| The growing characteristic of Thiobacillus ferrooxidans (T.f) was described by its redox behavior of Fe2+/Fe3+ and the electrochemical parameters of environment, the mechanism of the growing metabolism was studied in detail. Fe2+ was oxidized to Fe3+ by bacteria, and then a series of hydroxylation of Fe3+ occurs leading to poly-hydroxide, an ultimate jarosite ([NH4Fe3 (SO4) 2(OH) 6]) was formed, in which bacteria were growing cores. In the culture medium of 9K, the best growing conditions of T.f are pH=2~3.5, potential=400~800mV. During exponential growth, the potential is 500~750mV, the conductance is 8.2 X 103~4.5 X103 μΩ-1Three hypotheses were proposed according to the reaction of enzyme and the growth rule of T. f, on this base the differential coefficient and integral formulas of T. f growth velocity were deduced, in which Fe2+ is the restricted substrate. With optimization, the equation of T.f growth was analyzed in mathematics, the saturation constant (K), the max growth speed (μm) and the substrate concentration(5m) were obtained.To the pure mineral of chalcopyrite and bornite, the bioleaching research was carried out with original bacterial and domesticated bacterial. The effect of various factors on leaching, the catalysis of Ag+ to chalcopyrite and bomite and the catalysis of FeS2 to chalcopyrite were investigated. The domesticated bacterial can use the mineral as the energy substance more easily, so the sluggish time decreased, and the leaching rate was higher than that of original bacterial. The catalysis of FeS2 to chalcopyrite was remarkable and a theory of "electrochemical catalysis" was proposed.The bioleaching of low grade copper ore of Dexing Copper Mine, Dabaoshan Copper Mine was researched. At inoculation of 5%, slurry concentration of 10%, the bioleaching of Dexing low grade copper ore was ideal, copper extraction could reach 33.18% after 3 weeks leaching. To Dabaoshan copper ore, at slurry concentration of 10%, lixivium pH of 2.0, with the domesticated bacterial, copper extraction could reach 27.84% after 25 days leaching in sample 1#, in which low grade copper sulfide ore is the main component; in sample 2#, hypo-sulfide ore is the main component, copperABSTRACTextraction could reach 77.78% after 10 days leaching. The feasibility and effect of using some effective element of the tailing in flotation as the catalyzer for bioleaching were investigated.In 9K medium of inoculation or sterile controls, the chalcopyrite and pyrite electrode were studied by electrochemical techniques, such as cyclic voltammetry, Zeta potential scan, resistance of polarization etc. The corrosion characteristics and dynamics of electrochemistry were investigated; the dynamic parameters of the electrochemical process of anode were also determined.To the mineral electrode of chalcopyrite, the corrosion potential Eeon was 0.258V(vs.SCE), corrosion current 7corT was 0.52 A cm"2 and the resistance of polarization Rp was!8.28KQ in sterile controls; while inoculation, corr and /corr were 0.308V and 0.64 y A cm'2 respectively, P=16.16K . In both circumstance, the spot corrosion potentials E were the same as 0.633V, however the spot corrosion current of inoculation is 0.5mA, which is 10 times of that on sterile controls. The anode Tafel slopes were almost the same as 59.62m and 59.2 ImV respectively, but the Tafel slopes of cathode process increased from 23.96mV to 33.60mV while change sterile controls to inoculation. The results show that T.f have remarkable effect on the dissolution of chalcopyrite.To the mineral electrode of pyrite, Corr was 0.258V, C0rr was 0.52 u A -cm"2 and Rp was54.36KQ in sterile controls; while inoculation, corr and /C0rr were 0.308V and 0.64 u A ?cm"2 respectively, P=5.6K.Q. In both circumstance, b were the same as 0.704V, however 7b of inoculation is 0.58mA, which is higher than that on sterile controls, 0.49mA. The anode Tafel slopes were almost the same as 60.47mV and 59.42mV respectively, but the Tafel slopes of cathode process increased from 23.07mV to 31.53mV while cha...
|
PDF Full Text Request