Coal ultrafine

In an extensive study by Read et al. [93], 10 anionic surfactants were evaluated for their ability to remove pyritic sulfur and ash from ultrafine Illinois no. 5 coal by flotation processes. The authors observed that of the commercially available surfactants, sodium dodecyl sulfate was the most effective on either a weight or a molar basis, followed by a linear AOS (average molweight 272) and alkylpolyethoxylated sulfonates. Of the noncommercial surfactants tested, -(E -b-dodecene-b-suIfonate (f0) was the most effective and better than any commercial surfactant on a dosage/recovery basis. 

Yamashito, H. Yoshida, S. Tomita, A. (1991) Local structures of metals dispersed on coal. 2. Ultrafine FeOOH as active iron species for steam dassification of brown coal. Energy Euels 5 52—57... 

Ultrafine Structures in Coal Components as Revealed by Electron Microscopy... 

Since the work reported by McCartney et al. (9), ultrathin sections of other, more heterogeneous components and mixtures of components of coals of different rank have been prepared and observed. Procedures for minimizing artifacts have been learned and followed, and experience in observation has led to avoiding obvious faults. These sections were often not as large and continuous as those of homogeneous vitrinites, but adequate areas were available for electron microscopy. Observations of these various components revealed ultrafine structures of different size and form. Some of the structures can be correlated with those deduced from other direct or indirect study techniques others are unfamiliar and novel, and suggested interpretations are tentative. 

Figure 9, a fuzzy micrograph at very high magnification, is presented to show an apparent porous structure in fusain. The pores, the small light spots interspersed in the dark matrix, are less than 100 A. in diameter. A previous study has indicated that fusain is the most porous of coal components (5). Of course these ultrafine pores are much smaller than those associated with the ordinary cells of fusain. 

Examination of ultrathin tactions of coal in tko aloctron microscope hat revealed that one type of vitrinite (vitrinite A) it homogeneous, while the remaining vitrinite (vitrinite B) it a two-component material, the components having similar properties to vitrinite A and exinite, respectively. The material similar to exinite occurs in sheets no more than 1000 A. thick and is responsible for the lower reflectance and higher volatile matter yield of vitrinite B. Exinite, micrinite, and semifusinite have been identified in ultrathin sections. By using a technique of impregnation with a lead salt the ultrafine pore structure of vitrinite has been made visible. 

Li Y, Suriyawong A, Daukoru M, Zhuang Y, Biswas P (2009) Measurement and capture of fine and ultrafine particles from a pilot-scale pulverized coal combustor with an electrostatic precipitator. J Air Waste Manag Assoc 59 553-559... 

Physical properties Density Specific gravity Pore structure True density as measured by helium displacement Apparent density Specification of the porosity or ultrafine structure of coals and nature of pore structure between macro, micro, and transitional pores... 

King, J. G., and Wilkins, E. T. 1944. Proceedings of the Conference on the Ultrafine Structure of Coal and Cokes. British Coal Utilization Research Association, London, p. 45. 

The discrepancy between the ASTM organic sulfur values for coals and the sulfur that remains in "deep-cleaned coals has been noted elsewhere (Simmons, F.J., Otisca Industries, Ltd., Syracuse, NY, personal communication, 1988.). Tlie ASTM organic sulfur values obtained with -60 mesh raw coal samples are usually greater than the total sulfur values in deep-cleaned ultrafine coal used in slurries for fuels. It is proposed that the HN03-extraction method for organic sulfur can be used to determine an accurate value for the sulfur content in deep-cleaned coals. 

Separation of Ultrafine Pyrite from High Sulfur Coals by Selective Dispersion and Flocculation... 

A novel technique for separating ultrafine pyrite particles (minus 1 0 micrometers) from coal fines has been conceptually developed and tested. The technique involves the use of a selective polymeric dispersant for pyrite, while flocculating coal particles with a polymeric flocculant. The suspended pyrite can then be removed from the flocculated coal fines which settle preferentially by gravity. 

Blayden, H.E. Gibson, J. Riley, H.L. Proc, Conf, Ultrafine Structure of Coals and Cokes, BCURA (London) 1944, p.176. 

Ultrafine Struct. Coals and Cokes, BCURA (London) 1944, p. 176. 

Separator, the Falcon Concentrator, and the Knelson Concentrator. The development of advanced ultrafine dense-medium systems, such as Carefree Coal and MicroMag, also have the potential to improve cleaning of coal fines. However, none of these processes has yet achieved any significant degree of commercialization. 

Ultrafine oil slurry Ultrafine coal particle slurried with heavy oil and additives 40 Commercialized in the U.S. 

High concentration ultrafine coal-water slurry Ultrafine coal particle slurried with water and additives 70 Under development... 

Combustion particles are of complex chemistry, carrying most of the trace elements, toxins or carcinogens generated from the combustion process. Combustion of different types of fuels results in emissions of various trace elements which are present in the fuel material. In most cases there is not just one specific element that is related to the combustion of a particular fuel, but a source profile of elements [2]. For example, motor vehicle emissions contain Br, Ba, Zn, Fe and Pb (in countries where leaded petrol is used) and coal combustion results in the emission of Se, As, Cr, Co, Cu and Al. For comparison, the crustal elements include Mg, Ca, Al, K, Sc, Fe and Mn. Since most of the trace elements are nonvolatile, associated with ultrafine particles and less prone to chemical transformations, they often remain in the air for prolonged periods of time in the form in which they were emitted. 

The final session responded to the question If the mineral matter is in the coal, what can be done to remove the mineral matter This session dealt with a number of techniques to physically remove the mineral matter in processes called coal cleaning. These processes involve crushing and in some cases pulverizing to fine and even ultrafine sizes to permit the liberation of the mineral matter from the coal. An efficient separation requires removal of mineral matter with a minimum removal of the desirable combustible material. 

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