Center of Engineering Maintenance of Production of Polar Division of “Norilsk Nickel” MMC, Norilsk, Russia

A. F. Petrov, Head of Laboratory, e-mail: petrovaf@nk.nornik.ru
S. G. Anapolskaya, Сhief Specialist
A. V. Kelekhsaev, Chief Specialist
Z. A. Gagieva, Leading Engineer
S. I. Matveeva, X-ray Laboratory Assistant

Researches revealed that all samples of scaffolds are layered, which corresponds to the sequence of material sedimentation on the gas pipe walls. Growth of scaffolds is not constant, but cyclic, which is connected with the periodic entrance of fine-dispersed or humid materials ino the furnace. Chemical analysis showed, that decreasing of non-volatile charge components (Cu, Ni, Co) takes place by the gas pipe section length. Mainly, the gas pipe scaffold consists of iron, calcium, aluminium and silicon oxides; magnetite; calcium, magnium and iron silicates and sulphates of metals. As a results of phase analysis of scaffold samples, there was substantiated, that samples consist of large quantity of components: both the components, included in the content of initial raw materials, and the components, which are formed in the gas pipe section during the interconnection of dust and gaseous phase. At the same time, during the passage of gas-dust flow by the gas outlet section, the oxides formation processes are replaced by the sulphate formation processes. According to the content, scaffolds are more closed to ingrained ore. It can be supposed, that sanidine (Na, K)(Si₃Al)O₈ and anorthoclase Na_0.71K_0.29AlSiO₈ are the cement binding of scaffold. There are shown the basic reasons of scaffolds formation in gas pipes:
— initiation of turbulent flows in the area of changings of gas flows direction in gas pipes;

— existing of factors, conductive to the transformation of scaffold: melting, decriptation and dust sedimentations melting with formation of complex compounds of magnetite, silicates and sulphates. In addition, increasing of scaffolds formation in the gas pipe systems of weakened furnaces is connected with increasing of charge processing, end gas volume and entrance of fine, humid material and dust entrainment.

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