The importance of gold recovery from low grade ores and flotation tailings is continuously increasing due to raising gold demand and thereby high gold prices. However, due to raising social awareness of the ecological...The importance of gold recovery from low grade ores and flotation tailings is continuously increasing due to raising gold demand and thereby high gold prices. However, due to raising social awareness of the ecological impacts of cyanidic gold extraction and environ-mental specifications, the development and the implementation of alternative hydrometallurgical extraction processes have been a focus for many research institutions in last decades. Present work gives a comparison between compatible extraction reagents, with focus on less harmful processes. The target of this review is to point out the best cyanide-free processes of following methods and reagents: Bioleaching, Chlorination, Aqua Regia, Bromine, Thiocyanate, Thiosulfate and Thiourea leaching. For this propose, the gold leaching reagents are described and discussed in terms of their environmental and economical points of view. As result of this comparison, thiourea stands out as the most promising alternative gold leaching reagent to cyanide.展开更多
In many applications in aluminium industry, the number of inclusion-critical products increases and the quality of those products depend on the inclusion concentration and size. In order to improve the quality of alum...In many applications in aluminium industry, the number of inclusion-critical products increases and the quality of those products depend on the inclusion concentration and size. In order to improve the quality of aluminium products and the effectiveness of the processes, a reliable and cheaper on-line detection method is needed. Ultrasonic detection has been used in steel industry, but relatively rare in aluminium industry, although it would theoretically allow for an online non-intrusive detection of the cleanliness of the melt. In this work, the current information on ultrasonic inclusion detection was gathered and recommendations were provided on the Prerequisites for a set-up for ultrasonic detection of non-metallic inclusions in aluminium as a contribution on previous works. It has been concluded that ultrasonic waves seem promising, and should be experimented more on an industrial level to have a clear view on the potentials of the method.展开更多
文摘The importance of gold recovery from low grade ores and flotation tailings is continuously increasing due to raising gold demand and thereby high gold prices. However, due to raising social awareness of the ecological impacts of cyanidic gold extraction and environ-mental specifications, the development and the implementation of alternative hydrometallurgical extraction processes have been a focus for many research institutions in last decades. Present work gives a comparison between compatible extraction reagents, with focus on less harmful processes. The target of this review is to point out the best cyanide-free processes of following methods and reagents: Bioleaching, Chlorination, Aqua Regia, Bromine, Thiocyanate, Thiosulfate and Thiourea leaching. For this propose, the gold leaching reagents are described and discussed in terms of their environmental and economical points of view. As result of this comparison, thiourea stands out as the most promising alternative gold leaching reagent to cyanide.
文摘In many applications in aluminium industry, the number of inclusion-critical products increases and the quality of those products depend on the inclusion concentration and size. In order to improve the quality of aluminium products and the effectiveness of the processes, a reliable and cheaper on-line detection method is needed. Ultrasonic detection has been used in steel industry, but relatively rare in aluminium industry, although it would theoretically allow for an online non-intrusive detection of the cleanliness of the melt. In this work, the current information on ultrasonic inclusion detection was gathered and recommendations were provided on the Prerequisites for a set-up for ultrasonic detection of non-metallic inclusions in aluminium as a contribution on previous works. It has been concluded that ultrasonic waves seem promising, and should be experimented more on an industrial level to have a clear view on the potentials of the method.
