Oil Agglomeration Research Articles

Oil agglomeration and its effect on beneficiation and filtration of low-rank/oxidized coals

Low-rank/oxidized coals respond poorly to oil agglomeration. Emulsification of kerosene in the presence of surfactants dramatically reduces the size of the kerosene droplets, lowering the consumption of kerosene needed to agglomerate oil down to 0.25–0.5%. Surfactants can also entirely change the interaction between oil droplets and coal particles. Consequently, kerosene cationic emulsions can efficiently agglomerate oxidized coal particles. The agglomerates obtained in such a process can still be recovered by screening.

Oil Agglomeration for Recovery of Coal Fines: Effect of Vegetable Oil and Bacterial Pretreatment

In the present study, the technique of oil agglomeration has been explored with the aim of employing the process for recovery of coal fines from washery/coal industry effluents as well as deashing of coal. Both edible and non-edible vegetable oils have been tested for agglomeration of five different types of Indian coals widely used in power and metallurgical sectors. The yield of agglomerates ranged from 40.0 to 87.5% and ash rejections from 13.5 to 62.0% using different coal-oil combinations. Bacterial pretreatment of coal with mixed culture prior to oil agglomeration improved the selectivity of vegetable oils resulting in higher ash rejections (59.0−76.0%). Also, pretreatment of high sulphur coal with Thiobacillus ferrooxidans culture resulted in significant enhancement in pyritic sulphur rejection from 69.0 to 98.5%. Various process parameters have been optimized for vegetable oil agglomeration. Higher rates of biodegradation observed with vegetable oils as compared to that with petroleum fractions further supported their use as environmentally safe agglomerants.

Recovery of coal fines from washery and power plant effluents by integrated technique of oil agglomeration and biofilm formation.

The possibility of applying an integrated technique of oil agglomeration and biofilm formation for recovery of coal fines from coal washeries and power plants effluents has been explored. Laboratory experiments with simulated slurries of different Indian coal fines demonstrate that vegetable oils are satisfactory agglomerating agents for recovery of most of the coal fines depending on the nature of coal and type of oil. The agglomeration behaviour of coal fines was assessed in terms of % yield, % organic matter recovery and % ash rejections. Maximum 85% agglomerate recovery was obtained in the agglomeration stage. Residual oil concentrations in some cases were found to exceed the permissible limit. Recovery of residual coal fines and reduction in residual oil concentration in the resultant slurry after oil agglomeration have been attempted using biofilm formation. A laboratory scale treatment reactor was put under complete recirculation to facilitate attached microbial growth on coal particles as carrier under aerobic conditions. The influence of various parameters on attached growth and stable biofilm formation were studied. The growth patterns of attached cell in suspension and consumption pattern of carbon substrate (oil) have been investigated. Steady decline in residual substrate concentration in the slurry with corresponding increase in the growth of attached and free cell mass is observed. The growth process was favoured in pH range of 6.5-7.0. The attached growth was found to be expanded in size in due course of time ultimately leading to the formation of stable biofilm in the treatment reactor which was subjected to the influent total suspended solids loading resulting from oil agglomeration step. Performance of the biofilm reactor in terms of % reduction in total suspended solids and residual oil concentration in the influent slurry was assessed in continuous mode. Complete recovery of coal fines and 60% degradation of oil was observed in the final effluent discharged from the treatment reactor.

Integrated technique for pyritic sulphur reduction in Indian (ASSAM) coal

Microbial desulphurization of coal using a pyrite oxidizing organism such as Thiobacillus ferrooxidans, results in approximately 90% pyritic sulphur reduction in 30 d. An integrated technique, comprised of bacterial preconditioning and subsequent oil agglomeration, is concerned with surface modification of the pyrite by short contacts (2–240 min) with a culture of Thiobacillus ferrooxidans and its rejection during agglomeration. Coal (−250 μm) was preconditioned with the bacterial culture for 2.5–30 min before subjecting it to oil agglomeration. About 75–80% ash rejection and 90–97% pyritic sulphur reduction (PSRD) have been obtained. Extending preconditioning for 240 min could not improve the PSRD beyond 97%. By increasing the particle size from −250 μm to −800+400 μm the pyritic sulphur reduction (PSRD) decreased from 97% to 71%, whereas prolonging the preconditioning period to 240 min enhanced the PSRD to 90%. The integrated technique has considerably reduced the time requirement from 20–30 d to 30–240 min in order to obtain 90% pyritic sulphur reduction. Castor oil has been used as the agglomerant and found to be a good substitute to traditionally used petroleum fractions.

98/02690 Physical and chemical generalities and ecological aspects for oil agglomeration process of low-grade coals: Biletskyi, V. S. et al. DGMK Tagungsber., 1997, 9702, (Proceedings ICCS '97, Volume 1), 499–5502

98/02690 Physical and chemical generalities and ecological aspects for oil agglomeration process of low-grade coals: Biletskyi, V. S. et al. DGMK Tagungsber., 1997, 9702, (Proceedings ICCS '97, Volume 1), 499–5502

98/02653 Air-promoted oil agglomeration of moderately hydrophobic coals. Part 1. General characteristics: Milana, G. et al. Coal Prep., 1997, 18, (1/2), 17–36.

98/02653 Air-promoted oil agglomeration of moderately hydrophobic coals. Part 1. General characteristics: Milana, G. et al. Coal Prep., 1997, 18, (1/2), 17–36.

98/02681 Kinetics of a gas-promoted oil agglomeration process: Zhang, F. and Wheelock, T. D. Coal Prep., 1997, 18, (1/2), 69–90.

98/02681 Kinetics of a gas-promoted oil agglomeration process: Zhang, F. and Wheelock, T. D. Coal Prep., 1997, 18, (1/2), 69–90.

98/02654 Air-promoted oil agglomeration of moderately hydrophobic coals. Part 2. Effect of air dosage in a model mixing system: Drzymala, J. and Wheelock, T. D. Coal Prep., 1997, 18, (1/2), 37–52.

98/02654 Air-promoted oil agglomeration of moderately hydrophobic coals. Part 2. Effect of air dosage in a model mixing system: Drzymala, J. and Wheelock, T. D. Coal Prep., 1997, 18, (1/2), 37–52.

98/01849 Evaluation of response of brown coal to selective oil agglomeration by zeta potential measurements of the agglomerates : Gurses, A. et al. Fuel, 1997, 76, (14/15), 1439–1444

98/01849 Evaluation of response of brown coal to selective oil agglomeration by zeta potential measurements of the agglomerates : Gurses, A. et al. Fuel, 1997, 76, (14/15), 1439–1444

98/01872 Selective oil agglomeration of Lafia coal, Nigeria : Uwadiale, G. G. O. O. Trans. Soc. Min., Metall., Explor., 1996 (Pub. 1997), 300, 179–180

98/01872 Selective oil agglomeration of Lafia coal, Nigeria : Uwadiale, G. G. O. O. Trans. Soc. Min., Metall., Explor., 1996 (Pub. 1997), 300, 179–180

Estimation of coal hydrophilicity by flow microcalorimetry

The adsorption heat of methanol on a coal surface was measured by flow microcalorimetry (FMC). Eight coals, each with different oxygen contents, were used as adsorbents. Methanol adsorption heat depends on the number of hydrophilic groups on the coal surface, while the amount of methanol adsorbed is independent of the surface chemical composition of coal. We examined a range of methanol concentrations in n-hexane: 2–20 g/l, and found that the adsorption heat reaches equilibrium before 20 g/l methanol concentration. The heat of methanol adsorption at 20 g/l is effected neither by the particle size distribution nor by the quantity of inorganic impurities in the coal adsorbent; however, methamol adsorption heat varies in direct proportion to the coal hydrophilicity, a parameter affecting the recovery of fine coal in oil agglomeration and flotation. FMC data for methanol adsorption heat can be used to estimate the coal hydrophilicity. Estimates obtained in this way agree well with those obtained by Sun's surface-component theory.

Determination of bridging liquid type in oil agglomeration of lignites

The aim of this study was to determine the appropriate bridging liquid for lignites at selective agglomeration. Kerosene, diesel-oil, fuel-oil, spindle oil, heavy neutral, bright stock, light neutral and various surface active components were used. The best results were obtained with a mixture of 70% fuel-oil + 15% Acorga M5640 + 15% 2-ethyl hexanol or other alcohol type of reagents. It was determined that a clean coal having an ash content of 17% with a combustible recovery more than 90%, was produced from a coal with an ash content of 35.27%.

Determination of bridging liquid type in oil agglomeration of lignites

The aim of this study was to determine the appropriate bridging liquid for lignites at selective agglomeration. Kerosene, diesel-oil, fuel-oil, spindle oil, heavy neutral, bright stock, light neutral and various surface active components were used. The best results were obtained with a mixture of 70% fuel-oil + 15% Acorga M5640 + 15% 2-ethyl hexanol or other alcohol type of reagents. It was determined that a clean coal having an ash content of 17% with a combustible recovery more than 90%, was produced from a coal with an ash content of 35.27%.

98/00961 Oil agglomeration at low pH as a pretreatment for liquefaction of Wyoming (USA) subbituminous coal: Winschel, R. A. et al. DGMK Tagungsber., 1997, 9704 (Proceedings ICCS '97, Volume 3), 1369–1372

98/00961 Oil agglomeration at low pH as a pretreatment for liquefaction of Wyoming (USA) subbituminous coal: Winschel, R. A. et al. DGMK Tagungsber., 1997, 9704 (Proceedings ICCS '97, Volume 3), 1369–1372

98/00072 Oil agglomeration at low pH as a pretreatment for liquefaction of Wyoming (USA) subbituminous coal

98/00072 Oil agglomeration at low pH as a pretreatment for liquefaction of Wyoming (USA) subbituminous coal

98/00064 Evaluation of response of brown coal to selective oil agglomeration by zeta potential measurements of the agglomerates

98/00064 Evaluation of response of brown coal to selective oil agglomeration by zeta potential measurements of the agglomerates

脱灰石炭造粒粒子の解砕による石炭‐重油‐水混合物の流動特性

The flow characteristics of coal-oil-water mixture (COW) was investigated. COW was prepared by a disintegration of deashed coal agglomerates, which were obtained by the oil agglomeration of coal. When the volume fraction of dispersed waterdrops in COW was smaller than 0.2, the dispersed waterdrops influenced the flow characteristics of COW to the same extent as the dispersed coal particles. COW behaved as Bingham fluid. Both the yield value and Bingham viscosity increased with increasing total disperse phase volume fraction in COW, and with decreasing temperature. The relative viscosity of COW was well correlated by the equation derived with reference to Mooney's equation.

微粒石炭浮選における脱灰性の評価と単体分離度の推定

The authors have developed a new method to evaluate coal flotation behavior. The liberation degree of mineral matter in feed and the ultimate ash content of froth product can be estimated using this method. Modified release analysis and oil agglomeration tests were carried out using different feed size of coal. The results were plotted on combustible recovery vs. ash content of clean coal curves and on combustible (or mineral matter) recovery vs. yield curves. Graphic analysis of these curves is proposed to give the ultimate ash content of coal concentrate obtained under ideal conditions and the liberation degree of mineral matter of flotation feed. By comparing these curves with conventional flotation results, the mass of mineral matter entrapped mechanically in froth was determined. In this paper the above procedures are described in detail using Datong coal. The ultimate ash content decreased and reached about 1 % with decreasing average feed sizes, smaller than 2μm, and the liberation degree increased to above 90 %. The mass of entrapped mineral matter increased drastically for feed smaller than 20μm.

Maceral/microlithotype partitioning through triboelectrostatic dry coal cleaning

Three eastern Kentucky and two Illinois Basin coals were tested in a bench scale triboelectrostatic separation unit. The three eastern Kentucky samples provided a rank series of petrographically comparable coals. The Illinois Basin bituminous coals were lower rank and had high vitrinite ( ∼ 80%) and sulfur contents in comparison to the other three coals. Triboelectrostatic beneficiation provides efficient maceral and mineral partitioning in the high volatile A and B bituminous coals tested, with vitrinite, as vitrite and vitrinite-enriched microlithotypes, reporting to the clean fractions and the inertinites, liptinites, and minerals reporting to the tails. The high volatile C bituminous Springfield coal had a lower separation efficiency than the petrographically similar, but higher rank, Herrin coal. The decreased separation efficiency in the behavior of the Springfield coal may be a response to its higher moisture content. Compared to bench-scale fuel oil agglomeration of some of the same coals, triboelectrostatic separation provides clearer partitioning of mineral matter, sulfur, and macerals.

Evaluation of response of brown coal to selective oil agglomeration by zeta potential measurements of the agglomerates

The effects of suspension pH, concentration of surfactant (cetyltrimethylammonium bromide, CTAB) and concentrations of electrolytes (FeCl 3, CaCl 2 and NaCl) on the recovery of agglomerate and on the reductions in ash and pyritic sulfur in selective oil agglomeration were investigated. The correlation between recovery and reductions in ash and pyritic sulfur and the zeta potential of the agglomerates was also studied. It was found that there was a close correspondence between them and that zeta potential measurements on the agglomerates would give a measure of the effectiveness of oil agglomeration.