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By Chengliang Jliang, B. K. Parek, Xuxin Shao

Of the impurities present in phosphate ore, dolomite is the most difficult to remove due to the similar chemical compositions of the impurities and also adsorption of dissolved species of dolomite onto phosphate. A new amphoteric surfactant was found to be a suitable collector for separation of dolomite from phosphate. Flotation results showed that the new amphoteric collector had a high flotation selectivity for dolomite in wide pH ranges. The flotation study of francolite and dolomite in each other's supernatant demonstrated that the dissolved ions had little effect on the selectivity of the new collector, but were detrimental to the flotation separation using sodium oleate as collector. A phosphate concentrate with 35.2% P2O5 with 90% recovery was obtained using 290 g/t of the amphoteric collector from a mixture of francolite and dolomite containing 26.2% P2O5. The rejection of MgO was 81.41%.

Jan 1, 1999

By S. M. Carpenter

In an ever increasing ?carbon? society; management and growth will be measured by one?s carbon footprint (or output). Industries, especially mining, are under an ever increasing scrutiny of carbon, water and environmental mandates. These mandates are measured by the emissions caused by the combustion of fossil fuels. The fundamental building-block for any business, strategic or management decision must be based on an understanding of one?s ?footprint?. The scrutiny is most stringent for the commodities producers, power producers & fuel suppliers in the energy market. An overview of currently acceptable standards, application of those standards and nuances experienced in collecting the data necessary to analyze and complete a company?s carbon footprint will be presented. A lack of regulation, the fear and expectation of new and ever constraining rules, regulation and a change in the federal administration is a recipe for uncertainty in the marketplace.

Jan 1, 2010

By J. C. Haptonstall

The Bismark Mine is located in northern Chihuahua, Mexico, 150 km (95 miles) southwest of Ciudad Juarez (Fig.1). The ore deposit was discovered in 1979 and was placed in production in 1992. The production rate is about 2.4 kt/d (2650 stpd) from an ore reserve of 8.5 Mt (9.3 million st). Grades currently average about 8% zinc, 0.5% lead, 0.2% copper and 50 g/t (1.46 oz/st) silver. Substantial inflows of water into the underground mine complicate the operation. Complex metallurgy poses another challenge for the operators. Bismark is a joint venture with 90% participation by Minas Penoles, SA de CR of Mexico City and 10% participation by Promociones Industriales Banamex, S A de C V (PIB S A) of Mexico City. Anew company, Minera Bismark, SA de CV was formed to operate the property. Cyprus Minerals was a 40% participant in the joint venture but, in early 1993, sold its share to Minas Penoles. The Bismark Mine is one of the largest new underground mining projects built in Mexico during the last 10 years. It is the country's fifth largest underground metal mine and provides about 1 % of the world's zinc supply at about 50 t/a (55,000 stpy). Bismark is a trackless operation with overall productivities of 7.6 t/manshift (8.4 st/manshift). The 2.4-kt/d (2650-stpd) concentrator started up in March 1992.

Jan 1, 1994

By Peter Cammack

Where raw coal from a mine is treated in dense medium separators ash in the washed product is generally very consistent, provided control of the medium suspension is maintained at a given specific gravity. When, however, the washing process is a Baum jig or other similar apparatus, making a separation at rather arbitrary gravities, the control of the product ash is less accurate, particularly in those cases where the design capacity of the washbox is exceeded by the load of high ash fines. In either of these cases an instantaneous measurement of ash while not essential would be desirable, to check the quality of the washed product and provide operator or management with instantaneous warning of changes in ash. Nearly 60% of all British coal mined goes for electricity generation, to burn at 17% ash, and since the overall average ash content of raw coal as mined is about 30% and varies within a range of 18 ? 40%, incombustible material has to be removed. The ash specification could be met either by total washing, or by washing part and blending the clean coal produced with the remaining untreated coal. Some plants use a straight tonnage split, but generally speaking in Britain it has been found more economical to screen and wash the oversize only. In either case for effective quality control in blending an instantaneous determination of the ash content of the product as it is made has been found essential, since standard ash determination by pyrolysis methods is lengthy and provides information too late to be used in the control of plants blending at the rate of 1000 ton/h.

Jan 1, 1976

By Louis W. Cope

Mongolia is known in western countries as the location of rich dinosaur fossil fields. However, the country is even richer in mineral resources. The Ministry of Industry and Trade reports 6,000 mineral occurrences of 80 metals and minerals. Mongolia has already attracted much foreign investment in the mining sector. Mining is the country’s largest industry. It is responsible for 17 percent of the gross domestic product, 65 percent of industrial output and 57 percent of export earnings.

Jan 1, 2006

By Robert A. Jankowski, J. Harrison Daniel, Fred N. Kissell

Introduction Longwall coal mining in the US has steadily increased since its introduction in 1960. There are now 108 systems operating. (Sprouls, 1986). Advantages of longwall mining include higher productivity, improved safety, and greater coal recovery. Respirable dust, however, is one of the more serious obstacles to realizing the full potential of longwall mining. Early in 1980, the US Bureau of Mines (USBM) initiated extensive in-house and contract research to identify and evaluate effective methods of controlling respirable dust exposure of longwall face personnel (Niewiadomski, Jankowski, and Kissell, 1981). It was found that several control procedures must be combined to assure compliance, using control techniques appropriate to the dust source. These techniques can typically be grouped into the following categories: reduction of dust generation; dilution of dust; capture or knockdown of dust; and dust avoidance. Control techniques can be divided into basic and effective dust control techniques; additional necessary controls; and optional supplementary controls. This information should allow longwall mine operators to select control methods applicable to their particular operations and to develop a dust control plan that meets Federal dust standards. Basic and effective dust control techniques There are three basic dust control techniques (Taylor and Jankowski, 1982) that should be implemented on all longwall mining operations. • A passive barrier or external water spray system design that confines shearer generated dust near the face and away from the operators. • Large quantities of water through the sprays, particularly the drum sprays, to aid in dust knockdown and prevent dust becoming airborne. • A cutting sequence that allows the shearer operators to work primarily on the intake-air side of the lead cutting drum. Shearer clearer There are some poorly designed shearer-mounted spray systems with nozzles directed upwind at the cutting and loading zone of the intake-side drum. These actually carry dust away from the face and upstream of the drum. Where, it mixes with the clean intake air (Fig. la,) and is carried out into the walkway over the shearer operators. The Bureau developed a novel shearer spray system, called the shearer clearer. It takes advantage of the air-moving capabili-

Jan 10, 1986

By V. Rajagopal

Corrosion and abrasion properties of a series of chromium-containing cast iron balls with Cr contents ranging from 0 to 29% was evaluated and compared with austenitic stainless steel and mild steel balls. Marked ball wear tests were performed on artificial ore samples consisting of 95% quartzite with either 5% pyrrhotite or 5% chalcopyrite under a nitrogen or oxygen atmosphere. The electrochemical mechanism was investigated by correlating the corrosive wear with the corrosion currents obtained from potentiodynamic polarization curves under abrasion. An offset in their electrochemical activities was observed somewhere between 16 and 26% Cr. In fact, 26 and 29% Cr cast irons showed an excellent corrosion resistance approaching that of austenitic stainless steel. Flotation recoveries were estimated on a 95% quartzite + 5% pyrrhotite sample ground with various cast iron ball materials under an oxygen or nitrogen atmosphere. Electrochemical results are found to be in good agreement with corrosive wear obtained from marked ball wear test and with flotation results.

Jan 1, 1991

By E. A. Sarver

The Fe(II) regeneration process is an important aspect of Alternate Anode Reaction Technology (AART) for copper electrowinning (EW). In AART, Fe(II) is oxidized to Fe(III) at the anode during EW, and it must be regenerated to maintain recyclable electrolytes. Regeneration is achieved via Fe(III) reduction by SO2(aq), and the reaction is catalyzed by activated carbon particles. To better understand this process, a kinetic model was developed and experimentally validated for the Fe(II) regeneration in the current work. The investigation focused on the primary reaction mechanism and the reaction rate dependence on four variables: carbon particle size, flow rate, initial Fe(III) concentration and initial SO2 concentration. The Fe(II) regeneration reaction is mass-transfer controlled in the presence of activated carbon. Carbon particle size and initial Fe(III) are the most influential factors under the conditions tested. Initial SO2 concentration is insignificant to the reaction rate.

Jan 1, 2007

By Marcus A. Wiley, Gregory Abramov

Borehole mining (BHM) is a remotely operated method of extracting rock material through boreholes by high-pressure water jets. Figure 1 illustrates a BHM tool and fluids circulation. The tool consists of at least two pipes, one for pumping down high-pressure water, the second for delivering slurry to the surface. This article reviews the BHM process. It discusses current and new applications for borehole mining and help the readers determine if BHM is applicable in their situations. Previous articles in ME about BHM explained either a particular project (ME, April 2001, pp. 33-36) or a newest patent in this area (ME, March 1991, pp. 313-318). However, neither one provided an overview on the modern BHM technology.

Jan 1, 2004

By F. Mielli

Mine operation managers are constantly tasked with identifying new ways to produce more, while using less. Mine effectiveness and reliability is the foundation of improving operational performance. Timely decisions need to be made in order to identify production waste. Intelligent data needs to be visualized in real-time. Operational events need to be captured with impacts quantified and root causes identified. Unfortunately, complex information technology solutions often have a very poor success rate, with some reports suggesting 30 percent of complex projects are canceled before completion.

Feb 27, 2013

By Syd S. Peng, C. Y. Chen

Introduction The Surface Mining Control and Reclamation Act was passed in 1977 to put an end to the uneven environmental standards and enforcement established by various coal mining states in the US. One year after passage, the Secretary of Interior was directed to promulgate permanent program regulations implementing Title V provisions of the Act. These regulations were to form the basis for state regulatory programs under the Act and to allow states to assume primary regulatory responsibility. To implement the underground mining provision of the Act, the Secretary is directed in section 516(a) of the Act to promulgate rules. But they must take into consideration the differences between surface and underground coal mining. The regulations developed by the Secretary in 1979, with respect to subsidence control, included: • a subsidence control plan as part of the permitting process; • substantive provisions establishing performance standards for subsidence control; and • provisions providing for the prohibition of mining under perennial streams, impoundments larger than 24.6 dam3 (20 acre ft), and certain public facilities and urban areas. Industry challenged the Secretary's regulations implementing the subsidence control provisions. The litigation was consolidated with all other challenges to the permanent program regulations. (Permanent Surface Mining Regulation Litigation, Civil Action No. 79-1144; D. D.C., May 16, 1980.) In two opinions dealing with the multitude of issues raised by both industry and environmental groups, the US District Court of the District of Columbia ruled against industry. It upheld the promulgated subsidence control provisions. The US Court of Appeals stayed the appeals pending the agency's review and revision of its regulations. The regulatory reform was conducted in accordance with the order from the Secretary of Interior and the President in 1981. As a result, the subsidence control regulation was revised, reproposed, and finalized in June 1983 (Federal Register). This regulation, along with others, was again challenged by environmental groups and industry. On Oct. 1, 1984, the court, after finding the Secretary's reading of the Act reasonable, upheld the 1983 subsidence regulation except for one section. On Feb. 21, 1985, in accordance with the court's ruling, the Office of Surface Mining (OSM) suspended a portion of 30 CFR 817.121 (c)(2) concerning the damage correction requirement for structures or facilities and reproposed it on July 8, 1985 (Federal Register). In conjunction with a request for public comments, OSM now also seeks comments on the omission from the 1983 rule of the requirement in the 1979 rule regarding a presubsidence survey and monitoring of damage to structures. Technical issues related to subsidence regulations The subsidence regulations of June 1, 1983, consist mainly of two parts: a subsidence control plan as part of the permitting process; and substantive provisions establishing performance standards. The latter also includes provisions for prohibiting mining under certain areas. Under subsidence control plan section 784.20, minimum require-

Jan 2, 1986

By D. Rendini, R. D. Gutridge

INTRODUCTION Gwinnett County, Georgia, is a part of the rapidly expanding metropolitan Atlanta Georgia area. Located approximately 48 km (30 miles) northeast of Atlanta, Gwinnett County has a current population in excess of 600,000 and is projected to reach a population of 1,200,000 by 2025. As a part of the County’s master plan to supply drinking water for the expanding population and to increase system reliability, the Gwinnett County Public Utilities Department undertook the Shoal Creek Raw Water Intake and Pump Station Project. Figure 1 shows a vicinity map for the project. Prior to construction of the Shoal Creek Raw Water Intake and Pump Station Project the County had a single raw water intake to feed water from Lake Sidney Lanier (Lake Lanier) into a filter plant for processing into potable water. This project together with a newly constructed water filter plant provides Gwinnett County additional capacity and system redundancy to prevent interruptions to the drinking water supply. Lake Lanier is a man made reservoir with over 800 km (500 miles) of shoreline and was constructed by the Army Corps of Engineers in the 1950s for hydro electric power generation, flood control, and navigation benefits for the Chattahoochee River. Over time, Lake Lanier has become an increasingly important source of drinking water for the metropolitan Atlanta area. This paper focuses on the primary underground construction and lake tap components of the project including a 42.7 m (140 ft) deep pump station shaft 24.4 m(80 ft) in finished diameter transitioning to a 6.1 m (20 ft) finished diameter shaft, a3.05 m (10 ft) finished diameter by 19.8 m (65 ft) deep intake shaft constructed in an average of 21.3 m (70 ft) of water, and a 190.5 m (625 ft) by 3.05 m (10 ft) finished diameter modified horseshoe tunnel connecting the two shafts. This raw water intake system, in conjunction with the incorporated pump station with 8 pumps and dual1,829 mm (72 inch) pipelines, provides a system capacity of 1,091,062 m3/day(240 MGD) to two water filter plants and is expandable by the addition of pumps to1,500,210 m3/day (330 MGD). Parsons provided design and construction management services for the project. The $29.6 million contract to construct the project was awarded to W.L. Hailey &Company. Notice to proceed was given August 6, 2001 and substantial completion was achieved on January 20, 2004. Value engineering changes adopted for the project contributed to completing the project at a final cost of $28.8 million.

Jan 1, 2005

Based on X-ray phase analysis and exploratory experiments, a new technology was developed to recycle multiple valuable elements in spent Al2O3-based catalyst. The experimental results showed that after roasting at 750°C for 30 minutes at an Na2O:Al2O3 mol ratio of 1.2, the leaching recoveries of alumina, vanadium and molybdenum from the spent catalyst were 97.2%, 95.8% and 98.9%, respectively. Vanadium and molybdenum in sodium aluminate solution can be recovered by barium hydroxide and barium aluminate. The precipitation recovery of vanadium and molybdenum was 94.8% and 92.6%, respectively. Al(OH)3 is prepared from sodium aluminate solution using the carbonation decomposition process. The purity of Al2O3 is 99.9% after calcinations, and the recovery of alumina can reach 90.6% in the whole process. The Ni-Co concentrate was leached with sulfuric acid, and a nickel recovery of 98.2% and a cobalt recovery of more than 98.5% were obtained under the experimental condition of 30% (w/w) H2SO4, 80°C, a liquid: solid ratio of 8:1 (by weight), a reaction time of 4 hours and a stirring rate of 800 rpm.

Jan 1, 2007

By A. Habibi

The ventilation survey was conducted in an underground longwall trona mine. The mine is relatively shallow and categorized as a gassy mine. The ventilation system consists of nine shafts (three intakes and six exhausts). Three surface based axial fans ventilate the mine configured in a blowing arrangement. Following the ventilation survey airflow quantity, frictional pressure losses and air psychrometric characteristics have been quantified. An accurate resistance survey has been conducted to calculate the pressure drop with regard to moving cages and skips in the shafts. This paper discusses the benefits of utilizing high accuracy digital pressure transducers and psychrometers in a ?leapfrogging? survey to gather data needed to build the computer ventilation model. Two underground booster fans with VFD are currently idle but available at the mine. The ventilation model has been used to determine the optimal booster fan locations to decrease the overall operating cost by reducing the load carried by the main fans. A leakage study has been conducted to evaluate the effects on the system of additional pressure from a booster fan. The study finally prepares a future ventilation model for the next fifteen years of mine operation and investigates the effect of proposed scenarios.

Feb 27, 2013

By Jeffrey D. Thatcher, Debra W. Struhsacker

With the burgeoning development of precious metals heap leach mining projects throughout the country regulatory agencies are beginning to take a closer look at the short-and long-term environmental consequences of heap leach mining. This increase in regulatory review is occurring on federal, state and local levels, and is affecting both large- and small-scale mining developments. Small-scale mining developments are receiving especially critical regulatory scrutiny because in the eyes of some regulatory agencies, small developers lack the credibility automatically accorded to major mining companies. This is due in part to a bad image of small miners based upon past environmental problems and permit violations caused by a few, small operators. The proponent of a small mining development thus faces special problems during the project permitting process, and must convince the regulatory authorities of his company's ability and commitment to plan, develop, and decommission a mining operation in compliance with environmental regulations. Not only must the small developer have a thorough understanding of the regulatory requirements affecting his project, he must also devote considerable effort to careful internal planning in order to produce a well organized approach to project permitting. The importance of proper planning cannot be overstated. Project planning is key to convincing the regulatory agencies that the small miner is capable of developing a viable project. More- over, the economics of a small mining project demand permit acquisition at modest cost and in a timely fashion. A well planned permitting effort will thus ensure that permits are received within budget and on schedule. This paper will review the federal, state, and local permitting requirements for heap leach projects, and the variability of these requirements from state to state. The environmental assessment process for projects developed on public lands, and the acquisition of zero- discharge water quality permits, air quality permits, and local special use permits as they apply to small mining developments will be discussed. The paper will conclude with a review of project decommissioning and cyanide neutralization requirements and their implications for small-scale heap leach projects.

Jan 1, 1987

By Bradford F. Townsend, Colin R. Speers

INTRODUCTION This is the first in a series of papers addressing practical tunnel lining design. The format for this and future papers is to present a particular topic and support the presentation of the guidelines by the practical application of a case history. The primary intent is to provide guidelines for the geotechnical and structural design of tunnels where the tunnel size and/or ground conditions dictates that systematic support of the excavation is required following each increment of excavation. This method of tunneling is commonly referred to as Sequential Excavation and Support(SES) and is also commonly termed the New Austrian Tunneling Method (NATM) The authors developed the design guidelines from experience gained over the past two decades during the design and construction of several major railway, highway and water-transfer tunnel projects in Africa and Asia. During this time it has been possible to compare the performance of the as-constructed structures to the predicted performance as given by the design process. Excavation was typically carried out in widely varying ground conditions (weak-bedded rock, jointed hard rock, and soil-like poorly cemented rock with groundwater). It is therefore intended that the design guidelines could be applied, in general terms at least, to any tunnel excavated in any ground mass condition with any ground material type (hard rock, soft rock, bedded rock, soft ground, and soil) with or without ground water. This first paper is an introductory paper that defines the scope and a brief outline of the design issues that may be presented in detail in later papers. What is design? It may be thought of as any rational/verifiable/justifiable process whereby a concept is transformed into information that can be used to bring the concept to reality. In the case of a civil structure, design may be defined as that process, which is documented and can be audited, that determines information such as the shape (form) of the structure, the dimensions (size) of the structure, the thickness and strength of structural members that comprise the structure, etc. This information can be used to compute the time, money and resources required for

Jan 1, 2005

By Ravi Ray, Kostas Kaklis, Zach Agioutantis

"Modern underground mining is becoming more complex and geotechnically challenging. The engineer uses numerical, analytical, and data-driven methods (empirical and/or experimental) or their combination to overcome these challenges. Each method has its advantages and disadvantages. Nevertheless, given the amount of innovation and experience involved in developing each of these techniques, it will be prudent to use all their benefits rather than favoring one technique over the other. Pillars are the most important support element in an underground mine. A holistic geo-mechanical solution needs to be determined to design mine pillars using a proper sequence and exact mix of the three methods. A combination of these methods, in sync, can encompass the several advantages of the three methods while eliminating their disadvantages. This paper presents a conceptual three-tier solution to the pillar design problem, to improve its design pedigree, using a proper combination of numerical, analytical, and data-driven methods. At the focus of this proposed method lies the Ground Reaction Curve (GRC) concept.INTRODUCTIONAlthough the stability analysis of underground excavations is a challenging problem, its understanding has improved tremendously over recent years through the use of improved tools and techniques. The trial and error method was replaced with more scientific methods like the empirical and analytical methods that are still in use today. Empirical methods were developed based on large data sets obtained from experiments and observations (e.g., coal pillar strength equations). Analytical methods were developed based on mechanical understanding of stability (e.g., safety factor for vertical pillar loading, Convergence Confinement Method). Improvement in computing power and numerical techniques led to the development of several numerical methods (e.g., finite difference, finite element) suitable for geo-mechanical analysis.Each of these methods have certain advantages and limitations. Nevertheless, the user is often puzzled over the proper method selection and over the proper sequence of using them. This exercise becomes more challenging when different methods are combined, where, for example, one has to estimate the pillar strength based on empirical equations (e.g., Mark-Bieniawski coal pillar strength equation), determine the factor of safety based on an analytical approach (e.g., tributary area load divided by pillar strength), and analyze pillar-strata interactions using numerical analysis (see Esterhuizen, Mark, and Murphy, 2010b).Challenges increase when current pillar design methods are designed as passive structures to balance the fixed dead weight of the overburden. This classic suspension design approach does not recognize the self-stabilizing capacity of the overburden (Frith and Reed, 2018). A practical solution to address these issues is the use of numerical analysis. However, one should always keep in mind that the numerical modelling approach may have certain practical limitations."

Jan 1, 2019

By Steve Kral

The mining industry is no stranger to hard times. Throughout its history, the industry has faced the ups and downs of commodity prices, difficult-to-mine-and-process ore bodies, labor issues and other problems. Throughout it all, though, the mining industry continues to provide the materials needed for society —even in the face of attacks by those who seek to cripple the industry or have it go away. The reason the mining industry survives, of course, is that mankind requires the products the industry produces. And, in recent decades, the industry has developed new technologies and improved on existing ones to produce those products in environmentally sound ways. At the same time, the economic benefits have been enormous to communities throughout the world where mining takes place.

Jan 1, 2002

By F. Freme

Coal production in the United States increased in2004 by 36 Mt (39.7 million st) to end the year at 1 Gt(1.11 billion st), according to the U.S. Energy Information Administration (EIA). This was a 3.7-percent in-crease from 2003’s 971.6 Mt (1.07 billion st) (Table 1).(All percentage change calculations are done at the short-tons level.) Although U.S. coal consumption rose in 2004, not all coal-consuming sectors had increased consumption for the year. Coal consumption increased in the electric power sectors by 1 percent and declined slightly in the other industrial sector, while coking coal consumption dropped by 2.4 percent. U.S. coal exports rose for the second consecutive year, while coal imports again increased to record levels. Coal stocks declined during the year, as electric generators used their stockpiles to helpmeet increased demands and missed shipments. Coal producers used their stockpiles to supplement their production levels.

Jan 1, 2005

By E. Galán

The largest Spanish kaolin deposits formed on granites occur in Galicia (NW Spain) due to a widespread kaolinization of Variscan granitoids. This paper provides insight of the origin of this kaolinization process on the basis of a mineralogical and geochemical study carried out in two kaolin deposits, presently mined to be used in the paper industry. Mineral composition of the deeply kaolinized rocks is dominated by well-ordered kaolinite with minor quartz, K-feldspar, mica (illite/muscovite), locally gibbsite, and traces of resistant accessory phases (rutile, ilmenite, zircon and monazite). The content and structural order of the kaolinite decrease with depth. Kaolinite formed by extensive replacement of feldspars (plagioclase). Differential mobilization of major and trace elements during kaolinization has been inferred by using a mass-balance approach. Significant amounts of Na, Ca and minor Mn, Sr, P and U were removed from incipiently leachable minerals (plagioclase and apatite), and K, Rb, Cs and Ba were released from K-feldspar and mica. On the contrary, Ti, Zr, Th, Hf and the REE are retained in the resistant trace minerals that are concentrated in the fine fractions of the kaolins.

Jan 1, 2010