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Magnesium Oxide Depressants (5 replies)

Bill Rico
9 months ago
Bill Rico 9 months ago

Help me with best depressants that will effectively reduce magnesium oxide in sulphide nickel concentrates and effects of MgO in the nickel concentrates

Bill Fraser
9 months ago
Bill Fraser 9 months ago

I used guar gum depressant at Munali Nickel Mine. Not much help that I got as sometime the MgO would almost equal concentrate grade say 10% Ni with MgO at 8-9% when projected was supposed to be 5%MgO. Next time when the mine restart, I would want to explore CMC and any other depressant for MgO.

9 months ago
Unterstarm 9 months ago

If it were a talc issue then the known talc depressants, i.e. CMC and guar, are expected to give some success. However, for MgO bearing species like serpentine found in nickel sulphides (and I'm not sure what is present in your ore) then I recommend you consider alternate depressant chemistries, such as tri-block copolymers at considerably lower dose. There has been success with this type of reagent chemistry at BHP Billiton's nickel sites in Australia in the past, as well as in other ore types containing MgOs.

Rahil Khan
9 months ago
Rahil Khan 9 months ago

Keep in mind that there are several CMC types, they all work different. Remember to use DOEs (Design of Experiments) to test your reagents.

Ace Levy
9 months ago
Ace Levy 9 months ago

Have you tried some CMC? I am using it at a plant treating Great Dyke ore.

John Koenig
9 months ago
John Koenig 9 months ago

There are a number of things which taken together will lead to high MgO in a nickel concentrate.

•Locking and aggressive collector dosages.

•Mechanical entrainment in the froth and long flotation times especially with a low nickel feed grade.

•Decreasing the grind size to reduce locking will increase the contribution of mechanical entrainment, and vice versa. However, establishing the response with respect to grind size, if not already know, should indicate whether there could be some benefits in altering the grind size from the current target.

•Floatable silicates - either naturally hydrophobic (all sheet silicates like biotite and talc) or activated via transition metal ions (e.g. copper).

Frother selection impacts the contribution of floatable silicates to the MgO issue. A strong frother (e.g. a high molecular weight polypropylene glycol ester) will increase the flotation rates/ultimate recoveries of floatable silicates. A weak frother (e.g. the traditional MIBC), will do the opposite.

I would suggest some mineralogy on the nickel concentrate, optical for a quick look at the degree of locking and XRD for identification of the silicates. This will provide you with a starting point for investigations.

With respect to polymeric depressants (CMCs, dextrins, guar gums, starches), there are several types - with some more effective than others for a given silicate mineral.

If the issue is really solely with floatable silicates, and no collectors are added prior to the first rougher flotation cell, then exploring a reverse float approach to get rid of the silicates may be cost effective.

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