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What's a ball-mill ball made out of?

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  • What's a ball-mill ball made out of?

    A customer brought me a big steel ball, about 5-1/4" in diameter (and nowhere near perfectly spherical) that he says came out of a ball-mill at one of the gold mines.

    He wanted to know what it was- I speculated it could be anything from mild steel to chilled cast iron- and wanted to know if I could drill it for a project he has in mind.

    A quick touch to the grinder gave me a short spray of bright yellow sparks with the telltale bursts of carbon. A file would cut it, but it was definitely tougher than mild. Drilling it, however, was a nonstarter- literally. I couldn't even mark it.

    I managed to drill it a bit with a carbide drill, but when I tried a regular drill in the same hole, to see if it had a work-hardened skin, the HSS drill still couldn't cut it.

    What are these things typically made from? And can it be annealed?

    Doc.
    Doc's Machine. (Probably not what you expect.)

  • #2
    I can look up what the balls from coal grinders are made of... specifically B&W ones.

    Would that help?

    Give me a rough age of the ball so I can check the appropriate book.
    "The Administration does not support blowing up planets." --- Finally some SENSIBLE policy from the Gov!

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    • #3
      The balls used in aluminum paste mills are Rockwell 60C case hardened, they behaved like bearing balls. The ones I'm familiar with are about 2" diameter.

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      • #4
        Originally posted by Grind Bastard
        Give me a rough age of the ball so I can check the appropriate book.
        -Probably within the last ten years.

        The balls used in aluminum paste mills are Rockwell 60C case hardened[...]
        -Supposedly these started out closer to 8" in diameter. This one's a used cast-off. If it was case hardened, that hardening is long gone. It could be work hardened though, I didn't drill in too far.

        Doc.
        Doc's Machine. (Probably not what you expect.)

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        • #5
          "...are made from a specialized steel alloy and heat-treated for maximum durability and hardness."

          Well bugger that I checked two of my 25 copies of Steam: Generation And Use and that's what they say.

          Now the RACEWAYS that the balls ride in are made out of cast iron, and it goes into details about that.

          This may require a bit more digging, I thought it spelled out what the balls were.

          Hunh.

          (BTW: Huge fan of your strip, Doc. It's on my morning read list. )
          "The Administration does not support blowing up planets." --- Finally some SENSIBLE policy from the Gov!

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          • #6
            GOT IT

            ELVERITE C cast steel.
            "The Administration does not support blowing up planets." --- Finally some SENSIBLE policy from the Gov!

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            • #7
              I'll take a wild ass guess at a maganease steel. This is very tough stiff used in abrasive environments, eath moving equiment, mining equpmentm mixer drums and furnature, rail switches, etc where the material is actually handled.

              Most GP steels have lower manganese content 0.3% to 0.6% but low carbon abrasion resistant manganese steel has an elevate manganese conten running around 1.5% at relatively low carbon. The stuff is very tough and work-hardening.

              Probably impossible to drill but it welds pretty good and forges great. What's the hole for? Eyebolts? Weld a hasp on it using 308 stainless filler.
              Last edited by Forrest Addy; 12-28-2011, 06:51 PM.

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              • #8
                Originally posted by Forrest Addy
                I'll take a wild ass guess at a maganease steel. This is very tough stiff used in abrasive environments, eath moving equiment, mining equpmentm mixer drums and furnature, rail switches, etc where the material is actually handled.

                That's what I was thinking too, the description of the sparks from grinding sounds right and so does what it's used for. Usually the way to check for Manganese steel is with a magnet and that will probably work here too but on work hardened Manganese the surface is sometimes magnetic. Check a bunch of different spots on this thing and if some seem only slightly magnetic or not at all then the mystery should be solved.



                BTW, if it is work hardened Manganese then drilling a hole in it would be a good way to learn new cuss words!

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                • #9
                  I have experience with balls from the copper mines and power plants where they are used on coal.
                  Neither is manganese steel. They are readily handled with a magnet.
                  I don't think they are anything special. I'm not sure what grind bastard means by raceways but a ball mill is a large cylinder that rotates. It is lined with an abrasion resistant material such as manganese steel. It rotates, tumbling the balls and the material to be pulverised. As the balls wear they are replenished with new ones so that there is a wide range of sizes. The feedstock is pulverised to the consistency of flour. The balls are consumable. It is much easier to replace balls than liners, therefore they are soft until work hardened.

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                  • #10
                    Originally posted by Doc Nickel
                    Supposedly these started out closer to 8" in diameter. This one's a used cast-off.
                    FYI, you can find giant bearing balls, NOS, on Ebay, which are hardened 52100. They would take a LONG time to wear out. I've seen as large as 5" in diamater -- not sure about 8"
                    "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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                    • #11
                      Originally posted by lazlo
                      FYI, you can find giant bearing balls, NOS, on Ebay, which are hardened 52100. They would take a LONG time to wear out. I've seen as large as 5" in diamater -- not sure about 8"
                      No body cares how long the balls last. As I said there is a mix of sizes in the mill. Time to add 2 tons of balls: About 4 man hours, including lock/tagout, forklift to bring them, everything.
                      Time to reline the mill, peryphery only : well over a thousand.
                      Last edited by tdmidget; 12-29-2011, 02:42 PM.

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                      • #12
                        Manganese steel,shows up in a lot of places and most of it is work hardening.

                        However did you try a sharpened up masonry drill?
                        I just need one more tool,just one!

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                        • #13
                          Originally posted by tdmidget
                          I have experience with balls from the copper mines and power plants where they are used on coal.
                          Neither is manganese steel. They are readily handled with a magnet.
                          I don't think they are anything special. I'm not sure what grind bastard means by raceways but a ball mill is a large cylinder that rotates. It is lined with an abrasion resistant material such as manganese steel. It rotates, tumbling the balls and the material to be pulverised. As the balls wear they are replenished with new ones so that there is a wide range of sizes. The feedstock is pulverised to the consistency of flour. The balls are consumable. It is much easier to replace balls than liners, therefore they are soft until work hardened.
                          Ball-and-race type pulverizer. Slightly different operating principle.

                          http://www.answers.com/topic/ball-an...ype-pulverizer

                          Best I can do, I'm in a hurry... got a hot date.
                          "The Administration does not support blowing up planets." --- Finally some SENSIBLE policy from the Gov!

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