Abstract

Paste-like tailings slurry (PTLS) is always simplified as a Bingham plastic fluid, leading to excessive computational errors in the calculation of the hydraulic gradient. In the case of paste-like tailings in long-distance pipeline transportation, to explore a high-precision and reliable hydraulic gradient formula, the rheological behavior of paste-like tailings slurry was analyzed, a time-varying hydraulic gradient model was constructed, and a series of laboratory shear tests were conducted. The results indicate that the PTLS shows noticeable shear-thinning characteristics in constant shear tests; the calculated hydraulic gradient declined by about 56%, from 4.44 MPa·km"jats:sup"−1"/jats:sup" to 1.95 MPa·km"jats:sup"−1"/jats:sup" within 253 s, and remained constant for the next four hours during the pipeline transportation. Comparing with the balance hydraulic gradient obtained in a semi-industrial loop test, the computational errors of those calculated by using the time-varying hydraulic gradient model, Jinchuan formula, and Shanxi formula are 15%, 78%, and 130%, respectively. Therefore, our model is a feasible and high-precision solution for the calculation of the hydraulic gradient of paste-like tailings in long-distance pipeline transportation. Document type: Article

Abstract

Taking the superfine tailings slurry (STS), fine tailings slurry (FTS), and unclassified tailings slurry (UTS) of a gold mine as examples, a series of laboratory shear tests were conducted to investigate the effect of anionic polyacrylamide (APAM) on the structural stability of the thickened tailings slurry in pipeline transportation. Experimental results showed that the FTS and UTS had shear-thinning and shear-thickening characteristics in the constant shear tests, respectively. After addition of APAM, when the shear rate was 30 s"jats:sup"−1"/jats:sup", standard deviations of apparent viscosity of FTS, UTS, and STS were 66.67%, 61.40%, and 35.33% lower, respectively. APAM enhances the strength of the flocculent structures, inhibits the hindered settling of the coarse-particle tailings, improves the structure stability of the solid particles on the structural plane, and assists pipeline transportation of the thickened tailings slurry. Document type: Article

Abstract

"jats:p"The research material used in the study was the martensitic creep-resistant steel P92 used for the manufacture of pipes being part of power generation units subject to heavy load. The research problem focused on two issues. The first one was to analyze how the plastic deformation cumulated in the material in low-cycle fatigue conditions affects the characteristics of the material in creep conditions in a temperature of 600ºC. The other one was concerned with analysis of a reverse situation, i.e. how the initial plastic deformation of the material in creep conditions changes the mechanical characteristics of the steel under low-cycle fatigue conditions in a temperature of 600ºC. Document type: Article

Abstract

Case study of corrosion failure of urban water supply system caused by environmental factors was presented. Nowadays corrosion monitoring of water distribution systems is an object of major concern. There is possibility of application broad range of techniques like gravimetric and electrochemical. Both kinds of techniques can be applied in laboratory and field conditions. In many cases researches limit the case analysis to measurements in laboratory conditions. Presented work contain critical analysis of results obtained in laboratory and field conditions based on corrosion monitoring of three pipelines systems failure in Krakow. Document type: Article