%0 Journal Article
%T Electro-Thermal and Semiconductivity Behaviour of Natural Sintered Complex Carbonate Ore for Thermo-Technological Applications
%A Loutfy H. Madkour
%J Journal of Geochemistry
%D 2014
%R 10.1155/2014/451782
%X The polymetal (Zn, Pb, Fe, Ca, Mg, Cd, Ba, Ni, Ti, and SiO2) complex Umm-Gheig carbonate ore is subjected to sintering treatment at 573, 773, 973 and 1273£¿K respectively for four hours. Chemical, spectral, X-ray and differential thermal analyses are applied for the native ore as well as for the samples preheated and sintered. The current versus applied DC voltage ( ¨C ) characteristics, bulk density , percent shrinkage (% ), activation energy and energy gap are established for the sintered ore. The electrical conductivity , thermal conductivity ( ) and thermoelectric power coefficient have been investigated as a function of applied temperature for the sintered ore materials. The electrical conduction is mainly achieved by free electrons near or in conduction band or n-type. As the sintering temperature increases the conduction of the ore is also increased due to the recombination process taking place between the electrons and holes. Electrons hopping between Fe2+ and Fe3+ are the main charge carriers. The formation of Fe3O4 at high sintering temperature acts as an active mineralizer, thus inducing an increased degree of crystallinity and a more ordered crystal structure is produced. 1. Introduction The polymetal deposits of the Red Sea ore belt (a zone extending NW-SE for a distance of 130£¿km) represent a complex morphogenetic type of mineralization [1]. The chief minerals are hydrozincite, zinc blende, smithsonite, and cerussite, while silica and carbonates constitute the bulk of the gangue. The investigated sample contains 30.7% Zn, 7.99% Pb, 5.05% Fe, and 6.58% SiO2. The minerals present in the complex ore are often so closely intergrown that either it is difficult to obtain suitable high-grade concentrates at high recoveries [2] by physical methods, or the recovery of metals from the respective concentrates is poor. Madkour and others [3¨C8] investigated experimentally the thermochemistry of the complex ores roasting, giving some theoretical thermodynamic calculations, for the recovery of metal value. It is possible to control the calcine composition by controlling the temperature and air-solid, an important step for understanding the properties and conduction mechanism of ZnO [9¨C11]. The solid state sintering represents a classical method for obtaining of materials with wide application possibilities, as microwave materials [12], ferrite materials [13], and others. In this sense, the aim of the present work is to investigate the electrical and thermal properties of the natural polymetal complex ore with a series of sintering temperatures: 573, 773,
%U http://www.hindawi.com/journals/jg/2014/451782/