WO2018009954A1

WO2018009954A1 - Composite ceramic-polyurethane disc for ufg mills

Info

Publication number: WO2018009954A1
Application number: PCT/AU2016/050607
Authority: WO
Inventors: Rod STEAD; David Sibley
Original assignee: Flsmidth A/S
Priority date: 2016-07-12
Filing date: 2016-07-12
Publication date: 2018-01-18

Abstract

An enhanced grinding disc, an outer liner and portions thereof for a grinding disc and a method for making an enhanced grinding disc are disclosed. The enhanced grinding disc having an inner portion comprised of a polymeric material and an outer liner or outer liner portions comprised of a harder material such as ceramic. The outer liner or outer liner portions comprised of harder material such as ceramic may be incorporated into a grinding disc whereby the outer liner or outer liner portions increase the wear life of the grinding disc.

Description

COMPOSITE CERAMIC-POLYURE THANE DISC FOR UFG MILLS

FIELD OF INVENTION The present invention relates to grinding discs for grinding mills and more particularly to composite ceramic-polyurethane grinding discs and a method for making the same.

BACKGROUND OF THE INVENTION

Grinding mills historically use polyurethane-cast or polyurethane-coated grinding discs on a rotating shaft to agitate a grinding media load within a housing. As coarse slurry enters one end of the grinding mill and moves to an opposite end, it is sheared and pulverized between the grinding media and the rotating grinding discs. At the opposite end of the grinding mill, finer slurry exits the housing. Accordingly, particle sizes within the slurry are reduced.

One example of such a grinding mill is the FLSmidth® VXPmill™ vertical regrind mill (formally known as the Knelson-Deswik VGM-series mill). The mill has a series of grinding discs which rotate within a barrel-shaped vertical housing filled with grinding media to pulverize particles in coarse feed slurry. Although the mill was originally developed in South Africa for the pigment industry, it has utility in flue gas desulphurization (FGD), platinum processing, gold processing, carbon-in-leach (CIL) circuits, tank-leaching, as well as other mineral processes. The FLSmidth® VXPmill™ was adapted from a horizontal design in order to provide a smaller installed footprint than a horizontal mill. Its vertical nature also works with gravity to ensure that slurry product exiting the top end of the mill is of certain fineness. Its greater range of tip speed (e.g., between 3m/s and 15 m/s, and more preferably 10-12 m/s) bridges the gap between lower tip speed mills (e.g., less than 3m/s) such as Vertimill® vertical mill (which is produced and sold by Metso) and higher tip speed horizontal mills (e.g., greater 15m/s) such as IsaMill™ (which is designed and manufactured by ETZSCH and offered by Xtrata Technology). Other non-limiting examples of grinding mill devices and their incorporated grinding discs may be seen in various literature including the following patents and patent application publications: US2010025512, US6189280, US2001000588, IN00819KN200, US51 14083, JP2095449, JP2095450, JP2006595, JP7008824, US4754934, DE3768803, US4660776, JP2006596, KR890003745, CA1256414, IN164657, JP63199793, CN85107923, JP62265392, JP62230891, US4242002, US5366639, US2005040266, US2011303774, US5797550, US5984213, US2011309174, US2009072057, US2005051651, US2010127108, WO2010DE00234, US2009072060, EP1970124, US2003209618, EP 1206971, DE10064828, WO04101154, US5333804, DE10028946, DE10064829, DE4130835, DE19832769, AU700295, AU697677, DE4421478, WO9007378, DE19510807, DE4425906, EP0504836, DE4419919, US4620673, DE4240779, EP0448100, DE2745355, DE3927076, DE4116421, US4915307, US4805841, DE3902689, EP0306921, GB1331662, DE8517645, DE8336257, US4558825, EP0074633, US3993254, GB2074895, US4273295, DE2163699, IT1001528, US4089473, GB 1509591, GB 1416509, FR2305225, US3937406, DE1805387, GB 1179292, and US3432109, without limitation. Typically, grinding discs are polyurethane-cast or polyurethane-coated and must be replaced every three to eight months (depending on the tip speed of the grinding mill) because of excessive wear due to the impact of the grinding media against the grinding discs within the housing. Depending on the volume and mass of the grinding media used within a typical grinding mill, the first third of the total number of grinding discs which are located closest to the slurry feed inlet typically exhibit the greatest amount of wear and are required to be replaced more frequently. In many cases, this first third comprises approximately four grinding discs. It can take four to six hours or more to replace this first third, and a full change-out of all grinding discs in a grinding mill (albeit, seldom necessary) takes approximately sixteen hours or more. These time-consuming repair processes— if performed too often, may result in losses such as superfluous operational downtime, increased labor costs, and reduced throughput. If the repair process is performed too infrequently, other expensive losses such as shaft failure, inefficient grinding, and/or further degradation of intact grinding discs or mill components may be incurred.

It has been determined that a new type of grinding discs are needed in order to reduce costs and time associated with the frequent repair and/or replacement of premature disc placement and to increase the useful life of previously existing grinding discs. According to some embodiments, advantages which may be realized through the practice of my invention may include one or more of the following: providing a cost-friendly, economical way for plant owners to subsidize everyday plant operations, offsetting maintenance costs, justifying large start-up capital expenditures, and/or lowering overhead costs, without limitation.

SUMMARY OF THE INVENTION

An enhanced grinding disc is provided that may include an inner portion and an outer liner. The inner portion may be comprised of polyurethane and the outer liner may be comprised of ceramic. The ceramic may be comprised of silicon carbide. The outer liner may be between 4 mm and 20 mm thick.

An enhanced grinding disc is also provided that may include an inner portion, a first outer liner portion and a second outer liner portion. The inner portion may be comprised of a hub and at least one flange or spoke extending outwardly from the hub. The first outer liner portion and the second outer liner portion may be comprised of ceramic. The first outer liner portion may be fastened to the second outer liner portion by a fastener. The fastener may be a reinforced wire. The reinforced wire may be galvanized.

Embodiments of the enhanced grinding disc may be configured so that the first outer liner portion and the second liner portion are comprised of a radial portion and rails where the radial portion is substantially perpendicular to the rails and where the radial portion of the first outer liner abuts the radial portion of the second outer liner. The radial portions may be curved. The radial portion of the first outer liner portion may be comprised of one or more holes. The radial portion of the second liner portion may also be comprised of one or more holes. And the reinforced wire may extend laterally through the holes.

An outer liner for use on a grinding disc is also provided. The outer liner may be comprised of ceramic.

A fastener for securing an outer liner portion to an inner portion of a grinding disc is also provided. The fastener may extend through the outer liner portions and the inner portion.

Methods for making the enhanced grinding discs are also provided. One method may be comprised of including the outer liner into the inner portion by pouring sthe inner portion into the outer liner. Another method may also be comprised of including the first outer liner portion and the second outer liner portion into the inner portion by pouring the inner portion into the first outer liner portion and the second outer liner portion. Another method may be comprised of positioning the outer liner into or onto the inner portion. Another method may be comprised of positioning the first outer liner portion and the second outer liner portion into or onto the inner portion.

A method for grinding material is also provided. A method may be comprised of providing the enhanced grinding disc and rotating the enhanced grinding disc on a shaft within a housing of a grinding mill.

Other details, objects, and advantages of the invention will become apparent as the following description of certain present preferred embodiments thereof and certain present preferred methods of practicing the same proceeds.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of an enhanced grinding disc are shown in the accompanying drawings and certain exemplary methods for producing the same are also illustrated therein. It should be understood that like reference numbers used in the drawings may identify like components.

Figure 1 is a top cross-sectional view of a first exemplary embodiment of an enhanced grinding disc.

Figure 2 is a 30 degree isometric view of a first exemplary embodiment of an outer liner / outer liner portion of an enhanced grinding disc.

Figure 3 is an enlarged, fragmentary vertical cross-sectional view of a first exemplary embodiment of an enhanced grinding disc.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS Turning to FIG. 1 through FIG. 3, an exemplary embodiment of an enhanced grinding disc (101) and portions thereof are shown. The enhanced grinding disc (101) has an inner portion (102) and an outer liner (103). The inner portion (102) may be comprised of a polymeric material, for instance, polyurethane; and the outer liner (103) may be comprised of a ceramic (for example, silicon carbide, silicon infiltrated silicon carbide, sintered silica carbide, partially stabilized zirconia, syalon, silicon nitride, without limitation), metal, or other material having a higher hardness than said inner portion (102). For example, in some exemplary embodiments, the inner portion (102) may comprise polyurethane composite materials, hard rubber compounds, and/or other composite polymers, including filled polymers (e.g., glass, ceramic, or carbon-filled polymers).

The inner portion (102) of the enhanced grinding disc (101) may contain a hub (104) which is typically harder than the inner portion (102). The hub (104) may be comprised of steel. The hub (104) may fix the enhanced grinding disc (101) to a rotating shaft within a housing of a grinding mill. The hub (104) may contain a radially- extending flange or a number of spokes or "fingers" extending radially-outwardly from the hub (104) to provide surface area and strength to the enhanced grinding disc (101). For example, the radially-extending flange or the number of spokes or "fingers" extending radially-outwardly from the hub (104) may assist in for example, firmly fixing the hub (104) / inner portion (102) to a rotating shaft within a housing of a grinding mill. The hub (104) may be over- molded or otherwise casted within the inner portion (102) in a mold to form a final enhanced disc grinding disc (101). One or more passages (105) may be provided within the inner portion (102) of the enhanced grinding disc (101) in order to enable flow of coarse slurry entering the grinding mill and assist in grinding the slurry. The passages (105) may take the form of apertures or cutouts in a profile of the inner portion (102) of the enhanced grinding disc (101).

The outer liner (103) may be a single annular piece, or may be comprised of a plurality of outer liner portions (106, 107) of an annulus. The annulus comprised of a plurality of outer liner portions (106, 107) may be joined together. The outer liner (103) and/or outer liner portions (106, 107) may be positioned onto, into, adjacent to, or otherwise juxtaposed with the inner portion (102) by interference fit, ridging, adhesive, weld, over molding, or other mechanical fastening means, such as hardware (screws, nuts, bolts, washers, wires). For example, in some embodiments, the plurality of outer liner portions (106, 107) may extend radially towards the hub (104) and fit into or communicate with complementary receiving portions provided with the inner portion (102). The inner portion (102) may extend through the radial portions (109) (for example, through holes) of the outer liner portions (106, 107) in order to join the plurality of outer liner portions (106, 107) together. In some embodiments, one or more fasteners (108) may extend laterally through radial portions (109) of the outer liner portions (106, 107) in order to join the plurality of outer liner portions (106, 107) together. In some embodiments, the fastener (108) may comprise a reinforced wire. In an exemplary embodiment, the reinforced wire may be comprised of galvanized steel, stainless steel, or other corrosion resistant material. In an exemplary embodiment, the reinforced wire may between 4 mm and 5 mm in diameter. It is contemplated that the reinforced wire may be tightened or loosened with a wire tensioner in order to provide a greater gap between a first liner portion and ta second liner portion or to provide a tighter connection between such portions. Additionally, one or more fasteners (108) may further serve as anchoring means which may be surrounded by the polymeric material of the inner portion (102).

In an exemplary embodiment, one or more fasteners (108) may extend through one or more rails (110) of the outer liner portions (106, 107). The rails (110) may be profiled to accommodate holes, ridges, projections or protrusions to attach the inner portion (102) to the outer liner portions (106, 107).

In an exemplary embodiment, the center of the passages (105) may be longitudinally aligned (e.g., "coaxial" with), and/or circumferentially aligned (e.g., sharing the same "radial" or angular position), with joints formed between the plurality of liner portions (106, 107).

In an exemplary embodiment a radial portion (109) of a first outer liner portion

(106) may abut a radial portion (109) of a second outer liner portion (107). The radial portion (109) may be curved to minimize the gap between a first outer liner portion (106) and a second outer liner portion (107). The radial portions may contain holes or passages wherein a fastener (108) may extend laterally through the hole or passage to attach a first outer liner portion (106) to a second liner portion (107). In some embodiments, the one or more fasteners (108) may extend laterally through radial portions (109) of the outer liner portions (106, 107) and be longitudinally aligned (e.g., "coaxial" with) with the height of the rails (1 10). In an exemplary embodiment the radial portions (109) of the outer liner portions (106, 107) may be between 4 mm and 20 mm thick (i.e. - the cross- sectional thickness of radial portions 109) and more preferably about 6 mm thick (i.e. - the cross-sectional thickness of radial portions 109). In an exemplary embodiment the height of the rails (110) may be between 20 mm to 300 mm and the radial portions (109) may extend radially inwardly between 1 mm and 20 mm above the height of rails (110). In other embodiments, the radial portions (109) may be approximately equal to the height of the rails (110) (i.e. - within 1 mm).

In an exemplary embodiment, controlled gaps between the inner portion (102) and outer liner (103) or plurality of outer liner portions (106, 107) may be introduced to enable movement of the outer liner (103) or plurality of outer liner portions (106, 107) within the inner portion (102) to for example, reduce the overall stress on the enhanced grinding discs (101) and to prevent cracking and breakage of the enhanced grinding discs

(101) .

In an exemplary embodiment, a rim section or rim sections may be disposed on the outer liner (103) or outer liner portions (106, 107), wherein the rim section or rim sections extend inwardly into the inner portion (102). The rim section(s) may run substantially parallel to the rails (110) of the outer liner portions (106, 107) and may abut the radial portion (109) of the outer liner portions (106, 107). The rim section may be positioned onto, into, adjacent to, or otherwise juxtaposed with the inner portion (102) by interference fit, ridging, adhesive, weld, over molding, or other mechanical fastening means, such as hardware (screws, nuts, bolts, washers, wires). For example, in some embodiments, the rim section may extend radially towards the hub (104) and fit into or communicate with complementary receiving portions provided with the inner portion

(102) . In some embodiments, one or more fasteners (108) may extend through rim sections of the outer liner portions (106, 107) or outer liner (103) in order to join a plurality of outer liner portions (106, 107) together or to join the inner portion (102) to the outer liner (103) or outer liner portions (106, 107). One or more fasteners (108) may further serve as anchoring means which may be surrounded by the polymeric material of the inner portion (102). In some preferred embodiments, the material of the outer liner (103) or plurality of outer liner portions (106, 107) comprise a ceramic, for example, silicon carbide, silicon infiltrated silicon carbide, sintered silica carbide, partially stabilized zirconia, syalon, silicon nitride, without limitation.

In an exemplary embodiment, the outer liner (103) or plurality of outer liner portions (106, 107) may be between 4 mm and 20 mm thick and more preferably about 6 mm thick. In an exemplary embodiment, one or more wear detectors, as discussed in copending U.S. Provisional Patent Application No. 61/886,014, which is incorporated by reference herein, in its entirety, may be deposited within the outer liner (103) and/or in one more of the outer liner portions (106, 107). A method for making the enhanced grinding discs (101) according to an exemplary embodiment is also contemplated and may include the steps of including the outer liner (103) and/or outer liner portions (106, 107) into the inner portion (102) by pouring the inner portion into the outer liner (103) or outer liner portions (106, 107). For example, the inner portion (102) may be poured around hub (104) and around wires as shown in the figures to include the outer liner (103) and/or outer liner portions (106, 107) into the inner portion (102). In a second exemplary embodiment for a method for making the enhanced grinding discs, the method may include the steps of positioning the outer liner (103) and/or outer liner portions (106, 107) into the inner portion (102) by interference fit, adhesive, weld, over molding, or other mechanical fastening means.

Other variations of the invention may include the process of refurbishing a used enhanced grinding disc (101) by re-casting a new inner portion (102) with a used outer liner (103) and/or outer liner portion(s) (106, 107). For example, an outer liner (103) or outer liner portion (106, 107) may be subjected to water blasting, grit blasting, or burn-off to remove residual inner portion (102). The removal process may be followed by a recasting step, wherein an inner portion (102) is poured within the prepared outer liner (103) or outer liner portion (106, 107) to form a completed enhanced grinding disc (101). During or after the re-casting step, one or more wear detectors as discussed in co-pending U.S. Provisional Patent Application No. 61/886,014 may be deposited within the outer liner (103).

Further variations of the invention may include the process of refurbishing a used enhanced grinding disc (101) by water blasting, grit blasting, or burn-off to remove worn or broken residual outer liner (103) and/or worn or broken residual outer liner portion(s) (106, 107) from an otherwise intact inner portion (102). The removal process may be followed by a surface preparation step, wherein the inner portion (102) may be scuffed and/or heated, and a new outer liner (103) and/or new outer liner portions (106, 107) may be provided and affixed to prepared surfaces of the inner portion (102) to form a completed enhanced grinding disc (101). Adhesives, fasteners, plastic (heat) welds, or partial re-casting techniques may be used to join new liner components (103, 106, 107) to a resurfaced inner portion (102).

Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. For example, while it is envisaged that the invention may have the most practicality with production mills ranging from 150 KW to 3000 KW or more, various aspects of the invention may be incorporated in a lab-size grinding mills (e.g., 10 liter), 2 meter grinding mills suitable for metallurgical testing, pilot-size mills (e.g., a 50 liter modular/mobile unit), or full-size production grinding mills (e.g., 1000L, 2000L, 2500L, or larger), without limitation. Moreover, the invention may be practiced with grinding mills having vertical or horizontal configurations. Moreover, it is anticipated by the inventors that any number of variations and/or combinations of features or elements described herein may be practiced without departing from the scope of the invention.

Accordingly, it is to be understood that the drawings and descriptions herein are provided by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.

LIST OF REFERENCE IDENTIFIERS

101 - Enhanced grinding disc

102 - Inner portion

103 - Outer liner

104 - Hub

- One or more passages

107 - One or more outer liner portions

108 - One or more fasteners

109 - One or more radial portions

110 - One or more rails

Claims

1. An enhanced grinding disc comprised of an inner portion and an outer liner, wherein said inner portion is comprised of polyurethane and said outer liner is comprised of ceramic

2. The enhanced grinding disc of claim 1 wherein said ceramic is comprised of silicon carbide.

3. The enhanced grinding disc of claim 1 wherein said outer liner is between 4mm and 20 mm thick.

4. An enhanced grinding disc comprising:

an inner portion;

a first outer liner portion; and

a second outer liner portion;

wherein said inner portion is comprised of a hub and at least one flange or spoke extending outwardly from said hub; wherein said first outer liner portion and said second outer liner portion are comprised of ceramic; and wherein said first outer liner portion is fastened to said second outer liner portion by a fastener.

5. The enhanced grinding disc of claim 4 wherein said fastener is a reinforced wire.

6. The enhanced grinding disc of claim 5 wherein said reinforced wire is galvanized.

7. The enhanced grinding disc of claim 5 wherein said first outer liner portion and said second liner portion are comprised of a radial portion and rails wherein said radial portion is substantially perpendicular to said rails and wherein said radial portion of said first outer liner abuts said radial portion of said second outer liner.

8. The enhanced grinding disc of claim 7 wherein said radial portions are curved.

9. The enhanced grinding disc of claim 7 wherein said radial portion of said first outer liner portion is comprised of one or more holes; wherein said radial portion of said second liner portion is comprised of one or more holes; and wherein said reinforced wire extends laterally through said holes.

10. An outer liner for use on a grinding disc; wherein said outer liner is comprised of ceramic.

11. A fastener for securing an outer liner portion to an inner portion of a grinding disc wherein said fastener extends through said outer liner portion and said inner portion.

12. A method for making the enhanced grinding disc of claim 1 comprising including said outer liner into said inner portion by pouring said inner portion into said outer liner.

13. A method for making the enhanced grinding disc of claim 4 comprising including said first outer liner portion and said second outer liner portion into said inner portion by pouring said inner portion into said first outer liner portion and said second outer liner portion.

14. A method for making the enhanced grinding disc of claim 1 comprising positioning said outer liner into or onto said inner portion.

15. A method for making the enhanced grinding disc of claim 4 comprising positioning said first outer liner portion and said second outer liner portion into or onto said inner portion.

16. A method for grinding material comprising: providing the enhanced grinding disc of claim 1 and rotating said enhanced grinding disc on a shaft within a housing of a grinding mill.

17. A method for grinding material comprising: providing the enhanced grinding disc of claim 4 and rotating said enhanced grinding disc on a shaft within a housing of a grinding mill.