Andritz-patentverwaltungs-gesellschaft M.b.h.

Andritz Ag

Other

Andritz-patentverwaltungs-gesselschaft M.b.h.

Jovan Starcevic

Wilhelm Karner

Erich Mahr

Edgar Braun

Karl Jirenec

Dietfried Gamsriegler

Karl Siegmund

A process for treating a stainless steel strip in an electrolytic tank produces a stainless steel with improved surface properties. The process subjects the stainless steel to a bright annealing process, followed by an electro-chemical treatment stage at current densities of up to 200 A/dm. The electro-chemical treatment is typically in a sulfate containing electrolyte solution. The current density can range from about 20 A/dmto about 200 A/dm.

Process for producing stainless steel with improved surface properties

A process for treating acidic and metallic waste water, particularly the rinsing water and/or used acids from pickling plants. The process includes the step of adding an alkaline solution or gas to bind the free acids in the waste water, followed by separation of the waste water into a first partial stream with high metal content and a second partial stream with low metal content. To achieve a more economical embodiment, particularly in terms of favorable energy consumption, and also reduce the nitrate load as much as possible, the free acids are bonded by adding ammonia solution or gas, and the first partial stream with the high metal content is fed to a regeneration plant to undergo pyrohydrolytic treatment, preferably by spray roasting. The second stream can be recycled to a rinse station.

Process for treating acidic and metallic waste water

A process for regeneration of electrolytes, in particular Na SO , from waste pickles created during picking of stainless steel, in particular stainless steel strips. The electrolytes are regenerated by adding Na H S O in an acid solution whereby Cr is reduced to Cr . Variables x, y, z and v having the following values: x&equals;0 to 2, y&equals;0 to 2, z&equals;1 to 6, v&equals;2 to 6.

Process for regeneration of electrolytes from pickle liquor, in particular of NA2S04 from pickle liquor for stainless steel

Stainless steel is pickled by a chemical and/or electrochemical pickling process using an acid liquid, containing substantially no nitric acid. The process uses a spent electrolyte solution from an electrochemical, neutral salt pickling tank, such as a sodium sulfate pickling tank. The spent electrolyte solution is added to an acid solution to form a pickling acid capable of pickling stainless steel, oxidizing Fe to Fe and reducing Cr to Cr .

Process for pickling steel

A system and method is provided for electrolytic pickling a metal strip, where the electric current is conducted through the strip indirectly without electrically conductive contact between the strip and the electrodes. The strip is run vertically or substantially vertically through the process, and the electrolyte liquid is fed in between the strip and the electrodes.

Method and apparatus for electrolytic pickling a metallic strip

Process for electrolytic treatment of continuous running material in which the material runs through an electrolytic liquid and electric potential is applied to the material. In order to guarantee freedom from differential potential in the material to be treated in any form of electrolytic treatment, the differential potential in the treated material is measured after electrolytic treatment and at least the same degree of inverse compensating potential is applied to the material. In an apparatus to implement the process, comprising at least one treatment tank to hold the electrolytic liquid and through which the material being treated is guided by means of guide rolls, as well as comprising at least one pair of electrodes to apply electric potential in the material, at least one device is included to achieve this aim and which is used to measure the differential potential of the treated material, together with at least one pair of additional electrodes connected to an adjustable rectifier, where the device for measuring the differential potential is connected to the controlling part of the rectifier.

Process and device for electrolytic treatment of continuous running

The invention concerns a process for pickling material strips made of steel, in particular stainless steel, where the strip passes through at last one pickling bath with at least one pickling acid. It is above all characterized by the fact that the acid concentration and/or the acid composition is controlled as a function of the material quality, of the pre-treatment and of the operating parameters of the pickling plant. Furthermore, the invention concerns a plant for carrying out the process, where at least two circulation tanks having different acid concentrations and/or acid compositions are provided.

Process and plant for pickling materials made of steel, in particular

Process for the electrolytic pickling of continuously advancing electrically conductive material, wherein the treatment periods as compared with purely chemical treatments are to be shortened respectively the length of the treatment plant is to be shortened and wherein the attack of aggressive ions onto the electrode material is to be counteracted for the attainment of longer life expectancies, in particular of the anode. The material to be treated is subjected to at least one cathodic treatment in a first vessel and merely an anodic treatment in an immediately following vessel, and the electrical circuit between the electrodes of different polarities in successive vessels is completed by way of the material being treated. In the apparatus according to the invention at least one anode dips into one of the successive vessels, whereas all electrodes in the immediately following vessel are of cathodic polarity.

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Vienna, Austria

Jovan Starcevic