Investigation of Electrostatics in Mineral Particles of Ferruginous Quartzite when Ruptured by Blasting

摘要

Ferruginous quartzite is a composition of the following rock forming minerals: quartz (SiO2); magnetite (Fe3O4); hematite (Fe,). (1) Quartz cell has a tetrahedron shape, with a Si4+ cation in the centre and O2～anions in the vertices. Electronegative degree of Si4+cation equals to 1,9 whereas for 02-anions similar value is 3. S. Quadrivalent Si4_ cation attracts one from four bivalent O2-anions. 85% ~90% of interaction between Si4+cation and O2-anions can be characterized as an ionic bond while the rest 10%～15% as a covalent bond. Single tetrahedron has 4 positively charged silicon cations and 8 negatively charged oxygen anions; thus its non-compensated negative charge amounts to -4. Plane-wise tetrahedrons are connected via vertices, thus forming hexagonal tetrahedron-type cells. The latter being connected together form plane networks with one hexagonal cell in the centre and all the rest around it in a circular pattern. (2) Magnetite cell is a cube with a Fe1666+cation in the centre (electronegative degree equals to 1. 85) and O2-anions in the vertices (electronegative degree equals to 3.5). Thus a single crystallite of magnetite has 2.666 positively charged Fe2666+ cations vs 16 negatively charged O2-anions, and its non-compensated negative charge amounts up to 13.444. In horizontal plane cubic magnetite crystallites are connected via cube vertices (where oxygen anions are located) forming hexagonal cube-type cells. These hexagonal cells are united-via external cube vertices-into networks with one hexagonal cell in the centre and all the rest around it in a circular pattern. (3) Hematite cell is an octahedron with a Fe3+cation in the centre (electronegative degree of 1.9) and O2 -anions in the vertices (electronegative degree equals to 3. 5). A single hematite crystallite has 3 positively charged Fe3+cations and 6 negatively charged O2anions with a total non-compensated negative charge of -9. In a horizontal plane hematite crystallites are united via oxygen anions into octahedron-type hexagonal cells and further into networks. Networks formed by hexagonal cells of tetrahedron, cubic, and octahedron types form in its turn kind of high-rise structures owing to covalent bond between oxygen anions of neighboring hexagonal cells. For bigger particles (up to 0. 15μm) ratio of negatively charged anions to positively charged cations becomes lower: 1) for Fe3O4 from 4.5 to 1.5000; 2) for Fe2O3 from 2 to 1. 222; 3) for SiO2 from 0. 5 to 0.1666. If the particles of magnetite, hematite, and quartz become still bigger the ratio remains practically unchanged. Thus it can be summed up that fine (dust-like) quartz particles emerging in the course of blasting operations have noncompensated positive charge. Hence an obvious recommendation for those working in quarries: to stem boreholes oxidized liquids with pH<7 ～8 are to be used.