Güven Önal

New aspect of chromite gravity tailings re-processing

Abstract Karagedik Chromite Concentrator of the ETI Holding Co., which is located in Fethiye (south Turkey), has been producing chromite concentrate assaying 47–48 % Cr2O3 from chromite ores containing 30–35 % Cr2O3 by gravity separation methods since 1920. The tailings, containing 13–14 % Cr2O3, which had been removed from this plant, were accumulated at stockpiles, amounting to about 1.2 million tons. Generally, at the chromite concentrators of Turkey, such as Karagedik Concentrator, ultra fine size chromite particles (minus 0.038 mm.) were removed as tailings. Likewise, the tailings of the Karagedik concentrator contain a minus 0.038 mm fraction amounting to 42 % of the total. The Cr2O3 content of this size faction is about 23 % with Cr2O3 distribution of 76 %. In order to recover the ultra fine chromite particles from the Karagedik Concentrator tailings, a new process, including Wet High Intensity Magnetic Separation and column flotation, was developed and the Karagedik Research Pilot Plant based on this process was commissioned in 1999. At this plant, final concentrates, assaying 46–48% Cr2O3 are produced and overall plant recoveries are about 60–65%.

Beneficiation of fine coal by using the free jet flotation system

Abstract The free jet flotation system was developed at the Berlin Technical University in 1985. This system was able to treat ultrafine particles of about −53 μm. In the present study, the fine size fraction of the coal (−0.5 mm) containing 45% ash taken from the Zonguldak Central Washery Plant (ZCWP) of Turkish Hard Coal was beneficiated by using the free jet flotation system. In the flotation tests, the best results were obtained in the case of using a mixture of 90% kerosene and 10% iso-octanol in the amount of 400 g/ton as a collector. Also, the optimum system parameters of a 30 l free jet type flotation (FJFT) cell used in this study were determined from the results of systematic tests. In the optimum free jet flotation conditions, the floating coal containing 18.73% ash with a combustible recovery of 72.4% was obtained.

RECOVERY OF Co, Ni, AND Cu FROM THE TAILINGS OF DIVRIGI IRON ORE CONCENTRATOR

In the Sivas-Divriği Iron Ore Concentrator, 600,000 t of tailings are discarded annually. There are already 1 million t of tailings deposited in ponds from the previous production activities. The presence of Co, Ni, and Cu in the tailings makes the beneficiation of those tailings attractive. In the experimental work, sulphide concentrates were produced from these two types of tailings by flotation. Under optimum flotation conditions, a bulk sulphide concentrate assaying 0.376% Co, 0.721% Ni, and 0.403% Cu was obtained with 83.1% Co, 57.7% Ni, and 59.0% Cu recoveries from the old tailings. On the other hand, another concentrate containing 0.384% Co, 0.687% Ni, and 0.393% Cu was produced under the same flotation conditions with 94.7% Co, 84.6% Ni, and 76.8% Cu recoveries from the new process tailings.

A new flowsheet for processing chromite fines by column flotation and the collector adsorption mechanism

Tailings produced from Uckopru Chromite Concentrator are composed of fines mostly below 1 mm of which 52.3 wt. % is below 0.1 mm. A new flow sheet involving shaking table for processing −1 + 0.1 mm size fraction, and High Intensity Wet Magnetic Separator (HIWMS) and column flotation for treating -0.1 mm size fraction was put forward. According to the new ffowsheet, the Uckopru Concentrator tailings assaying 13.99 wt. % Cr2O3 was upgraded to 47.4 percent Cr23 at a recovery of 66.4 wt. % using shaking table followed by a combination of magnetic separation and column flotation with a mixture of anionic collectors at pH 11. The success of such high pH with anionic surfactants is indeed intriguing. Electrokinetic methods were used to elucidate the mechanism of collector adsorption and correlate the findings with the optimum flotation conditions. Multivalent constituent ions such as Cr3+, Al3+, Fee+ and Mg2+ were found to adsorb on chromite surface and shift the iep of chromite in the direction of oxide form of the mineral. The anionic collectors also imparted a negative charge to chromite in the entire pH region. The positive sites on the chromite surface, onto which anionic collectors adsorb, are generated through the formation of significant amounts of hydroxy complexes of magnesium ion at pH 11. Complementary infrared data reveals the absence of a shift in the spectra indicating the possibility of physical adsorption in the system.

Sedimentation of clay in ultrasonic medium

It is well known that ultrasonic field is generally used in the cleaning of metal surfaces. Recently, there have been some attempts for the use of ultrasonic treatment in the mineral industry, especially in flotation and separation of fine particles from gases or liquids. Ultrasonic energy is used as a first time in the sedimentation of clay in this study. Laboratory scale sedimentation experiments are performed in natural and ultrasonic media in order to determine the sedimentation characteristics of clay samples in different settling environments. The effects of several parameters such as pulp density, flocculant addition and ultrasonic treatment on the sedimentation of clay are investigated and the optimum settling conditions are determined. It is found that ultrasonic treatment, applied during the sedimentation, positively affected the sedimentation of clay and increased the settling rates by lowering the settling time.

Beneficiation of the gold bearing ore by gravity and flotation

Gold concentration usually consists of gravity separation, flotation, cyanidation, or the combination of these processes. The choice among these processes depends on the mineralogical characterization and gold content of the ore. Recently, the recovery of gold using gravity methods has gained attention because of low cost and environmentally friendly operations. In this study, gold pre-concentrates were produced by the stepwise gravity separation and flotation techniques. The Knelson concentrator and conventional flotation were employed for the recovery of gold. Gold bearing ore samples were taken from Gümüşhane Region, northern east part of Turkey. As a result of stepwise Knelson concentration experiments, a gold concentrate assaying around 620 g/t is produced with 41.4wt% recovery. On the other hand, a gold concentrate about 82 g/t is obtained with 89.9wt% recovery from a gold ore assaying 6 g/t Au by direct flotation.

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.

Improved Fine Coal Dewatering by Ultrasonic Pretreatment and Dewatering Aids

The effects of ultrasonic pretreatment and surface active reagents to improve the efficiency of fine coal dewatering in high frequency vibrating screen have been carried out. The results showed that hydrophobic surface active reagents increased the contact angle and decreased surface tension of the solution reducing the moisture content of fine coal particles. Polyethylene glycol 400 monooleate (PEG-400) was found to be the most effective reagent. Furthermore, when ultrasonic pretreatment was introduced to the fine coal slurry, the residual total moisture content of the fine coal was further decreased.

PROCESS FLOWSHEET DEVELOPMENT FOR BENEFICIATION OF NICKEL ORE

Nickel sulphide ore subjected to this investigation was taken from the Marmara district of Turkey, where widespread chromite mineralization can be observed. Some amounts of magnetite and chromite exist in the ore together with sulphide and oxide type nickel minerals. The ore sample contains 1.32% Ni, 10.79% SiO2, 78.39% Fe2O3, 1.3 g/t Ag, and 1.0 g/t Au. The ore sample is constituted of about 70% magnetite, 15% sulphide minerals, and 5% chromite and iron oxides, as well as 10% gangue minerals. Nickel mineralization in the ore such as pentlandite, violarite, millerite awaruite, and asbolanewas determined. Due to the complex structure of mineralization, a combination of gravity-separation and flotation methods was applied for the concentration of nickel sulphide and oxide ores. A nickel concentrate containing 12.32% Ni was produced with 89.7% recovery and final tailings with 0.088% Ni can be disposed with 4.9% of metal loss. A process flowsheet was developed according to the optimum test results. The importance of this research is that it is the first example of developing a flowsheet for the beneficiation of sulphide and oxide type nickel mineralization observed together in chromite ore deposits.

BRIQUETTING OF FINE SIZE ASPHALTITE WITHOUT BINDER

ABSTRACT In this study, the effects of particle size, moisture, briquetting pressure, and preheating temperature were investigated on briquetting without binder of Sırnak Asphaltite, having a particle size of—20 mm, 46.22% ash, 5.83% total sulphur content, and 4900 kcal/kg calorific value. At the end of the briquetting experiments; mechanical strength values of briquettes produced in optimum conditions (particle size, − 1 mm; moisture, 3.6%; pressing value, 4 t/cm2; amount of lime, 12%) have the properties of first-class briquettes according to Turkish standards. The mechanical strength values of produced briquettes were affected positively in optimum conditions with preheating to 80°C. In combustion experiments using an upper burning stove, the combustion efficiency of briquettes, which contain 50.54% ash, 16.08% fixed carbon, 33.38% volatile matter, and 4.80% total sulphur have been calculated as 60%. During the combustion, sulphur content in smoke gas and particle emissions were determined as 2.34% and 3 mg/m3, respectively.