CN102465205B - Method for recycling gold from surface coating of scanning electron microscope sample - Google Patents
Method for recycling gold from surface coating of scanning electron microscope sample Download PDFInfo
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- CN102465205B CN102465205B CN2010105358077A CN201010535807A CN102465205B CN 102465205 B CN102465205 B CN 102465205B CN 2010105358077 A CN2010105358077 A CN 2010105358077A CN 201010535807 A CN201010535807 A CN 201010535807A CN 102465205 B CN102465205 B CN 102465205B
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Abstract
The invention provides a method for recycling gold from a surface coating of a scanning electron microscope sample. The method comprises the following steps of: (1), carrying out high-temperature roasting on a sample with a gold coating, which is represented to be used, of a scanning electron microscope, at an inert atmosphere or reducing atmosphere, wherein the roasting temperature is 1050-1250 DEG C; (2) selectively reducing the sample subjected to high-temperature roasting; (2) soaking the sample processed in the step (1) or the step (2) with a nitric acid and hydrogen peroxide mixing solution, wherein the preferable soaking time is 10-72h; and (4) separating the soaking solution in the step (3) from the sample, and recycling solid gold particles from the soaking solution by utilizing a solid-liquid separation method. Due to adoption of the method disclosed by the invention, the superfine gold particles on the surface of the scanning electron microscope sample can be effectively separated and recycled by using a low-toxicity chemical reagent and a simple process.
Description
Technical field
The present invention relates to the spraying plating of a kind of scanning electron microscope example sample making course to the recovery method of the gold of sample surfaces.
Background technology
At material science, be the performance of understanding material better and the relation between the microtexture, adopt electron microscope, as scanning electronic microscope (abbreviation scanning electron microscope) pattern of material and silk weaving structure being observed is a kind of research means commonly used.For most of materials of studying, even do not have electroconductibility owing to the electroconductibility of sample own is not good, so when carrying out morphology observation with scanning electron microscope, usually need be at its surperficial spraying plating one deck gold conducting film, avoiding scanning electron in sample surfaces generation electric charge accumulation, thereby obtain scanning electron microscope image clearly.Through estimation, the gold grade that the scanning electron microscope example surface is contained is higher, and gold content reaches 5～20g/kg, is more than 5 times of gold content in general gold ore and the general Au catalyst, therefore has higher recovery value.Yet the gold coating on current scanline electron microscopic sample surface does not still have the method recycled, abandons processing but do with scanning electron microscope example.
The recovery method of device coating gold mainly contains " cyanide process ", " chloroazotic acid method " and " iodo-sodium iodide method " etc. at present, but the aforesaid method chemical process faces complex process, cost is higher, process cycle is long, the chemical reagent consumption is more, and problem such as reagent toxicity is bigger.
CN100447264C discloses a kind of method that reclaims gold from waste of gold plating procedure.This method utilizes the settling velocity of the goldleaf characteristics slow than matrix that goldleaf is separated with matrix, reclaims gold from waste of gold plating procedure.By acid treatment, burn or utilize the gold-plated characteristics different with the cold shrinkage coefficient of matrix thermal expansion that the goldleaf in the broken waste of gold plating procedure is peeled off from matrix, pour water in the mixed body after peeling off, the settling velocity of visible goldleaf is slow than matrix when stopping to wash by water, matrix sinks to container bottom very soon, and goldleaf is suspended in to sink gradually in the water, topple over the water in the container this moment, and then goldleaf flows out with water, and matrix is stayed in the container.This method utilizes the settling velocity of the goldleaf characteristics slow than matrix that goldleaf is separated with matrix, reclaims gold from waste of gold plating procedure, does not reclaim but this method is suitable for the gold of scanning electron microscope example conducting film.CN100467631C then provides a kind of method that reclaims gold and copper from gold-plated printed circuit board waste material, with hydrogen peroxide and sulfuric acid as reaction reagent, from gold-plated printed circuit board waste material, reclaim Jin Hetong, agents useful for same is nontoxic, cheap, be easy to get, experimentation does not have nuisance and produces, equipment is simple, and is easy to operate.
The recovery method of above-mentioned coating gold, the gold that can be used for scanning electron microscope example surface spraying plating as " cyanide process ", " chloroazotic acid method " and chemical methods such as " iodo-sodium iodide methods " reclaims, but its drawback is self-evident.The gold recovery method that CN100447264C and CN100467631C adopt, chemical reagent toxicity is low and technology is simply effective, but the recovery method of the gold that both provide, critical step is the separating treatment after gold coating comes off from matrix.For telecommunications and the used gold-plated device of other industry, plated thickness is generally 0.5～10 μ m, and under this large-size, coating gold film is comparatively fine and close firm, and the gold that comes off from matrix obviously is separated easily and carries out subsequent processes.Different with common coating gold, gold thickness of coating on the scanning electron microscope example is generally 10～20nm, the I of the particle size of gold reaches 2nm, little size of particles like this, after peeling off, matrix is difficult to direct viewing, be difficult to carry out separating treatment by ordinary methods such as filtrations, and also be difficult to peel off from matrix.Therefore adopt method that above-mentioned prior art provides effectively not separate and carry out subsequent disposal it.
Summary of the invention
For overcoming the weak point of existing coating Recovery of Gold from Wastewater, the invention provides a kind of recovery method that is applicable to scanning electron microscope example overlay coating gold.The method according to this invention adopts the low toxicity chemical reagent the ultra-fine gold granules on scanning electron microscope example surface effectively can be separated and reclaim with simple technology.
The recovery method of scanning electron microscope example overlay coating gold of the present invention comprises following content:
(1) scanning electron microscope is characterized with the sample of crossing with gold plated film, carry out high-temperature roasting under inert atmosphere or reducing atmosphere, the temperature of roasting is 1050～1250 ℃, and preferred roasting time is 2～10 hours;
(2) selectable reduction step also can not adopt this step, and preferred method of reducing is: the sample after the high-temperature roasting is in the presence of hydrogen, 300～600 ℃ of reduction 1～10 hour;
(3) sample after step (1) or step (2) are handled soaks with nitric acid and hydrogen peroxide mixed solution, and preferred soak time is 10～72 hours;
(4) step (3) soaking solution and sample separation contain gold particles in the soaking solution, adopt the method for solid-liquid separation to reclaim the solid gold particles.
In the inventive method, the described inert atmosphere of step (1) is preferably nitrogen atmosphere, and reducing atmosphere is preferably the hydrogen-nitrogen mixture atmosphere of hydrogen atmosphere or hydrogen volume content 0.1%～10%.
In the inventive method, atmospheric operation is adopted in the described high-temperature roasting of step (1).Preferably in roasting apparatus, use reductor jointly, reductor such as carbon black, gac, metal reductor etc. with the sample of gold plated film.
In the inventive method, it is the gold plated film sample of matrix that the described sample with gold plated film of step (1) is preferably with the aluminum oxide, comprises various aluminum oxide or is catalyzer of carrier etc. with the aluminum oxide.
In the inventive method, the described reduction step working pressure of step (2) can for normal pressure to 5MPa.
In the inventive method, the described nitric acid of step (3) and hydrogen peroxide mixed solution are that nitric acid and hydrogen peroxide volume ratio are 4: 1～6: 1 mixing solutions, and used concentration of nitric acid is 1～3mol/L, and used hydrogen peroxide mass concentration is 10%～40%.In mass, nitric acid and hydrogen peroxide mixed solution consumption are 2～10 times of gold plated film sample.
In the inventive method, in the step (4), soaking solution and sample separation can adopt simply topple over, mode such as discharge opeing gets final product, and preferably stirs before separation, and the gold particles of peeling off is suspended in the soaking solution.The gold particles that contains in the soaking solution adopts the method for solid-liquid separation such as centrifugation to reclaim the solid gold particles.The solia particle that centrifugation gets can wash methods such as centrifugation, oven dry and further purify, and the liquid phase of centrifugation can be further used for washing the sample that separates behind the soaking solution.
The present invention is according to the characteristics of scanning electron microscope example surface gold coating; at first make its sintering be converted into macrobead or fine and close continuous film by high-temperature roasting; being placed on then in nitric acid and the hydrogen peroxide mixed solution peels off gold grain from aluminum oxide; high-temperature roasting can use sample gold plated film to be converted into macrobead on the one hand; separation after being convenient to; the gold plated film is easy to and peels off substantially, adopt low toxicity solution namely can reach the effect of fully peeling off.Reduction step after the suitable roasting condition of employing (reducing atmosphere or adding solid oxygen scavenger etc.) or the roasting can be avoided the gold oxidation, further improves the rate of recovery.The solid gold particles that the inventive method is peeled off generally can reach more than the 100nm, can be suspended in the soaking solution and then by solid-liquid separation and sample and separate, and be conducive to follow-up gold solid recovery.The used chemical reagent of the present invention is nitric acid and hydrogen peroxide, and with low cost, toxicity is low, and consumption is few, and environmental pollution is little, and the gold recovery method is simple.
Embodiment
Below by the detailed explanation in addition of the inventive method of embodiment, percentage composition wherein is benchmark with the quality.
Embodiment 1
Alumina powder surface coverage one deck carbon black of the spraying plating gold after scanning electron microscope analysis characterized, the 1050 ℃ of following roastings of tube furnace 10 hours that place logical high pure nitrogen, then in hydrogen production device under 400 ℃, 3MPa with hydrogen reducing 3 hours.The mixed solution of preparation nitric acid and hydrogen peroxide: concentration of nitric acid is 1mol/L, and hydrogen peroxide concentration is 40%, and both volume ratios are 4: 1.After nitric acid and hydrogen peroxide mix, with the sample after the roasting be soaked in 3 times in the mixed solution of its quality 70 hours.After soak finishing, under stirring action, discharge soak solution, by supercentrifuge with the soak solution centrifugation, skim supernatant liquid, add distilled water in the centrifuge tube, the ultra-sonic dispersion seabed sediment, and then use high speed centrifugation to separate, carry out repeatedly 5 times, till washings is neutrality.After the washes oven dry, get solid-state gold.Fineness of gold can reach 97% by analysis, and the rate of recovery can reach 97.5%.
Embodiment 2
Spraying plating gold after scanning electron microscope analysis characterized be the hydrogenation catalyst of carrier with the aluminum oxide, place to feed 1150 ℃ of following roastings of tube furnace 4 hours that hydrogen volume content is nitrogen-hydrogen gas mixture of 1%, naturally cool to room temperature then.The mixed solution of preparation nitric acid and hydrogen peroxide: concentration of nitric acid is 2mol/L, and hydrogen peroxide concentration is 30w%, and both volume ratios are 5: 1.After nitric acid and hydrogen peroxide mix, with the sample after the roasting be soaked in 3 times in the mixed solution of its quality 48 hours.After soaking end, with the soak solution centrifugation, skim supernatant liquid by supercentrifuge, add distilled water in the centrifuge tube, the ultra-sonic dispersion seabed sediment, and then use high speed centrifugation to separate, carry out repeatedly 5 times, till washings is neutrality.After the washes oven dry, get solid-state gold.Fineness of gold can reach 95.3% by analysis, and the rate of recovery can reach 94.5%.
Embodiment 3
Spraying plating gold after scanning electron microscope analysis characterized be 1250 ℃ of following roastings of tube furnace 2 hours that hydrogenation catalyst surface coverage one deck carbon black of carrier places logical pure nitrogen gas with the aluminum oxide, then in hydrogen production device under 450 ℃, 3MPa with hydrogen reducing 2 hours.The mixed solution of preparation nitric acid and hydrogen peroxide: concentration of nitric acid is 3mol/L, and hydrogen peroxide concentration is 40w%, and both volume ratios are 6: 1.After nitric acid and hydrogen peroxide mix, with the sample after the roasting be soaked in 2 times in the mixed solution of its quality 24 hours.After soaking end, with the soak solution centrifugation, skim supernatant liquid by supercentrifuge, add distilled water in the centrifuge tube, the ultra-sonic dispersion seabed sediment, and then use high speed centrifugation to separate, carry out repeatedly 5 times, till washings is neutrality.After the washes oven dry, get solid-state gold.Fineness of gold can reach 95.9% by analysis, and the rate of recovery can reach 96.7%.
Claims (8)
1. the recovery method of a scanning electron microscope example overlay coating gold is characterized in that adopting a kind of in the following dual mode:
Mode one:
(1) scanning electron microscope is characterized with the sample of crossing with gold plated film, carry out high-temperature roasting under reducing atmosphere, the temperature of roasting is 1050～1250 ℃;
(2) the selectable reduction step of sample after the high-temperature roasting;
(3) sample after step (1) or step (2) are handled soaks with nitric acid and hydrogen peroxide mixed solution;
(4) step (3) soaking solution and sample separation contain gold particles in the soaking solution, adopt the method for solid-liquid separation to reclaim the solid gold particles;
Mode two:
(1) scanning electron microscope is characterized with the sample of crossing with gold plated film, carry out high-temperature roasting under inert atmosphere, the temperature of roasting is 1050～1250 ℃;
(2) reduction step of sample after the high-temperature roasting;
(3) sample after step (2) is handled soaks with nitric acid and hydrogen peroxide mixed solution;
(4) step (3) soaking solution and sample separation contain gold particles in the soaking solution, adopt the method for solid-liquid separation to reclaim the solid gold particles;
Wherein the described sample with gold plated film of the step of dual mode (1) is for being the gold plated film sample of matrix with the aluminum oxide;
Wherein the reduction step of the step of dual mode (2) is: the sample after the high-temperature roasting is in the presence of hydrogen, 300～600 ℃ of reduction 1～10 hour.
2. it is characterized in that in accordance with the method for claim 1: roasting time is 2～10 hours in the step (1).
3. in accordance with the method for claim 1, it is characterized in that: the described inert atmosphere of step (1) is nitrogen atmosphere, and reducing atmosphere is the hydrogen-nitrogen mixture atmosphere of hydrogen atmosphere or hydrogen volume content 0.1%～10%.
4. in accordance with the method for claim 1, it is characterized in that: the described high-temperature roasting of step (1) is for using reductor jointly with the sample of gold plated film in roasting apparatus, reductor comprises carbon black, gac or metal reductor.
5. in accordance with the method for claim 1, it is characterized in that: the described nitric acid of step (3) and hydrogen peroxide mixed solution are that nitric acid and hydrogen peroxide volume ratio are 4: 1～6: 1 mixing solutions, used concentration of nitric acid is 1～3mol/L, and used hydrogen peroxide mass concentration is 10%～40%.
6. according to claim 1 or 5 described methods, it is characterized in that: in the step (3), in mass, nitric acid and hydrogen peroxide mixed solution consumption are 2～10 times of gold plated film sample, and soak time is 10～72 hours.
7. in accordance with the method for claim 1, it is characterized in that: in the step (4), stir before soaking solution and the sample separation, the gold particles of peeling off is suspended in the soaking solution.
8. in accordance with the method for claim 1, it is characterized in that: in the step (4), the gold particles that contains in the soaking solution adopts the solid-liquid separating method of centrifugation to reclaim the solid gold particles.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2010105358077A CN102465205B (en) | 2010-11-04 | 2010-11-04 | Method for recycling gold from surface coating of scanning electron microscope sample |
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| CN2010105358077A CN102465205B (en) | 2010-11-04 | 2010-11-04 | Method for recycling gold from surface coating of scanning electron microscope sample |
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| CN102465205B true CN102465205B (en) | 2013-08-28 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US4668289A (en) * | 1985-11-22 | 1987-05-26 | Wisconsin Alumni Research Foundation | Method for reclaiming gold |
| CA2154608A1 (en) * | 1995-07-25 | 1997-01-26 | Mourad Michael Hanna | Method of purifying gold |
| CN1205345C (en) * | 2002-04-04 | 2005-06-08 | 中国石油化工股份有限公司 | Method of recovering noble metal from spent catalyst containing noble metal |
| CN100567528C (en) * | 2006-11-17 | 2009-12-09 | 南化集团研究院 | A kind of method that from waste palladium carbon catalyst, reclaims precious metal palladium |
| CN100447264C (en) * | 2007-04-13 | 2008-12-31 | 浙江理工大学 | Method for recovering gold from waste of gold plating procedure |
| CN101100706A (en) * | 2007-07-13 | 2008-01-09 | 东华大学 | Method for immersing gold from printing wiring board |
| JP5160926B2 (en) * | 2008-03-06 | 2013-03-13 | 株式会社今井金箔 | Method of peeling gold leaf from gold leaf-attached product and method of collecting gold |
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