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1

Role of calcium and magnesium cations in the interactions between kaolinite and chalcopyrite in seawater

Uribe L., Gutierrez L., Laskowski J. S., Castro S.

Physicochemical Problems of Mineral Processing

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2017

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Vol. 53, iss. 2

737--749

EN

A number of flotation plants around the world have increased the use of seawater due to limited sources of fresh water. The aim of this research work is to study the role that Mg2+ and Ca2+ ions play in the interactions between kaolinite and chalcopyrite in seawater. In order to achieve this objective, the effect of kaolinite on flotation of chalcopyrite is studied over the pH range from 8 to 11, when flotation is carried out in seawater and in a 0.01M NaCl solution. The influence of calcium, magnesium, sodium, and potassium ions on the extent of depression by kaolinite is evaluated. The micro-flotation results indicate that chalcopyrite is depressed by kaolinite in both 0.01 NaCl solution and seawater. In the 0.01 NaCl solution, the depressing effect of kaolinite decreases as the pH increases from 8 to 11. However, the results obtained using seawater show that the depressing effect of kaolinite is similar to what is observed in a 0.01 NaCl solution only at pH values below 9, but above this pH kaolinite significantly affects the recovery of chalcopyrite. The results from experiments with using solutions containing individual cations show that the depressing action of kaolinite in the presence of Mg2+ and Ca2+ is more obvious at pH values of 9 and 10, respectively, which correlates with the pH values at which the first hydroxy-complexes of these divalent cations start forming. This seems to indicate that depressing effect of kaolinite on chalcopyrite in seawater may be related to formation of hydrolyzed species of calcium and magnesium. These species can induce heterocoagulation between kaolinite and chalcopyrite. The trends observed in the micro-flotation experiments are in good agreement with the results of the induction time measurements and slime coating tests.

2

Effect of seawater main components on frothability in the flotation of Cu-Mo sulfide ore

Laskowski J. S., Castro S., Ramos O.

Physicochemical Problems of Mineral Processing

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2014

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Vol. 50, iss. 1

17--29

EN

The main problem in the flotation of Cu-Mo sulfide ores in seawater is poor floatability of molybdenite at pH>9.5. Froth stability plays a very important role in determining concentrate grade and recovery in flotation operations and in this paper both floatability and frothability have been tested. The frothability have been studied by measuring froth equilibrium layer thickness in a modified laboratory flotation cell. Two chemical aspects of seawater need to be considered: the content of NaCl (around 87% of salinity), and the concentration of secondary ions (around 13%) (sulfate, magnesium, calcium, bicarbonate ions, etc.). Seawater, NaCl solutions, and seawater’s ions were found to depress frothability. The effect of pH on frothability over the pH range from 9.5 to 11, which is very strong in freshwater, becomes negligible in seawater and the tested electrolyte solutions. The analysis of the relationship between the mechanisms of molybdenite depression and the loss of frothability in seawater implies that the effects of the studied ions on molybdenite floatability and on pulp frothability are different. While depression of molybdenite floatability could be tracked down to magnesium hydroxide precipitation as a main culprit, the depression of frothability is a much more complicated issue.

3

The use of ultra-flocculation in optimization of the experimental flocculation procedures

Rulyov N. N., Laskowski J. S., Concha F.

Physicochemical Problems of Mineral Processing

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2011

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Vol. 47

5-16

EN

The use of sea water in the flotation of Cu-Mo sulfide ores requires better understanding of the effect of electrolyte concentration on performance of flocculants used in the solid/liquid separation unit operations. This paper deals with optimisation of the experimental procedure that will be used in studying the effect of sea water on flocculation. In the tests reported in this paper the tailings from one of Chile major flotation plants were subjected to the flocculation tests with Orifloc-2010 polyacrylamide in a Couette type reactor. It was shown that the flocculation efficiency can be dramatically improved by optimising the shear rate in the reactor, and that the procedure based on the ultra-flocculation can be used as a standardized experimental procedure in testing flocculants.

4

Use of pelletization to assess the effect of particle-particle interactions on coal handleability

Holuszko M. E., Laskowski J. S.

Physicochemical Problems of Mineral Processing

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2004

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Vol. 38

23-35

EN

Although there is no widely accepted rigorous definition of handleability, the handling coal characteristics often referred to as handleability define whether a coal has the ability to flow unhindered through the processing and transportation systems. The handleability may be severely affected if fine coal particles tend to aggregate. In the pelletization process, the rolling action of the drum is applied to bring the individual particles into proximity with each other so that they can aggregate and form pellets. Because of apparent similarities between these two processes, the pelletization tests are carried out in parallel to the handleability tests in this project, and the pelletization results are used to explain coal handleability properties.

PL

"Coal hadleability", termin, którego polskim odpowiednikiem jest "podatność transportowa węgla", charakteryzuje przepływ węgla przez różne węzły technologiczne i opisuje zachowanie się drobnego węgla podczas transportu, składowania i dozowania. Podatność transportowa węgla zależy w bardzo dużym stopniu od agregacji ziarn węgla. W procesie peletyzacji ruch obrotowy bębna/dysku powoduje stykanie się drobnych ziarn, które w wyniku tego mogą tworzyć kuliste pelety. Ta sama podatność ziarn do tworzenia agregatów w trakcie ich transportu powoduje agregację ziarn, co zasadniczo wpływa na podatność transportową takiego materiału. W tej pracy badano równolegle podatność transportową różnych próbek węgla i peletyzację tych próbek. Wyniki peletyzcji zostały użyte do scharakteryzowania właściwości drobnego węgla, które określają jego podatność transportową.

5

Testing flotation frothers

Laskowski J. S.

Physicochemical Problems of Mineral Processing

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2004

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Vol. 38

13-22

EN

In practice, fothers are selected following general guidelines and verification by laboratory and/or plant tests. The terms "powerful" or "selective," which are commonly used to characterize frothers, have intuitive rather than scientific meaning. A research program has been set out to study fundamental properties of the flotation frothers and to identify the tests which can provide information needed to characterize and classify such flotation agents. Since flotation frothers are used to reduce bubble size and increase froth stability, in the procedures adopted in this paper they were characterized by their ability to reduce bubble size in a flotation cell and to increase foam stability. It has been shown that the developed frother classification system based on these two measurements is able to correctly distinguish the frothers known as being selective from those which are known to be powerful.

PL

W praktyce odczynniki pianotwórcze (spieniacze) dobierane są zgodnie z ogólnymi zasadami i sprawdzone w testach laboratoryjnych oraz przemysłowych. Określenia takie jak: "mocne" lub "selektywny" są powszechnie stosowane dla scharakteryzowania spieniacza. Mają one znaczenie raczej intuicyjne niż naukowe. Został przyjęty program badawczy dla zbadania podstawowych właściwości odczynników pianotwórczych stosowanych w flotacji, oraz dla ustalenia testów, które dostarczą koniecznych informacji potrzebnych dla scharakteryzowania i klasyfikacji odczynników pianotwórczych. Odczynniki pianotwórcze stosowane są w celu redukcji rozmiarów pęcherzyków i wzrostu stabilności. Procedury, jakie użyto w tej pracy, były weryfikowane przez ich zdolność do charakteryzowania redukcji wielkości pęcherzyków w komorze flotacyjnej i wzrostu stabilności piany. Zostało pokazane, że system klasyfikacji spieniaczy, bazujący na dwóch zaprojektowanych parametrach, jest w stanie poprawnie rozróżniać spieniacze zwane jako "selektywne" od tych, które znane są jako "mocne".