Cold-wall rapid high-temperature lead recovery method for lead-containing ceramic

Abstract

The invention discloses a cold-wall rapid high-temperature lead recovery method for lead-containing ceramics, which comprises the following steps of: crushing waste lead-containing piezoelectric ceramic blocks, paving on a conductive substrate, electrifying for rapid high-temperature treatment, and condensing and collecting generated volatile flue gas to obtain a high-purity lead-containing product. The rapid high-temperature treatment method is creatively provided for lead recovery of the lead-containing ceramic, rapid high-temperature treatment and synchronous cooling collection are carried out, the concept is simple but ingenious, the practicability is high, and the recovered lead oxide has the advantages of high purity, uniform size and high reaction activity; the material is expected to be used as a precursor to realize synthesis of high-performance piezoelectric ceramics, battery materials, catalysts and special pigments, and has huge potential application value.

Description

Technical Field

[0001] The invention belongs to the technical field of ceramic materials, and in particular relates to a method for quickly recovering high-temperature lead from a cold wall of lead-containing ceramics. Background Art

[0002] Currently, lead-containing functional ceramics are widely used in sensors, transducers, ultrasonic equipment and other fields due to their advantages such as extremely high piezoelectric coefficient, excellent dielectric constant and electromechanical coupling efficiency, as well as excellent mechanical strength and chemical stability. However, lead-containing ceramics generally contain a large amount of harmful heavy metal lead, and improper disposal of it will seriously pollute the environment. Taking lead zirconate titanate (PZT) as an example, traditional methods for treating waste PZT mainly rely on simple sintering, landfilling or direct disposal. These methods cannot fully recover the valuable metal lead contained in it, and may cause the waste to produce lead-containing fly ash during high-temperature treatment. This not only wastes resources but also seriously pollutes the environment and endangers life and health. Therefore, the development of an efficient, low-energy, and environmentally friendly process for recovering lead from waste PZT has important scientific research and industrial application value, and is in line with the current industrial development trend of energy conservation, environmental protection and resource recycling.

[0003] Currently, traditional technologies for recycling lead-containing scrap materials primarily focus on high-temperature heat treatment and chemical separation. Traditional heat treatment methods utilize high temperatures to volatilize lead compounds from lead-containing scrap materials, thereby enabling lead recovery. These materials typically require calcination at high temperatures for 1-3 hours to exploit the high vapor pressure of lead for volatilization and separation. This process is energy-intensive and time-consuming. Furthermore, lead begins to lose weight as low as 575°C during volatilization, making temperature control extremely difficult. This can lead to uneven lead deposition within the furnace or lead dissipation with fly ash, resulting in low recovery efficiency, significant environmental impact, and high industrial costs. Chemical separation, on the other hand, involves dissolving and separating lead from the scrap material matrix through an acid-base reaction. While this method offers improved separation efficiency, it is complex, requires extensive chemical reagents, and generates significant wastewater, posing significant environmental risks. Overall, although some progress has been made in optimizing temperature control, reaction rate and condensation collection devices in recent years, traditional technologies are difficult to take into account the inevitable requirements of sustainable development such as high recovery rate, low cost, low carbon emissions, energy conservation and environmental protection, and there is an urgent need to develop new lead recovery technologies. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a method for rapid high-temperature lead recovery from the cold wall of lead-containing ceramics, which has high processing efficiency, low carbon emissions, and can achieve the purpose of efficient lead recovery.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] In the first aspect, the present invention provides a method for rapid high-temperature lead recovery from cold walls of lead-containing ceramics, comprising the following steps: crushing waste lead-containing piezoelectric ceramic blocks, then spreading them flat on a conductive substrate, then applying electricity for rapid high-temperature treatment, and condensing and collecting the generated volatile flue gas to obtain a high-purity lead-containing product.

[0007] In the above technical solution, it can be understood that by rapidly and high-temperature treating waste lead-containing piezoelectric ceramics, the lead is separated in the form of flue gas, and further cooling is performed to obtain recycled lead. Using a conductive substrate-based heating method, on the one hand, avoids the shortcomings of hot wall heating compared to traditional high-temperature treatment using a heating furnace, significantly improving energy efficiency and reducing energy consumption. On the other hand, the rapid heating time is only a few minutes, which is short, efficient processing, and shortens the recovery time.

[0008] As a preferred embodiment of the technical solution of the present invention, the lead-containing piezoelectric ceramics include at least one of lead zirconate titanate functional ceramics, lead zirconate functional ceramics, lead titanate functional ceramics, lead magnesium tungstate functional ceramics, lead magnesium niobate titanate functional ceramics, lead zinc niobate functional ceramics, and lead scandium niobate functional ceramics.

[0009] As a preferred embodiment of the technical solution of the present invention, the grinding is selected from at least one of mortar grinding, ball milling, ultrasonic grinding, and drum milling.

[0010] As a preferred embodiment of the technical solution of the present invention, the particles are crushed to a size of less than 1 mm.

[0011] As a preferred embodiment of the technical solution of the present invention, the paving thickness is 0.1 to 3 mm.

[0012] As a preferred embodiment of the technical solution of the present invention, the conductive substrate is selected from one of carbon felt, carbon cloth, and tungsten boat.

[0013] As a preferred embodiment of the technical solution of the present invention, the rapid high-temperature treatment is: heating the temperature to 800-1800° C. at a heating rate of 30-300° C. / s, and the treatment time is 20-300 seconds.

[0014] As a preferred embodiment of the technical solution of the present invention, the condensation collection temperature is 5 to 50°C. It can be understood that the condensation collection can adopt any common device structure, preferably a metal plate; the cooling form of the metal plate can be various common cooling forms such as air cooling and water cooling, preferably water cooling. That is, the condensation collection of volatile flue gas in this application is based on the arrangement of a water-cooled metal plate directly above the conductive substrate, so that the volatile flue gas can be cooled and accumulated on the metal plate, and the distance between the metal plate and the conductive substrate is preferably 2 cm. It should be noted that the above-mentioned setting method is only an example and does not represent a specific limitation on its treatment method. The temperature of condensation collection is 5 to 50°C, preferably 10°C.

[0015] In a second aspect, the present invention aims to protect the high-purity lead-containing product obtained by the above-mentioned recovery method.

[0016] In a third aspect, the present invention aims to provide the use of the high-purity lead-containing product obtained above in the preparation of piezoelectric ceramics, battery materials or catalysts.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) In view of the shortcomings of the current lead recovery technology in lead-containing ceramics, the present invention creatively proposes a cold wall rapid high-temperature recovery method, which can be achieved through rapid high-temperature treatment and synchronous cooling and collection. The concept is simple but ingenious and highly practical.

[0019] (2) The cold wall rapid high-temperature lead recovery method provided by the present invention can rapidly volatilize the lead element in waste lead zirconate titanate ceramics in a short period of time and efficiently collect it through the adjacent condensation unit, thereby achieving selective and efficient recovery of harmful lead elements in lead-containing ceramics, overcoming the problem of partial lead loss or co-condensation with impurities caused by long-term high-temperature treatment in traditional methods.

[0020] (3) The cold wall rapid high-temperature lead recovery method provided by the present invention significantly shortens the reaction time (only a few minutes), has the advantages of a short process flow, high efficiency, no waste liquid discharge, and simple equipment that is easy to scale up; in addition, the energy consumption, carbon emissions, and equipment operating costs are significantly lower than those of traditional long-term high-temperature sintering or chemical dissolution separation processes, and has high environmental and economic benefits.

[0021] (4) The cold wall rapid high-temperature lead recovery method provided by the present invention recovers lead elements mainly in the form of micron-sized flake lead monoxide, which has the advantages of high purity, uniform size, and high reactivity. It is expected to be used as a precursor to realize the synthesis of high-performance piezoelectric ceramics, battery materials, catalysts and special pigments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is the lead recovery efficiency at different temperatures in Examples 1 to 3;

[0023] Figure 2 The X-ray diffraction pattern of the powder collected in Example 2;

[0024] Figure 3 (a) and (b) are scanning electron microscope images of the powder collected in Example 2. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments. Of course, the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0026] Although the steps in the present invention are arranged with numbers, they are not intended to limit the order of the steps. Unless the order of the steps is clearly stated or the execution of a step requires other steps as a basis, the relative order of the steps can be adjusted. It is understood that the term "and / or" used herein refers to and covers any and all possible combinations of one or more of the associated listed items.

[0027] Example 1

[0028] A method for rapidly recovering high-temperature lead from a cold wall of lead-containing ceramics comprises the following steps:

[0029] (1) Raw material pretreatment: PbZr was mortared 0.5 Ti 0.5 The O3 ceramic (PZT ceramic) block was ground into less than 1 mm in a mortar, and the obtained powder was weighed to a mass of 0.042 g.

[0030] (2) Rapid high-temperature heating: The obtained PZT ceramic powder was spread on a 1 cm wide and 4 cm long carbon felt with a thickness of 1 mm. The two ends of the carbon felt were then connected to a constant current power supply through wires. The power supply parameters were set to 11 A and 200 s. The temperature of the carbon cloth was monitored in real time by a thermal radiation thermometer. The temperature was raised to 840 °C within 20 s, kept at this temperature until no obvious volatiles were released, and then rapidly cooled (cooling rate 220 °C / s) to room temperature to obtain yellow powder and white smoke.

[0031] (3) Product collection: A condensation collection plate is placed above the sample, with a distance of 2 cm between the condensation plate and the sample; the volatile flue gas is rapidly cooled on the condensation plate and condensed to form a yellow-white substance, which is a high-purity lead-containing product.

[0032] Efficiency calculation: The recovered mass is the difference between the mass before and after heating. The remaining material after heating was removed from the sealed glove box and weighed to 0.0305 g. The total lead mass was calculated based on the PZT composition ratio. The recovered lead mass was divided by the total lead mass to obtain a lead recovery rate η of 37.3%.

[0033] Example 2

[0034] A method for rapidly recovering high-temperature lead from a cold wall of lead-containing ceramics comprises the following steps:

[0035] (1) Raw material pretreatment: PZT ceramic blocks were ground into powder with a mortar to a size of less than 1 mm. The obtained powder was weighed to a mass of 0.0546 g.

[0036] (2) Rapid high-temperature heating: The obtained lead-containing ceramic powder was spread on a 1 cm wide and 4 cm long carbon felt with a thickness of 1 mm. The two ends of the carbon felt were then connected to a constant current power supply through wires. The power supply parameters were set to 12 A and 150 s. The temperature of the carbon cloth was monitored in real time by a thermal radiation thermometer. The temperature was raised to 960 °C within 20 s, kept at this temperature until no obvious volatiles were released, and then rapidly cooled (cooling rate 200 °C / s) to room temperature to obtain yellow powder and white smoke.

[0037] (3) Product collection: A condensation collection plate is placed above the sample, with a distance of 2 cm between the condensation plate and the sample; the volatile flue gas is rapidly cooled on the condensation plate and condensed to form a yellow-white substance, which is a high-purity lead-containing product.

[0038] Efficiency calculation: The recovered mass is the difference between the mass before and after heating. The remaining material after heating was removed from the sealed glove box and weighed to 0.0232 g. The total lead mass was calculated based on the PZT composition ratio. The lead mass in the collected powder was divided by the total lead mass to obtain a lead recovery rate (η) of 78%.

[0039] See also Figure 2 As shown, the main characteristic diffraction peaks of the obtained sample completely match the crystal plane diffraction peaks of lead oxide in the standard card, indicating that the sample is mainly PbO.

[0040] See further Figure 3 As shown, the obtained sample presents a circular flake structure with a size distribution between 1 and 3 μm.

[0041] Example 3

[0042] A method for rapidly recovering high-temperature lead from a cold wall of lead-containing ceramics comprises the following steps:

[0043] (1) Raw material pretreatment: PZT ceramic blocks were ground into powder with a mortar to a size of less than 1 mm. The obtained powder was weighed to a mass of 0.036 g.

[0044] (2) Rapid high-temperature heating: The obtained PZT ceramic powder was spread on a 1 cm wide and 4 cm long carbon felt with a thickness of 1 mm. The two ends of the carbon felt were then connected to a constant current power supply through wires. The power supply parameters were set to 13 A and 240 s. The temperature of the carbon cloth was monitored in real time by a thermal radiation thermometer. The temperature was raised to 1100 °C within 25 s, kept at this temperature until no obvious volatiles were released, and then rapidly cooled (cooling rate 250 °C / s) to room temperature to obtain yellow powder and white smoke.

[0045] (3) Product collection: A condensation collection plate is placed above the sample, with a distance of 2 cm between the condensation plate and the sample; the volatile flue gas is rapidly cooled on the condensation plate and condensed to form a yellow-white substance, which is a high-purity lead-containing product.

[0046] Efficiency calculation: The recovered mass is the difference between the mass before and after heating. The remaining material after heating was removed from the sealed glove box and weighed to 0.0112 g. The total lead mass was calculated based on the PZT composition ratio. The recovered lead mass was divided by the total lead mass to obtain a lead recovery rate η of 93.4%.

[0047] While the present invention is illustrated by the aforementioned embodiments, the present invention is not limited to these embodiments, nor does it necessarily rely on these embodiments for implementation. Those skilled in the art will appreciate that any improvements to the present invention, equivalent replacements for individual raw materials in the present invention, additions of auxiliary ingredients, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for rapidly recovering high-temperature lead from the cold wall of lead-containing ceramics, characterized in that: The method comprises the following steps: crushing the waste lead-containing piezoelectric ceramic blocks, then spreading them flat on a conductive substrate, then applying electricity for rapid high-temperature treatment, and condensing and collecting the generated volatile flue gas to obtain a high-purity lead-containing product.

2. The method for rapidly recovering high-temperature lead from the cold wall of lead-containing ceramics according to claim 1, characterized in that: The lead-containing piezoelectric ceramics include at least one of lead zirconate titanate functional ceramics, lead zirconate functional ceramics, lead titanate functional ceramics, lead magnesium tungstate functional ceramics, lead magnesium niobate titanate functional ceramics, lead zinc niobate functional ceramics, and lead scandate niobate functional ceramics.

3. The method for rapid high-temperature lead recovery from cold wall of lead-containing ceramics according to claim 1, characterized in that: The pulverization is selected from at least one of mortar grinding, ball milling, ultrasonic milling, and drum milling.

4. The method for rapid high-temperature lead recovery from cold walls of lead-containing ceramics according to claim 1, characterized in that: Crush to a size of less than 1 mm.

5. The method for rapid high-temperature lead recovery from cold wall of lead-containing ceramics according to claim 1, characterized in that: The tiling thickness is 0.1 to 3 mm.

6. The method for rapid high-temperature lead recovery from cold walls of lead-containing ceramics according to claim 1, characterized in that: The conductive substrate is selected from one of carbon felt, carbon cloth and tungsten boat.

7. The method for rapid high-temperature lead recovery from cold wall of lead-containing ceramics according to claim 1, characterized in that: The rapid high temperature treatment is as follows: heating the temperature to 800-1800° C. at a heating rate of 30-300° C. / s, and the treatment time is 20-300 seconds.

8. The method for rapid high-temperature lead recovery from cold walls of lead-containing ceramics according to claim 1, characterized in that: The condensation collection temperature is 5-50℃.

9. A high-purity lead-containing product recovered by the method according to any one of claims 1 to 8.

10. Use of the high-purity lead-containing product according to claim 9 in the preparation of piezoelectric ceramics, battery materials or catalysts.

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