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By S. Razavialavi

In the planning phase of every construction project, layout of temporary facilities is a crucial task; site layout can affect safety, travel cost and time, construction productivity, and space utilization. However, site layout planning can be a complicated problem, due to the interdependency of influencing factors. Although interaction among activities is one of the major drivers of site layout planning, it has not been properly addressed in past research. In this study, simulation is presented as a promising tool to address this gap. The capability of simulation technology to model complex processes in construction projects makes use of simulation tools in site layout optimization problems effective, while existing methods are unable to perfectly model these problems, in some cases. Additionally, the advantages and challenges of implementing simulation are assessed and a generic framework for simulation application in site layout planning is proposed.

Aug 1, 2013

By G Booth

Whilst communications systems in the mining industry have evolved over the years, the premise remains consistent that reliable communication is vital for safety and operational efficiency. TodayÆs open pit mines are benefiting from advanced developmental efforts based on mesh networking hardware and software technology. This paper highlights Rajant CorporationÆs adaptation of technology, originally developed for the defence and first responder industries, to provide wireless network connectivity in open pit mining applications. Featured is the large-scale deployment of over 300 mobile, meshing access points in the Bingham Canyon Copper mine near Salt Lake City, Utah, the worldÆs largest open pit copper mine. Many companies have positioned themselves, their technology and their product line in the arena of rugged outdoor wireless broadband mesh networking infrastructure. However, Rajant Corporation has combined specialised command and control software and portable networks which offer network extensibility and redundancy that are not available in any other networking solution. Rajant CorporationÆs BreadCrumb« offers unique traits in portability and non-line-of-site networking nodes which intelligently route and broadcast in standard 802.11 protocol. The advantage of RajantÆs solution is especially valuable for users needing equipment moved easily and rapidly into and out of the theatre of operations with uninterrupted network availability. The main differentiators that set the BreadCrumb« network apart from the competitors are mobility (continuous availability), simplicity, ability to properly load balance and power options. In 2007, RajantÆs BreadCrumb« wireless mesh system was selected by the Kennecott Utah Copper Corporation (KUCC), a wholly owned subsidiary of Rio Tinto, as its primary communications platform for operations within the Bingham Canyon Copper mine, the worldÆs largest open pit copper mine. The Rajant BreadCrumb« technology enables KUCC to gain additional operational efficiencies by tracking, monitoring and managing its copper mining operations. The primary goal of using the BreadCrumb« wireless mesh system Kennecott was to streamline its complex mining operations. KUCC required a high number of moving wireless nodes for improving mine monitoring and control. The Rajant InstaMesh« software running on the wireless BreadCrumb« units connects hundreds of devices to each other while rapidly transporting critical operational data. Kennecott has successfully implemented a large number of BreadCrumb« radios in an interconnected network that allows loader trucks, shovels, pumps, laptops and other production equipment to communicate with each other in real-time. These systems are a mix of secure access nodes that enable data and voice communications across a meshed, self-healing network for fleet dispatch, health monitoring and other critical mining applications. Many of the devices that require wireless communications are moving at all times throughout the wireless mining infrastructure. The BreadCrumb« nodes rapidly adapt to any changes in the network topology, assuring that IP traffic uptime and bandwidth are maximised. The installation layout and data network specifics, as well as maps and data network efficiencies will be detailed in the paper.

Jan 1, 2008

By J. Huisman

With the introduction of ever-stricter environmental operating guidelines, capital expenditure restrictions and operational budget cutbacks, the biological method of SO2 removal becomes more and more attractive. Biological treatment of dilute flue gases is a more cost effective technology in comparison to conventional sodium hydroxide scrubbing. Although the investment costs for sodium hydroxide scrubbing is lower, the operational costs are significantly higher. In addition, the end product of the biological installation is sulfur instead of sodium sulfate; and no further wastewater treatment of the bleed from the biological installation is required since heavy metals are removed simultaneously. Another option for the treatment of SO2 containing gas at a sulfuric acid plant is the production of extra sulfuric acid of the discharged SO2 by applying an additional converter. Comparing biological treatment with this option shows much lower investment costs for the biological installation. Sulfur is produced which can be converted to sulfuric acid, so the bio-route will be more cost-effective than an additional converter. In principle, the biotechnological gas cleaning system is an integration of an absorber with a wastewater treatment facility. In the absorber, the SO2 containing gas is brought into contact with the washing water. The effluent absorber liquid contains a mixture of sulfite and sulfate that is converted into elemental sulfur. This conversion takes place in an integrated system; first, the sulfite/sulfate mixture is converted anaerobically into sulfide; secondly, the sulfide is converted aerobically into elemental sulfur. Subsequently the sulfur is separated and the water is returned to the absorber. Due to the buffer capacity of the washing water, removal efficiencies over 98% are possible. In addition to SO2 removal, it is possible to convert for example other bleeds streams such as scrubber acid or weak acid to sulfur in the same SO2 installation. Recent evaluations concluded that biological desulphurization of flue gases is not only economically attractive in comparison to convention sodium hydroxide scrubbing but also in comparison to gypsum producing systems and even seawater scrubbers. This paper describes the technological and economical viability of biological flue gas desulphurization.

Jan 1, 2005

By D. Karpoff

"IntroductionUNTIL the recent discovery and development of deposits at Allard Lake, on the Lower Romaine river, practically the whole of Quebec's - and indeed of Canada's - production of ilmenite had come from deposits in the vicinity of St. Urbain, Charlevoix •county, a village about eight miles north of Bay St. Paul on the north shore of the St. Lawrence, some sixty miles below the city of Quebec (see Figure l) . Although these deposits were known nearly three hundred years ago and were worked in a small way during the years 1872-74, when a charcoal blast furnace was operated by the Canadian Titanic Iron Company for making white pig iron, it was not until 1908 that more or less continuous production commenced and has •continued to the present by the American Titanic Iron Company. The whole of the output has been exported to the United States.The ilmenite occurs in lenses •and dyke-like bodies within anorthosite. Production has come chiefly from three deposits: General Electric, Furnace, and East and West Coulombe. During 1951 -52, an extensive diamond drilling programme was carded out under the direction of the writer to test the Furnace and the East and West Coulombe deposits (Figures 2 and 3), which form part of the property of St. Lawrence Iron and Titanium Mines, Limited. The average tenor of the orebodies encountered in the course of the drilling was 38.60 per cent TiO2 and, in addition to these high-grade •bodies, there was found a very considerable tonnage of lower grade ore."

Jan 1, 1953

By Mary Cunningham

The EPA and DOE have collaborated on a series of studies to evaluate the effectiveness of treatment technologies at stabilizing bulk elemental mercury and wastes containing high concentrations (i.e., with greater than 260 mglkg total mercury) and multiple forms of mercury. The data from these treatment demonstrations are intended to help EPA to determine if regulatory revisions to allow a stabilization alternative for high-mercury subcategory wastes are warranted. In addition to mercury-contaminated wastes, the disposal of bulk elemental mercury is of concern because of the excess quantity of mercury in the Defense Logistics Agency (DLA) stockpile, as well as other potential sources of excess elemental mercury. The studies evaluated the effectiveness of several technologies at: I) stabilization of mercury in a "hard-to-treat" matrix; and 2) conversion of elemental mercury into a stable waste form for disposal. A surrogate waste was designed for the study on high-mercury wastes, which included an organic form of mercury, elemental mercury, and several mercury salts in an inorganic matrix. The surrogate waste and the bulk elemental mercury were treated by the vendors, and the treated waste forms evaluated for mercury Icachability, using both the TCLP and an automated, constant-pH leaching protocol. Constant pH leaching was conducted at pH 2,4,6,8 10 and 12 for 14 days at each pH. The leaching data demonstrate that the stability of the mercury in three treated waste forms varies widely across the pH range tested. Clearly, the stability of mercury in these treated waste forms will be highly dependant on the disposal conditions. The combination of site-specific disposal conditions and appropriate treatment technology must be considered as decisions are made about disposal of high-mercury wastes.

Jan 1, 2003

By Kadri Dagdelen

New underground coal mines have become increasingly expensive to open. A simple drift mine producing a raw coal product can cost as much as $50 million while a new shaft mine producing a washed coal product can cost up to $200 million. As a result, few if any speculative new mines are constructed. Normally, a long term coal supply agreement is needed to justify new mine projects. Negotiating a supply agreement prior to production start is difficult. Pricing must be based on estimated rather than historic costs and coal quality must be estimated from core hole samples versus actual shipments. Further in todays competitive coal markets, there is little margin for error in either price or quality.

Jan 1, 1983

By Matthew Thurley

Optimisation and control of comminution, pelletization, and agglomeration processes is a complex task with large potential for gains in productivity, energy efficiency, and particle size distribution quality. One factor in realising these gains is the requirement for fully-automated online particle size distribution measurement. Moreover, online particle size distribution measurement that is based on the particles on the visible surface and can avoid or mitigate substantial errors that result from under-sizing overlapped particles and over-sizing areas of fines particles. Literature review indicates a body of substantially 2D photographic based particle size measurement systems that suffer from a large number of significant errors except in the simplest case of a monolayer of particles under good illumination with limited color variation in the material. In order to measure the visible particles on a pile there are a number of requirements including; avoiding particle delineation errors due to variation in material color and shadows, detect overlapping versus non-overlapping particles, and identify areas of fine particles as fines and not large rocks. Results are presented using a fully-automated online measurement system of crushed rock on conveyor belt using a 3D surface laser profile. The system provides continuous online measurement and results are shown on over four hours of production after the primary crusher. Size distribution results are calculated using volumetric estimation of the particles on the surface of the pile. The results show a strong capability to discriminate size variation especially in the 10% and 20% passing values. Furthermore results show that if areas of fines are misclassified as large rocks, and overlapped particles misclassified as small rocks, then a near complete loss of discrimination occurs for the P10 and P20 values which become largely constant values.

Jan 1, 2014

By Daniel E. Collins

Massive banded Fe-Zn-Cu-Pb sulfide deposits in the Bagdad are associated with metamorphosed eugeosynclinal mafic volcanic and intrusives rocks Precambrian age. The geologic environment is very similar to that of the Jerome-Prescott area which lies 70 km. east of Bagdad. Mining of massive sulfides deposits began in 1917 on the Copper King mine in spite of its early discovery and the discovery of the Old Dick mine in 1882. The first shipments of zinc ore from the Copper King were hand sorted and averaged 46.89% Zn, 5.7 oz. Ag, 3.58% Pb and 1.68% Cu. Oxidized copper was first produced from the Old Dick mine in 1943~ In all, five deposits of massive sulfide ores have been mined in the Bagdad for a total production of nearly 2 million tons with an average grade of 12.0% Zn and 3.6% Cu. The largest deposit, the Bruce mine is currently closed because reduced metal prices and has produced a total of 823,000 tons of Zn-Cu ore to date. Mining of massive sulfide ore in the Bagdad area is presently idle. However, the potential for locating yet undiscovered ore bodies is good. Exploration for new ore bodies is difficult at best due to the complex geologic history of the area, the small size of individual ore bodies and lack of understanding as to the formation of massive sulfide deposits. The purpose of this investigation was to obtain a better understanding of the host rock formations through detailed geologic mapping, petrography and chemical analysis.

Jan 1, 1977

By Donald Deardorff

"Helical piles often rely on the final installation torque for ultimate capacity verification. When helical piles are designed using traditional bearing capacity equations for deep foundations and field monitored for a specified final installation torque, a factor of safety equal to 2 is often allowed for the design. One of the more common methods of determining torque during helical pile installation is by correlating the differential pressure across a hydraulic gear motor to a torque. Most drive head manufacturers provide multipliers to convert differential pressure to torque for different drive head models. These multipliers are based on theoretical torque equations and vary with the planetary gear ratio, hydraulic gear motor displacement and drive head efficiency. Drive head manufacturers show a linear fit between the differential pressure and output torque with no scaling effect. Previous drive head testing performed by the author has confirmed that the drive head differential pressure to torque relationship is generally linear however there is a scaling adjustment needed. This results in a variation of multipliers across the differential pressure range for a given drive head.Eight hydraulic drive heads from three manufacturers were field tested by Foundation Supportworks, Inc. to compare the torque versus differential pressure curves with varying installation equipment, hydraulic line sizes and hydraulic flow rates. Differential pressure was monitored using three methods including pressure gages, PT-Tracker and an Ashcroft AT-100. Flow and temperature was measured using a Webtech system analyzer. Torque was measured using a Pro-Dig in-line torque transducer, a TruTorque indicator and a Chance Mechanical Dial in-line torque indicator. The current testing indicates that a change in installation equipment and/or a change in hydraulic flow rate may affect the torque versus differential pressure curve of a given drive head. The results of this testing also show that some of the methods for determining torque during helical pile installations may be unconservative, thereby resulting in safety factors less than required."

Jan 1, 2017

By Limao Zhang

This paper presents a novel model to assess the risk of adjacent buildings in tunnelling environments based on Extended Cloud Model (ECM). ECM is an organic integration of Extension Theory (ET) and Cloud Model (CM), where ET is appropriately employed to flexibly expand the variable range from [0, 1] to (-8, +8), and CM is used to overcome the randomness and fuzziness during the gradation of evaluation factors. The risk level of a specific adjacent building is assessed by the correlation with the cloud models. A confidence indicator ? is proposed to illustrate the rationality and reliability of evaluating results. Ten buildings adjacent to Wuhan Metro Line Two (WMLT) are randomly chosen among hundreds of adjacent buildings for a case study. Results have proved to be consistent with the actual situation. Compared with other traditional evaluation methods, ECM has been verified to be a more competitive solution with high calculation accuracy, wide adaptability, as well as simplified computer programming. There are no stringent requirements on the quantity of training data during the modelling process, and the original data can be directly entered into ECM without a normalization procedure, avoiding the potential information loss. ECM can be offered as a decision support tool for the risk assessment in urban tunnelling construction and worth popularizing in other similar complicated projects.

Aug 1, 2013

By G. A. Brooks

Reactive ball milling has been proposed as a new route for producing carbides from oxides through carbothcrmic reduction. It is claimed that through milling oxide and graphite powders to the nanoscale, amorphous materials with very high reactivity are formed, that allows for easy transformation of the starting material to another in a subsequent thermal process. Thermodynamic analysis of this proposed process suggests that unless particle sizes are reduced to below 10nm, then reduction in size alone cannot explain a change in the stability of oxides. Even with nanometer scale powders, the products formed need to have a lower total surface energy than the reactants before a chemical change will occur. A model developed by Bhattacharya and Arzt for predicting localized temperature changes based on milling conditions suggest that temperarure rises less than 400 K will be achieved in laboratory conditions. The present calculations suggest that nanometer scale powders formed through high speed ball milling (>10 mls) may have undergone a process analogous to melting and quenching. Further work is required to fully distinguish these features.

Jan 1, 2003

By Sergey Dyachenko

"Following the adopted strategy for making the production modern, efficient and environmental friendly the Company completed a stage of the integrated program aimed at reconfiguration of its processing capacity.Upgrade of the Talnakh Concentrator with commissioning of two start-up facilities (SF) allowed an increase of 30% in its ore processing capacity up to 10 mtpa. In addition to a new high-tech equipment installed, a new concentration process was adopted offering the main advantage of 25-30% reduction of sulfides in concentrate. New concentration technology enabled the total amount of produced nickel concentrates (from Norilsk and Talnakh Concentrators) to be processed at upgraded smelting facilities of Nadezhda Metallurgical Plant and allowed decommissioning of smelting capacities of Nickel Plant resulting in emissions reduction by 30%.Nornickel plans to boost the capacity of Talnakh Concentrator to 18 mtpa by 2022, after commissioning of the 3rd SF. This will provide a shorter route for ores transportation from Talnakh mines along with improvement of cost/performance ratio of ore processing through the usage of the modern equipment and optimized concentration flow scheme. Total capacity of Talnakh Concentrator will be sufficient to process ores from Talnakh deposits with planned upstream assets development taken into account. Volume of ore mined from Norilsk deposits to be processed at Norilsk Concentrator will be also increased.Upgrading the crushing section at Kola MMC Concentrator in 2015 provided finer particles of the crushed ore, resulting in 6.6% increase in specific capacity of ore mills as well as 1% higher recovery of non-ferrous metals due to improved liberation of ore minerals.In 2015-2017 the Company was actively engaged in optimization of existing process flow schemes and parameters of Kola MMC, new high-performance reagents were adopted for concentration process, namely, collectors, depressors, flocculants. These measures allowed the Concentrator to reduce its annual operating unit costs and ensure sustainable production of concentrate with the lower grade of the incoming feedstock.Launched in October 2017, Bystrinsky GOK’s Concentrator was 3D designed and received a range of advanced technological solutions.All design process procedures and technologies rolled-out at the Company’s concentrators were developed by Russian R&D institutes, with the key role of Gipronickel Institute, R&D Service of Kola MMC and Polar Division's in-house Engineering Support Centre."

Jan 1, 2018

By Adrian C. Deneys, David G. C. Robertson

"Fluid flow phenomena on the surface of a molten slag have been documented using video photography in a laboratory scale D.C. arc furnace. The flow on the surface of the slag appeared to be electromagnetically influenced. This was confirmed by varying the position of the anode, which changed the direction of flow on the surface of the slag. Temperature measurements in the bath also confirmed the change in the directional nature of the fluid flow induced by the arc.During some periods, solids were fed into the arc attachment zone (AAZ) down the center of the hollow graphite electrode. Significant movement of the arc around the basal annular surface of the hollow electrode takes place. The point of attachment of an arc on a hollow electrode was more variable than an arc attached to a solid graphite electrode. Video images showed that the solids were rapidly incorporated into the bulk of the slag. Temperature measurements confirmed the existence of a superheated slag layer at the slag-gas interface, which allowed the solids to be rapidly incorporated into the melt.This work has been conducted to study fluid flow, temperatures, and solid behavior during feeding, in the arc attachment zone of a D.C. arc furnace. The work also has relevance to optimizing furnace design for pyrometallurgical slag cleaning processes."

Jan 1, 1999

By A M. Myrvang, B Nøst, N Q. Trinh, I S. B Bergh

The iron ore producer Rana Gruber AS is situated in northern Norway just below the Arctic Circle, and has been producing hematite and magnetite concentrates for more than 60 years. Since the late 1990s, the major part of the production comes from a sublevel stoping underground operation after many years of open pit mining. Despite moderate mining depth, the operations have experienced considerable rock stress problems due to quite high tectonic, horizontal stresses. To manage the problems, comprehensive rock mechanics investigations have been carried out by SINTEF, a major contract research organisation. This has included in situ rock stress measurements, laboratory investigations and numerical modelling. Based on this and practical experience, satisfactory design of vertical and horizontal pillars was achieved. At depth, the ore width increases from 30–40?m to more than 100?m. This, together with a major planned increase in production, called for a change of the mining method. After thorough investigations and considerations, it was decided to change to sublevel caving, very much like the LKAB system. The development of the new system has been closely followed up by rock mechanics measures, including 3D numerical modelling and comprehensive monitoring of deformations and rock stress changes. To achieve a satisfactory caving of the hanging wall, all vertical and horizontal pillars in the sublevel stoping area had to be removed. This has been a challenging task, and the development of the caving has been slow until recently. However, now the caving develops satisfactorily.CITATION:Bergh, I S B, Trinh, N Q, Myrvang, A M and Nøst, B, 2014. From sublevel stoping to sublevel caving at Rana Gruber, Norway – rock mechanical aspects, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 323–330 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By I. L. Feld

This Bureau of Mines report describes the development of a simple method of producing low-phosphorus hematite concentrates from certain submarginal southeastern iron ores. The investigation was undertaken to obtain additional information on the Clinton iron ore outcrops at the southwestern extremity of the Birmingham district of Alabama and to assist in the development of operating techniques that would make it profitable to use the marginal ores of this area for blast-furnace feed. Batch and continuous pilot-plant tests demonstrated that a relatively simple wet scrubbing treatment) followed by a desliming operation to reject argillaceous (clayey) gangue, consistently yielded a marketable granular hematite product. Iron losses were relatively high but could be tolerated in view of the low treatment cost.

Jan 1, 1960

By S. Lee, F. Campero

"Past heap leach design has evaluated hydrodynamic parameters based on a uniform particle size of heap material, but has ignored the equal importance of the instability of fine migration within heap stack in the beginning stages of the irrigation process. The proposed probabilistic model evaluates internal fine erosion and segregation potential of well-graded crushed ores by considering the entire particle size distribution shape and site compaction degree. Using this model, unsaturated flow model parameters were successfully evaluated based on synthesized soil-water characteristic curve (SWCC). Additionally, one-dimensional unsaturated transient flow modeling with Hydrus 1D® showed that the different recovery efficiencies of heap material under unsaturated flow patterns depending on the particle size distribution and compaction degree of heap material. Agglomeration preprocess employed by most heap leach sites can reduce the potential of fine erosion within heap material significantly, but internal stability of crushed ores and hydrodynamic-based analysis of heap material’s pore structure is equally important in the prescreening stage in order to improve efficiency of the heap leach and avoid a costly agglomeration process. INTRODUCTION Accurate estimation of heap leach recovery is a difficult task due to the variety of design parameters that need to be considered - such as geochemistry, hydro-dynamics, and geotechnical design aspects, most notably particle size distribution through the process of agglomeration. After agglomeration techniques were introduced to heap leach design, the influence of particle size distribution and compaction degree in enhanced heap leach recovery has been neglected. The main purpose of agglomeration is to prevent fine segregation and internal erosion during and after heap stacking for well graded crushed ores, which will eventually diminish heap reach recovery. Recent studies show that agglomerated heap materials that had been consolidated at 10 meters below heap surface can release the fines after contact time with lixiviant to the compacted heap material and produce poor drainage performance (Milczarek et al, 2013). It must be noted that engineers and practitioners should investigate feasibility of agglomeration benefit prior to heap leach design because the agglomeration process can incur up to 20 or 30% of project costs. Internal stability of stacked heap material is mainly governed by the particle size distribution of crushed ores. Depending on this stability, segregation and internal erosion of fines can be mitigated by the application of moderate compaction effort during heap construction. Investigation of segregation and internal erosion potential therefore takes precedence for well graded crushed ore since reaction time and contact area with lixivant are greater in finer ores."

Jan 1, 2016

By J. P. Messervey

Dr. K. A. Clark: No one will doubt the statement of fact that, during drilling operations through the bituminous sand beds in the Mildred-Ruth Lakes area, the core-barrel was found to contain bitumen with minor amounts of sand instead of bituminous sand. But many will doubt the interpretation of this fact as meaning that beds of bitumen occur interstratified with the bituminous sand beds. They will prefer to hold faith in the laws of physics, which deny that sand will float on oil or that fluid under pressure will not flow away through a permeable medium, until it is proved that the appearance of the oil in the core-barrel was not due to circumstances surrounding the drilling of the bituminous sand beds. The implication of the interpretation that sand is floating on oil is clear and it is unacceptable. Bituminous sand is unconsolidated sand more' or less saturated with a viscous oil. It is as difficult to conceive of bituminous sand lying on top of a body of the viscous oil as it is to conceive of unconsolidated sand more or less saturated with water lying on top of a body of water. The only difference between the two concepts is that the oil is viscous whereas the water is fluid. Oil-soaked sand placed on viscous oil would, when released, sink through the oil slowly, whereas water-soaked sand would sink through the water quickly.

Jan 1, 1947

By R. D. Cook, J. L. Johnson

"Measuring mud bed level in a sedimentation device is an important control variable. Methods used to date for this purpose have had limited success providing continuous, consistent measurements at a reasonable price. This paper describes a new instrument for detecting the mud bed / liquor interface as well as bed density profiles. The state of the bed is measured directly with sensors located in the thickener. Data from bench-scale and full-scale tests show that the bed level is well defined and easily detected. In addition, full-scale testing revealed unprecedented information about thickener beds. Variation in bed density gave new insight into thickener bed dynamics, providing design and control opportunities never before possible. This novel instrument can significantly improve thickener control by providing reliable and consistent bed level measurements. It is also capable of measuring bed density profiles that can potentially identify significant operating problems early enough to take corrective action before experiencing costly shut downs. INTRODUCTION Numerous studies and papers have been devoted to the subject of thickener design and operation to achieve specified throughput and discharge densities. Mathematical models have been developed that present methods for sizing thickeners and predicting performance under varying process conditions. The compression effect of deeper beds on dewatering performance is a recognized phenomenon (Wilhelm and Naide 1981). This is one variable of many that are inter-related and influence thickener performance. For example in the steady-state, continuous operation of a thickener, if the solids feed rate increases and the bed level remains the same, the underflow discharge rate must increase with the result of solids concentration being lower. The interactions of these parameters are at the heart of thickener models. One such model (Burger and Narvaez 2007), predicts solids concentration profiles increasing downward and discontinuities between settling zones. This model uses sediment height (bed level) as a parameter that influences capacity calculations to achieve the specified solids concentration of the underflow. Knowing the bed depth is critical to maintaining stable thickener operation. Implicit in these modeling strategies are some basic assumptions such as homogeneous distribution of solids in the different settling zones, plug flow of solids through the settling zones and steady state operation of the thickener. The accuracy of these assumptions has not been verified because there has been little visibility inside the bed of full size operating thickeners. Testing of the instrument presented in this paper demonstrates that it provides a degree of visibility of the dynamics in a thickener not previously possible and indicates that the basic assumptions of the modeling strategies may not be completely accurate."

Jan 1, 2015

By Brian Lightfoot

Ausmelt technology is a versatile bath smelting technology with application in many waste treatment fields at low capital and operating cost. Heavy metals extracted from wastes may be recycled to mainstream use and the slags produced will be inert and suitable for use as aggregate, shotblasting grit or other applications.

Jan 1, 1994

By N. N. Ngoepe

Positron Emission particle tracking (PEPT), which makes use of a radioactively labeled tracer particle, a positron camera and a tracking algorithm has been shown to be a viable method for studying flow properties in both the pulp and froth phases of flotation cells. Detailed velocity measurements of 300-400 µm glass beads were extracted to assess turbulence from velocity fluctuations in a micro flotation cell. The effects of particle speed and orientation at the instant of attachment events were studied. A minimum speed of 0.16 m/s was needed for a collision to lead to attachment. The most attachment events happen when the particle is directly in line with the inlet tube at 90o.

Sep 1, 2012