Preparation method of oxidized pellets for laterite-nickel ore hydrogen-based shaft furnace based on liquid phase regulation and control

Abstract

The invention discloses a preparation method of oxidized pellets for a laterite-nickel ore hydrogen-based shaft furnace based on liquid phase regulation and control, which comprises the following steps: S1, pretreatment: drying laterite-nickel ore, and carrying out crushing and high-pressure roller grinding pretreatment to obtain pretreated laterite-nickel ore; s2, uniform mixing: uniformly mixing the pretreated laterite-nickel ore and a composite additive to obtain a mixture; s3, pelletizing is conducted, specifically, the mixture is pelletized, and green pellets are prepared; and S4, oxidizing roasting is conducted, specifically, the green pellets are dried, preheated and roasted, and the high-strength and high-reducibility oxidized pellets are prepared. An efficient composite additive is developed on the basis of a molecular design theory, the composite additive has multiple active components, firstly, a molecular intercalation technology is utilized, middle-molecular organic binder pregelatinized starch is inserted into the middle of layered bentonite, and the binder performance of the bentonite is improved; then the modified bentonite is subjected to fiberization treatment through a high-pressure roller mill, selective dissociation and coarse crushing are generated under the fiberization treatment through the high-pressure roller mill, the layered structure characteristic of the bentonite is kept, and the purposes of strengthening organic composite modification and improving the performance of the organic composite bentonite are achieved. And through preparation of the efficient binder, the balling performance of the laterite-nickel ore is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of pellet preparation, and in particular to a method for preparing oxide pellets for hydrogen-based vertical shaft furnaces of laterite nickel ore based on liquid phase control. Background Technology

[0002] In recent years, with the rapid development of my country's national economy, the improvement of high-end manufacturing levels, and the upgrading of national consumption, the demand for stainless steel has been increasing, promoting the rapid development of my country's stainless steel industry. Currently, my country is the largest consumer and producer of stainless steel. Nickel is the main alloying element in stainless steel and one of the most important elements. However, my country faces a severe shortage of nickel ore resources and a high dependence on imports. With the increasing depletion of sulfide nickel ore resources, the global nickel industry has shifted its focus to laterite nickel ore for resource development. Currently, Japan and Europe control most of the high-grade laterite nickel ore resources that can be processed using mature technologies, while low-grade laterite nickel ore, which accounts for more than 50% of total nickel reserves, lacks mature technologies for economical and effective utilization. Therefore, developing innovative processes to efficiently utilize inexpensive and abundant low-grade laterite nickel ore to produce stainless steel mother liquor is of great significance for reducing stainless steel production costs and ensuring the high-quality and sustainable development of my country's stainless steel industry.

[0003] Pyrometallurgical smelting is the primary method for processing laterite nickel ore. Currently, pyrometallurgical technologies mainly include the sintering-blast furnace method, the direct reduction-magnetic separation method, and the rotary kiln-electric arc furnace (RKEF) method. All three processes can effectively process low-grade laterite nickel ore, but they are suitable for different types of ore. Firstly, the sintering-blast furnace method is suitable for limonite-type laterite nickel ore, the direct reduction-magnetic separation method is suitable for transitional laterite nickel ore, and the rotary kiln-electric arc furnace (RKEF) method is suitable for humus-type laterite nickel ore. Furthermore, all three technologies currently require coal as a reducing agent, resulting in high energy consumption and significant carbon emissions. Statistics show that producing one ton of nickel ferroalloy emits as much as 10.0 to 15.0 tons of CO2, accounting for more than 60% of the total CO2 emissions from the entire stainless steel production process. This undoubtedly severely restricts the achievement of carbon reduction targets in the stainless steel industry and even the steel industry as a whole.

[0004] Hydrogen-based reduction technology uses hydrogen as a reducing agent, which can significantly improve production efficiency while reducing carbon emissions, making it one of the important means for the steel industry to achieve green transformation. If hydrogen is used instead of coal as a reducing agent in the laterite nickel ore smelting process, it is expected to significantly reduce energy consumption and carbon emissions. Currently, although there has been much research on the preparation of oxide pellets for hydrogen-based shaft furnaces of ordinary iron ore, the preparation process for oxide pellets of laterite nickel ore with high burn-off and high silicon and magnesium content is still lacking, which seriously limits the progress of low-carbon smelting technology for laterite nickel ore. To this end, this patent develops a method for preparing oxide pellets for hydrogen-based shaft furnaces of laterite nickel ore based on liquid phase control. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing hydrogen-based oxide pellets for laterite nickel ore vertical shaft furnaces based on liquid phase regulation. The purpose is to cleanly and efficiently utilize difficult-to-process laterite nickel ore to prepare high-strength, highly reducing oxide pellets, providing high-quality furnace feed for stainless steel production.

[0006] To achieve the above objectives, the present invention provides a method for preparing hydrogen-based oxide pellets for laterite nickel ore shaft furnaces based on liquid phase regulation, comprising the following steps:

[0007] S1. Pretreatment: After drying, the laterite nickel ore is pretreated by crushing and high-pressure roller milling to obtain pretreated laterite nickel ore;

[0008] S2. Mixing: Mix the pretreated laterite nickel ore and composite additives obtained in step S1 to obtain a mixture.

[0009] S3. Pelletizing: Pelletize the mixture obtained in step S2 to prepare green pellets;

[0010] S4. Oxidative calcination: The green pellets obtained in step S3 are dried, preheated and calcined to prepare high-strength, high-reducing oxidized pellets.

[0011] The laterite nickel ore includes one or more of the following: limonite-type laterite nickel ore, transitional laterite nickel ore, and humus-type laterite nickel ore, containing 15% to 50% iron and 0.7% to 2.5% nickel.

[0012] Specifically, step S1 involves: drying the laterite nickel ore in a drying kiln until the moisture content is less than 2%, crushing it to a density of over 80% for -3mm using a jaw crusher, then crushing it to -1mm using a double roller crusher; finally, further crushing it using a high-pressure roller mill to achieve a density of 60-70% for -0.074mm and 30-45% for -0.045mm; the pressure of the high-pressure roller mill is 1.0-4.0 N / mm. 2 The scrap recycling rate is 20%~50%.

[0013] In step S2, a composite additive is added to the pretreated laterite nickel ore in step S1, with a proportion of 5% to 15% of the laterite nickel ore. The main components of the additive are 50% to 70% calcium-based flux, 10% to 15% carbonaceous material, 10% to 15% pregelatinized starch, 15% to 25% bentonite, and 5% to 10% nickel-iron smelting slag. The calcium-based flux includes at least one of limestone, quicklime, or hydrated lime. The carbonaceous material includes at least one of coke powder, bituminous coal, anthracite, and semi-coke. The nickel-iron smelting slag is the smelting slag produced during the smelting process of nickel sulfide ore.

[0014] In step S2, the preparation method of the composite additive is as follows: all components of the composite additive are finely ground to a particle size of -0.074 mm (over 90%), and then bentonite is subjected to sodium treatment in a NaOH solution, followed by aging treatment by stacking for 24 hours to ensure sufficient sodium treatment effect; the NaOH solution concentration is 1 mol / L to 4 mol / L, and the sodium treatment time is 2 to 3 hours; after aging, the bentonite and pregelatinized starch are pretreated by fiberization through a high-pressure roller mill, and then mixed with calcium-based flux, carbonaceous materials, and nickel-iron smelting slag using a high-power mixer. The mixing time of the high-power mixer is 60 to 180 seconds, and the rotation speed is 1000 to 3000 r / min.

[0015] Specifically, step S2 involves mixing laterite nickel ore and composite additives with water in a high-powered mixer; the high-powered mixer has a mixing time of 60-120 seconds and a rotation speed of 1000-3000 r / min.

[0016] Specifically, step S3 involves adding the mixed material to a disc pelletizer for pelletizing. The pelletizing time is 8 min to 12 min, the moisture content of the raw pellets is 12% to 16%, and the particle size of the raw pellets is 16 mm to 20 mm.

[0017] Specifically, step S4 involves: preparing oxidized pellets using a belt calciner with a material layer height of 300-500 mm, a forced-air drying temperature of 200-300℃, a forced-air drying velocity of 1.0-1.5 m / s, and a forced-air drying time of 4-6 min; and an exhaust drying temperature of 200-300℃, an exhaust drying velocity of 1.0-1.5 m / s, and a drying time of 4-6 min.

[0018] The preheating temperature is 800℃~1100℃, the preheating air velocity is 2.2~2.6m / s, and the preheating time is 10min~15min;

[0019] The roasting temperature is 1200℃~1300℃, the roasting air velocity is 2.2~2.6m / s, and the roasting time is 10min~15min; the homogenization temperature is 800℃~1000℃, the homogenization air velocity is 2.0~2.2m / s, and the homogenization time is 3min~5min.

[0020] Using the above technology, oxide pellets for hydrogen-based vertical shaft furnaces were prepared with a compressive strength exceeding 1500 N / piece, a drum strength exceeding 90%, and an abrasion resistance index of less than 5%, as well as dynamic reduction pulverized RDI. +3.2 Greater than 90%, reduction expansion less than 10%.

[0021] The above-described solution of the present invention has the following beneficial effects:

[0022] (1) The present invention discloses a method for preparing hydrogen-based oxide pellets for laterite nickel ore shaft furnaces based on liquid phase regulation. The key is the development of a highly efficient composite additive based on molecular design theory. This composite additive has multiple active ingredients. First, using molecular intercalation technology, a medium-molecular-weight organic binder, pregelatinized starch, is inserted into the middle of layered bentonite to improve the binder properties of the bentonite. Then, the modified bentonite is subjected to high-pressure roller mill fiberization treatment, which produces selective dissociation and coarse crushing, maintaining the layered structure characteristics of the bentonite and achieving the purpose of strengthening the organic composite modification and improving the performance of the organic composite bentonite. Through the preparation of the highly efficient binder, the pelletizing performance of laterite nickel ore is effectively improved. In addition, due to the good hydrophilicity of laterite nickel ore, the pelletizing moisture is high, which, combined with its own large burn-off, results in a low green pellet bursting temperature. The pellet drying process is prone to generating a large number of cracks, causing a sharp decrease in pellet strength. To address this, the composite additive contains some hydrophobic carbonaceous materials. The carbon particles provide hydrophobic gaps inside the pellets, providing channels for the diffusion of water vapor during the pellet drying process. This prevents the formation of pellet cracks due to excessive water vapor pressure inside, thereby improving the strength of the green pellets.

[0023] (2) This invention provides a method for preparing hydrogen-based oxidized pellets for laterite nickel ore shaft furnaces based on liquid phase control. The invention provides a multifunctional composite additive that, in addition to improving the bursting temperature of green pellets, can also utilize the nickel-iron smelting slag and calcium-based flux to adjust the amount of liquid phase during pellet roasting, thereby improving the strength of the laterite nickel ore oxidized pellets. Because laterite nickel ore suffers significant burn-off, large cracks and pores are usually generated during high-temperature roasting, resulting in low pellet density and poor strength. Therefore, this composite additive utilizes calcium-based flux to control the basicity of the pellets. Simultaneously, it leverages the high FeO content and low melting point of the nickel-iron smelting slag, through a clever combination of the two, to generate a calcium-iron olivine-like liquid phase during roasting, which fills the pores and repairs cracks, achieving self-healing of the damaged structure during pellet roasting, thereby improving the strength of the roasted pellets. At the same time, it also achieves efficient utilization of the difficult-to-treat nickel-iron slag. Attached Figure Description

[0024] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0025] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0026] The main components of the nickel-iron smelting slag used in this invention are as follows: Fe2O3 12.44%, FeO content 46.78%, SiO2 content 33.56%, MgO 1.01%, Al2O3 4.88%, and NiO 0.24%.

[0027] The present invention will be further described below with reference to specific embodiments and accompanying drawings.

[0028] Comparative Example 1:

[0029] Take, for example, a mixed laterite nickel ore, consisting of 50% of humus-type laterite nickel ore containing 22.12% iron and 1.45% nickel, and 50% of transitional laterite nickel ore containing 28.98% iron and 1.12% nickel;

[0030] S1. Pretreatment: The laterite nickel ore is dried in a drying kiln until the moisture content is less than 2%, then crushed to -3mm (82.5% purity) by a jaw crusher, and then crushed to -1mm by a double roller crusher. The crushed laterite nickel ore is then subjected to a high-pressure roller mill at a roller mill pressure of 1.5 N / mm. 2 With a scrap recycling rate of 30%, the material is further crushed to -1mm, of which -0.074mm accounts for 64.6% and -0.045mm accounts for 35.5%.

[0031] S2. Mixing: Mix the laterite nickel ore after roller milling with water using a high-power mixer for 120 seconds at a speed of 3000 r / min.

[0032] S3. Pelletizing: The pretreated mixture prepared in step S2 is pelletized to prepare green pellets. The pelletizing time is controlled at 10 min, the moisture content of the green pellets is 14%, and the particle size of the green pellets is 16 mm to 20 mm. The prepared green pellets have a drop strength of 12.3 times / (0.5 m), a compressive strength of 12.5 N / pellet, and a bursting temperature of only 200℃.

[0033] S4. Oxidative Calcination: The green pellets obtained in step S3 are loaded into a belt calciner for drying, preheating, and calcination, with the material layer height controlled at 300 mm. The temperature for exhaust drying of the green pellets is 200℃, the drying air velocity is 1.2 m / s, and the drying time is 4 min. The temperature for forced air drying is 200℃, the drying air velocity is 1.2 m / s, and the drying time is 4 min. The preheating temperature is 1100℃, the preheating air velocity is 2.4 m / s, and the preheating time is 15 min. The calcination temperature is 1300℃, the calcination air velocity is 2.2 m / s, and the calcination time is 15 min. The homogenization temperature is 900℃, the homogenization air velocity is 2.2 m / s, and the homogenization time is 4 min.

[0034] The oxidized pellets prepared by the above process have a compressive strength of only 826 N / piece, a drum strength of only 82.1%, an abrasion resistance index of 14.3%, and a dynamic reduction pulverization RDI. +3.2 It is only 62.5%, with a reduction expansion of 9.8%.

[0035] Example 1:

[0036] Taking a humus-type laterite nickel ore with 22.12% iron and 1.45% nickel as an example;

[0037] S1. Pretreatment: The laterite nickel ore is dried in a drying kiln until the moisture content is less than 2%, then crushed to -3mm (82.5% purity) by a jaw crusher, and then crushed to -1mm by a double roller crusher. The crushed laterite nickel ore is then subjected to a high-pressure roller mill at a roller mill pressure of 1.5 N / mm. 2 With a scrap recycling rate of 30%, the material is further crushed to -1mm, of which -0.074mm accounts for 64.6% and -0.045mm accounts for 35.5%.

[0038] S2. Mixing: The laterite nickel ore after roller milling is mixed with the composite additive using a high-pressure mixer. The composite additive ratio is 5%, the high-pressure mixing time is 120s, and the speed is 3000r / min. The main components of the composite binder are 50% limestone, 10% coke powder, 15% pregelatinized starch, 15% bentonite, and 10% nickel-iron smelting slag. The composite binder is prepared as follows: all components of the composite additive are finely ground to -0.074mm (92.5%). Then, the bentonite is sodium-treated in a 1.5mol / L NaOH solution for 2 hours and stored for 24 hours for maturation. After maturation, the bentonite and pregelatinized starch are pre-treated by fiberization through a high-pressure roller mill, and then mixed with limestone, coke powder, and nickel-iron smelting slag in a high-pressure mixer at 1500r / min for 60s.

[0039] S3. Pelletizing: The pretreated mixture prepared in step S2 is pelletized to prepare green pellets. The pelletizing time is controlled at 10 min, the moisture content of the green pellets is 14%, and the particle size of the green pellets is 16 mm to 20 mm. The prepared green pellets have a drop strength of 14.6 times / (0.5 m), a compressive strength of 15.8 N / pellet, and a bursting temperature of 310 °C.

[0040] S4. Oxidative Calcination: The green pellets obtained in step S3 are loaded into a belt calciner for drying, preheating, and calcination, with the material layer height controlled at 300 mm. The temperature for exhaust drying of the green pellets is 220℃, the drying velocity is 1.2 m / s, and the drying time is 4 min. The temperature for forced air drying is 250℃, the drying velocity is 1.2 m / s, and the drying time is 4 min. The preheating temperature is 1100℃, the preheating velocity is 2.4 m / s, and the preheating time is 15 min. The calcination temperature is 1300℃, the calcination velocity is 2.2 m / s, and the calcination time is 15 min. The homogenization temperature is 900℃, the homogenization velocity is 2.2 m / s, and the homogenization time is 4 min.

[0041] The oxidized pellets prepared through the above process achieved a compressive strength of 1521 N / pellet, a drum strength of 90.02%, an abrasion resistance index of 4.98%, and a dynamic reduction pulverization RDI. +3.2 The percentage was 90.11%, and the reduction expansion was 8.79%.

[0042] Example 2:

[0043] Taking a humus-type laterite nickel ore with 22.12% iron and 1.45% nickel as an example;

[0044] S1. Pretreatment: The laterite nickel ore is dried in a drying kiln until the moisture content is less than 2%, then crushed to -3mm (82.5% purity) by a jaw crusher, and then crushed to -1mm by a double roller crusher. The crushed laterite nickel ore is then subjected to a high-pressure roller mill at a roller mill pressure of 2.5 N / mm. 2 With a scrap recycling rate of 40%, the material is further crushed to -1mm, of which -0.074mm accounts for 68.89% and -0.045mm accounts for 42.12%.

[0045] S2. Mixing: The laterite nickel ore after roller milling is mixed with the composite additive using a high-pressure mixer. The composite additive ratio is 10%, the high-pressure mixing time is 120s, and the speed is 2000r / min. The main components of the composite binder are 60% limestone, 5% coke powder, 5% pregelatinized starch, 15% bentonite, and 15% nickel-iron smelting slag. The composite binder is prepared as follows: all components of the composite additive are finely ground to -0.074mm (91.8%). Then, the bentonite is sodium-treated in a 3.0mol / L NaOH solution for 3h and then piled for 24h for maturation. After maturation, the bentonite and pregelatinized starch are pre-treated by high-pressure roller milling for fiberization, and then mixed with limestone, coke powder, and nickel-iron smelting slag in a high-pressure mixer at 2500r / min for 120s.

[0046] S3. Pelletizing: The pretreated mixture prepared in step S2 is pelletized to prepare green pellets. The pelletizing time is controlled at 10 min, the moisture content of the green pellets is 16%, and the particle size of the green pellets is 16 mm to 20 mm. The prepared green pellets have a drop strength of 15.6 times / (0.5 m), a compressive strength of 16.2 N / pellet, and a bursting temperature of 340℃.

[0047] S4. Oxidative Calcination: The green pellets obtained in step S3 are loaded into a belt calciner for drying, preheating, and calcination, with the material layer height controlled at 400 mm. The temperature for exhaust drying of the green pellets is 200℃, the drying velocity is 1.2 m / s, and the drying time is 5 min. The temperature for forced air drying is 270℃, the drying velocity is 1.2 m / s, and the drying time is 5 min. The preheating temperature is 1050℃, the preheating velocity is 2.4 m / s, and the preheating time is 15 min. The calcination temperature is 1275℃, the calcination velocity is 2.2 m / s, and the calcination time is 15 min. The homogenization temperature is 900℃, the homogenization velocity is 2.2 m / s, and the homogenization time is 4 min.

[0048] The oxidized pellets prepared through the above process achieved a compressive strength of 1898 N / piece, a drum strength of 91.11%, an abrasion resistance index of 4.46%, and a dynamic reduction pulverization RDI. +3.2 The value was 90.89%, and the reduction expansion was 8.34%.

[0049] Example 3:

[0050] Taking a humus-type laterite nickel ore with 22.12% iron and 1.45% nickel as an example;

[0051] S1. Pretreatment: The laterite nickel ore is dried in a drying kiln until the moisture content is less than 2%, then crushed to -3mm (83.45% purity) by a jaw crusher, and then crushed to -1mm by a double roller crusher. The crushed laterite nickel ore is then subjected to a high-pressure roller mill at a roller mill pressure of 3.0 N / mm. 2 With a scrap recycling rate of 50%, the material is further crushed to -1mm, of which -0.074mm accounts for 69.78% and -0.045mm accounts for 44.12%.

[0052] S2. Mixing: The laterite nickel ore after roller milling is mixed with the composite additive using a high-pressure mixer. The composite additive ratio is 15%, the high-pressure mixing time is 180s, and the speed is 3000r / min. The main components of the composite binder are 50% limestone, 10% coke powder, 10% pregelatinized starch, 20% bentonite, and 10% nickel-iron smelting slag. The composite binder is prepared as follows: all components of the composite additive are finely ground to -0.074mm (92.28%). Then, the bentonite is sodium-treated in a 4.0mol / L NaOH solution for 3h and then stored for 24h for maturation. After maturation, the bentonite and pregelatinized starch are pre-treated by high-pressure roller milling for fiberization, and then mixed with limestone, coke powder, and nickel-iron smelting slag in a high-pressure mixer at 3000r / min for 180s.

[0053] S3. Pelletizing: The pretreated mixture prepared in step S2 is pelletized to prepare green pellets. The pelletizing time is controlled at 12 min, the moisture content of the green pellets is 15.5%, and the particle size of the green pellets is 16 mm to 20 mm. The prepared green pellets have a drop strength of 16.8 times / (0.5 m), a compressive strength of 17.7 N / pellet, and a bursting temperature of 380℃.

[0054] S4. Oxidative Calcination: The green pellets obtained in step S3 are loaded into a belt calciner for drying, preheating, and calcination, with the material layer height controlled at 400 mm. The temperature for exhaust drying of the green pellets is 220℃, the drying velocity is 1.2 m / s, and the drying time is 4 min. The temperature for forced air drying is 280℃, the drying velocity is 1.2 m / s, and the drying time is 4 min. The preheating temperature is 1100℃, the preheating velocity is 2.4 m / s, and the preheating time is 15 min. The calcination temperature is 1250℃, the calcination velocity is 2.2 m / s, and the calcination time is 15 min. The homogenization temperature is 950℃, the homogenization velocity is 2.2 m / s, and the homogenization time is 4 min.

[0055] The oxidized pellets prepared through the above process achieved a compressive strength of 2022 N / piece, a drum strength of 92.23%, an abrasion resistance index of 4.23%, and a dynamic reduction pulverization RDI. +3.2 The percentage was 91.45%, and the reduction expansion was 8.22%.

[0056] Example 4

[0057] Take, for example, a mixed laterite nickel ore, consisting of 50% of humus-type laterite nickel ore containing 22.12% iron and 1.45% nickel, and 50% of transitional laterite nickel ore containing 28.98% iron and 1.12% nickel;

[0058] S1. Pretreatment: The laterite nickel ore is dried in a drying kiln until the moisture content is less than 2%, then crushed to -3mm (84.56% purity) by a jaw crusher, and then crushed to -1mm by a double roller crusher. The crushed laterite nickel ore is then subjected to a high-pressure roller mill at a roller mill pressure of 1.5 N / mm. 2 With a scrap recycling rate of 40%, the material is further crushed to -1mm, of which -0.074mm accounts for 65.2% and -0.045mm accounts for 35.7%.

[0059] S2. Mixing: The laterite nickel ore after roller milling is mixed with the composite additive using a high-pressure mixer. The composite additive ratio is 5%, the high-pressure mixing time is 120s, and the speed is 3000r / min. The main components of the composite binder are 50% limestone, 10% coke powder, 15% pregelatinized starch, 15% bentonite, and 10% nickel-iron smelting slag. The composite binder is prepared as follows: all components of the composite additive are finely ground to -0.074mm (92.5%). Then, the bentonite is sodium-treated in a 1.5mol / L NaOH solution for 2 hours and stored for 24 hours for maturation. After maturation, the bentonite and pregelatinized starch are pre-treated by fiberization through a high-pressure roller mill, and then mixed with limestone, coke powder, and nickel-iron smelting slag in a high-pressure mixer at 1500r / min for 60s.

[0060] S3. Pelletizing: The pretreated mixture prepared in step S2 is pelletized to prepare green pellets. The pelletizing time is controlled at 12 min, the moisture content of the green pellets is 13.5%, and the particle size of the green pellets is 16 mm to 20 mm. The prepared green pellets have a drop strength of 14.8 times / (0.5 m), a compressive strength of 16.7 N / pellet, and a bursting temperature of 320℃.

[0061] S4. Oxidative Calcination: The green pellets obtained in step S3 are loaded into a belt calciner for drying, preheating, and calcination, with the material layer height controlled at 300 mm. The temperature for exhaust drying of the green pellets is 220℃, the drying velocity is 1.2 m / s, and the drying time is 4 min. The temperature for forced air drying is 250℃, the drying velocity is 1.2 m / s, and the drying time is 4 min. The preheating temperature is 1100℃, the preheating velocity is 2.4 m / s, and the preheating time is 15 min. The calcination temperature is 1300℃, the calcination velocity is 2.2 m / s, and the calcination time is 15 min. The homogenization temperature is 900℃, the homogenization velocity is 2.2 m / s, and the homogenization time is 4 min.

[0062] The oxidized pellets prepared through the above process achieved a compressive strength of 1789 N / pellet, a drum strength of 91.56%, an abrasion resistance index of 4.76%, and a dynamic reduction pulverization RDI. +3.2 The percentage was 90.56%, and the reduction expansion was 9.12%.

[0063] Example 5

[0064] Take, for example, a mixture of 75% humus-type laterite nickel ore containing 22.12% iron and 1.45% nickel and 25% transitional laterite nickel ore containing 28.98% iron and 1.12% nickel;

[0065] S1. Pretreatment: The laterite nickel ore is dried in a drying kiln until the moisture content is less than 2%, then crushed to -3mm (82.33% purity) by a jaw crusher, and then crushed to -1mm by a double roller crusher. The crushed laterite nickel ore is then subjected to a high-pressure roller mill at a roller mill pressure of 2.5 N / mm. 2 With a scrap recycling rate of 40%, the material is further crushed to -1mm, of which -0.074mm accounts for 67.78% and -0.045mm accounts for 37.22%.

[0066] S2. Mixing: The laterite nickel ore after roller milling is mixed with the composite additive using a high-pressure mixer. The composite additive ratio is 6%, the high-pressure mixing time is 120s, and the rotation speed is 3000r / min. The main components of the composite binder are 55% limestone, 10% coke powder, 10% pregelatinized starch, 15% bentonite, and 10% nickel-iron smelting slag. The composite binder is prepared as follows: all components of the composite additive are finely ground to -0.074mm (93.2%). Then, the bentonite is sodium-treated in a 2.5mol / L NaOH solution for 2h and stored for 24h for maturation. After maturation, the bentonite and pregelatinized starch are pre-treated by high-pressure roller milling for fiberization, and then mixed with limestone, coke powder, and nickel-iron smelting slag in a high-pressure mixer at 1500r / min for 60s.

[0067] S3. Pelletizing: The pretreated mixture prepared in step S2 is pelletized to prepare green pellets. The pelletizing time is controlled at 12 min, the moisture content of the green pellets is 14.0%, and the particle size of the green pellets is 16 mm to 20 mm. The prepared green pellets have a drop strength of 15.2 times / (0.5 m), a compressive strength of 17.3 N / pellet, and a bursting temperature of 330℃.

[0068] S4. Oxidative Calcination: The green pellets obtained in step S3 are loaded into a belt calciner for drying, preheating, and calcination, with the material layer height controlled at 400 mm. The temperature for exhaust drying of the green pellets is 240℃, the drying velocity is 1.2 m / s, and the drying time is 4 min. The temperature for forced air drying is 250℃, the drying velocity is 1.2 m / s, and the drying time is 4 min. The preheating temperature is 1100℃, the preheating velocity is 2.4 m / s, and the preheating time is 15 min. The calcination temperature is 1300℃, the calcination velocity is 2.2 m / s, and the calcination time is 15 min. The homogenization temperature is 900℃, the homogenization velocity is 2.2 m / s, and the homogenization time is 4 min.

[0069] The oxidized pellets prepared through the above process achieved a compressive strength of 2002 N / piece, a drum strength of 92.32%, an abrasion resistance index of 4.35%, and a dynamic reduction pulverization RDI. +3.2 The percentage was 91.12%, and the reduction expansion was 8.89%.

[0070] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for preparing hydrogen-based oxide pellets for laterite nickel ore shaft furnaces based on liquid phase control, characterized by comprising the following steps: S1. Pretreatment: After drying, the laterite nickel ore is pretreated by crushing and high-pressure roller milling to obtain pretreated laterite nickel ore; S2. Mixing: Mix the pretreated laterite nickel ore and composite additives obtained in step S1 to obtain a mixture. S3. Pelletizing: Pelletize the mixture obtained in step S2 to prepare green pellets; S4. Oxidative calcination: The green pellets obtained in step S3 are dried, preheated and calcined to prepare high-strength, high-reducing oxidized pellets.

2. The method for preparing oxide pellets for a hydrogen-based vertical shaft furnace of laterite nickel ore based on liquid phase control according to claim 1, characterized in that, The laterite nickel ore includes one or more of the following: limonite-type laterite nickel ore, transitional laterite nickel ore, and humus-type laterite nickel ore, containing 15% to 50% iron and 0.7% to 2.5% nickel.

3. A method for preparing oxide pellets for a hydrogen-based vertical shaft furnace of laterite nickel ore based on liquid phase control, as described in claim 1 or 2, characterized in that, Step S1 specifically involves: drying the laterite nickel ore in a drying kiln until the moisture content is less than 2%, crushing it to a density of over 80% for -3mm using a jaw crusher, then further crushing it to -1mm using a double roller crusher; finally, further crushing it using a high-pressure roller mill to achieve a density of 60-70% for -0.074mm and 30-45% for -0.045mm; the pressure of the high-pressure roller mill is 1.0-4.0 N / mm. 2 The scrap recycling rate is 20%~50%.

4. The method for preparing oxide pellets for a hydrogen-based vertical shaft furnace of laterite nickel ore based on liquid phase control according to claim 1, characterized in that, In step S2, a composite additive is added to the pretreated laterite nickel ore in step S1, with a proportion of 5% to 15% of the laterite nickel ore. The composite additive consists of 50% to 70% calcium-based flux, 10% to 15% carbonaceous material, 10% to 15% pregelatinized starch, 15% to 25% bentonite, and 5% to 10% nickel-iron smelting slag. The calcium-based flux contains at least one of limestone, quicklime, and hydrated lime; The carbonaceous material mentioned includes at least one of coke powder, bituminous coal, anthracite, and semi-coke; The nickel-iron smelting slag mentioned above is the smelting slag produced during the smelting process of nickel sulfide ore.

5. The method for preparing oxide pellets for a hydrogen-based vertical shaft furnace of laterite nickel ore based on liquid phase control according to claim 4, characterized in that, In step 2, the preparation method of the composite additive is as follows: All components of the composite additive are finely ground to -0.074 mm with a content of over 90%. Then, bentonite is subjected to sodium treatment in NaOH solution and stored for 24 hours for aging to ensure sufficient sodium treatment effect. The concentration of NaOH solution is 1 mol / L to 4 mol / L and the sodium treatment time is 2 to 3 hours. After aging, bentonite and pregelatinized starch are subjected to fiber pretreatment by high-pressure roller mill, and then mixed with calcium-based flux, carbon-containing materials and nickel-iron smelting slag using a high-power mixer. The mixing time of the high-intensity mixer is 60~180s, and the rotation speed is 1000~3000r / min.

6. The method for preparing oxide pellets for a hydrogen-based vertical shaft furnace of laterite nickel ore based on liquid phase control according to claim 1, characterized in that, Step S2 specifically involves mixing laterite nickel ore and composite additives with water in a high-powered mixer; the high-powered mixer has a mixing time of 60-120 seconds and a rotation speed of 1000-3000 r / min.

7. The method for preparing oxide pellets for a hydrogen-based vertical shaft furnace of laterite nickel ore based on liquid phase control according to claim 1, characterized in that, Step S3 specifically involves adding the mixed material to a disc pelletizer for pelletizing. The pelletizing time is 8 min to 12 min, the moisture content of the raw pellets is 12% to 16%, and the particle size of the raw pellets is 16 mm to 20 mm.

8. The method for preparing oxide pellets for a hydrogen-based vertical shaft furnace of laterite nickel ore based on liquid phase control according to claim 1, characterized in that, Step S4 specifically involves: preparing oxidized pellets using a belt calciner, with a material layer height of 300-500 mm, a forced-air drying temperature of 200℃-300℃, a forced-air drying velocity of 1.0-1.5 m / s, and a forced-air drying time of 4-6 min; and an exhaust drying temperature of 200℃-300℃, an exhaust drying velocity of 1.0-1.5 m / s, and a drying time of 4-6 min. The preheating temperature is 800℃~1100℃, the preheating air velocity is 2.2~2.6m / s, and the preheating time is 10min~15min; The roasting temperature is 1200℃~1300℃, the roasting air velocity is 2.2~2.6m / s, and the roasting time is 10min~15min; the homogenization temperature is 800℃~1000℃, the homogenization air velocity is 2.0~2.2m / s, and the homogenization time is 3min~5min.

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