ABSTRACT To accurately predict the product yield during coal preparation plant design, an arctangent model is proposed, and the derivation process of parameters in the model is described. To determine the adequacy and reliability of the model, a statistical analysis approach is used, and the accuracy of the model was verified using the prediction data of usual approximate formula method (AFM) and the

ABSTRACT Oil shale must have a large quantity of kerogen to be of economic benefit, but oil shale with about 30% kerogen is a low-quality ore. Thus, the column flotation technique has been utilized to increase its quality, and the results were analyzed by a reduced two-level factorial design to optimize the interaction effects of seven parameters by response surface modeling. The perturbation plots

ABSTRACT In view of the similarity between the partition curve of coal preparation and the cumulative curve of distribution function, the quartile of random distribution is often used to describe the characteristics of partition curve, the median being the separation density, quartile deviation being the probable error, quartile measure of skewness reflecting the asymmetry of the partition curve. With

ABSTRACT Dried coal typically had certain Particle Size Distribution (PSD) resulting from the size reduction process. Effect of PSD to the compaction phenomenon was investigated on the binary mixtures of Indonesian middle-rank coal with different mass fraction of small and large particles (%L). Compacted density of each coal mixtures was measured during uniaxial briquetting process and their compaction

ABSTRACT This type of fly ash is difficult to float even at a higher concentration of collector due to less dispersion of the collector molecules on the surface. Emulsification of kerosene in the presence of Sodium Dodecyl Sulfate (SDS) dramatically reduces the size of the kerosene droplets. The results showed that much less collector was required to achieve a good separation of carbon from fly ash

ABSTRACT The desulfurization and de-ashing of Darra Adam Khel Coal (Pakistan) was studied by oxidation using Hydrogen peroxide (H2O2) and formic acid (HCOOH) oxidation system. The maximum de-ashing and desulfurization of about 63 and 48% was achieved through oxidation at 70°C in 90 min with H2O2 and HCOOH volume of 2 mL each. Catalytic oxidation was studied in the presence of Tin (Sn) as catalyst loaded

ABSTRACT Water velocity and bed density are most important operating variables affecting the separation of coal particles in Teeter Bed Separator (TBS). In this paper, experimental investigation is carried out to evaluate the matching effect of operating variables on the performance of TBS for separating a coal sample with size of 1–0.25 mm. Furthermore, the particle motion based on the Euler-Euler

It is a well-established fact that the flotation performance is reflected in the structure of the froth surface. A machine vision is able to extract the froth features and present them to the plant operators or the process control system. In this communication, computer vision and machine learning techniques are integrated for recognition of process conditions of a coal column flotation circuit. An

Performance of the 100 mm water-only cyclone and its design parameters in cleaning minus 3.0 mm Indian coal was successfully evaluated via Taguchi based Grey-Relational-Analysis (GRA) using L16 (Single-level) orthogonal array experimental layout. The Taguchi method integrated with GRA was used as a performance index in analyzing multiple responses i.e., clean coal yield (%yield), ash content (%ash)

In the present investigation, an attempt has been made to beneficiate lignite using Burkholderia sp. GR 8–02, Bacillus sp. XQW, and mixed consortium. The experiments showed that Bacillus sp. XQW could remove 18.18–37.50% of total sulfur followed by mixed consortium (18.18–29.17%) and Burkholdria sp. GR 8–02 (9.09%-29.17%). There was also a concomitant decrease in the content of mineral matter as revealed

In this study, it was aimed to produce low-cost activated carbons from cornelian cherry stones (CCS) by ultrasound-assisted chemical activation with the use of LiOH, KOH, NaOH, and ZnCl2. In the study, adsorption capacities of the activated carbon samples for CH4 compared with that of commercially obtained activated carbon (AC), multi-walled carbon nanotubes (MWCNT), mesoporous silica (MCM-41), and

In this study, biological and physicochemical processes were combined to decrease the ash and sulfur contents of finely ground coal. Firstly, biodesulphurization experiments of lignites with high ash and sulfur contents were carried out with air-supply fiberglass bioreactor using Acidithiobacillus ferrooxidans. At the end of the 12-hour bacterial desulfurization experiments; ash content, sulfur content

Rotary dryers are generally preferred for industrial coal drying operations. However, the initial investment and maintenance costs of rotary dryers are quite high. There is also the risk of spontaneous combustion and ignition of coal in such dryers. In this context, carbonic film technology comes to the forefront when an environmentally friendly drying system with low initial investment cost and no

Linde-type A zeolite (LTA) was prepared from coal fly ash (CFA) and used as an adsorbent to remove acidic dye (Acid red 66, AR66) from its aqueous solution. The effectiveness of synthesized (LTA) in adsorbing (AR66) from an aqueous solution was studied using batch experiments. The equilibrium data were studied using the Langmuir and Freundlich models and it was found that the data fit better to Freundlich

In this study, the energy efficiency of three alternative grinding media including, coarse silica beads, fine silica beads, and granular sand, were evaluated and compared against standard stainless steel. Stirred mill test results show that both silica beads and granular sand were more efficient than stainless steel in producing ultrafine particles following the order of coarse silica beads>granular

This study used two-stage cyclones combined with a full cylinder and a short cone cyclone to recover super-low ash clean coal from the coal slime to solve problems of coal slime such as large production, difficult recovery, and low value-added used. After two-stage cyclones separation and screening, super-low ash clean coal with an ash content of 2.74% was obtained, and the mass yield was 10.56% via

This study shows the performance of a currently running vertical roller coal mill (VRM) in an existing coal-fired power plant. In a power plant, the coal mill is the critical equipment, whose effectiveness impacts the overall power plant efficiency. Uniform coal feeding mass flow rate and required particle size and temperature at the outlet channel throughout with better classifier performance are

Dry gravity-based separation processes such as pneumatic jigs and tables generally use density stratification of feed material with light and dense particles to achieve separation. Therefore, it is necessary to enhance the stratification of the particles in the separation bed. The main purpose of this work was to evaluate the use of an intrinsic autogenous separation medium of feed coal for the dry

In coal flotation, clean coal ash content is controlled by adjusting different operating parameters to meet the requirements for products. However, real-time control is strictly restricted by the traditional ash detection method, which is very time-consuming. Froth phase plays an important role in both transporting and upgrading flotation concentrate. The correlation between clean coal ash content

Release analysis is used to characterize the cleaning ability of coal fines. It defines the limit of separation at any target level of ash. Since flotation depends upon many factors like feed size and its composition, surface properties, and type of reagents, it is important to characterize the optimum boundary of separation. Release analysis following the BS7503 procedure was used to characterize

Oil agglomeration is an effective way to demineralize high ash coals as compared to froth flotation and density gradient separation. In this process, the choice of bridging liquid is critical with respect to economics and efficiency. Herein, we report turpentine oil as a potential bridging liquid which is demonstrably efficient in coal demineralization at lower concentration (10 vol.%) compared to

This paper reports experimental results for the flotation of a coking coal sample in highly saline water free of any organic chemicals using an oscillatory air supply. The results are compared with those obtained using a conventional steady air supply. The experiments were conducted with 0.5 M NaCl solution using a laboratory-scale flotation column equipped with a 50 µm pore-sized sparger. The oscillatory

Coal fly ash is regarded as a potential alternative source of rare-earth elements and has gained much attention over the past few years. However, the majority of rare-earth elements in coal fly ash are entrapped in the glassy phase, which makes the recovery of rare-earth elements from coal fly ash extremely challenging. In this paper, two pre-treatments (mechanical grinding and alkali solution treatment)

The separation of coal and gangue is an important part in the coal-preparation process, which can be realized by image recognition technique. The unique optical texture of coal is the most obvious visual features to distinguish coal and gangue. The current research represented the attempt to implement the multifractal analysis in the optical texture of coal and gangue. Firstly, fractal theory is applied

Coal fly ash is considered as a by-product of coal combustion power stations that may pertain unique properties and utilization fields. This review article gives an overview of different classification methods with comparative data on the chemical composition of coal and coal fly ash. Furthermore, a review describes in detail the utilization sectors of coal fly ash that expands from environmental application

This study aims to develop a globally valid prediction model for coal higher heating value (HHV). For the first time, the Gaussian process regression (GPR) method is performed to build the prediction model. For this purpose, a large dataset (as received basis) composed of a wide range of coal ranks is gathered from different geographic locations throughout the world countries in the related literature

The performance of a coal cleaning gravity separator is represented by plotting the partition curve, which is otherwise known as the Tromp curve. From this curve, the two performance parameters estimated are the specifics gravity of separation (SG50) and the sharpness of separation (EP). For a given washing unit, when a family of such curves is plotted against a normalized specific gravity (SG/SG50)

The ease or difficulty of implementing the dewatering process is determined by the state of filter cake pores. These pores are the channels vacated by the filtrate and represent the storage space for water. In this study, the effects of particle size distribution on the filter cake pore structure and the coal slurry dewatering process were studied through visual and quantitative methods. Experimental

This paper describes the development of metaheuristic based artificial neural network (i.e., ANN optimized with PSO, ANN-PSO) and multilinear regression models to predict the higher heating values (HHV) of solid fuels based on the parameters of proximate and ultimate analyzes of the solid fuels. Three hundred data points of HHVs, proximate and ultimate analyzes obtained from published papers on solid

Predicting the instant moisture content of the low-rank coals under the different drying conditions is crucial to construct the optimal system design and operation related to drying processes. Even if the thin-layer drying models are at the center of the field studies, the disadvantage of these type models is that the prediction results are valid only for the conditions of the drying experiment. Conversely

The high-rank coal reserves are limited and getting depleted at an escalating rate to meet the demands of growing population. This concern has compelled the scientific community to use the young high ash coals. The coal water slurry fuel is one promising way to use low-quality coal as an economical liquid fuel. Due to poor physico-chemical and surface properties of such coals, these systems appear

Screening of coal is one of the processes carried out to produce clean coal suitable for the blast furnace. In this work, the screening of moist coal was carried out for different angles of the screen and frequencies. A 2 mm screen perforation was used to separate undersize coal of size +1 mm-2 mm from the +1 mm-3 mm coal samples. For each experimental condition, the screening efficiency was calculated

In order to study the effect of electrochemical oxidation of pyrite in high-sulfur coal on coal spontaneous combustion, the electrochemical oxidation reaction of pyrite in coal was promoted by electrolysis experiments. The FTIR test results show that the content of active groups -OH and -CH2 increases after electrolysis of high sulfur coal. According to the ignition activation energy theory, which

Elastic screening methods are widely used in the classification of moist coal as they can overcome the problem of aperture blockage. However, the use of an equally inclined screen surface with balanced excitation facilitates material accumulation, worsening the screening performance. Here, a disequilibrium excitation structure was proposed to solve the accumulation problem, and its synchronization

This paper investigates the air dense medium fluidized bed (ADMFB) as a suitable dry beneficiation technique to upgrade +5.6 mm-13.2 mm South African coal. The separation efficiency of the ADMFB was assessed by determining the effect, if any, of particle size range, medium to coal feed ratios, and the addition of vibration on the separation ability of the bed. The coal was upgraded to varying degrees

Accurately positioning and identifying coal and gangue under the heterogeneous and complex scenarios of coal production is a key and difficult problem for coal and gangue sorting robot. This paper proposes an image processing based method for the problem and further develops a positioning and identification system. The coal and gangue samples are selected from Hancheng Coal Mine, China’s Shaanxi province

This work presents experimental results of combustion characteristics of low volatile Indian coal. Coal of different average relative density (ARD) varying from 1.35 to 2.0 was generated by density fractionation of the coal. Coal samples were characterized by proximate analysis, Fourier-transform infrared spectroscopy (FTIR), ultimate analysis, and gross calorific value (GCV). Combustion experiments

Processing of noncoking coals in India is limited due to the high cost involved in wet processing. In the present study, dry beneficiation of two high ash Indian non coking coal samples from two different coalfields, namely, Talcher (coal-A) and Ib Valley (coal-B) having diverse characteristics are studied using an air fluidized vibrating deck separator. Washing characteristics of two coal samples

The coal fly ash (CFA) in the present study contains a high content of gallium, which is categorized as a strategic metal. Gallium extraction from CFA is an important step toward its reutilization. Two different processes for gallium extraction were systematically investigated and compared. The effects of mixed acid, microwave power, microwave digestion time, the amount of HNO3, HF, and HCl were studied

The cyclonic–static microbubble flotation column (FCSMC) has been proven to be a promising technique for recovering fine-grained minerals. However, low recovery of coarse coal particles by the FCSMC has been reported due to utilization of a single mineralization step. In the present study, a novel modified flotation unit has been added to the conventional FCSMC to improve the recovery of coarse coal

Coals generally exist with clay minerals, which are very fine-sized minerals, and adversely affect the flotation of coal. For instance, they make the coal surface hydrophilic by coating coal surfaces and therefore, they inhibit bubble-particle attachment. Clay minerals can also cause over-consumption of reagents due to their high surface area. Additionally, clay minerals can transfer into the concentrate

Petrographic studies are commonly used to categorize the potential utilization of coals. Eleven coal samples from the Jharia coalfield (JCF), India, were studied using petrographic techniques to investigate maceral content, reflectance, and textural characteristics. Multiple test samples of each coal were slowly oxidized under controlled laboratory conditions from an ambient temperature of 30°c to

To maximize the potential of China’s scarce coking coal resources, we studied quality improvement techniques for coal middlings using a self-designed fluidized bed jet milling–fineness classification system. The middlings were obtained from the Xiqu coal preparation plant of the Shanxi Coking Coal Group. The results of this study show that the maximum ash gradient occurs between the classifier-I products

In this paper, an attempt is made to recover vitrinite-rich fraction coal using batch flotation operation. Three important operational variables, viz. collector dose (kg/ton), frother dose (kg/ton), and feed solid concentration, (%) have been changed according to Box–Behnken factorial design and their effect on the response parameter like yield, ash, and vitrinite maceral recovery (vmr) percent has

Partial substitution of pulverized coal (PCI) by renewable biocarbon for blast furnace injection is a practical approach to reduce GHGs in the steel production sector. For using biocarbon as feedstock, it is critical to measure its grindability to understand its milling behavior compared to that of typical PCI coal, and thus help decide on adjusting grinding process of existing equipment or selecting

Size reduction of oil shale is an essential process that allows the liberation of organic-rich constituents from inorganic portions to prepare the oil shale for further beneficiation processes. Grinding by conventional methods was impractical and led to technical and economic problems. In this study, the size reduction of the oil shale was conducted by attrition scrubbing process which seems to be

The interaction of coal and oxygen releases heat that promotes oxidation process when it constantly accumulates. If heat released is more than heat dissipated during the oxidation process, the temperature increases. When the temperature of the coal reaches its ignition point, the coal ignites and potentially result in spontaneous combustion. This study evaluated and developed reliable predictive models

Coal is still a significant energy source for the world. Due to the utilization of low-rank coal, drying is a key issue. There are lots of attempts to develop efficient drying processes. The most prominent method seems as thermal drying. For thermal drying processes, the most important subject is the coal moisture content change with time. In this study, convective drying experiments were utilized

To accurately estimate the separation effects and breakage characteristics of coal and gangue particles (CGPs), it is of great significance to understand the meso-morphologies of CGPs and their correlations with different crushing conditions. In the present work, the impact crushing tests were conducted to obtain the effects of sizes, gangue mixture ratios, and crushing velocities on the fractal characteristics

This study focused on the mechanisms of NaCl and CaCl2 enhancing the oily-bubble flotation of lignite. The degree of surface hydration of coal particles before and after conditioning with NaCl/CaCl2 was evaluated with the Einstein theory of dispersion viscosity, while the effect of these two electrolytes on lignite floatability was evaluated via attachment time and flotation tests. The results indicated

This work focuses on reducing the ash content in coal via the microwave-assisted extraction (MAE) method using the closed vessel system. Ash-free coal (AFC) was produced from three variously ranked Turkish coals through microwave-assisted extraction in N-methyl-2-pyrrolidone (NMP) containing a small amount of ethylenediamine (EDA) or tetralin. The extraction yield of these coals was found to depend

Due to the short life of nanobubbles in the pulp, their use in mineral processing, especially in fine grains, is rare. Hence, the use of sustainable nanobubbles with a long lifetime can lead to new results. In addition to the presence of micro-nano bubbles, the ultrasonic emission factor can also have a positive effect on flotation performance. The simultaneous effect of these two factors has not been

In this paper, a comprehensive coal property (chemical, mineralogical, physical, and petrographic) study was conducted using a caking coal from South Africa, density cuts and pyrolyzed samples to understand the % coal caking during pyrolysis. Coal particles of 4, 8, and 10 mm in diameters from the coal feed and its density cuts were pyrolyzed at 0.87, 15, and 30 bar and 450°C and 550°C in the North-West

Porous, granular or fibrous materials that contain oxidizable organic constituents often experience self-heating that leads to spontaneous combustion. Activated carbon is known to be prone to self-heating because of its high surface area. Experiments were conducted to identify factors likely to cause self-heating of materials for producing activated carbon. Spontaneous combustion and characterization

A new promising nuclear technique to determine the coal-ash content was investigated using a bismuth germinate (BGO) detector instead of a sodium iodide-thallium [NaI(Tl)] detector for the dual-energy gamma-ray transmission (DEGT) measurements at 59.6 and 661.7 keV. The peak detection efficiency of the high-energy gamma-ray radiation was about two- to three-fold higher when using a BGO than a NaI(Tl)

The water molecules associated with coal play a significant role in spontaneous ignition and combustion of coal. This paper deals with studies to evaluate the impact of moisture content on crossing point temperature (CPT) and ignition point temperature (IPT) of some low-rank coal and lignite after various stages of drying. Experimental data suggest (i) existence of critical moisture content value determining

In this study, activated carbons (ACs) were produced from coal using potassium hydroxide as a chemical-activating agent. The preparation procedure composed of KOH impregnation followed by activation at 700°C–900°C under the nitrogen atmosphere for the time duration of 1 h. The effects of various activation temperatures and various KOH to coal ratios on the porous structure of the products were examined

Rigid-flex elastic screening methods are widely employed in the efficient utilization of moist coal as they have high efficiency. Here, the synergy between the total excitation force (Ft), frequency (f), and disequilibrium excitation force coefficient (Fde) on the disequilibrium excitation rigid-flex elastic screening process was investigated. The results showed that the order of significance of the

Lignite plays a dominant role for energy production in Greece, covering over 30% of the demand for electricity generation. Increased energy demand requires, additionally to alternative energy sources, an increase in energy supply from both old and new deposits. Due to the low quality of mined lignite, methods of upgrading in terms of power plants’ efficiency and environmental performance need to be

Recently, a two-stage dynamic dense medium separator, called Tri-Flo, has become more applicable for treating difficult-to-wash coals. In this study, a 70-mm diameter transparent Tri-Flo separator was manufactured using prototyping and the effects of geometrical and operating parameters were investigated. Central composite design (CCD) was used in the experimental phase. The effects of internal tubes