Diatomic heat insulation materials with increased application temperature

Abstract

Results are provided for a study of an increase in application temperature for diatomite objects. Different molding methods and sample mix compositions are described for preparing objects based on diatomite with an application temperature up to 1150°C.The problem of effective use and saving of energy resources includes a list of critical technologies, and energy saving technology, i.e. in priority areas of the development of science and technology and engineering. As is well known [1], there is dissipation into the environment through protective structures of up to 40% of heat with a temperatures of gases discharged from 300 to 160°C, and therefore a reduction in this heat loss is an effective way of reducing the energy expended for manufacturing a production unit, and consequently increasing its competitiveness in domestic and world markets.Heat insulating materials in a refractory lining of a heating unit fulfil an important task, i.e. they retain heat and maintain the temperature at the required production level [2]. For the practical long-term use of any materials as a heat insulator two main characteristics are important [3]. The temperature of the long-term application and the accumulation capacity. The temperature of long-term application depends on the form of the lightweight material and its production technology. The most widespread aluminosilicate lightweight objects and unmolded mixes at the working temperature and with prolonged operation, gradually sinter and there is shrinkage. Here joints of the lining open, there is formation of shrinkage cracks and other defects; the process is accompanied by an additional increase in the thermal conductivity of the lining and heat loss. Silica lightweight heat insulation materials, in contrast to aluminosilicate materials, during prolonged operation and at operating temperatures do not sinter, and in some cases there is a small growth of them (0.1 -0.2%), providing lining tightness. The thermal conductivity of the material is practically unchanged and it remains constant over the whole operating period.Silica raw material is encountered in natural and technical materials in amorphous and crystalline states: in quartzites, quartz sands, tripolite, diatomite, opoka, and marshallite [4]. Of the amorphous materials for producing lightweight objects for industrial purposes there is extensive use of Inzensk deposit (Ul'yanov region) diatomite, as the purest with respect to impurity content. The main technological positions for production and the properties of foam-diatomite objects are given in publications [2,3]. Diatomites of the Inzensk deposit contain 74.80 -88.15% SiO 2 , 3.34 -9.75% (Al 2 O 3 + TiO 2 ), 2.37 -5.26% (Fe 2 O 3 + FeO), 0.47 -0.85% CaO, 0.61 -1.71% MgO, 0.96% K 2 O, 0.74% Na 2 O; Dm cal 2.73 -5.88%. Diatomite is a light porous self-cementing sedimentary rock, forming from residues of microscopic algae and radiolarian skeletons. The amorphous nature of the silica distinguishes it from normal silica. The greatest size of individual skeletons (up to 1...

To blend is a good solution to improve the heat insulation applicability of diatomite ores

“…To increase the porosity feature of the diatomite bricks, sawdust or Kashcheev et al 2009a;Hanna et al 2012;Ibrahim 2012;Da et al 2014;Lui et al 2017;Sari et al 2018). When diatomite is heated to above 1000°C, its amorphous silica structure is damaged and converted to cristobalite (Kashcheev et al 2009b;Ibrahim and Selim 2012). The phase transformation of cristobalite may be the reason of the strength reduction of the diatomite bricks.…”