Mechanism of the Removal of Arsenic in Limonite and Accelerating Material for Arsenic Removal.
Some consideration on the mechanism of removal of arsenic in limonite was made. Based on this mechanism some accelerating materials for arsenic removal were chosen and following results were obtained.
(1) The mechanism of arsenic in limonite was as follows,
This reaction was accelerated from right to left according to temperature rising. When CO existed in atmosphere, the reaction of arsenic removal was as follows,
The reaction rate of equation (2) was faster than equation (1). From upper two equations, the hindering effect of O2 and CO2 on the arsenic removal reaction was understood.
(2) The effect of accelerating materials for arsenic removal in limonite was tested in a laboratory.
In this case, coke, coal, pyrite, FeCO3 and FeCl2 were chosen as accelerating material in consideration of arsenic-removal mechanism.
The results were as follows.
a) Coke and coal were effective for accelerating arsenic removal and coke was more effective than coal.
b) Pyrite was also effective for accelerating arsenic-removal in some cases.
c) FeCO3, MnCO3 and FeCl2 were not effective for arsenic removal.