Patent Publication Number: US-11396022-B2

Title: Mono roller grinding mill

Description:
RELATED APPLICATIONS 
     This application claims priority benefit of U.S. Ser. No. 62/723,841 filed Aug. 28, 2018, the contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE DISCLOSURE 
     Field of the Disclosure 
     This disclosure relates to rock (material) grinding mills and more particularly to a roller grinding mill having a single roller therein, where the roller and outer ring (shell) surface cooperate to comminute material, and where the roller “floats” on the material being comminuted within the shell. The roller in one example is not connected to a drive system. The roller in one example does not have a pressure system connected exterior of the roller to increase pressure against the shell. 
     Background Art 
     For many industrial purposes it is necessary to reduce the size of rather large rocks or other material to a smaller particle size (commonly called “comminution”). For example, the larger rocks may be blasted out of an area such as a hillside, pit or mine, and these larger rocks are then directed into a large rock crusher, which is typically the first stage of comminution after blasting. The blasted rock sizes can exceed 1000 mm (&gt;40 inches) in size. The resulting output of the crusher is typically smaller rock that is less than 200 mm (8 inches) in a longest dimension which is then fed to a grinding mill or similar device. Such a grinding mill typically comminutes the crushed rock down to 50 mm (&gt;2 inches) sized rocks or less. 
     One common grinding mill comprises a large cylindrical grinding section, rotating along its horizontal axis, which in one example has a diameter of ten to fifty feet. One such mill is described in U.S. Pat. No. 7,497,395 incorporated herein by reference. The material (rocks or other material), along with optionally water or air, are directed into one end of the continuously rotating grinding section, which in one example comprises various types of lifting ribs (lifters) positioned axially on the inside surface of the grinding section to carry the material upwardly, on its surface, in a curved upwardly directed path within the grinding chamber so that this partially ground material tumble back onto other material in the lower part of the chamber. Thus, this material impacts other material components, and the inner surface of the grinding mill, optional bars, optional balls, etc., and the material is broken up into smaller fragments. In some examples large iron balls (e.g., two to six inches in diameter) are placed in the grinding chamber to obtain improved results. 
     It takes a tremendous amount of power to operate many examples of these grinding mills, and also there are other substantial costs involved in maintenance, operation, and repair. There are a number of factors which relate to the effectiveness and the economy of the operation, and the embodiments of the disclosure are directed toward improvements in such grinding mills and the methods employed. 
     SUMMARY OF THE DISCLOSURE 
     Disclosed herein are several embodiments of a mono roller grinding mill (MRGM). The mono roll grinding mill comprises an outer (anvil) ring, tube, or shell. The outer ring or anvil in one example has a substantially cylindrical structure with a substantially cylindrical inner surface. The shell in one example is supported on bearing pads or rollers beneath the shell. The shell rotates about a horizontal axis in use as the material therein is comminuted. The shell defines a substantially cylindrical chamber where material is placed during comminution. The MRGM in one form has a roller located within the shell, the roller in one example comprising a substantially cylindrical structure forming a substantially cylindrical outer surface. The shell may have openings to allow sized (crushed) rock to be flushed out of the machine during the anvil-roller rotation. In another example, combinable with the openings, a shield is provided with opening(s) therein for passage of material into and out of the mill. Since the centers or axes of the shell and roller are offset, their rotation causes a closing action of their surface distances to a minimum gap, where the highest compression stress is applied to the material. The shell inner surface and roller outer surface create a surface texture that grabs and captures the material during their concurrent rotating motion, forcing the material into a smaller and smaller available gap, as the roller compresses and comminutes the material against the shell, resulting in slow-steady compression fracture of the material. 
     In some embodiments, the shell and roller each have surface protrusions, such that rock or other materials may be captured between protrusions and then crushed between the shell and roller as they rotate In some embodiments, the roller has one or more circumferential annular ridges that fit within circumferential annular groove(s) of the shell such that material is crushed between the shell and the roller, due to the offset centers of the shell and roller. In this way, the shell and roller may operate at differential speeds with respect to each other to induce shear forces, as well as compression action on the material to be crushed. In this later embodiment, the circumferential ridges may have transverse ridges to restrain the rock which allows a compressive and shear comminution action to be applied to the material captured between ridges when the inner and outer rings rotate out of unison. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional, end view, of one embodiment of the disclosed MRGM. 
         FIG. 2  is a cross sectional side view of the embodiment of  FIG. 1   
         FIG. 3  is a cross sectional perspective end view of one example of the MRGM. 
         FIG. 4  is a cross sectional end view of the example of the MRGM shown in  FIG. 3 . 
         FIG. 5  is a cross sectional perspective end view of another example of the MRGM. 
         FIG. 6  is a cross sectional end view of another example of the MRGM. 
         FIG. 7  is a cross sectional perspective end view of another example of the MRGM. 
         FIG. 8  is a cross sectional end view of another example of the MRGM. 
         FIG. 9  is a cross sectional end view of an example of MRGM. 
         FIG. 10  is a cross sectional end view of another example of the MRGM. 
         FIG. 11  is a cross sectional end view of another example of the MRGM. 
         FIG. 12  is a cross sectional end view of one example of the MRGM in use. 
         FIG. 13  is a cross sectional perspective end view of one example of the MRGM in use. 
         FIG. 14  is a cross sectional end view of a prior art mill in use. 
         FIG. 15  is a cross sectional end view of the example of the MRGM shown in  FIG. 12 . 
         FIG. 16  is a cross sectional end view of the example of the MRGM shown in  FIG. 12 . 
         FIG. 17  is an end view of another example of the MRGM shown in  FIG. 1 . 
         FIG. 18  is a cross-sectional view taken along line  18 - 18  of  FIG. 17 . 
         FIG. 19  is a detail view of the region  19  of  FIG. 18 . 
         FIG. 20  is an end view of another example of the MRGM shown in  FIG. 1 . 
         FIG. 21  is a cross-sectional view taken along line  21 - 21  of  FIG. 20 . 
         FIG. 22  is a detail view of the region  22  of  FIG. 21 . 
         FIG. 23  is an end view of another example of the MRGM shown in  FIG. 1 . 
         FIG. 24  is a cross-sectional view taken along line  18 - 18  of  FIG. 17 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following disclosure, various aspects of a mono roll grinding mill (MRGM)  20  will be described. Specific details will be set forth in order to provide a thorough understanding of the disclosure. In some instances, well-known features may be omitted or simplified in order not to obscure the disclosed features. Repeated usage of the phrase “in one embodiment” or “in one example” does not necessarily refer to the same embodiment or example, although it may. 
     An axes system  10  is shown and generally comprises a vertical axis  12 , an anvil radial axis  14  extending radially outward from the center of the anvil (outer) ring  22 , a roller radial axis  16  extending radially outward from the center of the roller (inner) ring  28 , and a lateral axis  18 . The lateral axis  18  is generally aligned with the axes of rotation of the shell  22 , and the axes of rotation of the roller  28 . These axes and directions are included to ease in description of the disclosure and are not intended to limit the disclosure to any particular orientation. 
     In several examples herein, a reference system is used comprising a numeric identifier and an alphabetic suffix. The numeric identifier labels a general element and an alphabetic suffix is used in some examples to show a specific embodiment of the general element. For example, the general shell is identified in  FIG. 1  as  22 , while one specific embodiment is shown as  22   a  in  FIG. 3 . 
     To ensure clarity, the term “material” is used herein to indicate rock, mineral matter of variable composition, consolidated or unconsolidated, assembled in masses or considerable quantities, as by the action of heat or water and equivalent materials. The material (for example rock) may be unconsolidated, such as a sand, clay, or mud, or consolidated, such as granite, limestone, or coal. While not normally defined as rock, equivalent materials such as hardened concrete may also be used in the disclosed mill and are included in the term “material”. 
       FIG. 1  is a cross-sectional end view of an embodiment of a Conjugate Anvil Hammer Mill (CAHM)  20  with a floating roller. The term floating indicating that the roller may not be provided with a pressure device external of the roller  28 . Such external pressure systems are disclosed in U.S. Pat. No. 8,955,778 filed on Mar. 15, 2012 incorporated herein by reference. This embodiment of the CAHM comprises an outer shell  22  having a substantially cylindrical inner surface which defines a chamber  24 . The shell  22  is supported in one form by bearing pads  26 . Bearing pads  26  may include bearings, lubricants, and/or friction resisting materials. 
     The outer shell  22  in one example rotates about a first longitudinal center axis  42 . This outer shell  22  in in one example has a plurality of pockets or corrugations (not shown in  FIG. 1 , but shown in later figures), which interoperate with the roller  28  located within the outer shell  22 . The inner roller  28  in one form comprising a substantially cylindrical outer surface  34  which in one form is mounted to an axial shaft  30  to rotate about a longitudinal axis which is parallel to and offset from the axis  42  of the outer shell  22 , the inner roller  28  in several embodiments having a plurality of protruding elements or ridges such as the protruding elements  32  for example of  FIG. 10  attached to or formed with the outer surface  34  of the roller  28 , the protruding elements  32  in this form configured to increase efficiency of comminution as the inner roller  28  and shell  22  rotate. 
     Material  38  is inserted into the chamber  24  and comminuted between the outer surface  34  of the inner roller  28  and the inner surface  51  of the outer shell  22 . The material  38  may be mixed with a fluid (water) to aid in transport down the shell  22  and aid in comminution. In some embodiments, retaining shields  40  are positioned at the shell outer edges to contain material before and during comminution. 
     As can be seen, there may be a lateral gap  36  between the inner end surface of the shell  22  or retaining shield  40  and the end of the roller  28 . Thus, the feeding point  56  of the chute  58  may be inserted laterally  18  inward to form an overlap distance  48  such that material  38  inserted is less likely to be deposited in the gap  36 . 
     The density, size, shape, and weight of the roller may be specifically configured to maximize comminution based on shell configuration, and material to be comminuted. 
     In  FIGS. 1 and 2 , an embodiment of the roller  28  is shown positioned inside the shell  22 , wherein the rotational axes  43 / 42  of each ring are shown. In this embodiment, the shell  22  may be powered by a motor  44  and may rest on external bearings (pads  26 ). 
     In one example, the shell  22  is supported by hydrodynamic bearing pads  26  exerting lifting/supporting force on the outer surface  66  of the outer shell  22 . An embodiment is shown where the motor  44  drives the axle of the shell  22 . the outer surface  28  of the roller  28  engages the inner surface  51  of the shell  22  to transmit rotational force to the roller  28 . 
     In another example, a motor may alternatively or cooperatively drive the roller  28  by way of a gearing system on the outer surface thereof, or other apparatus such as a belt, or chain drive. 
     In some embodiments, the roller  28  may be pressed against the shell  22  by additional force, such as by filling the roller  28  with fluids (e.g. water) or other solids (e.g. sand). In one example it is desired to minimize the circumference of the roller  28  to maximize compression in a small fracture zone  78  where a larger circumference would more evenly distribute this pressure. By utilizing the weight of the roller  28  to comminute material  38  with no external pressure/drive system, power consumption directed toward forcing the roller  28  against the shell  22  can be decreased relative to prior art embodiments. This configuration operates as a constant-pressure system, rather than constant gap mill. As In this configuration, if material  38  is too hard to crush, the gap  49  between the outer surface  34  of the roller  28  and the inner surface  51  of the shell  22  will increase, rather than jamming or damaging the MRGM  20 . Thus, the floating embodiment where the roller  28  is allowed to float on the material  38  above the inner surface  51  of the shell  22  increases efficiency of the apparatus in many applications. 
     In some embodiments, the inner roller  28  has an outer diameter  52  sized between 50% and 80% of the inner diameter  50  of the outer shell  22 . 
     One example uses an inner roller  28  with an outer diameter  52  which is 0.2 (20%) of the inner diameter  50  of the outer shell  22 . Another ratio between outer diameter  52  of roller  28  and inner diameter  50  of the shell  22  may be between 0.65 and 0.7. This ratio represents a trade-off between (a) a larger inner roller  28  to improve the mechanical crushing advantage and longer wear life of the shell  22  to comminute material, and (b) a smaller shell  22  can comminute lighter throughput and be able to crush larger material due to the clearance  54  at the feeding point  56  as shown in the top of  FIG. 2 . 
     In one example, the roller  28  diameter is no less than 0.2 of the shell  22  inner diameter to ensure that pressure between the roller and the shell are adequate for breakage (comminution) of the material. 
     Looking to  FIG. 14 , the center of mass  60  common in mills including ball mills and rod mills is seen offset from the center  42  of the shell  22  by a distance  64 . This offset creating torque on the system, and greatly reducing efficiency of the overall system. Looking to  FIG. 12  is shown the center of mass  68  of a MRGM where the distance  74  is significantly reduced. 
     This torque and associated inefficiency can be further reduced where the center  43  of the roller  28  is very near the lateral position of the center  42  of the shell  22  and the speed of the shell  22  is set such that the material  38  does not build up at any location. In such an arrangement, the speed of the shell  22  in cooperation with the depth of the protruding elements  33  on the shell  22 , size/mass/density of the material  38 , inner diameter  50  of the shell  22  such that the material  38  is centrifugally forced toward the shell  22  and in each rotation of the shell  22  passes around the roller  28 . Combined with lateral  18  movement of the material  38 , this results in a helical transport  82  of the material down the shell  22  to an ejection port  96  laterally in opposition to the chute  58 . 
     Operation of one embodiment of the MRGM  20  will now be explained. Rock to be comminuted is fed into the mill in one example from a chute  58  that guides the material (rock)  38  into the chamber  24  between the outer shell  22  and inner roller  28 . Rotation of the shell  22  conveys the material  38 , by rotation and gravity to the comminution gap  49  between the shell  22  and the roller  28 , as the roller  28  applies pressure, and impacts with other material in the MRGM  20 , comminuting the material  38  within the shell  22  by way of compression fracture of the material (rock). In this embodiment, the material  38  then passes through an grate or opening or equivalent exit  96  or may be further comminuted by the rotating action of the shell  22  and roller  28  in a following rotation. In the examples shown in  FIGS. 3-11 and 12 , a shield  40  forms a ring attached to the shell  22 . The shield  40  in one example rotates with the shell  22  and as the material  38  passes over the inner edge of the shield  40 , it exits the mill  20 . This inner edge may be configured to maintain the roller  28  within the shell  22 . This retaining shield may be positioned on either lateral end of the shell  22 . 
     In some embodiments, the textured surfaces  62  of the shell  22  and/or textured surfaces  63  of the roller  28  as shown by way of example in  FIG. 10  assist in breaking the material  38 . In one previously described example the shell  22  is rotated by an external drive (motor  44 ) either near a central region as shown in  FIG. 2  or adjacent the bearing pads  26  on the perimeter, or other methods. The material  38  generally does not conform to the surfaces  62 / 63 ; thus the material  38  will commonly bridge from one texture surface to another in a two, three, or more point contact compression resulting in shear fracture of the material  38 . As each protruding element  32  contacts the material  38 , the material will tend to fracture and break. 
     In one example (G) as shown by way of example in  FIG. 10 , the roller  28   g  includes protruding elements  32 . The inner surface  51  of the shell  22  may be smooth or may include protruding elements  33 . 
     Looking to the example of  FIG. 3  and  FIG. 4 , an example (A) is shown where the protruding elements  32   a  on the roller  28   a  comprise ridges that extend laterally  18  down the roller  28   a . Similarly, the inner surface  51   a  of the shell  22   a  may comprise protrusions  33   a  that form ridges that extend laterally  18  down the shell  22   a.    
     Looking to the example shown in  FIG. 5 , the shell  22   b  and the roller  28   b  have protrusions  32   b  and  33   b  comprising ridges that extend helically down the shell  22   b  and/or roller  28   b . The ridges on the shell  22   b  of this example are not parallel to the ridges on the roller  28   b , and are substantially orthogonal at the compression fracture zone  78 . In one example, these ridges are configured to manipulate the material  38  as it passes laterally  18  down the shell  22   b  towards the exit  96  so as to maximize efficiency by controlling the number of circumferential passes through the compression fracture zone  78 . 
     Looking to  FIG. 7  is shown an example where the shell  22   c  and the roller  28   c  have protrusions  32   c  and  33   c  comprising ridges that extend down the shell  22   c  and roller  28   c . The ridges on the shell  22   c  are generally laterally aligned and the ridges on the roller  28   c  are substantially helical, thus they are not parallel to the ridges on the shell  22   c , and in this example are substantially orthogonal at the compression fracture zone  78 . In one example, these ridges are configured to manipulate the material  38  as it passes laterally  18  down the shell  22   c  towards the exit end so as to maximize efficiency by controlling the number of circumferential passes through the compression fracture zone  78 . 
     In the example shown in  FIG. 6 , the roller  28   c  has protrusions  32   c , while the shell  22   c  is substantially smooth on the inner surface. 
     In the example shown in  FIG. 8 , each of the roller  28   e  and the shell  22   e  have adjacent surfaces that are substantially smooth. 
     In the example shown in  FIG. 9 , the shell  22   f  has protrusions  33   f , while the roller  28   f  is substantially smooth on the inner surface  51   f.    
     In the example shown in  FIG. 10 , the shell  22   g  and the roller  28   g  have protrusions  32   g  and  33   g.    
     In the example shown in  FIG. 11 , the shell  22   h  and the roller  28   h  have protrusions  32   h  and  33   h . These protrusions are circumferentially asymmetric, forming ramps with a leading surface of a different configuration (angle or curvature) than the trailing surface relative to the direction of material flow  98 . 
     In the example shown in  FIG. 20-22  each of the shell  22   j  and roller  28   j  comprise protruding elements  33   j  and  32   j  respectively that extend laterally  18  and circumferentially down the MRGM  20 . The protrusions  33   j  and  32   j  nest together as a worm gear type arrangement, facilitating lateral movement of the material  38  from the inlet  58  to the exit  96 . 
     During initial startup of the MRGM  20 , an initial buildup of material  38  is anticipated at a loading end location  88 . This may result in tilting of the roller  28  as shown in  FIG. 21 , resulting in lateral movement of the roller  28  relative to the shell  22 . In at least one example, this lateral movement may be unexpectedly toward the feed end  90 . Thus, a fillet  92  (rounded edge) may be formed on the inner lateral end(s) of the shell  22  as well as a cooperating fillet  94  on the lateral end(s) of the roller  28 . 
     In one example this tilting is temporary, as the material  38  begins to exit at the ejection port  96  the system is more balanced. In other examples, the MRGM  20  is configured to maintain such a tilt, so as to improve efficient movement of material  38  from the chute  58  to the ejection port  96 . 
     In at least one example, the shell  22  may not have an even inner diameter  50  down the lateral length thereof but may be a frusta-conic shape to improve material movement. Similarly, the roller  28  may not have an even outer diameter  52  down the lateral length thereof, but may be a frusta-conic shape to improve material movement. 
     The roller  28  in one example is preferably positioned by gravity to achieve the desired gap  72  between shell  22  and roller  28 . One preferable position is achieved when broken material surface area is maximized for a given shell  22 . 
     In one example, material  38  is contained in the chamber  24  by the moving shell  22  and a shield  40 . In one example the feed chute  58  passes through or around the shield  40  chamber  24 . The shield(s) withhold the material from escaping the mill  20  at undesired positions during comminution. 
     In some embodiments, once the material  38  is crushed and rotates counterclockwise past a 6 o&#39;clock position  76  (the 6 o&#39;clock position being the position of minimum gap  49  between the two rings as shown in  FIG. 3 ) a desired number of rotations as shown in  FIG. 18  and in  FIG. 21 , most of the material will exit the mill  20  either through the openings  70  or through an opening in the shield  40 . In these embodiments, retention of the comminuted matter will aid in crushing more of the remaining matter as is understood by looking to  FIG. 12-16  where it can be seen that the material  38  tumbles, slides, and commutates the other material  38  as contact is made. In these figures it can be seen that the kidney, or shape of the comminuted material  38  is affected by the roller  28 , and the roller  28  thus imparts additional pressure in the compression fracture zone  78 . 
       FIG. 14  shows a mill  20  rotating at a relatively high rate of speed without a roller, where the material  38  travels further circumferentially around the shell  22  and drops onto the kidney  53 . Such examples do not control a compression fracture zone  78  and thus are less efficient than an MRGM  20 . 
     Additionally, some embodiments allow material  30  to re-enter the compression fracture zone  78  as shown in  FIG. 1, 18, 21  to create a finer ground material and/or to make a most efficient MRGM  20 . To this end, grates or classifiers of various designs known in the art may be utilized. For example, one example may involve grinding the material with successively finer grinding surface features between the shell  22  and roller  28  (axially from one side of the ring to the other side, parallel to the axis of rotation), whereby material  38  is fed from one lateral end of the mill  20  and discharged out the opposite lateral end. For example, an embodiment may have multiple stages of coarse to fine grinding in the same mill  20 , moving material dimensional geometries from large roller, to fine pin mesh as rock axial motion is utilized by trapping comminuted material  38  as the material  38  rotates up the shell  22  inner surface  51  or by tilting the mill  20  on its rotating axis  42 . 
     In some embodiments, the shell  22  may be mechanically driven by a motor  44  or equivalent device. For example, the shell  22  may rest on a ring and pinion gear system that drives the shell by the motor  40  or engine. The roller  28  is not connected to any control or drive apparatus, and thus floats on the material  38  during comminution. This makes modification of existing mills easy as the roller  28  may simply be inserted to replace multiple rods, balls, driven rollers, etc. No control or drive mechanism need be provided to the roller  28 . The control is the design of the outer surface of the roller  28  relative to the inner surface  51  of the shell, and the size, weight, density of the roller  28 . 
     In one example, the roller  28  has a first diameter at a first end, and a second diameter at other positions there along to control lateral  18  movement of material  38  along the mill  20 . In one example the roller is tapered along the lateral length to accomplish this. The protrusions on the roller, and on the shell may be configured to maximize the benefits of this geometry. 
     In one example the core of the roller  28  may be made of a different material than the outer surface. For example, the core may be made of lead, while the outer surface is steel, to maximize density, comminution efficiency, and life of the roller  28 . 
     In one example the ratio of the protrusions on the roller  28  is configured to maximize efficiency. In the example shown in  FIG. 12 , the relative size of the ramp-shaped protrusions  32 / 34  is equivalent, whereas the example shown in  FIG. 15  shows arcuate protrusions  32 / 33  having equivalent size. In each example, the number of protrusions  32  on the roller  28  is less than the number of protrusions on the shell  22  resulting in the roller  28  rotating at a faster angular velocity than the shell  22 . The example shown in  FIG. 16  shows a greater number, and smaller size protrusions  32  on the roller, resulting in a more similar angular velocity between the roller  28  and the shell  22 . Where the number of protrusions around the roller  28  equals the number of protrusions on the shell  22 , the relative angular velocity will be the same (they will rotate at the same speed). 
     In some embodiments, one or both of the shell  22  and roller  28  may have ridges  84  and/or grooves  86  as shown in  FIG. 3, 5, 7  to increase surface contour to better grip and retain material  38  entering the compression zone  78 . In this embodiment, the ridges may also impart shear stresses due to differential speeds between shell  22  and roller  28 . 
       FIG. 13  is a perspective view of a portion of an embodiment of a MRGM  20  illustrating material  38  (rock) being crushed in the mill  20 . The material  38  may then reposition toward the compression zone  78  and as the anvil  22  and roller  28  rotate, the material  38  is compressed between the anvil  22  and roller  28  as the gap  72  between the anvil  22  and roller  28  decreases into the compression zone  78 . As depicted in the embodiment of  FIG. 2 , material  38  that is smaller than the exit grates (openings)  70  passes through the outer surface  66  of the roller  28 . Non-ejected material  38  may remain in the MRGM  20  and return to the compression fracture zone  78  where it will eventually be ejected. Ejection may also occur past the shield  40  as previously described. 
     In one embodiment as shown in  FIG. 1 , the shield  40  may include an open region such that the rock which does not pass through the openings  70  when provided, may be ejected through the ejection port  96  along the direction of flow. 
     Additionally, the holes  70  in the grates of the shell  22  or laterally inward of the ejection port  96  may be sized according to the degree of comminution desired. For example, if it is desired that the largest resultant crushed material  38  have a maximum diameter of 50 mm then the grates  70  of the apparatus would have an inner diameter (width/length) of 50 mm. Additionally, the grates  70  may have different dimensions in other directions, for example, a hole may have a 50 mm width and a 150 mm length, where the length may be in the direction circumferentially around the inner surface of the outer ring. The size of the hole  70  may also be selected to reduce power consumption (as there is a pronounced increase in power consumption for a relatively small percentage change in hole size). 
     One significant disadvantage of prior art high pressure grinding roll (HPGR) and other crushing mills is that material would often jam between the shield and one or both rollers. In many prior art applications, the shield is static, and does not rotate with the shell  22 , further causing material to jam between the shield and the other components. This problem has been at least partially alleviated herein a where the shield  40  of one example is attached to the shell  22  either permanently or removably and rotates therewith. Thus, the shield(s)  40  will generally hold material  38  within the chamber  24 , and any material that would lie against the shield  40  in the compression zone  78 , will be compressed therein. 
     A mono roll grinding mill using a roller with no external pressure device substantially reduces capital cost, complexity and operating costs. Further, an un-driven roller in such an arrangement also substantially reduces capital cost, complexity and operating costs. Despite this no such mono roll grinding mill with floating roller exists in the prior art, despite numerous benefits outlined herein. 
     While the present disclosure is illustrated by description of several embodiments and while the illustrative embodiments are described in detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications within the scope of the appended claims will readily appear to those sufficed in the art. The disclosed apparatus and method in their broader aspects are therefore not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicants&#39; general concept.