A method of producing a cold rolled steel strip includes: subjecting a steel strip that has been cold rolled and subsequently continuously annealed to pickling by continuously feeding the steel strip into a mixed acid solution containing a first acid that is oxidizing and a second acid that is non-oxidizing to immerse the steel strip; and subsequently subjecting the steel strip to repickling by continuously feeding the steel strip into an acid solution containing a third acid that is non-oxidizing to immerse the steel strip. The concentration of the first acid in the mixed acid solution is lowered and the concentration of the second acid in the mixed acid solution is raised as the iron ion concentration in the mixed acid solution rises.

Continuous annealing equipment (1) including a cleaning device (11, 12) for performing a cleaning treatment on a steel strip (S) and an annealing device (12) for performing an annealing treatment on the steel strip (S) comprises an exhaust gas passage (31, 41) through which an exhaust gas discharged from the annealing device (12) flows, a solution circulation passage (32, 51) through which a cleaning solution used in the cleaning device (11, 12) circulates, and a heat exchanger (53) which forms a part of the solution circulation passage (32, 51) and contacts with the exhaust gas.

Disclosed is a method for continuous thermal treatment of a steel strip. The strip passes through consecutive thermal treatment chambers, is quickly cooled in at least one of the chambers by spraying liquid onto the strip, or by spraying a fluid made up of gas and liquid or spraying a combination of gas and liquid forming a mist. After quick cooling, a protective metal layer is deposited on the strip by dip coating. The cooling fluid strips iron oxides or other alloy elements contained in the steel to be treated, minimizing oxidation and reducing the oxides on the strip. Spray pressure and distance are chosen to facilitate the stripping property and the mechanical action of the sprayed fluid, reducing the layer of oxides on the strip. The temperature of the strip at the end of the cooling step is the temperature necessary for carrying out the desired treatment cycle.

A cleaning plant for hot-rolled metal strips provided with a surface oxide layer, the plant comprising unwinding means for unwinding at least one coil of rolled strip and pickling means for pickling said rolled strip; wherein there are provided measuring means for measuring the thickness of the surface oxide layer, arranged between said unwinding means and said pickling means; and wherein gaseous hydrogen detection means are provided to detect the presence of gaseous hydrogen in fumes produced by said pickling means. A corresponding cleaning method is also claimed.

A manufacturing method of a support for a planographic printing plate including at least an alkaline etching step of dissolving an aluminum surface layer of an aluminum web with an alkaline solution during a surface roughening treatment on a surface of the aluminum web continuously traveling, the manufacturing method comprising: a circulating step of cyclically using the alkaline solution between a treatment tank for the etching and an alkaline solution reservoir during adjusting composition concentration of the alkaline solution; and a filtering step of filtering the alkaline solution cyclically used so as to remove solid matter in the alkaline solution.

The present application relates to an annealing device (1), in particular an annealing furnace, for the oxidation-free heat treatment N) of a hot-rolled steel strip (3), which is provided for the production of an electrical steel strip and/or stainless steel strip, a treatment line (2) for the continuous pickling and oxidation-free annealing of a hot-rolled steel strip (3), and a method for the continuous pickling and oxidation-free annealing of a hot-rolled steel strip (3).