Normally HMS - or heavy media separation is used as a pre-concentration step on the front end of lead/zinc concentrators to reject lower grade gangue and feed. Mt Isa in Australia uses this type of circuit. Have not seen it done on the tails end of the process!

Thanks for your consideration, sure we use it as you said, but we lose much amount of zn/pb in cyclone overflow, feed grade approx. 8% and gangue side is 6%(80%feed weight). Any little change in media density ruins process.

Please elaborate the problem. I work with lead zinc flotation maybe I could help.

We use HMC for pre-concentrate zn/pb for years and the result was satisfying because we deal with gangue mineral grain density 2.65 (2-15mm) and zn/pb density 2.9, but recent years since mine grade output decreased (gangue unchanged but zn/pb grains 2.75) we can’t get result as well as those years. my question is that, is it possible at all by modifying this system we can overcome this problem using for example more precise control system for density or switching to new cyclone design? Or that cyclone doesn't answer and we should seek new alternative like kelsey jig which operate over finer fraction.

You can improve your process with hydrocyclone D5 to D15, like a example, we are concentrating CuOx (malaquite) on underflow, from 1.0- 2.0 to 2.0 to 4.0, after that we send this slurry to flotation process.

Can anyone help me regarding "COAL WASHABILITY USING FLOTATION TREE ANALYSIS"

Till now no one tried HMS separation for the reasons-

Minerals are interlocked. Gets liberated at 75 micron. HMS is not possible at 75 u.

Wt% of minerals is too small as compared to tailing. Hence Sp. Gr. difference is too sharp between concentrates and tailing.

Even pre-concentration concepts do not work as tailing losses will be heavy and not economical.

Send more details on con. % grade, tailing % grade etc.

Surely you have a good experience regarding this issue, four things:

•No 2 is, I think, the most important problem because as I said we can’t recover the intermediate particles which have near Sg to the tails particles.

•Cyc's are not capable to work with 75micron fraction of ore at all. And for this reason we have to pre-stage dry and wet screening.

•Feed 6% Zn+pb, concentrate 18%, tail 5% and there for recovery rate approx 15%.

•For low recovery which comes back to sharp Sg difference we are searching new technology ore any modification which can improve the system capability.

Did you check your mineralography of your ore sample?

Maybe the interlocked minerals of your ore are your problem! As you know The DMS system is highly dependent on the degree of liberation and differentiation of SG of your minerals. Could you describe your HMC system during operation to continue our discussion in a right track?

Why we cannot follow normal flotation after wet grinding to 75 micron and then think of arsenic separation.

Please tell me the following points.

•What is the mesh of grind that is required for the healthy degree of liberation?

•What is the gangue minerals associated?

•What are the phases of the minerals of Pb & Zn?

Answers to these questions may help towards the conclusion of the problem. Without achieving the optimum degree of liberation any beneficiation operation may not work.

Before doing a flow sheet one needs to study the ore for type of minerals present, their liberation sizes and liberated particle properties. As per their Individual particle properties and combined particle properties the unit operation and unit process are made and then arranged in logical sequence in the form of flow sheet. This is followed by capital equipment sizing and detail engineering and layout preparation. This is in general.

HMS Cyclones works when there is difference in SG of particle but Their Ep values are assured after discarding some base size of particle. I have used Multotec DMC in coal.

If the particles are liberated and HMS is not giving results then you can try Spiral concentrators at least for high density pb particle. I have used Multotec spiral concentrators for hematite and found effective up to 30-33 micron separation from alumina, silica and gangue. The feed sample is considered for trough angle after simulation.

If your ore is Pb-Zn in sulphide form then grind it to the optimum liberation size and ensure that the particle below 10 micron should be minimum and float by using MIBC or cresylic acid (Frother)/PEX or SIPX (Collectors) /Lime (pH Modulator)/Cuso4 (Activator)chemical. You can use tank cellsor u bottom and residence time/ volume of the cells depends on test works run. You can opt for Conventional or bulk flotation depending upon your consumer.

If your ore is having pyrite or pyrhotite you can use High gradient magnetic separators at final stage also.

These are the few you can play around after studying your ore.

We can’t use flotation because the ore is carbonate and there isn't any effective way regarding this issue. Any industrial flotation practice about znco3 (we didn’t find,) if available, can help us.

If multotec spiral really can work over micron's fraction I am eager to hear about this system capability. While more liberation would improve density differences between pb/zn and gangue mineral grains, but any more liberating (minus 1 mm) is not acceptable in

HMC (our system). Gangue grains Sg is 2.7 and Zn/Pb locked with gangue grains is 2.85. sure more grinding would change this Sg's and will be useful but this technology (HMC) can’t work and I think need some more precise and effective system like gravity system's which utilize jige and eccentricity systems together.

•2-15 mm, but more grinding would cause problem in separation.

•Si02, CaCo3, CaMgCo3,

•Znco3, Pbco3, interlocked with XXCo3 and little Sio2