CN112279297A - Method for selectively separating tin from electronic waste and synchronously preparing nano tin dioxide - Google Patents

Method for selectively separating tin from electronic waste and synchronously preparing nano tin dioxide Download PDF

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CN112279297A
CN112279297A CN202011343902.7A CN202011343902A CN112279297A CN 112279297 A CN112279297 A CN 112279297A CN 202011343902 A CN202011343902 A CN 202011343902A CN 112279297 A CN112279297 A CN 112279297A
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electronic waste
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CN112279297B (en
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苏子键
张元波
姜涛
侯炜
范晓慧
李光辉
郭宇峰
彭志伟
饶明军
刘硕
赵雪娟
王琰
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Central South University
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G19/00—Compounds of tin
    • C01G19/02—Oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00—Preliminary treatment of ores or scrap
    • C22B1/02—Roasting processes
    • C—CHEMISTRY; METALLURGY
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    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B25/00—Obtaining tin
    • C22B25/02—Obtaining tin by dry processes
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    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B25/00—Obtaining tin
    • C22B25/06—Obtaining tin from scrap, especially tin scrap
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Abstract

The invention discloses a method for synchronously preparing nano tin dioxide by selectively separating tin from electronic waste, which comprises the steps of uniformly mixing tin-containing electronic waste with an additive consisting of tin dioxide, inert alumina and silicon dioxide, placing the mixture in a weak oxidizing atmosphere to perform oxidizing roasting at 825-950 ℃, and placing roasted volatile matter in a strong oxidizing atmosphere to perform oxidizing roasting at 500-700 ℃ to obtain nano tin dioxide powder; the method takes the tin-containing electronic waste as the raw material, realizes the high-efficiency recovery of tin, prepares the high-purity nano tin dioxide powder material, realizes the comprehensive utilization of the electronic waste, obtains the product with higher economic value, has simple operation, low production cost and environmental protection, and meets the requirements of industrial production.

Description

Method for selectively separating tin from electronic waste and synchronously preparing nano tin dioxide
Technical Field
The invention relates to a method for recovering tin from tin-containing electronic waste, in particular to a method for efficiently separating tin from tin-containing electronic waste to obtain high-purity nano zinc oxide, and belongs to the technical field of electronic waste recovery.
Background
Electronic waste in urban mines contains abundant rare metal and precious metal resources, and is the key point of extracting metallurgy in the future. Unlike natural ore, most of the metal elements in the electronic waste exist in the form of simple metal and alloy, so the extraction metallurgical process cannot be completely similar to the traditional metallurgical process. Meanwhile, the electronic waste has various types and high content of metal elements, and if the electronic waste is completely put into the traditional pyrometallurgical and hydrometallurgical process, the loss rate of the metal elements is high, and particularly, in the pyrometallurgical process, precious metals such as gold and silver are easily dispersed in slag and are difficult to further enrich, separate and recover.
Compared with elements such as copper, gold, silver and indium, the value of tin in the electronic waste is relatively low, so that at present, no comprehensive recovery technology for tin in the electronic waste exists. Because the most-contained valuable metal element in the electronic waste is copper, the pretreated circuit board and the like are directly used as pyrometallurgical raw materials of the copper, copper products are obtained through the processes of blast furnace blowing, matte making, electrolytic refining and the like, in the process, a large amount of tin enters smoke dust or is dispersed into smelting slag, and the subsequent separation and recovery are difficult. The hydrometallurgy technology generally adopts an oxidant and an acid system to carry out oxidation leaching on metal elements in the circuit board, and then selective separation and recovery are realized through the difference of precipitation intervals of various metal ions, but the tin element is dissolved with elements such as lead, zinc, antimony and the like, the coincidence degree of the precipitation intervals is high, and thorough separation is difficult to realize; the purity of the precipitate is limited, and the precipitate can only be used as one of raw materials of tin pyrometallurgy, so that the product value is further reduced.
The tin oxide has excellent semiconductor properties, is widely applied to various aspects such as light, electricity, gas sensitivity and the like, and particularly has SO (sulfur oxide) resistance in the aspect of gas sensitive materials2、CO2、H2S、CH4And the detection limit of various toxic and harmful gases such as ethanol is sensitive, and the tin dioxide is one of the most mature gas-sensitive sensor raw materials in the current market. In order to ensure the performance, the material needs to have extremely fine particle size distribution and larger specific surface area.
Therefore, the selective and efficient separation of the metallic tin element in the electronic waste is realized, and the separated product is synchronously prepared into the high-purity nano tin dioxide product, so that the method has very important significance for resource utilization of the waste electronic products.
Disclosure of Invention
Aiming at the problems of low comprehensive recovery rate and low economic added value of metallic tin in tin-containing electronic waste in the prior art, the invention aims to provide a method for efficiently separating tin from tin-containing electronic waste in a high-temperature volatilization mode and recovering tin in a high-purity nano tin dioxide mode.
In order to achieve the technical purpose, the invention provides a method for synchronously preparing nano tin dioxide by selectively separating tin from electronic waste, which comprises the steps of uniformly mixing tin-containing electronic waste with an additive, placing the mixture in a weak oxidizing atmosphere to carry out oxidizing roasting at 825-950 ℃, and placing roasted volatile matter in a strong oxidizing atmosphere to carry out oxidizing roasting at 500-700 ℃ to obtain nano tin dioxide powder; the additive is a mixture of tin dioxide, inert alumina and silicon dioxide.
The key point of the method for synchronously preparing the nano tin dioxide by efficiently separating tin from the tin-containing electronic waste is to gradually oxidize and volatilize the metallic tin in the tin-containing electronic waste by cooperatively controlling the atmosphere and the temperature to obtain the high-purity nano tin dioxide powder. The tin-containing electronic waste enters a first-stage roasting area, the roasting is carried out under the control of higher temperature and weak oxidation atmosphere, the metallic tin with higher boiling point can be selectively oxidized into stannous oxide with low boiling point to volatilize under the condition, the stannous oxide enters a second-stage roasting area, the second-stage roasting area is regulated under the conditions of lower temperature and strong oxidation atmosphere, the stannous oxide can be completely oxidized into stannic oxide under the condition, monomer particles can be rapidly separated out from gas phase, and crystals can be controlled to grow into nano-scale stannic oxide particles. According to the technical scheme, the tin element can be selectively separated from the mixture material, oxidized step by step and nucleated in a homogeneous phase manner by means of sectional oxidation and synergistic control of the oxidizing atmosphere and temperature, so that the completely oxidized nano-scale tin dioxide powder is obtained.
The additive adopted by the invention consists of tin dioxide, inert alumina and silicon dioxide, wherein the tin dioxide plays a role of a weak oxygen catalyst and can promote the conversion of metallic tin to stannous oxide intermediate products and form gas-phase intermediate products; the inert alumina and the silica are both high-melting point inert substances, mainly improve the melting point of the system and promote the reaction, and do not react with tin oxide under the selected process conditions.
The inert alumina of the invention particularly refers to corundum crystal form alumina, which has compact structure and low reaction activity after being roasted at high temperature and is not easy to react with other metals and oxides.
As a preferable scheme, the tin-containing electronic waste is pretreated by a vacuum pyrolysis method or a mechanical crushing separation method, wherein the mass percent of tin is higher than 7.0%, and the mass percent of organic matters is lower than 0.5%. The organic content of the tin-containing electronic waste can be reduced by pretreating the tin-containing electronic waste through a vacuum pyrolysis method or a mechanical crushing and separating method, so that toxic organic gas generated in the roasting process is reduced, and the influence on the volatilization process of tin is reduced.
Preferably, the mass of the additive accounts for 5.0-10.0% of the total mass of the tin-containing electronic waste and the additive. Because the electronic waste contains a plurality of simple substances and alloys with low melting points, the melting point of the mixed material can be improved by adopting the additive, the stability of the metal tin is kept, and the stable conversion and volatilization of the tin to the intermediate product are promoted.
As a preferable scheme, the additive is composed of tin dioxide, inert alumina and silicon dioxide according to the mass ratio of 1 (25-40) to (30-50).
As a preferable scheme, in the process of oxidizing and roasting under a weak oxidizing atmosphere, the weak oxidizing atmosphere is controlled to be a mixed atmosphere of carbon dioxide and nitrogen, wherein the volume percentage concentration of the carbon dioxide is 2-5%, and the gas flow rate is 0.1-0.3 m/s. Under preferred conditions, the selective volatilization of tin as stannous oxide is primarily controlled.
Preferably, the oxidizing and roasting time is 60-120 min.
As a preferable scheme, in the process of oxidizing and roasting under a strong oxidizing atmosphere, the strong oxidizing atmosphere is controlled to be a mixed atmosphere of oxygen, carbon dioxide and nitrogen, wherein the volume percentage concentrations of the oxygen and the carbon dioxide are 5-10 vol.% and 1-2 vol.%, respectively, and the gas flow rate is 0.2-0.5 m/s. Under the optimized condition, the further oxidation of stannous oxide to stannic oxide is mainly favored, and the growth process of the crystal is controlled.
The tin-containing electronic waste is pretreated to remove organic components, and then is mainly mixed with metal powder, the main metal elements comprise lead, tin, zinc, copper, gold, silver, indium and the like, various metal elements exist in a simple substance or alloy phase form, in the simple substance component, the tin melting point is lowest, a liquid phase is easy to form to be bonded with other metals, the stability of tin can be kept under the action of a special additive, the tin is influenced by oxygen partial pressure in the oxidation process of the tin, if strong oxidizing atmosphere is directly adopted, the tin is directly oxidized into high boiling point tin-containing oxide, and the selective separation of the tin is difficult to realize The appearance is regular, and finally the nano-grade stannic oxide product with high purity and uniform granularity is obtained.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
1) the method takes the tin-containing electronic waste as the raw material, realizes resource utilization and green treatment of the solid waste, realizes sustainable development of tin resources, and obtains high-value products.
2) The invention realizes the staged gradual oxidation and separation of tin by cooperatively controlling the oxidation atmosphere and temperature, can efficiently separate and recover tin in the electronic waste, and has a recovery rate of over 90 percent.
3) The stannic oxide product prepared by the invention reaches the nanometer level, and the specific surface area is 100m2More than g, even granularity, and can be applied to a plurality of fields such as batteries, sensors, semiconductor materials and the like.
Drawings
Figure 1 XRD and microstructure analysis of the product prepared in example 1.
Detailed Description
The following examples are intended to further illustrate the present disclosure, but not to limit the scope of the claims.
Comparative example 1
The method comprises the following steps of (1) placing tin-containing electronic waste pyrolysis slag as a raw material (the tin content is 8.4%, and the organic matter content is 0.5%) in a two-section type controlled atmosphere roasting furnace for controlled atmosphere roasting; placing the material in a first-stage roasting area, wherein the first-stage atmosphere is a mixed weak oxidizing atmosphere of carbon dioxide and nitrogen, the concentration of the carbon dioxide is 3 vol.%, the roasting temperature is 950 ℃, and the gas flow rate is 0.2 m/s; the volatilized intermediate product enters a secondary roasting area along with airflow, the roasting temperature is 600 ℃, the secondary atmosphere is a mixed strong oxidizing atmosphere of oxygen, carbon dioxide and nitrogen, the oxygen concentration is 10 vol.%, the carbon dioxide concentration is 2 vol.%, and the gas flow rate is 0.2 m/s; the product can be separated and collected in the two-section area, the recovery rate of tin is 32.8 percent, and the purity of the nano tin dioxide product is 70.6 percent. This comparative example shows that without the addition of additives, the melting point of the system was low, the tin conversion rate and the separation recovery rate were low, and the obtained nano-powder was mixed with incompletely reacted components.
Comparative example 2
Taking tin-containing electronic waste pyrolysis slag as a raw material (the tin content is 8.4 percent, the organic matter content is 0.5 percent), adding a composite additive (the composite additive is a mixture of tin dioxide, inert alumina and silicon dioxide, and the ratio of the composite additive to the silicon dioxide is 1:25:30) according to the mass ratio of the materials being 10 percent, uniformly mixing the mixed materials, and placing the mixed materials into a one-stage type atmosphere-controllable roasting furnace for controlled atmosphere roasting; placing the material in a section of roasting area, wherein the atmosphere is a mixed strong-oxidizing atmosphere of oxygen, carbon dioxide and nitrogen, the concentration of oxygen is 10 vol.%, the concentration of carbon dioxide is 2 vol.%, the roasting temperature is 950 ℃, and the gas flow rate is 0.2 m/s; the product can be separated and collected in a section of area, the recovery rate of tin is 12.8 percent, and the purity of the nano tin dioxide product is 85.6 percent. This comparative example illustrates that during a calcination in a strongly oxidizing atmosphere, a large amount of tin, which has not yet formed a gaseous phase, is already peroxidized to form high-boiling oxides which remain in the mixture, which are detrimental to the separation of the tin and therefore have a very low conversion.
Example 1
Taking tin-containing electronic waste pyrolysis slag as a raw material (the tin content is 8.4 percent, the organic matter content is 0.5 percent), adding a composite additive (the composite additive is a mixture of tin dioxide, inert alumina and silicon dioxide, and the ratio of the composite additive to the silicon dioxide is 1:25:30) according to the mass ratio of 10 percent of the materials, uniformly mixing the mixed materials, and placing the mixed materials into a two-section type controlled atmosphere roasting furnace for controlled atmosphere roasting; the material is placed in a first roasting zone in a first atmosphere of carbon dioxide andmixing nitrogen with weak oxidizing atmosphere, wherein the concentration of carbon dioxide is 3 vol.%, the roasting temperature is 950 ℃, and the gas flow rate is 0.2 m/s; the volatilized intermediate product enters a secondary roasting area along with airflow, the roasting temperature is 700 ℃, the secondary atmosphere is a strong oxidizing atmosphere formed by mixing oxygen, carbon dioxide and nitrogen, the oxygen concentration is 10 vol.%, the carbon dioxide concentration is 2 vol.%, and the gas flow rate is 0.2 m/s; the product can be separated and collected in a two-section area, the recovery rate of the tin is 93.8 percent, the purity of the nano tin dioxide product is 98.6 percent, and the specific surface area of the tin dioxide is 126m2(ii) in terms of/g. (XRD phase analysis and microstructure analysis of the synthesized product are shown in FIG. 1, the grain size is 45nm, the theoretical purity is 98.7%, and the product dispersibility is good)
Example 2
Taking tin-containing electronic waste pyrolysis slag as a raw material (the tin content is 8.4 percent, the organic matter content is 0.5 percent), adding a composite additive (the composite additive is a mixture of tin dioxide, inert alumina and silicon dioxide, and the ratio of the composite additive to the silicon dioxide is 1:30:40) according to the mass ratio of 7 percent of the materials, uniformly mixing the mixed materials, and placing the mixed materials into a two-section type controlled atmosphere roasting furnace for controlled atmosphere roasting; placing the material in a first-stage roasting area, wherein the first-stage atmosphere is a mixed weak oxidizing atmosphere of carbon dioxide and nitrogen, the concentration of the carbon dioxide is 3 vol.%, the roasting temperature is 850 ℃, and the gas flow rate is 0.1 m/s; the volatilized intermediate product enters a secondary roasting area along with airflow, the roasting temperature is 700 ℃, the secondary atmosphere is a strong oxidizing atmosphere formed by mixing oxygen, carbon dioxide and nitrogen, the oxygen concentration is 8 vol.%, the carbon dioxide concentration is 2 vol.%, and the gas flow rate is 0.2 m/s; the product can be separated and collected in a two-section area, the recovery rate of tin is 94.2 percent, the purity of the nano tin dioxide product is 97.8 percent, and the specific surface area of the tin dioxide is 132m2/g。
Example 3
Taking tin-containing electronic waste pyrolysis slag as a raw material (the tin content is 8.4 percent, the organic matter content is 0.5 percent), adding a composite additive (the composite additive is a mixture of tin dioxide, inert alumina and silicon dioxide, and the ratio of the composite additive to the silicon dioxide is 1:35:50) according to the mass ratio of the materials being 10 percent, uniformly mixing the mixed materials, and placing the mixed materials into a two-section type controlled atmosphere roasting furnace for controlled atmosphere roasting; the material is placed in a first roasting areaThe first-stage atmosphere is a mixed weak oxidizing atmosphere of carbon dioxide and nitrogen, the concentration of the carbon dioxide is 2 vol.%, the roasting temperature is 900 ℃, and the gas flow rate is 0.1 m/s; the volatilized intermediate product enters a secondary roasting area along with airflow, the roasting temperature is 650 ℃, the secondary atmosphere is a strong oxidizing atmosphere formed by mixing oxygen, carbon dioxide and nitrogen, the oxygen concentration is 10 vol.%, the carbon dioxide concentration is 1 vol.%, and the gas flow rate is 0.2 m/s; the product can be separated and collected in a two-section area, the recovery rate of tin is 96.4 percent, the purity of the nano tin dioxide product is 98.3 percent, and the specific surface area of the tin dioxide is 139m2/g。
Example 4
The method comprises the following steps of taking a metal mixture obtained by a mechanical crushing separation method of tin-containing electronic waste as a raw material (the tin content is 7.6%, the organic matter content is 0.8%), adding a composite additive (the composite additive is a mixture of tin dioxide, inert alumina and silicon dioxide, the ratio of the composite additive to the silicon dioxide is 1:35:35) according to the mass ratio of 7.5%, uniformly mixing the mixed materials, and placing the mixed materials into a two-section type controlled atmosphere roasting furnace for controlled atmosphere roasting; placing the material in a first-stage roasting area, wherein the first-stage atmosphere is a mixed weak oxidizing atmosphere of carbon dioxide and nitrogen, the concentration of the carbon dioxide is 5 vol.%, the roasting temperature is 925 ℃, and the gas flow rate is 0.3 m/s; the volatilized intermediate product enters a secondary roasting area along with airflow, the roasting temperature is 650 ℃, the secondary atmosphere is a strong oxidizing atmosphere formed by mixing oxygen, carbon dioxide and nitrogen, the oxygen concentration is 6 vol.%, the carbon dioxide concentration is 2 vol.%, and the gas flow rate is 0.4 m/s; the product can be separated and collected in a two-section area, the recovery rate of tin is 97.6 percent, the purity of the nano tin dioxide product is 96.5 percent, and the specific surface area of the tin dioxide is 128m2/g。
Example 5
Taking a metal mixture obtained by a mechanical crushing and separating method of tin-containing electronic waste as a raw material (the tin content is 7.6 percent, the organic matter content is 0.8 percent), adding a composite additive (the composite additive is a mixture of tin dioxide, inert alumina and silicon dioxide, and the ratio of the composite additive to the silicon dioxide is 1:30:40) according to the mass ratio of 6 percent of the materials, uniformly mixing the mixed materials, and placing the mixed materials into a two-section type controlled atmosphere roasting furnace for controlled atmosphere roasting; the material is placed in a first-stage roasting region, and the first-stage atmosphere is dioxygenMixing carbon dioxide and nitrogen to form a weak oxidizing atmosphere, wherein the concentration of the carbon dioxide is 4 vol.%, the roasting temperature is 950 ℃, and the gas flow rate is 0.3 m/s; the volatilized intermediate product enters a secondary roasting area along with airflow, the roasting temperature is 550 ℃, the secondary atmosphere is a mixed strong oxidizing atmosphere of oxygen, carbon dioxide and nitrogen, the oxygen concentration is 8 vol.%, the carbon dioxide concentration is 1 vol.%, and the gas flow rate is 0.5 m/s; the product can be separated and collected in a two-section area, the recovery rate of tin is 94.3 percent, the purity of the nano tin dioxide product is 95.8 percent, and the specific surface area of the tin dioxide is 143m2/g。

Claims (7)

1. A method for synchronously preparing nano tin dioxide by selectively separating tin from electronic waste is characterized by comprising the following steps: uniformly mixing tin-containing electronic waste with an additive, placing the mixture in a weak oxidizing atmosphere to perform oxidizing roasting at 825-950 ℃, and placing a roasting volatile matter in a strong oxidizing atmosphere to perform oxidizing roasting at 500-700 ℃ to obtain nano tin dioxide powder; the additive is a mixture of tin dioxide, inert alumina and silicon dioxide.
2. The method for synchronously preparing nano tin dioxide by selectively separating tin from electronic waste according to claim 1, which is characterized in that: the tin-containing electronic waste is pretreated by a vacuum pyrolysis method or a mechanical crushing and separating method, the mass percent of tin is higher than 7.0%, and the mass percent of organic matters is lower than 0.5%.
3. The method for synchronously preparing nano tin dioxide by selectively separating tin from electronic waste according to claim 1, which is characterized in that: the mass of the additive accounts for 5.0-10.0% of the total mass of the tin-containing electronic waste and the additive.
4. The method for selectively separating and synchronously preparing nano tin dioxide in electronic waste according to claim 3, characterized by comprising the following steps: the additive is composed of tin dioxide, inert alumina and silicon dioxide according to a mass ratio of 1 (25-40) to (30-50).
5. The method for synchronously preparing nano tin dioxide by selectively separating tin from electronic waste according to claim 1, which is characterized in that: in the process of oxidizing roasting in a weak oxidizing atmosphere, the weak oxidizing atmosphere is controlled to be a mixed atmosphere of carbon dioxide and nitrogen, wherein the volume percentage concentration of the carbon dioxide is 2-5%, and the gas flow rate is 0.1-0.3 m/s.
6. The method for selectively separating and synchronously preparing nano tin dioxide in electronic waste according to claim 5, characterized in that: the oxidizing and roasting time is 60-120 min.
7. The method for synchronously preparing nano tin dioxide by selectively separating tin from electronic waste according to claim 1, which is characterized in that: in the process of oxidizing and roasting in a strong oxidizing atmosphere, the strong oxidizing atmosphere is controlled to be a mixed atmosphere of oxygen, carbon dioxide and nitrogen, wherein the volume percentage concentrations of the oxygen and the carbon dioxide are respectively 5-10 vol.% and 1-2 vol.%, and the gas flow rate is 0.2-0.5 m/s.
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CN102041474A (en) * 2010-12-20 2011-05-04 昆明理工大学 Preparation method for nano precious metal particle modified tin dioxide gas sensitive material
CN104152718A (en) * 2014-07-21 2014-11-19 中南大学 Method for synchronously separating tin and iron from tin-containing iron tailings

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1332726A (en) * 1971-02-12 1973-10-03 Proesa Sa Method for volatilizing tin
CN86101938A (en) * 1986-03-21 1987-05-20 个旧市化工研究所 The medium tin ore liquid phase oxidation is produced tindioxide
CN1530325A (en) * 2003-03-10 2004-09-22 中南大学 Method for preparing stannic anhydride nanometer crystal with solid phase reaction
CN102041474A (en) * 2010-12-20 2011-05-04 昆明理工大学 Preparation method for nano precious metal particle modified tin dioxide gas sensitive material
CN104152718A (en) * 2014-07-21 2014-11-19 中南大学 Method for synchronously separating tin and iron from tin-containing iron tailings

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中南矿冶学院有色重金属冶炼教研组: "《有色重金属冶金学下》", 30 September 1959, 冶金工业出版社 *
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