Leaching behavior of copper tailings solidified/stabilized using hydantoin epoxy resin and red clay.

Tailings produced by mining engineering and metal smelting industries have become a major challenge to the ecological environment and human health. Environmental compatibility, mechanical stability, and economic feasibility have restricted the treatment and reuse of tailings. A novel solidification/stabilization technology using hydantoin epoxy resin (HER) and red clay for copper tailing treatment was developed, and the leaching behaviors of solidified/stabilized copper tailings were investigated in this paper. The leaching characteristics were analyzed by toxicity characteristic leaching procedure (TCLP) leaching tests. Besides, the influence of red clay content and acid rain on the permeability characteristics and leaching characteristics were investigated based on flexible-wall column tests and microstructure tests. The results showed that the copper tailings solidification/stabilization technology with HER and red clay had excellent performances in toxicity stabilization. The leaching concentration of Cu in TCLP tests and flexible wall column tests remained within the limit specified by the Chinese national standard, and the concentration of Cu decreased significantly with the increase of the red clay content. Moreover, acid rain leaching changed the mineral composition and microstructure of solidified tailings, and the porosity of the samples increased with the dissolution of soluble minerals. Additionally, the hydraulic conductivities decreased slightly with the increase in the pH value of acid rain, and the solidified sample with 5% red clay had the lowest hydraulic conductivity.

A practical adaptive moving-mesh algorithm for solving unconfined seepage problem with Galerkin finite element method.

One of the great challenges of unconfined seepage through a dam lies in the accurate determination of free surface that depends on the complexity of the seepage model, especially if the model is characterized with complex geometry and sharp variations in permeability distribution. This study presents a practical methodology that combines the adaptive moving-mesh algorithm and the Galerkin finite element method (FEM) to solve an unconfined seepage problem with high efficiency and precision. The methodology employs a set of improvement terms, such as remainder factor, step-size parameter and termination condition, all of which guarantee that the simulation and the refinement fitting can be implemented efficiently until the free surface converges within a given allowable error. In particular, a specialized discussion is presented for the significant relation between the location of the exit point and the corresponding grid fineness. To validate the practicability of the proposed method, a series of examples are performed. Comparing the result with those of other numerical approaches, we conclude that even though the unconfined seepage model may be complicated with arbitrary complex geometry and sharp variations in permeability distribution, the proposed algorithm provides a great improvement in efficiency and accuracy in free-surface searching.

On-line surface plasmon resonance-high performance liquid chromatography-tandem mass spectrometry for analysis of human serum albumin binders from Radix Astragali.

Development of sensitive and effective methods that meet the demand of high-throughput, high-fidelity screening of bioactive components from natural products are important to drug discovery. We describe here a novel surface plasmon resonance-high performance liquid chromatography-tandem mass spectrometry (SPR-HPLC-MS/MS) system for rapid, continuous and effective screening and identification of human serum albumin (HSA) binders from Radix Astragali. The HPLC six-port valve was used as interface through which the dissociated HSA binders from SPR was collected and injected automatically to HPLC-MS/MS for analysis. Eleven isofalvonoids and nine astragalosides have been screened and identified as the main HSA binders in ethyl acetate extract of Radix Astragali. Compared with reverse ultrafiltration assay, the developed configuration is more cost effective and reproductive because of the higher reusability and stability of immobilized HSA on SPR chip. Furthermore, the assay minimized the matrix interference in MS because of the elimination of non-binding components before HPLC separation. It is concluded that this novel technology offers new perspectives for screening and identification of active components from complex mixtures.