Method for recovering refined indium and refined cadmium from cadmium-indium alloy waste

Abstract

The invention relates to the field of rare metal alloy separation and recovery, and provides a method for recovering refined indium and refined cadmium from cadmium-indium alloy waste, and the method mainly comprises the steps of 1, alkali fusion, 2, casting and 3, distillation.The method can avoid the problem that cadmium in the cadmium-indium alloy prepared from the recovered waste is oxidized and evaporated; therefore, the purity and proportion of indium and cadmium in the cadmium-indium alloy are improved, and the recovery rate is further improved; and meanwhile, a safe working environment can be kept, and adverse effects on the body of a worker are avoided.

Description

Technical Field

[0001] The invention relates to the field of separation and recovery of rare alloys, and in particular to a method for recovering refined indium and refined cadmium from cadmium-indium alloy waste. Background Art

[0002] Cadmium and indium are of high value and are widely used in electronics, glass, metallurgy, chemical industry, health care, agriculture and other industries. Cadmium-indium alloy is an alloy material with special properties and application fields. It is usually used in optoelectronic devices, semiconductor devices and other aspects. In the process of producing optical materials, semiconductor devices and other materials, cadmium-indium alloy scraps and waste will be produced. If they are discarded at will, it will cause great economic losses. Therefore, how to recycle cadmium and indium in cadmium-indium alloy waste has become the focus of cost saving.

[0003] CN104047023A discloses a method for producing zinc ingots and recovering indium and cadmium from indium-cadmium-zinc alloy, comprising the following steps: casting a zinc metal alloy containing 0.1-1.0% In, 0.2-2.0% Cd, and 95-99% Zn into an anode, electrolyzing in a zinc sulfate-lithium sulfate mixed solution system to obtain a cathode zinc sheet and an anode mud; melting the cathode zinc sheet to obtain a zinc ingot product; melting the anode mud into a secondary alloy; performing low-temperature distillation on the secondary alloy to obtain a crude cadmium product and a low-cadmium alloy; performing high-temperature distillation on the low-cadmium alloy to obtain a crude indium product and a low-indium alloy, and returning the low-indium alloy for electrolysis treatment. The invention has a short process flow, high production efficiency, low production cost, high comprehensive recovery of indium and cadmium, and a clean and environmentally friendly production process.

[0004] The above patent document melts the separated anode mud into a secondary alloy (cadmium-indium alloy), and then performs low-temperature distillation and high-temperature distillation in sequence to finally obtain an alloy of cadmium and indium. However, the above patent document does not avoid the problem of oxidation and evaporation of cadmium metal in the process of preparing cadmium-indium alloy. However, in practical applications, on the one hand, cadmium metal is extremely easy to be oxidized, which will affect the purity of subsequent purification. On the other hand, due to the high vapor pressure of cadmium metal, there is a risk of evaporation during the melting process. Moreover, cadmium and its compounds are extremely harmful to the human body. After being absorbed by the respiratory tract and digestive tract, they can enter the blood through the alveoli, causing kidney damage mainly with renal tubular lesions. In severe cases, chronic renal failure and osteomalacia and osteoporosis may occur.

[0005] Based on this, the technical problem solved in this case is: how to solve the problem of cadmium oxidation and evaporation when recycling cadmium-indium alloy waste, while purifying high-purity indium. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a method for recovering refined indium and refined cadmium from cadmium-indium alloy waste. The method can avoid the problem of cadmium being oxidized and evaporated in the preparation of cadmium-indium alloy from recycled waste, thereby improving the purity and proportion of indium and cadmium in the cadmium-indium alloy, and then improving the recovery rate; at the same time, it can also maintain a safe working environment and avoid adverse effects on the health of workers.

[0007] The technical solution of the present invention is:

[0008] A method for recovering refined indium and refined cadmium from cadmium-indium alloy waste comprises the following steps:

[0009] Step 1, alkali melting, sequentially putting solid sodium hydroxide and cadmium indium alloy waste into a melting furnace to completely melt, and letting the melt stand, wherein the upper layer of the melt is a by-product and the lower layer is a metal liquid;

[0010] Step 2: Casting, removing by-products, casting the molten metal into a mold to form a cadmium-indium alloy ingot;

[0011] Step 3: distillation, distilling and separating the cadmium-indium alloy ingot to obtain cadmium element and indium element.

[0012] In the above method for recovering refined indium and refined cadmium from cadmium-indium alloy waste, step 1 comprises the following steps:

[0013] Step 11, putting solid sodium hydroxide into a melting furnace to completely melt;

[0014] Step 12, putting the cadmium indium alloy waste into a melting furnace;

[0015] Step 13, homogenizing and stirring the mixture obtained in step 12 to melt the cadmium indium alloy waste to obtain a melt;

[0016] Step 14: The melt is allowed to stand, and the melt is naturally separated into by-products at the upper layer and molten metal at the lower layer.

[0017] In the above method for recovering refined indium and refined cadmium from cadmium-indium alloy waste, step 2 comprises the following steps:

[0018] Step 21, removing the byproducts on the upper layer and retaining part of the byproducts as a protective layer;

[0019] Step 22: pierce the protective layer, and cast the molten metal into a mold to form a cadmium-indium alloy ingot.

[0020] In the above-mentioned method for recovering refined indium and refined cadmium from cadmium-indium alloy waste, in step 21, a by-product with a thickness of 1 to 10 mm, including but not limited to 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, and 10 mm is retained as a protective layer.

[0021] In the above-mentioned method for recovering refined indium and refined cadmium from cadmium-indium alloy waste, before casting in step 2, the melt temperature is cooled to 100°C to 300°C, including but not limited to 100°C, 120°C, 150°C, 170°C, 200°C, 230°C, 250°C, 260°C, 270°C, and 300°C.

[0022] In the above-mentioned method for recovering refined indium and refined cadmium from cadmium-indium alloy waste, the set temperature of the melting furnace in step 1 is 400°C to 500°C, including but not limited to 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C, and 500°C.

[0023] In the above-mentioned method for recovering refined indium and refined cadmium from cadmium-indium alloy waste, the input mass ratio of cadmium-indium alloy waste and solid sodium hydroxide is 10-20, including but not limited to 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20.

[0024] In the above method for recovering refined indium and refined cadmium from cadmium-indium alloy waste, step 3 comprises the following steps:

[0025] Step 31, one-time distillation, loading the cadmium-indium alloy ingot into a graphite boat, and then putting it into a first medium-frequency vacuum distillation furnace, setting the parameters of vacuum degree less than 60 Pa, distillation temperature 800°C to 1100°C, including but not limited to 800°C, 830°C, 850°C, 880°C, 900°C, 920°C, 950°C, 980°C, 1000°C, 1030°C, 1050°C, 1080°C, 1100°C, keeping warm for 2 to 6 hours, including but not limited to 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, to obtain crude indium and 4N refined cadmium;

[0026] Step 32, secondary distillation, the crude indium is loaded into a graphite boat, and then put into a second medium frequency vacuum distillation furnace, under the conditions of setting parameters such as vacuum degree less than 60 Pa, distillation temperature of 1800°C to 2000°C, including but not limited to 1800°C, 1830°C, 1850°C, 1880°C, 1900°C, 1920°C, 1950°C, 1980°C, 2000°C, and heat preservation for 2 to 6 hours, including but not limited to 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, to obtain a first intermediate product and refined indium;

[0027] Step 33, distill three times, load the refined indium into a graphite boat, and then put it into a third medium frequency vacuum distillation furnace, set the parameters as a vacuum degree less than 60 Pa, and a distillation temperature of 2100°C to 2600°C, including but not limited to 2100°C, 2150°C, 2200°C, 2250°C, 2300°C, 2350°C, 2400°C, 2450°C, 2500°C, 2550°C, 2600°C, and keep warm for 2 to 6 hours, including but not limited to 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, to obtain a second intermediate product and high-purity indium.

[0028] In the above-mentioned method for recovering refined indium and refined cadmium from cadmium-indium alloy waste, the first intermediate product in step 32 is recovered and mixed with the next batch of cadmium-indium alloy ingots and step 31 is performed.

[0029] In the above-mentioned method for recovering refined indium and refined cadmium from cadmium-indium alloy waste, the second intermediate product in step 33 is recovered and processed.

[0030] One of the above technical solutions of the present invention has at least one of the following advantages or beneficial effects:

[0031] The present invention recovers waste by alkali melting, which can avoid the problem of cadmium being oxidized and evaporated in the preparation of cadmium-indium alloy from recycled waste, thereby improving the purity and proportion of indium and cadmium in the cadmium-indium alloy, and further improving the recovery rate; at the same time, it can also maintain a safe working environment and avoid adverse effects on the health of workers. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Picture 1 It is a simplified flow chart of Example 1 of the present invention;

[0033] Picture 2 This is a flow chart of Example 9 of the present invention. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Example 1

[0036] like Picture 1 As shown, a method for recovering refined indium and refined cadmium from cadmium-indium alloy waste comprises the following steps:

[0037] Step 1, alkali melting, sequentially putting 1 kg of solid sodium hydroxide and 20 kg of cadmium indium alloy waste into a melting furnace to completely melt, and letting the melt stand, wherein the upper layer of the melt is a by-product and the lower layer is molten metal; wherein the setting temperature of the melting furnace is 430° C.;

[0038] Step 2: Casting, removing by-products, changing the set temperature of the melting furnace to 200° C., allowing the melt to cool naturally to 200° C., and casting the molten metal into a mold to form a cadmium-indium alloy ingot;

[0039] Step 3, distillation, put the cadmium indium alloy ingot cast by alkaline melting into a clean graphite boat, put it into a medium frequency vacuum distillation furnace and place it in the induction area inside the graphite induction ring, turn on the vacuum pump, reduce the vacuum degree in the furnace to 50Pa, set the distillation temperature to 850℃, and keep it warm for 4h.

[0040] After the holding time is over, the heating program is turned off, the vacuum pump is turned off after the temperature is lowered for 2 hours, the indium metal in the graphite boat is taken out, and the distilled cadmium metal is collected for sampling and testing.

[0041] Test results: The purity of cadmium metal reaches 4N standard, and the recovery rate of cadmium metal products is 90%.

[0042] Table 1: Composition of cadmium indium alloy scrap of Example 1 (ppm)

[0043]

[0044]

[0045] Table 2: Cadmium metal impurity content (ppm) of Example 1

[0046] S Bi Fe Pb Cu Ni Na Al 2 2 1 2 1 1 10 1 Ag Mg Se Zinc Cr Ga In Sn 1 1 2 1 1 2 3 2

[0047] Analysis of results: In Example 1, an alkali melting process is performed before casting to prevent oxidation of cadmium metal in the molten state. At the same time, the molten sodium hydroxide will float above the molten metal when standing, which plays a role in inhibiting the evaporation of cadmium metal due to its high vapor pressure, thereby further improving the recovery rate of cadmium metal.

[0048] Example 2

[0049] A method for recovering refined indium and refined cadmium from cadmium-indium alloy waste, it should be noted that this embodiment uses the same batch of cadmium-indium alloy waste as in Example 1, comprising the following steps:

[0050] Step 11, putting 1 kg of solid sodium hydroxide into a melting furnace to completely melt; wherein the setting temperature of the melting furnace is 430°C.

[0051] Step 12, 20 kg of cadmium indium alloy waste is put into the melting furnace in batches. In this embodiment, the feeding amount of each batch is 1 kg and the interval between each feeding is at least 5 seconds;

[0052] Step 13, homogenizing and stirring the mixture obtained in step 12 for 2 hours to completely melt the cadmium indium alloy waste to obtain a melt;

[0053] Step 14, leaving the melt to stand for 2 hours, the melt is naturally separated into by-products at the upper layer and molten metal at the lower layer;

[0054] Step 2: Casting, removing by-products, changing the set temperature of the melting furnace to 200° C., allowing the melt to cool naturally to 200° C., and casting the molten metal into a mold to form a cadmium-indium alloy ingot;

[0055] Step 3, distillation, put the cadmium indium alloy ingot cast by alkaline melting into a clean graphite boat, put it into a medium frequency vacuum distillation furnace and place it in the induction area inside the graphite induction ring, turn on the vacuum pump, reduce the vacuum degree in the furnace to 50Pa, set the distillation temperature to 850℃, and keep it warm for 4h.

[0056] After the holding time is over, the heating program is turned off, the vacuum pump is turned off after the temperature is lowered for 2 hours, the indium metal in the graphite boat is taken out, and the distilled cadmium metal is collected for sampling and testing.

[0057] Test results: The purity of cadmium metal reaches 4N standard, and the recovery rate of cadmium metal products is 92%.

[0058] Table 3: Cadmium metal impurity content (ppm) of Example 2

[0059] S Bi Fe Pb Cu Ni Na Al 2 2 1 1 1 1 8 1 Ag Mg Se Zinc Cr Ga In Sn 1 1 2 1 2 1 3 2

[0060] Result analysis: Compared with Example 1, Example 2 adds cadmium-indium alloy waste in batches, mainly to prevent the phenomenon of bubbling caused by too fast feeding and avoid accidental loss of metal elements. In addition, after the feeding is completed, the melt can be homogenized by continuously stirring the melt, thereby improving the recovery rate of cadmium metal.

[0061] Example 3

[0062] A method for recovering refined indium and refined cadmium from cadmium-indium alloy waste, it should be noted that this embodiment uses the same batch of cadmium-indium alloy waste as in Example 1, comprising the following steps:

[0063] Step 11, putting 1 kg of solid sodium hydroxide into a melting furnace to completely melt; wherein the setting temperature of the melting furnace is 430°C.

[0064] Step 12, 20 kg of cadmium indium alloy waste is put into the melting furnace in batches. In this embodiment, the feeding amount of each batch is 1 kg and the interval between each feeding is at least 5 seconds;

[0065] Step 13, homogenizing and stirring the mixture obtained in step 12 for 2 hours to completely melt the cadmium indium alloy waste to obtain a melt;

[0066] Step 14, leaving the melt to stand for 2 hours, the melt is naturally separated into by-products at the upper layer and molten metal at the lower layer;

[0067] Step 21, remove the upper layer of byproducts and retain 2 mm thick byproducts as a protective layer;

[0068] Step 22: Change the set temperature of the melting furnace to 200° C., allow the melt to cool naturally to 200° C., break through the protective layer, and cast the molten metal into a mold to obtain a cadmium-indium alloy ingot.

[0069] Step 3, distillation, put the cadmium indium alloy ingot cast by alkaline melting into a clean graphite boat, put it into a medium frequency vacuum distillation furnace and place it in the induction area inside the graphite induction ring, turn on the vacuum pump, reduce the vacuum degree in the furnace to 50Pa, set the distillation temperature to 850℃, and keep it warm for 4h.

[0070] After the holding time is over, the heating program is turned off, the vacuum pump is turned off after the temperature is lowered for 2 hours, the indium metal in the graphite boat is taken out, and the distilled cadmium metal is collected for sampling and testing.

[0071] Test results: The purity of cadmium metal reaches 4N standard, and the recovery rate of cadmium metal products is 95%.

[0072] Table 4: Cadmium metal impurity content (ppm) of the purified samples in Example 3

[0073]

[0074]

[0075] Result analysis: Compared with Example 2, Example 3 retains part of the by-product of the upper layer as a protective layer. In actual production, the protective layer will form a film after cooling. After testing, it is speculated that indium is slightly soluble in sodium hydroxide at high temperature and is generated. By retaining the protective layer, the entire process from melting to casting prevents cadmium from being easily evaporated and oxidized at high temperatures.

[0076] Example 4

[0077] It is basically the same as Example 3, except that in step 21, a 1 mm thick by-product is retained as a protective layer.

[0078] Example 5

[0079] It is basically the same as Example 3, except that in step 21, a 5 mm thick by-product is retained as a protective layer.

[0080] Example 6

[0081] It is basically the same as Example 3, except that in step 21, a 10 mm thick by-product is retained as a protective layer.

[0082] Result analysis: There is no significant difference in the test results when comparing Examples 4 to 6. However, considering the difficulty of removing by-products and casting, the method of retaining 2 mm in Example 4 is a better choice, and the indium recovery rate is also higher.

[0083] Example 7

[0084] It is basically the same as Example 3, except that the setting temperature of the melting furnace in step 1 is 400°C, and before the casting in step 2, the melt temperature is cooled to 300°C.

[0085] Example 8

[0086] It is basically the same as Example 3, except that the setting temperature of the melting furnace in step 1 is 500°C, and before the casting in step 2, the melt temperature is cooled to 100°C.

[0087] Example 9

[0088] like Picture 2 , a method for recovering refined indium and refined cadmium from cadmium-indium alloy waste is shown. It should be noted that this embodiment uses the same batch of cadmium-indium alloy waste as in Example 1, and includes the following steps:

[0089] Step 11, putting 1 kg of solid sodium hydroxide into a melting furnace to completely melt; wherein the setting temperature of the melting furnace is 430°C.

[0090] Step 12, 20 kg of cadmium indium alloy waste is put into the melting furnace in batches. In this embodiment, the feeding amount of each batch is 1 kg and the interval between each feeding is at least 5 seconds;

[0091] Step 13, homogenizing and stirring the mixture obtained in step 12 for 2 hours to completely melt the cadmium indium alloy waste to obtain a melt;

[0092] Step 14, leaving the melt to stand for 2 hours, the melt is naturally separated into by-products at the upper layer and molten metal at the lower layer;

[0093] Step 21, remove the by-product on the upper layer and keep the by-product with a thickness of 1 mm as a protective layer;

[0094] Step 22: Change the set temperature of the melting furnace to 200° C., allow the melt to cool naturally to 200° C., break through the protective layer, and cast the molten metal into a mold to obtain a cadmium-indium alloy ingot.

[0095] Step 31, one distillation, put the cadmium indium alloy ingot cast by alkaline melting into a clean graphite boat, put it into the first medium frequency vacuum distillation furnace and place it in the induction area inside the graphite induction ring, turn on the vacuum pump, reduce the vacuum degree in the furnace to 50Pa, set the distillation temperature to 850℃, and keep it warm for 4h.

[0096] After the holding time is over, the heating program is turned off, the vacuum pump is turned off after the temperature is lowered for 2 hours, the crude indium in the graphite boat is taken out, and the distilled cadmium metal is collected;

[0097] Step 32, secondary distillation, the crude indium is loaded into a graphite boat, placed in the second medium frequency vacuum distillation furnace and placed in the induction area inside the graphite induction ring, the vacuum pump is turned on, the vacuum degree in the furnace is reduced to 50Pa, the distillation temperature is set to 1800°C, and the temperature is kept for 3 hours. The main purpose is to remove low-boiling point metal impurities.

[0098] After the holding time is over, the heating program is turned off, the vacuum pump is turned off after the temperature is lowered for 3 hours, the first intermediate product distilled out is collected, and the refined indium in the graphite boat is taken out;

[0099] Step 33, three distillations, put the refined indium into a graphite boat, put it into the third medium frequency vacuum distillation furnace and place it in the induction area inside the graphite induction ring, turn on the vacuum pump, reduce the vacuum degree in the furnace to 50Pa, set the distillation temperature to 2200℃, and keep it warm for 3h. The main purpose is to remove high boiling point metal impurities.

[0100] After the insulation time is over, the heating program is turned off, the vacuum pump is turned off after the temperature is lowered for 3 hours, the second intermediate product distilled is collected, the high-purity indium in the graphite boat is taken out, and the high-purity indium collected by distillation is sampled and tested.

[0101] Test results: The purity of high-purity indium reaches 4N standard, and the recovery rate of indium metal products is 95%.

[0102] In this embodiment, the first intermediate product in step 32 is recovered and mixed with the next batch of cadmium indium alloy ingots and step 31 is performed.

[0103] In this embodiment, the second intermediate product in step 33 is recovered and processed.

[0104] Table 5: Impurity content of high purity indium in Example 9 (ppm)

[0105]

[0106]

[0107] Example 10

[0108] It is basically the same as Example 9, except that the set distillation temperature of step 31, the first distillation is 800°C; the set distillation temperature of step 32, the second distillation is 1800°C; and the set distillation temperature of step 33, the third distillation is 2100°C.

[0109] The high-purity indium produced by distillation is sampled and tested.

[0110] Test results: The purity of high-purity indium reaches 4N standard, and the recovery rate of indium metal products is 95%.

[0111] Embodiment 11

[0112] It is basically the same as Example 9, except that the set distillation temperature of step 31, the first distillation is 1100°C; the set distillation temperature of step 32, the second distillation is 2000°C; and the set distillation temperature of step 33, the third distillation is 2600°C.

[0113] The high-purity indium produced by distillation is sampled and tested.

[0114] Test results: The purity of high-purity indium reaches 4N standard, and the recovery rate of indium metal products is 95%.

[0115] Comparative Example 1

[0116] Using the same batch of cadmium indium alloy waste as in Example 1, 20 kg of cadmium indium alloy waste was directly put into a melting furnace at 430°C for complete melting, and then the melt was naturally cooled to 200°C, and the molten metal was cast into a mold to form a cadmium indium alloy ingot, and the alkali-melting cast cadmium indium alloy ingot was loaded into a clean graphite boat, put into a medium-frequency vacuum distillation furnace and placed in the induction area inside the graphite induction ring, the vacuum pump was turned on, the vacuum degree in the furnace was reduced to 50 Pa, the distillation temperature was set to 850°C, and the mixture was kept warm for 4 hours.

[0117] After the holding time is over, the heating program is turned off, the vacuum pump is turned off after the temperature is lowered for 2 hours, the indium metal in the graphite boat is taken out, and the distilled cadmium metal is collected for sampling and testing.

[0118] Test results: The purity of cadmium metal reaches 4N standard, and the recovery rate of cadmium metal products is 72%.

[0119] Result analysis: Cadmium was oxidized and evaporated, causing a large amount of loss and resulting in a decrease in product recovery rate.

[0120] Comparative Example 2

[0121] A method for recovering refined indium and refined cadmium from cadmium-indium alloy waste comprises the following steps:

[0122] Step 11, putting 1 kg of solid sodium hydroxide into a melting furnace for complete melting; wherein the setting temperature of the melting furnace is 430° C., and the composition of the cadmium-indium alloy waste is 92.4% of cadmium, 7.39% of indium and other impurities.

[0123] Step 12, 20 kg of cadmium indium alloy waste is put into the melting furnace in batches. In this embodiment, the feeding amount of each batch is 1 kg and the interval between each feeding is at least 5 seconds;

[0124] Step 13, homogenizing and stirring the mixture obtained in step 12 for 2 hours to completely melt the cadmium indium alloy waste to obtain a melt;

[0125] Step 14, leaving the melt to stand for 2 hours, the melt is naturally separated into by-products at the upper layer and molten metal at the lower layer;

[0126] Step 21, remove the by-product on the upper layer and keep the by-product with a thickness of 1 mm as a protective layer;

[0127] Step 22: Change the set temperature of the melting furnace to 200° C., allow the melt to cool naturally to 200° C., break through the protective layer, and cast the molten metal into a mold to obtain a cadmium-indium alloy ingot.

[0128] Step 31, one distillation, put the cadmium indium alloy ingot cast by alkaline melting into a clean graphite boat, put it into the first medium frequency vacuum distillation furnace and place it in the induction area inside the graphite induction ring, turn on the vacuum pump, reduce the vacuum degree in the furnace to 50Pa, set the distillation temperature to 850℃, and keep it warm for 4h.

[0129] After the holding time is over, the heating program is turned off, the vacuum pump is turned off after the temperature is lowered for 2 hours, the crude indium in the graphite boat is taken out, and the distilled cadmium metal is collected;

[0130] Step 32, secondary distillation, put the crude indium into a graphite boat, put it into the second medium frequency vacuum distillation furnace and place it in the induction area inside the graphite induction ring, turn on the vacuum pump, reduce the vacuum degree in the furnace to 50Pa, set the distillation temperature to 1400℃, and keep it warm for 3h.

[0131] After the holding time is over, the heating program is turned off, the vacuum pump is turned off after the temperature is lowered for 3 hours, the distilled first intermediate product is collected, and the refined indium in the graphite boat is taken out and sampled for detection.

[0132] Test results: refined indium does not meet the 4N standard.

[0133] Table 6: Detection results of refined indium in Comparative Example 2 (ppm)

[0134] S Bi Fe Pb Cu Ni Na Al 2 34 2 138 5 652 2 1 Ag Mg Se Zinc Cr Ga CD Sn 1 1 1 2 1 1 1 59

[0135] Result analysis: When the distillation temperature was 1400℃, the low-boiling point impurities were not completely distilled out and the impurity content was relatively high.

[0136] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for recovering refined indium and refined cadmium from cadmium-indium alloy waste, characterized in that: The steps include: Step 1, alkali melting, sequentially putting solid sodium hydroxide and cadmium indium alloy waste into a melting furnace to completely melt, and letting the melt stand, wherein the upper layer of the melt is a by-product and the lower layer is a metal liquid; Step 2: Casting, removing by-products, casting the molten metal into a mold to form a cadmium-indium alloy ingot; Step 3: distillation, distilling and separating the cadmium-indium alloy ingot to obtain cadmium element and indium element.

2. The method for recovering refined indium and refined cadmium from cadmium-indium alloy waste according to claim 1, characterized in that: The step 1 comprises the following steps: Step 11, putting solid sodium hydroxide into a melting furnace to completely melt; Step 12, putting the cadmium indium alloy waste into a melting furnace; Step 13, homogenizing and stirring the mixture obtained in step 12 to melt the cadmium indium alloy waste to obtain a melt; Step 14: The melt is allowed to stand, and the melt is naturally separated into by-products at the upper layer and molten metal at the lower layer.

3. The method for recovering refined indium and refined cadmium from cadmium-indium alloy waste according to claim 1, characterized in that: The step 2 comprises the following steps: Step 21, removing the byproducts on the upper layer and retaining part of the byproducts as a protective layer; Step 22: pierce the protective layer, and cast the molten metal into a mold to form a cadmium-indium alloy ingot.

4. The method for recovering refined indium and refined cadmium from cadmium-indium alloy waste according to claim 3, characterized in that: In the step 21, a byproduct with a thickness of 1 to 10 mm is retained as a protective layer.

5. The method for recovering refined indium and refined cadmium from cadmium-indium alloy waste according to claim 1, characterized in that: Before performing the casting in step 2, the melt temperature is cooled to 100°C to 300°C.

6. The method for recovering refined indium and refined cadmium from cadmium-indium alloy waste according to claim 1, characterized in that: The setting temperature of the melting furnace in step 1 is 400°C to 500°C.

7. The method for recovering refined indium and refined cadmium from cadmium-indium alloy waste according to claim 1, characterized in that: The input mass ratio of the cadmium-indium alloy waste and the solid sodium hydroxide is 10-20.

8. The method for recovering refined indium and refined cadmium from cadmium-indium alloy waste according to claim 1, characterized in that: The step 3 comprises the following steps: Step 31, primary distillation, loading the cadmium-indium alloy ingot into a graphite boat, and then putting it into a first medium-frequency vacuum distillation furnace, under the conditions of setting parameters such as vacuum degree less than 60 Pa and distillation temperature of 800° C. to 1100° C., keeping the temperature for 2 to 6 hours, to obtain crude indium and 4N refined cadmium; Step 32, secondary distillation, the crude indium is loaded into a graphite boat, and then put into a second medium frequency vacuum distillation furnace, under the conditions of setting parameters such as vacuum degree less than 60 Pa and distillation temperature of 1800° C. to 2000° C., the temperature is kept for 2 to 6 hours to obtain a first intermediate product and refined indium; Step 33, distill three times, put the refined indium into a graphite boat, and then put it into a third medium frequency vacuum distillation furnace. Under the conditions of setting the vacuum degree less than 60 Pa and the distillation temperature of 2100°C to 2600°C, keep it warm for 2 to 6 hours to obtain a second intermediate product and high-purity indium.

9. The method for recovering refined indium and refined cadmium from cadmium-indium alloy waste according to claim 8, characterized in that: The first intermediate product in step 32 is recovered and distilled again with the next batch of cadmium indium alloy ingots.

10. The method for recovering refined indium and refined cadmium from cadmium-indium alloy waste according to claim 8, characterized in that: The second intermediate product in step 33 is recovered and processed.

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