Method for producing matte or crude metal in a suspension smelting furnace and suspension smelting furnace

Abstract

A method is provided for producing matte such as copper or nickel matte or crude metal such as blister copper in a suspension smelting furnace such as a flash smelting furnace or a flash converting furnace. Also provided is a suspension smelting furnace such as a flash smelting furnace or a flash converting furnace. The suspension smelting furnace comprises a reaction shaft, a settler in communication with a lower end of the reaction shaft, and an uptake shaft. The settler extending in two opposite directions from a landing zone for a jet of oxidized suspension below the reaction shaft in the settler so that the settler comprises a first settler part on a first side of the landing zone and a second settler part on an opposite second side of the landing zone.

Claims

1. Suspension smelting furnace, comprising: a reaction shaft provided with a concentrate burner for feeding sulfidic raw material containing metal, slag-forming agent and oxygen containing reaction gas into the reaction shaft to form a jet of oxidized suspension in the reaction shaft, a settler in communication with a lower end of the reaction shaft wherein the settler has an elongated configuration, wherein the settler comprises an inner space and a first end wall structure at one end of the settler and a second end wall structure at the opposite end of the settler and wherein a landing zone for the jet of oxidized suspension is formed in the inner space of the settler below the lower end of the reaction shaft and wherein the settler is configured to receive oxidized suspension from the reaction shaft at the landing zone and to form a layer of matte or crude metal, wherein the layer of matte or crude metal extends in a horizontal dimension over the whole inner space of the settler, and a layer of slag on top of the layer of matte or crude metal in the inner space of the settler, wherein the layer of slag extends in a horizontal dimension over the whole inner space of the settler, an uptake shaft for leading process gases from the suspension smelting furnace via the uptake shaft, wherein the uptake shaft has a lower end in communication with the settler, a first taphole for discharging slag from the layer of slag in the inner space of the settler, and a second taphole for discharging matte or crude metal from the layer of matte or crude metal in the inner space of the settler, wherein the first taphole is arranged in the vertical direction at a level above the second taphole, wherein the settler extends in two opposite directions from the landing zone for the jet of oxidized suspension below the reaction shaft in the settler so that the settler comprises a first settler part on a first side of the landing zone, wherein the first settler part has a first proximal end at the landing zone and a first distal end at the opposite end of the first settler part which first distal end also is the first end wall structure of the settler, and a second settler part on an opposite second side of the landing zone, wherein the second settler part has a second proximal end at the landing zone and a second distal end at the opposite end of the second settler part which second distal end also is the second end wall structure of the settler, the settler is provided with a bottom structure that slopes continuously downwardly towards the second taphole from the first end wall structure of the settler to the second end wall structure of the settler, by the first taphole for discharging slag from the layer of slag in the settler being arranged in the first end wall structure, by the second taphole for discharging matte or crude metal from the layer of matte or crude metal in the settler being arranged in the second end wall structure, and by the lower end of the uptake shaft being in communication with the settler via the second settler part.

2. The suspension smelting furnace according to claim 1, wherein the first settler part is provided with a partition baffle for preventing oxidized dust from entering at least a section of the first settler part, wherein the partition baffle extends from a roof of the first settler part downwards into the first settler part.

3. The suspension smelting furnace according to claim 1, wherein the first settler part is provided with reducing agent feeding means for feeding reducing agent into at least one of the layer of matte or crude metal and the layer of slag.

4. The suspension smelting furnace according to claim 1, wherein the first settler part is provided a burner for creating a reducing atmosphere in at least a section of the first settler part.

5. The suspension smelting furnace according to claim 1, wherein the distance between the reaction shaft and the uptake shaft is less than 10 m.

6. The suspension smelting furnace according to claim 1, wherein the inner space of the settler is in communication with the lower end of the reaction shaft at a point of the settler that is closer to the middle of the settler than one of the ends of the settler.

7. The suspension smelting furnace according to claim 1, wherein an additional reaction shaft has a lower end in communication with the first settler part, and the additional reaction shaft is provided with an additional concentrate burner for feeding sulfidic raw material containing metal, slag-forming agent and oxygen containing reaction gas into the additional reaction shaft to form an additional jet of oxidized suspension in the additional reaction shaft.

8. The suspension smelting furnace according to claim 1, wherein the reaction shaft is provided in addition to a concentrate burner with an additional concentrate burner for feeding sulfidic raw material containing metal, slag-forming agent and oxygen containing reaction gas into the reaction shaft to form an additional jet of oxidized suspension in the reaction shaft.

9. The suspension smelting furnace according to claim 8, wherein the settler comprises an additional landing zone for additional jet of oxidized suspension, and the additional landing zone is formed closer to the first settler part than the second settler part.

10. The suspension smelting furnace according to claim 1, wherein the first taphole is arranged in the first end wall structure of the settler.

11. The suspension smelting furnace according to claim 1, wherein the second taphole is arranged in the second end wall structure of the settler.

Description

LIST OF FIGURES

(1) In the following the invention will described in more detail by referring to the figures of which

(2) FIG. 1 is a schematic illustration of a suspension smelting furnace according to a first embodiment,

(3) FIG. 2 is a schematic illustration of a suspension smelting furnace according to a second embodiment,

(4) FIG. 3 is a schematic illustration of a suspension smelting furnace according to a third embodiment,

(5) FIG. 4 is a schematic illustration of a suspension smelting furnace according to a fourth embodiment,

(6) FIG. 5 is a schematic illustration of a suspension smelting furnace according to a fifth embodiment,

(7) FIG. 6 is a schematic illustration of a suspension smelting furnace according to a sixth embodiment

(8) FIG. 7 is a schematic illustration of a suspension smelting furnace according to a seventh embodiment,

(9) FIG. 8 is a schematic illustration of a suspension smelting furnace according to a eight embodiment,

(10) FIG. 9 is a schematic illustration of a suspension smelting furnace according to a ninth embodiment, and

(11) FIG. 10 is a schematic illustration of a suspension smelting furnace according to a tenth embodiment.

DETAILED DESCRIPTION OF THE INVENTION

(12) The figures show examples of various suspension smelting furnaces suitable for carrying out various embodiments of the method and various embodiments of the suspension smelting furnace.

(13) First the method for producing matte or crude metal in a suspension smelting furnace such as a flash smelting furnace or a flash converting furnace and preferred embodiments of the method and variants of the method will be described in greater detail.

(14) The method comprises a step for feeding sulfidic raw material containing metal 1, slag-forming agent 2 and oxygen containing reaction gas 3 by means of a concentrate burner 4 into a reaction shaft 5 of the suspension smelting furnace to form a jet of oxidized suspension 6 in the reaction shaft 5.

(15) In case the suspension smelting furnace is a flash smelting furnace, the sulfidic raw material containing metal 1 can for example be sulfidic non-ferrous concentrate such as sulfidic copper concentrate or sulfidic nickel concentrate.

(16) In case the suspension smelting furnace is a flash converting furnace, the sulfidic raw material containing metal 1 can for example be copper matte obtained from a flash smelting process performed in a flash smelting furnace.

(17) The slag forming agent can contain silica and/or calcium bearing material, such as lime or limestone.

(18) The oxygen containing reaction gas 3 can for example be air or oxygen-enriched air.

(19) The method comprises additionally a step for receiving the jet of oxidized suspension 6 in a landing zone 7 of a settler 8 in communication with a lower end (not marked with a reference numeral) of the reaction shaft 5. The settler 8 has an inner space 9 limited by a wall structure (not marked with a reference numeral), a bottom structure (not marked with a reference numeral) and a roof structure (not marked with a reference numeral). The settler 8 has a first end wall structure 27 at one end of the settler 8 and a second end wall structure 28 at the opposite end of the settler 8.

(20) The method comprises additionally a step for forming a layer of matte or crude metal 10 and a layer of slag 11 on top of the layer of matte or crude metal 10 in the settler 8. In case the suspension smelting furnace is a flash smelting furnace, a layer of matte 10 is formed in the settler 8, and in case the suspension smelting furnace is a flash converting furnace, a layer of crude metal 10 is formed in the settler 8.

(21) The method comprises additionally a step for leading process gases 12 produced in the suspension smelting process in the suspension smelting furnace from the suspension smelting furnace via an uptake shaft 13, wherein the uptake shaft 13 has a lower end in communication with the settler 8.

(22) The method comprises additionally a first discharging step for discharging slag 14 from the layer of slag 11 in the settler 8 through a first taphole 15.

(23) The method comprises additionally a second discharging step for discharging matte or crude metal 16 from the layer of matte or crude metal 10 in the settler 8 through a second taphole 17, wherein the first taphole 15 is arranged in the vertical direction at a level above the second taphole 17.

(24) The method comprises providing for the method, a suspension smelting furnace having a settler 8 extending in two opposite directions from the landing zone 7 for the jet of oxidized suspension 6 below the reaction shaft 5 in the settler 8 so that the settler 8 comprises a first settler part 18 on a first side of the landing zone 7 and a second settler part 19 on an opposite second side of the landing zone 7, and so that a lower end of the uptake shaft 13 is in communication with the inner space 9 of the settler 8 via the second settler part 19.

(25) The first discharging step for discharging slag 14 from the layer of slag 11 in the settler 8 is performed by discharging slag 14 from the layer of slag 11 in the settler 8 through a first taphole 15 arranged in the first settler part 18.

(26) The second discharging step for discharging matte or crude metal 16 from the layer of matte or crude metal 10 in the settler 8 is performed by discharging matte or crude metal 16 from the layer of matte or crude metal 11 through a second taphole 17 arranged in the second settler part 19.

(27) The method may comprise a providing step for providing the first settler part 18 with a partition baffle 20 for preventing oxidized dust created in the suspension smelting furnace from entering at least a section of the first settler part 18 so that the partition baffle 20 extending from a roof of the first settler part 18 downwards into the first settler part 18. FIGS. 2 to 5 and 7 and 8 shows suspension smelting furnaces in which the first settler part 18 has been provided with such partition baffle 20. As is shown in FIGS. 2 to 5 and 7 and 8, the position of such partition baffle 20 can be close to the reaction shaft 5 as is shown in FIGS. 3, 5 and 7, or alternatively more to the middle of the first settler part 18 as is shown in FIGS. 2, 4 and 8. If the method comprises such providing step, the method comprises additionally forcing slag from the layer of slag 11 downwards in the first settler part 18 by means of the partition baffle 20.

(28) The method may comprise a providing step for providing the first settler part 18 with reducing agent feeding means 21 for feeding reducing agent into at least one of the layer of matte or crude metal 10 and the layer of slag 11. FIGS. 4 to 8 shows suspension smelting furnaces in which the first settler part 18 has been provided with such reducing agent feeding means 21. If the method comprises such providing step, the method comprises additionally feeding reducing agent in the form of solid and/or gas such as natural gas into at least one of the layer of matte or crude metal 10 and the layer of slag 11 by means of the reducing agent feeding means 21.

(29) The method may comprise a providing step for providing the first settler part 18 with a burner 22 for creating a reducing atmosphere in at least a section of the first settler part 18. FIGS. 7 and 8 shows suspension smelting furnaces in which the first settler part 18 has been provided with such burner 22. If the method comprises such providing step, the method comprises additionally using the burner 22 for creating a reducing atmosphere in at least a section of the first settler part 18 for example by consuming oxygen present in the first settler part 18 in the burning process performed with the burner 22.

(30) The method comprises preferably, but not necessarily, as shown in the figures forming a layer of matte or crude metal 10 of at least one of sulfidic raw material containing metal 1, slag-forming agent 2 and oxygen containing reaction gas 3 fed by the concentrate burner 4 extending in a horizontal dimension over the whole inner space 9 of the settler 8, and forming a layer of slag 11 of at least one of sulfidic raw material containing metal 1, slag-forming agent 2 and oxygen containing reaction gas 3 fed by the concentrate burner 4 extending in a horizontal dimension over the whole inner space 9 of the settler 8.

(31) The method comprises preferably, but not necessarily, providing for the method a suspension smelting furnace having distance between the reaction shaft 5 and the uptake shaft 13 less than 10 m, preferably less than 4 m. if the reaction shaft 5 and the uptake shaft 13 are situated in this manner relatively close to each other, dust that has attached to the inner walls of the uptake shaft 13 will fall down from the uptake shaft 13 close to the reaction shaft 5 and an advantage of this is that because the temperature of the melt is high close to the reaction shaft 5, the dust will better blend in into the melt.

(32) The method comprises preferably, but not necessarily, providing for the method a suspension smelting furnace where the inner space 9 of the settler 8 is in communication with the lower end of the reaction shaft 5 at a point of the settler 8 that is closer to the middle of the settler 8 than one of the ends of the settler 8. This provides for both a large first settler part 18 and a large second settler part 19. The figures show suspension smelting furnaces where the reaction shaft 5 is situated at the middle of the settler 8.

(33) The method comprises preferably, but not necessarily, providing for the method a suspension smelting furnace having a settler 8 having an elongated configuration, as is shown in the figures.

(34) The method comprises preferably, but not necessarily, as is shown in the figures, providing for the method a suspension smelting furnace having a first settler part 18 having a first proximal end (not marked with a reference numeral) at the landing zone 7 and first distal end (not marked with a reference numeral) at the opposite end of the first settler part 18, which first distal end also is the first end wall structure 27 of the settler 8, and having the first taphole 15 for discharging slag 14 from the settler 8 arranged at the first distal end of the first settler part 18.

(35) The method comprises preferably, but not necessarily, as is shown in the figures, providing for the method a suspension smelting furnace the second settler part 19 having a second proximal end (not marked with a reference numeral) at the landing zone 7 and second distal end (not marked with a reference numeral) at the opposite end of the second settler part 19 which second distal end also is the second end wall structure 28 of the settler 8, and having the second taphole 17 for discharging matte of crude metal from the settler 8 arranged at the second distal end of the second settler part 19.

(36) The method may, as shown in FIG. 9, comprise a providing step for providing for the method a suspension smelting furnace provided with an additional reaction shaft 23 having a lower end in communication with a first inner space (not marked with a reference numeral) of the first settler part 18, wherein the additional reaction shaft being provided with an additional concentrate burner 24 for feeding sulfidic raw material containing metal 1, slag-forming agent 2 and oxygen containing reaction gas 3 into the additional reaction shaft 23 to form an additional jet 25 of oxidized suspension in the additional reaction shaft 23. If the method comprises such providing step, the method comprises feeding a feed of sulfidic raw material containing metal 1, slag-forming agent 2 and oxygen containing reaction gas 3 by means of the additional concentrate burner 24 than with the concentrate burner 4 so said feed comprises a smaller oxygen coefficient (total oxygen content for feed) than the oxygen coefficient of the corresponding feed that is fed into the reaction shaft 5 by means of the concentrate burner 4. A such feed into the additional reaction shaft 23 will lower the temperature of the slag in the first inner space of the first settler part 18 resulting in lower matte grade and therefore lower oxygen potential in the slag, which means lower Cu.sub.2S and Cu.sub.2O in equilibrium with the slag. Also lower magnetite content of the slag will decrease slag viscosity. Droplets of matte or crude metal therefore can easier flow down in the part of the slag layer in the first inner space of the first settler part 18 to the layer of matte or crude metal below the slag layer.

(37) The method may, as shown in FIG. 10, comprise a providing step for providing for the method a suspension smelting furnace provided a suspension smelting furnace having reaction shaft 5 being provided in addition to a concentrate burner 4 with an additional concentrate burner 24 for feeding sulfidic raw material containing metal 1, slag-forming agent 2 and oxygen containing reaction gas 3 into the reaction shaft 5 to form an additional jet 25 of oxidized suspension in the reaction shaft 5. If the method comprises such providing step, the method comprises feeding a feed of sulfidic raw material containing metal 1, slag-forming agent 2 and oxygen containing reaction gas 3 by means of the additional concentrate burner 24 than with the concentrate burner 4 so said feed comprises a smaller oxygen coefficient (total oxygen content for feed) than the oxygen coefficient of the corresponding feed that is fed into the reaction shaft 5 by means of the concentrate burner 4. If the method comprises such providing step, the method comprises preferably, but not necessarily, receiving the additional jet 25 of oxidized suspension in an additional landing zone 26 of the inner space 9 of the settler 8 in communication with the reaction shaft 5, which additional landing zone being formed closer to the first settler part 18 than the second settler part 19. A such feed into the reaction shaft 5 will lower the temperature of the slag flowing into the first inner space of the first settler part 18 resulting in lower matte grade and therefore lower oxygen potential in the slag, which means lower Cu.sub.2S and Cu.sub.2O in equilibrium with the slag. Also lower magnetite content of the slag will decrease slag viscosity. Droplets of matte or crude metal therefore can easier flow down in the part of the slag layer in the first inner space of the first settler part 18 to the layer of matte or crude metal below the slag layer.

(38) The method comprises preferably, but not necessarily, leading process gases 12 from the suspension smelting furnace via the uptake shaft 13 by sucking.

(39) The method may comprise providing for the method a suspension smelting furnace having the first taphole 15 arranged in the first end wall structure 27 of the settler 8.

(40) The method may comprise providing for the method a suspension smelting furnace having the second taphole 17 arranged in the second end wall structure 28 of the settler 8.

(41) The method may comprise providing for the method a suspension smelting furnace having a settler 8 provided with a bottom structure 29 that slopes downwardly for example in an inclined and/or curved manner towards the second taphole 16.

(42) The method may comprise providing for the method a suspension smelting furnace having a settler 8 provided with a bottom structure 29 that slopes downwardly for example in an inclined and/or curved manner towards the second taphole 16 between the first end wall structure 27 of the settler 8 and the second end wall structure 28 of the settler 8.

(43) The method may comprise providing for the method a suspension smelting furnace having a settler 8 provided with a bottom structure 29 that slopes downwardly for example in an inclined and/or curved manner towards the second taphole (16) from the first wall structure 27 of the settler 8 to the second end wall structure 28 of the settler 8.

(44) Next the suspension smelting furnace such as a flash smelting furnace or a flash converting furnace and preferred embodiments of the suspension smelting furnace and variants of the suspension smelting furnace will be described in greater detail.

(45) The suspension smelting furnace comprises a reaction shaft 5 provided with a concentrate burner 4 for feeding sulfidic raw material containing metal 1, slag-forming agent 2 and oxygen containing reaction gas 3 into the reaction shaft 5 to form a jet of oxidized suspension 6 in the reaction shaft 5.

(46) In case the suspension smelting furnace is a flash smelting furnace, the sulfidic raw material containing metal 1 can for example be sulfidic non-ferrous concentrate such as sulfidic copper concentrate.

(47) In case the suspension smelting furnace is a flash converting furnace, the sulfidic raw material containing metal 1 can for example be copper matte obtained from a flash smelting process performed in a flash smelting furnace.

(48) The slag forming agent can contain silica and/or calcium bearing material, such as lime or limestone.

(49) The oxygen containing reaction gas 3 can for example be air or oxygen-enriched air.

(50) The suspension smelting furnace comprises additionally a settler 8 in communication with a lower end of the reaction shaft 5. The settler 8 comprises an inner space 9 and a first end wall structure 27 at one end of the settler 8 and a second end wall structure 28 at the opposite end of the settler 8. A landing zone 7 for the jet of oxidized suspension 6 is formed in the inner space 9 of the settler 8 below the lower end of the reaction shaft 5. The settler 8 is configured to receive oxidized suspension 6 from the reaction shaft 5 at the landing zone 7 and to form a layer of matte or crude metal 10 and a layer of slag 11 on top of the layer of matte or crude metal 10 in the inner space 9 of the settler 8.

(51) The suspension smelting furnace comprises additionally an uptake shaft 13 for leading process gases 12 from the suspension smelting furnace via the uptake shaft 13. The uptake shaft 13 has a lower end in communication with the settler 8.

(52) The suspension smelting furnace comprises additionally a first taphole 15 for discharging slag 14 from the layer of slag 11 in the inner space 9 of the settler 8.

(53) The suspension smelting furnace comprises additionally a second taphole 17 for discharging matte or crude metal 16 from the layer of matte or crude metal 10 in the inner space 9 of the settler 8.

(54) The first taphole 15 for discharging slag 14 from the layer of slag 11 in the inner space 9 of the settler 8 is arranged in the vertical direction at a level above the second taphole 17 for discharging matte or crude metal 16 from the layer of matte or crude metal 10 in the inner space 9 of the settler 8.

(55) The settler 8 extends in two opposite directions from the landing zone 7 for the jet of oxidized suspension 6 below the reaction shaft 5 in the settler 8 so that the settler 8 comprises a first settler part 18 on a first side of the landing zone 7 and a second settler part 19 on an opposite second side of the landing zone 7.

(56) The first taphole 15 for discharging slag 14 from the layer of slag 11 in the settler 8 is arranged in the first settler part 18.

(57) The second taphole 17 for discharging matte or crude metal 16 from the layer of matte or crude metal 10 in the settler 8 is arranged in the second settler part 19.

(58) The lower end of the uptake shaft 13 is in communication with the inner space 9 of the settler 8 via the second settler part 19.

(59) The first settler part 18 may, as is shown in FIGS. 2 to 5 and 7 and 8, be provided with a partition baffle 20 for preventing oxidized dust from entering at least a section of the first settler part 18. The partition baffle 20 extends from a roof of the first settler part 18 downwards into the first settler part 18, forcing slag from the layer of slag 11 downwards in the settler 8 by means of the partition baffle 20.

(60) The first settler part 18 may, as is shown in FIGS. 4 to 8, be provided with reducing agent feeding means 21 for feeding reducing agent into at least one of the layer of matte or crude metal 10 and the layer of slag 11.

(61) The first settler part 18 may, as is shown in FIGS. 7 and 8, be provided a burner 22 for creating a reducing atmosphere in at least a section of the first settler part 18. A purpose of the burner 22 is to create a reducing atmosphere in at least a section of the first settler part 18 by consuming oxygen present in the first settler part 18 in the burning process performed with the burner 22

(62) In the suspension smelting furnace, the layer of matte or crude metal 10 formed of at least one of sulfidic raw material containing metal 1, slag-forming agent 2 and oxygen containing reaction gas 3 fed by the concentrate burner 4 is preferably, but not necessarily, configured to extend in a horizontal dimension over the whole inner space 9 of the settler 8, and the layer of slag 11 formed of at least one of sulfidic raw material containing metal 1, slag-forming agent 2 and oxygen containing reaction gas 3 fed by the concentrate burner 4 is preferably, but not necessarily, configured to extend in a horizontal dimension over the whole inner space 9 of the settler 8.

(63) In the suspension smelting furnace the distance between the reaction shaft 5 and the uptake shaft 13 is preferably, but not necessarily, less than 10 m, preferably less than 5 m.

(64) In the suspension smelting furnace the inner space 9 of the settler 8 is preferably, but not necessarily, in communication with the lower end of the reaction shaft 5 at a point of the settler 8 that is closer to the middle of the settler 8 than one of the ends of the settler 8.

(65) The settler 8 of the suspension smelting furnace has preferably, but not necessarily, an elongated configuration.

(66) The first settler part 18 has preferably, but not necessarily, a first proximal end at the landing zone 7 and first distal end at the opposite end of the first settler part 18 which first distal end also is the first end wall structure 27 of the settler 8, and the first taphole 15 for discharging slag 14 from the settler 8 is preferably, but not necessarily, arranged at such first distal end of the first settler part 18.

(67) The second settler part 19 has preferably, but not necessarily, a second proximal end at the landing zone 7 and second distal end at the opposite end of the second settler part 19 which second distal end also is the second end wall structure 28 of the settler 8, and second taphole 17 for discharging matte of crude metal from the settler 8 is preferably, but not necessarily, arranged at the second distal end of the second settler part 19.

(68) The suspension smelting furnace may, as is shown in FIG. 9, have an additional reaction shaft 23 having a lower end in communication with the first settler part 18. The additional reaction shaft 23 being provided with an additional concentrate burner 24 for feeding sulfidic raw material containing metal 1, slag-forming agent 2 and oxygen containing reaction gas 3 into the additional reaction shaft 23 to form an additional jet 25 of oxidized suspension in the additional reaction shaft 23.

(69) The reaction shaft 5 of the suspension smelting furnace may, as is shown in FIG. 10, be provided in addition to a concentrate burner with an additional concentrate burner 24 for feeding sulfidic raw material containing metal 1, slag-forming agent 2 and oxygen containing reaction gas 3 into the reaction shaft 5 to form an additional jet 25 of oxidized suspension in the reaction shaft 5. If the reaction shaft 5 of the suspension smelting furnace is provided with such additional concentrate burner 24, the settler 8 comprises preferably, but not necessarily, an additional landing zone for the additional jet 25 of oxidized suspension so that the additional landing zone is formed closer to the first settler part 18 than the second settler part 19.

(70) The suspension smelting furnace is preferably, but not necessarily, provided with sucking means leading process gases 12 from the suspension smelting furnace by sucking.

(71) The first taphole 15 may be arranged in the first end wall structure 27 of the settler 8.

(72) The second taphole 17 may be arranged in the second end wall structure 28 of the settler 8.

(73) The settler 8 may be provided with a bottom structure 29 that slopes downwardly for example in an inclined and/or curved manner towards the second taphole 16.

(74) The settler 8 may be provided with a bottom structure 29 that slopes downwardly for example in an inclined and/or curved manner towards the second taphole 16 between the first end wall structure 27 of the settler 8 and the second end wall structure 28 of the settler 8.

(75) The settler 8 may be provided with a bottom structure 29 that slopes downwardly for example in an inclined and/or curved manner towards the second taphole 16 from the first wall structure 27 of the settler 8 to the second end wall structure 28 of the settler 8.

(76) It is apparent to a person skilled in the art that as technology advances, 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.