Patent Publication Number: US-9845993-B2

Title: Method and arrangement for removing outgrowth in a suspension smelting furnace

Description:
FIELD OF THE INVENTION 
     The invention relates to a method for removing outgrowth in a suspension smelting furnace. 
     The invention also relates to an arrangement for removing outgrowth in a suspension smelting furnace. 
     Outgrowth comprising for example partially melted fine solids fed by the concentrate burner of a suspension smelting furnace may be built-up in the interior of a reaction shaft of a suspension smelting furnace reaction shaft, especially in the uppermost part of the interior of the reaction shaft in the vicinity of the concentrate burner. Such outgrowth has a negative effect on the suspension smelting process. 
     It is known in the art to manually remove such outgrowth manually. For this purpose, the reaction shaft can be provided with openings. This manual work is however both dirty and physically exhausting. 
     Publication WO 2012/001238 presents a suspension smelting furnace comprising a reaction shaft having a reaction shaft structure, a lower furnace, an uptake, and a concentrate burner for feeding at least reaction gas and fine solids such as copper or nickel concentrate into the reaction shaft of the suspension smelting furnace as well as at least one opening for an outgrowth removal means in a cooling block between the a reaction shaft structure and the concentrate burner. 
     OBJECTIVE OF THE INVENTION 
     The object of the invention is to provide a method and an arrangement for removing outgrowth in a suspension smelting furnace. 
     SHORT DESCRIPTION OF THE INVENTION 
     The method for removing outgrowth in a suspension smelting furnace comprises providing the reaction shaft with at least one opening for an outgrowth removal means. The method comprises additionally providing at least one outgrowth removal means having a movable piston, and arranging a movable piston of at least one outgrowth removal means such that the movable piston of at least one outgrowth removal means can move in the opening in the reaction shaft and into the reaction shaft, and moving the movable piston of at least one outgrowth removal means into the reaction shaft to push possible outgrowth in the reaction shaft by means of the movable piston of said at least one outgrowth removal means to detach possible outgrowth in the reaction shaft and to cause possible outgrowth to fall in the reaction shaft. 
     In the arrangement for removing outgrowth in a suspension smelting furnace, the reaction shaft comprises at least one opening for an outgrowth removal means. The arrangement comprises additionally at least one outgrowth removal means having a movable piston that is arranges such that the movable piston of said at least one outgrowth removal means can move in the opening in the reaction shaft and into the reaction shaft to push possible outgrowth in the reaction shaft by means of the movable piston of said at least one outgrowth removal means to detach possible outgrowth in the reaction shaft and to cause possible outgrowth to fall in the reaction shaft. 
     The method and the arrangement provides for several advantages. When the ignition zone moves further down the furnace due to outgrowth buildup in the vicinity of the concentrate burner, the volume and height of the reaction shaft is not utilized and efficiency drops. This causes a drop in oxygen utilization efficiency of the furnace. 
     Outgrowth buildup may also be formed unevenly the concentrate burner. The result of such uneven outgrowth buildup will be that the oxidizing conditions in the reaction shaft will vary so that in the reaction shaft will be created both vertical sections having over-oxidizing conditions i.e. a vertical section containing more oxygen than needed for the reactions and section having under-oxidizing conditions i.e. a vertical section containing less little oxygen than needed for the reactions and vertical sections having lower temperatures than other sections. In the different vertical sectors in the reactions shaft different amounts of magnetite (Fe 3 O 4 ) will be created in the reaction shaft. This has a decremental effect on settler slag quality, for example Cu/Ni losses may be higher. If a varying magnetite (Fe 3 O 4 ) is formed from the reaction shaft, it may also create a varying autogeneous (protective) layer in the settler walls and roof. A too thick autogeneous layer will reduce the melt holding capacity of the furnace and a too thin autogeneous layer will reduce the lifetime of the furnace. 
     It is therefore important to regularly ensure that the buildup situation and to avoid outgrowth buildup. This can be achieved by automatically forcing the pistons to move with regular intervals, suitable interval is 1-2 times/h, thereby pushing on the buildup and causing it to break and fall into the reaction shaft. 
     Heat losses in coolant circulating in a cooling block fastened at the top of the reaction shaft and having an aperture through which the concentrate burner extends through into the reactions shaft can be used to monitor outgrowth buildup formation. The cooling block may divided into a number of horizontal sections each having a channel for coolant fluid and each block being provided with coolant circulating means for circulating coolant fluid in the channel. In such case at least one coolant circulating means is provided with temperature measuring means for measuring the temperature of the coolant fluid that is fed into the channel of the horizontal section and correspondingly with temperature measuring means for measuring the temperature of the coolant fluid that is discharged from the channel of the horizontal section outlet temperature. Said at least one coolant circulating means is provided with temperature measuring means ay additionally be provided with coolant fluid flow measurement means. By using the results of the temperature and flow measurement, a heat loss calculation can be made for said at least one horizontal section for example by using the following equation
 
 Q=cp*V   out   *ro *( T   in   −T   out )  (1)
 
     Where 
     Q is the heat loss, 
     cp is the heat capacity of the coolant fluid, 
     V out  is the volumetric flow of the coolant fluid, 
     ro is the density of the coolant fluid, 
     T in  is the temperature of the coolant fluid that is fed into the channel, and 
     T out  is the temperature of the coolant fluid that is discharged from the channel. 
     When there is buildup formation at said at least one horizontal section of the cooling block, the calculated heat loss drops. When the heat loss for a certain section has dropped below a set threshold either as an absolute set value or as a calculated value based on averages or maximum or combination of these, the movable pistons of the outgrowth removal means are moved into the reaction shaft of the suspension smelting furnace and then withdrawn, causing the buildup in this section to drop into the reaction shaft. 
    
    
     
       LIST OF FIGURES 
       In the following the invention will described in more detail by referring to the figures, which 
         FIG. 1  a suspension smelting furnace, 
         FIG. 2  is a detail view of an embodiment of an arrangement for removing outgrowth in a suspension smelting furnace, 
         FIG. 3  shows a cooling block that is provided with eight openings for a maximum of eight outgrowth removal means, 
         FIG. 4  shows a part of an embodiment that is provided with a control arrangement for actuating at least one outgrowth removal means based on heat loss in coolant fluid that is fed into a coolant channels in a cooling block and that is discharged from the coolant channel of the cooling block, and 
         FIG. 5  shows a part of an embodiment that is provided with a control arrangement for actuating at least one outgrowth removal means based on heat loss in a coolant fluid that is fed into a coolant channels in a cooling block and coolant fluid that is discharged from the coolant channel of the cooling block. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention relates to a method for removing outgrowth in a suspension smelting furnace and to an arrangement for removing outgrowth in a suspension smelting furnace. 
       FIG. 1  shows a suspension smelting furnace which comprises a reaction shaft  1 , an uptake  2 , and a lower furnace  3 , as well as a concentrate burner  4  for feeding reaction gas (not shown in the figures) and fine solids (not shown) such as concentrate, preferable copper or nickel concentrate, matte and/or flux into the reaction shaft  1 . The operation of such a suspension smelting furnace is for example described in the Finnish patent publication FI22694. 
     First the method for removing outgrowth in a suspension smelting furnace and preferred embodiments and variants thereof will be describer in greater detail. 
     The suspension smelting furnace in the method comprises a reaction shaft  1  having a reaction shaft structure  9 , and a concentrate burner  4  for feeding at least reaction gas and fine solids such as copper or nickel concentrate into the reaction shaft  1  of the suspension smelting furnace. 
     The method comprises providing the reaction shaft  1  with at least one opening  5  for an outgrowth removal means  6 . 
     The method comprises providing at least one outgrowth removal means  6  having a movable piston  7 . 
     The method comprises arranging the movable piston  7  of at least one outgrowth removal means  6  such that the movable piston  7  of said at least one outgrowth removal means  6  can move in the opening  5  in the reaction shaft  1  and into the reaction shaft  1  i.e. into the interior (not marked with a reference numeral) of the reaction shaft  1 . 
     The method comprises moving the movable piston  7  into the reaction shaft  1  to push possible outgrowth in the reaction shaft  1  by means of the movable piston  7  of said at least one outgrowth removal means  6 , preferably to push outgrowth present in the reaction shaft  1  by means of the movable piston  7  of said at least one outgrowth removal means  6 . 
     In an embodiment of the method, the method comprises providing a cooling block  8  having an aperture  13  for the concentrate burner  4  and first fastening means  10  for fastening the concentrate burner  4  to the cooling block  8  and second fastening means  11  for fastening the cooling block  8  at the top of the reaction shaft  1  of the suspension smelting furnace. This embodiment of the method comprises additionally providing the cooling block  8  with at least one opening  5  for the movable piston  7  of at least one outgrowth removal means  6 . This embodiment of the method comprises additionally fastening the cooling block  8  at the top of the reaction shaft  1  of the reaction shaft  1  of the suspension smelting furnace so that the cooling block  8  is fastened to the reaction shaft structure  9  of the reaction shaft  1  of the suspension smelting furnace by using the second fastening means  11  and so that the cooling block  8  is fastened to the concentrate burner  4  by using the first fastening means  10  and so that the concentrate burner  4  extends into the reaction shaft  1 . The cooling block can for example be made of copper or comprise copper.  FIG. 3  shows a cooling block  8  having in total eight openings  5  for eight movable pistons  7  of eight outgrowth removal means  6 . 
     If the method comprises providing a cooling block  8  as described above, the method comprises preferably, but not necessarily, providing a coolant circulating means  14  for circulating coolant fluid (not shown in the drawings) in at least one channel  15  in the cooling block  8 . In such case the method comprises circulating coolant in said at least one channel  15  in the cooling block  8  by feeding coolant fluid into said at least one channel  1 ) and by discharging coolant fluid from said at least one channel  15 . In such case the method comprises measuring the temperature (T in ) of coolant fluid that is fed into said at least one channel  15 , measuring the temperature (T out ) of coolant fluid that is discharged from said at least one channel  15 , and measuring the volumetric flow (V out ) of the coolant fluid in said at least one channel  15 . In such case the method comprises calculating the heat loss (Q) of the coolant fluid in said at least one channel  15  in the cooling block  8  by using the temperature (T in ) of coolant fluid that is fed into said at least one channel  15 , the temperature (T out ) of coolant fluid that is discharged from said at least one channel  15 , and the volumetric flow (V out ) of the coolant fluid in said at least one channel  15  and controlling the outgrowth removal means  6  based on the calculated heat loss (Q). 
     The heat loss (Q) can for example be calculated by the following equation:
 
 Q=cp*V   out   *ro *( T   in   −T   out )  (1)
 
     where 
     Q is the heat loss, 
     cp is the heat capacity of the coolant fluid, 
     V out  is the volumetric flow of the coolant fluid, 
     ro is the density of the coolant fluid, 
     T in  is the temperature of the coolant fluid that is fed into the channel, and 
     T out  is the temperature of the coolant fluid that is discharged from the channel. 
     In the arrangement shown in  FIGS. 4 and 5  the cooling block  8  can be considered to be divided into four horizontal sector (not marked with a reference numeral) each horizontal sector having a channel  15  for coolant fluid. Each of these horizontal sectors may be provided with first temperature measuring means  16 , second temperature measuring means  17 , and flow measurement means  19  for independently calculating the heat loss (Q) within each horizontal sector. 
     If the method comprises calculating the heat loss (Q) of the coolant fluid in said at least one channel  15  in the cooling block  8  by using the temperature (T in ) of coolant fluid that is fed into said at least one channel  15 , the temperature (T out ) of coolant fluid that is discharged from said at least one channel  15 , and the volumetric flow (V out ) of the coolant fluid in said at least one channel  15  and controlling the outgrowth removal means  6  based on the calculated heat loss (Q) as described above, the method comprises preferably, but not necessarily, by moving the movable piston  7  of at least one outgrowth removal means  6  into the reaction shaft  1  to push possible outgrowth in the reaction shaft  1  by means of the movable piston  7  of said at least one outgrowth removal means  6  if the calculated heat loss (Q) goes below a pre-set value (Q set ). 
     If the method comprises calculating the heat loss (Q) of the coolant fluid in said at least one channel  15  in the cooling block  8  by using the temperature (T in ) of coolant fluid that is fed into said at least one channel  15 , the temperature (T out ) of coolant fluid that is discharged from said at least one channel  15 , and the volumetric flow (V out ) of the coolant fluid in said at least one channel  15  and controlling the outgrowth removal means  6  based on the calculated heat loss (Q) as described above, the method comprises preferably, but not necessarily, moving the movable piston  7  of at least one outgrowth removal means  6  into the reaction shaft  1  to push possible outgrowth in the reaction shaft  1  by means of the movable piston  7  of said at least one outgrowth removal means  6  if an average heat loss (Q ave ) calculated by using several calculated heat losses (Q) goes below a pre-set average value (Q aveset ). 
     The method comprises preferably providing at least one opening  5  for a movable piston  7  of at least one outgrowth removal means  6  adjacent to the concentrate burner  4  at the top of the interior of the reaction shaft  1  of the suspension smelting furnace. 
     The method may comprise an attachment step for attaching the outgrowth removal means  6  to the concentrate burner  4  as is shown in  FIG. 2 . 
     The method may comprise using a pneumatic cylinder-piston-arrangement in at least one outgrowth removal means  6  for moving the movable piston  7  of said at least one outgrowth removal means  6 . 
     The method may comprise using a linear actuator such as a mechanical actuator, a hydraulic actuator, or a pneumatic actuator in at least one outgrowth removal means  6  for moving the movable piston  7  of at least one outgrowth removal means. 
     The method may comprise providing the outgrowth removal means  6  with a control arrangement  12  for actuating at least one outgrowth removal means  6  to move the movable piston  7  of at least one outgrowth removal means  6  into the reaction shaft  1  for example with regular time-intervals. 
     Next the arrangement for removing outgrowth in a suspension smelting furnace and preferred embodiments and variants thereof will be describer in greater detail. 
     The suspension smelting furnace in the arrangement comprises a reaction shaft  1  having a reaction shaft structure  9 , and a concentrate burner  4  for feeding at least reaction gas and fine solids such as copper or nickel concentrate into the reaction shaft  1  of the suspension smelting furnace. 
     The reaction shaft  1  comprises at least one opening  5  for an outgrowth removal means  6 . 
     The arrangement comprises at least one outgrowth removal means  6  having a movable piston  7 . The movable piston  7  of at least one outgrowth removal means  6  is arranged such that the movable piston  7  of said at least one outgrowth removal means  6  can move in the opening  5  in the reaction shaft  1  and into the reaction shaft  1  to push possible outgrowth in the reaction shaft  1  by means of the movable piston  7  of said at least one outgrowth removal means  6 , preferably to push outgrowth present in the reaction shaft  1  by means of the movable piston  7  of said at least one outgrowth removal means  6 . 
     In a preferred embodiment of the arrangement, the arrangement comprises a cooling block  8  having an aperture  13  for the concentrate burner  4  and first fastening means  10  for fastening the concentrate burner  4  to the cooling block  8  and second fastening means  11  for fastening the cooling block  8  at the top of the reaction shaft  1  of the suspension smelting furnace. The cooling block  8  is provided with at least one opening  5  for at least one movable piston  7  of at least one outgrowth removal means  6 . The cooling block  8  is arranged at the top of the interior of the reaction shaft  1  of the reaction shaft  1  of the suspension smelting furnace so that the cooling block  8  is fastened to the reaction shaft structure  9  of the reaction shaft  1  of the suspension smelting furnace by using the second fastening means  11  and to the concentrate burner  4  by using the first fastening means  10  and so that the concentrate burner  4  extends into the reaction shaft  1 . The cooling block can for example be made of copper or comprise copper.  FIG. 3  shows a cooling block  8  having in total eight openings  5  for eight movable pistons  7  of eight outgrowth removal means  6 . 
     If the arrangement comprises a cooling block  8  as described above, the arrangement comprises preferably, but not necessarily, coolant circulating means  14  for circulating coolant fluid in at least one channel  15  in the cooling block  8  by feeding coolant fluid into said at least one channel  15  and by discharging coolant fluid from said at least one channel  15 . In such case the arrangement comprises first temperature measuring means  16  for measuring the temperature (T in ) of coolant fluid that is fed into said at least one channel  15  and arrangement comprises second temperature measuring means  17  for measuring the temperature (T out ) of coolant fluid that is discharged from said at least one channel  15 . The arrangement may additionally in addition to the first temperature measuring means  16  and to the second temperature measuring means  17  be provided with flow measuring means  19  for measuring the volumetric flow V out  of coolant fluid in said at least one channel  15 . In such case the arrangement comprises calculating means  18  for calculating heat loss (Q) by using the temperature (T in ) of coolant fluid that is fed into said at least one channel  15 , the temperature (T out ) of coolant fluid that is discharged from said at least one channel  15 , and the volumetric flow (V out ) of the coolant fluid in said at least one channel  15  for example by the following equation:
 
 Q=cp*V   out   *ro *( T   in   −T   out )  (1)
 
     where 
     Q is the heat loss, 
     cp is the heat capacity of the coolant fluid, 
     V out  is the volumetric flow of the coolant fluid, 
     ro is the density of the coolant fluid, 
     T in  is the temperature of the coolant fluid that is fed into the channel, and 
     T out  is the temperature of the coolant fluid that is discharged from the channel. 
     In such case by the arrangement comprises a control arrangement  12  controlling the outgrowth removal means  6  based on the calculated heat loss (Q) calculated by the calculating means  18 . In the arrangement shown in  FIGS. 4 and 5  the cooling block  8  can be considered to be divided into four horizontal sector (not marked with a reference numeral) each horizontal sector having a channel  15  for coolant fluid. Each of these horizontal sectors may be provided with first temperature measuring means  16  for measuring the temperature (T in ) of coolant fluid that is fed into the channel  15  and arrangement comprises second temperature measuring means  17  for measuring the temperature (T out ) of coolant fluid that is discharged from the channel  15  for independently calculating the calculated heat loss (Q) within each horizontal sector. 
     If the arrangement comprises a control arrangement  12  for controlling the outgrowth removal means  6  based on the heat loss (Q) calculated by the calculating means  18  as described above, the control arrangement  12  is preferably, but not necessarily, configured for controlling the outgrowth removal means  6  by moving the movable piston  7  of at least one outgrowth removal means  6  into the reaction shaft  1  to push possible outgrowth in the reaction shaft  1  by means of the movable piston  7  of said at least one outgrowth removal means  6  if the calculated heat loss (Q) goes below a pre-set value (Q set ). 
     If the arrangement comprises a control arrangement  12  for controlling the outgrowth removal means  6  based on the heat loss (Q) calculated by the calculating means  18  as described above, the control arrangement  12  is preferably, but not necessarily, configured for controlling the outgrowth removal means  6  by moving the movable piston  7  of at least one outgrowth removal means  6  into the reaction shaft  1  to push possible outgrowth in the reaction shaft  1  by means of the movable piston  7  of said at least one outgrowth removal means  6  if an heat loss (Q ave ) calculated by using several calculated heat losses (Q) goes below a pre-set average value (Q aveset ). 
     In the arrangement at least one opening  5  for a movable piston  7  of an outgrowth removal means  6  is preferably, but not necessarily, provided adjacent to the concentrate burner  4  at the top of the interior of the reaction shaft  1  of the suspension smelting furnace. 
     In the arrangement the outgrowth removal means  6  is preferably, but not necessarily, attached to the concentrate burner  4 . 
     In the arrangement the outgrowth removal means  6  comprises preferably, but not necessarily, a pneumatic cylinder-piston-arrangement in the outgrowth removal means  6  for moving the movable piston  7 . 
     In the arrangement the outgrowth removal means  6  comprises preferably, but not necessarily, a linear actuator such as a mechanical actuator, a hydraulic actuator, or a pneumatic actuator in the outgrowth removal means  6  for moving the movable piston  7 . 
     In the arrangement the outgrowth removal means  6  comprises preferably, but not necessarily, a control arrangement  12  for actuating the outgrowth removal means  6  to moving the movable piston  7  into the reaction shaft  1  for example with regular time-intervals. 
     It is apparent to a person skilled in the art that as technology advanced, the basic idea of the invention can be implemented in various ways. The invention and its embodiments are therefore not restricted to the above examples, but they may vary within the scope of the claims.