Hot-dip Galvanizing Production line

1. Technological process

1.1 load material                         1.2 check workpiece

1.3enter to the closed room                 1.4 pickling              

1.5 washing                             1.6 fluxing                

1.7 out of the closed room after drying        1.8 galvanizing              

1.9 cooling                              1.10 Non-Chrome passivating   

1.11 inspection                           1.12 packing

2. Processing before galvanizing

2.1 Acid pickling

The plating pieces will be hanged on the special sling in feeding area, then they will be transported into pickling closed room by rundles and put into the concentration of 15-20% HCl to soak some time, the purpose is to remove the oxide layer and rust on the surface of the plating pieces, and enhance the adhesion strength of the zinc layer; Scale, rust and other iron oxide react with acid solution and become the formation of salt in acid solution that will be removed. Waste acid produced by long-term production will be pumped into the waste acid treatment system to get relatively low concentration acid and be recycled after treatment, it is only need to add new acid. Acid mist can be centralized collection treatment by air pipes in the closed room.

2.2 Plating assistant

Plating pieces have been pickled and rinsed will be put into the plating assistant bath and immerse in ZnCl₂ - NH₄Cl double salt aqueous about 0.5 ~ 1 min. Using 316L sheathed heater(per set power is 80KW) to heat plating aid to keep the temperature about 50 ~ 70 ℃; Plating solution use online recycling treatment system, control the amount of iron ions and acid content in the solution.

3. Hot-dip galvanizing

The pieces have been plated will put into zinc liquid by crane and quickly open the vibrator vibration to remove the ashes of the clip in the plating parts .According the zinc layer thickness to set the zinc dipping time, hoisted out plating pieces after aborting zinc ash, zinc dust collected by closed gas-collecting hood, it will be treated by dust cleaning equipment processing. Zinc slag and zinc ash can be sold to the downstream manufacturers.

4. Post-processing 

4.1 Cool down

The surface temperature is very high when plating piece lifted from zinc pot, so it should be put into warm water to cooled to the normal temperature, otherwise it may produce off color and affect the appearance quality.

4.2 Chromium-free passivation

Cooled parts soak in chromium-free passivation pool more than 60 seconds to form passivation coating on galvanized products surface. It can keep the good appearance quality, prevent white rust during a certain period of time .