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By Terrence R. Lejcher

Strip mining has played a key role in the production of coal used to produce energy in this country. About 56 percent of the 1.3 x 106 hectares (3.2 x 106 acres) that had been disturbed by surface mining as of 1965 can be attributed to stripping (Udall, 1967). The runoff from these stripped areas is usually heavily polluted with high concentrations of total dissolved solids, iron, aluminum, manganese, sulfates, and has low pH values with high acidity. Another problem of a most serious nature in our large cities is the volume of treated solids to be disposed of after sewage treatment. Chicago is presently producing about 664 metric tons/day of dry weight solids (Horn and Earles, 1968). Disposal methods most commonly used include lagooning, incineration, and landfilling. The high cost of land in an urban community is prohibitive of lagoon storage. Incineration and landfill disposal create air and water pollution problems. Many countries including Australia, England and Israel have long realized the value of sewage solids if they are recycled back to the land. In the United States, the value of such solids in reclaiming strip mined land has been recognized by relatively few people. This paper is concerned with the use of anaerobically digested sludge to reclaim strip mined land.

Jan 1, 1972

By Marc. A. Meyers

The analysis of the phenomena involved in the determination of the compressive strength of iron-ore agglomerates leads to the identification of the important parameters. It is shown mathematically that the pellet rupture strength is proportional to the cross-sectional area. Fracture is initiated at the center of the pellets by the tensile stresses developed by the compressive loads normally to the compression axis. The variation in strength between individual pellets of identical composition and subjected to identical treatments is due to internal voids of varying sizes, that act as stress-concentration sites. Two novel testing procedures are proposed. The first consists of testing the pellets between two plates having three steel spheres each. This configuration simulates much better the environment actually encountered by the pellets. The second procedure consists of a thick-walled cylinder in which a piston penetrates; a large group of pellets is tested simultaneously, as the stress versus strain plot is being recorded. This latter test presents significant advantages over the conventional testing procedure; the main one is that one single test is sufficient to characterize the mechanical response of the pellets.

Jan 1, 1981

By Ashish Ranjan Kumar, Barbara Arnold, Luis Sanchez Gonzalez

The health and safety of miners is critical in the industry. Prolonged exposure to dust-laden air results in irreversible ailments like pneumoconiosis that have a severe impact on their lives. Operations use various personal protective devices (PPEs) to alleviate their exposure to respirable dust. Powered Air Purifying Respirator (PAPR) is one such device that uses high- efficiency filters and positive pressure masks to shield miners from airborne contaminants. Used in the medical and other industries, these respirators efficiently protected healthcare workers during the COVID-19 pandemic. Recently, the mining industry has shown a growing interest in adopting this PPE to ensure safe working conditions for the miners. We present an introduction to the PAPRs and discuss their dust capture efficacy in this manuscript.

Feb 1, 2025

By D. Nutakor

This paper presents the results of a study conducted on a slope failure that occurred in the Q7 mining cut at Rio Tinto's Bingham Canyon Mine. The slope failure occurred in a weak rock mass with an estimated rock mass rating of 25%. The failure mechanism was of the circular type, involving ten 15-m (50-ft) benches and covered a total width of 152 m (500 ft). The analysis used Adam Technology's photogrammetric method with a two-dimensional rock fall simulation program (RocFall software) to design a 3-m- (1 0-ft-) high berm located 7 m (24 ft) from the toe of the failed mass. Back and predictive analyses were performed on a cross-section through the slide using Slope/W software, resulting in flattening the interramp angle (IRA) from 44° to 38°. This design modification produced a factor of safety (FOS) of 1.14. Sensitivity analysis involving FOS vs. pore water pressure showed that FOS is sensitive to water saturation. A dewatering system using a series of horizontal holes drilled below the slide and dewatering holes drilled from a drainage gallery has since been established to improve the stability of the slope. Throughout the one-year period since this investigation, no significant slope movement has been detected by the slope stability radar, and mining is in progress below the failure.

Jan 1, 2012

By L. K. Eigenbrod

Throughout the mining industry, pneumoconiosis is one of the most severe occupational health problems being faced. The goal of completely eliminating pneumoconiosis as an occupational health hazard was underscored by the Federal Government with its enactment of Public Law 91-173 (Federal Coal Mine Health and Safety Act of 1969). Under this law, permissible dust level standards will be placed at 2 mg/m3 in mine atmospheres by December 30, 1972. The mining industry is thus faced with the tremendous technical challenge of achieving this level. Two basic questions can be raised with regard to this legislation. First, does a maximum dust concentration of 2 mg/m3 prevent the occurrence of pneumoconiosis? Secondly, can this dust standard be achieved using presently available methods and equipment? A precise answer to the first question has not yet been developed by the medical profession. Studies are continuing on the origin, prevention, and therapy of pneumoconiosis, and permissible dust levels could become even lower as medical evidence accumulates. The mining industry has addressed itself to the problems of dust con-tro1 for many years as related to personnel health, explosive mixtures, visibility, and machinery damage. Dust control methods being employed involve

Jan 1, 1971

By G. P. Larson

We define a specialized mineral market as follows: Specialized markets occur where a low volume of a given mineral is used to convey a large benefit to a specific product. Sales of these value added minerals to small markets generally require a different marketing approach than bulk or commodity markets for traditional minerals. Specialized markets are differentiated by several characteristics as listed in Table 1. [Table 1-Characteristics of Specialized Markets 1. Long-term sample evaluation 2. Small volume markets 3. Highly controlled properties 4. Customized specifications 5. Technical selling effort] Many of the specialized markets require long term evaluations before sales can be made. This can vary greatly depending on the type of industry and ultimate end-use of the final product. In some cases, complete evaluations may take from several weeks to years. Length of sample evaluation has no relationship to size of market. That is, the total market may be quite small or fairly large (e.g. from a few hundred pounds to a few million pounds). Uniformity of value added minerals from lot to lot is an extremely important characteristic for these markets. Variations that are of no consequence to one industry (or application) cannot be tolerated in another. This has led to customized specifications and test procedures for specific markets and applications. Because of the greater uniformity and customized specifications, the need for greater technical selling effort is required. This is particularly true in the initial developmental phases and contacts as well as in maintaining the account after the initial order. A small entrepreneurial organization can be used to advantage to achieve goals of sales and profit to these types of markets. The large commodity or bulk producer's sales and marketing organizations are not ordinarily equipped to give the necessary service or technical assistance to the specialized markets. The organization usually required for this type of marketing is given in Table 2. [Table 2- Specialized Marketing Organization Requirements 1. Flexible approach to technical and marketing problems 2. Versatile background in a broad range of industries 3. Laboratory backup when necessary 4. Marketing expertise 5. Technically competent management] In developing specialized markets, a flexible approach to both technical and marketing problems is necessary in understanding the needs and requirements of the industry and the applications involved. This flexibility is also helpful in adapting existing products to new market areas. Having knowledge of a range of industries as broad as possible can be very helpful. It often happens that a product developed in one area or industry can lead to its application in a different area with excellent results. Laboratory assistance for a wide range of tests and test procedures is an important asset in any development program for specialized markets. Laboratories can also assist in competitive evaluations. Marketing expertise and a management with some degree of technical understanding are necessary in to assign proper cost/ benefit ratios to a proposed new product or application of existing products. This is important since the total market volume can be small and the time required for initial contact to first sale can often be lengthy. Also, management's technical and marketing expertise is required in evaluating all possible options that can be considered viable when an application is presented. Once an organization of this type is in place, it is then possible to determine the needs of the marketplace, including when various minerals might have to be customized to fill those needs. There are generally two methods of marketing, as noted in Table 3. [Table 3- Method of Marketing 1. Product Driven -Develop a product with certain desirable properties and try to find a market to utilize those properties. 2. Market Driven -Know market well enough that when a need arises, it is possible to identify a product that will satisfy the need.] These approaches are not mutually exclusive and can be used at the same time. Marketing a value added mineral generally requires the "market driven" approach. Hence, the importance of a knowledgeable management as outlined above. To determine where needs and opportunities exist, several approaches can be used. Table4 lists some of the methods employed.

Jan 1, 1993

By Alexander E. McHugh

A study of some variables affecting the recovery of molybdenum from oxidized molybdenum minerals was made. The effects of variations in contact time, temperature, pulp density, particle size, and solvent concentration on the recovery of molybdenum using acid and alkaline solvents were investigated. Chemical analyses, screen analyses and microscopic examinations were made and the presence of important elements determined. A hydrometallurgical method was developed to recover the molybdenum from the oxidized molybdenum ore by simultaneous dissolution of the molybdenum with sulfuric acid, adsorption on activated charcoal and flotation of the charcoal. The molybdenum was extracted from the activated charcoal with sodium hydroxide, precipitated with calcium hydroxide as calcium molybdate and this regenerated sodium hydroxide for additional stripping. A solvent extraction method, using mines, was also studied to recover molybdenum from both alkaline and acid molybdenum solutions. Satisfactory results were obtained.

Jan 1, 1967

By Donald E. Zipperian

The studies described in this paper have established that flotation conducted in a column cell provided with gas generation by aspiration into surface tension lowered water, may considerably increase the efficiency and particle size range of a flotation process. Operation of a DEISTER FLOTAIRE ® Cell at several Southwest United States flotation plants under continuous rougher, scavenger and cleaner conditions has demonstrated the main positive features to be: (a) higher capacity per unit volume than conventional flotation equipment, (b) improvement of flotation of plus 0.210 m particles, (c) improved flotation of particles minus 0.037 m.

Jan 1, 1984

By Alen Shibu Joseph, Arvind Rajnarayan Singh, Mudila Dhanunjaya Rao, Kamalesh K. Singh

In this article, the cementation of major impurities from zinc sulphate leach solution by the addition of zinc dust was studied by considering different parameters including time, mesh size, and percentage of excess zinc dust. The output obtained from various experiments was utilized for the design of experiments. A multi-level categorical factorial design with a quadratic model was employed during this study. Results were predicted to minimize the concentration of impurity metals in the solution by altering the parameters. Furthermore, these predicted results were validated by performing another experiment. Successfully, it showed that the predicted and experimental data values were close to each other. The predicted optimized values were 40 min, 100% excess zinc dust, and 300 mesh size for copper; 42 min, 100% excess zinc dust, and 300 mesh size for cobalt; 37 min, 100% excess zinc dust, and 300 mesh size for cadmium; and 34 min, 100% excess zinc dust, and 300 mesh size zinc dust for nickel. At these optimized values, the experimental results showed 99.99%, 55.7%, 99.6%, and 76.6% cementation efficiencies for copper, cobalt, cadmium, and nickel respectively. The statistical design of experiments for the effective cementation of impurities corroborates the economic feasibility of optimizing parameters for the proposed process.

Jul 18, 2022

By George D. Brunton

The past and present argillaceous rock studies for the U.S. National Waste Terminal Storage Program consist of: (1) evaluation of the geological characteristics of several wide- spread argillaceous formations in the United States; (2) laboratory studies of the physical and chemical properties of selected argillaceous rock samples; and (3) two full-scale in situ surface heater experiments that simulate the emplacement of heat-generating radioactive waste in argillaceous rock.

Jan 1, 1981

By M. J. Gula, S. S. Xue, E. P. Horwitz

A study was conducted to remove iron from sulfate solu¬tions using Eichrom'sDipex®extractant, PP'-di(2-ethylhexyl) methanediphosphonic acid (H2DEH[MDP]). It was found that this extractant can effectively and selectively extract ferric ion from highly acidic solutions. Ninety-nine percent of the iron was extracted from a simulated feed solution in a single stage. The separation factor, Fe/Zn, was 106. More than 90% of the iron in a loaded organic can be recovered in an aqueous solution by reductive stripping. This paper presents the experimental results. A new process for iron removal using Dipex extractant is described and discussed.

Jan 1, 2000

By E. A. Gyawu, L. L. Eng, M. Fikru, K. Awuah-Offei

Investors and other stakeholders are increasingly concerned about the quality and quantity of sustainability disclosures as well as the extent to which such disclosures correlate with sustainability practices of mining firms. This is because disclosure policies vary widely across firms in terms of extensiveness, materiality, and disclosed topic. In this paper, we conduct a preliminary examination of the relationship between sustainability performance and disclosure. We use sustainability performance indicators such as water and energy use and the Sustainability Accounting Standards Board’s (SASB’s) standards to evaluate disclosures. Our preliminary results show that some measures of sustainability performance (energy use) are negatively correlated to the amount and quality of disclosures while others (water use) are not. Thus, investors should not judge sustainability performance based solely on the amount and quality of sustainability disclosures. In addition, our results suggest that firm size and ownership as well as institutional membership could impact the strength of correlations between disclosure policy and sustainability performance

Mar 2, 2022

By George Schmitt, Ted Dowey, Grant Millener, Sean McAndrew, Eric Jordan

The Rondout-West Branch Bypass Tunnel is being built to bypass a substantial leak in New York City’s primary water supply tunnel. The 13,500 foot long tunnel travels 600 feet under the Hudson River through the same troubled geology and high pressure water inflows that the original tunnel did in the 1940s. A Robbins TBM traversed this geology and built gasketed segments. Nine thousand two hundred feet of 16 foot diameter interliner was installed and backfilled within the segments. Finally, reinforced cast in place lining was placed. This paper addresses the challenges and the multi-tasking approach the contractor utilized.

Jun 13, 2021

By William Gleason

The mining industry is a unique space. It is one in which geologists and chemists can intersect with computer and data science professionals daily. The industry requires expertise in not just mining and metallurgical engineering, but also electrical, mechanical, environmental and more. It requires expertise in worker health and safety, behavioral science, finance and economics, as well as human resources management. The locations of mining operations are often in remote corners, and for underground activities, they are unlike anything else in the world. The industry presents those who join it a wealth of opportunities, but often struggles to overcome incorrect perceptions of safety, labor and environmental standards, making it difficult to recruit and retain employees at a time of increased demand for mined materials.

Dec 1, 2025

By Stig Premfors

Lamco Joint Venture is operating a Dravo Pelletizing machine to produce pellets from the natural slimes of an earthy hematite ore. The grate area of the machine 3.3 x 106 m equal to 350 m2 (3800 sq. ft.) and the installed fan capacity is 8200 HP. The limiting factor for production is normally fan capacity. This means that the processing fans can not pull the additional air (i.e the additional calories or BTUs) through the bed which would be required for increased production. A way to increase production without major modifications is to supply the additional calories needed for increase production by adding coal to the pellet feed. After successful laboratory tests following method of coal addition has been chosen and the following results have been obtained. 1. The ground coal is added to the slurry prior to the filters and the rotary dryer. 2. By adding 0.6% coal, an increase of about 15% in production rate has been obtained. 3. No significant changes of metallurgical properties have been observed (i.e. tumbler index, compressive strength, ferrous iron content, reducibility, Linder degradation and swelling). 4. No unexpected operation problems have been experienced. The pellet discharge temperature increases and is the limit for how much production can be increased by coal addition without making plant modifications.

Jan 1, 1971

By Jie Long, Zijie Liu, Pu Liu, Bo Li, Menghua Li, Qiang Wu

During coal mine operations, roadways may be located close to faults. When designing these roadways, it is important to determine the width of the rock mass between a roadway and a fault area to prevent water inrush. In this paper, the Xintian Coal Mine in the northern Guizhou Province of China is selected as a typical case. Through numerical simulation based on orthogonal tests, range analysis, and multiple linear regression (MLR) analysis, the process of water inrush from faults in excavation roadways is studied. The results show that the influencing factors of the safe width of a rock mass preventing water inrush (RMPWI) can be ranked according to the degree of influence from large to small as follows: the hydraulic pressure of the fault, the surrounding rock grade, the overburden depth of the roadway, the cross-section height, and the dip angle of the fault. Among them, the dip angle of the fault, the cross-section height, and the surrounding rock grade are negatively correlated with the safe width, while hydraulic pressure of fault and overburden depth of roadway are positively correlated with safety width. The predicted value for the safe width based on MLR is greater than the measured value of the width of the RMPWI when water inrush occurs, but less than the calculated value based on the empirical formula in the standard, which proves the accuracy and practicability of the prediction method. This research provides a certain basis and reference for the prevention and control of water inrushes in mines.

Jul 5, 2023

By Layton C. Binon

Exploration budgets are commonly determined by "rules of thumb" such as a percentage of earnings or other fiscal measure. An appropriate exploration budget is the amount needed to achieve the goals of the company. It can be determined by discounting the income expected from achieved goals. Budgets for individual projects are determined in a similar manner except that risk of failure is included in the computation.

Jan 1, 1981

By Gabriele Eccher, Michele Caponero, Paolo Cucino, Roberto D’Angelis

"This paper describes the optic fiber structural monitoring system implemented for Pavoncelli Bis tunnel. The paper highlights the optic fiber sensors customization capabilities, how they smoothly fit precast concrete lining processes and TBM operations, and how a lifelong service monitoring can be achieved. An overview of readings’ evolution during excavation concludes the paper.INTRODUCTIONPavoncelli Bis is a 10 km hydraulic tunnel designed to by-pass the existing Pavoncelli tunnel which experienced severe damages during the 1980 Irpino-Lucano earthquake, in south of Italy (Barla 2009). Pavoncelli Bis excavation work commenced in 1988-90, however, when excavation approached pk. 0+583 in 1992, water percolations became more and more consistent and resulted in work suspension. The tunnel was eventually sealed at pk. 0+383, leaving a flooded section between pk. 0.383 and pk. 0+583. Work resumed in 2012 where EPB-TBM excavation was adopted to cross the flooded section and to overcome complex hydro-geological conditions in various lito-types and, in particular, in the Varicolori Clay-shales area (Figure 1).Consequently, stress evolution monitoring is extremely important during construction and during the service life of tunnel lining in clay-shales and in faults areas. In particular, the paper focuses on the monitoring system proposed for the newly EPB-TBM excavated portion from pk 0+583 onwards where optic fiber sensing technology was chosen for its reading stability and reliability in presence of water and its ability to be connected in series and remotely interrogated at kilometers of distance. FBGS OPTICAL FIBER SENSOR TECHNOLOGYFiber Bragg Grating Sensors (FBGS) are gaining increasing attention in the field of experimental stress analysis. Basically, Fiber Optic Bragg Sensors are strain-measuring devices and therefore provide many of the advantages of the well-known metal foil strain gages (Kreuzer 2007).Bragg gratings are written into so called single-mode fibers. These fibers consist of a very small inner core of 4 to 9 µm diameter and an outer part (cladding) of pure glass (SiO2) of 125 µm diameter. The difference of refraction indexes between inner core and cladding causes the light to propagate only inside the small core."

Jan 1, 2016

By Basilio Giurgola, Jeremiah M. Jezerski, Filippo Azzara, Federico Bonaiuti, Russell H. Lutch

The Northeast Boundary Tunnel Project consists of a 23 ft diameter, 27,000 ft long, CSO tunnel, multiple underground connections, and significant surface works within an urban corridor. The NEBT alignment depths range from 60 to 140 ft and includes seven shafts ranging in depth from 77 to 155 ft with diameters varying from about 19.5 to 56 ft, some as in-line connections and others required adits for connection to the main tunnel. This paper focuses on the design and construction of two major underground connections which are the First Street Connector Tunnel and the Mount Olivet Road Diversion Sewer.

Jun 13, 2023

By Raúl Castro, René Gómez

In underground mining, rock fragment size is a key variable for productivity because it impacts equipment selection and mining structure design. This study characterizes granular material fragmentation during its flow to understand its characteristics and mechanisms. Tests were conducted using a laboratory setup to emulate various heights where material is drawn. The fragment-size distribution was measured before and after tests for clay, concrete fragments, and gravel. Results showed that fragmentation mainly occurs in minor sizes, with significant increases in fine material as travel distance increases.

Jan 10, 2022