MXPA97009010A - Continuous operations of cleaning and finishing of rolled steel strip pl - Google Patents

Abstract

The present invention relates to continuous strip steel strip finishing line apparatus comprising: A) means supplying flat rolled steel strip coils, with surface areas in the flat laminate contaminated with iron flash and associated scrap, such as those produced during gauge reduction, each winding provides an extended length of that flat rolled steel contaminated on the surface, B) means for unwinding rolling steel coils, flat, to provide flat rolled steel interconnected from successive windings forming a flat unitary rolled steel strip of continuous length for the surface preparation and finishing of the surface areas; C) a surface cleaning system of the strip that works continuously for that surface laminated steel contaminated on the surface, which includes: (i) a main tank of pre-selected capacity to stop the surface cleaning solution and means for providing sufficient continuous strip movement through the main tank to dislodge iron burrs and associated debris from the surface areas of the strip, (ii) means to remove a portion of the cleaning solution capacity of the main tank containing iron burr and associated debris dislodged; (iii) means for receiving such portion including: (a) a separating tank having a predetermined internal configuration having extended surfaces made of paramagnetic material; receiving that portion with burrs of iron and associated debris dislodged and distributing internally in the separating tank adjacent to at least one extended surface of the paramagnetic material, and (c) magnetic field source means mounted contiguously to at least one extended area of the area to establish magnetic flux lines, internally in e the separator tank, for withdrawing and retaining the iron burr and magnetically associated debris while the portion moves inside the tank in relation to that at least one extended area, and (d) means for returning the solution, of which the burrs of iron and the associated waste, and also retained, have been separated to the main tank for continuous use in the line to clean the strip of rolled or flat rolled steel, and d) means to direct the continuous length of the strip of rolled steel flat from the cleaning system to the following means of finishing the strip on the line

Description

CONTINUOUS OPERATIONS OF CLEANING AND FINISHING OF ROLLED PLATED STEEL STRIP. DESCRIPTION OF THE INVENTION This invention relates to the finishing and cleaning operations of flat rolled steel strip or strip, and more specifically with the improvement of the protective adhesion against corrosion of finished coatings by improving the continuous cleaning methods and the apparatus. for flat rolled steel as supplied for coating finishing operations. Rolled flat steel as provided for corrosion prevention includes surface hot rolling contaminants and / or cold roll caliper reduction. The large capacity cleaning solution can be formed in the processing lines of stripped flat steel or bare in an attempt to extend the period of time during which a cleaning solution can be used without interrupting the line operations to replace the solution. cleaned. However, the increased capacities of the tank increase the detention time in order to allow the removal of large volumes of spent solution and replacement with a new chemically controlled cleaning solution. That so-called line of continuous strip termination operations can not be continuous when it is necessary to stop the operations of the finishing line for the removal and replacement of the cleaning solution. It has been found that by changing the levels of iron burr in the cleaning solutions there is an effect of decreasing the quality in the cleaning and final coating operations. It is an object of the present invention to allow flat rolled steel strip finishing operations without interruption by cleaning operations. The objects of the invention are to increase the uniformity of the continuous strip cleaning operations and the finishing operations, and to decrease the requirements to eliminate the scrap. Other advantages and contributions of the invention are more specifically set forth with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS The Figure is a general schematic arrangement for describing the operations of finishing line and cleaning of flat rolled steel strip that materializes the present invention; Fig. 2 is a schematic arrangement for describing a continued flat rolled steel strip cleaning mode; Figure 3 is a schematic cross-sectional view for describing functions of a particulate separation and holding tank for use in the apparatus of Figure 2; Figure 4 is a schematic elevation view taken along line 4-4 of Fig. 3 to describe operation when the contaminated solution enters the separator tank in the embodiment of Figure 3; Figure 5 is a schematic elevation view taken along line 5-5 of Figure 3 to describe the operation before and after the return of the solution cleaned from the tank of Figure 3; Figure 6 is a schematic elevation view taken along line 6-6 of Figure 3 to describe an internally contaminated solution distribution of the separation tank in the area described in relation to Figure 4; Figure 7 is a graphical presentation to describe the operational results of the invention for removing iron burr; Figure 8 is a graphical presentation for describing operational results of the invention by decreasing the iron content of a dipping galvanizing bath. Rolled flat steel, as provided after rolling and calibrated reductions of cold rolling, presents surface contaminants including iron burr and combinations of different forms of iron oxide. In certain operations, the incrustation of the hot rolled laminate may not be properly removed prior to cold rolling, and in addition, the level of iron flash increases during cold roll gauge reductions. Surface contaminants can also include semi-solid agglomerates when cold rolling lubricants are used, for example in rolling tempering operations. It has been found that the iron flash continues to accumulate in the high capacity cleaning tanks despite mechanical filtering. Other important factors of the operation and of the coating finish are also presented. It has been found that by significantly changing and increasing the levels of iron burrs in the cleaning solution it is harmful to the uniformly and also damagingly clearing for the finish coating in line. For example, increasing the levels of iron burr in an in-line cleaning solution increases the flash carried by the strip or release to the hot dip galvanizing bath and this increases the iron content in the galvanizing bath decreasing the effectiveness of the additions of aluminum to the bathroom. It has been found that continuous separation of contaminants in the surface area of the rolled steel improves in-line cleaning and improves finishing operations. Finishing operations for flat rolled steel includes such operations as hot dip coating with zinc, zinc alloys, leaded metal and the like, electroplated metal with tin, zinc, nickel zinc, chromium and chromium oxide, and coatings of prevention of temporary corrosion, and / or coating with a polymeric material in a solvent, electrolytically, or in a solid laminate or powder form. Referring to the termination line mode of Figure 1, the flat rolled steel strip of the coils 20, 21 has been produced from ingots cast by hot processing including hot rolling, during which the incrustation of the laminate and other contaminants of waste are formed on the surface areas. This is followed by cold rolling, often without sufficient removal of the incrustation from the hot rolling, and in addition the cold rolling increases the iron burrs on the cold rolled surfaces. Also, when the stripping or stripping is tempered by rolling, a lubricant is added so that the contaminated stripped surface areas may include semi-solid agglomerates. The front and rear edges of the detachment are roughened at 22 (FIG. 1) in preparation for feeding by shrink rolls 24 to the welder 26. The use of a ring tower helps to provide a flat length rolled steel strip detachment for a continuous length. interruption-free processing due to the discontinuity of the length of the strip. In continuous strip galvanizing operations, the finishing line operations have to be interrupted due to the cleaning operations of the detachment. Continuous mechanical filtration of large capacity cleaning solution tanks does not stop the increase of iron burr in such tanks. Iron burrs accumulate in the tanks at approximately 500 ppm in a two-week operating period of a continuous strip galvanizing line. And the non-uniformity in the continuous cleaning operation accompanies the increase in iron burr formation. The increase in the level of iron burr in a large capacity tank increases quantitatively the iron burrs carried by the detachment and therefore increases the iron content in the hot dip galvanization bath in the line. The loss of time during the interruption of operations and the elimination of large quantities of cleaning solution present great economic problems. However, the detriment to the uniformity of cleaning, the non-uniform coating adhesion, and the detriment to the rolled surfaces used in the heat treatment in line or in the annealing furnaces for continuous detachment present additional problems. The present teaching, by decreasing the iron burrs carried by the detachment, facilitate a significant decrease in the iron content of a hot dip dip galvanizing pewter or zinc bath. The continuous circulation control of the cleaning solution is preferred. A preselected portion of the cleaning solution from a main cleaning tank is continuously removed and a feedback duct is provided for the continuous return of the cleaning solution after extensive and controlled (a) separation, (b) removal and ( c) retention of surface contaminants by the feedback path. Mechanical continuous filtration of solid and semi-solid contaminants is preferred. As taught, the step is advantageously used to facilitate the desired control of solution removal and feedback. However special separation means are provided for the controlled separation, removal and retention of the iron burrs and associated debris from the cleaning of the detachment and the finishing operations. The configurational characteristics of a special tank that separates consistently, removes and retains solid and semi-solid contaminants described in more detail below in relation to Figs. 2-6. In the embodiment of Figure 1, the receiving means 36 initiates a controlled removal of the cleaning solution, with iron flash and associated waste, from a preselected location or locations of the cleaning tank 32 and / or the cutter 34. The ducts 37. 38 from the main cleaning tank are directed to the receiving means 36 in which the movement can be made by pumping systems. The mechanical filtering means can be included as part of the receiving means 36. When the mechanical filtering is used, the conduit 39, (shown with interrupted lines) returns the filtrate to the tank 32, after mechanically filtering the solid and semi-solid contaminants. . Then a special separation and retention separation structure (described in detail in relation to Figures 3-6) works to keep the cleaning and termination systems in line free of separate contaminants. Such controlled separation, removal and retention can be performed to eliminate the mechanical filtering, but preferably it is used in combination to provide the desired increase of the feedback line 42 of the separating structure 40 to complete a path of the solution from the receiver 36 through of the structure 40, and return to the main tank 32. The separation, removal and retention of the contaminants according to the invention allow a cleaning system that works continuously, which eliminates any need for a periodic change of large volumes of contaminated cleaning solution from a tank such as 32. In the continuous strip finishing operations of fig. 1 m, a cleaning solution rinses the place 48, and the enclosure of the strip 50, as indicated at 52, can be provided to carry a surface oxidation is minimized while the strip 50 is directed to the furnace 54. The atmosphere of the heat treatment furnace 54, is it controls to prevent oxidation of the surface areas of the strip, preferably, the furnace 54 is provided with a chemically reducing atmosphere, such as nitrogen and hydrogen. The path of the strip in the heat treatment furnace 54 can also be fitted or mounted in horizontal layers, or circulated vertically in a tower, to provide a treatment path of the steel substrate, which extends in length, for example several hundred at six hundred feet (approximately 540 meters) or more. The detachment is guided and supported by rollers in such furnaces and the treatment temperature is preselected from about 345 ° C to 700 ° (650 to 1250 F). From the furnace 54, the heat-treated strip 56 is routed through a chute 58 to a covering operation, schematically shown in FIG., which can be selected from a variety of finishing and coating methods. After finishing, several steps, such as leveling the strip or cutting into sheets, which is schematically represented by station 62, can be carried out, in the specific embodiment of Figure 1, the continuous strip is processed into coils 64, 66 of a given length. The continuous cleaning system of the steel strip of the invention includes a special separating means 70 (Figure 2) for the separation, removal, and retention of the iron flash and the associated waste. In the flat rolled steel continuous strip cleaning mode of FIG. 2, the contaminated surfaces of strip 72 are generally treated by a last dip, in a main tank having sufficient capacity to provide the desired path through a solution hot caustic; A carver or scraper 74 may also be used, the cleaning solution with accompanying contaminants is preferably removed continuously from a preselected location, and places, and is directed through a conduit such as 75 or 76. Control of the iron burr in the main tank is schematically indicated at 77. A filtering structure 78 that is mechanically operated continuously is preferably selected to provide a removal of a portion of the capacity of the main tank 73 at a controlled rate. The filtrate from which the iron burr has been mechanically filtered and the associated waste is continuously returned from the mechanical filtering structure 78 through the conduit 80 to the main tank 73. It has been found that the continuous mechanical filtering does not stop the formation of iron. Iron burr in large capacity cleaning solution tanks, such as 73, 74, used in continuous steel strip galvanizing lines. The solid and semi-solid contaminants purged from the mechanical filter structure 78 are buffed or moved by water jet, preferably preferably. Such a blown purge is directed through conduit 82 to the separation means including tank 70 for continuous separation and retention of solid and semi-solid contaminants. The separation tank 70 functions to retain such contaminants in a controlled manner so as to reduce the iron flash in the solution of the main tank 73 and / or so as to maintain a controlled and selected purity level for the iron flash in such a main tank. To carry out such functions, the tank 70 is made of non-ferromagnetic material that is identified and mentioned as paramagnetic. The configurational aspects of the separation tank 70 (Fig 3) and the paramagnetic material have no effect on the magnetic flow lines. The structural framework can be used to weld the bottom and bottom edges of a separator tank, such as 70, as long as the framework is selected so as not to influence the magnetic lines of the flow acting within the separation tank 70 as part of the invention. The paramagnetic material and the novel configuration of the separation tank 70 ('"Fig -3-6) are selected to provide an extra surface treatment of the purge, pushed with washing from the mechanical filtering structure, which carries iron burr, iron oxides, and semi-solid agglomerates Such iron flash and associated waste are controllably separated and retained in the separation tank 70. With such separation and retention, the clean solution of the separation tank 70 is returned to the main tank of the tank. cleaning solution 73. Continuous strip finishing line operations are provided, and these do not need to be interrupted because of the cleaning functions of the strip surface.An iron burr level, as selected for the main tank 73 (shown and described in relation to FIG. 7) is continuously controlled at a low level desired by the continuously operating cleaning system and by the method of the present invention. And this teaching facilitates the decrease of the iron content in a hot dip galvanization bath for the embodiment of Figure 1, where the decrease is controlled, as shown and described in relation to Figure 8, in greater detail.

Referring to the cross-sectional view of the contaminant separation tank 70 of Figure 3, the side walls, landfills, a dam site, a foam protector surrounding the tank outlet, and the sloped bottom panels are all formed of a paramagnetic material, such as polypropylene. An optimum capacity for tank 70 is preselected. A volume of approximately 500 gallons (approximately 2000 liters (it has been selected for use in a specific modality with a main tank of 5000 gallons 73 for a hot-dip galvanizing line of steel strip, which has an average steel steel pitch in the margin of approximately two million square feet (180,000 square meters) of surface area on one side and per day, the iron burr and associated waste already purged from the mechanical filtering structure 78 are continuously entrained by a liquid (Fig. 2) and are introduced through the inlet 84 of the separation tank 70 (Fig 3) and are distributed through the duct 86. The distribution through an internal surface width of the end wall panel 87 is best seen in the Figure 6. The flushing purge of the cleaning solution, with burr and associated debris, is directed and controlled in the tank 70 to carry out a separation and retention of the tank. to burr and such debris. Means for creating a magnetic field are mounted, so that they are not in contact with a caustic cleaning solution .. Preferably the field source is mounted at the entrance end 84 of the tank 70 on the external surface of the end wall 87. The magnetic field source is mounted in horizontal rows such as 88, 89, 90 (Figures 3, 4). A plurality of magnets can be mounted in each row (FIGS 3-5) across the width of tank 70; or a single magnet that extends across the width of the tank in each row (indicated by Figure 6). Although permanent magnets are preferred, electromagnets can be used. The establishment and placement of the magnetic field sources, as well as the magnetic force, are selected. As best seen in Figures 3-4, the magnets have been positioned to function as an external surface of the end wall 87; The retention structure 92 of the magnets is paramagnetic in order to avoid diminishing the influence of the magnetic field. The magnetic field extends through the wall of paramagnetic material 87 and is exerted inside the tank 70. The flow lines are basically established in a parallel relationship to the flat surface of the end wall 87 across its width, and they are established along their height, in the specific modality, by the preselection of the number of rows of magnets. The flow lines are not affected by the extreme wall material that is approximately one inch (2.5cm) thick polypropylene. The liquid-driven and mechanically filtered purge that enters, contaminated with flash and other debris, is distributed as shown in Figure 6, in a wide area while it is subjected to the magnetic force line in a large surface area. The contaminants in the pushed purge consist essentially of ferromagnetic material, such as iron flash and various iron oxides; other contaminants are associated or agglomerated, for example by rolling or rolling oils that are not ferromagnetic. Such contaminants are forced by the magnetic field towards an internal surface, for example, the end wall 87 on which the sources of magnetism are mounted. Some contaminants are held directly against the end wall and some are held in suspension in a cumulative solution, which will be described later, some descend under the influence of gravity to a defined area between the end wall 87 and the sloping floor panel 94 ( Fig 3) to be drained from tank 70.

The iron flash and associated drops are attracted and maintained in the tank 70. Although most of the purged solids are ferromagnetic, other semi-solid contaminants, which are bonded or agglomerated with the above, are also drawn to the end wall. and / or towards other surfaces to separate and stop in tank 70. As the liquid rises in space 95 (on the inlet side of the solution in tank 70) the solids are partially retained by the position of the landfill 96. The accumulating liquid must pass below the lower distal end 97 of the landfill 96 in order to fill the space 95, established in part by dam or dam 98 and located on the entry side of the tank mode 70 shown. The ferromagnetic contaminants, which are suspended and stopped in the accumulating liquid in tank 70, seem to attract and stop similar contaminants from the entering solution. An increase in the strength of the magnetic field can be selected to increase the influence of the magnetic field inside the tank. During the time that the solution is being assembled on the inlet side (space 95) the forming or cover solution can be added to space 99 on the return side of the dock 98 if the distribution and / or balance of the solution weight , or the forces due to such weight, are required due to the use of magnetic couple materials to form a unit tank structure (70). in practice for the bracing effect of the inclined panels 94, 100 and the use of side walls of two inches (5 cm) of thickness, they can provide an adequate reinforcement of the tank, manufactured to be unitary, with the paramagnetic panels using material of heated plastic welding, which is compatible with the panel material and also paramagnetic. The purge pushed by incoming fluid travels on the inner surface of the wall 87 with contaminants attracted by the magnetic field. Then, the solution moves along the bottom floor 94 under a distal end of the landfill 96 while filling the space 95. After passing through the openings in the dike 98 (or over a dike site if a dam of decreasing height), the liquid directed along the inclined floor panel 100 is brought under the influence of other sources of magnetic field, such as those shown in rows 102 and 103 along the return wall 104 (Figures 3 and 5). The remaining contaminants in the liquid (ßi exist) after the first separation, settlement and suspension process, are brought under the influence of the magnetic force lines established by the magnets of rows 102, 103. As the level of the cleaning solution rises in the space 99 above the lower distant end of the foam retainer 106 (which surrounds the return outlet 108) the return liquid, from which the contaminants have been separated and have been retained, directed, basically free of foam, towards the main tank 73. A return pumped can be provided as indicated in 109, for the main tank 73. The positioning of the tank 70 in relation to the main tank can allow the return by gravity, either supplying or returning, the tank 70 can be improved by pumps, where the physical placement of the line requires it. These configurational features of the separator tank 70, as presented and described in relation to FIGS. 3-6, provide extended surface surfaces for exposure to the magnetic field sources in order to assist in the control of the separation and retention of the flash and associated waste, providing ease for the removal of retained contaminants. That, for example, by draining compartments 95-99, simultaneously or separately. The cleaning of the burr from the tank 70 is facilitated by the configurational and functional aspects of the separator tank 70. It should be understood that the number of landfills, dam sites, floor panels, number of magnets, and number of placements for the magnets, can be increased, along with the increase in field strength or magnetic fields, to increase the magnetic influence in relation to the form of movement of The solution inside the separator tank 70. It has been found that the contaminants, attracted by the line of magnetic force tend to be suspended in and stop in the accumulating liquid. Such suspended contaminants extend a substantial distance towards the center of the tank, which is indicative of the strength of the magnetic field. Drain valves 108, 110, (Fig. 3), are positioned so that the cleaning solution from a tank compartment 70, po dreftft t * fcf-tmteiéft p \ i ¥ HÁ & carry the suspended pollutants. Each compartment can be cleaned or emptied by vacuum suction or drainage methods or combinations thereof. When a compartment is drained, the contaminants fall under the influence of gravity when the liquid moves towards the drainage area defined by each end wall and its respective sloped floor wall (94, 100). Without trying to establish it, it seems that the lines of magnetic force can be concentrated by the attracted ferromagnetic contaminants, and that this can help to attract other contaminants. The continuous liquid suction cleaning of an internal wall can be used, or time intervals can be selected to clean the individual compartments of the separation tank 70. A time interval can be selected based on empirical results, or dynamic measurements can be made during system operation of cleaned. For example, a purity level for the iron burrs in the main tank 73, 74 can be selected; and based on burr measurements at 77, for tank 73, (which would include tank 74 with withdrawal of liquid through line 76, for pushed purge going into 111), and for feedback coming out (at 112, from the separator tank 70, a desired purity level for the treatment tanks 73, 74, can be established and maintained), the level of the flash measured at 112, in the feedback line is maintained at or below the desired level for the tank 73, measured at 77. The effectiveness of the retention in the separator tank 70, is determined by the continuous comparison of the measurements at 112 and 112.

The selection of a low level of purity for the iron flash is taught by the invention to maintain a continuous cleaning and finishing operations, markedly improved. The effectiveness of the methods and apparatuses of the invention allows the selection of a desired level of purity for the iron burrs, for the return solution from the separator tank 70, for example, purity levels for the feedback solution from the tank 70, ß select notably below 100 ppm, for the flash; selecting a level of approximately 50 ppm, a burr reduction is provided by a factor of 10 to 15 times below the upper level of 500ppm, previously considered acceptable for treatment with a hot caustic cleaning solution. For example, the separation tank 70 can be operated to return the solution with a purity level of about 30 to 40 ppm, of iron flash, to decrease its level in the main tank 73, and this can be maintained at such a low level selected or lower, indefinitely. The effect of such a low level of flash on the iron content of an in-line hot dip galvanizing bath is an important contribution in the invention and is discussed in more detail in relation to Fig. 8.

By cleaning or flushing one or both of the interior spaces 95, 99 of the tank 70, the cleaning or finishing operations on the line will not be interrupted. Due to the short interval used in draining tank 70, there are several alternatives. As mentioned, each space (95, 99) can be emptied separately or simultaneously. In the specific embodiment of Figs. 2 and 3, the return filtrate of the mechanical filtered structure 78 may continue along the conduit 80, with the valves (114, 115), closed during the short interval required for draining and rinsing on both sides of the tank 70. The pushed or entrained purge of the structure 78 can accumulate in the chamber 116, and each accumulation treated after the draining and emptying of the tank 70, or the entrained purge can be sent to a tank that is separate or to a separate compartment of the tank 70, that has been emptied during the short time required to empty a compartment. A T connection, on the entry line can send drag purge to any compartment (95, 99), while the other is emptied. In general, the sequencing of emptying a tank 70, of small relative capacity, can be determined by measuring the level in ppm, of the flash in the solution from tank 70, in relation to the desired low level of iron burr selected and maintained in the tank. main tank, as described above. The intervals of approximately 1, 2 weeks to clean are satisfactory when operating at full capacity, the hot dip galvanizing line being cleaned with approximately 2 million square feet of strip surface, per side and day. In a functional mode, both spaces 95, 99, of tank 70, (Fig. 3), can be rapidly drained in 10 to 15 minutes. The inner walls of tank 70 are washed using a water pressure supplied with hose. The external mounting of the magnets is preferred in order to provide smooth internal surfaces, to facilitate the emptying of magnetically attracted ferromagnetic contaminants. Tank 70 can be drained and contaminants washed from its interior walls and bottom panels, occupying the entire procedure for a 500 gallon tank, approximately 20 to 30 min. The caustic cleaning solution can gradually be replenished as the tank 70 is filled after a periodical drain drain. A level selected for the caustic detergent is maintained in the main tank during the cleaning operation. The procedures for draining or otherwise removing the iron flash and associated debris from the tank 70 may be periodically or continuously revised to maintain the desired separation and retention efficiency within the tank., so that there is a basic uniformity of the desired level of purity as selected for the flash in the solution for the continuous operation of the main tank 73, as described above. Fig. 7 graphically shows the current or practical measurement of the purity level of tank burr 73, during operations in which the burr has been kept below an average level of approximately 50 ppm. A wide experimental period at that selected level is now about to pass the six months. The practice of the present invention indicates that the interruption of the termination line operations due to the cleaning operations of the strip, will not be required in the foreseeable future. To measure the burr in ppm, 5 thousand gallons of cleaning solution are equal to slightly more than 600 thousand ounces of solution, the present solution using 600 gause magnets can maintain a uniform low level of burr of less than about 300 ounces, in such a tank. Such a level constitutes a purity level of less than about 50 ppm. The level of flash as indicated in Fig. 7, has been maintained using magnets of approximately 600 gauss, supplied by Eriez Magnetice of Erie Pennsylvania, under the designation "Extra Power 600". Magnets of additional force reaching up to 1,500 gauss, and of an increased length equal to the width of the separation tank (as indicated schematically in Fig. 6), are being installed for experimental operation and collection of additional data, such magnets of the same supplier are obtained under the name "Super Power 1,500". The following tabulated data relates to cleaning solution operations for a continuous strip galvanizing line as described. TABLE I main tank 73 5,000 gallons tank withdrawal 73 approx. 2,700 g / h. filter apparatus 78 centrifugal separator Lakos In-Line tank separator 70 500 g tank length 70 8 feet tank width 70 4 foot tank height 70 4.25 feet purge rinsed to tank 70 approx. 400 gal / h magnetic field strength 600 gauss per magnet magnets per row 4 total magnets in extreme wall 12 total input side magnets in extreme wall 8 exit side pass through line 2 million feet continuous surface area galvanizing side and day A suitable centrifugal separator of continuous operation, comprises a Lakos In-Line separator, manufactured by Lakos Separators, E.U. , 1911 North Helma Avenue, Fresno, California 93727; Rinse or push through intervals or continuous mechanically filtered purged material is possible. Caustic detergent materials can be obtained from suppliers such as Elf Atochem North America, Inc., 2375 State Road, Cornwall Heights, Pennylvania 19020. FIG. 8 shows how the iron content of an in-line hot dip galvanizing bath has been reduced. (from about .072%, to .057%), based on daily measurements over a period of about 3 months (94 days), during which the flash in a main cleaning tank such as 73, in Fig. 2, it remained at the level as indicated in Fig. 7. The iron content of such a galvanizing bath continues to decrease due to the low level of iron burr that is introduced into the bath due to the cleaning operations of the strip in accordance with the present invention. As a result of the decrease of iron in the galvanizing bath, the aluminum deficiency increases and the aluminum iron waste decreases. The iron content of the galvanizing bath is expected to continue to decrease along the solid line of Fig. 8, at a substantially lower level. As the iron content decreases the aluminum additions to the bath, they can be further decreased and standardized based on the steel pitch, however, increased additions of aluminum will be required when the galvanizing coating forms an alloy with the steel substrate. Such a product in which the lightweight galvanized coating is entirely alloyed with the substrate steel by increasing the temperature of the steel strip requires the addition of aluminum. Although specific material dimensions and data have been established in describing a specific embodiment of the invention, it should be recognized that based on what has been presented, technicians can present operations that differ from those described without departing from the concepts of the invention.

Claims (21)

1. CLAIMS 1.- Continuous-running steel strip finishing line comprising: A. means supplying rolled coils of rolled piano steel, with surface areas in the flat laminate contaminated with iron burr and associated scrap, like those produced during the reduction of caliber, each winding provides an extended length of that flat rolled steel contaminated on the surface; B. means for unwinding the flat rolled steel coils, to provide rolling interconnected flat rolling steel in succession forming a continuous unitary flat rolled steel strip for the surface preparation and finishing of the surface areas; C. a strip surface cleaning system that continuously works for that surface contaminated flat laminated steel, which includes: (i) a main tank of pre-selected capacity to stop the surface cleaning solution and means to provide sufficient movement of the continuous strip through the main tank to dislodge the iron burrs and the associated waste from the surface areas of the strip;
2. (ii) means for removing a portion of the capacity of the cleaning solution from the main tank containing iron burr and associated debris dislodged; (iii) means for receiving such portion including: (a) a separator tank having a predetermined internal configuration having extended surfaces made of magnetic material; (b) input means for receiving that portion with iron burrs and associated debris dislodged and internally distributing in the separator tank contiguously to at least one extended surface of the paramagnetic material; and (c) means that are a magnetic field source mounted contiguously to at least one surface to establish magnetic flux lines, internally in the separator tank, in order to attract and retain the iron burr and the magnetically associated debris while the portion moves inside the tank in relation to that at least one extended surface; and (d) means to return the solution from which the iron burrs and associated debris have been separated, and also retained to the main tank to continue on the line of application of cleaning on the rolled or flat rolled steel strip; Y
3. D. Means for directing the continuous length of the steel strip from the cleaning system to the following means for terminating the strip in the line. Apparatus according to claim 1, characterized in that it includes oven means for heat treating the flat rolled steel strip located in the line after the surface cleaning system. 3. Apparatus according to claim 1, characterized in that the rear line strip of the finishing means includes: means for applying protective coating against corrosion to the cleaned steel strip, selecting the group means consisting of: (i) ) means of electrolyte metal plating; (ii) means for coating with hot dip metal; (iii) means for applying a polymer coating; (iv) combinations thereof.
4. 4. Apparatus according to claim 1, characterized by means of mechanical filtrates located to operate between the main surface cleaning tank and the separating tank.
5. 5. Apparatus according to claim 4, characterized in that said filtering means comprise a mechanical filtering structure continuously operable with means to receive that portion with discharged iron burrs and debris continuously associated from the main tank at a controlled rate, including means for mechanically filtering the burr and associated waste from that portion; and conducting means to return the filtering of the continuous function filter structure to the main tank.
6. Apparatus according to claim 5, characterized in that the continuous operating mechanical filter structure includes: means for continuously purging the burr and the associated waste as mechanical filtering from the withdrawn portion, to discharge the purged fluid contaminated with the filtered burr , and with associated waste; and means for directing that contaminated purged fluid to the inlet of a separator tank.
7. 7. Apparatus according to claim 1, wherein the separator tank is elongated and has an end wall contiguous with a longitudinal end of the tank and an end wall at the other longitudinal end; a dike means centrally located; and intermediate bottom panel between the longitudinal ends, the bottom panel includes: at least one bottom panel that acts with the dam to form at least one compartment for accumulating a solution on each longitudinal side of the dam; and at least one lower panel being inclined to provide a direction to the separate iron burrs and a gravitational direction for the burrs and the associated waste from the dike toward each of the longitudinally extended walls.
8. 8. Apparatus according to claim 7, including landfills in the separator tank to control at least partially the movement of liquid within the separator tank between its longitudinal ends; each of the configurational structures of the separator tank including such end walls, which have each other side by side, the place of the dike, landfill, and bottom panel are made of paramagnetic material.
9. 9. Apparatus according to claim 8, characterized in that the end wall of the separator tank, the side wall, the dike, the landfills, and the bottom panel are assembled to provide a unitary structure.
10. 10. The structure according to claim 1, characterized in that it includes for the control of the content of iron burr of the solution in the cleaning system.
11. 11. Apparatus according to claim 6, wherein the following in-line finishing means comprises means for galvanizing the continuous strip with a hot dip galvanizing bath.
12. 12. The structure according to claim 11, characterized in that it includes means for the controlled content of the iron bubbles in the solution to be returned from the separator to the main tank, to quantitatively decrease the iron burrs capable of associating with the steel strip when directed from the main tank of the cleaning system to the hot dip galvanizing bath; and means for controlling the hot dip bath to determine the quantitative decrease in iron content of the bath resulting from the quantitative decrease in flash in the main tank.
13. 13. - Continuous operating surface cleaning system for flat laminated steel strip that allows on-line operations of continuous termination of the strip cleaned on the surface, system comprising: A. Surface cleaning means including a main treatment tank containing sufficient surface cleaning solution for the treatment of the contaminated surface areas of the continuous steel strip, to dislodge the flash and the associated waste from those areas in preparation for subsequent operations at the continuous strip finishing line; B. means for removing a portion or portion of the cleaning solution from the main tank, including burrs and waste associated with a controlled rate during continuous cleaning operations; C. means for directing the portion of solution withdrawn to the separating means for separating and retaining the iron burrs and the associated waste; D. the separating means includes: (i) a separator tank made of a paramagnetic material that has an inlet and outlet that together with the internal surfaces provide a configuration that directs the movement of that portion within the separator tank; and (ii) means for creating a magnetic field source arranged to establish lines of magnetic flux contiguous to at least one of the surfaces within the separator tank, in order to attract and retain the iron flash and the associated waste inside the tank. separator; and E. means to continually return the solution, from which the burrs and the associated waste have been removed and have been retained in the separator tank by its outlet to the main tank of the cleaning solution for continuous use in that system. cleaned of surface.
14. 14. Apparatus according to claim 13, characterized in that the internal configuration means define separate compartments in the separator tank to expose the portion of the contaminated cleaning solution that has been treated to more than one source of adjacently located magnetic field.
15. 15. Apparatus according to claim 13, further including means for controlling the iron flash of the solution in the inlet and outlet means, to control the iron burrs of the separator tank.
16. 16. Apparatus according to claim 15, characterized in that magnetic field sources are provided for the separator tank, to keep the burr in the main tank below a preselected level.
17. 17. Apparatus according to claim 13, characterized in that they define when there are two separate compartments, one on each side of the site centrally located for the dike, and means for removing the iron burrs and associated waste retained from each of them. the compartments to allow the selection of the consious group to remove such waste from each compartment, either separately or to remove the waste from both compartments simultaneously.
18. 18. Apparatus according to claim 17, wherein the separator tank is elongated having input means at one longitudinal end; and exit means located at the other longitudinal end of the separator tank.
19. 19. - Method for providing a cleaning system with continuously operable solution for use to clean iron burrs and other associated surface debris from a flat rolled steel strip, for a subsequent processing on a continuously operable steel strip finishing line, characterized in that; A. a main solution tank is provided in line and means to receive the steel in the form of continuous strip for the purpose of surface cleaning; B. provide for the cleaning of the surface of the continuous steel strip by: (i) selecting a capacity of cleaning solution in the main tank that allows the continuous removal of a preselected portion of the solution already contaminated with iron debris and debris associated; (ii) continuous removal of the preselected portion of that capacity from the main tank that is used for surface cleaning of the steel strip to remove the burrs and the associated waste; (iii) directing that removed portion to continuous mechanical filtering media with return of filtrate to the main tank, from which the iron flash and waste have been mechanically filtered; (iv) fluidly pushing the mechanically filtered purge including the flash and associated debris from the mechanical filter medium; (v) directing that purge pushed or rinsed with fluid to a separator tank to separate and retain the iron burr and associated waste, the separator tank uses paramagnetic material having a configuration that defines: (a) an input means for the purge rinsed,

    (b) magnetic field source means arranged to attract and retain the iron burr and the associated waste formed by the contaminants inside the separator tank; (c) means of exit to return the cleaning solution from which the iron burrs and the associated waste have been separated and retained. (vi) removing said cleaning solution from the outlet medium of the separating tank and directing it for its return to the main tank of the cleaning solution; and (vii) continuing that controlled circulation of the cleaning solution with the separation and retention of the flash and the associated waste, externally to the main tank to establish and maintain a desired pre-selected level of the iron flash in the main tank.
20. 20. Method according to claim 19, characterized in that it includes the control of the content of iron burr of the solution that Be uses in the main tank; control the content of the iron burr of the cleaning solution retained in the separating tank; and continuously operating the strip cleaning system to establish and maintain a level for the iron burr in the main tank that is less than about one hundred ppm.
21. 21. Method for decreasing the iron content of a hot dip galvanizing bath placed in line that is used in continuous rolling operations of rolled steel or flat rolled comprising the steps of: providing continuous flat rolled steel strip windings as it is produced by the reduction of the caliber, including cold rolling, resulting in flat laminated surface areas that are contaminated with iron burr and associated waste; then directing that strip to a main tank of high capacity surface cleaning solution; continuously withdraw a preselected portion of the capacity of the main tank to perform mechanical filtering and feedback of the filtrate to the high capacity main tank; pushing with fluid the mechanically filtered purge to direct it to a separator tank made of paramagnetic material; separating and retaining the iron burrs and the associated waste in that separator tank, exposing them to the action of a magnetic field on an extended surface of the separator tank; return the cleaning solution with less than about one hundred ppm, from iron burr to the main tank to reduce the level of and keep the level of the iron burr in the main tank to less than one hundred ppm, decreasing the iron burr cover by hot-dip galvanizing bath, thereby decreasing the iron content of the galvanizing bath.

    SUMMARY A continuous steel strip cleaning system, including a special separation means (70), for the separation, removal and retention of the iron burrs and the associated waste is presented. In the mode of cleaning a continuous strip of flat rolled steel, the contaminated surfaces of the strip (72), are generally treated by at least a partial immersion, in a main tank (73), which has sufficient capacity to provide the travel desired through a hot caustic solution. The cleaning solution with accompanying contaminants is preferably removed continuously from a preselected location, or preselected locations and directed through a conduit such as (76). The control of the iron burr in the main tank (73) is indicated schematically in (77). A continuously operable mechanical filtering structure (78) is preferably selected to provide a removal of a portion of the total capacity of the main tank (73) at a controlled rate. A filtrate from which the burr and the associated waste have been mechanically filtered is continuously fed back into the main tank (73), from the mechanical filtering structure (78), through a conduit (80).