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Effective circulating load ratio in mill circuit for milling capacity and further flotation process : lab scale study

100%

Pural Y. E. , Çelik M. , Özer M. , Boylu F.

Physicochemical Problems of Mineral Processing

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2022

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tom Vol. 58, iss. 5

art. no. 149916

EN

The design of the grinding circuits and the control of the transferring load in the ore preparation plants are of great importance from a technical and economic point of view. The importance of the circulating load for grinding process is well known and stated in the literature. However, there are not many studies on the effect on the following processes. In this study, the effect of the circulating load on both the grinding capacity and the subsequent flotation process was investigated at laboratory scale. Copper ore was used in the experiments. The circulating load was adjusted by changing the residence time of the material in the mill. Then, flotation experiments were carried out with the materials obtained at different circuit loads. The results showed that the grinding capacity can be increased up to 180% by optimizing the circulating load and it will positively affect the flotation performance. It was observed that a concentrate with the highest recovery for the same Cu grade was obtained with CLR of 150 % when compared to flotation recoveries through various CLRs. It is suggested that the circulating load should not be evaluated only in terms of the grinding process, but also the subsequent processes should be considered. Future studies in this area may contribute to industrial applications.

2

Effect of blunging process on purification of halloysite ore from ferrous impurities by dry magnetic separation

100%

Durgut E. , Çınar M. , Boylu F. , Ozdemir O.

Physicochemical Problems of Mineral Processing

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2024

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tom Vol. 60, iss. 2

art. no. 187186

EN

The objective of this research is to study the effects of feed particle size, splitter angle, and washing process on Fe2O3 removal efficiency in the separation of ferrous impurities from halloysite ore by dry magnetic separation in order to increase the purity of halloysite sample after crushing and blunging processes separately. Firstly, after crushing ore in a jaw crusher and sizing to -2+1 mm, -1+0.5 mm, and -0.5+0.212 mm fractions, the sized materials were fed to REMS-type dry magnetic separator at a constant belt speed of 300 rpm with the splitter angles of 0, 15, 30º separately. Maximum Fe2O3 removal efficiency (FRE) (97.1%) was obtained in the nonmagnetic product at -0.5+0.212 mm size fraction and 0º splitter angle. The minimum Fe2O3 content (1.3%) was reached in the nonmagnetic product obtained in the experiment with the feed size of -2+1 mm and a splitter angle of 0º. Secondly, dry magnetic separation was applied to the washed -2+0.212 mm size fraction after drying at room temperature to evaluate the coarse particle-sized halloysite ore that was gained by mechanical dispersion in the aqueous medium towards sodium hexametaphosphate (SHMP), while a significant part of the clay minerals went into fine size after the dispersion process. In the experiment performed with a 0º splitter angle after washing, it was determined that halloysite concentrate of 0.4% Fe2O3 content could be obtained with 98.8% Fe2O3 removal efficiency. As a result of dry magnetic separation experiments, it was seen that Fe2O3 removal efficiency decreased as the splitter angle increased, while Fe2O3 content in magnetic and nonmagnetic products increased. It was determined that washing and cleaning of finesized minerals plastered on particle surfaces after mechanical dispersion and particle release of minerals with different magnetic properties increased the dry magnetic separation efficiency, and nonmagnetic products with very low Fe2O3 (0.4%) and high Al2O3 (31.9%) content was obtained. The blunging process in the presence of dispersant caused the dispersion of clay minerals and allowed to liberating of the ferrous minerals from the halloysite ore, hence the increase in the FRE for the magnetic separation.

3

Bubbling properties of frothers and collectors mix system

75%

Batjargal K. , Guven O. , Ozdemir O. , Karakashev S. I. , Grozev N. A. , Boylu F. , Çelik M. S.

Physicochemical Problems of Mineral Processing

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2022

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tom Vol. 58, iss. 5

art. no. 152890

EN

This paper studies the effect of the type and concentration of selected frothers and collectors mix system on the bubble sizes (Sauter mean diameter, SMD) of bubbling flow produced in a micro flotation cell and the determination of bubble size distribution (BSD). The usage of dodecyl amine hydrochloride (DAH) collector on the critical coalescence concentration of commercial frothers PPG200, PPG400, and PPG600 was investigated in detail. The results of these studies showed that the usage of DAH decreased the CCC of these frothers. Each frother + collector mixing system exhibited its unique ability in preventing coalescence of the bubbles in the order of PPG200 < PPG400 < PPG600. The factorial experiments established that the type of the frother, collector, and their concentration had a major effect on the size of the bubbles. The BSD in the presence of PPG600 + DAH mix system resulted in a little bit wider BSD which indicated the effect of frother type in mixed systems.

4

Physical restrictions of the flotation of fine particles and ways to overcome them

63%

Karakashev S. I. , Grozev N. A. , Ozdemir O. , Guven O. , Ata S. , Bournival G. , Batjargal K. , Boylu F. , Hristova S. , Çelik M. S.

Physicochemical Problems of Mineral Processing

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2022

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tom Vol. 58, iss. 5

art. no. 153944

EN

This work analyses the basic problems of the fine particles flotation and suggests new ways to overcome them. It is well accepted that the poor recovery of fine particles is due to the small collision rate between them and the bubbles due to the significant difference between their sizes. This common opinion is based on a theory, assuming in its first version a laminar regime, but later has been advanced to intermediate turbulence. It accepts that the particles are driven by the streamlines near the bubbles. In reality, the high turbulence in the flotation cells causes myriads of eddies with different sizes and speeds of the rotation driving both bubbles and particles. Yet, a theory accounting for high turbulence exists and states that the collision rate could be much higher. Therefore, we assumed that the problem consists of the low attachment efficiency of the fine particles. Basically, two problems could exist (i) to form a three-phase contact line (TPCL) the fine particle should achieve a certain minimal penetration into the bubble, requiring sufficient push force; (ii) a thin wetting film between the bubble and the particle forms, thus increasing the hydrodynamic resistance between them and making the induction time larger than the collision time. We assumed particles with contact angle θ = 80°, and established a lower size flotation limit of the particles depending mostly on the size of the bubbles, with which they collide. It spans in the range of Rp = 0.16 um to Rp = 0.40 um corresponding to bubbles size range of Rb = 50 um to Rb = 1000 um. Hence, thermodynamically the particle size fraction in the range of Rp = 0.2 um to Rp = 2 um are permitted to float but with small flotation rate due to the small difference between the total push force and maximal resistance force for formation of TPCL. The larger particles approach slowly the bubbles, thus exceeding the collision time. Therefore, most possibly the cavitation of the dissolved gas is the reason for their attachment to the bubbles. To help fine particles float better, the electrostatic attraction between bubbles and particles occurred and achieved about 92% recovery of fine silica particles for about 100 sec. The procedure increased moderately their hydrophobicity from θ ≈ 27.4° to θ ≈ 54.5°. Electrostatic attraction between bubbles and particles with practically no increase of the hydrophobicity of the silica particles ended in 47% recovery. All this is an indication of the high collision rate of the fine particles with the bubbles. Consequently, both, an increase in the hydrophobicity and the electrostatic attraction between particles and bubbles are key for good fine particle flotation. In addition, it was shown experimentally that the capillary pressure during collision affected significantly the attachment efficiency of the particles to the bubbles.