Influence of Thermal Stability of Quartz and the Particle Size Distribution of Burden Materials on the Process of Electrothermal Smelting of Metallurgical Silicon
The article describes the thermal stability of quartz deposits in Kazakhstan-Aktas and Sarykul. It is established that the quartz of the Aktas deposit is a raw material with low thermal stability, and quartz is of medium-durability at Sarykul deposit. The complex influence of the thermal stability of this raw material on the technological parameters of smelting of technical silicon under experimental industrial conditions of electrothermal melting in a furnace with a capacity of 30 MVA was studied at LLP “Tau-Ken-Temir” (Kazakhstan). A new method for optimizing the smelting of commercial silicon has been developed, even when using raw materials with low thermal stability. The main idea of the method is that the less thermally stable quartz is used, the more the initial size of its pieces should be. Optimum values of the average size of pieces of quartz-Aktas(85-95 mm) and Sarykul-(30-40 mm) are obtained.
Changes in Quartz During Heating and the Possible Effects on Si Production
In Si and FeSi production, the main Si source is SiO2, in the form of quartz. Reactions with SiO2 generate SiO gas that further reacts with SiC to Si. During heating, quartz will transform to other SiO2 modifications with cristobalite as the stable high-temperature phase. Transformation to cristobalite is a slow process. Its rate has been investigated for several industrial quartz sources and has been shown to vary considerably among the different quartz types. Other differences in behavior during heating between these quartz sources, such as softening temperature and volume expansion, have also been studied. The quartz-cristobalite ratio will affect the rate of reactions involving SiO2. The industrial consequences and other implications of the observed difference between quartz types are discussed. Initial studies of industrial quartz were published by Ringdalen et al. In the current work, a new experimental method has been developed, and an investigation of several new quartz sources has confirmed the earlier observed large variation between different sources. The repeatability of the data has been studied and the effect of gas atmosphere investigated. The results from the earlier work are included as a basis for the discussion.
Calculation of Complex Radiant Heat Load From Surrounding Radiator Surface Temperatures
Abstract A method for calculating the radiant heat exchange between an absorber and individual radiating components in its surroundings is reported. Radiator surface temperatures, ambient and absorber temperatures, and configuration factors for radiating components in the surroundings are used in the customary radiant heat exchange formulae. Simplified methods for calculating or estimating configuration factors for radiators of various shapes solely from angles, subtended at the absorber by the radiators are presented. The method has been verified in the laboratory under controlled conditions and has been used to advantage in the field studies. The method has advantages over the globe therometer method in certain applications.