Black and nonferrous metal solid waste co-treatment and utilization method

Abstract

The invention discloses a black and nonferrous metal solid waste co-treatment and utilization method, which comprises the following steps: directly mixing wet-based waste acid regeneration impurity-removal sludge with red mud, and neutralizing and eliminating corrosivity by utilizing the acid-base characteristics of the wet-based waste acid regeneration impurity-removal sludge and the red mud; and drying the mixed material at 150-200 DEG C, adding 7-15% of carbon and 2-5% of an adhesive, grinding until the particle size is less than 0.1 mm, adding 4-8% of water, pressing into balls, drying green balls, roasting at 1150-1200 DEG C, cooling, and feeding into a blast furnace for smelting. The TFe content of the product pellets is larger than or equal to 70.78%, the blast furnace material standard is met, AlO in the red mud is converted into high-quality granulated slag, and the quality coefficient is 1.7-2.0. The method realizes safe and high-quality utilization of two types of solid wastes, reduces land occupation, and has good economic and social benefits.

Description

Technical Field

[0001] This invention relates to the field of metal solid waste treatment technology, specifically a method for the co-processing and utilization of ferrous and non-ferrous metal solid waste. Background Technology

[0002] Wastewater generated from the acid pickling of steel strips in cold rolling mills of ferrous metal smelting enterprises undergoes a series of chemical reactions followed by solid-liquid separation. The liquid from plate and frame filter press separation is then processed using a spray roasting process to produce regenerated acid and iron oxide red. The resulting sludge, after impurity removal, has a high iron content, a pH of 2-4, and strong acid corrosiveness, and is generally disposed of via landfill, which is not only land-consuming and costly but also wastes ferrous resources. Red mud, the solid waste generated from the Bayer process of alumina production in non-ferrous metals, has a high alkaline content and a pH of 10-13, classifying it as strongly alkaline industrial waste. In 2024, my country added 115 million tons of red mud, bringing the cumulative stockpiled amount to over 1.5 billion tons. Landfilling or stockpiling occupies limited land resources, causes significant pollution and harm to the ecological environment, and hinders the sustainable development of the industry.

[0003] Existing waste acid regeneration sludge treatment technologies mainly rely on single roasting and dechlorination. Due to the high acidity of the waste acid regeneration sludge and the corrosive substances generated during roasting, equipment corrosion is unavoidable, leading to severe equipment damage and environmental harm. In terms of co-processing and utilization technologies for red mud from ferrous and non-ferrous metal solid waste, the focus is mainly on the co-processing and utilization of red mud with raw materials and auxiliary materials for iron and steel smelting, and red mud with lime or other alkaline solid wastes. This invention provides a method for the co-processing and utilization of waste acid regeneration sludge from ferrous metal solid waste and red mud from non-ferrous metal solid waste. Based on the characteristics of the two substances, the wet basis of the two substances is directly mixed to eliminate corrosivity, followed by pelletizing and roasting to increase the TFe content for use as blast furnace iron-containing material. This allows for the high-quality application of ferrous elements in both substances, while the high Al2O3 content in the red mud is converted into granulated blast furnace slag. Summary of the Invention

[0004] The purpose of this invention is to provide a method for the co-processing and utilization of ferrous and non-ferrous metal solid waste, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for the co-processing and utilization of ferrous and non-ferrous metal solid waste, comprising the following steps:

[0006] S1: Mix wet-based waste acid regeneration sludge and wet-based red mud in their natural state, with a weight ratio of (4:1) to (17:3) to obtain a mixture; S2: Dry the mixture at 150-200℃, then add 7-15% carbon source and 2-5% binder by weight, and grind them together until the particle size is <0.1mm to obtain powder; S3: Add 4-8% water by weight to the powder, stir, and press it into pellets; S4: Dry the pellets at 100℃, calcine them at 1150-1200℃, cool them, and send them into a blast furnace for smelting. The waste residue is separated and water-cooled to obtain granulated blast furnace slag.

[0007] Preferably, the waste acid regeneration sludge has a moisture content of 45%, and the dry basis content of TFe is 42-50 wt% and Cl content is 7-31 wt%; the red mud has a moisture content of 85%, and the dry basis content of TFe is 19-22 wt%, Al2O3 is 15-19 wt%, CaO is 16-21 wt%, MgO is 0.3-0.8 wt%, SiO2 is 8-13 wt%, TiO2 is 5-8 wt%, MnO is 0.1-0.3 wt%, and Na2O2 is 8 wt%.

[0008] Preferably, in step S2, the carbon source is pulverized coal commonly used in blast furnaces, and the binder is bentonite or a mixture of bentonite and corn starch.

[0009] Preferably, in step S4, the roasting is carried out in a microwave roasting oven for a roasting time of 30-60 minutes.

[0010] Preferably, in step S4, the TFe content of the pellets reaches more than 70% after calcination and cooling, and the compressive strength is greater than 2000N.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0012] 1. Eliminate corrosion and reduce equipment wear.

[0013] This invention utilizes the acid-base properties of waste acid regeneration sludge (acidic, pH 2-4) and red mud (alkaline, pH 10-13) to achieve a neutralization reaction through direct wet mixing. This eliminates the strong corrosiveness of the two solid wastes at the source, avoids the corrosion problem of acidic substances on equipment in traditional single roasting treatment, significantly extends the service life of equipment, and reduces operation and maintenance costs.

[0014] 2. High-quality utilization of ferrous resources to enhance the value of raw materials.

[0015] After co-processing, the total iron content (TFe) of the pellets can reach over 70.78%, which is superior to the chemical composition requirements of GB / T 276924-2024 "Iron Pelletizing Ore" and fully meets the raw material standards for blast furnace ironmaking. The iron content in both solid wastes is maximized, solving the problem of iron resource waste caused by traditional landfilling or inefficient treatment, and achieving a high-quality transformation of "solid waste into resources."

[0016] 3. Optimize the quality of waste residue and expand secondary utilization pathways.

[0017] The high Al2O3 content in red mud is transformed into granulated blast furnace slag during blast furnace smelting. Its quality coefficient (CaO + MgO + Al2O3) / (SiO2 + TiO2 + MnO) reaches 1.7~2.0, which is higher than the ≥1.2 required by GB / T 203-2008. It can be directly used as a high-quality cement admixture or building material raw material, thereby enhancing the economic value of waste slag.

[0018] 4. Reduce solid waste stockpiling and lower environmental risks.

[0019] This method enables the large-scale co-processing of ferrous and non-ferrous metal solid waste, significantly reducing the need for landfilling or stockpiling of waste acid sludge and red mud, lowering the risk of ecological pollution from land resource occupation and leakage of heavy metals and acidic and alkaline substances, and contributing to the sustainable development of the industry. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the co-processing of ferrous and non-ferrous metal solid waste in this invention. Detailed Implementation

[0021] 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.

[0022] This invention provides a method for the co-processing and utilization of ferrous and non-ferrous metal solid waste. Specifically, wet-based waste acid regeneration and impurity removal sludge is mixed evenly with red mud. The mixture is dried at 150-200°C, and then 7-15% carbon and 2-5% binder are added and ground together to a particle size of <0.1mm. Then, 4-8% water is added to press the pellets into balls. The green pellets are dried, calcined at 1150-1200°C, cooled, and then added to a blast furnace for utilization.

[0023] The waste acid regeneration sludge has a water content of 45%, and the dry basis contains 42-50 wt% TFe and 7-31 wt% Cl. The red mud has a water content of 85%, and the dry basis contains 19-22 wt% TFe, 15-19 wt% Al2O3, 16-21 wt% CaO, 0.3-0.8 wt% MgO, 8-13 wt% SiO2, 5-8 wt% TiO2, 0.1-0.3 wt% MnO, and 8 wt% Na2O.

[0024] To facilitate understanding of the above technical methods, the following embodiments are provided:

[0025] Example 1

[0026] a. Wet-based waste acid regeneration and impurity removal sludge and red mud are placed in a mixing mixer at a weight ratio of 4:1 and mixed evenly;

[0027] b. Place the mixture in an oven and dry at 150°C;

[0028] c. Place the dried waste acid regeneration sludge and red mud mixture, 7% of the mixture's weight of coal powder, and 3% of the mixture's weight of bentonite into a ball mill. After ball milling for 20 minutes, pass the mixture through a 0.1 mm sieve. Continue ball milling the material remaining on the sieve until it is less than 0.1 mm.

[0029] d. Put the ball-milled powder into a mixer, add water while mixing, and stop adding water when the amount of water reaches 5% of the powder. Continue mixing for 5 minutes.

[0030] e. Put the powder mixed with water into a briquetting machine and press it into briquettes under 100t pressure. After drying the raw briquettes at 100℃, put them into a microwave baking oven and bake them at 1150℃ for 30 minutes, then cool them to 25℃.

[0031] f. In step e above, the pellets have a TFe content of 70.78% and a compressive strength of 2019 N. The pellets are placed in the silo and conveyed to the top of the blast furnace by belt conveyor, where they are smelted together with other materials in the blast furnace.

[0032] Example 2:

[0033] a. Wet-based waste acid regeneration and impurity removal sludge and red mud are placed into a mixing mixer at a weight ratio of 17:3 and mixed evenly;

[0034] b. Place the mixture in an oven and dry at 200°C;

[0035] c. Place the dried waste acid regeneration sludge and red mud mixture, 10% of the mixture weight of coal powder, 4% of the mixture weight of bentonite and corn starch into a ball mill, ball mill for 30 minutes, and then pass through a 0.1 mm sieve. Continue ball milling the material remaining on the sieve until it is less than 0.1 mm.

[0036] d. Put the ball-milled powder into a mixer, add water while mixing, and stop adding water when the amount of water reaches 8% of the powder. Continue mixing for 8 minutes.

[0037] e. Place the powder mixed with water into a briquetting machine and press it into briquettes under 100t pressure. After drying the raw briquettes at 100℃, place them in a microwave baking oven and bake at 1175℃ for 30 minutes, then cool to 25℃.

[0038] f. In step e above, the pellets have a TFe content of 70.82% and a compressive strength of 2210N. The pellets are placed in the silo and conveyed to the top of the blast furnace by belt conveyor, where they are smelted together with other materials in the blast furnace.

[0039] Example 3:

[0040] Wet-based waste acid regeneration and impurity removal sludge and red mud are placed into a mixing mixer at a weight ratio of 17:3 and mixed evenly.

[0041] b. Place the mixture in an oven and dry at 200°C;

[0042] c. Place the dried waste acid regeneration sludge and red mud mixture, 15% of the mixture's weight of coal powder, 5% of the mixture's weight of bentonite, and corn starch into a ball mill. After ball milling for 40 minutes, pass the mixture through a 0.1mm sieve. Continue ball milling the material remaining on the sieve until it is less than 0.1mm.

[0043] d. Put the ball-milled powder into a mixer, add water while mixing, and stop adding water when the amount of water reaches 7% of the powder. Continue mixing for 10 minutes.

[0044] e. Place the powder mixed with water into a briquetting machine and press it into briquettes under a pressure of 300t. After drying the raw briquettes at 100℃, place them in a microwave baking oven and bake at 1200℃ for 60 minutes, then cool them to 25℃.

[0045] f. Pellets with a TFe content of 71.04% and a compressive strength of 2504N are placed into the silo and conveyed to the top of the blast furnace by belt conveyor, where they are smelted together with other materials in the blast furnace.

[0046] Please fill in the various indicators of the pellets from Examples 1, 2, and 3 in Table 1 below.

[0047] Table 1

[0048] Example TFe content compressive strength Example 1 70.78% 2019N Example 2 70.82% 2210N Example 3 71.04% 2504N

[0049] In summary, the processed pellets have a TFe content greater than 70%, which is better than the TFe requirements for iron pellets in GB / T 276924-2024, and the compressive strength of the pellets is greater than 2000N.

[0050] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for the co-processing and utilization of ferrous and non-ferrous metal solid waste, characterized in that: Includes the following steps: S1: Mix wet-based waste acid regeneration sludge and wet-based red mud in a natural state, with a weight ratio of (4:1) to (17:3) to obtain a mixture; S2: Dry the mixture at 150 to 200°C, then add 7 to 15% of its weight of carbon source and 2 to 5% of its weight of binder, and grind them together until the particle size is <0.1 mm to obtain powder; S3: Add 4-8% of the weight of water to the powder, stir and press into pellets; S4: Dry the pellets at 100°C, calcine at 1150-1200°C, cool and send to blast furnace for smelting, and obtain granulated blast furnace slag by separation and water cooling of the waste residue.

2. The method for co-processing and utilizing ferrous and non-ferrous metal solid waste according to claim 1, characterized in that: The waste acid regeneration sludge has a moisture content of 45%, and the dry basis content of TFe is 42-50 wt% and Cl content is 7-31 wt%; the red mud has a moisture content of 85%, and the dry basis content of TFe is 19-22 wt%, Al2O3 is 15-19 wt%, CaO is 16-21 wt%, MgO is 0.3-0.8 wt%, SiO2 is 8-13 wt%, TiO2 is 5-8 wt%, MnO is 0.1-0.3 wt%, and Na2O2 is 8 wt%.

3. The method for co-processing and utilizing ferrous and non-ferrous metal solid waste according to claim 1, characterized in that: In step S2, the carbon source is pulverized coal commonly used in blast furnaces, and the binder is bentonite or a mixture of bentonite and corn starch.

4. The method for co-processing and utilizing ferrous and non-ferrous metal solid waste according to claim 1, characterized in that: In step S4, a microwave roasting oven is used for roasting, and the roasting time is 30~60 minutes.

5. The method for co-processing and utilizing ferrous and non-ferrous metal solid waste according to any one of claims 1, characterized in that: In step S4, after the pellets are calcined and cooled, the TFe content reaches more than 70% and the compressive strength is greater than 2000N.

Images