Double shaft paddle mixer and arrangement and methods for producing paste
A double shaft paddle mixer, including a barrel chamber, and a first paddle screw and a second paddle screw. The first paddle screw is provided with first paddles and the second paddle screw is provided with second paddles. The barrel chamber includes a crushing zone and a mixing zone. The crushing zone is partly separated from the mixing zone by a partition member. A first inlet is connected to the crushing zone and a second inlet is connected to the mixing zone and an outlet connected to the mixing zone. The double shaft paddle mixer can be part of an arrangement and part of a method for producing paste.
1 . A double shaft paddle mixer, comprising:
a barrel chamber that is elongated and that extends axially;
a first paddle screw and a second paddle screw configured to rotate together in the barrel chamber in an intermeshing relationship,
the first paddle screw being provided with first paddles extending from a first shaft and the second paddle screw being provided with second paddles extending from a second shaft,
the barrel chamber comprising a crushing zone and a mixing zone,
the crushing zone being partly separated from the mixing zone by a partition member,
a first inlet connected to an upstream region of the crushing zone,
a second inlet being connected to an upstream region of the mixing zone and an outlet connected to a downstream region of the mixing zone, and
wherein the average paddle angle of the first paddles with respect to the centerline of the first paddle screw and the second paddles with respect to the centerline of the second paddle screw is larger in the mixing zone than in the crushing zone,
wherein the partition member extends from an inner surface of the barrel chamber,
wherein a limited passage is provided at the partition member between the crushing zone of the barrel chamber and the mixing zone of the barrel chamber essentially correspond to the cross section of the shape the first paddle screw and the second paddle screw together form as they rotates in the barrel chamber, and
wherein the relative number of first paddles and second paddles as calculated along a first rotation axis of the first paddle screw and as calculated along a second rotation axis of the second paddle screw is larger in the crushing zone than in the mixing zone.
2 . The double shaft paddle mixer according to claim 1 , wherein the average paddle angle in the crushing zone being between 1 and 10°.
3 . The double shaft paddle mixer according to claim 1 , wherein the average paddle angle in the mixing zone being between 5 and 25°.
4 . The double shaft paddle mixer according to claim 1 , wherein the mixing zone comprises a fluid adding zone and a homogenization zone,
wherein the fluid adding zone extends between the partition member and the second inlet, and
wherein the homogenization zone extends between the fluid adding zone and the outlet.
5 . The double shaft paddle mixer according to claim 1 , wherein the first paddle screw and the second paddle screw extend in parallel in the barrel chamber, and
wherein the first paddle screw and the second paddle screw are configured to rotate in opposite directions about their rotational axis.
6 . The double shaft paddle mixer according to claim 1 wherein at least some of first blades being at least partly paddle shaped, propeller blade shaped, or curved.
7 . The double shaft paddle mixer according to claim 1 wherein at least some of the second blades being at least partly paddle shaped, propeller blade shaped, or curved.
8 . The double shaft paddle mixer according to claim 1 wherein the first inlet has an opening capable of receiving pieces having a size between 100 and 200 mm.
9 . The double shaft paddle mixer according to claim 1 wherein the second inlet is in fluid connection with a source for fluid such as liquid, suspension or slurry.
10 . The double shaft paddle mixer according claim 1 , wherein the partition member is adjustable arranged in the barrel chamber so at to adjust the size and/or form of the limited passage at the partition member between the crushing zone of the barrel chamber and the mixing zone of the barrel chamber.
11 . The double shaft paddle mixer according to claim 1 , wherein the partition member is releasable arranged in the barrel chamber.
12 . The double shaft paddle mixer according to claim 1 wherein the first paddle screw and the second paddle screw are mirror identical.
13 . The double shaft paddle mixer according to claim 1 wherein at least one of the crushing zone and the mixing zone of the barrel chamber have an at least partly replaceable inner lining.
14 . The double shaft paddle mixer according to claim 1 wherein at least one of the fluid adding zone and the homogenization zone of the barrel chamber have a third inlet for adding a chemical.
15 . The double shaft paddle mixer according to claim 1 , wherein the average paddle angle in the crushing zone is between 2.5 and 7.5°.
16 . The double shaft paddle mixer according to claim 1 , wherein the average paddle angle in the crushing zone is about 5°.
17 . The double shaft paddle mixer according to claim 1 , wherein the average paddle angle in the mixing zone is between 1° and 20°.
18 . The double shaft paddle mixer according to claim 1 , wherein the average paddle angle in the mixing zone is between 1° and 15°.
19 . An arrangement for producing fluid such as paste or slurry, wherein the arrangement comprising:
a filter press for dehydrating feeding material, wherein the filter press is in fluid connection with a gravity-based separator;
a double shaft paddle mixer according to claim 1 ; and
wherein the first inlet of the double shaft paddle mixer is in fluid connection with the filter press and is configured to receive pieces of particulate material from the filter press.
20 . The arrangement according to claim 19 , further comprising a tank for paste in fluid connection with the outlet of the double shaft paddle mixer.
21 . The arrangement according claim 19 , wherein the gravity-based separator being part of a mineral beneficiation flotation arrangement, wherein the filter press is in fluid connection with gravity-based separator that is in fluid connection with a last flotation vessel in a series of flotation vessels and wherein a first flotation vessel in said series of floatation vessels is in fluid connection with a grinder.
22 . The arrangement according to claim 19 , wherein the gravity-based separator being in fluid connection the fluid adding zone of the barrel chamber of the double shaft paddle mixer via the second inlet of the double shaft paddle mixer.