SIBX in Copper, Gold and Base-Metal Flotation

Sodium isobutyl xanthate (SIBX, CAS 25306-75-6) is one of the most widely used sulphide collectors. Its C4 chain gives a strong collecting power with reasonable selectivity, which is why it appears in copper, lead-zinc, nickel and gold circuits around the world. This page covers where SIBX is used, how it is applied, and how much is typically needed.

1. What SIBX is

Property	Value
Name	Sodium isobutyl xanthate (SIBX)
CAS number	25306-75-6
Chain length	C4 (isobutyl)
Character	Strong collector, reasonably selective – a good all-round sulphide collector
Typical form	Pale-yellow to yellow solid / granules

Xanthates make target sulphide minerals hydrophobic so they attach to air bubbles and float. Chain length sets the balance: shorter chains (SEX, SIPX) are more selective and weaker; longer chains (PAX) are stronger and less selective. SIBX sits in the middle – strong enough for most sulphide ores, selective enough for many separations.

2. Where SIBX is used

Target mineral	Typical circuit	Role of SIBX
Chalcopyrite (CuFeS₂)	Porphyry and copper sulphide ores	Primary collector for copper flotation
Galena (PbS)	Lead-zinc ores	Collector for the lead flotation stage
Sphalerite (ZnS)	Zinc circuits	Collector after activation; zinc depressed in the lead stage
Gold-bearing sulphides	Gold and gold-copper ores	Collector to float the gold-bearing sulphide
Pentlandite (Ni)	Nickel sulphide ores	Collector in bulk nickel flotation
Silver / polymetallic	Complex ores	Collector within a staged reagent scheme

3. Typical reagent schemes

Ore	Typical scheme
Copper sulphide	SIBX collector + frother (e.g. MIBC) + lime for pH; often a rougher-scavenger-cleaner arrangement
Lead-zinc	SIBX for lead flotation with zinc depression (typically zinc sulphate, sometimes with other depressants); then activate and float zinc
Gold / gold-copper	SIBX (or a SIBX/SIPX blend) to float the sulphide host; collector level set by the sulphide content
Nickel sulphide	SIBX with controlled pH and non-selective conditions to maximise nickel recovery

Dosage and pH are ore-specific. Always screen the collector (and its combination with frother and modifiers) in laboratory flotation tests before a plant trial.

4. Dosage

Stage	Typical dosage (starting point)
Rougher	Higher addition to maximise recovery
Scavenger	Added to recover the remaining sulphide
Cleaner	Lower addition (or a more selective collector) to improve concentrate grade
Overall	Commonly about 10 – 100 g per tonne of ore, set by the ore and circuit

SIBX is usually added as a solution (made up on site) to the conditioning tank or the grinding circuit, at a controlled pH and with enough residence time for adsorption.

5. Practical notes

Staged addition. Split the collector between rougher and scavenger to balance recovery and selectivity.
pH control. Lime is commonly used to set the pH; it affects both the collector and the mineral surfaces.
Degradation. Xanthates decompose with moisture, heat and time – make up solutions fresh and use stock within its shelf life.
Blending. SIBX is often blended with SIPX or PAX to fine-tune the recovery/selectivity balance.
Water quality. Hard or contaminated process water can consume collector; watch the dosage response.

6. Choosing between SIBX and other xanthates

SIBX is the general-purpose choice. Use SIPX (more selective) where a cleaner concentrate matters; use PAX (stronger) where recovery is the priority. See the SIBX vs SIPX vs PAX comparison and the xanthate selection chart for the decision tables.

Frequently Asked Questions

What is SIBX used for?

As a sulphide collector in copper, lead-zinc, nickel and gold flotation circuits – a strong, reasonably selective general-purpose collector.

How much SIBX is used?

Commonly about 10-100 g/t, split between rougher, scavenger and cleaner stages; the dose is ore-specific and set by flotation testing.

Is SIBX or SIPX better for copper?

SIBX is stronger for recovery; SIPX is more selective for a cleaner concentrate. Many plants use one in the rougher and the other in the cleaner – confirm on the ore.

How is SIBX added?

Usually as a freshly made-up solution to the conditioning tank or grinding circuit, at controlled pH with adequate residence time.