Resource eficient Zn/Ni electroplating process

The alkaline, cyanide-free membrane coating process eliminates the production of waste water and considerably reduces the amount of fresh water and energy required.

• Membrane technology by COVENTYA GmbH for efficient and CN-free Zn/Ni plating
• Evaporator system for the thermal treatment of rinsing water, semi-concentrates and concentrates with the option of recovering electrolytes
• Analytical online monitoring of the ingredients and concentrations in the electrolytes using automatic analysers

• The plating process is free of cyanide
• The cyanide-free alkaline Zn/Ni membrane process shows a high degree of electro-chemical efficiency (> 80%). This value is about 1.5 to 1.6 times that of a conventional plating plant. The deposition rate is between 0.07 and 0.09 µm/min at 0.3 A/dm²
• The membrane process uses 50-60% less energy than a conventional plating system
• Consumption of organic additives was reduced by over 50% compared with conventional plating processes
• The need for fresh water in the plant has been reduced
• The installation produces no waste water. The rinsing water and spent electrolytes are concentrated in an open evaporator. The exhaust vapour is dissipated over the roof.
• The goal of recycling the exhaust vapour as a distillate for use as rinsing water could not be achieved during the project period
• The goal of re-supplying a significant proportion of the concentrate extracted in the evaporator to the electrolyte bath was not achieved for the following reason: the refilling volume exceeds both the drag-out and the evaporation values, and the concentrate extracted in the evaporator must therefore be disposed of thermally.
• Utilization of the concentrate is uneconomic due to the low concentrations of metal
• The Zn/Ni plating achieved by the membrane process meets the quality requirements in all respects (particularly where coating thickness and protection from corrosion are concerned)