Dear Ronny, the mats of ...

Dear Ronny, the mats of floating plants are basically made for assimilating organic waste and depleting fecal bacteria. To a limited extent there should be an effect on cyanides in low concentrations (which are used for gold lixiviation) - but there is NO sanitating effect on mercury: To the contrary, this might be converted from salts to organic Hg compounds, which are much more toxic to humans and animal models than inorganic Hg compounds.

Other compounds, like heavy metals and semi-metals like arsenic, as they frequently occur with the gold on primary deposits (in "veins"), are partially mobilized, partially precipitated and retained by plants. In higher concentrations they can damage the mats by killing the plants (for instance, if they contain copper). To assess mobilization/precipitation, there have to be studies about suitable pH / Eh ranges and their changes induced by the activity of the floating plants. Only then, mobilizing and precipitating effects can be inferred for every metal in discussion.

The wastewater from coal mines may contain sulphates (from oxidized pyrite and other sulphides occurring in the coal beds) and possibly heavy metals. Most likely the plants have a limit for SO4 tolerance. Regarding the heavy metals, the above mentioned conditions apply.

Finally... diamonds and granite: AFAIK no toxic compounds are used for processing despites fuels and lubricants... and, to a small extent, grease to separate diamonds from their matrix on vibrating tables. All of these do not seem to harm the plants in the concentrations that are typical for wastewater, and for the typical compounds of mineral oil (aliphatic and aromatic hydrocarbons) as well as glycerol esters, which are main component of fat, the plants might improve their natural decay (which is to be proved or falsified by other studies that possibly are offered by the manufacturer - but have to be tested on site).

Sorry to make it more complicated: Maybe there's already an application case elsewhere in the world, which could supply experience?

Best regards, F. Helms