Cold Rolled Annealing and Pickling Line (C-APL) for Stainless Steel Strip
Tenova, with its over 50 years of experience, has the competence and knowledge of the thermal, electrochemical and chemical processes, terminal equipment mechanical design, control and automation know how which is required for the production of stainless steel strip.strip.
The entry of an APL has a small sealing followed by a Preheating Furnace (PF). The strip is heated by waste gas coming from the Direct Fired Furnace (DFF), in the DFF strip is further heated to the required annealing temperatures and hold for certain soaking time. Strip is supported inside furnace by up-down rollers. After the annealing section, the strip enters a air cooling section followed by a water quench for final cooling and a wringer roller.
In recent years Tenova has addressed its research activities to develop innovative degreasing sections, new pickling technologies aimed at reducing both the polluting effects of the chemicals used and the overall process operational costs, optimized mechanical solution for terminal equipment, Skin Pass Mill sections, design solution to minimize the fire load and other.
After the annealing operation, Electrolytic-descaling and Pickling are very important process in the manufacture of Cold Rolled stainless steel
The Electrolytic descaling process convert and partially dissolve the thin but compact layer of scale present on the strip surface. The Tenova high efficiency electrolytic tanks, operated with Sulfuric acid at controlled Temperature, tanks also to the optimized geometries and high turbulence, reduce the electrical consumption and eliminate the presence of Cr6+ in the bath
The following pickling process is needed to dissolve a portion of the strip surface having not the correct percentage of alloy elements (so called Chromium depleted layer)
So generally the Descaling and Pickling processes involving a multi-step chemical reactions, and is one of the most polluting and costly chemical processes in the steel industry due to the presence of the highly corrosive acids and hazardous substances such as hexavalent chromium, nitrates and NOx.
Eco4 (ECOcological and ECOnomical stainless steel pickling process) is a new stainless steel pickling process developed by Tenova which avoids formation of hexavalent chromium (Cr6+) as above described, strongly improving the maintenance operator’s health and safety conditions, reduces or eliminate completely NOx and Nitrates in the waste water, reduces acid and chemical reagent cost for acid and fumes treatments, reduces overall energy consumption and reduces the investment and operating costs for spent acid and waste waters regeneration and treatment.
Furthermore also fully re-generable acids solution is available for chemical tanks furtherly reducing or eliminating cost for waste treatment and sludge disposal, recovering acid ( as HCL or HF) and alloy metals (Cr, Ni, Mn..
General Manager Sales Heat Treatment of Steel Strip, Tenova LOI Thermprocess
Director Sales, Tenova Technologies Pvt Ltd
Director of Sales Tenova LOI Thermprocess, Tenova Technologies (Tianjin)
Vice President Sales and Technology, Tenova Inc.
Senior Vice President Sales & Marketing, Tenova LOI Thermprocess