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Deendence of Froth Behaviour on Galvanic Interactions
Published in J. S. Laskowski, E. T. Woodburn, Frothing in Flotation II, 2018
Rao et al.[23] observed that most sulphides had mixed potentials at or above the xanthate/dixanthogen redox potentials at various concentrations of potassium ethyl xanthate, while the mixed potentials of the same minerals in contact with metallic iron were substantially below the xanthate/dixanthogen redox potential. As indicated in the previous paragraph, it is not a simple problem to predict whether the metal xanthate or dixanthogen will form on the mineral surface under specific conditions. However, on the basis of the aforementioned discussion there is a high probability that the metal xanthate with a lower hydrophobicity (than dixanthogen) will form on sulphide minerals when they are in galvanic contact with mild steel. In contrast, if these minerals are on their own such as when they are milled in a ceramic mill, there is a good chance that dixanthogen will form on their surfaces. This will cause low selectivity between the minerals and even an overloading of the froth by hydrophobic particles.
Telechelic Polyhydroxyalkanoates/Polyhydroxybutyrates (PHAs/PHBs)
Published in Sophie M. Guillaume, Handbook of Telechelic Polyesters, Polycarbonates, and Polyethers, 2017
Abdulkadir Alli, Baki Hazer, Grażyna Adamus, Marek Kowalczuk
Thermoresponsive polymers based on microbial polyesters and poly(N-isopropyl acryl amide) (PNIPAM) have been reported recently [131]. The unsaturated poly(3-hydroxy undecenoate) (PHU) and 1:1 mixture of 10-undecenoic acid and soy oil acids (PHU-Sy), were brominated using bromine, in the dark, at room temperature. The resulting brominated PHAs were next transformed to macroreversible addition-fragmentation chain transfer (RAFT) agents via the substitution reaction with potassium ethyl xanthate. RAFT polymerization of N-isopropyl acryl amide (NIPAM) was then initiated by the PHA derivative containing xanthate pendant groups in order to obtain brush-type PHA-g-PNIPAM thermoresponsive amphiphilic graft copolymers (Scheme 3.34). The water uptake of the recovered PHU-g-PNIPAM and (PHU-Sy)-g-PNIPAM amphiphilic graft copolymers ranged from 50% to completely soluble in water.
Froth flotation
Published in D.V. Subba Rao, Mineral Beneficiation, 2011
Flotation operation was initially developed to treat the sulphides of lead, zinc and copper. In a typical flotation practice of lead-zinc ore, the different reagents used are sodium cyanide and zinc sulphate as depressants for pyrite and sphalerite, potassium ethyl xanthate as collector for lead circuit to float galena, sodium isopropyl xant-hate in zinc circuit to float sphalerite, copper sulphate to activate already depressed sphalerite in zinc circuit, lime as pH regulator, and crysilic acid as frother in both circuits. In some plants, Methyl Iso-Butyl Carbinol (MIBC) is used as a frother. For the flotation of chalcopyrite (copper mineral in most of the copper concentrators), sodium isopropyl xanthate and pine oil are the collector and frother respectively in most of the plants. Soda ash is used as a pH regulator.
Beneficiation of Lead-Zinc Ores – A Review
Published in Mineral Processing and Extractive Metallurgy Review, 2022
Aryasuta Nayak, M. S. Jena, N. R. Mandre
Modeling and simulation tools are widely used in mineral processing industries for the prediction of separation efficiency. Such models are used for accurate prediction, error calculation, etc. Ghaffari, Hayati and Shekholeslami (2012) used Monte-Carlo simulation by @Risk software to analyze the complex lead-zinc flotation circuit of Bama concentrator, Iran. Fluctuations in input parameters are unavoidable in the case of plant-scale operations. Such fluctuations lead to variation in output data. So, analysis of such fluctuations, error diagnosis is quite complicated. Hence, the authors suggested that Monte-Carlo method can be helpful for probability and sensitivity analysis of lead-zinc circuits in day-to-day operation. Kostović and Gligorić (2015) applied the TOPSIS method based on multi-criteria decision making (MCDM) for ranking and selection of optimal collectors using different types of xanthates, such as potassium ethyl xanthate (KEX), sodium isopropyl xanthates (NaIPX), and potassium isobutyl xanthates (KIBX). They found that KEX at a dosage of 17 g/t gave promising results for Pb flotation. Further optimization of this model showed that it is useful for final decision-making in mineral processing experiments as well as solving specific problems in the daily laboratory (Kostović and Gligorić 2015).
Effect of strong collectors and frothers on coarse particle flotation using the HydroFloat™ for a North American concentrator
Published in CIM Journal, 2022
A. Di Feo, M. De Souza, R. Lastra, A. Hobert
The HydroFloat™ uses innovative flotation techniques to enhance the potential to recover coarse grained particles. The absence of a froth phase at the top of the cell allows particles to attach to bubbles and immediately exit the vessel, reducing the likelihood of drop back into the pulp. Additionally, the settling conditions created by the rising column of water allow coarse particles to become buoyant once attached to a bubble (Mehrfert, 2017). The HydroFloat™ employs an aerated fluidized bed of solids designed to recover coarse particles (Kohmuench et al., 2007). It offers reduced turbulence, improved bubble-particle collision and attachment, decreased buoyancy restrictions, higher particle residence time, and plug-flow separating conditions (Kohmuench et al., 2010). This technology has been used for industrial mineral flotation to recover particles as coarse as 3,000 μm (Kohmuench et al., 2007) and in coal, potash, phosphate, Cu, and gold flotation (Kohmuench et al., 2007). In this paper, PAX/FrothPro 630 and potassium ethyl xanthate (PEX)/X-133 were tested at two pH values using the HydroFloat™. The objective was to determine whether a stronger collector and frother would increase pay metal recovery in the HydroFloat™.
Synthesis, structure and reactivity of some chiral benzylthio alcohols, 1,3-oxathiolanes and their S-oxides
Published in Journal of Sulfur Chemistry, 2020
R. Alan Aitken, Philip Lightfoot, Andrew W. Thomas
Our synthesis started by diazotization of the amino acids leucine, valine and isoleucine bearing bulky alkyl side chains in the presence of 3–6 equivalents of potassium bromide [4] to afford the α-bromo acids 1–3 (Scheme 1). These showed good agreement of boiling point and optical rotation with literature values. An attempt was then made to introduce sulfur by addition of potassium ethyl xanthate to a solution of the α-bromo acids in aqueous sodium carbonate. This proved to be highly effective in the case of bromo acid 1 to afford the previously unknown derivative 4 in almost quantitative yield. However, as previously documented [5], the corresponding reaction with the more sterically hindered bromo acids 2 and 3 failed. Direct reduction of the xanthate 4 with lithium aluminium hydride gave a mixture of mercapto alcohol and mercapto acid in both THF and diethyl ether, so the acid group was first converted into the ethyl ester to give 5, which was then efficiently reduced to afford the mercapto alcohol 6 as an intensely unpleasant smelling oil. To give the first target benzylthio alcohol 7, this was S-benzylated by treatment with sodium ethoxide in ethanol followed by benzyl bromide.