Ore classification introduction

Neutral refractories

Neutral refractories include chromite and carbon refractories.
Chromite refractories contain at least 25% Cr ₂ O ₃ and have a fire resistance of about 1800 ^o C. They are used to separate layers of acidic and basic refractories in order to prevent interaction between them.
Carbon refractories contain up to 90% carbon and are divided into graphite and carbon. Crucibles for melting various metals are made from graphite, and individual parts of metallurgical furnaces are made from coal ( t = 2000 ^o C). It cannot be used in steel-smelting furnaces because the steel is carburized.
Slag - formed during the smelting of metals and has a low density (2-4 g/cm ³ ), floats above the liquid metal, isolating it from the direct influence of furnace gases. They are formed from fused waste rock, fluxes, fuel ash and refractory lining as it breaks down, from absorbed gases and compounds released from the metal. The composition of the slag, melting temperature , fluidity, and chemical activity largely determine the success of smelting and the yield of metal of a given composition. The slags are basic with a predominance of basic oxides and acidic with a predominance of acid oxides.
Fluxes. They facilitate slagging during metallurgical smelting, promote the fusion of waste ore, forming with it, as well as with ash (fuel, slag that melts at a calculated temperature; they bind and ensure the transfer of harmful impurities from the metal into the slag. Fluxes are acidic, containing an excess of SiO ₂ ; basic - basic oxides CaO , MgO , MnO , FeO , etc. and neutral ones containing alumina, as well as alkali and alkaline earth chlorides and fluorides.

Pyrometallurgical processes

These processes in most cases occur at high temperatures and often involve the melting of materials. Pyrometallurgical processes are divided into two groups based on temperature and the nature of the phases involved: roasting and metallurgical smelting.