A limonite-type laterite nickel ore oxidation pellet and its preparation method and application

Abstract

The present invention belongs to the field of metallurgical technology, and specifically relates to a limonite-type laterite nickel ore oxidation pellet, and a preparation method and application thereof. The method comprises the following steps: dividing the dried coarse-grained limonite-type laterite nickel ore into two parts, a and b; preparing nickel-iron concentrate after enriching iron and nickel from part a; drying part b of the limonite-type laterite nickel ore to obtain a binder; mixing the nickel-iron concentrate and the binder obtained in step F in a certain proportion to obtain a mixture; pelletizing the mixture to obtain raw balls of a certain particle size; drying, preheating, roasting, and cooling the raw balls in sequence to obtain limonite-type laterite nickel ore oxidation pellets. The present invention is aimed at limonite-type laterite nickel ore with a high crystal water content, and changes its surface properties by magnetizing roasting, so that it is more conducive to forming pellets. The raw materials are subjected to magnetizing roasting and the roasted balls have higher strength, which is more in line with the needs of blast furnace smelting.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgy, and in particular relates to a limonite-type laterite nickel ore oxidation pellet and a preparation method and application thereof. Background Art

[0002] Nickel is an important strategic metal, which is mostly used as an alloy element to produce various types and grades of steel, including food-grade stainless steel that is indispensable to people's lives, as well as high-temperature alloy steel and high-performance special steel commonly used in national defense, military, aerospace, etc.

[0003] Nickel, as a common austenite-forming element, can change the crystal structure of stainless steel. For example, it can change the crystal structure of plain carbon steel from a body-centered cubic (BCC) structure to a face-centered cubic (FCC) structure, thereby changing plain carbon steel into austenitic stainless steel and improving the properties of stainless steel, giving it excellent plasticity, weldability and toughness.

[0004] 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 metallic nickel source. However, as the nickel sulfide ore with low mining difficulty becomes less and less, the development cost is getting higher and higher. Using laterite nickel ore as raw material to produce ferronickel and using ferronickel instead of electrolytic nickel as the metallic nickel source is an important trend in the sustainable development of the stainless steel industry.

[0005] Among land-based nickel resources, the nickel content of sulfide nickel ore and laterite nickel ore is about 3:7, and the nickel production ratio is about 1:1. As the demand for stainless steel continues to rise, the demand for nickel iron has been driven, so laterite nickel ore has gradually become the focus and hot spot of nickel resource development.

[0006] Many studies and work have been done on the wet treatment of laterite nickel ore, and a series of processes and technologies for efficiently extracting nickel and cobalt from laterite nickel ore have been developed. The process energy consumption and production cost of wet treatment of laterite nickel ore are significantly lower than those of pyrometallurgical treatment of laterite nickel ore. However, compared with pyrometallurgical treatment, wet treatment of laterite nickel ore is limited by factors such as small production scale and long production process, and accounts for a small proportion of nickel produced by laterite nickel ore.

[0007] Under the current high demand for stainless steel, pyrometallurgy can meet the current industry needs through large-scale industrial production, and at the same time recover the iron in laterite nickel ore, thereby recovering costs and improving economic benefits. The main pyrometallurgical processes currently include the matte smelting process for producing nickel matte and the rotary kiln granular iron process, blast furnace smelting process, and rotary kiln pre-reduction-electric furnace smelting process for producing nickel iron.

[0008] The main application method of limonite-type laterite nickel ore in China is the sintering-blast furnace method, which prepares nickel-containing iron water through sintering and then prepares stainless steel, but the sintering machine has low output, low sintered ore strength, and seriously affects the smooth operation of the blast furnace. In addition, there is a lack of acidic furnace charge that balances the alkalinity in the blast furnace, and the process of directly preparing oxidized pellets from limonite-type laterite nickel ore has not yet made a breakthrough. An effective method for preparing limonite-type laterite nickel ore pellets is urgently needed to fill the gap in blast furnace acidic furnace charge. Summary of the invention

[0009] In order to solve the deficiencies of the prior art, the present invention provides a limonite-type laterite-nickel ore oxidized pellet and a preparation method and application thereof. The present invention uses part of the limonite-type laterite-nickel ore to prepare nickel-iron concentrate after enrichment of iron and nickel, and uses part of the limonite-type laterite-nickel ore to prepare a binder, which can improve the pelletizing performance of the limonite-type laterite-nickel ore without introducing other minerals. The limonite-type laterite-nickel ore oxidized pellet provided by the present invention can be used as blast furnace acidic charge, has high compressive strength, and meets the requirements of blast furnace charge.

[0010] The technical solution provided by the present invention is as follows:

[0011] A method for preparing limonite-type laterite nickel ore oxidation pellets comprises the following steps:

[0012] A: The dried coarse-grained limonite-type laterite nickel ore is divided into two parts, a and b;

[0013] B: uniformly mixing the limonite-type laterite nickel ore part a obtained in step A with a certain proportion of a reducing agent to obtain a mixture;

[0014] C: roasting the mixture obtained in step B to obtain a magnetized roasted ore;

[0015] D: Grinding the magnetized roasted ore obtained in step C;

[0016] E: subjecting the magnetized roasted ore obtained in step D to magnetic separation to obtain nickel-iron concentrate enriched with iron and nickel;

[0017] F: drying the limonite-type laterite nickel ore part b obtained in step A to obtain a binder;

[0018] G: uniformly mixing the nickel iron concentrate obtained in step E and the binder obtained in step F in a certain proportion to obtain a mixture;

[0019] H: pelletizing the mixture obtained in step G to obtain green balls of a certain particle size;

[0020] I: The green balls obtained in step H are dried, preheated, roasted and cooled in sequence to obtain limonite-type laterite nickel ore oxidized pellets.

[0021] In the above technical solution:

[0022] For limonite-type laterite nickel ore with high crystal water content and high viscosity, magnetizing and roasting part of limonite-type laterite nickel ore can change its surface properties, reduce viscosity, and improve ball-forming performance. At the same time, nickel-iron concentrate enriched with iron and nickel can be prepared to increase the nickel and iron content in the pellets.

[0023] Modifying some limonite-type laterite nickel ore and increasing its surface area can enhance the viscosity of limonite-type laterite nickel ore when used as a binder to ensure ball formation without introducing other mineral impurities.

[0024] Specifically, in step A:

[0025] Drying temperature is 50℃~300℃;

[0026] The moisture content of the limonite-type laterite nickel ore after drying is <1%.

[0027] Specifically, in step B, the reducing agent includes but is not limited to anthracite, CO or H2, the amount of solid reducing agent added is 5-30% of the limonite-type laterite nickel ore a, and the set concentration of the gas reducing agent is not less than 10%.

[0028] Specifically, in step C, the magnetization calcination temperature is 650-900° C., and the magnetization calcination time is 10-120 min.

[0029] Specifically, in step D, the grinding equipment is selected from a tower mill or a ball mill; the grinding method is dry grinding or wet grinding; the particle size of the ore particles after the grinding treatment is -0.074 mm, accounting for 40 to 90%;

[0030] Specifically, in step E, the magnetic separation equipment includes but is not limited to a dry magnetic separator or a wet magnetic separator, and the magnetic field strength is 800 to 3000 Gs; the iron content in the nickel-iron concentrate is 55 to 62%, and the nickel content is 0.9 to 1.2%.

[0031] Furthermore, in step F, grinding and modification are performed after drying, which is beneficial to increase the specific surface area of ​​the limonite-type laterite nickel ore b. The particle size of the ore particles after modification is -0.074 mm, accounting for 60-90%.

[0032] Specifically, in step G, the amount of binder added is 5 to 30% of the mass of the mixture.

[0033] Specifically, in step H, the ball making process includes but is not limited to a disc ball making process or a cold pressing ball making process, the ball making time is 9 to 30 minutes, the moisture content of the raw balls is 8 to 25%, and the particle size of the raw balls is 6 to 20 mm.

[0034] Specifically, in step I, the green balls are dried in a belt roaster or a chain grate rotary kiln, the preheating temperature is 1000-1200°C, the preheating time is 10-20 minutes, the roasting temperature is 1200-1300°C, and the roasting time is 10-20 minutes.

[0035] The present invention also provides an oxidized pellet prepared according to the above preparation method. It can be used as an acidic charge for a blast furnace.

[0036] The oxidized pellets provided by the present invention have a nickel content of more than 1.2% and a compressive strength of more than 2000 N. They meet the requirements of blast furnace charge and can be used as blast furnace acid charge.

[0037] The beneficial effects of the present invention are:

[0038] The present invention aims at limonite-type laterite nickel ore with high crystalline water content, and changes its surface properties through magnetization roasting to make it more conducive to forming pellets. The pellets of the raw materials after magnetization roasting have higher strength and are more in line with the requirements of blast furnace smelting. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The present invention provides a process flow chart of the method for preparing limonite-type laterite nickel ore oxidation pellets. DETAILED DESCRIPTION

[0040] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0041] In the following examples, unless otherwise specified, all raw materials or reagents are from the prior art.

[0042] The limonite-type laterite nickel ore raw material was purchased, and its specific indicators were as follows: TFe=46.0%, Ni=0.8%.

[0043] Comparative Example 1

[0044] In a comparative example, a limonite-type laterite nickel ore with TFe=46.0% and Ni=0.8% was dried at 150°C for 20 minutes, and the particle size before and after drying was 3 mm. Dry grinding was used to grind the limonite-type laterite nickel ore to a particle size of -0.074 mm, accounting for 60%, and mixed with bentonite with a particle size of -0.074 mm, accounting for 90%, and the mass ratio of bentonite was 1.5% of the total mass. Under the condition of 10% moisture, the green ball particle size was controlled at 8-16 mm, the green ball drop strength was 5 times / 0.5m, the roasting temperature was 1250°C, the roasting time was 15 minutes, and the finished pellets were prepared, and the compressive strength was 1200N / piece.

[0045] Example 1

[0046] In one embodiment, a limonite-type laterite nickel ore with TFe=46.0% and Ni=0.8% is divided into two parts, a and b. The limonite-type laterite nickel ore a is mixed with anthracite powder, a reducing agent, with a particle size of less than 1 mm, according to a mass ratio, wherein the anthracite accounts for 15% of the total amount of anthracite and limonite-type laterite nickel ore, and is magnetized and roasted at 750°C for 20 minutes; the magnetized and roasted limonite-type laterite nickel ore is crushed by dry grinding to an ore particle size of -0.074 mm, accounting for 80%. The magnetized and roasted limonite-type laterite nickel ore is separated by a dry magnetic separation device at a magnetic field strength of 1000Gs, and the separated nickel iron concentrate has TFe=60% and Ni=1.0%. The limonite-type laterite nickel ore b is dried at 150°C for 120 minutes, and the limonite-type laterite nickel ore b is a binder, and the particle size is -0.074 mm, accounting for 30%. The nickel-iron concentrate is mixed with the binder, the mass ratio of the binder is 1.5% of the total mass, and the moisture content is 10%. The green ball particle size is controlled at 8-16mm, the green ball drop strength is 20 times / 0.5m, the roasting temperature is 1250℃, the roasting time is 15min, and the finished pellets are prepared, and their compressive strength is 1800N / piece.

[0047] Example 2

[0048] In one embodiment, a limonite-type laterite nickel ore with TFe=44.3% and Ni=0.7% is divided into two parts, a and b. The limonite-type laterite nickel ore a is roasted under a CO concentration of 40%, and magnetized and roasted at 850°C for 30 minutes; the magnetized and roasted limonite-type laterite nickel ore is crushed by wet ball milling to a particle size of -0.074 mm, accounting for 60%. The magnetized and roasted limonite-type laterite nickel ore is sorted by dry magnetic separation equipment at a magnetic field strength of 1200Gs, and the nickel iron concentrate after sorting has TFe=61% and Ni=1.2%. The limonite-type laterite nickel ore b is dried at 130°C for 120 minutes to obtain the limonite-type laterite nickel ore b as a binder, and the particle size is -0.074 mm, accounting for 60%. The nickel-iron concentrate is mixed with the granular binder, the mass ratio of the binder is 1.9% of the total mass, and the moisture content is 8%. The particle size of the green ball is controlled at 8-16 mm, the drop strength of the green ball is 15 times / 0.5 m, the roasting temperature is 1200 ° C, the roasting time is 10 min, and the finished pellets are prepared with a compressive strength of 2000 N / piece.

[0049] Example 3

[0050] In one embodiment, a limonite-type laterite nickel ore with TFe=46.3% and Ni=0.9% is divided into two parts, a and b. The limonite-type laterite nickel ore a is roasted under a CO concentration of 30% and magnetized and roasted at 800°C for 50 minutes. The magnetized and roasted limonite-type laterite nickel ore is crushed by wet ball milling to a particle size of -0.074 mm, accounting for 70%. The magnetized and roasted limonite-type laterite nickel ore is sorted by dry magnetic separation equipment at a magnetic field strength of 1500Gs, and the nickel-iron concentrate after sorting has TFe=60% and Ni=1.1%. The limonite-type laterite nickel ore b is dried at 150°C for 120 minutes, and the limonite-type laterite nickel ore b obtained is used as a binder, and is ground and modified, and the particle size is -0.074 mm, accounting for 95%. Mix the nickel iron concentrate with the granular binder, the mass ratio of the binder is 1.5% of the total mass, and the green ball particle size is controlled at 8-16mm under the condition of 20% water content, the green ball drop strength is 10 times / 0.5m, the roasting temperature is 1250℃, the roasting time is 10min, and the finished pellets are prepared, and their compressive strength is 2600N / piece. The process can be as follows Figure 1 shown.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing limonite-type laterite nickel ore oxidation pellets, characterized in that: The following steps are involved: A: The dried coarse-grained limonite-type laterite nickel ore is divided into two parts, a and b; B: uniformly mixing the limonite-type laterite nickel ore part a obtained in step A with a certain proportion of a reducing agent to obtain a mixture; C: roasting the mixture obtained in step B to obtain a magnetized roasted ore; D: Grinding the magnetized roasted ore obtained in step C; E: subjecting the magnetized roasted ore obtained in step D to magnetic separation to obtain nickel-iron concentrate enriched with iron and nickel; F: drying the limonite-type laterite nickel ore part b obtained in step A to obtain a binder; G: uniformly mixing the nickel iron concentrate obtained in step E and the binder obtained in step F in a certain proportion to obtain a mixture; H: pelletizing the mixture obtained in step G to obtain green balls of a certain particle size; I: drying, preheating, roasting and cooling the green balls obtained in step H in sequence to obtain limonite-type laterite nickel ore oxidized balls; In step G, the amount of binder added is 5 to 30% of the mass of the mixture; In step F: the dried limonite-type laterite nickel ore b is ground and modified; after the modification, the particle size of the ore particles is -0.074 mm, accounting for 60-90%.

2. The method for preparing limonite-type laterite nickel ore oxidized pellets according to claim 1, characterized in that: In step A: Drying temperature is 50℃~300℃; The moisture content of the limonite-type laterite nickel ore after drying is <1%.

3. The method for preparing limonite-type laterite nickel ore oxidized pellets according to claim 1, characterized in that: In step B, the reducing agent includes but is not limited to anthracite, CO or H2, the amount of solid reducing agent added is 5-30% of the limonite-type laterite nickel ore a, and the concentration of gas reducing agent is set not less than 10%; In step C, the magnetization calcination temperature is 650-900° C., and the magnetization calcination time is 10-120 min.

4. The method for preparing limonite-type laterite nickel ore oxidized pellets according to claim 1, characterized in that: In step D, the grinding equipment is selected from a tower mill or a ball mill; the grinding method is dry grinding or wet grinding; the particle size of the ore particles after the grinding treatment is -0.074 mm, accounting for 40 to 90%; In step E, the magnetic separation equipment includes but is not limited to a dry magnetic separator or a wet magnetic separator, and the magnetic field strength is 800 to 3000 Gs; the iron content in the nickel-iron concentrate is 55 to 62%, and the nickel content is 0.9 to 1.2%.

5. The method for preparing limonite-type laterite nickel ore oxidized pellets according to claim 1, characterized in that: In step H, the ball making process includes but is not limited to a disc ball making process or a cold pressing ball making process, the ball making time is 9 to 30 minutes, the moisture content of the raw balls is 8 to 25%, and the particle size of the raw balls is 6 to 20 mm.

6. The method for preparing limonite-type laterite nickel ore oxidized pellets according to any one of claims 1 to 5, characterized in that: In step I, the green balls are dried in a belt roaster or a chain grate rotary kiln, the preheating temperature is 1000-1200°C, the preheating time is 10-20 minutes, the roasting temperature is 1200-1300°C, and the roasting time is 10-20 minutes.

7. An oxidized pellet prepared according to the preparation method according to any one of claims 1 to 6.

8. An application of the oxidized pellets according to claim 7, characterized in that: As acidic charge for blast furnace.

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