01737 Occurrence and volatilization behavior of Pb, Cd, Cr in Yima coal during fluidized-bed pyrolysis

01737 Occurrence and volatilization behavior of Pb, Cd, Cr in Yima coal during fluidized-bed pyrolysis

01 Solid fuels (preparation) Preparation 04/01732 An assessment of acid wash and bioleaching pretreating options to remove mercury from coal show th...

171KB Sizes 1 Downloads 210 Views

01 Solid fuels (preparation)

Preparation 04/01732 An assessment of acid wash and bioleaching pretreating options to remove mercury from coal

show that the method on electrochemical enhancing desulfurization of high sulfur coal in flotation could effectively remove sulfur in clean coal and improve product quality.

04/01736 Heat treatment of coals and distributions of x-ray diffraction phases of their organic matter

Dronen, L. C. et al. Fuel, 2004, 83, (2), 18i 186. The United States Environmental Protection Agency is expected to begin regulating the release of vapour-phase mercury from coal-fired power plants in the year 2007. Chemical pre-treatment methods were investigated for mercury removal effectiveness from pulverized lowsulfur North Dakota lignite coal. More limited results were obtained for a pulverized high-sulfur Blacksville bituminous coal. A two-step acid wash treatment showed removal rates of 60-90%, compared to one-step treatments with concentrated HC1, which yielded removals of 30-38%. Removal effectiveness is similar for first step solvents of water, pH 5.0 acid, or pH 2.0 acid followed by concentrated HCI as the second step solvent, and is independent of first step incubation time. Neither of two bacterial strains, Thiobacillus ferrooxidans and T. thiooxidans, was found effective for mercury removal.

Korolev, Y. M. Koks i Khimiya, 2003, (3), 8 12. (In Russian) The application of heat treatment of coal to their structure and composition usually considers such things as position of the development of fundamental performance to the structure of coal substances, and in the plan of practical supplement, in the amount of study on thermal preparation of the coat mixtures, with entire increase in processing effectiveness of coke beds. Methods often include IR spectroscopy, NMR, and EPR. In this work X-ray diffraction for phase analysis was applied to thermally processed lines of stone coal (anthracite) from Kuznetskii basin, treated for 2 hours at two temperature ranges: 300°-400 ° and 500°-600 ° . The phases of organic matter were examined. Phases observed were polynaphthenes (called the ~-strip), a graphite-like phase, Gf, and various other phases in the coal and interstices. The various coals and processes were compared as to the extent of graphitization and increase of the graphite-like phase.

04/01733 Degradation of a Victorian brown coal in subcritical water

04/01737 Occurrence and volatilization behavior of Pb, Cd, Cr in Yima coal during fluidized-bed pyrolysis

Kashimura, N. et al. Fuel, 2004, 83, (3), 353 358. Conversion characteristics of a Victorian brown coal in sub-critical water were investigated. Pulverized brown coal was heated up to 623 K in flowing sub-critical water pressurized at 25 MPa. The total conversion of the coal into extract and non-condensable gas reached over 70 wt%-daf, which was appreciably higher than the maximum conversion (50 wt%-daf) with a sub-critical non-hydrogen donor solvent, 1-methylnaphthalene (MN). Laser-ionization-desorption mass spectrometry showed that the sub-critical water extract was richer in lower-molecular-mass compounds than the sub-critical MN one. Thus, degradation of the coal occurred more extensively in sub-critical water than in MN. Along with the conversion in sub-critical water, both the total contents of hydrogen and phenolic hydroxyls in the whole products remained nearly unchanged. This suggests comparable and simultaneous formation and decomposition of hydroxyls through hydrolysis of ethers/esters and dehydration condensation between hydroxyls/carboxyls, respectively. For detecting the hydroxyl formation, the coal was first heated at 623 K under an inert gas atmosphere until the formation of water and the other volatiles was completed. Then, the heat-treated coal (LY-H) was exposed to flowing sub-critical water. As expected, the net formation of phenolic hydroxyIs from LY-H was detected as 0.8 mmol-OH/g-LY-H while that of hydrogen as 2.3 mmolH/g-LY-H. Approximately a half of the hydrogen gain was explained as phenolic hydroxyls gain, suggesting the importance of hydrolysis of esters and ethers that formed carboxyls and alcoholic hydroxyls as well as phenolic hydroxyls.

Lu, H. et al. Fuel, 2004, 83, (1), 39-45. The volatilization behaviour of Pb, Cd, Cr and the influence of coexisting mineral matters were investigated during pyrolysis of Yima coal in a fluidized-bed reactor at temperatures ranging from 500 to 900°C. The modes of occurrence of Pb, Cd, Cr in Yima raw coal and two char samples were determined using density fraetionation, demineralization and sequential chemical extraction methods. Lead in Yima coal is mostly associated with mineral matter in various forms, mainly pyrite, sulfates and monosulfides. Large part of cadmium is associated with pyrite. Chromium in Yima coal is mainly associated with organic matter. Different trends are observed for various forms of trace metals during pyrolysis. Lead associated with pyrite, sulfates and carbonates, lead in water soluble and ion exchangeable forms, and cadmium associated with pyrite are all unstable under pyrolysis conditions. During Yima coal pyrolysis, the volatilities of lead and cadmium vary greatly with pyrolysis temperature, while chromium volatility in Yima raw coal only has slight changes over the temperature range (500-900°C) studied. The volatility of Pb, Cd, Cr in demineralized Yima coal (YimaD) is much higher than that of Yima coal during pyrolysis. New thermally stable forms of Pb, Cd and Cr are formed during pyrolysis of Yima, whereas the sources of them are different. The interactions between chromium and its coexisting mineral matters in Yima coal retard its vaporization during pyrolysis.

04/01734 gases

Desulfurization kinetics of coal combustion

Braganca, S. R. et al. Brazilian Journal of Chemical Engineering, 2003, 20, (2), 161-169. Desulfurization of the gases from coal combustion was studied, using limestone (marbIe) as the sorbent in a fluidized-bed reactor. The kinetic parameter, k, was measured by analysing the reduction in SO2 emissions in relation to time when a batch of limestone was introduced directly into the combustor chamber. The influence of sorbent composition and particle size was also studied. The CaO content in the limestone was more important than the MgO content. Sorbent particle size showed a strong influence on the reaction time and efficiency of desulfurization. The results of this work prove that marble type is important in the choice of sorbent for a desulfurization process. A magnesian limestone showed a better performance than a dolomite. Therefore, the magnesian limestone is more efficient for a shorter particle residence time, which is characteristic of the bubbling fluidized bed.

04/01735 Experimental research on enhancing desulfurization of high sulfur coal in flotation by electrochemical methods Yang, Y. et al. Meitan Zhuanhua, 2003, 26, (2), 60-63. (In Chinese) The modification mechanism of coal and coal-pyrite surface was studied after treatment with electrolysis reduction and metal corrosion interaction. By using IR spectra and X-ray diffraction analyses, surface modification of coal and coal-pyrite takes a different direction, which is beneficial to desulfurization of high sulfur coal flotation after pretreatment with different electrochemical methods. Under certain electrochemical operation conditions, hydrophilic substances are produced on pyrite surface and its floatability lowered. At the same time, the oxygen-containing functional groups on coal surface reduced and the floatability of coal improved. A range number of researches

04•01738 runoff

Removal and recovery of metals from a coal pile

Ibeanusi, V. M. et al. Enviromnental Monitoring and Assessment, 2003, 48, (1-2), 35-44. The removal and recovery of heavy metals from a coal pile runoff water using a mixture of multiple metal-tolerant bacterial strains of ATC 55673, and ATCC 55674 and a Pseudomonas were studied. The analysis of elemental composition of metal precipitants recovered from the bacterial biomass by transmission electron microscopy and energy dispersive X-ray analysis revealed the presence of metals originally present in the wastewater. Analysis of metals in culture supernatant and bacterial biomass by inductively coupled plasma emission spectroscopy (ICP-ES) indicated a removal of 82-100% and a recovery of 15-58% of metals from the wastewater and bacterial biomass, respectively.

04/01739 Results of the demonstration operation, the demonstration and dissemination project for a coal preparation system, model project for an environmentally harmonized coal utilization system in China. Coal preparation technology suited for de-sulfurizing and deashing performance Ondera, J. et al. Shigen to Sozai, 2003, 119, (4,5), 214 219. (In Japanese) This model project had been carried out since the 1997 Japanese fiscal year (JFY) to 2001 JFY by the subsidy from New Energy and Industrial Technology Development Organization (NEDO) in order to demonstrate the effect of the new coal preparation technology system on deashing and de-sulfurizing of high-sulfur raw coal. The system consists of 'VARI-WAVE' air-pulsated jig, high,shear mixer, flotation cells, tailing thickerer, pressure filter, central control facility and so on, with the throughput of 450 000 ton per annum. The demonstration operation had been conducted since November 2001 to March 2002, at Jinjia Coal Preparation Plant, Panjiang Coal & Electrical Power (Group) Co. Ltd, Guizhou Province, People's Republic of China. High sharpness of separation was obtained by 'VARI-WAVE' air-pulsated jig owing to the trapezoidal pattern of water pulsation. Flotation of

Fuel and Energy Abstracts

July 2004