Abstract: A refiner for refining pulps, includes a shaft, a rotor disc attached firmly to the shaft and a shaft bearing, the rotor disc being disposed between two stator discs and forming a refining chamber between the rotor disc and the stator discs. The shaft is movable in an axial direction and the shaft bearing is connected hydraulically to the refining chamber, ensuring low wear on the rotor discs and stator discs and, in particular, on the refiner plates on these discs, also in continuous operation.

Abstract: A refiner segment for a refiner of lignocellulosic material includes a first bar, a second bar, a first dam, and a second dam. The first bar has a width and includes a first bar weakening section. The first bar weakening section includes two planar faces defining a wedge-shaped recess with a tip and a base. The two planar faces meet at the tip. The tip is separated from the base by a depth. The depth is greater than or equal to half of the width and less than or equal to the width. The first dam extends between the first bar and the second bar. The second dam extends between the first bar and the second bar. The first bar, the second bar, the first dam, and the second dam define a first essentially box-shaped region. The first bar weakening section is positioned within the first essentially box-shaped region.

Abstract: A refiner segment for refining lignocellulosic material, has a surface including a plurality of bars extending along a direction between an inner periphery of the refiner segment and an outer periphery of the refiner segment, and a plurality of dams, each of the plurality of dams extending between a corresponding pair of adjacent bars among the plurality of bars, wherein at least one of the plurality of dams is a three-dimensionally extending body including three sides, the three-dimensionally extending body extends between the corresponding pair of adjacent bars and includes a curved side, forming one of the three sides, facing the inner periphery of the refiner segment, the curved side having a concave curvature with regard to the inner periphery to thereby form a rounded section in an area defined by the at least one of the plurality of dams and the corresponding pair of adjacent bars.

Abstract: The grinder includes a container having a discharge opening for material to be ground; first and second grinding tools, the first tool rotatable relative to the second grinding tool about a rotation axis for crushing the material in a gap between the tools. The second tool has an inlet channel limited by a wall section around the axis for supplying material into the gap and is moveable relative to the first tool axially to the axis. A collar seal between container and second tool has a through-channel for discharging material into the inlet channel and is stationary relative to the container so that a first annular collar seal section limiting the through-channel contacts the container and overlaps the second tool wall section toward the axis. The collar seal includes a second annular section connected to the first annular section via an elastic spring and supported on a contact surface.

Abstract: A bean grinding device and a bean grinding coffee machine including the bean grinding device the bean grinding device includes a grinding assembly and an adjusting assembly; the grinding assembly includes a bean grinding chamber, an outer grinding wheel, and an inner grinding wheel; the outer grinding wheel and the inner grinding wheel are disposed inside the bean grinding chamber; the adjusting assembly includes at least two stages of adjusting mechanisms; the at least two stages of adjusting mechanisms includes a first adjusting mechanism and a second adjusting mechanism; the first adjusting mechanism and the bean grinding chamber are connected by means of a first track; the second adjusting mechanism and the outer grinding wheel are connected by means of a second track; and positions of the first adjusting mechanism and the second adjusting mechanism are relatively fixed in an axial direction.

Abstract: A refiner plate segment including a plurality of bars and grooves for refining lignocellulosic materials, where the grooves between adjacent bars includes a plurality of teeth having a wave-like profile with alternating high and low points. The wave-like profile of the teeth within the grooves increases turbulence in the refining process to tumble the fibers and push them toward the refining gap to reduce energy and improve the efficiency of the fiber reduction process.

Abstract: A refining system and process using a specially designed stator refiner plate. The specially designed stator refiner plate includes a major refining surface having a series of bars and grooves, the bars include a leading surface having an irregular surface. The irregular surface hosts a series of protrusions extending along the bar. The bar further comprises a trailing surface that is relatively smooth compared to the leading surface. The trailing surface lacks an irregular surface.

Abstract: A blade segment of a disc refiner for refining fibrous material has an inner circumference and an outer circumference as well as a first side edge and a second side edge which connect the inner circumference and the outer circumference. The side edges are curved, with one convex and the other concave. The segment has a refining surface with blade bars and grooves which define a pumping direction. The side edges of the blade segment curve in the vicinity of the inner circumference in the pumping direction, and in the vicinity of the outer circumference in a non-pumping direction.

Abstract: A refiner comprises at least one first refining surface (1?) and at least one second refining surface (2?), which refining surfaces (1?, 2?) are arranged opposite to one another and mobile in relation to one another. In the refiner (10, 11) either at least the first (1?) or the second (2?) refining surface comprises refining surface portions (15, 27) feeding material to be refined and/or refining surface portions (15, 27) discharging refined material as well as refining surface portions (16) grinding the material to be refined, on the upper surface of which there are blade bars (17) and between them blade grooves (18). Both in the first refining surface (1?) and in the second refining surface (2?) of the refiner (10, 11) the cross-sectional area (A) of at least some blade grooves (18) are arranged to change in the longitudinal direction of the blade grooves (18).

Abstract: A system for refining lignocellulosic material including a first stator plate segment refining zone and a first rotor place segment refining zone, each of which has grooves. The rotor plate groove width is larger than the stator plate groove width in the inner part of the refining zone, but substantially similar in the outer part of the refining zone.

Abstract: A method and system are presented for grinding and reclaiming of polymer material such as a rubber. The apparatus comprising a stator (4) and a rotor (2) in near face-to-face relationship with each other forming an operating zone for rubber grinding and reclaiming therebetween. The stator (4) has a substantially flat smooth face surface and the rotor (2) has a concave face surface with a depth gradually decreased from a center to a periphery thereof. The rotor further comprising at least one curved protrusion (30) with a radius of curvature gradually increased from the center to the periphery of the rotor.

Abstract: Described herein is nanocellulose produced by introducing a mixture of cellulose based fiber raw material and water through a refining gap, having a width smaller than 0.1 mm. In the refining gap, the fiber raw material is subjected to processing forces varying in the direction of introducing said mixture, by means of refining zones provided in the gap one after each other in the feeding direction, whereby the refining surfaces differ in surface patterning and/or surface roughness. The mixture of fiber raw material and water is guided past the refining surfaces in the feeding direction to different locations in the refining zone by by-pass channels provided in the stator. The width of the refining gap is maintained by the combined effect of the feeding pressure of the mixture of fiber raw material and water fed into the refining gap and the axial force of the rotor.

Abstract: This invention relates to the art of methods and apparatuses for grinding various materials into smaller particles; particularly, to those known in the art as pulverizing systems and devices. This invention provides methods and apparatuses for an improved disc mill assembly that utilizes a tapered flywheel and water jacket in conjunction with planar grinding disk cutting devices to create a tapered grinding channel.

Abstract: A method for refining aqueous suspended cellulose fibers including the step of guiding the fibers in an aqueous suspension between refiner fillings. The refiner fillings are provided with refining strips and interposed grooves and are located either on a rotor or a stator. The refiner fillings are caused to be rotatably moved relative to each other and pressed against each other, thereby transmitting mechanical a refining action to the cellulose fibers. The refiner fillings include barriers in at least part of the grooves, the barriers closing the grooves at least partially.

Abstract: A grinder for a coffee machine includes a first grinding disc disposed in a housing. A drive moves the first grinding disc about a rotational axis. A second grinding disc is disposed in the housing. There is a threaded part in which the second grinding disc is attached. The threaded part is screwable into the housing. A drive wheel is disposed coaxially with respect to the threaded part and rotates the threaded part with respect to the housing. A grinding gap between the two grinding discs is thereby able to be set. A setting wheel co-operates with the drive wheel, the setting wheel being attached to the housing. A supply opening is disposed in the housing for supply of coffee beans to be ground. A path guide opening guides away the coffee ground between the two grinding discs. A holder is adjustably attached to the housing and is fixable in any position.

Abstract: A device for comminuting bulk charge stock with a housing surrounding a rotational axis. The housing has a first front wall, a second front wall plane parallel at an axial distance and a shell wall connecting the first front wall and second front wall on the circumferential side, which together form a comminuting chamber. A comminuting system rotating about the rotational axis is arranged in the comminuting chamber, which comminuting system has first comminuting tools and second comminuting tools interacting therewith, which form a concentric comminuting zone for charge stock. In order to cool the comminuting zone effectively and economically, a cooling channel is provided, which surrounds the shell wall outside in the plane of the comminuting chamber, wherein the cooling channel has an entry opening for charging with cooling gas and an exit opening for the discharge of the cooling gas.

Abstract: Refiner plate segments and refiner plates having fully dammed or partially dammed grooves on a major surface that may control flow behavior of lignocellulosic materials passing between refining plates in a refiner. The dammed grooves form groove segments, and each groove segment has a length of no more than about 30 mm or a subrange thereof.

Abstract: A rubbing machine and its tool pan are disclosed. The tool pan (122) comprises a number of homocentric annular structures (125) which have a lot of rubbing zones (121). Provided between the contiguous rubbing zones is at least a ramp (127), which is extending along the normal of the tool pan, and the height of which is increased gradually towards the fringe of the tool pan. In the rubbing machine (100) the tool pan is used. The rubbing machine is applicable in paper making industry, and can effectively separate and fibrillate the fiber of herbage by mechanical force between a pair of tool pans, thereby needing not to use chemicals, and according with the modern conception of environmental protection.

Abstract: A refiner plate carrier for use in refining lignocellulosic material including a mounting mechanism for mounting to a refiner plate segment and not a rotor or stator disk. The combined plate carrier and refiner plate segment may be then attached to a refiner disk. The refiner plate carrier need not provide structural support to the segment during lignocellulosic refining.

Abstract: An automatic and continuous rubber extracting device comprises a first grinding stone having a central opening and second grinding stone rotatable mounted against the first grinding stone. The first grinding stone is a top stone and the second grinding stone is a bottom stone. A cone is disposed within the central opening of the first grinding stone. A motor apparatus is provided for rotating the bottom stone and the cone. A screw feed is in communication with the central opening of the first grinding stone. Plant material from the screw feed is fed along the cone and between the first grinding stone and second grinding stone. The cone may be provided with grooves and recesses along an lateral surface thereof.

Abstract: A refining plate for refining lignocellulosic material including: a radially outer peripheral edge and a substrate surface; a refining zone having a plurality of substantially radially disposed bars and grooves between the bars, wherein the bars protrude upward from the substrate surface and the grooves each have a groove width, and a steam channel traversing the bars and grooves of the refining zone, wherein the steam channel has a radially outer end radially inward of the outer peripheral edge of the plate and the steam channel has a width substantially greater than the groove width.

Abstract: A refining surface (1, 2) of a refiner for defibrating lignocellulose-containing material has a first blade bar (14?) and a second blade bar (14?) with a blade groove (15) therebetween. A third blade bar has a rising guide surface (21) for guiding the lignocellulose-containing material to an upper surface (14c) of the third blade bar. The third bar guide surface is arranged, in the direction of travel of the first and the second blade bar (14?), at least partly between the first and the second blade bar, between the first blade bar and an imaginary extension of the second blade bar, between an imaginary extension of the first blade bar and the second blade bar, or between the imaginary extensions of both the first and the second blade bar.

Abstract: A refiner or disperser blade is made of a steel alloy by casting. The alloy comprises, in weight percent: 0.6 to 4 wt-% carbon (C), 0.5 to 1.5 wt-% silicon (Si), 0.4 to 1.5 wt-% manganese (Mn), 12 to 28 wt-% chromium (Cr), 4 to 12 wt-% niobium (Nb), as well as iron (Fe).

Abstract: This invention relates to the art of methods and apparatuses for grinding various materials into smaller particles; particularly, to those known in the art as pulverizing systems and devices. This invention provides methods and apparatuses for an improved disc mill assembly that utilizes a tapered flywheel and water jacket in conjunction with planar grinding disk cutting devices to create a tapered grinding channel.

Abstract: A method for detecting an amount of grains within a container of a rotating grinding member is described, said method comprising the steps of: supplying (FORP1) a first driving torque to the rotating grinding member during a first interval (T1) of a grinding cycle (CM); —having (CTM1OO) a first value indicative of a period of rotation of said member at the first driving torque; supplying (RP2) the rotating grinding member, during a second interval (T2) of said cycle, with a second driving torque lower than the first driving torque; —measuring (CTM50) a second value indicative of the relative period of rotation of said member at the second driving torque, processing (CDTR, CNFR) the first and second values in order to generate information (ALR) indicative of the amount of grains being within the container.

Abstract: A device for grinding input material is provided with a supporting disk rotating around an axis of rotation within a housing. On the supporting disk, in its circumferential area, first grinding tools are arranged concentrically, axially opposite from which second grinding tools are arranged, forming a radial grinding gap. During operation of a device in accordance with the invention, the grinding tools execute a motion relative to one another. In accordance with an embodiment, the first grinding tools be fastened over an interchangeable ring to the supporting disk, wherein the interchangeable ring is fastened removably to the supporting disk concentric to the axis of rotation and on which the first grinding tools are arranged.

Abstract: A refiner plate carrier for use in refining lignocellulosic material including a mounting mechanism for mounting to a refiner plate segment and not a rotor or stator disk. The combined plate carrier and refiner plate segment may be then attached to a refiner disk. The refiner plate carrier need not provide structural support to the segment during lignocellulosic refining.

Abstract: A device for aligning the refining disc of a refining apparatus, in which refining apparatus lignocellulose-containing material is disintegrated and refined, which device is intended to be arranged in a support (701) for the axle package of the refining apparatus, the supporting (701) resting on a ground surface, which axle package comprises the rotary refining disc of the refining apparatus, a rotation axle to which the rotary refining disc is attached, and a bearing housing (702) in which the axle is journalled by means of bearings arranged in the bearing housing (704).

Abstract: Disclosed is a grinder which includes a grinder assembly retained in a housing. The grinder assembly receives material for grinding such as coffee beans. Grinding burrs are provided, one of which is rotated by a grinder drive motor of the grinder assembly. The other of the burrs is generally non-rotatable with regard to the general grinding operation. The two grinding burrs are provided with grinding surfaces against which beans are ground. The grinding surfaces are spaced a desired dimension away from each other to produce a desired grind of coffee. An apparatus, system and method is disclosed for adjusting at least the generally non-rotatable burr to maintain, calibrate or otherwise adjust the dimension or gap between the grinding surfaces of the burrs.

Abstract: Apparatus for aligning a refining disc is a refiner is disclosed, the apparatus including a first wedge slidable along a support for the axle package of the refining disc, a second wedge disposed between the first wedge and a bearing housing in which the rotatable axle of the axle package is journalled, the second wedge being slidable transversely to the slidable movement of the first wedge, a controller for controlling displacement of the first wedge including an actuator at one end of the support and a control axle extending from the actuator to the first wedge, the control axle being rotatable and rotatably secured to the first wedge whereby operation of the actuator causes rotation of the control axle, which in turn causes displacement of the first wedge which causes transverse displacement of the second wedge.

Abstract: A refiner blade comprising a blade surface for defibrating a lignocellulose-containing material, the blade surface comprising blade bars and blade grooves provided therebetween. At least one blade groove provided in the blade surface is formed by removing material from the blade surface by water cutting.

Abstract: A disc refiner is disclosed, including a shaft, a rotatable disc and a stationary disc, both with refiner elements. Between the stationary refiner elements and the stationary disc, axially deformable chambers are arranged, filled with an incompressible hydraulic medium, whereby the stationary refiner elements can move angularly in order to adjust themselves tangentially in parallel to the refiner elements of the rotatable disc, and the incompressibility of the hydraulic medium prevents stationary refiner elements from moving axially and impairing the axial stiffness.

Abstract: A refiner (1) comprising a stator (2) and a rotor (6) that comprise a planar portion and a conical portion after the planar portion, which in turn comprise refining surfaces (4, 8) provided with blade bars (15, 18, 24) and blade grooves (16, 19, 25) therebetween, and the planar portions (4?, 81) of the refining surfaces (4, 8) of the stator (2) and the rotor (6) comprising at least two refining zones (14, 17, 23) in the direction of the radius (R) of the planar portion.

Abstract: A grinder (30) has a toolessly attached ingredient hopper assembly (50) overlying a toolessly attached fixed grinding burr (134) defining the top of a grind chamber (158) within which is received a mating rotary grinding burr (150) that is slidably mounted to a rotary drive motor (154) for adjustment relative to the fixed grinding burr (134). Adjustment is achieved automatically by control of a stepper motor (168) that pushes on the end of an elongate member (151) passing through a hollow rotary drive axle (152) and carrying the rotary grinding burr (150) at an opposite end.

Abstract: Methods and apparatus controlling the alignment between refining surfaces of opposite refining discs are disclosed which are relatively rotatable and which are incorporated in a refiner for disintegrating and refining lignocellulose-containing material in a refining gap between the refining surfaces. The disclosed method includes positioning at least three sensors at least three measurement positions, measuring the vibrations at each of the measurement positions during refiner operation, and comparing each of the measured vibrations at each of the measurement positions with each other.

Abstract: A bushing to assist in positioning a bolt in the bolt apertures of refining plates and disk. The bushing is a cylindrical sleeve that slides over the bolt shaft, before the bolt is inserted into the aperture. The bushing may be short relative to the length of the bolt and the aperture. The bushing fits between the bolt and aperture in the refining plate and/or disk, as the bolt engages the threads of the plate and/or disk. The bolt is centered in the aperture and the centered bolt ensures that the plate segment is properly positioned on the disk as the bolt fastens the segment to the disk.

Abstract: A fibrous slurry refiner includes a casing, a rotor secured to a rotor shaft, and first and second pluralities of grinding surfaces. The rotor is disposed within the casing and is rotatable via the rotor shaft. The first plurality of grinding surfaces is secured to the rotor, and the second plurality of grinding surfaces is disposed facing the first plurality of grinding surfaces and fixed in the casing. An inlet plate for each of the plurality of grinding surfaces directs the fibrous slurry toward a set of facing first and second grinding surfaces and imparts a rotary flow to the fibrous slurry.

Abstract: A disc mill assembly for a pulverizing system includes: a flywheel, a water jacket, two disc blades, and two ring clamps. In alternate embodiments, the disc mill assembly also includes: an air inlet to provide input air from an external air supply and an improved blade height adjustment mechanism. A disc blade is also provided. The disc blade is a single member with a central aperture that is the only through hole in the blade. Users may cost-effectively adopt a disposal versus sharpening policy for replacement of the disc blade. A method for controlling a temperature of material in a disc mill assembly having first and second disc blades is provided. The method includes: directing an adjustable input air stream, directing material to be ground, monitoring the temperature of the material, and controlling the air stream directing and/or the material directing in response to the temperature monitoring.

Abstract: An improvement to a mechanical refining system relates to an apparatus including three or more actuators (100) coupled to a stator (42) of the refining system, and a controller for independently operating the actuators. An improved method of refining permits adjustment of the overall width of a refining gap between refining elements mounted by the stator and a rotor as well as the trim of the refining elements relative to each other.

Abstract: A disc refiner is disclosed, including a shaft, a rotatable disc and a stationary disc, both with refiner elements. Between the stationary refiner elements and the stationary disc, axially deformable chambers are arranged, filled with an incompressible hydraulic medium, whereby the stationary refiner elements can move angularly in order to adjust themselves tangentially in parallel to the refiner elements of the rotatable disc, and the incompressibility of the hydraulic medium prevents stationary refiner elements from moving axially and impairing the axial stiffness.

Abstract: A refiner plate assembly and method includes an annular arrangement of adapter subplates that mount to a refiner disk of a disk refiner using a conventional mounting technique, such as bolted in a standard pattern associated with the particular disk refiner. The adapter subplate arrangement remains mounted to the disk and provides a universal mounting surface for an annular arrangement of individual removable refiner segments. A steam and/or accept evacuation channel is provided in this assembly via filter passages at a radially intermediate location in one or more refiner segments which communicate with a recess or channel in one or more associated adapter subplates that direct the steam and/or accepts through outlet ports in the outer rim of the adapter subplate(s). Refining efficiency is provided in a universal refiner plate assembly by eliminating steam volume and already refined pulp from outer portions of the refining zone.

Abstract: A refiner (1) comprising a stator (2) and a rotor (6) that comprise a planar portion and a conical portion after the planar portion, which in turn comprise refining surfaces (4, 8) provided with blade bars (15, 18, 24) and blade grooves (16, 19, 25) therebetween, and the planar portions (4?, 81) of the refining surfaces (4, 8) of the stator (2) and the rotor (6) comprising at least two refining zones (14, 17, 23) in the direction of the radius (R) of the planar portion.

Abstract: A nondenatured ground matter with high quality is produced through efficient grinding while preventing overheating by, even in the case of grinding a material to be ground having a flexible thin film, such as cereal grain, efficiently crushing the thin film of low grindability to thereby obtain a ground matter of fine grains with uniform size by the use of simple apparatus and operation. A raw material is fed through raw material supply channel (55,56) into raw material introduction part (11) between fixed grinding disc (4) and moving grinding disc (5). The moving grinding disc (5) is hung down by means of drive shaft (21), and the gap between the same and the fixed grinding disc (4) is adjusted by means of gap adjusting means (7). While preventing any heat transfer from drive unit (8), power is transmitted to the drive shaft (21) so as to rotate the moving grinding disc (5).

Abstract: A powder based granules disintegrating and sizing device, includes: a drive shaft that is inserted horizontally in the casing main body; a plurality of circular plates that are fixedly supported at intervals by the drive shaft; and a stator, the plate surface of the circular plate and the inclined surface of the stator configuring a gap portion A where a powder based granules accumulates, and a narrowest gap portion between the circumferential edge of the circular plate and the stator configuring a disintegrating and sizing portion B. The stator stretches over the entire circumference of the circular plate, a raw material feeding port is provided on a side wall in the vicinity of the drive shaft of the casing main body, and a cutout portion through which a raw material passes is formed on the plate surface of the circular plate.

Abstract: A sensor, sensor disk, sensor measurement correction system, and method used in measuring a parameter in the refining zone. The sensor includes a spacer that spaces its sensing element from the disk. In one preferred embodiment, the spacer is made of an insulating material that insulates the sensing element from the thermal mass of the disk to prevent the thermal mass from affecting sensor measurement. The sensor includes a housing carried by the spacer that, in turn, carries the sensing element. Where the sensing element is a temperature sensing element, the housing is thermally conductive and the housing and spacer enclose the sensing element. Each sensor is disposed in the refining surface, preferably in its own separate bore in the disk and flush with or below axial refiner bar height. Signals from one or more sensors are processed by a processing device linked to a module containing calibration data that is applied to make sensor measurements more accurate.

Abstract: Method for producing a fibrous material for the manufacturing of preformed parts, in which a binder is added to the fibrous material and it is pressed into a preformed part upon application of heat, characterised in that a portion of particles of plastics and/or fibers from plastics is admixed to a particle or fiber mass of a first group of particles or fibers, the particle size of said particles from plastics and/or fibers from plastics approximately corresponding to the particle size of the particles or fibers of the first group, wherein the particles from plastics and/or fibers from plastics are obtained by crushing and/or defibrating agglomerates of pure or mixed plastics in a disc refiner, and that if necessary water is fed into the disc refiner during the crushing process.

Abstract: A disc housing intended for refiners with refining discs rotating in opposed directions relative to each other is disclosed for mechanically disintegrating and working fibrous material. The disc housing surrounds the refining discs in an air-tight manner, and is provided with an outlet for the worked fibrous material. The inside of the disc housing alond its periphery is formed with a channel, which, as seen in the circumferential direction, has a continously increasing radius, which increases all the way to the outlet, which is located tangentially as a direct continuation of the channel.

Abstract: A powder based granules disintegrating and sizing device having a drive shaft in a horizontal direction inside a casing, a rotor fixed to the drive shaft, a sizing stator having an inclined surface a gap section A where the powder based granules settles being formed by the plate surface of the rotor and the inclined surface of the sizing stator, and a disintegrating and sizing section B being formed by the narrowest gap section between the circumferential edge of the rotor and the sizing stator. The drive shaft is supported in a cantilever fashion, the rotor is fixed to an open side end portion thereof, the sizing stator is installed over the whole circumference of the rotor, a raw material supply port is opened in the vicinity of the central portion of the rotor, and a product output port is opened in the vicinity of position directly below the rotor.

Abstract: A vertical crusher having a housing defined chamber, enclosing a vertical axis rotor. The chamber has material(s) feed inlet(s) into the chamber. There is a drop-through outlet, which may be closable, from the chamber from which material(s) of at least a maximum size can drop in use. There are air inlet(s) into said chamber and air classifier outlet(s) from the chamber, for air or fine particles. Within the chamber also is a mass of discrete media, agitatable under the direct and/or indirect action of the rotor.

Abstract: A special shape of bars on refining discs or plate segments (54) of a rotating disc refiner (10) is disclosed including a plurality of bars (76) generally extending outwards toward the outer end of the disk across its surface, arranged in a single, two or more radial zones (64, 66, 68), the plurality of the bars within a zone being curved with the shape of a logarithmic spiral. Disc refiners including such refining discs are also disclosed.