Method for recovering indium from indium-containing wastewater

Abstract

The invention discloses a method for recovering indium from indium-containing wastewater, which belongs to the technical field of resource recycling and reutilization, and comprises the following steps: adding zinc powder into the indium-containing wastewater, reacting under ultrasound, filtering, washing and drying to obtain a precipitate; loading the precipitate into a tubular furnace, introducing hydrogen, carrying out first heat treatment, and then carrying out second heat treatment to obtain an indium alloy; uniformly mixing indium alloy and fused salt, and smelting to obtain an alloy ingot; performing vacuum distillation on the alloy ingot to obtain an indium ingot; and carrying out electrolysis by taking an indium ingot as an anode, a titanium plate as a cathode and indium-containing liquid as electrolyte to obtain refined indium. According to the method, the indium-containing wastewater is subjected to replacement, precipitation and replacement of metal indium under the ultrasonic action, then the indium metal is subjected to high-temperature reduction purification through two times of heat treatment in the presence of hydrogen, indium is purified into refined indium through fused salt smelting distillation and electrolytic refining, the process is short, operation is easy, and the cost is low.

Description

Technical Field

[0001] The present invention relates to the technical field of resource recovery and reuse, and particularly relates to a method for recovering indium from indium-containing wastewater. Background Art

[0002] Indium, a kind of rare and dispersed metal, about 70% of the global indium metal is used in the preparation of ITO targets, and is widely used in fields such as flat panel displays, information materials, aerospace, and national defense. However, when the ITO target is sputter-coated on glass, the utilization rate is less than 30%. During the production process, corner materials, cut materials, etc. will also be generated, leaving a large amount of ITO waste targets.

[0003] Facing the problems of scarce indium primary ore and increasing indium metal prices, the comprehensive recovery of indium resources is required. In the production process of ITO targets, cleaning before forming is a key step. The main purpose of cleaning is to remove impurities, oxides, oil stains, manual residues or other pollutants in the raw material powder to ensure the smooth surface of the target and avoid impurities affecting the performance of the target. During the cleaning process, cleaning waste liquid will inevitably be generated, and the cleaning waste liquid (i.e., indium-containing wastewater) will inevitably contain indium and other metal elements. Therefore, recovering indium from indium-containing wastewater can alleviate the problems of scarce indium primary ore and increasing indium metal prices to a certain extent. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for recovering indium from indium-containing wastewater, which can effectively recover indium in indium-containing wastewater and improve the purity of indium.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A method for recovering indium from indium-containing wastewater, comprising the following steps:

[0007] Adding zinc powder to indium-containing wastewater, reacting under ultrasonic waves, filtering, washing, and drying to obtain a precipitate;

[0008] Loading the precipitate into a tubular furnace, introducing hydrogen, performing a first heat treatment, and then performing a second heat treatment to obtain an indium alloy;

[0009] Mixing the indium alloy and molten salt evenly, melting to obtain an alloy ingot;

[0010] Performing vacuum distillation on the alloy ingot to obtain an indium ingot;

[0011] Using the indium ingot as the anode, a titanium plate as the cathode, and an indium-containing solution as the electrolyte, and performing electrolysis to obtain refined indium.

[0012] In this invention, indium-containing wastewater is used to displace and precipitate indium metal under ultrasonic action to improve the reaction rate, enabling indium to have more sufficient solid-liquid contact during zinc powder displacement. Then, indium metal is purified by high-temperature reduction through two heat treatments under hydrogen, allowing hydrogen to fully react with indium to remove impurity elements. After molten salt smelting, distillation, and electrolytic refining, indium is purified to refined indium. The process is short, the operation is simple, and the cost is low.

[0013] Among them, the indium-containing wastewater is the wastewater generated during the production of ITO targets.

[0014] Among them, the content of indium in the indium-containing wastewater is 0.5 - 1 g / L.

[0015] As a preferred embodiment of this invention, the concentrations of the main elements in the indium-containing wastewater are In 0.5 - 1 g / L, Sn 0.08 - 0.17 g / L, Fe 0.03 - 0.1 g / L, Cu 0.1 - 0.5 g / L, Zn 5.1 - 7.9 g / L, and Ni 0.04 - 0.1 g / L. The recovery method of this invention has better effects especially for indium-containing wastewater with main components within this range, and can better remove impurity elements.

[0016] As a preferred embodiment of this invention, the solid-liquid ratio of the zinc powder to the indium-containing wastewater is (10 - 20) g : 1 L;

[0017] The power of the ultrasonic wave is 50 - 100 W, the temperature during the reaction under ultrasonic wave is 30 - 50 °C, and the time is 2 - 6 h.

[0018] As a preferred embodiment of this invention, the input amount of hydrogen is 4 - 6 L / min.

[0019] As a preferred embodiment of this invention, the temperature of the first heat treatment is 300 - 450 °C, and the time is 2 - 6 h;

[0020] The temperature of the second heat treatment is 600 - 800 °C, and the time is 2 - 6 h.

[0021] This invention adopts two heat treatments, which can effectively improve the recovery effect. Among them, the first heat treatment is mainly to remove crystal water and make the alloy in a molten state, and the second heat treatment is to enable hydrogen to better react with the indium alloy and remove the oxygen element therein, thereby purifying indium metal.

[0022] As a preferred embodiment of this invention, the mass ratio of the indium alloy to the molten salt is 100 : (5 - 10).

[0023] As a preferred embodiment of this invention, the molten salt includes at least one of calcium oxide, sodium nitrate, sodium borate, quartz, and borax.

[0024] As a preferred embodiment of the present invention, the temperature of the smelting is 300 - 400 °C, and the smelting time is 1 - 2 h.

[0025] As a preferred embodiment of the present invention, the temperature of the vacuum distillation is 900 - 1100 °C, and the time is 4 - 6 h.

[0026] As a preferred embodiment of the present invention, the current density of the electrolysis is 80 - 100 A / m 2 , the temperature is 20 - 25 °C, and the voltage is 0.1 - 0.25 V.

[0027] As a preferred embodiment of the present invention, the indium-containing solution comprises the following components: indium sulfate at 80 - 120 g / L, sodium chloride at 80 - 85 g / L, gelatin at 0.2 - 0.3 g / L, and thiourea at 0.05 - 0.1 g / L.

[0028] The beneficial effects of the present invention are as follows: The present invention displaces and precipitates metallic indium from indium-containing wastewater under the action of ultrasound, and then undergoes two heat treatments under hydrogen for high-temperature reduction and purification of indium metal. Through molten salt smelting, distillation, and electrolytic refining, indium is purified to refined indium. The process is short, the operation is simple, and the cost is relatively low. Detailed implementation manners

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. Apparently, the described embodiments are some, but not all, of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present application.

[0030] In the present application, for the technical features described in an open-ended manner, it includes a closed technical solution composed of the listed features, and also includes an open technical solution containing the listed features.

[0031] In the present application, regarding the numerical range, unless otherwise specified, the above numerical range is considered continuous, and includes the minimum and maximum values of this range, as well as each value between such minimum and maximum values. Further, when the range refers to an integer, it includes each integer between the minimum and maximum values of this range. In addition, when providing multiple ranges to describe features or characteristics, these ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0032] In the present application, there is no particular limitation on the specific dispersion and stirring treatment methods.

[0033] Unless otherwise specified, the component raw materials or instruments used in the embodiments and comparative examples of the present invention are all commercially available raw materials or instruments, and the component raw materials used in each parallel experiment are of the same kind.

[0034] The following examples are provided to facilitate the understanding of the present invention. These examples are not provided to limit the scope of the claims.

[0035] Example 1

[0036] A method for recovering indium from indium-containing wastewater, comprising the following steps:

[0037] (1) Add zinc powder to indium-containing wastewater, react at 40 °C for 4 h under 100 W ultrasound, filter, wash, and dry to obtain a precipitate;

[0038] The solid-liquid ratio of the zinc powder to the indium-containing wastewater is 15 g: 1 L;

[0039] The main element concentrations of the indium-containing wastewater are In 0.65 / L, Sn 0.15 g / L, Fe 0.08 g / L, Cu 0.12 g / L, Zn 6.22 g / L, and Ni 0.05 g / L.

[0040] (2) Load the precipitate into a tubular furnace with a quartz tube, introduce hydrogen at a rate of 5 L / min, perform heat treatment at 450 °C for 4 h, and then perform heat treatment at 600 °C for 4 h to obtain an indium alloy;

[0041] (3) Mix the indium alloy and calcium oxide evenly according to a mass ratio of 100:10, melt at 400 °C for 1 h, remove the surface scum, and cool to obtain an alloy ingot;

[0042] (4) Place the alloy ingot in a graphite crucible, put it into a vacuum distillation furnace, perform vacuum distillation at a vacuum degree of 1 Pa, the temperature of the vacuum distillation is 1100 °C, and the time is 5 h to obtain an indium ingot;

[0043] (5) Use the indium ingot as the anode, a titanium plate as the cathode, and an indium-containing solution as the electrolyte to perform electrolysis to obtain refined indium.

[0044] The current density of the electrolysis is 90 A / m 2 , the temperature is 20 °C, and the voltage is 0.2 V.

[0045] The indium-containing solution includes the following components: 80 g / L of indium sulfate, 85 g / L of sodium chloride, 0.2 g / L of gelatin, and 0.1 g / L of thiourea.

[0046] Example 2

[0047] A method for recovering indium from indium-containing wastewater, comprising the following steps:

[0048] (1) Add zinc powder to the indium-containing wastewater. Under 100 W ultrasonic wave, react at 40 °C for 4 h, filter, wash, and dry to obtain a precipitate.

[0049] The solid-liquid ratio of the zinc powder to the indium-containing wastewater is 15 g:1 L.

[0050] The main element concentrations in the indium-containing wastewater are In 0.65 / L, Sn 0.15 g / L, Fe 0.08 g / L, Cu 0.12 g / L, Zn 6.22 g / L, and Ni 0.05 g / L.

[0051] (2) Load the precipitate into a quartz tube and place it in a tube furnace. Pass hydrogen at a rate of 5 L / min, perform heat treatment at 300 °C for 4 h, and then perform heat treatment at 800 °C for 4 h to obtain an indium alloy.

[0052] (3) Mix the indium alloy and calcium oxide evenly according to a mass ratio of 100:10, melt at 400 °C for 1 h, remove the surface scum, and cool to obtain an alloy ingot.

[0053] (4) Place the alloy ingot in a graphite crucible, put it into a vacuum distillation furnace, perform vacuum distillation at a vacuum degree of 1 Pa, the temperature of the vacuum distillation is 1100 °C, and the time is 5 h to obtain an indium ingot.

[0054] (5) Use the indium ingot as the anode, a titanium plate as the cathode, and an indium-containing solution as the electrolyte to perform electrolysis to obtain refined indium.

[0055] The current density of the electrolysis is 90 A / m 2 , the temperature is 20 °C, and the voltage is 0.2 V.

[0056] The indium-containing solution includes the following components: indium sulfate 80 g / L, sodium chloride 85 g / L, gelatin 0.2 g / L, and thiourea 0.1 g / L.

[0057] Example 3

[0058] A method for recovering indium from indium-containing wastewater, comprising the following steps:

[0059] (1) Add zinc powder to the indium-containing wastewater. Under 100 W ultrasonic wave, react at 40 °C for 4 h, filter, wash, and dry to obtain a precipitate.

[0060] The solid-liquid ratio of the zinc powder to the indium-containing wastewater is 15 g:1 L.

[0061] The main element concentrations in the indium-containing wastewater are In 0.65 / L, Sn 0.15 g / L, Fe 0.08 g / L, Cu 0.12 g / L, Zn 6.22 g / L, and Ni 0.05 g / L.

[0062] (2) Load the precipitate into a tube furnace using a quartz tube, introduce hydrogen at a rate of 5 L / min, perform heat treatment at 450 °C for 4 h, and then perform heat treatment at 600 °C for 4 h to obtain an indium alloy;

[0063] (3) Mix the indium alloy and calcium oxide evenly according to a mass ratio of 100:5, melt at 400 °C for 1 h, remove the surface scum, and cool to obtain an alloy ingot;

[0064] (4) Place the alloy ingot in a graphite crucible, put it into a vacuum distillation furnace, perform vacuum distillation at a vacuum degree of 1 Pa, the temperature of the vacuum distillation is 1100 °C, and the time is 5 h to obtain an indium ingot;

[0065] (5) Use the indium ingot as the anode, the titanium plate as the cathode, and the indium-containing solution as the electrolyte to perform electrolysis to obtain refined indium.

[0066] The current density of the electrolysis is 90 A / m 2 , the temperature is 20 °C, and the voltage is 0.2 V.

[0067] The indium-containing solution includes the following components: indium sulfate at 80 g / L, sodium chloride at 85 g / L, gelatin at 0.2 g / L, and thiourea at 0.1 g / L.

[0068] Example 4

[0069] A method for recovering indium from indium-containing wastewater, comprising the following steps:

[0070] (1) Add zinc powder to the indium-containing wastewater, react at 40 °C for 4 h under 100 W ultrasonic, filter, wash, and dry to obtain a precipitate;

[0071] The solid-liquid ratio of the zinc powder to the indium-containing wastewater is 15 g:1 L;

[0072] The main element concentrations of the indium-containing wastewater are In 0.65 / L, Sn 0.15 g / L, Fe 0.08 g / L, Cu 0.12 g / L, Zn 6.22 g / L, and Ni 0.05 g / L.

[0073] (2) Load the precipitate into a tube furnace using a quartz tube, introduce hydrogen at a rate of 5 L / min, perform heat treatment at 450 °C for 4 h, and then perform heat treatment at 600 °C for 4 h to obtain an indium alloy;

[0074] (3) Mix the indium alloy and calcium oxide evenly according to a mass ratio of 100:10, melt at 300 °C for 2 h, remove the surface scum, and cool to obtain an alloy ingot;

[0075] (4) Place the alloy ingot in a graphite crucible and put it into a vacuum distillation furnace. Carry out vacuum distillation at a vacuum degree of 1 Pa, with the temperature of vacuum distillation being 1100 °C and the time being 5 h to obtain indium ingots;

[0076] (5) Use the indium ingot as the anode, the titanium plate as the cathode, and the indium-containing solution as the electrolyte to carry out electrolysis to obtain refined indium.

[0077] The current density of the electrolysis is 90 A / m 2 , the temperature is 20 °C, and the voltage is 0.2 V.

[0078] The indium-containing solution includes the following components: indium sulfate at 80 g / L, sodium chloride at 85 g / L, gelatin at 0.2 g / L, and thiourea at 0.1 g / L.

[0079] Example 5

[0080] A method for recovering indium from indium-containing wastewater, comprising the following steps:

[0081] (1) Add zinc powder to the indium-containing wastewater, react at 40 °C under 100 W ultrasonic for 4 h, filter, wash, and dry to obtain a precipitate;

[0082] The solid-liquid ratio of the zinc powder to the indium-containing wastewater is 15 g:1 L;

[0083] The main element concentrations of the indium-containing wastewater are In 0.65 / L, Sn 0.15 g / L, Fe 0.08 g / L, Cu 0.12 g / L, Zn 6.22 g / L, and Ni 0.05 g / L.

[0084] (2) Load the precipitate into a tubular furnace with a quartz tube, introduce hydrogen at a rate of 5 L / min, carry out heat treatment at 450 °C for 4 h, and then carry out heat treatment at 600 °C for 4 h to obtain an indium alloy;

[0085] (3) Mix the indium alloy and calcium oxide evenly according to a mass ratio of 100:10, melt at 400 °C for 1 h, remove the surface scum, and cool to obtain an alloy ingot;

[0086] (4) Place the alloy ingot in a graphite crucible and put it into a vacuum distillation furnace. Carry out vacuum distillation at a vacuum degree of 1 Pa, with the temperature of vacuum distillation being 900 °C and the time being 6 h to obtain indium ingots;

[0087] (5) Use the indium ingot as the anode, the titanium plate as the cathode, and the indium-containing solution as the electrolyte to carry out electrolysis to obtain refined indium.

[0088] The current density of the electrolysis is 90 A / m 2 , the temperature is 20 °C, and the voltage is 0.2 V.

[0089] The indium-containing solution includes the following components: indium sulfate at 80 g / L, sodium chloride at 85 g / L, gelatin at 0.2 g / L, and thiourea at 0.1 g / L.

[0090] Example 6

[0091] A method for recovering indium from indium-containing wastewater includes the following steps:

[0092] (1) Add zinc powder to the indium-containing wastewater, react at 40 °C for 4 h under 100 W ultrasound, filter, wash, and dry to obtain a precipitate.

[0093] The solid-liquid ratio of the zinc powder to the indium-containing wastewater is 15 g:1 L.

[0094] The main element concentrations in the indium-containing wastewater are In 0.65 / L, Sn 0.15 g / L, Fe 0.08 g / L, Cu 0.12 g / L, Zn 6.22 g / L, and Ni 0.05 g / L.

[0095] (2) Load the precipitate into a quartz tube and place it in a tube furnace, introduce hydrogen at a rate of 5 L / min, perform heat treatment at 450 °C for 4 h, and then perform heat treatment at 600 °C for 4 h to obtain an indium alloy.

[0096] (3) Mix the indium alloy and calcium oxide evenly according to a mass ratio of 100:10, melt at 400 °C for 1 h, remove the surface scum, and cool to obtain an alloy ingot.

[0097] (4) Place the alloy ingot in a graphite crucible, put it into a vacuum distillation furnace, perform vacuum distillation at a vacuum degree of 1 Pa, the temperature of the vacuum distillation is 1100 °C, and the time is 5 h to obtain an indium ingot.

[0098] (5) Use the indium ingot as the anode, a titanium plate as the cathode, and the indium-containing solution as the electrolyte to perform electrolysis to obtain refined indium.

[0099] The current density of the electrolysis is 90 A / m 2 , the temperature is 20 °C, and the voltage is 0.2 V.

[0100] The indium-containing solution includes the following components: indium sulfate at 120 g / L, sodium chloride at 80 g / L, gelatin at 0.3 g / L, and thiourea at 0.05 g / L.

[0101] Comparative Example 1

[0102] A method for recovering indium from indium-containing wastewater includes the following steps:

[0103] (1) Add zinc powder to the indium-containing wastewater, react at 40 °C for 4 h under 100 W ultrasound, filter, wash, and dry to obtain a precipitate.

[0104] The solid-liquid ratio of the zinc powder to the indium-containing wastewater is 15 g: 1 L;

[0105] The main element concentrations in the indium-containing wastewater are In 0.65 g / L, Sn 0.15 g / L, Fe 0.08 g / L, Cu 0.12 g / L, Zn 6.22 g / L, and Ni 0.05 g / L.

[0106] (2) Mix the precipitate and calcium oxide evenly according to a mass ratio of 100:10, melt at 400 °C for 1 h, remove the surface scum, and cool to obtain an alloy ingot;

[0107] (3) Place the alloy ingot in a graphite crucible and put it into a vacuum distillation furnace. Carry out vacuum distillation at a vacuum degree of 1 Pa, with a vacuum distillation temperature of 1100 °C and a time of 5 h to obtain an indium ingot;

[0108] (4) Use the indium ingot as the anode, a titanium plate as the cathode, and an indium-containing solution as the electrolyte to carry out electrolysis to obtain refined indium.

[0109] The current density of the electrolysis is 90 A / m 2 , the temperature is 20 °C, and the voltage is 0.2 V.

[0110] The indium-containing solution includes the following components: indium sulfate at 80 g / L, sodium chloride at 85 g / L, gelatin at 0.2 g / L, and thiourea at 0.1 g / L.

[0111] Comparative Example 2

[0112] A method for recovering indium from indium-containing wastewater, comprising the following steps:

[0113] (1) Add zinc powder to the indium-containing wastewater, react at 40 °C for 4 h under 100 W ultrasonic waves, filter, wash, and dry to obtain a precipitate;

[0114] The solid-liquid ratio of the zinc powder to the indium-containing wastewater is 15 g: 1 L;

[0115] The main element concentrations in the indium-containing wastewater are In 0.65 g / L, Sn 0.15 g / L, Fe 0.08 g / L, Cu 0.12 g / L, Zn 6.22 g / L, and Ni 0.05 g / L.

[0116] (2) Load the precipitate into a tubular furnace with a quartz tube, introduce hydrogen at a rate of 5 L / min, and perform heat treatment at 600 °C for 4 h to obtain an indium alloy;

[0117] (3) Mix the indium alloy and calcium oxide evenly according to a mass ratio of 100:10, melt at 400 °C for 1 h, remove the surface scum, and cool to obtain an alloy ingot;

[0118] (4) Place the alloy ingot in a graphite crucible and put it into a vacuum distillation furnace. Carry out vacuum distillation at a vacuum degree of 1 Pa, with the temperature of vacuum distillation being 1100 °C and the time being 5 h to obtain indium ingots.

[0119] (5) Use the indium ingot as the anode, a titanium plate as the cathode, and an indium-containing solution as the electrolyte to carry out electrolysis to obtain refined indium.

[0120] The current density of the electrolysis is 90 A / m 2 , the temperature is 20 °C, and the voltage is 0.2 V.

[0121] The indium-containing solution includes the following components: indium sulfate at 80 g / L, sodium chloride at 85 g / L, gelatin at 0.2 g / L, and thiourea at 0.1 g / L.

[0122] Comparative Example 3

[0123] A method for recovering indium from indium-containing wastewater, comprising the following steps:

[0124] (1) Add zinc powder to the indium-containing wastewater, react at 40 °C for 4 h under 100 W ultrasonic, filter, wash, and dry to obtain a precipitate.

[0125] The solid-liquid ratio of the zinc powder to the indium-containing wastewater is 15 g:1 L;

[0126] The main element concentrations of the indium-containing wastewater are In 0.65 / L, Sn 0.15 g / L, Fe 0.08 g / L, Cu 0.12 g / L, Zn 6.22 g / L, and Ni 0.05 g / L.

[0127] (2) Load the precipitate into a quartz tube and place it in a tube furnace, introduce hydrogen at a rate of 5 L / min, and perform heat treatment at 450 °C for 4 h to obtain an indium alloy.

[0128] (3) Mix the indium alloy and calcium oxide evenly according to a mass ratio of 100:10, melt at 400 °C for 1 h, remove the surface scum, and cool to obtain an alloy ingot.

[0129] (4) Place the alloy ingot in a graphite crucible and put it into a vacuum distillation furnace. Carry out vacuum distillation at a vacuum degree of 1 Pa, with the temperature of vacuum distillation being 1100 °C and the time being 5 h to obtain indium ingots.

[0130] (5) Use the indium ingot as the anode, a titanium plate as the cathode, and an indium-containing solution as the electrolyte to carry out electrolysis to obtain refined indium.

[0131] The current density of the electrolysis is 90 A / m 2 , the temperature is 20 °C, and the voltage is 0.2 V.

[0132] The indium-containing solution includes the following components: indium sulfate at 80 g / L, sodium chloride at 85 g / L, gelatin at 0.2 g / L, and thiourea at 0.1 g / L.

[0133] Comparative Example 4

[0134] A method for recovering indium from indium-containing wastewater includes the following steps:

[0135] (1) Add zinc powder to the indium-containing wastewater, react at 40 °C for 4 h under 100 W ultrasound, filter, wash, and dry to obtain a precipitate;

[0136] The solid-liquid ratio of the zinc powder to the indium-containing wastewater is 15 g:1 L;

[0137] The main element concentrations in the indium-containing wastewater are In 0.65 / L, Sn 0.15 g / L, Fe 0.08 g / L, Cu 0.12 g / L, Zn 6.22 g / L, and Ni 0.05 g / L.

[0138] (2) Load the precipitate into a quartz tube and place it in a tube furnace, introduce hydrogen at a rate of 5 L / min, perform heat treatment at 450 °C for 4 h, and then perform heat treatment at 600 °C for 4 h to obtain an indium alloy;

[0139] (3) Mix the indium alloy and calcium oxide evenly according to a mass ratio of 100:10, melt at 200 °C for 1 h, remove the surface scum, and cool to obtain an alloy ingot;

[0140] (4) Place the alloy ingot in a graphite crucible, put it into a vacuum distillation furnace, perform vacuum distillation at a vacuum degree of 1 Pa, the temperature of the vacuum distillation is 1100 °C, and the time is 5 h to obtain an indium ingot;

[0141] (5) Use the indium ingot as the anode, a titanium plate as the cathode, and the indium-containing solution as the electrolyte to perform electrolysis to obtain refined indium.

[0142] The current density of the electrolysis is 90 A / m 2 , the temperature is 20 °C, and the voltage is 0.2 V.

[0143] The indium-containing solution includes the following components: indium sulfate at 80 g / L, sodium chloride at 85 g / L, gelatin at 0.2 g / L, and thiourea at 0.1 g / L.

[0144] Comparative Example 5

[0145] A method for recovering indium from indium-containing wastewater includes the following steps:

[0146] (1) Add zinc powder to the indium-containing wastewater, react at 40 °C for 4 h under 100 W ultrasound, filter, wash, and dry to obtain a precipitate;

[0147] The solid-liquid ratio of the zinc powder to the indium-containing wastewater is 15 g: 1 L;

[0148] The main element concentrations of the indium-containing wastewater are In 0.65 / L, Sn 0.15 g / L, Fe 0.08 g / L, Cu 0.12 g / L, Zn 6.22 g / L, and Ni 0.05 g / L.

[0149] (2) Load the precipitate into a tubular furnace with a quartz tube, introduce hydrogen at a rate of 5 L / min, perform heat treatment at 450 °C for 4 h, and then perform heat treatment at 600 °C for 4 h to obtain an indium alloy;

[0150] (3) Mix the indium alloy and calcium oxide evenly according to a mass ratio of 100:10, melt at 500 °C for 1 h, remove the surface scum, and cool to obtain an alloy ingot;

[0151] (4) Place the alloy ingot in a graphite crucible, put it into a vacuum distillation furnace, perform vacuum distillation at a vacuum degree of 1 Pa, the temperature of the vacuum distillation is 1100 °C, and the time is 5 h to obtain an indium ingot;

[0152] (5) Use the indium ingot as the anode, the titanium plate as the cathode, and the indium-containing solution as the electrolyte to perform electrolysis to obtain refined indium.

[0153] The current density of the electrolysis is 90 A / m 2 , the temperature is 20 °C, and the voltage is 0.2 V.

[0154] The indium-containing solution includes the following components: indium sulfate at 80 g / L, sodium chloride at 85 g / L, gelatin at 0.2 g / L, and thiourea at 0.1 g / L.

[0155] Comparative Example 6

[0156] A method for recovering indium from indium-containing wastewater, comprising the following steps:

[0157] (1) Add zinc powder to the indium-containing wastewater, react at 40 °C for 4 h under 100 W ultrasonic, filter, wash, and dry to obtain a precipitate;

[0158] The solid-liquid ratio of the zinc powder to the indium-containing wastewater is 15 g: 1 L;

[0159] The main element concentrations of the indium-containing wastewater are In 0.65 / L, Sn 0.15 g / L, Fe 0.08 g / L, Cu 0.12 g / L, Zn 6.22 g / L, and Ni 0.05 g / L.

[0160] (2) Load the precipitate into a tubular furnace using a quartz tube, introduce hydrogen at a rate of 5 L / min, perform heat treatment at 450 °C for 4 h, and then perform heat treatment at 600 °C for 4 h to obtain an indium alloy;

[0161] (3) Mix the indium alloy and calcium oxide evenly according to a mass ratio of 100:2, melt at 400 °C for 1 h, remove the surface scum, and cool to obtain an alloy ingot;

[0162] (4) Place the alloy ingot in a graphite crucible, put it into a vacuum distillation furnace, perform vacuum distillation at a vacuum degree of 1 Pa, the temperature of the vacuum distillation is 1100 °C, and the time is 5 h to obtain an indium ingot;

[0163] (5) Use the indium ingot as the anode, the titanium plate as the cathode, and the indium-containing solution as the electrolyte to perform electrolysis to obtain refined indium.

[0164] The current density of the electrolysis is 90 A / m 2 , the temperature is 20 °C, and the voltage is 0.2 V.

[0165] The indium-containing solution includes the following components: indium sulfate at 80 g / L, sodium chloride at 85 g / L, gelatin at 0.2 g / L, and thiourea at 0.1 g / L.

[0166] Comparative Example 7

[0167] A method for recovering indium from indium-containing wastewater, comprising the following steps:

[0168] (1) Add zinc powder to the indium-containing wastewater, react at 40 °C for 4 h under 100 W ultrasonic, filter, wash, and dry to obtain a precipitate;

[0169] The solid-liquid ratio of the zinc powder to the indium-containing wastewater is 15 g:1 L;

[0170] The main element concentrations of the indium-containing wastewater are In 0.65 / L, Sn 0.15 g / L, Fe 0.08 g / L, Cu 0.12 g / L, Zn 6.22 g / L, and Ni 0.05 g / L.

[0171] (2) Load the precipitate into a tubular furnace using a quartz tube, introduce hydrogen at a rate of 5 L / min, perform heat treatment at 450 °C for 4 h, and then perform heat treatment at 600 °C for 4 h to obtain an indium alloy;

[0172] (3) Mix the indium alloy and calcium oxide evenly according to a mass ratio of 100:20, melt at 400 °C for 1 h, remove the surface scum, and cool to obtain an alloy ingot;

[0173] (4) Place the alloy ingot in a graphite crucible and put it into a vacuum distillation furnace. Conduct vacuum distillation at a vacuum degree of 1 Pa, with the temperature of vacuum distillation being 1100 °C and the time being 5 h to obtain indium ingots;

[0174] (5) Use the indium ingot as the anode, a titanium plate as the cathode, and an indium-containing solution as the electrolyte to conduct electrolysis to obtain refined indium.

[0175] The current density of the electrolysis is 90 A / m 2 , the temperature is 20 °C, and the voltage is 0.2 V.

[0176] The indium-containing solution includes the following components: indium sulfate at 80 g / L, sodium chloride at 85 g / L, gelatin at 0.2 g / L, and thiourea at 0.1 g / L.

[0177] Comparative Example 8

[0178] A method for recovering indium from indium-containing wastewater, comprising the following steps:

[0179] (1) Add zinc powder to the indium-containing wastewater, react at 40 °C for 4 h under 100 W ultrasonic, filter, wash, and dry to obtain a precipitate;

[0180] The solid-liquid ratio of the zinc powder to the indium-containing wastewater is 15 g:1 L;

[0181] The main element concentrations in the indium-containing wastewater are In 0.65 / L, Sn 0.15 g / L, Fe 0.08 g / L, Cu 0.12 g / L, Zn 6.22 g / L, and Ni 0.05 g / L.

[0182] (2) Load the precipitate into a tube furnace with a quartz tube, introduce hydrogen at a rate of 5 L / min, conduct heat treatment at 450 °C for 4 h, and then conduct heat treatment at 600 °C for 4 h to obtain an indium alloy;

[0183] (3) Mix the indium alloy and calcium oxide evenly according to a mass ratio of 100:2, melt at 400 °C for 1 h, remove the surface scum, and cool to obtain an alloy ingot;

[0184] (4) Place the alloy ingot in a graphite crucible and put it into a vacuum distillation furnace. Conduct vacuum distillation at a vacuum degree of 1 Pa, with the temperature of vacuum distillation being 1100 °C and the time being 5 h to obtain indium ingots;

[0185] (5) Use the indium ingot as the anode, a titanium plate as the cathode, and an indium-containing solution as the electrolyte to conduct electrolysis to obtain refined indium.

[0186] The current density of the electrolysis is 90 A / m 2 , the temperature is 20 °C, and the voltage is 0.2 V.

[0187] The indium-containing solution is an indium sulfate solution with a concentration of 80 g / L.

[0188] Test example

[0189] Among them, the purity and recovery rate of refined indium in the examples and comparative examples are shown in Table 1.

[0190] Table 1

[0191]

[0192]

[0193] In the present invention, indium metal is displaced and precipitated from indium-containing wastewater under the action of ultrasonic waves, and then purified by high-temperature reduction through two heat treatments under hydrogen. Through molten salt smelting, distillation and electrolytic refining, indium is purified to refined indium. The process is short, the operation is simple, and the cost is relatively low.

[0194] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for recovering indium from indium-containing wastewater, characterized in that: The following steps are involved: The zinc powder is added into the indium-containing wastewater, reacted under ultrasound, filtered, washed, and dried to obtain a precipitate; The precipitate is placed in a tube furnace, hydrogen is introduced, a first heat treatment is performed, and then a second heat treatment is performed to obtain an indium alloy; The indium alloy and the molten salt are mixed evenly, and smelted to obtain an alloy ingot; The alloy ingot is subjected to vacuum distillation to obtain an indium ingot; With indium ingot as anode, titanium plate as cathode and indium-containing liquid as electrolyte, electrolysis is carried out to obtain refined indium.

2. The method for recovering indium from indium-containing wastewater according to claim 1, characterized in that: The solid-to-liquid ratio of the zinc powder and the indium-containing wastewater is (10-20) g:1 L; The power of the ultrasound is 50-100W, the temperature of the reaction under ultrasound is 30-50°C, and the reaction time is 2-6h.

3. The method for recovering indium from indium-containing wastewater according to claim 1, characterized in that: The amount of hydrogen introduced is 4-6 L / min.

4. The method for recovering indium from indium-containing wastewater according to claim 1, characterized in that: The first heat treatment temperature is 300-450°C and the time is 2-6h; The second heat treatment temperature is 600-800° C. and the time is 2-6 hours.

5. The method for recovering indium from indium-containing wastewater according to claim 1, characterized in that: The mass ratio of the indium alloy to the molten salt is 100:(5-10).

6. The method for recovering indium from indium-containing wastewater according to claim 1, characterized in that: The molten salt includes at least one of calcium oxide, sodium nitrate, sodium borate, quartz stone and borax.

7. The method for recovering indium from indium-containing wastewater according to claim 1, characterized in that: The smelting temperature is 300-400° C., and the smelting time is 1-2 hours.

8. The method for recovering indium from indium-containing wastewater according to claim 1, characterized in that: The vacuum distillation temperature is 900-1100° C. and the time is 4-6 hours.

9. The method for recovering indium from indium-containing wastewater according to claim 1, characterized in that: The current density of the electrolysis is 80-100A / m 2 , temperature is 20~25℃, voltage is 0.1~0.25V.

10. The method for recovering indium from indium-containing wastewater according to claim 1, characterized in that: The indium-containing solution comprises the following components: 80-120 g / L of indium sulfate, 80-85 g / L of sodium chloride, 0.2-0.3 g / L of gelatin, and 0.05-0.1 g / L of thiourea.

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