Fine particle flotation for Florida dolomitic phosphate pebbles

A Florida dolomitic phosphate pebble sample was processed using a 1.2 liter stirrer-tank flotation cell and 2-in ID packed flotation column aiming at achieving a phosphate concentrate containing more than 30% P2O 5 and less than 1.0% MgO contents at high P2O5 recovery.;The characteristics of fatty acid collector, FA-12 and a newly developed PA-31 collector were evaluated for frothability and dolomite flotation rate. The evaluation results show that both reagents have high frothability, but PA-31 has much stronger frothability than FA-12, and higher selectivity in separating dolomite from phosphate mineral.;The mineralogical study indicates that the phosphate pebble sample needs to be ground to minus 150 mum (-100 mesh) for liberation of dolomite from phosphate. For the stirrer-tank cell, the composite phosphate concentrate has 31.66% P2O5 and 0.79% MgO at the overall P 2O5 recovery of 92%. For packed column flotation, the composite phosphate concentrate has 30% P2O5 and 0.96% MgO at the overall P2O5 recovery of 91%

Dolomite flotation of high magnesium phosphate ores using fatty acid soap collectors

The separation of dolomite from apatite has been recognized as one of the most difficult subjects in mineral processing due to the similarities in their physiochemical properties. In this study, selective surfactants were used with a fatty acid soap collector to improve the flotation performance of separating dolomite from high magnesium phosphate ores.;Three surfactants, diethyl phthalate (DP), Tween-80 (TW) and derivative of sulfonate salt (DSS1) were used. Hallimond cell flotation was conducted using pure dolomite sample to determine the effects of various factors including dosages, particle size, Ca2+ ions and slimes on the dolomite flotation recovery. The results showed that the surfactants can significantly improve dolomite flotation performance by increasing collecting ability and tolerating the effect of calcium ions and slime contents.;The stirrer-tank cell batch flotation tests were carried out using two natural high magnesium phosphate ore samples containing 3.3% and 1.5% MgO. The test results showed that the surfactant DP could improve dolomite flotation at low dosages, and DSS1 could enhance the separation of dolomite from phosphate by improving both collecting ability and flotation selectivity. When 10% of DSS1 was used with the fatty acid soap as collector, at least 10% more dolomite can be removed with less P2O5 loss. The effectiveness of the surfactant DSS1 in enhancing dolomite flotation was further demonstrated in modified packed column flotation with natural dolomitic phosphate ore sample.;The addition of the surfactant DSS1 into fatty acid soap collector could improve its frothability and froth stability, and reduce the bubble size. It has been found that the dolomite flotation performance has a close relationship with the frothability and froth stability of the collector

Strictly ergodic distal models and a new approach to the Host-Kra factors

Cocycles are a key object in Antol\'{i}n Camarena and Szegedy's (topological) theory of nilspaces. We introduce measurable counterparts, named nilcycles, enabling us to give conditions which guarantee that an ergodic group extension of a strictly ergodic distal system admits a strictly ergodic distal topological model, revisiting a problem studied by Lindenstrauss. In particular we show that if the base space is a dynamical nilspace then a dynamical nilspace topological model may be chosen for the extension. This approach combined with a structure theorem of Gutman, Manners and Varj\'{u} applied to the ergodic group extensions between successive Host-Kra characteristic factors gives a new proof that these factors are inverse limit of nilsystems

Maximal pronilfactors and a topological Wiener-Wintner theorem

For strictly ergodic systems, we introduce the class of CF-Nil($k$) systems: systems for which the maximal measurable and maximal topological $k$-step pronilfactors coincide as measure-preserving systems. Weiss' theorem implies that such systems are abundant in a precise sense. We show that the CF-Nil($k$) systems are precisely the class of minimal systems for which the $k$-step nilsequence version of the Wiener-Wintner average converges everywhere. As part of the proof we establish that pronilsystems are $coalescent$. In addition, we characterize a CF-Nil($k$) system in terms of its $(k+1)$-$th\ dynamical\ cubespace$. In particular, for$k=1$, this provides for strictly ergodic systems a new condition equivalent to the property that every measurable eigenfunction has a continuous version