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By Ralph L. Merklin

One of the most commonly employed set of calculations in mill design and research is the material balance, known in wet beneficiation plants, as an Ore and Water Balance. For mill designers, the balance is one of the principal requirements in determining the proper size of launders, pipelines, process equipment, etc. In process development, one of the major goals is the establishment of an optimum balance. The usual procedure for calculating a material balance involves a manual technique utilizing reference tables, pre -obtained data, and a slide rule or desk calculator. With these, the engineer must perform a series of calculations which are repetitious in nature and time consuming. Figure I is the flowsheet of the grinding and flotation circuits for a copper concentrator. The initial ore and water balance was calculated manually and required approximately 24 manhours. Later, a number of changes were made in the balance, each of which required an average of 8 manhours.

Jan 1, 1967

By S. K. Sharma

The Bureau of Mines' Tuscaloosa Research Center is conducting research to develop a basic understanding of solid-liquid separation in order to improve the dewatering of fine particle slurries. In the present investigation capillary suction time (CST) of kaolin slurries was determined. The average specific resistance of the cake was also determined by fitting the CST data to the theoretical equations used in this paper. The experimental data were analyzed by a powerful computer-based method, chemometrics, that uses statistical techniques to remove error and to find the number of physically significant factors contributing to the data. Results showed that two significant factors explain the CST data.

Jan 1, 1991

By Francesco Chiappalone, Miriam Piemontese, Lance Waddel, Paolo Perazzelli, Emidio Tamburri, Roberto Schuerch

The Three Rivers Protection & Overflow Reduction Tunnel is part of the Long-Term Control Plan of the City of Fort Wayne, Indiana (USA). The 4.9 m internal diameter tunnel, of length approximately 7.5 km, is excavated at a depth of approximately 40–60 m through carbonate rocks using a slurry TBM. Due to the high hydraulic conductivity of the rock mass and the high in-situ ground water pressure (up to 6.5 bar), the management of the water inflow during the TBM advance and standstills, represents the major challenge for the project. This paper outlines the geotechnical conditions and the hazards related to the large water inflows expected in the pre-excavation phase and discusses the experience gained during the construction of the first 8,224 feet (2,507 m), (first third of the total length of the tunnel).

Jun 13, 2021

By John Jonkman

Two major changes occured during the last 5 years in the applications of computers. First, the cost of computer equipment decreased drastically in an era of high inflation. Second, technological breakthroughs in hardware and software have been applied successfully so that the average person can successfully utilize the computer without having to be a computer expert himself. The mining industry has recognized that computing technology has evolved to a point where it can be applied successfully to assist in improving productivity. Since equipment downtime is one of the major reasons for lost production, the Kennecott Minerals Company has developed a comprehensive maintenance information system which now assists the maintenance department in minimizing equipment downtimes. This paper discusses the primary features and functions of this system, the state-of-the-art technology that has been applied, and the benefits that resulted from using this system. Programs to support mobile equipment maintenance scheduling, which currently are under development, are reviewed and a summary of future applications is given.

Jan 1, 1982

By L. Borsch

Geochemical laboratories are commonly criticized by geologists about poor analytical reproducibility and erratic anomaly patterns, especially when gold and trace metals from resistant minerals are reported. Geochemical analysis in mineral exploration is a compromise between high productivity on the one hand, imposed by large numbers of samples, and analytical precision and accuracy on the other. However, the physical properties of resistant minerals, such as cassiterite, gold, beryl, chromite, zircon and others, interfere with both of these requirements. Therefore, the degree of sample homogeneity that can reasonably be achieved in sampling and sample preparation must be considered. Subsequently, the understanding of its effects on analytical data quality and the consequences on data interpretation will provide a basis for understanding the problems common to exploration as an interdisciplinary science. Complaints about poor and inadequate analytical performance are not confined to exploration geochemistry. They are a common feature in mining and metallurgy and wherever sampling and analysis of "grains" are concerned - the "nugget" or "grain size effect." The "grain size" effect Poor analytical reproducibility is normal for gold and a well-defined group of other elements usually found in resistant placer minerals. Those who use and interpret geochemical data must realize and appreciate the chemical, the physicochemical, the physical and the mineralogical properties of the elements and their minerals. Especially for the "placer" minerals and their elements, such comprehensive interpretation is crucial. The most important factor to consider is the behavior of a mineral and its metal component(s) during weathering and their integration into the sampled medium, in exploration mostly sediments and soils. (Data interpretation for samples of water, gas, to a certain extent rock, follows different patterns.) A mineral may be chemically and physically stable or it may easily disintegrate physically or decompose chemically, or any combination of such processes, at varying degrees. The breakdown products, in turn, may or may not, interreact with the environment. If the nature of an element or a mineral predestines it for a heterogenous distribution in the sample medium, then nature, size and number of grains likely to occur should be considered in relation to the sample portion taken for analysis. This allows the estimation of their effect on analytical precision and accuracy. Elaborate and sophisticated statistical calculations exist on this subject. But these approaches do not cope with the complexity of the natural surface environment. The miner alogical, chemical and environmental behavior of elements and minerals can be estimated but not calculated. However, the mineral grain sizes and their influence on analytical precision can be precisely calculated if certain conditions, assumptions and idealizations are made. If the geochemical and mineralogical characteristics of minerals and elements are understood, such calculations demonstrate the grain (or nugget) effects that mineral properties and (geo)chemical behavior of minerals and elements cause on the precision and accuracy of geochemical analysis through their influence on sample homogeneity. Two other factors that influence the sample homogeneity and the nugget effect are the efficiency of sample preparation and the sample portion taken for analysis. In this way, certain element- or mineral-specific parameters can be established as a guide for the sampling program. The information, for example, may assist in determining sampling procedures in the field, especially the sample weight to be taken for "representative samples." Also, it may help assess whether analytical data, as provided by the laboratory, are acceptable. Finally, it may help determine the approach in data interpretation. However, all such simplified calculations are based on idealized, that is, unreal assumptions and conditions. As such, they represent one extreme end on the scale of probabilities. The reality is found somewhere away from this extreme, towards homogeneity. An example from a study of an eluvial gold prospect may be given for illustration: •Original sample weight: 20 kg (44 lbs) of rock gravel, crushed and ground to -0.18 mm (-80 mesh). •Au content: 20 grains of Au, average size of about 0.5 mm3 (0.03 cu in.) each = 7.5 mg each, making a total of about 150 mg Au in the sample = 7.5 ppm Au. Assumptions •Au occurs in the sample as free, discrete grains only. •Not more than one grain, if any, goes into each sample split (analyte) portion (20 grains of 7.5 mg Au each). •Analysis of original rock sample: 100 g sample for analysis, 20 kg/100 g = 200 samples 20 samples with 1 grain each: result, - 75 ppm Au. 180 samples with no grain: result, 0 ppm Au chances 1:9 •10 g sample for analysis:

Jan 1, 1996

By W. G. Fischer

Trona ore at the Westvaco mine of FMC Corporation has been obtained by room- and-pillar methods since the mine began operation. The flat-lying, 10-foot bed of trona, Na2CO3 NaHCO3 2H2O, is covered by 1500 feet of weak shale and sandstone. Extraction of pillars on the retreat quite often throws large amounts of weight onto development workings. Weak shales in the roof and floor fail rapidly and the mine ribs slough to such an extent that mining often becomes very difficult. When this occurs efficiency goes down, costs go up, and the risk to men and machinery increases greatly. Difficult mining conditions in the early 60's forced a re-evaluation of all presently known mining techniques in bedded deposits. Many room-and-pillar mining plans' were compared with the system in use at that time, but none of them offered a better solution to the roof control problem. Longwall techniques were seriously considered, but machinery was not available that would cut the hard trona seam and still maintain the productivity obtained from room-and-pillar sections. Roof cones troy in the longwall methods appeared to be more satisfactory than that found in room-and--pillar techniques. It was therefore felt that a new technique using the longwall principle and based on rock mechanics should be tried rather than previously known pillaring methods.

Jan 1, 1966

By J. Villeneuve

Steady-state simulation has proved to be a very useful aid in designing new plants and optimizing existing ones. The algorithms and data definitions of existing simulators often, however, require a great deal of expertise for implementing a simulation-based methodology. The constraints imposed by conventional simulators are explained and the advantages of a new algorithm, the Objective-Driven Simulation, are shown. These advantages are a) an improvement in the simulation results, which enables simplifications of the methodologies used, and b) the possibility of taking into account economic objectives for plant operation, thus extending the range of application of steady-state simulation.

Jan 1, 1992

By Ossi V. I. Hintikka

There are several limestone deposits around the Lohja area in southern Finland. Raw material for cement rock is mined from some of them. The formations are geologically complicated, and therefore selective mining is used whenever possible. One of these mines is the Tytyri underground limestone mine, which is divided into two parts; Törmä and Solhem. In addition to the selective mining system hand sorting or picking must be used at the Tytyri mine to improve the overall grade of the blended limestone. Some means were needed in order to improve the quality and to increase the feed rate by the elimination of hand sorting. Sorting machines were considered and eventually a Sortex 811MW was pilot plant tested at the Ojamo mine near Tytyri. This machine now continues to be used on production.

Jan 1, 1971

By R. L. Grayson

Productivity achievements in underground coal mining over the past ten years highlight the improvement of management practices as well as the adoption of new technology. Research findings and results from operational studies characterize the aspects of good management that translate into high productivity. In concert with these findings, the Mine Management Support System (MMSS) is being developed, under co-sponsorship of the U.S. Bureau of Mines and the West Virginia University Energy and Water Research Center, as a knowledge-based system to enhance more efficient management of underground coal mines. Concentrating on capturing the intricate knowledge needed to manage a mine effectively, MMSS will encompass information and rules on work scheduling, desired work practices, regulations impinging on operations and planning, responses to operating problems, and the labor-management work agreement.

Jan 1, 1990

By Shawn T. Sorrell

Phillips Coal Company (PCC) submitted the first surface mine permit application under the Office of Surface &lining approved regulatory program of the State of Louisiana. This application for the Oxbow Lignite Surface Mine which is located approximately 64 kilometers (40 miles) southeast of Shreveport, Louisiana was submitted in March 1981. The State of Louisiana Office of Conservation, Surface Mining Division, assigned this application number LSM-1, indicating it is the first one submitted in Louisiana history. The permit area for the Oxbow Mine encompasses 6,251 hectares (15,627 acres). Of this total permit area, 5,862 hectares (14,656 acres) were classified by soil type as prime farmland by the U.S. Soil Conservation Service (SCS). Prime farmland acreage in the permit area became a major central issue in our early planning stages and throughout the permitting process of the Oxbow Mine, due to the magnitude of acreage involved.

Jan 1, 1982

By M. J. Laurila

On-line analyzers have made possible the use of Fuzzy Logic Control (FLC) for local control applications in coal preparation plants. This includes FLC control of complete circuits such as heavy media vessels, cyclones and froth flotation. These circuits can be controlled in real time in a feedback control loop with an on-line analyzer. Control strategies can be readily developed using Statistical Process Control (SPC) techniques which are first applied off-line in manual mode through the use of control charts and then this process is brought on-line using FLC in conjunction with an on-line analyzer to fully automate the circuit. This paper outlines the types of control strategies employed and presents examples of automatic verses manual control.

Jan 1, 1997

By R. W. Sims

"He?s an SOB, but he's my SOB." Many of us have heard this line in reference to attorneys, and can appreciate the humor. However, the thought reflects a deeper attitude that lawyers should be used for attack purposes in the legal system or the regulatory process. Often, more permitting progress can be made with tact and flexibility than with inflexible, overly aggressive strategies. Usually, administrative hearings or other litigation work to the disadvantage of the applicant. Thus, I have concerns about approaching any permitting system with a hard-line attitude. On the other hand, the project team must always be prepared to defend permit applications and present a legally adequate case at public meetings, administrative hearings, or judicial proceedings. This paper discusses a number of strategies intended to increase the probabilities for successful permitting, whether opposition is informal or highly organized.

Jan 1, 1990

By R. M. Imhof, M. J. G. Battersby, J. V. Brown

There is a plethora of former industrial sites where coal mining operations have left large slurry impoundments. These contain raw washed fines, which have previously been too expensive to process to requisite grades for commercial use. New technology has been developed for fine material processing, namely the Imhoflot pneumatic flotation G-Cell. This froth flotation technique is a highly efficient means of concentrating coal and is particularly appropriate to the nature of materials encountered in tailings ponds. The high volumetric throughput resulting from the vastly reduced residence time in the cell allows for drastically reduced equipment sizes when compared to conventional flotation cells. This means the process, when combined with innovative pre treatment and filtration equipment can be developed as a mobile plant concept. This is seen as a minimum requirement when re-treating and rehabilitating fine coal ponds.

Jan 1, 2003

By H. Maleki

The U.S. Bureau of Mines pioneered the use of borehole deformation gauges and overcoring techniques to measure in situ stress. These measurements provide input to structural mine design and support selection for specific geologic conditions. This paper presents recent stress measurements in a western U.S. coal mine where the orientation of the stress field remained relatively unchanged over distances of several kilometers. The horizontal stress magnitude increased with depth of cover and in relation to major geologic structures. Local variations in roof stress profiles were used to develop generic models relating stress arching to strata stiffness and the inelastic behavior of mine roof.

Jan 1, 1994

By S. Yerel

Block cutter machines have been extensively used in natural stone industry, which is a sub-section of mining industry. In this study, the costs occurring in plate losses cut from Bilecik beige marble with a circular saw block cutter machine have been predicted using Statistical Process Control (SPC) techniques. One of SPC techniques is Shewhart control charts such as mean control chart. These charts have been efficiently at determining the plate losses. The costs occurring in plate losses have been calculated by using the result of Shewhart control chart. Finally, this study presents the necessity and usefulness of SPC techniques in assessment of natural stone industry.

Jan 1, 2010

By W. S. Hannan

History Leaching of sulfide ore was first attempted by the Phelps Dodge Corporation about 1900 at Bisbee, Arizona, when Dr. James Douglas conducted experiments in an attempt to apply the leaching techniques then in use at Rio Tinto, Spain. Although this initital attempt was unsuccessful, research work was continued which culminated in successful leaching operations at Tyrone, New Mexico, in 1917 and at Bisbee beginning in 1920. Leaching has continued intermittently since that date, with material from the Lavender Pit being leached today. The Lavender Pit Leach Dump Stripping for the Lavender Pit was started in 1951, with mining operations on stream in 1954 and continuing to the present. All material removed from the pit has been classified as waste, leach material, milling ore, or direct smelting ore, depending upon grade and degree of oxidation. Lavender Pit leach material has been stockpiled in a single dump, called No. 7 Dump. This dump covers an area of approximately 135 acres and average about 300 feet in height. The dump has been deposited over a period of 20 years by truck haulage and contains several layers, each of which has a permeable boulder layer at the bottom and a compacted layer at the top. Leaching of Lavender Pit material was started in 1956 and has proceeded simultaneously with dump construction. Former leach pond areas and haulage surfaces have been ripped with D-9 tractors before deposition of succeeding layers of ore.

Jan 1, 1972

By Carrie Smith

The Society for Mining, Metallurgy & Exploration’s annual conference and expo, MINEXCHANGE 2026, will take place Feb. 22–25, 2026, at the Salt Palace Convention Center in Salt Lake City, UT. The event will foster a hub for innovation, technical exchange and policy discussion for the global mining industry. Over four days, attendees will take part in short courses, technical sessions, field trips and networking events that highlight the advancement of the mining industry. The conference’s keynote session, titled “Regaining America’s Mineral Dominance,” will start at 8:30 a.m. on Feb. 23 in the Grand Ballroom E–J. The speaker will address the sweeping policy actions now shaping the nation’s mineral future, following a series of executive orders issued by the Trump administration designed to bolster domestic mineral production and energy security. These directives, including Immediate Measures to Increase Domestic Mineral Production (EO 14241) and Establishing the National Energy Dominance Council (EO 14213), have set in motion a coordinated effort across the Departments of Interior, Energy, Defense and Commerce to enhance the United States’ position as a global leader in critical minerals. The invited speakers include Utah Governor Spencer J. Cox and Nate Foster, managing director of Rio Tinto Kennecott, who will examine how policy and industry are converging to meet surging demand for minerals essential to modern technology. Governor Cox is expected to highlight Utah’s long-standing role in American mining, from the early development of Kennecott Copper to its current position as a producer of 40 of the nation’s 50 identified critical minerals. Foster, meanwhile, will offer insights into Rio Tinto’s extensive operations in Utah, including the Kennecott Copper Mine — one of only two operating copper smelters in the United States — and the company’s ongoing efforts to build more resilient, sustainable supply chains. Rio Tinto’s work in critical mineral production, from copper and tellurium in Utah to new operations in Arizona, has made it a fundamental figure in the U.S. mineral economy. Projects such as the Resolution Copper development and the revival of Gunnison Copper using Rio Tinto’s innovative Nuton technology illustrate how private-sector leadership is driving sustainability in domestic mining. These advancements come at a critical moment for the industry, as copper prices remain near historic highs. The keynote session will emphasize that meeting future mineral demand will require a concerted effort between government, industry and technology partners to secure responsible, domestic production. Immediately following the keynote, the Robert E. Murray Innovation Award Lecture will start at 10 a.m. as part of the same session. Lucy England, managing director at FLSmidth, will present on “Sustainable Copper Mining Flowsheets and the MissionZero Mine.” England, who has spent more than 25 years in mineral processing and innovation, will discuss how FLSmidth’s MissionZero initiative aims to develop the world’s most efficient

Feb 1, 2026

By P. Somasundaran, D. R. Nagaraj, Jing Wang

Polysaccharides have been widely used as depressants in mineral processing for decades. They constituent one of the most abundant family of biopolymers. However, only a small number of them have been used by industry so far because of a general lack of understanding of interactions between these polymers and minerals. In this work, adsorption tests, electrophoretic mobility measurements, microflotation and fluorescence spectroscopic tests were performed along with computer simulation to explore the mechanistic aspects of guar gum adsorption and conformation on talc as a function of relevant variables such as ionic strength, pH, solvent composition and polymer molecular weight. From microflotation tests, it was found that talc hydrophobicity decreased markedly due to the adsorption of guar gum even at very low concentrations and reached a plateau below moximum adsorption. Guar gum adsorption on talc was found to be not affected significantly by changes in solution conditions such as pH and ionic strength, ruling out electrostatic force as controlling factor for adsorption. Fluorescence spectroscopic studies showed no evidence of the formation of hydrophobic domains at talc-aqueous interface. Also urea, a hydrogen bond breaker, reduced the adsorption of guar on talc. All of the above results suggest that one of the main driving forces for guar adsorption on talc is hydrogen bonding in preference to electrostatic or hydrophobic force. This information should help toward designing reagents of optimum molecular architecture for efficient depression, dispersion or other such surface modification of particles.

Jan 1, 2005

By Robert W. Elayer

For the design of a coal mine and process plant, a comprehensive foundation of geologic information is essential. Historically, the development, collation, and use of this information for design have been costly and time consuming. With the application of a digital computer, however, the effort expended can be reduced and maximum effective use of the geologic information realized. The purpose of this paper is to demonstrate the feasibility and convenience of using a computer to Store and manipulate geologic data for use in mine and process plant design.

Jan 1, 1975

By T. G. Carnahan

The U.S. Department of the Interior, Bureau of Mines, performed a laboratory-scale investigation of technique for recovering silver from pregnant solutions generated in the hydrometallurgical treatment of complex base-metal sulfide concentrates with oxidizing chloride media. This provides a means for recovery and simplified reduction of accessory silver to metal from ions. The method consists of adding NaI or KI to the solution to precipitate AgI, which is then contacted with Na2S to produce Ag2S and to regenerate the iodide salt solution. Silver recoveries range from 99 pct with 20 pct excess iodide precipitant, to-92 pct when the theoretical stoichiometric amount of precipitant is employed. The Ag2S product can be reduced to silver metal by contact with aluminum chips in NaOH solution followed by purification with conventional fire refining techniques.

Jan 1, 1980