Silver nitrate clean production method and equipment

Abstract

The invention belongs to the technical field of silver nitrate production, and relates to a silver nitrate clean production method and equipment, silver nitrate is produced through electrochemical reaction, the equipment comprises a tank frame, a modular electrolytic tank, a power supply system and a feed liquid circulation system, the modular electrolytic tank comprises a cathode chamber, a cationic membrane, a middle chamber, an anionic membrane, an anode chamber, an anode, an anode chamber, an anionic membrane and a middle chamber, the cation membrane and the cathode chamber are sequentially combined to form an electrolytic cell module, the cathode chamber and the middle chamber are separated by the cation membrane, the anode chamber and the middle chamber are separated by the anion membrane, the cathode chamber, the middle chamber and the anode chamber are respectively provided with a liquid inlet and outlet, the liquid flow direction is that the liquid flows from bottom to top, and the upper part of the cathode chamber is provided with a gas guide port. Equipment is simple, investment is saved, and scale is easy to control.

Description

Technical Field

[0001] The invention belongs to the technical field of silver nitrate production and relates to a clean production method and equipment for silver nitrate. Background Art

[0002] Silver nitrate is a colorless crystal that is easily soluble in water. It is commonly used in photographic emulsions, silver plating, mirror making, printing, medicine, hair dyeing, and the detection of chloride, bromide, and iodide ions. It is also used in the electronics industry. The common industrial method of producing silver nitrate is to react silver with nitric acid, which requires large equipment investments and produces nitrogen oxide pollutants. Summary of the Invention

[0003] The present invention provides a clean production method and equipment for silver nitrate, which utilizes electrochemical reaction to produce silver nitrate, fully utilizes nitric acid, does not generate nitrogen oxides, and is clean and low-consumption. The equipment includes a tank frame, a modular electrolytic cell, a power supply system, and a liquid supply circulation system.

[0004] The trough frame consists of a support, a clamping device, a hanging beam, a movable end plate and a fixed end plate.

[0005] Modular electrolyzer:

[0006] (1) An electrolytic cell module is formed by sequentially assembling the cathode chamber, cationic membrane, middle chamber, anionic membrane, anode chamber, anode (with frame and outer filter bag), anode chamber, anionic membrane, middle chamber, cationic membrane, and cathode chamber;

[0007] (2) The cathode chamber and the middle chamber are separated by a cationic membrane, and the anode chamber and the middle chamber are separated by an anionic membrane;

[0008] (3) The cathode chamber, middle chamber, and anode chamber are all provided with liquid inlet and outlet ports, and the liquid flow direction is bottom-in and top-out. An air guide port is provided on the top of the cathode chamber; two rows of small cylinders are arranged in equal parts along the length direction on the outside of the upper frame of the cathode chamber, middle chamber, and anode chamber, and are tangent to the vertical surface of the upper frame. The position of the small cylinders matches the position of the circular holes on the upper edge of the filter cloth and ion membrane;

[0009] (4) A positioning groove is provided in the cathode chamber frame for embedding the cathode; the cathode is made of stainless steel, titanium, alloy or graphite;

[0010] (5) The filter bag of the anode jacket is placed in the anode frame; the anode material is metallic silver or an inert anode coated with metallic silver or silver powder;

[0011] (6) Both series and parallel connection are possible. In series connection, two adjacent electrolytic cell modules are separated by a partition. According to the direction of current flow, the cathode of the upper module is connected to the anode of the next adjacent module. In parallel connection, the two adjacent cathode chambers of two adjacent electrolytic cell modules are merged into one cathode chamber. The anodes and cathodes of all modules are connected together.

[0012] (7) The modular electrolytic cell is placed on the cell frame hanging beam close to the fixed end plate and is located between the fixed end plate and the movable end plate. The movable end plate presses the modular electrolytic cell under the action of the pressing device.

[0013] The DC power supply supplies power to the electrolytic cell. The DC power supply inputs 380V three-phase AC or 220V civilian AC and outputs DC power with adjustable constant current.

[0014] Liquid circulation system:

[0015] (1) The cathode liquid flows from the cathode liquid high-level tank to the lower liquid inlet of the cathode chamber, flows into the cathode chamber from the lower liquid inlet of the cathode chamber, overflows from the upper liquid outlet on the other side of the cathode chamber and flows into the cathode liquid low-level buffer tank, and is pumped from the cathode liquid low-level buffer tank into the cathode liquid high-level tank; the cathode liquid circulation volume is controlled by the cathode liquid high-level tank outlet valve, and the cathode liquid circulation pump automatically starts and stops according to the liquid level of the cathode liquid low-level buffer tank;

[0016] (2) The middle chamber liquid flows from the middle chamber liquid high-level tank to the middle chamber lower liquid inlet, flows into the middle chamber from the middle chamber lower liquid inlet, overflows from the upper liquid outlet on the other side of the middle chamber and flows into the middle chamber liquid low-level buffer tank, and is pumped from the middle chamber liquid low-level buffer tank into the middle chamber liquid high-level tank; the middle chamber liquid circulation volume is controlled by the middle chamber liquid high-level tank outlet valve, and the middle chamber liquid circulation pump automatically starts and stops according to the liquid level of the middle chamber liquid low-level buffer tank;

[0017] (3) The anolyte flows from the anolyte high-level tank to the lower liquid inlet of the anode chamber, flows into the anode chamber from the lower liquid inlet of the anode chamber, overflows from the upper liquid outlet on the other side of the anode chamber and flows into the anolyte low-level buffer tank, and is pumped from the anolyte low-level buffer tank into the anolyte high-level tank; the anolyte circulation volume is controlled by the anolyte high-level tank outlet valve, and the anolyte circulation pump automatically starts and stops according to the liquid level of the anolyte low-level buffer tank; the concentrated anolyte is diverted for purification and crystallization, and the crystallization mother liquor returns to the anolyte low-level buffer tank.

[0018] The process for the clean production equipment of silver nitrate of the present invention comprises the following steps:

[0019] (1) Using stainless steel, titanium, alloy or graphite as cathode, metallic silver or inert anode coated with metallic silver or silver powder as anode, make electrolytic cell module and assemble the electrolytic cell;

[0020] (2) Connect the power supply system;

[0021] (3) The cathode liquid, middle chamber liquid, and anode liquid are each equipped with a high-level tank, a low-level buffer tank, and a circulation pump, and the liquid supply circulation system is connected;

[0022] (4) The dilute sulfuric acid solution is loaded into the cathode liquid high-level tank, the dilute nitric acid solution is loaded into the middle chamber liquid high-level tank, and the dilute silver nitrate solution is loaded into the anode liquid high-level tank; the cathode liquid, middle chamber liquid, and anode liquid are circulated separately, and the circulation direction is from the high-level tank to the corresponding electrolytic cell chambers by gravity, and the overflow of each electrolytic cell chamber flows into the corresponding low-level buffer tank, and the low-level buffer tank is pumped into the corresponding high-level tank;

[0023] (5) Turn on the DC power supply and open the outlet valves of each high-level tank to supply liquid to each chamber of the electrolytic cell. The liquid level of each chamber of the electrolytic cell rises at the same height. As the liquid level of each chamber of the electrolytic cell rises, gradually increase the current density to 500-700A / m 2 ;

[0024] (6) The high-level tank outlet valve controls the circulation volume of each chamber of the corresponding electrolytic cell;

[0025] (7) Automatically control the start and stop of the corresponding circulation pump according to the liquid level of the low-level buffer tank;

[0026] (8) The cathode liquid is a sulfuric acid solution with a concentration of 1 mol / L, and the middle chamber liquid is a nitric acid solution with a concentration of 2 mol / L;

[0027] (9) The anolyte is a silver nitrate solution at 60°C. The concentrated anolyte is diverted for purification and crystallization, and the crystallization mother liquor is returned to the anolyte low-level buffer tank; the crystals are tested and dried, and qualified products are packaged and stored;

[0028] (10) Replace the anode or add silver powder to the anode filter bag and compact it.

[0029] This method uses the principle of electrochemistry and passes direct current:

[0030] Anode reaction: 2Ag-2e=2Ag +

[0031] Ag + Blocked by the anion membrane and retained in the anode chamber, NO3 in the middle chamber - It enters the anode chamber through the anion membrane, where the concentration of silver nitrate in the anolyte increases, and the concentrated anolyte is diverted for purification and crystallization;

[0032] Cathode reaction: 2H + +2e=H2↑

[0033] Middle Room H + Entering the cathode chamber through the cation membrane to replenish the H consumed by the cathode reaction + .

[0034] The advantages of the present invention are: full utilization of nitric acid, no generation of nitrogen oxides, clean and low-consumption; simple equipment, low investment, and easy scale control. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1This is a schematic diagram of the device connection of the present invention.

[0036] Markings in the figure: 1- rack, 2- modular electrolytic cell, 3- power supply system, 4- liquid circulation system, H1- middle chamber liquid high level tank, V1- middle chamber liquid high level tank outlet valve, L1- middle chamber liquid low level buffer tank, P1- middle chamber liquid circulation pump, H2- anode liquid high level tank, V2- anode liquid high level tank outlet valve, L2- anode liquid low level buffer tank, P2- anode liquid circulation pump, H3- cathode liquid high level tank, V3- cathode liquid high level tank outlet valve, L3- cathode liquid low level buffer tank, P3- cathode liquid circulation pump. DETAILED DESCRIPTION

[0037] See attached Figure 1 , the specific implementation is as follows:

[0038] Make cathode chamber, middle chamber, anode chamber, and anode (with frame and outer filter bag).

[0039] The cathode chamber, middle chamber and anode chamber are all provided with liquid inlet and outlet, and the liquid flow direction is bottom-in and top-out. An air guide port is provided at the top of the cathode chamber.

[0040] A positioning groove is provided in the cathode chamber frame for embedding the cathode. The cathode is made of stainless steel, titanium, alloy or graphite. The anode is made of metallic silver or an inert anode coated with metallic silver or silver powder. The anode jacket filter bag is placed in the anode frame.

[0041] There are two rows of small cylinders along the length direction on the outside of the upper frame of the cathode chamber, middle chamber and anode chamber. They are equally arranged along the length direction and tangent to the vertical surface of the upper frame. The positions of the small cylinders are adapted to the positions of the circular holes on the upper edge of the filter cloth and ion membrane.

[0042] The cathode chamber and the middle chamber are separated by a cationic membrane, and the anode chamber and the middle chamber are separated by an anionic membrane. An electrolytic cell module is assembled in the order of cathode chamber, cationic membrane, middle chamber, anionic membrane, anode chamber, anode (with frame and outer filter bag), anode chamber, anionic membrane, middle chamber, cationic membrane and cathode chamber.

[0043] The modular electrolytic cell is placed on the cell frame hanging beam close to the fixed end plate, between the fixed end plate and the movable end plate. After hanging, the modular electrolytic cell is pressed tightly and can be connected in series or in parallel.

[0044] When connected in series: a partition is set between two adjacent electrolytic cell modules, and according to the direction of current, the cathode of the upper module is connected to the anode of the adjacent lower module.

[0045] When connected in parallel: the two cathode chambers of two adjacent electrolytic cell modules are merged into one cathode chamber, and the anodes and cathodes of all modules are connected together.

[0046] Connect the power supply system;

[0047] The cathode chamber, middle chamber and anode chamber are each equipped with a high-level tank, a low-level buffer tank and a circulation pump;

[0048] The middle chamber liquid high level tank H1 is connected to the middle chamber liquid high level tank outlet valve V1, V1 is connected to the electrolytic cell middle chamber liquid inlet pipe, the electrolytic cell middle chamber liquid outlet pipe is connected to the middle chamber liquid low level buffer tank L1, L1 is connected to the middle chamber liquid circulation pump P1, and P1 is connected to H1;

[0049] The anolyte high-level tank H2 is connected to the anolyte high-level tank outlet valve V2, V2 is connected to the electrolytic cell anode chamber inlet pipe, the electrolytic cell anode chamber outlet pipe is connected to the anolyte low-level buffer tank L2, L2 is connected to the anolyte circulation pump P2, and P2 is connected to H2; the electrolytic cell anode chamber outlet pipe branch is connected to the purification crystallization system, and the crystallization mother liquor returns to L2;

[0050] The cathode liquid high level tank H3 is connected to the cathode liquid high level tank outlet valve V3, V3 is connected to the electrolytic cell cathode chamber liquid inlet pipe, the electrolytic cell cathode chamber liquid outlet pipe is connected to the cathode liquid low level buffer tank L3, L3 is connected to the cathode liquid circulation pump P3, and P3 is connected to H3;

[0051] Connect the liquid supply circulation system.

[0052] The dilute nitric acid solution is loaded into the middle chamber liquid high-level tank H1, the silver nitrate solution is loaded into the anode liquid high-level tank H2, and the dilute sulfuric acid solution is loaded into the cathode liquid high-level tank H3. The liquid circulation direction is: it flows from the high-level tank into each chamber of the electrolytic cell by gravity, and the overflow of each chamber of the electrolytic cell flows into the low-level buffer tank, and the low-level buffer tank is pumped into the high-level tank;

[0053] Turn on the DC power supply, open the outlet valves of each high-level tank to supply liquid to each chamber of the electrolytic cell, and the liquid level of each chamber of the electrolytic cell rises at the same height. As the liquid level of each chamber of the electrolytic cell rises, gradually increase the current density to 500-700A / m 2 ;

[0054] The high-level tank outlet valve controls the circulation volume of each chamber of the corresponding electrolytic cell;

[0055] Automatically control the start and stop of the corresponding circulation pump according to the liquid level of the low-level buffer tank;

[0056] The cathode liquid is a sulfuric acid solution with a concentration of 1 mol / L, and the middle chamber liquid is a nitric acid solution with a concentration of 2 mol / L;

[0057] The anolyte temperature is 60°C, the overflow of concentrated anolyte is diverted to purification and crystallization, and the crystallization mother liquor is returned to the anolyte low-level buffer tank; the crystals are tested and dried, and qualified products are packaged and stored;

[0058] Replace the anode or add silver powder to the anode filter bag and compact it.

Claims

1. Silver nitrate clean production equipment, characterized in that: It includes a tank frame, modular electrolytic cells, power supply system and liquid circulation system.

2. Silver nitrate clean production equipment according to claim 1, is characterized in that: The trough frame is composed of a support, a pressing device, a hanging beam, a movable end plate, and a fixed end plate.

3. Silver nitrate clean production equipment according to claim 1, is characterized in that: (1) The modular electrolytic cell is assembled into an electrolytic cell module in the order of cathode chamber, cationic membrane, middle chamber, anionic membrane, anode chamber, anode (with frame and outer filter bag), anode chamber, anionic membrane, middle chamber, cationic membrane, and cathode chamber; (2) The cathode chamber and the middle chamber of the modular electrolytic cell are separated by a cationic membrane, and the anode chamber and the middle chamber are separated by an anionic membrane; (3) The cathode chamber, middle chamber, and anode chamber of the modular electrolytic cell are all provided with liquid inlets and outlets, and the liquid flow direction is downward inlet and upward outlet. An air guide port is provided on the upper part of the cathode chamber; two rows of small cylinders are arranged in equal parts along the length direction on the outer side of the upper frame of the cathode chamber, middle chamber, and anode chamber, and are tangent to the vertical surface of the upper frame. The positions of the small cylinders are adapted to the positions of the circular holes on the upper edge of the filter cloth and the ion membrane; (4) A positioning groove is provided in the cathode chamber frame of the modular electrolytic cell for embedding the cathode; the cathode is made of stainless steel, titanium, alloy or graphite; (5) The anode jacket filter bag of the modular electrolytic cell is placed in the anode frame; the anode material is metallic silver or an inert anode coated with metallic silver or silver powder; (6) The modular electrolytic cells can be connected in series or in parallel. When connected in series, two adjacent electrolytic cell modules are separated by a partition, and the cathode of the upper module is connected to the anode of the adjacent lower module according to the direction of current; when connected in parallel, the two adjacent cathode chambers of the two adjacent electrolytic cell modules are merged into one cathode chamber, and the anodes and cathodes of all modules are connected together. (7) The modular electrolytic cell is placed on the cell frame hanging beam close to the fixed end plate, and is located between the fixed end plate and the movable end plate. The movable end plate presses the modular electrolytic cell under the action of the pressing device.

4. Silver nitrate clean production equipment according to claim 1, is characterized in that: The DC power supply of the power supply system supplies power to the electrolytic cell. The DC power supply inputs 380V three-phase AC or 220V civilian AC and outputs DC power with adjustable constant current.

5. Silver nitrate clean production equipment according to claim 1, is characterized in that: (1) The cathode liquid in the liquid supply circulation system flows from the cathode liquid high-level tank to the lower liquid inlet of the cathode chamber, flows into the cathode chamber from the lower liquid inlet of the cathode chamber, overflows from the upper liquid outlet on the other side of the cathode chamber and flows into the cathode liquid low-level buffer tank, and is pumped from the cathode liquid low-level buffer tank into the cathode liquid high-level tank; the cathode liquid circulation volume is controlled by the cathode liquid high-level tank outlet valve, and the cathode liquid circulation pump automatically starts and stops according to the liquid level of the cathode liquid low-level buffer tank; (2) In the liquid supply circulation system, the liquid in the middle chamber flows from the middle chamber liquid high-level tank to the liquid inlet at the lower part of the middle chamber, flows into the middle chamber from the lower liquid inlet, overflows from the upper liquid outlet on the other side of the middle chamber and flows into the middle chamber liquid low-level buffer tank, and is pumped from the middle chamber liquid low-level buffer tank into the middle chamber liquid high-level tank; the circulation volume of the middle chamber liquid is controlled by the liquid outlet valve of the middle chamber liquid high-level tank, and the middle chamber liquid circulation pump is automatically started and stopped according to the liquid level of the middle chamber liquid low-level buffer tank; (3) The anode liquid in the liquid supply circulation system flows from the anode liquid high-level tank to the lower liquid inlet of the anode chamber, flows into the anode chamber from the lower liquid inlet of the anode chamber, overflows from the upper liquid outlet on the other side of the anode chamber and flows into the anode liquid low-level buffer tank, and is pumped from the anode liquid low-level buffer tank into the anode liquid high-level tank; the anode liquid circulation volume is controlled by the anode liquid high-level tank outlet valve, and the anode liquid circulation pump automatically starts and stops according to the liquid level of the anode liquid low-level buffer tank; the concentrated anode liquid is diverted for purification and crystallization, and the crystallization mother liquor returns to the anode liquid low-level buffer tank.

6. The process for the clean production of silver nitrate is characterized in that: The following steps are involved: (1) Using stainless steel, titanium, alloy or graphite as cathode, metallic silver or inert anode coated with metallic silver or silver powder as anode, make electrolytic cell module and assemble the electrolytic cell; (2) Connect the power supply system; (3) The cathode liquid, middle chamber liquid, and anode liquid are each equipped with a high-level tank, a low-level buffer tank, and a circulation pump, and the liquid supply circulation system is connected; (4) The dilute sulfuric acid solution is loaded into the cathode liquid high-level tank, the dilute nitric acid solution is loaded into the middle chamber liquid high-level tank, and the dilute silver nitrate solution is loaded into the anode liquid high-level tank; the cathode liquid, middle chamber liquid, and anode liquid are circulated separately, and the circulation direction is from the high-level tank to the corresponding electrolytic cell chambers by gravity, and the overflow of each electrolytic cell chamber flows into the corresponding low-level buffer tank, and the low-level buffer tank is pumped into the corresponding high-level tank; (5) Turn on the DC power supply and open the outlet valves of each high-level tank to supply liquid to each chamber of the electrolytic cell. The liquid level of each chamber of the electrolytic cell rises at the same height. As the liquid level of each chamber of the electrolytic cell rises, gradually increase the current density to 500-700A / m 2 ; (6) The high-level tank outlet valve controls the circulation volume of each chamber of the corresponding electrolytic cell; (7) Automatically control the start and stop of the corresponding circulation pump according to the liquid level of the low-level buffer tank; (8) The cathode liquid is a sulfuric acid solution with a concentration of 1 mol / L, and the middle chamber liquid is a nitric acid solution with a concentration of 2 mol / L; (9) The anolyte is a silver nitrate solution at 60°C. The concentrated anolyte is diverted for purification and crystallization, and the crystallization mother liquor is returned to the anolyte low-level buffer tank; the crystals are tested and dried, and qualified products are packaged and stored; (10) Replace the anode or add silver powder to the anode filter bag and compact it.

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