Methods for recovering iodide scrap

Abstract

This invention relates to a method for recovering iodide scrap. [Means] The method includes the steps of: treating dissolved iodide scrap with activated carbon adsorption and performing solid-liquid separation to obtain an iodide solution; concentrating and crystallizing the iodide solution to obtain iodide crystal particles; and sequentially vacuum heating and vacuum distillation of the iodide crystal particles to obtain iodide with a purity of 4N or higher. The method does not require the addition of other materials during recovery, can obtain iodide with a purity of 4N or higher, realizes scrap recycling, reduces costs, and further reduces environmental pollution of the scrap, thereby realizing green recycling.

Description

[Technical Field]

[0001] This invention belongs to the technical field of scrap processing and relates to a method for recovering scrap, and more particularly to a method for recovering iodide scrap. [Background technology]

[0002] Cesium iodide crystals are excellent halide crystals with a low melting point (only 621°C), mature growth technology, ease of growing large crystals, and low cost, making them widely used in high-energy physics, security inspection, industrial non-destructive testing, and nuclear medicine imaging. Sodium iodide crystals have high density, high photon yield, and relatively low cost, and are widely used in fields such as nuclear medicine, environmental monitoring, and oil well exploration. They also have excellent energy resolution and high optical output, making them suitable for use in gamma cameras and positron emission tomography (PET).

[0003] When iodide crystals such as cesium iodide and sodium iodide leak during growth, the leaked material cannot be used as is. Furthermore, iodide crystals also generate some scraps and offcuts during processing, and these raw materials cannot be used as is either. Therefore, it is necessary to recover and process the leaked material and waste raw materials so that they can be reused.

[0004] In response to this, it is necessary to provide a method for recovering iodide scrap in such a way that the purity of the recovered iodide is 4N or higher. [Overview of the project] [Problems that the invention aims to solve]

[0005] In view of the shortcomings of conventional technology, the present invention aims to provide a method for recovering iodide scrap that does not require the addition of other materials during recovery, can obtain iodide with a purity of 4N or higher (≧99.99 wt%), enables scrap recycling, reduces costs, and further reduces environmental pollution of scrap, thereby achieving green recycling. [Means for solving the problem]

[0006] To achieve the objective of this invention, the present invention employs the following technical solutions.

[0007] The present invention The present invention provides a method for recovering iodide scrap, comprising the steps of: treating dissolved iodide scrap with activated carbon adsorption and performing solid-liquid separation to obtain an iodide solution; concentrating and crystallizing the iodide solution to obtain iodide crystal particles; and sequentially vacuum heating and vacuum distillation of the iodide crystal particles to obtain iodide with a purity of 4N or higher. The iodide scrap is scrap generated during the growth process of iodide crystals.

[0008] The method according to the present invention does not require the addition of other materials during recovery, can obtain iodide with a purity of 4N or higher, enables scrap recycling, reduces costs, and further reduces environmental pollution from the scrap, thereby achieving green recycling.

[0009] Preferably, the iodide scrap includes cesium iodide scrap or sodium iodide scrap.

[0010] Preferably, the temperature of the vacuum heating is 300°C to 320°C.

[0011] Preferably, the vacuum heating time is 10 hours or more.

[0012] Preferably, the absolute pressure of the vacuum heating is 3 × 10⁻⁶ 3 Pa is less than or equal to 1 × 10 3 It is preferable that the value is Pa or less.

[0013] Preferably, the absolute pressure of the vacuum distillation is 3 × 10⁻⁶ -3 Pa is less than or equal to 1 × 10 -3 It is preferable that the value is Pa or less.

[0014] Preferably, when the iodide scrap is cesium iodide scrap, the vacuum distillation temperature is 650°C to 680°C.

[0015] Preferably, when the iodide scrap is sodium iodide scrap, the temperature of the vacuum distillation is 700°C to 720°C.

[0016] Preferably, the iodide scrap further comprises thallium iodide scrap.

[0017] Preferably, if the iodide scrap further contains thallium iodide scrap, the vacuum heating temperature is 300°C to 320°C, the vacuum heating time is 10 hours or more, and the absolute pressure of the vacuum heating is 3 × 10⁻⁶ 3 Pa is less than or equal to 1 × 10 3 It is preferable that the value is Pa or less.

[0018] Preferably, if the iodide scrap further contains thallium iodide scrap, the absolute pressure of the vacuum distillation is 3 × 10⁻⁶. -3 Pa is less than or equal to 1 × 10 -3 It is preferable that the value is Pa or less.

[0019] Preferably, the vacuum distillation includes a first distillation and a second distillation performed in sequence, wherein thallium iodide is recovered and obtained in the first distillation, and cesium iodide or sodium iodide is recovered and obtained in the second distillation.

[0020] Preferably, the temperature at which thallium iodide is recovered and obtained in the first distillation is 450°C to 470°C.

[0021] Preferably, the temperature for recovering cesium iodide by the second distillation is 650°C to 680°C.

[0022] Preferably, the temperature for recovering sodium iodide by the second distillation is 700°C to 720°C.

[0023] Preferably, the solution obtained by dissolving the iodide scrap is a saturated aqueous solution.

[0024] Preferably, the activated carbon used in the activated carbon adsorption treatment is required to have an ash content ≤ 5 wt%, an iodine adsorption value ≥ 600 mg / g, and an average particle size ≥ 5 mm.

[0025] Preferably, the method of solid-liquid separation includes suction filtration.

[0026] As a preferred technical solution 1 of the method according to the present invention, the method includes: (1) Dissolving cesium iodide scrap in water to obtain a saturated cesium iodide waste liquid; (2) Adding activated carbon to the cesium iodide waste liquid, stirring and adsorbing it, and then performing suction filtration to obtain a cesium iodide solution; (3) Concentrating and crystallizing the cesium iodide solution to obtain iodide crystal particles; (4) Vacuum heating the iodide crystal particles under the conditions of an absolute pressure of 3×10 3 Pa or less and a temperature of 300°C to 320°C for 10 h or more to remove crystal water, and then performing vacuum distillation under the conditions of an absolute pressure of 3×10 -3 Pa or less and a temperature of 650°C to 680°C to obtain cesium iodide with a purity of 4N or more.

[0027] As a preferred technical solution 2 of the method according to the present invention, the method includes: (1) Dissolving sodium iodide scrap in water to obtain a saturated sodium iodide waste liquid; (2) Adding activated carbon to the sodium iodide waste liquid, stirring to adsorb, and then performing suction filtration to obtain a sodium iodide solution, (3) A step of concentrating and crystallizing a sodium iodide solution to obtain iodide crystal particles, (4) The iodide crystal particles are subjected to an absolute pressure of 3 × 10 3 Vacuum heating is performed for 10 hours or more under conditions of Pa or less and a temperature of 300°C to 320°C to remove crystal water, and then the absolute pressure is reduced to 3 × 10⁻⁶. -3 The method includes the step of obtaining sodium iodide with a purity of 4N or higher by vacuum distillation under conditions of Pa or less and a temperature of 700°C to 720°C.

[0028] As a preferred technical example 3 of the method according to the present invention, the method is: (I) A step of dissolving a combined scrap consisting of sodium iodide scrap and thallium iodide scrap in water to obtain saturated waste liquid, (II) Adding activated carbon to the saturated waste liquid, stirring to adsorb, and then performing suction filtration to obtain a solution of iodide, (III) A step of concentrating and crystallizing the iodide solution to obtain iodide crystal particles, (IV) When the iodide crystal particles are subjected to an absolute pressure of 1 × 10 3 Vacuum heating is performed for 10 to 12 hours under conditions of Pa or less and a temperature of 300°C to 320°C to remove crystal water, and then the absolute pressure is reduced to 3 × 10⁻⁶. -3 The first distillation was performed under conditions of Pa or less and a temperature of 450°C to 470°C to obtain thallium iodide with a purity of 4N or higher, and then the absolute pressure was reduced to 3 × 10⁻⁶. -3 The method includes the step of performing a second distillation under conditions of Pa or less and a temperature of 700°C to 720°C to obtain sodium iodide with a purity of 4N or higher.

[0029] As a preferred technical example 4 of the method according to the present invention, the method is: (I) A step of dissolving a combined scrap consisting of cesium iodide scrap and thallium iodide scrap in water to obtain saturated waste liquid, (II) Adding activated carbon to the saturated waste liquid, stirring to adsorb, and then performing suction filtration to obtain a solution of iodide, (III) A step of concentrating and crystallizing the iodide solution to obtain iodide crystal particles, (IV) When the iodide crystal particles are subjected to an absolute pressure of 1 × 10 3 Vacuum heating is performed for 10 to 12 hours under conditions of Pa or less and a temperature of 300°C to 320°C to remove crystal water, and then the absolute pressure is reduced to 3 × 10⁻⁶. -3 The first distillation was performed under conditions of Pa or less and a temperature of 450°C to 470°C to obtain thallium iodide with a purity of 4N or higher, and then the absolute pressure was reduced to 3 × 10⁻⁶. -3 The method includes the step of performing a second distillation under conditions of Pa or less and a temperature of 650°C to 680°C to obtain cesium iodide with a purity of 4N or higher. [Effects of the Invention]

[0030] Compared to the prior art, the present invention offers the following beneficial effects.

[0031] The method according to the present invention does not require the addition of other materials during recovery, can obtain iodide with a purity of 4N or higher, enables scrap recycling, reduces costs, and further reduces environmental pollution from the scrap, thereby achieving green recycling. [Brief explanation of the drawing]

[0032] [Figure 1] This is a flowchart of the iodide scrap recovery method according to the present invention. [Modes for carrying out the invention]

[0033] The technical aspects of the present invention will be further explained below with reference to specific embodiments. Those skilled in the art will understand that the above embodiments are merely for the purpose of understanding the present invention and should not be considered as specifically limiting the present invention.

[0034] The present invention provides a method for recovering iodide scrap, the flowchart of which includes the following steps, as shown in Figure 1.

[0035] In S101, the dissolved iodide scrap is subjected to activated carbon adsorption treatment, and solid-liquid separation is performed to obtain an iodide solution.

[0036] In S102, the iodide solution is concentrated and crystallized to obtain iodide crystal particles.

[0037] In S103, the iodide crystal particles are sequentially subjected to vacuum heating and vacuum distillation to obtain iodide with a purity of 4N or higher.

[0038] The method according to the present invention does not require the addition of other materials during recovery, can obtain iodide with a purity of 4N or higher (≧99.99 wt%), enables scrap recycling, reduces costs, and further reduces environmental pollution from scrap, thereby achieving green recycling.

[0039] In some embodiments, the iodide scrap includes cesium iodide scrap or sodium iodide scrap.

[0040] In some embodiments, when the iodide scrap includes cesium iodide scrap or sodium iodide scrap, the vacuum heating temperature is 300°C to 320°C, and may be, for example, 300°C, 305°C, 310°C, 315°C, or 320°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] In some embodiments, when the iodide scrap includes cesium iodide scrap or sodium iodide scrap, the vacuum heating time is 10 hours or longer, and may be, for example, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, or 15 hours, but is not limited to the listed numbers, and other unlisted numbers within the numerical range are also applicable.

[0042] In some embodiments, when the iodide scrap includes cesium iodide scrap or sodium iodide scrap, the absolute pressure of the vacuum heating is 3 × 10⁻⁶ 3 It is less than or equal to Pa, for example, 0.1 × 10⁻⁶ 3 Pa, 0.5 × 10 3 Pa, 1 × 10 3 Pa, 1.5 × 10 3 Pa, 2 × 10 3 Pa, 2.5 × 10 3 Pa or 3 × 10 3 Pa is also acceptable, but it is not limited to the listed numbers; other unlisted numbers within the numerical range also apply, 1 × 10 3 It is preferable that the value is Pa or less.

[0043] In some embodiments, when the iodide scrap includes cesium iodide scrap or sodium iodide scrap, the absolute pressure of the vacuum distillation is 3 × 10⁻⁶. -3 It is less than or equal to Pa, for example, 0.5 × 10⁻⁶ -3 Pa, 1 × 10 -3 Pa, 1.5 × 10 -3 Pa, 2 × 10 -3 Pa, 2.5 × 10 -3 Pa or 3 × 10 -3 Pa is also acceptable, but it is not limited to the listed numbers; other unlisted numbers within the numerical range also apply, 1 × 10 -3 It is preferable that the value is Pa or less.

[0044] In some embodiments, when the iodide scrap is cesium iodide scrap, the vacuum distillation temperature is 650°C to 680°C, and may be, for example, 650°C, 660°C, 670°C, or 680°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0045] In some embodiments, when the iodide scrap is sodium iodide scrap, the vacuum distillation temperature is 700°C to 720°C, and may be, for example, 700°C, 705°C, 710°C, 715°C, or 720°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0046] In some embodiments, the iodide scrap further comprises thallium iodide scrap.

[0047] In some embodiments, if the iodide scrap further includes thallium iodide scrap, the vacuum heating temperature is 300°C to 320°C, and may be, for example, 300°C, 305°C, 310°C, 315°C, or 320°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0048] In some embodiments, if the iodide scrap further includes thallium iodide scrap, the vacuum heating time is 10 hours or more, and may be, for example, 10 hours, 10.5 hours, 11 hours, 11.5 hours, or 12 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0049] In some embodiments, when the iodide scrap further contains thallium iodide scrap, the absolute pressure of the vacuum heating is 3 × 10⁻⁶ 3 It is less than or equal to Pa, for example, 0.5 × 10⁻⁶ 3 Pa, 1 × 10 3 Pa, 1.5 × 10 3 Pa, 2 × 10 3 Pa, 2.5 × 10 3 Pa or 3 × 10 3 Pa is also acceptable, but it is not limited to the listed numbers; other unlisted numbers within the numerical range also apply, 1 × 10 3 It is preferable that the value is Pa or less.

[0050] In some embodiments, when the iodide scrap further contains thallium iodide scrap, the absolute pressure of the vacuum distillation is 3 × 10⁻⁶. -3 It is less than or equal to Pa, for example, 0.5 × 10⁻⁶ -3 Pa, 1 × 10 -3 Pa, 1.5 × 10 -3 Pa, 2 × 10 -3 Pa, 2.5 × 10 -3 Pa or 3 × 10 -3 Pa is also acceptable, but it is not limited to the listed numbers; other unlisted numbers within the numerical range also apply, 1 × 10 -3 It is preferable that the value is Pa or less.

[0051] In some embodiments, if the iodide scrap further comprises thallium iodide scrap, the vacuum distillation includes a first distillation and a second distillation, performed in sequence.

[0052] In some embodiments, the temperature at which thallium iodide is recovered and obtained in the first distillation is 450°C to 470°C, and may be, for example, 450°C, 455°C, 460°C, 465°C, or 470°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0053] In some embodiments, the temperature at which cesium iodide is recovered and obtained in the second distillation is 650°C to 680°C, and may be, for example, 650°C, 655°C, 660°C, 665°C, 670°C, 675°C, or 680°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0054] In some embodiments, the temperature at which sodium iodide is recovered and obtained in the second distillation is 700°C to 720°C, and may be, for example, 700°C, 705°C, 710°C, 715°C, or 720°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0055] In some examples, the solution in which the iodide scrap is dissolved is a saturated aqueous solution.

[0056] In some embodiments, the activated carbon used in the activated carbon adsorption treatment is required to have an ash content of ≤ 5 wt%, an iodine adsorption value of ≥ 600 mg / g, and an average particle size of ≥ 5 mm.

[0057] In some embodiments, the method of solid-liquid separation includes suction filtration.

[0058] As a preferred technical example of the method according to the present invention, the method is: (1) A step of dissolving cesium iodide scrap in water to obtain saturated cesium iodide waste liquid, (2) Adding activated carbon to the cesium iodide waste liquid, stirring to adsorb, and then performing suction filtration to obtain a cesium iodide solution, (3) A step of concentrating and crystallizing a solution of cesium iodide to obtain iodide crystal particles, (4) The iodide crystal particles are subjected to an absolute pressure of 3 × 10 3 Vacuum heating is performed for 10 hours or more under conditions of Pa or less and a temperature of 300°C to 320°C to remove crystal water, and then the absolute pressure is reduced to 3 × 10⁻⁶. -3 The method includes the step of obtaining cesium iodide with a purity of 4N or higher by vacuum distillation under conditions of Pa or less and a temperature of 650°C to 680°C.

[0059] As a preferred technical example 2 of the method according to the present invention, the method is: (1) A step of dissolving sodium iodide scrap in water to obtain saturated sodium iodide waste liquid, (2) Adding activated carbon to the sodium iodide waste liquid, stirring to adsorb, and then performing suction filtration to obtain a sodium iodide solution, (3) A step of concentrating and crystallizing a sodium iodide solution to obtain iodide crystal particles, (4) The iodide crystal particles are subjected to an absolute pressure of 3 × 10 3Vacuum heating is performed for 10 hours or more under conditions of Pa or less and a temperature of 300°C to 320°C to remove crystal water, and then the absolute pressure is reduced to 3 × 10⁻⁶. -3 The method includes the step of obtaining sodium iodide with a purity of 4N or higher by vacuum distillation under conditions of Pa or less and a temperature of 700°C to 720°C.

[0060] As a preferred technical example 3 of the method according to the present invention, the method is: (I) A step of dissolving a combined scrap consisting of sodium iodide scrap and thallium iodide scrap in water to obtain saturated waste liquid, (II) Adding activated carbon to the saturated waste liquid, stirring to adsorb, and then performing suction filtration to obtain a solution of iodide, (III) A step of concentrating and crystallizing the iodide solution to obtain iodide crystal particles, (IV) When the iodide crystal particles are subjected to an absolute pressure of 1 × 10 3 Vacuum heating is performed for 10 to 12 hours under conditions of Pa or less and a temperature of 300°C to 320°C to remove crystal water, and then the absolute pressure is reduced to 3 × 10⁻⁶. -3 The first distillation was performed under conditions of Pa or less and a temperature of 450°C to 470°C to obtain thallium iodide with a purity of 4N or higher, and then the absolute pressure was reduced to 3 × 10⁻⁶. -3 The method includes the step of performing a second distillation under conditions of Pa or less and a temperature of 700°C to 720°C to obtain sodium iodide with a purity of 4N or higher.

[0061] As a preferred technical example 4 of the method according to the present invention, the method is: (I) A step of dissolving a combined scrap consisting of cesium iodide scrap and thallium iodide scrap in water to obtain saturated waste liquid, (II) Adding activated carbon to the saturated waste liquid, stirring to adsorb, and then performing suction filtration to obtain a solution of iodide, (III) A step of concentrating and crystallizing the iodide solution to obtain iodide crystal particles, (IV) When the iodide crystal particles are subjected to an absolute pressure of 1 × 10 3Vacuum heating is performed for 10 to 12 hours under conditions of Pa or less and a temperature of 300°C to 320°C to remove crystal water, and then the absolute pressure is reduced to 3 × 10⁻⁶. -3 The first distillation was performed under conditions of Pa or less and a temperature of 450°C to 470°C to obtain thallium iodide with a purity of 4N or higher, and then the absolute pressure was reduced to 3 × 10⁻⁶. -3 The method includes the step of performing a second distillation under conditions of Pa or less and a temperature of 650°C to 680°C to obtain cesium iodide with a purity of 4N or higher.

[0062] To clearly illustrate the technical concept of the present invention, the purity in the following test examples is obtained by glow discharge mass spectrometry (GDMS), the recovery rate is the mass % of the recovered iodide relative to the mass of iodide corresponding to the scrap, the ash content of the activated carbon used in the following test examples is 4 wt%, the iodine adsorption value is 620 mg / g, and the average particle size is 6 mm. Test Example 1

[0063] This test example provides a method for recovering iodide scrap, the method comprising the following steps.

[0064] (1) Cesium iodide scrap (with a cesium iodide purity of 95 wt%) was dissolved in water to obtain saturated cesium iodide waste liquid.

[0065] (2) Activated carbon was added to the cesium iodide waste liquid, stirred to adsorb, and then suction filtration was performed using a Buchner funnel to obtain a cesium iodide solution.

[0066] (3) The cesium iodide solution was concentrated and crystallized to obtain crystal iodide particles containing crystal water.

[0067] (4) When the iodide crystal particles are subjected to an absolute pressure of 1 × 10 3 Vacuum heating at 310°C for 10 hours to remove crystal water, and then absolute pressure 3 × 10 -3 Cesium iodide was obtained by vacuum distillation under conditions of Pa and a temperature of 660°C. (Test Example 2)

[0068] This test example provides a method for recovering iodide scrap, the method comprising the following steps.

[0069] (1) Cesium iodide scrap, similar to that used in Test Example 1, was dissolved in water to obtain saturated cesium iodide waste liquid.

[0070] (2) Activated carbon was added to the cesium iodide waste liquid, stirred to adsorb, and then suction filtration was performed using a Buchner funnel to obtain a cesium iodide solution.

[0071] (3) The cesium iodide solution was concentrated and crystallized to obtain crystal iodide particles containing crystal water.

[0072] (4) When the iodide crystal particles are subjected to an absolute pressure of 1 × 10 3 Vacuum heating at 300°C for 10 hours to remove crystal water, and then absolute pressure 3 × 10 -3 Cesium iodide was obtained by vacuum distillation under conditions of Pa and a temperature of 650°C. (Test Example 3)

[0073] This test example provides a method for recovering iodide scrap, the method comprising the following steps.

[0074] (1) Cesium iodide scrap, similar to that used in Test Example 1, was dissolved in water to obtain saturated cesium iodide waste liquid.

[0075] (2) Activated carbon was added to the cesium iodide waste liquid, stirred to adsorb, and then suction filtration was performed using a Buchner funnel to obtain a cesium iodide solution.

[0076] (3) The cesium iodide solution was concentrated and crystallized to obtain crystal iodide particles containing crystal water.

[0077] (4) When the iodide crystal particles are subjected to an absolute pressure of 1 × 10 3 Vacuum heating at 320°C for 10 hours to remove crystal water, and then absolute pressure 3 × 10 -3Cesium iodide was obtained by vacuum distillation under conditions of Pa and a temperature of 680°C. (Test Example 4)

[0078] This test example provides a method for recovering iodide scrap, and all aspects were the same as in Example 1 except that the vacuum distillation temperature was 640°C. Test Example 5

[0079] This test example provides a method for recovering iodide scrap, and all aspects were the same as in Example 1 except that the vacuum distillation temperature was 690°C. Test Example 6

[0080] This test example provides a method for recovering iodide scrap, the method comprising the following steps.

[0081] (1) Cesium iodide scrap, similar to that used in Test Example 1, was dissolved in water to obtain saturated cesium iodide waste liquid.

[0082] (2) Activated carbon was added to the cesium iodide waste liquid, stirred to adsorb, and then suction filtration was performed using a Buchner funnel to obtain a cesium iodide solution.

[0083] (3) The cesium iodide solution was concentrated and crystallized to obtain crystal iodide particles containing crystal water.

[0084] (4) The iodide crystal particles are subjected to an absolute pressure of 3 × 10 -3 Cesium iodide was obtained by vacuum distillation under conditions of Pa and a temperature of 660°C. (Test Example 7)

[0085] This test example provides a method for recovering iodide scrap, the method comprising the following steps.

[0086] (1) Cesium iodide scrap, similar to that used in Test Example 1, was dissolved in water to obtain saturated cesium iodide waste liquid.

[0087] (2) Activated carbon was added to the cesium iodide waste liquid, stirred to adsorb, and then suction filtration was performed using a Buchner funnel to obtain a cesium iodide solution.

[0088] (3) The cesium iodide solution was concentrated and crystallized to obtain crystal iodide particles containing crystal water.

[0089] (4) The iodide crystal particles are subjected to an absolute pressure of 3 × 10 3 The sample was vacuum-heated for 10 hours under conditions of Pa and a temperature of 310°C to remove crystal water and obtain cesium iodide.

[0090] The purity and recovery rates of cesium iodide obtained in Test Examples 1 to 7 are shown in Table 1.

[0091] [Table 1] Test Example 8

[0092] This test example provides a method for recovering iodide scrap, the method comprising the following steps.

[0093] (1) Sodium iodide scrap (sodium iodide purity was 94 wt%) was dissolved in water to obtain saturated sodium iodide waste liquid.

[0094] (2) Activated carbon was added to the sodium iodide waste liquid, stirred to adsorb, and then the sodium iodide solution was obtained by suction filtration using a Buchner funnel.

[0095] (3) The sodium iodide solution was concentrated and crystallized to obtain crystal iodide particles containing crystal water.

[0096] (4) When the iodide crystal particles are subjected to an absolute pressure of 1 × 10 3 Vacuum heating at 310°C for 10 hours to remove crystal water, and then absolute pressure 3 × 10 -3 Sodium iodide was obtained by vacuum distillation under conditions of Pa and a temperature of 710°C. (Test Example 9)

[0097] This test example provides a method for recovering iodide scrap, the method comprising the following steps.

[0098] (1) Sodium iodide scrap, similar to that used in Test Example 8, was dissolved in water to obtain saturated sodium iodide waste liquid.

[0099] (2) Activated carbon was added to the sodium iodide waste liquid, stirred to adsorb, and then the sodium iodide solution was obtained by suction filtration using a Buchner funnel.

[0100] (3) The sodium iodide solution was concentrated and crystallized to obtain crystal iodide particles containing crystal water.

[0101] (4) When the iodide crystal particles are subjected to an absolute pressure of 1 × 10 3 Vacuum heating at 300°C for 10 hours to remove crystal water, and then absolute pressure 3 × 10 -3 Sodium iodide was obtained by vacuum distillation under conditions of Pa and a temperature of 700°C. (Test Example 10)

[0102] This test example provides a method for recovering iodide scrap, the method comprising the following steps.

[0103] (1) Sodium iodide scrap, similar to that used in Test Example 8, was dissolved in water to obtain saturated sodium iodide waste liquid.

[0104] (2) Activated carbon was added to the sodium iodide waste liquid, stirred to adsorb, and then the sodium iodide solution was obtained by suction filtration using a Buchner funnel.

[0105] (3) The sodium iodide solution was concentrated and crystallized to obtain crystal iodide particles containing crystal water.

[0106] (4) When the iodide crystal particles are subjected to an absolute pressure of 1 × 10 3 Vacuum heating at 320°C for 10 hours to remove crystal water, and then absolute pressure 3 × 10 -3Sodium iodide was obtained by vacuum distillation under conditions of Pa and a temperature of 720°C. (Test Example 11)

[0107] This test example provides a method for recovering iodide scrap, and all aspects were the same as in Example 1 except that the vacuum distillation temperature was 690°C. Test Example 12

[0108] This test example provides a method for recovering iodide scrap, and all aspects were the same as in Example 1 except that the vacuum distillation temperature was 730°C. Test Example 13

[0109] This test example provides a method for recovering iodide scrap, the method comprising the following steps.

[0110] (1) Sodium iodide scrap, similar to that used in Test Example 8, was dissolved in water to obtain saturated sodium iodide waste liquid.

[0111] (2) Activated carbon was added to the sodium iodide waste liquid, stirred to adsorb, and then the sodium iodide solution was obtained by suction filtration using a Buchner funnel.

[0112] (3) The sodium iodide solution was concentrated and crystallized to obtain crystal iodide particles containing crystal water.

[0113] (4) The iodide crystal particles are subjected to an absolute pressure of 3 × 10 -3 Sodium iodide was obtained by vacuum distillation under conditions of Pa and a temperature of 710°C. (Test Example 14)

[0114] This test example provides a method for recovering iodide scrap, the method comprising the following steps.

[0115] (1) Sodium iodide scrap, similar to that used in Test Example 8, was dissolved in water to obtain saturated sodium iodide waste liquid.

[0116] (2) Activated carbon was added to the sodium iodide waste liquid, stirred to adsorb, and then the sodium iodide solution was obtained by suction filtration using a Buchner funnel.

[0117] (3) The sodium iodide solution was concentrated and crystallized to obtain crystal iodide particles containing crystal water.

[0118] (4) The iodide crystal particles are subjected to an absolute pressure of 3 × 10 3 The solution was vacuum-heated for 10 hours under conditions of Pa and a temperature of 310°C to remove crystal water and obtain sodium iodide.

[0119] The purity and recovery rates of sodium iodide obtained in Test Examples 8 to 14 are shown in Table 2.

[0120] [Table 2] Test Example 15

[0121] This test example provides a method for recovering iodide scrap, the method comprising the following steps.

[0122] (I) Iodide scrap consisting of sodium iodide scrap and thallium iodide scrap (sodium iodide content was 82.9 wt%, and thallium iodide content was 0.42 wt%) was dissolved in water to obtain saturated wastewater.

[0123] (II) Activated carbon was added to the saturated waste liquid, stirred to allow adsorption, and then suction filtration was performed to obtain an iodide solution.

[0124] (III) The iodide solution was concentrated and crystallized to obtain iodide crystal particles.

[0125] (IV) The iodide crystal particles are subjected to an absolute pressure of 3 × 10 3 Vacuum heating was performed for 11 hours under conditions of Pa and a temperature of 310°C to remove crystal water, after which the absolute pressure was 3 × 10⁻⁶. -3 At Pa, the first distillation was performed at a temperature of 460°C to obtain thallium iodide, and then the absolute pressure was increased to 3 × 10⁻⁶. -3Sodium iodide was obtained by performing a second distillation under conditions of Pa and a temperature of 710°C. (Test Example 16)

[0126] This test example provides a method for recovering iodide scrap, the method comprising the following steps.

[0127] (I) Iodide scrap similar to that used in Test Example 15 was dissolved in water to obtain saturated wastewater.

[0128] (II) Activated carbon was added to the saturated waste liquid, stirred to allow adsorption, and then suction filtration was performed to obtain an iodide solution.

[0129] (III) The iodide solution was concentrated and crystallized to obtain iodide crystal particles.

[0130] (IV) The iodide crystal particles are subjected to an absolute pressure of 3 × 10 3 Vacuum heating at 300°C for 12 hours to remove crystal water, and then absolute pressure 3 × 10⁻⁶ -3 The first distillation was performed under conditions of Pa and a temperature of 450°C to obtain thallium iodide, and then the absolute pressure was increased to 3 × 10⁻⁶. -3 Sodium iodide was obtained by performing a second distillation under conditions of Pa and a temperature of 700°C. (Test Example 17)

[0131] This test example provides a method for recovering iodide scrap, the method comprising the following steps.

[0132] (I) Iodide scrap similar to that in Test Example 15 was dissolved in water to obtain saturated wastewater.

[0133] (II) Activated carbon was added to the saturated waste liquid, stirred to allow adsorption, and then suction filtration was performed to obtain an iodide solution.

[0134] (III) The iodide solution was concentrated and crystallized to obtain iodide crystal particles.

[0135] (IV) The iodide crystal particles are subjected to an absolute pressure of 3 × 10 3Vacuum heating at 320°C for 10 hours to remove crystal water, and then absolute pressure 3 × 10 -3 The first distillation was performed under conditions of Pa and a temperature of 470°C to obtain thallium iodide, and then the absolute pressure was increased to 3 × 10⁻⁶. -3 Sodium iodide was obtained by performing a second distillation under conditions of Pa and a temperature of 720°C. (Test Example 18)

[0136] This test example provides a method for recovering iodide scrap, and all aspects were the same as in Test Example 15, except that the temperature of the first distillation was 440°C. Test Example 19

[0137] This test example provides a method for recovering iodide scrap, and all aspects were the same as in Test Example 15 except that the temperature of the first distillation was 480°C. Test Example 20

[0138] This test example provides a method for recovering iodide scrap, and all aspects were the same as in Test Example 15 except that the temperature of the second distillation was 690°C. Test Example 21

[0139] This test example provides a method for recovering iodide scrap, and all aspects were the same as in Test Example 15 except that the temperature of the second distillation was 730°C. Test Example 22

[0140] This test example provides a method for recovering iodide scrap, the method comprising the following steps.

[0141] (I) Iodide scrap similar to that in Test Example 15 was dissolved in water to obtain saturated wastewater.

[0142] (II) Activated carbon was added to the saturated waste liquid, stirred to allow adsorption, and then suction filtration was performed to obtain an iodide solution.

[0143] (III) The iodide solution was concentrated and crystallized to obtain iodide crystal particles.

[0144] (IV) The iodide crystal particles are subjected to an absolute pressure of 3 × 10 -3Potassium iodide was obtained by performing the first distillation under the condition that the temperature was 460 °C and the pressure was continued until the absolute pressure reached 3×10 -3 Pa. Sodium iodide was obtained by performing the second distillation under the condition that the temperature was 710 °C and the absolute pressure was 3×10

[0145] The purity and recovery rate of sodium iodide obtained in Test Examples 15 to 22 are as shown in Table 3.

[0146]

Table 3

[0147] This test example provides a method for recovering iodide scraps, and the method includes the following steps.

[0148] (I) An iodide scrap composed of cesium iodide scrap and thallium iodide scrap (the cesium iodide content was 82.9 wt% and the thallium iodide content was 0.42 wt%) was dissolved in water to obtain a saturated waste liquid.

[0149] (II) Activated carbon was added to the saturated waste liquid, stirred and adsorbed, and then suction filtration was performed to obtain a solution of iodide.

[0150] (III) The solution of iodide was concentrated and crystallized to obtain iodide crystal particles.

[0151] (IV) The iodide crystal particles were vacuum heated at 310 °C for 11 h under an absolute pressure of 3×10 3 Pa to remove crystal water, and then the first distillation was performed under the condition that the absolute pressure was 3×10 -3 Pa and the temperature was 460 °C to obtain thallium iodide, and then the second distillation was performed under the condition that the absolute pressure was 3×10 -3 Pa and the temperature was 660 °C to obtain cesium iodide. Test Example 24

[0152] This test example provides a method for recovering iodide scraps, and the method includes the following steps.

[0153] (I) Scrap iodide similar to Test Example 23 was dissolved in water to obtain a saturated waste liquid.

[0154] (II) Activated carbon was added to the saturated waste liquid, stirred and adsorbed, and then suction filtration was performed to obtain a solution of iodide.

[0155] (III) The iodide solution was concentrated and crystallized to obtain iodide crystal particles.

[0156] (IV) The iodide crystal particles were vacuum heated at an absolute pressure of 3×10 3 Pa and a temperature of 300 °C for 12 h to remove crystal water, and then the first distillation was performed at an absolute pressure of 3×10 -3 Pa and a temperature of 450 °C to obtain thallium iodide, and subsequently the second distillation was performed at an absolute pressure of 3×10 -3 Pa and a temperature of 650 °C to obtain cesium iodide. Test Example 25

[0157] This test example provides a method for recovering scrap iodide, and the method includes the following steps.

[0158] (I) Scrap iodide similar to Test Example 23 was dissolved in water to obtain a saturated waste liquid.

[0159] (II) Activated carbon was added to the saturated waste liquid, stirred and adsorbed, and then suction filtration was performed to obtain a solution of iodide.

[0160] (III) The iodide solution was concentrated and crystallized to obtain iodide crystal particles.

[0161] (IV) The iodide crystal particles were vacuum heated at an absolute pressure of 3×10 3 Pa and a temperature of 320 °C for 10 h to remove crystal water, and then the first distillation was performed at an absolute pressure of 3×10 -3 Pa and a temperature of 470 °C to obtain thallium iodide, and subsequently the second distillation was performed at an absolute pressure of 3×10 -3A second distillation was performed under conditions of Pa and a temperature of 680°C to obtain cesium iodide. (Test Example 26)

[0162] This test example provides a method for recovering iodide scrap, and all aspects were the same as in Test Example 23 except that the temperature of the second distillation was 640°C. Test Example 27

[0163] This test example provides a method for recovering iodide scrap, and all aspects were the same as in Test Example 23 except that the temperature of the second distillation was 690°C. Test Example 28

[0164] This test example provides a method for recovering iodide scrap, the method comprising the following steps.

[0165] (I) Iodide scrap similar to that used in Test Example 23 was dissolved in water to obtain saturated wastewater.

[0166] (II) Activated carbon was added to the saturated waste liquid, stirred to allow adsorption, and then suction filtration was performed to obtain an iodide solution.

[0167] (III) The iodide solution was concentrated and crystallized to obtain iodide crystal particles.

[0168] (IV) The iodide crystal particles are subjected to an absolute pressure of 3 × 10 -3 The first distillation was performed under conditions of Pa and a temperature of 460°C to obtain thallium iodide, and then the absolute pressure was increased to 3 × 10⁻⁶. -3 A second distillation was performed under conditions of Pa and a temperature of 660°C to obtain cesium iodide.

[0169] The purity and recovery rate of cesium iodide obtained in Test Examples 23 to 28 are shown in Table 4.

[0170] [Table 4]

[0171] In summary, the method according to the present invention does not require the addition of other materials during recovery, can obtain iodide with a purity of 4N or higher, enables scrap recycling, reduces costs, and further reduces environmental pollution from scrap, thereby achieving green recycling.

[0172] The above description is merely a specific embodiment of the present invention, but the applicant states that the scope of protection of the present invention is not limited thereto, and that those skilled in the art should understand that all modifications or substitutions that are readily conceivable to those skilled in the art within the technical scope disclosed herein are included within the scope of protection and disclosure of the present invention.

Claims

1. The process involves the steps of: dissolving iodide scrap, treating it with activated carbon adsorption, and performing solid-liquid separation to obtain an iodide solution; The steps include concentrating and crystallizing the iodide solution to obtain iodide crystal particles, The process includes the step of sequentially vacuum heating and vacuum distillation of the iodide crystal particles to obtain iodide with a purity of 4N or higher. A method for recovering iodide scrap characterized by the following:

2. The iodide scrap includes cesium iodide scrap or sodium iodide scrap. The method for recovering iodide scrap according to feature 1.

3. The temperature of the vacuum heating is 300°C to 320°C. and / or, the vacuum heating time is 10 hours or more. and / or the absolute pressure of the vacuum heating is 3 × 10 ３ It is less than or equal to Pa. The method for recovering iodide scrap according to feature 2.

4. The absolute pressure of the vacuum distillation is 3 × 10⁻⁶ －３ It is less than or equal to Pa, and / or, if the iodide scrap is cesium iodide scrap, the vacuum distillation temperature is 650°C to 680°C. and / or, if the iodide scrap is sodium iodide scrap, the vacuum distillation temperature is 700°C to 720°C. The method for recovering iodide scrap according to feature 2.

5. The iodide scrap further comprises thallium iodide scrap. The method for recovering iodide scrap according to feature 2.

6. The temperature of the vacuum heating is 300°C to 320°C. and / or, the vacuum heating time is 10 hours or more. and / or the absolute pressure of the vacuum heating is 3 × 10 ３ It is less than or equal to Pa. The method for recovering iodide scrap according to feature 5.

7. The absolute pressure of the vacuum distillation is 3 × 10⁻⁶ －３ It is less than or equal to Pa, and / or the vacuum distillation includes a first distillation and a second distillation performed in sequence, Thallium iodide is recovered and obtained in the first distillation, and cesium iodide or sodium iodide is recovered and obtained in the second distillation, and / or, the temperature at which thallium iodide is recovered and obtained in the first distillation is 450°C to 470°C. and / or, the temperature at which cesium iodide is recovered and obtained in the second distillation is 650°C to 680°C. and / or, the temperature at which sodium iodide is recovered and obtained in the second distillation is 700°C to 720°C. The method for recovering iodide scrap according to feature 5.

8. The solution obtained by dissolving the iodide scrap is a saturated aqueous solution. The method for recovering iodide scrap according to feature 1.

9. The activated carbon used in the activated carbon adsorption treatment is required to have an ash content of ≤ 5 wt%, an iodine adsorption value of ≥ 600 mg / g, and an average particle size of ≥ 5 mm. The method for recovering iodide scrap according to feature 1.

10. The aforementioned solid-liquid separation method includes suction filtration. The method for recovering iodide scrap according to feature 1.

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