Silver oxalate preparation device and silver oxalate preparation method

Abstract

The present invention relates to the field of silver oxalate and discloses a silver oxalate preparation device and a silver oxalate preparation method. The silver oxalate preparation device of the present invention comprises a first dissolution unit (1), a second dissolution unit (2), a synthesis unit (3), a centrifugal separation unit (4), a storage and reuse unit (5), a silver recovery unit (7) and a waste acid neutralization unit (8). Using the silver oxalate preparation device of the present invention to prepare silver oxalate can simplify the preparation steps, significantly reduce the amount of water used, and reduce silver loss and waste acid discharge.

Description

Technical Field

[0001] The present invention relates to the field of silver oxalate, and in particular to a device for preparing silver oxalate and a method for preparing silver oxalate. Background Art

[0002] Silver oxalate is an important silver salt. As a raw material for preparing nanosilver and silver catalysts, it has important application value in the fields of photosensitive chemistry and catalyst synthesis.

[0003] Existing methods for preparing silver oxalate involve reacting silver nitrate with solutions of oxalate-containing compounds, such as oxalic acid, sodium oxalate, or ammonium oxalate. However, due to the low solubility of oxalic acid (only approximately 9.52 g at room temperature), the resulting silver oxalate requires extensive water washing to remove impurities. This process consumes a lot of water and results in high unit production costs. Improving production capacity, reducing water consumption per unit of product, and lowering production costs are key technical challenges. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above-mentioned problems existing in the prior art and provide a device for preparing silver oxalate and a method for preparing silver oxalate. The use of the device to prepare silver oxalate can simplify the preparation steps, significantly reduce the amount of water used, and reduce silver loss and waste acid discharge.

[0005] In order to achieve the above object, the present invention provides a silver oxalate preparation device, which includes a first dissolution unit, a second dissolution unit, a synthesis unit, a centrifugal separation unit, a storage and reuse unit, a silver recovery unit and a waste acid neutralization unit.

[0006] The first dissolution unit and the second dissolution unit are each connected to a synthesis unit, so that the silver nitrate solution in the first dissolution unit and the oxalate-containing solution in the second dissolution unit enter the synthesis unit to react;

[0007] The synthesis unit is connected to the centrifugal separation unit, so that the reaction product generated in the synthesis unit enters the centrifugal separation unit for solid-liquid separation and then is washed to obtain a washing liquid and a filter cake;

[0008] The centrifugal separation unit includes a feed port and a discharge port;

[0009] The storage and reuse unit includes a liquid inlet and a liquid outlet, wherein the liquid inlet is connected to the discharge port of the centrifugal separation unit, and the liquid outlet is connected to the feed port of the centrifugal separation unit, and is used to recover the washing liquid obtained by the centrifugal separation unit and send the recovered washing liquid into the centrifugal separation unit through the liquid outlet for reuse;

[0010] The silver recovery unit is used to recover silver in the washing liquid. The silver recovery unit is connected to the discharge port of the centrifugal separation unit and the liquid outlet of the storage and reuse unit. The washing liquid enters the silver recovery unit through the discharge port and the liquid outlet to recover silver.

[0011] The waste acid neutralization unit is used to neutralize the washing liquid. The waste acid neutralization unit is connected to the silver recovery unit so that the washing liquid after silver recovery enters the waste acid neutralization unit for neutralization.

[0012] Preferably, the storage and reuse unit is a liquid storage tank.

[0013] Preferably, the silver recovery unit is a liquid storage tank.

[0014] Preferably, the waste acid neutralization unit is a reactor with a frame stirrer.

[0015] Preferably, the centrifugal separation unit is a centrifugal filter.

[0016] Preferably, the first dissolving unit and the second dissolving unit each include a heating unit and a first stirring unit.

[0017] Preferably, the first dissolving unit is a reactor.

[0018] Preferably, the second dissolving unit is a reactor.

[0019] Preferably, the synthesis unit includes a cooling unit and a second stirring unit.

[0020] Preferably, the synthesis unit is a reactor.

[0021] According to a second aspect of the present invention, a method for preparing silver oxalate is provided, wherein the preparation is carried out in the silver oxalate preparation device of the present invention, comprising the following steps:

[0022] 1) preparing a silver nitrate solution in the first dissolution unit and preparing an oxalate compound-containing solution in the second dissolution unit;

[0023] 2) introducing the silver nitrate solution and the oxalate compound solution obtained in step 1) into the synthesis unit to react;

[0024] 3) passing the reaction product obtained in step 2) into the centrifugal separation unit for centrifugal separation and then washing, and centrifuging to obtain a washing liquid and a filter cake during washing;

[0025] 4) passing the washing liquid obtained in step 3) into the storage and recycling unit for recovery;

[0026] 5) passing the recovered washing liquid obtained in step 4) and / or the waste acid liquid obtained by centrifugal separation into the silver recovery unit to recover silver;

[0027] 6) passing the washing liquid after silver recovery obtained in step 5) into the waste acid neutralization unit for neutralization,

[0028] The method further comprises sending the washing liquid recovered by the storage and reuse unit into the centrifugal separation unit for reuse.

[0029] Preferably, in step 2), the molar ratio of oxalate in the oxalate-containing compound introduced into the synthesis unit (3) to silver nitrate in the silver nitrate solution is 1:1.25-2, preferably 1:1.4-2, and more preferably 1:1.5-1.9.

[0030] Preferably, the washing conditions include: first washing with a recovered washing liquid and then washing with water, wherein the water washing makes the pH of the washed water greater than 5.

[0031] Preferably, in step 2), the reaction conditions include: reaction temperature 5-30° C., reaction time 10-600 min.

[0032] Preferably, the concentration of the silver nitrate solution is 2-85% by mass, and the concentration of the oxalate compound solution is 4-33% by mass.

[0033] Preferably, the concentration of the silver nitrate solution is 10-50% by mass, and the concentration of the oxalate compound solution is 9-30% by mass.

[0034] Through the above technical solution, the silver oxalate preparation device of the present invention simplifies the preparation steps, significantly reduces the amount of water used in the preparation of silver oxalate, and reduces the loss of silver and the discharge of waste acid. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a schematic diagram of a silver oxalate preparation device of the present invention,

[0036] Description of Reference Numerals

[0037] 1: first dissolution unit; 2: second dissolution unit;

[0038] 3: synthesis unit; 4: centrifugal separation unit;

[0039] 5: Storage and reuse unit; 6: Pump;

[0040] 7: Silver recovery unit; 8: Waste acid neutralization unit; DETAILED DESCRIPTION

[0041] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0042] The following reference Figure 1 , the preparation device of silver oxalate provided by the present invention will be specifically described. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0043] like Figure 1 As shown, the silver oxalate preparation device provided by the present invention includes a first dissolution unit 1, a second dissolution unit 2, a synthesis unit 3, a centrifugal separation unit 4, a storage and reuse unit 5, a silver recovery unit 7 and a waste acid neutralization unit 8;

[0044] The first dissolution unit 1 and the second dissolution unit 2 are each connected to a synthesis unit 3, so that the silver nitrate solution in the first dissolution unit 1 and the oxalate-containing solution in the second dissolution unit 2 enter the synthesis unit 3 to react;

[0045] The synthesis unit 3 is connected to the centrifugal separation unit 4, so that the reaction product generated in the synthesis unit 3 enters the centrifugal separation unit 4 for solid-liquid separation and then is washed to obtain a washing liquid and a filter cake;

[0046] The centrifugal separation unit 4 includes a feed port and a discharge port;

[0047] The storage and reuse unit 5 includes a liquid inlet and a liquid outlet, wherein the liquid inlet is connected to the discharge port of the centrifugal separation unit 4, and the liquid outlet is connected to the feed port of the centrifugal separation unit 4, and is used to recover the washing liquid obtained by the centrifugal separation unit 4 and send the recovered washing liquid into the centrifugal separation unit 4 through the liquid outlet for reuse;

[0048] The silver recovery unit 7 is used to recover silver in the washing liquid. The silver recovery unit 7 is connected to the discharge port of the centrifugal separation unit 4 and the liquid outlet of the storage and recycling unit 5. The washing liquid enters the silver recovery unit 7 through the discharge port and the liquid outlet to recover silver;

[0049] The waste acid neutralization unit 8 is used to neutralize the washing liquid. The waste acid neutralization unit 8 is connected to the silver recovery unit 7 so that the washing liquid after silver recovery enters the waste acid neutralization unit 8 for neutralization.

[0050] According to the present invention, the first dissolution unit 1 is used to prepare a silver nitrate solution, and the second dissolution unit 2 is used to prepare an oxalate compound-containing solution. In order to speed up the dissolution speed, save time and improve efficiency, preferably, the first dissolution unit 1 and the second dissolution unit 2 each include a heating unit and a first stirring unit.

[0051] The heating unit is not particularly limited and can be a heating device commonly used in the chemical industry. Preferably, the heating unit is one or more of an electric heater, a steam heating jacket and a steam heating coil; more preferably, the heating unit is an electric heater and / or a steam heating jacket.

[0052] In order to facilitate heating, preferably, the heating unit is arranged outside the first dissolving unit 1 and the second dissolving unit 2 .

[0053] The first stirring unit is not particularly limited and can be a stirring device commonly used in the chemical industry. Preferably, the first stirring unit is one or more of an electric paddle type or a propeller type. Specifically, a frame stirrer can be used.

[0054] The first dissolving unit 1 may be a reactor commonly used in the art, preferably a reactor with an electric heating device and a frame stirrer.

[0055] Likewise, the second dissolving unit 2 may be a reactor commonly used in the art, preferably a reactor with an electric heating device and a frame stirrer.

[0056] According to the present invention, the synthesis unit 3 is used to react a silver nitrate solution with an oxalate compound solution to generate silver oxalate. In order to fully react and lower the temperature after the reaction is completed so that the silver oxalate is fully precipitated, the synthesis unit 3 includes a cooling unit and a second stirring unit.

[0057] Preferably, the cooling unit is one or more of a cooling jacket, a cooling coil or natural cooling without insulation; more preferably, the cooling unit is a cooling jacket.

[0058] There is no particular limitation on the location of the cooling unit, as long as cooling can be achieved. Preferably, the cooling unit is arranged outside the synthesis unit 3, for example, in the form of a jacket.

[0059] Preferably, the second stirring unit is one or more of an electric paddle stirrer and a propeller stirrer.

[0060] The synthesis unit 3 may be a reactor commonly used in the art, preferably a reactor with a jacket cooling device and a frame stirrer.

[0061] According to the present invention, in order to facilitate the addition and discharge of materials, it is preferred that the feed port of the centrifugal separation unit 4 is located above the centrifugal separation unit 4, the discharge port of the centrifugal separation unit 4 is located below the centrifugal separation unit 4, the liquid inlet of the storage and reuse unit 5 is located above the storage and reuse unit 5, and the liquid outlet of the storage and reuse unit 5 is located below the storage and reuse unit 5.

[0062] According to the present invention, to facilitate the recycling of the washing liquid, a pump 6 is preferably provided between the liquid outlet of the storage and recycling unit 5 and the feed inlet of the centrifugal separation unit 4. The pump 6 delivers the liquid in the storage and recycling unit 5 to the centrifugal separation unit 4 for washing. Various pumps commonly used in the chemical industry can be used as the pump 6.

[0063] According to the present invention, in order to facilitate further processing of the washing liquid having a pH that is too low to be suitable for re-washing, preferably, the liquid outlet of the storage and reuse unit 5 is used to pass the washing liquid having a pH lower than 1 into the silver recovery unit 7 to recover silver, and to make the pH of the washing liquid in the storage and reuse unit 5 above 1.

[0064] According to the present invention, the silver recovery unit 7 is used to recover silver from the washing liquid and / or the waste acid solution obtained by centrifugal separation. The method for recovering silver can be, for example, reacting a compound solution containing chloride ions with the washing liquid and recovering the resulting precipitate. The compound containing chloride ions can be, for example, an alkali metal hydrochloride and / or an alkaline earth metal hydrochloride, ammonium chloride or hydrochloric acid, preferably sodium chloride, ammonium chloride or hydrochloric acid.

[0065] According to the present invention, the waste acid neutralization unit 8 is used to neutralize the acid in the washing liquid after silver recovery. The neutralization method can be, for example, reacting the washing liquid with an alkali. The alkali can be, for example, an alkali metal hydroxide, preferably sodium hydroxide.

[0066] In order to improve the neutralization efficiency, preferably, the spent acid neutralization unit further includes a third stirring unit, which can be an electric frame-type, paddle-type or propeller-type stirrer.

[0067] According to the present invention, the centrifugal separation unit 4 is preferably a centrifugal filter. The centrifugal filter may be a centrifugal filter used in the existing chemical industry for solid-liquid separation.

[0068] According to the present invention, the storage and reuse unit 5 may be any container commonly used in the art for storing liquids, for example, a liquid storage tank, preferably a plastic liquid storage tank.

[0069] According to the present invention, the silver recovery unit 7 may be any container commonly used in the art for storing liquids, such as a liquid storage tank, preferably a plastic liquid storage tank.

[0070] According to the present invention, the spent acid neutralization unit 8 is preferably a reactor with a frame stirrer, more preferably a stainless steel or enamel reactor with a frame stirrer.

[0071] A second aspect of the present invention provides a method for preparing silver oxalate, which is prepared in the silver oxalate preparation device of the present invention and comprises the following steps:

[0072] 1) preparing a silver nitrate solution in the first dissolution unit 1 and preparing an oxalate compound-containing solution in the second dissolution unit 2;

[0073] 2) passing the silver nitrate solution and the oxalate compound solution obtained in step 1 into the synthesis unit 3 to react;

[0074] 3) passing the reaction product obtained in step 2 into the centrifugal separation unit 4 for centrifugal separation and then washing to obtain a washing liquid and a filter cake;

[0075] 4) the step of passing the washing liquid obtained in step 3 into the storage and reuse unit 5 for recovery;

[0076] 5) passing the recovered washing liquid obtained in step 4) into the silver recovery unit 7 to recover silver;

[0077] 6) passing the washing liquid after silver recovery obtained in step 5) and / or the waste acid liquid obtained by centrifugation into the waste acid neutralization unit 8 for neutralization and then discharge;

[0078] The method further comprises sending the washing liquid recovered by the storage and reuse unit 5 into the centrifugal separation unit 4 for reuse.

[0079] According to the present invention, from the perspective of saving water and facilitating solid-liquid separation, preferably, the concentration of the silver nitrate solution is 2-85% by mass, and the concentration of the oxalate compound solution is 4-33% by mass; more preferably, the concentration of the silver nitrate solution is 10-50% by mass, and the concentration of the oxalate compound solution is 9-30% by mass.

[0080] According to the present invention, preferably, in step 2, the reaction conditions include: reaction temperature 5-30°C, reaction time 10-600 min; more preferably, the reaction conditions include: reaction temperature 10-30°C, reaction time 60-300 min.

[0081] According to the present invention, when the ratio of oxalate in the oxalate-containing compound to silver nitrate in the silver nitrate solution is a specific value, the reaction is more sufficient. Preferably, in step 2, the molar ratio of oxalate in the oxalate-containing compound passed into the synthesis unit 3 to silver nitrate in the silver nitrate solution is 1:1.25-2.5; more preferably, in step 2, the molar ratio of oxalate in the oxalate-containing compound passed into the synthesis unit 3 to silver nitrate in the silver nitrate solution is 1:1.25-2; more preferably, in step 2, the molar ratio of oxalate in the oxalate-containing compound passed into the synthesis unit 3 to silver nitrate in the silver nitrate solution is 1:1.4-2; further preferably, the molar ratio of oxalate in the oxalate-containing compound passed into the synthesis unit 3 to silver nitrate in the silver nitrate solution is 1:1.5-1.9.

[0082] According to the present invention, from the perspective of saving washing water, preferably, the washing conditions include: first washing with recycled washing liquid and then washing with water, and the water washing makes the pH of the water after washing greater than 5.

[0083] According to the present invention, as a method of recovering silver, for example, it can be: reacting a compound solution containing chloride ions with the washing liquid and recovering the resulting precipitate, and the compound containing chloride ions can be, for example, alkali metal hydrochloride and / or alkaline earth metal hydrochloride, ammonium chloride or hydrochloric acid, preferably sodium chloride, ammonium chloride or hydrochloric acid.

[0084] According to the present invention, the neutralization method may be, for example, reacting the washing liquid with a base. The base may be, for example, an alkali metal hydroxide, preferably sodium hydroxide, in an amount such that the pH value is approximately 7.

[0085] The present invention will be described in detail below by way of examples, but the present invention is not limited to the following examples.

[0086] The following example 1 adopts Figure 1 The silver oxalate preparation apparatus shown in the figure prepares silver oxalate. The apparatus comprises a first dissolution unit 1, a second dissolution unit 2, a synthesis unit 3, a centrifugal separation unit 4, a storage and reuse unit 5, a silver recovery unit 7, and a waste acid neutralization unit 8. The first dissolution unit 1 and the second dissolution unit 2 are each a reactor with an electric heater and a frame stirrer. The synthesis unit 3 is a reactor with a jacket cooling device and a frame stirrer. The centrifugal separation unit 4 is a centrifugal filter with a feed inlet and a discharge port. The storage and reuse unit 5 is a liquid storage tank with a liquid inlet, a liquid outlet, and a liquid discharge port. The silver recovery unit 7 is a plastic liquid storage tank, and the waste acid neutralization unit 8 is a neutralization reactor with a frame stirrer.

[0087] The first dissolution unit 1 and the second dissolution unit 2 are each connected to a synthesis unit 3, the synthesis unit 3 is connected to the feed port of the centrifugal separation unit 4, the discharge port of the centrifugal separation unit 4 is connected to the liquid inlet of the storage and reuse unit 5, and is used to recover the washing liquid obtained by the centrifugal separation unit 4. The storage and reuse unit 5 includes a liquid inlet and a liquid outlet, the liquid inlet is connected to the discharge port of the centrifugal separation unit 4, the liquid outlet is connected to the feed port of the centrifugal separation unit 4 and is pumped into the centrifugal separation unit 4 via a pump 6. The recovered washing liquid enters the centrifugal separation unit 4 through the liquid outlet to wash the filter cake. The liquid outlet of the storage and reuse unit 5 is also connected to the silver recovery unit 7, so that the washing liquid enters the silver recovery unit 7 to recover silver. The silver recovery unit 7 is connected to the spent acid neutralization unit 8, so that the recovered washing liquid is neutralized and discharged.

[0088] Example 1

[0089] (1) The first dissolution unit 1 and the second dissolution unit 2 were heated to 65° C., and 165 kg of a 40% by mass silver nitrate solution and 130 kg of a 16% by mass oxalic acid solution were respectively added under stirring at 20 rpm.

[0090] (2) The silver nitrate and oxalic acid solutions were introduced into the synthesis unit 3 at a mass flow ratio of 127:100, and cooled so that the solution temperature in the synthesis unit 3 was 25° C. The reaction residence time was 3 h.

[0091] (3) The solution in the synthesis unit 3 is sent to the centrifugal separation unit 4, and centrifuged at 950 rpm for 40 min at room temperature until the solid and liquid are completely separated, and the centrifuged liquid is discharged into the silver recovery unit 7; thereafter, the filter cake is washed with water while centrifuging at 950 rpm until the pH of the washed water is 6, using a total of 331 kg of water. About 67.04 kg of silver oxalate solid is collected from the centrifuge and sealed in a dark place. The silver content of the silver oxalate solid is 62.0% by weight after analysis, and the yield is 99.2%. The total water consumption in the process is 7.9 kg / kg-silver oxalate.

[0092] (4) The washing liquid obtained in step (3) is sent to the storage and recovery unit 5 for recovery.

[0093] (5) 0.228 kg of sodium chloride was added to the silver recovery unit 7, mixed evenly, and then settled for 24 hours to obtain a precipitate and a supernatant, wherein the total weight of the precipitate was 0.1692 kg and the silver content was 65.2%.

[0094] (6) The supernatant obtained in step (5) is passed into the spent acid neutralization unit 8, and sodium hydroxide is gradually added until the liquid is neutral.

[0095] Example 2

[0096] (1) The first dissolution unit 1 and the second dissolution unit 2 were heated to 65° C., and 165 kg of a 40% by mass silver nitrate solution and 130 kg of a 16% by mass oxalic acid solution were respectively added under stirring at 25 rpm.

[0097] (2) The silver nitrate and oxalic acid solutions were introduced into the synthesis unit 3 at a mass flow ratio of 127:100, cooled to a temperature of 25° C. in the synthesis unit 3, and reacted for 3 h.

[0098] (3) Turn on the agitator of the synthesis unit 3 (25 rpm), pass the solution in the synthesis unit 3 into the centrifugal separation unit 4, and centrifuge at 950 rpm for 40 min until the solid and liquid are completely separated. The waste acid stock solution separated by centrifugation is collected into the silver recovery unit 7; then, while centrifuging at 950 rpm, wash the obtained filter cake with the recovered washing liquid of Preparation Example 1, and discharge the above washing liquid into the silver recovery unit 7; then wash the obtained filter cake with water until the pH of the washed water is 6, using a total of 235 kg of water.

[0099] (4) The washing liquid obtained by washing with water in step (3) is passed into the storage and recovery unit 5 for recovery.

[0100] (5) 0.560 kg of sodium chloride was added to the solution in the silver recovery unit 7, mixed evenly, and allowed to settle for 24 hours to obtain a precipitate and a supernatant.

[0101] (6) The supernatant obtained in step (5) is passed into the spent acid neutralization unit 8, and sodium hydroxide is gradually added until the liquid is neutral.

[0102] 66.8 kg of silver oxalate product was obtained, with a silver content of 62.2% and a yield of 99.1%. In addition, 0.221 kg of silver chloride precipitate was recovered, with a silver content of 66.0%. The process used 6.5 kg of water per kg of silver oxalate per unit product.

[0103] Example 3

[0104] (1) The first dissolution unit 1 and the second dissolution unit 2 were heated to 65° C., and 190 kg of a 35% by mass silver nitrate solution and 139 kg of a 15% by mass oxalic acid solution were respectively added under stirring at 20 rpm.

[0105] (2) The silver nitrate and oxalic acid solutions were introduced into the synthesis unit 3 at a mass flow ratio of 137:100, cooled to a temperature of 20° C. in the synthesis unit 3, and reacted for 4 h.

[0106] (3) The agitator of the synthesis unit 3 was turned on (20 rpm), and the solution in the synthesis unit 3 was passed into the centrifugal separation unit 4 and centrifuged at 950 rpm for 50 min until the solid and liquid were completely separated. The filter cake was then washed with 215 kg of the recovery washing liquid of Example 2 while centrifuging at 950 rpm. The washing liquid was discharged into the silver recovery unit 7, and the filter cake was washed with water until the pH of the washed water was greater than 5. A total of 198 kg of water was used.

[0107] (4) The washing liquid obtained by washing with water in step (3) is passed into the storage and recovery unit 5 for recovery.

[0108] (5) The recovered washing liquid is passed into the silver recovery unit 7, 0.674 kg of sodium chloride is added, mixed evenly and then settled for 24 hours to obtain a precipitate and a supernatant.

[0109] (6) The supernatant obtained in step (5) is passed into the spent acid neutralization unit 8, and sodium hydroxide is gradually added until the liquid is neutral.

[0110] 68.5 kg of silver oxalate product was obtained, with a silver content of 61.0% and a yield of 99.0%. The process used 6.3 kg of water per kg of silver oxalate per unit product. In addition, 0.255 kg of silver chloride was recovered, with a silver content of 65.0%.

[0111] In the early stage of washing the silver oxalate filter cake with deionized water, the centrifugal filtrate with a pH less than 1 or less than 1.5 can be directly discharged into the silver recovery unit 7, and only the filtrate with a higher pH can be reused.

[0112] Comparative Example 1

[0113] (1) Silver nitrate and oxalic acid were dissolved at room temperature to prepare 0.825 kg of a 40% by mass silver nitrate solution and 1.312 kg of an 8.0% by mass oxalic acid solution, respectively.

[0114] (2) While stirring continuously, the silver nitrate and oxalic acid solutions were added to a 3000 ml glass beaker in a mass flow ratio of 63:100. After the reaction was complete, the mixture was cooled naturally to room temperature (25°C). The process took 4 hours.

[0115] (3) Using a Buchner funnel, the slurry was filtered under suction, and the filter cake was washed with distilled water, with 300 mL of distilled water used each time, until the pH value of the washing water was greater than 5, with a total of 1800 mL of water, and the washing liquid was discharged. 0.332 kg of silver oxalate filter cake was obtained, with a silver content of 62.5% by mass and a yield of 99.0%. The total water consumption during the process was 10.4 kg / kg-silver oxalate.

[0116] A comparison of the water consumption during the preparation process of the above-mentioned embodiment and the comparative example shows that, by adopting the process and method of the present invention, the water consumption per unit product in the preparation process is greatly reduced. In addition to obtaining the target product, a certain amount of silver chloride can be recovered, which greatly improves the economic efficiency of the production process. Moreover, the process can be operated continuously, the process is greatly simplified, and it is more environmentally friendly.

[0117] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A device for preparing silver oxalate, characterized in that: The device comprises a first dissolving unit (1), a second dissolving unit (2), a synthesis unit (3), a centrifugal separation unit (4), a storage and recycling unit (5), a silver recovery unit (7) and a waste acid neutralization unit (8). The first dissolution unit (1) and the second dissolution unit (2) are each connected to a synthesis unit (3), so that the silver nitrate solution in the first dissolution unit (1) and the oxalate-containing solution in the second dissolution unit (2) enter the synthesis unit (3) to react; The synthesis unit (3) is connected to the centrifugal separation unit (4), so that the reaction product generated in the synthesis unit (3) enters the centrifugal separation unit (4) for solid-liquid separation and then is washed to obtain a washing liquid and a filter cake; The centrifugal separation unit (4) comprises a feed port and a discharge port; The storage and reuse unit (5) comprises a liquid inlet and a liquid outlet, wherein the liquid inlet is connected to the discharge port of the centrifugal separation unit (4), and the liquid outlet is connected to the feed port of the centrifugal separation unit (4), and is used to recover the washing liquid obtained by the centrifugal separation unit (4), and to send the recovered washing liquid into the centrifugal separation unit (4) through the liquid outlet for reuse; The silver recovery unit (7) is used to recover silver in the washing liquid. The silver recovery unit (7) is connected to the discharge port of the centrifugal separation unit (4) and the liquid outlet of the storage and reuse unit (5). The washing liquid enters the silver recovery unit (7) through the discharge port and the liquid outlet to recover silver. The waste acid neutralization unit (8) is used to neutralize the washing liquid. The waste acid neutralization unit (8) is connected to the silver recovery unit so that the washing liquid after silver recovery enters the waste acid neutralization unit (8) for neutralization.

2. The silver oxalate preparation device according to claim 1, wherein: The storage and reuse unit (5) is a liquid storage tank.

3. The silver oxalate preparation device according to claim 1, wherein: The silver recovery unit (7) is a liquid storage tank.

4. The silver oxalate preparation device according to claim 1, wherein: The waste acid neutralization unit (8) is a reactor with a frame stirrer.

5. The silver oxalate preparation device according to claim 1, wherein: The centrifugal separation unit (4) is a centrifugal filter.

6. The silver oxalate preparation device according to claim 1, wherein: The first dissolving unit (1) and the second dissolving unit (2) each include a heating unit and a first stirring unit.

7. The silver oxalate preparation device according to claim 6, wherein: The first dissolving unit (1) is a reactor.

8. The silver oxalate preparation device according to claim 6, wherein: The second dissolving unit (2) is a reactor.

9. The device for preparing silver oxalate according to claim 1, wherein: The synthesis unit (3) includes a cooling unit and a second stirring unit.

10. The silver oxalate preparation device according to claim 9, wherein: The synthesis unit (3) is a reaction kettle.

11. A method for preparing silver oxalate, characterized in that: The preparation is carried out in the silver oxalate preparation device according to any one of claims 1 to 10, comprising the following steps: 1) preparing a silver nitrate solution in the first dissolution unit (1) and preparing an oxalate compound-containing solution in the second dissolution unit (2); 2) passing the silver nitrate solution and the oxalate compound solution obtained in step 1) into the synthesis unit (3) to cause a reaction; 3) passing the reaction product obtained in step 2) into the centrifugal separation unit (4) for centrifugal separation and washing, and centrifuging to obtain a washing liquid and a filter cake during washing; 4) the step of passing the washing liquid obtained in step 3) into the storage and recycling unit (5) for recovery; 5) the step of passing the recovered washing liquid obtained in step 4) and / or the waste acid liquid obtained by centrifugal separation into the silver recovery unit (7) to recover silver; 6) The washing liquid after silver recovery obtained in step 5) is passed into the waste acid neutralization unit (8) for neutralization. The method further comprises sending the washing liquid recovered by the storage and reuse unit (5) into the centrifugal separation unit (4) for reuse.

12. The preparation method according to claim 11, wherein In step 2), the molar ratio of the oxalate in the oxalate-containing compound introduced into the synthesis unit (3) to the silver nitrate in the silver nitrate solution is 1:1.25-2.

13. The preparation method according to claim 12, wherein In step 2), the molar ratio of the oxalate in the oxalate-containing compound introduced into the synthesis unit (3) to the silver nitrate in the silver nitrate solution is 1:1.4-2.

14. The preparation method according to claim 13, wherein In step 2), the molar ratio of the oxalate in the oxalate-containing compound introduced into the synthesis unit (3) to the silver nitrate in the silver nitrate solution is 1:1.5-1.

9.

15. The preparation method according to claim 11, wherein The washing conditions include: first washing with a recovered washing liquid and then washing with water, wherein the water washing makes the pH of the washed water greater than 5.

16. The preparation method according to claim 11, wherein In step 2), the reaction conditions include: reaction temperature 5-30° C., reaction time 10-600 min.

17. The preparation method according to claim 11, wherein The concentration of the silver nitrate solution is 2-85% by mass, and the concentration of the oxalate-containing compound solution is 4-33% by mass.

18. The preparation method according to claim 17, wherein The concentration of the silver nitrate solution is 10-50% by mass, and the concentration of the oxalate compound solution is 9-30% by mass.

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