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A new approach in separation process evaluation. Efficiency ratio and upgrading curves

Irannajad M., Nuri O. S., Allahkarami E.

Physicochemical Problems of Mineral Processing

2018

Vol. 54, iss. 3

847--857

In mineral processing separation efficiency (SE), operation efficiency (OE), selectivity index (SI) and other indices have been used to evaluate the separation process. Up to now, no study has been conducted on the relationship between the SE, OE and SI indices. In this research, two upgrading curves are proposed based on the above indices for process and selectivity evaluation. The first upgrading curve is based on recovery R, SE, and OE as a function of concentrate grade. This curve has three background lines, including no upgrading line, ideal upgrading line and the ideal mixing line. The proposed upgrading curve is applicable not only for process evaluation by specification of OE and SE, but also for selectivity evaluation with the lowest difference between SE and OE. The curve showed that the recovery value is always greater than the SE and OE values. The parameters of OE, SE and R were used for plotting the upgrading curve as a function of concentrate grade taking into consideration all of them at a time. A new selectivity indicator, namely Efficiency Ratio (ER) as the selectivity parameter, is proposed as the ratio of OE to SE. The ER values fluctuate between 1 and . It can be presented as a function of concentrate and tailing grades (ER = [c(1-t)]/[1(c-t)]). The results showed that ER is insensitive to the feed grade and has the inverse relationship with SI. To measure the separation selectivity, another upgrading curve is proposed based on ER and SI parameters. This curve is divided into seven separation classes for evaluation the class of a separation process from ideal class to no separation one. The results of this research can be useful for separation process evaluation.

Optimization of desliming prior to phosphate ore upgrading by flotation

Ahmed H. A. M.

Physicochemical Problems of Mineral Processing

2007

Vol. 41

79-88

Flotation is one of the most efficient techniques applied for phosphate upgrading. Desliming of flotation feed is a critical pre-request step for successful phosphate/gangue separation by flotation. Generally, the target of the desliming step is to minimize the feed fines to avoid their negative effects during flotation. However, such slimes normally contain phosphates which are considered as losses. An effective desliming should pay attention to minimizing the losses of phosphate bearing minerals in the removed slimes and, as a second target, to keep high phosphate recovery in the flotation feed. In this paper optimization of the desliming stage to achieve both targets at-a-time was studied using different techniques at different operating conditions. The applied slimes removal techniques included screening and hydrocycloning. It was found that desliming using hydrocyclone, at its optimum operating conditions, is better than desliming using screens. This is because the deslimed product contained small amount of phosphate slimes leading to efficient separation by flotation with an overall selectivity index B=0.739 defined by formula (wzór) where ĺε 1,c= P2O5 recovery in flotation concentrate, %; ĺε 2,t = MgO recovery in both slimes and flotation tail, % .

Flotacja jest jedną z najbardziej efektywnych technik stosowanych do wzbogacania fosforytów. Odszlamianie nadawy flotacyjnej jest ważnym warunkiem wstępnym dobrej separacji fosforytów od skały płonnej. Ogólnie, celem etapu odszlamiania jest minimalizacja ilości drobnych ziarn dla uniknięcia ich negatywnego wpływu na flotację. Jednakże szlamy zawierają także fosforany, które zostają tracone. Efektywne odszlamianie powinno brać pod uwagę minimalizację strat fosforanów w usuwanych drobnych ziarnach oraz pozwolić na utrzymywanie wysokiej zawartości fosforanów w nadawie flotacyjnej. W tej pracy optymalizowano etap odszlamiania dla uzyskania obu celów jednocześnie. Użyto różnych technik badawczych stosując zróżnicowane warunki technologiczne. Jako sposób usuwania drobnych ziarn zastosowano przesiewanie i klasyfikację w hydrocyklonach. Stwierdzono, że w optymalnych warunkach odszlamianie w hydrocyklonach jest lepsze niż na sitach. Odszlamiany materiał zawiera małe ilości fosforanów i dlatego prowadzi to do efektywnej separacja za pomocą flotacji a wskaźnik selektywności B, zdefiniowany jako (wzór) osiąga wartość 0.739, gdzie ε 1,c oznacza uzysk P2O5 w koncentracie flotacyjnym w %, podczas gdy ε 2,t oznacza uzysk MgO w szlamach jak i w odpadzie flotacyjnym (w %) .