Retec cell

Eig. 9. Retec cell for heavy-metal recovery from wastewaters. 

RETEC cell from Eltech Systems Corp [23,252,253]... 

Retec cell with vertical metal or carbon foam cathodes. The cell performance is achieved mainly by high electroactive area. The cathode product is removed by dissolving or is used as anodes. 

Retec cell Eltech Vertical metal (or carbon) foam electrodes in a tank Discontinuous cathode may be steel (which may be chemically stripped for reuse) or carbon for precious metals -cathode may be reused as an anode in plating No ... 

Retec cell (Eltech) Vertical metal or carbon foam electrodes (divided cell) Discontinuous by leaching or anodic dissolution... 

A promising high surface area material for three-dimensional electrodes is reticulated carbon (RVC) or metal. This material has been used in the Retec cell, which is an undivided monopolar connected reactor utilising a bank of vertical foam cathodes (60 x 50 cm) with interspersed DSA anodes. It has been demonstrated [26], using a 0.4 m long cathode, that the concentration of Cu(II) (in sodium sulphate, pH = 2) can be reduced from 10 ppm to approximately 0.1 ppm in a single pass even in the presence of air saturated solutions. 

Rather than using plate electrodes, a much higher surface area is obtained by using reticulated (foam) cathodes (Chapter 2, section 2.4.2). This principle is exploited in the patented RETEC cell which employs one of three types of cathode (1) Copper foam is standard for many applications (2) Nickel foam used for special applications and (3) Carbon foam, particularly for precious metals (this aids subsequent refining operations, and minimizes contamination by base metals). 

As an example of performance, a pilot-scale RETEC cell containing seven cathodes and operating at 35 A may be used to recover copper from an acid sulphate liquor, in a single-pass operation. At the 500 mg dm" Cu level, 84% metal removal is achieved with a current efficiency of 46%. A lower Cu level of 100 mg dm results in 90% removal with 10% current efficiency. At very low Cu levels (c. 30 mg dm min ) the fractional conversion is still high at 93%, albeit with a low (c. 3%) current efficiency. The data was obtained using standard pore cathodes and a flow rate of 0.75 dm min Metal removal efficiencies are greater at low flow rates, but the amount of metal recovered is less than can be achieved at high flow rates with lower efficiencies. 

Cl recovery of CrO Cr plating rinse water Eltech Retec chrome recovery cell 131... 

Cells with three-dimensional electrodes providing enlarged specific electrode area and improved mass transport due to the specific fluid dynamics inside the three-dimensional structure are, for example, the porous flow-through cell [68], the RETEC (RETEC is a trademark of ELTECH Systems Inc., Cardon, Ohio) cell [15], the packed-bed cell [69-71],... 

Fig. 7.2 The RETEC-50 cell, fa) The major components, (b) The RETEC-50 cell assembled. (Courtesy EES Corporation. RETEC t a trademark of ELTECH Systems Inc.)...

The 50 cathode cell has overall dimensions of approximately 180 x 60 x 50 cm with a cross-sectional area for flow of c. 1530cm it has provision for an air-sparging system to improve mixing and promote turbulence within the electrolyte. A porous filter plate is built into the cell at the inlet tn order to diffuse liquid Sow through the cell to prevent localized metal accumulation on the cathodes which could Lead to short circuiting. When the foam cathodes are fully loaded, they are replaced with fresh ones. In single pass operations, the cathodes nearest the inlet require most frequent replacement. The RETEC-50 cell is primarily aimed at electroplating wastes and typically operates at 400-500 A and from -2 to -6V. 

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