Experimental Study Of Resource Utilization Of Flotation Algae Residue As Pavement Brick Materials

With people’s living standards improving, the pollution of water is more and moreserious. The eutrophication of lakes, rivers and reservoirs are more serious. The use offlotation processing in water treating produces a large amount of dross which called theflotation algae residue. The algae residual contains high concentrations and large amounts ofharmful substances such as organic matter, pathogens, parasites and heavy metals. Primarymethods to deal with the flotation algae residue at this stage are landfill, incineration, etc.,which cannot effectively deal with the flotation algae slag. It is easy to cause secondarypollution and pose a threat to water bodies. Experimental Study of the flotation algae residuegenerally limited in the compost, biogas, etc, which does not make the flotation algae residuetruly harmless. Using flotation algae slag as raw materials to produce pavement brick as thefinal disposal of the slag flotation algae, which turn waste into treasure, enhance the value ofthe flotation of algae residue and reduce the burden on the environment, and also broughtsome economic benefits.This paper started from analysis flotation algae residue characteristics and the physicaland chemical properties and microstructure of the Yellow River silt, coal gangue. Combinedwith the fired brick technology, researched and discussed on using of flotation algae residue,the Yellow River silt, coal gangue as the main raw material to make the flotation algae residuepavement bricks modified.Particular contents in this paper were summarized as follows:(1) The physical and chemical properties of raw materials were analyzed. Focus on theflotation algae residue analysis, scanning electron microscopy figure shows the surface of theflotation algae residue containing the multi-fiber, organic matter and granular inorganic matter,and it had porous structure. The chemical composition analysis flotation algae residue showsit contains a large organic fraction, and less plastic. The chemical composition analysis of theYellow River silt shows high silica content, good adhesion, which can improve the plasticityof the raw materials. The chemical analysis of coal gangue shows high content of aluminumoxide, which can improve the strength of the pavers. The concentration of pollutants inflotation algae residue is in line with the standards of urban sewage treatment plant sludgetreatment used in making argillaceous brick (CJ/T289-2008).(2) Selection of production process to make pavement brick. Analysis of raw materialsreach a decision that the pavement brick production process contains mixing, aging, compression molding, drying, roasting and cooling. Mixing combined with dry mixing andwet mixing, the aging time is24h and the temperature was controlled at above10℃,compression molding selected half dry pressing and drying time is12h, roasting controlledwith roasting curve.(3) Experimental study of the flotation algae residue pavement brick. The ranges of theflotation algae residue content, forming pressure, the calcinations temperature were discussedpreliminary. The best conditions of road brick combination was determined by orthogonalexperiment, that is a15%weight content of flotation algae residue under the moldingpressure of35MPa and then roasted under calcination temperature1000℃with the holdingtime of1h, the Yellow River silt and coal gangue ratio3:1.The compressive strength ofpavement brick, formed under above conditions, can be achieved29.8MPa and waterabsorption of15.6%.(4) The effect of flotation algae residue content, forming pressure, calcination temperatureon the performance of flotation algae residue pavement bricks was analyzed. The content pfflotation algae have a decisive impact on performance of flotation algae residue pavementbricks, and in present study the flotation algal residue content cannot exceed20%. The greaterforming pressure, the better performance of flotation algae residue pavement bricks, but thepressure must lower than35MPa. The higher calcination temperature, the better performanceof flotation algae residue pavement bricks have, the strength of blocks was almost optimalwhen calcination temperature reached1100℃.(5) Modification of pavement brick. The causes of pavement brick cracks were analyzed,and the cracks are divided into general cracks, layered cracks and annular cracks. The bestconditions under which the performance of pavement brick can be modified best weredetermined by orthogonal experiment, namely, at the ratio of feldspar powder, fine aggregatemoisture content and the others is30:10:12:48. And the compressive strength of flotationalgae residue pavement bricks was close to22MPa when the percentage of flotation algaeresidue reached to20%. On account of solving lower content of flotation algae residue, theflotation algae residue combustion ash was used to make pavement brick. When the content ofalgae residue ash was up to40%, the compressive strength of pavement brick reached to21MPa.