STUDYING THE COMPRESSIBILITY OF GROUND  METALLURGICAL RAW MATERIALS

Abstract

The preparation of fine-grained mineral raw materials for ferrous metallurgy by pelletizing is addressed. Under laboratory conditions, the dependences showing the compressibility of metallurgical charges on the nature of the raw materials and technological factors of the pelletizing process were studied. To quantify and compare compression performances, a new measure was developed such as the compressibility of ground materials. Using nonlinear regression analysis and methods of experiment planning theory, a mathematical description for the dependences of the compression coefficient on the following factors was carried out: the plasticizer content (ranging from 0 to 50%) and the moisture content of the charge (from 0 to 10%), hardness of the particles according to the mineralogical scale (from 2 to 6 units), dynamic viscosity of the binder (from 1 to 657 mPa · sec), amount of the carbon-containing component (from 10 to 90%), and particle size of the iron- and carbon-containing components in the charge (from 1 to 4 mm). The compaction pressure range is limited to 220 MPa. Three mathematical models were produced to establish relationships between the charge compressibility and the indicated factors as polynomial dependencies and as Lorentz function. The quality of the models was assessed using standard statistical indicators: the Cochran and Fisher tests and the average relative error. The models were analyzed, including that by solving appropriate optimization problems. Extremes of the functions for metallurgical charges were established and technological recommendations were obtained. The results can be used in the planning of measures to improve the compressibility of charges from mineral raw materials and the development of optimal technological pelletizing modes.