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By James A. Finch, Yue Hua Tan, Wei Zhang

"The paper is part of our study of the frother structure-property relationship using bubble rise velocity. Single bubble rise velocity profiles were determined in a 350 cm column for surfactants from the polypropylene glycol (PPG) family. Using velocity at 300 cm, the concentration to reach minimum velocity (CMV) is determined. The CMV is shown to decrease as alkyl chain length (n, number of carbons) increases and as the number of propylene oxide groups (m) increases. Linear correlations log CMV vs. n and m were observed. Taking literature data for critical coalescence concentration (CCC), linear log CMV vs. log CCC correlations were also noted. Mechanisms are briefly discussed, and prediction of CCC made for a commercial polypropylene glycol.INTRODUCTIONAs one of the great enabling technologies of the 20th century, froth flotation is a highly versatile method for physically separating minerals by exploiting differences in wettability (hydrophobicity). Over the last century, flotation reagents have undergone significant developments (Khoshdast and Sam, 2011). One important group of reagents is frothers which are used to reduce bubble size, slow bubble rise velocity and help stabilize froth (Klimpel and Isherwood, 1991).Frothers, originally derived from natural sources (e.g., pine oil and cresylic acid), are largely replaced today by synthetic products which provide more consistent properties. Polyglycols, based on PEO (polyethylene oxide), PPO (polypropylene oxide), or PBO (polybutylene oxide) groups, were first described by Leja and Nixon (1957) and have attracted wide use since then (Farrokhpay 2011). The chemical structure of polyglycols can be represented by a general formula: R(X)mOH, where R = H, or CnH2n+1 and X stands for EO (-C2H4O-), PO (-C3H6O-), or BO (-C4H8O-). The polypropylene glycol ethers (CnH2n+1(PO)mOH) are the most common of these reagents (Pugh, 2007) and the focus of this study.In general, the chemical structure of frother molecules comprises two parts, a non-polar hydrophobic hydrocarbon (alkyl: CnH2n+1) chain and a polar hydrophilic head. By introducing the ether -Olinkage, which acts as another polar site, the propoxy group (-OC3H6-) in the structure makes the frother readily soluble in water (Somasundaran and Wang, 2006), facilitating the industrial use of these frothers. Available as by-products, Dow Chemicals introduced as series of polyglycols, e.g., Dowfroth (DF) 200, 250, 263, and 1012, the most familiar being DF250 (CH3(PO)4OH), a polypropylene glycol methyl ether. While no longer available from Dow, these and other polyglycols are still widely used."

Jan 1, 2016

By Burrows. A.

Temperature profiles in the lead smelter sinter bed at Xstrata Zinc Mount Isa sinter plant have been measured using a wireless temperature probe. Corresponding sinter samples have been collected for characterization. The sinter peak bed temperatures were found to be in the range of 1000 - 1200 °C. Microstructures and softening temperatures of these sinters have been characterised. Strong correlations have been observed between peak bed temperature and peak hood temperature, and between mean sinter softening temperature and peak bed temperature. It was found that higher peak bed temperature results in higher sinter softening temperature. For the feed material used in the trials, to obtain sinters with mean softening temperatures above 1050 °C, peak bed temperatures above 1130 °C are required. There appears to be a direct correlation between granule size distribution in the feed and peak bed temperature attained. High peak bed temperatures are observed in sinters with narrow granule size distribution.

Jan 1, 2008

By A. Alfantazi, L. Choudhary

Gold leaching in thiosulfate solution has attracted widespread research interest through the last two decades primarily due to its perceived environmental benefits in comparison to the conventional gold cyanidation technique. However, the data on the corrosion and/or corrosion-induced failures of plant infrastructure materials in the solutions relevant to thiosulfate gold leaching are very limited. Accordingly, this study aims to characterize the electrochemical corrosion behavior of stainless steel 316L in the thiosulfate gold leaching solutions. Electrochemical corrosion response was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy. The morphology of corroded specimens was analyzed using scanning electron microscopy.

Jan 1, 2014

A study was made to determine the effect of increasing concentrations of dissolved oxygen on the floatability of galena pyrite and chalcopyrite. Adsorption, flotation and contact-angle tests were done in deoxygenated, in air-saturated and in oxygen-saturated solutions. The results showed that the adsorption of collector increased as the concentration of oxygen increased. Adsorption followed the exponential law r = kC'/"• Discontinuities in the curves were observed after the adsorption of several monolayers of collector. Although adsorption increased with increasing oxygen concentration, the floatability of the pyrite minerals did not increase, because oxidation had adverse effects on the floatability of these minerals. The floatability of galena was maximum in oxygen-saturated solutions, pyrite was depressed and chalcopyrite was also slightly depressed. Contact-angle tests proved that a bubble could not be attached to large flat surfaces in deoxygenated solutions, because sufficient surface free energy was not available for adhesion after the deformation of the bubble. In the presene of air, all the minerals yielded the same maximum angle of 72 degrees, characteristic of isopropyl xanthate.

Jan 1, 1970

By M. D. Gerst

The degree to which copper will continue to be in an integral part of the world economy in the future will depend largely on the dynamics of global economic development, the primary and secondary copper resource stock, technological change, and potential environmental constraints. We have characterized the copper cycle of 1994 for all of Earth's regions and for the planet itself (T. Graedel et al., Environmental Science & Technology, 38, 1242-1252, 2004) and recently updated that cycle to year 2000. In this paper, we compare various features of the 1994 and 2000 cycles. The three largest-using regions, Asia, Europe, and North America, all increased their absolute rate of copper use between 1994 and 2000, and all increased the per-capita rate of copper use as well. Globally, the use of copper increased by about 32%, from 11.7 to 15.3 million metric tons, while population increased by only 8%. Various changes are seen in scrap trade, finished products trade, and other parameters of the cycle. We conclude by considering how the rates of technological change and growth in demand, especially in Asia, may influence the copper cycle in the years ahead.

Jan 1, 2007

By A. F. Gregory

"AbstractA resumé of aerial radiation survey studies performed by and for Eldorado Mining and Refining, Limited, since 1943 is presented. Flight tests were initiated in 1947 and were followed .by intensified use and study of Geiger counters and other radiation detectors. Development of an aerial scintillation counter began in 1948, but •a sensitive large crystal unit was not available for exploration purposes until 1950. Modifications of this unit have been used in all subsequent surveys.For the Eldorado detector, several limiting conditions were established for successful radioactivity detection, the most important being that natural vein exposures can only be assuredly detected .at distances less than 150 feet. Sedimentary and pegmatitic radioactive occurrences can be detected at much greater distances. A helicopter investigation technique appears to •have •a useful prospecting potential.IntroductionAerial radiation surveys were first proposed in the early 1940's. However, it was not until 1949 that airborne detectors were extensively used in the search for radioactive minerals. Eldorado has flown about 50,000 miles of exploration flights, exclusive of tests, using a variety of •detectors and aircraft. Considerable data have •been gathered for .the evaluation of the several techniques employed. Much of the early work was performed with the co-operation of the National Research Council of Canada ( 1). More recent work was done in conjunction with the Commercial Products Division of Atomic Energy of Canada, Limited. The Development Department of this latter corporation designed and built the scintillation counter used in recent Eldorado surveys."

Jan 1, 1955

By P. Gautier

Current feedstock in the aluminum hot forging processes can be used in the cast or extruded forms. The microstructural variation between as-cast and extruded materials could result in different mechanical properties and corrosion resistance for hot-forged products. Corrosion performances were examined for forged parts produced by two AA6082 feedstocks at different conditions using the following corrosion tests: open circuit potential, anodic polarization, salt spray exposure and corrosion fatigue. With the help of optical and scanning electron microscopes, metallographical investigations were carried out on cast-forged and extruded-forged materials before and after corrosion. The corrosion behavior of both materials was compared in both as-forged and aged tempers. Results show that there is no significant difference in the corrosion performance for final cast-forged and extruded-forged products.

Jan 1, 2011

By Mike Robotham

Drum hoists in the 21st century have the same fundamental objective as their earliest 19th century counterpart. And yet a lot has changed in the design of the hoist from those early days of underground mining. These changes are driven by the need for greater productivity and reliability at ever increasing depths without compromising the all important safety demanded by the industry today. This paper reflects on how these changes have influenced design of a modern hoist Director of Engineering, Mike Robotham is a chartered engineer and has been with DavyMarkham for over 30 years. Having completed a craft apprenticeship he later joined the engineering department as a junior engineer. He has a wealth of experience of working on medium to large engineering projects in the field of mechanical, electrical and hydraulic equipment

May 1, 2013

By J. O. Wheeler

"DEFINITION OF THE REGION, ITS BOUNDARIES, AND PHYSICAL AND GE'OLOGICAL CHARACTERISTICSTHIS PAPER concerns the Western Cordilleran region, embracing most of British Columbia, the southern half of Yukon Territory and the southwestern most part of the District of MacKenzie. It excludes Vancouver Island and the Queen Charlotte Islands, which are discussed in a background paper on the Pacific Continental Shelf. The region is bounded on the south by the northwestern United States, on the west by the continental shelf and Alaska, on the north by the front of the Ogilvie Mountains, on the northeast by the axis of the MacKenzie Mountains and on the east by the Rocky Mountain Trench.The region is dominated by two mountain chains that con tain icefields and glaciers: the St. Elias, Coast and Cascade Mountains in the west; the Selwyn, Pelly, Cassiar, Omineca and Columbia Mountains in the east. The Intermontane region between these mountain chains consists of lower mountains and plateaus. In the mountains, the region above the timberline and many of the steep valley-walls provide good exposures of rock, but these areas are subject to rockslides and landslides and in winter to snow avalanches. Much of the Western Cordillera was covered by ice-sheets at various times during the Pleistocene epoch. Consequently, the larger valleys in the mountains and much of the Intermontane region contain much glacial drift and alluvium and only limited exposures of rock. This same terrain in the Southern Cordillera, however, is the most favourable for agriculture. Parts of the region, particularly in the two mountain chains, are heavily forested. Elsewhere, the forest cover is less, with grassland prevailing in the south and tundra in the north."

Jan 1, 1969

By J. A. Orr

The details connected with the mining and subsequent handling of Creighton ore were fully covered in a paper presented to the Institute in 1920. The following brief notes describe certain phases of the present practice and show wherein it differs from the practice at that time. These may be summarized under the following headings. (a) Recovery of pillars. (b) Drawing the ore. (c) Change from sub-level tramming to branch-raise system. (d) Chute construction. The present stoping practice is the same as formerly, i.e., fiat-backed shrinkage stopes of 60-foot width, between rib pillars of 15-foot width, extending from the footwall to the hanging-wall. Formerly, when these stopes were completed to the stopes above, they were drawn empty of broken ore, and the 15-foot rib pillars were caved into the stopes and drawn off through the same chutes as were used to draw the ore from the stopes.

Jan 1, 1926

By B. Burger, T. Bester, S. Deonarain, L. S. Schultz

"This paper details the process followed to raise drill and equip a 6.1 metre diameter vertical service shaft at Glencore’s Mindola Deeps project in Kitwe, Copperbelt Province, Zambia. The project scope comprises a shaft collar, bulk air intake, a pre-sink to -90 metres and raise drilling the shaft from surface to a final depth of 1,892 metres underground, in four separate lifts of approximately 475 metres each. Equipping of the shaft steelwork, headframe erection and commissioning the shaft for hoisting. In addition, the scope included the development of a decline down from 5430’ level underground to the new shaft position on 6205’ level. This paper will provide some insight into the successes and challenges encountered during execution of the shaft works to date and provide some learnings for future projects of a similar nature. INTRODUCTION The Mindola Mine is situated to the west of the city of Kitwe in the Copperbelt Province of the Republic of Zambia (Figure 1). The mine is owned and operated by Mopani Copper Mines Plc (MCM), whose shareholders are Glencore AG (73.1%), First Quantum (17.9%) and ZCCM Holdings Plc (10%).Productivity at the Mindola mine has been adversely affected because of significant ventilation and ore re-handling challenges, which are caused by the dilapidated infrastructure, and design of the existing vertical and sub vertical shaft system. In the circumstances, it was apparent that it was necessary to sink a new vertical shaft that would increase the volume of fresh air down the mine, improving the underground working environment and the current hoisting restrictions, resulting in an increase in productivity and efficiency. Because there were two existing levels ideally situated and perpendicular to one another and because a third level was in close proximity to that perpendicular and because the mine required a ramp down to shaft bottom in any event, consideration was given to raise drilling the shaft as opposed to using conventional blind sinking methodologies."

Jan 1, 2019

By J. Bardinas

"The use of autogenous mills has become widespread, owing to their capacity and favorable capital and operating costs. Optimal operation of these systems is critical, given their high energy consumption and effect on downstream processing. A considerable effort has been spent over the years in the development of advanced control systems to achieve a better performance in this regard. However, despite significant advances, the problem still remains challenging, owing to the nonlinear behaviour of the system with respect to the mill variables, and, the unmeasured ore variability come from the mine.The mill load, in particular, can be seen as a state variable of the mill, which could be important for; modelling and control, and, important insights into the mill behaviour. In this investigation, time series cluster analysis was performed using online mill load measurements in order to identify the different control states of the mill. More specifically, this time series was divided into short non-overlapping segments. A distance matrix was set up for each segment and the information was captured by means of textural features, similar to that used in multivariate image analysis. These wavelet and grey level cooccurrence matrix features could subsequently be used to rapidly identify the normal operating conditions from the feed disturbances in the mill.In principle, the methods and models presented here, once suitably validated and calibrated, could be used in online process monitoring of autogenous mills. They also could serve as a foundation for developing more advanced process control models."

Jan 1, 2016

By V. Bonilla-Sierra, M. Elmouttie, L. Scholtès, F. V. Donzé

In the presence of joint sets sub-parallel to a slope face, the stability of the rock mass is controlled by the shear strength of the joints. On one hand, if the joints are persistent their shear strength can be assessed according to Mohr-Coulomb criterion, assuming appropriate values for the cohesion and the friction angle on the joint surface. On the other hand, if the joints are non-persistent with their continuity being interrupted by the presence of rock bridges, their shear strength will increase considerably. In this latter case, the contribution of the rock bridges to the shear strength of the joint has to be accounted for in order to better assess the stability of the rock mass. A numerical analysis of the progressive failure of a rock slope involving a non-persistent joint has been set up based upon simulations performed using a Discrete Element Method (DEM) algorithm specifically enhanced for the modeling of jointed rock masses. Pre-existing discontinuities are explicitly accounted for in the model by using a modified contact logic that ensures an explicit and constitutive mechanical behavior of the joint planes. In addition, rock bridges can be spatially distributed along these joint planes following a prescribed probabilistic technique. Jennings’ formulation (Jennings, 1970) is considered as one of the first rock slope analysis that evaluates the shear resistance to sliding as a weighted combination of the shear resistance of the intact rock and the joint planes. The validity of this formulation is discussed in the present study. Contrary to the Jennings’ formulation, we show that tensile failure is an important mechanism, particularly as the dip angle of the sliding plane increases.

Jan 1, 2015

By Robert P. Harrison, Marie-Christine Patoinel, Kristian E. Waters

This paper describes a collaboration between McGill University and Hatch Ltd. to expose undergraduate students to real-world industrial projects. As part of the final-year design course, the students receive a detailed lecture on Scale-Up of New Technologies', including seven case studies drawn from over fifty years of full-scale industrial projects. The students are taught the basic concepts of scale-up, including the limits of pure theory and the need for empiricism. Insights from real scale-up failures and successes are fictionalized as Projects A, B, C, etc. The students are then asked to identify the guiding principles that can be distilled from these case studies.

Jan 1, 2011

By Anton Sizo, Alexey Klyashtorin

The Gunnar uranium mine operated from 1953 to 1961 on the shore of Lake Athabasca, in 1964 the site was abandoned, and the mine pit flooded. In 1981, the pit was found to be stratified with a chemocline at ~70 m by a sharp change in conductivity and TDS. The uranium concentration was ~700 μg/l on the surface, 320 μg/l at 50 m, and 2,900 μg/l at 110 m. The Ra-226 concentrations were 0.1, 0.06, 0.12, and 0.4 Bq/l. By 2017, the chemocline was ~60 m deep. The highest uranium concentration was 1150 μg/l and the lowest concentration (220 μg/l) was attributed to the chemocline. In the deeper column, the uranium content varied around 750 μg/l. The uranium distribution down the pit profile was aligned with DO, ORP, and TDS. Ra-226 averaged to ~0.4 Bq/l, Ra-226 and uranium profiles were inversely related with the respective maximum and minimum attributed to the chemocline. The uranium and radium amount accumulated in the pit by 2017 was 3,420 kg and 2,163 GBq, respectively. The uranium and radium apparent accumulation trend estimates to 64 kg/y and 41 MBq/y, respectively. A stable chemocline and no concentration gradients in the other parts of the pit suggest that the contaminants are unlikely to inflow from the bottom opening or outside the pit, but rather are mobilized from the pit walls. The contaminants are not in a steady state, and concentrations of both uranium and radium are likely to increase slowly in the future if no remediation occurs.

Jan 1, 2020

By Nigel Saunders, Zhanli Guo

"Quench sensitivity of heat-treatable aluminium alloys is closely related to the precipitation process taking place during quenching. Faster cooling results in less precipitation of coarse phases during cooling, leaving more solutes in the solution before ageing. An alloy in such state would be of greater hardening potential as larger amounts of hardening phases may precipitate out during ageing. Hence, to understand the quench sensitivity of an alloy, it is essential to understand its precipitation process. Precipitation is a diffusion-controlled process and the diffusion is made complicated by the so-called quenched-in vacancies. These vacancies form during solution treatment, become “excess” when temperature goes down, and annihilate during the following cooling and ageing treatments, making diffusion now a function of both temperature and time. This paper first investigates the formation and annihilation of quenched-in vacancies and their effect on diffusion. The diffusion affected by quenched-in vacancies is considered in the kinetic models to realise the calculation of TTT/CCT diagrams for aluminium alloys. The calculated CCT diagrams have been used to explain the observed quench sensitivity and age hardening behaviour of various commercial alloys. The transformation from GP zones to other hardening phases during ageing is also discussed.INTRODUCTION The heat treatment of aluminium alloys mainly consists of three stages: a solution treatment at an elevated temperature, quenching from this solution treatment temperature to room temperature, followed by an ageing treatment to allow the precipitation of strengthening phases(Davis, 1993).The following statements generally describes how quench sensitivity is observed in heat-treatable Al-alloys: faster cooling results in,(i) less precipitation of coarse phases formed at high temperature during cooling, (ii) more solutes kept in solution before ageing, and (iii) larger amounts of hardening phases being formed, i.e. a greater hardening potential. Thus, the quench sensitivity of an alloy is closely related to its precipitation kinetics."

Jan 1, 2018

By J. C. Li, Y. Zou, L. He

"The effect of rock joints is significant in characterizing dynamic behaviors of discontinuous rock masses. To reveal the relation between the transmission coefficient and the contact situation of the joint surface, an experimental study on stress wave propagation across an artificial rock joint was carried out using a modified Split Hopkinson Pressure Bar (SHPB) apparatus. All the bars and specimens were norite cored from the same site, and one surface of the specimen which contacted to the transmitted bar was sawn with a number of notches to simulate the artificial rough joint. According to a wave separation method, two strain gauges were mounted on each pressure bar at a specific spacing, then the incident, reflected and transmitted waves across the joints were obtained from the test data. It was found that the contact situation of the rock joint surface makes a different on the wave propagation. Finally comparisons of the transmission coefficients with different contact area ratios and different joint thicknesses were made respectively. The results show the effects of contact area ratio and thickness of joints on wave transmission.INTRODUCTIONJoints affect the dynamic mechanical behaviors of the rock masses significantly. When propagates across the rock masses, wave usually attenuates in amplitude and frequency due to the presence of the joint as a discontinuous interface in the rock masses. Rock joints are the main factor that affects the behaviors and properties of rock masses. Many researchers have focused on the mechanical properties of rock joints under quasi-static conditions. Nowadays, the effect of joint dynamic properties on wave propagation across rock masses is gradually taken into account in theoretical and numerical studies.The effective contact area, joint roughness, and properties of the asperities and filling materials have been found to influence the normal stiffness of joints (Bandis et al. 1983). As suggested by the International Society for Rock Mechanics (ISRM), the roughness of the discontinuities can be generally characterized by large-scale “waviness” and small-scale “unevenness” (Brown 1981). Many researchers focused on the roughness of rock joints that affects the mechanical properties of rock masses and wave propagation. For example, Brown and Scholz (1985, 1986) presented theoretically and verified experimentally a closure model of contact between two random nominally flat elastic surfaces, which showed that the joint closure property depended both on the surface topography and material properties. Pyrak-Nolte et al. (1997) presented the quantitative aperture data for three-dimensional interconnected fracture networks, which were imbedded in intact opaque rock samples several centimeters in length, using x-ray computerized tomographic (CT) imaging. Fardin et al. (2001) systematically investigated the effect of scale on the surface roughness of rock joints and concluded that samples should be equal to or larger than the stationary limit for surface roughness to be accurately characterized on a laboratory scale or in the field. Zhao et al. (2006) conducted excellent ultrasonic tests across intact cement mortar specimens, singlefracture specimens, and two-fracture specimens."

Jan 1, 2015

By J. Drenda

The model for methane removal from the workings directly behind an advancing longwall as presented in this paper may be used for U-ventilated cross or length-wise systems of longwall advance, starting from the boundaries of the extraction field. In mines with high methane concentrations, Uventilated longwall extraction from the boundary of the extraction field produces a methane risk. The risk is manifested by a higher methane concentration at the end of the longwall, upper gate and incline. The methane in increasing concentrations, which is emitted mainly from the workings with caved areas, appears towards the end of the longwall and in the upper gate. The graphical model of the longwall provided includes both the workspace of the longwall and the caved area. Based upon a model of the rock distribution in the cave, a ventilation model comprising two standard air splits and large number of crosswise air splits has been constructed. Simulations indicate that if the shearer is not present in the longwall, the air distribution in the caved area is symmetrical. The presence of the shearer, both at the bottom and the top of the longwall, causes an asymmetrical air distribution in the cave, that is the asymmetrical flows in the goaf and longwall workspace and in the inflows and outflow between those regions. This phenomenon causes an increase in methane concentration at the end of the wall and at the upper gate. The methane removal method proposed for workings with a caved area directly behind the advancing U-ventilated longwall, starting from the boundary of the field, consists of the removal of methane-air mixtures from the caved area with the boom pipes. These booms may be of several meters long and may be extended if necessary. The insertion of the boom pipes into the cave towards the end of the longwall and connecting them with the general methane removal system creates negative pressure causing a change in the depression field, which is the aerodynamic potential field in the goaf area around the ends of the boom pipes. This will promote the extraction of the methane-air mixture from voids and the goaf cracks, and the area from which methane is being extracted may extend to the side of the cave. This is a positive phenomenon, which could result in the methane flow from the goaf into the airflow in the longwall workspace decreasing or even stopping. A reduction in the methane flow into the longwall workspace with extractions booms will be advantageous for the production continuity. Based on the floor load model for the rocks in the cave and the methane-removal boom load model, the value of the force required to move the boom behind the advancing wall has been calculated. Strength calculations for the pipe were performed using a finite elements method. The analysis results, as well as the comparison of the pipe material effort to the strength parameters of steel, which can serve as piping material (for the assumed load conditions), lead to a belief that the proposed boom construction satisfies the strength requirements.

Aug 1, 2013

By A. Otsuki

"This paper discusses the primary collector adsorption onto a sulphide mineral in mixed collector systems to understand its adsorption mechanism. UV-vis measurements were performed to identify the primary collector concentration adsorbed on pyrite, and the adsorption kinetics under different conditions were compared to distinguish their difference between single and mixed collector systems. Small amount of secondary collector addition prior to the primary collector addition significantly improved the adsorption kinetics of primary one. The result was explained by the combination of two previously proposed mechanisms (i.e., different adsorption site mechanism and multi-layer product mechanism). This study showed UV-vis measurement as an effective tool to study mixed collector adsorption behaviour.INTRODUCTIONCollectors are surfactants composed of heteropolar molecules with a non-polar and a polar group (Lotter & Bradshaw, 2010). In a froth flotation process, the function of collector is to improve the hydrophobicity of target minerals and selectively float them with the aid of gas bubbles. Because of the chemical or physical attraction between the polar group and the mineral surfaces sites, collector molecules adsorb on the particle surface with the non-polar group assigned towards the bulk solution (i.e., water), thus the mineral particle surface becomes hydrophobic (Wills & Napier-Munn, 2006).Thiol collectors are major collectors widely used in sulphide mineral flotation. Potassium amyl xanthate (PAX), dithiocarbamate (DTC), dithiophosphate (DTP), mecaptobenzothiazole (MBT) are some common thiol collectors. Previous studies reported that some mixed collectors systems enhanced the flotation performance (e.g., Bradshaw, 1997; Bradshaw et al., 1998; Rao & Forssberg, 1997). Thiol collector mixtures are often used in the flotation of sulphide ores, and discussed with the synergistic benefits (Bradshaw et al., 1998) which include lowering the total collector dosage requirements, improving the sulphide recovery and the rate of flotation as well as the improving the froth characteristics. The current paper mainly considered the mixture between two thiol collectors (PAX and DTC, considered as a weaker and selective collector, and stronger and less selective collector, respectively (Bradshaw, 1997)) to further understand their adsorption mechanism that should assist in improving the flotation performance of refractory gold ore."

Jan 1, 2016

By F. Hassani, J. Peck, D. J. Lucifora

The performance of a rotary blasthole drill is heavily dependent on the material being drilled. This material is a microcosm of the in-situ geology that makes up the surface mine in which the rotary blasthole drill is deployed. The performance metrics that are influenced by the in-situ geology are penetration rate (distance drilled per unit time), rotary torque and to a lesser extent rotary speed and vibration. For simulation and testing purposes it is useful to have a validated plant model based upon the application of study. Once validated, a plant model can be used to perform simulation based testing as a supplement and possibly in place of more expensive and logistically complex field testing. Previous studies in the field of rock mechanics have supplied proven models that relate the performance of a rotary blasthole drill to the material being drilled for a given rock type with a given drill bit. In this study, field based experiments were conducted in an active surface mine on a working rotary blasthole drill and the corresponding monitoring while drilling (MWD) data was recorded. Data analysis was then performed on the collected field data. The techniques used successfully fit the collected MWD data to the previously proven rock mechanic models. This paper explores the theory relating rotary blasthole drill performance to the material being drilled, illustrates the required data collection and data analysis techniques, and demonstrates the ability of these techniques and the known rock mechanic models to provide a simulated plant model for the drilling process that can then be validated. This validation is also discussed.

Jan 1, 2015