Basket anodes

Although rod anodes screwed into the side walls of containers are preferred, plate anodes and basket anodes are mostly necessary on the base. They are particularly suitable for large containers without being built in. Plate anodes are supplied with a flat plastic holder to which the cable conductor is attached and... 

In such cases basket anodes are frequently used. These have a relatively large surface and work at a low driving voltage due to their special construction. A cylinder of platinized titanium-expanded metal serves as the basket to which a titanium rod is welded. This serves as the current lead and carrier, and ends in a plastic foot that contains the cable lead and at the same time serves as the mounting plate. The expanded metal anode exhibits a very uniform anode current density distribution, even at large dimensions, in contrast to the plate anode. The reason is the many comers and edges of the metal that make the point effect only evident at the outer edges of the anode. 

For these reasons, the cathodic corrosion protection of chemical plant parts is restricted to neutral solutions, service water, and alkalis. Various types of anodes are available for the protection of container interiors. Platinized disk electrodes, bar anodes, and titanium basket anodes are used. They are now supplied ready for installation and are designed in such a way that, in continuous operation, they can emit 8-10 A at a current density of 6-8 A/dm. ... 

Figure 7.15 Plotating basket anode in molten salt electrorefining [29].

In some cases, particularly with iaactive metals, electrolytic cells are the primary method of manufacture of the fluoroborate solution. The manufacture of Sn, Pb, Cu, and Ni fluoroborates by electrolytic dissolution (87,88) is patented. A typical cell for continous production consists of a polyethylene-lined tank with tin anodes at the bottom and a mercury pool (ia a porous basket) cathode near the top (88). Pluoroboric acid is added to the cell and electrolysis is begun. As tin fluoroborate is generated, differences ia specific gravity cause the product to layer at the bottom of the cell. When the desired concentration is reached ia this layer, the heavy solution is drawn from the bottom and fresh HBP is added to the top of the cell continuously. The direct reaction of tin with HBP is slow but can be accelerated by passiag air or oxygen through the solution (89). The stannic fluoroborate is reduced by reaction with mossy tin under an iaert atmosphere. In earlier procedures, HBP reacted with hydrated stannous oxide. 

Since the 1960s titanium mesh anode baskets have been used (21), especially in nickel plating solutions. Nickel anodes in the form of small round buttons and pellets combined with the titanium anode basket allows a constant anode area to be maintained with a minimum of effort. 

The alkaline version of the Mn02 / zinc cell follows a different concept because it turns the construction of the Leclanche cell completely around now the cathode (Mn02 + carbon) forms a hollow cylinder contacting the inner wall of the cell container (steel) along its outer surface. The inner cavity has to accommodate anode, electrolyte, separator, and current collector. Usually, the separator forms a basket, which is automatically inserted and pre-... 

In a pilot plant [2,13], superalloy scrap containing Mo, W, Cr, Fe, Co, and Ni is pretreated in a furnace with carbon to transfer refractory metals (Mo, W, etc.) into carbides. The melt is granulated and the resulting material is charged into titanium baskets. Diaphragm-type electrolytic cells are used for anodic dissolution of the granulated material. Fe, Co, Ni, and small amounts of Cr are dissolved into a calcium chloride solution by the current. The metal carbides are not dissolved and remain as an anodic residue in the baskets. 

Color Plate 12 Formation of Diffusion Layer During Electrolysis (Box 17-3) (a) Cu electrode (flat plate, left) and Pt electrode (mesh basket, right) immersed in solution containing KI and starch, with no electric current, (b) Starch-iodine complex forms at surface of Pt anode when current flows. 

A cell used by the Salzbergwerke,1 Stassfurt, is shown in section in Fig. 7. It is of iron, and contains the solution of manganate, which is replenished by gradual solution of the fused product contained in the metal baskets B. The cathodes are immersed in cement boxes C which serve as diaphragms, and sheet iron anodes A dip into the liquor between the metal baskets and the cement cathode... 

Another cell for gold recovery is the Mintek cell. It has a rectangular configuration with alternating anodes and cathodes in parallel. The anodes are perforated stainless steel plates. The cathodes are removable plastic baskets with perforated sides, packed with steel wool. The electrodes fit the cell sides and bottom, so that the electrolyte has to flow through the electrodes. Packed cathodes of steel wool... 

Electrolytic dissolution in nitric acid has been used at the Savannah River [B22] and Idaho Qiemical Processing plants [AlO, All] to dissolve a wide variety of fuels and cladding materials, including uranium alloys, stainless steel, aluminum, zircaloy, and nichrome. The electrolytic dissolver developed by du Pont [B22], pictured in Fig. 10.4, uses niobium anodes and cathodes, with the former coated with 0.25 mm of platinum to prevent anodic corrosion. Metallic fuel to be dissolved is held in an alundum insulating frame supported by a niobium basket placed between anode and cathode and electrically insulated from them. Fuel surfaces facing the cathode undergo anodic dissolution in a reaction such as... 

Anodic corrosion of the niobium basket that supports the fuel is inhibited by an electrically conducting oxide film, which forms on the niobium. 

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