a parametric study of froth stability and its effect on column flotation of fine coal particles

1
0 1 Solid fuels (preparation) of exinite and vitrinite with the broad Lorentz 1 lines. Intensities (I) of the broad Gauss and the narrow Lorentz 3 lines of exinite and vitrinite changes with temperature according to the Curie law (I = Cm). The existence of thermally excited multiplet states was not stated for inertinite. The two groups of paramagnetic centres of inertinite with Lorentz 2 and Lorentz 3 lines obey the Curie law. 02/00069 Through the looking glass: unravelling the network structure of coal Gregory, D.M. et al. Prepr. Symp. - Am. Chem. Sm., Div. Fuel Chem., 2000, 45, (2), 200-204. Numerous swelling parameters measured by magnetic resonance microscopy (MRM) are found to correlate with cross-link density of the polymer network under investigation. Use of these parameters to assess the three-dimensional network structure of coal is discussed. 02/00070 Time resolved small angle X-ray scattering reactivitv studies on coals. asohaltenes. and oolvmers Winans, 6.E. et al. Prepr. - km. ‘chemical S&.. Di;. FLel chemical, 1999. 44. (1). 576-580. The bbj&& of this study is to examine changes in the structure of coals, asphaltenes, and polymers in situ with small angle X-ray scattering (SAXS) during thermal treatments. We have built a SAXS instrument at the Basic Energy Sciences Synchrotron Radiation Center at the Advanced Photon Source that allows us to obtain scattering data on very small samples and in the millisecond time domain. The Argonne Premium Coal samples, petroleum derived asphaltenes, and polymers with functionality to model fossil fuels were used in this study. The information that can be derived from these experiments includes: changes in fractal dimensionality, surface topology, and size and type of porosity. The information is correlated with other methods on the same samples. 02/00071 Verification of the Aida’s chemical determination method for oxygen-functionality in coal and coal product Aida, T. et al. Prepr. Symp. - Am. chemical Sm.. Div. Fuel chemical, 1999, 44, (3), 571-575. The method for the determination of carboxylic acid and phenolic hydroxyl functionalities in coal and coal product by using reactions of tetrabutylammonium borohydride and lithium borohydride in pyridine solvent (determination of the volume of the hydrogen product) was compared with the non-aqueous titration method using a pyridine solution of n-BudNOH (0.1 mol/L) as a titrant. Benzoic acid and 2. naphthol as model compounds and pyridine extracts of Pittsburgh No. 8 and Illinois No. 6 coals were used in the study. It was suggested that the content of the carboxyl group in Illinois No. 6 coal was up to five times higher than that reported before. 02iOOO72 X-ray fluorescence techniques in Czech coal industry Cechak, T. Proc. Eur. Conf. Energy Dispersive X-Ray Spectrom. (EDXRS-98), 1998, 329-331. Edited by Fernandez, J.E., Tartari, A. X-ray fluorescence analysis using backscattering is employed in the determination of ash in coal and X-ray fluorescence analysis is used for the determination of sulphur content of coal in mines in the Czech Republic. One-purpose XRF analysers with the proportional counter and controlled by a microcomputer are produced in Czech Republic. These analysers with 23sPu use the X-ray backscattering method for routine determination of the ash content of coal samples. For measurement of the sulphur contents in coal two sources may subsequent$ be used. The 55Fe for the excitation of S, Ca, and Ti lines, and 23 Pu for the excitation of Fe and other elements with higher Z. For a more precise measurement of S content the analysers with Si (Li) detector are used. The XRF analysers connected in the net with the dual energy gamma ray transmission analysers enable the quality of coal production in the whole mining to be controlled. The results from XRF measurements were also compared with the corresponding results from the chemistry laboratory. Preparation 02/00073 A parametric study of froth stability and its effect on column flotation of fine coal particles Tao, D. et al. 1~. J. Miner. Process, 2000, 59, (l), 25-43. Laboratory flotation tests have been conducted to examine the effect of froth stability on the column flotation of finely pulverized coal. The upgrading of coal in a flotation column can be significantly improved when froth stability is properly controlled through the manipulation of appropriate variables such as gas flow rate (V,), wash water flow rate (V,), froth height, wash water addition point, and feed solid concentration. Increases in wash water flow rate and gas flow rate promoted froth stability, resulting in higher combustible recovery, but possibly higher ash recovery as well. The optimum rates were determined to be 2 and 0.3 cm/s for V, and V,, respectively. The specific influence of wash water flow rate on water recovery was found to be closely related to how the frother dosage was maintained. Coal particles could stabilize or destabilize the froth, depending on their size and concentration in the cell. Those in the 100 mesh fraction destabilized froth at lower concentrations and stabilized it at higher concentrations while micronized particles always showed froth-break- ing power. The froth profiles of solid content and ash content were established at varying wash water flow rates and wash water addition points, from which it was concluded that froth cleaning occurred primarily at the pulp-froth interface and drainage above the wash water addition point. 02/00074 A survey of coal cleaning technologies (coal preparation) Okazaki, T. Nippon Enerugi Gakkaishi, 2000, 79, (4), 267-284. (In Japanese) A review with 14 references. Because of a general lowering of quality of run-of-mine coal in recent years, the need for coal cleaning has significantly increased. In order to reduce the environmental impact caused by production, transportation, procession and consumption of coal, it is necessary to introduce various technologies for clean use of coal, such as coal preparation. The purpose of coal preparation is to improve the quality of coal to make it suitable for a specific purpose by (1) cleaning to remove inorganic impurities; (2) sizing-crushing, or screening, or both; or (3) special treatment such as blending, coal-oil mixture, coal-water mixture, etc. Recently, advanced coal cleani,ng techniques have been focused to produce a super clean coal because of the increasing usage of coal and the reduction of environmental problems. 02/00075 Agent for treating raw coal Zhang, Q. et al. Faming Zhuanli Shenqing Gongkai Shuomingshu CN 1,228,466 (Cl. ClOLlOjOO), I5 Sep 1999, Appl. 98,110,591, 20 Nov 1998. 6. (In Chinese) The agent comprises S-fixing agent 76-82, leavening agent 10-13, catalyst 2-3, and oxidant S-7%. The S-fixing agent contains CaO 70% and 2 1 of CaCOj, NaZCOx and MgO 15-30%. The leavening agent is selected from one or more of NaCI, KNOX, NaNOx and CaC03; the catalyst from one or more of FeZ03, MnOz, Crz03 and COO; the oxidant from KMn04, KC103 and NaN03. The agent also contains binders. The binders are selected from papermaking waste, Al-making slag and soap-making slag, and the addition to the raw coal is 5-10%. The addition of the agent to the raw coal is 5-10%. 02/00076 An evaluation of coal preparation technologies for controlling trace element emissions Luttrell, G.H. et al. Fuel Processing Technology, 2000, 65-66, 407422. Recent studies suggest that low-cost coal preparation technologies can play an important role in reducing the emissions of air toxics at electric utilities. To evaluate this approach, a detailed study was conducted at Virginia Tech to quantify the capabilities of a variety of conventional and advanced precombustion cleaning processes for removing hazar- dous air pollutant precursors (HAPPs). Characterization data obtained from this study indicate that most HAPPs associate with mineral impurities commonly found in run-of-mine coals. Some elements (e.g. mercury) were found to associate with pyritic sulphur, while others (e.g. manganese) were more closely associated with ash-bearing minerals. Furthermore, pilot-scale tests conducted as part of this work demonstrated that conventional cleaning processes could achieve HAPPs rejections of 50-80%. The use of advanced processes further improved these rejections, particularly for HAPPs associated with pyrite. The data also showed that trace element rejections could be improved by pulverizing the feed coal to liberate mineral matter. However, mathematical simulations indicated that these apparent gains are often not realized in industrial operations due to the lower separation efficiencies of the finer coal cleaning circuits. 02lOOO77 Application of dense-medium in an enhanced gravity separator for fine coal cleaning Honaker, R.Q. et al. Miner. Eng., 2000, 13, (4), 415-427. Dense-medium separators have proven to be the most efficient processes for removing the undesirable gangue material from run-of- mine coal. The application cf high-pressure feed injection into dense- medium cyclones to provide an elevated centrifugal force has recently been found to allow efficient separation performances for the treatment of fine coal (i.e. <lOOO pm). However, high-pressure injection requires specialized pumps and results in relatively high maintenance requirements. A test program was conducted to evaluate the potential cleaning of 1000 x 44 pm fine coal using dense-medium in an enhanced gravity separator (EGS), which mechanically generates an enhanced gravity field. Test results indicate that the use of dense- medium in a EGS resulted in an 8% wt. unit increase in mass yield Fuel and Energy Abstracts January 2002 9

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Page 1: A parametric study of froth stability and its effect on column flotation of fine coal particles

0 1 Solid fuels (preparation)

of exinite and vitrinite with the broad Lorentz 1 lines. Intensities (I) of the broad Gauss and the narrow Lorentz 3 lines of exinite and vitrinite changes with temperature according to the Curie law (I = Cm). The existence of thermally excited multiplet states was not stated for inertinite. The two groups of paramagnetic centres of inertinite with Lorentz 2 and Lorentz 3 lines obey the Curie law.

02/00069 Through the looking glass: unravelling the network structure of coal Gregory, D.M. et al. Prepr. Symp. - Am. Chem. Sm., Div. Fuel Chem., 2000, 45, (2), 200-204. Numerous swelling parameters measured by magnetic resonance microscopy (MRM) are found to correlate with cross-link density of the polymer network under investigation. Use of these parameters to assess the three-dimensional network structure of coal is discussed.

02/00070 Time resolved small angle X-ray scattering reactivitv studies on coals. asohaltenes. and oolvmers Winans, 6.E. et al. Prepr. - km. ‘chemical S&.. Di;. FLel chemical, 1999. 44. (1). 576-580. The bbj&& of this study is to examine changes in the structure of coals, asphaltenes, and polymers in situ with small angle X-ray scattering (SAXS) during thermal treatments. We have built a SAXS instrument at the Basic Energy Sciences Synchrotron Radiation Center at the Advanced Photon Source that allows us to obtain scattering data on very small samples and in the millisecond time domain. The Argonne Premium Coal samples, petroleum derived asphaltenes, and polymers with functionality to model fossil fuels were used in this study. The information that can be derived from these experiments includes: changes in fractal dimensionality, surface topology, and size and type of porosity. The information is correlated with other methods on the same samples.

02/00071 Verification of the Aida’s chemical determination method for oxygen-functionality in coal and coal product Aida, T. et al. Prepr. Symp. - Am. chemical Sm.. Div. Fuel chemical, 1999, 44, (3), 571-575. The method for the determination of carboxylic acid and phenolic hydroxyl functionalities in coal and coal product by using reactions of tetrabutylammonium borohydride and lithium borohydride in pyridine solvent (determination of the volume of the hydrogen product) was compared with the non-aqueous titration method using a pyridine solution of n-BudNOH (0.1 mol/L) as a titrant. Benzoic acid and 2. naphthol as model compounds and pyridine extracts of Pittsburgh No. 8 and Illinois No. 6 coals were used in the study. It was suggested that the content of the carboxyl group in Illinois No. 6 coal was up to five times higher than that reported before.

02iOOO72 X-ray fluorescence techniques in Czech coal industry Cechak, T. Proc. Eur. Conf. Energy Dispersive X-Ray Spectrom. (EDXRS-98), 1998, 329-331. Edited by Fernandez, J.E., Tartari, A. X-ray fluorescence analysis using backscattering is employed in the determination of ash in coal and X-ray fluorescence analysis is used for the determination of sulphur content of coal in mines in the Czech Republic. One-purpose XRF analysers with the proportional counter and controlled by a microcomputer are produced in Czech Republic. These analysers with 23sPu use the X-ray backscattering method for routine determination of the ash content of coal samples. For measurement of the sulphur contents in coal two sources may subsequent$ be used. The 55Fe for the excitation of S, Ca, and Ti lines, and 23 Pu for the excitation of Fe and other elements with higher Z. For a more precise measurement of S content the analysers with Si (Li) detector are used. The XRF analysers connected in the net with the dual energy gamma ray transmission analysers enable the quality of coal production in the whole mining to be controlled. The results from XRF measurements were also compared with the corresponding results from the chemistry laboratory.

Preparation

02/00073 A parametric study of froth stability and its effect on column flotation of fine coal particles Tao, D. et al. 1~. J. Miner. Process, 2000, 59, (l), 25-43. Laboratory flotation tests have been conducted to examine the effect of froth stability on the column flotation of finely pulverized coal. The upgrading of coal in a flotation column can be significantly improved when froth stability is properly controlled through the manipulation of appropriate variables such as gas flow rate (V,), wash water flow rate (V,), froth height, wash water addition point, and feed solid concentration. Increases in wash water flow rate and gas flow rate

promoted froth stability, resulting in higher combustible recovery, but possibly higher ash recovery as well. The optimum rates were determined to be 2 and 0.3 cm/s for V, and V,, respectively. The specific influence of wash water flow rate on water recovery was found to be closely related to how the frother dosage was maintained. Coal particles could stabilize or destabilize the froth, depending on their size and concentration in the cell. Those in the 100 mesh fraction destabilized froth at lower concentrations and stabilized it at higher concentrations while micronized particles always showed froth-break- ing power. The froth profiles of solid content and ash content were established at varying wash water flow rates and wash water addition points, from which it was concluded that froth cleaning occurred primarily at the pulp-froth interface and drainage above the wash water addition point.

02/00074 A survey of coal cleaning technologies (coal preparation) Okazaki, T. Nippon Enerugi Gakkaishi, 2000, 79, (4), 267-284. (In Japanese) A review with 14 references. Because of a general lowering of quality of run-of-mine coal in recent years, the need for coal cleaning has significantly increased. In order to reduce the environmental impact caused by production, transportation, procession and consumption of coal, it is necessary to introduce various technologies for clean use of coal, such as coal preparation. The purpose of coal preparation is to improve the quality of coal to make it suitable for a specific purpose by (1) cleaning to remove inorganic impurities; (2) sizing-crushing, or screening, or both; or (3) special treatment such as blending, coal-oil mixture, coal-water mixture, etc. Recently, advanced coal cleani,ng techniques have been focused to produce a super clean coal because of the increasing usage of coal and the reduction of environmental problems.

02/00075 Agent for treating raw coal Zhang, Q. et al. Faming Zhuanli Shenqing Gongkai Shuomingshu CN 1,228,466 (Cl. ClOLlOjOO), I5 Sep 1999, Appl. 98,110,591, 20 Nov 1998. 6. (In Chinese) The agent comprises S-fixing agent 76-82, leavening agent 10-13, catalyst 2-3, and oxidant S-7%. The S-fixing agent contains CaO 70% and 2 1 of CaCOj, NaZCOx and MgO 15-30%. The leavening agent is selected from one or more of NaCI, KNOX, NaNOx and CaC03; the catalyst from one or more of FeZ03, MnOz, Crz03 and COO; the oxidant from KMn04, KC103 and NaN03. The agent also contains binders. The binders are selected from papermaking waste, Al-making slag and soap-making slag, and the addition to the raw coal is 5-10%. The addition of the agent to the raw coal is 5-10%.

02/00076 An evaluation of coal preparation technologies for controlling trace element emissions Luttrell, G.H. et al. Fuel Processing Technology, 2000, 65-66, 407422. Recent studies suggest that low-cost coal preparation technologies can play an important role in reducing the emissions of air toxics at electric utilities. To evaluate this approach, a detailed study was conducted at Virginia Tech to quantify the capabilities of a variety of conventional and advanced precombustion cleaning processes for removing hazar- dous air pollutant precursors (HAPPs). Characterization data obtained from this study indicate that most HAPPs associate with mineral impurities commonly found in run-of-mine coals. Some elements (e.g. mercury) were found to associate with pyritic sulphur, while others (e.g. manganese) were more closely associated with ash-bearing minerals. Furthermore, pilot-scale tests conducted as part of this work demonstrated that conventional cleaning processes could achieve HAPPs rejections of 50-80%. The use of advanced processes further improved these rejections, particularly for HAPPs associated with pyrite. The data also showed that trace element rejections could be improved by pulverizing the feed coal to liberate mineral matter. However, mathematical simulations indicated that these apparent gains are often not realized in industrial operations due to the lower separation efficiencies of the finer coal cleaning circuits.

02lOOO77 Application of dense-medium in an enhanced gravity separator for fine coal cleaning Honaker, R.Q. et al. Miner. Eng., 2000, 13, (4), 415-427. Dense-medium separators have proven to be the most efficient processes for removing the undesirable gangue material from run-of- mine coal. The application cf high-pressure feed injection into dense- medium cyclones to provide an elevated centrifugal force has recently been found to allow efficient separation performances for the treatment of fine coal (i.e. <lOOO pm). However, high-pressure injection requires specialized pumps and results in relatively high maintenance requirements. A test program was conducted to evaluate the potential cleaning of 1000 x 44 pm fine coal using dense-medium in an enhanced gravity separator (EGS), which mechanically generates an enhanced gravity field. Test results indicate that the use of dense- medium in a EGS resulted in an 8% wt. unit increase in mass yield

Fuel and Energy Abstracts January 2002 9