Apatite-staffelite ore flotation efficiency improvement using two-stage slurry thickening

2022 ◽  
pp. 121-131
Author(s):  
Valery Morozov ◽  
Polivanskaya Valeriya
Keyword(s):  
Caustic Soda ◽  
Liquid Glass ◽  
Efficiency Improvement ◽  
Selective Flocculation ◽  
Two Stage ◽  
Flotation Process ◽  
Apatite Concentrate ◽  
P2o5 Content ◽  
Condensed Product ◽  
Mode A

The studies were performed suggesting that the cause of P2O5 losses during apatite-staffelite ores (ASO) treatment are due to non-selective flocculation of fine classes during flotation. When using strong flocculants, special preparation of condensed slurries is necessary, ensuring their deflocculation before the flotation process. A scheme and mode of preparation of fine classes for the flotation process have been developed, including thickening of the classification overflows using strong anionic flocculants and deflocculation of the thickened product before the flotation process with reagents-dispersants used in the basic flotation mode. A mode of preparation of slimes of ASO ores for flotation is proposed, including thickening of the discharge of the classification operation using the anionic flocculant “Praestol-2540”, conditioning of the condensed product with additions of liquid glass and caustic soda in a ratio of 1 : 1, dilution and re-thickening of deflocculated slimes, consolidation and flotation thickened sludge and sand. The big laboratory tests have shown that the application of the developed regime provides a total increase in the extraction of P2O5 from ore from 70,1 to 71,5 % with an increase in the P2O5 content in apatite concentrate from 37,1 to 37,8 %, which makes the developed technology promising for processing refractory ASO at Kovdorsky GOK.

scholarly journals A Review on Anaerobic Co-Digestion with a Focus on the Microbial Populations and the Effect of Multi-Stage Digester Configuration

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 1106 ◽  
Author(s):  
Anahita Rabii ◽  
Saad Aldin ◽  
Yaser Dahman ◽  
Elsayed Elbeshbishy
Keyword(s):  
Anaerobic Digestion ◽  
Microbial Population ◽  
System Stability ◽  
Microbial Consortia ◽  
Microbial Populations ◽  
Stage Versus ◽  
Two Stage ◽  
Waste Sludge ◽  
Multi Stage ◽  
Mode A

Recent studies have shown that anaerobic co-digestion (AnCoD) is superior to conventional anaerobic digestion (AD). The benefits of enhanced bioenergy production and solids reduction using co-substrates have attracted researchers to study the co-digestion technology and to better understand the effect of multi substrates on digester performance. This review will discuss the results of such studies with the main focus on: (1) generally the advantages of co-digestion over mono-digestion in terms of system stability, bioenergy, and solids reduction; (2) microbial consortia diversity and their synergistic impact on biogas improvement; (3) the effect of digester mode, i.e., multi-stage versus single stage digestion on AnCoD. It is essential to note that the studies reported improvement in the synergy and diverse microbial consortia when using co-digestion technologies, in addition to higher biomethane yield when using two-stage mode. A good example would be the co-digestion of biodiesel waste and glycerin with municipal waste sludge in a two-stage reactor resulting in 100% increase of biogas and 120% increase in the methane content of the produced biogas with microbial population dominated by Methanosaeta and Methanomicrobium.

CFD Analysis of the Unsteady Flow in a Two-Stage Axial Turbine

2016 ◽  
Author(s):  
Yang Pan ◽  
Qi Yuan ◽  
Qian Chen ◽  
Qing Ge ◽  
Dawei Ji
Keyword(s):  
Unsteady Flow ◽  
Rotational Speed ◽  
High Speed ◽  
Stokes Equations ◽  
Great Influence ◽  
Two Stage ◽  
Lower Efficiency ◽  
Axial Turbine ◽  
Partial Admission ◽  
Mode A

Partial admission, which has the advantage of avoiding large losses while the turbine at low load operations, is widely used in regulating the power of turbomachinery. However, partial admission causes prominent unsteady flow, additional exciting forces and extra losses. Thus, it has great significance to investigate the characteristics of partial admission turbines. In this paper, efficiency and unsteady flow performance of a small two-stage subsonic axial turbine with partial admission are analyzed. Firstly, a 3-D model with four discontinuous equally-distributed nozzle blocks was built, and the computational grid, which only consisted of hexahedral mesh, was generated. Reynolds Averaged Navier-Stokes equations were solved by commercial software ANSYS-CFX and the RNG k-ε turbulence model was adopted. Secondly, to investigate the influence of admission modes, two partial admission modes (A-two diagonal valve opening; B-two adjacent valves opening) were analyzed separately and compared with the full admission situation (Mode C). Finally, the turbine performances in Mode A and B at other speeds (75% and 110% of rated speed) were analyzed and pressure distributions at three different heights (10%, 50% and 90% of the blade height) were investigated in detail. The results indicated that partial admission could cause extra mixture losses and lead to lower efficiency. Among these kinds of modes, full admission (Mode C) performed best in efficiency, and Mode B performed better than Mode A under partial admission conditions. Furthermore, strong non-uniformity was found in circumferential direction and large pressure drop occurred at the gap between two admission blocks due to expansion effects. The computational results also showed that the flow parameter fluctuations attenuated evidently in the downstream stages and the pressure vibration mainly occurred after nozzle stages. Strong vortices and backflow can be noticed at the pressure side of the active nozzle boxes. Additionally, the rotational speed has a great influence on the performance of turbine. Higher rotational speed led to bigger efficiency and smoother pressure distribution. And the alteration trend becomes slow at high speed.

Light load efficiency improvement of solar farms three-phase two-stage module integrated converter

2016 ◽  
Author(s):  
Ahmadreza Amirahmadi ◽  
Utsav Somani ◽  
Mahmood Alharbi ◽  
Charlie Jourdan ◽  
Issa Batarseh
Keyword(s):  
Efficiency Improvement ◽  
Two Stage ◽  
Light Load ◽  
Three Phase
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