Abstract: A ball mill liner assembly and installation method thereof; the ball mill liner assembly comprises wear-resistant liners (1), installation modules (3) and self-fixing liners (2); the self-fixing liners are made of ductile materials such as carbon steel or low-carbon alloy steel; the wear-resistant liners are integrally made of ceramic material; self-fixing liners are installed between a plurality of wear-resistant liners, and installation modules made of low-carbon alloy steel are used adjacent to the self-fixing liners.

Abstract: This disclosure relates to wear-resistant rubber compositions, such as those, for example, comprising at least one hydroxy-terminated polybutadiene, at least one natural rubber, at least one polymerization accelerant; at least one sulfur; and at least one polybutadiene, wherein the wear-resistant rubber composition may have an effective cross-linking density of at least about 30×10?5 moles/cm3.

Abstract: A mill includes a housing with a first end portion, a second end portion, and a lateral area disposed therebetween. The housing includes a raw material inlet, an air inlet, a recirculated material inlet, and a material outlet. An impeller is supported by the housing and includes a shaft disposed along the longitudinal axis of the housing, with a plurality of curved blades. A method for milling includes receiving a material of a first size range, introducing the material to an apparatus via a first inlet and introducing air into the apparatus via a second inlet. The method also includes agitating the material via an impeller, where the agitation reduces at least some of the material to a second size range by the time the material reaches an outlet of the apparatus. The processed material is delivered to subsequent processing operations.

Abstract: An assembly comprises a vessel comprising a shell exhibiting at least one opening extending therethrough, a structure covering an internal surface of the shell, and at least one plug device contacting the shell and the structure. The at least one plug device comprises a rigid body comprising a male connection structure longitudinally extending into the least one opening, and a base structure extending outwardly beyond a lateral periphery of the male connection structure and positioned longitudinally between the structure and the shell. A plug device for a milling application, and a method of plugging a component of an assembly are also described.

Abstract: Disclosed herein is a rock mill lifter having in one example: a radially outward surface with a radially inward recess having a radially inward surface which is substantially parallel to; a calculated radially outward lift surface of the lifter at a minimum allowed lifter height. The rock mill lifter in one example may further include: a circumferential following surface having; a radially inward recess configured to wear to be; substantially parallel to the radially inward surface of the radially inward recess.

Abstract: A forged, mill liner bolt (100) has a head (114), a shank (112), tapered load-bearing surfaces (116) and lateral projections (120) defining an undercut surface (117), and a sealing member (118) abutting the undercut surface. A plurality of plastically deformable projections (122) extend from the tapered load-bearing surfaces (116) for spreading a load applied to the bolt. Sealing member (118) provides a partially-elastic joint to maintain clamp loading. Sealing member (118) provides an interior seal within a bore in a mill liner to prevent leaking of and racing by mill slurry liquids.

Abstract: A crusher wear resistant liner for positioning at a crusher bottom shell includes a plurality of modular wear resistant plates mountable at an inside surface of the bottom shell and positioned side-by-side to surround and protect the bottom shell interior. To prevent independent dislodgement of each plate and liner, respective inter-engaging formations are provided at each plate to contact at least one adjacent plate of the assembly to arrest any unintentional downward movement in the event that the primary fixings become ineffective.

Abstract: An interlocking liner segment for a tumbling unit is disclosed which comprises a body having an inner surface having a first end and a second end, an outer surface, a first side edge, a second side edge opposite the first side edge, a front edge, and a back edge, a first lifter portion at the first end having a first aperture; a second lifter portion at the second end having a second aperture; and a rifling portion on the inner surface intermediate the first lifter portion and the second lifter portion.

Abstract: A crushing mill with an internal ring inside an external ring is disclosed. In some embodiments, the inner ring has protrusions that fit within pockets in the outer ring such that as the rings rotate rock or other materials may be crushed between the protrusions and pockets of the inner and outer rings, respectively. In some embodiments, the inner and outer rings each have surface protrusions such that rock or other materials may be crushed between the inner and outer rings as they rotate. In some embodiments, the inner ring has a circumferential ridge that fits within a circumferential groove of the outer ring such that rock or other materials may be crushed between the rings. In some embodiments the rings operate at differential speeds with respect to each other to induce shear forces on the material to be crushed.

Abstract: Some of the embodiments described herein relate to liner elements such as lifter bars that can be used in grinding mills. In one example, a lifter bar has a top elastomeric layer and a bottom elastomeric layer, the composition of the top elastomeric layer being different from that of the bottom elastomeric layer. In another example, a lifter bar is constructed from carbon black-reinforced natural rubber and has a leading face and a protrusion at a top region of the leading face. In a further example, a lifter bar is fabricated from carbon black-reinforced natural rubber and has a leading face geometry such that face angle ? remains 25° or less over an operational period measured form the time the lifter bar is new, until the height of the lifter bar is reduced by a certain amount, e.g., by 80%. Also disclosed are methods for manufacturing an elastomeric liner element and for grinding an ore.

Abstract: A wear-resistant lining for ball mills comprises a base (3) made of a material that is elastically deformable at the work surface (4) subjected to wear from which it is obtained, a plurality of cavities or hollows (5) suitable for accommodating bodies of hard material inside them. The presence of said bodies of hard material has the function of imparting particular wear resistance to the work surface (4) in that they are suitable for coming into contact with the grinding bodies or balls (6) made of hard material which are used in the mill as the grinding charge. The cavities or hollows (5) of at least part of said plurality are dimensioned and proportioned so that each of them is suitable for accommodating at least one of the grinding bodies or balls (6) inside it.

Abstract: A lifter bar assembly for a crushing mill is disclosed including: a plurality of lifter bar segments; the segments being arranged to be installed adjacent to one another to form a lifter bar; wherein each of the segments are of a weight which can be safely handled by a team of two people.

Abstract: A lifter bar assembly for a crushing mill is disclosed including: a plurality of lifter bar segments; the segments being arranged to be installed adjacent to one another to form a lifter bar; wherein each of the segments are of a weight which can be safely handled by a team of two people.

Abstract: Some of the embodiments described herein relate to liner elements such as lifter bars that can be used in grinding mills. In one example, a lifter bar has a top elastomeric layer and a bottom elastomeric layer, the composition of the top elastomeric layer being different from that of the bottom elastomeric layer. In another example, a lifter bar is constructed from carbon black-reinforced natural rubber and has a leading face and a protrusion at a top region of the leading face. In a further example, a lifter bar is fabricated from carbon black-reinforced natural rubber and has a leading face geometry such that face angle ? remains 25° or less over an operational period measured form the time the lifter bar is new, until the height of the lifter bar is reduced by a certain amount, e.g., by 80%. Also disclosed are methods for manufacturing an elastomeric liner element and for grinding an ore.

Abstract: A lifter bar assembly for a crushing mill is disclosed including: a plurality of lifter bar segments; the segments being arranged to be installed adjacent to one another to form a lifter bar; wherein each of the segments are of a weight which can be safely handled by a team of two people.

Abstract: A mill liner assembly for mounting on an inner diameter of a shell of a grinding mill. The mill liner assembly includes one or more shell plates for engagement with the shell, each of the shell plates having a cooperating portion thereof, and one or more lifter bars, each of the lifter bars having a mounting portion thereof, the mounting portion being receivable on the cooperating portion. The mill liner assembly also includes one or more layers having one or more substantially non-resilient materials and a substantially non-sticking surface. The layer is at least partially positioned on at least a first selected one of the cooperating portion and the mounting portion, to position the non-sticking surface thereof for engagement with a second selected one of the cooperating portion and the mounting portion, to impede adhesion of the shell plate and the lifter bar to each other.

Abstract: A wear-resistant lining for ball mills comprises a base (3) made of a material that is elastically deformable at the work surface (4) subjected to wear from which it is obtained, a plurality of cavities or hollows (5) suitable for accommodating bodies of hard material inside them. The presence of said bodies of hard material has the function of imparting particular wear resistance to the work surface (4) in that they are suitable for coming into contact with the grinding bodies or balls (6) made of hard material which are used in the mill as the grinding charge. The cavities or hollows (5) of at least part of said plurality are dimensioned and proportioned so that each of them is suitable for accommodating at least one of the grinding bodies or balls (6) inside it.

Abstract: A lifter bar is includes at least one attachment formation for use in lifting the lifter bar; wherein the at least one attachment formation is embedded in the lifter bar. A method of producing the lifter bar and tools for use in handling the lifter bar are also described.

Abstract: A lined drum includes a drum having a wall with an inner surface. The lined drum also includes a plurality of liner segments, each liner segment having inner and outer opposing surfaces, opposing side edges, and opposing end edges, the outer surface of the liner segment facing the inner drum surface and the side edges of adjacent liner segments being spaced from each other to define a space therebetween, and at least one retainer having opposing side edges overlapping the side edges of the adjacent liner segments, the at least one retainer attached to the wall of the drum in the space between the side edges of the adjacent liner segments. The lined drum may also include a plurality of bar segments, each bar segment attached to the wall of the drum and at least one retainer.

Abstract: A mill liner element is structured with an elongated elastomer member having a non-elastomeric backing plate and a plurality of non-elastomeric inserts formed into the elastomer member to provide a liner element that provides a lifter bar element and a wear element that is less prone to cracking compared to conventional all-metal mill lining elements, and which provides ease of handling and replacement when worn. A multiplicity of mill liner elements are positionable in a grinding mill shell, and are suitable for use in a variety of types of grinding mill structures, including ball mills and AG and SAG mills.

Abstract: The invention concerns an arrangement for the joining and attachment of a wear lining element (1) onto a surface that is subject to wear, a supporting surface (5) of a supporting construction (2), comprising attachment means (9) that when anchored in the wear lining element are each one intended to be inserted into attachment holes (10) arranged in the supporting construction whereby the wear lining element is held fastened against the supporting surface by means of supplementary fastening means (16) that are associated with the attachment means positioned to interact with the tensioning surface (11) located on the opposite side of the supporting surface.

Abstract: A wear liner for use with a brush cutter, the cutter having a cylindrical, rotatable, cutting drum carrying cutting teeth and a cover at least partially covering the drum to limit dispersal of cut material. The liner comprises a sheet of material which can be shaped to fit against the inner surface of the cover. The liner has holes on its sides for use in detachably connecting the liner with fastening means to the cover against the cover's inner surface. The liner has protective means mounted on its inner surface adjacent each hole to protect part of the fastening means located adjacent the inner surface of the liner, when the liner is mounted to the cover and the fastening means extend through the opening, from wear by material thrown by the cutter during its operation. The invention is also directed toward a brush cutter incorporating the liner.

Abstract: A lifter bar assembly for a crushing mill is disclosed including: a plurality of lifter bar segments; the segments being arranged to be installed adjacent to one another to form a lifter bar; wherein each of the segments are of a weight which can be safely handled by a team of two people.

Abstract: A liner assembly for use in a grinding mill, the liner assembly including a liner body including a mounting member, and an elastomeric cushioning member operatively connected to the mounting member. The cushioning member includes a plurality of support cavities therein, and a plurality of wear elements mounted within the support cavities.

Abstract: A relocatable oil sand slurry preparation system is provided for preparing an aqueous oil sand slurry amenable to pipeline conveyance while producing minimum overall rejects, comprising (a) a relocatable rotary digester for slurrying oil sand and water and digesting oil sand lumps to form a pumpable slurry, the rotary digester having a feed end for receiving oil sand and water, a slurrying chamber comprising a plurality of lifters for slurrying the oil sand and water, and a trommel screen end for screening out oversize rejects from the oil sand slurry which falls through the trommel screen; and (b) a relocatable rejects recirculation unit operably associated with the rotary digester for receiving oversize rejects and delivering the rejects back to the rotary digester for further digestion. In a preferred body, relocatable oil sand slurry preparation system further comprises a rejects crusher for crushing oversize rejects prior to delivering rejects back to the rotary digester.

Abstract: A lifting element for a drum of a grinding mill to be used for grinding of ores and minerals. The lifting element is attachable to a frame of the drum and extending in the longitudinal direction of the drum. The lifting element includes a flexible body and a wear protection element located in the leading edge of the body with respect to the direction of rotation of the drum. The wear protection element includes at least two different parts manufactured of different materials having toughness and hardness different from each other.

Abstract: A lifting element for a drum of a grinding mill to be used for grinding of ores and minerals, said lifting element being attached to a frame of the drum and extending in the longitudinal direction of the drum, and said lifting element comprising a flexible body and a wear protection located in the leading edge of the body with respect to the direction of rotation of the drum. The wear protection consists of at least two different parts, said parts being manufactured of different materials having toughness and hardness different from each other.

Abstract: A pulp lifter for installation in a grinding mill has a leading edge and a trailing edge with respect to rotation of the mill and comprises a first wall bounding an interior space and a second wall dividing the interior space into first and second sections. The first wall includes a leading edge wall formed with an inlet opening providing access to the second section and an inner edge wall formed with an outlet opening for discharge of slurry from the second section. The second wall includes a guide that extends substantially from an outer end of the leading edge wall to a trailing end of the inner edge wall, and the first section of the interior space is open at the trailing edge of the pulp lifter.

Abstract: A method for manufacturing a multimaterial component or construction, whereby a multimaterial component or construction is manufactured comprising wear resistant material and elastomer material. The invention also includes use of a multimaterial component or construction manufactured with said method.

Abstract: A cushioning element suitable for use in a liner assembly for a grinding mill, the liner assembly including a mounting element having a recess therein, the cushioning element being located within the recess, and a wear element operatively connected to the cushioning element, the cushioning element including a cushion body of elastomeric material including a side section and opposed end sections, a plurality of cavities within the cushion body and extending from at least one of the end sections towards the other end section.

Abstract: A grinding machine having plurality of lift elements positioned within the rotating drum. The lift elements are provided with a central ridge contact surface portion with slanted side surfaces extending from the ridge contact portion in a downward and outward configuration. Adjacent pairs of side surfaces form valleys with the downwardly converging side surfaces. In the grinding process, this enhances the effectiveness of the grinding mill.

Abstract: A rotary kiln for pyroprocessing particulate material includes a cylindrical kiln shell supported for rotation about a longitudinal central axis. The kiln has a discharge opening that includes a lump breaker system. The lump breaker system includes multiple insert retainers mounted to the shell and positioned along the inner circumference of the rotary kiln. Each insert retainer includes multiple mounting slots for receiving breaker inserts that can be easily removed and replaced when worn. Each of the breaker inserts can be individually removed from its respective retainer without removing either the retainer or the layer of refractory in the rotary kiln.

Abstract: An apparatus for compacting and storing cigarette butts includes a housing having a central bore with a releasable bottom closure, a closable upper extremity, and a plunger which can be forced downwardly to compact butts within the bore. The plunger also serves as releasable closure for the upper extremity of the bore.

Abstract: The invention concerns a liner consisting of juxtaposed individual rings of lining plates forming the cover of the cylindrical housing of a rotary mill. The liner consists of a number of lining plates located at selected sites and configured in the form of deflectors (20, 30) comprising a fin (26, 36) arranged on edge on a base plate (22, 32) fixed to the housing and forming an angle less than 25° relative to a diametral plane of the mill.

Abstract: A pilot plant scale SAG mill suitable for use in design of a commercial scale SAG mill. The ball mill has a cylindrical outer chamber having flanges at opposed ends. The cylindrical outer chamber contains a removable grinding chamber in the form of a sleeve. The removable grinding chamber has a diameter of 2-5 feet and a ratio of diameter:length in the range of 3:1 to 1:1. The removable grinding chamber contains a plurality of steel balls. The removable grinding chamber extends partly down the length of the cylindrical chamber and has longitudinal lifters attached to the internal surface of the sleeve. The lifters are capable of lifting steel balls located in the removable grinding chamber during rotation of the cylindrical outer chamber. The removable grinding chamber has means at one end for receiving particulate ore from a feed hopper and a removable diaphragm at the opposed end, the removable diaphragm having outlet ports therein for discharge of ground particulate ore into the cylindrical outer chamber.

Abstract: A grizzly bar device for a rotating kiln having an annular array of bars having at least two adjacent bars, wherein the thickness the bars is reduced in lateral and radial directions, and gap between the adjacent bars increases in width as the bars extend laterally from front to back of the bar and extend radially inward of the kiln. Another taper on a front face of the bars provides a cutting corner on each bar.

Abstract: Process and apparatus for slushing contaminated recovered paper in a slushing device including a rotatable drum having first and second face on axial ends and at least one displacement body having an outside wall curved at least in sections located inside drum and held from outside of the drum to form processing channel between at least curved section of outside wall of displacement body and at least a part of an inside wall of drum to mechanically process the recovered paper. Process includes feeding recovered paper with impurities into drum on first face, moving recovered paper and impurities within drum from first to second face, and transporting recovered paper and impurities out of drum at second face together via a rotating coil. The instant abstract is neither intended to define the invention disclosed in this specification nor intended to limit the scope of the invention in any way.

Abstract: A pilot plant scale SAG mill suitable for use in design of a commercial scale SAG mill. The ball mill has a cylindrical outer chamber having flanges at opposed ends. The cylindrical outer chamber contains a removable grinding chamber in the form of a sleeve. The removable grinding chamber has a diameter of 2-5 feet and a ratio of diameter:length in the range of 3:1 to 1:1. The removable grinding chamber contains a plurality of steel balls. The removable grinding chamber extends partly down the length of the cylindrical chamber and has longitudinal lifters attached to the internal surface of the sleeve. The lifters are capable of lifting steel balls located in the removable grinding chamber during rotation of the cylindrical outer chamber. The removable grinding chamber has means at one end for receiving particulate ore from a feed hopper and a removable diaphragm at the opposed end, the removable diaphragm having outlet ports therein for discharge of ground particulate ore into the cylindrical outer chamber.

Abstract: A grinding mill liner, characterized by a sinusoidal shape to promote certain types of grinding. In one embodiment, the mill liner shape defines sinusoidal lifters with low face angles whereby impact grinding can be minimized, and attrition grinding can be maximized. In a further embodiment, the inner liner surface shape defines sinusoidal lifters with high face angles whereby impact grinding can be increased, and attrition grinding can be decreased.

Abstract: There is described a milling machine which has a shell main unit and enables an improvement in the efficiency of crushing ore by uniform distribution of grinding members within the shell main unit and which enables an improvement in the quality of crushed stones by prevention of excessive crushing of ore. The shell main unit includes a first cylindrical section provided on an ore supply side and a second cylindrical section provided on a crushed stone outlet side. The first cylindrical section is tapered such that the inner diameter thereof becomes greater toward the ore supply side, and the second cylindrical section is tapered such that the inner diameter thereof becomes greater toward the ore supply side. The first cylindrical section is tapered with a very small cone angle, and the second cylindrical section is tapered with a cone angle greater than that of the first cylindrical section. The axial center of the shell main unit resides in the first cylindrical section.

Abstract: The mill comprises a cylindrical shell (16) lined with an interior lining and intended to contain material to be ground and a charge of grinding implements, in which the lining, which is made up of rings of juxtaposed individual lining plates, has interior longitudinal lifting profiles to encourage the lifting of the charge and of the material to be ground as the mill rotates. In order to adapt the lifting profile to the parameters and conditions in which the mill operates, each plate has, on the rear face, when viewed in the direction in which the mill rotates, a step (10b, 12b, 14b) of a radial height that is taller than the front face, and each ring of plates comprises several different types of plate (10, 12, 14) which differ at least in terms of the radial height of their step (10b, 12b, 14b) and which follow on from one another, in the circumferential direction, in a determined order.

Abstract: A wall exposed to wear has a wear lining composed of a number of juxtaposed wear lining elements of an elastomeric material or of a mix of elastomeric and other wear-resistant materials. The wear lining elements are secured to a supporting surface with fastening means. Two opposite narrow faces of the wear lining elements have V-shaped recesses, which open toward the narrow faces. The fastening means have washers with V-shaped projections, the V-legs of which are inserted into and abut against the bottom wall of the recesses or into shoulders formed in the recesses, after fastening the elements.

Abstract: A system and method for recycling a waste glass cullet includes a first screening station for separating large glass shards of approximately one inch in diameter from smaller glass shards in the cullet, a crusher to reduce the large glass shards to smaller glass shards smaller than approximately one inch in diameter, a second screening station to separate remaining large contaminants having a diameter of approximately one inch or greater from the cullet, a series of vacuum inlets disposed along a conveyor to remove light contaminants, a presoaking apparatus comprising a holding tank partly filled with a presoaking solution, a rotary washing apparatus comprising a drum with vanes disposed along an inner wall of the drum to toss the cullet in the washing solution, the vanes being oriented so that the cullet is tossed progressively forwardly toward a discharge outlet of the drum, to remove buoyant contaminants from the cullet, a dewatering apparatus to remove excess water from the cullet, and a dryer for reducin

Abstract: A segmented liner assembly and liner segment fastening system is disclosed for the rotatable shell of an ore grinding machine, the shell having a plurality of mounting bores formed therethrough. The liner assembly consists of a plurality of liner segments each of which has one mounting bore that extends into the body of the segment from its mounting surface and a mounting recess having a transverse size greater than that of the mounting bore which extends from the mounting bore to the grinding surface. A threaded member extends through a mounting bore of the shell and an aligned mounting bore of the segment into the recess of the segment and externally of the shell. The threaded member is screwed into a nut that is seated at the base of the mounting recess. In a first embodiment, the threaded member has an integrally formed wrenching head enabling the threaded member to be rotated and screwed into the nut, thus drawing the liner segment tightly against the inner surface of the shell.

Abstract: A lining element (10) for mounting onto an inner surface of a drum mantle (56) in a grinding mill, comprising an elongated lifter member (12) of a wear resistant material adapted to be axially oriented with respect to the drum mantle and to project radially into the drum, and an elongated single-piece support member (26) of an elastomeric material adapted to resiliently support the elongated lifter member over a full length thereof above the inner surface of the drum mantle. The support member is extended peripherally in a rearward direction with respect to an operational forward direction of rotation of the drum into contact with a subsequent lining element (10) to be mounted onto the inner surface, and to cover entirely therebetween the inner surface of the drum mantle.

Abstract: An improved lifter and a method of repairing a damaged lifter employed in a rotary drum debarker of the type which removes the bark of logs by introducing logs into a rotating drum wherein the the logs tumble and flail against one another so that the bark is removed by the tumbling and rubbing action of one log against another. A plurality of lifters are arranged around the interior surface of the drum so that the point or vertex of the lifter is facing toward the axis of rotation of the drum. The lifters are provided with cleats on the vertex of the lifter in the direction of rotation of the drum to protect the lifter from excessive wear. In addition the cleat lifts the logs higher in the drum which improves the tumbling action. Damaged lifters may be repaired by the addition of the cleat to the vertex of the lifter.

Abstract: Process and device for decomposing fibrous material in an installation including a drum having an inner wall, a first end, and a second end, a displacer having an outer wall positioned inside the drum, and a processing channel formed between at least a portion of the outer wall and at least a portion of the inner wall. The process includes pouring fibrous material to be decomposed into the drum, relatively moving the outer wall relative to the inner wall in a peripheral direction of the drum, and mechanically processing the fibrous material in the processing channel.

Abstract: A novel laminar assembly for use with comminution equipment, such as a liner for protecting the shell of an ore crushing mill or as a wear tip on a blow bar for use in a rock impact crusher. The laminar segment includes a plurality of laminae which are attached to each other with a pair of rods extending through a pair of axial holes positioned in the base of the laminae, thereby forming a segment of virtually any desired length. Conventional mounting bolts may extend through radial holes in the laminae between the axial holes to attach the liner segment to the comminution equipment. The utilization of small laminae enable the laminae to be formed from hardened materials such as heat treated steel or cut from a plate and then heat treated such that the microstructure throughout the laminae may be strictly controlled, thereby providing a laminae with consistent hardness and toughness throughout the laminae.

Abstract: A rotatable debarking drum for removing the bark from logs comprises a cylindrical member and a plurality of axially extending rows of debarking tools circumferentially distributed on an inner circumference of the cylindrical member. Each row of debarking tools includes a plurality of axially spaced-apart arcuate ribs extending transversally relative to the cylindrical member axis. The discontinuous axially extending rows of debarking tools arrangement contributes to increase the efficiency of the overall debarking operation.

Abstract: An asphalt roofing material recycling system and method is used to recycle asphalt materials, such as asphalt shingles and tar paper that include granules, fibers or other particles. The asphalt material is simultaneously heated and milled in a heated milling apparatus, such as a heated ball mill, to reduce the asphalt material granules to a fine mesh in suspension in liquid asphalt. Excess moisture is removed from the asphalt material being recycled, either during heating and milling by continuously venting the heated milling apparatus, or before the heating and milling in a drying apparatus. The heated milling apparatus preferably includes a rotatable milling vessel rotated at an acute angle with respect to the horizontal plane and having an opening that provides continuous venting. The rotatable milling vessel includes a plurality of mixing members, such as rods or paddles, extending from an interior surface and preferably arranged in a helical pattern to force the asphalt material away from the opening.