Search Documents

By W. J. Atkinson

Since the inception of the Ashton (formerly Kalumburu) Joint Venture in 1972 the parties have expended 524 million in exploration for diamonds in the Kimberley region. This has resulted in the discovery of the currently subeconomic Ellendale deposits in 1976/77 and the economic Argyle - Smoke Creek Deposits in 1979/80. In addition to Argyle and Ellendale some 90 kimberlitic and lamproitic bodies have been discovered grouped broadly into three provinces, on the west, east and north margins of the Kimberley block. These bodies range in size from dyke-like features less than one metre in width to pipes with a surface area of 128ha. The bodies with larger surface area are volcanic crater deposits, infilled with air-fall and water deposited tuffs and epiclastic sediments.

Jan 1, 1984

By James M. Barker

The borate deposits of Death Valley, first exploited in 1882, were a major world source of boron-bearing products until shortly after very large deposits near Boron, California (Kramer) came on stream in 1926. Borate mining in Death Valley then became moribund, with most extant deposits held as reserves backing Kramer. Tenneco began borate operations following acquisition of claims in 1967 and is the only active borate producer inside Death Valley National Mon¬ument. Borate ores, confined to the lower Furnace Creek Formation (early to middle Pliocene), initially precipitated in a shallow lake fed by boron-rich volcanic hot springs associated with the Basin and Range province. Later diagenesis and remobilization plus regional folding, faulting, and erosion altered and complicated originally simple borate mineralogy and distribution. Dominant ore minerals are ulexite (NaCaB509.8H20), probertite (NaCaB509.5H20), and colemanite (Ca2B6011.5H20). Tenneco currently operates two open pits near Ryan, California. Mining is by bulldozer-pushed scrapers hauling waste and front-end loader/off-highway truck combinations for ore and waste haulage. Archeological, environmental, and aesthetic considerations influence both mine plans. Boraxo Pit, opened in 1970, has deep ore (stripping ratio 10 to 13:1) which occurs along a fault and as beds in shale on the hanging wall. Problems include pit wall instability (adverse bedding), non¬ripable calcareous shale (11,000 fps), and mixed ore separation. Sigma Pit, opened in 1975, has shallow (stripping ratio 1 to 1). low dipping, bedded ore in shale. Massive ulexite and "granular" un- cohesive colemanite present problems in mining and milling. Colemanite is crushed to -6 inches, washed, dried at 350°F, then calcined at 800°F with 100 tpd capacity. Crushed (-6 inch) ulexite or probertite is Raymond milled to customer specifications with a capacity of 1000 tpd.

Jan 1, 1976

By J. L. Huiatt

The U.S. Bureau of Mines and Great Salt Lake Minerals and Chemical Corp. developed a froth flotation process for concentrating potassium salts from Great Salt Lake solar evaporites containing about 5 percent K. The crude evaporites, which were predominately halite (NaCl) with smaller amounts of kainite (KCl.MgSO4.2.7H20) and schoenite (K2SO4MgSO4.6H20), were conditioned in a saturated brine solution, thus converting nonfloatable kainite to the floatable mineral schoenite. Schoenite was then selectively floated with a medium-molecular weight fatty acid. Continuous small-scale pilot plant testing indicated that 80 percent of the potassium could be recovered from the crude evaporites in flotation concentrates assaying about 11 percent K.

Jan 1, 1975

By Donald R. Williamson

The Cyprus Pima Mining Company's open pit operation was started in 1957 with the normal assumption that the ore reserve estimate was accurate within an acceptable range of values. At that tine reserves were law - volume (+10 million tons) and high grade (+1.5% Cu). Several periods of growth have brought the operation to its present production level of 55,000 tons per day of ore and +125,000 tons of waste. Over the years, a number of attempts to refine and polish the ore reserve figures have been made using a variety of established standard procedures. None of these attempts have produced results which are totally satisfactory, particularly when comparisons are made between ore reserve estimates and short to medium range production figures. Other refinements were tried using adaptations of established methods combined with computer modeling techniques. The resulting mine-model ore blocks were an improvement but they still tended to show too match tonnage of mill feed, often at too low a grade. One attempt at Kriging had only limited success. Statistical studies of operations data revealed relationships which could be used to subdivide ore blocks in much the same way as they are actually mined. Comparisons thus far between these newly developed ore blocks and production data show that the new method of evaluation yields excellent results. A new, better procedure for estimation of ore reserves apparently has been developed for the Cyprus Pima deposits. The specific procedures seem likely to have direct application to other, similar operations. The methods used to develop the procedures could be of value to still other operations.

Jan 1, 1976

By Jin Zhao, Weijie Wei, Jinwang Zhang, Xiaohang Wan, Shengli Yang

Reasonable mining-retention ratio (ratio of room width to pillar width) is vital to recovery rate and stope stability in underground mining of solid potassium salt deposits. Based on the engineering background of a solid underground potassium salt mine in Khammouan Province, characteristics of the plastic zone of the pillar, and the variation of recovery rate and stope stability under different mining-retention ratio conditions are discussed. The results show that compared with current room width (8 m) and pillar width (10 m), the optimization method of improvement of stope stability. The research results are helpful to recover as much solid potash resources as possible under the premise of ensuring the stability of stope.

Jun 25, 2024

By J. Klemenic

This paper presents an analysis of gold production and prices over an extended period. Production patterns are provided for the world as a whole and for the five major producing countries. Gold prices as a function of interest rates, as measured by municipal bond rates, are given for the period 1947 to the present. World gold production has had a phenomenal increase since 1980, with the exception of South Africa, all major producing nations participated in this increase, even though the price of gold generally has been decreasing since the high level attained in 1980.

Jan 1, 1993

By Aydin Shaterpour Mamaghani, Bilgin. Nuh, Engin Dogan, Tayfun Erdogan

"Improved safety and more environmentally friendly operation are basic advantages of mechanical excavation over the drill and blast method. Raise Boring Machines (RBMs) are one of the types of these machines which have recently been increased use in Turkey. The excavated hole with RBM is more stable than other methods and has better air flow, making it ideal for ventilation shafts. This paper is a summary of the performance of a RBM in the Balya PB-Zn Mine in Turkey. Length and diameter of the ventilation shaft are 200 m and 2.4 m, respectively. The geological and geotechnical characteristics of the strata excavated in the mine are first given and later the validity of a model developed to predict the machine performance is discussed. It is believed that the results of this study and the model given to estimate the performance of the RBM will be useful guide for future applications. INTRODUCTION Raise boring technology was developed to meet the demands of the mining industry, but has also found numerous applications in tunneling or infrastructure projects for ventilation purposes. Raise boring machine uses a small diameter drill rod, around 230-350 mm to drill a pilot hole down to the required depth up to around 2000 m. Once the pilot hole has been drilled to the desired depth, a reamer of up to 9 m diameter is attached to the drill rod. The reamer is then pulled back up to the upper level, creating a round shape. Continues operation provides a faster advance rate than other methods. RBMs are suitable both in hard and soft rock. The flexibility in different angles and diameters is a great advantage compared to drill and blast excavation method. RBM creates a shaft with smooth walls which usually does not require lining. The hole is more stable than a drilled and blasted method and has better air flow, making it ideal for ventilation shafts. Raise boring is convenient method in competent rock; however several problems are faced in geological formations where geological discontinuities are dominant. Moreover, assembly and disassembly time may be long in some cases. The performance and operational parameters of the excavating machine should be predicted prior to starting the excavation operations in order to fulfill the economic requirements of the project. In the light of this fact, the main objective of this investigation is to summarize a case study on raise boring machine performance and suggest a new model based on laboratory test results. First, general description of the mine and project are provided. Then, the physical and mechanical characteristics of the samples taken from project area are discussed. In the third section, performance and operational parameters of RBM are investigated to understand the machine behavior in different rock characteristics and also to collect a useful database for further investigation. In the fourth section, a new model for performance estimation of RBM are recommended."

Jan 1, 2016

By J. Navoyski, B. Macdonald, W. J. Helfrich, J. L. Bellanca, B. Demich

DISCLAIMER The findings and conclusions in this paper are those of the authors and do not necessarily represent the official position of the National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention. Mention of company names or products does not constitute endorsement by NIOSH. ABSTRACT Recent advances in computing, rendering, and display technologies have generated increased accessibility for virtual reality (VR). VR allows the creation of dynamic, high-fidelity environments to simulate dangerous situations, test conditions, and visualize concepts. Consequently, numerous products have been developed, but many of these are limited in scope. Therefore, National Institute for Occupational Safety and Health researchers developed a VR framework, called VR Mine, to rapidly create an underground mine for human data collection, simulation, visualization, and training. This paper describes the features of VR Mine using self-escape and proximity detection as case studies. Features include mine generation, simulated networks, proximity detection systems, and the integration and visualization of real-time ventilation models. INTRODUCTION There are many definitions of virtual reality (VR) that include various levels of immersion and features [1]. Some definitions refer to specific technologies [2], while others are limited to visualization [3]. For this paper, a more general definition of VR will be adopted. VR is defined as the collection of hardware and software that interactively engages users and stimulates their senses within a synthetic or virtual environment. From a hardware standpoint, this can include anything from a phone to a head-mounted display (HMD) to a large-scale theater as well as speakers, microphones, haptic sensors, and interaction devices. The software used to create virtual environments (VEs) generally includes a game engine, custom software components and libraries, and two-dimensional and three-dimensional graphical assets. Recent hardware and software advances have increased the fidelity and availability of VR. New and improved technologies including HMDs and high-resolution monitors and projectors can display sharper, more detailed visualizations. For example, in the past five years between the release of the Oculus Rift DK1 (2013) and the HTC Vive Pro (2018), there was a three-fold increase in resolution along with a 50% increase in the refresh rate. Furthermore, despite early claims that low-cost VR technology was readily available [4], computational power has not been sufficient to handle the large amount of data generated by these systems [5]. In the past five years, however, rendering speeds have more than doubled and memory has more than tripled [6], allowing these visualizations to be incorporated into higher-complexity and -fidelity VEs that more closely mirror the real world. Similarly, software capabilities have also significantly improved through game engine advancements and feature development. In the past several years, game engines have added and improved features such as physics, lighting, platform support (e.g. Android), and asset development integration. Some of the current leading commercial game engines are Amazon Lumberyard, CryEngine, Unreal, and Unity, but this can quickly change as is evident in the literature [7, 8].

Jan 1, 2019

By G. J. Karabin

The Boundary Element Method of Numerical Modeling has become an increasingly popular rock mechanics -mine design tool. It has been used by the Roof Control Division, Pittsburgh Safety and Health Technology Center, MSHA, to aid in the resolution of complex ground control problems since 1985. This paper will present an overview of an evolving simulation process and details of methods utilized to generate necessary coal, rock and gob input properties. Also included is a description of a Deterioration Index System that is used to link model output to observed mine conditions and two case studies to illustrate that process.

Jan 1, 1995

By R. Pinksen

The IOC Mining and Operations Departments expressed an interest in reducing the amount of oversize material (>1.0 m x 1.0 m x 1.0 m; 39 inches x 39 inches x 39 inches) being produced and its subsequent downstream effects including in-pit sorting and reduction, damage to mobile equipment, and significant delays in the loading pockets and the primary crushers. To achieve this goal an oversize reduction project was undertaken by the mine and to date has significantly improved upon baseline measures. One key approach used to reduce the amount of oversize was the implementation of thicker emulsion. The introduction of a thicker emulsion provided more resistance to the forces created by dynamic water and reduces the infiltration of the emulsion into the cracks and fissures of the rockmass. Reduced amounts of oversize and more consistent fragmentation throughout the muckpiles has been a result. Additionally, a significant reduction in nitrates leached into the mine water discharge has been realized. To determine the effectiveness of the oversize reduction project, IOC used a of first-of-kind technology to assess fragmentation presented to the shovel at the digging face. A Digital Vision System (DVS) was installed on one of the shovels to capture images that were stamped with GPS locations. A large population of digital images were analysed to produce a robust fragmentation distribution baseline that was used as one of the mine key performance indicators (KPI). Changes to blasting practice were subsequently measured against the baseline KPI to assess effectiveness.

Jan 1, 2011

By Derek J. Barratt

The existence of a critical size buildup in an autogenous or SAG mill can be predicted from proper examination of drill core and ore samples. Methods of dealing with such critical size in a primary mill are reviewed in the context of ore properties, whether or not pilot plant-scale testwork has been conducted, and also with respect to the design of new plants or the retrofitting of existing operations. The implications of not planning for pebble crushing in situations where it is appropriate are discussed.

Jan 1, 1992

By Raymond Sandiford, Kenneth Xu, Taehyun Moon

Tunnel approach structures situated in slow moving earth flows are subjected to significant earth pressures. The authors have developed a system, utilizing collapsible concrete columns, that limits such loading. The system uses an array of collapsible concrete columns in front of the structure to absorb downslope movement and limit-imposed loads. This concept has been modelled using 3D FEM analyses and a rudimental lab test. For implementation, the collapsible columns would be prefabricated in strengths to mimic the soil strength profile. This concept has merit, and analytical results demonstrate that collapsible columns are a viable means to limit loading.

Jun 23, 2024

By L. Xu

Since the establishment of the standard dust concentration of 2 mg/m3, a strong effort has been made by mining engineers and researchers to provide better dust control equipment and procedures for underground coal mines. Particular areas of success have been control of dust generation by better coal-cutting strategy, better design of water sprays for dust suppression and air movement, use of scrubbers, and improved design of face ventilation systems. A drastic improvement occurred over time such that the average dust concentrations for continuous miner operators dropped from 6.5 mg/m3 in 1968 to 1.3 mg/m3 in 1980 and for auger, cutter, longwall, and roof bolter occupations from 2.7 mg/m3 in 1973 to 1.6 mg/m3 in 1980 (Niewiadomsky, 1983).

Jan 1, 1990

By O. M. Arafat, J. A. Finch

"The Functional Performance Equation calculated from a plant grinding survey defines two distinct ball mill circuit efficiencies and how they relate to total production rate through the target grind size. The survey data are also used to calculate a complete ball mill size distribution model, represented by the energy specific grinding rates, not just through the target grind size, but through all the size classes. Cyclone separation performance is represented by individual size recoveries to underflow. When these two unit operation performances are entered into the circuit modelling program (Streamline™), along with the circuit feed rate and size distribution, all the circuit survey size distributions and mass flows are perfectly regenerated by the program. The many issues associated with the historical Epstein (breakage-selection) models are eliminated. Once the circuit program is populated, pump and cyclone performance changes can be evaluated using a step-by-step procedure in order to maximize Classification System Efficiency. Mill water use and media sizing opportunities are also diagnosed in order to maximize Mill Grinding Efficiency at the size of interest. An example is provided. This circuit analysis and modelling system, and related training, is provided through a web-based application. INTRODUCTION Since its development (McIvor, 1988), the Functional Performance Equation for ball milling has facilitated new understanding of industrial circuit cause and effect relationships, leading to significant strides in operational performance. Success stories of this refreshing approach to plant circuit performance improvement are now too numerous to list. Finch and McIvor (circa 1986) also discovered that the Functional Performance “Mill Grinding Rate” at the size of interest was the same cumulative grinding rate that is calculated from mill feed and discharge size distributions using a first-order rate equation. By calculating these cumulative grinding rates for all screen sizes, a complete ball mill model is generated (as used by Finch and Ramirez, 1981). Others in industry, Hinde and Kalala (2009), for example, have noted the same. Lacking the complexity needed to maintain their interest, most researchers have ignored this model, broadly opting instead for Epstein’s (1948) characterization of grinding as a chemical reaction, combining “selection rate” and “breakage size distribution” functions. The much simpler ball mill model presented here has previously been incorporated into a proprietary circuit modeling program (McIvor, 2005) and used for plant improvement work (for example, see McIvor and Finch, 2007, and McIvor, 2014). Now, by combining this extremely business-friendly ball mill model with optimization criteria from Functional Performance Analysis, a circuit modeling system (including the needed supplementary steps to assure successful plant implementation of circuit design changes) is at the disposal of every plant metallurgist, grinding equipment/material provider, and circuit designer."

Jan 1, 2017

By H. Colijn

Vibratory or oscillatory conveyors can be found in all types of industry, handling virtually any granular bulk material, often at elevated temperatures. These conveyors can be combined with other process functions, such as screening, cooling, drying and dewatering, while conveying. Although construction and installation is relatively simple, the engineering and design analysis of the vibratory mechanics is fairly complex. This paper will discuss the basic types of vibratory conveyors and the analysis of the material movement along the carrying trough.

Jan 1, 1985

By H. Copur

Roadheaders have become widely used in underground mining and tunneling operations because they offer the flexibility to excavate soft- to medium-strength rock formations. A critical issue in successful roadheader application is the ability to develop accurate and reliable estimates of machine production capacity and the associated bit costs. Increased pressure to improve productivity and lower costs in the mining and civil construction industries has been the driving force behind the more wide- spread use of mechanical excavation systems. This has caused both industries to move away from the conventional drill and blast methods. Additional benefits of mechanical mining include improved safety, reduced ground support requirements and fewer personnel. These advantages, coupled with recent enhancements in machine performance and reliability, have resulted in mechanical miners taking a larger share of the rock excavation market. Roadheaders are the most widely used underground partial-face excavation machines for soft- to medium- strength rocks, particularly for sedimentary rocks. They are used for development and production in soft rock mining (main haulage drifts, roadways and crosscuts), particularly in coal, industrial minerals and evaporitic rocks. In civil construction, roadheaders are used to excavate railways, roadways, and sewer and diversion tunnels in soft ground conditions. They are also used to enlarge and rehabilitate underground structures. Their ability to excavate almost any profile opening also makes them attractive to those mining and civil construction projects where various opening sizes and profiles are needed. In addition to their high mobility and versatility roadheaders are generally low capital cost systems com- pared with most other mechanical excavators. Because of higher cutting-power density due to a smaller cutting drum, roadheaders can excavate rocks harder and more abrasive than continuous miners and borers.

Jan 1, 1998

By J. R. Sims

Gold assays from production blastholes in the Mercur Hill Pit were used to delineate known ore zones and to determine how well previous exploration drilling defined these zones. The most important factors causing inadequate ore zone definition were: 1) inappropriate location of drill holes relative to the ore zones, 2) presence of stopes from previous mining, 3) sampling and assaying errors, and 4) smoothing of the ore zone boundaries during ore reserve estimation. Infill drilling strategies were evaluated to determine the efficiency with which a given drill pattern defined the known ore zones. A drilling strategy was developed which improved ore zone delineation when compared to techniques which maintained uniform drill spacing.

Jan 1, 1992

By J. P. Allen

Cobalt, nickel, and manganese can be recovered quickly, cleanly, and selectively from cobalt-rich manganese crust by leaching in dilute acid solutions in the presence of hydrogen peroxide. Common selective precipitation methods can then be used to recover these metals from the leach liquor. The leaching reaction produces only oxygen as a byproduct, and the waste residue from leaching was tested and found to be non-hazardous under existing EPA specifications. The leaching process is effective in either fresh water or seawater. This research is a part of the Bureau of Mines program to identify the mineral resources of the Exclusive Economic Zone and devise methods for recovering their valuable components.

Jan 1, 1990

By Jodi Banta

Thanks to strong industry support and longstanding partnerships, the University of Arizona has provided extensive pre-college mining education and outreach for more than a decade. These efforts to promote mining-related degree programs and the wide variety of indemand career opportunities reach thousands of middle and high school students and hundreds of teachers every year. The School of Mining Engineering & Mineral Resources is constantly looking at ways to help students overcome barriers into degree programs. But competition among degree programs for talent is fierce, and outreach has not made a big enough difference in the number of students pursuing mining engineering degrees. With workforce shortages threatening to undermine the industry, more is needed. The Bureau of Labor Statistics estimates 500 new mining engineering jobs each year, and according to a study by Deloitte (2023) nearly 50 percent of skilled engineers will reach retirement age in the next decade. At the same time, the 14 accredited mining or mineral engineering degree programs in the United States are producing fewer than 200 graduates annually (Society of Mining Professors and Society for Mining, Metallurgy & Exploration, 2021). To better understand mining’s competitive position, the School of Mining Engineering & Mineral Resources conducted a comprehensive study to determine (1) how prospective college students, parents and educators perceive the industry, related careers and the mining engineering degree, (2) factors affecting students’ choices of degrees and career plans and (3) the roles parents and educators play and how they influence students. This article is the first of two installments to discuss the results. This installment focuses on what students, parents and educators think about mining and where they get those impressions, as well as the role parents and educators play in influencing students’ choices of careers and degrees. The second installment, scheduled for publication in a later issue of Mining Engineering, looks at what students are seeking in their degrees and careers, and how mining compares with other degrees and industries.

Sep 1, 2025

By J. B. Offei, K. Awuah-Offei

Mining companies registered with the SEC were required to comply with Regulation S-K 1300 for their annual report covering the first fiscal year ending on or after January 1, 2021. Consequently, most mining registrants filed their first S-K 1300 compliant disclosures in 2022. The US Securities & Exchange Commission (SEC), as part of its disclosure review program, has been issuing comment letters in response to these filings. This paper presents an overview of the trends in these comment letters. The authors reviewed comment letters retrieved from the SEC’s EDGAR database based on Standard Industrial Classification (SIC) Codes that cover mining, the content of the comment letter (whether it references S-K 1300 or not), the names of SEC staff listed in the comment letters, and other criteria. The analysis shows the SEC staff's reviews have been comprehensive covering the breadth of S-K 1300 and eliciting compliance with the rule. The staff through their comments are eliciting all the disclosures required by S-K 1300 and are not allowing registrants to substitute disclosures based on other standards for S-K 1300 disclosures. It is important, however, not to over generalize as the comments are based on the particular context.

Feb 1, 2023