Patent Description:
The invention relates also to an arrangement and a method for producing paste.

<CIT> discloses a double shaft paddle mixer comprising a barrel chamber, a first paddle screw and a second paddle screw.

The object is to provide a double shaft paddle mixer that is capable of making fluid such as paste or slurry of pieces comprising particulate material such as finer clay, silt, filtered solids, or sand sized material, which pieces having a size that can be between <NUM> and <NUM>.

The double shaft paddle mixer is characterized by the definitions of independent claim <NUM>.

Preferred embodiments of the double shaft paddle mixer are defined in the dependent claims <NUM> to <NUM>.

The invention relates also to an arrangement for producing paste as defined in claim <NUM>.

Preferred embodiments of the arrangement for producing paste are defined in independent claims <NUM>-<NUM>.

The invention relates also to a method for producing paste as defined in claim <NUM>.

The idea is based on dividing the barrel chamber of the double shaft paddle mixer into a crushing zone and a mixing zone by means of a partition member preventing pieces of comprising particulate material having a too large size from exiting the crushing zone and enter the mixing zone. A first inlet that can be capable of receiving pieces comprising particulate material, which pieces having a size between <NUM> and <NUM> is connected to an upstream region of the crushing zone of the barrel chamber and a second inlet that can be configured to receive fluid such as liquid, suspension or slurry is connected to an upstream region of the mixing zone of the barrel chamber. Because the average paddle angle of the first paddles and of the second paddles with respect to the centerline of the first paddle screw and of the second paddle screw is larger in the mixing zone of the barrel chamber than in the crushing zone of the barrel chamber, the material that is fed into the crushing zone of the barrel chamber via the first inlet will move slower in the crushing zone of the barrel chamber than material in the mixing zone of the barrel chamber, after said material having been shredded in the crushing zone of the barrel chamber and having entered the mixing zone of the barrel chamber and after fluid being added to said material via the second inlet. The result of this is an increased residence time in the crushing zone of the barrel chamber which is an advantage, because the size of the pieces that exits the crushing zone of the barrel chamber to enter the mixing zone of the barrel chamber must be small enough to pass the partition member between the crushing zone and the mixing zone. The crushing in the crushing zone can be autogenous.

In the following the double shaft paddle mixer will described in more detail by referring to the figures of which.

The figures show an embodiment of the double shaft paddle mixer.

The double shaft paddle mixer comprising a barrel chamber <NUM> that is elongated and that extends axially.

The double shaft paddle mixer comprising a first paddle screw <NUM> and a second paddle screw <NUM> configured to rotate together in the barrel chamber <NUM> in an intermeshing relationship. For the rotation of the first paddle screw <NUM> and the second paddle screw <NUM> can either a common or separate rotation means <NUM> such as electric motors be provided.

The first paddle screw <NUM> is provided with first paddles <NUM> and the second paddle screw <NUM> is provided with second paddles <NUM>.

The barrel chamber <NUM> comprises a crushing zone <NUM> and a mixing zone <NUM> so that the crushing zone <NUM> is partly separated from the mixing zone <NUM> by a partition member <NUM>. In other words, the partition member <NUM> is arranged in the barrel chamber <NUM> so that a limited passage <NUM> is provided at the partition member <NUM> between the crushing zone <NUM> of the barrel chamber <NUM> and the mixing zone <NUM> of the barrel chamber <NUM>. The purpose of the limited passage <NUM> is to prevent that pieces having a too large size moves from the crushing zone <NUM> of the barrel chamber <NUM> to the mixing zone <NUM> of the barrel chamber <NUM>. This assures that the first paddles <NUM> of the first paddle screw <NUM> and that the second paddles <NUM> of the second paddle screw <NUM> have to a sufficient degree fine-divided the matter that passes through the limited passage <NUM> at the partition member when matter exits the crushing zone <NUM> of the barrel chamber <NUM> and to enter the mixing zone <NUM> of the barrel chamber <NUM>.

The thickness of the first paddles <NUM> and the second paddles <NUM> is preferably, but not necessarily, between <NUM> and <NUM> at least in the crushing zone <NUM> of the barrel chamber <NUM> to provide for effective crushing effect by hitting the pieces comprising particulate material in the crushing zone <NUM> of the barrel chamber as the first paddle screw <NUM> and the second paddle screw <NUM> rotates.

A first inlet <NUM> is connected to an upstream region of the crushing zone <NUM> of the barrel chamber <NUM>, and a second inlet <NUM> is connected to an upstream region of the mixing zone <NUM> of the barrel chamber <NUM> and an outlet <NUM> connected to a downstream region of the mixing zone <NUM> of the barrel chamber <NUM>.

The average paddle angle of the first paddles <NUM> with respect to the centerline of the first paddle screw <NUM> and of the second paddles <NUM> with respect to the centerline of the second paddle screw <NUM> is larger in the mixing zone <NUM> than in the crushing zone <NUM>.

The first paddles <NUM> of the first paddle screw <NUM> are configured by rotating, and the second paddles <NUM> of the second paddle screw <NUM> are configured by rotating to move matter present in the barrel chamber <NUM> from the upstream end of the crushing zone <NUM> towards the downstream end of the mixing zone <NUM>.

The average paddle angle in crushing zone <NUM> can for example be between <NUM> and <NUM>°, preferably between <NUM> and <NUM>°, such as about <NUM>°.

The average paddle angle in mixing zone <NUM> can for example be between <NUM> and <NUM>°, preferably between <NUM> and <NUM>°, such as between <NUM> and <NUM>°.

The mixing zone <NUM> of the barrel chamber <NUM> can comprise a fluid adding zone <NUM> and a homogenization zone <NUM> so that the fluid adding zone <NUM> extends between the partition member <NUM> and the second inlet <NUM>, and so that the homogenization zone <NUM> extends between the fluid adding zone <NUM> and the outlet <NUM>. If the mixing zone <NUM> of the barrel chamber <NUM> comprises such fluid adding zone <NUM> and such homogenization zone <NUM>, the relative number of first paddles <NUM> and of second paddles <NUM> as calculated along the first rotation axis A of the first paddle screw <NUM> and as calculated along the second rotation axis B of the second paddle screw <NUM> is preferably, but not necessarily, larger in the homogenization zone <NUM> than in the mixing zone <NUM>. If the mixing zone <NUM> of the barrel chamber <NUM> comprises such fluid adding zone <NUM> and such homogenization zone <NUM>, the average paddle angle of the first paddles <NUM> and of the second paddles <NUM> with respect to the centerline of the first paddle screw <NUM> and of the second paddle screw <NUM> is preferably, but not necessarily, larger in the homogenization zone <NUM> than in the mixing zone <NUM>.

The relative number of first paddles <NUM> and of second paddles <NUM> as calculated along the first rotation axis A of the first paddle screw <NUM> and as calculated along the second rotation axis B of the second paddle screw <NUM> is preferably, but not necessarily, larger in the crushing zone <NUM> of the barrel chamber <NUM> than in the mixing zone <NUM> of the barrel chamber <NUM>.

The first paddle screw <NUM> and the second paddle screw <NUM> extend preferably, but not necessarily, in parallel in the barrel chamber <NUM>, and the first paddle screw <NUM> and the second paddle screw <NUM> are preferably, but not necessarily, configured to rotate in opposite directions about their rotational axis.

The partition member <NUM> extends from an inner surface <NUM> limiting the barrel chamber <NUM>, so that the limited passage <NUM> provided at the partition member <NUM> between the crushing zone <NUM> of the barrel chamber <NUM> and the mixing zone <NUM> of the barrel chamber <NUM> essentially correspond to the cross section of the shape <NUM> the first paddle screw <NUM> and the second paddle screw <NUM> together have as they rotates in the barrel chamber <NUM> as illustrated in <FIG>. This to ensure that the pieces comprising particulate material have been crushed to a sufficient degree before the pieces can pass the partition member <NUM> and travel from the crushing zone <NUM> of the barrel chamber <NUM> to the mixing zone <NUM> of the barrel chamber <NUM>.

The size of the first paddles <NUM> of the first paddle screw <NUM> is preferably, but not necessarily, selected so that the first paddles <NUM> extend <NUM> to <NUM> from the first shaft <NUM> of the first paddle screw <NUM> to achieve effective crushing and mixing action. The size of the second paddles <NUM> of the second paddle screw <NUM> is preferably, but not necessarily, selected so that the second paddles <NUM> extend <NUM> to <NUM> from the first second <NUM> of the second paddle screw <NUM> to achieve effective crushing and mixing action.

At least some of first blades are preferably, but not necessarily, at least partly paddle shaped, propeller blade shaped, or curved.

At least some of the second blades are preferably, but not necessarily, at least partly paddle shaped, propeller blade shaped, or curved.

The first inlet <NUM> has preferably, but not necessarily, an opening capable of receiving pieces having a size between <NUM> and <NUM>. The first inlet <NUM> provided a passage that leads to the barrel chamber <NUM> of the double shaft paddle mixer.

The second inlet <NUM> can be in fluid connection with a source for fluid (not shown in the figures) such as liquid, suspension or slurry. The second inlet <NUM> provided a passage that leads to the barrel chamber <NUM> of the double shaft paddle mixer.

The partition member <NUM> is preferably, but not necessarily, adjustable arranged in the barrel chamber <NUM> so at to adjust the size and/or form of the limited passage <NUM> at the partition member <NUM> between the crushing zone <NUM> of the barrel chamber <NUM> and the mixing zone <NUM> of the barrel chamber <NUM>.

The partition member <NUM> is preferably, but not necessarily, releasable arranged in the barrel chamber <NUM> so as to allow changing or replacing of the partition member <NUM> with another partition member. The other partition member <NUM> can for example be configured to provide a limited passage <NUM> having another size and/or form of the limited passage <NUM> at the partition member <NUM> between the crushing zone <NUM> of the barrel chamber <NUM> and the mixing zone <NUM> of the barrel chamber <NUM>. A need to replace the partition member <NUM> can also arise if the partition member <NUM> wears due to erosion with the result that the size and/or form of the limited passage <NUM> at the partition member <NUM> between the crushing zone <NUM> of the barrel chamber <NUM> and the mixing zone <NUM> of the barrel chamber <NUM> changes.

The first paddle screw <NUM> and the second paddle screw <NUM> are preferably, but not necessarily, mirror identical.

The double shaft paddle mixer is preferably, but not necessarily, essentially completely made of metal such as of steel.

At least one of the crushing zone <NUM> and the mixing zone <NUM> of the barrel chamber <NUM> can have an at least partly replaceable inner lining (not illustrated).

At least one of the fluid adding zone <NUM> and the mixing zone <NUM> of the barrel chamber <NUM> having third inlet for adding chemical to enhance viscosity of paste produced with the double shaft paddle mixer.

Next an arrangement for producing fluid such as paste or slurry will be described in greater detail.

The arrangement comprises a filter press <NUM> for dehydrating feeding material <NUM>, and a double shaft paddle mixer <NUM> in the form of any embodiment presented. A first inlet <NUM> of the double shaft paddle mixer <NUM> is in fluid connection with the filter press <NUM> and configured to receive pieces of particulate material <NUM> from the filter press <NUM>. The filter press <NUM> is in fluid connection with a gravity-based separator <NUM>.

The arrangement can comprise a tank <NUM> for paste <NUM> in fluid connection with an outlet <NUM> of the double shaft paddle mixer <NUM>.

The gravity-based separator <NUM> can be part of a mineral beneficiation flotation arrangement, wherein the filter press <NUM> is in fluid connection with gravity-based separator <NUM> that is in fluid connection with the last flotation vessel <NUM> in a series of flotation vessels <NUM> and wherein the first flotation vessel <NUM> in said series of floatation vessels <NUM> is in fluid connection with a grinder <NUM>. The gravity-based separator <NUM> can be in fluid connection the fluid adding zone <NUM> of the barrel chamber <NUM> of the double shaft paddle mixer <NUM> via a second inlet <NUM> of the double shaft paddle mixer <NUM>.

Next the method for producing fluid such as paste or slurry and some embodiments of the method will be described in greater detail.

The method comprises feeding material <NUM> to be dehydrated to a filter press <NUM> from the gravity-based separator <NUM>.

The method can comprise feeding material <NUM> to be dehydrated to a filter press <NUM> from the gravity-based separator <NUM> of a mineral beneficiation flotation arrangement, wherein the filter press <NUM> is in fluid connection with the last flotation vessel <NUM> in a series of flotation vessels <NUM> and wherein the first flotation vessel <NUM> in said series of floatation vessels <NUM> is in fluid connection with a grinder <NUM>.

The method comprises producing particulate material in the filter press <NUM>.

The method comprises breaking said particulate material into pieces of particulate material <NUM>.

The method comprises feeding said pieces of particulate material into a crushing zone <NUM> of a barrel chamber <NUM> of the double shaft paddle mixer <NUM> via a first inlet <NUM> of the double shaft paddle mixer <NUM>.

The method comprises crushing said pieces of particulate material in the crushing zone <NUM> of the barrel chamber <NUM> of the double shaft paddle mixer <NUM> to produce crushed pieces of particulate material in the double shaft paddle mixer <NUM>.

The method comprises moving crushed pieces of particulate material in the double shaft paddle mixer <NUM> from the crushing zone <NUM> into a fluid adding zone <NUM> of the barrel chamber <NUM> of the double shaft paddle mixer <NUM>.

The method comprises feeding fluid into the fluid adding zone <NUM> of the barrel chamber <NUM> of the double shaft paddle mixer <NUM> via a second inlet <NUM> of the double shaft paddle mixer <NUM>.

The method comprises feeding fluid from the gravity-based separator <NUM> into the fluid adding zone <NUM> of the barrel chamber <NUM> of the double shaft paddle mixer <NUM> via a second inlet <NUM> of the double shaft paddle mixer <NUM>.

The method comprises mixing fluid and crushed pieces of particulate material in the fluid adding zone <NUM> of the double shaft paddle mixer <NUM> while moving fluid and crushed pieces of particulate material from the fluid adding zone <NUM> of the double shaft paddle mixer <NUM> to a homogenization zone <NUM> of the barrel chamber <NUM> of the double shaft paddle mixer <NUM> to produce paste <NUM> of fluid and crushed pieces of particulate material in the homogenization zone <NUM> of the barrel chamber <NUM> of the double shaft paddle mixer <NUM>.

The method comprises discharging paste <NUM> from the homogenization zone <NUM> of the barrel chamber <NUM> of the double shaft paddle mixer <NUM> to the outside of the barrel chamber <NUM> of the double shaft paddle mixer <NUM> via an outlet <NUM> of the double shaft paddle mixer <NUM>.

Next an alternative method for producing fluid such as paste or slurry and some embodiments of the method will be described in greater detail.

The alternative method comprises providing a double shaft paddle mixer <NUM> according to any embodiment presented earlier.

The method comprises feeding material <NUM> to be dehydrated to a filter press <NUM> from a gravity-based separator <NUM>. The method comprises preferably, but not necessarily, feeding material <NUM> to be dehydrated to a filter press <NUM> from a gravity-based separator <NUM> of a mineral beneficiation flotation arrangement, wherein the filter press <NUM> is in fluid connection with the last flotation vessel <NUM> in a series of flotation vessels <NUM> and wherein the first flotation vessel <NUM> in said series of floatation vessels <NUM> is in fluid connection with a grinder <NUM>.

The method comprises feeding said pieces of particulate material into the crushing zone <NUM> of the barrel chamber <NUM> of the double shaft paddle mixer <NUM> via the first inlet <NUM> of the double shaft paddle mixer <NUM>.

The method comprises moving crushed pieces of particulate material in the double shaft paddle mixer <NUM> from the crushing zone <NUM> into the mixing zone <NUM> of the barrel chamber <NUM> of the double shaft paddle mixer <NUM>.

The method comprises feeding fluid into the mixing zone <NUM> of the barrel chamber <NUM> of the double shaft paddle mixer <NUM> via the second inlet <NUM> of the double shaft paddle mixer <NUM>.

The method can comprise feeding fluid from the gravity-based separator <NUM> into the mixing zone <NUM> of the barrel chamber <NUM> of the double shaft paddle mixer <NUM> via the second inlet <NUM> of the double shaft paddle mixer <NUM>.

The method comprises mixing fluid and crushed pieces of particulate material in the mixing zone <NUM> of the double shaft paddle mixer <NUM> while moving fluid and crushed pieces of particulate material in the mixing zone <NUM> of the double shaft paddle mixer <NUM> to produce paste <NUM> of fluid and crushed pieces of particulate material in the mixing zone <NUM> of the barrel chamber <NUM> of the double shaft paddle mixer <NUM>.

The method comprises discharging paste <NUM> from the mixing zone <NUM> of the barrel chamber <NUM> of the double shaft paddle mixer <NUM> to the outside of the barrel chamber <NUM> of the double shaft paddle mixer <NUM> via an outlet <NUM> of the double shaft paddle mixer <NUM>.

The methods can include feeding the paste to a tank <NUM> for paste <NUM>.

The particulate material <NUM> has preferably, but not necessarily, a residual moisture between <NUM> and <NUM> %.

The fluid <NUM> has preferably, but not necessarily, a residual moisture between <NUM> and <NUM> %.

The paste <NUM> has preferably, but not necessarily, a moisture between <NUM> and <NUM> %.

Claim 1:
A double shaft paddle mixer,
comprising a barrel chamber (<NUM>) that is elongated and that extends axially, and a first paddle screw (<NUM>) and a second paddle screw (<NUM>) configured to rotate together in the barrel chamber (<NUM>) in an intermeshing relationship,
the first paddle screw (<NUM>) being provided with first paddles (<NUM>) and the second paddle screw (<NUM>) being provided with second paddles (<NUM>),
the barrel chamber (<NUM>) comprising a crushing zone (<NUM>) and a mixing zone (<NUM>),
the crushing zone (<NUM>) being partly separated from the mixing zone (<NUM>) by a partition member (<NUM>),
a first inlet (<NUM>) being connected to an upstream region of the crushing zone (<NUM>),
a second inlet (<NUM>) being connected to an upstream region of the mixing zone (<NUM>) and an outlet (<NUM>) connected to a downstream region of the mixing zone (<NUM>), and
the average paddle angle of the first paddles (<NUM>) with respect to the centerline of the first paddle screw (<NUM>) and of the second paddles (<NUM>) with respect to the centerline of the second paddle screw (<NUM>) being larger in the mixing zone (<NUM>) than in the crushing zone (<NUM>), and
the partition member (<NUM>) extending from an inner surface limiting the barrel chamber (<NUM>), and
a limited passage (<NUM>) provided at the partition member (<NUM>) between the crushing zone (<NUM>) of the barrel chamber (<NUM>) and the mixing zone (<NUM>) of the barrel chamber (<NUM>) essentially corresponding to the cross section of the shape (<NUM>) the first paddle screw (<NUM>) and the second paddle screw (<NUM>) together form as they rotate in the barrel chamber (<NUM>).