Fırat Karakaş

Recovery improvement of coarse particles by stage addition of reagents in industrial copper flotation circuit

ABSTRACT Obtaining high recovery in coarse particle size fractions has been always under investigation in recent years. In the present study, stage addition of chemical reagents is used to improve copper grade and recovery of coarse size fractions (i.e., >100 µm) at industrial rougher flotation cells. Due to the poor efficiency of primary grinding circuit, coarse particles were detected as predominate size fraction in rougher flotation feed. Sampling results from rougher tailings showed that 58% of precious copper minerals were distributed to size fraction of −105 + 297 µm. Stage addition of collectors including sodium isopropyl xanthate (Z11), dithiophosphate and mercaptobenzthiazole (Nascol-451), and xanthate-flomin (C-4132) and frothers as methyl isobutyl carbonyl (MIBC) and Aerofroth 65 (A65) were implemented to avoid losing of coarse valuable particles in rougher tailings. Three different patterns were given for stage additions as 75-25-0, 75-0-25, and 75-13-12. The results indicated that copper grade of tailings declined relatively 56% using optimized stage addition of reagents at the head of rougher banks (i.e., 75-13-12). In addition, copper recovery of rougher cells improved around 2%. Size by size analysis of copper recovery for the rougher cells revealed the significant effect of the stage addition of chemical reagents on recovery improvement of coarse particles. GRAPHICAL ABSTRACT

The Effect of Collector's Type on Gold and Silver Flotation in a Complex Ore

Gold and silver are recovered by gravity concentration, cyanidation, or flotation from ores. The choice of those processes depends on the mineralogical characterization as well as gold and silver contents of the ore. Flotation has been applied on ores containing free gold and silver particles for many years. The flotation efficiency of gold and silver particles depends on the modifiers and collectors. This paper presents the results of the effect of different collector combinations on gold and silver recoveries from lead and zinc ores by flotation. Best results were obtained on the use of Aero 208 + Aerophine 3418 A as collectors at the dosages of 350 + 350 g/t and 1000 g/t Na2SiO3 as a depressant at pH 4.5 where particle size was below 38 µm. According to the process, a concentrate assaying 1026.9 g/t Au and 10185 g/t Ag was obtained. On the other hand, a concentrate containing 50.6% Pb was obtained with 39.7% recovery using potassium amyl xanthate (KAX) and aminothiophenol (ATP). This concentrate graded 235 g/t Au and 3740 g/t Ag.

The kinetics modeling of chalcopyrite and pyrite, and the contribution of particle size and sodium metabisulfite to the flotation of copper complex ores

ABSTRACT In this study, a series of batch flotation experiments was conducted to evaluate both the role of particle size distribution and the presence of sodium metabisulfite Na2S2O5 (SMBS) in chalcopyrite and pyrite flotation. Kinetic flotation tests were also carried out in order to evaluate the kinetics behavior of the above-mentioned minerals. Following this, different flotation kinetics models were compared to the data from the experiments. According to the obtained results, it can be stated that feed particle size distribution plays a greater role in chalcopyrite and pyrite grades rather than their recoveries. However, the contribution of SMBS is higher than that of particle size with respect to pyrite recovery. In this study, the maximum recoveries for chalcopyrite and pyrite were found to be 92.2% and 47.5%, respectively. The minimum pyrite recovery (13.47%) occurred in the presence of 40 g/t Xanthate-flomin (C-4132), 20 g/t methyl isobutyl carbonyl (MIBC), 20 g/t polypropylene glycol (F742), 200 g/t sodium metabisulfite (SMBS), and at a d 70 of 70 µm. A comparison between several flotation kinetics models and the experimental data revealed that the perfect mixer and the Arbiter models showed completely similar results for both chalcopyrite and pyrite with respect to the use of different configuration of chemical reagents.

Effect of Coal Moisture on the Treatment of a Lignitic Coal through a Semi-Pilot-Scale Pneumatic Stratification Jig

Dry processing methods are well known to be sensitive to the moisture content of the processed material. It is well known that cohesive forces among the particles originating from the surface moisture hinder the individual movement or appropriate stratification of particles during separation. Furthermore, high surface moisture also hampers the flow of feed material. In this study, the effect of total/surface moisture on separation of lignitic coals was investigated by using Allair stratification jig with the aim of finding possible critical surface moisture content for optimum separation. Coal samples in the size of −13 + 4 and −4 mm were processed at different particle total/surface moisture levels to recover as clean coal concentrate as possible along with obtaining tailings with minimum levels of combustibles. It is envisaged that a critical surface moisture on both classification (effective screening) and separation is available around 5.5% surface moisture (corresponding to 15% total moisture) for −13 + 4 mm whereas effective separation is not possible for the −4 mm size range even at minor changes in surface moisture of particles.

Ultrafine coal flotation and dewatering: Selecting the surfactants of proper hydrophilic–lipophilic balance (HLB)

ABSTRACT Fine and ultrafine coal (−200 µm) enrichment and its further dewatering processes are more difficult than that of coarser sizes. Utilization of this size fraction, however, is inevitable owing to economic and environmental enforcements. Chemical reagents are widely used in fine coal dewatering to achieve lower cake moistures. Surfactants of the same structures are also used effectively in coal flotation within preparation and coal washing processes. These surfactants contain hydrophilic and lipophilic groups, the ratio of which is known as hydrophilic–lipophilic balance (HLB). Flotation separation efficiency and dewatering performance of hard bituminous coal slimes as well as water recovery characteristics and related entrainment degree during the flotation were investigated using eight various nonionic surfactants of different HLB values. The main motivation of the study is to suggest proper reagent properties by which highest efficiency in both flotation and dewatering can be achieved. This can result in significant economic advantages for industrial processes and also reduce the environmental disadvantages of using chemicals. The flotation separation efficiency of the most lipophilic surfactants (lower HLB) and conventional oily collectors were found to be the highest, while the surfactants with moderate HLB (~10) showed the best filtration performance.

Composite Films Based on Styrene-co-butyl-acrylate with Colemanite and Calcium Bentonite Mineral Fillers

Composites are engineered materials made from two or more constituent materials, which remain separate and distinct on the macroscopic level within the finished structure and also with significantly different physical or chemical properties. In recent years, there has been a great interest in polymer/inorganic composites, which stems from their improved properties. Mineral fillers in composites are widely used in industrial applications such as adhesives and paints. They provide better mechanical properties and thermal resistance to the systems and also reduce manufacturing costs. In this study, a comparative evaluation of colemanite and calcium bentonite minerals used as a filler in an aqueous polymer emulsion (styrene-co-butyl acrylate copolymer) is performed. The effect of amount and type of mineral additives on the mechanical properties of composites is investigated. Meanwhile, a comparison between colemanite and calcium bentonite is made on the basis of their different dispersion characteristics in a polymeric matrix. The degree of interfacial interaction between the filler and polymeric matrix is also modeled using the B parameter.