Method for preparing phosphoric acid and aluminum sulfate by using acid wastes and waste aluminum

Abstract

This method for preparing phosphoric acid and aluminum sulfate by using acid wastes and waste aluminum may comprise the steps of: dissolving the waste aluminum in the acid wastes; collecting hydrogen gas generated during the dissolution; filtering a dissolution solution, in which the waste aluminum is dissolved, thereby separating out aluminum phosphate; removing impurities from a mixed solution in which a sulfuric acid aqueous solution and the aluminum phosphate are added to a solution remaining after the filtration; converting the collected hydrogen gas into electric energy; using the electric energy to distill the mixed solution, thereby separating out phosphoric acid; and recovering a material remaining after the phosphoric acid separation, and separating out aluminum sulfate.

Description

Method for producing phosphoric acid and aluminum sulfate using waste acid and aluminum waste metal

[0001] This relates to a method for producing phosphoric acid and aluminum sulfate using waste acid and aluminum waste metal.

[0002] The metal surface treatment industry uses large quantities of toxic substances and chemicals, resulting in wastewater containing heavy metal ions, hazardous substances, phosphorus, and various salts. Previous treatment methods for this metal surface treatment industry were limited to removing heavy metals and hazardous substances, requiring significant facility investment, operation, and maintenance costs. Highly acidic wastewater is first neutralized by raising the pH, and additional chemicals are used to induce salt precipitation, incurring significant costs. The final concentrated sludge is then entrusted to specialized waste management companies for landfill or incineration. The purified water is then discharged into rivers, causing additional environmental pollution. This process is unecologically unproductive and inefficient. Furthermore, while much of the metal waste is recycled, recycling requires significant energy and contributes to further environmental pollution.

[0003] One aspect of the present disclosure provides a method for producing phosphoric acid and aluminum sulfate, which can reduce waste disposal costs by recovering high value-added byproducts from wastewater generated in a surface treatment process and metal waste generated in various metal product manufacturing processes.

[0004] One aspect of the present disclosure is to provide an economical and environmentally friendly method for producing phosphoric acid and aluminum sulfate, which can recycle a portion of waste that was previously landfilled or incinerated by using aluminum scrap metal that is difficult to recycle, and which does not require a separate energy source or chemical by using hydrogen gas and aluminum phosphate generated during the process.

[0005] The technical problems to be achieved in this document are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0006] A method for producing phosphoric acid and aluminum sulfate using waste acid and aluminum waste metal according to one embodiment of the present disclosure may include the steps of dissolving the aluminum waste metal in the waste acid, capturing hydrogen gas generated during the dissolution, filtering the solution in which the aluminum waste metal is dissolved to separate aluminum phosphate, removing impurities from a mixture obtained by adding a sulfuric acid aqueous solution and the aluminum phosphate to the solution remaining after the filtering, converting the captured hydrogen gas into electric energy, distilling the mixture using the electric energy to separate phosphoric acid, and recovering a material remaining after the separation of the phosphoric acid to separate aluminum sulfate.

[0007] Additionally, the above-mentioned waste acid may include sulfuric acid and phosphoric acid.

[0008] Additionally, the above-mentioned waste acid may contain 65 to 85 wt% phosphoric acid and 15 to 35 wt% sulfuric acid.

[0009] In addition, the above dissolution can be performed under conditions of pH 1.0 to 5.0 and a temperature of 50°C or higher and less than 100°C.

[0010] Additionally, the purity of the hydrogen gas may be 99% or higher.

[0011] In addition, the filter for the primary filtration may be at least one selected from among nonwoven fabrics, woven fabrics, and knitted fabrics having pores of 30 to 50 mesh.

[0012] In addition, in the secondary filtration, the filter may be at least one selected from among nonwoven fabrics, woven fabrics, and knitted fabrics having a pore size of 5 to 15 ㎛.

[0013] In addition, the material of the filter during the first and second filtration may include at least one selected from polypropylene, polyethylene, polyester, polyurethane, polyester, polyamide, glass fiber, and fluorine.

[0014] Additionally, the above sulfuric acid aqueous solution may contain 20 to 40% sulfuric acid.

[0015] Additionally, the above sulfuric acid aqueous solution may be included in a weight ratio of 1:0.1 to 20.0 with respect to aluminum phosphate.

[0016] Additionally, the above electrolytic treatment can be performed by flowing a current of -1.66 eV or less.

[0017] In addition, the above distillation can be performed by heating at a temperature higher than the boiling point of phosphoric acid (158°C) and lower than the boiling point of sulfuric acid (338°C), and then lowering the temperature to 60 to 70°C, which is lower than the boiling point of phosphoric acid.

[0018] In addition, the above distillation can be performed by heating at a temperature higher than the boiling point of phosphoric acid (158°C) and lower than the boiling point of sulfuric acid (338°C) until the yield of phosphoric acid becomes 70%, reducing the pressure to 760 mmHg, heating at 60 to 100°C until the yield of phosphoric acid becomes 99% or more, and then lowering the temperature to 60 to 70°C, which is lower than the boiling point of phosphoric acid.

[0019] Additionally, the purity of the above phosphoric acid may be 99% or higher.

[0020] A water treatment agent according to one embodiment of the present disclosure may include the prepared aluminum sulfate.

[0021] According to the idea of ​​the present disclosure, phosphoric acid and aluminum sulfate, which are high value-added byproducts, can be recovered from wastewater generated in a surface treatment process and metal waste generated in various metal product manufacturing processes, thereby reducing waste disposal costs, and by using hydrogen gas and aluminum phosphate generated during the process, resources can be recycled without the need for a separate energy source or chemical, thereby providing an environmentally friendly method for manufacturing phosphoric acid and aluminum sulfate.

[0022] FIG. 1 is a drawing showing a process diagram for a method for producing phosphoric acid and aluminum sulfate from waste acid and aluminum waste metal according to one embodiment.

[0023] FIG. 2 is a diagram showing an SEM photograph of aluminum phosphate separated from waste acid and aluminum waste metal according to one embodiment.

[0024] FIG. 3 is a diagram showing the results of SEM EDS analysis of three areas (1, 2, 3 in FIG. 2) of aluminum phosphate separated from waste acid and aluminum waste metal according to one embodiment.

[0025] Figure 4 is a diagram showing the amount of hydrogen gas produced according to temperature and time during the reaction of waste acid and aluminum waste metal according to one embodiment.

[0026] Preferred embodiments of the present invention are described below. However, the embodiments of the present invention may be modified in various ways, and the technical concept of the present invention is not limited to the embodiments described below. Furthermore, the embodiments of the present invention are provided to more fully explain the present invention to those of ordinary skill in the art.

[0027] Preferred embodiments of the present invention are described below. However, the embodiments of the present invention may be modified in various ways, and the technical concept of the present invention is not limited to the embodiments described below. Furthermore, the embodiments of the present invention are provided to more fully explain the present invention to those of ordinary skill in the art.

[0028] The terminology used in this application is solely for the purpose of describing specific examples. Therefore, for example, singular expressions include plural expressions unless the context clearly dictates otherwise. Additionally, it should be noted that terms such as "comprise" or "have" used in this application are used to clearly indicate the presence of features, steps, functions, components, or combinations thereof described in the specification, and are not used to preliminarily exclude the presence of other features, steps, functions, components, or combinations thereof.

[0029] Meanwhile, unless otherwise defined, all terms used herein should be considered to have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Therefore, unless explicitly defined herein, specific terms should not be interpreted in an overly idealistic or formal sense. For example, singular expressions herein include plural expressions unless the context clearly indicates otherwise.

[0030] In addition, the terms "about", "substantially", etc. in this specification are used in the sense of or close to the numerical value when manufacturing and material tolerances inherent to the meanings mentioned are presented, and are used to prevent unscrupulous infringers from unfairly using the disclosure contents in which exact or absolute numerical values ​​are mentioned to aid in the understanding of the present invention.

[0031] In general, metal surface treatment is performed for the purpose of providing functions such as corrosion prevention, color and gloss improvement, hardness, wear resistance, and heat resistance, and the types of metal surface treatment include plating, chemical treatment, anodization, painting, lining, surface hardening, and coating. Among these, anodizing is a process in which a metal or part is placed on an anode and electrolyzed in a dilute acid electrolyte, and an oxide film with excellent adhesion to the base metal is formed by the oxygen generated at the anode. The representative material for anodizing is aluminum (Al), and anodizing is also performed on other metal materials such as magnesium (Mg), zinc (Zn), titanium (Ti), tantalum (Ta), hafnium (Hf), and niobium (Nb).

[0032] This anodizing film treatment process is a degreasing process that removes oils such as cutting oil and tapping oil that remain during processing by immersing the metal in a neutral detergent with a pH of 7-9 and a weak alkaline solution at 30-40℃ for about 20-30 minutes, a washing process to remove foreign substances or stains after degreasing, an etching process that immerses the metal in a 10% sodium hydroxide solution at 60-70℃ for about 1 minute to remove oil and oxide films on the metal surface, a washing process to remove foreign substances or stains after etching, a chemical polishing process to improve the gloss of the product surface, a washing process to remove foreign substances or stains after chemical polishing, a desmutting process that neutralizes and removes smut using a chemical mixture of water and nitric acid (HNO3) in a 1:1 ratio, and a chemical treatment using sulfuric acid with a concentration of 15-20%. The anodizing process, a washing process to remove sulfuric acid from the product, a coloring process to obtain the desired color of the product, and a sealing process as a finishing process may be included.

[0033] Among the anodic oxidation film treatment processes, wastewater generated during processes such as anodizing, plating, etching, and desmutting can be used as the waste acid of the present invention.

[0034] Additionally, aluminum metal waste applied to devices such as mobile phones, TVs, notebooks, various machines, and construction equipment can be used as the aluminum waste metal of the present invention.

[0035] Below, a method for producing phosphoric acid and aluminum sulfate using waste acid and aluminum waste metal is described in detail.

[0036] A method for producing phosphoric acid and aluminum sulfate using waste acid and aluminum waste metal according to one disclosed embodiment may include the steps of dissolving the aluminum waste metal in the waste acid, capturing hydrogen gas generated during the dissolution, filtering the solution in which the aluminum waste metal is dissolved to separate aluminum phosphate, removing impurities from a mixture obtained by adding a sulfuric acid aqueous solution and the aluminum phosphate to the solution remaining after the filtering, converting the captured hydrogen gas into electric energy, distilling the mixture using the electric energy to separate phosphoric acid, and recovering a material remaining after the separation of the phosphoric acid to separate aluminum sulfate.

[0037] Hereinafter, a method for producing phosphoric acid and aluminum sulfate using waste acid and aluminum waste metal of the present invention is described in detail.

[0038] First, the waste acid and aluminum waste metal are dissolved.

[0039] The above-mentioned waste acid and aluminum waste metal can be used as waste water generated from a surface treatment process, for example, waste acid generated during the anodic oxidation film treatment process described above, and aluminum metal waste applied to various devices.

[0040] In order to manufacture phosphoric acid and aluminum sulfate using the above waste acid, a waste acid containing phosphoric acid and sulfuric acid can be used, and specifically, a waste mixed acid of 65 to 85 wt% phosphoric acid and 15 to 35 wt% sulfuric acid can be used.

[0041] Conventionally, aluminum scrap metal generated during metalworking processes is difficult to recycle due to its assembly with polymer compounds such as plastics and glass fibers. However, the present invention utilizes aluminum scrap metal generated during the metalworking process and separates phosphoric acid and aluminum sulfate from it, thereby enabling efficient recycling of the aluminum scrap metal.

[0042] When dissolving aluminum scrap metal in the above-mentioned waste acid, since the dissolution reaction may not occur well due to Al2O3 on the surface of the aluminum scrap metal, it is preferable that the dissolution be carried out for 50 to 180 minutes under the conditions of pH 1.0 to 5.0 and a temperature of 50°C to 100°C, preferably 60 to 90°C. That is, the pH of the waste acid is adjusted to 1.0 to 5.0, and the dissolution is carried out at a temperature of 50°C to 100°C so that the dissolution reaction on the surface of the aluminum scrap metal proceeds smoothly.

[0043] When the pH and temperature during the dissolution are within the above ranges, the aluminum scrap metal can be maximally dissolved in the waste acid, so it is desirable to maintain them within the above ranges. In addition, when the pH and temperature during the dissolution are outside the above ranges, the dissolution reaction on the surface of the aluminum scrap metal does not occur well, so the redox reaction between the waste acid and the aluminum scrap metal does not proceed smoothly, and thus the separation of the desired hydrogen gas and aluminum phosphate may be difficult.

[0044] In addition, if the dissolution time is less than 50 minutes, the oxidation-reduction reaction between the waste acid and the aluminum waste metal may not be sufficient to proceed, and if it exceeds 180 minutes, the separation efficiency of hydrogen and aluminum phosphate may decrease with respect to the time.

[0045] When waste acid and aluminum waste metal are dissolved under the temperature and pH conditions described above, a redox reaction occurs between the waste acid and aluminum waste metal as shown in the following reaction formula 1, thereby obtaining a hydrogen and metal salt solution.

[0046] Scheme (1): 2H3PO4(l)+H2SO4(l)+2Al(s) → 2AlPO4(s)+H2SO4(l)+3H2(g)

[0047] Redox reactions occur through the exchange of electrons between reactants. Oxidation refers to the loss of electrons, while reduction refers to the gain of electrons. Each metal exhibits a different tendency to lose electrons and become oxidized. This tendency is referred to as the metal's reactivity. A comparison of the reactivity of representative metals is as follows.

[0048] K > Ca > Na > Mg > Al > Zn > Fe > Ni > Sn > Pb > H > Cu > Hg > Ag > Pt > Au

[0049] Here, aluminum, which is more reactive than hydrogen and has a greater tendency to ionize, reacts with the waste acid and is oxidized, losing electrons to form a metal salt, and when hydrogen is reduced by receiving electrons from aluminum, hydrogen gas is generated.

[0050] That is, when aluminum waste metal is dissolved in waste acid, hydrogen gas (H2) in a gaseous state is generated through a redox reaction, and a solution containing aluminum phosphate salt can be obtained.

[0051] At this time, the hydrogen gas may have a purity of 99% or higher. The remaining elements in the gas, excluding hydrogen, may be general atmospheric components such as nitrogen, oxygen, argon, and carbon dioxide. Hydrogen with a purity of 99% or higher can reduce separation costs compared to lower-purity hydrogen, increase the output of fuel cells used in hydrogen utilization, and lower the failure rate of hydrogen-utilizing machinery, thereby promoting efficient machine operation.

[0052] Additionally, the hydrogen gas can be converted into electrical energy and used as an energy source for subsequent phosphoric acid separation.

[0053] Typically, to convert hydrogen into electrical energy, a hydrogen fuel cell is used. When hydrogen enters the hydrogen fuel cell stack, a catalyst inside the stack causes the hydrogen to react with external oxygen, and the electrons generated here are used to convert it into electrical energy.

[0054] That is, the separated hydrogen gas can be captured and converted into electrical energy using a hydrogen fuel cell as described above, and then used as an energy source for heat treatment in a phosphoric acid manufacturing process. Therefore, it is an environmentally friendly method in that it utilizes a by-product produced during the process of the present invention without the need for a separate energy source, and has the effect of reducing costs.

[0055] In addition, the aluminum phosphate salt dissolved in the above solution is in a combined form with polymer compounds such as plastic and glass fiber, and cannot be said to be in the form of pure aluminum phosphate due to the combined polymer compounds.

[0056] Accordingly, after the above dissolution, the solution in which the aluminum phosphate salt is dissolved can be filtered to separate pure aluminum phosphate (Al2PO4) in a solid state.

[0057] The above filtration can be performed as a primary filtration to separate high molecular compounds and a secondary filtration to separate aluminum phosphate.

[0058] The above primary filtration is performed to remove high molecular weight compounds combined with aluminum phosphate salt, and filters such as filter paper and sieves that are commonly used to remove impurities can be used.

[0059] Specifically, the above primary filtration can use a filter such as a non-woven fabric, fabric, or knitted fabric having a porosity of 30 to 50 mesh, and the material can be polypropylene, polyethylene, polyester, polyurethane, polyester, polyamide, glass fiber, or fluorine that does not react with acid.

[0060] If the porosity of the above primary filtration filter is less than 30 mesh, it may be difficult to separate the polymer compound, and if it exceeds 50 mesh, not only the polymer compound to be separated but also metal salt components may pass through the filter and be separated.

[0061] The solution from which the polymer compound has been separated through the primary filtration filter is then subjected to a secondary filtration to separate the aluminum phosphate.

[0062] The above secondary filtration can be performed using a filter such as a non-woven fabric, fabric, or knitted fabric with a pore size of 5 to 15 ㎛, and the material can be polypropylene, polyethylene, polyester, polyurethane, polyester, polyamide, glass fiber, or fluorine that does not react with acid.

[0063] If the pore size of the secondary filtration filter is less than 5㎛, it may be difficult to separate aluminum phosphate, and if it exceeds 15㎛, it may not be possible to separate pure aluminum phosphate.

[0064] Next, impurities are removed from the mixture obtained by adding sulfuric acid aqueous solution and aluminum phosphate to the solution remaining after the above filtration.

[0065] Aluminum sulfate, manufactured from waste acid and aluminum waste metal according to the present invention, is typically used as a water treatment agent. The higher the aluminum content in the aluminum sulfate, the greater its value as a water treatment agent. Furthermore, to recycle the manufactured phosphoric acid, it must be separated from all impurities.

[0066] Accordingly, when the previously separated aluminum phosphate and sulfuric acid aqueous solution are added to the remaining solution after separation of aluminum phosphate and reacted, the aluminum combined with phosphoric acid is dissolved by sulfuric acid, and the dissolved aluminum combines with sulfuric acid, as shown in the following reaction formula 2. Then, when the temperature is raised above the boiling point of phosphoric acid, only pure phosphoric acid can be recovered.

[0067] Reaction formula (2): 2AlPO4(s)+3H2SO4(l)+H2O(l)→Al2(SO4)3(s)+2H3PO4(l)+H2O(l)

[0068] The sulfuric acid aqueous solution used at this time may be an aqueous solution containing 20 to 40 wt% sulfuric acid. Furthermore, from the perspective of resource recycling, a waste film refining solution containing 20 to 40 wt% sulfuric acid may be used as the sulfuric acid aqueous solution. If the sulfuric acid content is less than 20 wt%, aluminum may not be properly separated from aluminum phosphate, or the value of the aluminum sulfate produced thereafter as a water treatment agent may be reduced.

[0069] The mixing ratio of the solution remaining after the above filtration, aluminum phosphate, and sulfuric acid aqueous solution is not specifically limited, but since the higher the concentration of sulfuric acid, the better the performance of aluminum sulfate as a water treatment agent, it is preferable to add as much sulfuric acid aqueous solution as possible. Specifically, it is preferable that the sulfuric acid aqueous solution is included in a weight ratio of 1:0.1 to 20.0 with respect to aluminum phosphate, and more preferably, it is included in a weight ratio of 1:0.5 to 4.0.

[0070] If the weight of aluminum sulfate compared to the aluminum phosphate is outside the above range, aluminum may not be separated from the aluminum phosphate well, or the value of the aluminum sulfate produced thereafter as a water treatment agent may be reduced.

[0071] By removing impurities from the solution remaining after the above filtration, a mixture of aluminum phosphate and sulfuric acid aqueous solution can be produced, high-purity phosphoric acid and aluminum sulfate suitable for water treatment agent specifications.

[0072] Specifically, an electrode is added to the above mixture, and a current below the standard potential electrode of aluminum is applied to electrolyze the impurities.

[0073] By adding an insoluble electrode to the above mixture and using it as an anode, and applying a current below -1.66 eV, which is the standard potential electrode of aluminum, impurities such as metals with a lower standard potential electrode than aluminum, such as iron, arsenic, manganese, lead, cadmium, mercury, and chromium, are precipitated at the cathode.

[0074] The mixture from which impurities have been removed can then be distilled to separate high-purity phosphoric acid.

[0075] At this time, the distillation can utilize electric energy converted from hydrogen gas separated during the previous production of aluminum phosphate, and the method of converting hydrogen gas into electric energy can be performed according to a conventional method using a hydrogen fuel cell as described above.

[0076] The above distillation can be performed by heating at a temperature higher than the boiling point of phosphoric acid but lower than the boiling point of sulfuric acid, and then lowering the temperature to below the boiling point of phosphoric acid. The boiling point of phosphoric acid can be lowered or raised by adjusting the pressure as needed. That is, it is preferable that the above mixture be heated at a temperature higher than the boiling point of phosphoric acid (158°C) but lower than the boiling point of sulfuric acid (338°C), and then lowered to a temperature of 60 to 70°C, which is lower than the boiling point of phosphoric acid.

[0077] Specifically, the mixture is heated using electric energy converted from hydrogen gas to a temperature higher than the boiling point of phosphoric acid (158°C) and lower than the boiling point of sulfuric acid (338°C). At this time, distillation can be carried out by continuously heating to a temperature higher than the boiling point of phosphoric acid, but in order to save electric energy consumed during heating, heating can be carried out to a temperature higher than the boiling point of phosphoric acid but lower than the boiling point of sulfuric acid until the yield of phosphoric acid becomes 70%, and then the pressure can be reduced to 760 mmHg or lower to adjust the boiling point of phosphoric acid to 60 to 100°C, and then heating can be carried out until the yield of phosphoric acid becomes 99%. As described above, gaseous phosphoric acid (H3PO4) and water vapor (H2O) are generated through distillation.

[0078] Next, the gaseous phosphoric acid can be separated into liquid phosphoric acid by lowering the temperature to 60-70°C, which is below the boiling point of phosphoric acid, without reducing the pressure. If the temperature and time during the phosphoric acid separation are outside the above range, the separation of aluminum sulfate may not occur smoothly.

[0079] Phosphoric acid separated in this way can be separated into high purity phosphoric acid with a purity of 99% or more because only water and phosphoric acid are vaporized when distilled by heating.

[0080] Finally, the solid material remaining after the above phosphoric acid separation is recovered as the final aluminum sulfate.

[0081] As described above, solid aluminum sulfate (Al2(SO4)3) separated from waste acid and aluminum waste metal can be used as a water treatment coagulant, and phosphoric acid (H3PO4) can be reused as a chemical for chemical processes such as semiconductor etching solution and surface treatment.

[0082] Hereinafter, a method for producing phosphoric acid and aluminum sulfate using waste acid and aluminum waste metal will be described with reference to drawings.

[0083] FIG. 1 is a drawing showing a process diagram for a method for producing phosphoric acid and aluminum sulfate from waste acid and aluminum waste metal according to one embodiment.

[0084] Referring to FIG. 1, a method for producing phosphoric acid and aluminum sulfate from waste acid and aluminum waste metal according to one embodiment may include the steps of dissolving the aluminum waste metal in the waste acid, capturing hydrogen gas generated during the dissolution, filtering the solution in which the aluminum waste metal is dissolved to separate aluminum phosphate, removing impurities from a mixture obtained by adding a sulfuric acid aqueous solution and the aluminum phosphate to the solution remaining after the filtering, converting the captured hydrogen gas into electric energy, distilling the mixture using the electric energy to separate phosphoric acid, and recovering a material remaining after the separation of the phosphoric acid to separate aluminum sulfate.

[0085] According to the present invention as described above, phosphoric acid and aluminum sulfate, which are high value-added by-products, can be recovered from wastewater generated in a surface treatment process and metal waste generated in various metal product manufacturing processes, thereby reducing waste disposal costs. In addition, by using hydrogen gas and aluminum phosphate generated during the process, recycling of resources is possible without the need for a separate energy source or chemicals, so it can be said to be an environmentally friendly method.

[0086] Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are intended only to illustrate the present invention and the scope of the present invention is not limited to these examples.

[0087] Example

[0088] A spent acid reaction solution was prepared by adding 92 mL of water to 58 mL of spent acid (pH 0.48) containing 80 wt% phosphoric acid and 30 wt% sulfuric acid to adjust the pH to 1.33. In this solution, aluminum waste metal containing polymer compounds of plastic and glass fiber (GF) was dissolved at a temperature of 80°C for 120 minutes.

[0089] At this time, the hydrogen generated by the reaction between the waste acid and the aluminum waste metal was captured separately, and the solution was first filtered using a nonwoven fabric with pores of 30 to 50 mesh to separate the polymer compound, and then second filtered using a polypropylene filter with a pore size of 5 to 15 ㎛ to separate the solid aluminum phosphate.

[0090] Next, a 30 wt% aqueous sulfuric acid solution was mixed with the remaining solution after the secondary filtration in a weight ratio of 1:2.5 to the separated solid aluminum phosphate. Then, an insoluble electrode was added to the mixture, and a current of -1.66 eV or lower was applied to electrolyze impurities such as iron, arsenic, manganese, lead, cadmium, mercury, and chromium.

[0091] The mixture from which the above impurities had been removed was heated at 158°C until the yield of phosphoric acid was 70% or more, then the pressure was reduced to 760 mmHg or less, the boiling point of phosphoric acid was adjusted to 100°C, and the mixture was heated until the yield of phosphoric acid was 99% or more, thereby separating gaseous phosphoric acid (H3PO4) and water vapor (H2O). Next, the gaseous phosphoric acid was cooled to 60°C, which is below the boiling point of phosphoric acid, to separate liquid phosphoric acid. At this time, the previously separated hydrogen was converted into electrical energy and used as an energy source for heating. The solid material remaining after separating the phosphoric acid was recovered to produce the final aluminum sulfate.

[0092] The SEM image of the separated aluminum phosphate is shown in Fig. 2, and the SEM EDS analysis results for three areas (1, 2, 3 in Fig. 2) of the aluminum phosphate in Fig. 2 are shown in Table 1 and Fig. 3 below. The unit in Table 1 is weight%.

[0093] Category COAlPS1 Zone 1.6564.1711.3515.647.192 Zone 2.8563.4511.0215.127.553 Zone 1.7063.7711.1915.677.67

[0094] As shown in Table 1 and FIGS. 2 and 3 above, it was confirmed that aluminum phosphate separated from waste acid and aluminum waste metal according to the present invention contains Al, P, S, and O as main components without impurities such as iron, arsenic, lead, cadmium, chromium, manganese, and mercury. Through these results, it was found that if aluminum sulfate is manufactured using the aluminum phosphate separated in this way, it will be suitable for use as a water treatment agent because it does not contain impurities.

[0095] In addition, the purity of the separated phosphoric acid was measured through ICP analysis, and it was found that the purity of the separated phosphoric acid was over 99% as only water and phosphoric acid were vaporized during distillation by heating.

[0096] In addition, the components of the solid aluminum sulfate remaining after phosphoric acid separation were analyzed using the titrimetric method (based on a dilution of 1 part sulfuric acid: 4 parts water) among the water treatment agent standard analysis methods, and the results are shown in Table 2 below. The measurement results in Table 2 are based on a dilution of 1 part sulfuric acid: 4 parts water, and are converted and shown as the conversion results.

[0097] The standards, specifications, and labeling standards for aluminum sulfate used as a water treatment agent are as shown in Table 3 below.

[0098] Test item measurement results (dilution) conversion results H2SO4(%) 12.97% 64.85% Al2O3(%) 1.77% 8.85%

[0099] This product is a colorless to light yellow-brown transparent liquid. Identification test It must be suitable when tested according to the identification test method. pH 3.0 or more Insoluble matter - Aluminum oxide (Al2O3) 8.0% or more Ammonia nitrogen (NH3-N) 0.01% or less Iron (Fe) 0.3% or less Arsenic (As) 10 mg / kg or less Lead (Pb) 10 mg / kg or less Cadmium (Cd) 2 mg / kg or less Chromium (Cr) 10 mg / kg or less Manganese (Mn) 25 mg / kg or less Mercury (Hg) 0.2 mg / kg or less

[0100] As shown in Table 2 above, it was confirmed that the aluminum sulfate separated according to the present invention can be used as a water treatment agent, including sulfuric acid and aluminum oxide, without containing impurities such as arsenic, lead, cadmium, chromium, manganese, and mercury.

[0101] Experimental example

[0102] To measure the difference in reactivity between waste acid and aluminum waste metal according to temperature and time, 58 mL of waste acid (pH 0.48) mixed with 30 wt% sulfuric acid was used to prepare a waste acid reaction solution by adding 92 mL of water to adjust the pH to 1.33. 0.5 g of aluminum waste metal was dissolved therein and reacted for 180 minutes.

[0103] To examine the difference in reactivity according to temperature and time, the amount of hydrogen produced according to temperature and time is shown in Figure 4, and the reactivity results according to temperature are shown in Table 4 below.

[0104] pH 30℃50℃80℃100℃Reaction waste acid volume (mL)58585858Mole of hydrogen produced (mmol)0.323.8020.2731.99Mole of hydrogen / Reaction waste acid volume (mol / L)0.0050.0650.3500.551

[0105] As shown in Table 4 and Figure 4 above, it was confirmed that the higher the reaction temperature when dissolving waste acid and aluminum waste metal, the higher the reactivity. However, when reacting at a temperature above 100°C, the solvent water may evaporate, affecting the concentration of the waste acid solution. Therefore, it was confirmed that it is preferable to react at a temperature below 100°C when dissolving waste acid and aluminum waste metal.

[0106] Although the embodiments of the invention disclosed above have been illustrated and described, the disclosed invention is not limited to the specific embodiments described above, and various modifications may be implemented by a person having ordinary skill in the art to which the disclosed invention pertains without departing from the gist claimed in the claims.

Claims

1. A method for producing phosphoric acid and aluminum sulfate using waste acid and aluminum waste metal, Dissolving the aluminum waste metal in the above waste acid, Capturing the hydrogen gas generated during the above melting, The above aluminum scrap metal is filtered to separate the dissolved solution to obtain aluminum phosphate. Impurities are removed from the mixture of the solution remaining after the above filtration by adding a sulfuric acid solution and the above aluminum phosphate, Converting the captured hydrogen gas into electrical energy, The above mixture is distilled using the above electric energy to separate phosphoric acid, A manufacturing method comprising a step of recovering the remaining material after the above phosphoric acid separation and separating aluminum sulfate.

2. In paragraph 1, The above-mentioned waste acid is a manufacturing method including sulfuric acid and phosphoric acid.

3. In paragraph 1, A manufacturing method wherein the above waste acid contains 65 to 85 wt% of phosphoric acid and 15 to 35 wt% of sulfuric acid.

4. In paragraph 1, The above dissolution is a manufacturing method performed under conditions of pH 1.0 to 5.0 and a temperature of 50℃ or higher and less than 100℃.

5. In paragraph 1, A manufacturing method wherein the purity of the above hydrogen gas is 99% or higher.

6. In paragraph 1, A manufacturing method in which the above filtration is performed as a primary filtration for separating a polymer compound and a secondary filtration for separating aluminum phosphate.

7. In paragraph 6, A manufacturing method wherein the filter for the first filtration comprises at least one selected from nonwoven fabrics, woven fabrics, and knitted fabrics having pores of 30 to 50 mesh.

8. In paragraph 6, A manufacturing method in which the filter for the secondary filtration comprises at least one selected from nonwoven fabrics, woven fabrics and knitted fabrics having a pore size of 5 to 15 ㎛.

9. In paragraph 1, A manufacturing method wherein the above sulfuric acid aqueous solution contains 20 to 40% sulfuric acid.

10. In paragraph 1, A manufacturing method wherein the above sulfuric acid aqueous solution is included in a weight ratio of 1:0.1 to 20.0 with respect to aluminum phosphate.

11. In paragraph 1, The above impurities are manufactured by electrolytic treatment by applying a current of -1.66 eV or less.

12. In paragraph 1, The above distillation is a manufacturing method performed by heating at a temperature higher than the boiling point of phosphoric acid (158°C) and lower than the boiling point of sulfuric acid (338°C), and then lowering the temperature to 60 to 70°C, which is lower than the boiling point of phosphoric acid.

13. In paragraph 1, The above distillation is a manufacturing method in which heating is performed at a temperature higher than the boiling point of phosphoric acid (158°C) and lower than the boiling point of sulfuric acid (338°C) until the yield of phosphoric acid becomes 70%, reducing the pressure to 760 mmHg, heating at 60 to 100°C until the yield of phosphoric acid becomes 99% or higher, and then lowering the temperature to 60 to 70°C, which is lower than the boiling point of phosphoric acid.

14. In paragraph 1, A method for producing phosphoric acid and aluminum sulfate, wherein the purity of the phosphoric acid is 99% or higher.

15. A water treatment agent containing aluminum sulfate manufactured by the manufacturing method of clauses 1 to 14.

Images