从工艺矿物学角度分析稀土尾矿作为NH_(3)-SCR催化剂的可行性

Feasibility of Rare Earth Tailings as NH_(3)-SCR Catalyst from Perspective of Process Mineralogy

选择性催化还原法(SCR)是工业上广泛应用的控制NO_(x)排放比较成熟的技术,矿物催化剂逐渐成为脱硝领域的研究热点,稀土金属元素和过渡金属元素具有联合协同作用,白云鄂博稀土尾矿堆积量巨大且共伴生元素丰富,二次资源的利用“迫在眉睫”。本文从稀土尾矿的工艺矿物学角度深入分析其作为脱硝催化剂的可行性,稀土尾矿含有赤铁矿/磁铁矿、黄铁矿、氟碳铈矿、钛矿物和锰矿物等矿物,其中Fe,Ce,Mn均可作为催化剂的活性元素。矿物间的连生有利于活元素的联合作用,磁铁矿和氟碳铈矿与碳酸盐矿物、硅酸盐矿物、萤石及其他矿物连生有利于活性元素分散。含有Fe和Ce元素的矿物小颗粒(18.75~89.19μm)占比较高。酸活化后稀土尾矿脱硝活性最高为83%,N_(2)选择性在88%以上。稀土尾矿经过机械力或酸等活方式活化后,有希望成为脱硝催化剂。

Selective catalytic reduction(SCR)technology,is widely used in industry to reduce NO_(x) emission.Mineral catalyst has gradually become the focus in the field of denitrification.Rare earth metal and transition metal show synergistic effect in SCR technology.Bayan Obo rare earth tailings,with huge accumulation and rich associated elements,should be utilized as secondary resources.In the paper,the feasibility of rare earth tailings used as denitrification catalyst is analyzed from the perspective of process mineralogy.Rare earth tailings contain hematite/magnetite,pyrite,bastnaesite,titanium and manganese minerals,among which Fe,Ce and Mn can be used as active elements of catalysts.The combination of magnetite and bastnaesite with carbonate minerals,silicate minerals,fluorite and other minerals is conducive to the dispersion of active elements.The proportion of small particles(18.75~89.19μm)of minerals containing Fe and Ce is moreth another size particles.After acid activation,the denitrification activity and N_(2)selectivity of rare earth tailings are higher than 83%and 88%,re⁃spectively.Rare earth tailings,treated with ball milling or acid,could be used as NH_(3)-SCR catalyst.