WO2025127527A1 - Manufacturing material of sodium bicarbonate and gypsum and manufacturing method for sodium bicarbonate and gypsum using same - Google Patents

Abstract

The present invention relates to a manufacturing method for sodium bicarbonate and gypsum, comprising the steps of: preparing sodium bicarbonate (NaHCO₃) by carbonating a raw material including sodium sulfate Na₂SO₄), an impurity leaching inhibitor, and impurities; and preparing gypsum (CaSO₄) by using waste liquid generated in the step of preparing the sodium bicarbonate, wherein the impurity leaching inhibitor includes a sulfur (S)-containing material. According to the present invention, impurities such as mercury (Hg) and lead (Pb) may be prevented from being leached in waste generated during a process of manufacturing sodium bicarbonate and gypsum. Accordingly, as designated waste can now be treated as general waste, a reduction in waste treatment costs can be expected.

Description

Raw materials for manufacturing sodium bicarbonate and gypsum and method for manufacturing sodium bicarbonate and gypsum using the same

The present invention relates to a raw material for manufacturing sodium bicarbonate and gypsum containing sodium sulfate, an impurity dissolution inhibitor, and impurities, and a method for manufacturing sodium bicarbonate and gypsum therefrom.

Sodium bicarbonate ( _NaHCO3 ) is used for various purposes such as glass manufacturing, water treatment, and food additives, and is also used to remove harmful gases such as sulfur oxides (SOx) emitted from various factories, thermal power plants, and incinerators. Currently, sintering plants of steel mills use sodium bicarbonate as an adsorbent to remove sulfur oxides, and the amount of sodium bicarbonate used is increasing every year to meet stricter environmental regulations. When industrial sodium bicarbonate is imported from overseas, there is a problem that the price of sodium bicarbonate imports also varies greatly depending on overseas economic conditions.

In the reaction that removes sulfur oxides using sodium bicarbonate, carbon dioxide and sodium sulfate (sodium sulfate, _Na2SO4 ) are generated, and currently, they are being buried as they are _, causing disposal costs and secondary environmental problems. Therefore, the development of technology for sodium sulfate regeneration is urgent.

When the waste from the smelting process is regenerated, some waste is generated, and impurities such as mercury (Hg) and lead (Pb) exist inside. The waste generated during the process is classified as designated waste if it is not further processed. According to the current waste management law, mercury must be dissolved at 0.005 mg/L or less and lead must be dissolved at 3 mg/L or less according to the process test method to be classified as general waste. These are toxic metals that cause harmful effects on the human body, so leakage must be prevented, and they must be converted to substances with low solubility and buried and stored.

The present invention has been devised in consideration of the above circumstances, and can provide a method for manufacturing sodium bicarbonate and gypsum, which suppresses the generation of carbon dioxide and recycles sodium sulfate.

The present invention can provide a raw material for manufacturing sodium bicarbonate and gypsum, in which the elution of impurities such as mercury and lead is suppressed, and a method for manufacturing sodium bicarbonate and gypsum using the raw material.

The raw materials for manufacturing sodium bicarbonate and gypsum according to one embodiment of the present invention include sodium sulfate (Na ₂ SO ₄ ), an impurity dissolution inhibitor, and impurities.

The above raw material may contain an impurity release inhibitor in an amount of 0.01 wt% to 5 wt% based on the total weight of the raw material.

The above impurity release inhibitor may contain a sulfur-containing substance in an amount of 10 wt% or more and 90 wt% or less based on the total weight of the impurity release inhibitor.

The above sulfur-containing material may be one selected from sodium bisulfide, sodium sulfide, and ICX (Sodium Cellulose Xanthate).

The above impurities may include at least one selected from the group consisting of lead (Pb), copper (Cu), arsenic (As), mercury (Hg), cadmium (Cd), chromium (Cr), cyanide (CN), potassium (K), calcium (Ca), iron (Fe), and chlorine (Cl).

According to another embodiment of the present invention, a method for producing sodium bicarbonate and gypsum includes the steps of producing sodium bicarbonate (NaHCO ₃ ) by carbonating a raw material including sodium sulfate (Na ₂ SO ₄ ), an impurity release inhibitor, and impurities; and the step of producing gypsum (CaSO ₄ ) using a waste liquid generated in the step of producing the sodium bicarbonate, wherein the impurity release inhibitor includes a sulfur (S)-containing substance.

The above raw material may contain an impurity release inhibitor in an amount of 0.01 wt% to 5 wt% based on the total weight of the raw material.

The above impurity release inhibitor may contain a sulfur-containing substance in an amount of 10 wt% or more and 90 wt% or less based on the total weight of the impurity release inhibitor.

The above sulfur-containing material may be one selected from sodium bisulfide, sodium sulfide, and ICX (Sodium Cellulose Xanthate).

The above impurities may include at least one selected from the group consisting of lead (Pb), copper (Cu), arsenic (As), mercury (Hg), cadmium (Cd), chromium (Cr), cyanide (CN), potassium (K), calcium (Ca), iron (Fe), and chlorine (Cl).

In the step of manufacturing the above-mentioned sodium bicarbonate, primary waste containing 3 mg/L or less of the above-mentioned impurities may be generated.

In the step of manufacturing the above plaster, secondary waste containing 1.1 mg/L or less of the above impurities may be generated.

The step of manufacturing the above-mentioned sodium bicarbonate may include a step of manufacturing a mixture by dissolving desulfurization waste in water and then adding an impurity dissolution inhibitor; a step of obtaining a raw material by separating the mixture into solid/liquid; and a step of manufacturing the sodium bicarbonate by carbonating the raw material by adding ammonia water and carbon dioxide to the raw material.

The step of manufacturing the gypsum may include a step of adding a calcium-containing material to the waste liquid to obtain a slurry; a step of removing ammonia from the slurry and then adding an acidic solution to obtain a second mixture; and a step of separating the second mixture into solid/liquid to manufacture the gypsum.

According to the method for manufacturing sodium bicarbonate and gypsum using the sodium bicarbonate and gypsum manufacturing raw materials of the present invention, it is possible to have the effect of preventing impurities such as mercury (Hg) and lead (Pb) from being eluted from waste generated in the process of manufacturing sodium bicarbonate and gypsum. Accordingly, since designated waste can be treated as general waste, a reduction in waste disposal costs can be expected.

Figure 1 is a flow chart schematically illustrating a method for manufacturing sodium bicarbonate and gypsum according to one embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to various examples. However, the embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

The present invention relates to a method for producing sodium bicarbonate and gypsum from a raw material containing sodium sulfate and an impurity dissolution inhibitor.

Flue gases from steel mills and sintering plants contain sulfur oxides (SOx), and when desulfurization treatment is performed using sodium bicarbonate to remove the sulfur oxides, waste desulfurization agents are generated. This desulfurization method using sodium bicarbonate has the advantage of increasing desulfurization efficiency and reducing chemical costs, as one _H2O and one _CO2 are released from two sodium bicarbonate units by the heat of the flue gas, thereby activating them into _{Na2CO3 , which} has a larger contact area.

2NaHCO ₃ (s) a Na ₂ CO ₃ (s) + CO ₂ (g) + H ₂ O (g)

Na ₂ CO ₃ (s) + SO ₂ (g) + 1/2O ₂ (g) a Na ₂ SO ₄ (s) + CO ₂ (g)

However, in the desulfurization method using sodium bicarbonate, carbon dioxide is emitted as shown in the reaction formula above. In addition, when sulfur oxides are removed using sodium bicarbonate, waste converted to sodium sulfate (sodium sulfate, Na ₂ SO ₄ ) is generated.

Since Mangcho contains sodium, it is possible to produce sodium bicarbonate from Mangcho, and since the pH is relatively high, it is easy to dissolve carbon dioxide ( _CO2 ) required in the sodium bicarbonate production process. By utilizing Mangcho waste to regenerate sodium bicarbonate in this way, various problems can be solved at once, such as minimizing waste generation, achieving carbon neutrality through carbon dioxide reduction, and stabilizing operations through internal circulation of sodium bicarbonate.

Mercury (Hg) and lead (Pb) exist inside the waste desulfurizer, and they exist in the form of mercury chloride (HgCl ₂ ) and lead chloride (PbCl ₂ ) in the waste generated during the sodium bicarbonate and gypsum production processes. The solubility of impurities including mercury and lead according to temperature is shown in Table 1. The solubility shown in Table 1 represents the mass (g) of the substance dissolved per 100 mL of water.

substance 20℃ 40℃ 60℃ 80℃ Mercuric chloride (HgCl ₂ ) 6.6 10.2 16.3 30.0 Lead chloride (PbCl ₂ ) 1.1 1.4 1.9 2.5 Mercury sulfide (HgS) 2.9 x 10 ^-25 - - - Lead sulfide (PbS) 6.8 x 10 ^-13 - - -

As can be seen in Table 1, mercury chloride and lead chloride have high solubility. Mercury is classified as designated waste when it is dissolved at 0.005 mg/L or more, and lead is classified as designated waste when it is dissolved at 3 mg/L or more.

Meanwhile, as can be seen in Table 1, mercury sulfide and lead sulfide have very low solubility and are hardly dissolved.

The content of mercury and lead inside the waste desulfurizer is in ppm, and the amount of sulfide ion injected is also small. In order for the injected sulfide ion to react well with the mercury ion (Hg ²⁺ ) and lead ion (Pb ²⁺ ) present in the solution, it is necessary to inject sulfide ion when dissolving the waste desulfurizer, or to inject it mixed with other substances in the raw material.

The method for producing sodium bicarbonate and gypsum of the present invention comprises the steps of producing sodium bicarbonate (NaHCO ₃ ) by carbonating a raw material including sodium sulfate (Na ₂ SO ₄ ), an impurity dissolution inhibitor, and impurities; and the step of producing gypsum (CaSO ₄ ) by using a waste liquid generated in the step of producing the sodium bicarbonate.

In order to manufacture the above raw material, first, the desulfurization waste including the desulfurization agent and the nitrate can be dissolved in a dissolving agent to manufacture a solution. The dissolving agent can be water ( _H2O ). When the desulfurization waste is dissolved in water, mercuric chloride and lead chloride with high solubility can exist in the solution in the form of ions of mercury (Hg2 ⁺ ) and lead (Pb2 ⁺ ).

After that, an impurity release inhibitor can be added to the solution and stirred. The impurity release inhibitor includes a sulfur (S)-containing substance.

Since sulfur-containing substances contain sulfide ions (S ^2- ), if an impurity dissolution inhibitor is added to the solution, mercury sulfide and lead sulfide may be generated. The solution must be alkaline for the above-mentioned mercury sulfide and lead sulfide generation reaction to occur easily. The waste desulfurization agent is alkaline (pH>9), which provides good conditions for generating mercury sulfide and lead sulfide.

After stirring, the mixture is separated into solid and liquid to obtain solid desulfurization waste (primary waste) and raw material (sodium extraction solution).

The above raw material contains sodium sulfate (Na ₂ SO ₄ ), an impurity dissolution inhibitor, and impurities.

The above impurity release inhibitor may contain 10 wt% or more and 100 wt% or less of a sulfur (S)-containing substance. By utilizing the impurity release inhibitor of the present invention, mercury and lead, etc. are not released from waste generated during the process, and thus designated waste can be treated as general waste, thereby reducing waste disposal costs.

The above sulfur-containing material may be one selected from sodium bisulfide, sodium sulfide, and ICX (Sodium Cellulose Xanthate). Sulfide ions can exist in various forms. Considering the purity of sodium bisulfide, sodium bisulfide (NaHS), sodium sulfide (Na ₂ S), and ICX (Sodium Cellulose Xanthate) have the advantage of being able to use sodium ions as a sodium bisulfide raw material.

The above impurities may include at least one selected from the _group consisting of sodium sulfate ( _Na2SO4 ), lead (Pb), copper (Cu), arsenic (As), mercury (Hg), cadmium (Cd), chromium (Cr), cyanide (CN), potassium (K), calcium (Ca), iron (Fe), and chlorine (Cl).

The method for producing sodium bicarbonate and gypsum of the present invention includes a step of carbonating a raw material to produce sodium bicarbonate (NaHCO ₃ ).

Ammonia water and carbon dioxide can be added to the raw material, reacted in a carbonation reactor to obtain a slurry, and the slurry can be separated into solid and liquid to obtain a solid and a waste liquid. The solid can be washed and dried to produce sodium bicarbonate.

The purity of the sodium bicarbonate produced from the step of producing the sodium bicarbonate of the present invention can be 97% or more, and the yield of the sodium bicarbonate can be 75% or more.

In the step of manufacturing the above-mentioned sodium bicarbonate, primary waste containing 3 mg/L or less of the above-mentioned impurities may be generated. When the impurity content in the primary waste is 3 mg/L or less, the leakage of toxic metals harmful to the human body can be suppressed, and the cost of waste disposal can be reduced.

In the step of manufacturing the above plaster, secondary waste containing the impurities of 1.1 mg/L or less may be generated. When the impurity content in the secondary waste is 1.1 mg/L or less, the leakage of toxic metals harmful to the human body can be suppressed, and the cost of waste disposal can be reduced.

The method for producing sodium bicarbonate and gypsum of the present invention includes a step of producing gypsum (CaSO ₄ ) using waste liquid generated in the step of producing the sodium bicarbonate.

The step of manufacturing the gypsum may include a step of adding a calcium-containing material to the waste liquid to obtain a slurry. The calcium-containing material may be quicklime. After removing ammonia from the slurry, an acidic solution may be added and stirred to obtain a second mixture. The acidic solution may be a sulfuric acid aqueous solution. Alternatively, the slurry may be separated into solid and liquid to obtain a second solid and a second waste liquid. After aeration is performed on the second waste liquid to remove ammonia, the second solid may be mixed again, and then a sulfuric acid aqueous solution may be added and stirred to obtain a third mixture. Thereafter, the second mixture or the third mixture may be separated into solid and liquid to obtain gypsum and waste water.

When producing gypsum using waste liquid generated during the manufacturing process of sodium bicarbonate, there are advantages in that the cost of producing gypsum can be reduced by recycling raw materials, and the amount of waste discharged can be reduced, thereby preventing environmental pollution.

The purity of the gypsum manufactured from the step of manufacturing the gypsum of the present invention can be 95% or more, and the yield of the gypsum can be 75% or more.

Example

Hereinafter, the present invention will be described more specifically with reference to examples. The following examples are intended to more specifically explain the present invention, but the present invention is not limited thereto.

Example 1

Steps for manufacturing a bicarbonate

A solution was prepared by adding 99.93 g of desulfurized waste and 200 mL of water and stirring at 40°C for 1 hour. To the solution, sodium sulfide ( _Na2S ) was added as an impurity dissolution inhibitor, and 0.7 g of sodium sulfide ( _Na2S ) was added so that the weight ratio of sodium sulfide was 0.7 wt% based on the sum of the masses of the desulfurized waste and sodium sulfide, and additional stirring was performed at 40°C for 1 hour. After stirring, the mixture was separated into solid and liquid to obtain solid desulfurized waste (primary waste) and raw material (sodium dissolution solution).

The raw material manufacturing process was repeated until 100 g of primary waste was obtained.

100 g of primary waste and 1 L of water were added. The pH was adjusted to between 5.8 and 6.3 using hydrochloric acid. After stirring at room temperature and pressure for 6 hours, the solution was filtered (Glass filter GF-B 1 μm) to obtain a filtrate.

The amount of lead (Pb) in the residue was confirmed using the ICP (Inductively Coupled Plasma) method, and the amount of mercury (Hg) was confirmed using the AA (Atomic Absorption) method. The results of the mercury (Hg) and lead (Pb) extraction experiments for 100 g of primary waste are shown in Table 2.

Meanwhile, 90 g of ammonia water having a concentration of 25 to 30 wt% and 100 g of carbon dioxide were added to 500 g of the above raw material and reacted in a carbonation reactor to obtain a slurry. The slurry was separated into solid and liquid to obtain solids and waste liquid.

After washing the above first solid, it was dried in an oven at 50°C for more than 12 hours to obtain sodium bicarbonate.

The yield and purity of the sodium bicarbonate are shown in Table 3. The yield of the sodium bicarbonate was calculated based on the Na ⁺ mol of the waste desulfurizer and the produced sodium bicarbonate. The purity of the sodium bicarbonate was measured using ICP equipment and XRD (X-ray Powder Diffraction) equipment.

Steps in making plaster

To 500 g of the waste liquid obtained in the above-mentioned step of manufacturing the sodium bicarbonate, 350 g of 25% quicklime slurry was added and stirred for 1 hour. After stirring, the slurry was separated into solid and liquid to obtain a second solid and a second waste liquid.

The above second waste liquid was heated to 80°C and aerated using an inert gas to recover _NH3 within the slurry. The second waste liquid from which _NH3 was removed by aeration was mixed with the second solid obtained after the solid/liquid separation, and 110 g of a 30 wt% sulfuric acid aqueous solution was added and stirred. Thereafter, solid/liquid separation was performed to obtain gypsum and waste water.

The yield and purity of gypsum are shown in Table 4. The gypsum yield was calculated based on the SO ₄ ^2- mol of the waste desulfurizer and the produced gypsum. The gypsum yield was measured by ICP, and the purity of gypsum was measured by XRD.

For 1000 g of wastewater obtained in the above plaster manufacturing step, evaporation and concentration were performed for 1 hour at a temperature of 80°C or higher and a pressure of 0.1 bar or lower to obtain secondary waste.

100 g of secondary waste and 1 L of water were added. The pH was adjusted to between 5.8 and 6.3 using hydrochloric acid. After stirring at room temperature and pressure for 6 hours, the solution was filtered (Glass filter GF-B 1 μm) to obtain a filtrate.

The amount of lead (Pb) in the residue was confirmed using the ICP method, and the amount of mercury (Hg) was confirmed using the AA method. The results of the mercury (Hg) and lead (Pb) elution experiments for 100 g of secondary waste are shown in Table 5.

Examples 2 to 5

Sodium bicarbonate and gypsum were manufactured in the same manner as in Example 1, except that 98.7, 98, 97.7, and 96.7 g of desulfurized waste were added, respectively, and 1.3, 2.0, 2.3, and 3.3 g of sodium sulfide were added, respectively.

Comparative Example 1

Sodium bicarbonate and gypsum were manufactured in the same manner as in Example 1, except that 100 g of desulfurized waste was added and sodium sulfide was not added.

Experimental example

The amount of lead (Pb) in the filtrate of the primary wastes of Examples 2 to 5 and Comparative Example 1 was confirmed using the ICP method, and the amount of mercury (Hg) was confirmed using the AA method. The results of the mercury (Hg) and lead (Pb) elution experiments for 100 g of primary waste are shown in Table 2.

Na ₂ S (wt%) Hg (mg/L) Pb (mg/L) Comparative Example 1 0.0 0.1087 3.1221 Example 1 0.7 0.0031 2.1055 Example 2 1.3 0.0012 1.0522 Example 3 2.0 Not detected Not detected Example 4 2.3 Not detected Not detected Example 5 3.3 Not detected Not detected

It can be confirmed that mercury is detected at 0.005 mg/L or less and lead is detected at 3 mg/L or less in the primary wastes of Examples 1 to 5.

The yield and purity of the sodium bicarbonate of Examples 2 to 5 and Comparative Example 1 are shown in Table 3.

Na ₂ S (wt%) Purity of the medium (%) Yield of the medium (%) Comparative Example 1 0.0 98.5 77 Example 1 0.7 98.3 80 Example 2 1.3 98.2 79 Example 3 2.0 97.9 81 Example 4 2.3 98.1 78 Example 5 3.3 99.1 77

It can be confirmed that there is no difference in the purity and yield of the sodium bicarbonate in Comparative Example 1 and Examples 1 to 5. It can be confirmed that the presence or absence of sodium sulfide does not affect the purity and yield of the sodium bicarbonate.

The yield and purity of the gypsum of Examples 2 to 5 and Comparative Example 1 are shown in Table 4.

Na ₂ S (wt%) Gypsum Purity (%) Gypsum yield (%) Comparative Example 1 0.0 95.2 80 Example 1 0.7 97.1 81 Example 2 1.3 96.3 79 Example 3 2.0 95.1 78 Example 4 2.3 96.1 82 Example 5 3.3 97.3 75

It can be confirmed that there is no difference in the purity and yield of gypsum between Comparative Example 1 and Examples 1 to 5. It can be confirmed that the presence or absence of sodium sulfide does not affect the purity and yield of gypsum.

The amount of lead (Pb) in the filtrates of the secondary wastes of Examples 2 and 3 and Comparative Example 1 was confirmed using the ICP (Inductively Coupled Plasma) method, and the amount of mercury (Hg) was confirmed using the AA (Atomic Absorption) method. The results of the mercury (Hg) and lead (Pb) elution experiments for 100 g of secondary waste are shown in Table 5.

Na ₂ S (wt%) Hg (mg/L) Pb (mg/L) Comparative Example 1 0.0 0.0623 2.7922 Example 1 0.7 0.0122 1.0022 Example 2 1.3 0.0015 0.0556 Example 3 2.0 Not detected Not detected Example 4 2.3 Not detected Not detected Example 5 3.3 Not detected Not detected

It was confirmed that mercury was detected at 0.005 mg/L or less and lead was detected at 3 mg/L or less in the waste of Examples 1 and 2.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and it will be apparent to those skilled in the art that various modifications and variations are possible within a scope that does not depart from the technical spirit of the present invention described in the claims.

Claims (13)

Raw material for manufacturing sodium bicarbonate and gypsum, including sodium _sulfate ( _Na2SO4 ), impurity dissolution inhibitors and impurities. In the first paragraph, A raw material containing 0.01 wt% or more and 5 wt% or less of an impurity release inhibitor based on the total weight of the raw material. In the first paragraph, The above impurity release inhibitor is a raw material containing 10 wt% or more and 100 wt% or less of a sulfur-containing substance based on the total weight of the impurity release inhibitor. In the third paragraph, The above sulfur-containing material is a raw material selected from sodium bisulfide, sodium sulfide, and ICX (Sodium Cellulose Xanthate). A step of manufacturing sodium bicarbonate (NaHCO ₃ ) by carbonating a raw material containing sodium sulfate (Na ₂ SO ₄ ), an impurity dissolution inhibitor, and impurities; and It includes a step of manufacturing gypsum (CaSO ₄ ) using waste liquid generated in the step of manufacturing the above-mentioned sodium bicarbonate. The above impurity release inhibitor comprises a sulfur (S)-containing substance. Method for manufacturing sodium bicarbonate and gypsum. In paragraph 5, A method for manufacturing sodium bicarbonate and gypsum, wherein the above raw material contains an impurity release inhibitor in an amount of 0.01 wt% to 5 wt% based on the total weight of the raw material. In paragraph 5, A method for manufacturing sodium bicarbonate and gypsum, wherein the impurity release inhibitor comprises a sulfur-containing material in an amount of 10 wt% or more and 100 wt% or less based on the total weight of the impurity release inhibitor. In paragraph 5, A method for manufacturing baking soda and gypsum, wherein the sulfur-containing substance is one selected from sodium bisulfide, sodium sulfide and ICX (Sodium Cellulose Xanthate). In paragraph 5, A method for producing sodium bicarbonate and gypsum, wherein the impurities include at least one selected from the group consisting of lead (Pb), copper (Cu), arsenic (As), mercury (Hg), cadmium (Cd), chromium (Cr), cyanide (CN), potassium (K), calcium (Ca), iron (Fe), and chlorine (Cl). In paragraph 5, In the step of manufacturing the above-mentioned solution, A method for manufacturing sodium bicarbonate and gypsum, wherein primary waste containing 3 mg/L or less of the above impurities is generated. In paragraph 5, In the step of manufacturing the above plaster, A method for manufacturing sodium bicarbonate and gypsum, which produces secondary waste containing 1.1 mg/L or less of the above impurities. In paragraph 5, The steps for manufacturing the above-mentioned solution are: A step of preparing a mixture by dissolving desulfurized waste in water and then adding an impurity release inhibitor; A step of obtaining a raw material by separating the solid/liquid of the mixture; and A method for manufacturing sodium bicarbonate and gypsum, comprising a step of manufacturing sodium bicarbonate by adding ammonia water and carbon dioxide to the raw material to carbonate the raw material. In paragraph 5, The steps for manufacturing the above plaster are: A step of obtaining a slurry by adding a calcium-containing material to the above waste liquid; A step of removing ammonia from the above slurry, and then adding an acidic solution to obtain a second mixture; and A method for producing baking soda and gypsum, comprising the step of producing gypsum by separating a second mixture into solid and liquid.

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