized in that, Includes the following steps: S1. Obtain laterite nickel ore and chromium ore as raw materials. The laterite nickel ore includes first laterite nickel ore and second laterite nickel ore. The chromium ore includes first chromium ore and second chromium ore. The mass ratio of the laterite nickel ore to the chromium ore is x. The mass ratio of the first laterite nickel ore to the second laterite nickel ore is y. The mass ratio of the first chromium ore to the second chromium ore is y. S2. Mix the first laterite nickel ore and the first chromium ore to obtain a first mixed ore, and pre-reduce the first mixed ore, the second laterite nickel ore and the second chromium ore with hydrogen to obtain a first pre-reduced mixed ore, a second pre-reduced laterite nickel ore and a second pre-reduced chromium ore. S3. The first pre-reduced mixed ore is carbonized and heated to obtain a molten pool, and then kept at the temperature to obtain stainless steel mother liquor. The temperature keeping process further includes: dividing the second pre-reduced laterite nickel ore into z parts by mass and dividing the second pre-reduced chromium ore into z parts by mass, and adding them to the molten pool in the order of 1 part of the second pre-reduced chromium ore and 1 part of the second pre-reduced laterite nickel ore.

2. The method for producing stainless steel mother liquor by low-carbon melting based on nickel-chromium mineral synergy according to claim 1, characterized in that, In step S1, the laterite nickel ore and the chromite have a mesh size ≥ 200 mesh. By mass percentage, the composition of the laterite nickel ore includes: MgO: 10%-30%, SiO2: 20%-40%, NiO: 3%-5%, Fe2O3: 30%-40%, with the remainder being unavoidable impurities; the composition of the chromite includes: MgO: 5%-20%, Al2O3: 8%-20%, Cr2O3: 30%-55%, Fe2O3: 25%-35%, with the remainder being unavoidable impurities.

3. The method for producing stainless steel mother liquor by low-carbon melting based on nickel-chromium mineral synergy according to claim 1, characterized in that, In step S1, x is 2:1 and y is (1-3):

1.

4. The method for producing stainless steel mother liquor by low-carbon melting based on nickel-chromium mineral synergy according to claim 1, characterized in that, In step S3, z is 1-2.

5. The method for producing stainless steel mother liquor by low-carbon melting based on nickel-chromium mineral synergy according to claim 1, characterized in that, In step S2, the hydrogen pre-reduction method is as follows: the first mixed ore, the second laterite nickel ore, and the second chromium ore are heated to 900-1150℃ and kept at that temperature for 50-70 minutes in a hydrogen atmosphere, and then slowly cooled to room temperature in the furnace to obtain the first pre-reduced mixed ore, the second pre-reduced laterite nickel ore, and the second pre-reduced chromium ore. The flow rate of the hydrogen is 400-600 mL / min.

6. The method for producing stainless steel mother liquor by low-carbon melting based on nickel-chromium mineral synergy according to claim 1, characterized in that, In step S3, the insulation temperature is 1500-1650℃.

7. The method for producing stainless steel mother liquor by low-carbon melting based on nickel-chromium mineral synergy according to claim 1, characterized in that, In step S3, the MgO / SiO2 ratio of the slag in the stainless steel mother liquor is 0.4-0.

7.

8. The method for producing stainless steel mother liquor by low-carbon melting based on nickel-chromium mineral synergy according to claim 1, characterized in that, In step S3, the Cr content in the stainless steel mother liquor is ≥13%.

9. The method for producing stainless steel mother liquor by low-carbon melting based on nickel-chromium mineral synergy according to claim 1, characterized in that, In step S3, the Ni content in the stainless steel mother liquor is ≥4%.

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