Preparation, properties and applications of fly ash-based porous geopolymers: A review

Development of porous geopolymers foamed by aluminum and zinc powders

Recently, more and more attention has been paid to the removal of nickel ions due to their negative effects on the environment and human health. In this research, fly ash obtained as a result of incineration of municipal sewage sludge with the use of circulating fluidized bed combustion (CFBC) technology was used to analyze the possibility of removing Ni(II) ions in adsorption processes. The properties of the material were determined using analytical methods, such as SEM-EDS, XRD, BET, BJH, thermogravimetry, zeta potential, SEM, and FT-IR. Several factors were analyzed, such as adsorbent dose, initial pH, initial concentration, and contact time. As a result of the conducted research, the maximum sorption efficiency was obtained at the level of 99.9%. The kinetics analysis and isotherms showed that the pseudo-second order equation model and the Freundlich isotherm model best suited this process. In conclusion, sewage sludge fly ash may be a suitable material for the effective removal of nickel from wastewater and the improvement of water quality. This research is in line with current trends in the concepts of circular economy and sustainable development.

https://www.mdpi.com/1996-1944/14/11/3106/pdf

Highly Effective Adsorption Process of Ni(II) Ions with the Use of Sewage Sludge Fly Ash Generated by Circulating Fluidized Bed Combustion (CFBC) Technology

Since 1980, numerous studies have been conducted to recycle plastic waste and fly ash into a new material called composite material. This paper aims to evaluate the development of this composite material within four decades of progress review. The evaluation is based on their accomplishments or findings regarding the method used to recycle the Polyethylene Terephthalate PET (RPET) waste to produce the composite materials, mechanical properties, fly ash modification, and previous researcher limitations. In the early 1980s, the researchers investigated the composite potential of the material by polymerizing PET and mixing it with fly ash before the mechanical recycling method discovered in the late 1990s that combined PET flakes with fly ash in an extrusion process to create a composite material. To improve polymer and fly ash compatibility, researchers added a silane coupling agent, used different fly ash particle sizes, and modified the surface with sulfuric acid solutions (5, 10, and 15%) before mixing with RPET. 

Development of composite material from Recycled Polyethylene Terephthalate and fly ash: Four decades progress review

The novel class F fly ash-based geopolymer, largely made of fly ash from the coal solid waste, was used as a kind of grouting material in the coal and electricity-integrated mine from which the solid waste comes, for the purpose of in situ utilization of fly ash. The ratio experiment of material, designed through the orthogonal method, was used to study material properties such as fluidity and strength which are important to the application of mine grouting, and the optimal material proportioning scheme for Green Fly Ash-based grouting material is determined. It has been found out that there was serious rib spalling, roof deformation, obvious floor heave, crack development, and some water seepage in the permanent refuge chamber of the mine. Therefore, to solve these problems, a specific scheme of grouting reinforcement for the surrounding rocks of the permanent refuge chamber and roadway in this mine was designed. Through an analysis of the reinforcement effect of the cementation of surrounding rock after the grouting process, it can be concluded that the green fly ash-based polymer as grouting material can well penetrate into the cracks of the broken surrounding rock and get fully cemented with the surrounding rock and that it can reduce the deformation of the surrounding rock effectively, increase the integrity, and improve the carrying capacity of the surrounding rock. Besides, the grouting reinforcement effect of surrounding rock was verified through numerical simulation, and the grouting process design of green fly ash-based polymer mine was discussed. This study can provide a green and economical approach to the in situ utilization of fly ash which is a kind of coal solid waste.

/pdf/a-novel-class-f-fly-ash-based-geopolymer-and-its-application-cjr8nmayek.pdf

A Novel Class F Fly Ash-Based Geopolymer and Its Application in Coal Mine Grouting

The aim of this paper is to study the particle size effect of fly ash (FLA) on pore structure and strength of Fly Ash Foamed Geopolymer (FAFG). Information on the macro-pores such as macro-pore size and distribution of FAFG is captured through binarization processing. Porosity and compressive strength of FAFG are respectively tested by Archimedes density test method and uniaxial compressive strength test method. It can be concluded that the FLA particle size has an effect on the pore structure and strength of FAFG. More specifically, the effect of FLA particle size shows itself macroscopically on the quantity of middle and large macro-pores and the uniformity of macro-pores distribution, and microscopically on the quantity of micro-holes and cracks and calcium silicate (C-S-H) quantity at the early stage of FAFG mixture. All of the properties of FAFG follow some kind of changing rule except at the turning point when FLA particle is of 0.125~0.25 mm in size. To explain clearly the root cause of FLA particle size effect on FAFG, SEM, and XRD are employed to explore the microstructure of FAFG and the component of FLA. It turns out to be the amorphous phase SiO2 content in FLA of different particle sizes which could determine the reaction extent of FAFG mixture.

/pdf/fly-ash-particle-size-effect-on-pore-structure-and-strength-19lappk8fx.pdf

Fly Ash Particle Size Effect on Pore Structure and Strength of Fly Ash Foamed Geopolymer

The invention discloses a flyash-based goaf grouting material and a preparation method thereof. The flyash-based goaf grouting material is prepared from the following components in parts by weight: 0.6-0.8 part of flyash, 0.2-0.4 part of cement clinker, 0.03-0.05 part of palygorskite powder, 0.008-0.012 part of hydroxypropyl methyl cellulose, 0.03-0.05 part of gypsum, 0.06-0.1 part of sodium silicate and 0.8-1.2 parts of water. The flyash-based goaf grouting material disclosed by the invention realizes resource recovery in-situ utilization of coal mine solid waste, has the characteristics of simple process, good liquidity, moderate setting time and good water retaining capacity, and is suitable for performing grouting fire prevention and extinguishment treatment on goaf through grouting pipelines in a coal mine.

Flyash-based goaf grouting material and preparation method thereof

The invention discloses a pressure stabilizing device of a rock drilling and rock breaking experiment machine. The device comprises an oil cylinder body, a loading mechanism, an impact platform, a drill rod, a drill rod platform and displacement sensors. The loading mechanism comprises an oil cylinder piston arranged in the oil cylinder body, and a lifting platform arranged on the lower end of theoil cylinder piston, the upper end of the drill rod platform is located in a guide hole of the oil cylinder piston, the lower end of the drill rod platform is fixed to the impact platform, multiple spring pull rods are arranged on the impact platform and are in one-to-one corresponding to lifting holes, the spring pull rods penetrate through the lifting holes, each spring pull rod is sleeved withtwo springs, the two springs are located above and below the lifting platform correspondingly, the drill rod is arranged below the drill rod platform, and the two displacement sensors are connected with the lifting platform and the spring pull rods through a lifting platform displacement measuring rod and a drill rod displacement measuring rod correspondingly. A rock sample can be subjected to rock breaking and drilling experiments under the drilling pressure stabilizing condition, the structure is simple, operation is convenient, and the test effect is good.

Kang Yanlei

Papers

Fly Ash Particle Size Effect on Pore Structure and Strength of Fly Ash Foamed Geopolymer

Flyash-based goaf grouting material and preparation method thereof

Pressure stabilizing device of rock drilling and rock breaking experiment machine