KR20200025957A - Recycling method of ammonium nitrate waste - Google Patents

Abstract

The present invention relates to a method for recycling ammonium nitrate waste and, more specifically, to a method for recycling ammonium nitrate waste, which removes and acquires heavy metal and rare metal, such as iron, chromium, indium, and gallium, from the ammonium nitrate waste, acquires high purity recycled ammonium nitrate, and concentrates and refines the high purity recycled ammonium nitrate to apply the same to fertilizer so as to recycle resources and prevent environmental pollution. According to the present invention, the method comprises: a pretreatment step (S100) of removing impurities and heavy metal from ammonium nitrate waste; a dissolution and neutralization step (S200) of dissolving and neutralizing the ammonium nitrate waste from which the impurities and the heavy metal are removed; a filtering step (S300) of filtering the dissolved and neutralized ammonium nitrate waste; a valuable metal extraction and removal step (S400) of solvent-extracting a filtered ammonium nitrate waste filtrate to remove indium (In) and gallium (Ga) which are valuable metal; a concentration step (S500) of concentrating the filtrate from which indium and gallium are removed; and a processing step (S600) of using the concentrated filtrate as a raw material to manufacture fertilizer and a microorganism nutritional supplement.

Description

Recycling method of ammonium nitrate waste {RECYCLING METHOD OF AMMONIUM NITRATE WASTE}

The present invention relates to a method for recycling ammonium nitrate waste, and more particularly, to remove and obtain heavy metals and rare metals such as iron, chromium, indium and gallium from ammonium nitrate waste, and to obtain high-purity recycled ammonium nitrate, The present invention relates to a method for recycling ammonium nitrate waste, which can be recycled by concentrating and purifying and applying it to fertilizer, as well as preventing environmental pollution.

In general, transparent conducting oxide (TCO) has a high transmittance and excellent electrical properties in the visible range, such as liquid crystal display (LCD), plasma display panel (PDP), solar cell, light emitting device (light) It is used as a transparent electrode for emitting diodes (LEDs), etc., and has high utility in various fields such as low-emissitivity window, touch-control panel, and electro-magnetic shield. It is an indispensable material that realizes high added value that is indispensable for the development of the medium and long term display industry.

At present, TCO is composed of more than 90% of ITO (Indium-Tin Oxide), which has excellent light transmittance, conductivity, and favorable pattern formation, and researches on ITO alternative materials and processes. Oxide) is in progress.

Meanwhile, the metal oxide manufacturing process is a raw material for indium tin oxide (ITO) and IGZO target manufacturing processes and is an indispensable material in the LCD, PDP, touch panel, and OLED industries. This happens.

However, ammonium nitrate waste generated in the metal oxide (Metal Oxide) process of the electrical and electronics industry is mainly treated by landfill and neutralization, causing environmental pollution, which is emerging as a social problem.

Therefore, many attempts and developments have been made to recycle such wastes, and as related prior arts, Patent Document 1 neutralizes using 25% NaOH solution after leaching with hydrochloric acid using IGZO scrap as a starting material. A method for producing a gallium metal through electrolysis of a gallium-containing solution generated by filtration is disclosed, and Patent Document 2 discloses a batch vacuum in which a high concentration of indium-containing waste acid generated in the manufacturing process of an ITO (Indium-Tin Oxide) thin film is produced. A method for recovering indium and acid by vacuum evaporation and concentration of indium-containing waste acid, which is an eco-friendly method using high-purity indium and simultaneously recovering the indium, by using an evaporation and concentration facility, has been proposed.

On the other hand, UAN (Urea Ammonium Nitrate) is a liquid fertilizer (Urea ammonium and ammonium nitrate mixed) (ammonium nitrate 38% -42%, urea 28% -32%, water 26-34%). Define liquid fertilizers for 28% to 32%. Currently, domestic production and sales are not available, and are manufactured by four major nitrogen-based fertilizer multinational companies, CF Industries, Farmland, Arcadian, and Terra (8,000,000 ~ 10,000,000t / year) .The main producers are USA, Ukraine, China, etc. It is used in North America, Southeast Asia, India and Australia.

In Korea, ammonium nitrate dissolves well in water and is used as a fertilizer for hydroponic cultivation and nutrient cultivation, but domestic consumption is used at about 10,000ton / year.

The present inventors dissolve and neutralize ammonium nitrate waste in Publication No. 10-2017-0060834 (Patent Document 3) as part of a study to fertilize waste ammonium nitrate, a waste generated in the display electronics industrial process, and extract the solvent. After the removal of the metal, the filtrate presented a recycling method to utilize the filtrate as a compound fertilizer, UAN (Urea Ammonium Nitrate) fertilizer.

However, the ammonium nitrate produced by the recycling method contains heavy metals and impurities, and the concentration of ammonium nitrate obtained is also low, which is not suitable for use as a fertilizer without further processing.

Accordingly, the present inventors have developed a recycling method for minimizing the impurities and heavy metal content of ammonium nitrate waste and concentrating to obtain high purity and high concentration of ammonium nitrate, and the ammonium nitrate prepared by the recycling method is a separate additional process. The present invention has been found to be suitable for application to UAN fertilizers and microbial nutrients without treatment.

Patent Document 1: Japanese Patent Application Laid-Open No. 2012-193396 (Method for Producing Metal Gallium) Patent Document 2: Domestic Patent No. 10-1251887 (Method for recovering indium and acid by vacuum evaporation and concentration of indium-containing waste acid) Patent Document 3: Domestic Publication No. 10-2017-0060834 (Recycling Method of Ammonium Nitrate Waste)

An object of the present invention for solving the above problems is to remove and obtain heavy metals and rare metals such as iron, chromium, indium and gallium from ammonium nitrate waste, and to obtain high-purity recycled ammonium nitrate, which is concentrated and purified It is to provide a recycling method of ammonium nitrate waste that can be applied to fertilizers to not only recycle resources but also prevent environmental pollution.

Recycling method of ammonium nitrate waste of the present invention for solving the above problems is a pretreatment step (S100) to remove impurities and heavy metals from the ammonium nitrate waste; and dissolution and neutralization to dissolve and neutralize ammonium nitrate waste from which impurities and heavy metals are removed Step (S200); and filtering the dissolved and neutralized ammonium nitrate waste (S300); and solvent extraction of the filtered ammonium nitrate waste filtrate to extract indium (In) and gallium (Ga) as valuable metals; Extraction and removal of valuable metals to be removed (S400); and concentration step (S500) of concentrating the filtrate from which indium and gallium have been extracted and removed; and processing step of manufacturing the fertilizer or microbial nutrient from the concentrated filtrate as raw materials (S600). ).

The pretreatment step (S100) is a first pretreatment step (S110) for filtering the precipitate formed by adding an alkaline solution to pH 3 to 4 to the ammonium nitrate waste (S110); and the first pretreatment step A second pretreatment step (S120) of adding a surfactant to the filtrate generated by to form agglomerates in which heavy metals are adsorbed, and filtering the precipitate after cooling and settling to remove the heavy metals.

In the dissolving and neutralizing step (S200), 1 to 50 parts by weight of ammonium nitrate waste is added to 100 parts by weight of nitric acid (HNO 3), and dissolved by stirring for 1 to 24 hours at a temperature of 60 to 90 ° C., followed by ammonia (NH 3). It is characterized in that the neutralization to pH 7 ~ 8.

The valuable metal extraction and removal step (S400) is based on 100 parts by weight of the filtered ammonium nitrate waste filtrate, 20 to 200 weight of a solvent alone or in combination of two or more of trialkylphosphine solvent, oxime solvent, or phosphate solvent. It is characterized in that the addition is added and stirred for 30 minutes to 2 hours at a speed of 500 ~ 1,500rpm to obtain and remove the concentrated solution extracted indium (In) and gallium (Ga)

The concentration step (S500) includes a first concentration step (S510) for evaporating and concentrating the filtrate from which indium and gallium have been extracted and removed; and a second concentration step (S520) for concentrating the evaporated concentrate using electrodialysis. Characterized in that.

The second concentration step (S520) during the electrodialysis, the ion exchange resin is characterized in that one of the cation exchange resin ^® CMX, CM-1 ^®, Selemin CMV ^®, and combinations thereof.

The urea-ammonium nitrate mixed fertilizer for solving the above problems is characterized in that the present invention is prepared using ammonium nitrate obtained by the recycling method of the ammonium nitrate waste described above.

As described above, according to the recycling method of ammonium nitrate waste according to the present invention, high purity regenerated ammonium nitrate is obtained while removing and obtaining heavy and rare metals such as iron, chromium, indium and gallium from the ammonium nitrate waste. In addition, by concentrating and purifying and applying it to fertilizers, not only can resources be recycled, but there is an effect to prevent environmental pollution.

1 is a flow chart showing a method for recycling ammonium nitrate waste according to the present invention.
Figure 2 is a graph showing the concentration change of iron ions according to (a) iron content ICP-OES results and (b) pH in the pretreatment step (S100) according to the present invention.
Figure 3 is a graph showing the chromium removal efficiency according to (a) chromium content ICP-OES results and (b) S / M in the pretreatment step (S100) according to the present invention.
Figure 4 is a photograph of the evaporation concentration equipment applied in the concentration step (S500) according to the present invention.
5 is a graph showing the selectivity of the ion exchange membrane in the concentration step (S500) according to the present invention.
Figure 6 is a graph showing the electrodialysis efficiency in the concentration step (S500) according to the present invention.
Figure 7 is an ammonium nitrate purified and concentrated filtrate prepared in the method for recycling ammonium nitrate waste according to the present invention UAN fertilizer photograph.

Specific features and advantages of the invention will now be described in detail with reference to the accompanying drawings. Prior to this, when it is determined that the detailed description of the function and its configuration related to the present invention may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted.

The present invention relates to a method for recycling ammonium nitrate waste, and more particularly, to remove and obtain heavy metals and rare metals such as iron, chromium, indium and gallium from ammonium nitrate waste, and to obtain high-purity recycled ammonium nitrate, The present invention relates to a method for recycling ammonium nitrate waste, which can be recycled by concentrating and purifying and applying it to fertilizer, as well as preventing environmental pollution.

1 is a flow chart showing a method for recycling ammonium nitrate waste according to the present invention.

The recycling method of ammonium nitrate waste according to the present invention is a pretreatment step (S100) for removing impurities and heavy metals from the ammonium nitrate waste and a dissolution and neutralization step (S200) for dissolving and neutralizing ammonium nitrate waste from which impurities and heavy metals have been removed. And a filtration step of filtering neutralized ammonium nitrate waste (S300) and a valuable metal extraction and removal step of extracting and removing indium (In) and gallium (Ga), which are valuable metals, by solvent extraction of the filtered ammonium nitrate waste filtrate. (S400) and the concentration step (S500) for concentrating the filtrate extracted and removed indium and gallium and a processing step (S600) for producing a fertilizer or microbial nutrient from the concentrated filtrate as a raw material.

The pretreatment step (S100) is to improve the reactivity with the solvent in the dissolution and neutralization step (S200) to remove and neutralize the impurities, such as chloride, Fe, Cr, and heavy metals contained in the ammonium nitrate waste (S200), filtration In step (S300) to improve the filtration efficiency, in the extraction and removal of valuable metals (S400) as well as to improve the extraction efficiency and purity of the valuable metals, it is possible to improve the quality of the fertilizer finally produced.

In addition to the valuable metals such as indium and gallium contained in the ammonium nitrate waste, it contains impurities such as Cl, Na, K, and Ca. Among them, Cl interferes with filtration or heats dioxins in the acid leaching process. It is involved in the generation of toxic substances such as alkali metals such as Na and K, which have high solubility and are not easy to remove from the solution phase.Also, alkaline earth metal Ca increases acid consumption, thereby removing impurities, thereby improving process efficiency as described above. You can do it.

The impurities may be removed through a simple washing process, but preferably, 1 to 2N sodium hydroxide at a concentration of 9 to 11 and agitated for 10 to 30 minutes while maintaining the pH at 9 to 11 to further improve the efficiency of removing impurities. You can.

In addition, the ammonium nitrate waste contains about 30 to 200 ppm of heavy metals such as iron (Fe) and chromium (Cr), and is formed by adding an alkaline solution to pH 3 to 4 to remove the heavy metal. Injecting a surfactant into the filtrate generated by the first pretreatment step (S110) and the first pretreatment step by filtering the precipitate to remove the iron-containing filtrate to form an aggregate adsorbed Cr and the remaining heavy metals and cold precipitation And a second pretreatment step S120 of filtering the precipitate to remove heavy metals.

In the first pretreatment step (S110), the alkali solution is introduced into the ammonium nitrate waste to pH 3 to 4 and maintained for 10 to 120 minutes to filter the resulting precipitate to remove the iron-containing precipitate. At this time, the alkaline solution is injected to pH 3 to 4, it is difficult to form a precipitate below pH 3, when the pH exceeds 4, the formation of the precipitate compared to the pH increase and the removal rate of the iron component is insignificant because of the process efficiency It is desirable not to deviate from the pH range.

In the second pretreatment step (S120), after removing the precipitate in the first pretreatment step, the surfactant is added to the remaining filtrate to form aggregates in which heavy metals are adsorbed on the micelle, and the precipitates are cooled and precipitated to filter the precipitates by Cr and Other heavy metals can be removed efficiently.

In this case, the surfactant may be any one of anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, and combinations thereof, More preferably, the heavy metal component of the cation effectively by the electrostatic attraction Anionic surfactants capable of easily adsorbing and agglomerating to precipitate and separate may be used.

The anionic surfactant is any one of a carboxylic acid salt (RCOO ^- M ⁺ ), a sulfonic acid salt (RSO 3 ^- M ⁺ ), a sulfate ester salt (ROSO 3 ^- M ⁺ ), a phosphate ester salt (RPO 3 ^- Na 2 ⁺ ), and a combination thereof. Specific examples include sodium dodecyl sulfate (SDS), ammonium lauryl sulfate (ALS), sodium lauryl ethylene sulfate (SLES), linear alkylbenzene Linear Alkylbenzene Sulfonate (LAS), Alpha-Olefin Sulfonate (AOS) Alkyl Sulfate (AS), Alkyl Ether Sulfate (AES), Sodium Alkane Sulfonate Sulfonate (SAS) and combinations thereof, but is not limited thereto. More preferably, sodium dodecyl sulfate (SDS) can be used.

The amount of the surfactant is added to have a S / M molar ratio of 6 to 10: 1. If the amount of the surfactant is less than the above range (less added), it is difficult to adsorb and separate heavy metals. If exceeded (if added a lot), the effect of adsorption and separation of heavy metals due to the increase in content is insignificant, and therefore it is preferable not to deviate from the above range in terms of process efficiency.

While reacting with the surfactant and injecting sodium hydroxide, the sludge is first filtered while maintaining pH 6 to 8, and the filtrate is cooled at 3 to 5 ° C. for 3 to 6 hours to cool and settle the aggregates adsorbed with heavy metals, followed by filtration. Let's go.

The surfactant may be performed for 6 hours to 15 hours from the time of the input to the filtration separation of the aggregates, and more preferably, the initial time of input (20% of the total reaction time from the start) of the total reaction time is 150 at 30 to 35 ° C. The mixture was stirred at 300 rpm to uniformly disperse the surfactant inside the filtrate, and firstly filtering impurity sludge while maintaining pH 6 to 8 while injecting sodium hydroxide, and stopping the stirring for more than 20% to 50% of the total reaction time. By standing still at room temperature (20-25 ° C), the heavy metal component is stably adsorbed to the micelles of the surfactant to have a time for forming aggregates, and the reaction time is over 50% to 3 ° C until the end point. The aggregates are cooled and precipitated. Preferably, the cooling settling process may be performed for 3 hours to 6 hours.

The aggregate containing the iron precipitate obtained in the first pretreatment step (S110) and the chromium and the heavy metal obtained in the second pretreatment step (S120) is obtained through a solid-liquid separation and a filtration process using an ion exchange resin. Through this, the quality of the fertilizer can be improved by minimizing the impurity content of the final product.

In addition, iron, chromium and heavy metals are obtained in the form of precipitates by dissolving micelles by dissolving and repeatedly washing with lukewarm water at 30 to 50 ° C. to separate and utilize iron, chromium and heavy metals from the obtained precipitates and aggregates. The flotation and separation of micelles can remove the sludge with suspended sludge and yield iron, chromium and heavy metals deposited on the bottom.

Dissolution and neutralization step (S200) is a step of dissolving and neutralizing ammonium nitrate waste from which impurities and heavy metals have been removed, and more specifically, after dissolving ammonium nitrate waste in nitric acid (HNO 3), pH 7-8 Ammonia (NH 3) is added until the solution is neutralized to form a solution in which nitric acid, ammonium ions, and valuable metals are dissolved.

When dissolving, 1 to 50 parts by weight of ammonium nitrate waste is added to 100 parts by weight of nitric acid (HNO 3), and dissolved by stirring for 1 to 24 hours at a temperature of 60 to 90 ° C., if the dissolution conditions are less than the above range, ammonium nitrate waste This may not be dissolved properly, and if it exceeds the above range, the removal rate of indium (In) and gallium (Ga) does not increase any more in proportion to the above range of the above condition, which may be uneconomical.

In the filtration step (S300), the dissolved and neutralized ammonium nitrate waste is filtered to separate the solid residue and the filtrate, and the filtration method is not limited as long as it can be separated into the filtrate (solid residue) and the filtrate. Directly, a filter press can be used.

A filter press is a pressurized filtration device which puts a substance to be filtered between filter cloths and applies a pressure to solid-liquid separation, and its operation method is well known and detailed description thereof will be omitted.

Solid-liquid separation step (S200) is carried out under filter cloth size 50 to 200 mesh, pressure 2 to 15 kgf / ㎠, it is excellent in solid-liquid separation efficiency under the filter cloth size and pressure conditions.

More specifically, if the filter cloth size exceeds 200 mesh, frequent clogging of the filter cloth occurs, the filtration efficiency is lowered. If the filter cloth size is less than 50 mesh, it is preferable that the resolution of the solid residue is lowered so as not to exceed the filter cloth size. .

In addition, when the pressure of the filter press is less than 2kgf / ㎠, the filtration efficiency is lowered, when the pressure exceeds 15 kgf / ㎠, it is difficult to expect to increase the solid-liquid separation efficiency according to the pressure increase, unnecessary power consumption is generated For this reason, it is preferable not to deviate from the said pressure range.

Valuable metal extraction and removal step (S400) is a step of extracting and removing indium (In) and gallium (Ga), the valuable metal contained in the filtrate by solvent extraction of the filtrate formed by the filtration step (S300).

The solvent extract may use any one or more of a trialkyl phosphine solvent, an oxime solvent, a phosphate solvent, and a combination thereof, and more specifically, di (2-ethylhexyl) phosphate (di (2-ethylhexyl) phosphate acid solvent, mono (2-ethylhexyl) phosphate acid solvent, hydroxynanylacetophenone oxime solvent, trialkyl Phosphine (trialkylphosphine) solvent, trioctylphosphine solvent, bis (2,4,4-xmflapxlfvpsxlf) phosphinic acid (Bis (2,4,4-trimethylpenthyl) phosphinic acid), di-2ethylhexyl Phosphonic acid (di-2ethyl hexyl phosphoric acid) solvent, 2-ethylhexyl phosphinic acid solvent, mono-2-ethylhexyl ester solvent, di -2,4,4-trimethyl pentylphosphinic acid solvent and di-2,4,4-trimethylpentyl mono Va'a-o spin acid can be selected from one or more (di-2,4,4-trimethyl penthyl monothiophosphinic acid) based solvent.

Preferably, the trialkylphosphine solvent is Cyanex 932 (Trialkylphosohine oxide) manufactured by SYTEK in the US, the oxime solvent Lix 973 (5-dodecyl-salicylad oxime) manufactured by Henkel, Germany, is used as a phosphoric acid solvent. SYTEK's D2EHPA (di (2-ethylhexyl) phosphate acid) can be used.

To 100 parts by weight of the filtered ammonium nitrate waste filtrate, 20 to 200 parts by weight of the solvent extract was added and stirred for 30 minutes to 2 hours at a speed of 500 to 1,500 rpm to extract indium (In) and gallium (Ga). Concentrates can be obtained and removed.

In this case, when the content and the stirring conditions of the solvent extract is less than the above range, there is a concern that indium (In) and gallium (Ga) may not be properly removed, if exceeded, indium (In) and gallium (Ga) in proportion to the excess range ) Removal rate no longer increases, which may be uneconomical.

The recovery of indium from the obtained concentrate was dissolved in an acid solution using an indium recovery facility, and immersed in an aluminum or zinc plate, which is a metal plate having an ionization tendency greater than indium, to recover indium. The acid solution used at this time may be used by selecting one or more of nitric acid, hydrochloric acid, hydrofluoric acid, sulfuric acid and acetic acid having a concentration of 3 to 7M.

The recovery of gallium may be carried out by using electrolytic sampling, wherein the electrolytic sampling process is carried out under a current density of 200 to 1,500 A / m 3 using an insoluble electrode plate such as SUS, and the pH of the electrolyte is 9 to 13, Preferably from 12 to 13 is preferred because the progress of the electrolysis can be easily.

Concentration step (S500) is a step of concentrating the concentration of ammonium nitrate contained in the filtrate to 20% or more by evaporating the filtrate from which indium and gallium is extracted and removed.

The concentrating step (S500) is to condense the evaporation concentrate formed through the first concentration step (S510) and the first concentration step (S510) to evaporate the filtrate from which the indium and gallium is extracted and removed by electrodialysis 2 Tea concentration step (S520) is included.

The first concentration step (S510) is a step of concentrating ammonium nitrate by first injecting the filtrate from which indium and gallium have been extracted and removed into an evaporator, where the concentration of ammonium nitrate contained in the filtrate is greater than that of the filtrate. 20 to 40% higher.

At this time, in the first concentration step (S510) is concentrated 12 hours to 36 hours under the evaporator concentrator temperature 60 to 150 ℃, it is difficult to obtain a high concentration of ammonium nitrate relative to the unit volume below the temperature and time, the temperature and time If exceeded, it is preferable that a high temperature degeneration of the filtrate occurs or the effect of concentration with increasing temperature and time is insignificant so that a large amount of energy is consumed so as not to deviate from the above range.

The secondary concentration step (S520) is a step of secondary concentration of the evaporated concentrate formed by the first concentration step (S510) using electrodialysis, the concentration of ammonium nitrate less than 10% by the above process fertilizer It can be concentrated to have more than 20% suitable for use in.

At the time of electrodialysis, the ion exchange resin may be a cation exchange resin, and preferably, a cation exchange resin having a membrane resistance of 0.5 to 3.5 Pa · cm 2 may be used. Specific examples thereof include CMX ^® , CM-1 ^® , Any of Selemin CMV ^® and combinations thereof can be used.

In the processing step (S600), the concentrated filtrate is used as a raw material to prepare a fertilizer or a microbial nutrient, and the ammonium nitrate filtrate is prepared as a fertilizer based on the fertilizer process standard (Rural Development Administration Notification No. 2013-5, 2013214). Urea (Urea Ammonium Nitrate) fertilizer by mixing Ures and water, or by adding P (phosphate) and minerals (K, Ca, Mg) as a nutrient for microorganisms for waste water purification Applicable

On the other hand, compound fertilizer refers to a fertilizer containing two or more components of the three elements of fertilizers, there are four types of compound fertilizer in the process standard. The fourth type is a compound fertilizer of liquid, hydrating and water soluble, and refers to fertilizer manufactured by mixing refined ammonium nitrate with minerals, potassium and phosphorus. . The main demand is for nutrient farms and foliar application costs.

And UAN (Urea Ammonium Nitrate) fertilizer is a liquid fertilizer mixed with urea (Urea) and ammonium nitrate generally defines a liquid fertilizer having a nitrogen concentration of 28% to 32%.

Here, the manufacturing content of the compound fertilizer, the production content of the UAN fertilizer and the content of TN and P are very variable depending on the fertilizer process standards, UAN fertilizer product specifications, the use environment, the purpose of use, the amount of use of the fertilizer or nutrients in particular its content It does not limit, it can be applied to a variety of standards and contents already known.

Hereinafter, as another embodiment for achieving the above object, the urea-ammonium nitrate mixed fertilizer of the present invention is characterized in that is prepared by mixing the ammonium nitrate and urea obtained by the above-mentioned recycling method of ammonium nitrate waste, The description thereof will be omitted as described above.

Hereinafter, the present invention will be described in detail with reference to a preferred embodiment. However, the following Example is for illustrating this invention concretely, It is not limited only to this.

1. Pretreatment of Ammonium Nitrate Waste

The raw material (ammonium nitrate waste) was supplied by a company that produces waste ammonium nitrate in Gumi and Gyeongbuk. The nitrogen concentration, water and heavy metal content are shown in Table 1 below.

Most of the raw materials were in the form of waste liquor and sludge, and the pH was found to contain 3.5-12.5, 200-300 rpm indium, and 250-350 ppm gallium. In addition, impurities such as Ca and Na were also included, and other metals were insignificant or hardly detected.

1-1. Fe condition removal condition setting by pH adjustment

Samples of five companies were mixed at a ratio of 1: 1: 1: 1: 1 and then experimented. The pH of the raw material was found to be 2.2, and the Fe content was analyzed by ICP-OES according to the pH. Figure 2 is a graph showing the concentration change of iron ions according to (a) ICP-OES results and (b) pH in the pretreatment step (S100) according to the present invention. As a result, the lower the pH, the higher the Fe content, but was found to remove about 20% at pH 3, about 45% at pH 3.5, and at least 90% at pH 4.0. Since pH 4.0, there was no significant change in removal rate. The reason for this is that under low pH conditions, most of them are present in the form of Fe3 +, and as the pH increases, Fe3 + reacts with the hydroxyl group and thus is removed in the form of precipitate.

1-2. Heavy metals by cooling precipitation method using SDS ( Cr ) Removal

The amount of SDS added to the waste ammonium nitrate solution was administered using the S / M ratio, that is, the molar ratio of surfactant / metal, for the synthetic wastewater and the single element solution. SDS-injected wastewater was adjusted to pH 7 using NaOH to remove sludge firstly using general filter. The filtrate was refrigerated at 4 ° C. for about 5 hours to induce cold settling of SDS. Due to the decrease in solubility at low temperatures, the eluted SDS is aggregated and precipitated into visible large masses. At this time, the heavy metals are adsorbed around the hydrophilic group of micelles composed of SDS, so they coagulate and precipitate together. When this is filtered using MF, most heavy metals are not filtered and remain on the sludge and are removed. SDS remaining in the filtrate was adsorbed and removed using an anion exchange resin (Amberlite IRA420). S / M ratio was 2, 4, 6, 8, and 10, respectively.

Figure 3 is a graph showing the (a) chromium content ICP-OES results and (b) chromium removal efficiency according to S / M in the pretreatment step (S100) according to the present invention, Cr is removed as the S / M ratio increases This was improved. The S / M ratio was removed from 2 to 52.5%, and the S / M ratio was removed from 4 to 78%. S / M ratio of 6 to 10 showed more than 96% higher removal efficiency, but S / M ratio is the most effective at 6 in terms of efficiency.

2. Dissolution and Filtration Steps

25 g of ammonium nitrate waste was added to 100 g of nitric acid (HNO 3) solution, stirred at 65 ° C. for 12 hours to dissolve, and neutralized to pH 7-8 by adding ammonia (NH 3). The dissolved and neutralized ammonium nitrate waste was separated into a solid residue and a filtrate using a filter press. At this time, the filter press was used as JDFP-4.1-MA model plate size of 790 * 800 mm, Chamber volume 4,100ℓ / cycle, hourly processing speed 1.5 Ton / Hr standard. Filter pore size was carried out under 50 to 200 mesh, pressure 10 ~ 15 kgf / ㎠.

3. Valuable metal extraction and removal step

In order to select a solvent for extracting indium, as shown in Table 2 below, the indium extraction efficiency of the solvent Cyanex-923, Lix-84I, D2EHPA, PC-88A was confirmed. In was used to have a concentration of 1500mg / kg, the reaction and stirring (500rpm) time was 30 minutes, the ratio of A / O was 1.

As a result, it was confirmed that D2EHPA was most suitable as an extraction solvent for selectively extracting In.

In order to confirm a suitable mixing ratio of the extraction solvent D2EHPA, the mixing ratio was selected as shown in Table 3 below, and the indium extraction efficiency was confirmed.

 In was used having a concentration of 1500mg / kg, had a reaction and stirring (500rpm) time of 30 minutes, settling time of 30 minutes.

As a result, it was confirmed that the extraction amount of indium increases as the content of the extraction solvent increases, and when the extraction solvent is added to 50 parts by weight or more relative to 100 parts by weight of the filtrate, it was confirmed that the extraction is more than 90%.

4. Concentration step

4-1. Evaporation

Treatment capacity is 200 liter / hr, 1300W * 3000D * 500H of square type, Teflon coating, stainless steel 304 SUS acid-proof material, and evaporative concentration is carried out using evaporative concentrator equipped with 10 electric heaters of 5kW / h. It was. Figure 4 shows the evaporation concentration equipment applied in the concentration step (S500) according to the present invention.

The temperature of the evaporator was controlled at 90 to 110 ° C. and concentrated for 14 hours to increase the concentration of ammonium nitrate in the filtrate from 3% to 9%.

4-2. Optimal condition of ion exchange membrane for high concentration concentration

To be used as fertilizer, it needs to be concentrated at high concentration of 20% or more. Accordingly, the selectivity of the ion exchange membranes was measured according to the concentration change, and the procedure was performed to select an ion exchange membrane effective for high concentration concentration. As the cation exchange membrane, the selectivity of the ion exchange membrane was compared with the concentration of NaCl for Neosepta CMX, Tokuyama Soda Co (CM-1) and Selemion CMV (Asahi Glass Co).

Table 4 below shows the properties of the cation exchange membrane.

5 is a graph showing the selectivity of the ion exchange membrane. The selectivity was found to decrease with increasing NaCl concentration. Among the membranes used in the experiment, ion selectivity was found in the order of CMX> CM-1> CMV.

4-3. Concentration of Ammonium Nitrate by Electrodialysis

It was evaluated whether the electrodialysis process was effective to concentrate ammonium nitrate above 20%. Electrodialysis was carried out using CMX ion exchange resin, 2L of 8% ammonium nitrate solution was added to the dilution tank, and electrodialysis was performed at each concentration while changing the concentration of ammonium nitrate in the concentration tank by 15, 20, 25, 30, 35%. The current efficiency according to the concentration change of the concentration tank was measured.

Figure 6 shows a graph showing the electrodialysis efficiency, the results obtained by evaluating the average current efficiency of 1 hour through the results of electrodialysis experiments at each concentration, the electrical efficiency is increased from 15% to 35% concentration of the concentration tank They decreased to 97.1, 93.2, 92.0, 90.1, 89.9, and 88.0%, respectively. Based on the results of previous studies, it is known that it does not affect the process at around 90%. Therefore, it was expected that an ammonium nitrate concentrate of 30% or more could be obtained by concentrating by electrodialysis using the CMX membrane used in this experiment.

Based on the above results, the concentrated filtrate having an ammonium nitrate concentration of 9% according to the present embodiment was subjected to electrodialysis using a CMX membrane to obtain a concentrated filtrate having an ammonium nitrate concentration of 23% (Fig. 7 (a)), the addition of urea and distilled water to the concentrated filtrate without the additional impurities removal and concentration process to meet the UAN product standard only to be prepared as a UAN fertilizer was able to confirm the availability as a fertilizer (Fig. 7 shown in (b)).

As described above, the present invention has been described with reference to the accompanying drawings. However, those skilled in the art to which the present invention pertains do not depart from the spirit and scope described in the claims of the present invention. In the present invention can be carried out by various modifications or variations. Therefore, the scope of the invention should be construed by the claims described to include examples of many such variations.

Claims (7)

In the recycling method of ammonium nitrate waste,
A pretreatment step (S100) of removing impurities and heavy metals from the ammonium nitrate waste; and
Dissolving and neutralizing step of dissolving and neutralizing ammonium nitrate waste from which impurities and heavy metals have been removed (S200);
Filtration step (S300) for filtering the dissolved and neutralized ammonium nitrate waste; And
Valuable metal extraction step (S400) for extracting the filtered ammonium nitrate waste filtrate solvent to extract indium (In) and gallium (Ga) as valuable metals; and
Concentrating step of concentrating the filtrate extracted indium and gallium (S500); And
Characterized in that it comprises a processing step (S600) of manufacturing a fertilizer or microbial nutrient from the concentrated filtrate as a raw material
Method for recycling ammonium nitrate waste.
The method of claim 1,
The pretreatment step (S100)
A first pretreatment step (S110) of filtering the precipitate formed by adding an alkaline solution to pH 3 to 4 to the ammonium nitrate waste to remove the filtrate containing iron;
Including a second pretreatment step (S120) for removing the heavy metals by adding a surfactant to the filtrate generated by the first pretreatment step to form agglomerates in which heavy metals are adsorbed, and filtering the precipitate after cooling and settling.
Method for recycling ammonium nitrate waste.
The method of claim 1,
The dissolution and neutralization step (S200)
1 to 50 parts by weight of ammonium nitrate waste was added to 100 parts by weight of nitric acid (HNO 3), stirred for 1 to 24 hours to dissolve at a temperature of 60 to 90 ° C., and then neutralized to pH 7 to 8 by adding ammonia (NH 3). Characterized by
Method for recycling ammonium nitrate waste.
The method of claim 1,
The valuable metal extraction step (S400) is
To 100 parts by weight of the filtered ammonium nitrate waste filtrate, 20 to 200 parts by weight of a solvent alone or used in combination of two or more of trialkylphosphine solvent, oxime solvent or phosphate solvent was added and 30 at a speed of 500 to 1,500 rpm. Stirring for 2 minutes to 2 hours to obtain and remove the concentrated solution extracted indium (In) and gallium (Ga), characterized in that
Method for recycling ammonium nitrate waste.
The method of claim 1,
The concentration step (S500) is
A first concentration step (S510) of evaporating and concentrating the filtrate from which indium and gallium are extracted; and
Characterized in that it comprises a; secondary concentration step (S520) for concentrating the evaporated concentrate using electrodialysis
Method for recycling ammonium nitrate waste.
The method of claim 7, wherein
The second concentration step (S520) is
In electrodialysis, the ion exchange resin is characterized by using any one of cation exchange resins CMX ^® , CM-1 ^® , Selemin CMV ^® and combinations thereof
Method for recycling ammonium nitrate waste.
A urea-ammonium nitrate mixed fertilizer comprising ammonium nitrate obtained by the method for recycling the ammonium nitrate waste of any one of claims 1 to 6.

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