MBT in Mineral Flotation

2-Mercaptobenzothiazole (MBT, CAS 149-30-4) is not only a rubber accelerator – it is also a well-established flotation collector. Its thiol group adsorbs on sulphide surfaces, and it is used where xanthates alone struggle, especially in the flotation of oxidised and partly oxidised ores. This article covers where MBT is used as a collector, how it compares with xanthates, and how it is applied.

1. Why MBT works as a collector

The thiol (-SH) group in MBT bonds to metal ions on mineral surfaces, making the surface hydrophobic so it attaches to air bubbles and floats. Because the same chemistry works on copper, lead and zinc sulphides – and, after sulphidisation, on their oxidised forms – MBT is a versatile collector.

2. Where MBT is used

Application	Why MBT
Oxidised copper ores (after sulphidisation)	Collects sulphidised copper minerals that respond poorly to xanthate alone
Sulphide copper, lead and zinc ores	Thiol group adsorbs on sulphide surfaces
Mixed / complex ores	Used with xanthates or as an alternative collector to improve recovery
Precious-metal bearing sulphides	Contributes to sulphide recovery in some circuits

3. MBT vs xanthates

Collector	Type	Strengths	Notes
Xanthates (SIBX, SIPX, PAX, SEX)	Thiol collectors	Fast, low cost, very widely used on sulphide ores	Weaker on oxidised minerals
MBT	Thiazole thiol collector	Effective on sulphidised oxidised ores and some complex sulphides	Higher cost per tonne; used where it adds recovery
Dithiophosphates / thionocarbamates	Other thiol collectors	Selectivity alternatives	Circuit-specific

The two families are often used together: a bulk xanthate for the main sulphide recovery, with MBT added where the ore carries oxidised or difficult minerals.

4. How MBT is applied

Parameter	Typical practice
Dosage	Set by ore testing (commonly tens to a few hundred g/t)
Addition	Conditioning tank or grinding circuit, usually as a solution or emulsion
pH	Circuit-specific; often alkaline with lime
With sulphidisation	For oxide ores, sulphidise first (for example with NaHS/Na₂S), then float with MBT
Solubility	Low in water; usually added as a solution in alkali or as an emulsion, or dry to the mill

MBT has low water solubility, so how it is added matters: many plants dissolve it in alkaline solution or add it as a fine emulsion or dry feed. Confirm the addition method with your reagent engineer.

5. Circuit practice

Lab first. Collector dosage and the sulphidisation regime are ore-specific – screen them in flotation tests before a plant trial.
Stage the addition. Add to conditioning with enough time and mixing for adsorption.
Watch the froth. A thiol collector changes froth character; adjust frother and circuit accordingly.
Combine. MBT often works best as part of a collector suite, not alone.

6. Handling and supply

Skin sensitizer. MBT is classified as a skin sensitizer – use gloves and dust control in reagent make-up.
Aquatic toxicity. Prevent release to water; manage reagent spillage and tailings properly.
Packaging. 25 kg bags and 1000 kg jumbo bags, with per-batch COA and SDS.

Frequently Asked Questions

Is MBT used as a flotation collector?

Yes. Its thiol group adsorbs on sulphide minerals, and it is used in sulphide flotation and in the sulphidised flotation of oxidised ores where xanthates are less effective.

How does MBT compare with xanthate?

Xanthates are faster, cheaper and the first choice for most sulphide ores; MBT adds recovery on oxidised and complex minerals and is often used alongside xanthates rather than instead of them.

What dosage of MBT is used in flotation?

It is ore-specific – screen it in the laboratory. Typical additions run from tens to a few hundred grams per tonne.

How is MBT added to a flotation circuit?

Usually to conditioning or the grinding circuit, as an alkaline solution, an emulsion, or occasionally as dry feed, because of its low water solubility.