A method for preparing a porous magnesium silicate-based adsorbent by using laterite nickel ore smelting tailings and magnesite tailings

Abstract

The application relates to a method for preparing a porous magnesium silicate-based adsorbent by using laterite nickel ore smelting tailings and magnesite tailings, and belongs to the field of comprehensive utilization of mineral resources. The method uses the laterite nickel ore smelting tailings and the magnesite tailings as raw materials, uses low-cost coal powder as fuel, and prepares the porous magnesium silicate-based adsorbent through a heat-preservation crystallization-fine grinding activation-calcination crystallization method. The product has good crystallinity and large specific surface area, realizes high-value utilization of the laterite nickel ore smelting tailings and the magnesite tailings, achieves the purpose of consuming industrial solid wastes, and has high economic and social benefits.

Description

Technical Field

[0001] This invention belongs to the field of comprehensive utilization of mineral resources, specifically relating to a method for preparing porous magnesium silicate-based adsorbents using tailings from laterite nickel ore smelting and magnesite tailings. Background Technology

[0002] Lateritic nickel ore is an important nickel resource. Among them, the siliceous-magnesian type lateritic nickel ore is characterized by nickel and silicates in association, and has a high magnesium content. Pyrometallurgical processes to produce ferronickel alloys are an effective method for processing this type of lateritic nickel ore. A typical RKEF process involves crushing the lateritic nickel ore and feeding it into a rotary kiln. After drying, roasting, and pre-reduction, it enters a submerged arc furnace for electric arc reduction smelting. After melting and separation in the submerged arc furnace, ferronickel alloys and smelting tailings are obtained. Since 2015, China has generated over 100 million tons of lateritic nickel ore smelting tailings annually. The main components of smelting tailings are silicon dioxide and magnesium oxide, and they often contain elements such as iron, aluminum, and calcium. To reduce the environmental damage caused by the stockpiling and landfilling of lateritic nickel ore smelting tailings, research on the comprehensive utilization of smelting tailings is particularly important. Lateritic nickel ore smelting tailings are generally used as raw materials for building materials and industrial asbestos, and related comprehensive utilization is still in the theoretical research stage. Therefore, how to make high-value-added large-scale utilization of tailings from laterite nickel ore smelting remains an urgent problem to be solved.

[0003] Approximately 50% of the magnesite mining and processing yields tailings, resulting in a large amount of industrial solid waste. Currently, both domestically and internationally, magnesite tailings are disposed of through stockpiling and landfilling. This not only wastes mineral resources and occupies vast amounts of land, but also damages the local ecological environment. The main component of magnesite tailings is MgO, accounting for approximately 20%–40%, with the remaining main component being SiO2, accounting for approximately 10%–30%, and small amounts of CaO and Al2O3. Due to the high MgO content in magnesite tailings, it is theoretically possible to recycle and reuse them as raw materials to produce magnesium-containing building materials (concrete, cement, microcrystalline glass), refractory materials (magnesia sand), and ceramic materials. In conclusion, the treatment and reuse of magnesite tailings is an urgent problem to be solved.

[0004] Magnesium silicate is a novel layered adsorbent material. In recent years, it has been used to treat heavy metal ions and organic dyes in water, showing promising application prospects. Currently reported synthesis methods for magnesium silicate adsorbents mainly include hydrothermal synthesis, solvothermal synthesis, and template methods. These methods primarily use high-purity reagents such as water glass, magnesium sulfate, magnesium chloride, and silicon dioxide as raw materials, resulting in high costs and hindering large-scale industrial production. Summary of the Invention

[0005] To address the shortcomings of existing technologies, particularly the difficulties in large-scale utilization of laterite nickel ore smelting tailings and magnesite tailings, unreasonable reuse processes, poor product performance, and low value, this invention provides a method for preparing porous magnesium silicate-based adsorbents using laterite nickel ore smelting tailings and magnesite tailings. This method uses laterite nickel ore smelting tailings and magnesite tailings as raw materials, and inexpensive coal powder and coal gangue as fuel. The porous magnesium silicate-based adsorbent is prepared through a heat-insulating crystallization-fine grinding activation-calcination crystallization method. The product has good crystallinity and a large specific surface area, achieving high-value-added utilization of laterite nickel ore smelting tailings and magnesite tailings, while simultaneously achieving the goal of consuming industrial solid waste.

[0006] The technical solution of this invention is as follows:

[0007] A method for preparing porous magnesium silicate-based adsorbents using tailings from laterite nickel ore smelting and magnesite tailings specifically includes the following steps:

[0008] (1) Insulation pre-reaction

[0009] The high-temperature laterite nickel ore smelting tailings in the electric arc furnace flow into the heat preservation bin through the discharge port. The magnesite tailings containing a certain amount of moisture are dried using the waste heat of the rotary kiln. The dried magnesite tailings are transported by belt and feeder and mixed with the laterite nickel ore smelting tailings at a certain ratio and at a uniform speed. The mixed material is then heat-pre-reacted and cooled to room temperature to obtain the reaction raw material.

[0010] (2) Fine grinding and activation

[0011] The raw materials in step (1) are processed by a jaw crusher and a roller crusher to be crushed to a certain particle size. Then, the raw materials are fed into a ball mill and ground to a certain fineness to obtain activated material.

[0012] (3) Calcination and crystallization

[0013] The activated material is fed into the sintering machine via a feeder. The sintering machine uses pulverized coal as fuel. After the activated material undergoes a roasting and crystallization reaction for a certain period of time, sintered material is obtained.

[0014] (4) Crushing and granulation

[0015] The sintered material is cooled in an annular cooler. The residual heat from sintering is collected and used to dry the magnesite tailings in step (1). The cooled sintered material is crushed by an impact crusher and then screened and sized by a vibrating screen. The coarse particles are porous magnesium silicate adsorbents, and the fine particles are returned to the crushing process before fine grinding.

[0016] in:

[0017] In step (1), the temperature of the tailings from the high-temperature laterite nickel ore smelting is 1400-1600℃; and the content of SiO2+MgO, the main component of the tailings from the laterite nickel ore smelting, is ≥85% by mass fraction.

[0018] In step (1), the total content of CaO+Al2O3 in magnesite is ≤3% by mass fraction, and the moisture content of magnesite tailings is ≤16%.

[0019] In step (1), the mass ratio of magnesite to laterite nickel ore is (0.5-6):1.

[0020] In step (1), the pre-reaction time of the mixture is 6 to 24 hours.

[0021] In step (2), after the reaction raw materials pass through a jaw crusher and a roller crusher, the maximum particle size of the crushed product is 6-10 mm; after ball milling, the fineness of the activated material is -325 mesh, accounting for 65%-98% by mass fraction.

[0022] In step (3), the ash content in the pulverized coal is ≤25% by mass.

[0023] In step (3), the calcination and crystallization reaction temperature of the activated material in the sintering machine is 1200-1420℃, and the time is 20-60min.

[0024] In step (4), the sintering material is cooled in an annular cooler at a rate of 15-40℃ / min. After cooling to 100-200℃, it is naturally cooled in the air. The residual heat from sintering is collected and the magnesite tailings raw material is dried until the moisture content is less than 5%.

[0025] In step (4), the screen size of the vibrating screen is 8-20mm.

[0026] In step (4), the specific surface area of ​​the magnesium silicate adsorbent is 20–55 m². 2 / g.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] (1) This invention makes full use of the high silicon and magnesium content in laterite nickel ore tailings and combines the advantages of magnesium as the main component and high silicon content in magnesite tailings. It creatively proposes a method to prepare high-value-added porous magnesium silicate adsorbent material by high-temperature crystallization reaction of the two.

[0029] (2) This invention makes full use of the high temperature characteristics of the tailings of laterite nickel ore flowing out of the electric arc furnace, quickly mixes the magnesite tailings and the laterite nickel ore tailings, conducts heat preservation pre-reaction, increases the contact time between the two, generates a large number of active contact sites, and utilizes the subsequent high temperature crystallization process.

[0030] (3) After the raw materials for heat preservation reaction are crushed, the present invention uses fine grinding to further promote the mixing and homogenization of laterite nickel ore and magnesite, which increases the specific surface area and reactive sites of the raw materials and is more conducive to the formation of magnesium silicate crystal phase in the subsequent high-temperature roasting stage.

[0031] (4) The fuel used in the high-temperature roasting of this invention is high-ash, low-quality coal powder. The roasting process has low requirements for fuel quality, thus saving fuel costs.

[0032] (5) The present invention fully recovers the waste heat of the ring cooler for preheating and drying of magnesite tailings containing a certain amount of moisture, thereby saving production costs.

[0033] (6) By controlling the ratio of laterite nickel ore smelting tailings and magnesite tailings within a reasonable range, and by controlling the three processes of preheating reaction, fine grinding activation and high-temperature roasting, the present invention fully ensures the crystal quality and pore structure of magnesium silicate adsorbent products. The products have excellent properties such as high degree of crystallinity and large specific surface area. Attached Figure Description

[0034] Figure 1 A schematic diagram of the process for preparing porous magnesium silicate-based adsorbents using tailings from laterite nickel ore smelting and magnesite tailings.

[0035] Figure 2 In Example 1 of this invention, the XRD pattern of the obtained porous magnesium silicate sample is shown. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Example 1

[0038] A method for preparing porous magnesium silicate-based adsorbents using tailings from laterite nickel ore smelting and magnesite tailings is illustrated in the following flowchart. Figure 1 As shown, the specific steps include:

[0039] (1) Insulation pre-reaction

[0040] The high-temperature laterite nickel ore smelting tailings (SiO2+MgO ​​total content of 87.62% by mass fraction) at 1450℃ in the electric arc furnace flowed into the heat preservation silo through the discharge port. Magnesite tailings containing 14% moisture by mass (CaO+Al2O3 total content of 1.54% by mass fraction) were dried using the waste heat of the rotary kiln. The dried magnesite tailings were transported by belt conveyor and feeder and mixed with the laterite nickel ore smelting tailings at a uniform speed according to the mass ratio of magnesite to laterite nickel ore of 4:1. The mixed material was kept at a high temperature for 8 hours for pre-reaction, and then cooled to room temperature to obtain the reaction raw material.

[0041] (2) Fine grinding and activation

[0042] The reaction raw materials in step (1) are processed by a jaw crusher and a roller crusher to crush the product to a maximum particle size of 10 mm. The raw materials are then fed into a ball mill for fine grinding to obtain activated material. The activated material has a fineness of -325 mesh content of 71% (by mass fraction).

[0043] (3) Calcination and crystallization

[0044] The activated material is fed into the sintering machine via a feeder. The calcination and crystallization reaction temperature of the activated material in the sintering machine is 1250℃. The sintering machine uses pulverized coal with an ash content of 21% as fuel. The sintering material is obtained after calcination and crystallization reaction of the activated material for 30 minutes.

[0045] (4) Crushing and granulation

[0046] The sintered material was cooled in an annular cooler at a rate of 15℃ / min, and discharged after cooling to 150℃. The residual heat from sintering was collected, and the moisture content of the magnesite tailings from step (1) was dried to a mass fraction of 3.2%. The cooled sintered material was crushed using an impact crusher, and then sieved and sized using a vibrating screen with a 10mm aperture. Coarse particles with a diameter greater than or equal to the screen aperture size were used as porous magnesium silicate adsorbent, while fine particles smaller than the screen aperture size were returned to the pre-grinding crushing process. The final porous magnesium silicate adsorbent had a specific surface area of ​​48.91 m². 2 / g. Its XRD results Figure 2 As shown, its crystallinity is good.

[0047] Example 2

[0048] A method for preparing porous magnesium silicate-based adsorbents using tailings from laterite nickel ore smelting and magnesite tailings specifically includes the following steps:

[0049] (1) Insulation pre-reaction

[0050] The high-temperature laterite nickel ore smelting tailings (SiO2+MgO ​​total content of 91.5% by mass fraction) at 1490℃ in the electric arc furnace flowed into the heat preservation bin through the discharge port. Magnesite tailings containing 9% moisture by mass (CaO+Al2O3 total content of 2.73% by mass fraction) were dried using the waste heat of the rotary kiln. The dried magnesite tailings were transported by belt conveyor and feeder and mixed with the laterite nickel ore smelting tailings at a uniform speed according to a magnesite to laterite nickel ore mass ratio of 2:1. The mixed material was heat-pre-reacted for 16 hours and then cooled to room temperature to obtain the reaction raw material.

[0051] (2) Fine grinding and activation

[0052] The reaction raw materials in step (1) are processed by a jaw crusher and a roller crusher to crush the product to a maximum particle size of 6 mm. The raw materials are then fed into a ball mill for fine grinding to obtain activated material. The activated material contains 86% fineness of -325 mesh (by mass fraction).

[0053] (3) Calcination and crystallization

[0054] The activated material is fed into the sintering machine via a feeder. The calcination and crystallization reaction temperature of the activated material in the sintering machine is 1310℃. The sintering machine uses pulverized coal with an ash content of 17% by mass as fuel. The sintering material is obtained after calcination and crystallization reaction of the activated material for 50 minutes.

[0055] (4) Crushing and granulation

[0056] The sintered material was cooled in an annular cooler at a rate of 25℃ / min, and discharged after cooling to 120℃. The residual heat from sintering was collected, and the moisture content of the magnesite tailings from step (1) was dried to a mass fraction of 4.5%. The cooled sintered material was crushed using an impact crusher, and then sieved and sized using an 8mm sieve. Coarse particles with a diameter greater than or equal to the sieve aperture size were used as porous magnesium silicate adsorbents, while fine particles smaller than the sieve aperture size were returned to the pre-grinding crushing process. The final porous magnesium silicate adsorbent had a specific surface area of ​​39.75 m². 2 / g, with good crystallinity.

[0057] Example 3

[0058] A method for preparing porous magnesium silicate-based adsorbents using tailings from laterite nickel ore smelting and magnesite tailings specifically includes the following steps:

[0059] (1) Insulation pre-reaction

[0060] The high-temperature laterite nickel ore smelting tailings (86.1% SiO2+MgO ​​by mass fraction) from the electric arc furnace at 1580℃ flowed into the heat preservation bin through the discharge port. Magnesite tailings (2.15% CaO+Al2O3 by mass fraction) containing 11% moisture by mass were dried using the waste heat of the rotary kiln. The dried magnesite tailings were transported by belt conveyor and feeder and mixed with the laterite nickel ore smelting tailings at a uniform speed according to a mass ratio of magnesite to laterite nickel ore of 1:1.5. The mixed material was heat-pre-reacted for 12.5 hours and then cooled to room temperature to obtain the reaction raw material.

[0061] (2) Fine grinding and activation

[0062] The reaction raw materials in step (1) are processed by a jaw crusher and a roller crusher to crush the product to a maximum particle size of 8 mm. The raw materials are then fed into a ball mill for fine grinding to obtain activated material. The activated material has a fineness of -325 mesh content of 92% (by mass fraction).

[0063] (3) Calcination and crystallization

[0064] The activated material is fed into the sintering machine via a feeder. The calcination and crystallization reaction temperature of the activated material in the sintering machine is 1350℃. The sintering machine uses pulverized coal with an ash content of 18% by mass as fuel. The sintering material is obtained after calcination and crystallization reaction of the activated material for 40 minutes.

[0065] (4) Crushing and granulation

[0066] The sintered material was cooled in an annular cooler at a rate of 40℃ / min, and discharged after cooling to 180℃. The residual heat from sintering was collected, and the moisture content of the magnesite tailings from step (1) was dried to a mass fraction of 3.8%. The cooled sintered material was crushed using an impact crusher, and then sieved and sized using a vibrating screen with a 12mm aperture. Coarse particles with a diameter greater than or equal to the screen aperture size were used as porous magnesium silicate adsorbent, while fine particles smaller than the screen aperture size were returned to the pre-grinding crushing process. The final porous magnesium silicate adsorbent had a specific surface area of ​​35.82 m². 2 / g, with good crystallinity.

[0067] Example 4

[0068] A method for preparing porous magnesium silicate-based adsorbents using tailings from laterite nickel ore smelting and magnesite tailings specifically includes the following steps:

[0069] (1) Insulation pre-reaction

[0070] The high-temperature laterite nickel ore smelting tailings (SiO2+MgO ​​total content of 91.1% by mass fraction) at 1600℃ in the electric arc furnace flowed into the heat preservation bin through the discharge port. Magnesite tailings containing 13% moisture by mass (CaO+Al2O3 total content of 2.73% by mass fraction) were dried using the waste heat of the rotary kiln. The dried magnesite tailings were transported by belt conveyor and feeder and mixed with the laterite nickel ore smelting tailings at a uniform speed according to the mass ratio of magnesite to laterite nickel ore of 1:2. The mixed material was heat-pre-reacted for 20 hours and then cooled to room temperature to obtain the reaction raw material.

[0071] (2) Fine grinding and activation

[0072] The reaction raw materials in step (1) are processed by a jaw crusher and a roller crusher to crush the product to a maximum particle size of 6 mm. The raw materials are then fed into a ball mill for fine grinding to obtain activated material. The activated material contains 95% -325 mesh (by mass fraction).

[0073] (3) Calcination and crystallization

[0074] The activated material is fed into the sintering machine via a feeder. The calcination and crystallization reaction temperature of the activated material in the sintering machine is 1280℃. The sintering machine uses pulverized coal with an ash content of 11% by mass as fuel. The sintering material is obtained after calcination and crystallization reaction of the activated material for 60 minutes.

[0075] (4) Crushing and granulation

[0076] The sintered material was cooled in an annular cooler at a rate of 30℃ / min, and discharged after cooling to 200℃. The residual heat from sintering was collected, and the moisture content of the magnesite tailings from step (1) was dried to a mass fraction of 4.9%. The cooled sintered material was crushed using an impact crusher, and then sieved and sized using a vibrating screen with a 20mm aperture. Coarse particles with a diameter greater than or equal to the screen aperture size were used as porous magnesium silicate adsorbent, while fine particles smaller than the screen aperture size were returned to the pre-grinding crushing process. The final porous magnesium silicate adsorbent had a specific surface area of ​​51.78 m². 2 / g, with good crystallinity.

[0077] Example 5

[0078] A method for preparing porous magnesium silicate-based adsorbents using tailings from laterite nickel ore smelting and magnesite tailings specifically includes the following steps:

[0079] (1) Insulation pre-reaction

[0080] The high-temperature laterite nickel ore smelting tailings (89.7% SiO2+MgO ​​by mass fraction) at 1540℃ in the electric arc furnace flowed into the heat preservation silo through the discharge port. Magnesite tailings (2.38% CaO+Al2O3 by mass fraction) containing 13.5% moisture by mass were dried using the waste heat of the rotary kiln. The dried magnesite tailings were transported by belt conveyor and feeder and mixed with the laterite nickel ore smelting tailings at a uniform speed according to a magnesite to laterite nickel ore mass ratio of 3:1. The mixed material was heat-pre-reacted for 15 hours and then cooled to room temperature to obtain the reaction raw material.

[0081] (2) Fine grinding and activation

[0082] The reaction raw materials in step (1) are processed by a jaw crusher and a roller crusher to crush the product to a maximum particle size of 10 mm. The raw materials are then fed into a ball mill for fine grinding to obtain activated material. The activated material contains 73% -325 mesh (by mass fraction).

[0083] (3) Calcination and crystallization

[0084] The activated material is fed into the sintering machine via a feeder. The calcination and crystallization reaction temperature of the activated material in the sintering machine is 1395℃. The sintering machine uses pulverized coal with an ash content of 18% by mass as fuel. The sintering material is obtained after calcination and crystallization reaction of the activated material for 40 minutes.

[0085] (4) Crushing and granulation

[0086] The sintered material was cooled in an annular cooler at a rate of 35℃ / min, and discharged after cooling to 120℃. The residual heat from sintering was collected, and the moisture content of the magnesite tailings from step (1) was dried to a mass fraction of 3.8%. The cooled sintered material was crushed using an impact crusher, and then sieved and sized using a vibrating screen with a 15mm aperture. Coarse particles with a diameter greater than or equal to the screen aperture size were used as porous magnesium silicate adsorbent, while fine particles smaller than the screen aperture size were returned to the pre-grinding crushing process. The final porous magnesium silicate adsorbent had a specific surface area of ​​39.82 m². 2 / g, with good crystallinity.

[0087] Example 6

[0088] A method for preparing porous magnesium silicate-based adsorbents using tailings from laterite nickel ore smelting and magnesite tailings specifically includes the following steps:

[0089] (1) Insulation pre-reaction

[0090] The high-temperature laterite nickel ore smelting tailings (with a total SiO2+MgO ​​content of 90.7% by mass fraction) at 1410℃ in the electric arc furnace flowed into the heat preservation silo through the discharge port. Magnesite tailings containing 15% moisture by mass (with a total CaO+Al2O3 content of 1.4% by mass fraction) were dried using the waste heat of the rotary kiln. The dried magnesite tailings were transported by belt conveyor and feeder and mixed with the laterite nickel ore smelting tailings at a uniform speed according to a magnesite to laterite nickel ore mass ratio of 5:1. The mixed material was heat-pre-reacted for 11 hours and then cooled to room temperature to obtain the reaction raw material.

[0091] (2) Fine grinding and activation

[0092] The reaction raw materials in step (1) are processed by a jaw crusher and a roller crusher to crush the product to a maximum particle size of 8.9 mm. The raw materials are then fed into a ball mill for fine grinding to obtain activated material. The activated material contains 82% -325 mesh (by mass fraction).

[0093] (3) Calcination and crystallization

[0094] The activated material is fed into the sintering machine via a feeder. The calcination and crystallization reaction temperature of the activated material in the sintering machine is 1360℃. The sintering machine uses pulverized coal with an ash content of 20% as fuel. The sintering material is obtained after calcination and crystallization reaction of the activated material for 46 minutes.

[0095] (4) Crushing and granulation

[0096] The sintered material was cooled in an annular cooler at a rate of 37℃ / min, and discharged after cooling to 194℃. After collecting the residual heat from sintering, the moisture content of the magnesite tailings from step (1) was dried to a mass fraction of 2.8%. The cooled sintered material was crushed using an impact crusher, and then sieved and sized using a vibrating screen with an 11mm sieve aperture. Coarse particles with a diameter greater than or equal to the sieve aperture size were used as porous magnesium silicate adsorbents, while fine particles with a diameter smaller than the sieve aperture size were returned to the pre-grinding crushing process. The final porous magnesium silicate adsorbent had a specific surface area of ​​48m². 2 / g, with good crystallinity.

[0097] Example 7

[0098] A method for preparing porous magnesium silicate-based adsorbents using tailings from laterite nickel ore smelting and magnesite tailings specifically includes the following steps:

[0099] (1) Insulation pre-reaction

[0100] The high-temperature laterite nickel ore smelting tailings (SiO2+MgO ​​total content of 95.6% by mass fraction) at 1600℃ in the electric arc furnace flowed into the heat preservation bin through the discharge port. Magnesite tailings containing 16% moisture by mass (CaO+Al2O3 total content of 1.7% by mass fraction) were dried using the waste heat of the rotary kiln. The dried magnesite tailings were transported by belt conveyor and feeder and mixed with the laterite nickel ore smelting tailings at a uniform speed according to the mass ratio of magnesite to laterite nickel ore of 2.4:1. The mixed material was kept at a high temperature for 7 hours for pre-reaction, and then cooled to room temperature to obtain the reaction raw material.

[0101] (2) Fine grinding and activation

[0102] The reaction raw materials in step (1) are processed by a jaw crusher and a roller crusher to crush the product to a maximum particle size of 9.1 mm. The raw materials are then fed into a ball mill for fine grinding to obtain activated material. The activated material contains 68% -325 mesh (by mass fraction).

[0103] (3) Calcination and crystallization

[0104] The activated material is fed into the sintering machine via a feeder. The calcination and crystallization reaction temperature of the activated material in the sintering machine is 1350℃. The sintering machine uses coal powder with an ash content of 20% by mass as fuel. The sintering material is obtained after calcination and crystallization reaction of the activated material for 30 minutes.

[0105] (4) Crushing and granulation

[0106] The sintered material was cooled in an annular cooler at a rate of 16℃ / min, and discharged after cooling to 190℃. After collecting the residual heat from sintering, the moisture content of the magnesite tailings from step (1) was dried to a mass fraction of 1.9%. The cooled sintered material was crushed using an impact crusher, and then sieved and sized using a vibrating screen with a 10mm sieve aperture. Coarse particles with a diameter greater than or equal to the sieve aperture size were used as porous magnesium silicate adsorbents, while fine particles with a diameter smaller than the sieve aperture size were returned to the pre-grinding crushing process. The final porous magnesium silicate adsorbent had a specific surface area of ​​46m². 2 / g, with good crystallinity.

[0107] Example 8

[0108] A method for preparing porous magnesium silicate-based adsorbents using tailings from laterite nickel ore smelting and magnesite tailings specifically includes the following steps:

[0109] (1) Insulation pre-reaction

[0110] The high-temperature laterite nickel ore smelting tailings (SiO2+MgO ​​total content of 86.5% by mass fraction) at 1510℃ in the electric arc furnace flowed into the heat preservation bin through the discharge port. Magnesite tailings containing 9% moisture by mass (CaO+Al2O3 total content of 1.9% by mass fraction) were dried using the waste heat of the rotary kiln. The dried magnesite tailings were transported by belt conveyor and feeder and mixed with the laterite nickel ore smelting tailings at a uniform speed according to the mass ratio of magnesite to laterite nickel ore of 4:1. The mixed material was kept at a heat preservation temperature for 6 hours for pre-reaction, and then cooled to room temperature to obtain the reaction raw material.

[0111] (2) Fine grinding and activation

[0112] The reaction raw materials in step (1) are processed by a jaw crusher and a roller crusher to crush the product to a maximum particle size of 7 mm. The raw materials are then fed into a ball mill for fine grinding to obtain activated material. The activated material contains 85% -325 mesh (by mass fraction).

[0113] (3) Calcination and crystallization

[0114] The activated material is fed into the sintering machine via a feeder. The calcination and crystallization reaction temperature of the activated material in the sintering machine is 1200℃. The sintering machine uses pulverized coal with an ash content of 25% as fuel. The sintering material is obtained after calcination and crystallization reaction of the activated material for 53 minutes.

[0115] (4) Crushing and granulation

[0116] The sintered material was cooled in an annular cooler at a rate of 22℃ / min, and discharged after cooling to 115℃. After collecting the residual heat from sintering, the moisture content of the magnesite tailings from step (1) was dried to a mass fraction of 3.7%. The cooled sintered material was crushed using an impact crusher, and then sieved and sized using a vibrating screen with a 12mm sieve aperture. Coarse particles with a diameter greater than or equal to the sieve aperture size were used as porous magnesium silicate adsorbents, while fine particles with a diameter smaller than the sieve aperture size were returned to the pre-grinding crushing process. The final porous magnesium silicate adsorbent had a specific surface area of ​​37m². 2 / g, with good crystallinity.

Claims

1. A method for preparing porous magnesium silicate-based adsorbents using tailings from laterite nickel ore smelting and magnesite tailings, characterized in that, Specifically, the following steps are included: (1) Insulation pre-reaction The high-temperature laterite nickel ore smelting tailings in the electric arc furnace flow into the heat preservation bin through the discharge port. The magnesite tailings containing a certain amount of moisture are dried using the waste heat of the rotary kiln. The dried magnesite tailings are transported by belt and feeder and mixed with the laterite nickel ore smelting tailings at a certain ratio and at a uniform speed. The mixed material is then heat-pre-reacted and cooled to room temperature to obtain the reaction raw material. (2) Fine grinding and activation The raw materials in step (1) are processed by a jaw crusher and a roller crusher to be crushed to a certain particle size. Then, the raw materials are fed into a ball mill and ground to a certain fineness to obtain activated material. (3) Calcination and crystallization The activated material is fed into the sintering machine via a feeder. The sintering machine uses pulverized coal as fuel. After the activated material undergoes a roasting and crystallization reaction for a certain period of time, sintered material is obtained. (4) Crushing and granulation The sintered material is cooled in an annular cooler. The residual heat from sintering is collected and used to dry the magnesite tailings in step (1). The cooled sintered material is crushed by an impact crusher and then screened and sized by a vibrating screen. The coarse particles are porous magnesium silicate adsorbents, and the fine particles are returned to the crushing process before fine grinding.

2. The method for preparing porous magnesium silicate-based adsorbents using laterite nickel ore smelting tailings and magnesite tailings according to claim 1, characterized in that, In step (1), the temperature of the tailings from the high-temperature laterite nickel ore smelting is 1400-1600℃; by mass fraction, the content of SiO2+MgO, the main component of the tailings from the laterite nickel ore smelting, is ≥85%, the total content of CaO+Al2O3 in the magnesite is ≤3%, and the moisture content of the magnesite tailings is ≤16%.

3. The method for preparing porous magnesium silicate-based adsorbents using laterite nickel ore smelting tailings and magnesite tailings according to claim 1, characterized in that, In step (1), the mass ratio of magnesite to laterite nickel ore is (0.5-6):

1.

4. The method for preparing porous magnesium silicate-based adsorbents using laterite nickel ore smelting tailings and magnesite tailings according to claim 1, characterized in that, In step (1), the pre-reaction time of the mixture is 6 to 24 hours.

5. The method for preparing porous magnesium silicate-based adsorbents using laterite nickel ore smelting tailings and magnesite tailings according to claim 1, characterized in that, In step (2), after the reaction raw materials pass through a jaw crusher and a roller crusher, the maximum particle size of the crushed product is 6-10 mm; after ball milling, the fineness of the activated material is -325 mesh, accounting for 65%-98% by mass fraction.

6. The method for preparing porous magnesium silicate-based adsorbents using laterite nickel ore smelting tailings and magnesite tailings according to claim 1, characterized in that, In step (3), the ash content in the pulverized coal is ≤25% by mass.

7. The method for preparing porous magnesium silicate-based adsorbents using laterite nickel ore smelting tailings and magnesite tailings according to claim 1, characterized in that, In step (3), the calcination and crystallization reaction temperature of the activated material in the sintering machine is 1200-1420℃, and the time is 20-60min.

8. The method for preparing porous magnesium silicate-based adsorbents using laterite nickel ore smelting tailings and magnesite tailings according to claim 1, characterized in that, In step (4), the sintering material is cooled in an annular cooler at a rate of 15-40℃ / min. After cooling to 100-200℃, it is naturally cooled in the air. The residual heat from sintering is collected and the magnesite tailings raw material is dried until the moisture content is less than 5%.

9. The method for preparing porous magnesium silicate-based adsorbents using laterite nickel ore smelting tailings and magnesite tailings according to claim 1, characterized in that, In step (4), the screen size of the vibrating screen is 8-20mm.

10. A method for preparing porous magnesium silicate-based adsorbents using laterite nickel ore smelting tailings and magnesite tailings according to claim 1, characterized in that, In step (4), the specific surface area of ​​the magnesium silicate adsorbent is 20–55 m². 2 / g.

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