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By S. Hamilton

Borates are essential to life, and to many products that are essential to an acceptable standard of living. They occur naturally in seawater at an average concentration of five milligrams of boron per liter. Fresh water lakes, rivers, streams and ground water generally have concentrations of about one milligram boron per liter. Borates are also present in soil at concentrations ranging from 0.1 to three milligrams of boron per kilogram. Because most of that boron is locked into insoluble minerals, clay or organic matter, boron deficiency is more widespread than boron enrichment. Borates evaporate into the atmosphere from seawater, rain, snow and hot springs. In rain and snow, natural boron concentrations range from 0.002 and 0.1 milligrams boron per liter. All told, boron moves through the atmosphere at a rate of 5 Mt to 7 Mt/a (5.5 million to 7.7 million stpy).

Jan 1, 2005

Ion exchange (IX) has been in use for a long time, references to IX are made in The Bible, Exodus Chapter 15 vs. 22-25 ?and the waters were made sweet?.1, 2 Aristotle noted a reduction in the salt content of water when passed through certain types of sand, a phenomena probably associated with ion exchange characteristics of zeolites. Some major milestones in IX development include; ? ~ 1400 BC Moses ? ~ 330 BC Aristotle ? 1850 the discovery of the IX process3 ? 1909 Gans proposed zeolites for gold recovery ? 1935 sulfonated coals used for water softening ? 1939 copper recovery from Rayon Production ? 1940 The Rare Earth Project at Ames ? 1952 first South African U IX mine at West Rand (first SX of U using amines 1957) ? 1954 first U IX in USA at Shiprock Mine N.M. USA. ? Late 1950?s U IX over 50 fixed bed systems installed in North America ? 1950?s-1960?s FSU introduce U IX both fixed bed and RIP ? 1968 Gold IX (RIP) Muruntau Uzbekistan (CIL wasn?t commercialized until 1973) ? Mid 1970?s FSU & USA independently develop ISL combined with IX for U recovery ? 1978 Chinese Tungsten IX commercial Plant ? 1984 Uranium extraction from seawater ? 2004 Recovery of Gallium using hydroxyamic acid ligands ? Current ? Commercialization of IX for recovery of gold thiosulfate. Ion exchangers can be naturally occurring or synthetic; the majority of ion exchange materials in use today are synthetic resins based upon organic polymers such as polystyrene or methacrylate. Into more modern times the use of ion exchange for metal recovery was first proposed for the recovery of gold using zeolites in 1909.4 In 1939 copper was being recovered from the manufacturing of Rayon using ion exchange5 a development that continued applicability through to current times in the production/recovery of copper and nickel in ammoniacal leach processes. In early 1949 researchers at the Rohm & Haas Company discovered that hexavalent uranium existed as an ionic complex in sulfuric acid leach liquors, and that quaternary ammonium anion exchange resins exhibited a high selectivity for this ionic species6 The first commercial application of this technology went on-stream in October 1952 at the West Rand Consolidated Mines, Ltd operation in South Africa. 7 Ion Exchange has been applied for the recovery and purification of a range of metals;8 ? Uranium, Thorium and transuranic elements ? Rare Earths ? Gold, Silver and platinum group metals (PGM?s) ? Chromium, Copper, Zinc, Nickel, Cobalt ? Refractory Metals; Molybdate, Vanadate, Tungstate, Rhenium Mercury.

Feb 27, 2013

By G. A. Johnson

Basic management principles will be discussed (as they apply to minerals education efforts), especially in light of the changing nature of volunteerism in today’s society. Also, the “minerals education tree” will be presented, along with public opinion / public policy realities.

Jan 1, 2001

By A. J. Basu

Geotechnical design plays a key role in mine design. I A proper geotechnical design provides a safe working environment and facilitates efficient mining operation. There are mainly three design approaches I) judgmental, based on observational and experiential facts, 2) empirical, based on empirical design formulae, and 3) analytical, incorporating numerical analysis. Most design applications are based on the design methods one and two as mentioned earlier. However, complexities arise in deep underground mining operations and deep open pit mines. These complexities and difficult geological environment introduce more uncertainties and simple empirical formulae would not be adequate as a design tool. These situations require numerical modelling and analysis of the design problems including interpretation of the results obtained from the analysis. There are several tools available for performing the numerical modelling and analysis. A brief review of the available tools was addressed earlier (Basu and Kuruppu, 1995). The authors selected ANSYS (a general purpose finite element analysis tool) for use in mining geomechanics and geotechnical design. This paper includes several examples demonstrating the applicability of this software in designing structures applicable to mining geomechnics. The authors hope that the design examples will demonstrate the use of the numerical modelling and analysis application in excavation design.

Jan 1, 1996

By L. Gertsch, R. Gertsch

Mechanical mining is steadily gaining usage in the mining industry. A variety of machines currently finds employment: tunnel boring machines, roadheaders, continuous miners, surface miners, and augers. These machines have advantages compared to drill and blast mining methods, including increased safety, lower cost, uniform muck size, and accurately sized openings. A century of experience with mechanical methods has already paid dividends to the coal industry. Current trends guarantee eventual development of true general-purpose hardrock mechanical mining machines. Mechanical miners will become integrated mining systems and will determine the design of mines, when several significant challenges have been met.

Jan 1, 2001

By Steve Kral

Conference themes are usually chosen by organizers to reflect the current state of the industry. The Colorado Section MPD came up with what may be the most appropriate theme of a mining conference during the last few years. The local SME MPD section’s theme of its 56th annual conference was “The Wild, Wild World of Mining.” The current boom can be felt in all aspects of the industry, including exploration, mining, processing, sustainability, and economic and political issues. Each of the 25 speakers at the conference, held in Colorado Springs, CO, touched on how the boom has impacted each of those aspects. The meeting attracted about 110 people from around the world.

Jan 1, 2006

By Syd S. Peng

In the past few years, the numbers of underground coal mines in this country using longwa11 mining method have been dramatically increased. In the latest count there are approximately 90 10ngwa11 faces amounting roughly 8% of the total underground production. Meanwhile, shortwall mining adapting longwa11 powered supports to 'coal mining and handling systems in room and pillar mining is also gaining importance in the Appalachian coal field. Although there are only 7 operating shortwall faces so far, indications are that it will be increasing steadily. Modern longwall faces are highly mechanized and productive. One of these key elements that contribute to the success of modern longwall mining is self-advanced powered supports. There are several types of powered supports. Frame type is two sets of one to four hydraulic legs supporting beam-type roof canopy and floor base. However, chock type is more popular and connected to broad roof and base structure. Shield supports were introduced recently but proved to be highly successful (1). A shield support consists of two hydraulic jacks mounted between a base plate and a gob shield. The base plate is hinged to gob shield which is in turn hinged to roof canopy.

Jan 1, 1977

Instabilities occurred as a result of climate changes caused to investigate the rock behavior dependency to temperature changes, in this paper. In the natural earth condition, the phase transition of pore water has known to be the most effective factor causing different rocks mechanical properties due to temperature changes. So, the temperature range of [-30, 30]°C is selected in laboratory tests of this study. P-wave velocity, unconfined compressive strength (UCS) and elasticity modulus of rocks at different temperatures are studied by developing a temperature adjusting apparatus. The tests were performed on three rock types. The results show that firstly, the temperature reduction and pore fluid freezing improves these rock?s mechanical properties. Secondly, the dependency of rock properties to climate changes depends on the type and shape of its porosity as well as porosity percent. The improvement of rock mechanical properties in jointed rocks exceeds rocks with spherical pores. Finally, maximum changes in rock?s properties occur at [-10, 0]°C, which includes the phase transition of pore fluid. Keywords: Temperature; Rock Mechanical Properties; Pore Fluid; Porosity.

Feb 27, 2013

By Jafar Safarian, Manish Kumar Kar, Ahmad Hassanzadeh, Casper van der Eijk

To minimize the carbon footprint in the industrial valourization of bauxite residue, hydrogen was used as a reducing agent. The current study experimentally investigated hydrogen reduction of bauxite residue-CaO sintered and self-hardened pellets at 1000 °C, along with magnetic separation of these reduced pellets for iron recovery. Calcium was introduced to bauxite residue to form leachable calcium aluminate phases with the existing alumina in bauxite residue. This involved the addition of either CaCO3 or a mixture of CaO and CaCO3 while maintaining the fixed Ca content during pelletization. The former underwent sintering at 1150 °C, while the latter was self-hardened through the cementing effect of CaO in exposure to moisture and air. Both types of pellets were reduced in a thermogravimetry furnace at an elevated temperature under similar conditions. The pellets were characterized by the X-ray diffraction (XRD) method and scanning electron microscope (SEM) coupled with energy dispersive spectroscopy (EDS), and their physical and mechanical properties were measured via standard techniques. During hydrogen reduction, a negligible amount of gehlenite ( Ca2Al2SiO7) was formed in the self-hardened pellets, while this phase dominated in the sintered pellets. Alumina in the bauxite residue converted to mayenite phases during reduction in both the pellet types; however, reduced self-hardened pellets had a higher amount of alumina containing mayenite leachable phase. The two pellets showed similar reduction behaviour, while different chemical, physical, and mechanical properties were observed. The magnetic properties of milled reduced pellets were examined through a Davis Tube magnetic separator in a wet environment under a constant magnetic field of 800 G. Higher iron recovery was observed for the self-hardened reduced (41%) pellets than for the sintered pellets (27%).

Nov 23, 2023

By G. Pan

Although geostatistical techniques have been widely accepted as the standard methods for reserve calculations in the mining industry, the production data of many mines frequently differ from geostatistical estimations based on exploration and development drilling. The discrepancies in recovered metal amounts, commonly in the range between 10% and 30%, are related to different factors. Major causes vary from mine to mine. A common cause, however, is the ignorance of important geological constraints in reserve modeling. Three major factors appear to be related to such an unfortunate fact: 1) modelers are over-confident on geostatistical techniques, 2) it is difficult to establish geological models, and 3) mine schedules are too tight to allow detailed geological modeling work. Defining mineralization envelopes has been a major effort in geological modeling. Past experiences have showed that geological modeling is much mo~ demanding than the choice of sophisticated kriging estimators. Since building envelopes for complex ore bodies can be extremely tedious and time-consuming, computerized approaches are badly needed for mine modelers. A comprehensive procedure reported here is referred to as probability-assigned constrained kriging (PACK), which includes a built-in method for defining 3-d mineralization envelopes. The modeling technique is fast and accurate for complex precious metal deposits. The technique is demonstrated on a gold deposit. The estimation results are compared with blast-hole based production panels, showing that the estimated tonnage is 2.2% larger than the actual production and the average grade is 2.6% lower.

Jan 1, 1994

By R. T. Richins

Coeur d'Alene Mines Corporation (CDE) is a precious metals mining company. The company's three mining operations are located In Nevada and Idaho. Collectively, these mines (Rochester in Nevada, and the Galena and Coeur In Idaho) produced about 61,000 ounces of gold and more than 7.5 million ounces of silver in 1991. The company is currently planning the development of two major properties; the Fachinal gold-silver project in Chile and the Kensington gold project near Juneau, Alaska. Fachinal and Kensington hold encouraging potential to significantly expand CDE's gold production during this decade. The permitting process for these two distinctly contrasting environmental settings, project design requirements and regulatory/political circumstances provide the basis for a comparative analysis of licensing and permitting requirements, timeliness of the permitting process and costs in the U.S. and Chile.

Jan 1, 1993

By H. A. Taylor

Graphite is elemental carbon that crystallizes in the hexagonal system as six-sided platelets. It occurs naturally and is mined. And it can be made artificially from petroleum coke in the form of shapes (electrodes) and powders. The market for most kinds of graphite in most end-uses was good in 2004. The 2005 graphite market looks positive. The major graphite prices, as given in Industrial Minerals, remained unchanged throughout the year. The preliminary 2004 U.S. Geological Survey (USGS) prices for natural graphite showed almost no change for crystalline flake. They were $600/t ($544/st) in 2004 and$622/t ($564/st) in 2003. Mexican amorphous graphite was almost unchanged at $150/t ($136/st) in 2004 from$152/t ($138/st) in 2003.

Jan 1, 2005

By C. S. Compton, T. E. Marshall, D. R. Dolinar, R. Grau, L. J. Prosser, A. T. Iannacchione, D. C. Oyler

Unrecognized roof beam failures resulted in 69% of the falls of ground injuries occurring in underground U.S. stone mines from 1990 to 1996. Field investigations at 45 underground stone mines suggest that excessive beam sag or deflection is the principal unstable roof behavior characteristics associated with miner injuries. Laminated roof structures, common in most underground stone mines, allow the immediate roof to separate into distinct beams. The timely determination of roof beam deflection could provide stone miners with advanced knowledge of potentially hazardous roof. Existing methods to assess roof conditions consist of observational and monitoring techniques. Observational techniques include open drillholes, sounding, wedging, and borescopes. Monitoring techniques include scratch tools, extensometers, telltales, Miners Helpers, and Guardian Angels1. Miners have difficulty utilizing these techniques because roof beams are located an average of 8 m(26.5 ft) above the miner’s head in environments that are dark, dusty and noisy and these deflections are measured in millimeters of movement. To help mitigate the potential for falls of ground injuries to underground stone miners, the National Institute for Occupational Safety and Health (NIOSH) has developed the Roof Monitoring Safety System (RMSS) to aid in monitoring dangerous levels of roof beam deflection. If enough site-specific information is collected and placed on highly visible maps, individual mining operations could establish general guidelines for responding to specific roofbeam deflection occurrences. This would help in implementing a pro-active, comprehensive roof control plan for reducing falls of ground injuries.

Jan 1, 1999

By S. Hamilton

Occurrences of boron-containing ores are relatively rare on a global basis. The first verifiable use of borax was in the 8th century by Arabian gold and silversmiths. Due to the rarity of the borate mineral occurrences, borates were originally traded at relatively high prices and were used for very specialized applications. Today, there are

Jan 1, 2006

By L. Shevenell, L. Stillings

The Acid Drainage Technology Initiative-Metal Mining Sector (ADTI-MMS) has established a Pit Lake Committee to enhance the science and understanding for the long-term management of pit lakes. Participation in this new committee is from members of federal and state agencies, industry, and academia, including numerous individuals representing 10 states. Work has begun on a pit lake literature search and review, database, classification, and sampling and monitoring procedures document. Coordination with the International Network for Acid Prevention (INAP) has been established. Future work will include preparing a prediction and assumption verification document, a report identifying variables upon which water quality is dependent, and an applied remediation technologies document, including an evaluation of the effects of backfilling.

Jan 1, 2002

By G. Le Bel

The paper proposes three methods to determine optimum lifetime of a mining project1. The conclusion is that the three methods arrive at the same optimum production rate (by coincidence). It is also stated that: "The stochastic and option pricing models, in addition to providing a more realistic optimum mine life than the traditional NPV (net present value) calculation, showed that the example project has the potential for substantially higher return. By explicitly considering a project's potential risks, the stochastic or option pricing techniques can more accurately describe its probable investment performance." This discussion is intended to demonstrate that: • It is no coincidence that the three methods arrive at the same optimum production rate. • The stochastic and option pricing models do not provide a more realistic optimum mine life than the traditional NPV calculation. • The potential for a substantially higher return is misrepresented. First, a review of investment decision theory in mining is needed. Net present value is the preferred performance measure because of the flexibility offered when comparing various alternatives. However, it presents the following disadvantages: • The discount rate selection is not straightforward. • The NPV obtained represents a deterministic characterization of the variables included in the cash flow calculations, i.e. a single-point estimate.

Jan 1, 1993

By P. C. Thakur

Frictional ignitions (also called face ignitions) is defined as the rapid oxidation of a mixture of methane and air with a visible flame that could last from a few seconds to several minutes. These ignitions have a potential to turn into a mine explosion and eventually a large-scale mine fire. Over the last 22 years, U.S. coalmines have had 1566 frictional ignitions. There were no fatalities but serious injuries have occurred. Every effort, therefore, should be made to prevent frictional ignitions. The preventative measures fall under four categories: (a) degasification of coal seams prior to mining, (b) adequate ventilation, (c) wet cutting or water-jet assisted cutting and (d) machine design to minimize ignitions. The paper discusses each of these techniques in detail.

Jan 1, 2006

By B. Cavender

Safety departments have traditionally been held responsible for the safety performance of their division or company. This approach leads to a lack of ownership of safety issues by the larger organization. An alternative paradigm is significantly more effective: the members of the work force (managers as well as workers) are fully responsible and accountable for safe production. The safety department is not extinct, however. Its role has changed, to focus on training, litigation, and external relationships such as community relations. This approach was implemented at BHP Copper's Superior mine and mill in Arizona. By obtaining the genuine commitment of the work force to accident-free production, the mill's MSHA incident rate immediately dropped from 7.4 to zero. The mill also ran one year with no MSHA citations. When this philosophy was implemented at the divisional level, the division's incident rate decreased from 9.5 to 1.1,an 88-percent reduction in six months.

Jan 1, 2000

By C. Newman

"Over the past decade, as conventional underground deposits have been depleted, mining operations have been forced to produce at greater depths and in more geologically and geometrically challenging conditions. As such, there has been a global increase in the application of cemented paste backfill (CPB) in tabular deposits utilizing open stope mining method with a delayed backfill placement. Despite the extensive use of CPB, many fundamental factors affecting the design of safe and economical fill structures are still not well understood. A critical issue in the design of backfilled stopes is the determination of stress states within the fill material itself as well as the surrounding rock mass. Analytical equations provide a means of quickly evaluating the effectiveness of a given design. However, in developing these equations large assumptions are implemented to simplify the design problem. It is important that one understands these simplifications as well as their effect on the overall design. This paper investigates common analytical equations utilized in the evaluation of single vertical backfilled stopes and their assumptions through comparisons to numerical modeling results. INTRODUCTION AND BACKGROUND As the mining industry continues to produce at greater depths and in more geometrically and geologically complex conditions, cemented paste backfill (CPB) has gained traction as a means of providing localized ground support in modern stope-and-fill mining operations. The application of CPB in stope-and-fill mining as a ground support material has led to the reduction of mine waste costs, while increasing both mine production and stability. In an attempt to achieve total extraction of the mining reserve, stope-and-fill mining operations often employ a primary-secondary excavation-support sequence (see Figure 1). In this practice, primary stopes are initially excavated and then backfilled in a two-stage pour; plug and final pours. During the first stage (plug), a CPB material with increased cementitious content is placed at the bottom of the stope providing a strong base from which to build a backfill structure as well as protect mine works from material breakthrough. Following placement, the backfill plug is allowed to cure to a given strength as designated by the mine design. Upon achieving the required cure strength, a less cementitious CPB material is used to backfill the remaining stope area. This is referred to as the final pour stage. With all primary stopes excavated and supported using backfill, the extraction of the secondary stopes commences as primary stopes are utilized as artificial pillars. While the application of CPB in a primary-secondary extraction-support mining sequence allows for a substantial increase in reserve recovery, it is imperative the mining personnel and planning engineers have a clear understanding of the material’s behavior and stress interaction with the surrounding rock mass to ensure the most efficient, cost-effective, and safe extraction of underground deposits."

Jan 1, 2018

By R. L. Grayson

For the years 1990 and 1991, West Virginia's underground coal small-mine fatality rate « 20 employees) was approximately ten times higher than the national coal industry rate. Although the total number of fatalities decreased to 17 in 1992 (from 22 in 1991), West Virginia still led ,the nation in coal mining fatals. A team of mining and safety professionals from West Virginia University studied the problem over the past year, interfacing with the Mine Safety and Health Administration and the West Virginia Office of Miners' Health, Safety and Training. A clear path for 'formal intervention was determined and is presented here.

Jan 1, 1994