The vertical electrode electrolyzer invented by Mobius in 1890 is the most widely used one in Europe and other regions. However, the horizontal electrode electrolyzer invented by tume and balbach thum was also used in America. Although the latter has the advantage of dissolving anode completely, it is not used now because of many disadvantages.
Although the electrolytic conditions, equipment and operation of silver in different factories are similar, some of them are quite different. For example, a factory adopts the following electrolysis process:
Area current 250-300a / m2, cell voltage 1.5-3.5v, liquid temperature self heating (35-50 ℃). The electrolyte contains Ag 80-100g / L, HNO 32-5g / L and Cu less than 50g / L. The circulation speed of electrolyte is 0.8-1l / min, and the mixing speed of glass rod is 20-22 times / min. The cathode is 0.7 × 0.35m, 3mm thick pure silver plate. The gold + silver content of anode bird is over 97%, and the gold content is no more than 33%. The anode cycle is 34-38h. The same polar distance is 135-140mm. Electrolytic silver powder contains 99.86-99.88% silver.
Mobius vertical electrode electrolyzers are mostly reinforced cement tanks, lined with soft plastic, with a nearly square shape. The liquid collecting tank and the high-level tank are steel plate tanks lined with soft plastic. The circulation form of electrolyte is from bottom to top, and small vertical stainless steel pump is used to pump liquid.
The cells are combined in series. The anode plate is hung in a two-layer cloth bag with a silver hook for drilling. The cathode pure silver plate is hung on the copper rod with a lifting eye. During electrolysis, the cathode silver grows rapidly. In addition to being broken by the glass rod, the silver crystal on the cathode should be scraped off 2-3 times with a plastic scraper within 8 hours to prevent short circuit. When the electrolysis period reaches 20 hours, the anode is continuously dissolved and the distance between the two electrodes is gradually increased, and the current density is also gradually increased, resulting in the rise of cell voltage fluctuation. When the cell voltage gradually rises to 3.5V, the anode plate has basically dissolved, at this time, it should be out of the cell. The extracted electrolytic silver is placed in the filter tank and washed with hot water until there is no green or micro green in the washing solution, and then dried and sent to the ingot. The residual electrode in the diaphragm bag (the ratio of residual electrode is about 4% – 6%) and the primary black gold powder are washed and dried, and then the secondary alloy plate is melted and cast. The secondary black gold powder is washed, dried, fused and cast into the thick gold anode plate and sent to electrolysis for pure gold extraction.
Post time: May-13-2020