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This paper highlights significant findings from focusing on developing a sustainable lightweight aggregate (LWA) concrete, which replaced Portland cement partially with municipal solid waste incineration fly ash (MSWI FA) and all of the conventional coarse aggregate with LWA sintered by MSWI FA, shale, and sludge. A series of four experiments, differing in dosage of MSWI FA and aggregate, were conducted for this project. The results of this study generally showed that appropriate amount of MSWI FA substitution for cement has no significantly lowered the compressive strengths of LWA concrete, while it can lower the oven-dry density and the thermal conductivity. The optimum performance of LWA concrete (after 28 days of curing) is as follows: (1) slump flow of 700 mm, (2) compressive strength of 30.14 MPa, (3) dry apparent density of 1.66 g/cm3, (4) thermal conductivity of 0.73 W (m K)−1; the mixture ratio of LWA, fly ash, cement, and fine sand is 3.0: 0.1: 0.9: 2.0 based on dry weight. Meanwhile, th...

The farmland surface soils effected by uranium tailing were sampled, and the contents of 238U, 232Th, 226Ra, Cu, As, Cd, Pb and Zn in the samples were analyzed. The Index of Geoaccumulation and the Potential Ecological Risk Index were employed to evaluate the pollution degree of heavy metals in the soil. The results showed the content of Cd, As, Pb, 238U and 226Ra in the farmland soil exceeded background value. The Index of Geoaccumulation indicated the main polluted factor influencing farmland soil was 226Ra (highly contaminated), the next was 238U and Cd (uncontaminated-moderate contaminated). The potential ecological risk intensity caused by Cu, Zn, Pb and As are all low, and by Cd was moderate contaminated. The potential ecological risk level of integrated heavy metals was low in the study area, and Cd was the main factor. However, the potential ecological risk assessment did not take into account the effects of radionuclide 238U, 232Th, 226Ra, so that and the results of the potential ecological risk were less than that of actual. The metals input in farmland soil are possibly caused by uranium tailings loss and their seepage.

The effect of surfactant on improving the leaching rate of uranium was studied under both batch and column experiments. Batch experiments show that surfactant DMSS can improve the leaching rate and the the surface tension is decreased about 55.29%. 70 mg/l DMSS has the highest leaching rate of uranium , which close to the micellar concentration of DMSS. In the column study, with the addition of DMSS, the leaching rate of uranium is improved 8.3%. Thus the surfactant DMSS can accelerate leaching of uranium.

The farmland soil and creek sediments in different depth in the mining area were sampled, and their content of 238U,226Ra and 232Th were determined by gamma spectrometric method to assess the impact of the soil environment by single index method. The result shows 232Th was not influenced on soil in survey area. 226Ra influenced more seriously than 238U on farmland soil, meanwhile, the farmland soil at downstream of tailings dam was contaminated seriously by radionuclides than at other places. For creak sediments ,adit water resulted in more serious pollution by 238U than 226Ra, however, tailings erosion resulted in more serious pollution by 226Ra than 238U.

The presence of the colloid will affect uranium heap leaching. The objective of this study was the examination of the ability of colloid retardation to uranium by irons hydroxide colloids simulated heap leaching process. Batch studies have been carried by observing the effects of pH, contact time, uranium concentration. Iron hydroxide colloids can exist stably at pH 1.5-3.0. The size of the colloid samples is between 20 nm and 1000 nm. The sorption equilibrium was attained at 24 h. The load uranium capacity on iron hydroxide colloids are between 2.43×10-3 and 3.84×10-3 mmol/mol. The colloid morphology of before and after loaded uranium were identified using S-4800 scanning electron microscopy (SEM/EDS). The load uranium capacity on iron hydroxide colloids is least at pH=2, it implies that the appropriate pH of uranium heap leach is 2.0 on the point of retardation of colloid to uranium migration.