Introduction Rod Mill Used as the primary comminution unit in a grinding circuit. Rods are placed parallel along the length of the rod mill. Rods are 150mm shorter than the mill length. Breakage occurs more from cascading than cateracting. The product size distribution is narrower than a ball mill but significantly coarser.
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Expert Answer 100% (1 rating) Transcribed image text: Problem 2 A two stage grinding circuit using a rod mill in open circuit with a ball mill in closed circuit with a rake classifier is used to grind 40 tons per hour of ore (sp. gr. ).
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Rod mills are used in an open circuit between crushing and the ball mill. They often operate in wet and where the pulp contains up to 50% solid by mass. This machine is equally very applicable to dry where it could take a feed that has achieved 6% moisture. As such, when the product is sticky, rod mills are preferred over ball mills.
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The rod mill product is characterized by its narrow size distribution if it is compared with that of a ball mill operating under the same conditions in open circuit. This is partly due to the bridging action of the rods over the coarse particles avoiding the fine sizes (the grinding kinetics aspect), and partly due to the nature of material ...
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The next two examples are for rod mill ball mill circuits. Figure 2 shows a conventional rod millball mill circuit. The data for this circuit and Wi0 calculations are: Rod mill size x (′ x 16′ diameter inside shell ′ ′ rods) Ball mill size x (″ x 16′ diameter inside shell ′)
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Because of this, the rod mill can effectively reduce 1″ feed size to 10 mesh or finer in open circuit. The voids (or interstitial space) within a rod load are approximately half those in a ball mill grinding load. Rods in place weigh approximately 400 pounds per cu. ft. and balls in place approximately 300 pounds per cu. ft..
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The primary Rod Mill in open circuit will reduce crushed ore to approximately minus 10 mesh. A Mineral Jig is recommended if coarse mineral and metallics are present. The spiral or rake classifier overflow passes to the unit cell and on to classification and regrinding. High grade unit cell concentrates can be produced with this system, and on ...
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Open circuit grinding consists of one or more grinding mills, either parallel or in series, that discharges a final ground product without classification equipment and no return of coarse discharge back to the mill. Some very simplistic examples of open circuit grinding are see below and are made of a Rod mill, Ball Mill or a Rod mill, ball ...
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When finer material is required, a ball mill is used in a closed circuit. . A rod mill in an open circuit may be followed by a ball mill in a closed circuit. Patterson Industries ContinuousType Ball Pebble Mills. Open Circuit Operations . Closed Circuit Systems . Complete the Ball and Pebble Mill Specification Sheet and submit by e ...
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Multiple stages may include a rod mill followed by a ball mill (two stage circuit), or a semiautogenous grinding (SAG) mill followed by a ball mill (two stage circuit). Smaller plants tend to add extra crushing stages in order to operate a single grinding stage only. If a ball mill uses little or no water during grinding, it is a 'dry' mill.
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dard Circuit, assume m diameter overflow mills, and use a rod mill F80 of 16,000 µm and a rod mill P80 of 1,000 µm. Note that—in order for no correction factor for ball mill product fineness to apply—the ball mill circuit P80 should be no less than approximately 70 µm (Bond, 1962). This
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Consider a grinding circuit, consisting of a rod mill in open circuit and a ball mill in closed circuit with a hydrocyclone, as in Figure 1. (a) Imagine that, as part of a survey of the above circuit, samples were taken of the rod mill and ball mill discharges and of the cyclone underflow and overflow, and that sieve analyses of composite samples of these products gave the following results ...
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The Work Index values listed in Table I and II apply directly to a wet grinding overflow type rod mill feet in diameter in open circuit; and to a wet grinding overflow type ball mill feet in diameter in closed circuit with a rake classifier at 250% circulating load, and with 80% or more of the feed passing 4 mesh. ...
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open circuit SAG mill, 2. closed circuit ball mill. The Australian experience of milling lateritic ore is to use a highaspect ratio mill at the initial stages of operation using a singlestage circuit. With time, as the hardness of the ore increases with depth in the mine, a secondstage ball mill is added.
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The grinding media in these mills are rock pebbles of suitable size (3″ to 6″) screened out of the intermediate crushing circuit. c. Secondary autogenous mills (or secondary pebble mills) which process a coarse ground product. (4 to 14 mesh; or, finer) obtained from rod mills or from primary or intermediate autogenous mills.
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Autogenous mills range up to 12 meters in diameter. The lengthtodiameter ratios in the previous table are for normal applications. For primary grinding, the ratio could vary between 1:1and :1. For fine regrinding in open circuit, the ratio ranges from :1 to :1. Some ball mills are separated in to compartments by grates.
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It depends on the rod mill work index and on the desired product size. It will also depend on if you are grinding open or closed circuit and wet or dry. And if you have any stages of grinding, crushing, or classification before it! It will generally be between 10 mm and 50 mm. Sandeep Bisht.
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The crushed ore after automatic sampling is subjected to twostage grinding using a Rod Mill in open circuit and a Ball Mill in closed circuit with a Classifier. The Unit Flotation Cell receives the discharge from the ball mill for recovery of a substantial amount of the granular silver minerals together with galena as soon as freed. Reagents ...
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Closed circuit crushing is recommended for single stage grinding as there is greater control over size of feed going to the one ball mill. Open circuit crushing is advantageous when using twostage grinding due to the ability of the rod mill to handle an oversize feed product.
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The presence of "fines" in open circuit rod mill feed has long been recognized as an important factor for both stable and efficient mill operation. Although addition of extra fines to rod mill feed was common practice in the past, few details have been reported. The fortunate exception is the experience at Frood Stobie.
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Separator efficiency is defined as specific power consumption reduction of the mill opentoclosedcircuit with the actual separator, compared with specific power consumption reduction of the mill opentoclosedcircuit with an ideal separator. ... Ball and Rod Mills. JeanPaul Duroudier, in Size Reduction of Divided Solids, 2016. ...
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Grinding and Flotation. Fine ore at minus 19mm (¾") sizing is fed at a controlled rate into the opencircuit 2600mm x 3960mm (8'6 x 13'0) Hardinge rod mill at an average feed rate of 2,106 STPD or STRH. Rod mill discharge at a nominal size of minus 16 mesh and a pulp density of 75 percent solids combines with ball mill discharge ...
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The crushing is open circuit,, there is no recycle loop. The two grinding circuits are closed circuit,, oversize material is recycled for recrushing or regrinding to specified particle sizes. ... These can be rod mills which are suitable for relatively coarse grinding, and ball mills which are practically capable of grinding down to ...
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Author links open overlay panel Deniz Altun a, Carsten Gerold b, Hakan Benzer a, Okay Altun a, Namık Aydogan a. Show more. Add to Mendeley. ... At the end of the study, the VRM performance was compared with rodball mill circuit of the copper plant, of which the ore was tested, in terms of specific energy consumption and wear rate. 2.
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Example: A mill in closed circuit with a classifier receives 300 dry tons of crude ore per day, and the percentages of solid are respectively 25, 50, and 84% in the classifier overflow, feed to classifier, and sand, equivalent to L: S ratios of,, and Then the circulating load ratio equals
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Several experiments were performed on a continuous rod milling circuit. Two flowsheets arrangements were considered to produce the particles with size <500 µm: an open circuit and a closed one.
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