Process for recovering copper and aluminum from flue gas CO removal catalyst waste agent

Abstract

The invention discloses a process for recovering copper and aluminum from a flue gas CO removal catalyst waste agent, and belongs to the technical field of industrial catalysis. Aiming at a flue gas CO removal catalyst of a copper-based aluminum carrier commonly used in industrial flue gas, the invention provides a method for recovering copper and aluminum from a CO removal catalyst waste agent, and the method mainly comprises the specific steps of pretreatment of the flue gas CO removal catalyst waste agent, sodium salt roasting treatment, alkaline leaching treatment, precipitation treatment and replacement treatment. After treatment, aluminum oxide and copper oxide can be respectively obtained, and can be used for preparing a new agent of a CO removal catalyst. According to the recovery process, dry and wet combination is adopted, aluminum and copper in the waste agent are subjected to alkaline leaching at the same time through a one-step method, then the copper and the aluminum are recovered step by step through pH adjustment, auxiliary precipitation and a replacement reaction, and the comprehensive recovery rate of aluminum oxide of the waste agent exceeds 95% and can reach 98.5% to the maximum; the comprehensive recovery rate of copper oxide exceeds 90%, and the highest recovery rate can reach 99.3%. According to the process, the recovery selectivity and the recovery efficiency of the flue gas CO removal catalyst waste agent are improved, and the emission of three wastes in the recovery process is also reduced.

Description

Technical Field

[0001] The invention relates to the technical field of industrial catalysis, and in particular to a process for recovering copper and aluminum from flue gas de-CO catalyst waste. Background Art

[0002] Carbon monoxide (CO) is a common toxic gas and one of the six major air pollutants. Automobile exhaust and steel production flue gas emissions are the main sources of CO. At present, the mature "three-way catalytic" emission reduction technology has basically solved the problem of CO emissions in automobile exhaust, but CO emission reduction in steel industry flue gas is still in the exploratory stage. According to statistics, China's steel industry will consume about 700 million tons of coal in 2023, and the CO generated in the sintering process alone will be as high as 50 million to 60 million tons, and its calorific value is converted into standard coal of 2.016 million to 2.419 million tons. The volume fraction of CO in sintering flue gas is low (about 1%), and it is difficult to utilize resources. It is generally discharged directly into the atmosphere, which not only causes environmental pollution, but also leads to energy waste. Therefore, effectively controlling carbon monoxide emissions in flue gas is very important for continuously improving the quality of the atmospheric environment.

[0003] Copper-based catalysts are widely used to remove CO from factory flue gas. The catalyst uses alumina as a carrier, in which the active component copper oxide accounts for 20-40% of the total mass. Due to the complex components of factory flue gas, alkali metals, sulfur dioxide, etc. can cause catalyst poisoning, and fly ash can block the micropores of the catalyst, resulting in an average life of carbon monoxide catalysts of only 2-3 years, and the application cost of enterprises is high. The discarded catalyst contains a large amount of copper oxide and aluminum oxide. Direct discard will not only cause environmental pollution, but also lead to a waste of copper and aluminum resources. Therefore, the copper and aluminum can be recycled and reused through physical and chemical methods.

[0004] Waste catalyst recovery technology mainly includes dry process and wet process. The dry process is to use a heating furnace to heat the waste catalyst and other additives together to reduce them to alloys for recovery, including oxidation roasting, volatilization and sublimation methods, and the process route is relatively simple. However, its energy consumption is high, and only intermediate products such as alloys can be obtained. For example, patent CN201610979567 discloses a method for dry recovery of metal titanium, vanadium and tungsten in waste SCR catalysts, which uses a dry process to achieve the recovery of valuable metals such as titanium, vanadium and tungsten; the wet process is to use appropriate solvents to dissolve the valuable metals in the waste catalyst and extract and collect them again, including organic solvent method, acid dissolution method, alkali dissolution method and other methods. The utilization rate and recovery rate of the wet process are high, but its process route is relatively complex, and waste liquid will be generated during the process. Volatile solvents may also produce toxic gases and other problems. For example, patent CN202410649387 discloses a method for recovering nickel-containing waste catalysts, which uses a wet process to achieve a high proportion of nickel recovery in waste nickel catalysts and produce high-quality nickel sulfate. In recent years, ultrasound has attracted wide attention in the field of leaching and recovery due to its unique thermal effect and cavitation mechanical effect. The use of ultrasound to pretreat impurities on the surface of spent catalysts can effectively shorten the metal leaching time, reduce the amount of reagents used, and lower the required leaching temperature.

[0005] In summary, the demand for flue gas carbon monoxide catalysts is huge, but due to various reasons such as high catalyst cost, short life, and immature catalyst recovery process, flue gas carbon monoxide catalytic technology has not been promoted on a large scale. Summary of the invention

[0006] In view of this, the purpose of the present invention is to recover copper and aluminum in flue gas deCO catalyst waste, and to provide a process for recovering copper and aluminum from waste catalyst. This method organically combines dry and wet methods, adopts a one-step method to simultaneously leach aluminum and copper in the catalyst waste, and then recovers copper and aluminum in steps by adjusting pH, auxiliary precipitation and replacement reaction. This process improves recovery efficiency while achieving high-quality recovery, and can reduce the pollution of industrial waste to the environment, which has great environmental and economic significance.

[0007] To achieve the above object, the technical solution of the present invention is achieved as follows: The process for recovering copper and aluminum from flue gas de-CO catalyst waste comprises the following steps: S1. Pretreatment: crush the waste flue gas deCO catalyst, add deionized water, put it into an ultrasonic reactor, perform ultrasonic treatment at a certain power for a certain period of time, and then filter to obtain filter cake and filtrate. The purpose of this step is to clean the carbon deposits, fly ash, etc. on the surface of the waste catalyst to improve the leaching efficiency. The cavitation effect of ultrasound can make the particles inside the waste catalyst system collide at high speed, reduce the thickness of the diffusion layer, increase the mass transfer efficiency, and generate local turbulence, etch the solid surface, increase the mass transfer area, and thus improve the leaching efficiency; S2, sodium calcination treatment: After adding additive A to the filter cake of S1, mix it evenly with an appropriate amount of NaOH, and calcine it at a certain temperature for a certain time to obtain a mixture. The purpose of this step is to convert the aluminum oxide in the spent catalyst into a soluble sodium salt and further remove impurities.

[0008] S3, alkali leaching treatment: At a certain temperature, use an appropriate amount of alkali solution and additive B to dissolve the S2 mixture, filter after sufficient reaction, and obtain filter cake and filtrate. The purpose of this step is to extract aluminum and copper elements in the waste catalyst into the filtrate and separate them from insoluble impurities.

[0009] S4, precipitation treatment: After adding the additive C to the S3 filtrate, add an appropriate amount of acid solution to adjust the pH to obtain a precipitate. After aging and filtering, a filter cake and a filtrate are obtained. After washing, drying and roasting the filter cake, an alumina sample is obtained. The purpose of this step is to use the additive and the precise adjustment of pH to convert the aluminum element in the filtrate into an alumina precursor, and then make alumina, and at the same time separate the filtrate containing copper elements.

[0010] S5, replacement treatment: add an appropriate amount of replacement agent to the filtrate of S4, react at a certain temperature for a certain time, and then filter to obtain a filter cake and a filtrate. The purpose of this step is to carry out directional separation and extraction of the copper component in the filtrate through the replacement reaction to produce copper oxide.

[0011] Preferably, the flue gas deCO catalyst waste agent described in step S1 is crushed to a particle size of less than 300 mesh, calcined at 450° C. for 6 h, ultrasonically treated with a power of 100-600 W for 10-60 min.

[0012] Preferably, the additive A in step S2 is one or both of boric acid and aluminum fluoride, the amount of additive A is 0.02-0.1 times the mass of the waste catalyst, the mass of NaOH is 0.5-2 times the mass of the waste catalyst, the roasting temperature is 400-600°C, and the roasting time is 3 hours. The additive A can reduce the melting point of alumina, promote the crystal transformation of alumina, accelerate the formation of sodium aluminate, and improve the subsequent leaching efficiency.

[0013] Preferably, the alkaline solution in step S3 is one or both of ammonia water and NaOH solution, the additive B is ammonium carbonate, the additive amount is 0.02-0.1 times the mass of the waste catalyst, the leaching temperature is 30-80° C., the leaching time is 1-6 hours, the mass of the alkaline solution is 5 times the mass of the waste catalyst, and the pH of the alkaline solution is 9-11. The additive B can increase the leaching rate of copper oxide and accelerate the leaching speed.

[0014] Preferably, the auxiliary agent C in step S4 is one or both of polyacrylamide and polyaluminium chloride, the precipitant is nitric acid solution, the mass of the auxiliary agent is 0.1-0.3 times the mass of the filtrate, the alkali solution is adjusted to a pH of 8-10, the aging time is 12 h, the roasting temperature is 500° C., and the roasting time is 6 h. The auxiliary agent C accelerates the precipitation of aluminum ions through adsorption and bridging.

[0015] Preferably, the displacing agent in step S5 is iron powder, the mass of the iron powder is 1.2-2 times the mass of the catalyst copper oxide, the reaction time is 1-6h, the reaction temperature is 30-80°C, the calcination temperature is 450°C, and the calcination time is 6h.

[0016] This method can recover more than 90% of copper oxide and more than 95% of aluminum oxide in the spent catalyst, both of which can be used to prepare new CO catalysts and other catalysts.

[0017] Compared with the prior art, the application of the present invention in the field of flue gas denitrification has the following advantages: (1) The present invention first focuses on the problem of recycling waste flue gas deCO catalyst, and proposes a pretreatment method of ultrasonic treatment and sodium roasting and an efficient process for simultaneous alkaline leaching and recovery of copper and aluminum, which reduces the temperature and time required for leaching of metals in the waste flue gas deCO catalyst, while also having a higher leaching rate, avoiding the common acid leaching process, and solving the problem that copper oxide cannot be efficiently separated by acid leaching in the recovery of waste catalyst copper and the acid leaching process causes damage to the equipment.

[0018] (2) The present invention first uses a polymer auxiliary agent in combination with a pH adjustment method to induce the precipitation and separation of aluminum in the copper-aluminum mixed leachate, thereby separating the copper ions and aluminum ions in the leachate, providing the possibility for subsequent recovery, solving the problem of aluminum carrier waste in the recovery process, shortening the process flow, and improving the recovery efficiency.

[0019] (3) The present invention has developed a full-process process for resource recovery and utilization of copper and aluminum in flue gas deCO catalyst waste, which adopts a process combining dry and wet methods, and simultaneously leaches copper and aluminum in the waste catalyst and then recovers them in steps. The recovery process is short, efficient, consumes less auxiliary materials, has low production costs, and is environmentally friendly. In the whole process, the comprehensive recovery rate of copper oxide exceeds 90%, and can reach up to 99.3%. The comprehensive recovery rate of aluminum oxide exceeds 95%, and can reach up to 99%. It not only realizes the efficient recovery and utilization of copper and aluminum in waste catalysts, but also avoids excessive pollution to the environment during the recovery process. The whole process has high economic feasibility and is suitable for practical industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows the specific steps of recovering copper and aluminum from CO removal catalyst waste DETAILED DESCRIPTION

[0020] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0021] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0022] The waste flue gas carbon monoxide catalyst used in the embodiment was provided by a steel plant in Hebei Province. After sampling and ICP testing, its main components were found to be as follows: Element Alumina Copper Oxide The remaining components Quality fraction (%) 54 32 14 Example 1

[0023] S1, pretreatment: 500 g of spent catalyst was crushed to less than 300 mesh, soaked in deionized water for 2 h, placed in an ultrasonic reactor, and subjected to ultrasonic treatment at 100 W power for 10 min, then filtered to obtain a filter cake and a filtrate; S2. Sodium calcination treatment: The S1 filter cake was evenly mixed with 10 g of boric acid and 135 g of NaOH, and then calcined to obtain a mixture. The calcination temperature was 400° C. and the calcination time was 3 h.

[0024] S3, alkaline leaching treatment: at 30 ° C, take 200 g of ammonia water with a mass concentration of 25%, add 2300 g of water to make an alkaline solution with a pH of 9, add 10 g of ammonium carbonate, put the S2 mixture into the solution, react for 1 hour, and then filter to obtain a filter cake and a filtrate.

[0025] S4. Precipitation treatment: add 13.5 g of polyacrylamide to the S3 filtrate, then add 0.1 mol / L nitric acid solution dropwise to adjust the pH to 8. After 12 h of aging, filter to obtain a filter cake and filtrate. Wash and dry the filter cake, and finally calcine at 500°C for 6 h to obtain 268 g of alumina sample #1.

[0026] S5. Replacement treatment: add 192 g of iron powder to the filtrate of S4, react at 30°C for 1 h, filter to obtain a filter cake and a filtrate, dry the filter cake, and calcine at 450°C for 6 h in an air atmosphere to obtain 152 g of copper oxide sample #1. Example 2

[0027] S1, pretreatment: 500 g of spent catalyst was crushed to less than 300 mesh, soaked in deionized water for 2 h, placed in an ultrasonic reactor, and subjected to ultrasonic treatment at 600 W power for 60 min, and then filtered to obtain a filter cake and a filtrate; S2. Sodium calcination treatment: The S1 filter cake was evenly mixed with 50 g of aluminum fluoride and 270 g of NaOH, and then calcined to obtain a mixture. The calcination temperature was 600° C. and the calcination time was 3 h.

[0028] S3, alkaline leaching treatment: at 80 ° C, take 580 g of 25% ammonia water and 20 g of 0.1 mol / L NaOH solution, add 1900 g of water to prepare an alkaline solution with pH = 11, add 50 g of ammonium carbonate, put the S2 mixture into the solution, react for 6 hours, and then filter to obtain a filter cake and a filtrate.

[0029] S4. Precipitation treatment: add 40.5 g of polyaluminium chloride to the S3 filtrate, then add 0.1 mol / L nitric acid solution dropwise to adjust the pH to 10. After aging for 12 h, filter to obtain a filter cake and filtrate. Wash and dry the filter cake, and finally calcine at 500°C for 6 h to obtain 261 g of alumina sample #2.

[0030] S5. Replacement treatment: add 320 g of iron powder to the filtrate of S4, react at 80°C for 6 h, filter to obtain a filter cake and a filtrate, dry the filter cake and calcine at 450°C for 6 h to obtain 175 g of copper oxide sample #2. Example 3

[0031] S1, pretreatment: 500 g of spent catalyst was crushed to less than 300 mesh, soaked in deionized water for 2 h, placed in an ultrasonic reactor, and subjected to ultrasonic treatment at 400 W power for 30 min, then filtered to obtain a filter cake and a filtrate; S2. Sodium calcination treatment: The S1 filter cake was evenly mixed with 25 g of aluminum fluoride, 10 g of boric acid and 202.5 g of NaOH, and then calcined to obtain a mixture. The calcination temperature was 500° C. and the calcination time was 3 h.

[0032] S3. Alkali leaching treatment: At 60°C, take 598 g of 25% ammonia water and 2 g of 0.1 mol / L NaOH solution, add 1900 g of water to form an alkaline solution with pH=10, add 25 g of ammonium carbonate, put the S2 mixture into the solution, react for 4 hours, and then filter to obtain a filter cake and filtrate.

[0033] S4. Add 27 g of polyacrylamide and 27 g of polyaluminum chloride to the filtrate of S3, then add 0.1 mol / L nitric acid solution dropwise to adjust the pH to 9. After aging for 12 h, filter to obtain a filter cake and filtrate. Wash and dry the filter cake, and finally calcine at 500°C for 6 h to obtain 268 g of alumina sample #3.

[0034] S5. Replacement treatment: Add 240 g of iron powder to the filtrate of S4, react at 60°C for 3 h, filter to obtain a filter cake and a filtrate, dry the filter cake, and calcine at 450°C for 6 h to obtain 163 g of copper oxide sample #3.

[0035] The mass fractions of aluminum oxide and copper oxide samples can be obtained by ICP testing as shown in the following table

[0036] The aluminum recovery rate of the spent catalyst is calculated by the following formula:

[0037] The copper recovery rate of the spent catalyst is calculated by the following formula:

[0038] Finally, the aluminum recovery rates of the waste catalysts of Example 1, Example 2, and Example 3 were 95.6%, 97.9%, and 98.5%, respectively; and the copper recovery rates were 91.0%, 98.7%, and 99.3%, respectively.

[0039] Based on the above test results, it can be seen that this process for recovering copper and aluminum from waste flue gas deCO catalyst has a good recovery rate of waste catalyst aluminum oxide and copper oxide.

[0040] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A process for recovering copper and aluminum from flue gas de-CO catalyst waste, characterized in that: The steps include: S1. Pretreatment: crush the waste flue gas deCO catalyst, add deionized water, put it into an ultrasonic reactor, perform ultrasonic treatment at a certain power for a certain time, and then filter to obtain a filter cake and a filtrate; S2, sodium calcination treatment: after adding additive A to the filter cake of S1, mix it evenly with an appropriate amount of NaOH, and calcine it at a certain temperature for a certain time to obtain a mixture; S3, alkali leaching treatment: at a certain temperature, use an appropriate amount of alkali solution and auxiliary agent B to dissolve the S2 mixture, filter after sufficient reaction, and obtain a filter cake and a filtrate; S4, precipitation treatment: after adding auxiliary agent C to the S3 filtrate, add an appropriate amount of acid solution to adjust the pH to obtain a precipitate, after aging and filtering, obtain a filter cake and a filtrate, wash, dry and calcine the filter cake to obtain an alumina sample; S5. Replacement treatment: add an appropriate amount of replacement agent to the filtrate of S4, react at a certain temperature for a certain time, filter to obtain a filter cake and a filtrate, and dry and calcine the filter cake to obtain a copper oxide sample.

2. The process for recovering copper and aluminum from flue gas deCO catalyst waste according to claim 1, characterized in that: The flue gas deCO catalyst waste agent described in step S1 is crushed to a particle size of less than 300 mesh, the roasting temperature is 450° C., the time is 6 h, the ultrasonic treatment power is 100-600 W, and the treatment time is 10-60 min.

3. The process for recovering copper and aluminum from flue gas deCO catalyst waste according to claim 1, characterized in that: The auxiliary agent A in step S2 is one or both of boric acid and aluminum fluoride, the mass of the auxiliary agent A is 0.02-0.1 times the mass of the waste catalyst, the mass of NaOH is 0.5-2 times the mass of the waste catalyst, the calcination temperature is 400-600°C, and the calcination time is 3 h.

4. The process for recovering copper and aluminum from flue gas deCO catalyst waste according to claim 1, characterized in that: The alkaline solution described in step S3 is one or both of ammonia water and NaOH solution, the auxiliary agent B is ammonium carbonate, the mass of the auxiliary agent B is 0.02-0.1 times the mass of the waste catalyst, the leaching temperature is 30-80°C, the leaching time is 1-6h, the mass of the alkaline solution is 5 times the mass of the waste catalyst, and the pH of the alkaline solution is 9-11.

5. The process for recovering copper and aluminum from flue gas deCO catalyst waste according to claim 1, characterized in that: In step S4, the auxiliary agent C is one or both of polyacrylamide and polyaluminium chloride, the precipitant is nitric acid solution, the mass of auxiliary agent C is 0.1-0.3 times the mass of the filtrate, the alkali solution is adjusted to a pH of 8-10, the aging time is 12 h, the calcination temperature is 500°C, and the calcination time is 6 h.

6. The process for recovering copper and aluminum from flue gas de-CO catalyst waste according to claim 1, characterized in that: In step S5, the displacing agent is iron powder, the mass of the iron powder is 1.2-2 times the mass of the catalyst copper oxide, the reaction time is 1-6h, the reaction temperature is 30-80°C, the calcination temperature is 450°C, and the calcination time is 6h.

Images