Treatment and recovery process for magnetic separation of waste high-temperature alloy

Abstract

The invention belongs to the field of resource recovery treatment, and provides a treatment and recovery process for magnetic separation of waste high-temperature alloy, the treatment and recovery process comprises the following steps: carrying out magnetic separation on the high-temperature alloy to obtain high-iron low-nickel magnetic concentrate and high-nickel low-iron magnetic tail; the magnetic concentrate and the magnetic tail are respectively leached, the magnetic concentrate is subjected to high-temperature and high-pressure iron removal after being leached, then the pH is adjusted for impurity removal, the pH can be directly adjusted for impurity removal after the magnetic tail is leached, and filtrate obtained after pH adjustment and impurity removal is combined and can be used for extracting nickel and cobalt. The high-temperature alloy is divided into magnetic tailings and magnetic concentrates through magnetic separation, so that the problem of low leaching rate of direct leaching of all high-temperature alloy powder is effectively solved; the cost can be effectively reduced only by performing high-temperature and high-pressure iron removal on the magnetic concentrate; and the magnetic concentrate and the magnetic tail are respectively subjected to leaching and pH adjustment for impurity removal, so that compared with direct treatment of all high-temperature alloy powder, the used acid solution and precipitator are effectively reduced, the coprecipitation rate of nickel is reduced, and the yield of nickel is improved.

Description

Technical Field

[0001] This invention belongs to the field of resource recycling and processing, and relates to a magnetic separation process for the recycling of waste high-temperature alloys. Background Technology

[0002] Nickel and its compounds have become increasingly widely used and are now an irreplaceable material in the metallurgical industry and some emerging industries. However, as a finite and non-renewable resource, nickel's sustainable development needs to be considered.

[0003] High-temperature alloys are ultra-heat-resistant alloys made primarily of nickel, ferronickel, or cobalt. They possess unparalleled mechanical strength and resistance to surface oxidation and corrosion, allowing them to operate in extreme temperature environments without structural damage. They are widely used in metal components operating under extreme conditions in aerospace, nuclear industry, and petrochemical fields. However, with the increasing use of nickel-based high-temperature alloys, alloy waste is also increasing year by year. Recycling this nickel-based high-temperature alloy waste can achieve the secondary utilization of other non-ferrous metals such as chromium, cobalt, and molybdenum while recovering nickel.

[0004] For high-temperature alloys with nickel as the main component, the mainstream technologies for nickel recovery in the field usually include leaching and direct pH adjustment for impurity removal.

[0005] Specifically, leaching with sulfuric acid or hydrochloric acid is the first step to bring valuable metal elements from the material into the solution. Effective leaching of nickel and cobalt is crucial for achieving high metal recovery rates in subsequent processes. When high-temperature alloys with nickel-iron as the main component are leached with sulfuric acid at a 2:1 acid excess ratio, the nickel leaching rate is generally around 90%, with room for improvement. The slag rate is approximately 16.7%, and the nickel content in the slag is relatively high, reaching 16.12%. Therefore, a second-stage leaching process is needed on the leaching slag to further enhance the nickel recovery rate.

[0006] Since impurities such as iron, chromium, and aluminum are also leached along with nickel and cobalt in the first leaching step, their presence can affect subsequent nickel extraction and purification. Therefore, sodium hydroxide (liquid alkali), sodium carbonate, or lime are typically used to directly adjust the pH to precipitate impurities, separating valuable metals like nickel and cobalt from impurities such as iron, chromium, and aluminum. However, during the direct pH adjustment precipitation process, iron easily forms ferric hydroxide colloids, making solution filtration difficult and also entraining a large amount of nickel into the precipitate residue, resulting in nickel losses of up to 31%–36% and a decrease in nickel yield.

[0007] In addition, to further address the issue of nickel entrainment in the ferric hydroxide colloid generated during pH adjustment, researchers have attempted to remove most of the iron using a high-temperature, high-pressure method before pH adjustment precipitation. This reduces the amount of iron, chromium, aluminum, and other impurities in the subsequent pH adjustment precipitation, significantly decreasing nickel entrainment precipitation. However, this operation results in 15%–20% chromium precipitation in the iron-containing slag, and the pre-treatment of the entire leachate with high-temperature, high-pressure iron removal is inconvenient and energy-intensive, leading to a substantial increase in costs. Summary of the Invention

[0008] In view of the problems existing in the prior art, the purpose of this invention is to provide a process for the treatment and recycling of waste high-temperature alloys by magnetic separation. The process includes magnetic separation of the high-temperature alloy to obtain high-iron, low-nickel magnetic concentrate and high-nickel, low-iron magnetic tails. The magnetic concentrate and magnetic tails are leached separately. After leaching, the magnetic concentrate undergoes high-temperature, high-pressure iron removal followed by pH adjustment for impurity removal. The magnetic tails can be directly adjusted for pH impurity removal after leaching. The filtrates after pH adjustment and impurity removal are combined and used for nickel and cobalt extraction. Separating the high-temperature alloy into magnetic tails and magnetic concentrate by magnetic separation effectively solves the problem of low leaching rates when directly leaching all high-temperature alloy powder. High-temperature, high-pressure iron removal only on the magnetic concentrate effectively reduces costs. Leaching and pH adjustment of the magnetic concentrate and magnetic tails separately significantly reduces the amount of acid solution and precipitant used compared to directly treating all high-temperature alloy powder, and also reduces the nickel co-precipitation rate, thus increasing the nickel yield.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] This invention provides a process for the treatment and recycling of waste high-temperature alloys through magnetic separation, the process comprising the following steps:

[0011] The high-temperature alloy is subjected to magnetic separation to obtain magnetic concentrate and magnetic tail; the mass of iron in the magnetic concentrate accounts for more than 95% of the mass of iron in the high-temperature alloy, and the mass of nickel in the magnetic concentrate accounts for less than 15% of the mass of nickel in the high-temperature alloy.

[0012] The magnetic material is subjected to a first acid leaching to obtain a first leaching solution and a first leaching residue; the first leaching solution is subjected to a first oxidation and high-temperature and high-pressure iron removal to obtain a first filtrate and a first filter residue; the first filtrate is subjected to a first pH adjustment to remove impurities to obtain a third filtrate and a third filter residue.

[0013] The magnetic tail is subjected to a second acid leaching to obtain a second leachate and a second leachate residue; the second leachate is then subjected to a second oxidation and a second pH adjustment for impurity removal to obtain a second filtrate and a second filter residue.

[0014] The second filtrate and the third filtrate are combined to extract nickel and cobalt.

[0015] The magnetic separation process for recycling waste high-temperature alloys described in this invention innovatively utilizes magnetic separation to separate the high-temperature alloy into two parts: the magnetic tail and the magnetic concentrate. The magnetic concentrate has a high iron content and a low nickel content, while the magnetic tail has a low iron content and a high nickel content. Therefore, specific leaching and impurity removal processes can be tailored to the magnetic concentrate and the magnetic tail, improving the leaching rate. Since most of the iron in the high-temperature alloy is concentrated in the magnetic concentrate, after leaching, the magnetic concentrate can undergo high-temperature and high-pressure iron removal followed by pH adjustment for impurity removal. This ensures complete iron removal while avoiding the significant cost increase caused by high-temperature and high-pressure iron removal of the entire high-temperature alloy leaching solution. Simultaneously, since most of the nickel in the high-temperature alloy is concentrated in the magnetic tail, with only a small amount of iron present, the magnetic tail can undergo direct pH adjustment for impurity removal after leaching. This ensures effective removal of impurities such as iron while avoiding the high nickel co-precipitation rate, entrainment losses, and the generation of large amounts of colloids that would affect subsequent processes if the entire high-temperature alloy leaching solution were adjusted for impurity removal. Using the aforementioned processing and recycling technology can improve the recovery rate and purity of nickel.

[0016] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following technical solutions.

[0017] As a preferred embodiment of the present invention, the high-temperature alloy includes iron, nickel, and cobalt, and also includes at least one of tungsten, titanium, aluminum, chromium, niobium, molybdenum, or hafnium.

[0018] It should be noted that the high-temperature alloys used in the recycling process described in this invention are typically waste materials that need to be recycled.

[0019] As a preferred embodiment of the present invention, the magnetic field strength of the magnetic separation is 180-220 mT, such as 180 mT, 185 mT, 188 mT, 190 mT, 192 mT, 195 mT, 198 mT, 200 mT, 204 mT, 208 mT, 212 mT, 216 mT or 220 mT, etc., preferably 198-202 mT, and more preferably 200 mT.

[0020] As a preferred embodiment of the present invention, the mass of chromium in the magnetic flux accounts for 40% to 55% of the mass of chromium in the high-temperature alloy, for example, 40%, 41%, 42%, 43%, 45%, 46%, 48%, 49%, 50%, 52%, 53%, 54%, or 55%.

[0021] Preferably, the mass of the magnetic flux accounts for 30% to 40% of the total mass of the high-temperature alloy, for example, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40%.

[0022] Generally speaking, the nickel content in high-temperature alloys is greater than the iron content. For example, nickel accounts for 40% to 60% of the mass, while iron accounts for 20% to 35%. Therefore, after magnetic separation, most of the iron and nickel are separated, resulting in a relatively small amount of magnetic concentrate compared to the magnetic tail, which accounts for about 60% to 70% of the mass of the high-temperature alloy. Thus, removing only a small portion of the magnetic concentrate after high-temperature and high-pressure iron removal can help control costs.

[0023] As a preferred embodiment of the present invention, the acid solutions for both the first acid leaching and the second acid leaching include sulfuric acid.

[0024] Preferably, the acid solution used for the first and second acid leaching is 1.1 to 2.2 times the theoretical amount, for example, 1.1 times, 1.2 times, 1.3 times, 1.4 times, 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times, 2 times, 2.1 times, or 2.2 times.

[0025] Preferably, the temperature of both the first and second acid leaching is 85-95°C, such as 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, 91°C, 92°C, 93°C, 94°C, or 95°C, and the time is 120-360 min, such as 120 min, 140 min, 160 min, 180 min, 200 min, 220 min, 240 min, 260 min, 280 min, 300 min, 320 min, 340 min, or 360 min.

[0026] As a preferred embodiment of the present invention, the concentration of iron in the second leachate is <1g / L, for example, 0.9g / L, 0.8g / L, 0.7g / L, 0.6g / L, 0.5g / L, 0.4g / L, 0.3g / L, 0.2g / L or 0.1g / L.

[0027] Since most of the nickel in the high-temperature alloy is concentrated in the magnet tail, with only a small amount of iron present, the iron concentration in the magnet tail leachate is <1g / L, and pH adjustment can be performed directly to remove impurities.

[0028] As a preferred embodiment of the present invention, the first leaching residue is combined with the magnetic tail for a second acid leaching.

[0029] In this invention, after the magnetic ore undergoes the first acid leaching, most of the iron dissolves in the first leaching solution. The iron content in the first leaching residue is relatively low, with the iron element accounting for less than 1.5% of the mass of the first leaching residue, preferably less than 1%, while the nickel element accounts for 40% to 60% of the mass. This composition and proportion are similar to those of the magnetic tail, so they can be combined with the magnetic tail for the second acid leaching.

[0030] Preferably, the second filter residue is combined with the magnetic flux for the first acid leaching. The nickel content in the second leaching residue is usually low and can be directly discharged.

[0031] As a preferred embodiment of the present invention, the oxidant used in the first oxidation and the second oxidation includes hydrogen peroxide.

[0032] As a preferred embodiment of the present invention, the high-temperature and high-pressure iron removal is carried out at a pH of 1.5 to 3.5, for example, 1.5, 1.8, 2, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, or 3.5. Under pH conditions of 1.5 to 3.5, ferric ions hydrolyze to ferric hydroxide, which, after dehydration, forms ferric oxide.

[0033] Preferably, the temperature of the high-temperature and high-pressure iron removal is 200-230℃, such as 200℃, 203℃, 205℃, 208℃, 210℃, 212℃, 214℃, 217℃, 220℃, 223℃, 225℃, 228℃, or 230℃; the pressure is 2-4MPa, such as 2MPa, 2.3MPa, 2.5MPa, 2.8MPa, 3MPa, 3.3MPa, 3.5MPa, 3.8MPa, or 4MPa; and the time is 1-3h, such as 1h, 1.2h, 1.4h, 1.6h, 1.8h, 2h, 2.2h, 2.4h, 2.6h, 2.8h, or 3h.

[0034] As a preferred technical solution of the present invention, both the first pH adjustment for impurity removal and the second pH adjustment for impurity removal include adjusting the pH to 3.3 to 3.7, such as 3.3, 3.4, 3.5, 3.6 or 3.7, to precipitate iron and chromium, preferably 3.4 to 3.6, and more preferably 3.5.

[0035] Since the magnetic flux undergoes high-temperature and high-pressure iron removal after leaching, and the iron content in the magnetic tail is low, a lower pH of 3.3 to 3.7 is sufficient to achieve the desired impurity removal effect when adjusting the pH, without the need for a higher pH value.

[0036] As a preferred technical solution of the present invention, the method for extracting nickel and cobalt includes extraction.

[0037] It should be noted that, due to space limitations and to avoid redundancy, this invention does not exhaustively list all point values ​​within the above numerical range, but it is not limited to the listed values ​​either; other unlisted values ​​within the above numerical range are also applicable.

[0038] Compared with existing technical solutions, the present invention has at least the following beneficial effects:

[0039] The magnetic separation process for recycling waste high-temperature alloys described in this invention separates the high-temperature alloy into magnetic tails and magnetic concentrate through magnetic separation, effectively solving the problem of low leaching rate when directly leaching all high-temperature alloy powder. High-temperature and high-pressure iron removal only on the magnetic concentrate can effectively reduce costs. Leaching and pH adjustment for impurity removal of the magnetic concentrate and magnetic tails respectively effectively reduces the amount of acid solution and precipitant used compared to directly processing all high-temperature alloy powder, and also reduces the co-precipitation rate of nickel, thus effectively improving the nickel yield. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the process for processing and recycling waste high-temperature alloys using magnetic separation, as described in this embodiment. Detailed Implementation

[0041] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0042] Those skilled in the art will understand that the embodiments described are merely illustrative of the invention and should not be construed as limiting the invention.

[0043] In one or more embodiments of the present invention, the present invention provides a process for the treatment and recycling of waste high-temperature alloys by magnetic separation, the process of which is as follows: Figure 1 As shown, the processing and recycling process includes the following steps:

[0044] Step S1: The high-temperature alloy is subjected to magnetic separation to obtain magnetic concentrate and magnetic tail; the mass of iron in the magnetic concentrate accounts for more than 95% of the mass of iron in the high-temperature alloy, and the mass of nickel in the magnetic concentrate accounts for less than 15% of the mass of nickel in the high-temperature alloy.

[0045] Step S2: The magnetic material is subjected to a first acid leaching to obtain a first leaching solution and a first leaching residue; the first leaching solution is subjected to a first oxidation and high-temperature and high-pressure iron removal to obtain a first filtrate and a first filter residue; the first filtrate is subjected to a first pH adjustment to remove impurities to obtain a third filtrate and a third filter residue.

[0046] Step S3: The magnetic tail is subjected to a second acid leaching to obtain a second leachate and a second leachate residue; the second leachate is subjected to a second oxidation and a second pH adjustment for impurity removal to obtain a second filtrate and a second filter residue.

[0047] Step S4: Combine the second filtrate and the third filtrate to extract nickel and cobalt.

[0048] In some embodiments, in step S1, the high-temperature alloy includes iron, nickel, and cobalt, and also includes at least one of tungsten, titanium, aluminum, chromium, niobium, molybdenum, or hafnium.

[0049] In some implementations, in step S1, the magnetic field strength of the magnetic separation is 180–220 mT.

[0050] In some embodiments, in step S1, the mass of chromium in the magnetic flux accounts for 40% to 55% of the mass of chromium in the high-temperature alloy.

[0051] In some embodiments, in step S1, the mass of the magnetic flux accounts for 30% to 40% of the mass of the high-temperature alloy, which is 100% of the total mass.

[0052] In some embodiments, the acid solution used for the first acid leaching in step S2 and the second acid leaching in step S3 both include sulfuric acid.

[0053] In some embodiments, the acid solution used in the first acid leaching in step S2 and the second acid leaching in step S3 is 1.1 to 2.2 times the theoretical amount.

[0054] In some embodiments, the temperature of the first acid leaching in step S2 and the second acid leaching in step S3 are both 85-95°C, and the time is 120-360 min.

[0055] In some embodiments, the concentration of iron in the second leachate in step S3 is <1 g / L.

[0056] In some embodiments, the first leaching residue in step S2 is combined with the magnetic tail in step S3 for a second acid leaching.

[0057] In some embodiments, the oxidant used in the first oxidation in step S2 and the second oxidation in step S3 includes hydrogen peroxide.

[0058] In some embodiments, the high-temperature and high-pressure iron removal in step S2 is carried out at pH = 1.5 to 3.5.

[0059] In some embodiments, the temperature of the high-temperature and high-pressure iron removal in step S2 is 200-230°C, the pressure is 2-4 MPa, and the time is 1-3 hours.

[0060] In some embodiments, both the first pH adjustment for impurity removal in step S2 and the second pH adjustment for impurity removal in step S3 include adjusting the pH to 3.3-3.7 to precipitate iron and chromium.

[0061] In some implementations, the method for extracting nickel and cobalt in step S4 includes extraction.

[0062] As a further example, in some embodiments, step S1 may involve: separating iron and nickel from high-temperature alloy powder by magnetic separation under a magnetic field strength of 200 mT to obtain magnetic concentrate and magnetic tailings. Table 1 shows the mass content and mass percentage of each component in the high-temperature alloy powder, magnetic concentrate, and magnetic tailings. It can be seen that the mass of iron in the magnetic concentrate accounts for 95.77% of the mass of iron in the high-temperature alloy, and the mass of nickel in the magnetic concentrate accounts for 10.29% of the mass of nickel in the high-temperature alloy; the mass of iron in the magnetic tailings accounts for 2.20% of the mass of iron in the high-temperature alloy, and the mass of nickel in the magnetic concentrate accounts for 87.83% of the mass of nickel in the high-temperature alloy; based on the mass of the high-temperature alloy as 100%, the mass of the magnetic concentrate accounts for 36.42% (i.e., separation efficiency).

[0063] Table 1

[0064]

[0065] In Table 1 and the following tables, taking Fe as an example, Fe concentrate = Fe concentrate / Fe alloy powder; Fe tailings = 1 - Fe tailings / Fe alloy powder.

[0066] As a further example, in some embodiments, step S2 can be performed as follows: 80 mL of concentrated sulfuric acid is diluted to 400 mL, then 50 g of magnetic powder obtained through magnetic separation is weighed, and the magnetic powder is slowly added to the diluted sulfuric acid, the amount of sulfuric acid being 1.5 times the amount of sulfuric acid required for theoretical leaching. The first acid leaching is carried out under water bath heating at 90°C, with stirring for 4 hours. Then, 370 mL of the first leaching solution is obtained by filtration, a certain amount of water-washed residue is added and stirred for 10 minutes, and 325 mL of the first washing liquid is obtained by filtration. The washed residue is then dried in an oven for 3 hours to obtain 2.52 g of the first leaching residue. The results are shown in Table 2, which displays the mass content and mass percentage of each component in the magnetic powder, the first leaching solution, the washing liquid, and the first leaching residue. The leaching rates of Ni, Fe, and Cr are 78.63%, 99.90%, and 98.75%, respectively. The nickel content in the residue is 56.80%, and the iron content is only 1.42%, which can be combined with the magnetic tail.

[0067] Table 2

[0068]

[0069] As a further example, in some embodiments, step S2 can be performed as follows: 95 mL of concentrated sulfuric acid is diluted to 400 mL, then 50 g of magnetic powder obtained through magnetic separation is weighed, and the magnetic powder is slowly added to the diluted sulfuric acid, the amount of sulfuric acid being 1.8 times the amount required for theoretical leaching. The first acid leaching is carried out under water bath heating at 90°C, with stirring for 4 hours. Then, 422 mL of the first leaching solution is obtained by filtration, a certain amount of water-washed residue is added and stirred for 10 minutes, and then filtered to obtain 435 mL of the first washing liquid. The washed residue is dried in an oven for 3 hours to obtain 2.33 g of the first leaching residue. The results are shown in Table 3, which displays the mass content and mass percentage of each component in the magnetic powder, the first leaching solution, the washing liquid, and the first leaching residue. The leaching rates of Ni, Fe, and Cr are 85.50%, 99.94%, and 99.24%, respectively. The nickel content in the residue is 41.68%, and the iron content is only 1.28%, which can be combined into the magnetic tail.

[0070] Table 3

[0071]

[0072] As a further example, in some embodiments, step S2 may also involve: adding excess hydrogen peroxide to the first leachate for a first oxidation to oxidize ferrous iron to ferric iron, then adjusting the pH to 2.5, performing high-temperature and high-pressure iron removal at 200°C and 3.5 MPa, and filtering to obtain a first filtrate and a first filter residue; performing a first pH adjustment to remove impurities from the first filtrate, precipitating iron and chromium at pH 3.5, and filtering to obtain a third filtrate and a third filter residue.

[0073] As a further example, in some embodiments, step S3 can be performed as follows: 77 mL of concentrated sulfuric acid is diluted to 400 mL, then 50 g of magnetic tail powder obtained through magnetic separation is weighed, and the magnetic tail powder is slowly added to the diluted sulfuric acid, the amount of sulfuric acid being 1.5 times the amount of sulfuric acid required for acid leaching. A second acid leaching is carried out under water bath heating at 90°C, with stirring for 4 hours. Then, 323 mL of the second leaching solution is obtained by filtration, and a certain amount of water-washed residue is added and stirred for 10 minutes. After filtration, 281 mL of the second washing solution is obtained. The washed residue is dried in an oven for 3 hours to obtain 9.3 g of the second leaching residue. The results are shown in Table 4, with leaching rates of Ni, Fe, and Cr of 94.05%, 52.99%, and 97.96%, respectively, and a nickel content of 1.79% in the residue.

[0074] Table 4

[0075]

[0076] As a further example, in some embodiments, step S3 can be performed as follows: 90 mL of concentrated sulfuric acid is diluted to 400 mL, then 50 g of magnetic tail powder is weighed and slowly added to the diluted sulfuric acid. The amount of sulfuric acid is 1.7 times the theoretical amount required for leaching. A second acid leaching is carried out under water bath heating at 90°C, with stirring for 4 hours. Then, 446 mL of the second leaching solution is obtained by filtration. A certain amount of water-washed residue is added and stirred for 10 minutes. 370 mL of the second washing solution is obtained by filtration. The washed residue is dried in an oven for 3 hours to obtain 9.3 g of the second leaching residue. The results are shown in Table 5. The leaching rates of Ni, Fe, and Cr are 98.71%, 58.73%, and 100.81%, respectively, and the nickel content in the residue is 1.28%.

[0077] Table 5

[0078]

[0079] As a further example, in some embodiments, step S3 can be performed as follows: 90 mL of concentrated sulfuric acid is diluted to 400 mL, then 50 g of magnetic tail powder is weighed and slowly added to the diluted sulfuric acid. The amount of sulfuric acid is 1.7 times the theoretical amount required for leaching. A second acid leaching is carried out under water bath heating at 90°C, with stirring for 3 hours. Then, 5 g of sodium chlorate is added, and the reaction is continued for another hour. The mixture is then filtered to obtain 405 mL of the second leaching solution. A certain amount of water-washed residue is added and stirred for 10 minutes. The mixture is then filtered to obtain 485 mL of the second washing solution. The washed residue is dried in an oven for 3 hours to obtain 10.6 g of the second leaching residue. The results are shown in Table 6. The leaching rates of Ni, Fe, and Cr are 99.13%, 90.59%, and 102.50%, respectively, and the nickel content in the residue is 0.01%.

[0080] Table 6

[0081]

[0082] As a further example, in some embodiments, step S3 may also involve: taking 100 mL of the second filtrate, heating it in a water bath to 80°C, slowly adding a low-concentration liquid alkali for a second pH adjustment to remove impurities; after adjusting the pH to 3.5, stirring the reaction for 30 min, and then allowing it to settle for 30 min; filtering the solution to obtain 96 mL of the second filtrate; adding a certain amount of water to the residue and washing the residue for 10 min to obtain 174 mL of the fourth washing solution; finally, drying the residue in an oven for 3 h to obtain 7.69 g of the second filter residue. The results are shown in Table 7, with precipitation rates of 99.99% and 97.55% for Fe and Cr, respectively, and a precipitation rate of 14.68% for nickel.

[0083] Table 7

[0084]

[0085] It should be noted that in the above embodiments, steps S2 and S3 can be performed simultaneously without any specific order.

[0086] As a further example, in some embodiments, step S4 can be performed, in which the second filtrate is combined with the third filtrate, and then used to extract nickel and cobalt.

[0087] [Comparative Example]

[0088] This comparative example provides a method for recycling a high-temperature alloy, the recycling method comprising steps T1 and T2:

[0089] Step T1. Dilute 182 mL of concentrated sulfuric acid to 800 mL, then weigh 100 g of high-temperature alloy powder B. Slowly add the high-temperature alloy powder B to the diluted sulfuric acid. The amount of sulfuric acid is 1.8 times the amount required for leaching. Under water bath heating at 90°C, stir and react for 4 hours. Then filter to obtain 730 mL of leaching solution. Add a certain amount of water-washed residue and stir for 10 minutes. Filter to obtain 650 mL of washing solution. Dry the washed residue in an oven for 3 hours to obtain 19.2 g of leaching residue. The results are shown in Table 8. The leaching rates of Ni, Fe, and Cr are 84.2%, 88.74%, and 91.61%, respectively, and the nickel content in the residue is 21.96%.

[0090] Table 8

[0091]

[0092] Alternatively, step T1 is as follows: Dilute 202 mL of concentrated sulfuric acid to 800 mL, then weigh 100 g of high-temperature alloy powder. Slowly add the high-temperature alloy powder to the diluted sulfuric acid, with the amount of sulfuric acid being 2.0 times the amount required for leaching. Under water bath heating at 90°C, stir and react for 4 hours. Then filter to obtain 610 mL of leaching solution. Add a certain amount of water-washed residue and stir for 10 minutes. Filter to obtain 550 mL of washing solution. Dry the washed residue in an oven for 3 hours to obtain 16.7 g of leaching residue. The results are shown in Table 9. The leaching rates of Ni, Fe, and Cr are 89.52%, 90.05%, and 91.76%, respectively, and the nickel content in the residue is 16.12%.

[0093] Table 9

[0094]

[0095] Step T2. Take 100 mL of acid leaching solution, heat it to 80 °C in a water bath, slowly add a low concentration of alkali solution, adjust the pH to remove impurities. When the pH is adjusted to 4.5, stir the reaction for 30 min, then precipitate for 30 min. Filter the solution to obtain 132 mL of purified solution. Add a certain amount of water to the slag, wash the slag for 10 min, and obtain 166 mL of washing solution. Finally, dry the slag in an oven for 3 h to obtain 31.38 g of slag. The results are shown in Table 10. The precipitation rates of Fe and Cr are 99.82% and 99.15%, respectively, and the precipitation rate of nickel is 36.66%.

[0096] Table 10

[0097]

[0098] As can be seen from the above, the magnetic separation and recycling process for waste high-temperature alloys described in this invention effectively solves the problem of low leaching rate when directly leaching all high-temperature alloy powder by separating the high-temperature alloy into magnetic tail and magnetic fines through magnetic separation; high-temperature and high-pressure iron removal only on the magnetic fines can effectively reduce costs; leaching and pH adjustment for impurity removal of the magnetic fines and magnetic tails respectively effectively reduces the amount of acid solution and precipitant used compared to directly treating all high-temperature alloy powder, and the co-precipitation rate of nickel is reduced, thus effectively improving the nickel yield.

[0099] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0100] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0101] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A process for processing and recycling waste high-temperature alloys using magnetic separation, characterized in that, The processing and recycling process includes the following steps: The high-temperature alloy is subjected to magnetic separation to obtain magnetic concentrate and magnetic tail; the mass of iron in the magnetic concentrate accounts for more than 95% of the mass of iron in the high-temperature alloy, and the mass of nickel in the magnetic concentrate accounts for less than 15% of the mass of nickel in the high-temperature alloy. The magnetic material is subjected to a first acid leaching to obtain a first leaching solution and a first leaching residue; the first leaching solution is subjected to a first oxidation and high-temperature and high-pressure iron removal to obtain a first filtrate and a first filter residue; the first filtrate is subjected to a first pH adjustment to remove impurities to obtain a third filtrate and a third filter residue. The magnetic tail is subjected to a second acid leaching to obtain a second leachate and a second leachate residue; the second leachate is then subjected to a second oxidation and a second pH adjustment for impurity removal to obtain a second filtrate and a second filter residue. The second filtrate and the third filtrate are combined to extract nickel and cobalt.

2. The process for processing and recycling waste high-temperature alloys by magnetic separation according to claim 1, characterized in that, The high-temperature alloy includes iron, nickel, and cobalt, and also includes at least one of tungsten, titanium, aluminum, chromium, niobium, molybdenum, or hafnium.

3. The magnetic separation process for treating and recycling waste high-temperature alloys according to claim 1 or 2, characterized in that, The magnetic field strength of the magnetic separation is 180–220 mT.

4. The process for treating and recycling waste high-temperature alloys by magnetic separation according to any one of claims 1-3, characterized in that, The mass of chromium in the magnetic flux accounts for 40% to 55% of the mass of chromium in the high-temperature alloy; Preferably, the magnetic flux accounts for 30% to 40% of the mass of the high-temperature alloy, which is 100% of the total mass.

5. The magnetic separation and recycling process for waste high-temperature alloys according to any one of claims 1-4, characterized in that, The acid solutions for both the first and second acid leaching processes include sulfuric acid; Preferably, the acid solution used for the first and second acid leaching is 1.1 to 2.2 times the theoretical amount. Preferably, the temperature of the first acid leaching and the second acid leaching are both 85-95°C, and the time is 120-360 min; Preferably, the concentration of iron in the second leachate is <1 g / L.

6. The magnetic separation and recycling process for waste high-temperature alloys according to any one of claims 1-5, characterized in that, The first leaching residue is combined with the magnetic tail for a second acid leaching.

7. The magnetic separation process for treating and recycling waste high-temperature alloys according to any one of claims 1-6, characterized in that, The oxidizing agents used in the first oxidation and the second oxidation include hydrogen peroxide.

8. The magnetic separation process for treating and recycling waste high-temperature alloys according to any one of claims 1-7, characterized in that, The high-temperature and high-pressure iron removal is carried out at pH = 1.5 to 3.5; Preferably, the temperature for the high-temperature and high-pressure iron removal is 200–230°C, the pressure is 2–4 MPa, and the time is 1–3 hours.

9. The process for treating and recycling waste high-temperature alloys by magnetic separation according to any one of claims 1-8, characterized in that, Both the first pH adjustment for impurity removal and the second pH adjustment for impurity removal involve adjusting the pH to 3.3–3.7 to precipitate iron and chromium.

10. The process for treating and recycling waste high-temperature alloys by magnetic separation according to any one of claims 1-9, characterized in that, Methods for extracting nickel and cobalt include extraction.

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