東華大學圖書館 |

Conductivity Measurements of the Froth in Flotation.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Conductivity Measurements of the Froth in Flotation./
作者:	Lepage, Mark R.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2023,
面頁冊數:	482 p.
附註:	Source: Dissertations Abstracts International, Volume: 85-05, Section: B.
Contained By:	Dissertations Abstracts International85-05B.
標題:	Software. -
電子資源:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30718521
ISBN:	9798380707855

Conductivity Measurements of the Froth in Flotation.
Lepage, Mark R.

Conductivity Measurements of the Froth in Flotation. - Ann Arbor : ProQuest Dissertations & Theses, 2023 - 482 p.

Source: Dissertations Abstracts International, Volume: 85-05, Section: B.

Thesis (Ph.D.)--McGill University (Canada), 2023.

The froth zone plays an important role in the recovery and grade of flotation operations by acting as an intermediate between the collection zone and concentrate launder. The main roles of the froth zone are to transport collected particles from the collection zone to the concentrate launder (affecting the concentrate recovery), and to upgrade the concentrate by allowing the drainage of water within the froth containing entrained gangue material (affecting the concentrate grade). As bubble-particle aggregates rise from the collection zone to the froth, water also transports entrained material. This process of entrainment is non-selective and negatively affects concentrate grade. The water carried by the froth, thus, presents itself as an interesting metric to monitor to quantify water overflow). It was determined that for a given set of operating conditions, the normalized (to the froth equilibrium height) water content profiles were similar, regardless of the achieved froth height. It was also determined that changing the input air rate and changing the frother concentration produced markedly different water content profiles, characterized mainly by the large differences in the water content in the froth just above the collection/froth zone interface.the performance of flotation froths. The use of electrical conductivity has been used to quantify the relative phase fractions in dispersions (akin to the froth zone), however little literature exists for the application in quantifying the froth zone in flotation.This thesis examines the development and application of a conductivity sensor to quantify the volumetric water content fraction in the froth zone in flotation. In specific, a conductivity sensor was applied to measure the top of froth water content, then, through the utilization of numerical simulations of the electric field produced by axial ring conductivity electrodes, a conductivity profiling sensor was developed and applied to measure the vertical water content profiles of flotation froths.The measurement of the top of froth water content was performed in two (air-liquid) and three (air-liquid-mineral) phase systems. The results showed that for a given input air rate, a strong correlation between the measured top of froth water content and the recovered water overflow rate, a metric often used in laboratory experiments to infer recovery through entrainment, exists. Under changing input air rates, the top of froth water content measurement cannot account for increases in volumetric froth recovery, expected to be largely affected by changing input air rates. To account for this, an investigation into the use of a preliminary froth camera (to track volumetric froth recovery) in conjunction with the top of froth water content measurement was performed to directly infer the water overflow rate and, with knowledge of the systems entrainment factor, the recovery through entrainment.Numerical simulations of bulk conductivity measurements revealed a strong dependency of electric field uniformity on measurement bias towards the outer edge of the measurement volume using axial ring conductivity electrodes. A quantification technique was developed, termed the Effective Measurement Volume (EMV) which was used to quantify the radial uniformity of the current density produced within the measurement volume of a given electrode geometry. Using simulated and experimentally emulated annular flow conditions, which produced a large radial change in conductivity, the effect of the measurement bias on the resulting bulk conductivity (used to predict the relative phase fractions) was investigated. Electrode geometries with low EMV values produced large error in phase fraction estimation, while electrode geometries with EMV values approaching 1.0 (approaching a uniform electric field), approached no error in phase fraction estimation. The EMV was used to investigate the effect of electrode width, separation, and diameter. It was determined that an electrode separation-to-diameter ratio should be no less than 1.0, which produced an EMV value of ~ 0.97. Understanding the theoretical limitations of the electrode geometries, a four-electrode method conductivity method was proposed to measure the conductivity profile of the froth zone.Using the insights gained from the bulk conductivity measurement simulations, a conductivity profiling system was developed using 32 separate electrodes, providing a vertical measurement resolution of 1 cm. A hardware and software system was developed, termed McGill FrothSightto control conductivity profiling measurements. The system was applied to investigate the water content profiles of two-phase flotation froths operated at the froth equilibrium height (without water overflow). It was determined that for a given set of operating conditions, the normalized (to the froth equilibrium height) water content profiles were similar, regardless of the achieved froth height. It was also determined that changing the input air rate and changing the frother concentration produced markedly different water content profiles, characterized mainly by the large differences in the water content in the froth just above the collection/froth zone interface.

ISBN: 9798380707855Subjects--Topical Terms:

619355
Software.

Conductivity Measurements of the Froth in Flotation.
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502 $a Thesis (Ph.D.)--McGill University (Canada), 2023.
520 $a The froth zone plays an important role in the recovery and grade of flotation operations by acting as an intermediate between the collection zone and concentrate launder. The main roles of the froth zone are to transport collected particles from the collection zone to the concentrate launder (affecting the concentrate recovery), and to upgrade the concentrate by allowing the drainage of water within the froth containing entrained gangue material (affecting the concentrate grade). As bubble-particle aggregates rise from the collection zone to the froth, water also transports entrained material. This process of entrainment is non-selective and negatively affects concentrate grade. The water carried by the froth, thus, presents itself as an interesting metric to monitor to quantify water overflow). It was determined that for a given set of operating conditions, the normalized (to the froth equilibrium height) water content profiles were similar, regardless of the achieved froth height. It was also determined that changing the input air rate and changing the frother concentration produced markedly different water content profiles, characterized mainly by the large differences in the water content in the froth just above the collection/froth zone interface.the performance of flotation froths. The use of electrical conductivity has been used to quantify the relative phase fractions in dispersions (akin to the froth zone), however little literature exists for the application in quantifying the froth zone in flotation.This thesis examines the development and application of a conductivity sensor to quantify the volumetric water content fraction in the froth zone in flotation. In specific, a conductivity sensor was applied to measure the top of froth water content, then, through the utilization of numerical simulations of the electric field produced by axial ring conductivity electrodes, a conductivity profiling sensor was developed and applied to measure the vertical water content profiles of flotation froths.The measurement of the top of froth water content was performed in two (air-liquid) and three (air-liquid-mineral) phase systems. The results showed that for a given input air rate, a strong correlation between the measured top of froth water content and the recovered water overflow rate, a metric often used in laboratory experiments to infer recovery through entrainment, exists. Under changing input air rates, the top of froth water content measurement cannot account for increases in volumetric froth recovery, expected to be largely affected by changing input air rates. To account for this, an investigation into the use of a preliminary froth camera (to track volumetric froth recovery) in conjunction with the top of froth water content measurement was performed to directly infer the water overflow rate and, with knowledge of the systems entrainment factor, the recovery through entrainment.Numerical simulations of bulk conductivity measurements revealed a strong dependency of electric field uniformity on measurement bias towards the outer edge of the measurement volume using axial ring conductivity electrodes. A quantification technique was developed, termed the Effective Measurement Volume (EMV) which was used to quantify the radial uniformity of the current density produced within the measurement volume of a given electrode geometry. Using simulated and experimentally emulated annular flow conditions, which produced a large radial change in conductivity, the effect of the measurement bias on the resulting bulk conductivity (used to predict the relative phase fractions) was investigated. Electrode geometries with low EMV values produced large error in phase fraction estimation, while electrode geometries with EMV values approaching 1.0 (approaching a uniform electric field), approached no error in phase fraction estimation. The EMV was used to investigate the effect of electrode width, separation, and diameter. It was determined that an electrode separation-to-diameter ratio should be no less than 1.0, which produced an EMV value of ~ 0.97. Understanding the theoretical limitations of the electrode geometries, a four-electrode method conductivity method was proposed to measure the conductivity profile of the froth zone.Using the insights gained from the bulk conductivity measurement simulations, a conductivity profiling system was developed using 32 separate electrodes, providing a vertical measurement resolution of 1 cm. A hardware and software system was developed, termed McGill FrothSightto control conductivity profiling measurements. The system was applied to investigate the water content profiles of two-phase flotation froths operated at the froth equilibrium height (without water overflow). It was determined that for a given set of operating conditions, the normalized (to the froth equilibrium height) water content profiles were similar, regardless of the achieved froth height. It was also determined that changing the input air rate and changing the frother concentration produced markedly different water content profiles, characterized mainly by the large differences in the water content in the froth just above the collection/froth zone interface.
520 $a La zone de mousse joue un role important dans la recuperation et la qualite des operations de flottaison en agissant comme intermediaire entre la zone de collecte et le lanceur de concentres. Les roles principaux de la zone de mousse sont de transporter les particules recueillies de la zone de collecte au blanchisseur de concentre (affectant la recuperation de concentre), et d'ameliorer le concentre en permettant le drainage de l'eau dans la mousse contenant le materiel de gangue entraine (affectant la teneur en concentres). Comme les agregats de particules de bulle montent de la zone de collecte a la mousse, l'eau transporte egalement le materiel entraine. Ce processus d'entrainement est non selectif et affecte negativement la qualite du concentre. L'eau portee par la mousse se presente donc comme une metrique interessante a surveiller pour quantifier la performance des mousses de flottation. L'utilisation de la conductivite electrique a ete utilisee pour quantifier les fractions de phase relatives dans les dispersions (semblables a la zone de mousse), cependant peu de litterature existe pour l'application dans la quantification de la zone de mousse dans la flottation.Cette these examine le developpement et l'application d'un capteur de conductivite pour quantifier la fraction volumetrique de la teneur en eau dans la zone de mousse en flottation. En particulier, un capteur de conductivite a ete applique pour mesurer la teneur superieure en eau de mousse, puis, grace a l'utilisation de simulations numeriques du champ electrique produit par des electrodes de conductivite anneaux axiaux, un capteur de profilage de conductivite a ete developpe et applique pour mesurer les profils verticaux de la teneur en eau des mousses de flottation.La mesure de la teneur superieure en eau de mousse a ete effectuee dans deux systemes (airliquide) et trois systemes (air-liquide-mineral). Les resultats ont montre que pour un debit d'air d'entree donne, il existe une forte correlation entre la teneur maximale mesuree en eau de mousse et le taux de debordement de l'eau recuperee, une mesure souvent utilisee dans les experiences en laboratoire pour deduire la recuperation par entrainement. En ce qui concerne les taux d'entree d'air changeants, le sommet de la mesure de la teneur en eau de la mousse ne peut pas tenir compte de l'augmentation de la recuperation volumetrique de la mousse, qui devrait etre largement influencee par la variation des taux d'entree d'air. Pour tenir compte de cela, une enquete sur l'utilisation d'une camera utilisee pour surveiller la mousse (pour suivre la recuperation volumetrique de mousse) en conjonction avec la mesure de la teneur en eau de mousse superieure a ete effectuee pour deduire directement le taux de debordement d'eau et avec connaissance du facteur d'entrainement des systemes, la recuperation par entrainement.Des simulations numeriques de mesures de conductivite en vrac ont revele une forte dependance de l'uniformite du champ electrique sur le biais de mesure vers le bord exterieur du volume de mesure a l'aide d'electrodes de conductivite axiale annulaire. Une technique de quantification a ete developpee, appelee volume de mesure efficace (EMV) qui a ete utilisee pour quantifier l'uniformite radiale de la densite de courant produite dans le volume de mesure d'une geometrie d'electrode donnee. En utilisant des conditions d'ecoulement annulaire simulees et experimentalement emulees, qui ont produit un grand changement radial de la conductivite, l'effet du biais de mesure sur la conductivite globale resultante (utilisee pour predire les fractions de phase relatives) a ete etudie. Les geometries d'electrodes avec des valeurs VME faibles ont produit une grande erreur dans l'estimation de la fraction de phase, tandis que les geometries d'electrodes avec des valeurs VME approchant 1,0 (approchant un champ electrique uniforme), n'ont approche aucune erreur dans l'estimation de la fraction de phase. Le VME a ete utilise pour etudier l'effet de la largeur, de la separation et du diametre des electrodes. Il a ete determine qu'un rapport de separation des electrodes par rapport au diametre ne devrait pas etre inferieur a 1,0, ce qui a produit une valeur VME de 0,97. Pour comprendre les limites theoriques des geometries des electrodes, une methode de conductivite a quatre electrodes a ete proposee pour mesurer le profil de conductivite de la zone de mousse.Un systeme de profilage de conductivite a ete developpe a partir des resultats des simulations de mesure de conductivite en vrac, offrant une resolution de mesure verticale de 1 cm. Un systeme materiel et logiciel, appele McGill FrothSight,a ete developpe pour controler les mesures de profilage de conductivite. Le systeme a ete applique pour etudier les profils de la teneur en eau des mousses de flottation biphasees utilisees a la hauteur d'equilibre de la mousse (sans debordement d'eau). Il a ete determine que, pour un ensemble donne de conditions d'exploitation, les profils de teneur en eau normalises (a la hauteur d'equilibre de la mousse) etaient semblables, peu importe la hauteur de mousse atteinte. Il a egalement ete determine que le changement du debit d'air d'entree et la modification de la concentration des mousses produisaient des profils de teneur en eau sensiblement differente, caracterisee principalement par les grandes differences dans la teneur en eau de la mousse juste en haut de l'interface de la zone de collecte/zone de mousse.
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