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By D. W. Fuerstenau

In mineral processing, the last century of the current millenium has been the century of froth flotation. The process did not result from fundamental research, but was developed over the years by empirical methods. In more recent years, our understanding of the fundamental principles of the flotation process have made significant strides. This paper reviews some of the historical perspectives of developments in flotation reagents, the development and application of experimental tools for delineating flotability and interfactial phenomena, advances in flotation fundamentals, and the development of flotation kinetics, both macroscopic and microscopic subprocesses. Through the application of surface chemistry, the flotation process has permitted economic utilization of a vast array of complex ores.

Jan 1, 1999

By V. R. Degner

Given: the process tonnage, performance objectives, and plant floor area, the paper will outline the metallurgical and machine hydrodynamic scale-up procedures for translating the lab flotation test results to the design of a full size flotation machine installation, including the machine number, size, and arrangement. Machine selection considerations for rougher, scavenger and cleaner duty, and special considerations relative to specific applications, will be summarized where appropriate. The value of kinetic modeling in quantitative metallurgical (lab to full size machine) scale-up will be reviewed considering a coal installation, and design information for additional applications such as copper, molybdenum, iron, phosphate, and potash will be discussed.

Jan 1, 1986

Surface characterization techniques, i.e. contact angle measurement, atomic force microscopy (AFM) surface force and surface imaging measurement, were applied to investigate the molybdenite surface in aqueous solution. It was shown that the cleaved basal surface of molybdenite was very hydrophobic with a 92 degree water contact angle. The non-polar component of the solid surface free energy is 50.52 mJ/m2 while the polar components are almost zero. The solid surface was not reactive and was only weakly charged at the pH 6. When the aqueous media changes from water to 1×10-4 M KEX solution, the measured contact angle, adhesion force and surface roughness all increase slightly. However, ethanol rinsing made the surface change back to the bare substrate. It was suggested that the hydrophobic chemical, i.e. dixanthogen, which was shown in the morphology of patches by the AFM image, physically adsorbed on the hydrophobic molybdenite surface through the hydrophobic interaction.

Jan 1, 2009

By J. Brent Hiskey

INTRODUCTION Metal electrodeposition processes are of fundamental technological importance to a number of fields. Electrorefining, electrowinning, electroplating, and electrogalvanizing have all been the subject of intense study for over a century. More recently, electrochem- ical deposition has played a critical role in advances in microelectronics and lately has been an enabling technology for the production of certain nanostructured materials. Electrometallurgists have most frequently been concerned with the structure and morphology of massive deposits. For example, in metal recovery steps such as electrorefining and electrowinning, deposits demonstrating adherent coarse-grained characteristics are most desirable. In the case of electroplating, a bright fine-grained, tenacious and strongly adherent deposit is required. The fabrication of microelectronic devices and the production of nanoscale structures such as nanoparticles, nanowires, and nanorods requires a keen understanding of early stage deposition effects. The initial stages of metal deposition, usually referred to as electroclystallization, are fundamentally linked to nucleation and growth phenomena. Early stage deposits are typically very ordered. Whereas, bulk metal deposition structures are much more ran- dom. In both cases, the discharge of a metal ion at an electrified interface is represented by simple cathodic reduction as follows: [ ] Me(H2O)xn[ ] is a hydrated metal ion residing in the bulk solution and Me is the metal atom occupying a crystallographic lattice position. A similar reduction reaction can be

Jan 1, 2005

By Michael Fehler, Hidenshi Kaieda, Leigh House

Hydraulic fracturing has gained in popularity in recent years as a way to determine the orientations and magnitudes of tectonic stresses. By augmenting conventional hydraulic fracturing measurements with detection and mapping of the microearthquakes induced by fracturing, we can supplement and independent1 y confirm information obtained from conventional analysis. Important information obtained from seismic monitoring includes: the state of stress of the rock, orientation and spacing of the major joint sets, and measurements of rock elastic parameters at locations distant from the wellbore. While conventional we1l 1ogging operations can provide information about several of these parameters, the zone of interrogation is usually limited to the immediate proximity of the borehole. The seismic waveforms of the microearthquakes contain a wealth of information about the rock in regions that are otherwise inaccessible for study. By reliably locating the hypocenters of many microearthquakes, we have inferred the joint patterns in the rock. We observed that microearthquake locations do not define a simple, thin, planar distribution, that the fault plane solutions are consistent with shear slippage, and that spectral analysis indicates that the source dimensions and slip along the faults are small. Hence we be1 ieve that the microearthquakes result from slip along preexisting joints, and not from tensile extension at the tip of the fracture. Orientations of the principal stresses can be estimated by using fault plane solutions of the larger microearthquakes. By using a joint earthquake location scheme, and/or calibrations with downhole detonators, rock velocities and heterogeneities thereof can be investigated in rock volumes that are far enough from the borehole to be representative of intrinsic rock properties.

Jan 1, 1986

By Yanchuan Li, Haifei Yao, Haiyan Wang

"Dust pollution is very serious in coal mining process, which is a great threat to the underground staff health and equipment and facilities safety. Coal seam water injection in mining process is an effective way to reduce coal mine dust concentration at the source. However, the effectiveness of water injection is limited in high-pressure and low-porosity coal seam. To improve the moisture content of coal seam, expand the wetting range and enhance the effect of dust reduction by water injection, the injectability and influencing factors of coal water injection are analyzed by numerical simulation method, and the sealing technology under high-pressure condition is studied. Then, according to the practical conditions of Tangkou coal mine, the parameters and process system of process system are designed, the effect of high-pressure water injection in coal seam was determined by testing water injection quantity, water increment and dust concentration. It is showed that the dust-removal rate of the high dust concentration operation such as falling coal and moving frame is 63.49% and 59.72%, the maximum dust-removal rate of multi-processes is 53%, which achieve a high level of application. The research results in this paper is of important theoretical and practical value to improve the water injection effect of high-pressure and low-porosity coal seam and improve the efficiency of dust removal in coal mining process.Introduction With the increasing of the depth and mechanization of coal mining, coal dust, the impact of ground pressure, ground temperature and other natural disasters continue to upgrade the harm degree (Wang 2011, Wu et al 2012), disaster incidents occur frequently, which seriouslythreaten the safe and efficient mining and the physical and mental health of underground staff. Coal seam water injection can effectively reduce the coal dust when coal crushing, prevent the impact of mine pressure, coal and gas outburst disasters, by increasing the thermal conductivity of coal, reduce coal temperature, and prevent spontaneous combustion of coal. In addition, coal seam water can soften the hard coal, so that speed up the recovery rate, improve coal production and efficiency (Wu et al 2008, Nie et al 2007). However, the coal seam in many mining area is with high-pressure and low-porosity feature, Coal joint cracks are not developed and relatively hard, water injection is difficult in these coal seams, then the desired disaster prevention effect cannot be achieved (Jin et al 2001, Zhao et al 2000). In this paper, the numerical simulation and field test methods are used to design the high-pressure and low-porosity coal seam water injection technology, so as to solve the difficult problem of coal dust control in high-pressure and low-porosity in deep well mining process."

Jan 1, 2017

By R. W. Brann, R. C. Freas

Franklin Industrial Minerals operates several mines/quarries, including two room and pillar underground mines. Both of these mines are operated as multiple level room and pillar including heading and bench operations on one or both of the levels. This paper focuses on Franklin’s Crab Orchard, Tennessee mine, which produces both high purity chemical grade limestone and crushed stone for construction applications. The high purity chemical specifications for the chemical grade limestone and filler/extender applications are inconsistent with the non-chemical rock being produced to supply the crushed stone market. As a consequence Franklin has developed a unique mine plan and operation to maintain both product balance and a safe and stable working environment.

Jan 1, 2003

By Gunjan R. Bhattarai, Kumar Bhattarai

Recently, there has been an enormous increase of interest in artificial intelligence (AI), machine learning (ML), and their applications by researchers, government agencies, and the underground construction industry. Ultimately, these tools have the potential to automate the design and construction processes and boost productivity, safety, quality, and operational stability. This paper presents ongoing research and applications of artificial neural networks (ANNs), robotics, and 3D technologies in ground characterization, tunnel ground support prediction, risk projection and reduction, and productivity enhancement in TBM operations. The paper further investigates potential uses of AI, robotics, and 3D technologies in the underground construction industry

Dec 1, 2022

By S. P. Girrens

A coupled finite element geomechanical- hydrology code is currently under development for application to the problem of predicting groundwater disturbances associated with mine subsidence. The structural-fluid coupling is addressed by calculating the subsided mine geometry, with emphasis placed on determining the strata disturbance and locating damaged regions, for input into a hydrology code, which determines localized volume flow rates and aquifer fluctuations. Benefits from coupling will be best realized when field measurements, an additional aspect of the study concurrent with analytical investigations, indicating the relationship between increasing rock strain and increasing permeability are incorporated into hydraulic material descriptions. Hydrologic and struc- tural calculations are presented to demonstrate computational capabilities applicable to mine subsidence

Jan 1, 1982

By S. A. Kupferman

Cement raw materials used in southern California and Arizona cement plants occur in a wide variety of geologic environments. Limestone, the primary material making up 75-80% of the raw materials mix used in cement manufacture, is mined solely from Paleozoic Era deposits. During this time, 570-245 million years ago, vastly more limestone was formed in California and Arizona than at any other time (continent was in southern latitudes). The general geology of each limestone deposit associated with the eight southern California and two Arizona cement plants will be reviewed. Many of these deposits are geologically complex, having been subjected to Mesozoic deformation, metamorphism and instrusive events, along with Cenozoic uplift and deformation. All of the cement plants in this region require the use of secondary additives in order to meet the chemical requirements for cement. The kinds of additives vary greatly, depending upon the chemistry of the limestone deposit, cement specifications, and the cement manufacturing process. In some cases, clay deposits with suitable chemistry on or near the limestone sources are utilized. Where alkali limitations or need for alumina-rich materials exist, then specialty clay deposits are used. Iron-rich sources in the region include iron ore deposits and slag or mill scale from local steel mills. The geologic setting and location of these additives, along with gypsum and silica-rich deposits presently in use, will be mentioned.

Jan 1, 1987

By R. L. White

Classification of Mills Mills may be classified under four categories that relate to the type of action utilized to grind the material: Tumbling. The most important of these to the minerals processing industry are tumbling mills. Grinding media is actuated in a free¬form pattern in a rotating drum causing it to tumble, material being ground passing through the tumbling media. Work is done by a combi¬nation of attrition and impact. Impact. Grinding media is actuated in a distinctive pattern so that it impacts the material being ground. Work is done by impact. Roller. Grinding media is actuated in a distinctive pattern, mate¬rial being ground passing under or between the media. Work is done by compression. Fluid Energy. There is no grinding media as such. Energy is imparted to the material by transfer of kinetic energy from the fluid to the material. Grinding is accomplished by interparticle impact and attrition. Tumbling Mitts The main physical arrangement consists of a lined cylindrical drum mounted on trunnion bearings driven by a ring gear and pinion, in turn connected directly or through a reducer to the electric motor. Variations to this general arrangement include: (1) Drum mounted on rollers instead of trunnions. (2) Bearings on the drum directly, not on trunnions. (3) Utilization of multiple pinions on the gear. (4) Trunnion-type drive arrangement through a gear reducer with¬out the use of a ring gear. (5) Motor rotor mounted directly on the drum with stator around the drum, thus eliminating the gearing. The drum consists of a shell and heads lined with replaceable liners of various types and configurations. Various types of tumbling mills are tabulated; illustrations of some are shown. The types are so designed for specific purposes. Media utilized include steel rods, balls, or rock of the same material as being ground or of special material in the instance where iron contami¬nation is detrimental (see Figs. 9 and 10 and Table 2). Impact Mills Although there may be some overlapping of interpretation of terms, impact mills are considered those in which the media is actuated in a distinctive manner, at relatively high speed, impacting the material to be ground. There is an overlapping also in what may be considered to be crushing equipment rather than grinding equipment. Hammer Mill or Impactor. Material is fed into the equipment; inside hammers of impactors revolve at a high speed, breaking the material on impact with the hammers (see Fig. 11). Material is also thrown against the periphery of the mill, causing impact grinding to occur. Equipment is normally lined with replaceable abrasive resis¬tant metal; hammers are also

Jan 1, 1985

By Warnie Flint

According to statistics compiled by the National Safety Council, US Bureau of Mines, American Medical Association, and other agencies, accidental injuries cause more deaths than all the leading diseases. No one is immune to an accident. Probably the best way to describe an accident is to say that it is an unexpected happening. The automobile driver is not expecting a terrifying crash, the electrician does not expect to be electrocuted, nor is the coal miner expecting the roof to fall on him. All personal injuries will not result in death. There is a multitude of victims who are living proof of what accidents can mean to an individual-victims who are blind, paralytic, missing arms, legs, etc. In most instances the earning power of these individuals is gone, and they are utterly dependent upon family or welfare. For many years there seemed to be an attitude that prevailed in industrial America that accidents were inevitable, and that so many fatalities and injuries should be expected. This, of course, was utter nonsense. Since the birth of such organizations as The National Safety Council, American Society of Safety Engineers, and. the US Bureau of Mines, much progress has been made in reducing accidents. The enactment of compensation laws greatly contributed to the progress that has been made. Does this mean that all accidents can be prevented? Unfortunately, it does not. Human psychology indicates that men will work unsafely or perform unsafe acts for the following reasons : 1) Lack of knowledge or skill. 2) Conflicting motivations, such as: (a) to be more comfortable, (b) to save time or effort, (c) to be accepted by a group. 3) Physical or mental condition. Nearly everyone desires his own safety, but not all individuals are willing to do what they know to do to insure their own safety.

Jan 1, 1981

By B. A. Firth

Australia is the largest exporter of coking and thermal coal to the international market. This market has required that the coal being presented to the customer has a particular level and consistency of quality. In this context, the Australian industry has developed coal preparation practices that allow this criteria to be met while maximising the recovery of coal from the resource. This has required on- going developments in both coarse and fine coal cleaning technology over the past 30 years. Coal flotation has undergone a number of developments with regard to maximising recovery from the overall plant circuit. This includes innovative flotation circuits (split feed), methods of enhancing the use of reagents and control of pH. During the 1990s, there have been major changes in flotation as practised in Australian coal preparation plants. Columns have become the preferred technology for both greenfield developments and plant upgrades. This paper will outline the above developments with a number of plant examples and the reasoning that has driven the change. The ongoing research that is being carried out on new cells to optimise the overall fine coal circuit will also be discussed.

Jan 1, 1999

By J. L. Huiatt, D. G. Foot, J. D. McKay

The US Bureau of Mines compared column flotation using either fine or coarse bubbles with conventional flotation on a Montana chromite ore. On deslimed ore, fine-bubble column flotation produced a &.7% Cr2O3-grade rougher concentrate with 87% recovery, compared with 43.8% and 43.5% Cr2O3-grade rougher concentrates with 85% and 77% recovery for coarse-bubble column flotation and conventional flotation, respectively. On undeslimed ore, coarse- and fine-bubble column flotation produced rougher concentrates containing approximately 41.5% Cr2O3 with 95% recovery, exceeding conventional flotation, which produced 35.6% Cr2O3 -grade concentrates with 87% recovery.

Jan 1, 1987

By Eric Ohl

Due to the world's ever increasing minerals and energy demands, process plants have to cope economically with ever growing throughput rates. This trend has accelerated the development of high capacity vibrating screens. Screens with screening areas of 30 to 50 square meter (322 to 540 square feet) and width of 5.5 meter (18') are technically possible and are being used presently with great success. This paper will concern itself with the general aspects of large screen design, by using modern technology and the latest findings with regards to fatigue strengths relative to the laws of vibration. It also will investigate the technical and economical limits of such designs.

Jan 1, 1983

By Paul Gribbon, Greg Colzani, Jim McDonald

The $300 million West Side Combined Sewer Over?ow Project consists of over5.5 kilometers of soft ground tunnel, an 833-million liter per day (220-MGD) deep shaft pump station, 3 kilometers of micro tunneling, and other miscellaneous shafts and pipelines. The construction contract, underway since September 2002, is a reimbursable cost plus fixed fee contract that included a quali?cations-based contractor procurement process and has undergone some modi?cation since execution. This paper will describe the contractual issues addressed to date, dispute resolution, where improvements can be made, and how an Owner can evaluate whether this type of contract is the best approach for an underground project.

Jan 1, 2005

By Robert J. Guardia, James Rustvold, Robert A. Robinson, Christopher A. Robertson

In 1999, the Bonneville Power Administration (BPA) replaced approximately 730 m(2,400 ft) of damaged 42- and 36-inch concrete pipe by microtunneling Permalock pipe through sand and partly below groundwater. Microtunneling saved $3.5 to $5 million from the estimated cost of a shored excavation and avoided a railroad and contaminated valley fill. A slurry microtunnel boring machine (MTBM) was used for two segments where groundwater was present and a wheel excavator MTBM was used for one segment where groundwater was not present. This paper describes design and construction of this project that was completed within 2% of the bid and engineer’s estimate.

Jan 1, 2001

By Ehsan Alavi, Brian Hagan, Colin LaVassar, Glen Frank, Derek Dugan, Rick Capka, Lisa Mori

"Tunnel face instability is one of the most common issues in EPB tunneling. The evaluation of an ideal face support pressure is a critical element in the design and construction phases of EPB tunneling. In this study, measured tunnel face pressures in three EPB tunneling projects (University Link U230 and U220 projects and the Northgate Link Extension N125 Project) for Sound Transit in Seattle, WA are compared with the calculated analytical methods. This comparison shows that the analytical methods generally overestimate the required tunnel face support. The best practice for managing the face pressure in EPB tunneling operation is discussed based on the experience gained through these projects. Furthermore, the algorithm that is developed for identifying ground loss in these projects is addressed. INTRODUCTION Earth pressure balanced tunneling relies on using muck within the chamber to support the face. Muck is pressurized by controlling the advance rate of the tunnel boring machine and the speed of the screw conveyor. Target face pressure is typically calculated by using the geotechnical assumptions in the geotechnical baseline report. The concept behind EPB tunneling is that the application of sufficient face support pressure will prevent tunnel face instability and the resultant over excavation. Tunnel face instabilities caused by a lack of sufficient face support can lead to ground loss and surface settlement (Anagnostou & Kovári 1996, Kirsch 2010). A certain support pressure must be achieved to counteract water and earth pressure with an adequate factor of safety. While the water pressure can be predicted accurately, the determination of the resultant earth pressure on the face is less precise. This becomes manifested in the relatively high partial safety factors on the earth pressure."

Jan 1, 2016

By T. Gouri Charan, G. V. Rao

A spherical agglomeration process for the separation of scheelite fines of less than 30 µm in very low concentration of 0.04% WO3 in a binary mixture with quartz fines of less than 30 pm has been described. A concentrate containing 14% WO, with more than 90% recoveries could be achieved by means of anionic sodium sulfo succinate collector at pH 3.5 and also with commonly used anionic sodium oleate at pH 10.5 as per the conceptual flowsheet suggested. Such a process is envisaged as commercial potential for the recovery of fine-grained scheelite present in the tailings of gold plants as found in India.

Jan 1, 1991

By Francis B. Gularte, James E. Monsees, John-Paul Whyte, Gary E. Taylor

In a short section of the Los Angeles Metro Rail system approximately 222.5 m (730 ft) of 6.4 m (21 ft) diameter twin-tube tunnels separated by a 1.8 m (6 ft) narrow pillar were designed to pass under a major eight lane freeway and a metropolitan intersection with only 3.7 m (12 ft) to 5.8 m (19 ft) of loose fill and alluvium cover. The design considerations and the chemical grouting program used to stabilize the alluvial materials is discussed. Also included is a discussion of the novel shield used for tunnel excavation and the effects of the subsequent fire.

Jan 1, 1991