By ALFREDO P HERNANDEZ
THE Johson Gold Mining Corp does not use mercury to extract gold.
This was stressed by company vice-president Jason Marcelo as he reacted to a report in MWBuzz saying that the miner uses mercury in its gold operations.
In email sent to the online news website, Marcelo clarified that “JGMC does not use and never used mercury in its mining and processing operations”.
|A mining site operated by Johson. - Photo by chrisbegoode|
He said: “JGMC has a carbon-in-leach gold recovery plant.
“As part of legitimate operations and compliance to regulations, plant "tailings" or "slurry" is impounded in a controlled disposal site, designed by a geotechnical engineer, while also being regularly monitored and maintained by JGMC's technical team.
“In addition to that, there is consistent monitoring both from Mines and Geo Sciences Bureau (MGB) and Environmental Management Bureau (EMB), and of course regular monitoring of the host community barangay representatives,” said Marcelo.
According to mining website http://mine-engineer.com/mining/minproc/cilplt.htm, a carbon In leach gold recovery plant process million tons of ore every year with an average gold content of 0.043 ounces of gold per ton of ore.
“Approximately 85% of the gold is recovered in the plant.
“The crushed ore is fed to tanks of cyanide solution, where the gold is dissolved in the cyanide.
“The pregnant solution is then transferred to a series of tanks, where carbon is added.
“The gold is adsorbed onto the surface of the carbon. The carbon, with gold attached, is removed by screening.
“The gold bearing carbon is then introduced into a heated sodium hydroxide-cyanide-water solution where the gold is dissolved.
“This concentrated solution is passed through a series of electrowinning cells, where the gold quickly plates (in about three minutes) onto the stainless steel cathodes.
“The gold is washed from the cathodes, with high pressure sprays, dried and melted, to be poured into molds for gold bricks, or ingots.”
Cyanide is an “extremely poisonous salt of hydrocyanic acid”, according the online dictionary WordWeb.
Environmentalists have claimed that there is great risk that cyanide-treated solution used to extract gold could spill into the environment through faulty containment ponds, or when such ponds broke or leaked and released the cyanide solution onto lands and creeks, which the nearby community uses as source of water.
On its website, Johson said that there are tributaries around its mining camp which flow down onto the Mambulao Bay, which is just about a kilometer away from the mine camp.