Investigation of the effect of agglomeration time, pH and various salts on the cleaning of Zonguldak bituminous coal by oil agglomeration

In this study, the effects of bridging liquid concentration, agglomeration time, pH and various salts on the combustible recovery and ash contents of the agglomerated products have been investigated. Kerosene was used as bridging liquid. The optimum values of kerosene concentration, pH and agglomeration time have been determined as 20 wt%, 7.5 and 15 min, respectively. Metallic salts, such as FeSO₄, NaCl, FeCl₃, Al₂(SO₄)₃ were used in the experiments in which the effects of salts were investigated. While the combustible recovery slightly increased depending on the increase in the concentration of NaCl, very small decreases have been recorded in the recoveries depending on the increase in the concentration of the FeCl₃. A considerable reduction occurs in the agglomeration recovery with the increasing concentration of FeSO₄, while the combustible recovery slightly decreases at low concentration of Al₂(SO₄)₃.     

Optimization of experimental conditions for recovery of coking coal fines by oil agglomeration technique

The significance of coking coal in the metallurgical sector as well as the meager coking coal reserves across the globe increase the necessity to recover coking coal fines from the fine coking coal slurries generated from coal preparation and utilization activities. Oil agglomeration studies were carried out by varying the experimental conditions for maximum recovery of coking coal fines i.e., yield of the agglomerates. The various operational parameters studied were oil dosage, agitation speed, agglomeration time and pulp density. By using Taguchi experimental design, oil dosage (20%), agitation speed (1100 rpm), agglomeration time (3 min) and pulp density (4.5%) were identified as the optimized conditions. A confirmation experiment has also been carried out at the optimized conditions. The percentage contribution of each parameter on agglomerate yield was analyzed by adopting analysis of variance (ANOVA) statistical method as well as multiple linear regression analysis. The order of influence of the parameters on the agglomerate yield is of the following order: pulp density > oil dosage > agitation speed > agglomeration time. A mathematical model was developed to fit the set of experimental conditions with the yield obtained at each test run and also at the optimized conditions. The experimentally obtained yield was compared with the predicted yield of the model and the results indicate a maximum error of 5% between the two. A maximum yield of 90.42% predicted at the optimized conditions appeared to be in close agreement with the experimental yield thus indicating the accuracy of the model in predicting the results.     

Investigation of kinetics of agglomerate growth in oil agglomeration process

In this study, the kinetics of agglomerate growth in a batch oil agglomeration process has been studied using bituminous coal. The effect of operating variables such as kerosene concentration, pulp density and speed of agitation on the agglomeration process was investigated. It has been found that the second-order kinetic equation describes the growth of agglomerates adequately. The growth of the agglomerates in the oil agglomeration process shows a self-preserving growth. Using this, a characteristic curve has been developed. For the prediction of the size distribution of the agglomerates, the d₅₀ values of the agglomerates must be known. Therefore, a model has been developed by using the kinetic equation for estimation of d₅₀ values of agglomerates for this coal. It was shown that the size distribution of the agglomerates for any levels of the process variables studied can be predicted using the equation of characteristic curve and d₅₀ values. Knowledge obtained from this study will be helpful for technological advancement of this kind of study.     

Multi-response optimization of oil agglomeration with multiple performance characteristics

In this paper, the multi-response optimization of grade and recovery simultaneously using Taguchi quality loss function has been done for Zonguldak/Turkey bituminous coal by oil agglomeration. The controllable factors selected in this investigation are solid content, amount of oil, agitation time and agitation rate. The percentage contribution of each controllable factor has been determined on the performance of oil agglomeration. The amount of oil has been found as the most effective factor and its contribution is 65.42% on multiple quality characteristics. The confirmation experiment has also been carried out according to the optimum conditions predicted. The grade and recovery have been increased up to 0.565% and 93.04%, respectively against the initial value of grade and recovery as 0.436% and 75.08%, respectively. The results show considerable improvement in both the quality characteristics such as grade and recovery with the multi-response optimization used, as compared the initial value of grade and recovery.     

Maceral and microlithotype response to oil agglomeration for selected eastern Kentucky high volatile A bituminous coals

The petrographic response of three high volatile A bituminous, petrographically complex eastern Kentucky coals to oil agglomeration was tested using several agglomerating oils. Four oils, hexane, fuel oil, kerosene, and pentane, were tested on the Leatherwood coal, the intermediate coal in the rank series. The testing scheme for the other two coals consisted of using only the hexane and fuel oil with a lesser number of tests than on the initial coal tested. Coal rank emerges as a significant parameter in the behavior of the coals. Particularly for the hexane agglomeration, the coals had quite different behaviors, with the highest-rank coal having greater clean-coal yield at lower oil concentrations than the other two coals. The two high-rank coals exhibit similar yield curves for fuel oil, with the lower-rank coal achieving the yield of the latter coals at higher oil concentrations. The role of the organic petrography and the mineral matter, both closely associated with the macerals in carbominerite microlithotypes and organic-dominant microlithotypes, is an obvious complicating factor. A tendency for duroclarite, the vitrinite-rich trimaceral microlithotype, to partition between vitrinite-rich varieties in the concentrate and vitrinite-poor varieties in the tails was noted at higher oil concentrations for all three coals.     

Application of the Box-Wilson experimental design method for the spherical oil agglomeration of coal

In this study, the Box-Wilson statistical experimental design method was employed to evaluate the effects of important variables such as bridging liquid (oil) concentration, salt (CaCl₂·2H₂O) concentration and stirring speed on the agglomeration of bituminous coal. Response function coefficients were determined by the regression analysis of experimental data and the predictions were found to be in good agreement with the experimental results. The optimum kerosene concentration, CaCl₂·2H₂O concentration and stirring speed were determined as 30 wt%, 1 M and 1683 rpm, respectively, when considering combustible recovery and ash content.In addition, contact angle and solution surface tension measurements were carried out to evaluate of agglomeration success with the contact angle values and surface tension values. The surface tension of CaCl₂ 2H₂O solutions and the average contact angle increased with increasing CaCl₂·2H₂O concentration.     

Modified oil agglomeration process for coal beneficiation. II. Simultaneous grinding and oil agglomeration

The spherical oil agglomeration technique developed at the National Research Council of Canada (NRC) for cleaning and recovering very small coal particles can be simplified by combining the grinding and agglomeration steps such that the excess energy expended while grinding is used for mixing and agglomeration. Experiments with the Szego mill, which is able to handle the pasty agglomerates, have shown that ash removal from Minto (New Brunswick) coal is comparable to that obtained with the usual NRC process. The generally flaky products of the Szego mill allow better ash liberation, and the presence of oil enhances grinding performance. Favourable oil-coal-water ratios have been established. Major savings in equipment and operating costs are possible with the combined process.     

The investigation of coal-pyrite/lignite concentration and their separation in the artificial mixture by oil agglomeration

In this study, the concentration of coal-pyrite and lignite taken from Yozgat-Ayridam (Turkey) Coal Management was investigated by oil agglomeration.In the previous studies, the agglomeration of coal-pyrite was investigated using different bridging liquids (fuel oil, diesel oil and kerosene) and the combination of reagent (KEX, Acorga M5397)+kerosene. When using only bridging liquids, the agglomeration recovery of pyrite was very low. To increase the hydrophobicity of pyrite, KEX was used. However, the pyrite was not agglomerated with an acceptable recovery. But when using Acorga M5397, which is a chelating reagent, the agglomeration recovery of pyrite was increased. The pyrite was agglomerated with a recovery of 76.70 wt% by single-stage agglomeration.In the optimum conditions which were determined for coal-pyrite, the agglomeration recovery of lignite was investigated. It was found that the lignite could not be agglomerated with an acceptable recovery.To investigate the separation of coal-pyrite and lignite, the artificial mixture of coal-pyrite and lignite was prepared with the weight ratio of 1/4 of coal-pyrite and lignite. It was found that the pyrite could be agglomerated at a recovery of 96.54% with three-stage agglomeration process. The lignite concentrate was produced with a recovery of 73.96 wt% and the pyrite content of 0.86 wt%.These findings showed that the coal-pyrite and lignite could be separated by oil agglomeration using appropriate reagent and bridging liquid.     

Modified oil agglomeration process for coal beneficiation. III. Grinding and agglomeration using different szego mill designs

The simultaneous grinding/agglormeration process has been used to beneficiate Minto coal. Experiments with the Szego Mill, a planetary ring-roller mill with grooved rollers, have given good results. Different roller ridge/groove sizes have been tested and favourable oil-coal-water ratios established. Ash removal is closely related to grinding performance. Very short mill residence times, of the order of 10 seconds, are sufficient for microagglomerate formation. Considerable equipment and operating cost savings are possible with the modified process.     

Microbial desulfurization of coal and oil

Biotreatment of fossil fuels may be regarded as suitable technology for the desulfurization of oil and coal before combustion, especially for small-scale combustion plants where flue gas cleaning is too expensive.

Although several patents, especially on the field of biodesulfurization of oil, already exist, successful application in a large scale could not be demonstrated until now. “Organic sulfur” is characterized by covalent C-S bonds and can be regarded as an element which is integrated in the macromolecular matrix of coal and in organic sulfur compounds present in oil. As for the results of more semi-empirical approaches no reproducibility and transferability to other oil qualities could be demonstrated when model compounds representing the organic sulfur species were used.

This research strategy resulted in a number of promising biochemical pathways for the degradation and/or desulfurization of such compounds. However, up to now the use of microorganisms able to degrade model compounds in a biotechnological process for coal or oil desulfurization does not meet the expectations.

Thus, it has to be concluded that additional research is needed which should be focussed on the development of biocatalysts with a broad substrate specificity and on methods to improve the availability of the organically bound sulfur in the molecular structure of oil and coal.     

Optimization of solvent extracted melon seed oil using RSM

Effect of roasting temperature and roasting duration on oil yield (OY) and quality of melon seed (Citrullus lanatus Thunb.) was studied using RSM. Five levels of roasting temperature (87.6, 100, 130, 160, and 172.4°C) and duration (12.9, 15, 20, 25, and 27.1 min) considered. Quality parameters determined were specific gravity (SG), color (CO), free fatty acid (FFA), and anisidine value (AV). Recorded range of OY, SG, CO, FFA, and AV were 44.0–67.5%, 0.9–1.0, and 13.1–94.0 abs, 1.7–5.3%, and 3.9–28.2 mg/L, respectively. The variables have significant effect (p<0.05) on all the responses with exception of SG. Coefficients of determination ($R^{2} $ ) of predictive equations for OY, CO, FFA, and AV were 0.79, 0.97, 0.95, and 0.95, respectively. Optimum roasting temperature and duration were 133.06°C and 20.19 min, respectively. These gave 63.5% OY, 0.9 SG, 13.1 abs CO, 1.7% FFA, and 3.4 mg/L AV. Practical applications: Melon seeds contain about 60% edible oil. Optimization of the process parameters (heating duration temperature) will enhance high OY with good quality. Models developed in this study can be useful for producers of oil extraction equipment and potential investors into commercial production of the oil.     

Modified oil agglomeration process for coal beneficiation. iv. pilot-plant demonstration of the simultaneous grinding-agglomeration process

Simultaneous grinding and agglomeration (SGA) in the novel Szego Mill allows significant simplifications and energy savings. The excess grinding energy is used for mixing and agglomerate formation. Results are reported over a range of operating conditions. The SGA process has been demonstrated in the laboratory and in a 12 tonnes/day pilot plant with satisfactory results. The economics of coal beneficiation for slurry fuel preparation is considered.     

Biological production of methane from bituminous coal

Biogasification of coal offers significant economic and environmental benefits for the continued utilization of coal resources. Several consortia from various natural sources associated with coal have been shown to produce methane from media containing only coal as the organic carbon source. Methane production of these samples has continued to increase with time. The cultures have remained viable and have continued to produce methane after 5 successive transfers to media containing coal as the sole carbon source. Methane quantities of 4 and 5 volume percent methane (0.03 and 0.04 mmol per tube) have been observed from Pittsburgh and Wyodak coals. Serum tube experiments were scaled to larger column experiments that also indicated that methane is produced from medium containing coal as the only carbon source.     

燃煤超细颗粒物团聚促进机制的实验研究

煤粉燃烧排放大量超细颗粒物对大气环境和人类健康造成了严重的危害。提出一种燃后区烟尘团聚促进新方法，通过在燃后区烟道喷射团聚促进剂，利用絮凝理论，增加超细颗粒之间的液桥力和固桥力，促使超细颗粒物团聚长大，进而被现有除尘装置捕获，减少超细颗粒的排放。在自行设计搭建的团聚实验台上进行了系统的实验研究，分析了团聚促进剂溶液的pH值、流量、浓度，团聚室的温度以及模拟烟气中粉尘浓度等因素对超细颗粒物团聚效率的影响。结果表明，化学团聚对于超细颗粒物的脱除具有显著的作用，喷入团聚促进剂后的烟尘排放浓度远比无团聚和喷水的情况要低；团聚促进剂的高分子链对超细颗粒的吸附絮凝作用促进超细颗粒团聚，显著降低烟尘排放浓度，实现超细颗粒物经济高效脱除，达到国家新的烟尘排放标准。     

Modified oil agglomeration process for coal beneficiation. I. Mineral matter liberation by fine grinding with the szego mill

The spherical oil agglomeration technique developed at the National Research Council of Canada (NRC) is an excellent method for cleaning and recovering very small coal particles. The finely ground coal, dispersed in water, is contacted with oil by intensive mixing. The hydrophobic coal particles collect onto the oil droplets to form the agglomerates which are then separated from the aqueous phase by screening. A Szego Mill was used to wet grind Minto (New Brunswick) coal which was then subjected to laboratory agglomeration by the NRC procedure. A comparison with coal ground in a ball mill indicated superior ash rejection. The improved performance is attributed to better mineral liberation which is enhanced by the more flaky particles produced in the Szego Mill.     

Effects of operational parameters on emission performance and combustion efficiency in small-scale CFBCs

A well-designed CFBC can burn coal with high efficiency and within acceptable levels of gaseous emissions. In this theoretical study effects of operational parameters on combustion efficiency and the pollutants emitted have been estimated using a developed dynamic 2D (two-dimensional) model for CFBCs. Model simulations have been carried out to examine the effect of different operational parameters such as excess air and gas inlet pressure and coal particle size on bed temperature, the overall CO, NO_x and SO₂ emissions and combustion efficiency from a small-scale CFBC. It has been observed that increasing excess air ratio causes fluidized bed temperature decrease and CO emission increase. Coal particle size has more significant effect on CO emissions than the gas inlet pressure at the entrance to fluidized bed. Increasing excess air ratio leads to decreasing SO₂ and NO_x emissions. The gas inlet pressure at the entrance to fluidized bed has a more significant effect on NO_x emission than the coal particle size. Increasing excess air causes decreasing combustion efficiency. The gas inlet pressure has more pronounced effect on combustion efficiency than the coal particle size, particularly at higher excess air ratios. The developed model is also validated in terms of combustion efficiency with experimental literature data obtained from 300 kW laboratory scale test unit. The present theoretical study also confirms that CFB combustion allows clean and efficient combustion of coal.     

分散剂在尾煤选择性聚团脱灰中的应用

利用选择性聚团法对平顶山尾煤进行脱灰分选 ,加入分散剂后 ,在一定程度上可降低超细精煤的灰分。选择六偏磷酸钠、硅酸钠、腐植酸钠、木素磺酸钙、碳酸钠、糊精 6种分散剂进行了应用实验 ;并通过测量矿浆的ZETA电位分析了这些分散剂的作用机理。     

Steam gasification of an australian bituminous coal in a fluidized bed

To produce low calorific value gas, Australian coal has been gasified with air and steam in a fluidized bed reactor (0.1 m-I.Dx1.6 m-high) at atmospheric pressure. The effects of fluidizing gas velocity (2–5 U_f/U_mf), reaction temperature (750–900 °C), air/coal ratio (1.6-3.2), and steam/coal ratio (0.63–1.26) on gas composition, gas yield, gas calorific value of the product gas and carbon conversion have been determined. The calorific value and yield of the product gas, cold gas efficiency, and carbon conversion increase with increasing fluidization gas velocity and reaction temperature. With increasing air/coal ratio, carbon conversion, cold gas efficiency and yield of the product gas increase, but the calorific value of the product gas decreases. When steam/coal ratio is increased, cold gas efficiency, yield and calorific value of the product gas increase, but carbon conversion is little changed. Unburned carbon fraction of cyclone fine decreases with increasing fluidization gas velocity, reaction temperature and air/coal ratio, but is nearly constant with increasing steam/coal ratio. Overall carbon conversion decreases with increasing fluidization velocity and air/ coal ratio, but increases with increasing reaction temperature. The particle entrainment rate increases with increasing fluidization velocity, but decreases with increasing reaction temperature. This paper is dedicated to Professor Dong Sup Doh on the occasion of his retirement from Korea University.     

Optimization of oil extraction from locust bean using response surface methodology

Optimization of oil extraction from locust beans (Parkia biglobosa) using central composite rotatable design of RSM was carried out. Independent variables were roasting temperature (90, 100, 110, 120, 130°C) and roasting duration (5, 10 15, 20, 25 min), while the responses were oil yield (OY), free fatty acid (FFA), color (CO), stability, anisidine value (AV), and specific gravity (SG). Data obtained from this study were analyzed using ANOVA and regression analysis. OY, FFA, CO, oil stability, AV, and SG of the oil ranged between (19.0–22.5%), (0.65–3.1%), (37.9–199.9 mg/L), (3.6–6.4%), (11.4–59.9 mg/L), (0.7–0.9), respectively. Roasting conditions significantly influenced all dependent variables at p<0.05. Coefficients of determination (R²) of the generated models ranged from 0.49 to 0.98. Optimum roasting condition was 108°C for 10 min. This gave 22.3% OY, 1.7% FFA, 54.9 mg/L CO, 4.1% stability, 16.5 mg/L AV, and 0.9 SG. Desirability of 0.8 was obtained for optimum conditions. Practical applications: Generally, African locust bean is fermented to give condiment. It has not been used for commercial oil production despite its richness in oil, but soybean with a similar oil content of about 18–20% has been used both for condiment and commercial oil production. Research into the potential of locust bean as a source of edible oil is desirable. Roasting is among pre‐treatment methods employed in vegetable oil industry. Information on degree of influence of these parameters on quantity and quality of oil recovered oil from African locust benefits both entrepreneur and researchers. Also, the developed mathematical expression for OY, FFA, CO, oil stability, AV, and SG, as influenced by roasting temperature and duration is an effective tool in predicting these parameters. The research output has both immediate and potential application.