Abstract:
A device for pickling strip-shaped or wire-shaped material has guiding mechanisms for feeding and guiding the material in a serpentine path formed by several loops having vertical sections and liquid delivery devices positioned to bring the material into contact with a pickling liquid. At least two vertical pickling cells are provided in the apparatus, each with two vertical sections. Each of the individual cells are activated and deactivated optionally and independently of one another to be able to change or set the effective pickling length exactly, even in purely chemical pickling processors, and thus obtain a precisely definable, variable pickling effect, while retaining the space-saving design of the plant.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to an apparatus and process for pickling a continuous strip material in the form of a continuous sheet or continuous wire. The invention is particularly directed to an apparatus having guiding mechanisms for the continuous strip material for feeding the strip material in several loops having vertical sections and liquid delivery devices to bring the strip material into contact with the pickling liquid.  
         BACKGROUND OF THE INVENTION  
         [0002]    Various continuous pickling devices are known in the art for applying a pickling liquid to a continuously moving strip of material. Many of these devices include a bath where the strip material is immersed in the bath as it is conveyed through the device. Other continuous pickling devices including one or more sprayers to spray a continuous stream of the pickling liquid onto the surfaces of the continuous strip.  
           [0003]    Another type of pickling apparatus is disclosed in Austrian Patent No. 206247 B1. This patent discloses a pickling apparatus having a pickling tower that contains one or more vertically oriented loops of the continuous strip material. Spray nozzles are provided in the tower to apply the pickling medium directly to the strip material.  
           [0004]    A similar apparatus is disclosed in Austrian Patent No. 218331 B1. The patent discloses the pickling apparatus having a pickling tower where the pickling medium is sprayed onto the strip material which is guided vertically in several loops. The apparatus includes a concentric nozzle surrounding the strip material so that the pickling medium flows downward over the strip material. The pickling apparatus disclosed in these patents provide a long length of the strip material that is subjected to the pickling liquid while minimizing the floor space required for the apparatus.  
           [0005]    These prior pickling apparatus that include vertical sections have a fixed length of the strip material that is contacted with the pickling medium. Thus, it is not possible to vary the pickling effect by changing the length of the strip material that is contacted with the pickling medium such as in purely chemical pickling processes. Conventional horizontal pickling tanks where the strip material is fed through a pickling tank filled with the pickling medium do not allow variation in the pickling effect by the pickling medium. One proposal to control the pickling effect is disclosed in German Patent Application No. 4240572 A1. The apparatus disclosed in this patent application having horizontal sections includes additional injection nozzles within the pickling tanks to control the amount of the pickling medium contacting the strip material. This apparatus does not allow the control of the pickling action in selected areas or to distinguish between areas within the pickling tank where a strong pickling action takes place compared to a poor pickling action. In addition, this apparatus has a predetermined length of the pickling tank and the length of the strip material that is subjected to the pickling medium.  
           [0006]    Another example of a horizontal pickling tank is disclosed in U.S. Pat. No. 4,807,653, which discloses a series of consecutive pickling cells. The pickling cells are sealed off by rollers at each end which convey the strip material through the apparatus. The rollers do not permit complete separation of the individual pickling cells or sections. Although the squeezed rollers remove a portion of the pickling medium, there is always a certain amount of the pickling medium that remains on the strip material and is carried into the subsequent pickling cells. The pickling medium is also carried into the rinse station where the strip material is contacted with a rinsing or flushing medium. This apparatus also does not allow a change in the length of the strip material that is subjected to the pickling medium.  
           [0007]    The prior pickling apparatus are generally effective for their intended use but have experienced various limitations. Accordingly, there is a need in the industry for an improved pickling apparatus and process for controlling the pickling effect on the strip material.  
         SUMMARY OF THE INVENTION  
         [0008]    The present invention is directed to a process and apparatus for pickling a continuous strip of material such as a continuous sheet or continuous wire-shaped material. The invention is also directed to an apparatus that is able to control the effective length of the strip material within the pickling apparatus, control the extent of the pickling effect on the strip material and to control the effective length of the strip material that is contacted with the pickling medium.  
           [0009]    Accordingly, a primary aspect of the invention is to provide a pickling apparatus that is able to select and change the effective pickling length of a strip material within the pickling apparatus in a precise manner. The effective pickling length as used herein refers to the length of the section of the strip material that is being contacted with and treated by the pickling medium at any one time as the continuous strip material is conveyed through the pickling apparatus.  
           [0010]    A further aspect of the invention is to provide a pickling apparatus and process that can be a purely chemical pickling process where the pickling effect is controlled and adjustable while reducing the amount of floor space required for the pickling plant and apparatus.  
           [0011]    Another aspect of the invention is to provide a pickling apparatus and process where the apparatus includes a plurality of liquid treating cells arranged in sequence where each of the cells can be selectively controlled to control the pickling effect on the continuous strip material within the respective pickling cell.  
           [0012]    Still another aspect of the invention is to provide a pickling apparatus and process where the apparatus includes a plurality of guide members for feeding a continuous material in a serpentine path defining a plurality of loops where each loop defines a pickling cell. The supply and flow of pickling medium delivered to each of the pickling cells is monitored and controlled to control the effect of the pickling medium on the length of the continuous material within the respective pickling cell and the pickling effect of the continuous material as it moves continuously through the apparatus.  
           [0013]    A further aspect of the invention is to provide an apparatus having at least two vertical pickling cells where each of the pickling cells includes two vertical sections of the strip material that is subjected to the pickling medium. The supply of the pickling medium to each of the individual pickling cells is activated and deactivated independently of one another to selectively control the amount of the pickling medium supplied to the strip material within a respective pickling cell and within the entire apparatus. In this manner, the pickling effect on the strip material can be controlled without changing the speed of the strip material through the apparatus. The vertical arrangement of the pickling cells allows a large pickling length of the strip material to be treated and allows selected changes in the effective length of the strip material that is subjected to the pickling medium. Selectively and independently activating or deactivating the entire pickling cell or portions of the pickling cell provides improved drainage of the pickling medium from the strip material to reduce the amount of pickling medium that is transferred to subsequent cells or to the rinsing station.  
           [0014]    A further aspect of the invention is to provide a pickling apparatus having a plurality of pickling cells where each of the pickling cells include a guide assembly for defining at least two vertical sections in the strip material being processed. A liquid supply device is positioned to supply a flow of the pickling medium against each of the vertical sections of the strip material. The supply devices for each of the vertical sections are connected to a control device to selectively control the flow of the pickling medium to each of the supply devices and independently of one another within a pickling cell. Selectively actuating each of the liquid supply devices effectively subdivides the pickling apparatus into pickling zones so that each pickling zone can be controlled to adjust the effective length of the strip material being subjected to the pickling medium.  
           [0015]    Another aspect of the invention is to provide a pickling apparatus and process having at least five pickling cells provided in sequence where each of the pickling cells include two vertical sections of the continuous strip material. Each of the vertical sections include a supply device for supplying a pickling medium to each of the vertical sections. By selectively controlling the supply devices and controlling the amount of the pickling medium directed to the strip material, the effective length of the strip material subjected to the pickling medium can be adjusted between 0 and 100% in 10% increments, thereby providing precise adjustments in the extent of the pickling process that is desired.  
           [0016]    The various aspects of the invention are basically attained by providing a pickling apparatus for pickling a continuous material. The pickling apparatus comprises a first liquid treating cell that has a feed device for continuously feeding the continuous material in a substantially vertical loop with first and second vertical sections. A first fluid supply device supplies the pickling liquid onto the continuous material on the first and second vertical sections. At least one second liquid treating cell has a feed device for receiving the continuous material from the first liquid treating cell and continuously feeding the continuous strip in a substantially vertical loop which has first and second vertical sections. A second fluid supply device supplies the pickling liquid onto the continuous material on the two vertical sections. A control device is connected to the first liquid supply device and to the second liquid supply device for independently controlling a flow of the pickling liquid from the first liquid supply device and the second liquid supply device.  
           [0017]    The aspects of the invention are also attained by providing a pickling apparatus for pickling a continuous material. The pickling apparatus comprises a plurality of liquid pickling cells arranged in sequence for treating the continuous material with a pickling liquid. Each of the liquid pickling cells has a first guide roller at a top end of the treating cell and a second guide roller at a bottom end of the cell for guiding the continuous material in a substantially vertical loop which has a first vertical section extending between the first guide roller and second guide roller and a second vertical section extending between the second guide roller and a first guide roller of an adjacent liquid pickling cell. Each cell has a liquid supply device for supplying the pickling liquid to the first and second vertical sections of the continuous material. A control device is coupled to the liquid supply for selectively and independently controlling the supply of pickling liquid to each cell.  
           [0018]    The various aspects of the invention are further attained by providing a process of pickling a continuous steel material. The process comprises the steps of feeding the continuous steel material through a plurality of sequentially arranged liquid treating cells. Each of the cells has an upper guide roller and lower guide roller to guide the steel material in a substantially U-shaped loop within each of the cells and form a first and second vertical section. A dispensing device is provided in each of the cells for directing a pickling liquid onto each of the first and second vertical sections. Each dispensing device is selectively controlled to selectively operate the dispensing device within a cell independently of the operation of a dispensing device of another cell.  
           [0019]    These and other aspects of the invention will become apparent from the following detailed description of the invention, which in conjunction with the annexed drawings, disclose various embodiments of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0020]    The following is a brief description of the drawings in which:  
         [0021]    [0021]FIG. 1 is a schematic view of the pickling apparatus in one embodiment of the invention showing the pickling cells of the apparatus arranged in sequence;  
         [0022]    [0022]FIG. 2 is a schematic diagram of the pickling apparatus in another embodiment of the invention showing a first section having a plurality of pickling cells arranged in sequence followed by a second section positioned downstream of the first section of pickling cells; and  
         [0023]    [0023]FIG. 3 is a schematic diagram of another embodiment of the invention showing the plurality of pickling cells arranged in first and second sections and a supplemental spray nozzle for supplying additional pickling medium to the strip material. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0024]    The present invention is directed to an apparatus and process for contacting a continuous material with a treating liquid. The invention is particularly directed to an apparatus and process for supplying a pickling liquid medium to a continuous material in a controlled manner to control the pickling effect on the continuous material. The apparatus and process are able to control the pickling effect within selected pickling cells in the apparatus and control the complete pickling effect as the continuous material passes through the apparatus.  
         [0025]    The continuous material that is treated by the apparatus and process of the invention is typically steel or stainless steel. The steel or stainless steel continuous material can be a hot rolled or a cold rolled steel or stainless steel as known in the art. The continuous material can be in the form of a continuous strip or sheet or in the form of a wire or rope. As used herein, the continuous material or continuous strip material refer to a continuous substrate that can be in any suitable shape or form that can be continuously fed through the apparatus and continuously treated with a pickling solution. The continuous material is supplied from a supply roll or manufacturing facility, fed through the pickling apparatus and recovered on a spool.  
         [0026]    The pickling medium is typically a pickling acid or mixed acid as known in the art of pickling steel and stainless steel. The pickling acid can include an acid selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, phosphoric acid, and mixtures thereof.  
         [0027]    [0027]FIG. 1 is a schematic diagram of a pickling apparatus in a first embodiment of the invention. Referring to FIG. 1, apparatus  10  includes a feed and guide assembly  12  for continuously feeding a continuous material  14  through apparatus  10  in a substantially serpentine path. The continuous material hereinafter is referred to as strip material  14  which can be in any suitable form such as a sheet, flat strip, wire or rope. Guide assembly  12  defines a plurality of pickling cells  16  arranged in sequence from an inlet end  18  to an outlet end  20 .  
         [0028]    Strip material  14  is guided around a first guide roller  22  positioned at the inlet end  18  of assembly  10 . Guide roller  22  receives strip material  14  from a supply (not shown) and directs the strip material in a substantially downward direction to a second guide roller  24 . Second roller  24  is positioned below first guide roller  22  to direct strip material  14  in a substantially vertical path while continuously conveying strip material  14  through apparatus  10 . The length of strip material  14  extending between first guide roller  22  and second guide roller  24  defines a first vertical section within the respective pickling cell  16 . An upper roller  26  is positioned above second roller  24  and adjacent the first guide roller  22  to direct strip material  14  upwardly from second roller  24  and to define a second vertical section of strip material  14  extending between second roller  24  and upper roller  26 . First guide roller  22 , second roller  24  and upper roller  26  define a first of the pickling cells  16  for treating strip material  14  with a pickling liquid.  
         [0029]    As shown in FIG. 1, a plurality of the upper rollers  26  are spaced apart along the length of apparatus  10 . A plurality of lower rollers  24  are also spaced apart and oriented to align with upper rollers  26  for continuously guiding strip material  14  in the serpentine path. Each of the lower rollers  24  cooperate with upper rollers  26  to define the respective pickling cells  16  and to form a first vertical section  28  and a second vertical section  30  of strip material  14  within each cell  16 . As shown in FIG. 1, each upper roller  26  cooperates with two adjacent pickling cells  16  to guide strip material  14  from second vertical section  30  of a first pickling cell to a first vertical section  28  of an adjacent pickling cell  16 . As shown, first vertical section  28  and second vertical section  30  of strip material  14  are substantially parallel and oriented substantially perpendicular to the longitudinal dimension of apparatus  10 . In this manner, each pickling cell  16  includes two vertical sections of strip material  14 . It is to be understood that strip material  14  is preferably being continuously conveyed through apparatus  10  so that the various sections of strip material  14  are intended to refer to the strip material within a specified area at any one time.  
         [0030]    In the embodiment illustrated in FIG. 1, apparatus  10  includes five pickling cells  16  arranged in sequence for continuously receiving strip material  14  and providing an effective pickling length for treating the strip material. The outlet end  20  of assembly  10  includes a guide roller  8  positioned above the downstream lower roller  24  for directing strip material  14  to a subsequent processing station or to a suitable winding roll as desired. A squeeze or press roller  34  is provided at outlet end  20  to cooperate with second guide roller  32  to remove the pickling medium or rinse medium from strip material  14  before exiting apparatus  10 . Although five pickling cells  16  are illustrated in the embodiment of FIG. 1, the actual number of pickling cells can vary depending on the spacing between the lower rollers  24  and the upper rollers  26  and the desired effective length of the pickling zone subjected to the pickling medium.  
         [0031]    The height of the individual pickling cells  16  can vary depending on the number of pickling cells within apparatus  10  and the desired maximum and/or minimum effective pickling length of the strip material to be treated with the pickling medium. Typically, each vertical section of strip material  14  within each pickling cell  16  has an effective pickling length of about 1 to about 10 meters, with lengths between about 3 and 6 meters being preferred. In more preferred embodiments, the effective pickling length for each vertical section of strip material  14  within each pickling cell is about 3.5 meters. In this manner, the effective pickling length of apparatus  10  is about 35 meters in the embodiment of FIG. 1 where five pickling cells  16  are provided. By arranging the upper and lower rollers to form the serpentine path of the strip material  14 , the horizontal length of apparatus  10  is typically about 10 meters, which is less than ⅓ of the length of a conventional horizontal pickling line apparatus.  
         [0032]    Referring to FIG. 1, a liquid supply device  36  is provided within each pickling cell  16  for supplying a pickling medium to strip material  14  as it is conveyed through each pickling cell  16 . Typically, liquid supply device  36  is positioned at an upper end within each pickling cell  16  so that the pickling medium is supplied to strip material  14  at an inlet end of each pickling cell  16 .  
         [0033]    In preferred embodiments, liquid supply device  36  includes two liquid dispensing units  38  within each pickling cells  16 . Liquid dispensing units  38  in the embodiment illustrated include a spray nozzle  40  positioned on opposite sides of strip material  14  to direct a spray  42  of the pickling medium against opposite sides of strip material  14 . Preferably, liquid dispensing units  38  are positioned at an upper end of first horizontal section  28  and second horizontal section  30  so that the pickling medium flow downward over the sections of strip material  14 . Liquid dispensing units  38  in one embodiment also include a dam  44  to form an overflow  46  of the pickling medium to ensure a continuous layer of the pickling medium on first vertical section  28  and second vertical section  30  of strip material  14  within each pickling cell  16 . Overflow  46  of pickling medium flows downwardly to provide continuous coating of strip material  14  with the pickling medium.  
         [0034]    In preferred embodiments, each liquid dispensing unit  38  is supplied with the pickling medium through a conduit  48  which is connected to a main supply line  50 . Each conduit  48  includes a control valve  52  for independently controlling the flow of the pickling medium to each spray nozzle  40 . Each valve  52  is connected to a control device  54 . Control device  54  selectively actuates each valve  52  independently of one another to control the flow and supply of the pickling medium to each horizontal section within a given pickling cell  16  and to control the flow of pickling medium independently to each of the pickling cells  16 . Control device  54  can be a microprocessor or other suitable control device capable of selectively actuating each valve  52  as known in the art. Control device  54  is able to selectively activate or deactivate liquid dispensing units  38  by opening and closing valves  52  within each of pickling cell  16  independent of the treating process in another cell.  
         [0035]    A collection tank  56  is positioned below each pickling cell  16  to collect the pickling medium that drains from strip material  14  as it passes through each of the pickling cells  16 . Collection tank  56  includes an outlet pipe  58  which supplies the collected pickling medium to a pump  60 . Pump  60  pumps the pickling medium from collection tank  56  to supply line  50  to recirculate the pickling medium. A suitable filter  62  and a feed device  64  for supplying fresh or regenerated pickling acid to the system are included in supply line  50 . In this embodiment, a single collection tank  56  is provided to collect the spent pickling medium that drains from the individual pickling cells.  
         [0036]    In one embodiment, apparatus  10  can include an adjusting assembly  66  connected to one or more of lower rollers  24  to selectively adjust the height of lower roller  24  with respect to the adjacent upper rollers  26 . Adjusting assembly  66  is capable of selectively adjusting the height of the lower roller  24  to increase or decrease the length of a first vertical section  28  and a second vertical section  30  in a respective or adjacent pickling cells  16 . In this manner, the effective pickling length of the strip material can be selectively adjusted.  
         [0037]    Control device  54  selectively operates valves  52  to control the flow of pickling medium within apparatus  10  and to control the amount of pickling medium that contacts the strip material  14 . In one embodiment, control device  54  can actuate each valve  52  to supply pickling medium to each spray nozzle  40  and the amount of pickling medium supplied to each spray nozzle  40  to provide a maximum pickling effect on strip material  14 . In embodiments where it is unnecessary or undesirable to treat strip material  14  with a maximum amount of the pickling medium that is capable of apparatus  10 , control device  54  can selectively and independently close one or more valves  52  to reduce the flow of pickling liquid that is supplied to strip material  14 . Valves  52  can be closed in a respective pickling cell  16  so that no pickling medium is supplied to strip material  14  in the respective pickling cell  16 . When valves  52  of a pickling cell  16  are closed so that no pickling medium is supplied, it is generally preferred to deactivate one or more of the pickling cells at the upstream end of apparatus  10 . In other embodiments, a single valve  52  for each pickling cell  16  is closed so that only one of the two spray nozzles in each pickling cell  16  supplies pickling medium to the strip material  14 . Either of valves  52  can be deactivated depending on the desired pickling effect.  
         [0038]    In embodiments where one or more of valves  52  are closed, the rinse liquid can be supplied to the strip material to keep the strip material wet or damp, thereby avoiding streaking or staining. In one embodiment, mist projector or mist spray devices  68  are provided in at least one pickling cell  16  that is capable of supplying a rinsing liquid to contact strip material  14 . In one embodiment, mist spray device  68  is operatively connected to control device  54  to control the timing and amount of the spray, and to activate and deactivate mist spray device  68 . Typically, mist spray device  68  forms a light mist or spray of a rinse liquid that is sufficient to prevent strip material from drying without completely rinsing strip material as in a conventional rinsing station. The mist spray device  68  is preferably positioned next or proximate dispensing units  38  on both sides of continuous strip material  14  as shown in FIG. 1. Mist spray devices  68  arranged close to liquid dispensing units  38  can provide a continuous mist that can rinse along the vertical sections of the continuous strip material to prevent the continuous strip material from coming into contact with the atmosphere, thereby preventing or inhibiting oxidation. In one embodiment, mist spray devices  68  are actuated in response to a deactivation of liquid dispensing unit  38  in a respective liquid treating cell to prevent continuous strip material  14  from drying and being exposed to the air. In the embodiment illustrated, the downstream liquid treating cell includes mist spray devices  68 , although more than one or all of the cells can be provided with mist spray devices.  
         [0039]    Apparatus  10  generally uses a chemical pickling process where the strip material is treated with a pickling acid or mixed acid. In one embodiment, apparatus  10  can include electrodes  70  to apply an electric potential to one or more sections of strip material  14 . As shown in FIG. 1, electrodes  70  are connected to one upper roller  26  and lower roller  24  within a pickling cell to apply an electric potential to strip material  14  within the respective pickling cell. Electrodes  70  are connected to a suitable electric power source  72 . The current and voltage applied to electrodes  70  are as known in the art for the electrolytic treatment of steel and stainless steel. In the illustrated embodiment, one section is provided with electrodes to electrolytically treat the strip material. In other embodiments, more than one section or pickling cell can electrolytically treat the strip material.  
         [0040]    The effective length of the treatment within each pickling cell  16  is dependent on the distance between spray nozzles  40  and lower rollers  24 . Preferably, liquid dispensing units  38  provide a continuous flow of the pickling medium to form a continuous film that flows downwardly toward lower roller  24 . In one embodiment, liquid dispensing units  38  can be mounted on an adjustable rack  74  for selectively adjusting the height of liquid dispensing units  38  with respect to lower roller  24  within a given pickling cell  16 .  
         [0041]    [0041]FIG. 2 shows a pickling apparatus  80  in a second embodiment of the invention. Pickling apparatus  80  is similar to the embodiment of FIG. 1 so that identical elements are identified by the same reference number with the addition of a prime. As shown in FIG. 2, apparatus  80  includes a plurality of lower rollers  24 ′ and upper rollers  26 ′ to guide strip material  14 ′ in a serpentine path through apparatus  80 . Liquid dispensing units  38 ′ are provided within each pickling cell  16 ′ to supply pickling medium to first vertical section  28 ′ and second vertical section  30 ′ within each pickling cell  16 ′.  
         [0042]    In the embodiment of FIG. 2, apparatus  80  has a first pickling section  82  positioned upstream with respect to apparatus  80  and a second pickling section  84  positioned downstream of first pickling section  82 . An upper roller  86  is positioned to guide strip material  14 ′ from first pickling section  82  to second pickling section  84 . A press roller  88  cooperates with roller  86  to remove the pickling medium from strip material  14 ′ before feeding strip material  14 ′ to second pickling section  84 .  
         [0043]    First pickling section  82  includes a collection tank  90  positioned below the respective pickling cells  16 ′ for collecting the pickling medium. In the embodiment illustrated, first pickling section  82  includes three pickling cells  16 ′. The collected pickling medium is directed by a pump  92  to a supply line  94 . Supply line  94  supplies the pickling medium through valves  52 ′ and conduits  48 ′ as in the previous embodiment. A collection tank  96  is positioned below pickling cells  16 ′ of second section  84  to collect the pickling medium draining from strip material  14 ′. The pickling medium is supplied by a pump  98  to a supply line  100 . Supply line  100  feeds the pickling medium through valves  52 ′ of conduits  48 ′ to liquid dispensing units  38 ′ within second pickling section  84 .  
         [0044]    In the embodiment of FIG. 2, first pickling section  82  and second pickling section  84  supply a pickling medium to the continuous strip  14 ′. Control device  54 ′ independently actuates each dispensing unit  38 ′ within each of the pickling cells  16 ′ of first pickling section  82  and second pickling section  84 . In one embodiment, second pickling section  84  can include a rinse liquid to rinse the pickling medium from strip material  14 ′ before discharging from pickling apparatus  80 .  
         [0045]    In FIG. 3, another embodiment of the pickling apparatus  104  is shown. Pickling apparatus  104  is substantially similar to apparatus  10  and apparatus  80  so that identical elements are identified by the same reference number with the addition of a prime.  
         [0046]    Liquid dispensing units  38 ′ include an overflow to form a waterfall-like flow of the pickling medium onto strip material  14 ′. The continuous flow of the pickling medium produces a highly turbulent descending film along strip material  14 ′ as it is conveyed through apparatus  104 . In the embodiment of FIG. 3, secondary spray nozzles  106  are provided within one or more of pickling cells  16 ′ to direct a supplemental spray of the pickling medium onto strip material  14 ′. As shown in FIG. 3, a supply line  110  extends from collection tank  90 ′ to four secondary spray nozzles  106  positioned on opposite sides of strip material  14 ′. A high pressure pump  112  is provided to supply the pickling medium from first collection tank  90  to secondary spray nozzles  106 . In alternative embodiments, spray nozzles  106  can be connected to a rinse liquid such as water to direct a rinse liquid directly to strip material  14 ′.  
         [0047]    In the operation of apparatus  104 , selected pickling cells  16 ′ and liquid dispensing units  38 ′ can be deactivated to selectively control the effective length of the pickling treatment of strip material  14 ′. Typically, pickling cells  16 ′ at the upstream end of apparatus  104  are deactivated when less than all of the pickling cells  16 ′ are required to supply the pickling medium. Secondary spray nozzles  106  can supply a rinse liquid to strip material  14 ′ within the upstream pickling cell  16 ′ to keep strip material  14 ′ wet or moist to prevent streaking and staining.  
         [0048]    While various embodiments of the invention have been described herein, it will be appreciated that various changes and modifications can be made without departing from the scope of the invention as defined in the appended claims.