1. Structure of nickel sulfide electrolytic cell 1) Tank The main equipment for nickel sulfide anode electrolysis is electrolytic cell. The cell housing is made of reinforced concrete and lined with anti-corrosive materials. The anti-corrosion linings used in China include: lining lacquered linen, acid-resistant porcelain, soft polyvinyl chloride plastic sheet, epoxy resin, etc. The anti-corrosion effect of the lacquered lining is good, but the drying time required for the lacquer film is longer, and the toxicity of the lacquer is larger, and it has been used less. The anti-corrosion effect of the soft PVC plastic sheet lining is also good, but the weld quality is not easy to guarantee due to the large lining area. At present, more epoxy resin is used, which is used as a lining with high strength, good integrity and good corrosion resistance. The construction method is manual lining. The anti-corrosion effect mainly depends on the choice of the formulation, the surface treatment of the base layer, the arrangement of the epoxy resin cloth and the degree of resin penetration, and whether the heat treatment conditions are reasonable. Jinchuan company construction of cell lined with epoxy resin, epoxy resin paving 5 to 7 layers, the service life of more than a decade.
An acid-resistant ceramic tile is placed over the corrosion-resistant lining at the bottom of the cell (Figure 1) to protect the bottom of the tank from corrosion. The bottom of the tank is provided with a discharge port for discharging the anode slime. The electrolytic cell is mounted on a reinforced concrete beam, and the four corners of the slot are insulated with an insulating plate.
The following table shows the technical performance of the electrolytic cell used by some manufacturers in China.
2) Diaphragm holder The diaphragm used in nickel electrorefining is a diaphragm bag made of polyester cotton with a certain water permeability. It is placed on a diaphragm holder with a rectangular shape and an open top for the purpose of placing the cathode and containing the purified electrolyte. The diaphragm is fixed to the diaphragm holder. Previously, the diaphragm holder was made of wood and the service life was only 3 months. Nowadays, round steel is used as the skeleton, and the assembled diaphragm frame is made of epoxy resin or rubber as an anti-corrosion layer.
The technical performance of the nickel sulfide anode electrolyzer below | |||
project | I factory | II factory | III factory |
Production capacity / (ta-1) | 40000 | 1200 | 600 |
Number of electrolytic cells | 384 | 44 | 17 |
Among them: the number of plate slots / one | 38 | 2 | 1 |
Number of liquid making tanks/piece | 96 | 　 | 　 |
Cell length / mm | 7340 | 3680 | 7600 |
Width / mm | 1150 | 1170 | 700 |
Depth/mm | 1480 | 1320 | 1200 |
Electrolytic cell material | Reinforced concrete lining epoxy | Reinforced concrete lining epoxy | Reinforced concrete lining burlap |
Anode (length × width × thickness) / mm | 860×370×(50～55) | 730×350×35 | 470×650×(25～30) |
Cathode sheet (length × width) / mm | 880×860 | 850×870 | 490×670 |
Number of anodes per wafer | 38×2 | 19×2 | 41 |
Number of cathodes per chip | 37 | 18 | 40 |
Same pole center distance / mm | 190 | 190 | 190~200 |
3) Acidic liquid-making electrolytic cell The material, size and anti-corrosion lining of the acidic liquid-making electrolytic cell are completely the same as those of the finished electrolytic cell. The difference is that it does not use a diaphragm bag, and therefore does not place a diaphragm holder, which is a diaphragmless electrolytic cell.
2, cathode, anode specifications 1) an anode of nickel sulfide anode lugs are embedded beforehand at the anode casting a copper wire or a flat steel ring ring (FIG. 2). China's nickel-sulphide electrolytic refineries use small anode shape specifications and also have job requirements.
(1) The shape of the anode plate is 860mm × 370mm, the thickness is 50 ~ 55mm, and the porosity of the anode plate should be controlled to a low limit;
(2) The surface bulge height and the vent depth are not more than 10 mm;
(3) the curvature of the plate surface and the air hole are not more than 10 mm;
(4) The surface slag area does not exceed 3%;
(5) The exposed part of the copper ear wire is 250-270mm long and is firmly embedded.
2) The cathode sheet (cathode sheet) is processed by embossing, nailing and the like of the nickel flakes peeled off by the seed plate. In order to avoid dendrite formation at the cathode edge, the width of the cathode and the curvature of the cathode are not better than the anode. Large 40 ~ 50mm (Figure 3).
3) kinds of plate manufacturers are currently electroless nickel sulfide as the titanium starting sheet material (FIG. 4). Compared with the stainless steel seed plate, the titanium plate has high corrosion resistance and the initial piece is easily peeled off.
Due to the smooth surface of the new titanium plate, the deposited nickel is not easily formed, so it needs to be pretreated before use. The treatment method is to soak the titanium seed plate in an aqueous solution containing 400-700 g/L of sulfuric acid and 80-90 ° C for 0.5 to 1 min, and then wash it with clean water, and then use coarse sandpaper to make a width of about 30 mm on the left and right sides of the seed plate. The edge of the light can be used after the acid-resistant rubber is applied. After the titanium plate is used for 3 to 5 months, it needs to be treated once more by the above method. The initial sheet rate can reach more than 95%.
3. The DC circuit connection of the DC circuit in the electrolysis workshop is generally connected by the double-connection method, that is, all the anodes in each electrolytic cell are connected side by side, all the cathodes are also connected in parallel, and the slots and the slots are connected in series, that is, All cells are connected in series in a DC supply line.
The current intensity of the cell is equal to the sum of the currents through the electrodes of the same name in the cell, the so-called cell current, and the cell voltage is equal to the voltage drop between any pair of anodes and cathodes in the cell.
In order to supply power to the anode and anode in the tank, a trough busbar is arranged on both sides of the electrolyzer, and the busbar is generally made of a copper plate of 100 mm×10 mm, and is composed of single piece, double piece and three pieces of riveting according to the total current. Busbar.
When the electrolytic cell is being loaded and unloaded, it is generally required to short-circuit "horizontal electricity". The “cross-electric†operation uses a rectangular or square rod at each end of the electrolytic cell to connect the slots on both sides of the electrolytic cell, so that the slot current flows shortly from the rod, and no longer passes through the cathode of the groove. And anode, but because of the high voltage and high current of nickel electrolysis, this "Maple" method is easy to cause accidents such as burning bus, firing, power failure, etc. Now, a fixed "horizontal" device has been installed in the trough head to reduce labor. Strength, safe and reliable.
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