scholarly journals PHYSICOCHEMICAL AND ELECTROCHEMICAL METHODS FOR MODIFYING THE PROPERTIES OF DIAMONDS AND ORE PULP COMPONENTS DURING THE SEPARATION OF DIAMOND-BEARING KIMBERLITES

2021 ◽  
Vol 13 (2) ◽  
pp. 238-247
Author(s):  
Galina DVOICHENKOVA ◽  
◽  
Elena CHANTURIA ◽  
Alexander TIMOFEEV ◽  
Elena CHERNYSHEVA ◽  
...  
Keyword(s):  
Raw Materials ◽  
Experimental Studies ◽  
Dense Medium ◽  
Protective Shell ◽  
Foam Separation ◽  
Industrial Enterprises ◽  
Diamond Crystals ◽  
Heavy Medium ◽  
The Media ◽  
The Stability

The main deposits of kimberlite ores located in the regions of Western Yakutia are enriched at the ALROSA diamond extraction factories using a similar technology, in which the maximum completeness of extraction and safety of diamond crystals is ensured by the stages of schemes. The bulk of diamond crystals is extracted in the processes of heavy medium, sticky and foam separation, the effectiveness of which is determined by the properties of diamonds, kimberlite minerals and the media separating them. The article presents the results of theoretical and experimental studies carried out by ICEMR RAS together with the largest universities in Russia, scientific and industrial enterprises of ALROSA. It is shown that the use of combined energy methods of destruction and removal of hydrophilizing formations on diamond crystals provides hydrophobization of their surface in the processes of sticky and foam separation. It has been established that the efficiency and economic indicators of the process of dense medium separation of diamond-containing raw materials are due to the stability of the technological properties of the weighting agent of the ferrosilicon medium and the suspension prepared on its basis. The method for modifying the corrosion resistance of ferrosilicon by nitriding its surface has been substantiated and tested. The proposed method makes it possible to create a protective shell on the surface of the granules, preventing their destruction upon contact with corrosive components of the water-air environment. Semi-industrial tests have established the possibility of increasing the extraction of diamonds into concentrates for sticky and foam separation by 4 and 5.2%, respectively. The results of laboratory tests have confirmed the possibility of reducing the corrosion rate of ferrosilicon by 5-6 times in the process of dense medium separation.

scholarly journals Experimental studies on preparation of the porous and small-diameter poly(ε-caprolactone) external vascular scaffold and its degradability and biocompatibility

2018 ◽  
Vol 6 ◽  
pp. 2
Author(s):  
Qingyun Chen ◽  
Xia Jiang ◽  
Li Feng
Keyword(s):  
Mechanical Property ◽  
Raw Materials ◽  
Degradation Mechanism ◽  
Experimental Studies ◽  
Small Diameter ◽  
Thermomyces Lanuginosus ◽  
Control Group ◽  
Vascular Scaffold ◽  
The Media ◽  
Form Stability

Aim: This study was aim to prepare a porous poly(ε-caprolactone) (PCL) biodegradable external vascular scaffold by dipping and leaching method, and to assess its mechanical property, degradability and biocompatibility. Methods: We used the PCL-1, PCL-2 as the raw materials and NaCl particles as the pore-forming agents to construct a porous PCL external vascular scaffold. We tested the mechanical property of the porous PCL external vascular scaffold. The degradability of the scaffold was studied in the presence of thermomyces lanuginosus lipase (TL lipase). After 1, 3, and 5, 7 days, the samples were taken out, and the pH of the media was measured. The form-stability of the scaffold was investigated by macroscopic observation and the microstructure of it was observed by SEM. The cytotoxicity of the scaffold was evaluated by CCK-8 assay. Results: PCL-1 could make a white integrated external vascular scaffold with uniform texture. When the concentration of NaCl was less than or equal to 50%, the tensile strength of the porous PCL-1 external vascular scaffolds were higher than 4.2 Mpa, which meet the demand of clinical vascular transplantation. With the degradation of the scaffold in the lipase media, the form-stability of the scaffold was seriously destroyed, the surface of the scaffold began to degrade with some honeycomb holes, and the pH of the media values were lower than the initial reading of 7.4. Rat adipose-derived stem cells (rADSCs) cultured in the extractions of the porous PCL external vascular scaffold had good proliferation and cell morphology compared to the control group. Conclusion: The porous PCL-1-50 external vascular scaffold, with the 50% concentration of NaCl, had the maximum porosity on the basis of enough mechanical strength which meets the demand of clinical vascular transplantation. Moreover, it had good biocompatibility with rADSCs and the degradation mechanism of the scaffold was surface degradation.

scholarly journals Analysis of composition and dispersion of fuel emulsions

2020 ◽  
pp. 124-131
Author(s):  
V. O. Melnyk
Keyword(s):  
Raw Materials ◽  
Thermal Power ◽  
Practical Importance ◽  
Poor Quality ◽  
Fuel Oil ◽  
Polluted Water ◽  
Water Emulsion ◽  
Industrial Enterprises ◽  
The Stability ◽  
The Cost

The development of the economy of the state, as well as industrial enterprises, leads to an increase in demand for all types of energy carriers. This is characterized by the constant search and exploration of new progressive types of energy and sources of raw materials, especially for thermal power plant TPPs, CHPs and utilities, which use liquid fuel - usually fuel oil - to operate. For such enterprises, stable and timely supply of fuel raw materials, improvement of methods of its combustion, reduction in the cost of obtaining energy, etc. are relevant. Existing heavy hydrocarbon combustion technologies are of poor quality and it is therefore advisable to develop new ones or to optimize existing ones. This will reduce energy costs for technological preparatory operations for the de-watering of fuels, reduce the amount of polluted water reservoirs, and minimize their harmful effects on the envi-ronment. One of the most promising areas for combustion of heavy water hydrocarbons is the use of water emulsion fuels (WEF). The stability and efficiency of combustion of such a fuel emulsion will greatly depend on the amount and dispersion of water in the WEF. Today, such emulsification technologies and WEF parameters are not yet well understood and are therefore of great scientific and practical importance. The analysis of the theories describing the effect of dispersion and the amount of water in the emulsion on the combustion indices shows that they are contradictory. This can be due to the different physical characteristics of the fuel: composition, viscosity, temperature, etc., which has led to different results. Since studies by different authors were conducted under dif-ferent conditions, modes, equipment and with different fuel emulsions, it is not possible to indicate the optimum value of dispersion and amount of water. Obviously, in each case there will be a different optimal "surface" of the ratio of the size of the droplets of water and its number in the WEF. Future experimental and theoretical studies on the combustion of WEF should focus on the water content range of 3-30% and the dispersion of 1-35 microns.

A possibility of using nickel concentrate, obtained as a result of hydrometallurgical enrichment of manganese-containing raw materials, at steel alloying

2020 ◽  
Vol 76 (7) ◽  
pp. 709-715
Author(s):  
O. Yu. Kichigina
Keyword(s):  
Raw Materials ◽  
Experimental Studies ◽  
Selective Extraction ◽  
Technological Parameters ◽  
Nickel Iron ◽  
Nickel Recovery ◽  
Nickel Concentrate ◽  
Steel Alloying ◽  
High Degree ◽  
Comprehensive Processing

At production of stainless steel expensive alloying elements, containing nickel, are used. To decrease the steel cost, substitution of nickel during steel alloying process by its oxides is an actual task. Results of analysis of thermodynamic and experimental studies of nickel reducing from its oxide presented, as well as methods of nickel oxide obtaining at manganese bearing complex raw materials enrichment and practice of its application during steel alloying. Technology of comprehensive processing of complex manganese-containing raw materials considered, including leaching and selective extraction out of the solution valuable components: manganese, nickel, iron, cobalt and copper. Based on theoretical and experiment studies, a possibility of substitution of metal nickel by concentrates, obtained as a result of hydrometallurgical enrichment, was confirmed. Optimal technological parameters, ensuring high degree of nickel recovery out of the initial raw materials were determined. It was established, that for direct steel alloying it is reasonable to add into the charge pellets, consisting of nickel concentrate and coke fines, that enables to reach the through nickel recovery at a level of 90%. The proposed method of alloying steel by nickel gives a possibility to decrease considerably steel cost at the expense of application of nickel concentrate, obtained out of tails of hydrometallurgical enrichment of manganese-bearing raw materials, which is much cheaper comparing with the metal nickel.

FUNDAMENTAL CAPITAL FINANCING OF PRODUCTION

2020 ◽  
Vol 8 (3) ◽  
pp. 74-78
Author(s):  
Farrux Zulfiyev ◽  
Keyword(s):  
Raw Materials ◽  
Economic Reforms ◽  
Equity Financing ◽  
Capital Financing ◽  
The Republic ◽  
The Stability

This article is based on the principles of shared financing of the production of raw materials. The article is aimed at financing the production of capital on the basis of equity in order to further strengthen the stability of economic reforms in the republic. At the same time, the essence of equity financing, the risks associated with it, and the efficiency of raw materials are covered

scholarly journals Performance Evaluation of Heading-and-Winning Machines in the Conditions of Potash Mines

2021 ◽  
Vol 11 (8) ◽  
pp. 3444
Author(s):  
Sergey A. Lavrenko ◽  
Dmitriy I. Shishlyannikov
Keyword(s):  
Energy Efficiency ◽  
Experimental Studies ◽  
Efficiency Coefficient ◽  
Mechanized Method ◽  
Methodological Approaches ◽  
The Stability ◽  
Technical Solutions ◽  
Potash Mine ◽  
Complex Indicators ◽  
Potassium Magnesium

The authors focus on the process of potash ore production by a mechanized method. They show that currently there are no approved procedures for assessing the performance of heading-and-winning machines operating in the conditions of potash mines. This causes difficulties in determining the field of application of heading-and-winning machines, complicates the search for implicit technical solutions for the modernisation of existing models of mining units, prohibits real-time monitoring of the stability of stope-based technological processes and makes it difficult to assess the performance of the services concerning mining enterprises. The work represents an aggregate assessment of the performance of heading-and-winning machines for potash mines by determining complex indicators describing the technological and technical levels of organising the work in stopes. Such indicators are the coefficients of productivity and energy efficiency, respectively. Experimental studies have been carried out in the conditions of the potash mine of the Verkhnekamskoye potassium-magnesium salt deposit to assess the performance of the latest and most productive Ural-20R heading-and-winning machines manufactured in Russia. Using the above methodological approaches, this paper shows that the unsatisfactory technological performance of the studied machine is due to the low productivity of the mine district transport. The average productivity coefficient was 0.29. At the same time, high values of the energy efficiency coefficient show that the productivity of the machine is on par with design conditions.

scholarly journals Causality and stability conditions of a conformal charged fluid

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
Farid Taghinavaz
Keyword(s):  
Chemical Potential ◽  
Second Law Of Thermodynamics ◽  
Dense Medium ◽  
Wave Number ◽  
Second Law ◽  
Stability Conditions ◽  
Charged Fluid ◽  
Large Wave ◽  
The Stability ◽  
Large Wave Number

Abstract In this paper, I study the conditions imposed on a normal charged fluid so that the causality and stability criteria hold for this fluid. I adopt the newly developed General Frame (GF) notion in the relativistic hydrodynamics framework which states that hydrodynamic frames have to be fixed after applying the stability and causality conditions. To do this, I take a charged conformal matter in the flat and 3 + 1 dimension to analyze better these conditions. The causality condition is applied by looking to the asymptotic velocity of sound hydro modes at the large wave number limit and stability conditions are imposed by looking to the imaginary parts of hydro modes as well as the Routh-Hurwitz criteria. By fixing some of the transports, the suitable spaces for other ones are derived. I observe that in a dense medium having a finite U(1) charge with chemical potential μ0, negative values for transports appear and the second law of thermodynamics has not ruled out the existence of such values. Sign of scalar transports are not limited by any constraints and just a combination of vector transports is limited by the second law of thermodynamic. Also numerically it is proved that the most favorable region for transports $$ {\tilde{\upgamma}}_{1,2}, $$ γ ˜ 1 , 2 , coefficients of the dissipative terms of the current, is of negative values.

Applications of Computational Fluid Dynamics (CFD) Tools for Gravity Concentrators in Coal Preparation

2007 ◽  
Vol 2 (1) ◽  
Author(s):  
Y. K. Xia
Keyword(s):  
Multiphase Flows ◽  
Coupling Effect ◽  
Numerical Models ◽  
Dense Medium ◽  
Hindered Settling ◽  
Heavy Medium ◽  
Computational Fluid Dynamics Cfd ◽  
Dimensional Simulation ◽  
Dense Medium Cyclone ◽  
Lagrange Approach

Extensive progress has been made in using CFD tool in the simulation of multiphase flows in some gravity concentrators. Several case studies for calculation of multiphase flows by different numerical models in spiral, dense medium cyclone, water only cyclones, hindered-settling bed separator, heavy medium vessel and jig are reviewed. The Euler-Lagrange approach in calculation of the particle movement and particle-liquid coupling effect are also discussed. The limitation of Euler-Euler models in the treatment of the particles with a size distribution, and disadvantages of discrete element method (DEM) in description of the jigging processes will be presented. The successful two-dimensional simulation of the hindered-settling bed separator, heavy medium vessel and jig by Euler-Lagrange approach is also addressed.

scholarly journals Extended-State-Observer-Based Super Twisting Control for Pneumatic Muscle Actuators

Actuators ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 35
Author(s):  
Yu Cao ◽  
Zhongzheng Fu ◽  
Mengshi Zhang ◽  
Jian Huang
Keyword(s):  
Control Method ◽  
Experimental Studies ◽  
State Observer ◽  
Extended State Observer ◽  
Extended State ◽  
Pneumatic Muscle ◽  
System States ◽  
The Stability ◽  
Twisting Control ◽  
Muscle Actuators

This paper presents a tracking control method for pneumatic muscle actuators (PMAs). Considering that the PMA platform only feedbacks position, and the velocity and disturbances cannot be observed directly, we use the extended-state-observer (ESO) for simultaneously estimating the system states and disturbances by using measurable variables. Integrated with the ESO, a super twisting controller (STC) is design based on estimated states to realize the high-precision tracking. According to the Lyapunov theorem, the stability of the closed-loop system is ensured. Simulation and experimental studies are conducted, and the results show the convergence of the ESO and the effectiveness of the proposed method.

SEISMIC WAVE PROPAGATION IN POROUS GRANULAR MEDIA

Geophysics ◽  
1956 ◽  
Vol 21 (3) ◽  
pp. 691-714 ◽  
Author(s):  
Norman R. Paterson
Keyword(s):  
Granular Media ◽  
Experimental Studies ◽  
Seismic Wave Propagation ◽  
Beach Sand ◽  
Sound Waves ◽  
Filling Materials ◽  
Porosity And Permeability ◽  
Size Sorting ◽  
The Media ◽  
A Charge

Theoretical and experimental studies have been made of the manner in which sound waves are propagated in porous granular aggregates. A cylindrical piezo‐electric source is used and this simulates the explosion of a charge in a seismic shot‐hole. It is found that in general two waves of volume expansion are propagated and that these involve coupled displacements of both constituents of the media. The waves are termed frame‐waves, air‐waves or liquid‐waves depending upon the nature of the pore‐filler and the relative displacements of the constituents. The frame‐wave velocity is dependent upon the strength of the frame, the densities of solid and pore‐filling materials and the texture of the medium. Air‐ and liquid‐wave velocities are related to the texture of the medium and to the density and viscosity of the pore‐filler. Frame‐strength is important to a lesser degree. Waves are dispersive only in the case of media of very low permeability. Attenuation is related to viscosity, texture and frequency. Scattering is probably important only at the highest frequencies and largest particle diameters used in the experiments. It is shown that porosity and permeability of a beach sand can be inferred from velocity measurements. These properties provide information regarding grain‐size, sorting and the nature of the pore‐filler.

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