RU2821026C1 - Laboratory continuous semi-autogenous grinding (sag) mill - Google Patents

Abstract

FIELD: separation.

SUBSTANCE: invention relates to a system for continuous wet semi-autogenous grinding (SAG), which can be used in laboratories as testing equipment. System comprises a frame, a rotating cylinder supported inside the frame with possibility of rotation around a horizontal axis of rotation with respect to the frame, variable-speed drive system to drive revolving cylinder and SAG mill. Rotating cylinder includes multiple discharge holes along its periphery and internal spiral blade for gripping material inside the rotating cylinder, which is located after discharge holes, upwards to discharge holes during rotation. SAG mill is detachably attached to the rotating cylinder before the discharge holes. SAG mill includes a grinding chamber drum in a forward section of a rotating cylinder, wherein grinding chamber drum has inner diameter of about 19.2 inches and length of about 6.4 inches and comprises at least one internal elevator.

EFFECT: system for continuous wet semi-autogenous grinding ensures efficient operation of the SAG mill.

13 cl, 7 dwg

Description

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Patent Application Serial No. 63/037,892, filed June 11, 2020.

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

[0002] The following applies generally to semi-autogenous (SAG) mills and, in particular, to a laboratory wet SAG mill that can continuously operate less than one inch ore as a test on a SAG mill pilot plant to prepare a feed for testing on a pilot mini mineral extraction plant.

BACKGROUND OF THE INVENTION

[0003] Ore that is mined from the earth, whether in a quarry or underground, comes in a variety of particle sizes, from relatively small sizes to large chunks of mineralized material. The ore must be crushed to a particle size suitable for leaching or otherwise separating the valuable metals from the ore as natural minerals.

SUMMARY OF THE INVENTION

[0004] In accordance with one aspect of this disclosure, there is provided a continuous wet semi-autogenous (SAG) mill system, otherwise referred to herein as a continuous wet SAG mill system, comprising: a frame; a rotating cylinder supported within a frame so as to rotate about a generally horizontal axis of rotation with respect to the frame, the rotating cylinder including a plurality of discharge openings along its periphery and an internal helical paddle for picking up material within the rotating cylinder, which is after the unloading holes (further downstream relative to the unloading holes), in the opposite direction (closer downstream) to the unloading holes during rotation; a variable speed drive system for driving the rotating cylinder about an axis of rotation; and a SAG mill removably attached to the rotating cylinder in front of the discharge ports, the SAG mill comprising: a grinding chamber drum in a forward portion of the rotating cylinder, the grinding chamber drum having an internal diameter of about 19.2 inches and a length of about 6.4 inches, with this grinding chamber drum includes at least one internal lift; a feed end diaphragm attached to an upstream end of the grinding chamber drum, the feed end diaphragm including a central feed opening sized to allow crushed material to pass into the grinding chamber drum; and a discharge grid diaphragm removably attached to a downstream end of the grinding chamber drum, wherein the discharge grid diaphragm includes a plurality of discharge slots, the size and position of each of which allows the passage of only material that has been crushed to a predetermined size within the grinding chamber drum for passing through them.

[0005] In one aspect, the upstream end of the cylinder includes a peripheral cylinder flange to which the SAG mill loading end diaphragm is removably attached.

[0006] In one aspect, the downstream end of the grinding chamber drum includes a peripheral drum flange to which a discharge grate diaphragm is removably attached.

[0007] In one aspect, the feed end diaphragm is welded to the upstream end of the grinding chamber drum.

[0008] In one aspect, the frame is a cuboid frame.

[0009] In one aspect, the at least one internal lift includes a square-shaped lift.

[0010] In one aspect, the square-shaped lift has an area of 1.5 square inches.

[0011] In one aspect, the at least one internal lift includes a plurality of rectangular lifts.

[0012] In one aspect, the SAG mill system further comprises: an inlet pipe extending through the downstream end wall of the cylinder for supplying fluid and ore to the grinding chamber drum.

[0013] In one aspect, the discharge slots are located concentrically in the discharge grid diaphragm around an axis of rotation.

[0014] In one aspect, the drive system includes an electric motor and a circuit coupled to an external rotating cylinder.

[0015] In one aspect, the discharge grate diaphragm further includes a central control hole sized to receive a linear measuring rod extending from the outside of the cylinder through one of the selected discharge holes, thereby measuring the height of the material feed inside the SAG mill.

[0016] In one aspect, the central control hole is sized to allow excess material to exit the grinding chamber drum without flowing back to the feed inlet.

[0017] Other aspects and embodiments will become apparent upon reading the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Embodiments of the invention will now be described with reference to the accompanying drawings, in which:

[0019] FIG. 1 is a top view of a continuous wet semi-autogenous (SAG) mill according to an embodiment;

[0020] FIG. 2 is a side elevation cross-sectional view of the SAG mill system of FIG. 1;

[0021] FIG. 3 is a front cross-sectional view of the SAG mill system of FIG. 1 taken along line E-E of FIG. 2;

[0022] FIG. 4 is a side elevation cross-sectional view of the SAG mill and the upstream cylinder portion of the SAG mill system of FIG. 1, separately;

[0023] FIG. 5 is a top view of the SAG mill system of FIG. 1, with the top soundproof panel in position to enclose the components of the SAG mill system within the frame;

[0024] FIG. 6 is a vertical side view of the SAG mill system of FIG. 1, with the side soundproof panel in position to enclose the components of the SAG mill system within the frame; and

[0025] FIG. 7 is a cross-sectional top view of the SAG mill system of FIG. 1 along line C-C of FIG. 6.

DETAILED DESCRIPTION

[0026] Various methods are used in industry to effect size reduction, examples of which include crushing, rod and ball milling, autogenous comminution (AG) and semi-autogenous (SAG) or comminution. In SAG grinding, the ore is crushed to approximately 200 mm in the primary crusher, crushed and ground in a rotating mill containing large steel balls. An autogenous mill differs from an SAG mill in that it operates without steel balls. The balls in the SAG mill are usually steel balls. As the mill rotates, the balls are lifted by fixed lifting rods and then dropped onto the ore. The impact causes the large ore particles at the bottom of the charge to crush, crack and break, or otherwise transform into smaller particles, facilitated by abrasive grinding throughout the oval-curved charge. When the particulate material reaches the required size for subsequent ore processing, the particulate material is removed from the SAG mill through the diaphragm screen and discharge ports. The choice of particle size to be discharged and removed from the system is controlled by the size of the discharge screens and the use of screens or other types of classifiers and/or a group of hydrocyclones. By recycling oversized screens or classifiers back to the feed, the SAG mill can operate virtually continuously.

[0027] Industrial scale SAG mills are large and process many tons of ore per hour. The requirements for an SAG mill will vary depending on the characteristics of the particular ore body to be processed. Additionally, the ore will usually not have the same characteristics throughout the deposit. For example, the hardness characteristics of the ore and the concentration of minerals and metals may vary. Some parts of the ore body may be composed of relatively soft rock compared to other parts of the ore body. Therefore, the design of an industrial-scale SSI mill must be optimized to improve the processing efficiency of a particular ore mass. Thus, before a commercial SAG mill can be designed and built, the grinding characteristics of the ore mass must be verified, which in turn requires testing samples from different parts of the ore mass. The results obtained are used in the design of an industrial-scale SAG mill, which, if properly designed, will grind specified tons of ore per hour continuously at a given process feed rate. Flotation processing plants require the ability to operate the mill at a constant tonnage because maximum recovery cannot be achieved if the feed tonnage fluctuates.

[0028] Standard industry procedure was to use a pilot SAG mill having a diameter of six feet and an effective grinding length of two feet. Such a pilot SAG mill is used to provide metallurgical recovery data on crushed ore processing flowsheets and grinding characteristics, such as specific energy, to achieve the required fineness and product size distribution of the crushed material, which are representative and can be used at scale-up for mill design Industrial scale PSI. However, the pilot SAG mill, which is about six feet in diameter, processes up to one ton of ore per hour, and each test must be run for several days to obtain the data needed for scaling up calculations. Thus, a large quantity of ore is currently required for any pilot plant comminution test. Since no single ore sample is representative of the entire ore mass, it is necessary to obtain and process numerous samples from the ore mass, and many tons of each sample are required. Because of this, most plants are designed and built without adequate design data, which in turn leads to costly errors and production shortfalls. In reality, to get an underground mine up and running, obtaining a large sample (200mm size class pieces) suitable for testing in an SSI pilot plant is prohibitively expensive, and as a result, only open pit mines can be properly tested before start-up.

[0029] One effective alternative is to use a laboratory grade SAG mill approximately 19.2 inches in diameter and 6.4 inches long inside the chamber. An SAG mill of this size only requires a small sample of ore as a standard diamond drill core (15 kg required) and is run as a batch laboratory test rather than a continuous pilot plant test. Since significantly less quantity of each ore sample is required, the time and effort required to obtain and deliver multiple samples from an ore body, as well as sample processing time in this small SAG mill, are significantly reduced. However, a small SAG mill only provides data on ore hardness, ore specific gravity, and predicted energy consumption. This is sufficient data to calculate and scale up the size of the required mills (PSI and ball mills) to commercial size, when sufficient data will be obtained to determine the hardness variability functions for the array. However, this batch test does not provide the real-time continuous process data needed to validate laboratory energy consumption measurements, the real-time particle size distribution data needed to accurately design classification equipment needed to handle circulating load flow at full scale. installation, or metallurgical recovery reaction of crushed minerals, necessary to confirm the financial viability of the mining and processing operation. Customers and investors require this information to reduce the risk that a processing plant will not operate. Laboratory testing of the batch also does not provide sufficient quantities of crushed material for subsequent hydrometallurgical or pyrometallurgical pilot testing, which are necessary to physically recover minerals and/or metals for sale, as well as to demonstrate the purity of the mineral extraction, which will in turn determine the value of the recovered metal. On the market. Thus, meaningful pilot testing of a SSI mill crushed ore plant cannot be conducted at a reasonable cost from an underground deposit. In particular, minimal data have been obtained on the grinding aspects of the operation of a commercial SAG mill. Thus, the designer of an industrial scale SAG mill and downstream processes is forced to make design assumptions without actual supporting pilot plant data and without evidence of whether downstream metallurgical processes will respond as predicted by operation of a pilot plant that is not using the proper SAG process in continuous operation. grinding

[0030] Currently, in North America, most, if not all, metallurgical testing by flotation, leaching, gravity and magnetic beneficiation is carried out on a scale of approximately 10 to 100 kg per hour, with preparation for grinding carried out on finely crushed ore ( size class 1.7 mm) followed by grinding the ore in a ball mill to the size necessary for the extraction of minerals. By eliminating the PSI of grinding this material, the possibility of making serious errors in process selection increases, especially when, with excess PSI, the resulting fines consume large amounts of expensive reagents. The consequence of this is that the proposed industrial scale SAG mill is not the correct size or rating, and that the process so constructed may be incorrectly sized and inefficient.

[0031] The SAG mill pilot plant, with a diameter of approximately six feet and an effective grinding length of approximately 2 feet, has been the test SAG mills adopted and used in the industry for many years, especially for homogeneous ores that have been found in the iron ore processing business. However, given the heterogeneity of most copper and gold ores, a more economical device and method was required to test the hardness of ore mass samples prior to the design of an industrial scale SAG mill and subsequent processes, due to the wide variability of ore hardness.

[0032] US Patent No. 6,752,338 to Starkey, the contents of which are incorporated herein by reference, discloses a ball mill pilot plant (which is actually an SAG mill) comprising a cylindrical outer chamber having flanges at opposite ends, wherein said cylindrical outer chamber has a diameter of 2.5-5.5 feet and a length to diameter ratio of greater than 1:1. The cylindrical outer chamber contains a removable grinding chamber in the form of a sleeve, longitudinal lifters and a diaphragm, wherein said removable grinding chamber has a diameter to length ratio ranging from 3:1 to 1:1 and contains a plurality of steel balls not exceeding 15% of the volume of the grinding chamber . The removable grinding chamber extends partially along the length of the outer cylindrical chamber and has longitudinal lifters attached to the inner surface of the sleeve, capable of lifting steel balls and large pieces of ore located in the removable grinding chamber when the two cylindrical chambers rotate. The removable grinding chamber has at one end means for receiving ore particles from the feed hopper and said removable diaphragm at the opposite end. The removable diaphragm has outlet openings for discharging crushed ore particles into a cylindrical outer chamber, said cylindrical outer chamber having discharge openings for discharging crushed particles from the mill (PSI) and means for rotating the cylindrical outer chamber about a longitudinal axis. A test method using a ball mill (BMM) has also been disclosed.

[0033] US Patent No. 7,197,952 to Starkey, the contents of which are incorporated herein by reference, discloses a test method for designing an SAG or AG grinding circuit having at least one ball mill for grinding ore. The test method includes measuring the speed of a batch test mill for grinding a predetermined volume of ore to a first predetermined size in the first stage of SPM; calculation of the required grinding energy based on the measured revolutions for grinding in the first stage, the volume and the measured specific gravity of the ore; grinding in a ball mill at the second stage of ore from the first stage to a second specified size; and calculating, using Bond's Ball Mill Index, the required ball mill energy for the second stage required to produce the desired final grind size.

[0034] While the above patents disclose useful SAG pilot mill configurations and useful laboratory batch testing, to overcome the shortcomings of the prior art, improvements are desirable to enable meaningful, repeatable and relevant pilot plant testing for every mining project, including both open and underground mineral deposits. In particular, the use of standard diamond drilling for SAG pilot plant testing can open the door to full pilot plant testing of every known mineral deposit, as standard diamond drilling is used on every mineral discovery to determine the location and quality of the valuable minerals contained in the deposit . What is described here can significantly improve the quality of newly developed crushing and mineral extraction systems, since the prior art is based on the premise that the operation of the SIG pilot plant must be performed using rock pieces of at least 152 mm in size. However, based on analysis of laboratory test data over the past 15 years, it has been found that by using a laboratory batch SAG mill grinding chamber of approximately 19.2 inches in diameter and approximately 6.4 inches in length, SAG mills up to 40 feet in diameter can be accurately designed based on laboratory test data. Since the energy used in laboratory testing is about 75% of the energy used in processing a 152 mm load, it is now known that good designs may be possible using 80% of the passage of a 19.05 mm load, which is easily obtained from any standard core. diamond drilling. Importantly, this core size is available for almost every mineral deposit in the world.

[0035] The intent of an aspect of this disclosure is to provide the ability to avoid SSI and SI mill sizing and processing errors and allow owners to maximize profits from their new mining operations from the time the plant begins processing ore in the SSI or SI mill.

[0036] FIG. 1 is a top view of a continuous wet semi-autogenous (SAG) mill system 10 according to an embodiment. The SAG mill system 10 in this embodiment is a wet system having features that allow it to operate continuously. In particular, the SAG mill system 10 can operate to provide real-time continuous process data that is needed to validate laboratory energy consumption measurements, and real-time particle size distribution data that is needed to accurately design classification equipment needed for processing the circulation load flow in a full-scale plant. Because systems configured only for periodic laboratory testing do not provide sufficient quantities of crushed material for subsequent hydrometallurgical or pyrometallurgical pilot plant testing, or to demonstrate the purity of metal production, which in turn will determine the market value of the recovered metal, System 10 SAG mills can be operated continuously to process sufficient quantities of material so that sufficient and accurate data can be collected at a reasonable cost. As used herein, the term "continuously" or "continuous" refers to the operation of the system such that it accepts material while at the same time crushing material that has already been received so as to crush and discharge newly received material along with the material that has been received. which was crushed as new material was accepted, thereby processing sufficient volumes of material so that sufficient and accurate data could be obtained. This can be contrasted with a batch operation, in which a quantity of material is received at one time or over a short fixed period, and the quantity of material is processed and/or substantially completely discharged before another quantity of material is received for another discrete batch and test. It is understood that the SAG mill system described herein, considered to be in continuous operation, may therefore actually be stopped from feeding and rotating periodically, for example to briefly check the height/level of material in the SAG mill before resuming feed and rotation during a given test. This check can inform changes in the feed rate of material into the SAG mill during continuous operation.

[0037] The PSI mill system 10 includes a cylindrical 20 PSI mill attached and supported within a cylinder 40. The cylinder 40 extends longer than the 20 PSI mill 20 to provide balance and controllability of the system during rotation, and is itself supported within a cube-shaped frame 30 with the ability rotation relative to the frame 30 around the axis R of rotation. The cuboid frame 30 includes integral legs 32. The legs 32, in turn, can be attached to a supporting surface, such as a floor or workbench, using fasteners such as bolts. The bolts pass through the leg flanges 33 and into the support surface.

[0038] FIG. 2 is a side elevational cross-sectional view of the 10 PSI mill system, and FIG. 3 is a front cross-sectional view of the 10 PSI mill system along line E-E in FIG. 2.

[0039] FIG. 4 is a side elevation cross-sectional view of the SAG mill 20 and the upstream portion of the cylinder 40 of the SAG mill system 10 separately. As can be seen particularly in FIG. 4, in this embodiment, the PSI mill 20 includes a feed end diaphragm 22, a grinding chamber drum 24 attached to and extending from the feed end diaphragm 22, and a discharge grate diaphragm 26. removably attached to the drum 24 of the grinding chamber opposite the diaphragm 22 of the loading end. The discharge grate diaphragm 26 may be secured by bolts or other fastening mechanism suitable for removing fasteners such that the discharge grate diaphragm 26 can be removably attached to the grinding chamber drum 24 as described.

[0040] In this embodiment, the grinding chamber drum 24 has an internal diameter of about 19.2 inches and a length of about 6.4 inches. In this embodiment, lifters 23 extend from the inner walls of the grinding chamber drum 24 generally inward to lift ore to be processed (not shown) as well as steel balls (not shown) for processing.

[0041] In this embodiment, the feed end diaphragm 22 is welded at its periphery to the upstream end of the grinding chamber drum 24. The circular feed opening 25A extends centrally through the feed end diaphragm 22, thereby allowing crushed material from outside the mill chamber 20 to be fed into it for grinding. This allows the 20 PSI mill to be loaded with the material to be ground as well as steel balls. In this embodiment, the circular feed opening 25A has a diameter of 3.5 inches and is centered on the R axis of rotation. While the 20 PSI mill is rotating about the rotation axis R, material can be fed into the 20 PSI mill through the round feed hole 25A. The feed end diaphragm 22 is itself bolted to the upstream flange of the cylinder 40 and thus rotates with the cylinder 40 rotating with it the rest of the PSI mill 20 during operation of the PSI mill system 10. The feed end diaphragm 22 can be unscrewed from the cylinder 40, allowing the 20 PSI mill to be removed from the interior of the cylinder 40 for maintenance and modifications. Other methods of removably attaching the loading end diaphragm 22 to the cylinder 40 are also possible.

[0042] In this embodiment, the discharge grate diaphragm 26 is bolted at its periphery to the downstream end of the grinding chamber drum 24. As can be seen in FIG. 3, a series of concentrically located slots 27, only a few of which are indicated by guide lines in FIG. 3, continue through the discharge grate diaphragm 26, thereby allowing material to be discharged from the inside of the mill chamber 20 to the outside after grinding in the cylindrical chamber. mill 20, as will be described below. The size of each slot 27 corresponds to the maximum particle size that must be discharged from the SAG mill system 10 after grinding. The discharge grate diaphragm 26 otherwise blocks the discharge of larger material and blocks the discharge of steel balls. The slots 27 are arranged concentrically to provide a path for the crushed material to exit into the cylinder 40 at all angles of rotation of the cylinder 40, thereby facilitating continuous operation of the SAG mill system 10.

[0043] The discharge grid diaphragm 26 can be unscrewed from the grinding chamber drum 24 so as to separate the discharge grid diaphragm 26 from the grinding chamber drum 24. The discharge grid diaphragm 26, removably attached to the drum 24, allows different diaphragms, respectively, with larger or smaller slots, to be connected to the cylinder 24. This allows the user of the SAG mill system 10 to use alternative diaphragms with larger or smaller slots 27 of this discharge grate diaphragm 26 to control the size of particles to be discharged out after grinding. It will be understood that in order to remove or attach the discharge grate diaphragm 26 to the grinding chamber drum 24, the mill 20 PSI must first be removed from the cylinder 40 by unscrewing the charge end diaphragm 22 from the upstream end of the grinding chamber drum 24. Other methods of removably attaching the diaphragm 26 of the discharge grid to the drum 24 of the grinding chamber are also possible.

[0044] It has been found that maintaining the height of the material within the drum 24 at or about 26% of the volume available in the SAG mill 20 during pilot plant testing, as much as possible, is beneficial in maintaining the grinding efficiency of the SAG mill system 10. For example, it should be understood that if there is too little material in the 20 PSI mill, the available grinding capacity of the 20 PSI mill may be underutilized. On the other hand, if there is too much material in a 20 PSI mill, grinding performance may be reduced. Grinding performance may begin to decline after a certain volume of material is exceeded, as the additional material also serves as a cushion against falling material and steel balls, reducing the overall amount of coarse grinding that can be accomplished with such material and steel balls. To solve this problem, in this embodiment, a circular inspection hole 25B centered on the rotation axis R is also extended through the discharge grate diaphragm 26. The size of the circular test hole 25B allows a linear measuring rod to be passed through the circular test hole 25B and thus through the discharge grate diaphragm 26 to measure the height of the material inside the 20 PSI mill. In this embodiment, the circular inspection hole 25B has a diameter of 5.5 inches. It will be understood that the circular inspection hole 25B also allows excess material due to overfilling of the 20 PSI mill to be discharged through the circular inspection hole 25B rather than creating a buildup within the drum 24 at the feed end where it could damage the feed tube.

[0045] Immediately downstream of the PSI mill 20, discharge openings 29 continue through the side periphery of the cylinder 40. The discharge openings 29 serve to allow material to be discharged from the slots 27 of the discharge grate diaphragm 26 into the cylinder 40 to exit the cylinder 40, as will be described below.

[0046] In this embodiment, the relief holes 29 are evenly distributed around the periphery of the cylinder 40 and are oval in shape with a width of 2 inches and a length of 5.5 inches. The material discharged from the 20 PSI mill through the slots 27 enters the cylinder 40 and generally falls through the discharge openings 29.

[0047] The relief holes 29 are sized and positioned relative to the circular reference hole 25B to provide a linear path for a linear gauge rod to extend from the outside of the cylinder 40 into the circular reference hole 25B through one of the relief holes 29.

[0048] In this embodiment, cylinder 40 has a diameter of about 21 inches and a length of about 20 inches. The cylinder 40, while longer than the 20 PSI mill, is useful for physically stabilizing the 20 PSI mill during operation and for providing a surface that can be engaged for driving and rolling, as will be described below.

[0049] Beyond the discharge openings 29, the cylinder 40 includes a helical blade 45 extending inwardly from the side walls of the cylinder 40. It will be understood that a portion of the crushed material that has been discharged into the cylinder 40 through the discharge grate diaphragm 26 may be ejected through the discharge openings 29 into cylinder 40. Thus, such material is not immediately discharged through the discharge ports 29. For measurements using the SAG mill system 10, it is important that the material loaded into the SAG mill system 10 is ultimately discharged completely from the SAG mill system 10. The helical blade 45 rotates with the cylinder 40 during rotation in a continuous manner, thereby continually forcing any material that has been ejected downward from the discharge openings 29 back up toward the discharge openings 29, thereby completely discharging it. In this embodiment, the inlet pipe P extends centrally through the downstream end wall of the cylinder 40 inward to form a passage through which water (or other suitable fluid) can be introduced into the cylinder 40. The inlet pipe P extends centrally along the axis R rotation - into the downstream end wall of the cylinder 40, so that the cylinder 40 can rotate relative to the intake pipe P during continuous operation, despite the fact that the intake pipe P itself remains stationary. The stream of added water mixes with any material downstream of the discharge openings 29 to assist in entraining material within the cylinder 40 back up to and from the discharge openings 29.

[0050] In this embodiment, a typically V-shaped discharge hopper 50 is also supported by a cube-shaped frame 30 and is axially aligned with the discharge openings 29. The discharge hopper 50 receives the discharge material exiting the discharge openings 29 around it. during rotation during continuous operation. The discharge hopper 50 directs the discharged material down through the discharge passage 52 of the discharge hopper 50 to supply the discharged slurry to a vibrating screen or other classification device, and to examine and measure the flow, and to extract and manually recirculate the oversized material back to the SAG mill feed hopper through equal time intervals. The mill discharge passage 52 terminates at a point above the lowest extent of the legs 32 and underlying flanges 33, thereby allowing the legs 32 and flanges 33 to rest on the support surface without interference. The support surface, in turn, preferably has an opening through which material exiting the mill discharge passage 52 can flow downward for further classification and coarse recycling.

[0051] The discharge hopper 50, as viewed from the front of the 10 PSI mill, has “arms” that extend upward and close to the discharge openings 29 just above the level of the R axis of rotation. The arms are integrated with the collection chamber 54 of the discharge hopper 50. Each of the inward-facing portions of the arms and the collection chamber 54 have an opening top to receive discharge material exiting the discharge openings 29. For this reason, each of the arms are generally integrated channels , which receive discharged material exiting discharge openings 29 at any point along the arms. This configuration allows most of the discharge material that may be carried upward within the cylinder 40 that has not fallen straight down into the collection chamber 54 after grinding as it exits the discharge openings 29 to enter the open mouths of the discharge hopper arms 50. This, in turn, line, holds most or all of the discharge material exiting the SAG mill system 10 through the mill discharge passage 52 during continuous operation. Such discharge material exiting the discharge openings 29 at these higher locations is captured by the arms and directed downward along the arms to combine with any material in the collection chamber 54 and ultimately falls through the mill discharge passage 52.

[0052] In this embodiment, the cylinder 40 is supported by rubber rollers 90. In turn, the rubber rollers 90 are supported by corresponding axles, which in turn are supported by beams extending through the bottom of the cube-shaped frame 30. Thus, the mill is 20 PSI and the cylinder 40 can rotate as a unit about a rotation axis R with respect to the cuboid frame 30. It should be noted that the rubber rollers 90 are in contact with the annular, circular machined surface of the guide tracks formed by pairs of flanges 92 and 94 (indicated by dotted circles in Fig. 1) , which are located near, respectively, the front and rear ends of the cylinder 40.

[0053] In this embodiment, rotation of the cylinder 40 is achieved using an electric motor 100 driving a chain 110. The chain 110 is secured around the cylinder 40. The electric motor 100 is supported on a motor platform 102 extending from a cube frame 30, and a chain guard 112 is supported on top of the chain 110 by a cube-shaped frame 30. In this embodiment, the electric motor 100 is rated at 2 hp/1800 rpm/230 V/3 phase/60 Hz. A variable frequency drive (VFD) component (not shown), rated at 230 V/3 phase/60 Hz, powers the electric motor 100, allowing the user to reliably and efficiently control the speed at which the cylinder 40 rotates, and therefore the speed at which the cylinder 40 rotates. which the mill 20 rotates. It is clear that a mill speed of 20 PSI is important for optimizing grinding speed along with power consumption. For example, if the rotation speed is too high, the steel balls and other material in the 20 PSI mill will tend to be pushed outward by the centrifugal force with too much force. Consequently, steel balls and other material will not optimally fall back down upon reaching the upper portions of the 20 PSI mill in which they were spinning. On the other hand, if the rotation speed is too low, the steel balls and other material in the 20 PSI mill will not be lifted by the lifters 23 to the optimum height in the 20 PSI mill. Thus, the steel balls and other material generally do not reach the upper portions of the 20 PSI mill, from which they can gain potential energy useful for falling back onto the material below to be crushed.

[0054] In this embodiment, the feed hopper 5 and the feed tube 7 are supported on a cube-shaped frame 30. The feed hopper 5 and the feed tube 7 direct material into the interior of the mill 20 PSI through the circular feed opening 25A of the feed end diaphragm 22. The material to be ground can be loaded into the feed hopper 5 while rotating the cylinder 40 in continuous operation, since the feed tube 7, not fixed to the 20 PSI mill, is stationary with respect to the 20 PSI mill.

[0055] In this embodiment, each soundproofing panel is removably attached to a cube-shaped frame 20 to enclose the cylinder 40.

[0056] FIG. 5 is a top view of the SAG mill system 10 with a top soundproof panel 200B positioned to enclose components of the SAG mill system 10 within the frame 30. FIG. 6 is a vertical side view of the SAG mill system 10 with a side soundproof panel 200A , located in a position to enclose components of the SAG mill system 10 within the frame 30. FIG. 7 is a top cross-sectional view of the SAG mill system 10 along line C-C in FIG. 6.

[0057] In some embodiments, a soundproof panel is associated with the side of the cube frame 30 on which the motor 100 and chain 110 are located. The soundproof panel associated with the side of the cube frame 30 is not shown in the figures. This soundproof panel associated with the side of the cube-shaped frame 30 is configured to provide connection of the chain 110 to the cylinder 40 and the motor 100, and to accommodate a chain guard 112 extending outside the frame 30 to interact with the cylinder 40.

[0058] The soundproof panel 200B associated with the top of the SAG mill system 10 is adapted to the feed hopper opening 210, which is aligned with the feed hopper opening 5 inside the cube-shaped frame 30. This allows the user to feed material into the feed hopper 5 from the outside of the soundproof panel 200B. The soundproof panel 200B also includes a viewing window 220 with a cover 222. A handle is attached to the cover 222 to allow a user to manipulate the cover 222. The cover 222 is hinged to the soundproofing panel 200B to selectively close or open the viewing window 220. The viewing area 220 is axially aligned. with relief holes 29. The size of the inspection hole 220 allows the user, after stopping rotation, to pass the measuring rod through the inspection hole 220 and into the circular inspection hole 25B through the relief hole 29 in the cylinder 40. Thus, the height of the material inside the 20 PSI mill can be measured to confirm the quantity material inside the SAG mill.

[0059] It should be understood that making correct commercial particle size distribution predictions for a recycled material can be accomplished based on small-scale testing using the SAG mill system 10. No other SAG test in the world smaller than the 6-foot diameter SAG test mill can currently correctly predict the size distribution required for the design of auxiliary classification equipment in a new SAG mill circuit.

[0060] Although embodiments have been described with reference to the drawings, those skilled in the art will appreciate that variations and modifications may be made without departing from the spirit, scope and purpose of the invention as defined by the appended claims.

[0061] For example, while the described embodiments include a plurality of elevators with a grinding chamber drum, with each elevator depicted in the figures generally as a rectangle extending inwardly from the walls of the grinding chamber drum, alternatives are possible. For example, an alternative embodiment may include only one lift of this shape or one square lift, such as a 1.5-inch square lift.

Claims (21)

1. A continuous wet semi-autogenous (SAG) mill system comprising: - frame; - a rotating cylinder supported within a frame for rotation about a generally horizontal axis of rotation relative to the frame, the rotating cylinder including a plurality of discharge openings along its periphery and an internal helical paddle for picking up material within the rotating cylinder, which is located after the discharge openings, in in the opposite direction to the relief holes during rotation; - a variable speed drive system for driving the rotating cylinder around a generally horizontal axis of rotation; And - a SAG mill removably attached to the rotating cylinder in front of the relief holes, wherein the SAG mill contains: - a grinding chamber drum in a forward portion of the rotating cylinder, the grinding chamber drum having an internal diameter of about 19.2 inches and a length of about 6.4 inches, the grinding chamber drum including at least one internal lift; - a feed end diaphragm attached to the upstream end of the grinding chamber drum, the feed end diaphragm including a central feed opening sized to allow crushed material to pass into the grinding chamber drum; And - a discharge grid diaphragm, removably attached to the downstream end of the grinding chamber drum, wherein the discharge grid diaphragm includes a plurality of discharge slots, the size and position of each of which allows only material that has been crushed to a given size inside the chamber drum to pass through them grinding. 2. The continuous wet SAG mill system of claim 1, wherein the upstream end of the rotating cylinder comprises a peripheral cylinder flange to which the SAG mill feed end diaphragm is removably attached. 3. The continuous wet SAG mill system of claim 1, wherein the downstream end of the grinding chamber drum is enclosed by a discharge grate diaphragm, wherein the discharge grate diaphragm is removably bolted to the at least one internal lifter. 4. The continuous wet SAG mill system of claim 1, wherein the feed end diaphragm is welded to the upstream end of the grinding chamber drum. 5. The continuous wet SAG mill system of claim 1, wherein the frame is a cuboid frame. 6. The continuous wet SAG mill system of claim 1, wherein the at least one internal lift comprises a square shaped lift. 7. The continuous wet SAG mill system of claim 6, wherein the square shaped lifter has an area of 1.5 square inches. 8. The continuous wet SAG mill system of claim 1, wherein the at least one internal elevator comprises a plurality of rectangular elevators. 9. The continuous wet SAG mill system according to claim 1, further comprising: - an inlet pipe passing through the downstream end wall of the rotating cylinder to transfer fluid into the rotating cylinder. 10. The continuous wet SAG mill system of claim 1, wherein the discharge slots are located concentrically in the discharge grid diaphragm around a generally horizontal axis of rotation. 11. The continuous wet SAG mill system of claim 1, wherein the variable speed drive system comprises an electric motor and a circuit coupled to a rotating cylinder. 12. The continuous wet SAG mill system of claim 1, wherein the discharge grate diaphragm further includes a central control hole sized to accept a linear measuring rod extending from the outside of the rotating cylinder through the selected discharge hole, thereby measuring the height of the material inside the mill PSI. 13. The continuous wet SAG mill system of claim 12, wherein the central control hole is sized to allow excess material to exit the grinding chamber drum.