Papers by Keyword: Bioheapleaching

Abstract: The Zijinshan bioheapleaching plant started operating at the end of 2005. During four years of leaching operation, concern about migration of acidophiles from the heap into the nearby Ting river has arisen. A total of 44 soil samples, 49 water samples and 15 air samples were collected surround the heap at different spatial scales, and the quantitative distribution of acidophile around Zijinshan bioheap was studied. Chemical characteristics of the samples such as pH, copper content and iron content were analyzed. Real-time PCR assay was used to qualify acidophiles, included genus Acidithiobacillus, Leptospirillum, Ferroplasma and Sulfobacillus in all samples. The results showed that the four acidophiles displayed different biogeographic patterns. Geographic distance did not have a biogeographical effect on the experimental spatial scale for the genus Acidithiobacillus, Leptospirillum and Sulfobacillus. However, the geographic distance was a significant factor for genus Ferroplasma. The water soluble copper and iron concentrations of soil samples had crucial relevance for the existence of acidophiles. No significant variation was found among all the water samples regarding the concentation of acidophiles. The concentration of copper in the river met China National water quality II standard. These results indicated that: a) the dispersal of acidophiles from the heap may not be significant b) the adverse impact from the heap on the local environmental may not be significant.

Abstract: The distribution and diversity of bacterial community in Zijinshan commercial non-aeration copper bioheapleaching system operated at pH 0.8 for three years were investigated. The 24 meters high heap was cut off by mechanical digger. On the trapezoidal cross-section of the heap, 9 ore samples were taken from different vertical and horizontal locations and investigated by 16S rRNA gene clone library. Another 3 liquid samples from raffinate solution pond, spray solution pond and pregnant solution pond were also applied to 16S rRNA gene clone library analysis. The retrieved 1166 clone sequences from 12 samples were mainly related to genus Acidithiobacillus (42.36%), genus Leptospirillum (37.73%) and genus Sulfobacillus (6.52%). Relative high amount of heterotrophic bacteria were distributed at the ore surface in the internal part of the heap and in the liquid samples respectively. The retrieved heterotrophic bacterial sequences were mainly related to genus Acidiphilium (accounting 11.11% to 32.00% percent in the liquid samples), genus Acidovorax (accounting 12.37% in A1 sample), genus Pelomonas (accounting 4.17% to 10.31% in several ore samples) and genus Aquabacterium (accounting 10.31% in C2 sample). Bacterial diversity in the heap was increased from the surfcae layer to the interior of the heap. The proportion of genus Leptospirillum horizontally increased from the inner to the outer part while vertically decreased from lower depth (2-3 years leaching time) to higher depth(3-6 month leaching time), and reverse correlation of genus Acidithiobacillus was found in the heap. Our finding indicated that heterotrophic bacteria may play very important roles in the commercial bioheapleaching system, and revealed high distribution of genus Leptospirillum in the outer part of this non-aerated heap.

Abstract: Talvivaara complex multi-metal black schist deposit in Sotkamo, Finland, is the largest known sulfide nickel deposit in Europe with 340 million ton of classified resources. The mine can be operated for a minimum of 25 years with an annual nickel output of over 30 000 ton, which is about 2,5 % of the global production of primary nickel. Significant amounts of zinc, copper and cobalt can also be produced. In summer 2005, a 50 000 ton demonstration plant was constructed to the mine site. A representative ore sample was mined, crushed to 80 % -8 mm, agglomerated and built to a two-part heap (8 m high, 50m times 80 m). Irrigation of the heap was started in August 2005. The pilot heap was inoculated with indigenous bacteria collected from the site. The amount of bacteria in the pregnant leaching solution has been in the range of 106 – 108 cells/ml. The bacteria involved are mesophilic and thermophilic ones. The start-up of the solution flow resulted soon in elevated temperatures of over 50 0C in the pregnant leaching solution. The rise is due to the oxidation of the large quantity of pyrrhotite and pyrite in the ore. The elevated temperatures have also been maintained over the boreal winter conditions. Metal recovery was started in November 2005. At the end of the year 2006 94 % of Ni, 83 % of Zn, 3 % of Cu and 14 % of Co have been recovered. The demonstration plant is still running. The study has proven that Talvivaara black schist ore is well suited for bioheapleaching. Building of the mine will start in spring 2007, bioheapleaching in summer 2008 and the metal recovery plant in autumn 2008, if everything proceeds according to the plans.