Theoretical study on separation density of gravity beneficiation

Separation density is one of the most concerned operating parameters in gravity beneficiation.Although equal-errors cut point or distribution density is usually used as practical separation density in gravity beneficiation, the gravity separating process complexly affected by many kinds of factors is actually carried out at a fluctuant density; namely, the practical separation density is essentially a random variable.The studied results show that the equal-errors cut point is the mathematical expectation of this random variable, and the distribution density corresponds to the highest separation efficiency in the gravity separation process.This shows that the distribution density is the best working point of the gravity separation equipment under a particular operating condition.Therefore,in order to fully develop the function of the gravity separation equipment, the distribution density should be close to the theoretical separation density unlimitedly in the range of minimum fluctuation.

Separation density prediction of geldart A^(-)dense medium in gas-solid fluidized bed coal beneficiators

Gas-solid Fluidized Bed Coal Beneficiator(GFBCB)process is a crucial dry coal beneficiation fluidization technology.The work employs the GFBCB process alongside a novel Geldart A^(-)dense medium,consisting of Geldart A magnetite particles and Geldart C ultrafine coal,to separate small-size separated objects in the GFBCB.The effects of various operational conditions,including the volume fraction of ultrafine coal,the gas velocity,the separated objects size,and the separation time,were investigated on the GFBCB's separation performance.The results indicated that the probable error for 6∼3 mm separated objects could be controlled within 0.10 g/cm^(3).Compared to the traditional Geldart B/D dense medium,the Geldart A/A^(-)dense medium exhibited better size-dependent separation performance with an overall probable error 0.04∼0.12 g/cm^(3).Moreover,it achieved a similar separation accuracy to the Geldart B/D dense medium fluidized bed with different external energy for the small-size object beneficiation.The work furthermore validated a separation density prediction model based on theoretical derivation,available for both Geldart B/D dense medium and Geldart A/A^(-)dense medium at different operational conditions.

Utilization of Bubbles and Oil for Microplastic Capture from Water

The removal of microplastics(MPs)from water using oil has shown early promise;however,incorporation of this technique into a feasible in situ method has yet to be developed.Here,a simple yet effective method of MP capture from water using vegetable oil with bubbles is demonstrated to achieve high removal efficiencies of>98%.Comparisons are made with other methods of agitation,and higher removal efficiencies are observed when bubbles are used.Due to the low agitation provided by the bubbles,the oil layer remains unbroken,meaning that no oil is released into the bulk water phase.In this way,secondary contamination is avoided—unlike membrane filtration,another effective removal method,in which polymer-based membranes can break down due to chemical backwashing and ageing.It is demonstrated that variation in MP size within the micrometer range(50–170 lm)has minor impact on the removal efficiency;however,100%removal is achieved for larger,millimeter-sized MPs(500–5000 lm).Similarly,a high removal efficiency of greater than 99%is achieved in the capture of microfibers.Other factors such as oil volume and water salinity are also investigated and discussed.Based on these results,the proposed method can be introduced into multiple setting types as a passive and continuous method of MP capture.

Microplastics Detection and Identification in the Waters along Coastal Areas of Borongan City

This study detects the presence of microplastics in the coastal areas of Borongan City, Eastern Samar, this specifically implies the microplastics present in the waters along coastal areas of Borongan City. Two (2) sampling areas were identified and selected for the presence of these microcontaminants using density separation, filtration and microscopic identification. Results reveal a total of 35 microplastics observed from the water samples collected, with this the microplastics from Baybay boulevard with an average of 0.79 microplastics per Liter, while the average microplastic contamination in Hilangagan beach resort was calculated at 0.43 microplastics per Liter. This sums up to an average of 0.49 microplastics per Liter for both sampling sites in Borongan City.

Density gradient ultracentrifugation for colloidal nanostructures separation and investigation

In this article,we review the advancement in nanoseparation and concomitant purification of nanoparticles(NPs) by using density gradient ultracentrifugation technique(DGUC) and demonstrated by taking several typical examples.Study emphasizes the conceptual advances in classification,mechanism of DGUC and synthesis-structure-property relationships of NPs to provide the significant clue for the further synthesis optimization.Separation,concentration,and purification of NPs by DGUC can be achieved at the same time by introducing the water/oil interfaces into the separation chamber.We can develop an efficient method ‘‘lab in a tube" by introducing a reaction zone or an assembly zone in the gradient to find the surface reaction and assembly mechanism of NPs since the reaction time can be precisely controlled and the chemical environment change can be extremely fast.Finally,to achieve the best separation parameters for the colloidal systems,we gave the mathematical descriptions and computational optimized models as a new direction for making practicable and predictable DGUC separation method.Thus,it can be helpful for an efficient separation as well as for the synthesis optimization,assembly and surface reactions as a potential cornerstone for the future development in the nanotechnology and this review can be served as a plethora of advanced notes on the DGUC separation method.

INVESTIGATION OF DOMINANT FREQUENCIES IN TRANSITION REYNOLDS NUMBER RANGE OF FLOW AROUND A CIRCULAR CYLINDER PARTⅡ: THEORETICAL DETERMINATION OF THE RELATIONSHIP BETWEEN VORTEX SHEDDING AND TRANSITION FREQUENCIES AT DIFFERENT REYNOLDS NUMBERS

An attempt has been made to explore whether the power relation can be obtained from theoretical considerations. The classical laminar and turbulent boundary layer concepts have been employed to determine appropriate values of the scaling lengths associated with vortex shedding and shear layer frequencies to predict the power law relationship with Reynolds number. The predicted results are in good agreement with experimental results. The findings will provide a greater insight into the overall phenomenon involved.