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By R. C. Ford

The advent of solvent extraction-electrowinning (SX-EW) technology for recovery of copper from low grade oxide ores has extended the operational lives of many historic mines in the western United States, and made many other orebodies economically viable worldwide. Many of these operations are mature and face closure within the next decade, depending on market conditions. Closure of a large copper heap leach operation has not been undertaken, and differs in some important chemical respects from closure of gold leach pads. Challenges for closure include prediction of solution chemistry and draindown characteristics, determining the benefit of cover placement in semi-arid climates and evaluation of solution management strategies once the economics of copper recovery are no longer favorable. This paper discusses issues pertinent to copper heap closure in semi-arid and arid climates, and strategies for their management.

Jan 1, 2000

By Olav Moklebust

The R-N Process is an outgrowth of the development by the National Lead Company's Norwegian subsidiary Titania A/S, of a process for producing metallic iron and a high titanium content co-product from ilmenite. Development of the process for the treatment of iron ores was continued as a joint project of the Republic Steel Corporation and the National Lead Company in 1953. More recently in July, 1957, the R-N Corporation was created by these two companies to undertake the commercial promotion of the results of this joint project. This paper has been prepared with the permission and encouragement of these three companies. The R-N process has as its objective the making of metallic iron from iron ores or iron ore concentrates. The general principles of the process have already been disclosed in technical papers and patents. In general the process comprises the following steps: 1. Iron oxide in crushed natural iron ores or iron ore concentrates is reduced to about 95% metallic iron, without fusion in a rotary kiln in the presence of solid carbonaceous fuel,*such as, coke or char, limestone and combustible gases. 2. The kiln discharge, consisting of metallized ore, coke, lime and coke ashes, is cooled. The excess coke is regenerated and recycled to the kiln feed.

Jan 1, 1959

By Cody Giroux, Homer Scurlock, Michel Wasag

Silica and Crystalline Quartz exposure continues to be a serious health threat to nearly 2 million workers in the United States, including more than 100,000 working in high risk jobs such as abrasive blasting, foundry work, stonecutting, rock drilling, quarry work, mining and tunneling. The primary focus of this study is to identify the best methodology to reduce particulate-laden air and limit/eliminate exposure to respirable dust with silica/crystalline quartz during tunneling operations. This study focuses on two de-dusting systems employed on similar tunnel construction projects. The first project is the Coxwell Bypass Tunnel located in Toronto, Ontario Canada. The second project is the Westerly Storage Tunnel located in Cleveland, Ohio. The Toronto project is utilizing a wet de-dusting system. The Cleveland project is using a dry de-dusting system. The objective is to determine which system provides the best protection and suitability to capture, remove and ultimately reduce respirable concentrations of silica/ crystalline quartz to safety and healthy levels in underground tunneling activities.

Jun 13, 2021

By Kumar Vikram

Rich reserve of prime quality limestone in east khasi hills of India and abundant quantity of low-cost fuel (Natural Gas) in Bangladesh made Lafarge Surma cement limited a joint venture company of Lafarge France and Cementos Molins Spain to envisage an integrated cement plant at Chatak District-Sylhet) a bordering town of Bangladesh. Since April 2006 the single flight 17 km Long Belt Conveyor (LBC) built by M/S Larsen & Toubro Ltd. (L&T), ECC Division an engineering and construction company of India, is feeding limestone/shale to the Lafarge Surma cement plant. This engineering marvel was created on a turnkey basis with technology support of M/S Aumund France

Jan 1, 2008

By Alberto Sarmentero

Venezuela, once a world's top gold producer until 1886 Witwatersrand discovery, did let fall its role then because of a serious lack of infrastructure and population, and lately (since World war II times), because of discouraging mining and taxation laws, laying upon an oil prizes bonanza. Recent research leading to estimates of about 5.000 mt. of gold, mainly related to the greenstone belts of the Guiana Precambrian shield outcropping in Venezuela, are opening the scope for both Government and international investing and mining companies, for gold exploration and development projects in the country. This paper overviews Venezuelan Gold mining industry, as seen from the point of view of a participating mining company.

Jan 1, 1989

By Ricky Chipka, Roshan Thapa, Richard Yovichin, Greg Rogoff, Patrick Niemuth

A 4.5-mile-long, 96-inch-diameter outfall pipeline was constructed between North Texas Municipal Water District’s proposed Sister Grove Regional Water Resource Recovery Facility and the Stiff Creek Discharge Structure. Two TBM-mined tunnel segments were excavated for the outfall pipeline through rock and mixed-face conditions within the Austin Chalk Formation. The TBM mining performance was tracked in detail and evaluated during mining. This paper discusses the TBM configuration, TBM utilization, advance rates, and challenges of both tunnel segments.

Jun 13, 2023

By Johan K. Rodenburg

A major bauxite belt was discovered and evaluated from 1969 to 1974 by P. T. Alcoa Minerals of Indonesia in West Kalimantan, Indonesia. The proven reserves of beneficiated bauxite are 800 million tons averaging 38.6% AA1203 and 3.0% RSiO2. Inferred reserves of washed bauxite are in excess of 2 billion tons. The bauxite occurs as capping of low lying hills which were formed during the post Paleogene peneplaination stage. The overburden varies from 0.6 to 3.8 meters and the nodular bauxite horizon from 2.2 to 5.2 meters. The deposits were formed by the in situ weathering of predominantly acidic and basic intrusive rocks.

Jan 1, 1984

By Takashi Sakaguchi, Akira Nakajima

Some attempts were made to recover and remove heavy metal elements, such as uranium, copper and chromium, from aqueous systems by using several phosphate compounds. The phosphorylated derivatives of polysaccharides, chitin phosphate, chitosan phosphate and cellulose phosphate, have high abilities to accumulate heavy metals, such as uranium, copper, manganese, cobalt, cadmium, zinc, nickel and chromium, compared with non-phosphorylated polysaccharides. In order to obtain basic information on the recovery and removal of uranium that may be present in industrial effluents, mine waste water and seawater, the adsorption of uranium by chitin phosphate and chitosan phosphate was investigated in details. The adsorption of uranium by chitin phosphate and chitosan phosphate was much greater than copper, cadmium, manganese, zinc, cobalt, nickel, magnesium and calcium. The adsorption of uranium was very rapid and was affected by pH of the solution, temperature. granule radius and co-existence of carbonate ion. The amounts of uranium adsorbed on the adsorbents increased linearly as the external uranium concentration increased. Uranium adsorbed on chitin phosphate easily desorbed with diluted sodium carbonate solution. On the other hand, uranyl and cobalt ions were separated from each other by using chitin phosphate. Along with these fundamental research, some attempts were made to recover uranium from seawater.

Jan 1, 1993

By J. Alatalo

Autogenous grinding is a process of reducing the particle size distribution of an extracted ore by using the ore itself as the grinding media. It is a process that is difficult to control and there is a lack of knowledge of the events occurring inside the mill. To find out more about how the mill behaves under different processing conditions, a full factorial test was performed with iron ore in a pilot-scale pebble mill at the LKAB R&D facility in Malmberget. To complement this work, a strain gauge detector was embedded in one of the mill?s rubber lifters, the Metso Minerals continuous charge measurement (CCM) system, and was used to get more information about the charge dynamics. The data from the experiments has been analyzed. For production purposes, an increase in the number of particles smaller than 45 µm can be regarded as a probable increase in the production rate. The analysis shows that there will be an increase in fines at 65% of critical speed, especially when the mill is 45% full. This setting will also increase the power consumption, but improves the grindability of the ore even more. The deflection of the lifters is smaller for lower critical speeds. A higher degree of filling also gives a smaller toe angle and a higher shoulder angle as expected.

Jan 1, 2011

By C. C. Clark

The National Institute for Occupational Safety and Health (NIOSH), Ground Control Engineering Branch is investigating the use of shotcrete in weak rock mass mines with the objective of reducing fatalities and injuries resulting from rock fall accidents. When shotcrete is used as part of a multi-element ground support system there is a need to know when the material has developed a threshold early compressive strength of approximately 1 MPa (145 psi) for safe re-entry of miner and machine into shotcreted mine workings. This equates to the material having developed enough strength to be self-supporting and allow for emplacement of the remaining support elements that require drilling of the shotcrete layer without degradation. NIOSH researchers have developed methods and portable test equipment to measure shotcrete strength on-site in the first six hours after application using the ASTM C 116-90 (1990) standard. These advances were demonstrated in tests on five commercially available shotcrete mixes, sprayed as dry shotcrete using the field expedient methods and equipment. The strength values from these tests allowed for real-time identification of the early strength threshold and were consistent with strengths reported using laboratory-type equipment. The findings of this NIOSH research for determining shotcrete early strength can improve mine safety by providing a method for determining initial site specific material property values to be used for design and as a means to conduct on-site quality control and monitoring during production.

Jan 1, 2010

By Charles L. Kimbell

The year 1988 for the minerals indus¬try was one of favorable worldwide economic conditions for continued, rationally constrained growth. There was continued improvement in relations between market economy nations and the Soviet Union and China. The "shooting war" between Iran and Iraq ended. Soviet troops withdrew from Afghanistan. And conditions were generally favorable for economic growth in developed market economy countries. These favorable conditions were darkened only somewhat by the continuing foreign debt crises discernible in some major mineral producing developing market economy countries. However, there were situations developing that became major headlines in the late spring - situations that may have pronounced effects in 1989. The most significant event is the muddled situation in China. There is a good chance of worsening international relations and consequent restraint of development projects that could prove beneficial to China and her international partners. Of only slightly lesser evident significance was the death of Ruhollah Khomeini in Iran. This could lead to a variety of paths for the new Iranian leaders. Continued outbreaks of ethnic unrest in the Soviet Union clearly presented problems to the Gorbachev regime. This unrest has raised questions of how far the doctrines of "glasnost" and "peristroika" would be extended, including extensions into the minerals field. Another area of unrest is Panama with its tainted election and the Western Hemisphere's obvious dissatisfaction with the Noreiga regime. While not a direct threat to any major mineral industry enterprise, the political situation certainly presents a potential threat to the Panama Canal. That threat would have considerable impact on world

Jan 1, 1989

By R. Fedel-Moen, R. W. L. Kimber, B. D. Williams, S. R. Ragusa

The use o f cyanide to extract gold from ores is widespread. In the process of extracting gold, cyanide may form metal cyanide complexes with a variety of other metals present in the ore. This study was carried out to investigate the biodegradation of the Cu(I)-cyanide complex and tetracyanonickelate under varying pH and nutrient additions. Detailed studies using shake flask cultures and bioreactors showed that naturally occurring bacteria residing on gold-leach-pad ore uti¬lized the Cu(I)-cyanide complex (CuCN) and tetracyano-nickelate, Na2(NiCN4), as carbon and/or nitrogen sources. Ammonium-nitrogen (NH4+-N) and/or cyanate (CNO-) accumulated in solution as the metal cyanide complexes were degraded. The accumulation of cyanate as a product is a concern due to its toxicity. Degradation rates were increased if a growth substrate (peptone, 0.1%) was added to the medium or if bioreactors were primed with peptone before addition of the metal-cyanide complex. Tetracyanonickelate was degraded at pH 8 without added peptone, but it was not degraded at pH 10. The addition of peptone was required for degradation of the Cu(I)-cyanide complex at pH 8 and pH 10. At pH 8, the addition of peptone resulted in the accumulation of cyanate, whereas, at pH 10, cyanate was not detected in the cultures. Biodegradation of metal-cyanide complexes was faster (approximately 1.5 to ten times faster) in bioreactors than in shake flask cultures. The addition of peptone was not required for degradation of metal-cyanide complexes in bioreactors. However, priming the bioreaetor with peptone resulted in higher metal-cyanide degradation rates over multiple cycles.

Jan 1, 2000

By S. Mohanan, C. R. Kumar, S. K. Bhoja, T. Venugopalan

"A pressing issue that has often been the topic of discussion in iron-making operations in India is the high content of alumina in the country’s iron ore deposits. The presence of alumina has hampered production by affecting slag fluidity, and thereby the hot metal quality. Iron ores from Indian mines are generally rich in hematite, with traces or small amounts of goethite/limonite, kaolinite, gibbsite and quartz reported from time to time. In day-to-day production, emphasis is placed on checking the chemical analysis of product samples, but the true solution to the alumina problem lies in estimating the mineralogy of the ore samples. We developed a mathematical model, based on singular value decomposition, to predict mineralogy from classical chemical analysis. We then used X-ray diffraction patterns, scanning electron microscope analysis, and grain counting with an optical microscope to determine actual mineral compositions and to test the values predicted by the model. The results indicate that with regular calibration, the model can be used as a simple, fast and effective tool to predict on a regular basis the mineralogy of multiple samples.IntroductionIndian blast furnaces use high-grade iron ores (as lumps or as sinter) and coke (obtained from the destructive distillation of coal) as raw materials for the production of high-quality hot metal to be converted into different steel products through the Linz- Donawitz process. The iron ores are mainly sourced from the Singhbhum region of Odisha and Jharkhand states, the Bailadialla region of Chattisgarh state and the Bellary region of Karnataka and Goa states, and are mainly classified based on size as (1) lump ore (fed directly into blast furnaces), (2) fines (converted into sinter/pellets and fed to blast furnaces) and (3) slimes (< 0.15 mm; currently dumped in huge slime ponds). Any variation in the quality of the ores supplied results in variations in the production trends of hot metal."

Jan 1, 2015

By Ihsan Berk Tulu, Ted Klemetti, Deniz Tuncay, Cicek Sena, Zhao Haochen

"Analysis of Longwall Pillar Stability (ALPS) and Analysis of Retreat Mine Pillar Stability (ARMPS) treat the pillar as a passive structure that is designed to carry overburden dead-weight. This dead-weight is calculated by simple rules based on the geometry of the mining, such as “tributary area theory,” “pressure arch theory,” and “abutment angle theory.” Although the pressure arch loading approach indirectly accounts for the generally stiffer overburden response of narrow and deep panels, it does not include the effect of specific geology of the overburden in load calculations. The relationship between successful pillar layouts and overburden geology can be incorporated into the load calculation by using the Ground Response Curve (GRC) approach.This paper introduces the GRC modeling methodology to investigate the effect of overburden geology and excavation geometry on load transfer mechanisms using seven field measurement case studies from four U.S. mines. It was also shown that the modeling methodology used to derive GRC in this study approximates mining-induced stresses and deformations within 5% of the values measured in the field.INTRODUCTIONFrith and Reed (2017) stated that current state-of-the-art pillar design methods ignore the overburden mechanics and use estimated dead-weight of overburden to compute pillar sizes. In the United States and around the world, overburden loading is typically estimated by simple geometric rules, generally with the tributary area theory (TAT). The specific overburden mechanics, structural competence of the overburden strata, geology, in situ stresses, and overburden/pillar interactions are typically ignored. However, these important mechanical responses affect the stability of the mine pillars and openings; therefore, they also affect the safety of the mine workers.Research conducted by the National Institute for Occupational Safety and Health (NIOSH) after the Crandall Canyon mine disaster (Esterhuizen, Mark, and Murphy, 2010) showed that small panel width-to-depth ratios and stiff-strong overburden result in a reduction of the observed pillar loads, much smaller than the TAT estimate. In fact, as a response to the Crandall Canyon disaster, Mark (2010) implemented a pressure arch loading approach into the latest ARMPS program to recognize the inherently greater stability of narrow panels at depth. The pressure arch approach is a first logical step to introducing non-tributary area loading into the practical ARMPS program. Although the pressure arch loading indirectly accounts for the generally stiffer overburden response of narrow and deep panels, it does not include the effect of specific geology and mechanical response of overburden in the load calculations."

Jan 1, 2019

By Geoff W. Seward, Charles J. Maes

INTRODUCTION The work of the metallurgical engineer engaged in developing a leach, solvent extraction electro- winning process usually begins in the laboratory and generally proceeds via pilot plant testing before finally resulting in a commercial operation. The path leading to the development of the eventual process will involve a test program on leaching in order to derive information on the amenability of the copper-bearing material to acid dissolution, under various conditions. Commonly in North America the leach process of choice is either dump or heap leaching but it may also be in-situ leaching or the treatment of mine waste- waters and bleed streams. In the past, agitation and vat leaching have also been included in the list of options. Currently the economics of copper production dictate that only material of mineralogy and grade, capable of being leached without prior milling, will lead to a viable process. This is not necessarily true in other parts of the world where grades are higher and milling costs lower and therefore this paper con- fronts all the techniques available to the metallurgical engineer in terms of the evaluation of the solvent extraction process. Understanding the objectives of a laboratory and pilot plant evaluation of a solvent extraction route is important and these are described in some detail in this paper. Of at least equal importance is understanding limitations of such a test program and this aspect of process development is also discussed with reference to the kind of equipment and experimental practices that have been shown to produce results consistent with the objectives. WHERE TO BEGIN? At the inception of a project much information is developed on the variables of the leach process and indeed in some instances the type of leach that best suits the ore to be treated is the subject of intense investigation (Wadsworth 1983). The decision to treat the leach solution by solvent extraction focuses attention on the selection of the extractant most suited to the nature of the chemical composition of the solution. A laboratory screening program will probably need to be arranged in order to assist in narrowing the options and the following is suggested for this initial screening. Selection of a Representative Leach Solution This is preferably obtained from leaching a representative sample of the ore under conditions likely to pertain in the commercial leach circuit. As the conceptualized circuit flow sheet will undoubtedly involve the recycle of aqueous solutions via the leach, then it is desirable to know the nature of and the likely level of the impurity ions in the solution as well as the concentration of copper. The other most important parameter that is required is the free acid (Anon, Acorga Analytical Method) content of the solution. As a rule of thumb, it is always true that recovery across SX is maximized as the pH of the leach solution rises. Whilst a high pH may be desirable for SX recovery, it is not always desirable for the pH (or more correctly, the free acid) of the leach to rise too high. The working range, therefore, tends to be between 1.5-2.5 pH. At an early stage in process development it is likely that a number of ill-defined conditions will exist, making it difficult to decide on typical leach conditions in which case the screening tests should be carried out using a synthetic leach solution prepared from laboratory chemicals. In doing this the copper and free content should be carefully controlled along with the appropriate addition of major impurity ions as their sulphate salts. Preparation of Suitable Organic Solutions Manufacturers information sheets on the reagents to be tested are required at this stage The information necessary to make an informed judgment on reagent performance is: Copper Uptake Value. This will indicate the amount of copper that can be extracted by a reagent as a function of its operating concentration in a

Jan 1, 1986

By Dale R. Ralston, Roy E. Williams, Gerry V. Winter, George L. Bloomsburg

Jan 1, 1986

By Dale W. Norris, John A. L. Campbell

INTRODUCTION Optimization, as measured by productivity gains, is being achieved in our nation&apos;s preparation plants principally by automation, economy of scale, and reducing maintenance. Increased tonnage per unit of investment, a1 so a measure of optimization, is being achieved by breaking with tradition and increasing plant utilization, while simultaneously improving on equipment re1iabi1ity. Improved qua1ity, another measure of optimization, is being attained through technical innovation. This review will concentrate on state-of-the- art unit operations and processes, and will not discuss emerging new technologies which are covered in detail in other presentations of this symposium. It is recognized that much of what will be discussed in this paper is not unique to the fine coal circuit, but is equally applicable to the entire preparation plant. However, the areas reviewed are the principal means being used today to optimize an existing preparation plant&apos;s fine coal circuit. Prior to designing and optimizing a fine coal cleaning circuit, the question that must first be answered is, "Do we even want a fine coal circuit? This is a much more complex question than is readily apparent, as most of you recognize. It can be argued either way. In the final analysis the "bottom line" will hold (Blackmore, 1982). If your sales contract a1 lows it, and the selling price can justify it, you most assuredly want to build a fine coal circuit into your preparation plant. In general today, most new preparation plants do have fine coal cleaning circuits. The purpose of fine coal cleaning has changed with time. Some of the early applications of fine coal cleaning were to prevent stream pollution rather than to prepare a product for market (Merrill a Pennington, 1962). During the 50&apos;s, 60&apos;s and into the 70&apos;s the principal thrust of fine coal cleaning was in metallurgical coal preparation. More recently, the emphasis of the 80&apos;s is on steam coal processing. There is no consensus on what is fine coal. Traditionally, fine coal would be anything below 1/4" in size. Because of the advances being made in intermediate coal cleaning processes, i.e. heavy media cyclones and jig cleaning, this discussion will define fine coal as -28 mesh (Aplan, 1987). Figure 1 is a plot of the size ranges of a large number of U.S. bituminous coals. In general the -28 mesh fraction of a bituminous coal will be between 7% and 18% of the ROM feed with reported ranges of 5% to 40% (Aplan, 1987). Consequently, traditional fine coal cleaning is general 1 y involved with a re1 actively mi nor portion of the coal feed. Every effort is taken both in terms of mining and preparation to keep it that way because of the high cost of cleaning fines. The move away from this posture, namely, the techniques to fine grind coal to liberate pyrite is probably the biggest challenge facing fine coal processing today.

Jan 1, 1988

By James A. Pendleton

The Legislature of the State of Colorado adopted House Bill 1223, "The Colorado Surface Coal Mining Reclamation Act" (The State Act), in 1979. This Act provided for the creation of a state regulatory program as accommodated within Public Law 95-87, "The Surface Mining Control and Reclamation Act of 1977" (SMCRA). Section 34-33-121(2)(a) of the Colorado Revised Statutes (CRS) and Section 516(b) of Public Law 95-87, identically require the underground coal mine operator to "Adopt measures consistent with known technology in order to prevent subsidence causing material damage to the extent technologically and economically feasible, maximize mined stability, and maintain the value and reasonably foreseeable use of such surface lands, except in those instances where the mining technology used requires planned subsidence in a predictable and controlled manner..." On July 23, 1980, the Colorado Mined Land Reclamation Board adopted regulations to administer and enforce the State Act. Amendments to the Rules, including the subsidence regulations were adopted by the Board in August of 1981. These regulations require the prediction, monitoring and mitigation of "material damage" caused by subsidence.

Jan 1, 1985

By Evan J. Owen, Virginia T. McLemore

There are tens of thousands of inactive mine features in 274 mining districts in New Mexico (including coal, uranium, metals, and industrial minerals districts). However, many of these mines have not been inventoried or prioritized for reclamation. Many of these mines have existing mine wastes, generated during mineral production, which could have potential for critical minerals, especially since the actual mineral production was generally for precious and base metals and not critical minerals. The purpose of this project is to characterize and estimate the critical mineral endowment of mine wastes and “beta-test” USGS sampling procedures. This project is important to the state of New Mexico because critical mineral resources must be identified before land exchanges, withdrawals or other land use decisions are made by government officials. Future mining of mine wastes that potentially contain critical minerals will directly benefit the economy of New Mexico. Possible re-mining of mine wastes could clean up these sites and pay for reclamation. Furthermore, this project will include training of younger, professional geologists and students in economic and reclamation geology by the PIs.

Feb 1, 2024

By A. A. Compoli

Injecting water under pressure to wet the coalbed in advance of mining reduces mining-generated respirable dust. Owing to economic and geological barriers, water infusion for longwall dust control in the United States is currently limited to the Pocahontas No.3 Coalbed in Virginia. Water is pumped into the coalbed through underground boreholes drilled horizontally from the headgate toward the tailgate side of retreat longwall panels. This paper theorizes that the barriers to widespread utilization of water infusion for longwall dust control could be overcome by long-duration, low-pressure water infusion through vertical gob gas boreholes. Currently, 43% of the 72longwall mines in the United States employ vertical gob gas boreholes. Computer coalbed reservoir simulation suggests that one vertical surface borehole could infuse the same longwall panel area as four horizontal boreholes in the current water infusion system for longwall dust control in the Pocahontas No.3 Coalbed.

Jan 1, 1995