Method for preparing nickel-chromium oxide pellets by co-processing laterite nickel ore and stainless steel slag and its application

Abstract

This invention discloses a method for co-preparing nickel-chromium oxide pellets using laterite nickel ore and stainless steel slag, and its application, relating to the fields of metallurgical solid waste resource utilization and mineral processing technology. The method includes: raw material pretreatment: drying, crushing, and grinding laterite nickel ore and stainless steel slag to obtain laterite nickel ore powder and stainless steel slag powder with a particle size of -0.074 mm or more (more than 60%) and a D50 of 0.06 mm to 0.07 mm; pelletizing: mixing laterite nickel ore powder and stainless steel slag powder at a mass ratio of (75~85):20, and then forming pellets to obtain green pellets; oxidative roasting: the green pellets undergo preheating, roasting, and homogenization treatment to obtain nickel-chromium oxide pellets; wherein the roasting temperature is 1265℃~1285℃. The application is to use the nickel-chromium oxide pellets as a charge in a hydrogen-based vertical shaft furnace-electric furnace for stainless steel smelting. This invention solves the problems of stainless steel slag storage and comprehensive utilization of laterite nickel ore. By utilizing the complementary properties of the two materials, high-strength, high-metallurgical-performance nickel-chromium oxide pellets are obtained.

Description

Technical Field

[0001] This invention relates to the field of metallurgical solid waste resource utilization and mineral processing technology, specifically to a method for preparing nickel-chromium oxide pellets by co-processing laterite nickel ore and stainless steel slag, and its application. Background Technology

[0002] Nickel is an important alloying element in the production of stainless steel. The production of nickel-based stainless steel usually uses electrolytic nickel prepared from nickel sulfide ore as the source of metallic nickel. However, as nickel sulfide ore, which is easy to mine, becomes increasingly scarce and the development cost becomes increasingly high, producing ferronickel from laterite nickel ore and replacing electrolytic nickel as the source of metallic nickel is an important trend for the continued development of the stainless steel industry.

[0003] Steel slag, a solid waste generated during the smelting process, is alkaline and its main components include CaO and SiO2, while also containing Ni, Cr2O3, Fe, Al2O3, MgO, P, and S. With increasing steel production, the annual stockpiled steel slag is constantly increasing, with slag accounting for 10% to 15% of the steel produced per ton of steel. my country's steel slag utilization rate is only about 25%, and the domestic stockpiled volume has reached hundreds of millions of tons. Steel slag is classified into nickel-chromium-ferroalloy stainless steel slag, electric furnace steel slag, and open-hearth furnace steel slag. Currently, the nickel-chromium-ferroalloy stainless steel slag produced has low recovery rates due to its nickel and chromium content; most of it is stockpiled in metallurgical slag plants, with only a small amount of large slag steel used for resupply to the steelmaking process. The remaining nickel-chromium-ferroalloy stainless steel slag is not yet being effectively utilized. Summary of the Invention

[0004] This invention addresses the challenges of stainless steel slag stockpiling and reuse, as well as the comprehensive utilization of laterite nickel ore resources in the prior art, by providing a method for the synergistic preparation of nickel-chromium oxide pellets using laterite nickel ore and stainless steel slag, and its application.

[0005] Therefore, in a first aspect, the present invention provides a method for synergistically preparing nickel-chromium oxide pellets using laterite nickel ore and stainless steel slag, comprising:

[0006] Raw material pretreatment: The dried laterite nickel ore and the dried stainless steel slag are crushed separately and then ground to obtain laterite nickel ore powder and stainless steel slag powder; wherein the particle size of the laterite nickel ore powder is more than 60% with a particle size of -0.074mm and a D50 of 0.06mm~0.07mm, and the particle size of the stainless steel slag powder is more than 60% with a particle size of -0.074mm and a D50 of 0.06mm~0.07mm;

[0007] Pelletizing: The laterite nickel ore powder and the stainless steel slag powder are mixed and then formed into pellets to obtain green pellets; wherein the mass ratio of the laterite nickel ore powder to the stainless steel slag powder is (75~85):20;

[0008] Oxidation roasting: The green pellets are preheated, roasted and homogenized to obtain the nickel-chromium oxide pellets; wherein the roasting temperature is 1265℃~1285℃.

[0009] Furthermore, in the laterite nickel ore, the mass fraction of iron is 40%~50%, the mass fraction of nickel is 0.7%~1.5%, the mass fraction of Cr2O3 is 3%~6%, the mass fraction of SiO2 is 4%~8%, the mass fraction of MgO is 2%~4%, and the mass fraction of Al2O3 is 3%~7%.

[0010] Furthermore, in the stainless steel slag, the mass fraction of Cr2O3 is 3%~6%, the mass fraction of CaO is 45%~60%, the mass fraction of SiO2 is 25%~35%, the mass fraction of MgO is 3%~6%, the mass fraction of Al2O3 is 1%~3%, and the basicity CaO / SiO2 is between 1.7 and 2.0.

[0011] Further, the laterite nickel ore and stainless steel slag are dried, including:

[0012] The moisture content of the dried laterite nickel ore is controlled to be less than 10 wt%, and the moisture content of the dried stainless steel slag is controlled to be less than 10 wt%.

[0013] Furthermore, the process of forming pellets includes: using a disc pelletizer to form pellets, controlling the moisture content of the green pellets to be 20wt%~24wt%, and controlling the particle size of the green pellets to be 14mm~16mm.

[0014] Furthermore, the preheating includes: a preheating temperature of 940℃~960℃ and a preheating time of 10min~20min.

[0015] Furthermore, the roasting time is 10 min to 20 min.

[0016] Furthermore, the heat equalization includes: a heat equalization temperature of 990℃~1010℃ and a heat equalization time of 4min~6min.

[0017] Furthermore, the nickel-chromium oxide pellets have a nickel content of not less than 0.8 wt%, a Cr2O3 content of 3 wt% to 6 wt%, and a compressive strength greater than 2000 N.

[0018] In a second aspect, the present invention provides an application of nickel-chromium oxide pellets, wherein the nickel-chromium oxide pellets prepared by the above method are used as raw materials for hydrogen-based vertical shaft furnace-electric furnace smelting of stainless steel.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects:

[0020] The present invention provides a method for co-preparing nickel-chromium oxide pellets using laterite nickel ore and stainless steel slag, which solves the problems of stainless steel slag storage and comprehensive utilization of laterite nickel ore, realizing the greening of the entire "pelletizing-smelting" process, and utilizing the complementary properties of the two materials to form a synergistic effect.

[0021] (1) By using the particles of stainless steel slag as a "rigid skeleton", the problem of poor pelletization and easy agglomeration of laterite nickel ore is effectively improved, and the compressive strength of the pellets is increased by about 1 time. At the same time, the acidic oxides provided by laterite nickel ore can fix the expansion source in stainless steel slag, reduce the burn-off damage of laterite nickel ore, and thus improve the reducibility of the pellets.

[0022] (2) The calcium and silicon components in stainless steel slag are used to adjust the basicity of the pellets and improve the formation of the liquid phase structure of the pellets. In addition, the residual iron, nickel and chromium metal resources in stainless steel slag improve the grade of the pellets and the metal recovery rate, effectively reducing the overall cost of using the pellets. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in the embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0024] Figure 1 Microstructure diagram and SEM-EDS analysis of nickel-chromium oxide pellets provided in embodiments of the present invention. (Includes sub-figures) Figure 1 (a) is a 50x magnification image of nickel-chromium oxide pellets. Figure 1 (b) is a 100x magnification image of the nickel-chromium oxide pellets. Figure 1 (c) is a 500x magnification image of the nickel-chromium oxide pellets. Figure 1 (d) is a 2500x magnification microstructure diagram of nickel-chromium oxide pellets. Figure 1 (e) is the point 1 composition analysis spectrum of nickel-chromium oxide pellets. Figure 1 (f) is the point 2 composition analysis spectrum of nickel-chromium oxide pellets. Detailed Implementation

[0025] To better understand the above technical solutions, the technical solutions of the embodiments of this application will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of this application and the specific features in the embodiments are detailed descriptions of the technical solutions of the embodiments of this application, rather than limitations on the technical solutions of this application. In the absence of conflict, the embodiments of this application and the technical features in the embodiments can be combined with each other.

[0026] A first aspect of this invention provides a method for synergistically preparing nickel-chromium oxide pellets using laterite nickel ore and stainless steel slag, comprising:

[0027] Raw material pretreatment: Laterite nickel ore and stainless steel slag are dried, and the dried laterite nickel ore and stainless steel slag are crushed separately and then ground to obtain laterite nickel ore powder and stainless steel slag powder. The particle size of the laterite nickel ore powder is more than 60% with a particle size of -0.074 mm and a D50 of 0.06 mm to 0.07 mm, and the particle size of the stainless steel slag powder is more than 60% with a particle size of -0.074 mm and a D50 of 0.06 mm to 0.07 mm.

[0028] Pelletizing: Mix laterite nickel ore powder and stainless steel slag powder, and then form them into pellets to obtain green pellets; wherein, the mass ratio of laterite nickel ore powder to stainless steel slag powder is (75~85):20;

[0029] Oxidation roasting: The green pellets are preheated, roasted and homogenized to obtain nickel-chromium oxide pellets; the roasting temperature is 1265℃~1285℃.

[0030] This invention provides a method for co-preparing nickel-chromium oxide pellets using laterite nickel ore and stainless steel slag. The method utilizes the abundant CaO in the stainless steel slag as a flux to precisely adjust the pellet basicity. Furthermore, the SiO2 in the stainless steel slag, along with other components, forms a diopside-dominated liquid phase during roasting, thereby enhancing pellet consolidation. Simultaneously, the natural binding properties of laterite nickel ore partially replace bentonite, reducing costs. The gangue components (such as MgO and SiO2) in the laterite nickel ore, together with the stainless steel slag components, construct a MgO-SiO2-CaO multi-component liquid phase system, further optimizing the pellet's pelletizing properties and high-temperature performance. This method effectively overcomes the expansion and pulverization problem caused by the hydration of free CaO in stainless steel slag and eliminates the leaching risk of heavy metals such as chromium through high-temperature solidification. The prepared nickel-chromium oxide pellets have excellent compressive strength, reducibility and high-temperature metallurgical properties. All its indicators fully meet the smelting requirements of hydrogen-based shaft furnaces. It is a high-quality raw material that can be used to produce stainless steel mother liquor, realizing the efficient recovery of valuable metals (nickel, chromium and iron) and the green value-added utilization of solid waste resources.

[0031] In some embodiments, the laterite nickel ore contains 40%–50% iron, 0.7%–1.5% nickel, 4%–8% SiO2, 2%–4% MgO, 3%–7% Al2O3, approximately 25 wt%–35 wt% natural moisture, 10 wt%–15 wt% loss on ignition, and fine particle size. These components and physical properties directly affect pelletizing performance, roasting densification degree, and the final strength of the oxidized pellets. In stainless steel slag, the CaO content is 45%–60%, the SiO2 content is 25%–35%, the MgO content is 3%–6%, and the Al2O3 content is 1%–3%. Its basicity (CaO / SiO2) is typically between 1.7 and 2.0. Physically, it contains a certain amount of free CaO (f-CaO) and free MgO (f-MgO), is easily hydrated and expands, has porous particles, and is alkaline, which helps adjust the basicity and liquid phase ratio of the pellets.

[0032] Understandably, stainless steel slag is volumetrically unstable due to the presence of f-CaO and f-MgO, making it prone to expansion and pulverization. Furthermore, it has low recovery rates for valuable metals such as nickel and chromium, and chromium possesses potential environmental toxicity. Relevant testing data indicates that laterite nickel ore and stainless steel slag have complementary raw material characteristics:

[0033] Laterite nickel ore: contains iron (40~50%) and nickel (0.7~1.5%), but has high moisture content, fine particle size, and many magnesium, aluminum and silicon impurities;

[0034] Stainless steel slag: enriched with calcium, iron, chromium and a small amount of nickel-chromium metal particles, it is alkaline (CaO / SiO2≈1.9~2.0) and can replace flux (such as limestone).

[0035] Synergistic effects: Stainless steel slag contains a large amount of calcium oxide, which can replace limestone to adjust the basicity of laterite nickel ore. CaO / MgO can neutralize the acidic gangue of laterite nickel ore and lower the roasting and melting temperature. The residual nickel / chromium in stainless steel slag can improve the metallization rate of pellets. Solidification of heavy metals (such as chromium): High-temperature roasting causes chromium to form a stable spinel phase (FeCr2O4); at the same time, stainless steel slag enriches calcium, iron, chromium and a small amount of nickel-chromium metal particles, which, after replacing part of the limestone, can effectively improve the metallization rate of pellets and improve the grade of pellets.

[0036] In some embodiments, drying laterite nickel ore and stainless steel slag includes:

[0037] The moisture content of the dried laterite nickel ore is controlled to be less than 10 wt%, and the moisture content of the dried stainless steel slag is controlled to be less than 10 wt%.

[0038] Specifically, controlling the moisture content of the dried laterite nickel ore and stainless steel slag to less than 10 wt% can prevent bursting, bubbling, or pellet breakage caused by rapid evaporation of crystal water during roasting. If the moisture content is too high, the pellets are prone to cracking or bursting during the preheating stage, affecting the yield and strength of the finished product.

[0039] In some embodiments, pelletizing includes: using a disc pelletizer to pelletize, controlling the moisture content of the green pellets to be 20wt%~24wt%, and controlling the particle size of the green pellets to be 14mm~16mm.

[0040] Specifically, controlling the moisture content of green pellets at 20wt%~24wt% ensures good material bonding and uniform pellet shape during pelletizing. Too little moisture leads to difficulty in pelletizing, rough surface, and insufficient strength; too much moisture causes pellets to stick to the pan or deform. Controlling the green pellet size at 14mm~16mm balances strength and permeability. Due to the large burn-off of laterite nickel ore, if the particle size is too small during oxidative roasting, the pellets will shrink too much and are prone to pulverization during reduction; if the particle size is too large, it will be difficult to control during pelletizing and will reduce the uniformity of roasting.

[0041] In some embodiments, preheating includes: a preheating temperature of 940°C to 960°C and a preheating time of 10 min to 20 min.

[0042] Specifically, preheating at 940℃~960℃ for 10min~20min allows the pellets to fully dehydrate and form an initial binding phase. Too low a temperature or insufficient time results in a loose structure and low strength; too high a temperature or too long a time can cause local melting, adhesion, and increased energy consumption.

[0043] In some embodiments, the calcination time is 10 min to 20 min.

[0044] Specifically, a calcination time of 10 to 20 minutes ensures sufficient liquid phase formation. Too short a time results in insufficient liquid phase and inadequate strength; too long a time leads to grain coarsening, decreased porosity, and reduced reduction reaction activity.

[0045] In some embodiments, heat equalization includes: a heat equalization temperature of 990°C to 1010°C and a heat equalization time of 4 min to 6 min.

[0046] Specifically, a homogenization stage temperature of 990℃~1010℃ and a time of 4min~6min can facilitate the crystallization and precipitation of the liquid phase and eliminate thermal stress. Too low a temperature or insufficient time will lead to uneven density inside and outside the pellets, while too high a temperature or too long a time will result in a lower thermal stress release effect within the pellets, causing embrittlement.

[0047] In some embodiments, the key indicators of nickel-chromium oxide pellets are: Ni ≥ 0.8 wt%, Cr2O3 content 3 wt%~6 wt%, compressive strength > 2000 N / piece, drum index ≥ 95%, reducibility index ≥ 75%, and porosity of about 25%.

[0048] In a second aspect, the present invention provides an application of nickel-chromium oxide pellets, wherein the nickel-chromium oxide pellets prepared by the above method are used as raw materials for hydrogen-based vertical shaft furnace-electric furnace smelting of stainless steel.

[0049] Specifically, the nickel-chromium oxide pellets prepared by the above method have a nickel content of more than 0.8 wt% and a compressive strength of more than 2000 N / piece. The chromium-nickel iron ore pre-reduced pellets obtained by hydrogen-based shaft furnace reduction verification fully meet the smelting requirements of hydrogen-based shaft furnace-electric furnace and can be used as raw material for hydrogen-based shaft furnace-electric furnace for stainless steel smelting.

[0050] The present invention will be further described in detail below with reference to specific embodiments and comparative examples.

[0051] The proportions of each component in laterite nickel ore and stainless steel slag in Example 1 and Comparative Examples 1-8 are shown in Table 1 below.

[0052] Table 1. Component mass ratio (%)

[0053]

[0054] Example 1

[0055] A method for synergistically preparing nickel-chromium oxide pellets using laterite nickel ore and stainless steel slag includes the following steps:

[0056] (1) Pretreatment of laterite nickel ore and stainless steel slag: Dry the laterite nickel ore and stainless steel slag to a moisture content of less than 10% (by weight), crush the laterite nickel ore and stainless steel slag to less than 3mm using a double roll crusher, and then classify the laterite nickel ore and stainless steel slag into -0.074mm (88%) after high pressure roller milling (D50≈0.065mm).

[0057] (2) Batching: The pretreated laterite nickel ore and stainless steel slag are mixed. The ore mixing ratio (weight ratio) is laterite nickel ore: stainless steel slag = 80:20 to obtain the mixture.

[0058] (3) Pelletizing: The mixture is pelletized using a disc pelletizer. The pelletizing moisture content is fixed at 20%, and the pelletizing time is 35 minutes to obtain green pellets. The green pellets have a drop strength greater than 20 times / 0.5m, a compressive strength of 21.7N / pellet, and a bursting temperature greater than 470℃.

[0059] (4) Oxidative Calcination: The dried green pellets were oxidized and calcined in a muffle furnace to obtain nickel-chromium oxide pellets. The preheating temperature was 950℃ for 15 min; the calcination temperature was 1275℃ for 15 min; and the homogenization temperature was 1000℃ for 5 min. The microstructure and structure of the obtained nickel-chromium oxide pellets are as follows: Figure 1 As shown in Table 2, the performance indicators are shown in Table 3. The obtained nickel-chromium oxide pellets were used for hydrogen-based vertical shaft furnace reduction.

[0060] Comparative Example 1

[0061] The difference between Comparative Example 1 and Example 1 is that in step (1): laterite nickel ore and stainless steel slag are graded by high-pressure roller milling to a density of -0.044mm (90%) (D50≈0.03mm). The performance indicators of the obtained nickel-chromium oxide pellets are shown in Table 2.

[0062] Comparative Example 2

[0063] The difference between Comparative Example 2 and Example 1 is that in step (1), laterite nickel ore and stainless steel slag are graded by high-pressure roller milling to obtain a fraction of -0.104 mm (85%). The performance indicators of the obtained nickel-chromium oxide pellets are shown in Table 2.

[0064] Comparative Example 3

[0065] The difference between Comparative Example 3 and Example 1 lies in step (2): the pretreated laterite nickel ore is mixed with a binder at a weight ratio of 99:1 to obtain a single-ore mixture. The performance indicators of the obtained nickel-chromium oxide pellets are shown in Table 2.

[0066] Comparative Example 4

[0067] The difference between Comparative Example 4 and Example 1 lies in step (2): the pretreated stainless steel slag is mixed with a binder at a weight ratio of 99:1 to obtain a single-ore mixture. The performance indicators of the obtained nickel-chromium oxide pellets are shown in Table 2.

[0068] Comparative Example 5

[0069] The difference between Comparative Example 5 and Example 1 lies in step (2): the pretreated laterite nickel ore is mixed with stainless steel slag, and the ore ratio (i.e., weight ratio) is laterite nickel ore: stainless steel slag = 90:10 to obtain a mixture. The performance indicators of the obtained nickel-chromium oxide pellets are shown in Table 2.

[0070] Comparative Example 6

[0071] The difference between Comparative Example 6 and Example 1 lies in step (2): the pretreated laterite nickel ore is mixed with stainless steel slag at a ratio (i.e., weight ratio) of 70:30 to obtain a mixture. The performance indicators of the obtained nickel-chromium oxide pellets are shown in Table 2.

[0072] Comparative Example 7

[0073] The difference between Comparative Example 7 and Example 1 is that in step (4), the calcination temperature is 1250℃. The performance indicators of the obtained nickel-chromium oxide pellets are shown in Table 2.

[0074] Comparative Example 8

[0075] The difference between Comparative Example 8 and Example 1 is that in step (4), the calcination temperature is 1300℃. The performance indicators of the obtained nickel-chromium oxide pellets are shown in Table 2.

[0076] Table 2 Performance indicators of oxidized pellets from Example 1 and Comparative Examples 1-8

[0077]

[0078] Table 3 Metallurgical properties of nickel-chromium oxide pellets

[0079]

[0080] Results Discussion

[0081] In Example 1 of this invention, laterite nickel ore pelletizing was achieved by adding stainless steel slag. When the weight ratio of laterite nickel ore to stainless steel slag was 80:20, the compressive strength of the prepared nickel-chromium oxide pellets was above 2000 N / pellet, meeting the requirements of electric furnace production for raw material strength. The compressive strength of the pellets was approximately twice that of pelletizing laterite nickel ore alone. The obtained nickel-chromium oxide pellets were reduced in a hydrogen-based vertical shaft furnace, and reduction and low-temperature pulverization experiments were conducted at 900°C under reducing gas conditions (Table 3). The results showed that the obtained chromium-nickel iron ore pre-reduced pellets can be used as raw materials for smelting stainless steel, replacing some ferrochrome and ferronickel alloys, thereby saving energy consumption and reducing production costs in stainless steel production. As shown in Table 2, when the ratio of laterite nickel ore to stainless steel slag was 80:20, the pellets exhibited good pelletizing properties, and the roasting strength and reducibility reached their optimal levels, indicating that the appropriate addition of stainless steel slag can effectively improve the structure and performance. Figure 1The results indicate that the pellet cross-section exhibits a gradient structure: dense on the outside and porous on the inside. The outer edge first undergoes liquefaction and sealing, while volatiles are retained internally, forming numerous circular closed pores. At high magnification, the dark gray continuous phase at point 1 is a Ca-Mg silicate liquid phase / glass (diopside); the bright gray and other crystals at point 2 are a (Fe-Mg) spinel framework. This is consistent with the EDS results: point 1 is rich in Ca, Mg, and Si, but low in Fe. Point 2 is rich in Fe and Mg; thus, the "spinel framework + diopside liquid phase bonding" is beneficial to strength.

[0082] Comparative Examples 1 and 2 show that Comparative Example 1 has excessively fine particles (D50≈0.03mm), resulting in insufficient liquid phase formation, weak calcination bonding, and decreased strength; Comparative Example 2 has excessively coarse particles (D50≈0.09mm), resulting in poor pelletization and low density. This indicates that a moderate particle size (D50≈0.065mm) is most conducive to obtaining high-strength oxidized pellets.

[0083] Comparative Examples 3 and 4 show that pelletizing with either laterite nickel ore or stainless steel slag alone results in significantly inferior pelletizing performance and compressive strength compared to pelletizing with the composite ratio, indicating that the synergistic effect of the two has a significant effect on pelletizing and roasting strengthening.

[0084] Comparative Examples 5 and 6 show that when the proportion of stainless steel slag is too low (10%) or too high (30%), the performance of the pellets decreases, indicating that the optimal ratio is 80:20, which can balance alkalinity adjustment and liquid phase formation.

[0085] Comparative Examples 7 and 8 show that when the calcination temperature is below 1265℃, the liquid phase is insufficient and the strength is low; when the temperature is above 1285℃, pellet aggregation occurs and the porosity decreases. The optimal calcination temperature range is 1265℃~1285℃.

[0086] It will be readily understood by those skilled in the art that the above-described advantageous methods can be freely combined and superimposed without conflict. The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A method for preparing nickel and chromium-containing oxidized pellets by synergistically using laterite nickel ore and stainless steel slag, characterized in that, The application relates to a method for preparing nickel-chromium oxide pellets. Raw material pretreatment: dry laterite nickel ore and dry stainless steel slag are respectively crushed and then ground to obtain laterite nickel ore powder and stainless steel slag powder; wherein the particle size of the laterite nickel ore powder meets the requirement of more than 60% of -0.074 mm, and D50 is 0.06 mm-0.07 mm; the particle size of the stainless steel slag powder meets the requirement of more than 60% of -0.074 mm, and D50 is 0.06 mm-0.07 mm; Pelletizing: the laterite nickel ore powder and the stainless steel slag powder are mixed and then formed into pellets to obtain green pellets; wherein the mass ratio of the laterite nickel ore powder to the stainless steel slag powder is (75-85):20; Oxidation roasting: the green pellets are subjected to preheating, roasting and soaking treatment to obtain the nickel-chromium oxide pellets; wherein the roasting temperature is 1265 DEG C-1285 DEG C; the nickel-chromium oxide pellets have a nickel content of not less than 0.8 wt%, a Cr2O3 content of 3 wt%-6 wt%, a compressive strength of greater than 2000 N, and meet the smelting requirements of a hydrogen-based shaft furnace.

2. The method for preparing nickel and chromium-containing oxidized pellets in cooperation with laterite nickel ore and stainless steel slag according to claim 1, characterized in that, In the laterite nickel ore, the mass fraction of iron is 40%-50%, the mass fraction of nickel is 0.7%-1.5%, the mass fraction of Cr2O3 is 3%-6%, the mass fraction of SiO2 is 4%-8%, the mass fraction of MgO is 2%-4%, and the mass fraction of Al2O3 is 3%-7%.

3. The method for preparing nickel and chromium-containing oxidized pellets in cooperation with laterite nickel ore and stainless steel slag according to claim 1, characterized in that, In the stainless steel slag, the mass fraction of Cr2O3 is 3%-6%, the mass fraction of CaO is 45%-60%, the mass fraction of SiO2 is 25%-35%, the mass fraction of MgO is 3%-6%, the mass fraction of Al2O3 is 1%-3%, and the basicity CaO / SiO2 is between 1.7 and 2.

0.

4. The method for preparing nickel and chromium-containing oxidized pellets in cooperation with laterite nickel ore and stainless steel slag according to claim 1, characterized in that, The laterite nickel ore and the stainless steel slag are dried, and the method comprises the following steps: The moisture content of the dried laterite nickel ore is controlled to be less than 10 wt%, and the moisture content of the dried stainless steel slag is controlled to be less than 10 wt%.

5. The method for preparing nickel and chromium-containing oxidized pellets in cooperation with laterite nickel ore and stainless steel slag according to claim 1, characterized in that, The pelletizing comprises the following steps: pelletizing is performed by using a disc pelletizer, the moisture content of the green pellets is controlled to be 20 wt%-24 wt%, and the particle size of the green pellets is controlled to be 14 mm-16 mm.

6. The method for preparing nickel and chromium-containing oxidized pellets in cooperation with laterite nickel ore and stainless steel slag according to claim 1, characterized in that, The preheating comprises the following steps: the preheating temperature is 940 DEG C-960 DEG C, and the preheating time is 10 min-20 min.

7. The method for preparing nickel and chromium-containing oxidized pellets in cooperation with laterite nickel ore and stainless steel slag according to claim 1, characterized in that, The roasting time is 10 min-20 min.

8. The method for preparing nickel and chromium-containing oxidized pellets in cooperation with laterite nickel ore and stainless steel slag according to claim 1, characterized in that, The soaking comprises the following steps: the soaking temperature is 990 DEG C-1010 DEG C, and the soaking time is 4 min-6 min.

9. Use of nickel-containing chromium oxide pellets, characterized in that The nickel-chromium oxide pellets prepared by using the method according to any one of claims 1-8 are used as hydrogen-based shaft furnace-electric furnace charges for stainless steel smelting.

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