| Due to the complicated mineral composition,high content of alkaline gangues and mud,complex intergrowth,the complex oxidized copper ore is typically hard to process.The research of high efficient processing technology for complex oxidized copper ore is significant,which will improve the copper resource utilization and alleviate the contradiction between supply and demand of copper resource in our country.To solve the problems in processing complex oxidized copper ore,such as excessive acid consumption in acid leaching,easily jammed,inapplicability of bioleaching with autotrophic acid bacteria,complex process and high cost in ammonia leaching,the researches were carried out with focuses on breeding of alkalophilic bacteria and bioleaching behavior of complex oxidized copper ore.The methods involved in this work included field sampling,laboratory test and mechanism analysis.The work could be summarized as follows:(1)A heterotrophic alkalophilic ammonia-producing strain was obtained.The alkalophilic bacteria were isolated from soil sample,morphological characteristics of bacterial colony and cells were investigated,the bacteria was identified and named as Providencia sp.JAT-1.The growth and metabolism mechanism of bacteria was studied and the optimal growth conditions was determined as follows:sodium citrate 10 g/L,urea 20 g/L,temperature 30 ℃,initial pH 8,inoculum size 20%and shaking rate 180 rpm.(2)The acclimatization and mutation of leaching bacteria was conducted.The inhibition effect of ore pulp on growth and metabolism of bacteria JAT-1 was investigated and the adaptation of bacteria on ore pulp was improved,the proper bioleaching pulp density using JAT-1 was up to 14%.Using ultraviolet mutagenesis and chemical mutagenesis,the breeding of bacteria was conducted.After mutagenesis,the growth activity of bacteria was increased of 42.3%,ammonia production capacity was increased of 19%,resulted in the enhancement of activity,and leaching ability of bacteria was increased of 39%.(3)The bioleaching influence factors using alkalophilic ammonia-producing bacteria were studied and optimized.The influence of temperature,inoculum size,initial pH,pulp density,ore particle size and shaking rate on bioleaching of copper ore using alkalophilic bacteria was investigated;then the bioleaching significant influence factors were screened through Plackett-Burman design;the interaction of significant influence factors on bioleaching was studied using Box-Behnken design and the bioleaching performance bacteria was optimized,resulted in high efficient leaching of copper.(4)The bioleaching mechanism of copper ore using alkalophilic ammonia-producing bacteria was revealed.The one-step bioleaching,two-step bioleaching and spent medium leaching were designed,the leaching performances with bacteria and without bacteria were compared,and the transformation of phase,morphological characteristics and pore of copper ore before and after bioleaching was analyzed.Based on the experiments results,the effect of bacteria adsorption on bioleaching was studied,the bioleaching effect of bacterial metabolites was revealed,and thus bioleaching mechanism of copper ore using ammonia-producing bacteria was illuminated.(5)The solid-liquid reaction process and its kenitics during bioleaching were revealed.The solid-liquid interaction mechanism during bioleaching was discussed and the mechanism of ore erosion was revealed.Considering the concentration change of leaching agent,the reaction kinetics equation of film diffusion control,ash diffusion control and chemical reaction control were derived,respectively,the shrinking core model of heterotrophic bacteria bioleaching was built,the reaction control step of bioleaching using ammonia-producing bacteria was revealed and apparent activation energy of reaction was obtained.(6)A new leaching technology of complex oxidized copper ore was proposed.Aiming to the acid heap leaching problems of complex oxidized copper ore,the new heap bioleaching technology using alkalophilic bacteria was proposed and the new implementing plan was designed.Also,the technical measures for intensifying bioleaching were put forword,the bioleaching technology prototype of complex oxidized copper ore was formed. |
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