The Impact of Industrial Solid Wastes on Heavy Metal Solidification/stabilizayion of Magnesium Potassium Phosphate

Article history: Received: 21.01.2015. Received in revised form: 21.07.2015. Accepted:23.07.2015. In order to examine the impact of admixture amount on the heavy metal solidification/stabilization effect of Magnesium Potassium Phosphate cement (MKPC), industrial dusts, iron ore tailings and slag were added into Magnesium Potassium Phosphate containing 5g/kg of heavy metals at the ratios of 0, 5%, 10%, 20% and 30% respectively. Mixtures were firstly conserved for 1d, 7d, 15d and 28d respectively at conditions of 20±1°C and humidity ≥95%. Then, Toxicity Characteristic Leaching Procedure (TCLP) method was adopted to measure the leaching concentrations of solidified heavy metal ions, and to examine the impact of admixtures on MKPC solidified heavy metals. The results showed that admixtures at the ratio of 30% would reduce the strength of solidified heavy metals by approximately 70%, while extension of conservation time would improve the strength so as to meet the requirements of landfill processing. After conserving the samples containing 30% of admixtures for 28d, the ion concentration of Zn, Cu and Pb detected by TCLP method were lower than the TCLP standard regulated by the US Environmental Protection Agency (EPA). It shows that MKPC can be mixed with an appropriate amount of admixtures and conserved for a certain period of time before heavy metal solidification/stabilization.