KR101289987B1 - Method for recovering valuable metal in lcd waste glass - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a process for recovering valuable metals from waste glass generated in a liquid crystal display (LCD) production process and waste glass produced from waste electronic products. In order to finely crush the waste glass, strontium extraction step (A) using an alkali solvent to make an alkaline solution (3) containing strontium by putting an alkali solvent (2) in the crushed waste glass; In order to extract the indium and tin contained in the ITO film of the LCD waste glass, an acidic solvent (5) is added to the waste glass residue (4) from which strontium is extracted to make an acid solution (6) containing indium and tin (6). Indium and tin extraction using a solvent (B); In order to extract indium and tin contained in the acidic solution 6 and extract strontium contained in the alkaline solution 3, an alkaline solution 3 containing the strontium in the acidic solution 6 is provided. Precipitating salts of indium, tin and strontium in a neutral state by the addition of the salts of the valuable metals by heat dissolving to remove impurities and cooling the valuable metals using the acidic solution and alkaline solution to recover the valuable metals (C) It characterized in that the configuration, including.

Description

Recovery method of valuable metals from LCD waste glass and its process {METHOD FOR RECOVERING VALUABLE METAL IN LCD WASTE GLASS}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a process for recovering valuable metals from waste glass generated in a liquid crystal display (LCD) production process and waste glass produced from waste electronic products. The indium (In) and tin (Sn) and strontium (Sr) contained in the LCD waste glass itself is extracted together to provide a highly economical valuable metal recovery method and process.

Liquid crystal displays (LCDs) inject liquid crystals between two thin glass substrates, and then apply characters to a transparent electrode to display characters or pictures. It is widely used in the operation system and the like.

In general, an LCD uses a liquid crystal panel manufactured by bonding a first substrate on which a circuit element is formed and a second substrate on which a color filter is formed. In this case, glass is generally used for the first substrate or the second substrate. Liquid crystal is injected between the two substrates. And a transparent electrode is provided in a 1st board | substrate or a 2nd board | substrate. In this case, an indium tin oxide (ITO) film is used as the transparent electrode. The ITO film is mainly formed by sputtering, and indium (In) is used as a target. Indium (In) is a valuable metal obtained during zinc refining, and its depletion is recently threatened. Generally, about 300 mg / L of indium is contained in the waste LCD, and it is desired to recover the indium during the recycling process.

Accordingly, various techniques for recovering indium from the ITO waste target generated in the LCD process have been developed. For example, a method of dissolving an ITO waste target in an acid such as acetic acid or hydrochloric acid, precipitating and removing impurities such as Sn, neutralizing by adding ammonia, and recovering it as indium hydroxide is well known.

However, recovery of indium from LCD waste glass by applying such indium recovery method is difficult to realize due to the low economic feasibility. Accordingly, until now, the waste glass generated in the LCD production process or the waste glass generated in the home appliances are mostly buried or discarded, causing secondary environmental pollution or excessive processing costs. In particular, since indium and tin contained in the LCD waste glass are discarded, there is a problem of wasting valuable metals. LCD waste glass varies depending on the product, but tin is contained in the amount of 600-2000mg / L.

Currently, research and methods for extracting and recovering liquid crystals, indium or tin, which are valuable substances present in LCD waste glass, have been proposed for the LCD waste glass, but LCD glass, which is the waste after extracting the valuables, has been proposed. The residue or LCD waste glass itself lacks special recycling technology in consideration of economic feasibility, and the entire amount generated is incinerated or landfilled.

By incineration and landfill treatment of LCD waste glass, it is difficult to comply with EU WEEE regulations such as recycling rate of 75% or more and EPR legal recycling rate of more than 65%. This is because the relative weight of is high. For this reason, in order to reinforce the international competitiveness of producers and countries, it is very important to prepare an effective recycling plan related to LCD waste glass. Therefore, recycling methods of LCD waste glass have been proposed in various forms.

In 1993, VICOR, Germany, used EDV, Elctronikschrott, Abfallwirtschaft 1993, pp. Although the recycling method for recovering liquid crystal from LCD waste glass has been proposed in 231-241, there is no mention of the use of LCD waste glass itself. However, this method of recovering the liquid crystal is not practical because it is not only dioxin is generated in the liquid crystal recovery process but also very economical.

In 2000, Sharp has proposed a process of recovering organic substances, spectroscopic plates, color filters, etc. present in the LCD panel at a temperature range of 450 ° C. to 650 ° C. with air blocked in Japanese Patent Laid-Open No. 2000-24613. It's not about LCD glass. In 2001, Sharp Corporation, in three patent applications (Japanese Patent Laid-Open No. 2001-305501, Japanese Patent Laid-Open 2001-305502, Japanese Patent Laid-Open 2001-337305), recovered liquid crystals from waste LCD panels, shredded LCD glass, and then attached them to glass substrates. The technique of finally recovering glass after removing a thin film is disclosed. It is proposed here that the recovery of the effective metal is possible if necessary, but it suggests only a method for use as a gallet glass which is used by partially adding the remaining glass to the manufacture of the LCD glass.

2004 Merck (Roland Martin, Brigitte Simon-Hettich, Werner Beckedr, Proc. Int. Disp. Workshops, vol. 11, 583 (2004), proposed a method of lining agent that prevents corrosion of incinerator walls and coal substitute material used as silica or foundry sand substitute or reducing agent for metallurgical process.

In 2005, Sharp, Japan, reported in Sharp Gibo No. 92, p 17 (August 2005), how to make tiles with waste LCD and recover indium.

In 2007, Roland Martin of Germany, in an extension of Merck's research in 2004, used the technology of using LCD waste glass as a partial additive or replacement for melting, metallurgy and incineration processes in the 900 ° C to 1700 ° C temperature range. (US Patent Application Publication US 2007/0193414 A1).

As described above, various techniques for recovering indium from waste glass generated in the LCD process have been developed. For example, a method of dissolving an ITO waste target in an acid such as acetic acid or hydrochloric acid, precipitating and removing impurities such as Sn, neutralizing by adding ammonia, and recovering it as indium hydroxide is well known.

However, it is difficult to realize indium recovery from LCD waste glass by applying such an indium recovery method because of too little economic feasibility. Accordingly, until now, the waste glass generated in the LCD production process or the waste glass generated in the home appliances are mostly buried or discarded, causing secondary environmental pollution or excessive processing costs. In particular, since indium and tin contained in the LCD waste glass are discarded, there is a problem of wasting valuable metals. LCD waste glass varies depending on the product, but tin is contained in the amount of 600-2000mg / L.

Accordingly, the present invention relates to a method and a process that can recover the valuable metals economically compared to the conventional valuable metal recovery method. That is, the present invention is to increase the economics of the rare metal recovery method by extracting valuable metals such as strontium contained in the LCD waste glass itself as well as indium and tin contained in the ITO of the LCD waste glass.

That is, unlike ordinary glass, LCD glass contains various additives to secure glass strength, transparency, electronic properties, and the like. For example, LCD glass has a thin film thickness of 160 ~ 300㎛ boric acid (B) to secure the strength, arsenic (As) to secure the transparency, strontium to block the electromagnetic waves and smooth the flow of electrons Etc. are included. Among these, strontium contains 3 ~ 4% and is valuable as a valuable metal.

The strontium is an alkaline earth metal and has an atomic number of 38, an atomic symbol of Sr, an atomic weight of 87.62, a specific gravity of 2.54, a melting point of 769 ° C, and a chemical property between calcium (Ca) and barium (Ba). Strontium metal is soft, silvery white or yellow in color and is produced from zirconia or strontianite. Strontium is added in trace amounts in the form of SrO or SrSO4 and is used as a permanent magnet and as a component of LCD glass.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art, and a main object of the present invention is to provide a more economical valuable metal recovery method and process by extracting indium, tin and strontium from LCD waste glass at once.

It is another object of the present invention to extract indium, tin and strontium contained in the ITO film of the LCD waste glass, and extracting strontium contained in the LCD waste glass itself. To provide a valuable metal recovery method and process.

Method and process for recovering the valuable metal from the LCD waste glass according to the present invention for achieving the above object, (1) to crush the LCD waste glass, and (2) to put the alkali solvent in the crushed waste glass to extract strontium (3) separating the strontium-containing alkaline solution from the waste glass residue by using a screen, (4) adding acidic solvent to the separated waste glass residue and heating it to extract indium and tin, and (5) (6) precipitate the salts of indium, tin and strontium by neutralizing the acid solution containing indium and tin and the waste glass residue, and neutralizing the alkaline solution containing strontium in the acid solution containing indium and tin. (7) separating precipitates and neutral solutions of indium, tin and strontium using filter paper, (8) thermally dissolving at high temperature to remove impurities from the separated precipitates, (9) thermally dissolved indium, By gradually cooling the seats and strontium is created and tin, indium, strontium and the ingot (ingot) by sequential solidification, characterized in that cleaning the tin, indium, strontium in the ingot by using a 10 ultra-pure water.

According to the present invention, indium, tin and strontium are simultaneously extracted through one process including extracting indium and tin contained in the ITO film of the LCD waste glass and extracting strontium contained in the LCD waste glass itself. Extraction has the effect of providing a valuable metal recovery method and process economical and business.

In addition, the present invention by using the ammonia water used in the step of extracting strontium as a neutralizing agent to neutralize the acid solution generated in the step of extracting indium and tin not only saves the amount of neutralizing agent and simplify the process but also indium, Extracting tin and strontium at once has the effect of providing a valuable metal recovery method and process that is economical and feasible.

1 is a schematic flowchart showing a method and process for recovering valuable metals from an LCD waste glass according to the present invention;
2 is a flow chart showing a method and process for recovering valuable metals from an LCD waste glass according to the present invention;
Figure 3 is a schematic process diagram showing a method and process for recovering valuable metals from the LCD waste glass according to the present invention.

Hereinafter, with reference to the accompanying drawings will be described in detail a method and process for recovering valuable metals from the LCD waste glass according to the present invention.

First, as shown in Figures 1 and 2, the method and process for recovering the valuable metal from the LCD waste glass of the present invention, strontium extraction step (A) using an alkaline solvent, indium and tin extraction step using an acidic solvent (B) and the valuable metal extraction step (C) using an acidic solution and an alkaline solution.

In the strontium extraction step (A) using the alkaline solvent, in order to extract strontium contained in the LCD waste glass itself, finely crush the waste glass, and put the alkali solvent (2) in the crushed waste glass containing strontium It is a step to make an alkaline solution (3).

In the extraction of indium and tin using the acidic solvent (B), in order to extract indium and tin contained in the ITO film of the LCD waste glass, the acid solvent (5) is disposed on the strontium-extracted waste glass residue (4). This step is to make an acid solution (6) containing indium and tin.

Subsequently, the valuable metal extraction step (C) using the acidic solution and the alkaline solution extracts indium and tin contained in the acidic solution 6 and simultaneously extracts strontium contained in the alkaline solution 3. To this end, an alkaline solution (3) containing strontium is added to the acidic solution (6) to precipitate salts of indium, tin and strontium in a neutral state, and heat-dissolve the salts of the precipitated valuable metals to remove impurities and then cool. To recover the valuable metals.

Referring back to Figure 2, the strontium extraction step (A) using the alkaline solvent, the step of crushing the collected LCD waste glass using a grinder (S10), the alkaline solvent (1), More preferably, an alkaline solvent extraction step (S20) of extracting strontium contained in waste glass by adding ammonia water, and an alkaline solution (3) generated in the alkaline solvent extraction step (S20) using a predetermined screen (3) ) And separating the remaining waste glass residue (4) (S30).

The waste glass pulverized in the step of crushing the waste glass (S10) is easier to extract strontium as the size is smaller, but when the size of the waste glass is too small, it becomes difficult to separate the solid-liquid separation in the screening step (S30) of the waste glass The size is preferably pulverized to 1-3mm.

Ammonia water may be used as the alkaline solvent 2 used in the alkaline solvent extraction step (S20). Ammonia water is made by dissolving ammonia in water, and it dissolves while cooling because it generates heat. The solubility changes with temperature, and the higher the concentration, the smaller the specific gravity. The state of the NH ₃ molecule is not considered to be the presence of ammonium hydroxide NH ₄ OH, and is known to be in the intermediate state of NH ₃ · H ₂ O to which the water molecule is added and NH ₄ OH. Ammonia water is a colorless, transparent liquid with ammonia odor, pungent taste, and alkalinity. When heated or in the presence of a strong base, the solubility decreases and ammonia is lost. Ammonia water has an alkaline reaction and reacts with acid to form ammonium, since ammonia reacts with water to form a base called ammonium hydroxide. This ammonia water dissolves strontium in the waste glass. At this time, the amount of ammonia water used is 15 to 30% of the waste glass mass.

Indium and tin extraction step (B) using the acidic solvent, the strontium is extracted into the waste glass residue (4) to put any one selected from an acidic solvent (3), preferably nitrogen, chlorine, sulfuric acid at a constant temperature An acidic solvent extraction step (S40) of heating and extracting indium and tin from the ITO membrane, and an acidic solution (6) generated in the acidic solvent extraction step (S40) using a predetermined screen and containing indium and tin and waste It comprises a step (S50) for separating the glass residue (7).

At this time, the acid solvent (3) may be any one selected from nitrogen, chlorine, sulfuric acid, or any combination thereof. However, nitric acid has a high solubility in indium but a large amount of impurities, and hydrochloric acid has a low solubility but a small amount of impurities. The acid solvent (2) is used in an amount of 10 to 20% of the mass of waste glass. And the temperature for extracting the valuable metal in the acid solvent extraction step (S40) is maintained at 150 ~ 300 ℃.

Subsequently, the valuable metal extraction step (C) using the acidic solution and the alkaline solution is generated in the first screening step (S30) described above and the alkaline solution (3) containing strontium and the second screening step (S50). And mixing the acid solution 6 containing indium and tin to precipitate salts of indium, tin, and strontium in a neutral state (S60), and using the predetermined screen or filter paper, using the predetermined screen or filter paper. The third screening step (S70) of separating the precipitate (7) and the neutral solution (8) of the indium, tin, strontium produced in the step (S60) of precipitation of the salt, the precipitate of the separated indium, tin, strontium In order to remove the impurities (10) contained in (7), the precipitate (7) of indium, tin, and strontium was put in a crucible and heated to high temperature for thermal melting (S80), and the thermally dissolved indium, tin, and strontium Slowly cool to tin, indium and Rontyum it achieved by this step (S90) to create a solidified ingot in sequence, the production of valuable metals comprising the step (S100) of washing with ultra-pure water to the ingot.

The heat dissolution step (S80) is maintained at 900 ~ 1200 ℃ 1-8 hours. The cooling step (S90) is to gradually cool the heat-melted metal over 10 ~ 24 hours to determine the position of the tin, indium, strontium layer by the weight of the metal during cooling. Therefore, the ingot of the valuable metal may be divided into tin, indium, and strontium, and the purity may be gradually increased by remelting the cut tin, indium and strontium.

<Examples>

The collected LCD waste glass is prepared by grinding to a size of 1-3mm. 100 g of crushed waste glass was placed in a container, and 200 ml of ammonia water (NH ₃ 28%) was injected to extract strontium in the waste glass. The screen was used to separate the strontium-containing alkaline solution and the waste glass residue.

Then, 250 ml of HCl (35%) was injected into the separated waste glass residue to extract indium and tin contained in the ITO membrane of the waste glass. The screen was then used to separate the waste glass residue and the acidic solution containing indium and tin.

And an alkaline solution was injected into the acidic solution separated above to adjust the pH to 7.0. As a result, salts of indium, tin and strontium precipitated at the bottom of the vessel. A screen (filter) was used to separate the precipitates of indium, tin and strontium from the neutral solution.

The precipitates of indium, tin, and strontium separated were placed in a crucible at 1100 ° C., heated for 6 hours to melt, and impurities removed from the surface were removed. The molten valuable metal was slowly cooled for 24 hours to obtain a valuable metal ingot in which tin, indium, and strontium were sequentially arranged.

As described above, the method and process for recovering valuable metals from the LCD waste glass of the present invention comprises the steps of extracting indium and tin contained in the ITO film of the LCD waste glass, and extracting strontium contained in the LCD waste glass itself. And using the alkaline solution generated in the step of extracting the strontium as a neutralizing agent for neutralizing the acidic solution generated in the step of extracting the indium and tin, and subsequently indium, tin, and strontium at once. It is characterized in that the extraction.

1: crushed waste glass 2: alkali solvent
3: alkaline solution 4, 7: waste glass residue
5: acidic solvent 6: acidic solution
8: precipitate of indium, tin and strontium 9: neutral solution
10: Impurity 11: Ingot
12a, 12b, 12c: screen

Claims (6)

In order to extract strontium contained in the LCD waste glass itself, the collected LCD waste glass is pulverized using a pulverizer (S10), and the alkaline solvent (1) is put in the pulverized waste glass and included in the waste glass. Alkaline solvent extraction step (S20) for extracting strontium, and using a screen to separate the alkaline solution (3) and the remaining waste glass residue (4) generated in the alkaline solvent extraction step (S20) and the strontium Strontium extraction step (A) using an alkali solvent to make an alkali solution (3) containing strontium through the screen step (S30);
An acid solvent (3) is added to the waste glass residue (4) from which the strontium is extracted and heated to a constant temperature to extract indium and tin from the ITO membrane (S40), and the acid solvent is extracted using a screen. The acidic solution (6) containing indium and tin is subjected to a secondary screening step (S50) generated in step S40 and separating the acidic solution (6) containing indium and tin and the waste glass residue (7). Indium and tin extraction step (B) using an acid solvent to make;
In order to extract indium and tin contained in the acidic solution 6 and extract strontium contained in the alkaline solution 3, an alkaline solution 3 containing the strontium in the acidic solution 6 is provided. Precipitating salts of indium, tin and strontium in a neutral state by the addition of the salts of the valuable metals by heat dissolving to remove impurities and cooling the valuable metals using the acidic solution and alkaline solution to recover the valuable metals (C) The method for recovering valuable metals from the LCD waste glass, characterized in that comprising a. The method of claim 1,
Wherein said alkaline solvent is ammonia water, and said alkaline solution is ammonia water containing strontium. delete delete The method of claim 1,
Valuable metal extraction step (C) using the acidic solution and alkaline solution,
Neutral by mixing the alkaline solution (3) generated in the primary screening step (S30) described above and containing strontium, and the acidic solution (6) generated in the second screening step (S50) described above and containing indium and tin Precipitating the salt of indium, tin, strontium in the state (S60);
Tertiary screening step of separating the precipitate (7) and the neutral solution (8) of the indium, tin, strontium produced in the step (S60) of depositing the salt of the indium, tin, strontium using a predetermined screen or filter paper ( S70) comprising a method for recovering valuable metals from the LCD waste glass. 6. The method of claim 5,
Valuable metal extraction step (C) using the acidic solution and alkaline solution,
In order to remove the impurities (10) contained in the separated precipitates (7) of indium, tin, strontium and put the precipitate (7) of the indium, tin, strontium in a crucible and heated to a high temperature to heat dissolution (S80) and ;
Gradually cooling the heat-dissolved indium, tin and strontium to form an ingot in which tin, indium and strontium solidify in order (S90);
Method for recovering the valuable metal from the LCD waste glass, characterized in that the produced valuable metal further comprises the step of washing the ingot with ultrapure water (S100).

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