Investigation of spherical oil agglomeration properties of celestite

https://doi.org/10.1016/j.jcis.2003.12.001Get rights and content

Abstract

In this study, concentration of celestite particles was investigated by using oil agglomeration. For this purpose, effects of operating parameters were investigated, and zeta potential measurements and Fourier transform infrared spectrophotometry (FTIR) analyses have also been carried out. In the experiments, effects of operating parameters such as pH, stirring speed, amount of Na oleate as a anionic type collector and kerosene as a bridging liquid, solid ratio, agglomeration time, collector stirring time, conditioning time, and amount of EDTA were investigated to obtain optimum conditions. Zeta potential measurements were carried out for various pH values and amounts of Na oleate. FTIR analyses were investigated to determine the adsorption type of Na oleate on celestite surface. By evaluation of the experimental results, optimum oil agglomeration conditions of celestite were determined as follows: pH 7, stirring speed 1500 rpm, amount of kerosene 100 l/t, amount of Na oleate 10 kg/t, solid ratio 5 wt%, conditioning time 5 min, collector stirring time 1 min, agglomeration time 5 min, and amount of EDTA 1.0 kg/t. In the optimum conditions, celestite was concentrated with recovery of 89.47 wt%.

Introduction

In mineral processing, fine and ultrafine particles are inevitable because of mechanized mining methods, comminution processes, and greater size reduction needed to liberate the minerals [1], [2], [3], [4], [5]. These particles cause numerous problems in both concentration stages and other handling stages such as dewatering, transporting, and dust control. Since the conventional beneficiation techniques (froth flotation and gravity concentration processes) are inefficient in the sub-sieve size range, it has been necessary to develop new methods such as column flotation, carrier flotation, selective flocculation, and oil agglomeration. All of these methods rely on the physicochemical properties of the minerals [6], [7]. Size enlargement processes to upgrade fine particles are assuming ever-increasing importance today because of their relevance to waste treatment, environmental protection, and the efficient recovery and beneficiation of ores and coals [1], [2].

From these methods, oil agglomeration, which advantages due to the simplicity of the process and mineral beneficiation with high recovery, gains importance [1], [2], [8].

Considered from the physicochemical point of view, oil agglomeration is a kind of aggregation [9]. In this process, hydrophobic particles in water are agglomerated by the action of the bridging liquid, which is immiscible with the suspending liquid and must preferentially wet the hydrophobic particles. The agglomerated product can be separated from the suspension by floating, skimming, and screening [1], [2], [8], [9], [10]. Apart from hydrophobic particle agglomeration, oil agglomeration of salt-type minerals has two more stages, namely hydrophobic coagulation and agglomeration of flocs [9].

The principles of the application conditions of oil agglomeration have been investigated by various studies. Most oil agglomeration studies have been performed with naturally hydrophobic particles such as coal [1], [2], [8], [11]. However, there is limited research on agglomeration behavior of salt-type minerals such as barite and calcite [9], [10], [12], [13], [14], [15], [16], [17], [18]. Oil agglomeration conditions of celestite (SrSO4) have not been investigated in detail.

Celestite is the principal and most abundant source of strontium. Celestite is particularly used for production of strontium carbonate, nitrate, and hydroxide.

In this study, agglomeration behavior of celestite has been investigated using a classic flotation reagent (Na oleate) and optimum agglomeration conditions have been determined.

Section snippets

Materials

In this study, a celestite sample taken from Barit Maden Türk A.Ş. in Sivas, Turkey, was used. The sample was ground and sieved to <212 μm for oil agglomeration tests. The particle size distribution and the chemical analysis result of the ground sample are given in Fig. 1 and Table 1, respectively.

Chemicals

In the experiments, Na oleate (C17H33COONa) was used as anionic type collector. Na oleate was prepared from oleic acid (C17H33COOH) (Carlo Erba) and NaOH. Kerosene was used as bridging liquid. It was

The effect of pH

As is known, the agglomeration recovery or the extent of agglomeration depends on the surface properties of the particles and the nature of the agglomerant. The surface properties of the particles are controlled by the pH value of the aqueous medium. Therefore, the control of the pH values of the aqueous medium is primarily important. The effect of the pH values on the oil agglomeration recovery of celestite is given in Fig. 3. In addition, the effect of the pH on the zeta potential of

Conclusions

The conclusions obtained from this study are as follows:

Naturally hydrophilic celestite can be agglomerated with Na oleate as an anionic type collector and kerosene as a bridging liquid.

pH and amount of Na oleate are primarily important.

The oleate adsorption on celestite surface increases the negative zeta potential value.

The reaction between oleate anions and celestite is of chemical type.

The optimum oil agglomeration conditions are as follows: pH 7, stirring speed 1500 rpm, amount of kerosene

Acknowledgements

The authors acknowledge the financial support of this study provided by Cumhuriyet University Research Fund Unit.

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