Evaluacion de Parametros de Una Celda Jameson

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Optimization of design and operating parameters in a pilot scaleJameson cell for slime coal cleaning

Hasan Hacifazlioglu , Ihsan Toroglu 1

Department of Mining Engineering, University of Karaelmas, 67100, Turkey

Received 13 December 2006; received in revised form 7 March 2007; accepted 15 March 2007

Abstract

TheJamesonflotation cell hasbeen commonly used to treat a variety of ores (lead, zinc, copper etc.),coal andindustrialmineralsat commercial scalesince 1989. It is especially known to be highly efficient at fine and ultrafine coal recovery. However, although the Jameson cell has quite a simplestructure, it maybe largely inefficient if the design andoperating parameters chosen arenot appropriate. In thisstudy, the design and operating parametersof a pilot scale Jameson cell were optimized to obtain a desired metallurgical performance in the slime coal flotation. The optimized design parametersare the nozzle type, the height of the nozzle above the pulp level, the downcomer diameter and the immersion depth of the downcomer. Among theoperating parameters optimized are the collector dosage, the frother dosage, the percentage of solids and the froth height. In the optimum conditions, aclean coal with an ash content of 14.90% was obtained from the sampleslime having 45.30%ash with a combustible recovery of 74.20%. In addition, anew type nozzle was developed for the Jameson cell, which led to an increase of about 9% in the combustible recovery value.Crown Copyright 2007 Published by Elsevier B.V. All rights reserved.

Keywords: Jameson cell; Coal slime; Froth flotation; Downcomer; Nozzle

1. Introduction

Froth flotation is the most widely used method for fine coalbenefication and approximately 142 million tonnes of fine coalsare beneficiated by flotation worldwide annually [1,2]. Prior to1980s the most popular flotation devices were conventionalmechanical cells. However, some disadvantages involving highash entrainment, formation of coarse bubbles and low carryingcapacity have made it impossible to get coal with the desiredyieldand ash content. In the last few decades, many new technologyflotation devices such as Microcel column, Cyclo-microbubblecolumn, Pneumatic cell, Contact cell, Centrifloat, ASH, Hydrojet,LM cell and Jameson cell have been developed as alternatives tomechanical flotation cells [311].

The Jameson cell was developed jointly by Mount Isa Minesand Prof. G.J. Jameson of the University of Newcastle in the late1980s. It is a high intensity and high efficiency flotation device,

which uses induced air from atmosphere. In this technology, air isabsorbed from the atmosphere into the downcomer through theinfluence of the jet action caused by the highly pressurized pulp.This innovative flotation device can produce very fine bubbles(0.3 mm) without a compressor or an impeller mechanism.Compared with the conventional cells, the main advantages of theJameson cell include high production capacity, excellent separa-tion ability, long mechanical life, flexible cell design, low capitaland operating cost. In its first industrial application it was used asan alternative to the conventional column for base metal flotation

by MIM in Australia in 1989. The success in this applicationopened the way for studies on coal applications. The first Jamesoncell was installed in the Newsland Coal Handling and PreparationPlant (Australia) in 1990 for coal slime treatment. [6,12,13].

Fuel Processing Technology 88 (2007) 731736www.elsevier.com/locate/fuproc

Corresponding author. Tel.: +9 0372251107, +9 05557182553 (mobile).E-mail addresses: [email protected] (H. Hacifazlioglu),

[email protected] (I. Toroglu).1 Tel.: +9 0372251107.

Table 1Chemical analysis of the coal sample (dry basis)

Ash (wt.%) 45.30Volatile matter (wt.%) 20.80Fixed carbon (wt.%) 33.90Total sulfur (wt.%) 0.76Upper calorific value (kcal/kg) 4350

0378-3820/$ - see front matter. Crown Copyright 2007 Published by Elsevier B.V. All rights reserved.doi:10.1016/j.fuproc.2007.03.003
mailto:[email protected]:[email protected]://dx.doi.org/10.1016/j.fuproc.2007.03.003http://dx.doi.org/10.1016/j.fuproc.2007.03.003mailto:[email protected]:[email protected]


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Today, there are over 250 Jameson cells around the world used incoal, base metals, SXEW and industrial minerals [14].

Although the Jameson cell has a simple structure, there aresome important things in its design that must be put intoconsideration; for example, the height of the nozzle above the

pulp level, the immersion depth of downcomer and the ratio ofthe downcomer diameter to that of the cell are important factors

that play a major part in the cell performance. In a studyconducted by Gney et al. [15] in which they used a Jet flotationcell (similar to Jameson cell) to beneficate Zonguldak (Turkey)fine coal, the optimum nozzle height was 5 cm and theimmersion depth was 20 cm. In the end, they obtained a cleancoal with an ash content of 18.73% with a combustible recoveryof 72.40% from feed coal having 44.83% ash. As for the ratio ofthe downcomer diameter to that of the cell, Xstrata Technology[14] recommends a downcomer of 100 mm in diameter for a cellhaving a diameter of 500 mm. In this case, the optimum ratio ofthe downcomer diameter to that of the cell is 0.2.

In recent times, studies aimed at improving the performanceof the Jameson cell have focused on the nozzle (or orifice)systems, because the performance of the Jameson cell largelydepends on the energy of the jet created by the slurry passingthrough the nozzle. By increasing the energy of the jet (i.e. high

jet velocity), both the bubble-particle collision and the number of

bubbles increased leading to high flotation efficiency. A specialnozzle developed by Xstrata Technology has made it possible toincrease the energy of jet at a constant feed pressure. By the useof this nozzle referred to as Slurry Lens Orifice, the powerconsumption of the pump has decreased by 1015%. In theexperimental studies carried out within the scope of this study, itwas observed that the nozzle type had a great effect on theflotation performance of the Jameson cell. Therefore, investiga-tions were conducted, which aimed at the most appropriatenozzle type in order to maximize the combustible recovery valueusing three different nozzle types. As an alternative to theconventional one-hole nozzle, a moon type nozzle was deve-

loped, which is mentioned here for the first time. By using themoon type nozzle both, combustible recovery and ash rejectionincreased significantly due to dual jet forming in the cell.

Other parameters affecting the performance of the Jamesoncell relate to operating conditions: these are the dosage offrother and collector, the percentage of solids and the frothheight. In a Jameson cell, generally the optimum dosage offrother added to the feed varies from 200 to 400 g/t, with thecollector dosage ranging between 500 and 2000 g/t. The

percentage of solids in the pulp varies depending on the particlesize distribution of coal treated and it is usually 4% in slime

Table 2The distribution of ash and combustibles in the size fractions

Size fraction (m) Weight (%) Ash content (%) Combustible recovery (%)

+150 4.63 7.60 7.82150 106 4.67 5.45 8.07106 75 6.22 5.90 10.70

75 53 7.54 20.30 10.4953 38 7.67 25.20 10.5038 69.27 58.99 51.93Total 100.00 45.30 100.00

Fig. 1. The schematic view of a pilot scale Jameson flotation cell system.

732 H. Hacifazlioglu, I. Toroglu / Fuel Processing Technology 88 (2007) 731736


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coal flotation and 7% in fine coal flotation. The froth height isusually 2060 cm in many applications and can vary dependingon the desired product ash. Low froth height results a high

product ash and the reverse gives rise to a reduced recovery dueto the increased probability of particles dropping back from thefroth to the pulp [1319].

2. Experimental

The coal sample used in the flotation experiments was col-lected from a thickener underflow stream of a coal preparation

plant treating the Zonguldak seam in Turkey. The results of thechemical analysis of the test sample are given in Table 1. Inaddition, the distributionof ash and combustibles according to thesize fractions is given in Table 2.

Fig. 1 shows the pilot scale Jameson flotation cell installed inthe Mineral Processing Laboratory at Zonguldak KaraelmasUniversity. The system consists of a conical cell 130 cm in heightand 54cm in diameter, a conditioner of 0.3 m3 in volume, a circular

downcomer and a 2 kW feed pump. In the system, the conditionedpulp is fed into the cell by passing it through the nozzle with a pulppressure of 130 kPa. Air is absorbed from the atmosphere into thedowncomer where it is mixed with the pulp. Then, the pulp/airmixture passes downwards into the cell and bubbles disengage toconstitute a froth layer which bears the floated coal.

In this study, a test program was conducted to evaluate andoptimize the Jameson cell design and operating parameter valueswith the goal of maximizing recovery of combustible materialover a range desired product ash content value. Table 3 shows theinitial Jameson cell design and operating parameter values used atthe beginning of the flotationtests. First of all, the optimum nozzle

type was determined. Then, the optimum height of the nozzleabove the pulp level, the optimum depth to which the downcomeris immersed and the optimum downcomer diameter were

determined. After these, the optimum values of the operatingparameters the dosage of frother andcollector, the percentage ofsolids, and the froth height were investigated. Each optimumresult was used in subsequent experiments and the Jameson cellgained its ultimate optimization.

3. Results and discussion

3.1. Optimization of Jameson cell design parameter values

In order to determine optimum nozzle type, 3 different typenozzles were tested in the Jameson cell. The diagramsrepresenting their cross sections are given in Fig. 2, with a

being the type used in a Jameson cell and b employed in a jetflotation system [15,18]. As for the moon type nozzle, which ismentioned in this paper for the first time, it is a novel nozzletype whose performance has been well established after a longtime of research. It is, in a sense, a nozzle type combining the

classic and one-hole types. As shown in Fig. 3a, the maximumcombustible recovery value was obtained using the moon typenozzle. While tests conducted using the classic nozzle led to65.15% combustible recovery, a 72.00% combustible recoverywas achieved with the moon type. It was also proved to be moresuccessful in ash rejection. This is because the moon typenozzle produces a right-and-left dual jet action. Owing to thedouble jet action, there is not only a decrease in the turbulencein the froth zone but also an increase in the number of bubblesforming. In contrast, in the conventional nozzle system, the pulpejected from the single hole increases the turbulence in the frothzone and is only effective in the center of the cell. Therefore,excessive turbulence in the center created by the conventional

nozzle caused both an increase in product ash and a decrease inthe combustible recovery value.

The nozzle height is another important design parameterwhich affects on flotation performance of the Jameson cell.When the nozzle height exceeded 20 cm, intensive turbulenceand froth swelling were observed in the froth zone. Accordingly,at a height of 40 cm, a product with the highest ash content(21.10%) was obtained. In the case of the height less than 10 cm,the combustible recovery value fell to 60%. This was becausethepulpinthedowncomerrosesoastoimmersethenozzleinthe

pulp, thus suppressing the jet action. This suppression had anadverse effect on the bubble size distribution and amount in the

pulp and the recovery of coal particles decreased (Fig. 3b).The best flotation performance was obtained when the

immersion depth of the downcomer was 10 cm. Low immersion

Fig. 2. Nozzle types tested in the Jameson flotation cell experiments.

Table 3Jameson cell design and operating parameter values used at initial flotation tests

Percentage of solids 6Collector (Kerosene) 1 kg/t Frother (iso-octanol) 400 g/t Froth height 10 cmFeed pressure 130 kPa

Wash water rate 4 L/minNozzle type Moon typeNozzle height 20 cmImmersion depth 20 cmDowncomer diameter 12 cm

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depths (b10 cm) have a negligible effect on the flotation per-formance, whereas, at high immersion depths (N30 cm), there is

an increase in the ash recovery as opposed to a decrease in thecombustible recovery value. If the immersion depth is veryhigh, the pulp rises to the nozzle level in the downcomer and

brings about the suppression mentioned above. This is due tothe fact that the air sucking orifice is fixed and the air suckedthrough it becomes insufficient over time. In conclusion, if thedowncomer is immersed too much, a greater amount of air issucked (Fig. 3c).

The most suitable downcomer diameter for a cell 54 cm indiameter was found to be 15 cm. Using a downcomer 6 cm indiameter, the combustible recovery value fell to around 40%. Onthe other hand, though great downcomer diameters (N12 cm) ledto cleaner products, there was a decrease, if not considerable, inthe combustible recovery. This is attributable to the fact that the

downcomer with a greater diameter takes up more space on thecell surface (Fig. 3d). As a result, the optimum ratio of the

downcomer diameter to that of the cell was 0.27.

3.2. Optimization of Jameson cell operating parameter values

Under the conditions in given Table 3 and using optimumdesign parameters, the dosage of frother and collector, the

percentage of solids in the pulp, and froth height were optimized.These parameters varied during the experimental program overthe range of 200 to 600 g/t, 0.5 to 2.5 kg/t, 2 to 10% and 5 to25 cm, respectively.

Iso-octanol and kerosene were selected as the frother andcollector because they are readily available. The iso-octanol is analcohol type frother and enables the production of smaller air

bubbles and stabilization of the froth zone. Kerosene collector

Fig. 3. The effect of design parameters nozzle type, nozzle height, immersion depth and downcomer diameter on flotation performance of the Jameson cell.



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whichis a non-polar oil is used to promote the rigid adhesion of airbubbles to the coal surface. As seen in Fig. 4a, when the iso-octanol dosage increased from 200 to 400 g/t while the collectordosage was maintained constant at 1 kg/t, the combustiblerecovery value increased from 60.33% to 74.80%. However, athigh frother dosage (e.g. 600 g/t) the combustible recovery didn't

change much but the product ash content increased significantlydue to the ashentrainment. The same is true for kerosene addition.At the dosage of kerosene over 1.5 kg/t, the product ash increasedconsiderablybutcombustiblerecoveryremained almost thesame.As a result, the optimum dosages ofiso-octanol and kerosene forcoal slime flotation in the Jameson cell are 400 g/t and 1.5 kg/t,respectively (Fig. 4a and b).

The optimum percentage of solids in the pulp was determinedto be 4%. When the percentage of solids was increased from 4 to10, the combustible recovery value drastically decreased from74.80% to 56.45%. In addition, the highest product ash (20%)was obtained at the solid rate of 10% (Fig. 4c).

In the Jameson flotation cell, the rejection of entrained ash

particle depends on the froth height and wash water flow(constant at 4 L/min). If the froth is not high enough, ash

particles will be carried into the froth product and thus the ashcontent of product will increase. If the froth is high enough, the

probability of particles dropping back from the froth to the pulpwill increase and results in the froth product being furthercleaned. As seen in Fig. 4d, with the increase of the froth height

Fig. 4. The effect of operating parameters frother and collector dosage, percentage of solids and froth height on flotation performance of the Jameson cell.

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both product ash and combustible recovery decreased. As aresult, it appears that a froth height of 4 cm is appropriate toachieve both high combustible recovery and low ash product.

4. Conclusions

The optimum design and operating parameter values for aJameson cell 130 cm in height and 52 cm in diameter wereinvestigated for Zonguldak (Turkey) bituminous coal slime to becleaned in the best way. The findings obtained are summarized inFig. 5. Moreover, a more efficient nozzle was developed as analternative to the conventional nozzle used in a Jameson cell. Thenozzle referred to as moon type increased the combustiblerecovery by approximately 9%. In conclusion, the ash content ofthe sample coal was reducedfrom45.30% to14.90% with74.40%combustible recovery by using the pilot scale Jameson cell.

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Fig. 5. The schematic view of the Jameson cell with its optimum design and operating parameters.

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Evaluacion de Parametros de Una Celda Jameson

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