Froth Flotation (Sulphide & Oxide)

Froth Flotation (Sulphide & Oxide)

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Lead Zinc Manganese concentrate separation (4 replies)

6 years ago
Fantom 6 years ago

How, by flotation, would you separate sulphide rock with 8% Pb, 9% Zn, 0.3% Cu, and 3.5% Mn? Do you think it would be possible to produce 4 different and clean (penalty free) concentrates? Any possibility to make a manganese, a zinc, a lead and copper concentrate any smelter/refinery will buy?

6 years ago
Jorge 6 years ago
1 like by David

If lead, zinc and copper are sulphides, the logical process is to produce a Pb-Cu bulk concentrate, and tails from the Pb-Cu flotation circuit feed the zinc flotation circuit. In this case, the lead content is much higher than copper content, then it would be necessary to depress lead and float copper. Usually, lead and copper requires cleaning to get an acceptable concentrate grade. In this way, it is possible to get three concentrates.

The presence of manganese could be problem is the mineralogical specimen is alabandite (manganese sulphide). The presence of manganese oxide (rhodonite, rhodochrosite, psilomelane) would not be a problem.

If there is alabandite, the Pb-Cu bulk concentrate can content high levels of manganese. The testing program should be focused on manganese depression. It is difficult to get a decent manganese concentrate. Manganese is a poison for a Pb-Zn flotation process. You should perform a mineralogical study to determine the presence of manganese minerals.

6 years ago
David 6 years ago

Hello Fantom,

further to what Jorge said, I would comment that because you have so little copper, you might not be able to effectively/profitably separate the Pb from the Cu with incurring large Pb loses.

You may therefore just treat this as a Pb/Zn ore in which to just go after the Pb and Zn sequentially.

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6 years ago
Silverbus 6 years ago

Viability of Zinc mine with Zinc concentrate composition?
Is there an industry standard cut-off of zinc concentrate to manganese%?

Roughly what percentage of manganese in the zinc ore makes it undesirable/unsaleable due to it's likelihood of clogging tanks, lowering recovery and causing downtime?

I understand that the market and price partially depends on the smelter and other available ores that can be blended to remove the Mn effect on the zinc electrowinning cell feed.

Specifically, viability of a mine for this ore composition: Zinc concentrate which grades 56.3 zinc, 0.3 lead, 144 grams per ton silver and 1.3% manganese a desirable/preferred product, a marginal product or is it unsaleable?

6 years ago
David 6 years ago

Hello Mr. Silverbus and welcome to 911Metallurgist,

This seems to be the topic of the week. I have seen enough about it already! Am so glad I stopped investing in mining and now stick with cheese only

Here is what I know from being a metallurgist and always working as maximise the mining companies profitability (generally metal recovery) while minimising smelter penalties and always avoid rejection. Am not a concentrate marketer. Here is what I know of the cat & mouse game concentrate marketing and metal trading is. 

Now, 56% Zn, 0.3% Pb, 144 g/t Ag is good stuff. Zn & Ag are above, while Pb is below average numbers. The manganese in the zinc concentrate is saleable/marketable under 1.5% Mn. You must negotiate, find multiple buyers and eat penalties of course, but it is saleable. Penalties is a smelter's breakfast.

There are 1% Mn zinc concentrates being sold around the world today. Sold with penalties, yes.

The original Broken Hill deposit, located in far western New South Wales operated for 120 years producing Zinc concentrate with 1% Mn in it. Broken Hill is considered to be among the largest and highest grade base metal deposits ever found. The "BH" in the world's largest mining company, BHP Billiton, refers to "Broken Hill" and its early operations in the city. The BH deposit made BHP what it is now.

For high Manganese:
Look at at some 3% I think.

For low manganese in a zinc concentrate:
Look at at what? Zero?

Magically (3% + 0%) /2 = 1.5% - See how dilution can be the solution to pollution 🙂

There are worse things than Mn in a Zn concentrate: Cd, MgO, SiO2, Se, just to name a few. I actually don't know of a zinc concentrate over 50% Zn that is not being sold. Most get penalized, but always sold. Penalties are as necessary as they are profitable. Without penalties, miners would produce all kinds of off-spec material and the smelting process would not be able to operate. Penalties do keep miners inline and guide/maintain a steady feed quality for smelting.

No Zn conc is perfect. Smelters ALWAYS find something to penalize concentrates for, ALWAYS. This is how the make money. 

Even a 1.3% Mn can be attractive to smelters if it has no other impurities in it. A smelter will seek a zinc conc with low selenium, cadmium, or/and low magnesium, or/and low silica even if it has above average Mn in it. It allows them to buy somebody else's zinc conc with high "contaminants" and fleece them for those contaminants while they fleece/overcharge the Mn rich concentrate for its Mn. At the end, the smelter overcharged both zinc producers with penalties and treatment charges/fees TCTs in knowing full well their process can take "the average" of minor elements. Too much of this, not enough of that says the smelter. Penalties are not frivolous charges as they help cover extra cost the removal of the element causes. The value/amount of a given penalty can sometimes however be 'discretionary' depending on market conditions. That's the business. Smelters will cry and penalise miners all the way to the bank.

Some concentrates are sought after because they are coarse grain. They are preferred because the rest of world is getting finer. Coarser produces less dust and processes better. A 100 microns concentrate will be preferred over one containing the same deleterious elements if at 30 microns. Yet, the 100 micron does not receive a premium price nor is the 30 micron penalised. Coarse is just more marketable than finer.

Concentrate marketing is a complex business (read the footer PDFs).

Can the world absorb a zinc concentrate containing 1.3% Mn? My math say yes.

If we say the annual world mine production of zinc is 13,000,000 ton/yr of metal and that metal came from 55% Zn concentrates. This means 13M/0.55 = 24,000,000 tons is the annual mine zinc concentrate output.

Let' us assume that 24M tons contains 0.35 %Mn and let us assume your 1.3% Mn comes into 500,000 tons/yr of zinc conc. The math is: (24M x 0.35 + 0.5M x 1.3)/(24+0.5) = 0.37% Mn as your new world average. Am sure you know under 0.5% is a non issue.

World mine supply 0.35% Mn without your conc VS 0.37% with your conc. I fail to see the drama.

Not every smelter will be a buyer of this stuff I suppose, but again, we don't know. Maybe competing high-Mn zinc conc have other deleterious elements your zinc concentrate does not contain or maybe it is coarser than others.

Smelters will never tell you the whole story, never tell you the hand they hold. That is part of the poker game negotiations.

Can the world take a zinc with 3% Mn as is? A zinc with 4% Mn as is? Sometimes, if the reserves are large and rich enough yes, they carry the cost of solutions to be developed.

This is why some miners will integrate and build their own smelters/refinery. Hudbay, Cominco(Teck), Vedanta, Noranda(Glencore), Mount Isa Mines (Glencore) just to name what comes to me now. Zinc mining can be a tough business!  Look at this selling all of its mines, but keeping all smelters...

Manganese in zinc concentrate is an issue but Dugald River in Australia will make a zinc concentrate at 2-4% Mn as will Gamsberg in South Africa. The appropriate marketing strategy is to “smear it around” to multiple zinc plants so they can keep below the 0.3-0.5% Mn limit for feed zinc concentrate.

But again, I am not a marketing expert.

My job is not to sell the +1.5% Mn stuff, it is to keep the Mn out of the Zn or have it just low enough for it to be sold and lower it some more if doing it is cheaper than paying penalties for not doing it.

My view is 1.3% Mn is a speed bump but not a roadblock. 

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