Ak Steel Corporation

Armco Inc.

Armco Steel Company, L.p.

Jerald W Leeker

Vijay N Madi

Ronald D Rodabaugh

Clayton A Van Scoy

Christian D Nelson

Christopher M Kovscek

Joyce C Neidringhaus

The present invention provides a process for the removal of hydrogen peroxide from spent pickle liquor used in a steel strip pickling process. The process utilizes an enclosed decomposition tank which includes a pickle liquor inlet pipe, an outlet pipe, at least one vent pipe, an internal baffle, and a heat source.

Apparatus for removing hydrogen peroxide from spent pickle liquor

Method for removing hydrogen peroxide from spent pickle liquor

The present invention relates to a process for pickling hot rolled, hot rolled & annealed, and cold rolled & annealed stainless steel strip in a continuous fashion. The process comprises a series of pre-pickling tanks and pickling tanks, and optionally includes a scrubber-brush tank, a de-smutting tank, a filtration unit and a heat exchanger.

Hydrogen peroxide pickling scheme for stainless steel grades

The pickling process of the present invention is designed for pickling electrical steel strip in a continuous fashion and comprises at least one pickling tank equipped with at least one set of sprayers designed to spray the top and bottom surfaces of a steel strip with a solution comprised of hydrogen peroxide prior to and/or after the strip is immersed in a solution contained in a pickling tank. The set(s) of sprayers in each of the pickling tanks are located above the level of the pickle bath solution, rather than being located in separate spray tanks. Upon exiting the final pickling tank, the strip is brushed/scrubbed to loosen any residual scale to form a clean strip.

Hydrogen peroxide pickling scheme for silicon-containing electrical steel grades

This invention relates to a process for producing a cold rolled, recrystallation annealed, stainless steel strip having lustrous surfaces without being hot band annealed and/or pickled prior to cold reduction. The process includes the sequential steps of tension leveling to crack the scale and flatten a hot processed metal strip, shot blasting the strip to ablatively remove the scale and to provide a surface roughness less than 3.6 micron Ra using at least two pairs of wire brushes positioned adjacent to both surfaces of the strip with these cleaning brushes being rotated in opposite directions relative to each other to mechanically remove any residual scale. The mechanically cleaned strip then is mechanically polished with another pair of brushes to reduce the roughness to less than 2.0 micron Ra, cold reduced to have a surface roughness less than 0.4 micron Ra and recrystallization annealed. The particulate shot has a size of 0.10-0.50 mm. The cleaning brushes have a surface density of at least 12% unit square surface area and the bristles of the cleaning brushes have a tip diameter of 0.13-0.50 mm.

Method for descaling hot rolled strip

A process for removing scale from stainless steel using an aqueous solution containing hydrogen peroxide and an inorganic acid, i.e., hydrochloric or sulfuric acid. A hot rolled or annealed stainless steel strip (10) covered with scale is immersed into hot inorganic acid contained within pickling tanks (12) and (14). Thereafter, the strip may have residual amounts of tightly adherent scale (11). This scale is activated by a solution containing the inorganic acid and hydrogen peroxide applied to the strip such as by a spray header (16) extending completely transversely across and positioned above the strip and another spray header (18) extending completely transversely across and positioned below the strip. It may be desirable to pass the activated strip through the hot inorganic acid again and reactivate the strip at very high line speeds to insure complete removal of scale from the strip. Any hydrogen peroxide spray dripping from the strip is collected on a catch pan (30) and flowed into a tank (28). Preferably, the collected spent aqueous solution containing the inorganic acid and spent hydrogen peroxide is disposed in the pickling tanks. The aqueous solution aids in the removal of any residual scale and smut remaining on the strip thereby improving the cleanliness of the pickled strip.

Hydrogen peroxide pickling of stainless steel

A process for removing scale from stainless steel using an aqueous solution containing hydrogen peroxide. A hot rolled or annealed stainless steel strip (10) covered with scale is immersed into hot sulfuric acid contained within tanks (12) and (14). Thereafter, the strip may have residual amounts of tightly adherent scale (11). This scale is activated by the aqueous solution containing hydrogen peroxide applied to the strip such as by a spray header (16) extending completely transversely across and positioned above the strip and another spray header (18) extending completely transversely across and positioned below the strip. Any peroxide spray dripping from the, strip is collected on a catch pan (30) and flowed into a tank (28). Preferably, the peroxide solution is a dilute concentration of the acid in tanks (12) and (14). The hydrochloric acid removes smut from the strip formed by the sulfuric acid to improve the cleanliness of the pickled strip.

Caustic dezincing galvanized steel scrap. A dezincing plant includes a plurality of tanks interconnected in series with steel scrap sequentially being moved through each of the tanks. The tanks contain a caustic leaching solution including an oxidant with the leaching solution being circulated through each of the tanks in a direction opposite to the movement of the scrap. Fresh scrap initially is exposed to a partially depleted leaching solution with the oxidant concentration of the leaching solution increasing as the scrap moves through the series of tanks. Leaching solution depleted of its oxidant is transferred to an electrolytic cell where zinc is removed and plated as metallic zinc powder onto a cathode. The leaching solution is recycled by removing zinc. The chemistry of the leaching solution is controlled so that sufficient free caustic is present to prevent passivating zinc coating on the scrap. Oxidant is added to the recycled solution and the caustic concentration is adjusted, if necessary, to have a total caustic concentration of at least 5 M and the recycled solution is returned to the last tank. Compressed scrap bales are dezinced and ready for use as a melting furnace charge material.

Growing community of inventors

Trenton, OH, United States of America

Jerald W Leeker