Natural crystalline flake graphite

Figure 3. Scanning Electron Microscope Images of thermally purified natural crystalline flake graphite 2900G (a), and its ground versions displaying platelet (b) and spheroidal (c) morphologies.

The natural crystalline flake graphite from Zavalie field in Ukraine s Kirovograd Province has been subjected to thermochemical treatment and the resultant product, thermoexfoliated graphite, has been used as carbon material for CM creation. This material was selected because of following considerations ... 

Natural crystalline vein and flake graphite carbon (LOI) 80-99%... 

All graphite has crystal structure but only certain kinds and sizes of natural graphites are commercially classified as crystalline, a term used for import duty purposes. Throughout this article reference is made separately to flake, vein (lump or high crystalline), and amorphous forms, all of which are essentially the same crystalline form of carbon. However, fine structured graphites (cryptocrystalline (2)) have been classified as amorphous. 

Natural graphite may be divided into three grades in respect to grinding characteristics flake, crystalline, and amorphous. Flake is generally the most difficult to reduce to fine powder, and the ciystalline variety is the most abrasive. Graphite is ground in ball mills, tube mills, ring-roller mills, and jet mills wiui or without air classification. Benefici-ation by flotation is an essential part of most current procedures. 

Natural graphite occurs in the form of flakes (scales) and pieces (coarse lumps) as well as in a very finely divided form. The latter is called amorphous graphite, which is a misnomer because even in its finest form it consists of crystals, however small. It is predominantly found in its hexagonal modification, although the rhombohedral form is also found. The degree of crystallinity and carbon content vary from deposit to deposit. 

Oxidized RFL flakes still largely exhibit the expected flake-like nature expected for highly crystalline graphite as can be seen in Figure 24. With the overall flake shape remaining easily identifiable. 

The final natural graphite sample was a purified version of the more ideal, flakelike natural graphite and showed no traces of catalytic activity. As expected this sample exhibited the lowest reactivity and the oxidized microstracture revealed the hexagonal edges and umeactive basal plane expected for highly crystalline graphite flakes. 

Natural graphite is classified into three general types flake (also known asp/umbago), crystalline (vein), and amorphous, varying in physical properties, appearance, chemical composition, and impurities. These differences stem from the type of precursor material (oil, coal, or other carbonaceous deposits) and the natural process by which graphite was formed. Table 10.2 summarizes the characteristics ofthesethreetypes.I lPl... 

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