The sedimentary phosphate deposit of Bayovar is located in a very dry area of Peru （desert of Sechura） which is close to the Pacific coast. It consists of seven superposed layers （beds） which call for different st...The sedimentary phosphate deposit of Bayovar is located in a very dry area of Peru （desert of Sechura） which is close to the Pacific coast. It consists of seven superposed layers （beds） which call for different strategy of concentration. The ore is composed predominantly by apatite （84% in weight basis） plus silicates （16%）. To concentrate phosphate from beds 6-7, it is necessary to carry out further cationic reverse flotation of silicates, at neutral pH, to yield a concentrate which meets market specification. The new process was developed in laboratory scale by a collaborative program conducted between Vale S. A. and the University of Sao Paulo--Brazil. As water resources are very limited at Bayovar region, all the steps of concentration, including flotation, must be performed with seawater which must be continuously recycled. This work addresses some relevant topics related to the use of seawater in the reverse cationic flotation of silicates： influence of temperature, water quality （ageing and chemical composition） and collector type. The results indicate that amido amine works better than ether amine. If flotation is conducted with the former collector, the separation process is able to tolerate changes in temperature （25 ℃-40 ℃） and water quality caused by either evaporation or ageing.展开更多
China has abundant solar energy resource. Solar thermal collectors, particularly all-glass evacuated tubular collectors, have been studied and developed for 30 years, and solar thermal industry has developed rapidly f...China has abundant solar energy resource. Solar thermal collectors, particularly all-glass evacuated tubular collectors, have been studied and developed for 30 years, and solar thermal industry has developed rapidly for 15 years. There are various solar thermal systems, with an operation area of around 108 million m2 in 2007. These systems mainly provide domestic hot water, but some other applications are under extensive study and development as well.展开更多
文摘The sedimentary phosphate deposit of Bayovar is located in a very dry area of Peru （desert of Sechura） which is close to the Pacific coast. It consists of seven superposed layers （beds） which call for different strategy of concentration. The ore is composed predominantly by apatite （84% in weight basis） plus silicates （16%）. To concentrate phosphate from beds 6-7, it is necessary to carry out further cationic reverse flotation of silicates, at neutral pH, to yield a concentrate which meets market specification. The new process was developed in laboratory scale by a collaborative program conducted between Vale S. A. and the University of Sao Paulo--Brazil. As water resources are very limited at Bayovar region, all the steps of concentration, including flotation, must be performed with seawater which must be continuously recycled. This work addresses some relevant topics related to the use of seawater in the reverse cationic flotation of silicates： influence of temperature, water quality （ageing and chemical composition） and collector type. The results indicate that amido amine works better than ether amine. If flotation is conducted with the former collector, the separation process is able to tolerate changes in temperature （25 ℃-40 ℃） and water quality caused by either evaporation or ageing.
文摘China has abundant solar energy resource. Solar thermal collectors, particularly all-glass evacuated tubular collectors, have been studied and developed for 30 years, and solar thermal industry has developed rapidly for 15 years. There are various solar thermal systems, with an operation area of around 108 million m2 in 2007. These systems mainly provide domestic hot water, but some other applications are under extensive study and development as well.
