以TFe品位为30.71%的河南某焙烧氰化尾渣为原料,采用湿式强磁预选-磁化焙烧-磁选联合工艺制备铁精粉.结果表明,当强磁预选的磁场强度为1511.54 k A/m时,得到TFe品位44.96%、回收率78.27%的粗精矿;以该粗精矿为磁化焙烧原料,配10wt%焦粉,...以TFe品位为30.71%的河南某焙烧氰化尾渣为原料,采用湿式强磁预选-磁化焙烧-磁选联合工艺制备铁精粉.结果表明,当强磁预选的磁场强度为1511.54 k A/m时,得到TFe品位44.96%、回收率78.27%的粗精矿;以该粗精矿为磁化焙烧原料,配10wt%焦粉,于750℃下磁化焙烧45 min,焙烧样经二段磨矿、二段弱磁选,当二段磨矿细度小于0.028 mm占63.9%时,可得TFe品位61.71%、回收率68.66%的铁精粉;产率为16.79%的弱磁选尾矿不含氰化物,转化为一般工业固体废物.焙烧温度低于700℃时,部分赤铁矿未还原;焙烧温度超过800℃时,生成的磁铁矿转化成镁铁矿、铁橄榄石和方铁矿,磁铁矿含量降低,导致铁损失;焙烧温度为750℃时,磁铁矿含量最高.展开更多
To investigate the physical and chemical properties of the steelmaking dust, wet sieve separation, XRD, SEM, EDS, and traditional chemical analysis were carded out to obtain the particle size distribution, mineralogy,...To investigate the physical and chemical properties of the steelmaking dust, wet sieve separation, XRD, SEM, EDS, and traditional chemical analysis were carded out to obtain the particle size distribution, mineralogy, morphology, and the chemical composition of the dust. The dust with a total Fe content of 64.08wt% has coarse metallic iron, magnetite and hematite grains, while free clay minerals with a size of 〈38 μm are mainly iosidefite, calcium silicate, and calcite, which are conglomerated to each other. By following the procedures of wet magnetic separation, acid leaching, and oxidization calcination, magnetic materials were recycled and further prepared as iron oxide red with a productivity of 0.54 ton per unit ton of the dust. Middle iron concentrate with an Fe content of 65.92wt% can be reused as feeding material in the ironmaking industry. Additionally, washed water from acid leaching with an Fe^3＋ ion content of less than 5 g·L^-1 was recovered as feeding water in the wet magnetic separation procedure. 2008 University of Science and Technology Beijing. All fights reserved.展开更多
The development of low-carbon cementitious materials involves the selection of the appropriate raw materials and the transformation of the hydration mechanism.In this study,low-carbon and low-cost cementitious materia...The development of low-carbon cementitious materials involves the selection of the appropriate raw materials and the transformation of the hydration mechanism.In this study,low-carbon and low-cost cementitious materials were prepared using municipal solid waste incineration fly ash(MSWI FA),blast furnace slag(BFS),and desulfurization gypsum(DFG)as raw materials to reduce clinker usage.Results showed that the compressive strength of K5(mass ratio of BFS:DFG:MSWI FA=7:1:2)after 360 d of curing was 41.49 MPa,with a low leaching concentration of heavy metal residues that meet groundwater Class II standards,a dioxin content of only 25 ngTEG/kg,and a stable pH value ranging between 11 and 11.5.Microscopic analysis revealed a continuous decrease in the Ca/Si atomic ratios of K4(mass ratio of BFS:DFG:MSWI FA:P-I 42.5=42:10:20:28)and K5,i.e.,1.18-1.54 and 1.04-1.23,respectively,with the increase in the hydration age.The highest Al/Si atomic ratio of K5,i.e.,0.26-0.31,was observed with the strongest conversion trend of calcium-silicate-hydrate gel into calcium-aluminum-silicate-hydrate gel,and the network structure of sodium-(calcium)-aluminum-silicate-hydrate gel zeolite-like phase was generated.The water-to-binder(WTB)mass ratio of 0.35 was determined to be more suitable for the K4 and K5 systems and resulted in a 56.83%and 90.82%reduction in half-life ta compared with the WTB ratio of o.5,respectively.Notably,the value of the reaction velocity constant K in the induction period was 10 times that of K1,and the autocatalytic reaction controlled the value of N to<1.The X-ray absorption near-edge structure indicated that Zn solidification produced Zn_(2)SiO_(4) with a small solubility product.The production of 1 t of K5 emitted only 10.83 kg/t of CO_(2),which was 40 times less than that of K1.Overall,K5 provides the highest economic benefit at 40.08 USD/t,and the clinker-free cementitious system with multisolid waste synergy has significant advantages in terms of solidifying harmful substances,reducing carbon emissions,and lowering costs.展开更多
文摘以TFe品位为30.71%的河南某焙烧氰化尾渣为原料,采用湿式强磁预选-磁化焙烧-磁选联合工艺制备铁精粉.结果表明,当强磁预选的磁场强度为1511.54 k A/m时,得到TFe品位44.96%、回收率78.27%的粗精矿;以该粗精矿为磁化焙烧原料,配10wt%焦粉,于750℃下磁化焙烧45 min,焙烧样经二段磨矿、二段弱磁选,当二段磨矿细度小于0.028 mm占63.9%时,可得TFe品位61.71%、回收率68.66%的铁精粉;产率为16.79%的弱磁选尾矿不含氰化物,转化为一般工业固体废物.焙烧温度低于700℃时,部分赤铁矿未还原;焙烧温度超过800℃时,生成的磁铁矿转化成镁铁矿、铁橄榄石和方铁矿,磁铁矿含量降低,导致铁损失;焙烧温度为750℃时,磁铁矿含量最高.
文摘To investigate the physical and chemical properties of the steelmaking dust, wet sieve separation, XRD, SEM, EDS, and traditional chemical analysis were carded out to obtain the particle size distribution, mineralogy, morphology, and the chemical composition of the dust. The dust with a total Fe content of 64.08wt% has coarse metallic iron, magnetite and hematite grains, while free clay minerals with a size of 〈38 μm are mainly iosidefite, calcium silicate, and calcite, which are conglomerated to each other. By following the procedures of wet magnetic separation, acid leaching, and oxidization calcination, magnetic materials were recycled and further prepared as iron oxide red with a productivity of 0.54 ton per unit ton of the dust. Middle iron concentrate with an Fe content of 65.92wt% can be reused as feeding material in the ironmaking industry. Additionally, washed water from acid leaching with an Fe^3＋ ion content of less than 5 g·L^-1 was recovered as feeding water in the wet magnetic separation procedure. 2008 University of Science and Technology Beijing. All fights reserved.
基金supported by the National Key Research and Development Program of China (Nos.2019YFC1803500 and 2020YFC1910000)Fundamental Research Funds for the Central Universities (Nos.FRF-TP-20-003A1 and FRF-IDRY-20-014).
文摘The development of low-carbon cementitious materials involves the selection of the appropriate raw materials and the transformation of the hydration mechanism.In this study,low-carbon and low-cost cementitious materials were prepared using municipal solid waste incineration fly ash(MSWI FA),blast furnace slag(BFS),and desulfurization gypsum(DFG)as raw materials to reduce clinker usage.Results showed that the compressive strength of K5(mass ratio of BFS:DFG:MSWI FA=7:1:2)after 360 d of curing was 41.49 MPa,with a low leaching concentration of heavy metal residues that meet groundwater Class II standards,a dioxin content of only 25 ngTEG/kg,and a stable pH value ranging between 11 and 11.5.Microscopic analysis revealed a continuous decrease in the Ca/Si atomic ratios of K4(mass ratio of BFS:DFG:MSWI FA:P-I 42.5=42:10:20:28)and K5,i.e.,1.18-1.54 and 1.04-1.23,respectively,with the increase in the hydration age.The highest Al/Si atomic ratio of K5,i.e.,0.26-0.31,was observed with the strongest conversion trend of calcium-silicate-hydrate gel into calcium-aluminum-silicate-hydrate gel,and the network structure of sodium-(calcium)-aluminum-silicate-hydrate gel zeolite-like phase was generated.The water-to-binder(WTB)mass ratio of 0.35 was determined to be more suitable for the K4 and K5 systems and resulted in a 56.83%and 90.82%reduction in half-life ta compared with the WTB ratio of o.5,respectively.Notably,the value of the reaction velocity constant K in the induction period was 10 times that of K1,and the autocatalytic reaction controlled the value of N to<1.The X-ray absorption near-edge structure indicated that Zn solidification produced Zn_(2)SiO_(4) with a small solubility product.The production of 1 t of K5 emitted only 10.83 kg/t of CO_(2),which was 40 times less than that of K1.Overall,K5 provides the highest economic benefit at 40.08 USD/t,and the clinker-free cementitious system with multisolid waste synergy has significant advantages in terms of solidifying harmful substances,reducing carbon emissions,and lowering costs.
