Study On Bioleaching Of Low-grade Phosphate Ores

Phosphors were important raw material of industry and agriculture,although the total amounts of phosphate ore were plentiful,but the average grade was very low. The economic effectiveness was very poor when adopt tradition technique process low grade phosphate ore,on the contrary,the bioleaching technique have overwhelming advantages such like small pollution,less energy consumption,low cost of operation etc.all these cast new lights on exploiting and using low grade phosphate ore.Acidithiobacillus thiooxidans(At.t) and Acidithiobacillusferrooxidans(At.f) which were been widely use in biological hydrometallurgy were be adopted in this study.At.t and At.f were spperate from the acid drainage of a coal mine in Anhui province,after they be enriched and purfied a long time,the produce acide ability were been test on different substrate original pH value and differemt energy materals. At.t was found have stronger produce acid ability when the sbustrate original pH value was 2.35 and sulfur as the energy source in Starkey substrate.When the substrate original pH value was 3.01 and pyrite as energy source the At.f produce more acide in 9K sbustrate.Ultraviolet irradiation and Microwave inducement were applied to the bacterial cultivation process to produce At.t and At.f able to generate more acide.As a result: At.t generate acid capacity were be enhanced after induced by Ultraviolet irradiation and Microwave,especiallly when Microwave induced 10 second(MW 10 s) and Ultraviolet irradiation induced 5 minute(UV 5 min),the lowest pH value of the substrate were 1.45 and 1.52.When Mivrowave was applied to induce At.f 10 s,their generate acide capacity also improved,the lowest pH value of substrate were 1.82. At.f induced by Ultravioled irradiation had unconspicuous change on their generate acide capacity.The experiment of low grade phosphate ore leached by At.t and At.f indicated the phosphorus leached rate increased with the leached time in general.The mutagenesis with stronge generate acide capacity had more leached rate than the original bacterium during the same period.UV 5rain At.t leached rate can reach 39.14%,MW 10 s At.f phosphate leached rate was 38.12%,the original At.t and At.f correspond leached rate were 30.12%and 28.13%.The phosphate leached rate can improve by the addition of suitable kinds and quaintity of Tween series surfactant,At.t leached rate was increased to 41.12%when 0.001%(v/v) Tween 60 was added,At.f leached rate was increased to 38.25%when 0.001%(v/v) Tween 80 was added.The corresponded mutagenesis leahed rate only improved a little when Tween series surfactant was added.In order to find out the reasons affect the At.t and At.f phospate leached rate,the zeta potential and FTIR test were carried out.The IEP were smaller than the original At.t when they were induced cultivating by ultraviolet irradiation.The same change happened to At.f when they induced by microwave 10 s.The At.f grown with pryite has higher IEP than At.f grown with FeSO₄.The sulfur and pyrite particles IEP will increase with interaction times when they interacted with corresponding At.t and At.f The IEP of sulfur particles also increase when interatced with At.t in presence of Tween 60.The FTIR study on At.t and At.f cells surface substances shown that the chemical function group or the vibration mode of group had been changed,these means the hydrogen bond action changed on the surface,they maybe was the main reason cause the mutagenes surface characteristic changed.The reasonable interpretation to At.t and At.f leaching posphate ore and genetate acide experiment reuslts can be found out from the synthetically analyzed the results of zeta potential and FTIR experiments.