Depression of pyrite flotation by dextrin has been investigated through adsorption, electrokinetic and microflotation studies in systems open to the atmosphere. Adsorption of dextrin takes place through specific interaction with ferric oxyhydroxide species that result from the oxidation of pyrite surface. Dextrin shows an isoelectric point at pH 4 and pyrite does at pH 6.4. Within this pH range adsorption is suggested to be promoted by electrostatic interactions. Coadsorption of dextrin and isopropyl xanthate occurs on the surface of pyrite and is explained to happen through distinct mechanisms taking into account the heterogeneous nature of the surface. It is likely that dextrin depresses pyrite by enveloping the dixanthogen resulting from adsorption of xanthate ions. It is shown that dextrin is as effective depressant of pyrite as cyanide.
[Show abstract][Hide abstract] ABSTRACT: The interaction mechanism of sodium diisobutyl dithiophosphinate (DTPINa) with chalcopyrite, pyrite, galena and sphalerite was investigated by single mineral flotation experiment, adsorption measurement and FTIR spectrum analysis. Single mineral flotation experiments showed that sodium diisobutyl dithiophosphinate exhibited a strong ability to collect chalcopyrite and galena. For chalcopyrite and pyrite, the recovery of chalcopyrite can reach 96.2% when the dosage is 12 mg/L and pH value is 8. In the same situation, the recovery of pyrite is as low as 13.5%. For galena and sphalerite, the recovery of galena reached 91.7% when the dosage was 50 mg/L at pH 11, and the recovery of sphalerite was only 16.9%. DTPINa adsorbed on chalcopyrite and galena surfaces are more than that on pyrite and sphalerite surfaces. The adsorption capacity of DTPINa on the minerals surface is proportional to its dosage. The FTIR spectrum analysis results showed that the adsorption of DTPINa on sulfide minerals surface is chemical and S atoms in PS and PS may have taken part in the reaction. The natural ores experiments also confirmed the excellent performance of sodium diisobutyl dithiophosphinate.
Journal of Materials Research and Technology 01/2015; 23(2). DOI:10.1016/j.jmrt.2014.12.003
"Recently, López et al. (2004) investigated depression of pyrite flotation by dextrin through adsorption, electrokinetic and microflotation studies. They described the chemical interaction of dextrin with ferric oxyhydroxide sites on the surface of pyrite as follows: "
[Show abstract][Hide abstract] ABSTRACT: The interaction of glucose with pyrite has been investigated by a series of surface analyses, such as amounts adsorbed, TG, FTIR and XRD measurements. The adsorption experiment reveals that glucose would rapidly adsorb on the pyrite surface within 60 min. However, physical adhesion characterized as multi-molecular layer adsorption may occur based on adsorption isotherm type. All results obtained by TG and FTIR suggest that no adsorption took place after several times of washing. XRD results indicate that crystal structure of pyrite was not obviously destructed after glucose was added. The interplane distances of (111), (400) after interaction between glucose and pyrite were widened, which showed the similar manner with that of before interaction. All these convincing data imply that physical adsorption predominantly governs the interaction of glucose on pyrite.
[Show abstract][Hide abstract] ABSTRACT: A novel slope delay model for CMOS switch-level timing verification is presented. It differs from conventional methods in being semi-analytic in character. The model assumes that all input waveforms are trapezoidal in overall shape, but that they vary in their slope. This simplification is quite reasonable and does not seriously affect precision, but it facilitates rapid solution. The model divides the stages in a switch-level circuit into two types. One corresponds to the logic gates, and the other corresponds to logic gates with pass transistors connected to their outputs. Semi-analytic modeling for both cases is discussed
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