Steel strip pickling line continuous&push-pull type
Deep-type pickling lines consist of deep working tanks where the
acid solution presents an extremely slow flow motion. Shallow-type
pickling lines rely on a different tank design, which guarantees a
higher pickling effect on the bottom surface of the strip with
respect to conventional deep-type lines, even with slow motion of
acid flow. Unfortunately, some sealing problems characterize this
kind of line
Usually, the scale thickness is 10 to 20 μm. Its so-called scale
structure is not uniform, but mainly consists of a layer of wustite
(FeO). According to the descaling model described by Frisch and
Thiele (see Gruchot et al., 2001), the acid penetrates the scale
structure, thus reaching the free metal surface. The reaction
occurring between acid and free metal generates a local current
flowing from the scale-free metal portion, acting as an anode, to
the conductive wustite layer, playing the role of a cathode
Coil to Coil Pickling lines are a part of the finishing process of
flat rolled steel in which oxides and scale are removed from the
surface of the strip by dissolution in acid. Generally HCL is used
for carbon steel applications and hydrofluoric or nitric acids are
used for stainless steel.
Push-pull pickling lines primarily handle coils and do not have
welders at the entry sections nor storage areas for the strips.
Therefore, each coil is threaded through the process line
separately.
The pickling tanks of a push-pull line are generally shorter than
those of a continuous line because the line speed during pickling
(from about 150 to 660 fpm) is usually slower than that of a
continuous line. Other operating procedures of a push-pull line are
similar to those of a continuous line. The pickle “liquor” is
usually maintained at 180 °F or higher by external heat exchangers.
A rinse section follows the pickling section to remove acid residue
from the strip surface with fresh water. Pickled coils can be then
coated on both side of the strip with a rust preventative oil or
lubricant for later downstream processes like stamping or ship out
dry for parts to be later rollformed and painted for example
The push-pull pickling line
Process Flow
Main equipments according to processflow in turn are as follows:
Manually loading → entry skid→ coil loading trolley → pre-decoiling
(floor roller) → decoiling scraper →3-roller pinch straightener →
anti-bend roller → pay off reel → decoiling pinchroll → vertical
guide roller → 5-roller pinch straightener → transverse shearer→
vertical guide roller → acid pickling trough → washing trough →
edge blowingdevice → hot air dryer → accumulator pinch roll → pit
type accumulator →vertical guide roller → pinch centering machine →
circle shearer → waste edgerecoiler → 3-roller tension bridle roll
→ transverse shearer → vertical guideroller → exit pinch roll →
recoiler (EPC) → coil unloading trolley → rear partpressure roller
→ exit skid → manually unloading
Continuous Acid Pickling Line
Process Flow
Main equipments according to processflow in turn are as follows:
Manually loading → entry skid→ coil loading trolley I# &II# →
pay off reel I#&II# → decoiling scraper I# &II# →5-roller
pinch straightener I# &II# → transverse shearerI#&II# →
vertical guide roller → welder → crescentshearer → pinch roll →
entry accumulator → scale breaker → tension bridle roll →vertical
guide roller → acid pickling trough → washing trough → edge
blowingdevice → vertical guide roller → hot air dryer → tension
bridle roll → exit accumulator→ tension bridle roll → transverse
shearer → exit pinch roll → recoiler (EPC) →coil unloading trolley
→ exit skid → manually unloading
Technical Parameters| Production capacity | 350,000 tons annually (depend on the needs of customer, Max. annual
capacity is1,000,000 tons at present) |
| Raw material | hot rolling carbonstructure steel, high quality carbon structure
steel and low alloy steel coil,silicon steel; |
| Thickness of steel strip | 1.0~4.5mm |
| Width of steel strip | 400~1300mm (whenless than 600mm, semi-continuous method will be
adopted); |
| Processing speed | 30-180m/min (dependon the needs of output) |
| Coil weight | Max. 25tons |
| Energy | water, electricity, steam |
