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By J. D. Morgan

The US economy grew steadily in 1989, reaching an annual rate of $5.3 trillion in the last quarter (US trillion=1012 ). The value of domestically processed, mineral-based materials rose 5% to $315 billion (US billion=109). The value of metals produced from US ores rose 14% to $11.6 billion, while industrial minerals rose 2% to $20.2 billion. Recycled scrap was valued at $10 billion. Increasing economic activity stimulated metal prices. Yearly lows and highs were $2.31 and $3.56/kg ($1.05 and $1.62 per lb) for copper, $1.58 and $2.57/kg (72 and $1.17 per lb) for aluminum, 77 and 97 cents/kg (35 cents and 44 cents per lb) for lead, and $1.58 and $2.09/kg (72 cents and 95 cents per lb) for zinc. Many mining and metal companies reported reasonable profits. Consumer demand strongly affects mining because the US economy is saturated with long-lived products. Consumer, mortgage, and Federal debt continued to rise. 250 million US citizens already possess 172 million licensed motor vehicles and 100 million dwelling units. New car production fell 4% to 6.8 million units, while truck and bus production fell 1 % to four million units. New housing starts fell 9% to 1.4 million units. Imports supplied a significant proportion of total US consumption of several important mineral materials. Imports of crude and refined petroleum costing $50 billion exceeded domestic crude oil production. President Bush expressed "strong concerns about this country becoming further dependent on foreign oil." And the Department of Energy held a series of hearings around the country to develop ideas for a "national energy strategy."

Jan 1, 1990

By Donovan F. Symonds

INTRODUCTION The selection of the optimum coal preparation plant flowsheet is a vital part of the development of a new plant or the expansion of an existing facility. Selection of an inappropriate flowsheet or individual equipment items can result in costly production losses, or needless expenditures or redundant or oversized equipment. The accuracy of the flowsheet selection process is, like most decisions, heavily dependent upon the amount, reliability, and quality of the database. A flowsheet which is based on simple borehole information from an area that has experienced little or no previous mining activity must necessarily include significant allowances for uncertainties. However, a plant which is to be built at an existing mine with good information on run-of-mine (ROM) coal quality, as well as bulk washability data and accurate projections of future quality, can be optimized. The following chapter will describe the processes which should be followed to select the most appropriate flowsheet for each unique operation. They include: 1. Examining and adjusting the washability database to reflect the ROM feed. 2. An evaluation of clean coal specifications. 3. Selection of the level of washing required. This includes no washing, if the coal is already at the desired specification, all the way through to complex total washing circuits for metallurgical grade coals. 4. Selection of the appropriate circuit such as dense medium bath vs. Baum jig. The most appropriate circuit is generally determined on the basis of economics. An approach for performing the evaluation will be desired. 5. The steps that need to be followed to develop a balanced plant flowsheet. ADJUSTING WASHABILITY DATA It is not unusual to have as many as 10 to 20 sets of washability information available for a particular mining property. These may be a combination of core and bulk samples or all bulk samples. In the latter case, they may also be face and/or ROM samples. It is necessary to reduce all of this information to a single set of washability data that is representative of the mean feed to the proposed preparation plant. This set is used to compare the clean coal yield and quality characteristics of the various flowsheet options. The term "representative" has some serious negative connotations. It is recognized that ROM coal quality will vary throughout a mine. However, over a period of 250 to 350 days per year, certain trends can be established. If possible, this "representative" sample should be close to the coal quality of the mean daily sample in terms of raw ash and sulfur contents, clean coal yield, and clean coal ash and sulfur content. If possible, this sample should be within the

Jan 1, 1991

By Yi Luo

Subsidence events occurring above inactive room-and-pillar (R&P) mines, including abandoned mines or sealed portions of active mines, are classified as unplanned subsidence, because of their timing and distribution are unpredictable. When investigating such subsidence cases, many uncertainties exist and disputes often focused on whether the observed structural damages are caused by mine subsidence or other natural or artificial causes. However, solid evidence to identify the cause is often lacking. In order to conduct a complete and impartial investigation, thorough knowledge of subsidence theories and other ground control topics, as well as broad experience, are required.

Jan 1, 2011

By R. L. Grayson

The health and safety of employees, efficiency of the operating system and production are paramount goals in underground coal mining. The section foreman assumes responsibility for making his part of the total system function to meet these goals. However, section foremen often have not been prepared to assume the full range of their responsibilities upon becoming a supervisor. This discussion addresses the full range of section foreman responsibilities and concomitant authority. Management principles that must be mastered by him are presented, and performance expectations as well as criteria for their evaluation are examined. The benefits realized from effective foreman training are discussed.

Jan 1, 1985

By N. W. Johnson

Two analysis tools which have been applied to problems in industrial Flotation processses are the application of kinetics and detailed mineralogical or liberation data, both on a size-by-size basis. The paper describes practical examples of the application of kinetics to examination of the entrainment recovery mechanism, the retardation of valuable minerals at the commencement of flotation sections and the resolution of problems related to valuable species with reduced rate constants at the end of sections. Examples of the usefulness of size-by-size liberation data for monthly composite samples of products from a concentrator are also described.

Jan 1, 1985

The Cutoff grade optimization is very critical to the open pit production scheduling. In case of single mineral deposits, algorithms have been developed for determining cutoff grade policy that maximizes the net present value (NPV) of yearly cash flows. For deter-mining the cutoff grade policy for projects with two minerals including stockpiles the problem becomes much more complex. The purpose of this paper is to present fundamentals of a generalized cutoff grade optimization algorithm that will maximize the NPV of a project subject to mining, milling, and marketing constraints. Benefits of the methodology developed are demonstrated on three different case studies.

Jan 1, 1997

By Lex L. Udy

External detonation generated plasmas, highly ionized zones of reacting material ejected from the surface of detonating ex-plosive charges, are shown to be the cause of channel desensitization, i.e., the self-quenching of a detonating explosive column loaded in a borehole with an air annulus between the explosive and the borehole wall. The effects of this phenomenon on several explosive compositions and types are demonstrated and discussed. Explosives tested include aluminum sensitized and explosive sensitized slurries, ANFO, liquid explosives and dynamites. Various techniques are described that can be used to reduce or eliminate the plasma effect.

Jan 1, 1978

By M. Trim, Y. Sun, D. Tepavac, A. Kumar

Configuration of Rozelle Interchange Project’s ventilation system required design and construction of some of the largest and tallest underground civil caverns attempted in Australia. The paper focuses on the technical challenges of designing these caverns within a heterogeneous, generally weak sandstone under highstress conditions while providing a construction sequence that would align with the contractor’s preferred techniques and schedule. Various construction techniques were investigated, but ultimately an observational approach relying on a construction sequence and specialized instrumentation met both the designer’s and contractor’s requirements. Relevant data obtained from excavations and the construction monitoring program are presented within.

Dec 1, 2022

By J. C. Haptonstall

Stoping methods at the Homestake Gold Mine through 1978 had been traditional overhand cut-and-fill, shrinkage or square set. High costs, low-productivity and safety concerns prompted the mine to search for and adopt a "bulk mining" technique as a primary stoping method. Blasthole stoping had been successful but it is very development intensive, and was not suitable for the mine's accelerated mining program. Vertical Crater Retreat stoping was selected, and today accounts for over 50% of ore production. Case histories representing both the successes and failures of VCR stoping in the mine are discussed.

Jan 1, 1986

By G. A. Rosario, G. Peach

Twin 8.5 m diameter, 10 km long headrace tunnels under overburdens of up to 1870 m were excavated for the neelum jhelum hydroelectric project in north-eastern pakistan using two main beam gripper tunnel boring machines (tbms). Rock bursts were encountered and presented a significant danger to personnel and equipment. Micro seismic monitoring was installed to analyze rock burst characteristics and to create a database for future reference. Correlation of rock burst characteristics improved the ability to predict the likelihood, location, severity, and number of rock burst events. This paper presents the analysis of the micro seismic data

Dec 1, 2022

By Amin Mousavi, Soroush Khazaei, Yashar Pourrhimian

As a factory-like method, sublevel caving consists of development activities, stockpiling and production activities that are carried out on different levels independently. Therefore, considering the operation from the development phase to the plant will lead to more reliable production scheduling. This paper presents a mixed integer linear programming framework for the long-term production scheduling of sublevel caving that maximizes the net present value while satisfying development activities, mining, and processing capacities, continuous mining, the allowable number of active mining units, grade blending, and vertical and horizontal sequencing. The model is coded in Jupyter Notebook and is solved using the CPLEX solver.

Jun 25, 2023

By Qingqing Huang, Aaron Noble

The Mineral & Metallurgical Processing Division (MPD) of the Society for Mining, Metallurgy & Exploration held the first MPD Student Video Contest during the spring of 2021. The event showcased the work of 18 graduate and undergraduate students from several U.S. and international institutions. The contest began in January when students submitted a onepage abstract for judging. Over the next several months, they developed a three-minute video that further explained their research findings. Both the abstract and video were evaluated by a panel of judges, and the top-placing participant was recognized at an MPD virtual event held on June 10.

Sep 13, 2021

By X. Cheng

A series of batch flotation tests was performed on chalcopyrite-quartzite, pyrrhotite-quartzite, and on chalcopyrite-pyrrhotite-quartzite mixtures. Pulp potential measurements in the flotation tests of single sulfide minerals indicated that each sulfide mineral had its own optimum potential range for flotation. When these results were used to select the potential ranges for the separation of the two minerals from their mixture, their flotation responses changed and the selectivity of separation was adversely affected. A possible mechanism involving surface alteration through galvanic interaction is discussed. A method to improve the selectivity of flotation separation was proposed.

Jan 1, 1992

By David A. Heitman

The Buick Concentrator is a highly automated operation which utilizes a process control system for continuous monitoring and control. The process control system development, installation, and application to the concentrator grinding and flotation circuits are presented in this paper. The design and implementation of analog field sensing instrumentation, a continuous on-stream X-ray analyzer, grinding and classfication circuit controls, and a recent digital process control system utilizing a centralized computer are discussed. Emphasis is placed on the project planning and installation of the digital control system including a presentation of future plans for continuing application of computer control.

Jan 1, 1982

By Ke Yang, Kai Zhang, Xiaolou Chi, Xiangyang Zhang, Yingming Li

Based on the research background of 1303 working face return air roadway in Jinyuan Zhaoxian Mine, Shaanxi Province, a method of determining the reasonable spacing of boreholes is proposed based on the stress transfer degree of coal above and between boreholes, combined with the law of plastic zone and energy evolution by theoretical analysis and numerical simulation. After drilling pressure relief, the average daily energy of microseismic events decreased by 70%, and those with microseismic energy greater than 104 J decreased by 99.2%. The research has a strong guiding significance and research value for determining the reasonable distance of borehole pressure relief.

Jun 25, 2024

By D. S. Yantek, C. B. Brown

The mining industry is beginning to implement lithiumion batteries (LIBs) to power mine utility vehicles (MUVs) and rubber-tired mantrips (RTMs). However, the ability of LIBs to withstand the harsh conditions for these applications has not been rigorously evaluated. Concerns with the use of LIBs in the mining environment will be discussed including the effects of mechanical shock and vibration, temperature extremes, and moisture exposure. This paper will discuss adverse effects of the mining environment on LIBs and provide an overview of scientific gaps associated with the environmental susceptibility of LIBs used on MUVs and RTMs.

Feb 1, 2024

By Jupneek Singh, Zachary A. Kiehl, Leila Safazadeh, Gareth Kennedy, Eleonora Widzyk-Capehart, Jeremy W. Ward

Mine workers are continuously exposed to a host of nonfatal stressors and potentially fatal hazards: noise exposure, excessive vibration, poor air quality, toxicant exposure, ignition of combustible gases, equipment-related accidents, and thermal heat stress. Wearable or portable sensors and contextual analytics provide a platform to unobtrusively collect and fuse multimodal health and safety data in real time to compute both acute safety and longitudinal health insights. This paper presents preliminary trial results, conducted by Simtars, VigiLife, Inc., and Queensland Mines Rescue Service, of the application of wearable sensors to monitor heat stress and other vital biometrics for mines rescue personnel.

Feb 1, 2024

By D. D. Harbuck

The U.S. Bureau of Mines investigated germanium and gallium extraction from an ore containing 0.089% Ge and 0.036% Ga. While previous researchers concluded that a reducing agent such as 502 is needed to extract germanium and gallium from such ore, this research showed that high extractions (87% Ge, 97% Ga) were possible using sulfuric acid alone, if the acid concentration were properly controlled. This control was achieved using a two-stage counter-current leach circuit. Microprobe analyses revealed that the non-extracted germanium is in solid solution with quartz, and therefore cannot be leached with 502 or sulfuric acid.

Jan 1, 1991

By J. F. Barry

Newmont Mining Corporation and Barrick Goldstrike Mines, Inc. concluded an exchange of land and reserves in an agreement signed May 3, 1999.This exchange of assets allowed Newmont to develop the Deep Post underground mine from within Barrick’s Betze-Post open pit, thus reducing capital expenditures, lowering operating costs, and advancing the production schedule by nearly three years. Based on previous experience, Newmont is confident that the Deep Post underground mine can be successfully developed and operated within a large, active, open pit mine. The project also faces difficult geotechnical conditions including weak ground, scattered pockets of groundwater, and elevated rock temperatures.

Jan 1, 2000

By Daniel Willis, Ryan O’Connell

An 8-foot tall horseshoe adit tunnel located within an abutment of the Mount Morris Dam in Mount Morris, NY required repair of a failed reinforced concrete liner. The adit tunnel is entirely founded within highly weathered shale bedrock units, which induced unloading stress on the original tunnel liner. An epoxy-impregnated carbon fiber fabric wrap manufactured by Sika was chosen to repair the failed adit tunnel liner. Kilduff Underground Engineering completed the design of the tunnel repair utilizing both empirical and numerical methods. Merco Engineering Contractors completed the injection of chemical grout and repair liner installation.

Jun 23, 2024