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By T. M. “Mike” Gurr

"U. S. marketable phosphate rock production for the 2018 crop year (July 1, 2017 to June 30, 2018) showed an increase to 27.7 Mt (30.5 million st) from the 2017 crop year production of 27.1 Mt (29.8 million st), as reported to the U. S. Department of the Interior by the mining companies operating in the United States during crop year 2018 (Table 1). Domestic consumption decreased in the 2018 crop year to 23.9 Mt (26.3 million st), as compared to the 27.2 Mt (30 million st) consumed in crop year 2017. U.S. imports of phosphate rock increased to 3 Mt (3.3 million st) for the 2018 crop year from the 1.81 Mt (1.9 million st) for crop year 2017. Imports of phosphate rock were from Peru and Morocco. There was an increase of 2.85 Mt (3.1 million st) in producers’ stocks from 7.45 Mt (8.2 million st) in crop year 2017 to 10.3 Mt (11.3 million st) in crop year 2018 (Table I).For calendar year 2018, Florida and North Carolina phosphate rock production accounted for 75 percent of the total U.S. production, with the balance being produced in Idaho and Utah. The Florida and North Carolina percent of U.S. production is declining. U.S. production of 25.7 Mt (28.3 million st) in calendar year 2018 was produced by five companies at 10 mines in four states and accounted for approximately 9.6 percent of the world production of 267.7 Mt (295 million st) for calendar year 2018 (Table 2).In calendar year 2018, U.S. phosphate production decreased by 2.2 Mt (2.4 million st), while companies increased stocks of phosphate rock by 1.7 Mt (1.9 million st). The domestic production for calendar year 2018 of 25.7 Mt (28.3 million st) represents 78.4 percent of the domestic production capacity of 32.8 Mt (36.1 million st).At present, China reportedly produces more than 50 percent of the world’s phosphate rock. As a result of planned expansions, Morocco production has increased from 27 Mt (30 million st) in 2017 to 33 Mt/a (36 million stpy), which is approximately 12.3 percent of the world’s production, moving ahead of the U.S. production. In calendar year 2018, the U.S. phosphate rock production was 25.7 Mt (28.3 million st), which is less than 10 percent of the world’s production of phosphate rock (Fig. 1)."

Aug 1, 2019

By S. E. Younis

The mining industry is currently looking to better understand, anticipate, and be able to mitigate business and operational risks in order to deliver the rewards of risk taking, and to minimize the frequency and impact of risk on the downside. Assessing risk works from the premise that the identification and management of existing risks can be very challenging, especially when threats are not easy to detect, the likelihood of occurrence is difficult to gauge, and/or the consequences are uncertain. Some approach this as a ?check the box? task, even though fire and safety incidents continue to occur and investigations often find the hazard analyses did not properly identify the cause or consequence. You cannot engineer protective designs and safeguards for causes and consequences that have not been identified appropriately. For the mining industry, risk management is an important tool for making critical decisions and, in some cases, meeting regulatory requirements. Providing high-quality documentation that meets both regulatory and corporate requirements is critical for maintaining safe, uninterrupted mining operations. Risk management is a five-part process: 1. Identify the hazards and their causes, 2. Determine the hazard consequences, 3. Calculate the frequency of occurrence, 4. Quantify the risk associated with the system, process, or procedure, and 5. Provide feasible solutions for the risks

Jan 1, 2012

By D. Z. Mraz, R. S. Jones

Unlike in coal mines where caving methods are used, the subsidence over potash mines in Saskatchewan, Canada, is a function of gradual mining convergence. Because of the presence of high pressure water aquifers over the evaporite salt formations, the mines have to be designed as regionally stable and no caving is allowed. The extracted area converges gradually and the convergence is mainly a function of the extraction and the mining method employed. Consequently, the subsidence rate is very slow and the bridging of the over-lying strata is a considerably more important phenomenon than elsewhere. The paper evaluates a case history of convergence and subsidence in a deep potash mine in Saskatchewan.

Jan 1, 1986

By Y. Luo

Cuando se diseña y operan minas de carbón subterráneas con el método de cámaras y pilares, es siempre difícil obtener un buen equilibrio entre la prevención de subsidencia de la superficie y la obtención de un alto coeficiente de recuperación. En este trabajo se propone una metodología de diseño aplicando la teoría de arco de presión y se detallan los principios y modelos matemáticos involucrados. Se desarrolló un programa de computadora a fin de realizar el proceso de optimización del diseño y fue aplicado a la examinación de un caso documentado en el que había sucedido una falla masiva de un pilar en cascada sobre un área grande en una mina de carbón poco profunda. Los resultados indican que el método de diseño propuesto puede ser aplicado para prevenir la subsidencia y a la vez obtener un alto coeficiente de recuperación para operaciones mineras de cámara y pilares.

Jan 1, 2014

By Y. Luo

In designing and operating underground room-and-pillar coal mines, it is always difficult to achieve a good balance between preventing surface subsidence and achieving high recovery ratio. In this paper, a design methodology applying the pressure arch theory is proposed, and the principles and mathematical models involved are detailed. A computer program was developed to carry out the design optimization process and was applied to the examination of a documented case in which a massive cascading pillar failure had occurred over a large area in a shallow coal mine. The results indicate that the proposed design method can be applied to prevent subsidence while achieving reasonably high recovery ratio for roomand- pillar mining operations.

Jan 1, 2014

By Isabelle Lamb, Manfred K. Lechner, Daniel N. Adams

Sydney Australia’s M5 East Motorway connects southwestern suburbs to the airport. Central to the project are twin 3.8 km roadway tunnels which are mostly driven through rock. In order to come up with the winning tender, the project team developed several unique approaches for tunnel excavation and support. The project’s flat roof with thin shotcrete lining, 20 m wide underground intersections, thixotropic-grout sheathed rockbolts and cablebolts, and new shotcrete testing methods all differ significantly from traditional concepts. This paper presents the design basis and construction methods used to achieve the 100-year design life required by the project’s owner.

Jan 1, 2001

By C. Pattenden

The viability, self-reliance and resilience of small communities are perennial challenges in regional Australia. Recent developments in Australian mining regions seek to govern the minerals industry in a more holistic way that contributes to sustainable futures for affected communities in different contexts. In some areas of the State of Queensland land use conflicts and the cumulative impacts of multiple projects and activities across time and space have come to the fore. In more isolated regions of Western Australia the dominant issues relate to overstretching people, infrastructure and services in predominantly mining towns. In both cases, there is an ambition for regional towns with a strong extractive industry presence to transition into desirable, liveable and affordable cities with a diversified economy. The paper analyses two strategies - the Pilbara Plan in Western Australia, and the Sustainable Resource Communities Policy in Queensland - to identify how these governance instruments are contributing to sustainable development.

Jan 1, 2011

By T. V. Ramey

Heap leaching in certain parts of the world, such as Chile's Atacama Desert, brings unique design problems in the form of possible large differential settlements of the foundation soils due to the dissolution of salts in northern Chile the soils often contain very high concentrations of soluble salts (nitrates, potassium, magnesium, and common sodium). When a leak in the liner occurs, the escaping solution dissolves these salts and triggers differential settlement. If the settlement is great enough, the geo-membrane tears, the leakage increases, triggering more differential settlement. The nitrate plants have experienced many occurrences of this phenomenon where a brine pond will undergo a sudden and complete loss of the impounded liquors. The authors present a simplified technique to quantify the differential settlement resulting from dissolution and provide a method which can be used to select a geo-membrane with suitable flexibility under axi-symmetric (multi-axial) load conditions to tolerate the predicted settlement. (This paper was previously published for Randol Gold Forum 1996 [Ref. 6]).

Jan 1, 1997

By John J. Sammarco, Alan G. Mayton, Elaine N. Rubinstein

Researchers from the National Institute for Occupational Safety and Health (NIOSH) developed a light-emitting diode (LED) area luminaire called the Saturn and conducted a laboratory study using a Fletcher High Dual-boom Mast Feed (HDDR) roof bolting machine. The Saturn luminaire was designed to (1) enhance floor illumination to enable better detection of trip hazards in the interior spaces of a roof bolter and (2) reduce glare that has typically been an issue of concern on roof bolters. This paper reports on the results of achieving the second objective. The existing roof bolter lighting was the baseline and was compared with three versions of the Saturn luminaire relative to light intensity (100%, 75%, and 50%). Discomfort and disability glare data were obtained from 30 participants that comprised three age groups. Discomfort glare perceptions were obtained using the De Boer rating scale, and disability glare was quantified by using Mars Letter Contrast Sensitivity tests. Discomfort glare was reduced at least 3 levels with all Saturn versions. Also, a predictive model was used to estimate discomfort glare, and the results were similar. Disability glare was the least for the Saturn’s 50% intensity, and all Saturn versions had significantly less disability glare than with the baseline lighting. Veiling luminance was calculated and used as another indicator of disability glare. Veiling luminance was 28 to 42 times greater with the baseline lighting as compared with that of the Saturn lighting. Lastly, visibility levels were calculated. The Saturn versions were 4 to 6.5 times better in terms of visibility level.

By W. H. W. Husband

Rock salt has been mined by the solution method for many years in many countries. Attempts have been made in the past in Canada and various other countries to produce potash by the' same method. However, only Kalium Chemicals Limited (1) has been successful, possibly because the conditions in Saskatchewan are the most favorable conditions to be found so far for the development of a solution mining method for potash. There are significant differences in solution mining of rock salt and solution mining of potash. First, rock salt deposits are relatively pure in respect to soluble minerals, whereas potash is never found in the pure state and contains Substantial amounts of other soluble minerals, particularly rock salt. In comparison to rock salt, much less potash is dissolved and brought to the surface for the same amount of water circulated through the orebody. The amount of water to be evaporated per unit weight of product is a major difference. Much greater amounts of water must be evaporated when producing potash and the treatment of the brine is more complicated because other dissolved salts have to be separated. Secondly, the rock salt deposits, particularly the domes, are much thicker. Bed thickness is of prime importance because it determines the yield of a well and consequently the economics of the process. Furthermore, as rock salt provides a strong roof structure, larger cavities can be developed and this prolongs the life of the rock salt well.

Jan 1, 1971

By A. L. Holmes

This presentation in the open pit session deals with the development of a phosphate rock strip mine by CF Industries, Inc., a company that does not presently mine in the Central Florida Phosphate District. Land acquisition, engineering, financing and environmental permitting activities were begun in early 1975; site preparation, environmental monitoring and dragline construction began in mid-1975. The operation is due on-stream in late 1978. The reserve acquisition, permitting, and financing could each easily be developed into a separate paper of interest. Each, however, has been covered before for other mining ventures with similar capital and environment requirements. For that reason, I have chosen to discuss what CF Industries, Inc. is, why it is entering this new sec-tor of the agricultural chemicals business, and, to keep at least some technical basis, what design modifications are possible when the total mine output is used captively and it is unnecessary to have the flexibility to meet the numerous transportation and customer specification considerations. In an attempt to show the size and complexity of the CF organization, a brief description of existing facilities should help show why the big interest in mining phosphate rock.

Jan 1, 1977

By Grant A. Brackebusch

Paste tailings disposal was successfully implemented at the New Jersey mill in Kellogg, ID with two different types of ore feed, a gold ore and a silver ore. The purpose of this paper is to describe the production of paste tailings, including operational problems during commissioning, and also highlight the environmental and economic benefits that were realized versus conventional tailings disposal such as the recycling of process water, increased shear strength and reduced permeability of the tailings mass, and reduced environmental permitting.

By A. Duerksen

"Surface coal mining in West Virginia has supplied energy to the eastern coast of the United States for over a century. Over the years, the coal mining industry has been forced to adapt as societal demands regarding health, safety, and environmental impacts have changed. More recent pressure has called for another iteration of change: long-term post-mining sustainability. The research discussed in this paper investigates one potential solution - or component of a solution - to improve the sustainability of surface coal mining in West Virginia: post-mining wind power. The paper begins with an introduction to the Appalachian region of the U.S. and the role that mining has played in its history, followed by a discussion of the need for sustainable mining and how post-mining wind power may help fulfill it. Data processing methodology of field data from monitoring locations is then explained. The results are then used to estimate the electrical output of a wind turbine. This data is then utilized in a case study discussion of one of the monitored sites. The paper concludes with an analysis of the broader implications of the research and a discussion of future work."

Jan 1, 2011

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 J. F. Burr, D. Snyder, W. Calder

This paper provides a determination of the equivalent level of protection of the international standards relative to similar criteria used by the U.S. Mine Safety and Health Administration (MSHA) to approve two-fault intrinsically safe (IS) stand-alone equipment. U.S. mining law requires such a determination for MSHA to use alternatives to existing standards. The primary issue is to demonstrate that the international standards for equipment evaluation will provide at least the same level of protection for miners as the document currently used by MSHA.

Jan 1, 2018

By J. F. Burr, D. Snyder, W. Calder

This paper provides a determination of the equivalent level of protection of the international standards relative to similar criteria used by the U.S. Mine Safety and Health Administration (MSHA) to approve two-fault intrinsically safe (IS) stand-alone equipment. U.S. mining law requires such a determination for MSHA to use alternatives to existing standards. The primary issue is to demonstrate that the international standards for equipment evaluation will provide at least the same level of protection for miners as the document currently used by MSHA.

Jan 1, 2017

By J. P. Kennedy, O. A. Bascur

Large metallurgical complexes have more data than a small city and these data change as internal and external conditions evolve. Staffing turnover hinders experienced-based decisions especially with simple tools like spreadsheets. Lack of current information can contribute to decisions that result in significant deterioration in the quality of operation. Timely, unified information from sophisticated analyses presented to the broadest possible reach will improve operation. The major innovation is the addition of the web browser to the suite of software people will use with no training – the other two are spreadsheets and graphical presentations – and the consistent organization and transformation of the real time data to support broad access. This paper describes the data transformations and presentation methods necessary for a Web view, especially the special needs of real time data and analysis required for active operations decision-making. Many people inside and outside the complex, not just operators, need timely information that is abstracted, aggregated, organized and unified. Unification and aggregation of real time data presented via the Web opens a new paradigm for collaboration. The analysis tools are as important as the data. These rule-based tools add significantly to the operations database in the form of results stored for viewing with plant data. Mining and metallurgical plants already use many sophisticated analysis tools such as predictive maintenance policies based on statistical analysis vibration analysis, and oil and lube analysis for critical equipment. These add real time events, similar to an alarm package, and unified production information to the operational database. Simple models are used on line to create key indices that provide a real time indication of performance. Key indices include metrics for losses due to plant availability, performance efficiency, and overall process equipment effectiveness. These additional data in the operations database are used for early fault detection, increased production, better quality, higher availability of equipment and faster detection of process bottlenecks. An important feature is the ability for people to create their own key indices and store the results for use by anyone in the plant historian, but accessible by a browser. Keywords: plant information, principle components analysis, data reconciliation, gross error estimation, Internet, Word Wide Web

Jan 1, 2002

By E. E. Maurer

Kerr-McGee has operated the Ambrosia Lake uranium mill since startup in 1958. Tonnage milled per day has varied from 3500-7000 tons. The mill capacity is currently rated at 7000 tons per day. The process consists of two parallel circuits following crushing and sampling, \\lhich include open circuit rod mill grinding, sulfuric acid leach, cyclone classification, and counter-current washing circuits of sand classifiers and slime thickeners. Pregnant solution is clarified and polished by precoat pressure leaf filters prior to amine solvent extraction. Yellowcake is precipitated from the pregnant strip solution with ammonia, filtered and dried.

Jan 1, 1972

By R. Y. Wan

Acid ferric sulfate solution has been used for heap and dump leaching of low-grade chalcopyrite ores and is being considered as a possible lixiviant for the hydrometallurgical processing of copper sulfide concentrates. For many years, researchers have attempted to explain the leaching behavior of chalcopyrite, since the reaction rate kinetics are extremely slow and seem to be significantly influenced by the nature of the reaction product. A summary of conclusions drawn from reported literature on chalcopyrite leaching is found in the paper by Munoz, Miller, and Wadsworth(1) and more recently by Dutrizac.(2) Lowe(3) and Jones and Peters (4) attributed rate control to a surface reaction. Linge,(5) Dutrizac,(6) Bauer,(7) and researchers at the University of Utah(1,8) reported that the reaction rate is limited by transport in the chalcopyrite lattice or through the elemental sulfur reaction product layer. Munoz et al.(1) presented a model, derived from the Wagner theory of oxidation, which is based on the formation of a protective sulfur layer with rate control by electron transport through the insulating sulfur layer. By utilizing Wagner's parabolic oxidation relationships, (9) the following equation was obtained: [ ] where a is the fraction of CuFeS2 reacted at time t, pB is the molar density of CuFeS2, do is the initial diameter of the particle, e is the electronic charge, s is the total electrical conductivity of the sulfur layer, and ?G is the Gibbs free energy for the reaction:

Jan 1, 1984

By Vasilis Androulakis, Caroline Gerwig, Zach Agioutantis

Mining operations that involve caving of the overlying strata are designed so that caving occurs in a controlled manner by progressive overburden failure. However, there are many cases where the overlying strata bridge over the caved area for longer periods than anticipated and desired. As the caved area expands with the advance of the mining panel, excessive amounts of energy accumulate in the roof strata which will be rapidly released when the overburden eventually fails.