scholarly journals Molybdenite Flotation in the Presence of a Polyacrylamide of Low Anionicity Subjected to Different Conditions of Mechanical Shearing

Minerals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 895
Author(s):  
Darwin Estrada ◽  
Luver Echeverry ◽  
Andres Ramirez ◽  
Leopoldo Gutierrez
Keyword(s):  
Electrophoretic Mobility ◽  
Intrinsic Viscosity ◽  
Induction Time ◽  
Aqueous Media ◽  
Mining Industry ◽  
Settling Rate ◽  
Depressing Effect ◽  
Induction Times ◽  
Mechanical Shearing ◽  
Different Levels

Polyacrylamides (PAM) are used as flocculants in the copper-molybdenum mining industry to improve the settling rate of flotation tailings. These types of reagents are recirculated to flotation in the water that is recovered from the thickeners, and as a result of this practice they can cause depression of flotation of some important minerals such as molybdenite. The objective of this work was to study the effect of a PAM of 11.9% of degree of anionicity on the flotation of molybdenite. The effect of the anionic PAM on molybdenite flotation was studied under different levels (three) of flocculant mechanical shearing. The flotation data was discussed along with intrinsic viscosity, adsorption, induction time, and electrophoretic mobility measurements. It was found that the non-sheared PAM (NS–PAM) had the strongest depressing effect on molybdenite flotation, followed by the moderately sheared PAM (MS–PAM). The depressing effect of the strongly sheared PAM (SS–PAM) was negligible. The flotation data correlated with the induction time measurements that showed that molybdenite became more hydrophilic in the presence of the NS–PAM. The SS–PAM has no effect on the induction times. Further work is ongoing to understand the effect of PAM on molybdenite flotation in the presence of clay minerals and different aqueous media.

scholarly journals Audit on induction time delays in operating room at Kibogora District Hospital: A quality improvement project

2021 ◽  
Vol 9 (2) ◽  
pp. 163-168
Author(s):  
Jean Claude Uwimana
Keyword(s):  
Operating Room ◽  
Induction Time ◽  
Time Delays ◽  
High Rate ◽  
Improvement Project ◽  
Study Results ◽  
Induction Times ◽  
Or Team ◽  
Causes Of Delays ◽  
Operating Unit

Background: Induction time delays in Operating room (OR) is an issue that affects the productivity of an operating unit especially in a setting with limited resources. It can also results in providing inappropriate services to the patients and their families. The aim of this study was to determine the causes of induction time delays and to propose solutions on how to avoid the reasons of delays. Methods: A prospective observational study was conducted. It focused on elective general surgeries and orthopedic surgeries as they were mainly being performed during the study period. The data on the type of operation, the type of anesthesia, delay or no delay of induction (DOI) of anesthesia, causes of DOI were collected. DOI was considered as the time between the previous patient out of the OR and the next one in of more than 30 minutes. Emergency surgeries and elective obstetric surgeries were excluded from the study. Results: 24.8% of surgeries were done after delays of induction of anesthesia as opposed to 75.2% surgeries for which anesthesia was induced without delay. 48.6% of delays of induction to anesthesia were due to the hospital issues followed by anesthesia provision related issues. (40.0%). The surgery related and patient related issues accounted each one 5.7%. Conclusions: There was a high rate of surgeries that had delays in induction times. The OR managers need to work more with the hospital administration and the OR team to correct causes of delays.

Dispersion Polymerization of Acrylamide and Acrylic Acid in Aqueous Media

2009 ◽  
Vol 87-88 ◽  
pp. 233-238
Author(s):  
Jiao Lu ◽  
Bo Peng ◽  
Ming Yuan Li ◽  
Mei Qin Lin
Keyword(s):  
Aqueous Solution ◽  
Molecular Weight ◽  
Acrylic Acid ◽  
Intrinsic Viscosity ◽  
Salt Concentration ◽  
Apparent Viscosity ◽  
Dispersion Polymerization ◽  
Aqueous Media ◽  
Salt Solutions ◽  
Aqueous Salt Solutions

Dispersion polymerization of acrylamide and acrylic acid was successfully carried out in aqueous salt solutions using anionic polyelectrolytes as stabilizers. The influences of aqueous solution of salt concentration, molecular weight and concentration of the stabilizers on the apparent viscosity and stability of the dispersions, and on the molecular weight of the polymers prepared were investigated. The results showed that stable dispersions could be obtained on condition that salt concentration was between 26%~30%, concentration of stabilizers between 8%~12%, and intrinsic viscosity of stabilizers between 2.977~3.740 dL/g. With salt concentration ranging from 26% to 30%, molecular weight of products increased first and then decreased. Molecular weight of products was hardly changed when concentration of stabilizer was between 8%~12%. When intrinsic viscosity of stabilizer was between 2.977~3.740 dL/g, increase of the molecular weight of stabilizer resulted in a decrease in the molecular weight of the products.

scholarly journals Standardization of 2-phenoxyethanol as anesthetic for juvenile Brycon cephalus (Gunther, 1869): the use in field procedures

2004 ◽  
Vol 34 (2) ◽  
pp. 563-565 ◽  
Author(s):  
Luis Antônio Kioshi Aoki Inoue ◽  
Cristiano dos Santos Neto ◽  
Gilberto Moraes
Keyword(s):  
Induction Time ◽  
Tropical Fish ◽  
Anesthesia Induction ◽  
Negative Factor ◽  
Different Levels

Hyper motility is a negative factor in fish handling procedures due to the risks of damages to the animals. Chemicals are widely used to anesthetize fish during biometry and many other handling procedures. 2-Phenoxyethanol is largely employed, but many studies are necessary about tropical fish responses. The present research evaluated the anesthesia induction time for juvenile matrinxã submitted to eight different levels of 2-phenoxyethanol. The range of 2-phenoxyethanol concentration was 250-600mg liter-1. Induction time of anesthesia decreased as a function of 2-phenoxyethanol concentrations. Fish were safely anesthetized approximately after one minute of exposure to 2-phenoxyethanol batches in concentrations above 400mg/liter, and the recover period was about one minute for all anesthetic concentrations. 2-Phenoxyethanol is a safe anesthetic for juvenile matrinxã even in exposures up to 600mg liter-1 being recommended for many field procedures of fish handling.

Mechanisms Underlying Foam-Based Electronucleation of Hydrates

2018 ◽  
Author(s):  
Palash V. Acharya ◽  
Denise Lin ◽  
Vaibhav Bahadur
Keyword(s):  
Induction Time ◽  
Metal Ion ◽  
Electrical Potential ◽  
Carbon Foam ◽  
Molar Ratio ◽  
Electrical Potential Difference ◽  
Carbon Foams ◽  
Voltage Dependent ◽  
Open Cell Foams ◽  
Induction Times

Nucleation of clathrate hydrates at low temperatures is constrained by very long induction (wait) times, which can range from hours to days. Electronucleation (application of an electrical potential difference across the hydrate forming solution) can significantly reduce the induction time. This work studies the use of porous open-cell foams of various materials as electronucleation electrodes. Experiments with tetrahydrofuran (THF) hydrates reveal that aluminum and carbon foam electrodes can enable voltage-dependent nucleation, with induction times dependent on the ionization tendency of the foam material. Furthermore, we observe a non-trivial dependence of the electronucleation parameters such as induction time and the recalescence temperature on the water:THF molar ratio. This study further corroborates previously developed hypotheses which associated rapid hydrate nucleation with the formation of metal-ion coordination compounds. Overall, this work studies various aspects of electronucleation with aluminum and carbon foams.

Depressing Effect of Rumen Distension on Silage Intake of the Lactating Dairy Cow

1988 ◽  
Vol 1988 ◽  
pp. 82-82
Author(s):  
J.N. Mbanya ◽  
M.H. Anil ◽  
J.M. Forbes
Keyword(s):  
Latin Square ◽  
Depressing Effect ◽  
Lactating Cows ◽  
Lactating Dairy Cows ◽  
Preliminary Study ◽  
Voluntary Intake ◽  
Daily Milk Yield ◽  
Different Levels ◽  
Daily Milk ◽  
Friesian Cows

The numerous factors involved in the control of food intake by ruminants have been reviewed in detail (Baile and Forbes, 1974.). Distension of the rumen is thought to limit the voluntary intake of hay by dry cows (Campling and Balch, 1961) and by lactating cows (Mbanya, Anil and Forbes, 1987). In more recent reports, it is thought that some of these factors which are negative feedback signals combine additively in their effects to induce satiety (Forbes, 1986). Prior to investigating the additive effects of rumen distension to those of other feedback signals on intake of silage by lactating dairy cows, we carried out a preliminary study now reported to establish a response curve to different levels of distension which will enable an appropriate degree of distension to be imposed in future experiments involving combinations of treatments.Animals and Housing - Five rumen fistulated, non-pregnant Friesian cows in early lactation (mean daily milk yield, 25.2 kg) were used in a 5 x 5 Latin square design with a row omitted.

Induction Time Studies of Fe18Cr and 430 SS under Open Circuit Conditions in Chloride-Containing Sulfuric Acid

CORROSION ◽  
1984 ◽  
Vol 40 (4) ◽  
pp. 140-146 ◽  
Author(s):  
B. S. Covino ◽  
M. Rosen
Keyword(s):  
Induction Time ◽  
Chloride Ion ◽  
Open Circuit ◽  
Chloride Ions ◽  
Ion Concentration ◽  
Short Film ◽  
Corrosion Resistant ◽  
Passive Behavior ◽  
Induction Times ◽  
Aisi 430

Abstract In order to promote the effective and efficient application of corrosion resistant metals and alloys in mineral processing environments, the Bureau of Mines, U.S. Department of the Interior, has characterized the effect of aggressive ions on the corrosion and passive behavior of two stainless steels, Fe18Cr and AISI 430 SS. Samples prepassivated in oxygen saturated 1 N H2SO4 at 0.6 V NHE and then released to open circuit and aged for times ranging from 10 min to 80,000 min (55 days), were subsequently exposed to chloride ion concentrations ranging from 5 to 44 parts per thousand (ppt). Susceptibility to chloride ion attack was determined as a function of time in solution (film aging time), chloride ion concentration [Cl−], and open circuit potentials (E) at the time chloride was added by measuring the amount of time (induction time, t) required for a sample to begin corroding after adding the chloride ion. The experimentally determined induction times were fitted to an equation of the form: 1/t=K Em[Cl−]n where K, m, and n are empirically determined constants. Results obtained for short (<100 min) aging times were different from those for long (100 to 80,000 min) aging times. For Fe18Cr exposed for short film aging times prior to addition of the chloride, larger [Cl−] resulted in shorter induction times, and higher values of E resulted in longer induction times. For 430 SS exposed for short film aging times, and for 430 SS and Fe18Cr exposed for longer film aging times prior to addition of chloride ions, both larger [Cl−] and higher values of E resulted in shorter induction times.

Diffuse pollution associated with the mining sectors in South Africa: a first-order assessment

2007 ◽  
Vol 55 (3) ◽  
pp. 9-16 ◽  
Author(s):  
S.E. Coetser ◽  
R.G.M. Heath ◽  
N. Ndombe
Keyword(s):  
Water Pollution ◽  
South Africa ◽  
Water Quality ◽  
Mining Industry ◽  
Source Water ◽  
Diffuse Source ◽  
Levels Of Detail ◽  
Available Information ◽  
Different Levels ◽  
Receiving Water

Internationally it has become recognised that diffuse source water pollution from mining activities severely affects the degradation of water quality especially with regards to acidification and metal loading. South Africa is facing major problems with regard to the management and treatment of contaminated mine water. Very little has been published for South Africa about the quantities and qualities of diffuse source water pollution by the mining industry. Furthermore the available information has not yet been compiled into a consolidated overview that presents the total picture. Some of the problems that limit the use of the available information and would necessitate further processing to normalise the data, derive from the fact that the investigations producing the information were done at different times, to different levels of detail and using different approaches. A further complicating factor is that data for some mining commodities may not be available and may necessitate further investigation. The overview of the quantities and qualities of non-point source effluent production by different sectors needs to be interpreted in terms of the effect the effluent can be expected to have on receiving water quality (both surface and groundwater). It would thus be necessary to categorise waste types according to their effect on water quality and synthesise the data to obtain an estimate of the threat that different sectors and sub-sectors pose to receiving water quality.

scholarly journals Developing an integrated model for quelling illegal mining in South Africa

2017 ◽  
Author(s):  
Mbekezeli Comfort Mkhize
Keyword(s):  
South Africa ◽  
South African ◽  
Mining Industry ◽  
Integrated Model ◽  
Mining Activities ◽  
Significant Contributor ◽  
Illegal Mining ◽  
Theoretical Perspectives ◽  
Collaborative Efforts ◽  
Different Levels

Despite being recognised as a significant contributor in the South African economy, the mining industry is riddled with illegal mining activities. Though it remains difficult to precisely measure the extent of the activities in financial terms, it is estimated that more than R72 Billion have been lost. Lack of research on illegal mining partly compounds the problem. In view of this knowledge-gap, this article argues that whilst there is a multiplicity of stakeholders who deal directly with unlawful activities, poor integration of capacities at different levels remain discernible. The article assesses available literature and employs two theoretical perspectives as lenses through which to view the underlying reasons and the measures that can be put in place to quell illegal mining. The article concludes that an integrated model needs to be put in place in order to quell illegal mining in South Africa. The article recommends that the resources need to be pulled together and collaborative efforts need to be enhanced at all levels.

scholarly journals The Determinants of Mergers & Acquisitions in a Resource-Based Industry: What Role for Environmental Sustainability?

2016 ◽  
Vol 7 (2) ◽  
pp. 111-134
Author(s):  
Roberto Leon-Gonzalez ◽  
Lise Tole
Keyword(s):  
Environmental Sustainability ◽  
Mining Industry ◽  
Multinomial Logit Model ◽  
Random Parameters ◽  
Data Set ◽  
Aggregate Investment ◽  
The Relationship ◽  
Investment Choices ◽  
Different Levels ◽  
Pollution Havens

This paper examines the relationship between environmental stringency and mergers and acquisitions (M&A) activity in a highly polluting, resource-based industry. Specifically, it seeks to determine whether buyers are targeting countries with the same or different levels of environmental stringency than in their own country, i.e. whether pollution havens exist in the global mining industry. Rather than aggregate investment, which has been used by most previous studies, we analyze a dataset of individual investment choices. We model the choice of country and the amount invested jointly as the two variables are likely to be correlated. The choice of country is modeled using a random parameters multinomial Logit model. We use a hitherto unanalyzed data set of the value paid for all completed M&A in the mining industry worldwide between 1994 and 2006. We find no evidence of pollution havens in this industry. If anything, buyers from countries with high levels of environmental stringency are more likely to invest in countries with a similar level of environmental stringency and make larger investments in them than in less environmentally stringent countries.

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