Recovery of residual carbon from coal gasification fine slag by a combined gravity separation-flotation process.

Recovering inner residual carbon is important for fully utilizing coal gasification fine slag (CGFS) resources. In this study, we adopted a combined gravity-separation and flotation process to efficiently recover residual carbon by considering the characteristics of the CGFS and optimizing the operating factors of the process. CGFS is principally a mixture of residual carbon and ash, with low-density particles containing more of the former. Accordingly, residual carbon is preliminarily enriched by gravity separation, in which gas velocity (vg) and water velocity (vw) significantly impact separation efficiency, followed by feed volume (m). The residual carbon in the initial concentrate was preliminarily enriched (i.e., loss on ignition (LOI): 55.90%; combustible recovery (Ro): 72.36%) under appropriate operating conditions (i.e., vw = 0.04 m/s, vg = 3 m/s, m = 150 g). Moreover, the quality of the flotation concentrate was most influenced by collector dosage (mc), followed by aeration rate (η), frother dosage (mf), stirring speed (w), and grinding time (t) during flotation of the primary concentrate. The flotation concentrate exhibited LOI and Ro values of 90.95% and 50.34%, respectively, under the optimal flotation conditions (i.e., mc = 20 kg/t, mf = 15 kg/t, w = 2600 rad/min, η = 200 L/h, t = 360 s); it has a high residual carbon content and is an ideal raw material for preparing fuels or carbon materials.

Effects of Electroacupuncture on Sleep via the Dopamine System of the HPA Axis in Rats after Cage Change.

BACKGROUND: Insomnia is often related to stressful events. The hypothalamus-pituitary-adrenal (HPA) axis is related to stress, and dopamine (DA) and DA receptors are involved in the regulation of HPA axis. Electroacupuncture (EA) can improve sleep in individuals with insomnia, but the mechanism is unclear. We demonstrated that EA can improve sleep in rats after cage change through DA and the DA receptors in the HPA axis. METHODS: A rat model of insomnia was established by cage change to a dirty cage. The rats in treatment groups were intervened by EA and D1R (or D2R) antagonists. Electroencephalography (EEG) and electromyogram (EMG) were recorded to compare the changes in sleep. The DA, corticotropin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH), and cortisol (CORT) levels in the plasma and hypothalamus were measured by ELISAs, and the D1R and D2R levels were measured by RT-PCR and immunohistochemistry. RESULTS: The dirty group showed a significant increase in the amount of wakefulness and decrease in the amount of NREM sleep, with decreased numbers of long NREM sleep bouts and REM sleep bouts and increased mean duration of wakefulness during the light period. EA and D1R (or D2R) antagonists intervention could improve sleep disturbance by decreasing wakefulness in the light period after cage change, EA and D1R (or D2R) antagonists could increase the hypothalamus DA, CRH, ACTH, CORT level, and the D1R and D2R mRNA levels in the HPA axis, and the effect of EA plus D1R (or D2R) antagonist was not superior to that of EA or D1R (or D2R) antagonists alone. CONCLUSIONS: EA can improve the sleep of rats after cage change, and the mechanism may be related to the regulation of DA and D1R or D2R in the HPA axis.

The role of EDTA on rutile flotation using Al3+ ions as an activator.

Rutile is a relatively stable mineral, due to its weakly specific adsorption to collectors. The development and application of a high efficiency and low-toxicity activator is the main challenge in rutile flotation. In this study, Al3+ ions and EDTA (ethylene diamine tetraacetic acid) as mixed activators were investigated using micro-flotation tests. The results of the micro-flotation tests showed that the flotation recovery was slightly increased (from 65.8% to 69.7%) using single Al3+ ions as the activator and surprisingly, the activating effect was sharply improved (from 69.7% to 80.6%) after adding EDTA. The activating mechanism of Al3+ ions and EDTA was revealed by adsorption capacity measurements, zeta potential measurements, FT-IR spectroscopy analysis and XPS analysis. Al3+ ions were adsorbed on the rutile surface in the form of Al(OH) n 3-n (n = 0, 1, 2), which increased the zeta potential and the activating sites for anionic collector adsorption. The addition of EDTA removed the surplus Al3+ ions, and prevented the generation of hydrophilic colloidal Al(OH)3 over the pH range of optimum flotation.