Cherepovets plant "Severstal-Metiz" reduces consumption of sulphuric acid by 17%

Cherepovets plant "Severstal-Metiz" reduces consumption of sulphuric acid by 17%

During the last eight months of 2021, Cherepovets plant Severstal-Metiz has reduced its consumption of concentrated sulfuric acid for metal pickling from 131 to 108.7 tons per month, by introducing cyclic regeneration system for the pickling solution and doubling its pumping speed.

Etching (lowering the metal into a solution of sulfuric or hydrochloric acid) is one of the main stages in the preparation of wire rods before further processing, as it helps remove scale from the metal’s surface. The pickling solution needs to maintain a specific concentration, since iron oxide precipitates during chemical reactions. To do this, after pickling, the depleted solution is pumped to Severstal-Metiz’s sulphuric acid plant, acid is added to it, and it is then reused in the pickling process — this is how the regeneration works.

To reduce the impact on the environment from April to December 2021, specialists from the Cherepovets plant Severstal-Metiz laid a new pipeline and made the process cyclical. Due to the larger diameter of the pipeline, 72 centimeters, 12 centimeters more than that of the old pipeline, the pickling solution turnover rate was reduced from two hours to 40 minutes and the volume of its regeneration increased. Due to the implementation of the cyclic regeneration system, the plant’s consumption of sulphuric acid has decreased by 17%.

At the sulphuric acid plant, iron oxide is separated from the solution and then collected as iron sulfate, and the spent solution is sent to the PAO Severstal sludge accumulator.

Sergey Kovryakov, General Director of OAO Severstal-Metiz commented:

“Chemical descaling is currently one of the most effective methods of preparing a metal’s surface before processing and directly affects the quality of Severstal-Metiz's finished products. But at the same time, it has an additional impact on the environment. Therefore, we must use the available resources as efficiently as possible. Increasing the volume of regenerated solution and its turnover made it possible not only to reduce our consumption of sulphuric acid, but also to increase the production of iron sulfate by 32 tons per month up to 82.5 tons.”