Elements

Sodium cyanide's most common and well-known use is in the processing of gold ore. The NaCN solution is mixed with the ore, enabling low levels of gold to be retrieved. The gold can be recovered in two different ways:

 

Tank leaching: the gold ore is mixed with the cyanide solution in large tanks. Once the gold is dissolved, the used cyanide solution and leftover ore are carted off to tailings storage facilities (NICNAS 2013).

 

Heap leaching: the cyanide solution is poured onto a heap of crushed gold ore. The cyanide seeps to the bottom, dissolving gold along the way. The solution now containing dissolved gold settles at the bottom of the heap, and can be removed (NICNAS 2013).

 

The dissolution of gold is triggered by the presence of atmospheric oxygen (this is where NaCN's deliquiscence plays a role) and the reaction produces sodium cyanoaurite and sodium hydroxide (Tamura 2002):

 

4Au + 8NaCN + 2H2O + O2 → 4NaAu(CN)2 + 2NaOH

 

 

Unfortunately, sodium cyanide can be used as a chemical weapon. Upon reacting with moisture or acid, sodium cyanide produces deadly hydrogen cyanide (HCN) gas. Any sodium cyanide exposed to air will produce HCN, so it can be deadly even on its own. HCN is an extremely toxic gas and is an asphxiant that interferes with the body's ability to use oxygen (CDC 2003). In other words, it targets the bloodstream. Symptoms can be seen as early as seconds after inhalation; death may occur within minutes.

        Cyanides react with and bind to hemoglobin in the red blood cells faster than oxygen does. Oxygen needs the hemoglobin as a carrier to reach cells (in order for cellular respiration to occur). As a result of the cyanide reacting with the hemoglobin before oxygen can do so, oxygen is not able to reach the cells, resulting in cell mortality. Early symptoms of cyanide poisoning include headaches, confusion, shortness of breath, and anxiety. Severe cyanide poisonings progress to muscle spasms, comas, and death. 

 

Chemical Weaponry