Thiobacillus Ferrooxidans And Thiobacillus Thiooxidans Combined Leaching Thallium Ore Tailings And The Toxicity Evaluation Of Leaching Solution

Thallium as a dispersed element,exiting in the environment with the same kind of matter as the sulphide minerals, and rarely forms a separate Thallium mineral. The Thallium mine of Guizhou Xingren Lanmuchang is independent Thallium deposit in domestic rare. In the 19 th century 40 to 50 years, excessive mining of this area csused tailings produced, which had caused the serious society and the environment question because the tailings effected by biogeochemical interactions in the open-air storage process caused toxic and harmful substances of tailings into the environmen, and became the first typical area of natural Thallium poisoning.This study based on Guizhou Lanmuchang Thallium Ore Tailings, demesticaed Thiobacillus ferrooxidans and Thiobacillus thiooxidans which had been isolated dan purified from acid mine drainage by our laboratory with Thallium tailings. Seting the different ratios of mixed bacteria, Thiobacillus ferrooxidans different adding time,different energy material and pulp concentration so that study on the effects of microorganism on the leaching of heavy metals Tl from tailings of Thallium mine.The tailings were characterized by scanning electron microscope sem. Experimental study on seed germination of Chinese cabbage seeds with the leaching liquid which diluted into different concentrations, and then evaluating the toxicity effect of leaching fluid on Chinese cabbage through texting the effect of physiological and biochemical characteristics of Chinese Cabbage seeding.The main conclusions of this paper are described in the following:?1?Thallium ore tailings of Lanmuchang Thallium mining area contains many heavy metals, such as Fe, Tl, As, Cu, Cd, Cr, Zn, and the contents are19310.00 mg/kg,20.70 mg/kg, 143.80 mg/kg, 12.70 mg/kg, 15.64 mg/kg, 197.40 mg/kg, 19.88 mg/kg.Analyzing the tailings by SEM-EDX,the composition of the material elements of the surface of Thallium ore tailings is C, Si, O, Fe, S, Al, etc.,in which the content of Si element is the highest, andall kinds of element existing in the form of mutual binding.Analyze the tailings by XRD, the mainly mineral compose of Thallium ore tailings are quartz?SiO₂?, Dickite 2M1?Al₂Si₂O₅?OH?₄?, Anatase?TiO₂?, Monteponite?CdO?,Tennantite(Cu₁₂As_3.40 Sb_.60S₁₃)etc.?2?The leaching effect of Tl of the Thallium ore tailings was best when the ratio of Thiobacillus ferrooxidans and Thiobacillus thiooxidans was 1:7, initial pH of the culture medium was 2.0, Thiobacillus ferrooxidans adding time was 6 d and concen--tration of the slurry was 6%,.?3?Thiobacillus ferrooxidans and Thiobacillus thiooxidans could promote the dissolution of Tl from Thallium tailings, and the leaching effect of mixed bacteria was the best, the Thiobacillus ferrooxidans was the second and the Thiobacillus thio--oxidans was the third.The leaching rate of different bacterias was: mixed bacteria16.93%, Thiobacillus ferrooxidans 16.26%, Thiobacillus thiooxidans 9.7%. Com--paring sterile experimental group, the dissolution of Tl from the Thallium ore tailings had varying degrees of increase, the increase rate was:the mixed bacteria 347%,Thiobacillus ferrooxidans 330%, Thiobacillus thiooxidans 157%.Comparing the two experimental groups of single bacteria, the leching rate of Tl of the mixed bacteria was higer, and the increase rate was:4.1% higher than Thiobacillus ferrooxidans,74.5% higher than Thiobacillus thiooxidans.?4?The leaching solution of Thallium ore tailings had toxic effects of the Chinese cabbage. The presence of microorganisms can promote the dissolution of heavy metal ions from the Thallium ore tailings, and then increased the toxic effects of the Chinese cabbage. With the growth of the concentration of leaching solution, the influence of the leaching solution on the physiological and biochemical characteristics of Chinese cabbage was firstly promoting and then inhibiting. The cabbage growth was entirely inhibited when leaching solution concentration was 100%?leaching solution?;at the concentration of 10%, the enzyme activity of SOD of the experimental group was highest. Compared with the experimental group of CK leaching solution, the chlorophyll a, b and Carotenoid like of the other experimental group of adding bacteria was first increased and then decreased trend, and the maximum value appeared when the leaching solution concentration was 2%, at the same time, the maximum value of the experimental group of CK leaching solution appeared in 10%.Under the same leaching solution concentration, the root of cabbage was more sensitive than the stem and the toxicity effects of the leaching solution on the root was more than the stem; under the same dilution ratio, the toxicity effects of CK leaching solution on the cabbage was smaller than that of the adding bacteria.