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By George M. Potter

Under contractural arrangements with the Bureau of Mines, Mountain States Research and Development, Inc. (MSRD) completed a technological investigation to determine the feasibility of in situ mining of metal commodities other than copper and uranium, The study was based upon available literature and experience. The selection of potential candidates for in situ mining was influenced by economic importance, probable amenability to in situ methods, and environmental considerations. Four metals (or metal pairs) were chosen for feasibility studies: aluminum (with a copper byproduct), gold-silver, and manganese were recommended for further study and action; cobalt-nickel was also recommended contingent upon preliminary laboratory leaching and recovery investigations and field geohydrological work. Mining and recovery plans and an economic evaluation are included. Other metals with potential for in situ leaching are lead/ zinc, molybdenum, and vanadium.

Jan 1, 1981

By M. E. Rossi

This paper discusses the use of Conditional Simulation (CS) models to provide mill feed grade profiles for different time periods. The conventional approach of classifying block estimates as ore or waste generally does not adequately represent dilution, lost ore and the anticipated grade control data, including variability of mill feed from the pit and possible stockpiles. The detailed simulation of grade control practices can be done, but at the Pre- or Feasibility stage of the project may be impractical, since drawing dig limits on multiple benches is tedious and time consuming. Using the Feasibility Grade Control (FGC) method as developed by the Centre for Computational Geostatistics (CCG, University of Alberta-Edmonton), the CS models can be processed quickly to establish dilution and lost ore, and predict daily or short-term feed to the mill. The simulated nodes can be aggregated into selective mining units with adequate representation of likely geometries to be recovered from the pit, to mimic anticipated selectivity. An example from a large copper deposit is shown. The study provides an estimated stream of tonnages and grades fed to the plant by mining periods of interest and based on a specific mine design and schedule. The resulting cash flows support the economic and financial analyses of the Feasibility Study; also leads to improving mine schedules; and aids in developing blending schemes if necessary. INTRODUCTION The conventional approach of separating mineralized material into ore or waste categories does not always include a realistic amount of dilution and ore loss. Also, often it does not provide a good estimate of the grade that will be fed to the mill. If the grade control estimates are unbiased, they will over the long run represent the long-term average of grades fed to the mill; but the anticipated variability of mill feed from the pit and stockpile sources may be misrepresented. Some references on traditional grade control implementations can be found in Chunnett (1982); Davis et al. (1989); Srivastava et al. (1992); and Nowak (1992). Alternative methods based on economic variables improved significantly on the purely grade-based control methods, see Douglas et al. (1994). Further developments involved the use of geostatistical conditional simulations (CS) and profit models, which in several cases have been successfully implemented (Aguilar and Rossi, 1996; Rossi, 1997; Deutsch et al., 2000; Norrena and Deutsch, 2002; Neufeld, 2005; Jewbali and Dimitrakopoulos, 2009). But they can be impractical, mostly due to the lack of understanding of the methodology involved; even if semi-automatic dig limit drawing is implemented, there is always a need for is tedious and time consuming checking and corrections, even if using a single profit model derived from the simulated grades.

Jan 1, 2019

By MUSTAFA ERKAYAOGLU, ENVER YILMAZ

Coal mining is likely to sustain its critical role as energy requirements are increasing. While surface mining exploits coal seams near the surface, underground mining techniques are crucial for extracting deep coal reserves. Longwall mining is one of the most common methods used in underground coal mining operations. This paper introduces a data-based framework — including data collection, data analysis and the interpretation of operational data — for understanding the system efficiency of a longwall shearer. Operational performance is evaluated by the time between arrivals (TBA) and duration of the shearer stoppages, shearer drums’ reversal time, cutting speed and flit speed on daily production in a longwall top coal caving (LTCC) mine. A discrete event simulation model is developed to represent the bidirectional cutting sequence of a longwall shearer.

By Carlton M. Ray, William P. Levy, Thomas Lindberg

"The District of Columbia Water and Sewer Authority (DC Water) is implementing its $2.6 billion DC Clean Rivers Project to reduce combined sewer overflows to the District’s receiving waterbodies and mitigate chronic sewer flooding in District neighborhoods. The First Street Tunnel project is a major component of the DC Clean Rivers Project, designed to mitigate sewer flooding and basement backups in the District’s historic and densely populated Bloomingdale neighborhood. Bloomingdale has been historically affected by sewer flooding and was severely impacted by four storms in the summer of 2012 that caused significant damage to homes, the environment and public property. As a result, DC Water accelerated the design and construction of the First Street Tunnel in order to mitigate the effect storms have on the undersized sewers serving the neighborhood. The infrastructure designed to mitigate flooding, including the tunnel, are located within the highly urbanized neighborhood – with some structures being less than ten feet from residents front door steps. The success of a large public works project of this magnitude and in this unique location depends on a well informed and supportive public. With the local community impacted by flooding but concerned about heavy construction impacts, this paper details the components of a successful public outreach plan and lessons learned throughout the design and construction process. Early identification of community mitigation, working cooperatively with stakeholders and frequent dissemination of accurate information required the project team to establish a culture of problem solving collaboration with the community. BACKGROUND Chronic Flooding in the Northeast Boundary Sewershed The Northeast Boundary sewershed, in which the Bloomingdale neighborhood is located, is served primarily by a combined sewer system and has a long history of chronic flooding problems during moderate to severe storm events. The sewer system that serves the Northeast Boundary drainage area was constructed by the Federal Government in the late 1800's when developed areas of the District terminated at what is now Florida Avenue. Since construction of the system, population within the sewershed area has grown at an exponential rate. In meeting the growing needs of the population, the District experienced development that transformed previously low-density rural areas into new communities. Impervious areas have increased drastically since the sewer system was constructed and consequently, the existing sewer system does not have the capacity to convey storms with return frequencies beyond the 2-year storm without flooding. As a result of the capacity limitations, many of the low-lying areas have become chronic flooding areas due to the surcharging of sewers."

Jan 1, 2016

By Hemant Agrawal, Arvind Kumar Mishra

Rock breakage using blasting is one of the important operations of the mining industry. The delay timing decides the initiation sequence of holes in the blasts and is a crucial factor to improve the overall blast performance. Blast-induced ground vibration is an undesired yet unavoidable outcome of blasting. Peak particle velocity (PPV) is commonly used to measure the magnitude of blast-induced ground vibration. Channelization and better utilization of explosive energy delay are provided between blast holes using initiating systems. The use of different initiation systems even on the same site results in a very significant difference in the values of PPV generated. Due to scattered delay timings of pyrotechnic detonators, the scaled distance predictor equations obtained become unreliable. The error/scatter in delay timing leads to overlapping of holes and hence increases in maximum charge per delay. In this paper, an analytical approach has been discussed to measure the overlapping of holes during blasting with initiation systems having inherent cap scatter. The analytical approach will be calculating the probable overlapping of holes due to scatter in delay timing and will help blasting engineers to understand the variation in maximum charge per delay due to pyrotechnic based initiating systems. In this study, a total number of 102 blasts were conducted using different initiation systems at two different opencast coal mine and 221 corresponding blast vibrations events were recorded.

Nov 10, 2020

By D. K. Denton, M. J. Friedel, D. F. Scott, T. J. Williams

Spokane Research Center personnel have been investigating the use of seismic tomography to monitor the behavior of a rock mass, detect hazardous ground conditions, and assess the mechanical integrity of a rock mass affected by mining. Seismic tomography can be a valuable tool for determining relative stress in deep ( > 1220 m) underground pillars. If high-stress areas are detected, they can be destressed prior to development or avoided. High-stress areas can be monitored with successive seismic surveys to determine if stress decreases to a level where development can be initiated safely. There are several benefits to using seismic tomography to identify high stress in deep underground pillars. The technique is reliable, cost-effective, efficient, and non-invasive. Also, investigators can monitor large rock masses, as well as monitor pillars during the mining cycle. By identifying areas of high stress, engineers will be able to assure that miners are working in a safer environment.

Feb 24, 1997

By Nicolin Govender, Pramod Kumar, Raj Rajamani

Mill power models have been used in a variety of ways in industrial practice since power directly equates to throughput and fineness of ground product. We first start with Hogg-Fuerstenau Power Model and show how this model successfully predicted the power draw of many grinding mills in several mining operations. Then, we show how this model was on the verge of being able to predict the influence of lifter design on power draw. Next, we describe the discrete element model and how it overcame the issues faced by the previous power model. Using a DEM software known as Millsoft, we show the influence of lifter design geometry on power draw and analyze the power draw of rubber lifters versus the steel lifters via several case studies. As years passed, the two-dimensional discrete element model imbedded in Millsoft is superseded by three-dimensional discrete element method. Due to the gigantic computational power of graphic processing units, new computational codes that can do the tumbling motion along the entire length of the mill has come about. Here, we show the predictive capability of Blaze-DEM for ball and SAG mills.

By S. J. Neethling

The flotation froth structure and motion determines the amount of entrained gangue that is collected to the concentrate. Despite this important role in the overall performance, the behaviour of the froth is still ill understood. To date, predominantly empirical models have been developed to describe entrainment. A fundamentally based model is described and used here in an attempt to improve the understanding of entrainment. This general froth simulator (UMIST FrothSim) allows the modelling of a wide range of flotation conditions, as it takes account of a large number of the physical phenomena that occur within flotation froths. The model firstly describes gas motion and bubble coalescence, and the water motion based on gravitational, viscous and capillary effects. The motion of the solids distinguishes between various solids classes based on hydrophobicity, particle size and density and models them by including the effects of Geometric and Plateau border dispersion, particle settling and the motion of the water. The aim of this paper is to show the applicability of this model to explain the observed entrainment and collection of gangue. This is done by comparing model predictions with the experimentally observed relationship between the gangue and water recoveries. The model predicts the identical trends, which are explained in terms of the interaction between the linear effects of water motion and hindered settling and the non-linear effect of particle dispersion.

Jan 1, 2001

By R. K. Simpson, C. S. Eldridge, M. H. Tyler, J. P. Hodgkison

The WMC Olympic Dam Operation in South Australia is an integrated site, involving brown fields exploration through to production of copper cathode, uranium oxide, gold and silver bullion. The Geology and Analytical Services (GAS) Department reflects this totality and, therefore, is perhaps a unique construct in the industry. It comprises Geology, the Metallurgical Laboratory and the Analytical Laboratory, offering a single point of contact in matters of metal discovery and tracking through mine design, production, beneficiation and final product certification. This structure promotes value adding by removing traditional barriers between groups that can deliver more, collectively, than as individual units. This approach to value adding by bringing disparate groups together is echoed in each of the three sections where enhancements in the traditional value adding activities have been delivered by multi-skilling and encouraging overlapping involvement.

Jan 1, 2002

By Scott Lewis, Andrew Kositsky

"INTRODUCTIONThe South Napa Earthquake of 2014 caused ground motion at numerous reinforced concrete-lined (shotcrete-lined) winery tunnels in Napa County and Sonoma County, California. The occurrence of seismic ground motion at these tunnel complexes, known as wine caves, presented an opportunity to reevaluate seismic performance of reinforced concrete and reinforced shotcrete lined tunnels. The authors of this paper updated the most recent comprehensive compilation and evaluation of case studies by Power and others (1998), which correlates peak ground acceleration (PGA) at tunnel sites to damage. For this update, the authors evaluated the seismic performance of 31 wine caves near the South Napa Earthquake epicenter; including some of the 90 wine caves they designed since 1991, some caves designed by others, and additional caves constructed by contractors that they frequently work with. Tunnel designers can use the new data presented in this paper to help evaluate the usefulness of detailed seismic design analyses. THE SOUTH NAPA EARTHQUAKE The South Napa Earthquake occurred at 3:20 AM Pacific Daylight Time on August 24, 2014. Figure 1 shows the approximate location of the epicenter, the measured/estimated PGA contours, and the location of wineries with wine caves added to the database where the PGA was at least 0.2 g. The epicenter was along the West Napa fault, about 5 miles south-southwest of downtown Napa, California. The earthquake moment magnitude was 6.0, and measured/estimated PGAs were up to about 0.7 g. The duration of strong shaking was about 10 seconds. This earthquake was characterized by right lateral strike-slip fault movement, ground surface rupture, and after slip at the ruptures. Increased surface water flows were observed at seven creeks after the earthquake. Groundwater level rises of up to 5 feet were observed in Sonoma County wells after the earthquake. The earthquake was the largest seismic event in the San Francisco Bay Area, which includes Napa and Sonoma Counties, since the 1989 Loma Prieta Earthquake. The Napa event caused an estimated $400 million in damage. This damage included moderate to extensive structural damage to older commercial buildings and to some newer buildings in downtown Napa. This damage resulted from ground motions, subsequent fires, and failed underground utility systems."

Jan 1, 2016

By Zhonglin Ye, Guangping Dai, Ba Zhang, Yonggang Wei, Shiwei Zhou, Bo Li, Hua Wang

Decreasing copper content in slag is critical for improving copper recovery, where apparent viscosity is the main factor affecting the separation of matte/copper from the slag. The viscous behavior of copper converter slag was investigated during reduction process in this paper, and its non-Newtonian viscous behavior and shear thickening characteristics were clarified. The effects of silicate structure and solid particles in the melt on the slag apparent viscosity were investigated. As slag cleaning proceeded in an electric furnace, the magnetite gradually transformed into ferrous oxide, increasing the FeO/SiO2 ratio. With this ratio increased from 1.2 to 2.0, the slag structure was simplified, and its apparent viscosity decreased from 0.26 to 0.12 Pa·s at 1523 K. The iron phase was excessively reduced to metallic state; the slag contained metallic copper-iron alloy particles, increasing apparent viscosity. The apparent viscosity and phase structure of the slag corresponding to the iron phase reduction process were analyzed in detail; the results obtained in the present study are of great significance to the reasonable control of the converter copper slag cleaning process.

Nov 7, 2022

By B. J. Vorster

Introduction The South African Iron and Steel Co. Ltd., in Sishen, operates a large iron ore mine in the Cape Province of the Republic of South Africa. The mine is about 600 km (370 miles) west of Johannesburg. Its annual capacity is 100 Mt (110 million st) of ore and waste. Present production is 60 Mt/a (66 million stpy). The mine operates continuously six days a week. Primary equipment includes 55 154 t (170 st) Wabco and Unit Rig trucks and 14 P&H shovels. During 1979, a feasibility study into the application of a trolley assist system was launched. This was due to the escalation in diesel fuel costs and the appeal by the South African government to reduce the use of fossil fuels. Tests and economic evaluations proved the system technically feasible. The estimated discounted cash flow return exceeded 50%. Diesel fuel consumption would be reduced by 120 ML (31.7 million gal) in the next 10 years. The construction of 7.7 km (4.8 miles) of line and the conversion of 66 154 t (170 st) trucks were completed in March 1982. System description The conventional 154 t (170 st) diesel electric rear-dump haul-truck is equipped with two direct current wheelmotors in the rear axle. They drive the rear wheels through planetary gearboxes. A 1.2-MV (1600-hp) diesel engine and an alternator is used to power the wheelmotors. The trolley assist system consists of an overhead power line, a current collector mounted on the truck, and add-on control equipment where external electric power is routed by way of the current collector to the motorized wheels. The diesel engine is used to propel the truck on level sections. On inclines, the wheel-motors of the truck are coupled by way of a current collector to the externally generated electrical power supply for propulsion. The diesel engine, having lower output than the wheelmotors, limits the truck performance. Previously, maximum output was required from an engine on inclines. By supplying the wheelmotors from a virtually unlimited outside electric energy source, the truck performance is enhanced to the extent that speed is increased by 46% and fuel consumption reduced by 75%. System design The unique operational requirements of this mine rendered the already proven trolley pole system useless. Minimum loss in truck mobility and flexibility was required. Overhead lines and substations were required to be relatively light and portable. This enables fast repositioning of a line with no loss in material. These unique specifications set the base for the design of the Sishen system. Steel I-beams, 203 x 203 mm x 52 kg/m (8 x 8 in. x 35 lb per ft) with lengths varying from 8.3 to 11.3 m (27 to 37 ft), mounted on base plates about 4 x 2.6 m (13 x 8.6 ft) were used as masts. The masts were erected at about 50 m (165 ft) and the base plates covered with about 12 t (13 st) of iron ore to keep them absolutely stable. Results from the pilot installations indicated that using single cantilever cross arms for insulator and overhead conductor suspension was not practical. The tension in the overhead varied too much with temperature changes, causing too much sag in the lines. There had to be a positive and negative conductor. It was decided to suspend each polarity on an independent cantilever and keep the conductors under constant tension by weights acting through a two-to-one pulley tensioning arrangement. For each overhead conductor, a standard 160-mm (6.5-sq in.) grooved copper railway conductor was used. To obtain the necessary current carrying capacity, two of these conductors are used in parallel per pole. Insulators are rated at 4 kV and are of the composite type. An 11-kV three-phase line, supported by the pantograph line masts on the opposite side of the dc line, feeds the rectifier stations. The rectifier stations consist of an 11-kV to 860-V, three-phase 1.46 MVA transformer and a three-phase diode bridge rectifier. The output voltage is 1200 V do earthed through a current limiting resistance network so that the line po-

Jan 4, 1986

By Maurice Grieves

GC. Waterman Mr. Grieves' paper on "Shaft Sinking Today--A Boring Business Tomorrow" in the Dec. 1981 issue of MINING ENGINEERING is an excellent description of recent improvements in speed and costs of shaft sinking. However, shaft boring techniques are not a recent development. In 1935-36, the Idaho Maryland Co. (gold), Grass Valley, CA, bored the vertical 1.5-m-diam Idaho No. 2 ventilation and supply shaft to a depth of 346 m. The equipment was designed and perfected by Branner Newsome and was, I believe, described in "Transactions." Pickands Mather later bored a 1.8-m-diam shaft to a depth of about 305 m using Newsome's design. The Idaho No. 2 shaft cut through hard gabbro, diabase dikes, soft serpentine, very incompetent ankeritized serpentine and a strong fault zone. The completed shaft did not require timber support; the fault zone was cemented. Equipment consisted of a rotating 1.5-m or 3-m core barrel with a slotted bottom which cut a 76-mm kerf. The cutting agent was chilled steel shot introduced into the slot as needed. The driving mechanism and core barrel were lowered into the shaft, the former secured to the wall and the inshaft "engineer" operated the motors which controlled core barrel rpm and advance. After an advance of 1.5-3 m the equipment was lifted out of the shaft, a half(?) stick of powder cut off the drilled core, and it was hoisted to the surface with a cable attached to an eye bolt at the tope of the core. A "shift" consisted of three men: hoistman, equipment operator (down the shaft), and a surface laborer. Advance was variable as equipment and techniques were perfected. Near the end of the job advance was, as I remember, 1.5-3 m per shift. Costs were, as I recall, about $115/m. Up to 4 m cores were lifted out in one piece and swung to the dump by a stiff leg derrick. The Newsome equipment was relatively inexpensive to build and operate and his method should be (more than?) competetive with the methods described by Grieves. W.E. Hawes The author, in mentioning the South African developments of the cactus grab, ignores the parallel development of the Cryderman mucker in this hemisphere. Perhaps a slightly longer history of blind hold drilling would have been in order. Blind shaft boring got a major boost at the Nevada Test Site, as part of the nuclear weapons development, when it was essential to be able to quickly assess depth for weapons testing. One of the early civilian attempts to utilize this technology occurred when Kerr McGee drilled the shaft at the Section 19 Mine at Ambrosia Lake, NM. This twin masted drill rig belonged to a subsidiary of Kerr McGee, not Shaft Drillers. This was a difficult hole, due to bentonitic shales that decomposed. Later advances in drilling fluids eliminated this problem. The Conoco project referred to is not entirely correct, and needs minor amplification: The depth of the development (not pilot) shaft drilled was 684 m, at a diameter of 3.05 m, with a 2.16 m ID hydratatic casing being installed to a depth of 669 m. Conoco Inc., not Challenger, executed the drilling, however Conoco did use Challenger Drilling Company's Rig 14-S. Rig 14-S is unique in that it is specifically designed for shaft drilling, rather than being an oil field rig used for this service. All work was planned and directed by Conoco personnel. Deviation of the aforementioned shaft from vertical was 31 cm. Two smaller shafts (pilot shafts) were drilled with the same rig. These smaller ones were drilled 1.8 m in diameter, to depth of 665 m and cased with .91-m-diam casing, to depth of 650 m to be used as pilot holes for 5.5 m diameter shafts. The total elapsed time for all drilling, casing, cementing, and rig moves was 50 weeks. The constraints mentioned of vertical accuracy, torque, wall collapse, rig set up time, lining time etc., pumping out, etc., may not be as serious as the author implies. First, vertical accuracy: The record achieved by Conoco indicates that with reasonable care, good accuracy can be obtained, primarily by having a fair amount of weight in tension, rather than on the drill bit. Second, the amount of torque that can be applied to the drill stem has been greatly increased by the introduction of larger diameter drill stems, such as the new Hughes rig uses. Third, risk of collapse of shaft walls is minimal with the proper mud program. Basically, the walls are supported by the weight of the mud and it is not removed until some type of casing is installed and grouted in. Here in the real challenge of blind drilling shafts to devise a more economical method of lining bored shafts than using steel casing. The remaining issues were minor at Conoco, provided adequate planning and scheduling takes place. An excellent paper, "Shaft Drilling--Crownpoint Project" by Hassell H. Hunter, presented at the Fifth Uranium Symposium in Albuquerque in Sept. 1981 contains details of this project. A combination of blind boring, with enlargement by either mechanical means (boring machine, or tunneling type shield) or slabbing down, with muck removal through a larger bored shaft would seem to be the future trend in shaft development. The economics, especially for wet conditions, favor this concept over conventional sinking, as has been demonstrated at Kerr McGee --Churchrock, UNC--Churchrock and Conoco at Crownpoint.

Jan 3, 1983

By Steve Kral

The Society for Mining, Metallurgy and Exploration’s origins can be traced back to 1871. This was when 22 Pennsylvania coal mining engineers founded the American Institute of Mining Engineers (AIME). The organization’s objective was to “promote the arts and sciences connected with economic production of the useful minerals and metals, and the welfare of those employed in those industries by all lawful means.” Metallurgy and Petroleum were added to the AIME name in 1919 and 1956, respectively. Divisions of AIME were formed throughout the following years in recognition of the increasing trend toward specialization among mineral industry engineers. At the time, SME’s divisions consisted of the Coal Division (1930, now known as the Coal and Energy Division), the Industrial Minerals Division (1935), the Mineral and Metallurgical Processing Division (1948) and the Mining and Exploration Division (1949). The Environmental Division was created in 1997.

Jan 1, 2007

By J. M. Mutmansky, Y. J. Wang

The usual method employed to determine the direction of flow in a connecting airway in advance is to conduct a survey between the two existing nodes being connected by means of the new airway. It is then assumed that airflow will take place from the node with higher pressure to the node with lower pressure. The purpose of this paper is to examine this direction-of-flow problem -- using properties of the system characteristic curve for a two-terminal network -- and specify some conditions that ensure that flow will take from the higher-pressure node to the lower-pressure node. It is concluded that the only requirement is that all characteristic curves of fans in the network should be strictly decreasing. Five numerical examples illustrate some important properties of the direction-of-flow problem.

Jan 1, 1999

By M. E. Gershon

I would like to congratulate Professor Gershon on an idea that is obviously valuable and is certainly new to me. It has, however, to be further developed, in that one can get fallacious results by limiting oneself to positional weights. In the example problem, the positional weight of one block was 8.6 (the 8.0 value in the paper was incorrect) for 36 units in the cone, for a mean block value of 0.239. The positional weight of the second block was 4.4 for 15 units, for a mean block value of 0.293. Surely one would expect the second block to be rated higher. Additionally, the time value of money adjustment cannot be determined by depth, because the time that a block is mined is determined by the mining sequence, not depth. Figure 1 shows a slightly altered version of Professor Gershon’s pit. The overall value of the pit is the same, as are the total values under each of his blocks. The values in the right-hand cone have been reversed top to bottom, and the values in the rest of the pit adjusted to keep the central cone total unchanged. All values have been multiplied by 10. Figure 2 shows the sequence of mining, at three blocks per year, for Professor Gershon’s pit, and Fig. 3, the sequence for a pit under the other block. Table 1 shows the value and discounted value (157. ) of Professor Gershon’s pit, and Table 2 shows similar values for the second pit. It is apparent that the second pit schedule is more valuable than the first.

Jan 12, 1987

By Lee R. Kump, Sarma V. Pisupati, Peter L. Rozelle, Alan R. Larson, Timothy S. White, Nicholas A. Crescenzo, Maureen D. Feineman

The Mercer Clay bed in central Pennsylvania has produced feedstocks for the refractory industry in the USA and has also been investigated as a source of alumina and lithium. Developments in global markets for these commodities, as well as rare earth elements, have led to their classification as critical minerals in the USA, in turn renewing production opportunities for the Mercer Clay resource. The work reported here includes a review of the clay types and minerals involved, as well as past mineral processing and extractive metallurgy test work, and reports new research results from renewed investigation of the deposit as a polymetallic resource. This renewed work has found lithium contents that exceed 1,000 ppm, lying directly below the overlying Mercer coal, where the alumina content ranged from 32 to 34 wt%. Total rare earth concentrations were somewhat lower than have been found elsewhere in the region, and the highest contents were also found to be stratigraphically close to the coal. Further work is required to establish the mineral hosts for lithium and rare earths and to define the extent of enriched alumina, lithium, and rare earth concentrations.

Jul 22, 2021

By Jack R. Miller

This session has been organized to suggest to you that the development of direct reduction is important to the iron ore mining and coal mining industries. The papers presented this morning will include a discussion of the costs of making direct reduced iron (DRI), the iron ore and coal supplies needed to produce DRI, the financing of direct reduction (DR) projects and, probably most important, the impact of the DR development on the iron ore and coal industries. For starters, this opening presentation offers a brief statement about DR practice and DRI, under the title that should surprise no one: "Direct Reduction: What Is It?" There is always the chance? that a brief statement may become long and complicated. But, by mixing some slides borrowed from Hal Lownie with a larger number of photographs accumulated from other sources, I hope to avoid such pitfalls.

Jan 1, 1978

By J. V. Ghelarducci, M. A. Sharpe, D. G. Chedgy

This article presents a novel design, called the Climax, High Capacity Processor (HCP), for pre-combustion cleaning of coal. This design is particularly suitable for the plant capacities of 400 ~ 660 TPH. The HCP is different from the conventional designs with an equivalent throughput in three major aspects: 1) the use of one large capacity HM cyclone to separate coarse and intermediate raw coal in a single circuit; 2) the elimination of the conventional secondary magnetics recovery system by use of the high efficiency Climax, magnetic separators; 3) the use of "single line" piping with a minimum requirement of ancillary devices. In comparison with conventional designs with similar capacity, the HCP plant costs much less in capital investment, operation and maintenance.

Feb 24, 1997

By N. Arbiter

Fracture under low velocity free-fall and double impact, and under slow compression have been-investigated. The pattern of breakage and the size distribution of resulting fragments for sand-cement and glass spheres have been determined. Photoelasticity methods were used to simulate the stress distributions in free-fall impact in order to explain the observed patterns of breakage. Oblique fracture planes, occurring only in free-fall impact, develop along lines which coincide with the trajectories of principal compression as determined by mathematical analysis Breakage efficiencies for different modes of fracture were compared for both types of spheres. For the same specimen and loading system, static loading and low velocity dynamic loading induce geometrically similar stress fields resulting in reasonably similar fracture patterns and shapes of fragments.

Jan 1, 1968