Extraction of copper and zinc from naturally contaminated copper mine soils: Chemical fractionation analysis and risk assessment

The spatial and temporal distribution of tunnel failure is very complex due to geologic heterogeneity and variability in both mining processes and tunnel arrangement in deep metal mines. In this paper, the quantitative risk assessment for deep tunnel failure was performed using a normal cloud model at the Ashele copper mine, China. This was completed by considering the evaluation indexes of geological condition, mining process, and microseismic data. A weighted distribution of evaluation indexes was determined by implementation of an entropy weight method to reveal the primary parameters controlling tunnel failure. Additionally, the damage levels of the tunnel were quantitatively assigned by computing the degree of membership that different damage levels had, based on the expectation normalization method. The methods of maximum membership principle, comprehensive evaluation value, and fuzzy entropy were considered to determine the tunnel damage levels and risk of occurrence. The application of this method at the Ashele copper mine demonstrates that it meets the requirement of risk assessment for deep tunnel failure and can provide a basis for large-scale regional tunnel failure control in deep metal mines.

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Fouling Tendency of Ash Resulting From Burning Mixtures of Biofuels

18th International Conference on Fluidized Bed Combustion ◽

10.1115/fbc2005-78019 ◽

2005 ◽

Cited By ~ 1

Author(s):

Mischa Theis ◽

Bengt-Johan Skrifvars ◽

Mikko Hupa ◽

Honghi Tran

Keyword(s):

Flow Reactor ◽

Chemical Interaction ◽

Substrate Surface ◽

Agricultural Waste ◽

Pulp Mill ◽

Considerable Change ◽

Chemical Fractionation ◽

Feed Composition ◽

Linear Pattern ◽

Fractionation Analysis

Specified mixtures of peat with bark and peat with straw were burned in a lab-scale entrained flow reactor that simulates conditions in the superheater region of a biomass-fired boiler. Deposits were collected on an air-cooled probe that was inserted into the reactor at the outlet. For both mixtures, the deposition behaviour followed a non-linear pattern, which suggests that physico-chemical interaction between the ashes of the different fuels has taken place. The results indicate that it is possible to burn up to 30 wt-% bark (renewable biofuel and pulp mill waste) and up to 70 wt-% straw (renewable biofuel and agricultural waste) in mixtures with peat without encountering increased deposition rates in the reactor. The deposit composition was compared to the fuel ash composition using chemical fractionation analysis and SEM/EDX. While the composition of deposits obtained from pure fuels resembles the feed composition, a considerable change is observed in deposits obtained from mixtures. K and S compounds are attached to Si spheres and the substrate surface. The deposition rate is significantly lowered when removing K, S, Cl and Na in bark prior to burning by washing and mechanical/thermal dewatering.

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