Research And Practice On Bioleaching Of Low-grade Complex Copper Sulfide

There are few big copper mine in China, copper mineral resource in China are almost low grade and complex. In great need of new technology to process Chinese low grade copper mineral resource, so we can ease our long-term dependence on imported contradiction copper industry. In this paper for Yushui Copper Mine in Meizhou Guangdong province, bioleaching bacteria breeding and composite stain group to community, copper sulfide mineral bioleaching by flask and two kinds of columns, bioleaching industry experiment on 10,000 tons ore under groud, electrochemistry behavior of primary copper sulfide, apply this bioleaching technology to the bioleaching of 7 kinds sulfide mineral in 7 mine, in the end, successfully put this new bioleaching technology in practie in Zambia Chambishi Copper Mine. Such conclusions are as follwing:(1)From 7 AMD samples in 7 mines, by separation, screeming and identification process, we get 7 strains A.f which character is control by the mine environment. This 7 strains A.f were collected by CCTCC.Temperature, pH, cell concentration, Cu2+ and Fe2+ have effect on growth and oxidation ability of the 7 strains A.f. In the 7 strains A.f,3 one have good S and Fe2+ oxidation ability, which is called high strains A.f. By mix culture medium, from AMD richment,4 different communities with good S and Fe2+ oxidation ability were formed. In the end, the basic process of bioleaching bacteria screening and the combination of bioleaching bacteria stains were summarized.(2)Bacteria leaching rate of chalcopyrite by A.f is not high; the highest copper extraction is 54.25%in 30d. Bacteria leaching rate of bornite by A.f is above normal; the highest copper extraction is 77.55%in 30d. Temperature, cell concentration, pH and pulp density have effect on the bioleaching of chalcopyrite and bornite. While bioleaching of the mixture of chalcopyrite and bornite is more effective, the copper extraction is 86.25%in 30d. The bioleching of raw ore by the combination of bioleaching bacteria stains is feasible. The best condition of bioleaching test were:T=30℃, pulp density 10%, cell concentration 5%, the ore particle size were 90%, rotate speed was 170rad/s, pH=2.0, the copper extraction is 95.63%in 28d. By SEM and X-ray analysis of experimental samples and their leaching residua, the bioleaching mechanism was discussed.(3)Minetype and large-scale column bioleaching equipment were developed. By these two column bioleaching equipment, multi factor bioleaching experiment were in progress. By minetype column, essential parameter column bioleaching of can be gained. The large-scale column is the efficient semi industry experiment equipment. The best condition of large-scale column bioleaching test were:T=35℃, the ore particle size were +5-15mm, pH=2.0, the leaching solution spray was15L/h·m2, for the No.3 bacteria consortium, with aeration 2h each day, the copper extraction is 85.56%in 300d, the sulfide acid consumption is 158kg/t raw ore. This result not only showed that the novel bioleaching technology of the low grade copper ore was successful, but also provides technological parameter for industry project.(4)In Meizhou Yushui Copper Mine, over 10,000 tons ore heap built for bioleaching industry was conducted under well. The copper extraction is 80.45%in 330d bioleaching. Use CGA (Community Gene chip Array) to inspect bioleaching bacteria community structure change during 330d bioleaching process.(5)The monitoring of bacterial and chemical dissolution of massive chalcopyrite and bornite was performed using cyclic voltammetry (CV); during the oxidation process of chalcopyrite and bornite, so many intermediate reaction occurred at different oxidation-reduction potential with corresponding intermediate product generated.The biooxidation process of chalcopyrite and bornite were as follow:CuFeS2→Cu9FeS16→Cu5FeS4→Cu2S→Cu1.92S→Cu1.65S→CuS→S0→SO42-.H+ acted as oxidant during the oxidation of chalcopyrite and bornite, in the certain pH value range, low pH is avail to the the oxidation process. Bioleaching bacteria are also avail to the the oxidation process, different stains and consortium with different promote action. Fe2+ is avail to the the mineral oxidation process obviously. Fe2+ and Fe3+ together are more avail to the oxidation of chalcopyrite and bornite. Cu2+ has certain oxidizability for it can improve the bioleaching system potential. Certain concentration of Cl- is avail to the oxidation of chalcopyrite and bornite. During pH=2.0, their oxidation stimulative effect of chalcopyrite and bornite are:bacteria consortium+Cl->Cl> bacteria consortium>sterile control.(6) 7 mine sulfide ore column bioleaching experiment showed that: copper extraction is 87.22%for Xinjiang Wuqia 100kgs copper ore in 307d, copper extraction is 83.03%for Ningxia Zhiongwei 100kgs copper ore in 315d, copper extraction is 75.63%for Hubei Daye 100kgs copper ore in 307d, copper extraction is 15.47%for Heilongjiang Duobaoshan 180kgs copper ore in 326d.Copper, nickel and cobalt extraction are 92.56%,66.01%and 85.03% respectively for Xinjiang Hami 20kgs copper ore in 240 d.Nickel, cobalt, copper, iron and magnesian extraction are 88.62%,82.15%,56.39%,39.36% and 55.69%respectively for Gansu Jinchuan 150kgs copper ore in 350d.The bioleaching industrialization of the primary copper ore is more difficult the the secondary copper ore, Cu-Ni-Co sulfide with low content of calcium and magnesium ore are also easy to conduct bioleaching pratice. Bioleaching practice was successful in Chambishi copper mine in Zambia.0.6 million tone ore Dump for bioleaching, copper extraction was over 50%. Copper production increased with 20%, sulfur acid consumption decreased with 35%.