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By L. Donovan Clark

The term "powder factor" is almost universally accepted as the measure of the efficiency of a blasting program. It represents the economics of blasting since it designates quantity of explosive (thereby providing quality control in rock fragmentation) in terms of the associated volume broken. It is the wide use of this concept that explains the interest shown in an approach to rock blasting preferred by A. W. and Z. W. Daw* in a treatise on 3 blasting (1) substantiating its use in the form, Q = CVW3 for single shot hole, where Q = quantity of explosive lb Cv = blasting coefficient W3 = unit volume of rock It is obvious that the term Cv could also be called the apparent powder factor should the equation be written in the form, Cv = Q/W3 (lb per cubic unit). However, while the approach was ingenious** and the practical applications straightforward, their original, rather limited experimental work, along with certain assumptions, was questioned.

Jan 1, 1970

By B. Anamaeric

Economic, environmental and operational disadvantages of the traditional blast furnace process has led to the development of direct smelting reduction processes, including those that utilize self reducing/ fluxing dried greenballs as iron oxide feed materials. This is mainly due to improved carbothermic reduction, carburization and reaction kinetics. In this paper, the morphological changes of the greenballs as they transform to pig iron nuggets are examined over time at a constant temperature of 1,400° C. The products produced after each treatment were characterized using optical microscopy, scanning electron microscopy/energy dispersive spectroscopy and point counting/image analysis. The changes in the percent metallized area, wustite dendrite and slag matrix content of the structures were calculated. It was determined that the transformations were initially controlled by dissolving and containment of iron oxides in the molten slag and their consequent reduction to iron, followed by coalescence of the metallized areas. The final transformations were controlled by the carburization of the metallized areas.

By S. Miller, A. Krasner, M. Sizintsev, S. Schafrik, H. -P. Chiu, J. Sottile, A. Rajvanshi, Z. Agioutantis

In recent years, a great deal of effort has been put into automating mining equipment with the goal of improving worker health and safety and increasing mine productivity. Significant progress has been made in automating mining equipment such as load-haul-dumps and drills in underground environments where global positioning systems are unavailable. This paper addresses automating the task of positioning the shuttle-car (SC) under the continuous-miner (CM) coaldischarge conveyor during cutting and loading operations. A stereo depth camera is mounted on the SC. Machine learning based algorithms are applied on the camera’s output to identify the CM discharge conveyor and segment the scene into various regions such as roof, ribs, and personnel. This information is used to plan the shuttle car path to the CM discharge conveyor. The approach currently uses a 1/6th scale continuous miner and shuttle car in an appropriately scaled mock mine

Mar 2, 2022

By Samuel S. Adams

The Permian Salado Formation of west Texas and southeastern New Mexico is composed of halite and subordinate amounts of anhydrite, clay and potassium and magnesium-bearing evaporite minerals. Aspects of the geochemistry of the Salado Formation have been investigated through studies of the stratigraphy, mineral assemblages, textures and minor element content of the salts. These studies provide information on the origin of the evaporites when combined with data on equilibria in saturated salt solutions. The principal potash ore zone in the district is composed essentially of halite (NaC1) and sylvite (KC1). Data on the color, bromide content, and proportions of halite and sylvite suggest that this simple assemblage is the product of a series of replacements rather than primary precipitation. The bromide content of the salts also indicates that the brine which precipitated the Salado Formation was derived from the dissolution of older evaporites rather than the simple evaporation of sea water.

Jan 1, 1966

By Mirko Martini, Marcelo Benaglia, Andrea Codalli

Riachuelo Lot 3 forms part of a sanitation programme being implemented in Argentina to relieve the Riachuelo river basin from its current contamination. The programme, by far the most important in its kind in the country during the last decades, will expand the sewage capacity of Buenos Aires and will benefit an area of 4.3 millions inhabitants by intercepting a number of waste water discharges and conveying them to a new treatment plant prior to final discharge into the Rio de la Plata. The project foresees amongst other works the construction of an onshore 48 m deep shaft at the outlet of the treatment plant plus a 4,3 m inner diameter outfall tunnel of 12 km length. The last 1.5 km of the alignment is fitted with 34 vertical risers jacked from inside the tunnel to allow the discharge and dilution of the treated effluent into the Rio de la Plata. This paper describes the peculiarities and challenges, both in terms of design and in terms of construction, of the outfall tunnel, which was entirely bored under the Rio de la Plata using a 5.2 m cut diameter Tunnel Boring Machine (TBM). On one hand, the tunnel segmental lining was designed to work in tension during the system flow rate peaks while on the other the tunnel excavation faced a variety of complex conditions, such as crossing water bearing permeable soft ground formations and advancing at face pressures in excess of 3,5 bars for the entire route.

Jun 13, 2021

By F. B. Olender

Idler engineering, operation, and maintenance cannot be covered in depth in a short paper. Therefore, this will be a general look into the subject matter in light or the present-day technology. Depending on the source or reference used, belts for handling bulk material underground came into being between 1900 and 1920, while strip mining appeared in the thirties. The conveyor belt speeds in that era were in the 300 rpm to 500 rpm range. Belt speeds or 600-700 rpm were in vogue in the thirties, and the early sixties saw speeds or 800-900 rpm. Today, speeds or 1000 rpm are not looked at with dismay; in fact, speeds or 2000 rpm are being discussed. Among the driving forces moving the bulk materials handling industry to these greater heights have been the mining operators and engineers. Their appetite to increase output, yield, and reduced per-ton costs has constantly challenged the bulk material handling industry to develop products capable or handling these increased capacities. One or the products affected by this movement is the idler. Apart from the conveyor belt itself, it is one or the most significant parts or a conveyor system because or the sheer numbers needed in an installation.

Jan 1, 1971

By R. E. Driscoll

The exploration, geologist of necessity has to have a wide working knowledge of many specialties other than hiw own, First he has to use his own technical background to find a deposit,, of a mineral that is of interest, Once found, his problems are Just beginning, He then has to assume the role of an economist, an accountant, a mining engineer, a chemist, a metallurgist,, a salesman and what-have you, In the economic field, he must determine the marketability of either the ore or the refined mineral. He must gauge the supply and demand for the particular mineral he is interested in and make his best guess as to ultimate cash flow from a deposit over the estimated life of said deposit, He must then assume the role of a mining man and estimate cost of recovery, including an, evaluation of the most economic mining method, cost of supplies and labor, and again estimate a net cash flow. He must then determine amenability of ore to economic metallurgical methods, he must determine the legal status of the property involved and, after analysis of the specific situation, determine the best approach to a deal, After all of this he must sell it to the people who will put up the money and then put his deal together and sell it to the people who own the minerals, if that be necessary. Then he has to sit back, with crossed fingers and crossed legs wondering for some months, and in many cases even years, whether or not he is right. The expenditures required to open up a mine in this day of wild inflation are such that he has to be right, and the responsibilities are awesome.

Jan 1, 1958

By M.P. ROY, ASHISH K. VISHWAKARMA, A.K. MISHRA, P.K. SINGH, VIVEK K. HIMANSHU

Principal component analysis (PCA) is one of the dimension reduction techniques widely used to classify data based on features. Ground vibration is a major hazard arising from rock blasting operations, and accurate prediction of the vibration is necessary for designing controlled blasting parameters. Most of the widely accepted predictors of ground vibration consider the maximum explosive charge weight per delay (MCPD) and distance as the parameters responsible for ground vibration, but mining sites with bigger production targets have varying geometrical parameters to suit the excavator utility. Accordingly, other blast design parameters will also have impacts on ground-vibration intensity. A blast vibration predictor considering all the blast design parameters would be complicated, and some of the parameters will have overlapping contributions to ground-vibration intensity. Data classification using PCA is a feasible solution, and regression analysis may be performed to develop predictors using the classified input data. In this study, PCA was used along with multivariate logarithmic regression to predict ground vibration, and the performance of this technique to predict ground vibration was compared with the performances of various existing empirical predictors. The evaluation suggests that the predictor with logarithmic regression followed by PCA performs better than the existing empirical predictors.

Nov 1, 2022

By W. M. Tupper

[The two types of sulfide deposits in the Bathhurst Newcastle area are; (a) epignetic fissure deposits, and (b) massive sulfide deposits. Geological evidence has been variously interpreted to suggest a syngenetic origin, a source bed' origin, or a magmatic hydrothermal origin for the massive sulfide deposits. Sulfides disseminated through the black shales and argillites of the host rocks are enriched in S32 (mean value 22.34, S34. = 5.8 per mil) relative to the meteoritic standard of 22.21, and have a broad spread in range of values. S32/S34 ratios of sulfide minerals from the deposits occur in two distinct groups. The massive sulfide deposits exhibit ratios between 21.88 to 22.05, while the fissure deposits exhibit ratios between 22.18 and 22.21. These results suggest two separate sources for the sulfur, each, however, resulting in magmatic hydrthermal deposition because of the narrow spread of ratios in each group. Granite intrusive into the host rocks of the sulfide deposits have a mean K/A age of 386 ± 10 M.Y. Lead minerals in the sulfide deposits have a mean nodel lead age of 370±20 M. Y. Thus the lead minerals and the granite bodies were emplaced during the same major orogenic event. Sulfide minerals from magmatic hydrothermal deposit have a very narrow range of S32/S34 values, as do those of the Bathurst area. It seems reasonable, therefore, that well homogenized magmatic hydrothermal solutions are the most logical source of the sulfide deposits. Furthermore, the homogeneity of the lead isotopic abundance data gives strong independent evidence that the ores are of a magmatic hydrothermal origin.]

Jan 1, 1960

By Yuemin Zhao, Daniel Tao, Rick Honaker, Maoming Fan

"Froth flotation is the most widely used method of separating fine coal, especially coal with coking properties. However, froth flotation is not efficient for treating ultrafine coal and coarse coal particles. Our previous fundamental test results demonstrated that cavitation-generated nanobubbles around 700 nm in diameter can significantly improve coal and phosphate flotation performance over a wide particle size range. In this study, the effect of nanobubbles on the flotation performance of different particle size fractions of coal was investigated using a bank of 10-L flotation cells, a specially designed 50-mm inside diameter column and a 152-mm inside diameter column. It was found that nanobubbles that were either directly formed on or subsequently attached to the surface of coal particles during the froth flotation process improved flotation efficiency. The use of nanobubbles in a bank of mechanical cells flotation and column flotation significantly increased the flotation recovery at a given product grade. Nanobubbles increased the flotation rate constants of different coal particle sizes. The presence of nanobubbles in flotation slurry could extend the lower and the upper particle size limits for effective coal flotation.IntroductionFor minus 0.6 mm fine coal or minus 0.15 mm ultrafine coal particles, froth flotation is known to be the most efficient and the most cost-effective separation technique. However, flotation efficiency decreases sharply with ultrafine and relatively coarse coal particles. Studies have shown that the low flotation efficiency of ultrafine particles is mainly due to the low probability of bubble-particle collision (Yoon et al., 1989; Ralston and Dukhin, 1999). Enhanced flotation of fine and ultrafine coal can be achieved by increasing collision and attachment probabilities.The top size of particles that can be recovered by flotation depends on the combination of mineral properties and flotation devices. Turbulence in flotation devices is an important factor that affects the stability of bubble-particle aggregates. Even in the flotation of fine particles, bubble-particle detachment can significantly influence the kinetics of flotation taking place in mechanical cells, which provide intensive turbulent agitation (Deglon et al., 1999). Coarse particle flotation is more difficult, because increased agitation is required to maintain particles in suspension and coarse particles are more likely to detach under turbulent conditions (Mankosa and Kohmuench, 2002; Soto and Barbery, 1991). More efficient attachment of particles and improved flotation rate has been observed when tiny bubbles coexist with conventional-sized flotation bubbles (Attalla et al., 2000; Tao et al., 2010; Fan et al., 2010a, b, c, d; Fan et al., 2012)."

Jan 1, 2015

By Irving Hauser

The determination of new ways to cut costs in then times of economic uncertainty is essential in running a successful business. Arco Petroleum Products Company a Division of Atlantic Richfield Company recognized an opportunity for a substantial cast savings in transporting calcined petroleum coke to market by simply building an economical port facility at a location that would enable them to drastically cut their normal rail haulage distance.

Jan 1, 1982

By Steven W. Hunt, Isabelle Lamb, Steven B. Fradkin

Groundwater control is generally an important consideration and significant source of risk during most tunneling projects. Proper baselining of groundwater conditions requires: 1) a thorough understanding of the geological environment; 2) a focused site investigation; 3) identification of construction and adjacent property damage risks associated with inflows and short and long term piezometric level changes; and 4) consideration of contractual issues including restrictions on means and methods and pay items for associated work. This paper provides an overview of groundwater baselining issues and risks based on selected design studies and construction case histories.

Jan 1, 2005

By S. G. McDowell

This paper discusses the utilization of automation to increase productivity of continuous miners. Automation techniques are used during the design stage to decrease the time required and ensure the accuracy of the design. This is followed by automated manufacturing processes to reduce manufacturing time and improve the quality and consistency of parts. Combined, the result is a more reliable machine which can provide ongoing production capability. With the use of automation to enhance operator effectiveness and monitoring machine condition the productivity of machines is also improved.

Jan 1, 1991

By Chee Theng

"Mineral processors know you can put in the best technology in the world but it won’t work optimally without the support of the operators. Conversely, you may have complete operator support but won’t get top results without the right technology. When the two come together, the returns can be phenomenal.The first day of talks at the 68th Annual Colorado MPD Conference, held April 26-28 at The Broadmoor in Colorado Springs, covered the ground on these industry wisdoms.Coming together as a team“Think of the people, not just the lab and the numbers. That makes all the difference,” said Dee Kippers, of FMI Henderson Mine, in her talk on “Process optimization during a market downturn (A Moly MacGyver story).” Kippers told an entertaining story of the journey she and her team took in tackling the issue of an annual spike in iron content in the product at Freeport- McMoRan’s Henderson primary molybdenum mine near Empire, CO.As the metallurgists tried one thing after another — cranking up the iron depressant, adjusting pH with sodium hydroxide and hydrated lime, modifying reagent levels — Kippers found that when she shared her results with the operators, communicated with them on what she was doing and got their input, they were more willing to work with her, and more understanding and supportive of her efforts.The results make the case for getting people on board and coming together as a team. The cost savings from their optimization efforts, with little capital investment, have been “enough to cover the annual salaries of our metallurgy department and then some,” Kippers said.Considering the environmentDavid Lemieux, of Dundee Sustainable Technologies (DST), talked next on “Cyanidefree process for gold extraction,” presenting the results obtained from a demonstration campaign of the company’s novel chlorination process for gold extraction and associated arsenic stabilization process. Developed at an investment cost of C$35 million, they are ready for commercialization, having been demonstrated on the laboratory, pilot and demonstration scales.The DST process is differentiated from the Plattner chlorination process, which was in use from 1851 to 1916, by moderate process conditions of atmospheric pressure and ambient temperature — the result of using sodium hypochlorite solution, or bleach, instead of direct injection of chlorine gas — and new, cheaper materials of construction, such as polymers, plastics, fiberreinforced plastics and Teflon, resulting in lower capital and operating expenditures."

Jan 7, 2018

By Arvid E. Anderson

The paper describes the unique operating features of the Lebanon Concentrator Plant wherein both magnetic concentration and froth flotation are used. Chalcopyrite is selectively floated by the use of dual collectors, Aerofloats and secondary butyl xanthate. Both potassium ethyl xanthate and sodium isopropyl xanthate (dual collectors) are dissolved and emulsified with pine oil for the flotation of the pyrite. Sketches describing the plant operations are presented and plant operating metallurgical results obtained are also given. The optimum production of minerals by the froth flotation process is normally achieved [ ] smooth operating conditions, The process, because of its many variables, becomes an art as well as a science. Therefore, any phase of the operation which will aid the operator in his control of the numerous variables will help produce a smoother operating plant, One of the most important variables which the operator deals with is the addition of reagents, These are usually costly items and should be used discretely with minimum amount of waste, The danger is that ,this emphasis may reduce the reagent amount to a point below that required, or, on the other hand an excessive amount is added, Both conditions usually yield poor results. The drea of the metallurgist is to provide the operator with the tools enabling him to produce a good mineralized froth at all times. Normally the operator has no control concerning the type of reagents which he must use. This has usually been worked out for him in the laboratory and by plant-scale tests. He does have limited authority to control the amounts of the reagents at his disposal. This, I believe, is as it should be. However, the operator should be provided with the best combination of reagents for his particular job. The providing of this combination of reagents for his particular job, The providing of this combination is often difficult, yet it is very important in order to yield good results, With this in mind, the dual collector idea was introduced for the selective flotation of chalcopyrite, and also later for the flotation of pyrite at the Concentrator Plant of the Bethlehem Cornwall Corporation in Lebanon, Pennsylvania, Supplying several types of collectors has given the operator an additional effective tool, even though great variations are encountered in ore tonnage treated and in ore composition, This paper deals with the use of the dual collectors and with the addition of the reagents in the form of a pine oil emulsion, or more accurately, a pine oil suspension. It is hoped that other operators may find the ideas helpful. There does not seem, to me, to be definite scientific fact which would substantiate the necessity for the use of dual collectors. However, in actual operations, the metallurgical results at Lebanon became more uniform with the use of dual collectors, I look upon it as an "insurance policy" which greatly aids the operator during those periods when he is having trouble, One theory has been advanced, i.e. one collector has a greater tendency to float the coarser minerals, whereas the other one may float the finer ones. Consequently, a combination of the two collectors will result in optimum recoveries, There has been some evidence that this is true, but it is not conclusive, on the other hand, the use of a xanthate-pine oil suspension (or emulsion) should speed up the surface reaction of the collector with the sulfide minerals, result¬ing in more uniform flotation, This has definitely happened in our particular case. A more interesting unexplainable observation has also occurred; i.e., the xanthate solution does not appear to lose its strength as rapidly when it is in the form of an emulsion (or suspension), This was first observed when a 50 gallon drum of a 20% ethyl xanthate solution was taken to Wilmington, Delaware, for a laboratory test, using a homogenizer to produce the xanthate-pine oil emulsion. Upon arrival, the drum of xanthate had developed a considerable internal pressure, The relief of this pressure was accompanied by a strong odor, When the emulsion was returned to Lebanon for the plant test orders were issued to release the pressure prior to emptying the emulsion. Nopressure had developed within the drum and there was no unusual odor present, Since this time it has been observed that xanthate pine oil suspensions have greatly decreased the possible decomposition of the xanthate solutions. In fact, suspensions have been exposed for more than a month without apparently effecting their reactions in the flotation plant. On the other hand, we found that the regularly mixed concentrated xanthate solutions, after standing for several days, did not give the same results as the freshly made ones. This effect was greatly reduced by the use of xanthate pine oil suspension (or emulsion)

Jan 1, 1958

By J. A. Organiscak

Longwall mining technological improvements have provided significant increases in productivity over the last 15 years. Longwall productivity is anticipated to continue to escalate with expanded application of automated equipment. Automation technology that will likely be adopted over the next 5 years is memory cut with shearer initiation of shield movement supervised by a couple of face workers. Operations using this technology will most likely relocate many production workers from the face to the outby gate entries and position several face workers outby the shearer, exposing workers to different health and safety risks. These changing risks are primarily related to worker relocation and expected increased production levels. Workers outby the face will most likely have less dust and noise exposure, but will be exposed to other safety hazards associated with outby equipment movement, materials handling, and gate entry ground movements. The face workers will most likely be exposed to higher respirable dust and noise levels generated by the equipment at elevated production rates. Methane gas emission is also expected to increase with faster mining rates. These operational changes and the control technologies needed to reduce redefined longwall worker hazards at semiautonomous longwall operations require examination to maintain the health and safety of mine workers.

Jan 1, 1996

By M. H. Morcali

Pistachio nut shells, an agricultural waste biomass, and Lewatit TP 214, a commercial sorbent, were investigated as adsorbents for the adsorption of platinum from dilute hexachloroplatinic acid solutions. Before the pistachio nut shells were carbonized, adsorption percentage was 65%, whereas Lewatit TP 214 ensured almost 100% adsorption. However, after the pistachio nut shell was carbonized at 1,000° C under an argon atmosphere, the platinum adsorption (%) increased two-fold. The effects of such parameters as sorbent dosage, contact time, temperature and solution pH on adsorption were studied in detail in batch mode. The adsorption equilibrium data were best fitted with the Langmuir isotherm model. The maximum adsorption capacities, Qmax, at 25° C were found to be 38.31 and 33.22 mg/g for the carbonized pistachio nut shell and Lewatit TP 214, respectively. The adsorption of platinum on both sorbents was found to be described by the pseudo-second-order kinetic model. The results indicated that the activated carbon prepared from pistachio nut shells can be effectively used for the removal of platinum from acidic solutions.

By S. Dixon

The Phelps Dodge - PD/PERI Heap2D Model is a phenomenological stockpile leaching model that has been used to investigate the best operating practices for leaching chalcocite. The model was used to investigate the interrelationships of raffinate application rate, aeration rate, raffinate iron grade, acid cures, lift height, crush size, bulk density, air injection spacing and raffinate drip emitter spacing.

Jan 1, 2006

By M. Sears, K. Mohamed, J. Addis, J. Wickline, G. Rashed

To better understand the load shedding and the stress transfer on coal pillars due to room-and- pillar retreat mining in deep cover panels, researchers from the National Institute for Occupational Safety and Health (NIOSH) conducted a monitoring field study. Two sites, at overburden depths of 1,000 ft (304.8 m) and 1,500 ft (457.3 m), were selected in a room-and-pillar mine operating in Southern West Virginia. The deformation and stress changes in the roof and two adjacent pillars at each site were monitored during the retreat mining process. The monitoring results and field observations were used to calibrate large-scale FLAC3D models for each site. The calibrated models were used to assess different sizes of roof bolts installed in deep cover areas. INTRODUCTION Deep cover room-and-pillar retreat mining is an important emerging issue that will intensify in the future as shallower reserves are depleted (Mark, 2009; Chase et al., 2002). During pillar retreat mining, the likelihood of local and/or global instabilities increases due to elevated stress levels near the pillar line because of the abutment loading. In the last decade, approximately 31% of the room-and-pillar mining groundfall fatalities in the United States occurred during pillar retreat mining. Between 2013 and 2017, this proportion increased to 55%, of which 50% of these fatalities were due to falls of roof and rib that occurred during pillar recovery (MSHA, 2018). One interesting piece of information about pillar recovery fatalities was that the victim was nearly always under bolted roof. Sheared and broken #5 (5/8-in), fully grouted rebar bolt failure contributed to three of four fatal roof fall incidents that have occurred in deep cover retreat mines (NIOSH, 2010). This claim raised the following question at the study mine: Is it safe to use a 4-ft long #5 (5/8-in) rebar bolt grade 60 at a depth of cover more than 1,000 ft (304.8 m)? There was some concern about shear failure of the #5 (5/8-in) rebar bolt at a depth of cover over 1,000 ft (304.8 m). To answer the question and to reduce accidents and fatalities caused by ground falls due to room-and-pillar retreat mining in deep cover panels, the National Institute for Occupational Safety and Health (NIOSH) monitored the roof and rib deformation and the change in vertical pressure within two adjacent pillars during pillar recovery. The study was conducted at two deep cover sites in a room-and-pillar mine located in Southern West Virginia that operates in the Lower War Eagle (LWE) seam. The monitored sites were selected at 1,000 ft (304.8 m) and 1,500 ft (457.3 m) depths of cover. In this paper, site-1 represents the monitored site at 1,000 ft (304.8 m) of cover, while site-2 represents the monitored site at 1,500 ft (457.3 m) of cover. For this study, large-scale FLAC3D numerical models were calibrated based on both field observations and instrumentation results. The calibrated models were then used to compare the ground response and the induced stresses of two pillars at instrumented sites 1 and 2. The maximum lateral displacement (roof shift) obtained from the calibrated large-scale FLAC3D models was applied to a small-scale FLAC3D bolted models, the safety factor for axial stresses of the simulated roof bolts was calculated at the deep cover sites.

Jan 1, 2019

By C. J. Burkhalter, H. Andrade, T. C. A. Gardner, J. P. Campbell

During the 1990’s several copper heap leach facilities treating crushed and agglomerated oxide and sulfide ore were constructed in South America. The majority of these facilities have been in operation for at least three years, during which time the operators have been able to monitor the performance of the heaps. The basis for the paper is a compilation of these operators’ experiences, leading to a discussion of the lessons learned over the past decade. Several key geotechnical issues are examined, focusing upon the integrity of the ore, drainage material and pipe network, along with the success of any inter-lift liners.

Jan 1, 2002