I am separating minerals (zircon, apatite etc.) and look for new devices. Does anybody have experience with these machines?
Fritsch Disk Mill Pulverisette
Retsch Disc Mill DM 200 or DM 400
Retsch Jaw Crusher BB 50
I am particularly interested in pressure and shearing action of these machines. Can mineral grains get destroyed due to the shearing deformation in the disk mill?
What is the minimal (average) grain-size of the Retsch BB 50 Jaw Crusher? Can this can be used instead of disk mill to crush rocks and separate mineral grains afterwards?
Thank you for sharing your experience!
Hello Petra,
here is Linda! Hope you can recall me from LMU!
Here at UWA we are doing the mineral separation using the disk mill, I need to check if the brand is one of the 2 that you are wondering about!
hope you and your family are good!
ciao!
Hi Linda, wonderful to hear from you!!! This is great to discuss it with you. What do you think about the shearing mechanism due to the rotation of the discs? Can this destroy the grains? How is the milling procedure at UWA? Do you mill the sample down to the small fraction in several steps or just one?
Hi Petra Vesela
I am using RETSH VIBRATORY DISC MILL RS200 for Zircon, Apatite or heavy mineal separation, pulverising rock for XRF, etc and I have separated enough mineral grain.
The standard grain size for Zircon and Apatite separation is 200 Micron. From my experience it usually take 1-2 minute at 600rpm to grind at said size on igneous i.e. hard rock (grinding time is directly proportional to amount of sample and hardness). I expect less time for sedimentary rocks
Hi Shyasmson,
thank you very much for your experience. This is surprising! Do you grind the sample in one step? I thought that two or three are necessary to reduce the grainsize and not to break the grains. I still did not buy the machine, but it will be most propably such disc mill, Retsch or Fritsch.
It takes a lots of step to separate grain.
First you might need Jaw crusher to reduce its size to few mm
Secondly you need to put the rock chip to pulverise in Retsh vibrator mill (its not possible to grind it in one go, so you have to seive it in 200micron and again grind the larger grain untill all the sample pass through the 200 micron seive.
After that u can proceed to next step
Dear Stephanie, this sounds interesting, that the elongated zircon grains do not break! I have never tried it, because we use min. 3-4 kg large samples and they are all metamorphic "hard rocks". I would probably need days to crush it to proper grain size!? How large are your samples and how consolidated are they? Do you have a procedure sheet which decribe your separation techniques? I like to learn tricks!
Dear Stephanie,
thank you very much for the links and sharing your expertise and fotos - great!!! I´ll pass them to my student assistants. We are now trying panning and it works great with sedimentary zircon rich samples. But still, most of the samples are going this way: crushing - wilfley water table - Frantz - heavy mineral separation - and hand picking. Why we do Frantz already after Wilfley? Probably because we mostely have pretty much material. But it would be worth to check weather it is faster to swich these steps. Frantz needs sometimes a day/1 sample!!!
Dear Petra,
I can certainly help you a lot with the Retsch Mills. Please define first the initial particle size and the required fineness of you samples. How much sample do you have to mill?
Best regards, Tanja
Hi Tanja, sorry for the late response.
We use up to 25 kg hard rock sample, but average sample is 6 kg, chopped down to several cm. We work with particles in the range between 60 and 300 microns.
Petra
The BB 50 accepts pices up to 4 cm, ths might fit. You can certainly crush minerals down to more than 1 mm, with a gap width setting of zero maybe yoi´ll receive fine particles around 0.5-1 mm. This always depends on the sample material. You see that with a Jaw Crusher you will not recieve fine particles < 300 µm. This can be done in a Disc Mill, but this mill only accepts feed size particles up to 2 cm.
How do you seperate the particles afterwads? This is not clear for me. But if your goal is to crush particles down to 300 µm, you can use the BB 50 first (or larger crushers accepting even bigger initial particles) and in a second step for example the disc mill. Anyhow, I suppose for the fine crushing a Vibratory Disk Mill RS 200 could do the job quicker. Unfortunately there´s not Mill, which can accept bigger particles of several cm and cann crush so fine in only one step. You need two mills!
Please let me know if this was helpful. Maybe you can just send us a sample and we will see what the best solution in your case is. this is for free and you`ll get a much better idea afterwards ,-)
Thank you - yes this sounds feasible! We habe a "Backenbrecher" as a first mill and than a "Walzenmühle". I am thinking about a new mill, a disc mill - and I am wondering if there is experience with the two brands... The rest must solve my chief - she pays :-)
Ok, which Backenbrecher do you alredy have? As one of ours can be directly connected to the Disk Mill DM 400. So you have got a good solution for pre-and fine-crushing.
Anyhow, to be absulutely clear, you should send some testing material (also to other suppliers if you like) and compare ,-)
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