Fırat Burat

Selective separation of virgin and post-consumer polymers (PET and PVC) by flotation method

More and more polymer wastes are generated by industry and householders today. Recycling is an important process to reduce the amount of waste resulting from human activities. Currently, recycling technologies use relatively homogeneous polymers because hand-sorting waste is costly. Many promising technologies are being investigated for separating mixed thermoplastics, but they are still uneconomical and unreliable. At present, most waste polymers cause serious environmental problems. Burning polymers for recycling is not practiced since poisonous gases are released during the burning process. Particularly, polyvinyl chloride (PVC) materials among waste polymers generate hazardous HCl gas, dioxins containing Cl, etc., which lead to air pollution and shorten the life of the incinerator. In addition, they make other polymers difficult to recycle. Both polyethylene terephthalate (PET) and PVC have densities of 1.30-1.35g /cm(3) and cannot be separated using conventional gravity separation techniques. For this reason, polymer recycling needs new techniques. Among these techniques, froth flotation, which is also used in mineral processing, can be useful because of its low cost and simplicity. The main objective of this research is to recycle PET and PVC selectively from post-consumer polymer wastes and virgin polymers by using froth flotation. According to the results, all PVC particles were floated with 98.8% efficiency in virgin polymer separation while PET particles were obtained with 99.7% purity and 57.0% efficiency in post-consumer polymer separation.

Investigation on Interaction of Combustion Parameters of Coal-Water Mixtures Used in Fluidized Bed Combustor

Three different Turkish Lignites (İstanbul-Yeniköy, Manisa-Soma, and Muğla-Milas) were prepared in accordance with coal-water mixtures technology to determine the combustion parameters of a laboratory-scale fluidized bed combustor. In this context, the effects of parameters such as Ca/S, mean bed temperature, preheat, air emission, and feed rate were investigated on SO2, NOx, and CO emissions, while the combustion efficiency and the amount of unburned C were also calculated. In the combustion tests, it was observed that the quantity of SO2 in the flue gas is reduced when there is an increase in the Ca/S ratio in the mixtures. A maximum 95% of sulfur can be removed with Ca/S:4. It was observed that when the temperature in the fluidized bed unit increases, NOx emission increases and CO emission decreases. The optimum bed temperature was found to be approximately 900°C. The preheat temperature of the mixture significantly affects combustion and the efficiency is advanced by increasing preheat temperature. It was also determined that the amount of air added to the combustor affects the efficiency of combustion, with larger quantities of air resulting in lower amounts of unburned C in fly ash; however, increases in air quantities result in higher emissions of NOx.

Investigation of thermal treatment on selective separation of post consumer plastics prior to froth flotation

Plastics have become the widely used materials because of their advantages, such as cheapness, endurance, lightness, and hygiene. However, they cause waste and soil pollution and they do not easily decompose. Many promising technologies are being investigated for separating mixed thermoplastics, but they are still uneconomical and unreliable. Depending on their surface characteristics, these plastics can be separated from each other by flotation method which is useful mineral processing technique with its low cost and simplicity. The main objective of this study is to investigate the flotation characteristics of PET and PVC and determine the effect of plasticizer reagents on efficient plastic separation. For that purpose, various parameters such as pH, plasticizer concentration, plasticizer type, conditioning temperature and thermal conditioning were investigated. As a result, PET particles were floated with 95.1% purity and 65.3% efficiency while PVC particles were obtained with 98.1% purity and 65.3% efficiency.

Separation of PET and PVC by Flotation Technique Without Using Alkaline Treatment

PET and PVC cannot be separated by gravity separation techniques due to their close density. For this reason, plastic recycling needs other separation techniques. Froth flotation, which is used in mineral processing, could be useful because of its low cost and simplicity. The main objective of this research is to investigate the flotation characteristic of PET and PVC and determine the effects of plasticizers on plastic separation without any alkali pre-treatment. In selective flotation experiments, water bottles and waste water pipes were used for this purpose, and Triton XL-100 N and diethylene glycol dibenzoate were used as plasticizers. Various parameters such as pH, plasticizer concentration, conditioning time, and flotation time were investigated. According to the results, PET particles were floated with 100% purity, and the product remaining in flotation cell (PVC particles) was obtained with 86.1% purity.

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.

Characterization and production of Turkish nepheline syenites for industrial applications

Nepheline syenite, which is a silica-poor crystalline rock, competes with feldspar in applications such as glass, ceramic filler, and pigment industries. While its appearance is medium coarse granular like granite, main differences between them are nepheline syenite is silica poor, and contains high alumina and alkali content. Turkey has considerable nepheline syenite deposits in Kırşehir Region, and they contain 1.3% Fe2O3 on average, thus cannot be used unless beneficiated by flotation or/and magnetic separation. In this paper, physical and physicochemical experiments were carried out to improve the quality of nepheline syenite ore. After determinations of chemical, mineralogical, and properties of the sample, three different technologies such as flotation, magnetic separation, and leaching were applied on the ore sample, separately and combined. The obtained results showed that the magnetic separation alone could not produce a nepheline syenite concentrate assaying 0.45% Fe2O3. It was not also possible to obtain a nepheline concentrate less than 0.25% Fe2O3 adapting optimum flotation conditions. The best results were found in combination of the high intensity wet magnetic separation and flotation between -212+63 μm particle size, and a final concentrate with 0.20% Fe2O3 and 0.01% TiO2 was obtained. The leaching experiments were conducted to further decrease Fe2O3 content. Finally, a saleable nepheline syenite concentrate for tile, sanitary ware, electrode, glass, and fiberglass industries was obtained with 6.63% K2O, 9.02% Na2O, 0.15% Fe2O3, and 0.01% TiO2 by the weight of 63.9% at the end of the experiments.

Effect of Particle-Size Distribution and Degree of Saturation on Coal-Compacting Processes within a Coke-Making Operation

The bulk density of an oven charge is a very important factor for the selection of the coking coals and coke quality in a coke-making process for producing blast furnace coke. Major factors influencing the bulk density of coal are moisture content, particle surface properties, particle shape, particle-size distribution, and particle density. The bulk density can be increased significantly through compacting the coal to a coal cake prior to oven charging. The objective of the compaction processes is the production of a cake with high density and as well as a sufficient mechanical strength in order to ensure a trouble-free cake charging into the coke oven. The present article deals with the evaluation of the compaction process based on lab-scale test work. The two subprocesses of densification and strengthening during both stamping and pressing were theoretically and experimentally investigated using compaction test units in combination with a strength-test device. Systematic investigations showed that particle-size distribution and degree of saturation have significant influence on cake density and mechanical properties of the coal cake.

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.