Caking Coal Research Articles

Preparation of pelletized coke by co-carbonization of caking coal and pyrolyzed char modified with tar produced during pyrolysis of woody biomass

To further the utilization of biomass for cokemaking at ironmaking facilities and to reduce CO2 emissions, carbon/carbon composite (CC) from tar and char is produced from the pyrolysis of a woody biomass with quartz-made fixed-bed reactor at 10 °C/min to 200–500 °C. Then, the optimum conditions for preparing high-strength coke by blending caking coal and CC is investigated. The specific surface areas of char and tar yields via sawdust pyrolysis are maximized at 550 °C. When the mixture of pyrolyzed char and tar produced in large quantities during the same process is co-pyrolyzed, the pore observed in prepared char completely disappears due to filling of carbonaceous materials derived from tar-pyrolysis into char pores, and char yield is improved. When the strength of the coke prepared from the mixture and pelletization of caking coal and prepared CC is investigated, the indirect tensile strength of the prepared coke tends to decrease with an increase in temperature of CC preparation. And, it was found that the optimum CC preparation temperature is 250 °C (CC250) for high-strength coke preparation. Although increasing the blending ratio of CC250 to caking-coal decreases the strength of the coke, the extent of decreasing strength is smaller than that of slightly-caking coal or pyrolyzed char blended to caking coal. The filling of carbonaceous materials derived from tar-pyrolysis into pores of sawdust char during CC preparation influences the coke strength, such that the value is greater than that of physical mixture of sawdust char and carbonaceous materials from tar prepared with individually (carbonaceous materials derived from tar not loaded into pore in char).

Thermogravimetric analysis of the effects of four ionic liquids on the combustion characteristics and kinetics of weak caking coal

This study examined the combustion characteristics and kinetics of coal samples treated with imidazole-based ionic liquids (ILs), namely, [Emim][BF4], [Bmim][BF4], [Bmim][NO3], and [Bmim][I], under oxidation. The oxidation of the coal samples was investigated using thermogravimetry (TG) at heating rates of 4.0, 6.0, 8.0, and 10.0 °C·min−1. The results for the IL-treated samples revealed that the composite index S (representing the ignition, combustion, and burnout properties) decreased and Hf (representing the rate and intensity of the combustion process) increased with high correlation coefficients. The characteristic temperatures of the maximum oxidization mass gain (T2), ignition point (T3), maximum mass loss rate (T4), and burnout point (T5) increased by 13.1 ± 0.5, 9.2 ± 0.5, 21.5 ± 0.5, and 35.9 ± 0.5 °C, respectively. At T3 and the maximum mass loss rate, the release of CO and CO2 was further altered, suggesting that the CO functional groups were damaged or oxidized. The results of the Ozawa-Flynn-Wall kinetic equation used to determine the apparent activation energy (Ea) of coal samples revealed that the Ea of the treated samples increased. The reaction rate constant characterizes the effect of Ea and pre-exponential factors (A), and the results showed that ILs can weaken the reaction process at low temperatures (<130 °C).

Production of High-Quality Extruded Activated Carbons with Simultaneous Decrease of Solid Waste Production

The purpose of the study was to assess the effect of the metamorphism degree of coal dust on the properties of the produced extruded activated carbon, as well as the possibility of involving a by-product of granular activated carbon production for the purpose of its utilization. In the study, the coals of the Kuznetsk coal basin of the brands Brown Coal, Gas Coal, Weakly Caking Coal (SS(3SS) and SSOM), Lean Coal and Anthracite were analyzed. The optimal coal raw material, namely Weakly Caking Coal of the Bachatsky coal cut SS(3SS), was determined. The study of the effect of the coal grinding degree on the properties of the produced sorbent led to the conclusion that the content of the target fraction (0.1–40 μm) to 79 ± 0.5% in coal dust results in production of extruded activated carbon that meets all requirements of standard. The involvement of lean coal brand TPK – a by-product of granular activated carbons production – with weakly caking coal brand SS (3SS) with 1:1 ratio leads to a decrease of cost of obtained sorbent, as well as to improvement of some of its characteristics.

Insight into the effects of additive water on caking and coking behaviors of coal blends with low-rank coal

Additive water is usually needed to preserve 9–11% moisture content of blended coal in the stamp-charging coking process, which in fact is unfavorable for coking property. An insight into the improvement of coking property of coal blends with much low-rank coal (long flame coal SFC, lignite HLH) by regulating additive water was proposed in terms of its effects on the metaplast fluidity and the particle agglomeration behavior. The results indicate that the cohesiveness of gas coals (GC) can be properly enhanced by adding water. The restrictions on the condensation of aromatic structures and the break-up of –CH2– structure and the development of the polyhydroxy groups in aromatic structures are favorable to increase the fluidity of metaplast after adding water, as demonstrated by the optical texture and FTIR analysis of the semicoke (450 °C). The great difference in the hydrophilic properties for various rank coals leads to the particle agglomeration of gas coal and fat coal (GC and FC), which makes them difficult to mix uniformly with SFC after adding water, thus reduces the coking property. A reasonable approach of adding water suggests that H2O and SFC should be well mixed prior to blending with caking coals, which can lead to a uniform particle distribution and a better coking property. This approach promotes the direct and efficient utilization of low-rank coal (especially lignite) by the blending coking with no or less drying and dewatering processes.

Experimental substantiation of the choice of caking additives according to the data of the study fluid non-volatile products of thermal filtration

Extracts of fluid non-volatile products isolated from the plastic layer of caking and low-caking coals of different genetic types by reductivity were first studied in detail using EPR-spectroscopy and gas chromatography-mass spectrometry (GC-MS) methods to reveal the components responsible for caking. According to a study of extracts caking additive selection was carried out. Choice of conditions and experimental verification of the effect of the proposed anthracene additive on the plastic layer formation has been established. The rate of coal decomposition in different periods of pyrolysis has been calculated by the results of derivatography method.

Effect of the Particle Size of Iron Ore on the Pyrolysis Kinetic Behaviour of Coal-Iron Ore Briquettes

High reactivity coke is beneficial for achieving low carbon emission blast furnace ironmaking. Therefore, the preparation of highly reactive ferro-coke has aroused widespread attention. However, the effects of the particle size of iron ore on the pyrolysis behaviour of a coal-iron ore briquette are still unclear. In this study, the effect of three particle sizes (0.50–1.00 mm, 0.25–0.50 mm and &lt;0.74 mm) of iron ore on the thermal and kinetic behaviours of coal-iron ore briquettes were investigated by non-isothermal kinetic analysis. The results showed that the synergistic effect of iron ore and coal during coking mainly occurred during the later reaction stage (850–1100 °C) and smaller particle sizes of iron ore have a stronger synergistic effect. The addition of iron ore had little effect on T0 (the initial temperature) and Tp (the temperature at the maximum conversion rate) of briquette pyrolysis, however itgreatly affected the conversion rate and Tf (the final temperature) of the briquettes. T0 decreased with the decrease of iron ore particle sizes, while Tp and Tf showed opposite trends. After adding iron ore into the coal briquette, the reaction kinetics at all stages of the coal-iron ore briquettes changed. The weighted apparent activation energy of the caking coal (JM) briquette was 35.532 kJ/mol, which is lower than that of the coal-iron ore briquettes (38.703–55.627 kJ/mol). In addition, the weighted apparent activation energy gradually increased with decreasing iron ore particle sizes.

Characteristics of co-combustion of strongly caking and non-caking coals in a pilot circulating fluidized bed combustor (CFBC)

Co-firing of Russian caking coal with non-caking coals (mixtures of Australian bituminous and Korean anthracite coals) was performed on a pilot scale using a circulating fluidized bed combustor (CFBC). The free swelling index (FSI) of caking coal was very high and the alkali index of non-caking coals was relatively high. However, stable fluidization and combustion were attained using various coal blends (containing up to 20 wt% of strongly caking coal). The average particle size in bottom ash increased slightly as the proportion of caking coal increased, triggering a slight temperature rise in the lower part of the combustor. Scanning electron microscopy/energy dispersive spectrometry and X-ray diffraction analyses of coarse particles showed that Al-rich bottom ash captured problematic K to form kalsilite (KAlSiO4), with a melting point much higher than the operating temperature of a typical CFBC. Such data strongly suggest that stable CFBC co-combustion is possible using mixtures featuring strongly caking coals. The unburnt carbon content of fly ash and the O2 concentration in flue gas at the steady state increased linearly as the proportion of caking coal increased, indicating reduced co-combustion of caking coal. Morphological analyses of unburnt carbon in bottom ash revealed that pore clogging progressed on addition of caking coal, decreasing char reactivity by blocking oxygen access during co-combustion. In terms of pollutants, NO emission from fuel N in flue gas increased slightly on addition of caking coal, but N2O emission decreased slightly, attributable to a temperature rise in the dense combustor bed. However, the conversion rate of fuel S to SO2 did not significantly change when the proportion of caking coal increased.

A comparison of ignition characteristics of slurry fuels prepared using coal processing waste and finely divided coal

The scientific novelty of the research is that for the first time differences in the conditions and characteristics of the ignition and burning of droplets of slurries prepared on the basis of coals and waste from their enrichment have been established. The practical significance of the research results is that they illustrate the prospects of utilization of the numerous coal enrichment wastes by combustion in the composition of aqueous slurries with the generation of a rather large amount of energy and a relatively small negative environmental impact. The most significant characteristics were compared: the limiting (minimum) temperature; the ignition delay times; the maximum combustion temperature; the concentration of the main gas anthropogenic emissions. It has been found that fuel mixtures prepared from wet waste of coal flotation are characterized by higher inertia and ignition temperatures compared to slurries with high-quality coal dust. However, the established differences considering the availability and low cost of filter cakes illustrate the prospects of waste derived fuel combustion. The combustion heat of the investigated slurries based on coal and filter cake with addition of petroleum products differs by no more than 5–30%. The average difference between the duration of ignition for fuel droplets based on dust and filter cake of coking and low-caking coals is about 20%. At that the addition of waste turbine oil (10% wt.) into the filter cake reduces the duration of ignition by 12–25% and the ignition temperature – by 10–15 °C without a significant increase in anthropogenic gas emissions. The difference between the minimum ignition temperatures of coal and waste coal based slurries was from 10 °C to 80 °C. On environmental and economic indicators, coal waste is more attractive than coal.

Assessment of Thermal Efficiency of Recovery Stamp Charged Cokemaking

The cokemaking process is a complex phenomenon. The coke strength properties depend on the thermal conditions that prevail during coal carbonization to a large extent. The thermal conditions are influenced by operating parameters, viz., flue temperature, wall temperature, carbonization time, bulk density, and moisture content. The flue temperature and coking time are dependent variables with an inverse relationship. The heat required for making coke has a significant impact on the coking time and quality of the coke. Maintaining optimum thermal conditions in the recovery coke oven also helps in the conservation of energy and economy of the industry. In the present study, the authors have assessed the material balance, heat balance, and heat losses of a recovery stamp charged coke oven. This study helps further the overall understanding of heat flow that directly affects the heating rate into the coal cake, which allows for obtaining the optimal heat requirements for producing the desired quality of coke w...

Regimes of the Combustion of Organic Coal–Water Fuels

The results of an analysis of the combustion behavior of the drops of organic coal–water fuels (OCWFs) prepared based on the flotation products (cakes) of the enrichment the coal of five grades (longflame, gas, coking, low-caking, and lean coals) and two petroleum products (petroleum residue and spent turbine oil) are presented. The experiments were performed under the conditions of the stationary fastening of an OCWF drop on the junction of a quick-response thermocouple in a flow of heated (from 500 to 1000°C) air. The following three combustion regimes were revealed for all of the test OCWF compositions: stepwise regime with slow heating (smoldering), intense gas generation regime with the boiling of liquid fuel components (boiling), and regime with a distinct tear-off zone of gas flow (torch). It was shown that the occurrence of the above combustion behaviors substantially depends on the characteristics of the OCWF components: the ash content and the yield of volatile substances of coal cakes and the boiling points and the ignition and combustion temperatures of the petroleum products used. Based on the results of the experiments, the ranges of air temperature changes characteristic of each of the three combustion regimes of fuel suspensions were established.

OBTAINING GRANULATED ACTIVE CARBON FROM WASTES OF VEGETABLE RAW MATERIALS

In the processes of agricultural products production a sufficiently large amount of solid wastes which contain high molecular weight hydrocarbons such as lignin, cellulose, etc. is accumulated. However, such wastes are rarely used to produce active carbons, and only technologies with their use for obtaining crushed or powdered sorption materials are known. In the industrial production of granular activated carbon the fossil coals are mainly used. In this work, research was conducted on the development of methods for producing granulated active carbon of spherical form. And the characteristics of their porous structure were studied. The process of granulation of the spherical shape of sorbents was carried out by liquid dispersing composition containing pulverized wastes of vegetable origin and a binder. As plant materials we used walnut shells and peanuts, apricot seed, buckwheat husk, and for comparison, the dust caking coal of SSOM brand. As a binder a phenol formaldehyde resin was used. To remove volatile substances of plant the raw material was subjected to preliminary heat treatment without access of air in a muffle furnace at optimum temperature which was determined by thermogravimetry. Crushed carbon material was mixed with a binder component in a weight ratio of 1:5 and was sprayed into a solution of sulfuric acid with a concentration of 30-35% for the curing of the pellets. The obtained pellets were soaked in acid solution for 24-30 h, were separated from the liquid, were washed with distilled water to pH = 5-6, and were dried first in air and were subjected to heat treatment. The result of the research shows the possibility of regulation of characteristics of the porous structure of the spherical granular activated carbon depending on the plant material. The resulting spherical granules of activated carbon have developed system of micro - and mesopores. Depending on the type of plant waste the received active carbon has a radius of micropores in the range of (0.527-0.635) nm and maximum sorption volume varied from 0.46 to 0.71 cm3/g.Forcitation:Farberova E.A., Tingaeva E.A., Chuchalina A.D., Kobeleva A.R., Maximov A.S. Obtaining granulated active carbon from wastes of vegetable raw materials. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 3. P. 51-57

Influence of Inherently Present Oxygen-Functional Groups on Coal Fluidity and Coke Strength

The effect of various oxygen-containing compounds added and/or inherent O-species on coal fluidity and coke strength has been investigated in detail. When several O-containing compounds, which have different O-containing groups, are added independently to caking coal, the MF value almost decreases, and the extent of the decrease being ether < ketone < lactone < hydroxyl < acid anhydride < < ether/hydroxyl/lactone < carboxyl group. The COOH content in four coals used increases with decreasing C%, and the MF values decrease with increasing the content. The evolution of gaseous O-containing species (CO, CO2, and H2O) during carbonization at 3 °C/min of four coals up to 400 °C has been studied mainly with a flow-type quartz-made fixed-bed reactor to clarify the effect of the amount of O-containing gases evolved with the Gieseler fluidity of coal particles. A positive correlation is found between the amount of CO, CO2, or H2O evolved up to 400 °C and the COOH content in coal. However, a negative correlation be...

The Causes and Prevention Measures of Stuck Pump Phenomenon of Rod-pumped Well in CBM Field

In the process of CBM field exploitation, in order to realize the drainage equipment to work continuous stably, the article pays attention to study and solve the stuck pump problem, and aim of reducing reservoir damage and lowing production costs. Through coal particles stuck pump experiment and sediment composition analysis, we find out five primary cause of stuck pump phenomenon: sand from coal seam, sediment from ground, iron corrosion, iron scrap caused by eccentric wear, coal cake. According to stuck pump mechanism, the article puts forward 8 measures to prevent stuck pump phenomenon, and the measures are focused on technology optimization, operation management and drainage process control. After 7 years production practice, the yearly stuck pump rate has dropped from 8.9% to 1.2%, and the pump inspection period has prolonged 2 times. The experiment result shows that pure coal particles cannot cause stuck pump, but sand, scrap iron, and iron corrosion are the primary cause of stuck pump. The article study and design the new pipe string structure that the bottom of the pipe string is open. This kind of pipe string applied the sedimentation terminal velocity theory to solve the stuck pump phenomenon, and it can be widely used in CBM drainage development.

Ultrasonic technique for online measurement of bulk density of stamp charge coal cakes in coke plants

Coke oven batteries utilize stamp charged coal cakes for production of high quality blast furnace coke. Crushed coal blends are mechanically stamped to produce coal cakes. It is crucial to have a good control over this stamping operation so as to achieve a uniform bulk density (≈1100–1200kg·m−3 wet basis) of coal cake post stamping. This can facilitate robust and energy efficient coking operation. The dynamic nature of the stamping operation necessitates an online bulk density measurement technique. An ultrasonic technique which enables online measurement of bulk density during the stamping operation is described. The ultrasonic response was found to have a straight line correlation with bulk density (wet basis) and moisture content of stamped coal with an R2 value of 0.98. The effect of moisture content in the coal on the ultrasonic measurements is also discussed. A lab scale prototype was developed with integrated sensors to emulate online measurement. The prototype was found to have a measurement error of less than ±1.6%. This method can also be suitably adapted for online bulk density measurement of granular solids other than crushed coal.

Research on Improving Low Rank Coal Caking Ability by Moderate Hydrogenation

The hydrogenation test of low metamorphic coal was carried out by using a continuous hydrogen reactor at the temperature of (350-400)°C and the initial hydrogen pressure of 3 ~ 6Mpa. The purpose of the experiment was to increase the caking property, and the heating time was controlled from 30 to 50min. The test results show that the mild hydrogenation test, no adhesion of low metamorphic coal can be transformed into a product having adhesion, oxygen elements in coal have good removal, the calorific value of the product has been improved significantly and coal particles during pyrolysis, swelling, catalyst, hydrogenation, structural changes and the combined effects of particles a new component formed between financial and is a major cause of coal caking enhancement and lithofacies change, coal blending test showed that the product can be used effectively in the coking industry.

Characteristics of gas evolution profiles during coal pyrolysis and its relation with the variation of functional groups

Strict relation between the substituents or functional groups attached to the coal macromolecules and the generation of the volatile products, e.g., CH4, H2O, CO, CO2, etc., during the coal pyrolysis is an important but confusing subject. In this paper, quadrupole mass spectrometry, gas chromatography, and 13C nuclear magnetic resonance are applied to real-time monitoring the formations of volatile products, off-line quantitative determination of the total products from the pyrolysis of a sub-bituminous coal (SC), and the changes of diverse substitents in the SC along with coke foamation, respectively. These measurements are also performed for the pyrolysis of a caking coal to contrast SC. The qualitative and quantitative data reveal that, during coal pyrolysis, the functional groups related with the formation of CO, i.e., ether, carbonyl, and anhydride, can directly generate CO via bond breaking, or take a detour of the formation of other intermediates via condensation and recombination firstly. Moreover, the formations of CO2 and CH4 are related to the direct removal of -COO- and -CH3, respectively.

Dependence of the water wettability of the surfaces of fossil coals on their structure and properties

The dependence of the water wettability of coal surface on the structure and properties of coals of different stages of diagenesis and metamorphism was studied based on the evaluation of the angles of contact. It was found that the caking coals of Zh and K ranks exhibited maximum hydrophobic properties. Hydrophilic properties were most pronounced in brown coals and low-rank black coals with the highest concentrations of hydroxyl and carboxyl groups and a developed porous structure.

Research of a possibility of receiving sorbents for a sewage disposal from a wastage of coal preparation factory

The paper presents the results of the studies of the structure and porosity of the coal cake processed by electric arc plasma. The main limiting factor in processing of coal cakes sorbents is their high water content. As a result of coal washing, the main share of water introduced into the cake falls on hard-hydrate and colloidal components. This makes impossible application of traditional processes of manufacturing from a cake of coal sorbents. Using the electric arc intensifies the processes of thermal activation of coal cakes associated with thermal shock, destruction and vapor-gas reactions occurring at the surfaces of the particles at an exposure temperature of up to 3000 °C, which increases the title product outlet (sorbent) and thereby reduces manufacturing costs and improves environmental performance. The investigation of the thermal activation zone is carried out in the plasma reactor chamber by thermal imaging method followed by mapping-and 3D-modeling of temperature fields. the most important physical and chemical properties of the sorbents from coal cake activated by plasma was studied. The obtained results showed the possibility of coal cake thermal activation by electric arc plasma to change its material composition, the appearance of porosity and associated sorption capacity applied for wastewater treatment.

1-2-3 画像解析による粘結炭フリーコークスの強度発現機構の解明(session 1-2 コークス)

1-2-3 画像解析による粘結炭フリーコークスの強度発現機構の解明(session 1-2 コークス)

Assessment of thermal efficiency of heat recovery coke making

The heat recovery stamp charge coke making process is quite complicated due to the evolved volatile matter during coking, is partially combusted in oven crown and sole flue in a controlled manner to provide heat for producing metallurgical coke. Therefore, the control and efficient utilization of heat in the oven crown, and sole flue is difficult, which directly affects the operational efficiency. Considering the complexity and importance of thermal efficiency, evolution of different gases, combustion of gasses in oven crown and sole flue, and heating process of coke oven has been studied. A nonlinear regression methodology was used to predict temperature profile of different depth of coal cake during the coking. It was observed that the predicted temperature profile is in good agreement with the actual temperature profile (R2 = 0.98) and is validated with the actual temperature profile of other ovens. A complete study is being done to calculate the material balance, heat balance, and heat losses. This gives an overall understanding of heat flow which affects the heat penetration into the coal cake. The study confirms that 60% heat was utilized during coking.