Tinning Lines for Carbon Steel Strip

Tenova proposes an innovative technology for the new generation of tin plating lines.

Tenova state-of-the-art technology features the following:

• Lowest tin consumption

• More uniform coverage, better edges

• Advanced Edge Masks design and control

• Lowest coating thickness

• Less drainage of electrolyte

• Electrolyte always available

• More flexible production campaigns

• No anodes casting plant - No anodes handling

• Much higher safety levelthe

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

Value for Money
- Return on investment just 2 - 2,5 years (insoluble anodes system and tin dissolution plant)
- Reduced operating and production costs
- Requirement of less personnel
Efficiency
- Increased tinplate production
- Reduced electricity consumption
- More flexible campaigns in terms of strip width programming, since the edge masks can adapt to all strip widths
Safety
- Reduction of manpower for anode handling and therefore increase in safety during operation
Environment
- Better process control and elimination of phenol vapors in the plating cell areas
- Lower electrolyte discharge, consumption and pollution
Technical Excellence
- Improved strip quality related to the elimination of chronic defects, such as white edges and marks of anodes
- Coating thickness less than 1 g/m2