Method for synergistically treating fuming lead slag and waste automobile exhaust catalyst

Abstract

The present application belongs to the field of metallurgical waste residue treatment, and discloses a method for co-processing of fuming lead residue and waste automobile exhaust catalyst, comprising the following steps: crushing the waste automobile exhaust catalyst to obtain catalyst powder; uniformly mixing the catalyst powder with a slagging agent to obtain a mixed slag system; vortex stirring the mixed slag system and molten fuming lead residue, introducing a mixed gas of hydrogen and magnesium vapor into the vortex stirring system to obtain a reduced desulfurized molten liquid and a lead-zinc-containing flue gas; water quenching the reduced desulfurized molten liquid to obtain a base glass and a platinum group metal-containing alloy; and recovering the lead-zinc-containing flue gas. The present application makes full use of the physical latent heat of the molten fuming lead residue generated in the lead smelting process, reduces the capture temperature, saves reaction energy consumption, and solves the problems of high energy consumption, low recovery efficiency and tail residue that cannot be treated when the fuming lead residue and the waste automobile exhaust catalyst are treated separately.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical waste treatment, and more specifically, relates to a method for the synergistic treatment of fuming lead slag and waste automobile exhaust catalyst. Background Technology

[0002] Automotive exhaust catalysts primarily use cordierite ceramics as a carrier, with PGMs (platinum group metals Pt, Pd, and Rh) firmly attached to a γ-Al₂O₃ coating. They also contain certain amounts of CeO₂ and ZrO₂ as stabilizers and promoters. During use, they can accumulate other heavy metals such as vanadium (V), lead (Pb), and cadmium (Cd). Waste automotive exhaust catalysts are classified as hazardous waste and pose a significant environmental risk.

[0003] The recovery processes for PGMs from spent automotive exhaust catalysts mainly fall into three categories: pyrometallurgical, hydrometallurgical, and biological methods. Hydrometallurgical methods generate large amounts of waste liquid, while biological methods are limited by the cultivation and reproduction conditions of microorganisms, hindering large-scale application. Currently, the most widely used process is metal capture. Common capture agents include Fe, Cu, Pb, and matte. When using copper as a capture agent, a platinum-containing copper high alloy is obtained, making the separation of copper and platinum group metals difficult. When using Pb as a capture agent, there is a risk of Pb pollution. Similarly, when using matte as a capture agent, there is a risk of environmental pollution during the smelting process. Fe is the cheapest and most readily available capture agent, exhibiting excellent capture effects on the three precious metals Pt, Pd, and Rh. Furthermore, the subsequent separation process between Fe and PGMs is relatively simple. However, using Fe as a capture agent results in high smelting energy consumption and low capture efficiency.

[0004] In addition, the lead smelting industry discharges more than one million tons of fuming lead slag every year, which has not been effectively treated or reused.

[0005] Therefore, there is an urgent need to propose a method for the co-treatment of lead slag and waste automotive exhaust catalysts. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by proposing a method for the co-processing of fuming lead slag and waste automotive exhaust catalysts. This invention fully utilizes the latent heat of physical heat from the molten fuming lead slag generated during lead smelting, reducing the collection temperature, saving reaction energy consumption, and solving the problems of high energy consumption, low recovery efficiency, and inability to handle tailings when separately processing fuming lead slag and waste automotive exhaust catalysts.

[0007] To achieve the above objectives, the present invention provides a method for the co-treatment of fuming lead slag and waste automotive exhaust catalyst, the method comprising the following steps:

[0008] S1: The waste automobile exhaust catalyst is crushed to obtain catalyst powder;

[0009] S2: Mix the catalyst powder with the slag-forming agent evenly to obtain a mixed slag system;

[0010] S3: The mixed slag system and molten lead slag are stirred in a vortex. A mixture of hydrogen and magnesium vapor is introduced into the vortex stirring system to obtain a reducing desulfurization melt and lead-zinc containing flue gas.

[0011] S4: The reduced desulfurization melt is quenched with water to obtain basic glass and platinum group metal alloys; lead-zinc flue gas is recovered.

[0012] In this invention:

[0013] The Fe element in lead slag can be used as a collector for PGMs;

[0014] SiO2 and CaO in lead slag can be combined with Al2O3 and SiO2 in waste automotive exhaust catalysts to form a low-melting-point slag system after regulation, thereby reducing the collection temperature and preparing SiO2-CaO-Al2O3 microcrystalline glass. Furthermore, CeO2 and ZrO2 in waste automotive exhaust catalysts are enriched in SiO2-CaO-Al2O3 microcrystalline glass to improve its performance.

[0015] Pb and Zn in lead slag are enriched and recovered in flue gas.

[0016] According to the present invention, preferably, the waste vehicle exhaust catalyst is at least one of Al2O3 supported catalyst, SiO2 supported catalyst and Al2O3-SiO2 supported catalyst.

[0017] According to the present invention, preferably, the equipment for performing the crushing process includes a high-energy ball mill with a material-to-ball ratio of (4-6):1.

[0018] According to the present invention, preferably, the particle size of the catalyst powder is less than 400 μm.

[0019] According to the present invention, preferably, the slag-forming agent is at least one selected from CaO, B2O3, Na2O, K2O and Na2B4O7.

[0020] In this invention, the slag-forming agent and Al2O3 in the waste automobile exhaust catalyst form a low-melting-point mixed slag system including Na2O-Ba2O3-CaO-Al2O3-SiO2 or K2O-Ba2O3-CaO-Al2O3-SiO2. This mixed slag system can reduce the collection temperature of the reaction system and reduce energy consumption.

[0021] According to the present invention, preferably, the mixed slag system satisfies at least one of the following conditions: (1) CaO / Al2O3 = 0.8-1.2; (2) CaO / SiO2 = 0.2-0.6; (3) at least one of B2O3, Na2O, K2O and Na2B4O7 accounts for 1-5% of the total weight of the slag system.

[0022] According to the present invention, preferably, the mass ratio of the molten lead slag to the catalyst powder is 1:(0.8-1.2).

[0023] According to the present invention, preferably, based on the total weight of the molten lead slag, the content of Al2O3 is 8-12 wt.%, the content of SiO2 is 40-45 wt.%, the content of FeO is 40-50 wt.%, the total content of lead and zinc is 2-3 wt.%, and the remainder is impurities.

[0024] According to the present invention, preferably, the temperature of the molten lead slag is 1150℃-1250℃; the stirring speed of the vortex stirring is 10-100r / min, the stirring time is 10-40min, and the stirring temperature is 1200℃-1800℃.

[0025] In this invention, traditional recycling processes for PGMs from waste automotive exhaust catalysts involve cold materials, requiring significant energy consumption to heat them to the reaction temperature. This invention utilizes molten lead slag at 1150℃-1250℃, thus leveraging its internal energy to reduce energy consumption during the collection process. However, since the collection process typically requires 1300℃-1400℃, further heating is necessary, specifically setting the stirring temperature at 1200℃-1800℃, meaning the smelting process temperature is also 1200℃-1800℃.

[0026] According to the present invention, preferably, the time for introducing the mixture of hydrogen and magnesium vapor into the vortex stirring system is 10-40 min, and the amount of magnesium vapor injected into the mixture is 1.5-2 times the sulfur content in the vortex stirring system.

[0027] In this invention, as a preferred embodiment, such as Figure 2 As shown, magnesium metal generates magnesium vapor in the magnesium vapor generating chamber. The magnesium vapor is carried by H2 and bottom-blown into the molten pool containing the molten liquid for reduction and desulfurization.

[0028] According to the present invention, preferably, the vortex stirring impeller is made of high-purity graphite, the impeller type is a turbine impeller, and the insertion depth is 1 / 3 to 2 / 3 of the depth of the molten pool in which the vortex stirring system is located.

[0029] According to the present invention, preferably, the sulfur content in the platinum group metal alloy is less than 0.005%.

[0030] According to the present invention, preferably, the base glass is a CaO-Al2O3-SiO2 microcrystalline glass with wollastonite as the main crystalline phase enriched with CeO2 and ZrO2;

[0031] Based on the total weight of the base glass, the content of CeO2 is 0.1-0.5 wt.%, the content of ZrO2 is 0.15-0.6 wt.%, the content of CaO is 15-25 wt.%, the content of Al2O3 is 20-30 wt.%, the content of SiO2 is 30-45 wt.%, and the content of sulfur is 1-2.4 wt.%. The content of B2O3, Na2O, K2O, and Na2B4O7 is 1-5 wt.%.

[0032] The beneficial effects of the technical solution of the present invention are as follows:

[0033] (1) This invention makes full use of the latent physical heat of the molten lead slag produced during the lead smelting process, the slag system formed by the waste automobile exhaust catalyst and slag-forming agent, and the low melting point slag system formed by SiO2 and CaO in the lead slag and Al2O3 and SiO2 in the waste automobile exhaust catalyst after regulation. The three work together to reduce the collection temperature, save reaction energy consumption, and solve the problems of high energy consumption, low recovery efficiency and inability to treat tailings when separately processing lead slag and waste automobile exhaust catalyst.

[0034] (2) This invention uses SiO2 and CaO from lead slag and Al2O3 and SiO2 from waste automotive exhaust catalysts to prepare SiO2-CaO-Al2O3-based microcrystalline glass; moreover, CeO2 and ZrO2 from the waste automotive exhaust catalysts are enriched in the SiO2-CaO-Al2O3-based microcrystalline glass, thereby improving the performance of the microcrystalline glass. This invention forms a CaO-Al2O3-SiO2-based microcrystalline glass with wollastonite as the main crystalline phase.

[0035] (3) This invention simultaneously realizes the comprehensive recycling and utilization of Fe, Pb, and Zn in lead slag and PGMs, Ce, and Zr in waste automobile exhaust catalysts.

[0036] (4) The present invention uses eddy currents to dynamically control the trapping behavior, the reaction process is fast and efficient, the trapping time is shortened to less than 50 minutes, and the trapping rate is as high as 99.2%.

[0037] (5) In this invention, H2 is used as a reducing agent to replace coke in the traditional process, and the reduction product is H2O, which reduces CO2 gas emissions.

[0038] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0039] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the invention.

[0040] Figure 1 The diagram shows a flow chart of a method for the co-treatment of fuming lead slag and waste automobile exhaust catalyst provided by the present invention.

[0041] Figure 2 The diagram shows a schematic of the process of introducing a mixture of hydrogen and magnesium vapor into a method for the co-treatment of lead slag and waste automobile exhaust catalyst provided by the present invention.

[0042] Figure 3 The diagram shows a schematic representation of the material composition obtained by a method for co-processing lead slag and waste automobile exhaust catalyst provided by the present invention.

[0043] The annotations in the attached figures are explained as follows:

[0044] 1-Magnesium vapor generating chamber; 2-Molten pool. Detailed Implementation

[0045] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0046] In the following embodiments,

[0047] The CaO, B2O3, Na2O, K2O, Na2B4O7, and Mg used are all industrial-grade products;

[0048] The hydrogen in the mixture of hydrogen and magnesium vapor is 99.9% high-purity hydrogen.

[0049] Example 1

[0050] This embodiment provides a method for the co-treatment of lead slag and waste automotive exhaust catalyst, such as... Figure 1 As shown, the method includes the following steps:

[0051] S1: The Al2O3-SiO2 supported catalyst (containing 30 wt.% Al2O3, 52 wt.% SiO2, 3.5 wt.% S, with the remainder being impurities) was crushed in a high-energy ball mill at a material-to-ball ratio of 5:1, a rotation speed of 200 r / min, and a ball milling time of 30 min to obtain catalyst powder with a D50 of 150 μm.

[0052] S2: The catalyst powder is uniformly mixed with Na2O and CaO in a mass ratio of 1000g:120g:720g to obtain a mixed slag system;

[0053] S3: The mixed slag system and molten lead slag (containing 10 wt.% Al2O3, 42 wt.% SiO2, 45 wt.% FeO, 2.5 wt.% total lead and zinc, with the remainder being impurities) are stirred in a vortex. A mixture of hydrogen and magnesium vapor is introduced into the vortex stirring system to obtain a reducing desulfurization melt and lead-zinc-containing flue gas.

[0054] The mass ratio of the molten lead slag to the catalyst powder is 1000g:1000g.

[0055] The stirring speed of the vortex stirring is 50 r / min, the stirring time is 35 min, and the melting temperature is 1500℃.

[0056] The magnesium vapor is generated from 40g of metallic magnesium in a magnesium vapor generating chamber, and the magnesium vapor is carried by H2 into the molten pool containing the molten liquid; the mixture of hydrogen and magnesium vapor is introduced into the molten liquid for 35 minutes at a flow rate of 15L / min.

[0057] The eddy current stirring uses a high-purity graphite impeller, a turbine impeller, and the insertion depth is 1 / 3 to 2 / 3 of the depth of the molten pool in which the eddy current stirring system is located.

[0058] S4: The reduced desulfurization melt is quenched with water to obtain basic glass and platinum group metal alloys; lead-zinc flue gas is recovered.

[0059] Comparative Example 1

[0060] This embodiment provides a pyrometallurgical method for recovering platinum group metals from waste automotive exhaust catalysts. The only difference between this embodiment and Embodiment 1 is that no vortex stirring is used.

[0061] Test case

[0062] This test example performs component testing on the products obtained in Example 1 and Comparative Example 1.

[0063] The testing method involved using inductively coupled plasma atomic emission spectrometry (ICP-AES) to detect the contents of Pt, Pd, Rh, Pb, and Zn in Fe-PGMs, thereby calculating the yield of PGMs. A carbon-sulfur analyzer was used to detect the sulfur content in the Fe-PGMs mixture, and X-ray fluorescence spectrometry was used to detect the oxide content in the base glass.

[0064] The test results are shown in Table 1.

[0065] Table 1

[0066]

[0067] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for the co-treatment of lead slag and waste automotive exhaust catalyst, characterized in that, The method includes the following steps: S1: The waste automobile exhaust catalyst is crushed to obtain catalyst powder; S2: Mix the catalyst powder with the slag-forming agent evenly to obtain a mixed slag system; S3: The mixed slag system in S2 is added to the molten lead slag by vortex stirring. After the material is added, stirring is continued. A mixture of hydrogen and magnesium vapor is introduced into the vortex stirring system to obtain the reducing desulfurization melt and lead-zinc flue gas. Based on the total weight of the molten lead slag, the Al2O3 content is 8-12 wt.%, the SiO2 content is 40-45 wt.%, the FeO content is 40-50 wt.%, the total lead and zinc content is 2-3 wt.%, and the remainder is impurities; S4: The reduced desulfurization melt is quenched with water to obtain basic glass and platinum group metal alloys; lead-zinc flue gas is recovered; The sulfur content in the platinum group metal alloy is less than 0.005%; The base glass is a CaO-Al2O3-SiO2 microcrystalline glass with wollastonite as the main crystalline phase and enriched with CeO2 and ZrO2. Based on the total weight of the base glass, the content of CeO2 is 0.1-0.5 wt.%, the content of ZrO2 is 0.15-0.6 wt.%, the content of CaO is 15-25 wt.%, the content of Al2O3 is 20-30 wt.%, the content of SiO2 is 30-45 wt.%, the content of sulfur is 1-2.4 wt.%, and the content of B2O3, Na2O, K2O and Na2B4O7 is 1-5 wt.%.

2. The method for co-treating lead slag and waste automotive exhaust catalyst according to claim 1, wherein, The waste vehicle exhaust catalyst is at least one of Al2O3 supported catalyst, SiO2 supported catalyst, and Al2O3-SiO2 supported catalyst.

3. The method for co-treating lead slag and waste automotive exhaust catalyst according to claim 1, wherein, The equipment for performing the crushing process includes a high-energy ball mill with a material-to-ball ratio of (4-6):1; The particle size of the catalyst powder is below 400 μm.

4. The method for co-treating lead slag and waste automotive exhaust catalyst according to claim 1, wherein, The slag-forming agent is at least one of CaO, B2O3, Na2O, K2O and Na2B4O7.

5. The method for co-treating fumed lead slag and waste automotive exhaust catalyst according to claim 1 or 4, wherein, The mixed slag system satisfies at least one of the following conditions: (1) CaO / Al2O3 = 0.8-1.2; (2) CaO / SiO2 = 0.2-0.6; (3) at least one of B2O3, Na2O, K2O and Na2B4O7 accounts for 1-5% of the total weight of the slag system.

6. The method for co-treating lead slag and waste automotive exhaust catalyst according to claim 1, wherein, The mass ratio of the molten lead slag to the catalyst powder is 1:(0.8-1.2).

7. The method for co-treating lead slag and waste automotive exhaust catalyst according to claim 1, wherein, The temperature of the molten lead slag is 1150℃-1250℃; The stirring speed of the vortex mixer is 10-100 r / min, the stirring time is 10-40 min, and the stirring temperature is 1200℃-1800℃.

8. The method for co-treating lead slag and waste automotive exhaust catalyst according to claim 1, wherein, The time for introducing the mixture of hydrogen and magnesium vapor into the vortex stirring system is 10-40 minutes, and the amount of magnesium vapor injected into the mixture is 1.5-2 times the sulfur content in the vortex stirring system.

9. The method for co-treating lead slag and waste automotive exhaust catalyst according to claim 1, wherein, The eddy current stirring uses a high-purity graphite impeller, a turbine impeller, and the insertion depth is 1 / 3 to 2 / 3 of the depth of the molten pool in which the eddy current stirring system is located.

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