Abstract:
The chemical and biochemical oxidation of arsenopyrite caused the release of arsenic toenvironment. In this work, we studied the inhibition arsenopyrite oxidation by coating withsodium silicate. In the experiment, 0.001M Na2Si03 *9H20 at pH 1, 3, 5 and 7 was used tocoat on the particles (size < 300 nm) of arsenopyrite mineral. We chose pH at pH 3 and 5 asappropriate condition for the coating since the amount of iron and arsenic detected in solutionwas less than other condition (less than Fe conc. < 0.02 ppm, As conc. < 0.05 ppm) Arsenopyriteparticles coated with 0.001M Na2Si03 *9H20 at pH 3 and 5 were subjected to test for thesurface resistance to chemical oxidation by 0.145M H202 at pH 2,4 and 5. It was found surfacecoating at pH 3 resisted to chemical oxidation better that of coating at pH 5. In the microbialadsorption experiment on arsenopyrite coated and uncoated surfaces using Thiobacillusferrooxidans, it demonstrated that there was some difference in the number adsorbed cells. Sincethe adsorption followed the Langmuir adsorption isotherm, therefore we could analyze themaximum adsorption capacity (XAM) of the particle surface. It was found XAM for the coated anduncoated arsenopyrite surface was 4.710x 10กำลัง9 and 7.231 x 10กำลัง9 cellslg of FeAsS respectively. Sowe concluded that coated sodium silicate suppressed the adsorption of Thiobacillusferrooxidans.