The 2019 Raven trenches covered an area of over 800 m2 and returned multiple scorodite
, bismuth and siderite related sulphide vein exposures throughout the trenches.
The main mechanism of arsenic removal with FC was a chemisorption process, involving the formation of inner-sphere surface complexes and low-solubility minerals (scorodite
As discussed later, the presence of the weathered, oxidized form of arsenopyrite (FeAsS) known as scorodite
(FeAsO4<<2H2O), is critical to understanding local copper arsenic alloy production.
Sorbed As and scorodite
are common As species in soil environments and often result from the oxidation of As ore materials such as realgar or arsenopyrite.
Using extended x-ray absorption fine structure spectroscopy, the research team was able to identify that the arsenic was contained in the mineral scorodite
, an iron arsenate.
Just one example will do: under Scorodite
in the mineral listing we read of the specimens found in the Pingtouling mine, Guangdong Province, but the photo at hand shows a scorodite
from the newer discovery at Hezhou, Guangxi, and is captioned as such, though the text does not mention the Hezhou occurrence.
The commercially practiced processes for chemical fixation of arsenic includes the precipitation of calcium arsenite or arsenate, arsenic sulfide ([As.sub.2][S.sub.3]) arsenical ferrihydrite and crystalline scorodite
. Among them, the scorodite
process has been widely accepted as currently the most suitable method for stabilization of arsenic in terms of its high arsenic content, low TCLP arsenic solubility and environmental stability, if disposed appropriately.
The quartz veins hosting this mineralization are commonly banded with scorodite
and arsenopyrite and range in width from 10 to 30 centimeters.
This suggests that a reaction between aqueous Cu(II) and arsenopyrite occurs in the tailings, resulting in the precipitation of a Cu sulphide along the boundary according to the following simplified reaction (scorodite
represents the Fe-As-O coating):