Tinning Lines for Carbon Steel Strip

Tenova has developed a new low-sludge tin dissolution process based on insoluble anode technology. The application of this technology minimizes the amount of sludge produced and hence the loss of tin. Other benefits are the reduction of manpower for anode handling and therefore increase in safety during operation, improved coating quality, better process control and elimination of phenol vapors in the working environment.

The process is based on the oxidation of metallic tin granules by the tinning electrolyte flowing in a dissolution reactor. The electrolyte is then saturated with pure oxygen. Insoluble anodes are of a fixed width. In order to process strips of different widths, electrically insulating plates so called edge masks are used to prevent "white border defects" due to tin overcoating at the edge.

The strip edges engage in U-shaped sections arranged at the end faces of the masks. The degree of edge galvanization depends on the insertion depth of the strip edges into the U-shaped sections. It is therefore essential that the U-shaped sections always follow the strip travel precisely - the expected accuracy being less than 1 mm.

Tenova edge mask design guarantees easy inspection and access to the cell for maintenance and operational activities. Edge mask control was also developed, through a local PLC communicating with the line PLC, mainly to track the position of the weld and allow information about strip width to be sent to the local PLC.

Extra wide production flexibility:

• Capacity: up to 350.000 ton/year
• Width: up to 1.400 mm
• Thickness: from 0,1 to 0,6 mm
• Process speed: up to 600 m/min
• Total chromium coating: 35 to 140 mg/m2
• Chromium oxide coating: 7 to 35 mg/m2
• Tin coating: 0,6 to 15,2 g/m2