Study On Preparation Of Vegetation Concrete By Phosphate Tailings

Developing phosphorus resources brings a lot of phosphate tailings which has thepotential threats to the ecological environment. Phosphate tailings has certain gellingafter a certain amount of treatment and it contains phosphorus required for the growth ofvegetation. In this study, phosphate tailings as the main raw material, silica fume,phosphorus slag, gypsum and other solid waste as a secondary raw material to preparevegetation concrete. First, we conducted modified treatment on phosphate tailings suchas calcination, steam curing. Then using calcined phosphate tailings and steam curingmodified phosphate tailings as the main ingredient to prepare vegetation substrate,vegetation concrete and mine reclamation with nutrition impermeable layer, and testswere carried out planting vegetation.Phosphate tailings ore are mainly components of dolomite which was decomposedinto CaO and MgO under calcination at900℃for1.5h and the release of availablephosphorus content of the sample increased which can be used as nutrients for vegetationgrowth. Hydrated calcium silicate could be formed when calcined phosphate tailings andsilica fume were mixed with the mass ratio of8:1under the atmosphere of175℃,0.88MPa for8h. Then steam curing modified phosphate tailings was gained.Calcined phosphate tailings and tailings steam curing modified phosphorus wererespectively formulated into vegetation substrate with phosphorus slag, gypsum, perlite,soil and other compositions. The content was increased from20%to60%. In waterequivalent rainfall intensity1320mm/h, samples standard curing for7d were studied foranti-erosion experiments. We found that the anti-erosion time increased form50min to145min with increasing content of calcined phosphate tailings.and the samples of addingsteam curing modified phosphate tailings dropped from3min to0.5min with increasingcontent. The alkalinity of vegetation substrate with calcined phosphate tailings decreasedwith increasing time. While the alkalinity of vegetation substrate with steam curingmodified phosphate tailings was essentially unchanged. When the vegetation substratewas used for planting vegetation, germination rate of tall fescue was between60%to 75%and growth height was between8~11cm. Adding calcined phosphate tailings intovegetative substrate is more suitable for growth of tall fescue.The porosity of porous aggregate concrete prepared by particle size of16.0~19.0mm or19.0~26.5mm was about28%and the compressive strength was between3~5MPa. The compressive strength of the samples also declined but the magnitude wasnot large when30%or50%of the amount of cement was replaced by slag and zeolite.Composition with vegetation substrate and porous concrete to prepare vegetationconcrete which was also suitable for the growth of tall fescue.Making use of calcined phosphate tailings, phosphorus slag, gypsum, perlite andzeolite to prepare impermeable layers applied to mine reclamation. Tall fescue could rootinto impermeable layers and the growth was good.In this paper, phosphate tailings as the main raw material, silica fume, phosphorusslag, gypsum and concrete solid waste as a secondary raw material to prepare vegetation,substrate applied to protect slope and mine reclamation which has a certain value forenvironmental governance and the development of recycling economy.