"Lump Conditioner for a Mixer" in Patent Application Approval Process (USPTO 20160016131)
By a News Reporter-Staff News Editor at Politics & Government Week -- A patent application by the inventor Wallgren, Mark (
King City, CA
), filed on June 10, 2015, was made available online on January 28, 2016, according to news reporting originating from
, by VerticalNews correspondents.
This patent application has not been assigned to a company or institution.
The following quote was obtained by the news editors from the background information supplied by the inventors: "In various industries, mixers are used to uniformly mix various particulate materials. In many industries, for example mining, power generation, and oil sands, tailings are mixed with water to produce a material of consistent water content--a conditioned tailings to be used for further processing. In the mining industry, tailings result from the refinement of ore. These tailings are sometimes mixed together with water and cement to provide fill for underground mining methods. These tailings particles usually cover a spectrum of particle sizes ranging from clay size particles to sand sized particles (typically <1 .mu.m to >1 mm). When using the tailings to produce minefill, it is sometimes desirable to dewater the tailings to generate a fill with sufficient strength and pumpability at an optimized cost. Controlling the moisture content of the tailings is necessary to produce a fill with predictable strength. The process of producing tailings at a consistent moisture content is often accomplished by filtering part of the tailings stream and recombining it with a controlled amount of water to reach a target moisture content. Filtration of many tailings materials generates cohesive 'lumps' of material. In the case of minefill the lumps in the material can create problems with pumping the fill through pipelines. As such, these cohesive lumps are introduced into a mixer for mixing and conditioning with water to reduce the size and amount of lumps. Current mixers on the markets, however, are only designed for mixing and are inefficient at breaking down the lumps in the material.
"Various types of mixers which are known to be used for mixing various paste-like mixtures include horizontal single and twin shaft mixers, ribbon mixers, pan mixers, and planetary mixers. In a horizontal shaft mixer, conventional mixing blades are typically provided with a leading surface at an angle to the direction of motion, generally around 30 degrees off the normal plane of the motion vector. This pushes material to slide off the paddle and urges the material within the mixer not only in the circumferential direction of motion of the paddle, but also out of the plane of the motion of the paddles in an axial direction of the shaft. These motions of the material are required to effectively mix the material inside the mixer.
"The leading surface of the paddles are close to normal or even with a positive angle to the tangential surface (ie the boundary wall) of the mixer, and the leading edge of the paddle is adjusted to be directly adjacent to the boundary wall to prevent coarse gravel from being crushed between the paddle and the surface of the mixer. The leading edge is also close to the boundary wall of the mixer because that will scrape any material off the wall to ensure that the mixer stays clean without buildup along the surfaces of the boundary walls of the mixing chamber of the mixer.
"Although the arrangement of the mixing paddles described above have been found to be effective for mixing the paste, the known arrangement of paddles are ineffective at breaking up lumps or reducing lump size when mixing a paste-like mixture of moistened fine particles which has a tendency to clump."
In addition to the background information obtained for this patent application, VerticalNews journalists also obtained the inventor's summary information for this patent application: "The invention is a modification to existing mixers to make them suitable to condition lumps in the material being mixed.
"According to one aspect of the invention there is provided an improvement in a mixer comprising i) a vessel defining a mixing chamber therein surrounded by boundary walls for receiving a mixture containing lumps therein, ii) a plurality of mixing blades, and iii) a driving mechanism supporting the mixing blades in the mixing chamber for mixing motion relative to the vessel so as to mix the mixture within the mixing chamber of the vessel, in which the improvement comprises: a) the mixing blades including at least one lump conditioning blade having a rigid body terminating at a working edge along an outer side of the rigid body; and b) the driving mechanism supporting said at least one lump conditioning blade such that the lump conditioning blade is movable in a working direction along a respective one of the boundary walls with the working edge at a prescribed space from the boundary wall which is effective to reduce a lump size of the lumps in the mixture as the mixture passes between the working edge of the lump conditioning blade and the boundary wall.
"The lump conditioning blade effectively smears the lumps against the boundary walls of the mixing chamber of the mixer, to reduce the size of the lumps. The lump conditioning blade is particularly effective when used in combination with conventional mixing blades which subsequently scrape the smeared mixture off of the boundary walls subsequent to the lumps being broken up by the lump conditioning blade.
"According to a second aspect of the present invention there is provided a method of reducing lump size in a mixture containing lumps, the method comprising:
"providing a mixer as described above; and
"operating the driving mechanism to move said at least one lump conditioning blade in the working direction along the respective boundary wall with the working edge at said prescribed space from the boundary wall such that the mixture passes between the working edge of the lump conditioning blade and the boundary wall.
"When the mixer is used to mix a mixture comprising aggregate particles having a maximum diameter, preferably the prescribed space is greater than the maximum diameter of the aggregate particles.
"The mixer may be used to mix a mixture comprising a paste consisting of moistened tailing fines in a mining or oil sands operation, or alternatively to mix a mixture comprising concrete for example.
"When the boundary walls of the vessel include a general cylindrical portion, preferably the driving mechanism comprises at least one horizontal shaft supporting the mixing blades thereon for rotation about a horizontal mixing axis.
"When the boundary walls of the vessel include a pair of generally cylindrical portions, preferably the driving mechanism comprises a pair of horizontal shafts associated with the pair of cylindrical portions respectively upon which the mixing blades are supported for rotation relative to the boundary walls.
"Preferably the working edge of said at least one lump conditioning blade is discontinuous along a length thereof, for example the working edge of said at least one lump conditioning blade may be serrated.
"Preferably the mixing blades include at least one primary blade having a rigid blade body terminating at a working edge along an outer side of the rigid body which is supported by the driving mechanism so as to be movable in a working direction along a respective one of the boundary walls with the working edge thereof being in closer proximity to a respective one of the boundary walls than the working edge of said at least one lump conditioning blade. Preferably the working edge of said at least one primary blade is supported by the driving mechanism directly adjacent the boundary wall so as to be arranged to scrape the mixture from the boundary wall.
"Preferably the working edge of said at least one primary blade is disposed at an angle relative to the working direction thereof which is greater than an angle of the working edge relative to the working direction of said at least one lump conditioning blade.
"The leading face of the blade body of said at least one primary blade may be disposed at an angle relative to the working direction thereof which is greater than an angle of a main portion of a leading face of the blade body of said at least one lump conditioning blade.
"The lump conditioning blade may be supported by the driving mechanism along the same boundary wall in a leading relationship ahead of said at least one primary blade in the working direction.
"The working edge of said at least one lump conditioning blade is preferably oriented substantially parallel to the respective boundary wall and at an angle relative to the working direction between 60 and 90 degrees. More preferably, the working edge of said at least one lump conditioning blade may be oriented near perpendicular to the working direction.
"When the blade body of said at least one lump conditioning blade includes a leading face having an outer end portion locating the working edge thereon and a main portion which inwardly disposed relative to the outer end portion, preferably the working edge is supported in a trailing relationship in the working direction relative to the main portion of the leading face of the blade body.
"The main portion of the blade body of said at least one lump conditioning blade may be substantially perpendicular to the respective boundary wall.
"The main portion of the blade body of said at least one lump conditioning blade may be disposed at an angle of approximately 0 to 30 degrees to the working direction. More particularly, the main portion of the blade body may be near perpendicular to the working direction.
"In the illustrated embodiment the improvement includes the following features:
"i) A blade which is pulled away from the wall introducing a much bigger gap between the edge of the blade and the mixer wall, as compared to conventional mixing blades, thus defining a 'smearing gap' through which the lumps are squeezed to reduce the lump size.
"ii) The angle of the normal vector of the front surface to the velocity vector is changed as compared to conventional mixing blades, thus making it almost perpendicular (angle varies between 0 to 20 degrees) or perpendicular to turn it into a shearing blade instead of a mixing blade.
"iii) The surface at the outer edge of the blade curves or is bent away from the normal to the tangent in a trailing relationship relative to the direction of motion, thus acting to trap the material between the edge of the mixer and smear it onto the mixing wall. The bend in the surface could be a curvature or simply two flat surfaces at an angle to each other to generate the same effect with a smearing angle to the surface which is perpendicular to the tangential surface. This will force the material to get smeared onto the wall or kneaded between the wall and the shearing blade.
"iv) The outer working edge of the shearing blade is serrated, jagged, or otherwise interrupted and discontinuous to ensure that the agglomerated lumps are not smeared into a smooth surface, but rather the working edge introduces as much surface to the smeared mixture for the water to penetrate it as much as possible.
"v) These blades are put in together with the customary paddles on the same arcs such that the shearing blade smears any agglomerated chunks onto the wall and the mixing paddle travelling along the same co-incident circular path, scrapes it off the wall.
"This could be used for a single shaft or multiple shaft mixer where the blades of the mixers are mounted on some arm that sweeps over the surface of the mixer. More generally it could be used in any mixer where a paddle is mounted to a fixture that connects that paddle to a drive mechanism, that is where the drive mechanism forces the paddle to move over the surface such as in a pan mixer, or planetary mixer or ribbon mixer.
"Various embodiments of the invention will now be described in conjunction with the accompanying drawings in which:
BRIEF DESCRIPTION OF THE DRAWINGS
"FIG. 1 is a perspective view of a mixer including primary mixing blades and lump conditioning blades supported therein;
"FIG. 2 is a side elevational view of the mixer according to FIG. 1;
"FIG. 3 is a section view along the line 3-3 of FIG. 2;
"FIG. 4 is a section view along the line 4-4 of FIG. 2;
"FIG. 5 is a schematic representation of an alternative embodiment of the lump conditioning blades applied to a twin shaft mixer; and
"FIG. 6 is a schematic representation of yet another embodiment of the lump conditioning blades applied to a pan mixer.
"In the drawings like characters of reference indicate corresponding parts in the different figures."
URL and more information on this patent application, see: Wallgren, Mark. Lump Conditioner for a Mixer. Filed June 10, 2015 and posted January 28, 2016. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=5678&p=114&f=G&l=50&d=PG01&S1=20160121.PD.&OS=PD/20160121&RS=PD/20160121
Keywords for this news article include: Patents.
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