PROJECT’S NOVELTY AND ORIGINALITY DEGREE consists in the possibility of using solar energy for different processes of metallic and non-metallic materials processing technologies: heating, melting, burning. The contributions are based on the critical analysis of actual stage where it results the importance and feasibility of such equipment for materials heat processing based on non-conventional energy: solar energy. The type of the aimed constributions is energy and economic efficiency, national and European priorities. The most important researches refer to some metals and refractory materials behavior at high temperatures; also refer to some materials purification and the use of some chemical syntheses. In the figure it is presented the parabolic reflector of a solar furnace. Almost 60 plate mirrors are automatic following the sun and they concentrate the light into the reflector. The reflector concentrates sun’s rays light (heat) in order to produce approximately 1 MW and a temperature of 3300 °C. The furnace can use this temperature to produce steel in the crucible without a complementary energy source for realizing the heat process.

Steel or aluminum production needs a great deal of energy quantities. This is normally delivered of electric energy, natural gases or conventional fuels. Solar furnace uses energy delivered of sun’s power. In the image it can be noticed how sun’s rays can be focused towards the crucible where the ore is. This is heated at a very high temperature until it melts and it can be founded later on. Pollution is practically inexistent because solar energy is a pure form of energy. One of the most important applications of the solar furnaces is materials melting with higher melting point.

If the surface of a solid material is subjected to intense radiation from focus zone of a solar furnace it take place the melting of the material on a section whose area is approximately equal to Sun’s image area. Molten material quantity increases and forms a liquid cavity as heat gets into solid. Through such a process it is possible the melting procurement into a crucible made exactly from the material which is to be molten; this is cause to the existence of a high temperature gradient between the molten material and crucible’s exterior. In conventional furnaces the crucible is heated from exterior, thus, it always has a higher temperature than the molten material. That is why in such furnaces the crucible must be made from a more refractory material than the material which is to be molten. In addition it must be chemically inert towards molten material. The achievement difficulties of these two conditions increase as the melting point of the studied material is higher and over 2000 °C are few chances to avoid chemical reactions. The use of the solar furnaces in melting materials with high refractoriness overbears these important limitations of the conventional furnaces. Thus, melting can be realized in furnaces with horizontal axis. The furnace is rotated around the horizontal axis and has the interior diameter several times bigger than sun’s image diameter. If the speed of rotation is low the molten material remains downside the furnace and rotation helps to achieve a uniform distribution of heat. For higher speeds of rotation the molten material is centrifugally – forming a cavity- which will not permit its discharge from the furnace. The exterior walls of the furnace -made of steel- can be cooled with water for maintaining a high temperature gradient in the walls (if necessary). Under the situations when melting should realize a certain protective atmosphere it is passed an adequate gas flow as indicated in the figure. Among the materials to be studied are: quartz, zirconium dioxide, corundum, ceramic oxides and materials like carbides, nitrides and boron for which conventional melting techniques present a series of inconvenient. As well it can be studied the practice possibility for using solar furnaces in steels melting. Technically the crucible can be easily made by introducing into furnace cavity a refractory powder (like mullit) and sintering or even melting it by centrifuging the furnace exposed to solar radiation. That is why scrap is introduced in furnace, it melts and then if necessary it is molten. The performances of such a solar furnace must not be special because there is sufficient temperature of 2000 – 2500 °C. For future, a higher interest presents melting some other metals more expensive than steel like titanium, zirconium and molybdenum. In this case it must be assured an inert protective atmosphere and thereby it must be taken into account the complications and expenses related to these. Other applications of solar furnaces: impurities evaporation, zonal melting, fractionates crystallization, zirconium oxide extraction from zircon (zirconium silicate) and the materials study under thermal shock conditions.