Efficient Utilization Of Jiama Copper-molybdenum Ore

Copper and molybdenum are extremely important nonferrous metals and play an irreplaceable role in the national economy.Jiama extra-large copper-polymetallic ore deposit is located in the central zone of the autonomous region "one river and two streams",which is a typical representative of Gangdese metallogenic belt in Qinghai-Tibet Plateau.This mining area has been explored with copper metal content of 7.52×106 t,molybdenum metal content of 0.70×106t,lead metal content of 1.11 × 106t,zinc metal content of 0.64×106t,gold metal content 174.540 t,and silver metal content of 1.09×104t.Therefore,it is extremely urgent to carry out efficient utilization of the resources correspondingly.Due to the complex properties of Jiama copper-molybdenum ore and the fact that dressing wastewater can not drain to outside directly in an ecologically fragile zone at high altitude,it is of huge difficulty to make efficient utilization of the ore.In response to this situation,a thorough and systematic study was carried out in this paper,and some technological breakthroughs were made in the section of copper-molybdenum flotation separation.Finally,both copper and molybdenum were separated efficiently and recovered comprehensively.Based on systematic process mineralogy study,it is found that the main metallic minerals are chalcopyrite,molybdenite,galena,sphalerite and some secondary copper minerals,including bornite,chalcocite,copper,blue,tetrahedrite,etc.;the main gangue minerals are garnet,diopside,calcite,feldspar and quartz.Chalcopyrite possesses a wide range of dissemination size,while that of molybdenite and secondary copper minerals are finer than chalcopyrite.In addition,the distribution ratio of copper in secondary minerals reaches up to 16.92%,which has some adverse influences on the efficient use of the ore.Through a systematic laboratory test,the suitable conditions of Jiama copper-molybdenum ore flotation were obtained:grinding fineness was 70%-0.074 mm;the dosage of calcium oxide was 500 g/t(slurry pH value is 8 to 9);the dosages of butyl xanthate and 2#oil in rough flotation were 100 g/t and 40 g/t,respectively.Under these conditions,a flotation process,containing two-stage roughing,two-stage scavenging and three-stage concentrating,was performed.A copper-molybdenum bulk concentrate with a yield of 2.93%,copper grade and recoveries of 20.07%and 91.00%,molybdenum grade and recovery of 0.531%and 72.78%,gold recovery of 65.17%and silver recovery of 66.84%was obtained.Flotation conditions for the separation of copper-molybdenum bulk concentrate were determined as following:the regrinding fineness was 90%-0.048mm;the dosages of ZG-2 used as copper mineral inhibitor in roughing,concentrating and scavenging operations were 20000 g/t,10000 g/t,and 10000 g/t,respectively;the dosages of HTL-3 used as molybdenum collector in roughing,concentrating and scavenging operations were 100 g/t,30 g/t,and 30 g/t,respectively.Under these conditions,a flotation process,including single-stage roughing,two-stage scavenging,and four-stage concentrating,was implemented.Eventually,a molybdenum concentrate with a yield of 1.09%,molybdenum grade and recovery of 47.68%and 81.45%,copper grade of 1.09%and copper recovery of only 0.06%was obtained.And a copper concentrate of a yield of 98.91%,copper grade and recovery were 19.26%and 99.94%,molybdenum grade and recovery were 0.12%and 18.55%was also attained.The grade of gold and silver in copper concentrate were 7.05 g/t and 495.73 g/t,and the recovery of them in copper concentrate were 99.96%and 99.88%,respectively.The experiment results established a foundation for efficient utilization of Jiama copper-molybdenum ore.The results of the small test in the laboratory at the altitude of 4000 m indicated that the optimal pulp density was 18%;the best dosages of ZG-2 and HTL-3 were 10000 g/t and 80 g/t,respectively;and the appropriate regrinding fineness of roughing concentrate was 95%-0.048 mm.Under these conditions,a molybdenum concentrate with a yield of 0.95%,molybdenum grade and recovery of 45.19%and 81.28%,and a copper concentrate with a yield of 99.05%,copper grade and recovery of 23.58%and 99.95%were obtained through single-stage roughing,three-stage scavenging and five-stage concentrating.Regrinding molybdenum coarse concentrate was conducted during copper-molybdenum flotation separation,which greatly reduced the amount of grinding,improved the liberation degree of molybdenum minerals and copper minerals,and also avoided filtration problem of the copper concentrate.After appropriate aeration and chemical treatment,the wastewater could be completely returned to the flotation process with little effect on the flotation indexes,and could be reused continuously.The industrial practice of copper-molybdenum flotation separation was conducted at a 6000 t/d copper-molybdenum ore dressing plant in Jiama,Tibet.The results demonstrated that it was possible to obtain satisfactory industrial technical indicators by using the appropriate process and reagent system determined by laboratory test.The copper grade and recovery of copper concentrate were greater than 23%and 90%,respectively.The molybdenum grade and recovery of molybdenum concentrate were greater than 45%and 50%,respectively.Meanwhile,both gold and silver were effectively enriched in copper concentrate.The grades of gold and silver were 7.89 g/t and 523.15 g/t,and the recoveries of them were 68.91%and 70.22%,respectively.Through infrared spectroscopic analysis,SQX spectroscopic analysis,and simulated calculation based on quantum chemistry,the mechanisms of flotation reagents used in copper-molybdenum separation have been systematically studied.The results indicated that the main components of molybdenum mineral's collector HTL-3 are alkanes and olefin,which adsorb on the mineral surface by van der Waals's forces.Then the hydrophobicity of mineral surface is enforced,and the collecting of minerals is achieved.The main action groups of copper minerals inhibitor ZG-2 are S2" and HS",which adsorb on the chalcopyrite surface through the reactions of S atoms with Cu atoms and Fe atoms on the mineral surface.After HS' adsorbed on the chalcopyrite(112)surface,the surface energy of mineral crystals is much less than molybdenite(001)surface.Therefore,HS-adsorb more easily on the chalcopyrite surface,which increases floatability difference between chalcopyrite and molybdenite.In flotation process,HS' forms a more stable precipitate on the chalcopyrite surface,and desorb xanthate.Due to the favorable hydrophilicity of CuS,the separation of copper and molybdenum is achieved.In this paper,the flotation process of Jiama copper-molybdenum ore not only achieved efficient utilization of copper-molybdenum ore at high altitudes,but also adopted non-toxic and degradable reagents,ZG-2 and HTL-3,in copper-molybdenum flotation separation.In addition,the copper-molybdenum bulk concentrate is directly transported to the process of flotation separation,which simplifies the process structure,reduces the consumption of reagents,improves operating conditions of copper-molybdenum flotation separation and copper concentrate filtration,and boosts the technical and economic indicators.This process has broad application prospects,and is of great importance for promoting the economic development of Tibet,which has abundant non-ferrous mineral resources.