Study on Fly Ash Based Porous Ceramsite as Biological Filter Media

Using fly ash as a raw material,porous ceramic particles with an apparent density of 1.21 g/cm^(3),a visible porosity of 51.03%,and a specific surface area of 4.26 m^(2)/g were prepared and used as biofilter materials for wastewater treatment.Through SEM,XRD analysis,and heavy metal leaching analysis,it was found that porous ceramsite were porous materials with rough surfaces.After calcination,the newly formed mineral was silicate calcium feldspar.The heavy metal concentration in the leaching solution of porous ceramsite met the national surface water quality requirements.The treatment of domestic sewage showed that the volumetric loads of COD Cr,NH_(4)^(+)-N,and TN removed by the aerated biofilter were 5.23,0.98,and 0.35 kg/(m^(3)·d),respectively,with removal rates of 85.46%,96.13%,and 32.31%.

Preparation and Properties of High-strength Ceramsite in Low Water Absorption

Fly ash used as the main raw materials,incorporated with sintering expansion additive and fluxing additive in different ratio,was sintered high-strength lightweight aggregates of fly ash (ceramsite) in the laboratory-controlled electric furnace.The results show that the optimal sintering system is the sintering temperature range of 1250 ℃ to 1280 ℃ and retaining time of 5 min-10 min.The bulk density,the apparent density and 24 h water absorption of ceramsites decrease with the increase of sintering additive and the decrease of the amount of fly ash.The addition of fluxing additive can significantly enhance the compressive strength of ceramsite pellets,reduce its water absorption at 24 h and improve pore-shape ofinner structure.The firing coefficient (Pk) changed within 7.8-8.1 of raw materials can prepare high strength and low water absorption ceramsites.Pk kept a good linear relationship with porosity and strength of ceramsite particles.

A novel approach to with a preparing ultra-lightweight ceramsite large amount of fly ash

The disposal of fly ash has become a serious problem in China due to its rapid increase in volume in recent years.The most common method of fly ash disposal is solidification-stabilization-landfill,and the most common reuse is low-value-added building materials.A novel processing method for preparing ultra-lightweight ceramsite with fly ash was developed.The results show that the optimal parameters for preparation of ultra-lightweight ceramsite are as follows:mass ratio of fly ash:kaolin:diatomite=80:15:5,preheating temperature of 800℃,preheating time of 5 min,sintering temperatiire of 1220℃,and sintering time of 10 min.The expansion agent is perlite,at 10 wt.% addition.Finally,a ceramsite with bulk density of 340 kg/m3,particle density of 0.68 g/cm3,and cylinder compressive strength of 1.02 MPa was obtained.Because of its low density and high porosity,ultra-lightweight ceramsite has excellent thermal insulation performance,and its strength is generally low,so it is usually used in the production of thermal insulation concrete and its products.The formation of a liquid-phase component on the surface,and generation of a gas phase inside ceramsite during the sintering process,make it possible to control the production of the suitable liquid phase and gas in this system,resulting in an optimization of the expansion behavior and microstructure of ceramsite.These characteristics show the feasibility of industrial applications of fly ash for the production of ultralightweight ceramsite,which could not only produce economic benefits,but also conserve land resources and protect the environment.