In this paper, gold leaching of a refractory sulfide concentrate by chloride–hypochlorite solution was investigated and effects of stirring speed, temperature and particle size on the leaching rate were reported. Experimental data for leaching rate of gold were analyzed with the shrinking–core model. Results were consistent with chemical reaction control mechanism in the first 1 h of leachin...

A basic investigation into whether a geopolymer can be utilized as part of an artificial barrier during radioactive waste disposal was conducted in this study. Geopolymers are comprised primarily alumina and silica, they exhibit negligible leaching owing to the absence calcium. Studies on geopolymers limited compared those other cementitious materials because physical characteristics vary with ...

Dimethyl carbonate (DMC) can be applied as a greener alternative to more hazardous materials, e.g. phosgene or dimethyl sulfate. Herein, one-pot synthesis of DMC from propylene oxide, methanol and CO2 using alkali halide catalysts under mild conditions was studied. Addition Zn powder the K2CO3-NaBr-ZnO catalyst system seen increase selectivity 19.8% (TOF = 39.0 h?1) 40.2% 78.1 at 20 bar 160 °C ...

Three alkali swelling methods were used to treat two kinds of kraft pulp fibers. The morphological and chemical properties of the treated fibers were elucidated in terms of alkali concentration, with the aim of developing bulky paper and conserving wood resources. The effects of beating before and after alkali swelling were examined. The water retention value of fibers increased when higher con...

Aggregates containing certain constituents can react with alkali hydroxides in concrete. The reactivity is potentially harmful only when it produces significant expansion (Mather 1975). This alkali-aggregate reactivity (AAR) has two forms—alkali-silica reaction (ASR) and alkali-carbonate reaction (ACR, sometimes called alkali-carbonate rock reaction, or ACRR). ASR is more often a concern than A...

This study investigated the optimum conditions for the leaching of manganese-rich iron ore for subsequent beneficiation studies in laboratory scale. The experiments were carried out by varying the concentration of H2 SO4 solution and the leaching temperature. The properties of the iron ore was characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM)...

Vanadium recovery of Thermal Power Plant Ash (TPPA) is an attractive process which simultaneously satisfies the pollution control standards regarding TPPA disposal and provides a valuable source of vanadium for industrial demands. In the present research work, sulfuric acid leaching route has been employed for vanadium recovery from an Iranian TPPA. Effects of acid concentration, temperature, a...

Aggregates containing certain constituents can react with alkali hydroxides in concrete. The reactivity is potentially harmful only when it produces significant expansion (Mather 1975). This alkali-aggregate reactivity (AAR) has two forms—alkali-silica reaction (ASR) and alkali-carbonate reaction (ACR, sometimes called alkali-carbonate rock reaction, or ACRR). ASR is more often a concern than A...

purpose : studies show that phenytoin is effective in improvement of different chronic ulcers such as venous stasis ulcers, and diabetic ulcers. the exact mechanism is yet not clear investigators thought that phenytoin might help to heal intractable corneal ulcers by reducing inflammation, differentiating limbal fibroblasts, and promoting the invasion of the cornea with new blood vessels as sho...

In Canterbury land-use intensification, particularly irrigated dairy expansion, is occurring on stony soils. Concerns exist about the ability of these soils to sustain intensified land-use, while maintaining nutrient leaching within discharge limits. Environmental models consistently predict stony soils as having a high vulnerability to leaching under intensive land use, but there is little exp...