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By Gary R. Adams

Coating thickness control is typically difficult with touch-up solders for galvanized steel, and corrosion properties and abrasion resistance are sometimes poor. This paper reports on progress in ILZRO-sponsored research to develop an improved touch-up solder. Encouraging results were achieved in torch soldering trials with zinc-tin based alloys. Mouldability and coating thickness control were achieved over a practical working temperature range in which the solders consisted of a viscous mixture of solid primary zinc phase particles in a liquid zinc-tin eutectic matrix The mouldability was dependent on the microstructure of the starting material, and optimum structures could be obtained through control of casting solidification rates and/or by the addition of small amounts of copper. Hardness and preliminary corrosion test results showed potentially good mechanical and corrosion behaviour. The absence of toxic materials ensures environmental friendliness. Comprehensive performance testing is continuing on selected experimental zinc-tin-copper touch-up solders.

Jan 1, 1992

By Steve Kral

U.S. mines are among the most efficient, productive and safest in the world. Much of that efficiency is due to the high-technology equipment and processes available to the industry. The U.S. mining industry can produce more material now with fewer people than it could a few decades ago. And that material can be produced more safely. However, the workforce is growing older and fewer young people are filling the holes created by retirements. Even though mining is one of the highest paid occupations in the United States, young people believe they can find jobs that pay almost as well without the risks and the often remote locations associated with mines.

Jan 1, 2002

By M. E. C. Snyman, N. Naudé

"Coal fines produced during processing are difficult to dewater and result in a lower quality product and consequent lower value. A South African coal mine experiences severe difficulties with belt filter dewatering operations due to the presence of fines reporting from the thickener underflows. Plant 2 currently handles super-fine particles of size -34 µm and has low belt filter efficiency: excessive moisture retention lowers the product quality and strains downstream processing. It was necessary to determine an alternative method for dewatering these fines. Blending of fine material with coarser material was proposed as a solution. The effect of coal particle size and layering during ultrafines belt filter dewatering was evaluated using various blends of the fine Plant 2 material with coarser Plant 1 material. The best layering arrangement of the two materials and its optimum blend required to achieve reduced filter cake moisture content was determined in practise using a vacuum filter to simulate belt filtration. A blend of the two materials gave improved dewatering efficiency for the belt filters compared with that of the Plant 2 material alone. The best layering configuration was with Plant 2 material at the bottom and Plant 1 material on top. The optimum blend for industrial applications comprised 48% fines from Plant 2. IntroductionFines are produced during the processing of coal. It is estimated that 2 to 3% of run-ofmine coal reports to the ultrafine portion (-100 µm) (le Roux, 2005). The particle size of coal is inversely proportional to the amount of water adsorption, so smaller particles adsorb more moisture. Moisture removal requires either mechanical processes or thermal drying: mechanical processes are less expensive, but the fines still have high moisture retention. Discarding of fines leads to economic losses, so it is essential that they be dewatered so that they can then be sold as a product: fines need to be treated for both resource management and conservation reasons (Kenney, 1994). Removal of free surface moisture from ultrafine coal particles using a belt filter therefore remains a process that needs to be continuously improved. Ultrafine coal originating from a thickener underflow is known to be difficult to dewater owing to factors such as filter cloth blockage and moisture retention due to clogging. Mixing of finer and coarser materials has been proposed to deliver better dewatering efficiency and improved the quality of the recycled water (Kenney, 1994)."

Mar 1, 2019

Increase the safety of underground mine workers by minimizing hazards associated with rerailing mine cars after derailment. Background and Approach A serious operational problem in underground mines is the task of rerailing mine cars. Current rerailing practices are not only hazardous but are inefficient as well. Most methods involve pulling the derailed car back onto the track with a locomotive. This causes damage to the road bed and is not effective on curves or in situations where the car's wheels are too far from the rails. Jacks, wooden props, and pry bars are also used to raise or lower cars back onto their tracks but methods involving these tools require much strenous manual effort by mine workers, thus posing possible serious injuries. The problem is further compounded by the cramped, narrow confines of the underground mine environment which allows no space to permit use of cranes or other surface railroad rerailing techniques. The Bureau of Mines, aware of these problems, investigated improvements in current underground rerailing methods. Through a cooperative effort with Hoesch MFD, a system was designed and modified that can be easily carried into the mine by workers and quickly assembled at the derailment site. The system is hydraulically and pneumatically powered rather than reliant upon manual operation.

Jan 1, 1986

Since 2001, the Hybrid Stress Blast Model (HSBM) project members have developed a software suite to model the complete blasting process from non-ideal detonation to muck pile formation. To preserve the physics and improve solution time, the breakage engine uses a combination of analytical models and 2D axisym-metric finite differences to model near-field crushing, coupled to 3D discrete lattice fracturing and distinct element numerical methods to model throw and muck pile development. The model has been validated by comparison with laboratory and field tests in kimberlite. Multiple blasthole simulations are used to demonstrate how changes to blasting parameters can influence downstream efficiencies. Case studies of wall control blasting show that the presplit design must balance the two opposing effects of increased damage with increased charge and decreasing attenuation of the seismic waves with decreasing charge. Modelling of decoupled explosives needs further development. Reducing the charge towards the back of the trim blast results in a much more significant decrease in back damage than altering the timing. The model demonstrates how separation along the weaker planes in a jointed rock can coarsen the fragmentation, leading to inefficient beneficiation, and extends the damage to a distance of at least twice the burden behind from the blasthole, severely compromising the wall stability.

Jan 1, 2012

Since 2001, the Hybrid Stress Blast Model (HSBM) project members have developed a software suite to model the complete blasting process from non-ideal detonation to muck pile formation. To preserve the physics and improve solution time, the breakage engine uses a combination of analytical models and 2D axisym-metric finite differences to model near-field crushing, coupled to 3D discrete lattice fracturing and distinct element numerical methods to model throw and muck pile development. The model has been validated by comparison with laboratory and field tests in kimberlite. Multiple blasthole simulations are used to demonstrate how changes to blasting parameters can influence downstream efficiencies. Case studies of wall control blasting show that the presplit design must balance the two opposing effects of increased damage with increased charge and decreasing attenuation of the seismic waves with decreasing charge. Modelling of decoupled explosives needs further development. Reducing the charge towards the back of the trim blast results in a much more significant decrease in back damage than altering the timing. The model demonstrates how separation along the weaker planes in a jointed rock can coarsen the fragmentation, leading to inefficient beneficiation, and extends the damage to a distance of at least twice the burden behind from the blasthole, severely compromising the wall stability.

Jan 1, 2012

By N. Barton, E. Quadros

This paper addresses the prediction of groutable joint apertures, grout penetration limitations, and possible grout take volumes per cubic metre of rock, as a result of 5 to 10 MPa pre-injection pressures ahead of tunnels. Joints are obviously opened more than in the preceding Lugeon tests, and many rock mass properties can apparently be improved if stable micro-cement based materials are used. Cet article concerne la prédiction des ouvertures des fractures injectables, les limites de pénétration du coulis et les volumes injectés par mètre cube, d’après les résultats des injections à l’avant tête des tunnels sous pressions de 5 à 10 MPa. Evidemment les joints s’ouvrent plus que dans les essais Lugeon précédents. Maintes propriétés du massif peuvent apparemment être améliorés si l’on emploi des coulis a base de micro-ciment stable. Die Publikation widmet sich der Prognose injizierbarer Kluftöffnungen, Grenzwerte für Injektionsreichweiten und erreichbarer Injektionsvolumen pro Kubikmeter injizierter Fels, durch die Anwendung von 5 bis 10 MPa Vorinjektionsdrücken vor der Tunnelfront.Die Klüfte werden offensichtlich weiter geöffnet als in den vorhergegangenen Lugeon Versuchen und mehrere Felsparameter können durch die Verwendung von stabilisierten Micro-Zement basierten Injektionsmaterialien verbessert werden.

Jan 1, 2003

By Bruno A. Fichna

Longwall mining offers low cost potential for coal with high capital investment. As opposed to two shifts-per-day operation in most long- walls, Saarberg Mines in Germany increase utilization of capital by operating their longwalls around the clock. Differentiation between capital and operating costs, corrective maintenance versus preventive maintenance, improved roof conditions, and economical life of equipment was investigated. A surprisingly high degree of improvement was attained. Capital costs at Saarberg longwall coal mines have been reduced through a step-by-step research and trial program. This reduction was particularly influenced by the high performance pilot longwalls at the Ensdorf mine. The following presentation shows data and figures of those longwalls. End results were 40% reduction in capital costs, which could contribute favorably to investment decisions in the coal industry in a supply side economics environment.

Jan 1, 1982

At Namdeb, submerged beaches are earmarked for sampling and future mining and various sampling configurations are tested for optimality through the use of spatial simulations. For the creation of these virtual orebodies, basic statistics and variograms are needed, but in this specific instance no data exists from which the necessary parameters can be determined. The best that can be done is to use proxy data from onshore beaches, with adaptations where needed. The reworking of raised beaches during periods of rising and falling sea levels in some cases destroyed the internal beach structures, and it is very difficult to determine the variograms. A method is proposed whereby simulated annealing is used to adjust the sample locations to align the data pertaining to beach crests or cliff lines, thus improving the variogram structure along the shoreline in the direction of the highest geological continuity.

Jan 1, 2014

By S W. Kingman, D Whit, I S. Lowndes

The use of compressive crushing equipment such as gyratory crushers within minerals processing plants can potentially generate large quantities of dust. Remedies to this problem include the retrofitting of shrouds, enclosures, local exhaust ventilation (LEV) systems and water suppression systems. The single or combined application of these systems must be optimised to ensure they operate efficiently. It is desirable that the future design planning of such facilities include integrated dust suppression and/or removal systems to ensure material delivery rates are maintained and the welfare of the workforce is protected. The characteristic release of dust and the disturbance to the surrounding ventilation airflow is investigated by the construction and solution of computational fluid dynamic (CFD) models validated by data obtained from scale experiments. A 3D computational model was constructed using the FluentTM CFD software to represent the background ventilation regime within an underground crushing installation. The falling ore is represented as a continuum granular fluid falling under gravity from the raised bed of the dump truck. Transient path lines are computed to simulate the updraft airflow generated by the tipping process and indicate the dispersion path of any entrained dust. The relationships between the falling ore material, the displaced air and the shear induced flow are determined by an analysis of the computed volume/mass flow rates predicted across the crusher opening. An analysis of the airflow patterns predicted by the CFD simulation models indicates strong shear flows induced between the tipped material and the surrounding airflow in the vicinity of the crusher during tipping, and a strong influence of the background ventilation regime on the path taken by this shear flow. Scale experimental studies were conducted to characterise the induced shear flow and visualise the potential entrainment and transport of dust. An analysis of these experiments is presented.

Jan 1, 2005

By Robert A. Jankowski, J. Drew Potts

The Bureau has identified several ventilation techniques and a water spray application for reducing auger mining dust levels. The dust control methods all work by improving air quantity or flow patterns at the face. Section airflow is maximized by reducing air leakage between entries. Sealing stoppings with brushed- on mortar, containing fiberglass additives, reduces leakage. Heading airflow is maximized by properly installing the brattice curtain and keeping the area between the curtain and rib free from obstructions. The brattice curtains should be hung at least 1.7 m (5.5 ft) from the ribs in 7.9 m (26 ft) wide entries and kept less than 4.6 m (15 ft) from the face. A tight curtain seal is created by using the mine air pressure to force the curtain against the timbers, roof and floor of the mine. Using both a blowing curtain and an exhausting curtain will isolate some face workers from dusty air. The Bureau designed, auger clearer spray system, can be used to force heading air across the active face. Laboratory tests indicate that the auger clearer spray system can increase face velocities by more than 0.5 m/sec (100 ft/min), while using less than 0.13 l/sec (2.0 gal/min) of water.

Jan 1, 1989

Reduce the dust levels to which jacksetters and helpers on auger mining sections are exposed by identifying viable, effective methods for control-ling respirable dust on these sections. Approach The Bureau of Mines con-ducted laboratory tests and respirable dust surveys to identify the factors that distinguish clean auger mining operations from dusty ones. Study Results Results of the Bureau's study revealed that ventilation is the most important element of auger mining dust control. The four must important venitilation parameters are airflow, curtain configuration, curtain setback, and curtain installation.

Jan 1, 1988

By Jerry R. Riding

Metallurgical process methods have seen dramatic improvement over the past fifty years. As these improvements have come about, more and more emphasis has been placed on obtaining accurate and rapid analysis of the metallurgical processes. Well-defined conventional laboratory analysis procedures which have proven to be reliable were developed early in the mineral industry's history; however, these conventional procedures, which have not changed appreciably in fifty years, have the serious drawback that they are too slow to be of appreciable value in automatic control of the processes. For example, the assay results normally become available to a mill operator from eight to twenty-four hours after a sample is taken. Since the desired mineral separation can only be made while the minerals are in the flotation circuit, conventional assay results provide information similar to postmortem reports. Consequently, using conventional procedures, the mill is operated with information from an earlier period of time, which may not reflect current conditions. In recent years there has been a steady increase in the volume of required samples. At the same time, labor, material, and overhead costs have continued to rise causing the cost per assay to reach an alarming level. This rising cost per assay, plus the increasing demand for rapid analysis necessary for control, has caused the mining and metal processing industries to look toward other techniques to solve these problems As a result, X-ray fluorescence which can provide on-stream analysis necessary for control, as well as perform numerous laboratory assays at lower cost and at a much greater speed than conventional methods, has gained wide-spread attention. In addition, multichannel X-ray fluorescent instruments are now available which have been perfected to the point where the analysis of the most important chemical constituents is available within one minute after a sample is presented to the X-ray analyzer. Because of these obvious advantages, extensive use is being made today of X-ray analysis in the mining industry to analyze slags, ores, and mineral content of rocks. The results are used to make quick decisions for both mining and beneficiation of metals. For example, X-ray systems which provide rapid on-stream analysis of the slurries at desired points Fn metallurgical processes have recently been developed. The successful application of these systems has moved the milling process a step closer to fully automatic control.

Jan 1, 1969

By B. G. Cousins, L. Racine, R. S. MacPhail

"FLEX 31 is a chemically enhanced sodium isopropyl xanthate that has shown improved collection properties over SIPX for copper-bearing and copper-activated minerals. Characteristics such as improvement of recoveries with lower dosages and high pyrite and pyrrhotite rejection capabilities have all been exhibited by FLEX 31.The most improved results have been seen insphalerite flotation. Plant trial work carried out in the zinc circuit at the Louvicourt Concentratorin northern Quebec has produced data showing superior grade and recoveries from rougher concentrates that previously had not been attain-able with other reagents effectively. The improvement over SIPX adds up to an almost$1,000,000 annual improvement on the mine’s bottom line at present zinc prices.IntroductionSodium Isopropyl Xanthate (SIPX) is one of the most popular flotation chemicals on the market today. Somewhat more specific than amyl xanthates, SIPX is used in a variety of ores like copper/zinc, lead/zinc, arsenopyrite/pyrite, and many others (Melis et al., 1991). An investigation carried out by Tennants Research Technology Applications (TRTA), a division of Charles Tennant & Co. (Canada) Ltd., produced a chemically enhanced SIPX that has shown all the advantages of normal SIPX along with improved recoveries of copper and copper activated minerals. The new product has been named FLEX 31. Currently, FLEX 31 is manufactured at the Prospec Chemicals, another division of Charles Tennant & Co. (Canada) Ltd.A large amount of laboratory testing pro-grams have been carried out with FLEX 31 todate (MacPhail and Cousins, 1995; Cousins and MacPhail, 1996). One of the minerals that has a defnite affinity to improved fotation is sphalerite (ZnS). Once activated with copper sulphate, sphalerite has produced some of the most spectacular test work when FLEX 31 is compared directly to SIPX. Plant trials of FLEX31 at Aur Louvicourt Inc. carried out in 1995show that FLEX 31 is far superior to SIPX for activated sphalerite flotation."

Jan 1, 1997

By Robert MacPhail, Louis Racine, Bret G. Cousins

"Sodium Isopropyl Xanthate is employed in a wide variety of sulphide flotation procedures due to the specificity over other xanthates and the cost savings over other sulphide collectors such as thionocarbamates, xanthogen formates and dithiophosphates. An investigation carried out by Tennants Research Technology Applications (TRTA), has produced a chemically enhanced SIPX that has shown all the advantages of normal SIPX along with improved recoveries.Currently, FLEX 31 is manufactured at the Prospec Chemicals xanthate plant in Fort Saskatchewan, Alberta, Canada. Prospec, founded in 1983, produces approximately 4500 tonnes of xanthates per year and is presently undergoing expansion to produce approximately 6000 tonnes. The proprietary process for FLEX 31 is a new addition to plant operations that include the production of xanthates, thionocarbamates and xanthogen formates.This paper will cover the testwork on the zinc flotation circuit at the Louvicourt Mine in Val d'Or, Quebec. This testwork indicated that FLEX 31 could replace SIPX due to the ability of the FLEX to improve zinc flotation kinetics without adversely affecting final concentrate grade. FLEX has presently replaced SIPX in the zinc circuit at Louvicourt.BackgroundThe Louvicourt deposit is hosted by greenschist facies Archean volcanic rocks located in the southeast portion of the Abitibi Greenstone Belt. In the Val d'Or area, the volcanic rocks form an east-west striking, steeply dipping and south-facing sequence composed of thick mafic and ultramafic flows of the Lower Malartic Group.The joint venture has three partners-Aur Louvicourt Inc. (30%), Novicourt Inc. (45%) and Teck Corp (25%). Aur Resources holds 30% interest through Aur Louvicourt, a wholly owned subsidiary and is the operator of the project. Novicourt Inc. is 60.9% held by Noranda.Approximately 75% to 85% of Louvicourt's revenue comes from the sale of copper; 10% from gold (in the copper concentrate); 7% from zinc and 3% from silver (also in the copper concentrate) The copper at Louvicourt is fairly ""fast floating"". About 60% of the copper in the ore can be concentrated in the first flotation cells with feed grades of approximately 4% copper.The initial testwork and pilot trials had indicated that it would be difficult to achieve zinc grades over 52% and recoveries would have to be kept at a level amenable to salable concentrate grades. The actual mill results, with a fine regrind, achieved zinc grades of 55% to 56% at about 75% recovery."

Jan 1, 1996

By W. C. Foshee

The large volume of water used in coal preparation plants makes water recycling a necessity. Economical cleaning of dirty water usually requires flocculation with an efficient organic polyelectrolyte. This paper discusses identification of optimum flocculant systems. Supporting laboratory data with on-site tests and full scale field trials supplies information necessary for matching the polymer to the plant.

Jan 1, 1979

By Robert S. MacPhail, Chilombo Henry, Arnold Kabamba, David Mukelebai, Suresh Thirunagari, Bukali Victor, Yoram Kapai, Chomba Leonard, Kanna Amarasingham

"FLEX 31 is a chemically enhanced sodium isopropyl xanthate. Developed by Charles Tennant & Co (Canada) Ltd and has shown improved collection properties over SIPX for sulphide minerals flotation. Improvement of recoveries, grades, faster kinetics, lower dosages, high pyrite and pyrrhotite rejection capabilities have all been exhibited by FLEX 31. Recent plant trial carried out in the copper circuit at one of the largest copper mine in Zambia shown over US $ 2.00 Million annual improvement on the bottom line over SIPX at current copper prices. Data produced also showed superior grade and recoveries from rougher concentrates that previously had not been attainable with other reagents effectively. Flex 31 has also shown positive outcomes with zinc, Copper/Zinc, arsenopyrite and copper/molybdenum ores.IntroductionSodium Isopropyl Xanthate (SIPX) is one of the most popular flotation chemicals on the market today. Somewhat more specific than amyl xanthate, SIPX is used in a variety of ores like copper/zinc, lead/zinc, arsenopyrite/pyrite, and many others (Melis et al., 1991). An investigation carried out by the research division of Charles Tennant & Company (Canada) Limited has produced a chemically enhanced SIPX. This product has shown all the advantages of normal SIPX along with improved recoveries of copper and copper activated minerals. The product was named “FLEX 31”."

Jan 1, 2016

By E. Gybbon Spilsbury

(Pittsburg meeting, March, 1910.) THE recovery of gold and silver from their ores by means of the cyanide process has been so successful in the last few years that any radical improvement would seem impossible; yet the appliance to which I wish to call attention in this paper is really a radical departure from the methods now in general use. The most modern and approved of these, known as the all-sliming method, depends for its success on the grinding of the. ore so fine that practically 90 per cent. of it will pass through a 200-mesh screen. The slimes thus produced are then agitated and aerated in tanks of various types. The main object of this treatment is to insure such a thorough admixture of the pulp and solution that every particle of the ore is surrounded by a volume of solution sufficient to insure the dissolving of the whole of the gold- and silver-content. In addition, in order to expedite the action of the cyanide, and to oxidize such elements as would, if left in their active state, become cyanicides, air is blown in under pressure. In the Pachuca tank, this air is the active and sole means of agitation. The chief objections to all the methods off agitation used heretofore are the expense of operating and maintaining the mechanical devices for keeping the pulp in suspension, and the length of time required to obtain a fairly complete extraction. of the values. These objections are inherent to any method of agitation effecting a circulation of the pulp and the solution together, by giving the whole mass a circular movement, as in the low-tank system, or a vertical circulation, as in the Pachuca-tank system. In both methods, the particles of ore are kept traveling in the same direction as the solution, and with very little difference of speed; so that, while the whole mass is in

May 1, 1910

By B K. Da, S A. Balaji, G P. Roy, T K. Dutta

The raw material handling complex at the Durgapur steel plant provides iron ore, crushed coke and flux to two sinter plants. Either some facilities were not envisaged or not properly designed before the project stage which caused problems during operation of the plant. The absence of an in situ roll turning facility, used to increase maintenance activities for disassembly, transportation of rolls to central machine shop and assembly of rolls, led to decreased crusher availability and increased activities for the maintenance crew. The provision of a smaller vibro feeder/screen in place of a suitable sized screen caused jamming of the screen deck, adversely affecting screening efficiency and the crushing index of crushed coke. Some design modifications and developmental work was undertaken, such as the development and installation of an in situ roll turning facility in the existing limited space, achieving low feed (0.1 - 0.2 mm/rev), lower cutting speed of 30 - 40 m/minute for 350 BHN hard roll, which was also a difficult engineering challenge to bring within the tolerable limit of vibration. This was successfully achieved. Modifications to the screen deck, introduction of differential speed crushing and modification to the vibro screen and vibro feeder for uniform distribution of feed have been incorporated. These innovative design modifications to the in situ roll turning have led to a drastic decrease in maintenance activities and an improvement in the crushing index. Modifications to the screen have resulted in the elimination of jamming and improved screening. Modifications to the vibro screen before the primary crushers and to the vibro feeder before the secondary crushers have prevented excessive wear in the central portion of rolls, ultimately leading to increased roll life. Incorporation of differential speed crushing has resulted in an increased crushing index and decreased generation of micro fines. All the above modifications have led to distinct improvements in equipment availability, increased roll life and a decrease in maintenance activities and improvement in crushed coke granulametry, ultimately resulting in improved productivity and quality of iron ore agglomeration at the sinter plant. The innovative design modifications mentioned above are discussed in detail in this paper.

Jan 1, 2005

By Sib N. Mukherjee

Main ventilation fans are used in all the mines and they run continuously 24 hours a day and 365 days in a year. Any improvement in their performance can lead to considerable power saving. The basic principle for selection, operations, and related measures are discussed in brief in the paper. The contributions of different elements of mine fan on its performance are discussed in brief. The means to improve efficiency of a running fan is also discussed and the importance of saving even 1 Kwh is elaborated. It is found that the cost of the energy saved may even permit a replacement fan to be procured in a few years time.

May 1, 2007