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By George A. Savanick

Borehole (slurry) mining, in which a tool incorporating a water-jet cutter and a downhole slurry pump mines phosphate through a borehole, was field tested in northeastern Florida as part of a Bureau of Mines program to increase the domestic availability of critical minerals. Approximately 1700 tons (1.54x106 kg) of phosphate ore were mined at 40 tph (10.1 kg/s) from a depth of 250 ft (76 m). The borehole was filled with water during mining for roof support and to assist slurry pumping. Underwater cutting was enhanced with an air-shrouded water jet. Mined cavities were backfilled to prevent subsidence after abandonment. Roof subsidence during mining was avoided only when the cavity was filled with water. Environmental monitoring before, during, and after mining included hydrological studies and measurements of water quality. Significant water quality changes occurred only in the zone being mined and were confined to the immediate area of the borehole.

Jan 1, 1983

By Subhas G. Malghan

The response of feldspar flotation to tallow diamine dioleate collector in the presence of sulfuric acid is studied using batch flotation experiments. Application of this non-hydrofluoric acid (non-HF) reagent system in the flotation of mineralogically and chemically different feldspar ores is compared with that of the conventional hydrofluoric acid system. The dependence of flotation recovery and concentrate grade on feed particle size distribution, conditioning time, pulp density, and pH, combined variation of collector and acid addition rates, sodium hydroxide concentration in the collector solution, and initial pulp pH prior to conditioning is studied. The results have been discussed in relation to applicability of the non-HF system to plant trials, and the nature of the collector adsorption in the selective flotation of feldspar.

Jan 1, 1978

By Laszlo Valentyik

Heavy media separation (HMS) is one of the most widely used gravity methods in the mineral industry. The feed is separated, according to the specific gravities, into two products; float (light) and sink (heavy) particles. The universal acceptance of the process is due to simplicity, efficiency and robustness for ease of control. However, if optimum separation is desired during the operation of heavy media plants, a delicate balance of a number of variables is essential. Among the variables, the two which are generally the most frequently checked and controlled are specific gravity and consistency of the medium. The latter is a function of the settling rate of the media. The medium is generally made up of finely ground ferrosilicon, magnetite, galena, shale, quartz sand, clay contaminants and water. The frequently present clay in the medium acts as a stabilizing agent, since the coarse heavy medium solids (called media) would quickly settle if they were mixed only in water. Clay concentration of the medium varies between 3-7% by height (1,2). Although clay is essential for reasonable media stability, clay concentration greater than 7-8% imparts too high a viscosity to the medium, and the feed cannot accurately stratify and therefore separate into the required products. To be on the safe side, plant operators clean the medium from most of the clays, and would rather work at a lower stability than have a very viscous medium on their hands. The most recent advance in the area of consistency control rlas made by the introduction of atomized (spherical) ferrosilicon (3). This extended the upper limit of the use of ground ferrosilicon from 3.3 to approximately 3.6, broadening the range of the optimum operating conditions. A viscosity control method was also worked out by the use of low cost additives which lower viscosity while retaining a favorable low setting rate (4). Recently (5) polymers have been successfully used in oil well drilling muds then the requirements were mainly to suspend and transport cuttings during the periodic shutdowns and dril1ings respectively. The rheological properties of these polymer suspensions are such that they present an infinite viscosity to

Jan 1, 1971

The occlusion of unliberated gold particles in silicates and sulfides in crushed/milled ore dictates the recovery that can be expected. The grade of this occluded gold in cyanide leach residues shows a consistent, general relationship to the head grade of the ore, irrespective of mineralogy or geographical location. The residue grade almost invariably increases with the head grade, but not in proportion to it. This phenomenon appears to stem from the nature of the geological events originally responsible for creating the ore deposits. A statistically-based technique for determining the true head grade-tail grade relationship from gold plant operating data is described. The effect is illustrated with results from several worldwide gold milling operations analyzed over the last 35 years.

Jan 1, 2008

By H. Haselhuhn

Filtration of hematite ore slurries can be a bottleneck in some hematite processing plants due to inadequate filtration rates caused by the dispersion of fine particles. Flocculation of fine particles in the slurry decreases the specific cake resistance of the filter cake allowing for increased filtration rates. CO2 sparging of hematite slurry was shown to increase the filtration rate by altering the pH and the surface chemistry of the particles. It was shown that an increase in filtration rate of 278% can be accomplished by lowering the pH from 11 to 6.5 using CO2. This was attributed to increased flocculation of hematite and silica particles in the ore.

Jan 1, 2012

By Tony Szwilski

Indonesia has enormous mineral resources. Its population of more than 180 million people inhabit most of the more than 13,000 islands. The country is becoming a significant economic power in Southeast Asia. Indonesia is the largest Muslim country in the world. Java, its largest island, is the most densely populated area. The country's diversity is its strength. However, as only an estimated 16 million inhabitants speak bahasa Indonesia as the first language, communication problems endure. Although burdened with large debts, Indonesia has been able to service the debts better than most developing nations. This has given it high credibility and, with increasing frequency, creditor nations compete to provide Indonesia loans with the most the most favorable financial terms. Recent rising prices of petroleum crude has further improved Indonesia's economic status. It maintains a policy of stable oil prices that it promotes in OPEC, of which it is an influential member. As a result, Indonesia is becoming increasingly attractive to foreign investors. The South East Consortium for International Development (SECID) is made up of 34 universities in the southeastern US and Indonesian partners Lembaga Afiliasi Penelitian dan Industri (LAPI) of the Institute of Technology in Bandung, West Java. SECID bid successfully against international competition to develop new academic programs and campus for the Sriwijaya University UNSRI) in Palembang, South Sumara. Funding for the project was provided by the government of Indonesia through a loan from the Asian Development Bank (ADB). There are 47 public universities

Jan 1, 1991

By AMIT SHARMA, BIBHUTI BHUSAN MANDAL

Operators of mining vehicles are exposed to high levels of whole-body vibration (WBV) and are therefore at risk of developing vibration-related health disorders. For implementing an effective control strategy, it is imperative to locate the source(s) of vibration, and the specific changes that might occur to the vibration signals during its transmission through the seats to the recipient human body. With this objective, Seat Effective Amplitude Transmissibility (SEAT) values of seat modules used in dumpers (n = 10) and other heavy earth-moving machines (n = 11) were evaluated in an iron ore mine. Vibration was measured simultaneously on the seat and on the cabin floor beneath the seat using tri-axial and uni-axial accelerometers. The study aims at determining the quality of seat modules of the transport and non-transport vehicles from the perspective of their natural resonance frequencies and capability of any such seat in reducing harmful vibration. The highest acceleration values were observed in the z-axis for all the dumpers. SEATrms values ranged from 78 to 133% and SEATvdv values ranged from 72 to 130% for the dumpers. For other HEMMs, SEATrms values ranged from 55 to 125% and SEATvdv values ranged from 56 to 123%. Mechanical vibration contains multiple frequency components. To understand the changes taking place to the different signals at these frequencies, 1/3 octave band analysis was carried out for the signals recorded both on the seat and the floor. There was significant attenuation (38 to 57%) at 4 Hz for three Dumper seats, whereas they resonated in the range of 1.6–2.5 Hz. The transmissibility(%) in the resonating frequencies ranged from 108 to 156%. Resonance frequencies for the remaining seven dumpers ranged from 3 to 8 Hz. The spine has been reported to resonate at 4 Hz, whereas resonance at 1.6 Hz has little significance to human beings in regard to WBV of a seated person. Hence, the characteristic resonant frequency of 4 Hz of seats as observed in the present study has the potential of causing adverse impacts on spinal health. Evaluation of SEAT factors and resonance characteristics of seats are therefore recommended to be examined while selecting a mining vehicle for regular deployment in mines.

Mar 12, 2021

By Lynn B. Hales

There is a large economic opportunity associated with improving metallurgical performance in mineral processing plants that use process control. Thus, future control systems will be developed towards more sophisticated user friendly, computer-based systems that use powerful software analysis and control techniques. Auto-tuning, adaptive control and process models will gain expanded use because of their transparent availability to the system designer. Control of individual unit operations will be optimized and coordinated through expert systems that monitor economic conditions and management directives and direct operations accordingly. Plant areas, once considered cost centers, will be integrated into plant-wide control systems for economic control and optimization. This article looks at new control hardware, process sensors, control strategies and software development tools. It also looks at the economics driving the continued development of advanced process control systems. Process control systems routinely used in the mining industry were born when the microprocessor was invented. They have continued along an evolutionary path from vendor specific processing hardware and proprietary operating systems to computer industry standard "open architecture" systems. The many economic forces that drive the development and functionality of these process control systems will cause this evolutionary process to continue. Two of the broadest categories are the needs of the end users and the desire of the system manufacturers to distinguish their products from one another. More

Jan 1, 1994

By M. Li, W. R. Reed, J. P. Rider, J. D. Potts

"The National Institute for Occupational Safety and Health (NIOSH) recently developed a series of validated models utilizing computational fluid dynamics (CFD) to study the effects of air-blocking shelves on airflows and respirable dust distribution associated with mediumsized surface blasthole drill shrouds as part of a dry dust collector system. Using validated CFD models, three different air-blocking shelves were included in the present study: a 15.2-cm (6-in.)-wide shelf; a 7.6-cm (3-in.)-wide shelf; and a 7.6-cm (3-in.)-wide shelf at four different shelf heights. In addition, the dust-collector-to-bailing airflow ratios of 1.75:1, 1.5:1, 1.25:1 and 1:1 were evaluated for the 15.2-cm (6-in.)-wide air-blocking shelf. This paper describes the methodology used to develop the CFD models. The effects of air-blocking shelves and dust collector-to-bailing airflow ratios were identified by the study, and problem regions were revealed under certain conditions. IntroductionSurface blasthole drilling can generate considerable amounts of respirable silica dust. These high dust concentrations can be exacerbated by the high silica content as drilling cuts through silica-bearing materials such as sandstone and shale, causing overexposures for miners to respirable silica dust. These overexposures can lead to silicosis, an occupational lung disease that has no cure and is often fatal. A review of the Mine Safety and Health Administration (MSHA) respirable silica dust sample database from 2010 to 2016 for metal/nonmetal mining shows the following overexposure rates for occupations related to blasthole drilling: • 14.1 percent of rotary air drillers were overexposed to respirable silica dust (22 out of 156 samples).• 5.8 percent of rotary drillers were overexposed to respirable silica dust (nine out of 155 samples).• 7.3 percent of drill helpers were overexposed to respirable silica dust (three out of 41 samples).• 7.5 percent of blasters/shotfirers were overexposed to respirable silica dust (three out of 40 samples)."

Jan 5, 2018

By R. Owen

An overwhelming amount of data can be collected around the blasting process. This information can include blasting product, pattern design, blast results, and routing. It is only when these data sources are combined in a concise and accurate form that they are of real use in determining the safety and economic implications of each parameter. Two key technological aspects of blasting are drill fleet management (DFM) and size fraction analysis (SFA). As these technologies are integrated as near-real-time measurement and QA/QC tools, the resolution and realization of blasting parameters is significantly increased. The Freeport-McMoRan Morenci Mine has integrated these technologies along with other existing database structures to create a responsive and sustainable tool for reconciliation, forecasting and parameter matching. This ability allows Morenci to customize blast patterns to meet the criteria most critical to each shot, whether the impact is influenced by routing and recovery, equipment maintenance or safety concerns. DRILL FLEET MANAGEMENT The current DFM was stabilized in its current form in mid 2009 after database and hardware maintenance met stability requirements. Currently the system is running on 12 production drills. The system receives pattern layout and is capable of semi-autonomous drilling over the entire district. The fleet is capable of drilling in highly altered intrusive units and hard granites through the range of sedimentary and volcanic units that comprise the Morenci District. The system brings a level of accuracy not achievable with earlier paint-marked patterns. Depth control is also increased along with more consistent wear and maintenance patterns due to semi-autonomous drilling.

Jan 1, 2011

By JIAQI JIN, Joe Milbourne, Maoming Fan

Gold is very important to support the financial system, and to be used in industries of the jewelry, high-tech fields such as electronics and aerospace, etc. Gold is mainly extracted from three types of ores: primary ore (vein gold), placer (alluvial gold) and associated ore. Cyanide was widely used in gold ore flotation to depress gangue minerals and leaching/cyanidation. The process of extracting gold from gold ore, its separation and flotation concentrate, specifically through a technique called cyanidation or cyanide leaching. This method, which has been dominant since the 1970s, utilizes a dilute solution of cyanide to dissolve gold from the ore. While effective, the use of cyanide raises environmental and safety concerns due to its high toxicity. Cyanide spills can have severe environmental consequences. This has led to the exploration of alternative, environmentally friendly reagents. This paper discusses processing results using the alternative flotation depressants such as sodium sulfite (Na2SO3), etc. to produce a goldrich flotation concentrate for sale to a smelter or as feed to an alternative leaching agent. and methods to extract gold from ore without relying on cyanide.

Feb 22, 2026

By E. H. Cho, B. Conner

Three sulfide minerals, chalcopyrite, sphalerite, and pyrite, were leached using a bioleaching mode and an electrobioleaching mode. The former mode was used to leach the minerals with the bacterium A. ferrooxidans in a bioreactor. In the latter mode, the leaching of the minerals was performed in a combination of a bioreactor and an electrochemical cell. In this set-up, the solution was circulated between the bioreactor and the cathode compartment, the two reactors were in series, and the cell was operated intermittently. The mechanism is such that an increase in Fe(II) concentration, which is a nutrient of the bacteria, by electrochemical reduction of Fe(III) would increase the bacterial population and in turn would accelerate the leaching of the mineral. It has been found that the electrobioleaching of chalcopyrite is an improvement over the bioleaching with respect to the fact that leaching conversion is higher and a high level of Fe(II) concentration can be maintained. However, the electrobioleaching of sphalerite does not show any improvement over bioleaching. The electrobioleaching of pyrite is similar to that of chalcopyrite, and this has potential to be used in applications such as coal desulfurization and pretreatment of refractory gold ore in heap leaching where fine gold particles are entrapped inside pyrite particles.

Jan 1, 2006

By F. J. Brenner

The Slippery Rock Watershed Coalition was organized to restore a 70 km2 portion of the headwaters of the Slippery Rock Watershed in northwest Pennsylvania. Thirteen passive treatment systems have been installed with engineering and funding provided by private industries, county government and the Commonwealth of Pennsylvania. In addition, experimental systems have been installed at the Jennings Environmental Education Center which, in addition to monitoring the systems installed within the watershed, provide an array of educational and research opportunities for secondary, college and university students. The coalition sponsors an annual seminar for students to present the results of their research and field trips for public officials and private citizens to learn how public and private partnerships work together to restore the Slippery Rock Creek watershed.

Jan 1, 2002

By J. A. Botín

Identifying, quantifying and minimizing technical risks associated to investment decisions is a key challenge for the minerals industry decision takers and investors. However, risk analysis in most bankable mine feasibility studies are based on stochastic modelling of project NPV which, in most cases, fail to provide decision makers with a truly comprehensive analysis of risks associated to technical and management uncertainty and, as the result, are of little use for risk management and project optimization. This paper presents a value-chain risk management approach where project risk is evaluated for each step of the project lifecycle, from exploration to mine closure, and risk management is performed as part of a stepwise value added optimization process.

Jan 1, 2011

By D. Bogh

Wound rotor motors are used in difficult mining applications where there is a need to start high inertia, hard starting loads while limiting inrush current They are recognized as robust and simple to control. This paper will cover the performance, specification, and important issues to be considered when applying medium voltage wound rotor motors in mining applications. Medium voltage grinding, crusher, and conveyor applications will be discussed. Specifically covered are motor efficiency, speed range, and rotor control. Crane motors often have wound rotor construction, but their load cycle and ratings are outside the scope of this paper.

Jan 1, 2011

By William Harrison, Robert H. Trent

GENERAL DESCRIPTION History The most striking feature of mining in the United States has been the infrequent use of longwall systems. This system, which accounts for the majority of coal production in Europe, Japan, and other countries, is only recently growing out of its infancy in the mining of normal coal seams and is still untried in the mining of thick coal seams in the US. Its use in the mining of metal and nonmetal ore bodies has been virtually ig¬nored, except for isolated instances in trona, copper, and uranium. Longwall mining is believed to have originated in Shropshire, England, towards the end of the 17th cen¬tury (Laird, 1973). Although the method used would be considered primitive by today's standards, many of the basic concepts have remained unchanged. Longwall mining of coal in the US was first introduced before the turn of the century, but it never gained acceptance as it did in Europe. Historically, longwalling was a cyclic method where a single cut of coal was removed from the face on the producing shift each day, and the work of building stone packs in the gob and manually moving roof support was completed on the off shifts. Due to the amount of dead work, productivity was extremely low. In Europe, however, longwall methods were required despite the high costs involved, because only by this method could coal under heavy depth be mined with any reasonable degree of recovery. Reserves of coal lying under shallow cover, and therefore minable by room¬and-pillar methods, were long ago inadequate to supply most of Europe's coal requirements. In the US coal min¬ing has historically proceeded laterally with the new mines in virgin areas to replace old mines; in Great Britain, Germany, Japan, and many other countries, mining must proceed downward to greater depths. The depth of cover for most coal operations in the US is shallow, i.e., 61 to 305 m (200 to 1000 ft). This, combined with large reserves, has made room-and-pillar methods almost universally applicable. However, longwall systems were tried around the turn of the century. Whenever used, it was frequently noted that the opera¬tion was under the direction of men with foreign ex¬perience and was tried under ideal conditions. Some of the mines that were using longwall or had tried longwall prior to 1910 were the Radiant mine, CO; Vinton Coal Co., PA; Cambria Steel Co., Johnstown, PA; Grundy County and Spring Valley, IL; and unnamed mines in Washington, West Virginia, Kentucky, Iowa, and Kansas. As late as 1961, there was one circular longwall in operation at Centerville, IA. The first modern-day op¬eration to take advantage of European technology and longwall methods was Kaiser Steel Corp. at its Sunnyside mine near Price, UT. Due to deep cover and extremely poor roof conditions, combined with a need for in¬creased production, Kaiser management decided a new method was required and turned to longwall in 1961. The first longwall consisted of an Anderson Mavor shearer loader, British Jeffrey-Diamond conveying equip¬ment, and Dowty roof supports with a capacity made up of two and three 27-t (30-st) capacity props. After nor¬mal start-up problems, this unit averaged over 454 t (500 st) per shift (White and Palacios, 1976). During and after World War II, technology in hy¬draulics and controls had advanced to the point that self-advancing supports and hydraulic props were being developed. In 1960 only I % of West German produc¬tion was from mechanized longwall faces. This in¬creased to 37% in 1970 and 63% in 1973 (Kohlgruber, 1974). In 1976 there were 246 coal mines operating in the United Kingdom. Although this is only 50% of those operating ten years ago, the production has increased 42%, mainly through improvements in longwall equipment and methods (Hunter, 1976). In France and other European countries, the devel¬opment of longwall mechanization has been similar in seams up to 2.44 m (8 ft) thick. In seams that exceed 9.14 m (30 ft), a variety of longwall caving has been developed for coal seams with dips of 0 to 1.6 rad (0 to 90°). Those with the greatest success will be discussed later. As noted, the development of longwall mining to its present state of the art has mainly taken place since World War II with substantial gains in the last ten years. Mechanized longwall has been the result of several re¬lated major innovations (Jackson, 1975) 1) Development of the flexible armored face con¬veyor which can be installed along the face and moved forward without disassembly. 2) Development of face machines such as single and double drum shearer and coal plows which operate in conjunction with the armored conveyors. 3) Development of self-advancing hydraulic roof supports which now include chocks, chock shields, and shields. 4) Reliance of caving of the immediate roof based on proper planning and development. 5) Use of pneumatic slowing to enable extraction below overbuilt areas. The most recent developments in the mining of coal by longwall in the US include the introduction of shield supports at Kaiser's York Canyon mine in New Mexico, single-entry longwall development at Kaiser's Sunnyside mine, and Mid-Continent's advancing longwall system in Colorado. Metal and nonmetal longwall systems in the US have included the mining of copper at White Pine, MI; uranium in Utah and New Mexico, and trona in Wyoming.

Jan 1, 1982

In the present study, we have investigated the conditions for the formation of bubble clusters and the effect of well-defined agitation on the stability of clusters. A specially designed cell was used in which bubble clusters could be formed at the surface of a porous block in a fluidized bed of relatively coarse hydrophobic silica particles. The clusters then rose through a flow field of known turbulent characteristics. The size of the clusters before and after passing through the turbulent zone were measured using a high speed camera. The influence of shear rate on the deformation of the bubble clusters was investigated. The results showed that the Kolmogarov microscale was much smaller than the maximum cluster size, suggesting that the breakage of the clusters was mainly due to interaction with clusters in the inertial convection sub-range.

Jan 1, 2009

By A. ALLANORE, OLIVEIRA M. DE, D. CICERI, D. P. CHEN

The alkaline hydrothermal processing of K-feldspar rocks in an autoclave can be a pathway to synthesize a potassium fertilizer for tropical soils that is potentially cheaper and more efficient than traditional potash (KCl). When K-feldspar undergoes hydrothermal alteration in the presence of calcium oxide (CaO), it generates a complex mixture of calcium-aluminum-silicate-hydrate (CASH) minerals that incorporate K atoms stochastically in their structure. These atoms are subsequently released, as shown in a test-tube leaching test, indicating a possible uptake by crops. The relationship between the processing temperature and time in the autoclave for the hydrothermal reaction and the resulting mineralogy and elemental release are only partially understood and are investigated in this study. Elucidating that relationship is the key requisite for subsequent techno-economic analysis, and ultimately for the development of a fertilizer that can be considered as a feasible alternative to KCl.

By Patrick Shea

Old mine workings are found throughout the Western United Sates on lands administered by the U.S. Bureau of Land Management, U.S. Forest Service and private lands. Some of these mine workings date back to the late 1800s. There may be as many as 100,000 sites on lands administered by the National Park Service, U.S. Forest Service and Bureau of Land Management. The U.S. Department of the Interior has worked with the U.S. Geological Survey, the U.S. Forest Service, the U.S. Environmental Protection Agency, and western state governments to identify and prioritize these sites on Bureau of Land Management, National Park Service and U.S. Forest Service administered lands. This presentation will discuss the accomplishments we have made to date to clean up inactive and abandoned mine sites, focusing primarily on lands administered by the Bureau of Land Management.

Jan 1, 2000

By Jack A. McQuiston, Thomas A. Cross

Corrosion of equipment and machinery in the coal industry is usually the result of three main agents: acids, chlorides, and abrasion. Acids and chlorides are especially troublesome in coal preparation plants where soluble salts and sulfur in the coal produce a highly corrosive wash solution. Abrasion is common in all operations where coal is handled or conveyed. Together, the acid-chloride-abrasion combination results in some of the worst corrosive conditions found in any industry. The variety of equipment and structures in the coal industry calls for different corrosion control techniques. Table 1 lists the areas of concern for a number of items. Just as there is a wide variety of corrosion problems, there is a wide array of coating materials available. Tables 2 and 3 are selection charts to provide guidance in narrowing down the choices. Experience has shown that a limited number of coating systems work best on coal equipment and structures. These systems are described in Table 4. The good-better-best designation in the table refers to coating system longevity. Good indicates the least costly and shortest service life. In nearly all cases the lowest annualized cost can be achieved by using the coating system rated best, due to the avoidance of costly repaints and unnecessary downtime. The most expensive coating system, though, is worthless unless the coating system is properly applied. Field inspection to insure compliance with specifications is an important aspect, and is a service available from many coating suppliers. Even the best coating systems require periodic maintenance to achieve satisfactory results. Spot rusting from mechanical damage should be repaired annually to maximize the coatingsystem's results.

Jan 2, 1980