An Alternative to Clay in Building Materials: Red Mud Sintering Using Fly Ash via Taguchi’s Methodology

Abstract

“Red mud” or “bauxite residue” is a highly alkaline waste generated from alumina refinery with a pH of 10.5–12.5 which poses serious environmental problems. Neutralization or its treatment by sintering in presence of additives is one of the methods for overcoming the caustic problem as it fixes nearly all the leachable free caustic soda present in red mud. In the present study, feasibility of reducing the alkaline nature of red mud by sintering using fly ash as an additive via Taguchi methodology and its use for brick production, as an alternative to clay, is investigated. The analysis of variance (ANOVA) shows that sintering temperature is the most significant parameter in the process. A pH of 8.9 was obtained at 25–50% of red mud and 50–75% fly ash with water and temperature of . Alternatively 50% of red mud can be mixed with 50% of fly ash with water at temperature of to get a pH of about 8.4. The mechanism of this process has been explained with also emphasis on chemical, mineralogical, and morphological analysis of the sintered red mud. The results would be extremely useful in utilization of red mud in building and construction industry.

Manufacture of ceramics with high mechanical properties from red mud and granite waste

“…In this field, red mud is used as a starting material, along with traditional compounds like clay, silica or lime. There are several studies that endorse the use of red mud in concrete or cement (15) and in ceramic manufacture (bricks, tiles) (16,17), all of them meeting the required industrial standards.…”

Alpha Emitter Intrinsic Concentration in Copper required for Nuclear Spectrometry Application

“…In fact TENORM activity concentration is from 4 to 10 times the limits set for building materials in the European Union. The Venezuelan RM samples having high pH grade (11)(12), toxic metals and radioactive elements with concentration hundred times the soil average value, pose a serious and alarming environmental concern. Nevertheless it might be used for land reclamation, for the construction of dams and embankments, or conveniently reprocess again to extract elements such as iron (content 20 to 50% by weight).…”

“…Red mud dried matter was analysed in order to compare radon exhalation value with those measured for the purpose made bricks. NRPB/ISS diffusion chamber with CR-39 TM often found for radon survey, is a plastic device with a semi-spherical shape of 5.5 cm diameter with an inner volume of 0.0144 and 2 cm high (flat bottom) [12], provided with microslits, so that after it is properly closed, allows the diffusion of gases. Radon concentration inside the chamber reaches during measuring time interval, the same level as that prevailing inside the glass bottle ambient air, independent of the radon daughter's concentration.…”

“…In the case of samples from the industrial waste BAUXILUM pond (Puerto Ordaz, Bolivar state), high energy resolution gamma spectrometry measurements indicate that radioactive concentration is between 2.0 and 3.5 kBq.kg -1 [4]. Nevertheless the international literature [9] reported its utilization as additives in geopolymers [10], [11], clay material, cements, ceramics, fired and no fired breaks [12]. A review on this subject is given by Paramguru et al [13].…”

Synergistic Sintering of Lignite Fly Ash and Steelmaking Residues towards Sustainable Compacted Ceramics

“…In order to avert this environmental impact, the FA valorization in construction and other civil engineering applications should be considered. Several studies were already focused upon the addition of various loadings of FA in clayey mixtures, for the production of conventional extruded or sintered ceramics or even composite materials, destined for construction applications [10][11][12][13][14][15]. At the same time, several studies reported the usage of FA for the production of advanced ceramics and composite materials [16,17].…”