Classification of coals according

Although the validity of the analytical data is uncertain, a generally accepted fouling classification of coal, according to total chlorine content (ASTM D-2361 ISO 352 ISO 587), is as follows ... 

Table 1 Classifications of coal according to rank, and chemical and physical parameters characteristic of rank.

McCartney J. T. and Teichmuller M. (1972) Classification of coals according to degree of coalification by reflectance of the vitrinite component. Fuel 51, 64—68. 

Classification of Coals.—Coals obtained west of Pittsburgh are generally of inferior quality. Coal may be classified according to either the proximate or the ultimate analysis. Thus Frazer s classification ... 

An early method that attempted a definitive classification of coals on the basis of their composition and heating value was based on the ratio of the fixed carbon to the volatile combustible matter (C/V.Hc) (Frazer, 1877) in which the ratio of the volatile to fixed combnstible matter was a logical basis for the classification of coals. After various attempts to make the fuel ratio of the different coals fit the descriptions of the varieties of coal, it was concluded that coal could be classified according to the fuel ratio within wide limits, and the following divisions were snggested ... 

In the ASTM system for the classification of coals by rank and in the International System for the classification of hard coals (Chapter 2), high-volatile coals are classified according to their calorific value on a moist basis. In this instance, the calorific value is quoted for the coal containing its natural bed moisture. 

TaUe 17.5. Classification of coals by rank according to ASTM D388... 

One classification of coal is by rank, i.e., according to the degree of metamorphism, or progressive alteration, in the natural series from lignite to anthracite. In the ASTM classification, the basic criteria are the fixed-carbon content and the calorific valnes (in British thermal units) calcnlated on a mineral-matter-free basis. 

The pulverized coal ashes used in this stndy were obtained from Dutch and Danish coal fired installations. According to an earlier proposed classification acidic, neutral and alkaline reacting ashes were selected for specific purposes [1]. Some of the data presented in this paper refer to ashes collected in an earlier study on the classification of coal ashes [13]. The soil samples—clay, sand and peat— were collected from the C— horizon in the Netherlands by STIBOKA, Wageningen. More detailed information on the sample origin and properties is given in ref [14]. In this paper only data relevant to molybdenum behaviour will be presented. In table I the molybdenum content of the... 

Analysis. Analyses of a number of lignitic coals are given in Table 3. Figure 1, a distribution plot of 300 U.S. coals according to ASTM classification by rank, indicates the broad range of fixed carbon values (18). According to the ASTM classification, fixed carbon for both lignite and subbituminous coals has an upper limit of 69%, but in practice this value rarely exceeds 61%. 

Classilicalion of major coals according to rank or age is given in Table I. The criteria given in the prior paragraph are used in classifying the older and younger coals. Seventeen United States coals are arranged in order of the classification of Table 1 and presented in Table 2. 

Coal classification is the grouping of different coals according to certain qualities or properties, such as coal type, rank, carbon-hydrogen ratio, and volatile matter. Thus, due to the worldwide occurrence of coal deposits, the numerous varieties of coal that are available, and its many uses, many national coal classification systems have been developed. These systems often are based on characteristics of domestic coals without reference to coals of other countries. However, it is unfortunate that the terms used to describe similar or identical coals are not used uniformly in the various systems. 

Note (1) Where the ash content of coal is too high to allow classification according to the present systems, it must be reduced by laboratory float-and-sink method (or any other appropriate means). The specific gravity selected for flotation should allow amaximum yield of coal with 5-10% of ash. (2) 332a. .. > 14-16%VM. 332b. .. > 16-20%VM. 

The heterogeneity of coal, exemplified by Figure 1, is inherited from the diversity of source materials that accumulated in a peat swamp. Coals may be compared, contrasted, and classified on the basis of variations in the proportions of these microscopically identifiable components. Such a classification is referred to as a classification according to type. Coals may also be classified according to how severely geological alteration processes, referred to collectively as metamorphism, have affected their properties this is classification according to rank. These two classification methods are independent and orthogonal therefore, within certain limits, any type of coal can be found at any rank. 

It should be pointed out that the lithotype classification for brown coal does not conform to that for black coal. To date, the International Committee for Coal Petrology (ICCP) has not finalized a brown coal lithotype classification however, it is generally agreed that a lithotype classification should be based on macroscopic characteristics that can be determined in open cut faces. This principle has been followed in classifying the Latrobe Valley coals according to a system developed and used by the State Electricity Commission of Victoria (SECV) (25). 

Fly ash starts out as impurities in coal, mostly clay, shales, limestone, and dolomite, which ends up as ash, and fuse at high temperature becoming glass. Two U.S. classifications of fly ash are produced. Class C and Class F, according to the type of coal used. Class C fly ash, typically obtained from subbituminous and lignite coals, must have more than 50% total of silica, alumina, and iron oxide. Class F fly ash, typically obtained from bituminous and anthracite coals, has more than 70% of these oxides. 

Processing production of coal sample and physical mechanic parameters test are in strict accordance with the provisions of Measurement method of coal and rode physical and mechanical properties (GB/T 23561-2009), and Measurement method of coal seam impact tendency classification index (MT/T 866-2000). The experiment determined natural apparent density, compressive strength, consistent coefficient, elastic modulus, deformation modulus, wave velocity, rock burst energy index, elastic energy index, dynamic failure time, and other parameters. The determination results as shown in Table 1. 

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