Inhibition Of Biological Oxidation In Metal Sulfide Mine Tailings

Eosinophilic oxidizing bacteria will greatly accelerate the natural weathering of sulfide minerals, releasing a large number of toxic heavy metals, acid mine drainage (referred to as AMD), and a large number of H⁺, all of these will have very serious hazards on the surrounding Ecological environment.Studies showed that: acidophilic bacterium, represented by Acidithiobacillus ferrooxidans, played an important role in the process of minerals decomposition. This study isolated two strains Z1, Z2 from polymetallic sulfide mine tailings of Dabaoshan in Guangdong. The identification of the growth characteristics and 16SrDNA showed two strains had 99% similarity to standard strain ATCC23270, the two strains are both Acidithiobacillus ferrooxidans. Domestication confirmed strain Z1 had better Adaptability than strain Z2 in sulfide mine tailings pulp.The inhibition of Fe²⁺ oxidation was analyzed by adding different doses of two different bactericides into the solution of purified Acidithiobacillus ferroxidans(As the strain Z1 to experimental strain). The effects of two bactericides, sodium dodecyl sulfonate (referred to as SDS) and cetyltrimethylammonium bromide (referred to as CTAB) in inhibition of Acidithiobacillus ferroxidans in mineral tailings, were researched. The results showed that: experiments with bactericides SDS and CTAB could effectively inhibit the biological oxidation of metal sulphide tailings and acidification: whenρ(SDS) was 30 mg/L, the inhibition rate of Fe²⁺ oxidation was 82.83%; whenρ(CTAB) was 5 mg/L ,the inhibition rate of Fe²⁺ oxidation was 80.84%, pH, Eh in the solution added the bactericides were remained, so the use of bactericides can inhibit the growth of Acidithiobacillus ferrooxidans, the oxidation of Fe²⁺ oxidation and acid production. In view of the special role of Acidithiobacillus ferrooxidans in the process of weathering and oxidation of sulfide tailings, sterilization can be as an effective way to controll acidification and pollution of metal sulfide tailings.Bactericides used for control of bio-oxidation of tailings has been a precedent, but the sulfide tailings are greatly piled up to store open. In the wild, because of the existence of the objective conditions, sunshine and rain, Bactericides are easy to invalidation and lose. In this paper, a sustained release bactericides pills was preparated by driping.The results of SEM IR and Element analysis show that: SDS can be effectively dispersed evenly in the skeleton of the CA (cellulose acetate) sustained-release pills; the rate of drug is more than 40%; the dissolution of SDS is persistent in the acidic solution,ρ(SDS) of the solution increased gradually. But the pills with CTAB has the lower rate of 8.42%, it's so little.As the same to pills with SDS, CTAB pills has steady releasing characteristics.The result of bioleaching (pyrite) showed that: pH, Eh and heavy metal dissolution rates in the solution with SDS pills were very different from the blank: pH and Eh were stable in the treatment, but variable in the blank,ρ(Zn2+) and total Fe were lower than the blank. While the new and old tailings tailings also reflects the similar results, pH, Eh did not change significantly in the solution with SDS pills, and the dissolution of metal ions have also been significantly limited.Above all, this study explore an effective way to prepared an sustained-release pills which is able to inhibit the growth of Acidithiobacillus ferrooxidans, a long-term control of sulfide Tailings bio-oxidation can be achieved.