Study On The Preparation Of Copper Slag-based Iron-based Phosphate Chemical Bonding Material And Its Solidification Of Heavy Metals

Copper slag?CS?is the waste residue generated from the smelting process of copper by fire method.The large accumulation of copper slag not only occupies a large amount of land resources,but also the toxic substances contained in the copper slag will pollute the environment.Heavy metal pollution is an important issue in China.At the same time,in response to relevant national environmental protection policies,the method of heavy metal pollution control has changed to an environmentally friendly development.Among them,phosphate chemical bonding materials solidifying heavy metals is one of the more effective and environmentally friendly methods.In this paper,copper slag rich in iron oxide and ammonium dihydrogen phosphate were used to carry out chemical reaction at room temperature to prepare copper slag-based iron phosphate phosphates?CBIPCs?and used as matrix.The material solidifies heavy metals Pb,Cd,Cr.The following conclusions were obtained:?1?Preparation of copper slag-based phosphate chemical bonding materials?CBIPCs?shows that when m?CS?/m?P?=3/1,W/C=0.120,and the amount of borax is2%,the solidified form is naturally cured.The compressive strength of 28 d can reach 51.6 MPa.The XRD and SEM characterization of CBIPCs showed that the gelled phase formed by CBIPCs was mainly FeH₂P₃O₁₀·H₂O,FePO₄,Fe?H₂PO₄?₃.The unreacted raw materials existed as fillers in the interior of the material and closely related to gelation,Bonding forms a dense whole.?2?The effect of m?CS?/m?P?and borax content on the heavy metals Pb,Cd and Cr of CBIPCs shows that when m?CS?/m?P?=3/1,the amount of borax is 2%When the material has a good curing effect on heavy metal Pb;when m?CS?/m?P?=2/1 and the amount of borax is 4%,the solidification effect of the material on heavy metal Cd is better,when m?CS?/m?P?=2/1,when the amount of borax is 5%,the material has a good curing effect on heavy metal Cr.?3?The influence of the addition of heavy metals Pb,Cd and Cr on CBIPCs indicates that when the content of lead nitrate is 12%,the compressive strength of the solidified form is 24.5 MPa,and the concentration of heavy metal Pb is 0.086mg·L^-1.When the amount of cadmium nitrate is 6%,the compressive strength of the cured form is only 7.3 MPa at 28 d,the leaching concentration of heavy metal Cd is3.234 mg·L^-1,and when the amount of chromium nitrate is 8%,the solidified form is28 d.The compressive strength is only 16.3 MPa,and the heavy metal Cr has a toxic leaching concentration of 0.896 mg·L^-1.?4?XRD characterization of the cured form shows that metals such as PbHPO₄,Pb₃?PO₄?₂,Cd?H₂PO₄?₂,Cd₃P₅O₁₈·16H₂O,CrPO₄,Cr?PO₃?₃,PbHPO₄,Pb₃?PO₄?₂ are formed in the solidified form.Phosphate precipitation,the quality of the resulting gelled phase is relatively reduced.The SEM micromorphology of the solidified form shows that the addition of heavy metal Pb has little effect on the internal structure of CBIPCs,and the structure of the solidified form is still relatively dense.The addition of heavy metals Cd and Cr makes the structure of CBIPCs loose.