Abstract:

MPC（magnesium phosphate cement） was used to solidificate enrichment heavy metal Cu and Ni. The compressive strength of MPC added Cu（NO₃）₂ and Ni（NO₃）₂,the leaching concentration of Cu ²⁺ and Ni ²⁺,and the composition of hydration products were determined.The surface microstructure was observed.The chemical states and occurrence of Cu ²⁺ and Ni ²⁺ in cement were analyzed.Results showed that when content of Cu ²⁺ increased from 0 to 3%（mass fraction）,the compressive strength of cement increased first and then decreased with the increase of Cu ²⁺ content;the 7 d compressive strength reached the maximum value of 46.05 MPa,when the dosage of Cu ²⁺ was 1%.When the content of Ni ²⁺ increased from 0 to 3%（mass fraction）,the the compressive strength of cement decreased gradually with the content of Ni ²⁺ increased,and the 7d compressive strength decreased about 29%.The compactness of cement was directly related to the curing effect of Cu ²⁺ and Ni ²⁺.When the dosage of Cu ²⁺and Ni ²⁺ was both 3%,the maximum leaching concentration of Cu ²⁺ was 1.95 mg/L,and Ni ²⁺ was 0.97 mg/L,both far below the relevant national standards. Cu mainly exists in the form of Mg_0.95Cu0_.05O of +2,and Ni exists in the form of Ni（OH）₂ amorphous precipitation of +2.

Key words: heavy metal, MPC, mechanical property, solidification