CN107308918A - A kind of preparation method of rich nitride polyporous material and its in retrieving circuit board noble metal application - Google Patents

Abstract

The invention relates to a preparation method of a nitrogen-rich porous material and its application in recycling precious metals in circuit boards. Using ethylene glycol as a solvent, adding melamine and p-benzoquinone, heating and polycondensing, and finally adding xylene for dehydration to obtain porous material MOPs -1. The invention provides a high-efficiency precious metal adsorption material MOPs-1, which uses thiourea leaching solution as waste circuit board treatment liquid, studies the function of porous materials, can efficiently adsorb precious metals in thiourea solution, and reuses thiourea solution to achieve electronic waste Recycling of materials, recycling precious metals in electronic waste, and recycling plastics, protecting the environment, and generating economic and social benefits.

Description

A preparation method of nitrogen-rich porous material and its application in recycling circuit boards of precious metals application

technical field

The invention relates to the field of novel porous materials, in particular to a preparation method of a nitrogen-rich porous material and its application in recycling circuit boards of precious metals.

Background technique

In 2016, the world produced up to 50 million tons of waste electrical appliances. According to the United Nations Environment Program report, China is the second largest producer of e-waste, with more than 2.3 million tons of e-waste per year, second only to the 3 million tons of the United States. About 350 million tons of e-waste flows into China through various channels around the world every year. If these electronic wastes are not treated, they will not only have a serious impact on the environment, but also cause a serious waste of resources. According to statistics, an average of 1 ton of ordinary electronic waste contains 490kg of metal, 4kg of wires, 12kg of circuit boards, etc. If it is not recycled, it will cause a huge waste of resources. Therefore, with the increasing impact of e-waste on the ecological environment and the huge economic value of e-waste itself, the resource recovery of e-waste is becoming a global issue.

Compared with the recycling of plastics or other components, the recycling of metal resources has obvious advantages in terms of technology and economy. Due to their excellent electrical conductivity and corrosion resistance, precious metals are used in electronic products, accounting for the vast majority of the value of e-waste, and are the main economic value of e-waste recycling. Using effective methods to recycle electronic waste such as computers and mobile phones can not only relieve environmental pressure, but also recycle precious metals such as Ag, Au, and Cu, alleviating the pressure of the world's increasingly depleted resources.

Research status of precious metal recovery from electronic waste: Since the 1980s, the supply of precious metals in the form of secondary resources in Western countries has increased year by year. In 1998 alone, the supply of gold in the form of secondary resources was as high as 1,089 tons, about 43% of. It can be seen that the recovery of precious metals has gradually attracted people's attention. At present, the technologies for recycling precious metals mainly include: pyrometallurgy technology, hydrometallurgy technology, and biometallurgy technology.

Pyrometallurgical technology. Pyrometallurgical technology generally includes roasting, electric arc furnace or blast furnace melting, high temperature gas phase reaction, etc. The electronic waste is smelted at high temperature to separate the non-metal from the metal, and the precious metal is enriched in the metal phase or matte to separate from other metals, and then the precious metal is obtained by electrolytic refining or pyro-refining.

The technology of pyrometallurgical treatment of electronic waste also has some defects. The main ones are: ①Electronic waste contains chlorofluorocarbons, bromine flame retardants and organic substances, which are easy to generate toxic gases such as dioxins under oxidative conditions, so strict and efficient procedures must be carried out. Otherwise, it will cause serious secondary pollution; ②Precious metals and copper can be recovered at a relatively high recovery rate, but aluminum, iron, tin and other metals are oxidized and enter the slag, making it difficult to recycle; ③ Ceramics and glass fibers in electronic waste also enter the slag, which greatly increases the amount of slag produced during smelting, and also increases the entrainment loss of precious metals and other metals.

Hydrometallurgical technology. Compared with pyrometallurgical technology for recycling e-waste, hydrometallurgical technology is more complicated and the process is more diversified. Hydrometallurgy technology generally includes two steps: leaching with acidic or alkaline solvents, and then separation and removal of impurities from the leachate. In addition, in the industrial production of wet recycling of electronic waste, there are generally pretreatments such as mechanical crushing. When the hydrometallurgical process is used to recover precious metals in electronic waste, the solvents usually used in the leaching process mainly include cyanide, halide, thiourea, thiosulfate, etc., and then extract the precious metals from the leachate through various methods. precious metals. At present, the common extraction methods are: solvent extraction, ion exchange, solid phase extraction-adsorption and so on.

Solvent extraction method is widely used because of its good separation effect, large production capacity, convenient rapid and continuous operation, small storage capacity in the process, relatively safe, and easy to realize automatic control. However, the extraction method needs to be developed faster. It depends on the successful development and rational use of efficient, easy-to-obtain, low-cost, and less-loss extractants.

The ion exchange method is widely used because of its simple synthesis method, stable performance, large exchange capacity, and reusability. However, the separation selectivity of ions with the same charge and similar chemical and physical properties is not good, and the resin with strong adsorption capacity is difficult to leaching and regenerate. Therefore, it is necessary to further develop and modify the resin, optimize and improve the separation and washing process, so as to promote the development of ion exchange separation and purification of precious metals.

Compared with the traditional liquid-liquid extraction technique, the solid phase extraction method has the following advantages: (1) the operation steps are simple, the analysis speed is fast, and the pretreatment time is shortened; (2) the organic solvent consumption is small, which reduces the experimental cost , while reducing environmental pollution. As a new type of sample pretreatment technology, solid phase extraction has become the most commonly used separation and enrichment method. Therefore, it has developed rapidly in recent years and is widely used in many fields such as environment, medicine, food, life, etc., especially It has extensive research significance in the field of adsorption of heavy metals and noble metal ions.

Biometallurgy. Biotechnology has been successfully used to extract precious metals and copper from ores. Compared with the traditional metallurgical process, the biosorption process has many advantages, such as simple process, low cost, convenient operation, less chemical and biological solid by-products, and less toxicity of wastewater. The main reason is that the leaching time is long, and the effect on raw materials with high metal content is not obvious.

Domestic research results. The method of leaching gold and silver from ore with acidic thiourea solution was proposed by former Soviet scholars in 1941. Extensive research has been carried out internationally on the theory and technology of thiourea gold extraction. After 1960, some metallurgists have conducted many theoretical and applied researches on it, and established small pilot plants. In the 1980s, thiourea gold immersion attracted the attention of individual developed countries. In the past 30 years, the former Soviet Union, South Africa and other countries have done a lot of experimental research on gold extraction by thiourea method. In recent years, our country has also carried out many beneficial explorations in the experimental research of gold extraction by thiourea method, and made great progress. On the basis of small-scale experiments, industrial experiments with a scale of 2 tons per day have been carried out in Yuerya and Zhangjiakou gold mines; the thiourea gold extraction workshop with a scale of 10 tons per day in Longshui Gold Mine has been put into production.

In the past ten years, domestic studies have been carried out on acidic and alkaline thiourea gold leaching using thiourea as a complexing agent, ferric iron as a catalyst, and hydrogen peroxide as an oxidant (or thiourea as a complexing agent and air as an oxidant). Researchers at Donghua University have also achieved good results using thiocyanate as a complexing agent and manganese dioxide as an oxidant, with a gold leaching rate of 96% to 99%.

However, how to apply the treatment liquid is a difficult problem in the treatment process of waste electrical appliances. If a material is invented that can absorb precious metals in the treatment solution, the treatment solution can be reused, which will greatly save costs, reduce waste water discharge, and generate economic and environmental benefits. The invention provides a high-efficiency precious metal adsorption material, uses thiourea leaching solution as waste circuit board treatment solution, and studies the function of the porous material.

In short, the synthesis of highly efficient porous materials, the adsorption of noble metal ions, the reuse of waste metal treatment fluids, the recycling of precious metals and plastics from electronic waste, environmental protection, and economic and social benefits.

Contents of the invention

The purpose of the invention is to use a convenient method to synthesize a nitrogen-rich porous material MOPs-1, use it to absorb precious metal ions, simplify the process flow, use waste metal treatment liquid many times, reduce the cost of precious metal recovery, and realize turning waste into treasure and reducing pollution The discharge target meets the requirements of environmental protection and green environment, and it can be expected that this material will be widely used in industrial production in the future.

For realizing above-mentioned purpose of the invention, the technical scheme that the present invention provides is:

A nitrogen-rich porous material, the preparation method of which comprises the following steps: using ethylene glycol as a solvent, adding melamine and p-benzoquinone, heating and polycondensing, and finally adding xylene for dehydration to obtain the porous material MOPs-1.

Further, the molar ratio of melamine to p-benzoquinone is 3:(1.9-2.2); when the molar ratio is less than 3:1.9 or greater than 3:2.2, the yield is obviously reduced, and the physical properties of the material are also reduced.

Further, the heating polycondensation time is 5-8 hours, and if the time is less than 5 hours, the reaction yield will decrease, and if the yield is more than 8 hours, the yield will not be significantly increased.

Further, the heating temperature is 160-198°C. When the temperature is lower than 160°C, the reaction time becomes longer, and the boiling point of ethylene glycol is 198°C; finally, xylene is added for dehydration for 3-5 hours. If the time is less than 3 hours, the polycondensation is incomplete, resulting in The rate is low, greater than 5 hours, no significant improvement.

Further, the dehydration temperature is 136-140°C, the boiling point of xylene.

The present invention also discloses the application of the above-mentioned nitrogen-rich porous material in the recovery of circuit board precious metals.

Preferably, the mass ratio of the adsorption material to the noble metal is 12-(20:1).

The optimal ratio is obtained through an adsorption column test: the porous material is loaded into the adsorption column, the solution containing the noble metal is added to the adsorption column, and the adsorption column adsorbs the noble metal ions. Wash the adsorption column with 1% dilute hydrochloric acid aqueous solution, and analyze the precious metal.

When the experimental ratio is less than 12:1, the adsorption is not complete; when the ratio is greater than 20:1, the remaining precious metal concentration does not decrease significantly. Desorption endpoints were determined using atomic absorption spectroscopy.

Beneficial effect:

The recovery of precious metals from waste electronic devices can reduce pollution, provide valuable raw materials, and protect the environment. At present, the technologies for recycling precious metals mainly include: pyrometallurgy technology, hydrometallurgy technology, and biometallurgy technology. Hydrometallurgy technology has good application prospects due to the recovery of metals and plastics, but the use of organic solvents or chemically corrosive aqua regia brings environmental pollution. In the past ten years, the use of thiourea or thiocyanate as a complexing agent in China has made great progress, but how to save thiourea or ammonium thiocyanate solution and reduce sewage discharge is the key issue for the industrialization of this method. If a material is invented that can absorb precious metals in the treatment solution, the treatment solution can be reused, which will greatly save costs, reduce waste water discharge, and generate economic and environmental benefits.

The invention provides a high-efficiency precious metal adsorption material MOPs-1, which uses thiourea leaching solution as waste circuit board treatment liquid to study the function of porous materials, and can efficiently adsorb precious metals in thiourea solution, so that thiourea solution can be reused, so as to achieve electronic waste Recycling of materials, recycling precious metals in electronic waste, and recycling plastics, protecting the environment, and generating economic and social benefits.

Description of drawings

Figure 1: A schematic diagram of the preparation route and adsorption of precious metals of the material MOPs-1 involved in the present invention.

Figure 2: Infrared spectra of MOPs-1, p-benzoquinone (A) and melamine (B).

detailed description

The present invention will be further described below in conjunction with specific examples.

A high-efficiency precious metal adsorption material MOPs-1 uses thiourea leaching solution as waste circuit board treatment liquid to recover precious metals in electronic waste. The determination of metal and non-metal components in waste electronic circuit boards is shown in Table 1 below:

Table 1

The synthesis (embodiment 1～9) of material of the present invention and the property experiment (embodiment 10～12) of material see following embodiment: the synthesis of material:

Example 1

In 1L of ethylene glycol, add 0.20mol of melamine and 0.30mol of p-benzoquinone, heat, stir, keep the temperature stable at 180°C for 5 hours, add 300mL of xylene, install a water separator, and set the temperature at 136-140°C for 5 hours The toluene was refluxed to take away the water, polycondensed for 4 hours, stopped stirring, naturally cooled to room temperature, filtered to obtain a brown precipitate, washed three times with 100 mL of ethanol, and dried in vacuum at 80°C to obtain 40.5 g of a brown blocky solid with a yield of 86.5%.

Example 2

In 1L of ethylene glycol, add 0.19mol of melamine and 0.30mol of p-benzoquinone, heat and stir, keep the temperature stable at 180°C for 5 hours, add 300mL of xylene, install a water separator, and set the temperature at 136-140°C Toluene was refluxed to take away water, polycondensed for 4 hours, stopped stirring, naturally cooled to room temperature, filtered to obtain a brown precipitate, washed three times with 100 mL of ethanol, and dried under vacuum at 80°C to obtain 35.6 g of a brown solid with a yield of 80.1%.

Example 3

In 1L of ethylene glycol, add 0.22mol of melamine and 0.30mol of p-benzoquinone, heat, stir, keep the temperature stable at 180°C for 5 hours, add 300mL of xylene, install a water separator, and set the temperature at 136-140°C Toluene was refluxed to take away water, polycondensed for 4 hours, stopped stirring, naturally cooled to room temperature, filtered to obtain a brown precipitate, washed three times with 100 mL of ethanol, and dried in vacuum at 80°C to obtain 40.2 g of a brown solid with a yield of 85.9%.

It can be seen from Examples 1-3 that when the molar ratio of melamine to p-benzoquinone is 1.9-2.2:3, the reaction yield is higher. According to the molar ratio of melamine and p-benzoquinone being 2:3, it will be further elaborated in the examples.

Example 4

In 1L of ethylene glycol, add 0.20mol of melamine and 0.30mol of p-benzoquinone, heat, stir, keep the temperature stable at 160°C for 5 hours, add 300mL of xylene, install a water separator, and set the temperature at 136-140°C Toluene was refluxed to take away water, polycondensed for 4 hours, stopped stirring, naturally cooled to room temperature, filtered to obtain a brown precipitate, washed three times with 100 mL of ethanol, and dried in vacuum at 80°C to obtain 40.3 g of a brown solid with a yield of 86.1%.

Example 5

In 1L of ethylene glycol, add 0.20mol of melamine and 0.30mol of p-benzoquinone, heat, stir, keep the temperature stable at 198°C for 5 hours, add 300mL of xylene, install a water separator, and set the temperature at 136-140°C Toluene was refluxed to take away water, polycondensed for 4 hours, stopped stirring, naturally cooled to room temperature, filtered to obtain a brown precipitate, washed three times with 100 mL of ethanol, and dried under vacuum at 80°C to obtain 40.5 g of a brown solid with a yield of 86.5%.

It can be known from Examples 1, 4, and 5 that when the reaction temperature is 160-198° C., the reaction yield is stable. It will be further illustrated in the examples according to 180°C.

Example 6

In 1L of ethylene glycol, add 0.20mol of melamine and 0.30mol of p-benzoquinone, heat, stir, keep the temperature stable at 180°C for 8 hours, add 300mL of xylene, install a water separator, and set the temperature at 136-140°C The toluene was refluxed to take away the moisture, polycondensed for 4 hours, stopped stirring, naturally cooled to room temperature, filtered to obtain a brown precipitate, washed three times with 100 mL of ethanol, and dried under vacuum at 80°C to obtain 40.3 g of a brown solid with a yield of 86.1%.

Example 7

In 1L of ethylene glycol, add 0.20mol of melamine and 0.30mol of p-benzoquinone, heat and stir, keep the temperature stable at 180°C for 6.5 hours, add 300mL of xylene, install a water separator, and set the temperature at 136-140°C for 6.5 hours Toluene was refluxed to take away water, polycondensed for 4 hours, stopped stirring, naturally cooled to room temperature, filtered to obtain a brown precipitate, washed three times with 100 mL of ethanol, and dried under vacuum at 80°C to obtain 40.5 g of a brown solid with a yield of 86.5%.

As can be seen from Examples 1, 6, and 7, when the reaction time was 5-8 hours, the reaction yield was stable. This will be further illustrated in the Examples in terms of 5 hours.

Example 8

In 1L of ethylene glycol, add 0.20mol of melamine and 0.30mol of p-benzoquinone, heat, stir, keep the temperature stable at 180°C for 5 hours, add 300mL of xylene, install a water separator, and set the temperature at 136-140°C for 5 hours Toluene was refluxed to take away water, polycondensed for 3 hours, stopped stirring, naturally cooled to room temperature, filtered to obtain a brown precipitate, washed three times with 100 mL of ethanol, and dried in vacuum at 80°C to obtain 40.2 g of a brown solid with a yield of 85.9%.

Example 9

In 1L of ethylene glycol, add 0.20mol of melamine and 0.30mol of p-benzoquinone, heat, stir, keep the temperature stable at 180°C for 5 hours, add 300mL of xylene, install a water separator, and set the temperature at 136-140°C Toluene was refluxed to take away water, polycondensed for 5 hours, stopped stirring, naturally cooled to room temperature, filtered to obtain a brown precipitate, washed three times with 100 mL of ethanol, and dried under vacuum at 80°C to obtain 40.1 g of a brown solid with a yield of 85.7%.

Experiments on the properties of materials:

Example 10

Take 2 g of the above-mentioned porous material, add it to 3 L of aqueous solution containing 0.051 wt % of gold ions, 20 wt % of thiourea, and pH=2.5, stir at room temperature for 30 min, filter, and the remaining gold ion concentration is 16 ppm as determined by atomic absorption spectrometry, and the adsorption rate is 96.8%.

The gold-absorbing material is loaded into an adsorption column, and eluted with 1% hydrochloric acid solution. When the gold ion concentration in the effluent hydrochloric acid solution is determined by atomic absorption spectroscopy, the elution is stopped when it is less than 3 ppm, and 25 mL of hydrochloric acid is removed.

Example 11

Take 2 g of the above-mentioned porous material, add it into 300 mL of an aqueous solution containing 0.89 wt % of silver ions, 20 wt % of thiourea, and pH=2.5, stir at room temperature for 30 min, filter, and the concentration of remaining silver ions determined by atomic absorption spectroscopy is 156 ppm, and the adsorption rate is 98.2%.

The silver-absorbing material is packed into an adsorption column, and eluted with 1% nitric acid solution. When the concentration of silver ions in the effluent nitric acid solution is measured by atomic absorption spectrometry, the elution is stopped when the concentration of silver ions is less than 3 ppm, and 20 mL of nitric acid is removed.

Example 12

Get above-mentioned porous material 2g, add and contain 300mL and contain silver ion 0.89wt%, gold ion 215ppm, thiourea 20wt%, in the aqueous solution of pH=2.5, stir at room temperature 30min, filter, atomic absorption spectrometry determines remaining gold, silver ion concentration is respectively 10ppm, 152ppm, the adsorption rates are 95.3%, 98.3%, respectively.

Put the material adsorbing precious metals into the adsorption column, first elute with 20mL of 1% nitric acid solution, then with 10mL of 1% hydrochloric acid solution, and stop elution when the concentration of outflowing noble metal ions is less than 3ppm as determined by atomic absorption spectrometry.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention in any form. Any skilled person who is familiar with the profession, without departing from the scope of the technical solutions of the present invention, according to the technical essence of the present invention, Any simple modifications, equivalent replacements and improvements made in the above embodiments still fall within the protection scope of the technical solution of the present invention.

Claims (8)

1. a kind of rich nitride polyporous material, it is characterised in that：Its preparation methods steps are：Using ethylene glycol as solvent, melamine is added Amine and 1,4-benzoquinone, heat polycondensation, are eventually adding dimethylbenzene dehydration, obtain porous material MOPs-1.

2. rich nitride polyporous material according to claim 1, it is characterised in that：The mol ratio of the melamine and 1,4-benzoquinone For 3:(1.9~2.2).

3. rich nitride polyporous material according to claim 1, it is characterised in that：It is 5~8 hours to heat the polycondensation time.

4. rich nitride polyporous material according to claim 1, it is characterised in that：Heating-up temperature is 160~198 DEG C.

5. rich nitride polyporous material according to claim 1, it is characterised in that：Dimethylbenzene is eventually adding to be dehydrated 3~5 hours.

6. rich nitride polyporous material according to claim 1, it is characterised in that：Dehydration temperaturre is xylene boiling point 136~140 ℃。

7. application of the rich nitride polyporous material in the recovery of circuit board noble metal described in claim 1.

8. application of the rich nitride polyporous material according to claim 7 in the recovery of circuit board noble metal, it is characterised in that：Inhale Enclosure material is 12~(20 with noble metal mass ratio：1).