BS ISO 7404-4:2017 pdf download – Methods for the petrographic analysis of coals Part 4: Method of determining microlithotype, carbominerite and minerite composition
This document specifies a method,using a graticule with 20 crossline intersections,for determining theproportions of microlithotypes, carbominerite and minerite in coals. It applies only to determinationsmade on polished particulate blocks using reflected white light (about 400 nm to 700 nm).Additionalblue, blue-violet or UV light excitation (365 nm to 440 nm) for better identification of liptinite influorescence may be used especially at low rank coals.
The following documents are referred to in the text in such a way that some or all of their contentconstitutes requirements of this document.For dated references, only the edition cited applies. Forundated references, the latest edition of the referenced document(including any amendments) applies.ISO 7404-1,Methods for the petrographic analysis of coals — Part 1: Vocabulary
ISO 7404-2,Methods for the petrographic analysis of coals — Part 2:Methods of preparing coal samples
3Terms and definitions
For the purposes of this document, the terms and definitions given in IlSO 7404-1 and the following apply.ISO and IEC maintain terminological databases for use in standardization at the following addresses:
-ISO online browsing platform: available at http://www.iso.org/obp
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observation of a portion of the particulate block through the eyepiece graticule made during theanalysis
Note 1 to entry: The allocation of a point to a particular microlithotype, or to carbominerite or minerite, isdetermined by the macerals and/or mineral matter present at the 20 intersections of the graticule.A point is onlycounted if at least 10 intersections fall on a particle.
Examination by using a reflected light microscope and point count procedure of a representative sampleof coal prepared as a particulate block as described in ISo 7404-2.ldentification under an immersionmedium of the microlithotypes from their maceral composition.The proportions of the macerals aredetermined using a graticule having a grid with 20 points of intersection spaced to define a distance of50 um on the specimen between extreme intersections in the x (abscissa) and y (ordinate) directions,respectively. The use of such a graticule allows the analyst to comply with the 5 % minimum contentand 50 um minimum size stipulation.
Immersion medium, having a suitable refractive index and compatible with the microscope objective.
NOTE If reflectance measurements are required on the same particulate block, an immersion oil as specified in ISO 7404-5 is used.
6.1 Reflected?light?microscope, having an immersion objective of magnification between ×25 and ×60 and eyepiece of magnification between ×8 and ×12. The eyepiece shall have the facility for inserting a graticule.
6.2 Graticule, inscribed with a grid having 20 crossline intersections according to the pattern shown in Figure 1. The effective distance between extreme intersections in the x- and y-directions, respectively,is 50 μm.
NOTE 1 With a total number of 20 cross line intersections, a maceral appearing beneath a single intersection can be assumed to occupy 5 % by volume of the area covered by the grid.
NOTE 2 The graticule is designed for use with a particular combination of objective and eyepiece. Change in either objective or eyepiece will necessitate the use of a grid of different dimensions.
6.3 Mechanical or scanning stage, capable of advancing the specimen in the x-direction by equal steps of such length that only a negligibly small proportion of the particles examined receives more than one count on the same particle. The step-length is equal to half the maximum particle diameter, i.e. 0,5 mm to 0,6 mm for samples with a standard top particle size of 1 mm. The stage also permits a similar stepped advance in the y-direction. The stage movement may be actuated manually, by the counter mechanism or a computer attached to the stage.
6.4 Counter/computer, capable of registering the points in each category and preferably the grand total of points counted.
6.5 Sample mounting equipment, comprising slides, modelling clay and levelling press.BS ISO 7404-4 pdf download.