KR101308972B1 - Adsorbent having selective adsorption and preparing method of the same and recovery method of indium from wasted portabel device using the adsorbent - Google Patents

Abstract

In the present invention, a phenol group (-C ₆ H ₅ OH) of the sawdust molecule is substituted by a phosphate group (PO ₄ ^3- ), the step of immersing sawdust in an aqueous solution of phosphate phosphate and filtering to form a phosphate-impregnated sawdust as a solid And a step of forming the phosphate-substituted sawdust by heat-treating the phosphate-impregnated sawdust and washing and drying the phosphate-substituted sawdust, and a method for producing the indium selective adsorbent.
According to the present invention, various impurities other than indium can be removed in a short time from an indium-containing material containing various impurities such as factory wastewater, and indium can be selectively recovered, thereby easily obtaining high indium.

Description

Indium selective adsorbent, preparation method thereof, and method for recovering indium from waste portable equipment using the adsorbent {Adsorbent having selective adsorption and preparing method of the same and recovery method of indium from wasted portabel device using the adsorbent}

The present invention relates to an adsorbent for selectively adsorbing only indium which is a valuable metal, a method for preparing the same, and a method for recovering indium from a waste portable device using the adsorbent, and more particularly, a phenolic hydroxide group (-C ₆₎ of a sawdust molecule. H ₅ OH) is substituted by phosphoric acid group (PO ₄ ^3- ), and removes various impurities except indium in a short time from indium-containing materials including various impurities such as liquid crystal and factory wastewater The present invention relates to an indium selective adsorbent capable of easily obtaining high purity indium by recovering the same, a method for preparing the same, and a method for recovering indium from waste portable equipment using the indium selective adsorbent.

Most of indium is indium tin oxide (ITO) or indium zinc oxide (IZO), which is used for transparent conductive films, accounts for about 70% of the entire indium market, and includes regenerated materials. Nearly 80%

On the other hand, in the flat panel display (FPD) industry in which a transparent conductive film is used, there is a great increase in the demand for thin-type large-sized televisions as well as computer liquid-crystal display devices. In addition, as the European Union (EU) strengthens lead regulations, the demand for lead-free solder consisting of low melting point alloys including indium is expected to increase and demand will increase.

In accordance with such market trends, indium prices are on the rise, and at the same time, there is expected to be a battle to secure raw materials.

Due to this background, an atmosphere of regenerating indium is spreading, and regeneration of indium is not merely an environmental technology, but a material recovery technology having important economic feasibility.

In the case of indium, moreover, there is no major ore that can be extracted and industrially produced by recovering by-products of zinc smelting or by-products of lead smelting, particularly indium concentrated in soot. That is, the raw material which can collect indium contains many metal impurities, such as zinc, iron, copper, aluminum, gallium, arsenic, or cadmium, and there are many kinds of impurities contained in trace amount besides these metal components.

Therefore, a complex process is required to remove the metal impurities and recover high purity indium. In general, the recovery process of the indium is to adjust the pH to precipitate the indium into the hydroxide, to add the sulfiding agent to precipitate the impurities into the emulsion, to add the metal aluminum, zinc, cadmium or zinc-cadmium alloy, etc. It is performed by the combination of chemical refining methods and electrolytic refining methods, such as a method of performing precipitation precipitation, a method of recovering indium by solvent extraction, and a method of recovering indium by ion exchange.

A method of adjusting the pH to precipitate impurities into hydroxide is disclosed in Japanese Unexamined Patent Publication No. 2007-056367 or Japanese Unexamined Patent Publication No. 2007-131953. It is mainly to adjust the pH using the difference in the pH range where each metal ion produces a hydroxide to precipitate impurities into the hydroxide. For example, the separation of zinc, aluminum and indium is controlled to pH 12 or higher to dissolve zinc, aluminum, and precipitate and recover indium as a hydroxide. However, the hydroxide of indium produced by this method is extremely poor in filtration, so that the filtration facilities are large, the working time is delayed, and in particular, it is difficult to separate between impurities such as iron, copper, arsenic or cadmium and indium.

A method of precipitating impurities into an emulsion by adding a sulfiding agent is disclosed in Korean Patent Laid-Open Publication No. 2007-0101368 or Japanese Patent Laid-Open Publication No. 2007-131953. The difference in the solubility of the metal emulsion is mainly used, and the sulfiding agent is added to precipitate impurities into the emulsion. However, as described above, since the raw material capable of recovering indium contains many metal impurities, low-purity emulsions are generated in large quantities. Therefore, such emulsions generally have poor filterability, and in the case of leaching the obtained indium emulsion, there is a problem in that indium sulfate alone cannot be completely leached.

A method of substituting and depositing indium by adding metal aluminum, zinc, cadmium or zinc-cadmium alloy is disclosed in Korean Patent Laid-Open No. 2008-0031661, Japanese Patent Laid-Open No. 2008-207976 and Japanese Patent Laid-Open No. 2007-009274 It is. As described above, the method of substituting and depositing indium by adding metal aluminum, zinc, cadmium or zinc-cadmium alloy, etc., has a problem in that separation of the noble metal impurity and indium is impossible when the noble metal impurity is further included.

The method of recovering indium by the solvent extraction and the method of recovering indium by the ion exchange method have a problem in that the pretreatment burden increases according to the type of impurities, resulting in high operating cost.

In addition, since the separation of metal impurities is insufficient even through the chemical purification method, the electrolytic smelting method combined with the above chemical purification method also has a simple electrolytic sampling method in which the target metal is leached in an aqueous solution and electrolyzed to obtain a high purity metal on the negative electrode. It is not possible to employ a complicated electrolytic refining method using a target metal as an anode and a high purity metal as a cathode.

Any of the above methods have their drawbacks, and even if the above methods are combined, the process is complicated and complicated to recover high purity indium. Therefore, there is an urgent need for an economical and convenient means or method for producing high purity indium, preferably an indium selective adsorbent capable of removing various impurities other than indium in a short time and selectively recovering indium from valuable metals.

Korean Patent Publication No. 2007-0101368 Korean Laid-Open Patent No. 2008-0031661 Japanese Laid-Open Patent No. 2007-009274 Japanese Laid-Open Patent No. 2007-056367 Japanese Laid-Open Patent No. 2007-131953 Japanese Laid-Open Patent No. 2008-207976

The problem to be solved by the present invention is to remove various impurities except indium in a short time from the indium-containing material containing various impurities, such as liquid crystal or factory wastewater of the waste portable device, and to selectively recover the indium, to facilitate high purity indium It is to provide an indium selective adsorbent, a method for preparing the same and a method for recovering indium from waste portable equipment using the adsorbent.

The present invention provides an indium selective adsorbent, characterized in that the phenol group (-C ₆ H ₅ OH) of the sawdust molecule is substituted with a phosphoric acid group (PO ₄ ^3- ).

Indium desorption agent used to desorb the indium adsorbed on the indium selective adsorbent is at least one indium desorbent selected from the group consisting of hydrochloric acid, ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA) Included.

In addition, the present invention is the step of immersing sawdust in aqueous solution of urea phosphate and filtering to form a phosphate impregnated sawdust which is a solid content, the phenol group (-C ₆ H ₅ OH) of the sawdust molecule by heat treatment of the phosphate impregnated sawdust is a phosphate group (PO forming a phosphoric acid group substituted by a substituted sawdust ₄ ^3-) and provides a method for producing an indium-selective adsorbent, comprising the phosphate group substituted washed with water and dried sawdust.

The aqueous solution of phosphate urea used in the step of forming the phosphate-impregnated sawdust may be made to include 40 to 60 parts by weight of water with respect to 50 parts by weight of phosphoric acid.

Heat treatment of the phosphate-impregnated sawdust in the step of forming the phosphate-substituted sawdust can be carried out at 80 ~ 120 ℃.

In the step of forming the phosphate-substituted sawdust, the heat treatment of the phosphate-impregnated sawdust can be carried out for 90 to 150 minutes.

In addition, the present invention is a step of recovering the liquid crystal in a waste portable device, dissolving the liquid crystal in an alkaline solution to recover the indium-containing residue, dissolving the indium-containing residue in an acid to form an indium solution, the indium Recovering the remaining waste liquid after reducing the indium ions of the solution to indium by a metal substitution reaction, the phenol group (-C ₆ H ₅ OH) of the sawdust molecule is converted into a phosphoric acid group (PO ₄ ^3- ) It is possible to provide a method for recovering indium from a waste portable device, the method including adsorbing with an indium selective adsorbent which is substituted and recovering the indium adsorbed on the indium selective adsorbent by an indium desorbent.

Adsorption of the indium ions is preferably performed by adjusting the waste liquid to pH 3.5.

According to the present invention, various impurities other than indium are removed from the indium-containing material containing various impurities such as liquid crystal and factory waste water of waste portable equipment in a short time, and indium is selectively recovered to obtain high purity indium easily. Provide an indium selective adsorbent to help.

In addition, the present invention has the effect of enabling the recycling of resources by using a sawdust as a waste as a heavy metal adsorbent.

1 is a SEM photograph of the indium selective adsorbent according to Example 1 of the present invention.
2 is an EDX spectral chart of the indium selective adsorbent according to Example 1 of the present invention.
3 is a SEM photograph of the indium selective adsorbent according to Example 2 of the present invention.
4 is an EDX spectral chart of the indium selective adsorbent according to Example 2 of the present invention.
5 is an SEM photograph of oak sawdust as a comparative example.
6 is an EDX spectrum chart of oak sawdust as a comparative example.
7 is a graph of adsorption rate of valuable metals according to pH of the indium selective adsorbent of Example 1. FIG.
8 is a graph of adsorption rate of valuable metals according to pH of the indium selective adsorbent of Example 2. FIG.
9 is a chart showing the selective removal rate and adsorption capacity change of indium ions according to the dosage of the indium selective adsorbent of Example 1;
FIG. 10 is a chart illustrating removal rate and pH change of indium ions over time of the indium selective adsorbent of Example 1. FIG.
11 is a graph of indium desorption efficiency of a desorption agent used for indium desorption of an indium selective adsorbent.
12 shows measurement results of metal extraction rates of indium-containing residues in Example 4. FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, it should be understood that the following embodiments are provided so that those skilled in the art will be able to fully understand the present invention, and that various modifications may be made without departing from the scope of the present invention. It is not. The indium selective adsorbent of the present invention will be described in detail with reference to Examples.

The recovery of valuable metals by the wet method generates a large amount of waste liquid, and the waste water contains a certain amount of valuable metals. If it is just released, economic losses are caused by the loss of valuable metals, and technology development is required to minimize them. Currently, there is a research to recover valuable metals from wastewater using commercial ion exchange resins, but the situation is insignificant. Therefore, there is a need to develop an economical adsorbent having excellent durability and excellent selectivity with respect to specific valuable metals.

Recently, research has been conducted to remove heavy metals using agricultural waste such as waste wool, peanut wastes, tree barks, waste cotton, etc. Is showing. When such agricultural waste is used as a heavy metal adsorbent, it is very inexpensive and has a great advantage of economic process.

The researchers of the present invention conducted a study of selectively adsorbing and recovering indium from a mixed solution of zinc and indium using sawdust having the highest selectivity to indium among various waste adsorbents.

In addition, in order to increase the selectivity of indium, the sawdust equipped with phenolic hydroxide group (-C ₆ H ₅ OH) was chemically modified by replacing with a phosphoric acid group (PO ₄ ^3- ), which is a conventional commercial ion exchange resin It is necessary to replace.

The main adsorption functions of sawdust, wood waste, are carboxyl group (-COOH) and phenolic hydroxide group (-C ₆ H ₅ OH). Among these, phenolic hydroxide group (-C ₆ H ₅ OH) has low adsorption capacity for metals. Known. Therefore, the researchers of the present invention are to chemically substitute a phenolic hydroxide group (-C ₆ H ₅ OH) having a low adsorption capacity for the metal to transform into a functional group having a high selectivity to indium.

Among various compounds, compounds having phosphonate and phosphonic acid are known to have high selectivity to indium.

Accordingly, the present invention phosphoric acid group (PO ₄ ^{3 -)} having a high selectivity with respect to the main suction function of the molecule due sawdust hydroxide phenol group (-C ₆ H ₅ OH) in the indium being substituted by a modified chemical structure, the optional indium It is to provide an indium selective adsorbent that can be recovered by adsorption.

Indium adsorbed on the indium selective adsorbent may include hydrochloric acid (HCl), nitric acid (HNO ₃ ), ethylene diaminetetraacetic acid (EDTA), nitrilo triacetic acid (NTA), sodium hydroxide (NaCl), and the like. It is detached by an indium desorbent used alone or in mixture of two or more thereof.

Hereinafter, the manufacturing method of the indium selective adsorbent of this invention is demonstrated in detail.

The method for producing an indium selective adsorbent of the present invention includes the steps of immersing sawdust in an aqueous solution of urea phosphate and filtering to form a solid phosphate impregnated sawdust.

Phosphoric acid (H ₃ PO _{4) was added to} sawdust to prepare an indium selective adsorbent whose chemical structure was modified by replacing phenolic hydroxide group (-C ₆ H ₅ OH), which is the main adsorption functional group of sawdust molecules, with phosphoric acid group (PO ₄ ^3- ). ) Should form phosphate-impregnated sawdust with uniform penetration.

Accordingly, phosphoric acid, water for controlling the concentration of the phosphoric acid as a main component, and in addition to promoting the substitution of the phenolic hydroxide group (-C ₆ H ₅ OH) of the sawdust molecule with a phosphoric acid group (PO ₄ ^3- ) A proper amount of urea (Urea) is mixed to form an aqueous solution of urea phosphate.

Specifically, the aqueous solution of urea phosphate used to form the phosphoric acid-impregnated sawdust is 40 to 60 parts by weight of water with respect to 50 parts by weight of phosphoric acid, and an appropriate amount of urea is mixed therein. If the amount of water mixed in 50 parts by weight of phosphoric acid to form an aqueous solution of urea phosphate is less than 40 parts by weight, the ion selectivity of the indium selective adsorbent prepared using the aqueous urea phosphate solution may be lowered, thereby forming an aqueous solution of urea phosphate. When the amount of water mixed with 50 parts by weight of phosphoric acid exceeds 60 parts by weight, the indium adsorption capacity of the indium selective adsorbent prepared using the aqueous urea phosphate solution may be lowered.

In a state in which the aqueous solution of urea phosphate and the sawdust of the composition as described above is maintained for a predetermined time so that phosphoric acid is sufficiently uniformly penetrated into the sawdust, the mixture of the aqueous solution of urea phosphate and sawdust is filtered and separated Obtained by recovering solid phosphate-impregnated sawdust.

In addition, in the method for producing an indium selective adsorbent of the present invention, the phosphate-impregnated sawdust is heat-treated to form a phosphate-substituted sawdust in which the phenolic hydroxide group (-C ₆ H ₅ OH) of the sawdust molecule is substituted with a phosphate group (PO ₄ ^3- ). Steps are included.

Phosphoric acid-impregnated sawdust formed by depositing phosphoric acid (H ₃ PO ₄ ) on sawdust as described above, and a phosphate group (PO ₄ ³⁾ having high selectivity to indium for the phenolic hydroxide group (-C ₆ H ₅ OH) of the sawdust molecule ^-) to form a phosphate group substituted sawdust which can selectively adsorb an indium by substitution with.

Specifically, phosphate-impregnated sawdust in which phosphoric acid (H ₃ PO ₄ ) is uniformly infiltrated into sawdust molecules is heat-treated at 80 to 120 ° C. for 90 to 150 minutes to form a phenol group (-C ₆ H ₅ OH) of the sawdust molecule. a phosphate group (PO ₄ ^{3 -)} a phosphoric acid group substituted with to form a substituted sawdust.

When the temperature of heat-treating the phosphate-impregnated sawdust to form a phosphate-substituted sawdust is less than 80 ℃, the phenolic hydroxide group (-C ₆ H ₅ OH) of the phosphate-impregnated sawdust molecule may not be properly substituted with a phosphate group (PO ₄ ^3- ) When the temperature for heat-treating the phosphate-impregnated sawdust exceeds 120 ° C., the phosphate-substituted sawdust deteriorates and the practicality is lowered. In addition, if the phosphate groups have time to heat treating the phosphate impregnated sawdust to form a substituted sawdust less than 90 minutes a phosphate group (PO ₄ ^{3 -)} for the phosphoric acid impregnated sawdust molecule and the degree of substitution of the can be reduced, the time of heat-treating the acid-impregnated sawdust If it exceeds 150 minutes, the substitution of the phosphate group (PO ₄ ^3- ) for the phosphate-impregnated sawdust molecule may not proceed any further.

In addition, the method for producing an indium selective adsorbent of the present invention includes washing and drying the phosphate-substituted sawdust.

Unreacted material, such as a state of a phosphate group by washing with water and filtering the substituted phosphoric acid is substituted by ^{sawdust-phosphate} sawdust impregnated is heat-treated hydroxide sawdust molecular phenol group (-C ₆ H ₅ OH) is a phosphate group (PO ₄ ³⁾ as described above After the removal, it is dried at room temperature to prepare an indium selective adsorbent.

Hereinafter, examples of the indium selective adsorbent according to the present invention will be described in more detail, and the present invention is not limited to the following examples.

≪ Example 1 >

1. Mix 50 g of oak sawdust with 500 ml of phosphoric acid (Sigma Aldrich, reagent, concentration 85% by weight), 22.4 g of urea (Sigma Aldrich, reagent), and 500 ml of distilled water and stir for 10 minutes. Thereby forming a mixture of sawdust and aqueous solution of urea phosphate. The mixture of the sawdust and the aqueous solution of urea phosphate was maintained for 24 hours and then filtered through a filter to obtain a solid phosphorus-impregnated sawdust.

2. The phosphate-impregnated sawdust was heat-treated at 100 ° C. for 120 minutes to form a phosphate-substituted sawdust in which the phenolic hydroxyl group (—C ₆ H ₅ OH) of the sawdust molecule was substituted with a phosphate group (PO ₄ ^3- ).

3. The phosphate-substituted sawdust was washed four times with distilled water, and then dried thoroughly at room temperature to prepare an indium selective adsorbent.

4. The prepared indium selective adsorbent was photographed with a scanning electron microscope (SEM) to observe the surface state, and the scanning electron micrograph is shown in FIG. 1. In addition, EDX spectrum analysis was performed on the indium selective adsorbent, and the results of the EDX spectrum analysis are shown in FIG. 2. In addition, the content of the functional group of the indium selective adsorbent was calculated based on the analysis result of the EDX spectrum analysis, and the calculated content of the functional group of the indium selective adsorbent is shown in Table 1 below.

division weight% volume% Carboxyl group 55.53 63.24 Phenolic hydroxide group 41.41 35.41 sign 3.05 1.35

<Example 2>

50 g of oak sawdust is mixed with an aqueous solution of urea phosphate consisting of 750 ml of phosphoric acid (Sigma Aldrich, reagent, concentration 85 wt%), 22.4 g of urea (Sigma Aldrich, reagent, reagent), and 250 ml of distilled water. A mixture of an aqueous solution of urea phosphate was formed. The mixture of the sawdust and urea phosphate aqueous solution was maintained for 24 hours and then filtered through a filter to obtain a phosphate-impregnated sawdust as a solid.

The prepared indium selective adsorbent was photographed with a scanning electron microscope (SEM) to observe the surface state, and the scanning electron microscope photograph is shown in FIG. 3. In addition, EDX spectrum analysis was performed on the indium selective adsorbent, and the EDX spectrum analysis results are shown in FIG. 4. In addition, the content of the functional group of the indium selective adsorbent was calculated based on the analysis result of the EDX spectrum analysis, and the content of the functional group of the indium selective adsorbent was shown in Table 2 below.

division weight% volume% Carboxyl group 55.52 64.96 Phenolic hydroxide group 34.98 30.73 sign 9.50 4.31

<Comparative Example>

The oak sawdust which was not subjected to any treatment was photographed with a scanning electron microscope (SEM) as a comparative example to observe the surface state, and the scanning electron microscope picture is shown in FIG. 5. In addition, EDX spectrum analysis was performed on the oak sawdust, and the EDX spectrum analysis results are shown in FIG. 6. In addition, the functional group content of oak sawdust was calculated based on the analysis result of the EDX spectrum analysis, and the content of the functional group of oak sawdust was shown in Table 3 below.

division weight% volume% Carboxyl group 56.67 63.53 Phenolic hydroxide group 43.33 36.47 sign - -

1, 3 and 5, which are SEM photographs of Examples 1 and 2 and Comparative Examples, were observed before the phenolic hydroxyl group (-C ₆ H ₅ OH) of the sawdust molecule was substituted with the phosphoric acid group (PO ₄ ^3- ). The surface condition of subsequent sawdust did not differ significantly. That is, when the substitution with the phosphate group (PO ₄ ^{3 −} ), which is a chemical reaction, does not significantly change the surface state of the sawdust, it is judged that there is no physical change of the sawdust.

However, as a result of investigating the content of phosphorus (P) using the spectral charts of Examples 1 and 2 and Comparative Examples 2, 4 and 6, the phosphorus content of the indium selective adsorbents of Examples 1 and 2 was increased. It was found that the phenolic hydroxyl group (-C ₆ H ₅ OH) of the sawdust molecule was substituted with the phosphoric acid group (PO ₄ ^3- ). The indium selective adsorbent of Example 1 had a phosphorus content of about 3.05% by weight, whereas the indium selective adsorbent of Example 2 had a phosphorus content of about 9.50% by weight, compared to the indium selective adsorbent of Example 1 (PO ₄ ^3- ). It is judged that the degree of substitution with is high.

&Lt; Test Example 1 >

Selective adsorption tests of the valuable metals on the indium selective adsorbents of Examples 1 and 2 were carried out.

Selective adsorption of valuable metals was carried out in batch form using 100 ml of valuable metal solution. The indium selective adsorbent and the valuable metal solution were mixed and stirred for 24 hours in a shaking incubator, and the mixture was fixed at 25 ° C. The pH of the mixture was adjusted using various concentrations of nitric acid (HNO ₃ ) and ammonium hydroxide (NH ₄ OH), and the valuable metal solution of the mixture reaching the adsorption equilibrium was separated from the indium selective adsorbent by a filter. The separated valuable metal filtrate was diluted with distilled water and then measured by using an automatic adsorption spectroscopy (AAS: Atomic Absorption Spectroscopy, model name Perkin Elmer Analyst 300, USA). All experiments were repeated three times, and the average value was given as a result. Removal efficiency (RE) and adsorption capacity (Q) of the valuable metal ions were calculated based on the following equation.

Removal rate of valuable metal ions RE = [(C _i -C _f ) / C _i ] × 100 (%)

Adsorption capacity of valuable metal ions Q = [(C _i × V _i )-(C _f × V _f )] ÷ (1000 × M)

[Q; Adsorption capacity of metal ions (mg / g),

C _i ; Initial concentration of metal ions (mg / l),

V _i ; Initial volume of metal solution (ml),

C _f ; Final concentration of metal ions (mg / l),

V _f ; Final volume of metal solution (ml).

M; Indium Selective Adsorbent Initial Loading Amount of Adsorbent (g)]

The calculated removal rates of the valuable metal ions are shown in FIGS. 7 and 8.

Referring to FIG. 7, in the case of the indium selective adsorbent of Example 1, as the pH was increased, the removal rate of indium was increased while the removal rate of zinc was rather decreased. In particular, when the pH was 3.5, the removal rate of indium was about 90%, and zinc was hardly removed. Increasing pH increases the removal rate of indium due to the competitive adsorption between indium ions (In ^{3 +} ) and hydrogen ions (H ⁺ ). That is, at low pH, the removal rate decreases because the amount of hydrogen ions (H ⁺ ) is relatively higher than that of the high pH, so that competitive adsorption to the same adsorption site with indium ions (In ^{3 +} ) is severe.

The high selectivity removal rate of the indium selective adsorbent of Example 1 is considered to be an effect of the phosphate group, which can be explained by the HSAB theory. The theory is that hard acid has strong binding to hard base, and soft acid has good binding to soft base. In the case of intermediate, it can be combined with hard base or soft base depending on the oxidation state of acid. Is there.

For indium-selective adsorbent of the present invention, a phosphoric acid group (PO ₄ ^{3 -)} substituted on Sawdust unique carboxyl group (-COOH) belongs to the family of the Hard base, indium ions (In ^{+ 3)} is Hard acid and zinc ions (Zn ²⁺ ) belongs to the Intermediate. Thus, indium ions (In ^{3 +} ) belonging to hard acid bind well with carboxyl group (-COOH) and phosphoric acid group (PO4 ^3- ), It does not bind well with zinc ions (Zn ^{2 +} ).

8, the indium selective adsorbent of Example 2 had an indium removal rate of almost 97%, but did not meet the purpose of the present invention by removing about 3% of zinc.

Therefore, in view of the above experimental results, when adsorbing the mixture of indium and zinc at pH 3.5 with the indium selective adsorbent of Example 1, it is possible to remove 90% or more of indium alone without almost adsorbing zinc. The optimum condition was found.

&Lt; Test Example 2 &

The characteristics of selective removal rate and adsorption capacity of indium ions were measured while varying the amount of the indium selective adsorbent of Example 1, and the results are shown in FIG. 9.

Referring to FIG. 9, it was found that the adsorption capacity of indium ions was decreased while the amount of indium selective adsorbent was increased, but the removal rate of indium ions was increased.

In general, as the amount of adsorbent increases, the adsorption capacity tends to decrease. This is because as the amount of adsorbent increases, the adsorption sites unsaturated with heavy metals increase.

When 1.0 g of indium selective adsorbent was added to the valuable metal solution, about 87% of indium ions could be selectively removed from the valuable metal solution, and the adsorption capacity of indium ion per 1.0 g of indium selective adsorbent was about 1.1. Mg / g. As described above, zinc ions were hardly adsorbed in the indium selective adsorbent in which the indium ions were adsorbed.

From this result, it can be seen that the selectivity of the indium selective adsorbent of the present invention to the indium ion is very excellent, in particular, considering that the sawdust used as the main raw material of the indium selective adsorbent is waste, indicating that the indium selective adsorbent is a very economical adsorbent. As a result, it will be possible to replace the ion exchange resin which is currently used commercially.

<Test Example 3>

While indium ions are adsorbed with the indium selective adsorbent of Example 1 in a valuable metal solution having an initial concentration of 7.25 mg / l, the concentration of indium ions in the valuable metal solution with time changes, while the valuable metal solution The change in pH was also measured, and the results are shown in FIG. 10.

Referring to FIG. 10, it was found that the concentration and pH of indium ions were simultaneously decreased with time.

In terms of the change of indium ion concentration, no significant change occurred after about 120 minutes, which means that the adsorption process of In ions by phosphorylated sawdust proceeds almost within about 120 minutes.

In addition, the change of pH according to the change of time is the hydrogen ions of the carboxyl group (-COOH) (H ⁺ ) and the phosphoric acid group (PO 4 ^3- ) generated during the phosphorylation substitution of sawdust, which is considered to be the main adsorption function of the indium selective adsorbent. The ions (H ⁺ ) are dissociated, and the metal ions and the hydrogen ions (H ⁺ ) are ion exchanged to dissolve in the valuable metal solution to decrease the pH.

<Test Example 4>

After the mixture of the valuable metal solution and the indium selective adsorbent of Example 1 reached the adsorption equilibrium, the supernatant valuable metal solution was removed by centrifugation to obtain an indium selective adsorbent. A desorption experiment of an indium desorbent with respect to indium adsorbed to the obtained indium selective adsorbent was carried out, and the results are shown in FIG. 11.

Specifically, hydrochloric acid (HCl), nitric acid (HNO ₃ ), ethylenediaminetetraacetic acid (EDTA: ethylene diaminetetraacetic acid), nitriloacetic acid (NTA: nitrilo triacetic acid), and sodium hydroxide (NaCl) were used. In order to select the optimal indium desorbent, the concentration of all the indium desorbents was the same at 0.1 M and the S / L ratio was fixed at 1.0. The concentration of the indium desorbent and the desorption rate of indium over time were measured.

Indium removal rate is computed by following Formula.

Indium Desorption Efficiency =

Weight of metal contained in indium desorbent (mg) / Weight of metal adsorbed on adsorbent (mg)

The highest indium desorption rate was 90% when ethylenediaminetetraacetic acid and nitrile acetic acid were used as the indium desorption agent, and about 85% indium desorption rate was shown for hydrochloric acid. In terms of indium desorption rate, ethylenediaminetetraacetic acid and nitrile acetic acid were excellent as indium desorbents, but considering economical efficiency, hydrochloric acid having an indium desorption rate of 85% was selected as an optimal indium desorbent.

That is, as an indium desorbent for desorbing indium adsorbed on an indium selective adsorbent, hydrochloric acid (HCl), ethylene diaminetetraacetic acid (EDTA: ethylene diaminetetraacetic acid), or nitrile acetic acid (NTA: nitrilo triacetic acid) may be used alone or in combination. It is preferable to mix and use the above.

Hereinafter, a method for recovering indium from waste portable equipment using the indium selective adsorbent of the present invention will be described in detail. Hereinafter, a portable device is a mobile phone (mobile phone), an MP3 player, a tablet PC (personal computer), a netbook (netbook), a laptop computer (lap-top computer), a digital camera, a camcorder, etc. It is meant to include all possible electronics.

The method for recovering indium from a waste portable device using the indium selective adsorbent of the present invention includes recovering liquid crystal from the waste portable device.

Various portable devices such as mobile phones generally comprise about 60% by weight of external materials and accessories such as plastic cases and metal plates, about 31% by weight of printed circuit boards (PCBs) and various components, and about 9% by weight of liquid crystal (glass) parts. Although indium, which is a valuable metal, is not contained in the exterior materials and accessories such as plastic cases and metal plates, the liquid crystal contains indium as shown in Table 4 below.

Metal content (ppm) indium 118 Remark 614 aluminum 3,758 Copper 30 lead 43 nickel 459

Indium is contained not only in the liquid crystal of a portable device but also in the wastewater generated by etching the liquid crystal.

Accordingly, by applying the principle that the polymer component such as plastic or synthetic fiber is decomposed into organic compounds and vaporized when heated in an oxygen-free state, the polymer component such as plastic case, decorative string, etc. is separated and removed from the waste portable device, and applied to the magnetic force of the electromagnet. The liquid crystal is recovered from the printed circuit board (PCB), liquid crystal, dust, and various components remaining after the metal exterior member is separated and removed.

In addition, the method for recovering indium from a waste portable device using the indium selective adsorbent of the present invention includes dissolving the liquid crystal in an alkaline solution to recover an indium-containing residue.

Before dissolving the liquid crystal in an acid, in the liquid crystal, a metal selected from the group consisting of molybdenum, aluminum, tin, zinc, chromium, iron, copper, magnesium and other impurities and combinations thereof and metal hydrate forms containing these metals It is preferable to raise the indium content by eluting and removing it.

To this end, in the present invention, indium is dissolved in an alkali solution by using an insoluble property with respect to an alkali solution, thereby dissolving and removing metals dissolved in the alkaline solution, such as aluminum, silicon, tin, etc., from the liquid crystal. The indium-containing residue as a solid is recovered by a method such as centrifugation or the like.

In addition, the method for recovering indium from a waste portable device using the indium selective adsorbent of the present invention includes dissolving the indium-containing residue in an acid to form an indium solution.

The indium-containing residue as described above is dissolved in an acid such as hydrochloric acid, sulfuric acid, nitric acid, and the like to form an indium solution containing indium ions.

In addition, a method of recovering indium from a waste portable device using the indium selective adsorbent of the present invention includes recovering the remaining waste liquid after reducing the indium ions of the indium dissolving solution to indium by a metal substitution reaction.

By adding a metal having a greater ionization tendency than indium to an indium solution containing indium ions as described above, a metal substitution reaction is performed, thereby recovering the indium in which the indium ions of the indium solution are substituted and recovering the remaining waste solution. do.

Since the waste liquid still contains a significant amount of indium, in the present invention, the phenol group (-C ₆ H ₅ OH) of the sawdust molecule is removed from the waste liquid using an indium selective adsorbent in which the phosphate group (PO ₄ ^3- ) is substituted. It is to recover indium.

Further, using indium-selective adsorbent of the present invention method for recovering indium from waste portable device is a phosphate group (PO ₄ ^{3 -)} of the waste indium hydroxide phenol group (-C ₆ H ₅ OH) in the molecule is substituted by sawdust Adsorption with a selective indium selective adsorbent.

The indium contained in the waste liquid is adsorbed with an indium selective adsorbent formed by replacing a phenolic hydroxide group (-C ₆ H ₅ OH) of a sawdust molecule with a phosphoric acid group (PO ₄ ^3- ).

As described above, when the indium contained in the waste liquid is adsorbed with an indium selective adsorbent, the waste liquid is adjusted to pH 3.5 so that the indium selective adsorbent can adsorb and remove only 90% or more of indium without adsorbing zinc. It is preferable in that it can.

In addition, the method for recovering indium from the waste portable device using the indium selective adsorbent of the present invention includes the step of recovering indium adsorbed on the indium selective adsorbent by indium desorbent.

Indium adsorbed on the indium selective adsorbent is hydrochloric acid (HCl), nitric acid (HNO ₃ ), ethylenediaminetetraacetic acid (EDTA: ethylene diaminetetraacetic acid), nitrile acetic acid (NTA: nitrilo triacetic acid), sodium hydroxide (NaCl), etc. It recovers by desorption by the indium desorption agent used or used in mixture of 2 or more types.

Hereinafter, examples of a method for recovering indium from a waste portable device using an indium selective adsorbent according to the present invention will be described in more detail, and the present invention is not limited to the following examples.

<Example 4>

1. The wastewater generated during the liquid crystal etching process was neutralized and used as a metal solution, and the metal content was measured. The measurement results are shown in Table 5 below.

Metal content (ppm) indium 22,196 aluminum 38644.6 molybdenum 31418.7 chrome 9305.7 salt 17456.0 magnesium 2829.6 silicon 340.6 calcium 253.8 manganese 11.7 iron 1421.2 cobalt - nickel 64.4 Copper 1041.1 zinc 255.5 zirconium 15.0 cadmium 0.5 Remark 1965.5 antimony 151.2 lead 0.6 Bismuth 1.8

2. The indium-containing residue formed by mixing and stirring 100 g of sodium hydroxide to 100 g of the metal solution was recovered and the removal rate of the metal was measured, and the results are shown in Table 6 below.

division Removal rate (% by weight) Alkali Concentration (N) aluminum silicon Remark Sodium hydroxide 2 0.0 0.0 6.3 4 13.0 0.0 71.4 8 51.1 43.3 85.3

3. The indium-containing residue was dissolved in 0.1 M hydrochloric acid and 0.5 M hydrochloric acid, respectively, and the extraction rate of the metal was measured. The measurement results are shown in FIG. 12.

4. The plate-like zinc was added to the indium solution, and maintained at a temperature of 60 ° C. for 18 hours to reduce the indium ions of the indium solution to indium by a metal substitution reaction, thereby recovering the remaining waste solution.

5. The indium selective adsorbent and waste liquid were mixed and stirred for 24 hours at 25 ° C. and pH 3.5 in a shaking incubator, and the waste liquid of the mixture reaching the adsorption equilibrium was separated from the indium selective adsorbent by a filter.

6. Indium adsorbed on the indium selective adsorbent was recovered with hydrochloric acid, an indium desorbent. As a result of measuring the recovered indium and the separated waste liquid, about 86% of the indium ions could be selectively removed, and the adsorption capacity of the indium ions per 1.0 g of the indium selective adsorbent was about 1.1 mg / g.

As mentioned above, although preferred embodiment of this invention was described in detail, this invention is not limited to the said embodiment, A various deformation | transformation by a person of ordinary skill in the art within the scope of the technical idea of this invention is carried out. This is possible.

Claims (8)

Indium selective adsorbent, characterized in that the phenol group (-C ₆ H ₅ OH) of the sawdust molecule is substituted with a phosphoric acid group (PO ₄ ^3- ).
The method of claim 1, wherein the indium desorbent used to desorb the indium adsorbed on the indium selective adsorbent is hydrochloric acid (HCl), ethylene diaminetetraacetic acid (EDTA: ethylene diaminetetraacetic acid) and nitrile acetic acid (NTA: nitrilo triacetic acid) Indium selective adsorbent that is at least one or more indium leaving agent selected from the group consisting of.
Immersing the sawdust in an aqueous solution of urea phosphate and filtering to form a solid phosphate impregnated sawdust;
The method comprising the phosphate group to form a substituted sawdust substituted with ^- the phenolic hydroxide group of the phosphate impregnated heat treated sawdust shavings molecule (-C ₆ H ₅ OH) is a phosphate group (PO ₄ ^3); And
Method for producing an indium selective adsorbent comprising the step of washing and drying the phosphate-substituted sawdust.
The method of claim 3, wherein the aqueous solution of urea phosphate used in forming the phosphate-impregnated sawdust comprises 40 to 60 parts by weight of water with respect to 50 parts by weight of phosphoric acid.
The method of claim 3, wherein the heat treatment of the phosphate-impregnated sawdust in the step of forming the phosphate-substituted sawdust is configured to be carried out at 80 to 120 ℃.
The method of claim 3, wherein the heat treatment of the phosphoric acid-impregnated sawdust in the step of forming the phosphate-substituted sawdust is configured to be carried out for 90 to 150 minutes.
Recovering the liquid crystal from the waste portable device;
Dissolving the liquid crystal in an alkaline solution to recover an indium-containing residue;
Dissolving the indium-containing residue in an acid to form an indium solution;
Recovering the remaining waste liquid after reducing the indium ions of the indium dissolving solution to indium by a metal substitution reaction;
Adsorbing the indium in the waste liquid with the indium selective adsorbent of claim 1; And
And recovering the indium adsorbed on the indium selective adsorbent by recovering the indium adsorbed by the indium desorbent of claim 2.
8. The method of claim 7, wherein the step of adsorbing the indium ions is carried out by adjusting the waste liquid to pH 3.5.

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