Hasan Hacifazlioglu

Optimization of Some Parameters in a Modified Water-Only Cyclone for Metallurgical Coal Production from High-Ash Fine Coking Coals

Coking coal with generally 11% or lower ash content is termed as metallurgical coal and is used in the steel industry after the coking process. In Turkey, generally spirals and flotation machines are used for the production of metallurgical coal from high-ash fine coals. According to plant data, these devices are capable of producing clean coal with an ash content of 7%–15% from raw coal with 40%–60% ash content. This study aimed to produce metallurgical coal from high-ash coal using a modified water-only cyclone as this method is simple and easy to control. Firstly, the conventional water-only cyclone was modified, then some important operating parameters such as cyclone inclination, inlet pressure, and solids concentration were optimized. Following the optimization procedure, it was found that clean coal of metallurgical quality with 11% or lower ash content can be produced using a modified water-only cyclone.

Recovery of Coal from Cyclone Overflow Waste Coals by Using a Combination of Jameson and Column Flotation

Abstract In this study, combustible matters are recovered from high-ash waste coal separately, first by Jameson flotation and then column flotation. Although high combustible recovery can be obtained from waste coal by Jameson cell, low-ash coals could not be obtained due to low froth height. High froth depth in column flotation has increased the probability of particles dropping back from froth to pulp and very low-ash products have been obtained. However, column flotation has been relatively less successful compared to Jameson flotation in terms of coal recovery. Therefore, both cells have been combined in a common circuit system and low-ash products have been achieved with high combustible recovery values. As a result, clean coals with 7.12% ash were recovered from waste coal having 48.80% ash with 73.60% combustible recovery in the common circuit system. However, in a similar circuit system only with column flotation, coals with 7.04% ash were recovered with 67.85% combustible recovery value. On the other hand, only with Jameson cell, coals with 10.40% ash were recovered with 74.50% combustible recovery.

Enrichment of Silica Sand Ore by Cyclojet Flotation Cell

Cyclojet flotation is an alternative technique of jet flotation. It essentially has a mechanism for bubble formation with pulp jet spouting from the apex of hydrocyclone. The size of the bubbles formed with pulp jet in the cyclojet cell is very small, and the quantity of bubbles produced also limits its potential to produce high bubble-particle collision. This is particularly efficient in beneficiation of fine-grained ores. In this study, the performance of the cyclojet flotation cell was tested for removing iron-oxides from silica sand ore. Whether it can be used as an alternative to conventional mechanical cells was studied. The findings obtained from the cyclojet cell were compared with findings obtained from the conventional cell. It was seen that the cyclojet cell produced slightly better results than the conventional cell. Under the best conditions, while the cyclojet cell reduced the iron-oxide content in silica sand from 0.41% to 0.08%, the conventional cell reduced it to 0.10%. While iron removal efficiency was 80.49% for the cyclojet flotation, it was calculated as 75.61% for the conventional cell. These findings showed that cyclojet flotation can be used as an alternative method to conventional flotation for the removal of iron oxides from silica sand.

Pilot-scale Studies of Ash and Sulfur Removal from Fine Coal by Using the Cylojet Flotation Cell

This article presents the results of pilot-scale studies of ash and sulfur removal from a Turkish coal by using the cyclojet flotation cell. The cyclojet cell, which was developed by H. Hacifazlioglu and I. Toroglu in 2006, utilizes an alternative jet flotation technique. Apart from being based on the working principle of jet flotation, the cyclojet cell incorporates centrifugal forces into the flotation process, thus providing an excellent separation for ash and pyritic sulfur removal. The most important parameters for the removal of ash and pyritic sulfur in the cycojet cell are the length of the conical jet, frother type, wash water rate, and froth thickness. With decreasing the conical jet length and increasing the wash water rate and froth thickness, there is an increase in the removal of pyritic sulfur. On the other hand, the frothing agents MIBC produced better results in terms of pyritic sulfur removal in the cyclojet cell. Under optimal conditions, the cyclojet cell removed 61.25% of the pyritic sulfur and 73.98% of the ash with a combustible recovery value of 71.10% without any need for a depressant.

Comparison of Efficiencies of Microwave and Conventional Electric Ovens in the Drying of Slime-Coal Agglomerates

ABSTRACT Currently nearly 6 million tonnes of bituminous coal are produced in Turkey and more than 0.3 million tonnes of slime coal are discarded from the coal-washing plants. Slime coal is a low-calorie fuel containing clay and other minerals and high levels of moisture. The filter cake sample used for the study was obtained from a hydrocyclone overflow. The moisture content of the disc-filtered bituminous coal was 26% and its average particle size was ~30 microns. The slime-coal filter cake sample was agglomerated in 2 cm diameter material before the drying experiments. The agglomerates were dried separately in both microwave and conventional ovens. After the drying process, the efficiency of each oven was determined. The surface temperatures and compressive strengths of the agglomerates dried in both types of oven were compared. In the microwave oven, micro- and macrocracks appeared on the agglomerates causing them to dry faster. In that manner, the drying efficiency of the microwave was found to be higher. As the microwave energy heated the agglomerate selectively, the surface temperature was found to be lower. However, the quick-drying process caused a decrease in the strength of agglomerates.

A new process for the production of medium quality fuels from coal washing plant coarse tailings

ABSTRACT Turkey’s proven bituminous coal reserve is very low, and it is about 1.3 billion tons. The annual bituminous coal production is 2 million tons, and the annual import amount is 30 million tons. Turkey is a foreign-dependent country in its bituminous coal requirement. In this respect, the highest recycling of coarse and fine plant tailings is important in respect of the efficient use of limited natural resources. In this study, a novel process was developed for medium quality fuel production from coarse plant tailings. By the developed process, from coarse plant tailings with an ash content of 78.21%, medium quality fuel was produced which has ash content between 29.20 and 44.38% and which has economic value in the current market. The upper calorific values of these fuels change between 5620 and 4350 kcal/kg. The developed process basically includes the stages of micronized grinding and then froth flotation applied to the obtained powder tailing material.

The Recovery of Coal from Waste Coal Slurry by Cyclojet Flotation Cell

Abstract In this article, experiments were conducted under various working conditions in order to recover coal from waste coal slurry by cyclojet flotation. Waste coal slurry with 47.50% ash yielded products having an ash content of 7–17% with 65–80% combustible recoveries. It has been found that results of the cyclojet cell are close to the release curve, and the cyclojet cell can be substituted for the mechanically-agitated conventional cell. Moreover, the total flotation time for the cyclojet cell is 30 seconds and a cell with a capacity of 100 liters can enrich as much as 0.6 tonne of coal (for 5% solid ratio). It has other important advantages, such as having a simple structure, requiring little room, and being easy to operate.

The Benefication of Ultrafine Coal by Using the LM, Modified LM, and Conventional Flotation Cell

Abstract This article describes modification of the LM cell developed by Cheng Xinghua and using it to clean ultrafine coal. The major modifications involve replacing the column in a standard LM cell with a hydrocyclone and giving air into the system through a porous material. Thus, centrifugal forces are also incorporated into the system and a higher coal recovery is obtained. In addition, such important design and operating parameters as the apex diameter, gas flow rate, wash water rate, reagent dosage, and solid ratio were optimized, which affect the performance of the modified LM cell. Next, flotation experiments were carried out using the standard LM cell and conventional mechanical cell and the results were compared with those obtained from the flotation with the modified LM cell. It was established that the modified LM cell is an effective one for cleaning ultrafine coal and has a considerably high capacity. In fact, following the flotation of merely 60 sec, coals with an ash content of 46% yielded clean coals having a 10–15% ash content with 70–75% combustible recovery. The conventional flotation cell, on the other hand, produced a poor selectivity and lower coal yield. The separation efficiency of the modified LM cell was in the 55–60% range, whereas that of the conventional cell varied between 50–55%.

Effect of Temperature on Coal Flotation with Waste Vegetable Oil as Collector

ABSTRACT In this study, the effect of pulp temperature on coal flotation was investigated. Waste vegetable oil was used as collector. Experiments were carried out at different temperatures (5, 25, 50, and 75°C) and the pros and cons of each temperature for flotation performance were revealed. While flotation performance was lower in higher pulp temperatures (50 and 75°C), flotation performance was found higher in lower pulp temperatures (5 and 25°C). Highest combustible recovery values were obtained at 25°C pulp temperature, and the lowest ash product was obtained at 75°C. However, the lowest combustible recovery value was obtained in flotation at 75°C.

Production of Merchantable Coal from Low Rank Lignite Coal by Using FGX and Subsequent IR Drying

ABSTRACT Beneficiation of low rank lignite coals by wet cleaning methods is difficult and low efficiency. Low rank coals are broken into smaller particles in water and create too much slurry. Too much slurry is a problem and requires the construction of a large sludge pond. Clay minerals and other components in the texture of low rank coal also adsorb water. This creates various problems both during washing and in subsequent processes of washing. Especially dewatering and drying are an important cost element in coal preparation. Therefore, it is more rational to upgrade low rank coal with dry beneficiation techniques. Lignite coal which is net calorific value less than 2500 kcal/kg in Turkish coal market can not be sold. In this study, low rank coal with a lower calorific value 1650 kcal/kg was first treated with FGX dry separator and then dried with IR radiation to increase the net calorific value above 2500 kcal/kg.