| China is abundant in gold mineral resources,but most are hard to deal with.And arsenic ore,especially arsenic sulfide ore,is one of the main types.In order to extract valuable metals from arsenic-bearing ores,especially precious metals such as gold and silver,they need to be oxidatively pre-treated.Roasting,pressure oxidation and bacterial oxidation are common methods.Bacterial oxidation has competitive advantages for its low pollution,low investment,low cost,simple equipment,convenient operation compared with roasting and pressure oxidation.However,arsenic in arsenic bearing ore,especia lly As(?)is toxic to bacteria.So in order to strengthen the results of bacterial oxidation,training bacterial in arsenic leaching and studying mechanism of arsenic phase transformation become necessary.In this paper,three kinds of different arsenic ore were used as research object.Based on the analysis of the technological mineralogy,leaching of arsenic ore bacteria thermodynamics and the phase transition mechanism of arsenic were analyzed.Feasibility of arsenic bioleaching was identified,and then bioleaching on different arsenic ore were strengthen.Fluorescent staining was used for HQ0211 bacteria and observed the adsorption of arsenic ore under fluorescent microscope for the first time.Firstly,gading,XRF,quantitation,XRD and SEM-EDS were used to analyzing the mineralogy of three kinds of arsenic ore.The results show that:in 1#DS ore,As 39.4 wt%,Fe 33.45 wt%,.S 20.9 wt%are the main elements.And the main phase is arsenopyrite and a small amount of pyrite;in 2#XH ore,As 40.1 wt%,Fe 7.54 wt%,S 47.4 wt%are the main elements,And the main phase is realgar and orpiment;in 3#SK As 8.8 wt%,Fe 37.25 wt%,S 20.9 wt%are the main elements,pyrite(main)and arsenopyrite were detected in it.Then,FactSage was used to draw Eh-pH diagram of Fe-As-S-H2O under 25?,45?,65?and 85?.Eh-pH diagram was drawn when bacteria was added under 45? according to literature of science and technology from others.Arsenic performance was analyzed by thermodynamics,and arsenic were existed as H3AsO3?HAsO42-?H2AsO3-?H2AsO4-?H3AsO4?FeAsO4,etc,through all the process of bioleaching,Three kinds of arsenic ore bioleaching performance were studied,and the conditions were set to be:pulp density 1%,temperature 45?,RPM,190 r·min-1.The results show that:for 1#DS,after 18 d bioleaching,As leaching rate reached 94.6%;for 2#XH,after 14 d bioleaching,As leaching rate reached 35.4%;and for 3#SK,after 2.5 d bioleaching,As leaching rate reached 85.5%.The conversion process of arsenic in sulfide ore is:[AsS]2-?As(?)?As(?);The transformation process of the arsenic in realgar is divided into two parts:As4S4?As(?)?As(?),and As4S4?AsxSy(0.174?x/y?0.342).The bacteria on the surface of the ore was fluorescently stained and then observed under the microscope.The results show that:the attached bacteria can be separated into three parts,which were normal bacteria that emit bright green fluorescence,apoptosis bacteria that emit yellow-green fluorescence,and necrotic bacteria that emit orange-red fluorescence;bacteria were mainly adsorbed in group,for bacterial nutrition and self-protection or improvement of the microenvironment of the ore;and with the intensifying of bacterial corrosion,the mineral crystals gradually dissociated,and some fissures appear,and the bacteria could be adsorbed in a strip shape. |
PDF Full Text Request