A low-temperature pre-dewatering and sectional roasting method for improving the strength of limonite type laterite nickel ore pellets

Abstract

The present application relates to the technical field of iron ore pellet production, and particularly relates to a low-temperature pre-dehydration segmented roasting method for improving the strength of limonite-type laterite nickel ore pellets. The method comprises the following steps: mixing limonite-type laterite nickel ore with bentonite to obtain green pellets; sequentially drying, low-temperature pre-dehydrating, oxidizing preheating and high-temperature roasting the green pellets to obtain finished pellets. The low-temperature pre-dehydration stage is arranged before the conventional high-temperature preheating, the process of goethite decomposition and crystallization water release is regulated, the crystallization water gradually escapes from the inside of the pellets, and the coarse pores and connected cracks caused by rapid dehydration are reduced; then, the recrystallization of hematite and the connection between particles are promoted through oxidizing preheating and high-temperature roasting, and the internal organization density of the pellets is improved. Through regulating the dehydration process of the initial stage of the limonite-type laterite nickel ore pellet roasting, the present application significantly improves the compressive strength of the finished pellets, and the coarse and connected pores in the pellets are obviously reduced, and the connection degree of Fe-rich particles is improved.

Description

Technical Field

[0001] This invention relates to the field of iron ore pellet production technology, and in particular to a low-temperature pre-dehydration staged roasting method for improving the strength of limonite-type laterite nickel ore pellets. Background Technology

[0002] As the steel industry develops towards higher efficiency and greener practices, iron ore pellets, with their uniform particle size, good mechanical strength, and excellent metallurgical properties, have become an important raw material in blast furnace ironmaking. With the increasing proportion of iron ore pellets in blast furnace burdens, it is of great significance to utilize different types of iron ore resources to produce high-performance oxide pellets.

[0003] Lateritic nickel ore of the limonite type is an important iron-nickel symbiotic mineral resource, in which the iron minerals mainly exist in the form of hydrous iron oxides such as goethite. Compared with ordinary magnetite concentrate or hematite concentrate, this type of ore usually has a higher loss on ignition. During the heating process of pellets, goethite undergoes a dehydroxylation reaction and transforms into hematite, while releasing a large amount of water of crystallization.

[0004] In traditional pellet roasting, dried pellets are typically placed directly into a high-temperature preheating zone. For lateritic nickel ore with a high goethite content, a large amount of water of crystallization is easily released rapidly when the pellets are heated quickly. If the water vapor generated inside the pellets cannot diffuse outwards in time, it can easily cause the existing pores to expand and interconnect, and even form cracks, damaging the integrity of the internal structure of the pellets.

[0005] Meanwhile, the coarse pores and interconnected fissures formed in the early stages of roasting also affect the subsequent recrystallization of hematite particles and the bonding between particles, making the internal structure of the pellets relatively loose and ultimately reducing the compressive strength of the finished pellets. Existing methods for strengthening laterite-type nickel ore pellets mainly focus on increasing roasting temperature, extending roasting time, adjusting raw material alkalinity, optimizing binder addition, and changing the ore blending regime. These methods primarily target the high-temperature consolidation process of the pellets, while paying less attention to the structural damage caused by the rapid dehydration of goethite in the early stages of roasting in laterite-type nickel ore. The removal of goethite crystal water alters the initial pore structure of the pellets and further affects subsequent oxidation and interparticle consolidation.

[0006] Therefore, how to regulate the release of crystal water from goethite before the pellets enter the high-temperature preheating and roasting stage, reduce the coarse pores and structural defects caused by rapid dehydration, and create favorable conditions for subsequent recrystallization and particle consolidation of hematite, is a technical problem that needs to be solved to improve the strength of laterite-type nickel ore pellets. Summary of the Invention

[0007] To address the problem that excessively rapid dehydration of goethite during the pellet roasting process of limonite-type lateritic nickel ore pellets easily leads to the formation of coarse pores and interconnected fractures, which in turn affects subsequent pellet consolidation and results in low compressive strength, this invention provides a low-temperature pre-dehydration staged roasting method to improve the strength of limonite-type lateritic nickel ore pellets. This method adds a low-temperature pre-dehydration process before the conventional preheating stage, regulating the decomposition of goethite and the release of crystal water, improving the pore structure of the pellets in the early stages of roasting, creating favorable conditions for subsequent oxidation consolidation and high-temperature recrystallization, thereby increasing the compressive strength of limonite-type lateritic nickel ore pellets.

[0008] To achieve the above objectives, the present invention provides the following solution: One of the technical solutions of this invention is a low-temperature pre-dehydration staged roasting method for improving the strength of laterite-type nickel ore pellets, comprising the following steps: Raw pellets are obtained by mixing limonite-type laterite nickel ore with bentonite and then pelletizing the mixture. The green pellets are dried to obtain dried pellets; The dry pellets were subjected to low-temperature pre-dehydration, oxidation preheating, and high-temperature roasting in sequence to obtain limonite-type laterite nickel ore pellets.

[0009] The TG-DTG-DSC simultaneous thermal analysis curves of limonite-type laterite nickel ore are as follows: Figure 1 As shown, simultaneous thermal analysis results indicate that the weight loss of limonite-type lateritic nickel ore is mainly concentrated between 220 and 300 °C, reaching a maximum weight loss rate near 273.2 °C. Simultaneously, a significant endothermic process occurs within the range of 219.54 to 299.63 °C, with a weight loss rate of 6.34% during this stage, primarily related to goethite decomposition and removal of crystal water. Based on these thermal decomposition characteristics, this invention sets the low-temperature pre-dehydration process within the main dehydration temperature range of goethite. By rationally controlling the temperature and processing time, crystal water gradually diffuses out from the interior of the pellets, reducing the damage to the pellet structure caused by concentrated dehydration.

[0010] Based on low-temperature pre-dehydration, further oxidation preheating is used to promote the transformation of iron oxides inside the pellets and the formation of the initial solidified structure. High-temperature roasting is used to strengthen the recrystallization of hematite particles and the connection between particles, so that the internal pores of the pellets gradually shrink and the structure becomes denser, ultimately obtaining limonite-type laterite nickel ore oxide pellets with significantly improved compressive strength.

[0011] In a preferred embodiment of the present invention, the temperature of the low-temperature pre-dehydration is 230-250 °C and the time is 30-50 min; more preferably, it is 240 °C and 50 min.

[0012] The second technical solution of the present invention is a limonite-type laterite nickel ore pellet prepared by the above-mentioned low-temperature pre-dehydration staged roasting method.

[0013] Compared with the prior art, the present invention has the following beneficial effects: This invention introduces a low-temperature pre-dehydration stage before conventional high-temperature preheating, which allows the goethite crystal water in limonite-type laterite nickel ore pellets to be released gradually, thereby reducing the formation of coarse pores and interconnected fractures caused by rapid dehydration.

[0014] Low-temperature pre-dehydration can improve the initial pore structure of the pellets before they enter high-temperature preheating, making the internal structure distribution of the pellets more uniform during the subsequent oxidation process, which is conducive to further contact and connection of hematite particles.

[0015] Through subsequent oxidation preheating and high-temperature calcination, a more continuous solidified structure is formed between Fe-rich particles, and the internal structure of the pellets becomes more compact, thereby improving the overall structural integrity and compressive strength of the pellets.

[0016] When the preferred segmented roasting process of the present invention is adopted, the compressive strength of the finished pellets increases from 853.7 N without low-temperature pre-dehydration treatment to 1259.3 N, an increase of 405.6 N, or about 47.5%, indicating that low-temperature pre-dehydration can significantly enhance the consolidation process of limonite-type laterite nickel ore pellets. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 The TG-DTG-DSC simultaneous thermal analysis curves of limonite-type laterite nickel ore used in the embodiments and comparative examples of this invention; Figure 2 This is a schematic diagram of the low-temperature pre-dehydration staged roasting process of the present invention; wherein, (a) is a schematic diagram of the preparation, staged roasting and characterization process of limonite-type laterite nickel ore pellets, and (b) is a schematic diagram of the temperature regime for low-temperature pre-dehydration, oxidation preheating and high-temperature roasting. Figure 3 Optical microstructure of the pellet cross-sections obtained in Comparative Example 1 and Example 1; wherein, A, A1~A3 are the overall cross-sections of the pellets obtained in Comparative Example 1, and the corresponding outer, middle and core parts of the pellets; B, B1~B3 are the overall cross-sections of the pellets obtained in Example 1, and the corresponding outer, middle and core parts of the pellets; Figure 4 The results of SEM-EDS analysis of the pellets obtained in Comparative Example 1 and Example 1 are shown; where (a) is the pellet obtained in Comparative Example 1 and (b) is the pellet obtained in Example 1. Detailed Implementation

[0019] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0020] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0021] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0022] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0023] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0024] The first aspect of this invention provides a low-temperature pre-dehydration staged roasting method for improving the strength of laterite-type nickel ore pellets, comprising the following steps: Raw pellets are obtained by mixing limonite-type laterite nickel ore with bentonite and then pelletizing the mixture. The green pellets are dried to obtain dried pellets; The dry pellets were subjected to low-temperature pre-dehydration, oxidation preheating, and high-temperature roasting in sequence to obtain limonite-type laterite nickel ore pellets.

[0025] In a preferred embodiment of the present invention, the amount of bentonite added is 1% to 3% of the mass of the limonite-type laterite nickel ore.

[0026] In a preferred embodiment of the present invention, before mixing the limonite-type lateritic nickel ore with bentonite, the step of processing the limonite-type lateritic nickel ore is further included, specifically: drying and grinding the limonite-type lateritic nickel ore so that the mass proportion of particles smaller than 0.074 mm is not less than 85%.

[0027] In a preferred embodiment of the present invention, the particle size of the green pellets is 8 mm to 16 mm.

[0028] In a preferred embodiment of the present invention, the drying conditions for the green pellets are set as follows: drying at 90 ℃~120 ℃ for 3 h.

[0029] In a preferred embodiment of the present invention, the low-temperature pre-dehydration temperature is 230–250 °C and the time is 30–50 min; more preferably, it is 240 °C and 50 min. Under these conditions, the water of crystallization in goethite can be released relatively slowly, which is beneficial to reducing the formation of large pores and interconnected fractures inside the pellets.

[0030] In this invention, the function of low-temperature pre-dehydration is to gradually decompose the goethite in limonite-type laterite nickel ore and remove its water of crystallization.

[0031] In a preferred embodiment of the present invention, the oxidation preheating temperature is 800 ℃~1000 ℃ and the time is 10 min~30 min; preferably 1000 ℃ and 25 min.

[0032] In a preferred embodiment of the present invention, the high-temperature calcination temperature is 1190 ℃~1280 ℃ and the time is 10 min~30 min; preferably, it is calcined at 1280 ℃ for 30 min.

[0033] In a preferred embodiment of the present invention, the high-temperature calcination is further followed by a step of cooling to room temperature in an oxidizing atmosphere.

[0034] The process of this invention is simple and does not require the addition of complex reinforcing agents, which can effectively improve the consolidation performance of high burn-off limonite-type laterite nickel ore pellets.

[0035] The second aspect of the present invention provides a limonite-type laterite nickel ore pellet prepared by the above-described low-temperature pre-dehydration staged roasting method.

[0036] Unless otherwise specified, the technical solutions described in this invention are all conventional solutions in the field, and the reagents or raw materials used are all purchased from commercial channels or are publicly available unless otherwise specified.

[0037] In the following examples and comparative examples, both limonite-type lateritic nickel ore and bentonite were used as raw materials for pellet preparation. The contents of TFe, FeO, SiO2, CaO, MgO, Al2O3, Ni, and Cr2O3 in the limonite-type lateritic nickel ore were 48.35%, 0.54%, 3.25%, 0.036%, 2.10%, 6.90%, 0.70%, and 5.21%, respectively, with a loss on ignition of 11.72%. Before mixing the limonite-type lateritic nickel ore and bentonite, the limonite-type lateritic nickel ore was pre-treated: after drying to constant weight at 105 °C, it was finely ground, resulting in a particle size fraction of 90.49% smaller than 0.074 mm after grinding.

[0038] The treated limonite-type lateritic nickel ore was mixed with bentonite, with the bentonite addition amount being 2% of the mass of the limonite-type lateritic nickel ore. The mixture was fed into a disc pelletizer for pelletizing at a rotation speed of 20 r / min, a horizontal inclination angle of 45°, and a pelletizing time of 15 min. After pelletizing, green pellets with a particle size of 10–15 mm were screened and dried at 105 ℃ for 3 h to obtain dry pellets for subsequent roasting experiments.

[0039] The compressive strength of the pellets obtained under different conditions was determined according to ISO 4700. Each group of pellets was measured six times and the average value was taken. The calcined pellets were impregnated and cured with epoxy resin, and the cross-section of the pellets was ground and polished. The internal pores and mineral phase structure of the pellets were observed using an optical microscope, the particle connection state was observed using a scanning electron microscope, and the elemental distribution in different regions was analyzed using EDS. The percentage of pore area of ​​the pellet cross-section was determined using Image-Pro Plus 6.0 software.

[0040] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0041] Comparative Example 1 Lateritic nickel ore of limonite type was mixed evenly with bentonite (2% by mass of limonite type lateritic nickel ore) and then pelletized. Green pellets with a particle size of 10–15 mm were selected and dried at 105 °C for 3 h. The resulting dry pellets were not subjected to low-temperature pre-dehydration treatment, but were directly oxidized and preheated at 1000 °C for 25 min, and then calcined at 1280 °C for 30 min. After calcination, they were cooled to room temperature in air. The compressive strength of the resulting finished pellets was 853.7 N.

[0042] Compared with Example 1, the other raw material ratios, pelletizing, oxidation preheating, and high-temperature calcination conditions were the same, except that the low-temperature pre-dehydration stage of 240 °C for 50 min was not included. The compressive strength of the finished pellets decreased by 405.6 N. Microscopic observation of the pellet cross-section revealed a porosity of 28.28%, with numerous large pores and interconnected fissures within the pellets. These pores separated some Fe-rich regions, resulting in poor continuity between particles. SEM analysis showed that the Fe-rich particles were relatively dispersed, with distinct particle boundaries and insufficient contact between particles. EDS analysis indicated a certain degree of non-uniformity in the distribution of Fe, with localized enrichment of elements such as Mg, Cr, and Al (e.g., ...). Figure 3 and Figure 4 (As shown).

[0043] Because the dry pellets were not pre-dehydrated at low temperatures, they directly entered the 1000 ℃ oxidation preheating stage. During the rapid heating process, the goethite underwent concentrated decomposition, releasing a large amount of water of crystallization in a short period. This caused the original micropores inside the pellets to expand and interconnect, forming numerous coarse pores and local cracks. These structural defects reduced the effective contact area between Fe-rich particles, hindering subsequent recrystallization of hematite and interparticle bonding. Consequently, the resulting pellets had low compressive strength.

[0044] Comparative Example 2 Lateritic nickel ore of limonite type was mixed with bentonite (2% by mass of limonite type lateritic nickel ore) to form pellets. Green pellets with a particle size of 10–15 mm were selected and dried at 105 °C for 3 h. The resulting dry pellets were first subjected to low-temperature pre-dehydration at 220 °C for 10 min, then oxidative preheating at 1000 °C for 25 min, and finally calcined at 1280 °C for 30 min. After calcination, the pellets were cooled to room temperature in air. The compressive strength of the resulting finished pellets was 956.8 N.

[0045] Compared to Example 1, the raw material ratio, pelletizing, oxidation preheating, and high-temperature roasting conditions were the same, but the low-temperature pre-dehydration temperature was reduced by 20 °C, and the processing time was shortened by 40 min. Since 220 °C is on the low-temperature side of the main decomposition temperature range of goethite, and the processing time is relatively short, the degree of goethite decomposition and removal of crystal water in the pellets is limited. When the pellets enter the subsequent high-temperature preheating stage, residual crystal water will still be released rapidly; therefore, the improvement effect on the pore structure of the pellets is lower than that under the condition of "low-temperature pre-dehydration 240 °C, 50 min".

[0046] Comparative Example 3 Lateritic nickel ore of limonite type was mixed with bentonite (2% by mass of limonite type lateritic nickel ore) to form pellets. Green pellets with a particle size of 10–15 mm were selected and dried at 105 °C for 3 h. The resulting dry pellets were first subjected to low-temperature pre-dehydration at 300 °C for 50 min, then oxidative preheating at 1000 °C for 25 min, and finally calcined at 1280 °C for 30 min. After calcination, the pellets were cooled to room temperature in air. The compressive strength of the resulting finished pellets was 928.4 N.

[0047] Compared to Example 1, the other raw material ratios and roasting conditions remained the same, except that the low-temperature pre-dehydration temperature was increased from 240 °C to 300 °C. At 300 °C, the decomposition of goethite and the release rate of crystal water were significantly accelerated. Prolonged heat preservation would intensify the concentrated escape process of crystal water, causing some micropores to further expand and connect, increasing the possibility of coarse pores and local structural defects, which is not conducive to the subsequent continuous consolidation between particles.

[0048] Example 1 Lateritic nickel ore of limonite type was mixed evenly with bentonite at 2% of the ore mass, and pelletized in a disc pelletizer for 15 min. Green pellets with a particle size of 10–15 mm were selected and dried at 105 °C for 3 h. The resulting dried pellets were first pre-dehydrated at 240 °C for 50 min, then preheated by oxidation at 1000 °C for 25 min, and finally calcined at 1280 °C for 30 min. After calcination, the pellets were cooled to room temperature in air. The compressive strength of the resulting finished pellets was 1259.3 N.

[0049] Compared with Comparative Example 1, the other raw material ratios, pelletizing, oxidation preheating, and high-temperature roasting conditions were the same. The only addition was a low-temperature pre-dehydration stage at 240 ℃ for 50 min. The compressive strength of the pellets increased from 853.7 N to 1259.3 N, an increase of 405.6 N, or 47.51%. Because the water of crystallization in goethite can be released relatively gradually at 240 ℃, water vapor can gradually diffuse outward along the pores between particles, reducing the pore expansion and structural damage caused by the concentrated release of water of crystallization. This provides better initial structural conditions for subsequent oxidation preheating and high-temperature consolidation.

[0050] Microscopic analysis of the obtained pellet cross-section revealed a porosity of 11.22%, a decrease of 17.06 percentage points compared to Comparative Example 1. The number of large, interconnected pores within the pellets was significantly reduced, with pores primarily existing as smaller, more uniformly distributed isolated micropores. The continuity of the Fe-rich region was significantly improved. SEM analysis showed that the Fe-rich particles were more densely packed, with increased contact areas between particles forming a more continuous interconnected structure. EDS analysis indicated a more uniform distribution of Fe, and a reduced degree of local enrichment of elements such as Mg, Cr, and Al (e.g., ...). Figure 3 and Figure 4 (As shown).

[0051] Example 2 Lateritic nickel ore of limonite type was mixed evenly with bentonite (2% by mass of limonite type lateritic nickel ore) and pelletized. Green pellets with a particle size of 10–15 mm were selected and dried at 105 °C for 3 h. The resulting dry pellets were first pre-dehydrated at 230 °C for 50 min, then preheated by oxidation at 1000 °C for 25 min, and finally calcined at 1280 °C for 30 min. After calcination, the pellets were cooled to room temperature in air. The compressive strength of the resulting finished pellets was 1198.6 N.

[0052] At 230 ℃, goethite has entered the main dehydration temperature range. By extending the treatment time, the crystal water can be gradually released from the inside of the pellets, reducing the degree of concentrated dehydration of the pellets during the subsequent rapid heating process. This is beneficial to improving the initial pore structure of the pellets and subsequent particle consolidation. Therefore, the strength of the obtained pellets is higher than that of pellets that have not undergone low-temperature pre-dehydration treatment.

[0053] Example 3 Lateritic nickel ore of limonite type was mixed with bentonite (2% by mass of limonite type lateritic nickel ore) to form pellets. Green pellets with a particle size of 10–15 mm were selected and dried at 105 °C for 3 h. The resulting dry pellets were first subjected to low-temperature pre-dehydration at 250 °C for 40 min, then oxidative preheating at 1000 °C for 25 min, and finally high-temperature calcination at 1280 °C for 30 min. After calcination, the pellets were cooled to room temperature in air. The compressive strength of the resulting finished pellets was 1174.2 N.

[0054] At 250 ℃, the degree of decomposition of goethite is improved. By appropriately shortening the holding time, the rapid release of crystal water can be avoided, so that the pellets can retain a relatively complete initial pore structure while removing more crystal water. Therefore, it can improve the subsequent recrystallization and bonding conditions of hematite particles. The compressive strength of the finished pellets is higher than that of pellets that have not undergone low-temperature pre-dehydration treatment.

[0055] Example 4 Lateritic nickel ore of limonite type was mixed with bentonite (2% by mass of limonite type lateritic nickel ore) to form pellets. Green pellets with a particle size of 10–15 mm were selected and dried at 105 °C for 3 h. The resulting dry pellets were first pre-dehydrated at 240 °C for 40 min, then preheated by oxidation at 950 °C for 30 min, and finally calcined at 1270 °C for 30 min. After calcination, the pellets were cooled to room temperature in air. The compressive strength of the resulting finished pellets was 1108.5 N.

[0056] After adjusting the oxidation preheating temperature, preheating time, and high-temperature roasting temperature, the low-temperature pre-dehydration stage can still release some of the crystal water inside the pellets in advance, reducing the structural damage caused by rapid dehydration during subsequent heating. This is beneficial for the formation of a more continuous connection structure between Fe-rich particles, indicating that the low-temperature pre-dehydration staged roasting method of the present invention can improve the consolidation performance of limonite-type laterite nickel ore pellets within a certain range of process parameters.

[0057] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A low-temperature pre-dehydration staged roasting method for improving the strength of laterite-type nickel ore pellets, characterized in that, Includes the following steps: Raw pellets are obtained by mixing limonite-type laterite nickel ore with bentonite and then pelletizing the mixture. The green pellets are dried to obtain dried pellets; The dry pellets were subjected to low-temperature pre-dehydration, oxidation preheating, and high-temperature roasting in sequence to obtain limonite-type laterite nickel ore pellets.

2. The low-temperature pre-dehydration staged calcination method according to claim 1, characterized in that, The amount of bentonite added is 1% to 3% of the mass of the limonite-type laterite nickel ore.

3. The low-temperature pre-dehydration staged calcination method according to claim 1, characterized in that, Before mixing the limonite-type lateritic nickel ore with bentonite, the process includes a step of treating the limonite-type lateritic nickel ore, specifically by drying and grinding the limonite-type lateritic nickel ore so that the mass proportion of particles smaller than 0.074 mm is not less than 85%.

4. The low-temperature pre-dehydration staged calcination method according to claim 1, characterized in that, The particle size of the green pellets is 8 mm to 16 mm.

5. The low-temperature pre-dehydration staged calcination method according to claim 1, characterized in that, The drying conditions for the green pellets are set as follows: drying at 90 ℃~120 ℃ for 3 h.

6. The low-temperature pre-dehydration staged calcination method according to claim 1, characterized in that, The low-temperature pre-dehydration temperature is 230–250 °C and the time is 30–50 min.

7. The low-temperature pre-dehydration staged calcination method according to claim 1, characterized in that, The oxidation preheating temperature is 800 ℃~1000 ℃ and the time is 10 min~30 min.

8. The low-temperature pre-dehydration staged calcination method according to claim 1, characterized in that, The high-temperature roasting temperature is 1190 ℃~1280 ℃ and the time is 10 min~30 min.

9. The low-temperature pre-dehydration staged calcination method according to claim 1, characterized in that, The process after high-temperature roasting also includes a step of cooling to room temperature in an oxidizing atmosphere.

10. A limonite-type laterite nickel ore pellet prepared by the low-temperature pre-dehydration staged roasting method according to any one of claims 1 to 9.

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