Luženje teških metala iz flotacione jalovine

Abstract

Luženje teških metala iz flotacione jalovine ispitivano je pod prirodno atmosfersko – klimatskim uslovima sa aspekta uticaja na životnu okolinu. U tom smislu je određena distribucija i sadržaj jona teških metala u starom flotacijskom jalovištu iz uzoraka jezgara istražnih bušotina do dubine od 20m, dejstvo prirodno prisutnih oksidanasa i uticaja pH vrednosti rastvora na stepen izluživanja teških metala iz flotacijske jalovine kao i distribucija i sadržaj jona teških metala u okolnom zemljištu i biljkama. Za određivanje stepena izluživanja teških metala formiranoje paralelno šest različitih serija eksperimenta sa 0.01M H2SO4, sa i bez dodavanja oksidansa (H2O2 i O2), sa i bez prethodnog ispiranja uzoraka destilisanom vodom. Prethodno ispiranje uzoraka vršenoje u cilju uklanjanja lako rastvornih elemenata iz uzoraka i utvrđivanja razlike u daljem rastvaranju teških metala u odnosu na eksperimente bez prethodnog ispiranja uzoraka. Tokom eksperimenata je praćena pH vrednost rastvora i koncentracije Cu, Fe, Zn, Pb, As, i Mn u funkciji vremena. Rezultati eksperimentalnih istraživanja pokazali su da je dominantni sulfidni mineral pirit sa masenim učešćem od 21.57 %, dok kumulativno učešće jalovih minerala, koje predstavljaju kvarc, silikati i karbonati, iznosi 77 %. Prosečna oslobođenost pirita iznosi 90.9 %, što u prisustvu vode i atmosferskog kiseonika predstavlja veliki reaktivni potencijal za mobilizaciju jona teških metala. Ovaj mineral predstavlja i jedan od osnovnih uzroka povećane kiselosti jalovine sa pH vrednostima između 2.25 i 4.22. Raspoloživost kiseonika i atmosferskih voda glavni su razlozi za najveći stepen samoizluživanja sulfida tokom perioda odstojavanja jalovine u površinskim slojevima, pa je stoga i njihov sadržaj na površini najniži. Stepen oksidacije sulfida i mobilizacija jona teških metala u dubljim slojevima jalovišta daleko su niži zbog manje raspoloživosti kiseonika i rastvora pa je samim tim i njihov sadržaj znatno viši. Međutim,upravo ti minerali predstavljaju „gorivo“ za dugotrajnu kontaminaciju drenažnih voda jer se njihova mobilizacija odvija veoma sporo ali kontinualno.

Leaching of heavy metals from flotation tailings was studied under natural atmospheric- climate conditions in terms of impact on the environment. In that sense was determined the distribution and the content of heavy metal ions in the old flotation tailing samples from exploratory holes cores to a depth of 20m, the effect of oxidants naturally present and the pH value of the solution on the degree of leaching of heavy metals from the tailings as well as the distribution and content of heavy metal ions the surrounding soil and plants. To determine the degree of leaching of heavy metals were formed parallel the six different series of experiments with 0.01M H2SO4, with and without addition of oxidants (H2O2 and O2), with and without pre-rinsing of the samples with distilled water. Pre-rinsing of the samples was performed in order to remove easily soluble elements from the samples and determine the differences in the further dissolution of heavy metals in relation to the experiments without pre-rinsing the samples. During the experiments was monitored pH value of the solution and the concentration of Cu, Fe, Zn, Pb, As, and Mn in a function of time. The results of experimental studies have shown that the dominant sulphide mineral is a pyrite with mass participation of 21.57%, while the cumulative share of barren minerals, which are quartz, silicates and carbonates, is 77%. Average liberation of the pyrite is 90.9%, which in the presence of water and atmospheric oxygen present important reactive potential for mobilization of heavy metal ions. This mineral is also one of the main causes of the increased acidity of tailings with pH values between2.25 and4.22. The availability of oxygen and atmospheric waters are the main reasons for the highest level of sulphide minerals self-leaching during time in the surface layers, which makes their content the lowest at the surface. The oxidation of sulphides and mobilization of heavy metal ions in the deeper layers of the tailings are much lower due to less availability of oxygen and so the solution thus their content is considerably higher. However, it is these minerals actually represent the "fuel" for long-term contamination of drainage waters because their mobilization occurs very slowly but continuously.