Fly ashes from coal and petroleum coke combustion: current and innovative potential applications

Abstract

Coal fly ashes (CFA) are generated in large amounts worldwide. Current combustion technologies allow the burning of fuels with high sulfur content such as petroleum coke, generating non-CFA, such as petroleum coke fly ash (PCFA), mainly from fluidized bed combustion processes. The disposal of CFA and PCFA fly ashes can have severe impacts in the environment such as a potential groundwater contamination by the leaching of heavy metals and/or particulate matter emissions; making it necessary to treat or reuse them. At present CFA are utilized in several applications fields such as cement and concrete production, agriculture and soil stabilization. However, their reuse is restricted by the quality parameters of the end-product or requirements defined by the production process. Therefore, secondary material markets can use a limited amount of CFA, which implies the necessity of new markets for the unused CFA. Some potential future utilization options reviewed herein are zeolite synthesis and valuable metals extraction. In comparison to CFA, PCFA are characterized by a high Ca content, suggesting a possible use as neutralizers of acid wastewaters from mining operations, opening a new potential application area for PCFA that could solve contamination problems in emergent and mining countries such as Chile. However, this potential application may be limited by PCFA heavy metals leaching, mainly V and Ni, which are present in PCFA in high concentrations.

Properties of fly ash and metakaolín based geopolymer panels under fire resistance tests

“…To simulate the conditions of exposure to fire, the regulation requires that one of the sides of the protective material be exposed to heat according to a standard temperature curve defined by the equation [1]:…”

Effect of Alkaline Activator to Fly Ash Ratio for Geopolymer Stabilized Soil

“…Scientifically, geopolymer is the reaction of a solid aluminosilicate with a highly concentrated aqueous alkali hydroxide or silicate solution to produces a synthetic alkali aluminosilicate material [3]. Fly ash (residue from coal combustion) is used finely divided residue resulting from combustion of coal and has been used as cement replacement for the recent years [4]. Sodium silicate (Na 2 SiO 3 ) and sodium hydroxide (NaOH) solutions is commonly used to make an alkaline activator [5,6].…”

Цахилгаан Станцын Хаягдал Үнс, Үнсний Хэрэглээ, Үнсийг Манай Улсад Ашиглах Боломж

“…Хаягдал үнсийг цементийн түүхий эд юмуу нэмэлт болгон хэрэглэх нь одоогийн түвшинд ашиглагдаж буй хамгийн том хэрэглээ юм [17]. Нийт гарч буй үнсний 72%-ийг цемент, бетоны үйлдвэрлэлд ашигладаг байна [18].…”