scholarly journals Silylated Thiol-Containing Cellulose Nanofibers as a Bio-Based Flocculation Agent for Ultrafine Mineral Particles of Chalcopyrite and Pyrite

2021 ◽  
Author(s):  
Ana Luiza Coelho Braga de Carvalho ◽  
Feliciana Ludovici ◽  
Daniel Goldmann ◽  
André Carlos Silva ◽  
Henrikki Liimatainen
Keyword(s):  
Ultrafine Particles ◽  
Fine Particles ◽  
Cellulose Nanofibers ◽  
Aqueous Alkaline Medium ◽  
Selective Flocculation ◽  
Turbidity Removal ◽  
Floc Size ◽  
Mineral Particles ◽  
Tailing Ponds ◽  
Anionic Polyacrylamide

AbstractA considerable amount of very fine particles can be found, e.g., stored in tailing ponds, and they can include valuable or hazardous minerals that have the potential to be recovered. Selective flocculation, i.e., the formation of larger aggregates from specific minerals, offers a promising approach to improve the recovery of ultrafine particles. This study focuses on the use of a new bio-based flocculation agent made of silylated cellulose nanofibers containing a thiol-functional moiety (SiCNF). Flocculation was performed in separated systems of ultrafine mineral dispersions of pyrite, chalcopyrite, and quartz in aqueous alkaline medium. The flocculation performance of SiCNF was addressed in terms of the turbidity reduction of mineral dispersions and the floc size, and the results were compared with the performance of a commercial anionic polyacrylamide. SiCNF exhibited a turbidity removal efficiency of approximately 90%–99% at a concentration of 4000–8000 ppm with chalcopyrite and pyrite, whereas the turbidity removal of quartz suspension was significantly lower (a maximum of approximately 30%). The sulfide particles formed flocs with a size of several hundreds of micrometers. The quartz in turn did not form any visible flocs, and the dispersion still had a milky appearance after dosing 12,000 ppm of the flocculant. These results open a promising path for the investigation of SiCNF as a selective flocculation agent for sulfide minerals. Graphical Abstract

Study on Dispersion Behaviors of Oolitic Hematite Ultrafine Particles in Water

2011 ◽  
Vol 383-390 ◽  
pp. 3169-3173
Author(s):  
Fu Sheng Niu ◽  
Shu Xian Liu ◽  
Jin Xia Zhang ◽  
Yi Miao Nie
Keyword(s):  
Water Quality ◽  
Ultrafine Particles ◽  
Iron Ore ◽  
Fine Particles ◽  
Mixing Time ◽  
Selective Flocculation ◽  
Essential Condition ◽  
Dispersing Agent ◽  
Hematite Ore ◽  
Oolitic Hematite Ore

The fine oolitic hematite ore (＜20μm) is easily covered by the ore slime, therefore, it is processed very difficultly with traditional crafts, for example, gravity treatment, magnetic separation, and flotation. The tiny iron ore is unable to recycle effectively, bring about a large of useful minerals running off. It is indicated that the selective flocculation is effective separation craft in many research works. The good dispersion of fine particles is the selective flocculation essential condition, the excessive dispersion will destroy the selective flocculation, at the same time it can be influenced by the water quality, pH, the mixing time, the shear rate and the dispersing agent use level. In this article, to oolitic hematite ore, the chemistry dispersion research is conducted to provide the foundation for further selective flocculation separation.

Studies of copper selenide ultrafine particles by newly developed gas evaporation method

1990 ◽  
Vol 48 (4) ◽  
pp. 306-307
Author(s):  
Chihiro Kaito ◽  
Yoshio Saito
Keyword(s):  
Crystal Structure ◽  
Ultrafine Particles ◽  
Fine Particles ◽  
Production Method ◽  
Atmospheric Temperature ◽  
Copper Selenide ◽  
Quartz Boat ◽  
Selenium Vapor ◽  
Ar Gas ◽  
Ultra Fine Particles

The direct evaporation of metallic oxides or sulfides does not always given the same compounds with starting material, i.e. decomposition took place. Since the controll of the sulfur or selenium vapors was difficult, a similar production method for oxide particles could not be used for preparation of such compounds in spite of increasing interest in the fields of material science, astrophysics and mineralogy. In the present paper, copper metal was evaporated from a molybdenum silicide heater which was proposed by us to produce the ultra-fine particles in reactive gas as shown schematically in Figure 1. Typical smoke by this method in Ar gas at a pressure of 13 kPa is shown in Figure 2. Since the temperature at a location of a few mm below the heater, maintained at 1400° C , were a few hundred degrees centigrade, the selenium powder in a quartz boat was evaporated at atmospheric temperature just below the heater. The copper vapor that evaporated from the heater was mixed with the stream of selenium vapor,and selenide was formed near the boat. If then condensed by rapid cooling due to the collision with inert gas, thus forming smoke similar to that from the metallic sulfide formation. Particles were collected and studied by a Hitachi H-800 electron microscope.Figure 3 shows typical EM images of the produced copper selenide particles. The morphology was different by the crystal structure, i.e. round shaped plate (CuSe;hexagona1 a=0.39,C=l.723 nm) ,definite shaped p1 ate(Cu5Se4;Orthorhombic;a=0.8227 , b=1.1982 , c=0.641 nm) and a tetrahedron(Cu1.8Se; cubic a=0.5739 nm). In the case of compound ultrafine particles there have been no observation for the particles of the tetrahedron shape. Since the crystal structure of Cu1.8Se is the anti-f1uorite structure, there has no polarity.

A Study of Airborne Wear Particles Generated From a Sliding Contact

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Ulf Olofsson ◽  
Lars Olander ◽  
Anders Jansson
Keyword(s):  
Ultrafine Particles ◽  
Fine Particles ◽  
Urban Environments ◽  
Airborne Particles ◽  
Wear Particles ◽  
Coarse Particles ◽  
Sliding Velocity ◽  
Airborne Particle ◽  
Particle Generation ◽  
Pin On Disk

Recently, much attention has been paid to the influence of airborne particles in the atmosphere on human health. Sliding contacts are a significant source of airborne particles in urban environments. In this study airborne particles generated from a sliding steel-on-steel combination are studied using a pin-on-disk tribometer equipped with airborne-particle counting instrumentation. The instrumentation measured particles in size intervals from 0.01μm to 32μm. The result shows three particle size regimes with distinct number peaks: ultrafine particles with a size distribution peak around 0.08μm, fine particles with a peak around 0.35μm, and coarse particles with a peak around 2 or 4μm. Both the particle generation rate and the wear rate increase with increasing sliding velocity and contact pressure.

Flocculation as an Alternative to Increase the Recovery of Ultrafine Particles of Pyrite in Flotation of Tailings

2021 ◽  
Author(s):  
Ana Luiza Coelho Braga de Carvalho ◽  
Feliciana Ludovici ◽  
Henrikki Liimatainen ◽  
André Carlos Silva ◽  
Daniel Goldmann
Keyword(s):  
Aqueous Medium ◽  
Ultrafine Particles ◽  
Fine Particles ◽  
Column Flotation ◽  
Air Bubbles ◽  
Mineral Concentration ◽  
Alkaline Conditions

<p>Nowadays, flotation is the most commonly used method for mineral concentration. However, conventional flotation circuits are not suitable for ultrafine particles, and this is a challenge for the concentration of finely disseminated minerals. Moreover, tailing contain a considerable amount of very fine particles which can include valuable and hazardous minerals that have the potential to be recovered. Concern about ultrafine particles has increased as they are present in a wide variety of mineral pulps and can contain valuable minerals that have been lost to the tailings. Several alternatives have been proposed to improve the recovery of ultrafine particles in flotation, for example, decreasing the size of the air bubbles, column flotation, selective agglomeration of particles, etc. Among all, selective polymeric flocculation represents a promising option. The current study focuses on the use of polymeric flocculation to increasing the size of pyrite particles aiming to improve its recovery in the flotation of sulfidic tailings. Flocculation was performed with pyrite particles presenting P80 < 4 mm, in aqueous medium and alkaline conditions. Two polyacrylamides and a new nanocellulose-based chemical were used as flocculants. Microflotation tests were performed, without the addition of collector, to evaluate the formation of flocs through the reduction of the mechanical entrainment of pyrite after being submitted to flocculation.</p>

scholarly journals Exposure to Atmospheric Ultrafine Particles Induces Severe Lung Inflammatory Response and Tissue Remodeling in Mice

2019 ◽  
Vol 16 (7) ◽  
pp. 1210 ◽  
Author(s):  
Yara Saleh ◽  
Sébastien Antherieu ◽  
Romain Dusautoir ◽  
Laurent Y. Alleman ◽  
Jules Sotty ◽  
...  
Keyword(s):  
Ultrafine Particles ◽  
Chronic Exposure ◽  
Time Course ◽  
Fine Particles ◽  
Respiratory Health ◽  
Wall Thickening ◽  
Alveolar Wall ◽  
Similar Chemical ◽  
Time Course Experiment ◽  
Severe Lung

Exposure to particulate matter (PM) is leading to various respiratory health outcomes. Compared to coarse and fine particles, less is known about the effects of chronic exposure to ultrafine particles, despite their higher number and reactivity. In the present study, we performed a time-course experiment in mice to better analyze the lung impact of atmospheric ultrafine particles, with regard to the effects induced by fine particles collected on the same site. Trace element and PAH analysis demonstrated the almost similar chemical composition of both particle fractions. Mice were exposed intranasally to FF or UFP according to acute (10, 50 or 100 µg of PM) and repeated (10 µg of PM 3 times a week during 1 or 3 months) exposure protocols. More particle-laden macrophages and even greater chronic inflammation were observed in the UFP-exposed mice lungs. Histological analyses revealed that about 50% of lung tissues were damaged in mice exposed to UFP for three months versus only 35% in FF-exposed mice. These injuries were characterized by alveolar wall thickening, macrophage infiltrations, and cystic lesions. Taken together, these results strongly motivate the update of current regulations regarding ambient PM concentrations to include UFP and limit their emission.

scholarly journals Analysis of air pollution caused by particle matter emission from the copper smelter complex Bor (Serbia)

2010 ◽  
Vol 16 (3) ◽  
pp. 219-228 ◽  
Author(s):  
Visa Tasic ◽  
Novica Milosevic ◽  
Renata Kovacevic ◽  
Nevenka Petrovic
Keyword(s):  
Particulate Matter ◽  
Wind Speed ◽  
Ultrafine Particles ◽  
Fine Particles ◽  
Copper Smelter ◽  
Temporal Variations ◽  
Copper Production ◽  
Copper Smelting ◽  
Particulate Emissions ◽  
Limit Values

The main aim of this paper is to present analyses of temporal variations of particulate matter in Bor (Serbia) influenced by copper production at the Copper Smelter Complex Bor. Particulate emissions are of concern because the presence of fine particles (PM2.5 - particles with diametar less than 2.5 ?m) and ultrafine particles (PM0.1 - particles with diametar less than 0.1 ?m) assume higher risk for human health. Such particles can penetrate deeper into respiratory organs and, at the same time, a probability for such penetration and deposition in the respiratory system is greater. The analysis is based on comparison of SO2 and PM measurements at several locations in the area of Bor town in the close vicinity of Copper Smelter. PM concentrations were highly correlated with sulfur dioxide and inversely correlated with local wind speed during pollution episodes. Presented results indicate that the dominant source of coarse and fine particles in Bor town is the Copper Smelting Complex Bor. The most significant factors for particulate matter distribution are meteorological parameters of wind speed and direction. It was found that exceeding of daily limit values of concentrations of PM10 (50 ?g/m3) usually occurs due to very high concentrations in a period of several hours during the day.

The use of an analytical electron microscope in the analysis of mineral dusts

1977 ◽  
Vol 286 (1336) ◽  
pp. 625-638 ◽  
Keyword(s):  
Electron Microscope ◽  
Fine Particles ◽  
Dust Particles ◽  
Single Particles ◽  
Bulk Analysis ◽  
Mineral Concentration ◽  
Size And Shape ◽  
Mineral Particles ◽  
Analysis System ◽  
Bulk Chemistry

Dust samples, whatever their source, usually consist of small quantities of very fine particles from which the following information is necessary: (a) the morphology of the mineral particles in the dust, i.e. size and shape; (b) the identity of the mineral particles in the dust; (c) the proportion of each mineral contained in the dust; (d) the mineral concentration in the sample of air, water or biological material from which the dust was recovered. Information is also required as rapidly as possible from a single preparation so that many samples may be analysed on a routine basis. This paper will outline how this information can be obtained by using an electron microscope analysis system. With such an instrument, dust particles of all sizes may be observed and their size and shape obtained, while the electron microprobe may be used to analyse single particles to determine their chemistry and identify them. The bulk chemistry of the dust may be obtained in a similar manner by analysing large numbers of particles simultaneously. By using the chemical data obtained from single particles and also the bulk chemistry of the sample, the mineral composition of the dust may be computed. A measure of the mass of dust being analysed can be obtained from a measurement of the X-ray count rate obtained during bulk analysis, measurement of the incident electron-beam intensity and reference to an instrument calibration curve.

Investigation of the mechanism for selective flocculation process using natural iron ore tailings

2020 ◽  
Vol 117 (1) ◽  
pp. 102
Author(s):  
Lopamudra Panda ◽  
Surendra Kumar Biswal ◽  
Rayasam Venugopal ◽  
Narayan R. Mandre
Keyword(s):  
Ultrafine Particles ◽  
Iron Ore ◽  
Gangue Mineral ◽  
Ftir Analysis ◽  
Selective Flocculation ◽  
Iron Ore Tailings ◽  
Natural Iron ◽  
The Government ◽  
Zeta Potential Analysis ◽  
Flocculation Process

A huge quantity of iron ore tailings was generated every year from the iron ore washing plants during beneficiation. These discarded tailings were stored in the tailing pond. Safe storage and handling of these tailings are a major concern to the management. Due to depletion of high-grade ore, the government of India had reduced the cut-off grade from 55 to 45% because of the shortage of the iron ore reserves. Ultrafine particles present in the tailings cannot be treated effectively by the conventional methods due to particle size limitations. For Indian iron ore, associated gangue mineral alumina is the major source which causes problems in the blast furnace. Removal of alumina from the iron ore of ultrafine size is a hill task. A selective flocculation approach was employed to the iron ore tailings which contain 50.98% of Fe (T) with 8.86% of Al2O3 assay. It was observed that, when applying a selective flocculation process, the concentrate contains more than 63.48% Fe (%), 2.5% Al2O3 with 31.196% recovery (%). The mechanism was investigated using zeta potential analysis, FTIR analysis, etc.

Chemical Reactions with Single Microparticles

MRS Bulletin ◽  
1990 ◽  
Vol 15 (1) ◽  
pp. 26-33 ◽  
Author(s):  
E. James Davis ◽  
Mark F. Buehler
Keyword(s):  
Ultrafine Particles ◽  
Fine Particles ◽  
Reaction Rates ◽  
Pure Metal ◽  
Metal Alkoxide ◽  
Electrodynamic Balance ◽  
Hydrolysis Rates ◽  
Photochemical Polymerization ◽  
Titanium Silicon ◽  
Hydrolysis Of

Fine particles can be produced via aerosol processes either by means of vapor phase reactions that produce solid or liquid particles or by reactions between a preexisting solid or liquid particle and a reactive gas. This article examines the latter processes because a strong interest has developed in the production of materials via aerosol processing. Although fine particles are frequently produced using flow systems, such as in the laminar flow aerosol reactor of McRae and his co-workers, fundamental studies of the chemical kinetics are more readily done using single microparticles or microdroplets. Design of an aerosol reactor requires knowledge of the reaction rates, for there must be a sufficient residence time of the reacting species in the reactor to complete the desired reaction.Matijević reviewed early work on preparing well-defined and very pure metal oxides by hydrolysis of alkoxide aerosol particles, and Ingebrethsen and co-workers studied the hydrolysis rates of aerosol droplets of aluminum and titanium alkoxides and mixtures of the two alkoxides. Following Matijevic and his colleagues, Okuyama et al. used the thermal decomposition of metal alkoxide vapors to produce ultrafine particles of the oxides of titanium, silicon, and aluminum. The preparation of polymeric aerosols has been studied by Partch et al. and by Ward et al. The latter investigators used single-particle techniques (the electrodynamic balance) to obtain polymerization rate data for the photochemical polymerization of acrylamide monomer microparticles.

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