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By R. L. Grayson, Y. J. Wang

An application of material requirements planning (MRP) to coal mine inventory control is presented. MRP is an efficient material control system that integrates the production planning and inventory management functions. Net material requirements are determined from the production forecast utilizing bill of material files, the inventory status file, and the purchase order status file. Net requirements are computed for each period in a specified planning horizon, and purchase orders, offset by lead time, are initiated routinely to ensure timely receipt of materials. The MRP system is especially useful in production-inventory systems in which con¬sumption of materials is directly production dependent.

Jan 1, 1987

By Kenneth K. Landes

Lake stone is a term currently applied to chemical and metallurgical grade limestone or dolomite that is brought down Lakes Michigan and Huron by large cargo vessels, mostly self-unloaders. This stone comes from 5 quarries, all in Michigan and all steel company owned. The volume in 1973 was over 34 million tons. The primary reasons for the large volume are the quantity and quality of the stone available, and the low delivery costs to lower lakes markets. The source rocks are Silurian and Devonian limestones and dolomites of exceptional purity. The regional dip of these formations is 50 to 60 feet per mile southerly toward the lowest point in the Michigan structural basin, which is near the center of the Southern Peninsula. Two of the 5 quarries, both high calcium limestone sources, are on Lake Huron in the northeastern part of the Southern Peninsula. The other three are in the Northern Peninsula; one at the northern end of Lake Michigan, and two on northern Lake Huron. The western quarry is in limestone, the other two in dolomite.

Jan 1, 1975

By D. G. Purdy

Planning, as defined in Webster's New Collegiate Dictionary, is a detailed program of action designed to achieve an end. When developing a detailed plan to incorporate all the complex activities involved in a surface lignite mine, many elements must be carefully evaluated as to the individual and cumulative effects on the end result. The following elements are generally evaluated when planning a surface lignite mine: ? Reserve evaluation, including lignite quality characterization; ? Delineation of mining parameters, including lignite recovery factors, geotechnical factors, land control factors; ? Selection of mining blocks; ? Pit sequencing; ? Reclamation, including soil reconstruction design and land use planning; ? Overburden handling design; ? Selection of equipment; ? Sizing of equipment; ? Manpower requirements; and ? Other elements, including contract negotiations and execution, financing, investment return, operation economics, permitting and scheduling.

Jan 1, 1985

By Eugene A. Hickok

Seismic surveys utilizing the MD-1 have been performed by Geophysical Specialties Company since 1957 in many parts of the, U. S. and Canada and in several foreign countries. These surveys have proven the refraction seismic technique to be applicable to a wide variety of engineering problems. The best known applications of the instrument have been in the, construction industry, where it is used for the delineation of material and mineral deposits and for bedrock depth determinations. Fast on-the-site depth determinations give reliable subsurface' information even in boulder-strewn soils. A widely publicized use of the MD-1 is to make rippability studies in which the instrument is used to determine the seismic velocity of the materials to be excavated. By use of special tables which correlate rippability with seismic velocities, such as those prepared by the Caterpillar Tractor Company using the MD-1, the rippability of-a specific material may be determined.

Jan 1, 1962

By T. N. Andersen

The history of gold and silver analyses shows an interesting duality. On one hand, classical chemical and instrumental methods have evolved to meet changing needs, but on the other hand, the age-old and somewhat empirical fire assay has remained a popular tool. Inasmuch as gold and silver generally have been present in ores at low concentra¬tions, methods have been challenged by a need for sensitivity and selectivity coupled with reasonable assay time. A progressive increase in the importance of low grade materials as ore sources has led to the need for improved methods. Assays of these materials are required for process control and accounting in operating plants as well as for guiding research and development activities. The analytical response to these needs is evidenced by numerous reviews published through 1977-¬e.g., cf Kolthoff and Elving (1966), Beamish and Van Loon (1966, 1972, and 1977), Young (1971) , Mallett (1970), and Sen Gupta (1973). In this paper we present a brief sketch of the history and status of various gold and silver methods. A more detailed summary of atomic absorption spectroscopy (AAS) is Given, as this method has gained in popularity more than other assay methods. AAS methods currently in use are summarized and discussed briefly. This paper is not meant to be a detailed review, as are the above mentioned publications. Rather, we borrow from those works and more recent papers to report trends in gold and silver analyses (particularly in AAS). Also, we discuss some selected poten¬tial problems, and problems that have been experienced by this laboratory.

Jan 1, 1981

By David B. Gladwin

Regional characteristics in the coal resource base have resulted in application of different mining methods across Canada. Longwall methods predominate in eastern Canada, whereas open pit, hydraulic and room-and-pillar methods are utilized in the west. Both provincial and federal agencies have regulatory responsibilities and both also share in the development of R&D programs. This paper outlines the scale and scope of the various agencies involved with health and safety R&D in our expanding coal mining industry. Specific R&D activities in ventilation, dust control, explosion hazards, tunnel boring, strata control and truck braking, which form part of the national program, are outlined.

Jan 1, 1982

By Ralph B. Hall

Examination of cored material from the Southern Extension of the Florida Phosphate District has indicated a decidedly complex and diverse sequence of phosphatic sedimentary units. The perfunctory logging techniques formerly used in the Central District are inadequate to properly describe the intricate geology of these sediments. Adequate geologic training and familiarity with the potential ramifications of his judgement are a necessity for the logging geologist. A combination descriptive-graphic logging model is proposed that utilizes a standardized sediment nomenclature system and descriptive symbols for type materials commonly found in these sediments. Justification for adoption of this or a similar logging model is discussed.

Jan 1, 1983

By T. Qiu

"The purpose of this study is to investigate the effect of the dosage of sodium hypochlorite as activator on the flotations of depressed marmatite and depressed chalcopyrite, with a focus on activation-flotation kinetics. Four flotation kinetic models were applied to test data using 1stOpt statistical analysis software to estimate the relationships between the maximum flotation recovery rates for the depressed marmatite and depressed chalcopyrite, the flotation rate constants and the sodium hypochlorite dosages. Within the range investigated, the highest flotation performances of depressed marmatite and depressed chalcopyrite were obtained at 2.5 mL/L sodium hypochlorite with zinc recovery rate of 93.8 percent and 3 mL/L sodium hypochlorite with copper recovery rate of 94.6 percent, respectively, after four minutes of flotation. A second-order model with rectangular distribution of flotabilities gave the best fit to test data collected at various sodium hypochlorite dosages. For the highest flotation performances of depressed marmatite and depressed chalcopyrite, the respective equations of their flotation models were derived and presented.IntroductionCyanidation tailings are the solid residues generated by gold plants that use cyanide to extract gold (Lv, Ding and Qian, 2015; Zhang, Li and Yu, 2013). Because of increasing demand for gold, the Chinese gold industry has developed rapidly, with production amounting to 451.799 tons in 2014, an increase of 5.5 percent from 2013. Chinese gold production has been the highest in the world for eight consecutive years. As a result, more than 2.45 million tons of cyanidation tailings are estimated to be discharged into tailings ponds every year (Li et al., 2010; Lv, Ding and Qian et al., 2015; Wang et al., 2015; Zhang, Li and Yu, 2013; Zhang, Li and Yu, 2012), and approximately 300 million tons of cyanide tailings are stockpiled in China, with the potential to cause serious environmental pollution as well as death to wildlife (Adams and Lloyd, 2008; Donato et al., 2007; Hewitt, Breuer and Jeffery, 2012; Velasquez-Lopez et al., 2011; Stephen et al., 2009; Zagury, Oudjehani and Deschenes, 2004). Concerns over cyanidation tailings are not exclusively environmental but also economic, as tailings occupy considerable land area, and tailings storage facilities increase the production costs of gold enterprises (Donato et al., 2007). Tailings often contain other valuable metals such as zinc, lead and copper. For example, the cyanidation tailings of Gaoyao Hetai Gold Plant in Guangdong Province contain 2.5 percent copper (Cu), 0.31 percent lead (Pb), 0.23 percent zinc (Zn) and 15.36 percent iron (Fe) (Shi, 2008), and the tailings of Tianshui Gold Plant in Gansu Province contain 1.94 percent Cu, 5.96 percent Pb, 0.27 percent Zn and 24.62 percent Fe. Cyanidation tailings have therefore been increasingly viewed as a secondary resource rather than waste."

Jan 1, 2016

By Wolfgang Pietsch

DR iron') is a generic term for metallized product that results from the direct or solid state reduction of iron ore. In direct reduction, iron oxides are reduced to metallic iron in the solid state without an intermediate melting step. MIDREX ® Iron is the DR iron material produced in the MIDREX ® Direct Reduction Process. Except for some thermal and mechanical degradation, the external physical form of as-reduced DR iron is the same as the feed material. Chemically, oxygen associated with iron is removed leaving a very porous structure. Figure 1 is the scanning electron micrograph (SEM) of the internal surface of a MIDREX Iron pellet obtained from a Swedish oxide pellet during reduction at 760 °C. Figure 2 is the SEM of a polished and etched cross-section through the same pellet showing the amount of intraparticle porosity. As a result of this high porosity, apparent density of DR iron is relatively low, typically a¬round 2 g/cm3, and specific surface is extremely high, typically around 1.0 m2/g or more. Both density and specific surface depend on the raw materi¬al and the operating conditions of the direct reduction plant. Normally, more than 97% of the available iron is reduced into metallic iron with the rest mainly in the form of wustite (FeO). During direct reduction, the gangue in the iron remains essentially unchanged. Removal of oxygen and the corre¬sponding reduction in weight result in a slightly higher percentage gangue in the product than in the raw material.

Jan 1, 1976

By Alvin D. Cronberg

Silica flotation with amine salts has been a commercial process for years in certain non-sulfide mineral systems. Phosphate rock and feldspar deposits are notable examples. Generally, the quartz is clean and coarse. Primary amines and imidazolines are used, usually in a mole weight range 250-300, ad often fairly impure grades of collectors are satisfactory. As the production of magnetic iron concentrates grew in Michigan, Minnesota, Canada and in foreign locations, the iron mining companies began to explore amine flotation of silica to improve these concentrates. Many of the mining companies, as well as reagent suppliers, government laboratories and university research teams, had already studied amine collectors for silica, but the application to magnetic iron concentrates presented a real commercial opportunity to apply the art. Amine flotation of silica has been accomplished by simple addition of a flotation cell, and possibly a regrind mill, at the end of the magnetic concentration process. The flotation system gave the mill operator a flexible method to control final grade caused by ore variations in the feed. It increased iron content with lower silica, which resulted in lower freight costs per unit Fe and better pellets for blast furnace use.

Jan 1, 1968

By E. Watkins, S. J. SCHATZEL, K M. AJAYI, V. Gangrade, Z. Khademian

A stochastic discrete fracture network (DFN) model is developed based on mine site core log data to predict the horizontal and vertical permeabilities from the surface to the top of the caved zone at a longwall mining site in southwestern Pennsylvania. One hundred DFN realizations were generated to determine permeabilities for the isolated zone over an abutment pillar after mining the second panel. The results from this study show that the vertical and horizontal permeabilities from the DFN model agree closely with field measurements, which indicates that the resultant permeability obtained from the field measurements is representative of the predicted permeabilities. With this agreement, the aperture data for other zones of the mine could be obtained from the geomechanical model — specifically, for the fractured zone over the gob. Based on the successful validation of this model, this model could be further developed to predict the permeability of the fractured zone over the gob with fracture aperture obtained from the geomechanical analysis. This will complete the fracture characterization of the overburden, which could be used to predict potential shale gas flow to the mine in the event of a breach. This prediction could provide information on the associated risk of a casing breach and determination of methods to proactively prevent such an occurrence.

Feb 1, 2023

By Christopher R. Winter

Mining companies have sharpened their refocus on their tailings management strategies in recent years. Mining companies with tailings storage facilities that use the upstream construction method have been challenged to track the evolution of industry standards, assess risks, revise design, and communicate design revisions with regulators. While many aspects of best practices and industry standards have evolved in recent years as an attribute of continual improvement, the controlling standard in the design of many upstream dams is understanding the foundational strengths of hydraulically deposited tailings. Following best practices and industry standards, Hibbing Taconite Company managed by Cleveland-Cliffs, began the re-evaluation of foundation strengths underlying a system of upstream dams at the company’s iron ore mine tailings storage facility in northern Minnesota. Initial steps in the re-evaluation require reanalysis of design parameters and recommendations by the Engineer of Record to the Owner, which was followed by a series of meetings with the Technical Review Board to determine an initial path forward. Once a path forward and preliminary design parameters were determined, the Owner engaged with the State Dam Safety Engineer to discuss and seek approval of the plan. With continuous regulatory engagement throughout the process, further refinement of the design parameters for the hydraulically-placed tailings foundations underlying upstream dams began with field and lab geotechnical investigations. Following a review of risk assessments and trigger actions response plans, Hibbing Taconite revised its tailings storage facility operating plans and budget for the coming years. Based on the findings of the re-evaluation, reanalysis, and refinement of parameters, a paradigm shift was realized with the hydraulically placed tailings foundation strengths underlying the upstream system of dams. This paper explores the path that the Hibbing Taconite Company followed to understand the paradigm shift and construct downstream improvements. The plan involved tailings re-characterization, dam design revisions, operating plan reconciliation, budget revisions, wetland permitting, dam safety permit amendments, storm water prevention plans, borrow materials studies, new concrete decant structures and the pursuit to recognize and be consistent with industry standards.

Feb 1, 2024

By J. R. Schafler, J. L. Brinkman

"The US coal mining industry has suffered a recent decline in profits caused by a combination of decline in commodity demand and more restrictive government regulation, forcing coal mining companies to cease production in numerous mines. A 40% decrease in the total number of coal mines occurred from 1994 to 2000. The number of mines remained relatively constant until 2008 when a change of government sparked a series of new environmental regulations which have contributed to another 15% decrease from 2008 to 2016. In contrast, production has only decreased by 3%, increasing from 1994 to 2008, and then decreasing since 2008. However, this value is skewed by large increases in sub-bituminous coal production and decreases in other coal ranks. Several aspects assist in executive decisions on mine longevity and economic worth. Studies of open source mine data collected by mandated government surveys coupled with commodity history can be used to find relationships between mine closures and these elements, which include statistics on production tonnage, seam height, coal rank, etc. This paper looks at coal mining trends since 1994 by comparing mine, market, and regulation factors that may influence mine closure. INTRODUCTION The US coal mining industry is currently experiencing a decline in both demand and commodity price while facing implementation of more stringent air and water pollution regulations. Company profits have decreased significantly, forcing several major companies to declare bankruptcy. The industry was required to adapt to survive. Many of these companies have adjusted by abandoning mines; the last two decades have seen a drastic decrease in the number of mines. To discover the primary causes of this downturn, three major aspects must be studied: properties of abandoned mines, commodity history, and regulatory impact. TRENDS SINCE 1994 Each year, US coal mines are required to submit data on a wide variety of categories to the Mine Safety and Health Administration (MSHA) and the US Energy Information Administration (EIA). This data includes administrative records, production values, and information regarding the attributes of the mined material and the mine itself. Each year since 1996, EIA has released a report summarizing the data from two years prior. Additionally, MSHA maintains a database containing a collection of all the most current data. These resources are the primary sources for the following figures."

Jan 1, 2017

By Richard D. Zigmond

In this paper, a computer program that has been developed for determining the capital and operating costs for coal preparation plants is described along with its applications. The logic of the computer program is based upon the results of a survey of existing preparation plants, operators, plant contractors, equipment manufacturers, and consulting firms. This survey provided information on plant performance, order-of-magnitude costs, and costing procedures. Additionally, an extensive cost data file for the major capital equipment in coal preparation plants has been developed. Using the washability data and the computer program outputs, the cleaning costs per million Btu can be calculated. Details about the program and its applications can be found in a report by the authors (Zigmond et al., 1979).

Jan 1, 1981

By John J. Stetler

The Companhia Vale do Rio Doce in Brazil operates one of the most extensive systems in the world for the mining, transportation, processing, pelletizing and shipping of high grade hematite iron ore and pellets. Current shipping of unbeneficiated, sized, high grade ore from its ports at Tubarão and Vitória is now at the rate of 17,500,000 metric tons annually. An increase in this annual rate is now under study. Using the technology and facilities of Lurgi (1) and Arthur G. McKee company CVRD undertook a program to process and pelletize two types of fines - "Blue Dust" and ?Itabira Fines?. Blue Dust is a high grade fine ore which was bypassed while mining the direct shipping ores and which, also, exists as a very large ore body called the Conceição Mine. Itabira Fines is a lower grade of fine ore which is comprised of in-situ fines and, also fines which are generated in sizing the direct shipping ores for a rigid specification market.

Jan 1, 1970

By SUMANT KUMAR SAMAL, BHAGIRATHA MISHRA, MANOJA KUMAR MOHANTY, SUBASH CHANDRA MISHRA

Steelmaking consumes the majority of chromium and manganese ferroalloys for purposes such as to impart various properties to steel. The quality of ore governs the process kinetics as well as the process economy of the ferroalloy industry. The present study demonstrates the thermal transformation behavior of chromite and manganese ores with varying compositions. Simultaneous thermal analysis (differential thermal analysis/thermogravimetry, DTA/TG) was conducted on these ore samples, where the transformation of mineral phases was correlated with the thermogram characteristics and quantified. Phase, microstructure and compositional analysis results of individual ores corroborated with thermal analysis are in good agreement. Chromite samples are ferruginous with goethite and gibbsite contents, whereas manganese ores vary in composition and also exhibit multiple and/or overlapping transformations.

By F. G. Miller

It is generally accepted that sulfur exists in coal in three forms: (1) pyritic, (2) organic, and (3) sulfate sulfur. Sulfate sulfur usually makes up less than 1% of the total sulfur content. Pyritic and organic sulfur, make up almost all of the total sulfur and occur in varying amounts in different coals and can vary greatly in coal of the same seam Pyritic sulfurs of 20% to 80% of the total sulfur have been reported Other authors have shown that it is not possible to remove the organic sulfur without chemically altering the coal. Chapman and Jones (1) state: "Organic sulfur, unlike pyritic sulfur does not exist as discrete particles, but is intimately associated with the coal structure, and as such it is not possible to remove it or reduce its concentration by physical means." Any success in removing sulfur has come about by removing pyritic sulfur by physical means; therefore, removal of sulfur in the pyritic form is the subject of this investigation. The extent to which any impurities can be removed from a particular coal can be determined by a washability study. Outside of crushing coal, to finer sizes or chemically altering the coal, there are no known methods of changing this inherent washability characteristic. The efficiency of various methods used to remove impurities can be determined by comparison of results produced at a yield to the results as shown by a washability study. In recent years heavy media processes have proven their ability to wash plus 28 mesh coal and nearly produce results shown to be theoretically possible by the washability study. Therefore, it is the objective of this paper to show various methods of treating the finer fractions of the coal, in the hope of developing a process, which can effectively produce in the fine fractions the efficiency of heavy media devices in the coarse.

Jan 1, 1963

By G. Robert Moorehead, Peter T. Luckie, Harold L. Lovell, David J. Akers, James K. Kindig

Jigging is a process of particle stratification in which the particle re- arrangement results from an alternate expansion and compaction of a bed of particles by pulsating fluid flow. The vertical direction of fluid flow is reversed periodically. The rearrangement results in layers of particles that are arranged by increasing density from top to bottom of the bed. This response, developed from the many and continuously varying forces acting upon the particles, permits a solid-solid separation more related to particle density and less to particle size than any other "hydraulic-type" process. The stratification is usually carried out in a rectangular, open-top container called a jig, in which the mass of particles (termed a "bed") is supported on a perforated base through which the water flows in alternating directions. The coal particles, in addition to the vertically expanded and compacted bed motion, move continuously, horizontally across the supporting screen. Following the particle stratification, the particle bed is physically "cut" at a desired horizontal particle density plane to separate the desired clean coal product from the more dense refuse. The jig system includes means for continuously introducing the raw coal and for moving the water through the coal bed in a controllable manner, as well as for separating and removing the stratified particles from the system as two or more product streams. In coal preparation, this highly versatile unit operation is applied preferably to a wide size range of particles with top sizes up to 8 in. (20 cm) rather than to a closely sized fraction. In gravity ranges, the process has been applied to gold particles with a density of 19.3 and to coal particles having densities less than 1.30. Single jig washers have capacities from 5 (4.6) to greater than 700 tph (637 t/h) of feed coal. The separation results attainable by jigging have favored this unit operation as optimum for creating a clean coal product as required by steam coal specifications. Al- though the jig is used in preparing coals which are difficult to separate, its limitations to achieve both quality products and high recovery are being recognized in comparison with heavy media-based processes which make sharper separations from feeds having high "near-gravity" contents. The accu- racy of the densimetric stratification in the upper portions of the jig bed are less precise. It follows that coals with more than 10% near-gravity material

Jan 1, 1991

By E. D. Gálvez, L. A. Cisternas, A. López-Valdivieso, F. Lucay

"The floatability of molybdenite fines in saline solutions was investigated through microflotation studies using a modified Hallimond tube. In addition, the effect of pH and gypsum precipitation from calcium ions (Ca2+) and sulfate ions (SO4 2-) ions in saline water on the recovery of the molybdenite was analyzed. It was found that the floatability of molybdenite fines significantly increased with the ionic strength of the saline solutions and is independent of pH above 0.5 mol/L ionic strength. The high floatability of molybdenite in saline solutions is explained as being due to the low electrostatic repulsion between bubbles and the edges of molybdenite particles, which is exceeded by interactions due to van der Waals and hydrophobic forces. The precipitation of Ca2+ and SO4 2- ions as gypsum had a detrimental effect on the natural floatability of molybdenite because of gypsum crystal attachment on the faces of the molybdenite particles. This precipitation phenomenon may be initiated in copper–molybdenite flotation circuits that use recycled saline water, like seawater containing Ca2+ and SO4 2- ions.IntroductionWater availability is a significant factor in mining projects. Water, particularly fresh water from rivers and underground water, is becoming a scarce resource for mining operations and new projects. Under these circumstances, the use of water with high concentration of salts in flotation plants is becoming increasingly important (Cisternas and Moreno, 2014). The use of seawater has been studied as a sustainable solution for many mining companies in dry areas located near the sea. Notably, using seawater in mining operations is how mining companies in Chile have coped with the problem of water resources (Cisternas and Gálvez, 2014). In 1930, small plants in Chile used seawater to float chalcopyrite from high-copper-grade ores. In 1975, the results of tests in pilot plants for the flotation of copper minerals with seawater were reported. It was found that froth formation in seawater at pH 9.5 was suitable to make the rougher circuit work properly, even without frothers. The Cenizas mining group successfully floated chalcocite, bornite and chalcopyrite in the Las Luces plant in Taltal in Chile using seawater (Moreno et al., 2011). Minera Centinela (Antofagasta Minerals S.A. Chile) is currently processing porphyry copper ores using a seawater mixture consisting of 20 percent fresh seawater and 80 percent recycled water. Lower consumption of flotation reagents was reported in both seawater and salt water. In addition, studies performed with synthetic seawater showed that certain frothers increase the froth volume, whereas others decrease it. Additionally, the froth produced with seawater carries a high amount of gangue, and low-quality concentrates are obtained, requiring more cleaning stages."

Jan 1, 2015

By Julian Glasser

Starting with rutile, containing more than 55% TiO2 and of the proper particle size, the commercial production of titanium tetrachloride via fluidized bed chlorination is relatively very simple and economical. As compared to shaft chlorination, it operates at a much higher capacity for given sizing of equipment, and appears more foolproof, requiring less attention. Operating data were obtained on a 53" diameter fluidized bed chlorinator using Australian rutile and petroleum coke of controlled particle size. Production rates varied from 20 to 50 tons of crude TIC14 per day for a campaign extending over one month. Close to theoretical yields and efficiencies were obtained from the viewpoint of chlorine and/or rutile consumption. Details of important equipment design, critical operating conditions and pertinent results are described.

Jan 1, 1962