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

ABSTRACT Moisture content in coal powder is a critical index because it controls the difficulty of coal handling and ultimately its combustion efficiency in coal-fired power plants. A unilateral proton nuclear magnetic resonance (NMR) scanner was applied in a laboratory to nondestructively quantify moisture content in powdered samples of brown and subbituminous coals. Due to the open geometry of the

Supercritical CO2 (sCO2) dewaters coal through two mechanisms. For bituminous coal of 9.5% average moisture content the water is dissolved out of the coal and the concentration of water in the bulk sCO2 approximates its solubility limit. For lignite (54% average moisture content) the water extracted by the sCO2 exceeds its solubility limit in sCO2, which implies that a part of the water is displaced

The transportation of Lignite coal and Coal ash in slurry form through pipelines is economically and environmentally more viable than the other conventional modes of transportation. The main focus of the present work is to demonstrate the effect of particle concentration and size on the rheological properties of slurries and to further investigate the head loss, energy consumption, energy cost, and

Screening is an indispensable unit operation that is used extensively in many industries to separate particulate materials into different size fractions. A banana screen has high screening efficiency and is widely used for coal classification. In this study, the kinematic characteristics and velocity distribution of the banana screen surface during equal-thickness screening were investigated. High-speed

A novel method has been developed to estimate coke reactivity index (CRI) from coal properties through a kinetic approach. The model was derived from mass balance with a kinetic model of batch reactor CRI test. The parameters of kinetic model were optimized using non-linear least squared method. Three main properties of coals, i.e., Fe2O3 content, volatile matter, and coal rank were selected to predict

In order to investigate the influence of water content on spontaneous combustion characteristics of coal containing pyrite, the Thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) was carried out. The XRD results reveal high pyrite in the Yangquan anthracite. The water loss end temperature and initial reaction temperature increased, with the interval

Modern coal preparation plants are designed to achieve maximum overall clean coal yield with an acceptable amount of impurities to meet end-user requirements. LIMN is commonly used to design and simulate coal processing circuits based on size and density distribution data of coal. In this study, particle distribution data for size, density, and floatability were established for Punjab coal after crushing

This study aims to investigate the lignite ash behavior during combustion for electricity generation and to predict the Ash Fusion Temperatures (AFTs) using ash chemical composition. The studied lignite samples were collected from the area of Ptolemais-Amyntaio at Western Macedonia district of Northwest Greece. Ash chemical composition and its AFTs were determined for all collected samples. Results

The dielectric properties of lignite were studied by using the resonant cavity perturbation method. The effect of temperature, particle size, moisture content, and microwave frequency were investigated. Results showed that the variation of dielectric parameters could be divided into four stages: Stage I (25–200°C), Stage II (200–550°C), Stage III (550–800°C), and Stage IV (800–1000°C). The dielectric

In coal washeries, a considerable amount of fine coal is sent to tailings ponds in Turkey as well as in the World. Fine coal in the tailings should be recovered due to its economic value and potentially harmful environmental effects. In the present study, aggloflotation was tested to recover fine coal from tailings of Tunçbilek coal washery in Turkey. The effects of conditioning time, flotation time

The thermal properties of coke are important for coking production and blast furnace operation. At present, the Coke Reactivity Index (CRI) and Coke Strength after Reaction (CSR) indices are used as key indicators for evaluating these thermal properties. Furthermore, the strength after a certain percentage of carbon loss has been used as a supplementary indicator. The aim of the present study was to

The flotation of low-quality lignite coal in the presence of NaCl, MgCl2 and CaCl2 inorganic salts with/without the use of kerosene and MIBC as flotation chemicals was investigated in this study. In addition, the zeta potential and contact angle measurements were performed. The lignite sample exhibited a negative surface charge over a broad pH range and had no isoelectric point (iep). It was determined

Using coal as feed material and sodium chloride (density and size same as high ash-containing particles in coal feed) as a tracer, residence time distribution (RTD) studies have been carried out in air table. Residence time of particles plays a key role pertaining to density wise segregation on air table. Parameters i.e. air flow rate, side tilt and vibration frequency have strong effect on residence

In coal production, it is necessary to separate waste rock from raw coal. With the development of computer vision technology, the image recognition method with simple equipment and high efficiency has become a research hotspot. Image segmentation is a very important step before the image analysis in image recognition method. Traditional image segmentation takes pixel as processing unit, without considering

Rheological properties of coal water slurry (CWS) with different concentrations (45.77, 50.78, 52.13, 55.56, 57.67, and 61.06 wt%) were investigated by rotational rheometer at different temperatures (20–60°C), and shear rate with integral magnitude logarithmically increased from 1 to 200 s−1. The results show that the CWS is a pseudoplastic fluid, whose rheological characteristic follows Bingham model

The determination of gross calorific value (GCV) of solid fuel is important because GCV is frequently required in the design of most combustion and other thermal systems. However, experimental determination of GCV is time-consuming, which necessitated the development of different empirical equations to estimate GCV using the elemental composition of the solid fuels. With the growing popularity of empirical

Process control within a coal processing plant requires rapid and reliable intervention to the operation. Ash content has paramount importance for the identification of a particular lignite’s quality. Among the methods used for on-line content determination, efforts covering the ash content estimation at the processed particle size ranges and ensuring fast responses are more favorable. The aim of this