Solid waste recovery treatment method of stainless steel smelting system

Abstract

The invention discloses an iron-containing circulating material and solid waste recovery treatment method for a stainless steel smelting system, which comprises the following components in percentage by weight: 0.5-0.6% of nickel, 2-3% of chromium, 35-45% of iron and 3-5% of silicon dioxide. The specific structure and proportion control method for optimizing and proportioning circulating materials containing iron, nickel, chromium and the like and solid waste ensures that sintered ore reaches specific chemical component indexes, and a Lurgi belt type sintering machine is adopted; and the specific numerical range and the control method of key parameters such as the thickness of a sintered material layer, the thickness of a grate-layer material, the ignition temperature, the ignition negative pressure, the large flue negative pressure, the sintering time, the final temperature and the cooling time are strictly controlled, so that the strength of the sintered ore is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of recycling of iron-containing solid wastes in steel plants, and particularly to a method for recycling iron-containing circulating materials and solid wastes in a stainless steel smelting system. Background Art

[0002] The recycling of solid wastes in iron and steel enterprises is a crucial link, which not only helps to reduce environmental pollution, but also enables the effective utilization of resources and sustainable development. During the iron and steel production process, a large amount of solid waste is generated, such as dust from the tapping hole of ironmaking, dust from steelmaking, pickling sludge, etc. If these solid wastes are not properly treated, they will not only occupy land, but also may cause harm to the environment and human health. The effective recycling and utilization of these iron, nickel, and chromium-containing solid wastes can reduce the raw material consumption and resource loss of iron and steel enterprises, reduce production and slag discharge costs and increase revenues, and effectively control the environmental pollution caused by iron-containing industrial solid wastes.

[0003] In the prior art, the wet process is used to recycle valuable metals from industrial solid wastes. The process flow is long, the recycling cost is high, the economy is poor, and the slag produced during the disposal process does not meet the harmless requirements. For the above-mentioned iron-containing solid wastes, such as dust, dry recycling is adopted, and reasonable batching is carried out, and sintered ore for stainless steel smelting is produced through the sintering process, which has high economic and environmental benefits. A reasonable raw material ore blending structure and sintering process are the keys to obtaining high-quality sintered ore. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is: to provide a method for recycling iron-containing circulating materials and solid wastes in a stainless steel smelting system, and solve the problems raised in the above background art.

[0005] The above technical problem is solved by the following technical solutions: The present invention provides a method for recycling iron-containing circulating materials and solid wastes in a stainless steel smelting system, including obtaining pellet balls from pickling sludge (untreated iron-containing circulating materials) through a rotary dryer;

[0006] Pre-mixing and ore blending of the iron-containing circulating materials in the stainless steel smelting system to obtain a pre-mixed material;

[0007] The pre-mixed material is evenly mixed with quicklime powder and coke powder, and is mixed evenly through a cylindrical granulating mixer to obtain a uniformly mixed pellet sintering material. The uniformly mixed pellet sintering material is sintered by a Lurgi-type belt sintering machine to obtain sintered ore, realizing the recycling of solid wastes in the stainless steel smelting system;

[0008] Among them, calculated by the mass percentage of the iron-containing circulating materials in the stainless steel smelting system, it includes nickel: 0.5 - 0.6%, chromium: 2 - 3%, iron: 35 - 45%, silicon dioxide: 3 - 5%, and the balance of other chemical components is 46.4 - 60.6%.

[0009] In a preferred embodiment of the solid waste recycling and treatment method of the present invention: the water content of the material balls is 20-25%.

[0010] In a preferred embodiment of the solid waste recycling and treatment method of the present invention: the thickness of the mixed and pelletized sintering material is 800 mm.

[0011] In a preferred embodiment of the solid waste recycling and treatment method of the present invention: the thickness of the bed material for the mixed and pelletized sintering material (the gangue screened out from the laterite nickel ore, with a particle size < 30 mm after crushing) is 40 mm.

[0012] In a preferred embodiment of the solid waste recycling and treatment method of the present invention: the ignition temperature for sintering is 1000-1100 °C, and the ignition negative pressure is 5 Kpa.

[0013] In a preferred embodiment of the solid waste recycling and treatment method of the present invention: the negative pressure of the main flue for sintering is controlled to 9-11 Kpa.

[0014] In a preferred embodiment of the solid waste recycling and treatment method of the present invention: the sintering time is 50-60 min.

[0015] In a preferred embodiment of the solid waste recycling and treatment method of the present invention: the end temperature for sintering is 310-350 °C.

[0016] In a preferred embodiment of the solid waste recycling and treatment method of the present invention: the cooling time of the annular cooler during sintering is 50-60 min.

[0017] The beneficial effects of the present invention are as follows: By improving the sintering process steps and optimizing key parameters such as sintering temperature, time, and atmosphere, the materials can fully react during the sintering process, thereby improving the strength and wear resistance of the products. There are environmental and economic benefits, and it has broad application prospects in the fields of industrial solid waste treatment and metal resource recovery. By realizing the harmless disposal of industrial solid waste, the environmental pressure is effectively reduced, making a positive contribution to sustainable development. At the same time, by comprehensively recycling valuable metal resources, the production cost of enterprises can also be reduced, improving economic efficiency. Specific Embodiments

[0018] In order to enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below in conjunction with specific embodiments.

[0019] The terms used in the present invention are those general terms that are currently widely used in the art in consideration of the functions of the present invention. However, these terms may vary according to the intention of those of ordinary skill in the art, precedents, or new technologies in the art. In addition, specific terms may be selected by the applicant, and in such cases, their detailed meanings will be described in the detailed description of the present invention. Therefore, the terms used in the specification should not be construed as simple names, but based on the meanings of the terms and the overall description of the present invention.

[0020] The reference for the detection method of the conversion stock index in the present invention is: GB / T 24531-2024 (Determination method for drum strength of sinter and pellet).

[0021] The reference for the detection method of the screening index of sinter is:

[0022] 1. GB / T 10322.1 (Sampling and sample preparation methods for iron ores).

[0023] 2. GB / T 10322.2 (Experimental methods for evaluating the quality fluctuation of iron ores)

[0024] Example 1

[0025] This example provides a method for recycling and treating iron-containing circulating materials and solid wastes in a stainless steel smelting system, specifically as follows:

[0026] 1) Pickling sludge (containing iron-containing circulating materials to be treated in the stainless steel smelting system) is dried by a rotary dryer to obtain material balls with a water content of <25%.

[0027] 2) The material balls are pre-mixed and proportioned for ore blending. The ore blending requirements are such that, calculated by mass percentage of the premixed material, the nickel content is 0.545%, the chromium content is 2.637%, the iron content is 42.352%, the silicon dioxide content is 3.604%, and the balance of other chemical components is 51.162% to obtain a premixed material.

[0028] 3) The premixed material with a content of 91.4% is uniformly mixed with a flux (quicklime powder) with a content of 4.2% and a fuel (coke powder) with a content of 5.4%, and is homogenized by a cylindrical granulating mixer to obtain a homogeneous ball sintering material.

[0029] 4) The homogenized ball sintering material is sintered by a Lurgi-type belt sintering machine. Among them, the sintering material layer is controlled at 800 mm, the thickness of the bedding material is controlled at 40 mm, the ignition temperature is controlled at 1079 °C, the ignition negative pressure is controlled at 5 Kpa, the negative pressure of the main flue is controlled at 10 Kpa, the sintering time is controlled at 59.3 min, the end point temperature is controlled at 334.8 °C, and the cooling time of the annular cooler is controlled at 59.3 min. After sintering, sintered ore is obtained, realizing the recycling and treatment of solid wastes in the stainless steel smelting system.

[0030] The component percentages of the sintered ore obtained in this example were measured as follows: nickel 0.72%, chromium 2.97%, iron 47.63%, silicon dioxide 7.62%, basicity 1.48. The strength and particle size composition of the obtained sintered ore are shown in Table 1 below.

[0031] Table 1

[0032]

[0033] The drum index of traditional nickel sintered ore is in the range of 52 - 60% (literature reference: "Experimental Study on the Optimization of Laterite Nickel Ore Sintering Process", Sintering and Pelletizing, August 2022, Vol. 47, No. 4). As can be seen from Table 1, the drum index of the sintered ore of the present invention reaches 65.44%, significantly improving the service performance of the product.

[0034] Example 2

[0035] This example provides a method for recycling iron-containing recycled materials and solid waste in a stainless steel smelting system, specifically as follows:

[0036] 1) Pickling sludge (containing iron-containing recycled materials to be treated in the stainless steel smelting system) is dried by a rotary dryer to obtain feed pellets with a H₂O content < 25%;

[0037] 2) The feed pellets are pre-mixed and proportioned. The proportioning requirements are such that, based on the mass percentage of the premix, the nickel content is 0.58%, the chromium content is 2.483%, the iron content is 41.719%, the silicon dioxide content is 3.103%, and the remaining other chemical components are 52.115% for pre-mixing and proportioning to obtain a premix;

[0038] 3) The premix content of 92.3% is uniformly mixed with a flux (quicklime powder) content of 4.1% and a fuel (coke powder) content of 3.4% to obtain a uniformly mixed ball sintering material;

[0039] 4) The uniformly mixed ball sintering material is sintered by a Lurgi-type belt sintering machine. Among them, the sintering material layer is controlled at 800 mm, the thickness of the bedding material is controlled at 40 mm, the ignition temperature is controlled at 1084 °C, the ignition negative pressure is controlled at 5 Kpa, the negative pressure of the main flue is controlled at 10 Kpa, the sintering time is controlled at 54.7 min, the end point temperature is controlled at 315.2 °C, and the cooling time of the annular cooler is controlled at 54.7 min. After sintering, sintered ore is obtained, realizing the recycling of solid waste in the stainless steel smelting system;

[0040] The component percentages of the sintered ore obtained in this example were measured as follows: nickel 0.72%, chromium 2.97%, iron 47.63%, silicon dioxide 7.62%, basicity 1.58. The strength and particle size composition of the obtained sintered ore are shown in Table 2 below.

[0041] Table 2

[0042]

[0043] The drum index of traditional nickel sinter is in the range of 52 - 60% (literature reference: "Sintering and Pelletizing", Vol. 47, No. 4, August 2022, "Experimental Study on Optimization of Laterite Nickel Ore Sintering Process"). As can be seen from Table 2, the drum index of the sinter of the present invention reaches 64.50%, significantly improving the service performance of the product.

[0044] Example 3

[0045] This example provides a method for recycling and treating iron-containing recycled materials and solid wastes in a stainless steel smelting system, specifically as follows:

[0046] 1) Pickling sludge (containing iron-containing recycled materials to be treated in the stainless steel smelting system) is dried by a rotary dryer to obtain material balls with a water content of < 25%;

[0047] 2) The iron-containing recycled materials in the stainless steel smelting system: nickel is 0.589%, chromium is 2.824%, iron is 39.34%, silicon dioxide is 3.469%, and the remaining other chemical components are 54.078% are pre-mixed and proportioned to obtain a premix;

[0048] 3) The premix content of 91.7% is uniformly mixed with the flux (quicklime powder) content of 3.8% and the fuel (coke powder) content of 4.5% to obtain a uniformly mixed ball sintering material;

[0049] 4) The uniformly mixed ball sintering material is sintered by a Lurgi-type belt sintering machine. Among them, the sintering material layer is controlled at 800 mm, the thickness of the bedding material is controlled at 40 mm, the ignition temperature is controlled at 1072 °C, the ignition negative pressure is controlled at 5 Kpa, the negative pressure of the main flue is controlled at 10 Kpa, the sintering time is controlled at 56.23 min, the end point temperature is controlled at 333.7 °C, and the cooling time of the annular cooler is controlled at 56.23 min. After sintering, sintered ore is obtained, realizing the recycling and treatment of solid wastes in the stainless steel smelting system;

[0050] The component percentages of the sintered ore obtained in this example are measured as follows: nickel is 0.72%, chromium is 2.97%, iron is 47.63%, silicon dioxide is 7.62%, and the basicity is 1.57. The strength and particle size composition of the obtained sintered ore are as shown in Table 3 below.

[0051] Table 3

[0052]

[0053] The drum index of traditional nickel sinter is in the range of 52 - 60% (literature reference: "Experimental Study on the Optimization of Laterite Nickel Ore Sintering Process", Sintering and Pelletizing, Vol. 47, No. 4, August 2022). As can be seen from Table 2, the drum index of the sinter ore of the present invention reaches 61.58%, significantly improving the service performance of the product.

[0054] Comparative Example 1

[0055] This comparative example provides sintering with different initial material contents for comparison. The differences from Example 1 are specifically as follows:

[0056] 1) The pickling sludge (containing iron-containing recycled materials to be treated in the stainless steel smelting system) is dried by a rotary dryer to obtain feed pellets with a water content of < 25%.

[0057] 2) The feed pellets are pre-mixed and proportioned to obtain a premixed material. The proportioning requirements are such that, calculated by the mass percentage of the premixed material, the nickel content is 0.414%, the chromium content is 1.397%, the iron content is 21.64%, the silica content is 1.88%, and the remaining other chemical components are 84.027% for pre-mixing and proportioning to obtain the premixed material.

[0058] 3) The premixed material content is 90.1%, the flux (quicklime powder) content is 4.9%, and the fuel (coke powder) content is 5% are uniformly mixed to obtain a uniformly mixed pellet sintering material.

[0059] 4) The uniformly mixed pellet sintering material is sintered by a Lurgi-type belt sintering machine to obtain sinter ore. The Lurgi-type belt sintering machine is used to sinter the material pellets to obtain sinter ore. The sintering layer is controlled at 800 mm, the thickness of the bedding layer is controlled at 40 mm, the ignition temperature is controlled at 1072 °C, the ignition negative pressure is controlled at 5 Kpa, the negative pressure of the main flue is controlled at 10 Kpa, the sintering time is controlled at 56.23 min, the end point temperature is controlled at 333.7 °C, and the cooling time of the annular cooler is controlled at 56.23 min to obtain sinter ore, realizing the solid waste recycling treatment of the stainless steel smelting system.

[0060] After sintering, the component percentages of the sinter ore are obtained as follows: nickel is 0.62%, chromium is 2.64%, iron is 31.57%, silica is 6.26%, and the basicity is 1.62 times. The strength and particle size composition of the obtained sinter ore are as shown in the following table.

[0061]

[0062] It can be seen that when the mass composition of the raw material is less than the established range, the required mass percentage of the sintered ore cannot be obtained: nickel ≥ 0.7%, chromium ≥ 2.8%, iron ≥ 47.5%, silicon dioxide ≈ 6.00-7.00%, and basicity R ≈ 1.50 ± 0.15 times; at the same time, the drum strength is 54.24%, which is located in the 52-60% range of the drum index of traditional nickel sintered ore. The material with a mass composition of the raw material greater than the established range is extremely difficult to obtain in actual production. Therefore, the raw material mass composition is nickel: 0.4-0.6%, chromium: 1-3%, iron: 35-45%, silicon dioxide: 3-5%, and the balance of other chemical components is 46.4-60.6%. The sintered ore can meet the required sintered ore quality requirements.

[0063] In addition, during the experiment, when the circulating material distribution structure, raw material particle size, moisture, material layer thickness, ignition temperature, ignition negative pressure, and sintering end temperature were basically the same, the flue negative pressure was adjusted to 12Kpa and the sintering time was less than 50min. At this time, the sintering speed was too fast, the high-temperature reaction time during the sintering process was shortened, and the liquid phase generation and consolidation process could not be fully carried out, which ultimately led to an increase in porosity, which would cause the internal structure of the sintered ore to be not dense enough and the porosity to increase, thereby affecting the drum strength and reducing the output.

[0064] On the premise that the circulating material distribution structure, raw material particle size, moisture, material layer thickness, ignition temperature, ignition negative pressure, large flue negative pressure, and sintering end temperature are basically the same, the large flue negative pressure is adjusted to 8Kpa, and the sintering time is greater than 60min. At this time, when the negative pressure is too low, resulting in insufficient ventilation capacity, the waste gas in the material layer cannot be discharged in time, which ultimately affects the heat and oxygen transfer efficiency, resulting in excessive densification of the sintered ore and too close bonding between the particles, thereby increasing the sintering resistance, further reducing the sintering speed, reducing the utilization coefficient of the sintering machine, and reducing output.

[0065] After chemical composition analysis, the specific structure and proportion control method of the recycled materials and solid waste containing iron, nickel, chromium, etc. are optimized according to the chemical composition requirements of the sintered ore to ensure that the sintered ore meets the specific chemical composition indicators.

[0066] A Lurgi belt sintering machine is used, and the specific numerical ranges and control methods of key parameters such as sintering material layer thickness, base material thickness, ignition temperature, ignition negative pressure, large flue negative pressure, sintering time, end point temperature, cooling time, etc. are strictly controlled to improve the strength of the sintered ore.

[0067] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A solid waste recovery and treatment method for a stainless steel smelting system, characterized by: Pickling sludge containing iron-containing circulating material to be processed from a stainless steel smelting system is passed through a rotary dryer to obtain pellets; The pellets are premixed with ore to obtain a premix, wherein the premix comprises, by mass percentage, 0.5-0.6% nickel, 2-3% chromium, 35-45% iron, 3-5% silicon dioxide, and the balance of other chemical components is 46.4-60.6%; The premix with a content of 90% to 93% is mixed with a quicklime powder content of 3% to 5% and a coke powder content of 4% to 5% by a cylindrical granulating mixer to obtain a mixed ball sintered material. The mixed ball sintered material is sintered in a Lurgi belt sintering machine to obtain a sintered ore, thereby realizing the solid waste recovery and treatment of the stainless steel smelting system.

2. The solid waste recycling method according to claim 1, characterized in that: The moisture content of the pellets is 20-25%.

3. The solid waste recycling method according to claim 2, characterized in that: The thickness of the mixed ball sintered material is 800mm.

4. The solid waste recycling method according to claim 3, characterized in that: The thickness of the base material of the mixed ball sintering material is 40 mm, wherein the base material is the gangue sieved from the laterite nickel ore and crushed to a particle size of less than 30 mm.

5. The solid waste recycling method according to claim 1, characterized in that: The ignition temperature of sintering is 1000-1100°C, and the ignition negative pressure is 5Kpa.

6. The solid waste recycling method according to claim 5, characterized in that: The negative pressure of the sintering flue is controlled to 9-11Kpa.

7. The solid waste recycling method according to claim 6, characterized in that: The sintering time is 50 to 60 minutes.

8. The solid waste recycling method according to claim 7, characterized in that: The final temperature of sintering is 310-350°C.

9. The solid waste recycling method according to claim 8, characterized in that: During sintering, the cooling time of the ring cooler is 50 to 60 minutes.

10. The solid waste recycling method according to claim 9, characterized in that: In terms of mass percentage of the sintered ore, the nickel content is ≥0.7%, the chromium content is ≥2.8%, the iron content is ≥47.5%, the silicon dioxide content is 6.00-7.00%, and the basicity R is calcium monoxide / silicon dioxide=1.35-1.65.

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