Selective flotation of chalcopyrite from pyrite via seawater oxidation pretreatment

The flotation separation of chalcopyrite from pyrite has attracted increasing attention due to the consumption of vast water resources and depressants.This study proposed the seawater oxidation pretreatment for non-depressant flotation separation of chalcopyrite from pyrite,as an effective and environmentally friendly strategy.Without the addition of depressants,seawater oxidation for 3 d effectively depressed pyrite flotation,with the highest recovery difference greater than 70%and a selectivity index greater than 6 between chalcopyrite and pyrite.The surface investigation showed that pyrite surface was more readily oxidized to form hydrophilic Fe oxidants/oxyhydroxides,as compared to that of chalcopyrite.Further UV-visible spectrophotometer and Fourier transform infrared spectrum(FTIR)results indicated that xanthate was less adsorbed onto the treated pyrite surface,resulting in un-floatable particles.Chalcopyrite surface was changed slightly due to seawater oxidation,thereby insignificantly affecting its flotation.The coordination theory was further used to reveal the combination mechanisms between xanthate and pyrite or chalcopyrite.This study therefore provides a promising strategy to effectively separate chalcopyrite from pyrite,especially in the freshwater-deficient area.

Structure and Coordination Investigation of Iron-ion Tinting Principle in Ferreous Glass

The tinting phenomena of iron oxide contained glasses were studied from aspects of the electronic configuration, the iron ions coordination fields and the ions structure in glass. Several iron ion tinting forms at different redox or COD (chemical oxygen demand) conditions and their influential factors were given necessary explanations. The results reveal that the Fe^(3+)-O-Fe^(2+) structure is the real tinting reason of iron involved glasses, whereas the Si^(4+)-O-Fe^(3+) and Si^(4+)-O-Fe^(2+) formulations modify the glass colours. Under oxidizing melting condition, the amount of 4/6-coordinated Fe^(3+) increases and makes the glass colour yellowish. Conversely, reducing melting condition makes the 6-coordinated Fe^(2+) increased and gives much blue tint to the glass. The conventional tank furnace melting the very strong reducing condition, which is of high COD glass batch, is not suitable. The high ratio of ferrous/ferric in glass can be obtained with a new refining technology which contains no or little amount of refining agent.

Coordination-theoretic approach to modelling grid service composition process

A grid service composite process is made up of complex coordinative activities.Developing the appropriate model of grid service coordinative activities is an important foundation for the grid service composition.According to the coordination theory,this paper elaborates the process of the grid service composition by using UML 2.0,and proposes an approach to modelling the grid service composition process based on the coordination theory.This approach helps not only to analyze accurately the task activities and relevant dependencies among task activities,but also to facilitate the adaptability of the grid service orchestration to further realize the connectivity,timeliness,appropriateness and expansibility of the grid service composition.