A method for recovering rare and precious metal evaporation residues

Abstract

The present invention provides a method for recovering rare and precious metal evaporation residues, comprising: S1, classifying the residue crucibles containing the rare and precious metal evaporation residues, acid-washing, and then water-rinsing to remove residual water; S2, fixing the residue crucibles and arranging a receiving crucible below, so that the residue crucible is arranged above the receiving crucible at a certain inclination angle to ensure that the fluid in the residue crucible can flow into the receiving crucible without causing splashing; S3, preheating the residual crucible in a vacuum induction furnace after evacuation, then heating it to 1000-1800°C and maintaining the temperature, so that the rare and precious metals melt and flow from the residual crucible into the receiving crucible; S4, cooling the residual crucible to solidify the rare and precious metals in the receiving crucible, and then removing the rare and precious metals. This method can simply and efficiently recover high-purity rare and precious metals, with a high direct recovery rate, low pollution, and high efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of rare and precious metal recovery, and in particular relates to a method for recovering rare and precious metal evaporation residues. Background Art

[0002] High-purity rare and precious metals are essential base materials for evaporation coatings in the electronics industry, such as integrated circuits and semiconductor devices. With the continuous development of the integrated circuit industry, evaporation materials are required to have a purity of 99.999% or higher and to be completely clean. These materials are typically in the form of wires, rods, or blocks. The typical manufacturing process includes ingot melting and casting (static mold), plastic deformation processing, and heat treatment.

[0003] During the use of precious metal evaporation materials, a large amount of high-purity precious metals will inevitably remain in the molybdenum or tungsten crucible, resulting in serious waste of precious metals. The current industrial treatment process mainly includes a crushing-base metal embrittlement-aqua regia dissolution method. This method produces a large amount of acid mist and ammonia nitrogen tail gas, and is also seriously corrosive to equipment and has poor working conditions. In addition, during the nitrate removal and concentration process, some precious metals will be volatilized and lost, resulting in a reduced precious metal recovery rate. After the precious metals enter the solution, further separation and purification steps are required, which inevitably introduce other impurities and cause a small amount of precious metals to be dispersed in the solution or slag. In addition, another treatment method is to heat the crucible to melt the platinum and then pour it out. This method not only has poor operational continuity and low efficiency, but also easily sticks to the container or crucible wall, resulting in low yield and low metal purity, requiring further purification and processing. Summary of the Invention

[0004] To solve the above problems, this patent provides a method for recovering rare and precious metal evaporation residues. This method can simply and efficiently recover high-purity rare and precious metals with a high direct recovery rate, low pollution and high efficiency.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for recovering rare and precious metal evaporation residues, comprising:

[0007] S1. Classify the crucibles containing the evaporation residues of rare and precious metals, and then wash them with water after acid washing to remove the residual water;

[0008] S2. Fix the crucible containing the rare precious metal evaporation residue treated in S1, and place a receiving crucible below it, so that the crucible containing the rare precious metal evaporation residue is placed above the receiving crucible at a certain inclination angle to ensure that the fluid in the crucible containing the rare precious metal evaporation residue can all flow into the receiving crucible without causing splashing;

[0009] S3, placing the crucible containing the rare precious metal evaporation residue and the receiving crucible in a vacuum induction furnace, preheating them after evacuation, and then heating them to 1000-1800° C. for insulation, so that the rare precious metal melts and flows from the crucible containing the rare precious metal evaporation residue into the receiving crucible;

[0010] S4. Cool down to solidify the rare metal in the receiving crucible and take out the precious metal.

[0011] Preferably, in step S3, the insulation time is 10 to 30 minutes.

[0012] Preferably, in step S3, the heating rate is 10-20°C / min.

[0013] Preferably, in step S2, the tilt angle is 70-90°.

[0014] Preferably, in step S3, the vacuum degree after evacuation is 8-10 Pa.

[0015] Preferably, in step S3, the preheating temperature is 200-300°C.

[0016] Preferably, the rare and precious metals are one or more of gold, silver and platinum.

[0017] Preferably, the crucible containing the rare and precious metal evaporation residue is made of tungsten or molybdenum; and the receiving crucible is made of graphite or alumina.

[0018] Preferably, in step S1, the pickling is performed by using dilute hydrochloric acid, followed by water washing, and the residual water is removed by wiping with a dust-free cloth.

[0019] Preferably, step S3 further comprises cleaning the surface of the precious metal with hydrochloric acid and then washing with pure water.

[0020] Preferably, in step S1, the scrap crucible is fixed by a hollow crucible platform; the hollow crucible platform includes an upper and a lower part, the lower part is a hollow base, and the upper part is a hollow positioning platform, the positioning platform is provided with 3 to 5 or more crucible positioning positions for placing the scrap crucible, ensuring that the placed scrap crucible is 70 to 90 degrees with the horizontal direction, the bottom of the base is provided with a protrusion, and the base is clamped at the opening of the receiving crucible through the protrusion.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The method adopts a precious metal evaporation material crucible and a clean receiving crucible, and fixes the precious metal evaporation material crucible and the clean receiving crucible in a certain orientation to ensure that the fluid in the crucible containing the precious metal evaporation residue can all flow into the receiving crucible without causing splashing, and then performs high-temperature smelting, recovery and purification in a vacuum induction furnace. By prolonging the process of the metal entering the receiving crucible after melting, the rare precious metal melt is fully dispersed, and the volatilization of low-melting-point impurities contained in the precious metal evaporation material is promoted. Finally, high-purity rare precious metals are obtained in the receiving crucible, and the metal recovery rate is high, the purity is high, the process is short, and no wastewater or waste gas is generated.

[0023] The method is easy to operate, has high efficiency, and reduces precious metal loss. It has high direct recovery rate, high purity, small amounts of acid and alkali used in the recovery process, and a short process. It avoids the conventional precious metal-containing evaporation material first destroying the tungsten-molybdenum crucible, large equipment investment, and the treatment process that easily causes precious metal loss. After crushing, aqua regia is used for leaching. Aqua regia has severe corrosion and consumes a large amount of acid, which easily causes precious metal loss with the volatilization of acid vapor and also produces a large amount of ammonia nitrogen wastewater.

[0024] The direct recovery rate of precious metals by this method can reach over 99.5%, and the purity of the obtained metals can reach 99.99-99.995%. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 Schematic diagrams of top view and cross-section of the crucible platform, where (a) is a schematic diagram of top view and (b) is a schematic diagram of cross-section.

[0027] Figure 2 A three-dimensional schematic diagram of the crucible platform.

[0028] Figure 3 It is a schematic cross-sectional view of the assembly of the receiving crucible and the crucible platform.

[0029] Figure 4 1 is a comparison of the crucible of the residual gold-containing evaporation material in Example 1 before and after treatment, wherein (a) is the picture before treatment and (b) is the picture after treatment.

[0030] Figure 5 The figures are comparison pictures of the residual crucible containing platinum evaporation material before and after treatment in Example 2, wherein (a) is the picture before treatment and (b) is the picture after treatment.

[0031] Reference numerals:

[0032] 1. Crucible platform; 11. Positioning platform; 12. Base; 2. Receiving crucible; 3. Residue crucible. DETAILED DESCRIPTION

[0033] To facilitate understanding of the present invention, the present invention will be described in more comprehensive and detailed form below in conjunction with the accompanying drawings and preferred embodiments. However, the scope of protection of the present invention is not limited to the following specific embodiments.

[0034] The present invention provides a method for recovering rare and precious metal evaporation residues, comprising:

[0035] S1. Classify the crucibles containing the precious metal evaporation residues, pickle them and then rinse them with water to remove the residual water;

[0036] S2. Fix the crucible containing the rare precious metal evaporation residue treated in S1, and place a receiving crucible below it, so that the crucible containing the rare precious metal evaporation residue is placed above the receiving crucible at a certain inclination angle to ensure that the fluid in the crucible containing the rare precious metal evaporation residue can all flow into the receiving crucible without causing splashing;

[0037] S3, placing the crucible containing the rare precious metal evaporation residue and the receiving crucible in a vacuum induction furnace, evacuating the crucible and preheating them, then heating them to 1000-1800° C. and keeping them warm, so that the precious metal melts and flows from the crucible containing the precious metal evaporation residue into the receiving crucible;

[0038] S3. Cool down to solidify the precious metal in the receiving crucible and take out the precious metal.

[0039] In one embodiment, in step S3, the insulation time is 10 to 30 minutes.

[0040] In one embodiment, in step S3, the heating is performed slowly, which is beneficial for drying the material and the crucible, preventing the crucible from cracking and the material from splashing; on the other hand, the material slowly melts and flows out, which helps volatilize impurities and reduces the splashing loss of the metal solution; the heating rate is 10 to 20°C / min.

[0041] In one embodiment, in step S3, the vacuum degree after vacuuming is 8-10 Pa.

[0042] In one embodiment, in step S2, the tilt angle is 70-90°; the crucible containing the precious metal evaporation residue is placed 15-20 cm above the receiving crucible, and can also be set as needed.

[0043] In one embodiment, in step S3, the preheating temperature is 200-300° C. to remove moisture and avoid problems such as cracking caused by rapid heating of the crucible; and the preheating time is 20-30 minutes.

[0044] Optionally, the precious metal is one or more of gold, silver, and platinum.

[0045] In one embodiment, the crucible containing the precious metal evaporation residue is made of tungsten or molybdenum; and the receiving crucible is made of graphite or alumina.

[0046] In one embodiment, the pickling is performed by washing with dilute hydrochloric acid, followed by water washing, and the residual water is removed by wiping with a dust-free cloth.

[0047] In one embodiment, step S3 further includes cleaning the surface of the precious metal with hydrochloric acid, then washing with pure water, and drying.

[0048] In one embodiment, in step S2, the residual crucible 3 containing the evaporation residue of rare precious metals is fixed by a hollow crucible platform 1, and the crucible platform 1 includes an upper and a lower part. The upper part of the crucible platform 1 is a hollow positioning platform 11, and the lower part of the crucible platform 1 is a base 12. The positioning platform 11 is provided with 3 to 5 or more crucible positions for placing the crucible containing the evaporation residue of precious metals, ensuring that the placed residual crucible 3 is 70 to 90 degrees with the horizontal direction, which is easy to control the flow rate of the molten metal. The bottom of the base 12 is provided with a protrusion, and the base 12 is clamped at the opening of the receiving crucible 2 through the protrusion to ensure that the precious metal melt It can flow directly from the residual crucible 3 into the receiving crucible. The base 12 is a hollow cylinder. The cross section of the inner wall of the cylindrical hollow base 12 is trumpet-shaped. The trumpet opens downward into a 60-90° cone shape, which helps the high-temperature molten metal melt to drip without sticking to the crucible wall. The receiving crucible 2 is 10-15 cm high and the crucible height can also be adjusted according to actual needs. The receiving crucible has an arc-shaped bottom for easy demoulding or other different regular shapes as needed, such as rectangle, square, circle or triangle, etc. It can also be funnel-shaped. During the smelting process, the precious metal melt flows from the residual crucible 3 containing precious metal evaporation residues in the crucible position into the receiving crucible 2 to obtain metal particles. The top view of the crucible platform 1 is as shown in FIG. Figure 1 (a) shows the cross-sectional view. Figure 1 (b) shows the stereogram. Figure 2 As shown, the assembly cross-sectional diagram of the receiving crucible 2 and the crucible platform 1 is as shown in FIG. Figure 3 shown.

[0049] Example 1

[0050] Take the residual crucible 3 containing gold evaporation material, first clean the surface with 2% HCl, then rinse it twice with pure water and wipe it dry with a dust-free cloth, and clamp it in the clamping position of the crucible platform 1. The residual crucible 3 is at 90 degrees to the horizontal. The crucible platform 1 is placed on the 15 cm high receiving crucible 2. Evacuate to about 10 Pa, preheat the graphite crucible at 300℃ for 30 minutes, then slowly increase the temperature to 1200℃ at 10℃ / min, keep it warm for 20 minutes, and then slowly cool it to room temperature. Take out the gold nugget and clean the surface dust with 2% HCl. The gold purity is 99.995% and the yield is 99.7%. The comparison diagram of the residual crucible containing gold evaporation material before and after treatment is shown as follows. Figure 4 shown.

[0051] Example 2

[0052] Take the residual crucible 3 containing platinum evaporation material, first clean the surface with 2% HNO3, then rinse it twice with pure water and wipe it dry with a dust-free cloth, and clamp it in the clamping position of the crucible platform 1. The residual crucible 3 is 80 degrees to the horizontal. The crucible platform 1 is placed on the 10 cm high receiving crucible 2. Evacuate to about 10Pa, preheat the graphite crucible at 300℃ for 30min, then slowly heat it to 1800℃ at 15℃ / min, keep it warm for 30min, and then slowly cool it to room temperature. Take out the platinum block and clean the surface dust with 2% HCl. The platinum purity is 99.99% and the yield is 99.2%. The comparison diagram of the residual crucible containing platinum evaporation material before and after treatment is as follows: Figure 5 shown.

[0053] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for recovering rare and precious metal evaporation residues, characterized in that: include: S1. Classify the residual crucibles containing the evaporation residues of rare precious metals, pickle them and then rinse them with water to remove residual water; S2. Fix the scrap crucible processed by S1, and arrange a receiving crucible below, so that the scrap crucible is arranged above the receiving crucible at a certain inclination angle to ensure that the fluid in the scrap crucible can all flow into the receiving crucible without causing splashing; the scrap crucible is fixed by a hollow crucible platform; the hollow crucible platform includes an upper and a lower part, the lower part is a hollow base, and the upper part is a hollow positioning platform, the positioning platform is provided with 3 to 5 crucible positioning positions for placing the scrap crucible, ensuring that the placed scrap crucible is 70 to 90 degrees with the horizontal direction, the bottom of the base is provided with a protrusion, and the base is clamped at the opening of the receiving crucible through the protrusion; S3, placing the scrap crucible and the receiving crucible in a vacuum induction furnace, preheating them after evacuation, and then heating them to 1000-1800°C for insulation, so that the rare metal melts and flows from the scrap crucible into the receiving crucible; S4. Cool down to solidify the precious metal in the receiving crucible, and take out the precious metal.

2. The method for recovering rare and precious metal evaporation residues according to claim 1, wherein: In step S3, the insulation time is 10 to 30 minutes.

3. The method for recovering rare and precious metal evaporation residues according to claim 1, wherein: In step S3, the heating rate is 10-20°C / min.

4. The method for recovering rare and precious metal evaporation residues according to claim 1, wherein: In step S2, the tilt angle is 70-90°.

5. The method for recovering rare and precious metal evaporation residues according to claim 1, wherein: In step S3, the vacuum degree after the vacuuming is 8-10 Pa.

6. The method for recovering rare and precious metal evaporation residues according to any one of claims 1 to 5, characterized in that: In step S3, the preheating temperature is 200-300°C.

7. The method for recovering rare and precious metal evaporation residues according to any one of claims 1 to 5, characterized in that: The rare and precious metals are one or more of gold, silver and platinum.

8. The method for recovering rare and precious metal evaporation residues according to any one of claims 1 to 5, characterized in that: The residual material crucible is made of tungsten or molybdenum; the receiving crucible is made of graphite or alumina.

9. The method for recovering rare and precious metal evaporation residues according to any one of claims 1 to 5, characterized in that: In step S1, the pickling is performed by using dilute hydrochloric acid, followed by water washing, and the residual water is removed by wiping with a dust-free cloth.

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