Rounded atelectasis after exposure to refractory ceramic fibres (RCF)

Background Refractory Ceramic fibres (RCF) are man-made mineral fibres used in high performance thermal insulation applications. Analogous to asbestos fibres, RCF are respirable, show a pleural drift and can persist in human lung tissue for more than 20 years after exposure. Pleural changes such as localised or diffuse pleural thickening as well as pleural calcification were reported. Result A 45 years old man worked in high performance thermal insulation applications using refractory ceramic fibres (RCF) for almost 20 years. During a occupational medical prophylaxis to ensure early diagnosis of disorders caused by inhalation of aluminium silicate fibres with X-ray including high-resolution computed tomography (HRCT), bilateral pleural thickening was shown and a pleural calcification next to a rounded atelectasis was detected. Asbestos exposure could be excluded. In pulmonary function test a restrictive lung pattern could be revealed. In work samples scanning electron microscopy (SEM) including energy dispersive X-ray analysis (EDX) classified used fibres as aluminium silicate fibres. X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) showed crystalline as well as amorphous fibres. Conclusions A comprehensive lung function analysis and in case of restrictive lung disorders additional CT scans are needed in RCF exposed workers in accordance to the guidelines for medical occupational examinations comparable to asbestos exposed workers.

Pyrophyllite: An Economic Mineral for Different Industrial Applications

Pyrophyllite (Al2Si4O10(OH)2) is a phyllosilicate often associated with quartz, mica, kaolinite, epidote, and rutile minerals. In its pure state, pyrophyllite exhibits unique properties such as low thermal and electrical conductivity, high refractive behavior, low expansion coefficient, chemical inertness, and high resistance to corrosion by molten metals and gases. These properties make it desirable in different industries such as refractory; ceramic, fiberglass, and cosmetic industries; as filler in the paper, plastic, paint, and pesticide industries; as soil conditioner in the fertilizer industry; and as a dusting agent in the rubber and roofing industries. Pyrophyllite can also serve as an economical alternative in many industrial applications to different minerals as kaolinite, talc, and feldspar. To increase its market value, pyrophyllite must have high alumina (Al2O3) content, remain free of any impurities, and possess as much whiteness as possible. This paper presented a review of pyrophyllite’s industrial applications, its important exploitable properties, and the specifications required for its use in industry. It also presents the most effective and economical techniques for enriching low-grade pyrophyllite ores to make them suitable for various industrial applications.

3D Printing of Ceramic Shell Molds for Precision Casting of Turbine Blades

Traditionally, the technology used in the production of gas turbine blade castings characterized by a large number of technological conversions, high labor costs with a large amount of manual labor and the need to produce various types of complex and expensive equipment at different stages of production. This work aims to reduce the time and money spent on the manufacturing of ceramic shell shapes — a form suitable for the standard methods of precision casting by traditional heat-resistant nickel alloys. The proposed approached involves obtaining a shell shape with an internal core as a single, non-assembled product, without lengthy and time-consuming design and manufacturing processes involved in forming equipment for the production of castings based on smelted models. The proposed method is based on the use of 3D printing with refractory ceramic pastes. Using both uncooled and cooled blades as examples, models of casting molds were designed, technological processes were developed, and ceramic shell molds were manufactured. Experimental casting into a manufactured ceramic shell mold for an uncooled blade with a bandage shelf was performed and showed satisfactory results.

New process to obtain unslaked lime through microwave hybrid heating and its fluid dynamics computational modeling

This study aimed to analyze the advantages of limestone calcination through a conventional microwave heating technique. For such a purpose, the microwave was merged by hybrid heating and a refractory ceramic internally coated with copper oxide was used with a conventional muffle furnace. It has also been analyzed the behavior of calcining limestone with different masses and variations in retention time using a muffle furnace and microwaves, both with and without using the refractory ceramic. Afterwards, the process has been modeled so as to analyze temperature versus retention time. As a result, calcination using a microwave susceptor with the refractory ceramic substance proved to be a process that takes 35% less time than conventional methods. Furthermore, there has been a reduction in 66.1% of energy expenditure. It was also observed that the new procedure offers advantages in reduced greenhouse gases emissions on account of the release of only a single substance, ease of air treatment in industrial environments and being a more economically viable process for limestone calcination, which can be further utilized by companies belonging to such a sector. Its patent deposit number BR 202018073002-4 U2 in INPI.