AGITATOR IMPELLER, ARRANGEMENT AND USE.

Abstract

An agitator impeller (1), an arrangement, and a use. The impeller (1) comprises a hub disc (2) comprising a shaft-fixing structure (3) arranged centrally in the hub to receive a shaft (4) central and perpendicular from an upper side of the hub disc (2), a plurality of upper vanes (5) arranged on the upper side of the hub disc (2), and a plurality of lower vanes (6) arranged on a lower side of the hub disc (2). At least one of said plurality of upper vanes (5) is arranged to have a jet angle (Ju) of 5° - 45°, and the lower vanes (6) have a jet angle (Jl) that is different from said jet angle (Ju) of at least one of said plurality of upper vanes.

Description

AGITATOR IMPELLER, ARRANGEMENT AND USE lA / E / ZUZJ / UOOUlO BACKGROUND OF THE INVENTION The invention relates to an agitator impeller. The invention also relates to an arrangement for mixing gas with mud. The invention relates further to a use of the agitator impeller. Agitator impellers are commonly used in processes to mix gas with slurry. Many impellers have been found to suffer severe erosion with a limited service life. BRIEF DESCRIPTION OF THE INVENTION From a first aspect, an agitator impeller can be provided, comprising a hub disc comprising a shaft-fixing structure arranged centrally in the hub to receive a central shaft and perpendicularly from an upper side of the hub disc, a plurality of upper vanes arranged on the upper side of the hub disc, a plurality of lower vanes arranged on a lower side of the hub disc, wherein at least one of said plurality of upper vanes is arranged to have a jet angle of 5°-45°, and wherein the lower vanes have a jet angle that is different from said jet angle of at least one of said plurality of upper vanes. Therefore, an impeller that has an improved particle distribution around the impeller surface and a more uniform velocity distribution within the impeller blade region and thus has reduced erosion and can achieve a longer operating period. Viewed from another perspective, an arrangement for mixing gas with mud can be provided, comprising a mixing tank, at least one agitator impeller described above arranged in the mixing tank and attached to a shaft, and a motor for rotating the shaft and the agitator impeller. Therefore, an arrangement can be achieved that has a reduced need for maintenance or replacement of impeller(s). The agitator impeller and its arrangement are characterized as set forth in the independent claims. Certain other embodiments are characterized as set forth in the other claims. The inventive embodiments are also described in the specification and figures of this patent application. The inventive content of the patent application may also be defined in ways other than those defined in the following claims. The inventive content may also consist of several separate inventions, especially if the invention is examined in light of its express or implied subtasks or in view of the benefits obtained or groups of benefits. Some of the definitions contained in the following claims may then be unnecessary in view of the separate idea. The features of the different embodiments of the invention may, within the scope of the basic inventive idea, be applicable to other embodiments. In one embodiment, at least half of the upper blades, preferably all of the upper blades, have a jet angle of 5°-45°. One advantage is that the particle distribution and velocity distribution can be further improved. In one mode, the jet angle of the upper blade is in the range of 10° 40°, preferably 20° - 35°. One advantage is that the particle distribution and velocity distribution can be further improved. In one embodiment, the angle of attack of at least one of said plurality of upper blades is in the range of 65° - 85°, preferably 70° - 80°. One advantage is that low energy consumption of the impeller can be achieved. In one embodiment, at least half of the upper blades, preferably all of the upper blades, have an angle of attack of 65° - 85°, preferably 70° - 80°. One advantage is that the impeller's energy consumption can be further reduced. In one embodiment, the base edge of the upper blade is chamfered and / or curved. Another advantage is that the areas of the upper blade most vulnerable to erosion can be reduced, thus achieving a longer operating life for the impeller. In one configuration, the height of the upper blade is 12% - 20% of the impeller diameter (D). One advantage is that low shear stress and lower (higher) total pressures can be achieved on the impeller surface. In one embodiment, the jet angle of at least one of said plurality of lower vanes is in the range of -35° to 35°, preferably -10° to 10°, more preferably 0°. One advantage is that a high pumping capacity can be achieved. In one embodiment, at least half of the lower blades, preferably all of the lower blades, have a jet angle of -35° to 35°, preferably -10° to 10°, more preferably 0°. lA / E'ZUZÚ / UOOU IO One advantage is that an even greater pumping capacity can be achieved. In one embodiment, the angle of attack of at least one of said plurality of lower blades is in the range of 65° - 85°, preferably approximately 70° - 80°. One advantage is that low energy consumption of the impeller can be achieved. In one embodiment, at least half of the lower blades, preferably all of the lower blades, have an angle of attack of 65° - 85°, preferably 70° - 80°. One advantage is that the energy consumption of the impeller can be reduced even further. In one embodiment, the angle of attack of at least one of said plurality of lower blades, preferably of at least half of the lower blades, more preferably of all the lower blades, is different from the angle(s) of attack of the upper blades. One advantage is that the energy consumption of the impeller can be optimized. In one version, the base edge of the lower blade is curvilinear. One advantage is that this base edge shape can improve the gas dispersion properties of the impeller. In one configuration, the height of the lower blade is 20-30% of the impeller diameter (D). One advantage is that the flow near the walls of the mixing tank can be improved. In one embodiment, the hub disc around the axle fixing structure has a uniform thickness. One advantage is that the cube disc is more practical to manufacture from a single sheet material. In one configuration, the total height of the impeller is in the range of 35-50% of the impeller diameter. One advantage is that low shear stresses and low total pressures can be achieved on the impeller surface. In one configuration, the blade length is in the range of 50-60% of the impeller radius. One advantage is that the energy consumption of the impeller can be optimized. In one configuration, the number of upper blades is equal to the number of lower blades. One advantage is that the balance of the impeller can be improved. In one modality, the arrangement includes an autoclave. One advantage is that the impeller can be used in processes where high temperature and pressure are required, such as the pressure oxidation process (POX) to leach various sulfide minerals, which contain iron, nickel, cobalt, zinc, or copper. BRIEF DESCRIPTION OF THE FIGURES Some of the modalities that illustrate the present description are described in more detail in the accompanying figures, in which Figure 1 is a schematic perspective view of an agitator impeller, Figure 2 is a schematic top view of the agitator impeller shown in Figure 1. Figure 3 is a schematic bottom view of the agitator impeller shown in Figure 1. Figure 4 is a schematic side view of the agitator impeller shown in Figure 1. Figure 5 is a schematic side view of a partial cross-section mixing arrangement. Figure 6 illustrates the flow pattern of a prior art agitator impeller, and Figure 7 illustrates the flow pattern of a described agitator impeller. In the figures, some features are simplified for clarity. Similar parts are marked with the same reference numbers. DETAILED DESCRIPTION Figure 1 is a schematic perspective view of an agitator impeller, Figure 2 is a top schematic view of the agitator impeller shown in Figure 1, Figure 3 is a bottom schematic view of the agitator impeller shown in Figure 1, and Figure 4 is a side schematic view of the agitator impeller shown in Figure 1. The agitator impeller 1 comprises a hub disc 2 with a shaft mounting structure 3 centrally arranged on the hub disc to receive a shaft 4 centrally located and perpendicular to an upper side of the hub disc 2. It should be noted that only a portion of the shaft is shown in the figures. The shaft 4 can be attached to the mounting structure 3, for example, by fastening means such as bolts, welding, etc. The impeller 1 can be attached to the shaft 4 in a detachable manner, meaning the impeller can be replaced with a new one without changing the shaft 4. Alternatively, the impeller 1 is attached to the shaft 4 in an inseparable manner, meaning the impeller and shaft 4 are replaced as an integrated unit. Arrow R indicates the direction of rotation of the impeller 1. The impeller 1 comprises a plurality of upper blades 5 arranged on the upper side of the hub disk 2, and a plurality of lower blades 6 arranged on a lower side of the hub disk 2. lA / E'ZUZÚ / UOOU IO The impeller 1 is made of metallic material, such as steel or titanium alloy. In some embodiments, the impeller 1, or at least some surface sections thereof, comprise a coating. Preferably, the blades 5, 6, and the hub disc 2 are made of sheet material. The blade 5, 6 is normally manufactured separately and attached to the hub disc 2, for example, by welding. In one embodiment, a groove 13 (shown in Figure 4) is provided in the hub disc 2 in which the blade is disposed and fixed thereto, for example, by welding. The blade 5, 6 may comprise a tongue disposed in the groove (as shown in Figure 4), or alternatively, the groove has a width corresponding to the width of the blade. In yet another embodiment, a mortise and tenon joint is used to fix the blade to the hub disc. At least one of said plurality of upper blades 5 has a jet angle Ju of 5o- 45°. The meaning of the jet angle (the upper jet angle Ju shown in figure 2 and the lower jet angle Jl shown in figure 3) in this description is an angle between the radius r of the hub disk crossing the intersection of the hub disk 2 and the leading surface 14 of the blade at the base edge 7, and the direction of an intersection between a leading surface of the blade and the hub disk. Positive jet angle means that during the impeller rotation R, the inner edge of a blade crosses a radius r of the impeller before the outer edge of that blade. In one mode, the jet angle Ju of the upper blade 5 is in the range of 10° - 40°. In one mode, the jet angle Ju of the upper blade 5 is in the range of 20° - 35°. In one embodiment, at least half of the upper blades 5, preferably all the upper blades, have a jet angle Ju of 5°-45°, for example in the range of 10°-40°. In one embodiment, at least half of the upper blades 5, preferably all of the upper blades, have a jet angle Ju of 20° - 35°. In the configuration shown in the figures, all the upper blades 5 have a jet angle Ju in the range of 5° - 45°, more precisely approximately 25°. In one embodiment, an angle of attack Lu (shown in Figure 4) of at least one of said plurality of upper blades 5 is in the range of 65° - 85°, for example in the range of 70° - 80°. In the embodiment shown in the figures, all the upper blades 5 have an angle of attack Lu in said range, more precisely approximately 75°. The meaning of the angle of attack in this description is the angle between the disk of lA / E / ZUZJ / UOOUlO cube 2 and a blade attack surface. The lower blades 6 have a jet angle Jl different from the jet angle Ju of the upper blades. In one configuration, the jet angle Jl of the lower blade 6 is selected in the range of -35° to 35°. In one mode, the jet angle Jl of the lower vane 6 is selected in the range of -10° to 10°. In one mode, as shown in the figures, the jet angle Jl of the lower blades is 0o. In one configuration, the angle of attack Ll of at least one, such as at least half, or even all, of the lower blades 6 is in the range of 65° - 85°, for example in the range of 70° - 80°. In one configuration, such as the one shown in the figures, the angle of attack Ll of the lower blades is 75°. In one embodiment, the angle of attack Ll of at least one of the lower blades is different from the angle or angles of attack Lu of the upper blades. In one configuration, the angle of attack Ll of at least half of the lower blades is different from the angle or angles of attack Lu of the upper blades. In one configuration, the angle of attack Ll of all the lower blades is different from the angle or angles of attack Lu of the upper blades. The shape of the upper and lower blades 5, 6 can vary. For example, the base edge 7 of blade 5, 6 can be chamfered, curvilinear, or a combination of both. In one embodiment, all the upper blades 5 have a similar shape. In another embodiment, all the lower blades 6 have a similar shape. However, such similarity is not always required. In one embodiment, as shown in the figures, the upper blade 5 has a chamfered base edge, while the lower blade 6 has a curvilinear shape. The blade may be solid, but it may also comprise at least one orifice through which the fluid can flow. In one configuration, the height Hu of the upper blade is 12-20% of the impeller diameter D. In one embodiment, the height Hl of the lower blade 6 is 20-30% of the impeller diameter D. In one embodiment, the hub disc 2 around the shaft fixing structure 3 has a uniform thickness. The hub disc 2 is preferably made from a single sheet of metal. However, in some embodiments, the hub disc 2 may have a variable thickness; for example, the thickness may increase from the outer edge toward the shaft fixing structure 3. In one embodiment, the thickness at the shaft fixing structure 3 is 30%–50% greater than at the outer edge. The cube disk 2 can be round, as shown in the figures. In one embodiment, disk 2 has a polygonal shape, for example, such that the outer edge of disk 2 lies straight between two blades. The impeller diameter is typically in the range of 500 mm to 3000 mm. In one embodiment, as shown in the figures, the impeller diameter D is at least substantially equal to the diameter of the hub disk 2, since the outer edges 8 of the blades 5, 6 terminate at the outer edge of the hub disk 2. It should be noted, however, that in another embodiment at least some of the blades may extend over the outer edge of the hub disk 2. In yet another embodiment, at least some of the blades 5, 6 do not extend to the outer edge of the hub disk 2. In one mode, a total height Htot (shown in figure 4) of the impeller is in a range of 35-50% of the impeller diameter (D). In one embodiment, the blade length L is in the range of 50-60% of the impeller radius. This length L is measured at the intersection of the blade and the hub disk 2. In one configuration, as shown in the figures, the number of upper blades (5) is equal to the number of lower blades (6). In another configuration, the number of upper blades (5) is greater than the number of lower blades (6). In yet another configuration, the number of upper blades (5) is less than the number of lower blades (6). There can be an even or odd number of blades. In one embodiment, as shown in the figures, the lower blades 6 are at least substantially aligned with the upper blades 5. However, this is not always necessary. Therefore, in another embodiment, the blades are misaligned. Figure 5 is a schematic side view of a partial cross-section of a 100 mix arrangement. Arrangement 100 comprises a mixing tank 9, such as an autoclave, and agitator impeller(s) 1 described in this description arranged in the mixing tank 9 and attached to a shaft 4. The arrangement 100 shown in Figure 5 comprises three compartments 10. The first compartment 10a is provided with an agitator impeller 1 described herein. The second compartment 10b is provided with two agitator impellers fixed to the same shaft 4. One of these impellers is of the type 1 described herein, while the other impeller 12 is of a different type, differing from impeller 1. The third compartment 10c shown in Figure 5 comprises only one impeller 12, which differs from the impellers 1 described herein. Thus, all the impellers included in arrangement 100 need not be of the type described herein. The impellers 1, 12 are arranged to be turned by a motor 11, such as an electric motor. It should be noted that the arrangement 100 can vary in many ways. For example, the number of compartments can be one, two, or more than three. There can be two or more agitator impellers 1 arranged on two or more shafts 4 in a compartment. In one embodiment, the autoclave 9 is arranged for the pressure oxidation of a slurry material. The slurry material may comprise, for example, at least one sulfide material. In one embodiment, the agitator impeller 1 and arrangement 100 are used to mix gas into slurry. In one embodiment, said slurry has a particle concentration in the range of 10% to 60% by weight. In one embodiment, the agitator impeller 1 and arrangement 100 are used to leach sulphurous material containing iron. In one embodiment, the agitator impeller 1 and arrangement 100 are used to leach sulphurous material containing nickel. In one embodiment, the agitator impeller 1 and arrangement 100 are used to leach sulphurous material containing cobalt. In one embodiment, the agitator impeller 1 and arrangement 100 are used to leach sulphurous material containing zinc. In one embodiment, the agitator impeller 1 and arrangement 100 are used to leach sulphurous material containing copper. Figure 6 illustrates the flow pattern of a prior art agitator impeller, and Figure 7 illustrates the flow pattern of the described agitator impeller. The darker the flow, the higher the particle concentration. It is readily apparent that the particle concentration near the impeller surface is significantly reduced with the new impeller compared to the prior art impeller. The invention is not limited solely to the embodiments described above, but many variations are possible within the scope of the inventive concept defined by the following claims. Within the scope of the inventive concept, the attributes of different embodiments and applications may be used in conjunction with or in place of the attributes of another embodiment or application. The figures and related description are intended only to illustrate the idea of ​​the invention. The invention may vary in detail within the scope of the inventive idea defined in the following claims. REFERENCE SYMBOLS impeller agitator hub disc shaft fixing structure shaft upper blade lower blade base edge outer edge mixing tank motor compartment second-type impeller groove leading surface 100 disposition D impeller diameter Hu upper height Hl lower height Total height Ju upper jet angle Jl lower jet angle L blade length Lu upper attack angle Lower angle of attack R direction of rotation r radius

Claims

1. An agitator impeller (1), CHARACTERIZED in that it comprises - a hub disc (2) comprising a shaft fixing structure (3) arranged centrally in the hub to receive a shaft (4) central and perpendicular from an upper side of the hub disc (2), - a plurality of upper vanes (5) arranged on the upper side of the hub disc (2), - a plurality of lower vanes (6) arranged on a lower side of the hub disc (2), - wherein at least one of said plurality of upper vanes (5) is arranged to have a jet angle (Ju) of 5° - 45°, and wherein - the lower vanes (6) have a jet angle (Jl) different from said jet angle (Ju) of at least one of said plurality of upper vanes.

2. The agitator impeller according to claim 1, CHARACTERIZED in that - at least half of the upper vanes (5), preferably all the upper vanes, have a jet angle (Ju) of 5° - 45°.

3. The agitator impeller according to claim 1 or 2, CHARACTERIZED in that - said jet angle (Ju) of the upper vane (5) is in a range of 10° - 40°, preferably 20° - 35°.

4. The agitator impeller according to any of the preceding claims, CHARACTERIZED in that - an angle of attack (Lu) of at least one of said plurality of upper vanes (5) is in the range of 65° - 85°, preferably 70° - 80°.

5. The agitator impeller according to any of the preceding claims, CHARACTERIZED in that - at least half of the upper blades (5), preferably all of the upper blades, have an angle of attack (Lu) of 65° - 85°, preferably 70° - 80°.

6. The agitator impeller according to any of the preceding claims, CHARACTERIZED in that - the base edge (7) of the upper blade is chamfered and / or curvilinear.

7. The agitator impeller according to any of the preceding claims, CHARACTERIZED in that - the height (Hu) of the upper vane is 12-20% of the impeller diameter (D). IA / EZUZÚ / U30U 10 8. The agitator impeller according to any of the preceding claims, CHARACTERIZED in that - the jet angle (Jl) of at least one of said plurality of lower vanes (6) is in the range of -35° to 35°, preferably -10° to 10°, more preferably 0°.

9. The agitator impeller according to any of the preceding claims, CHARACTERIZED in that - at least half of the lower vanes (6), preferably all of the lower vanes, have a jet angle (Jl) of -35° to 35°, preferably -10° to 10°, more preferably 0°.

10. The agitator impeller according to any of the preceding claims, CHARACTERIZED in that - an angle of attack (Ll) of at least one of said plurality of lower vanes (6) is in the range of 65° - 85°, preferably 70° - 80°.

11. The agitator impeller according to any of the preceding claims, CHARACTERIZED in that - at least half of the lower blades (6), preferably all of the lower blades, have an angle of attack (Ll) of 65° - 85°, preferably 70° - 80°.

12. The agitator impeller according to any of the preceding claims, CHARACTERIZED in that - the angle of attack (Ll) of at least one of said plurality of lower blades (6), preferably of at least half of the lower blades (6), more preferably of all the lower blades is different from the angle(s) of attack (Ll) of the upper blades (5).

13. The agitator impeller according to any of the preceding claims, CHARACTERIZED in that the base edge (7) of the lower blade (6) is curvilinear.

14. The agitator impeller according to any of the preceding claims, CHARACTERIZED in that - the height (Hl) of the lower vane (6) is 20-30% of the impeller diameter (D).

15. The agitator impeller according to any of the preceding claims, CHARACTERIZED in that - the hub disc (2) around the shaft fixing structure (3) has a uniform thickness.

16. The agitator impeller according to any of the preceding claims, CHARACTERIZED in that lA / E / ZUZJ / UOOUlO - the total height (Htot) of the impeller is in a range of 35-50% of the impeller diameter (D).

17. The agitator impeller according to any of the preceding claims, CHARACTERIZED in that the length (L) of the blade is in a range of 50-60% of the radius of the impeller.

18. The agitator impeller according to any of the preceding claims, CHARACTERIZED in that - the number of upper blades (5) is equal to the number of lower blades (6).

19. The agitator impeller according to any of the preceding claims, CHARACTERIZED in that - the diameter of the impeller (D) is at least substantially equal to the diameter of the hub disc (2).

20. Arrangement (100) for mixing gas with mud, CHARACTERIZED in that it comprises - a mixing tank (9), - at least one agitator impeller (1) according to any of the preceding claims, arranged in the mixing tank (9) and fixed to a shaft (4), and - a motor (11) for rotating the shaft (4) and the agitator impeller (1).

21. The arrangement according to claim 20, CHARACTERIZED in that - the mixing tank (9) is an autoclave.

22. The arrangement according to claim 21, CHARACTERIZED in that - the autoclave is arranged for pressure oxidation of a slurry material comprising at least one sulfide material.

23. The arrangement according to any of claims 20-22, CHARACTERIZED in that it comprises - at least two agitator impellers (1) according to any of claims 1-19.

24. Use of the agitator impeller in accordance with any of claims 1 to 19 CHARACTERIZED in that it is for mixing gas in mud.

25. Use of the agitator impeller in accordance with any of claims 1 to 19 CHARACTERIZED in that it is for leaching sulphurous material containing iron.

26. Use of the agitator impeller according to any of claims 1 - 19 CHARACTERIZED in that it is for leaching sulphurous material containing nickel.

27. Use of the agitator impeller according to any of claims 1-19 CHARACTERIZED in that it is for leaching sulfurous material containing cobalt.

28. Use of the agitator impeller according to any of claims 1-19 CHARACTERIZED in that it is for leaching sulphurous material containing zinc.

29. Use of the agitator impeller according to any of claims 1-19 CHARACTERIZED in that it is for leaching sulphurous material containing copper.

Images