Table 1.

Comparison of conventional gold leaching technologies.

Immersion systems	Oxidants	Complexing agents	Advantages	Disadvantages
Cyanidation	O2	CN-	Simple process, high yield, remarkable economic benefit, large-scale industrial production.	Slow, no anti-interference, extremely toxic, harmful to environment and human health.
Thiosulfate	O2, Cu(NH3)42+	S2O32-	Rapid, high yield, strong anti-interference, slight equipment corrosion.	Large reagents consumption, complex gold recovery process.
Thiourea	Fe3+, H2O2	SC(NH2)2	Rapid, high yield, strong anti-interference, preliminary industrialization.	Poor stability, large consumption, strong corrosiveness, high cost.
Chlorine	Cl2, NaClO	Cl-	High yield, cheap and readily available reagents.	Strong toxicity, easy to leak, poor security, strong corrosiveness
Bromine	Br2	Br-	Rapid, cheap, good adaptability.	Volatile, difficult to transport.
Iodine–iodide	I3-	I-	Non-toxic, rapid, high yield, eco-friendly.	High cost, poor industrial application, harsh conditions.
Polysulfide	Sx2-	Sx2-, S2O32-	Cheap, non-toxic, rapid.	Subsequent process is not perfect.
NBS (in this paper)	Br2, Br·	Br-	Less dosage, mild, rapid, high yield, eco-friendly.	Under laboratory stage, unverified by industry.