Study On Microbial Leaching Of Low-grade Phosphate Or

The total amount of phosphate rock resources in China is rich,but the average grade is low.Compared with traditional mineral processing methods,microbial beneficiation has the advantages of small environmental pollution,simple operation,large scale industrial leaching,and low energy consumption,and is widely used.However,in the current application of microbial leaching,the commonly used bacteria is medium-temperature bacteria.Although its leaching efficiency of low-grade phosphate ore has been greatly improved compared with the traditional mineral processing method,it is vulnerable to the influence of external conditions such as leaching temperature and pulp concentration.Therefore,it is necessary to select a strain with better temperature tolerance and higher phosphorus leaching efficiency.This paper compares the leaching effect of thiobacillus ferrooxidans,acid pit water bacteria,dilute sulfuric acid and thermophilic sulfur rod-shaped bacteria on silicon-calcareous phosphate rock with grade of13.17% in Wengfu,Guizhou,and finds that the thermophilic sulfur rod-shaped bacteria has the best leaching effect.The growth and leaching of bacteria in pit water with pyrite and sulfur as nutrients were studied.Through setting different leaching time,initial p H,leaching system temperature,shaking table speed,pulp concentration of temperature-sensitive sulfur acid rod bacteria single factor leaching test,determine the more significant factors,design orthogonal experiment to optimize the leaching conditions;And by measuring the Zeta potential and FTIR of thermophilic sulfur rod-shaped bacteria,collophanite and dolomite,the leaching mechanism was studied in order to determine a method with higher phosphorus leaching efficiency.The research results are as follows:(1)The composition,structure,structure and disseminated grain size characteristics of wengfu phosphate ore were studied.The main ore minerals in this sample are collophanite and fluorapatite,and gangue minerals are dolomite,quartz and chalcedony.It is mainly stratified structure;Collophanite is amorphous colloidal and powdery,with particle size below 0.01 mm.(2)The growth curves of bacteria in pit water,thiobacillus ferrooxidans and thiobacillus heviticus rod-like bacteria were measured.It was found that they entered logarithmic growth phase after culture for 20 h,40h and50 h,respectively.The bacteria activity was the highest and leaching efficiency was the best in this period.(3)Pyrite and sulfur were used as nutrients for leaching phosphorus by bacteria in mine water,respectively.It was found that both of them could be used as energy materials for bacteria in mine water,and the final leaching rate of phosphorus reached 39.06% and 37.78%,respectively.(4)The pit water bacteria,thiobacillus ferrooxidans and thiobacillus hethermophilus rodeus were acclimated with gradiations of 0.2g,0.4g,0.6g and 0.8g,respectively,in order to adapt to the leaching environment and improve the leaching rate of phosphorus.(5)Bacterial acid leaching effect of phosphorus is evident due to dilute sulfuric acid.Under the condition of 30℃ and 160r/min constant temperature shaking speed for 12 days,the phosphorus leaching rate of bacteria in mine water reached 42% and that of thiobacillus ferrooxidans was about 38%.When the initial p H value of dilute sulfuric acid is 1.0,the phosphorus leaching rate is 6.2%.When the initial p H value is 3.5,the phosphorus leaching rate is only 2.2%.(6)The most important factor affecting the phosphate leaching by temperature-sensitive sulfur rod-shaped bacteria is the pulp concentration,followed by the temperature,the leaching time,and the rotation speed of the shaking table has the least influence on the phosphorus concentration in the system.Under the optimum condition of orthogonal experiment,the leaching rate is 92.15%.(7)By measuring Zeta potential and infrared spectrum of mineral surface before and after microbial adsorption,we can understand the surface properties of bacteria,and better explain the mode and intensity of interaction between thermophilic sulfur rod-like bacteria and ore bodies.