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By J. H. Hammarstrom, S. M. Fortier, W. C. Day, S. J. Ryker, R. R. Seal

"The United States’ supply of critical minerals has been a concern and a source of potential strategic vulnerabilities for U.S. economic and national security interests for decades (for example, see Strategic and Critical Minerals Stockpiling Act, 1939). More recently, with the rapid increase in the types of materials being used in advanced technologies (Fortier et al. 2018a), and geopolitical events surrounding the supply of rare earth elements (Ting and Seaman, 2013), among other developments, the critical minerals issue has again achieved a high level of visibility within the U.S. government (Executive Order 13817 (2017)).In this paper, the U.S. Geological Survey (USGS) provides an overview of its ongoing focus on critical minerals through the agency’s core competencies in mineral information, mineral resource assessments, geologic and topographic mapping, geophysical surveys and mineral resource research. Aspects of the multifaceted critical minerals issue addressed here include:• Identifying minerals that meet the definition of “critical” provided in Executive Order 13817.• U.S. net import reliance for critical mineral raw materials.• Current status of domestic critical mineral resource assessments.• Current status of topographic and geologic mapping, and geophysical survey coverage of the United States.• The Earth Mapping Resources Initiative (Earth MRI) to support future critical mineral exploration.• Critical mineral potential of waste streams from extractive industries.Identifying minerals as criticalU.S. government agencies and other organizations use a number of existing definitions and criteria to identify a mineral or mineral material as critical, strategic or otherwise important. The executive order defined a “critical mineral” to be “(i) a nonfuel mineral or mineral material essential to the economic and national security of the United States, (ii) the supply chain of which is vulnerable to disruption, and (iii) that serves an essential function in the manufacturing of a product, the absence of which would have significant consequences for our economy and national security.” This definition is broadly consistent with that defined by the National Research Council (NRC, 2008) and may be summarized as “essential in use” and “subject to disruption of supply.” Virtually all of the dozens of critical minerals studies conducted since the 2008 NRC report have used some variation of this same definition (Hayes and McCullough, 2018)."

May 1, 2019

By Alten F. Grandt

Surface mining consists of the removal of the geologic strata overlying the coal seam usually with large electric shovels, draglines or bucket wheels. The method produces more or less parallel ridges or peaks of cast overburden, usually called "spoil banks". The mined lands vary widely in their inherent characteristics to produce a vegetative cover and thus can be put to a wide variety of uses. Use is the key to economic and social benefits. Physical and Chemical Characteristics of Soil Material of Surface Mined Lands after surface mining operations, the soil material is a heterogeneous mass whose physical and chemical properties are dominated by the character of the geologic strata overlying the coal. These strata are highly variable in thickness and character. They may include the surface soil, loess, glacial till, sands, shales, slates, limestone and sandstone rock. The method of mining with the several types of mining equipment will also affect the resultant mined area.

Jan 1, 1968

By Christine M. Kammer

In 1852, six barrels of iron ore were loaded aboard the steamer Baltimore at Marquette, MI, after a trip by mule wagon from the nearby Cleveland Iron Mining Co. Shipped to Sault Ste. Marie, they were portaged around rapids and reloaded onto another ship for the final journey to the steel mills of Cleveland. In 1855, the same company-the predecessor of Cleveland-Cliffs Iron Co.-chartered the brigantine Columbia to carry the first iron-ore cargo through the newly opened Soo locks. In 1981, about 2,190 iron-ore shipments in the form of taconite pellets were transported by water from US Great Lakes-ports. The total volume during the 284-day shipping season was 63 Mt (62 million It). Counting Canadian ship¬ments, almost 76 Mt (75 million It) of iron ore were moved on the lakes last year. The five Great Lakes-Superior, Huron, Michigan, Erie, and Ontario-contain 20% of the world's fresh water. The area surrounding the lakes has 26% of the nation's populations, 47% of its steel production, and over 80% of the raw materials required to make steel. That figure includes 71% of the country's iron ore and 40% of its limestone. Only the availability of low-cost water transportation of raw materials has kept the heartland steel producers competitive. Iron ore shipped on the lakes originates in the Lake Superior district's Mesabi and Marquette iron ranges. Major mines and their principal partners are Cleveland-Cliffs Iron Co.'s Empire, Republic, and Tilden; Armco and Republic's Reserve Mining Co.; Oglebay Norton Co.'s Eveleth; Hanna Mining Co.'s National and Butler; Inland Steel Co.'s Minorca; Pickands Mather & Co.'s Erie and Hibbing, the latter operated in conjunction with Bethlehem Steel Corp.; and US Steel Corp.'s Minntac. Pelletized ore products at these facilities is shipped through seven principal ports on the upper lakes: Duluth, Two Harbors, Silver Bay, and Taconite Harbor, MN; Superior, WI, and Marquette, MI, on Lake Superior; and Escanaba, MI, on Lake Michigan. In 1981, tonnage volumes ranged from 13.3 Mt (13.1 million It) shipped from Duluth, to Marquette's total of 5.4 Mt (5.3 million It). The ore docks, with two exceptions, are operated by railroads, most of which are owned by mining companies. Table 1 illustrates US iron-ore shipments in 1981. In the lower lakes, ore is discharged at dock facilities close to the great steel-producing centers of Chicago, Detroit, Cleveland, Pittsburgh, and Buffalo. Between the mines and mills, lakes and connecting waterways form one of the country's most effective transportation systems. Each year, vessels on the Great Lakes transport about 181 Mt (200 million st) of bulk industrial and agricultural materials-a greater quantity at a lower cost than can be achieved by any other transportation mode. Major commodities in Great Lakes trade are iron ore, coal, grain, limestone, cement, sand, and petroleum products. About 125 US flag vessels serve this trade, among them 13 "1,000-

Jan 10, 1982

By D. W. Frommer

Processing nonmagnetic taconites by selective flocculation-desliming and flotation requires large volumes of water. If impounded without treatment these off-process waters require excessively large areas for containment. To discharge the waste water into natural waterways would contribute to stream pollution and likely would not be permitted. In Bureau of Mines experiments conducted in the Twin Cities Metallurgy Research Center&apos;s 900-lb/hr pilot plant, approximately 85 percent of water requirements for the flotation-based treatment of a Michigan nonmagnetic taconite were met by reclaimed water. Water reclamation of the off-process streams from flotation was accomplished by controlled additions of lime, sodium carbonate, and a synthetic flocculant to reduce turbidities to <1,000 ppm equivalent Si02, while maintaining a Ca(II) content of 516 ppm in the finished effluent. Flotation concentrates of good quality were obtained using the reclaimed water. The cost of chemicals used in water reclamation was approximately equal to the savings in flotation reagents attributed to recycling of the water.

Jan 1, 1970

By Kadri Dağdelen, Matthew Deutsch, Thys Johnson

Nested pit analysis in open-pit long range mine planning is used to define approximate ultimate pit limits and an initial high-level schedule in the early stages of a project. Modern ultimate pit optimizers can solve for dozens, or even hundreds, of nested pits however often a smaller subset of pits which are evenly spaced with respect to contained tonnage are desired for downstream analysis. In situations where that pushback selection process must be automated, such as when performing sensitivity analysis, or when the best subset of pushbacks is required; an optimization procedure is warranted. This paper describes a dynamic programming algorithm for selecting pushbacks following nested pit analysis, which is performant and addresses a long-standing inconvenience faced by long range open-pit mine planners.

Jun 25, 2023

By Lawrence K. Nordell

Historical methods of designing steel cord belt splices are compared with modern finite element modeling (FEM) methods. Dependence of the belt strength rating on the splice dynamic fatigue strengths is reviewed. A number of splice schematics are examined, using simple spring theory and FEM methods. Steel cord wire rope design is discussed. The importance of the insulation gum rubber properties and their splice dimensional factors and tolerances are analyzed. Splice fatigue lie analysis procedure is reviewed. This may be used to predict splice life or time of failure, depending on how the conveyor belt is operated.

Jan 1, 1993

By W. J. Spat

Political risk is an integral part of the mining business in Northern Andean countries. Peru, Ecuador, Colombia, and Venezuela all have a higher than average political risk compared with other South American countries. Successful operations in such contexts require: 1. Good political risk information; 2. A thoroughgoing political risk management plan; and 3. A strategy to deal with political risk perception on the part of the investing public. Obtaining quality political risk information, developing a political risk management plan, and addressing political risk perception are the foci of this work.

Jan 1, 1999

By James Donald Forrester

JAMES DONALD FORRESTER 32.1-EXAMINATIONS The field examination of a mineral deposit or mining enterprise requires a comprehensive effort to determine all natural and man-made factors bearing upon the problem to be resolved by the investigation. Therefore, the purpose to be served by an examination must be fully understood before the engineer assumes responsibility, and before actual field work starts. A clear understanding facilitates planning the approach to the project for maximum efficiency and thorough acquisition of information. It follows, of course, that the engineer has the necessary knowledge and experience to discharge satisfactorily the professional obligations attending the project. Some studies are in herently more complex than others, and the requirements of the problem are not always the same. Some examinations require the detailed investigation of large operating or nonoperating mines or, possibly, of mining districts; others involve more or less reconnaissance studies; and still others rela¬tively small undeveloped mineral occurrences. Likewise, the primary objective of some analyses may be the evaluation of a mineral deposit or a mining property, whereas in other projects the major objective may be guiding mining or drilling work in the discovery of new or hidden ore bodies and mineral-bearing structures. Thus, the possible range of any given examination may extend in varying degree through one, or more, of the following types of procedures: 32.1.1--GEOGRAPHIC ENVIRONMENT Studies of geographic environment should be made to ascertain the general physical situation in the area under consideration and to identify those correlative factors hearing on the, findings resulting from the field examination. This commonly will include determinations of: A. Location of the field area with respect to the state and county in which it occurs and, if feasible, a record of the township, range and section with reference to the principal meridian, and base line (or lines) that apply. For examinations in foreign countries, or in regions outside the continental United States, it is desirable that the field locality, in each instance, be identified with reference to the boundaries of some form of political entity essentially comparable in character to the divisions used in the United States. B. Distances from existing communities and related service centers, via: 1. Roads, both improved and unimproved. 2. Railroads. 3. Navigable waterways. 4. Airports. C. Topographic relief as it will influence the selection of 1. Pit site or positions of underground mine portals or shaft sites, including dump areas. 2. Mill site, including tailings disposal area.

Jan 1, 1973

By G. Davis

Mineral properties and mineral firms often trade at a market value that is significantly greater than the value indicated by discounted cash flow (DCF) techniques. A possible explanation is that DCF analysis does not consider the value derived from managerial flexibility. Presumably, then, at least some of the difference between DCF value and market value is due to managerial flexibility. This paper surveys the recent attempts to empirically quantify the value of managerial flexibility using option pricing theory. The results indicate that managerial flexibility, at least as measured by the option pricing methodology, falls well short of explaining the gap between DCF value and market value.

Jan 1, 1995

By Rodrigo Peroni, Vitor Campos

Carajás is one of the largest open pit mines in the world. The mine is comprised by a haul road network more than 100 km long, where the need for good roads is paramount and determining of the truck performances. This work integrates, regarding the ultimate pit design, an approach to consider an economic value to an originally unfit material, assuming it has the appropriate characteristics for haul road construction, which sometimes lies over economic iron ore. This measure demonstrated an improvement in the utilization of resources and guarantee the necessary material to the haul road design and Mining Pads maintenance.

Jun 25, 2023

By T. L. Myron

To determine the effect of flux crystal size on the production rate and strength of sinter, batch sintering tests were conducted on samples of both dolomite and limestone of various crystal sizes. In addition, calcination tests .were performed on the dolomite and Limestone to determine the effect of crystal size on calcination rate at various temperatures normally attained in sinter beds. The results indicate that flux crystal size does not affect sinter production rate or sinter strength.

Jan 1, 1962

By Augusto Andres Torres Toledo, João Felipe Coimbra Leite Costa, Luciano Nunes Capponi, Diego Machado Marques

Short-term mine planning to open pit requires defining diglines to orientate the excavation geometry. In deposits with multiple chemical variables, it is necessary to have more rigorous control over the feeding of the processing plant. This study analyzes the impact of incorporating multiple chemical variables, the risks generated by geological uncertainty, and the number and starting point locations of shovels in the sequential design of diglines. The objective is to maintain and preserve the low-grade variability, required tonnage, and continuity in sequentially selecting blocks. To achieve this, the probability distribution function of each chemical variable is used while attempting to maintain the ore grades as constant as possible. As it is difficult to maintain multiple elements with low variability simultaneously, the relevance of each chemical variable in the economic benefit is identified. Weights are assigned to signal the importance of each element based on its significance in the recovery process. Several diglines, consisting of sequential blocks, were generated on the same seed point to meet the weekly ore demand. Optimizing the stationarity of multiple chemical variables, accessing and reducing the geological uncertainty performed through geostatistical simulation of grades and transfers functions, considering the number and location of shovels, while meeting the operational restrictions of the selected blocks. The optimized digline with the multiple grades as stationary as possible is retained. The process is illustrated in a phosphate mine. The results show that the proposed method is viable and allows for a quick solution.

Jun 25, 2023

By P. A. Plunkert, D. E. Morse, L. McCartan, S. F. Sibley

Following the recession of 2001, restrained consumer spending, declines in domestic manufacturing and industrial output, and increased unemployment led to a lack-luster year in the domestic economy. In 2002, the U.S. real gross domestic product (GPD) grew only 2.4%. Significant production declines in the U.S. metals industry were registered by copper, lead and zinc producers. Steel producers, despite a slight improvement in shipments, continued to face strong foreign competition, higher energy costs and lower prices for their products. Homebuilding and other domestic construction sectors— major consumers of nonmetallic mineral products such as cement, brick, glass and stone — remained strong enough to help raise the output of industrial mineral materials slightly above 2001 levels. A strong U.S. dollar relative to other national currencies continued to weaken the competitive stance of U.S. metal and non-metal mineral materials companies alike against foreign producers in markets at home and abroad.

Jan 1, 2003

The National Mining Hall of Fame and Museum (NMHFM) in Leadville, CO will induct the class of 2011 on Sept. 10, 2011. Representing the coal, metallurgical/processing, research and development, marble and lead industries, this year?s inductees cover a diverse crosssection of the mining industry. William Francis Diamond, Wayne Hazen, Redfield Proctor and Jeffrey Zelms will join 210 other mining industry pioneers when they are formally inducted into the National Mining Hall of Fame at the 24th Annual Induction Banquet and Ceremony. The members of this year?s class were selected for being visionaries, leaders and ambassadors both within their own sectors and across the industry at large. Diamond had an illustrious engineering and managerial career that spanned four decades with Island Creek Coal Co. During that time, he was responsible for the engineering and construction of the deepest coal mines producing in North America at the time.

Jan 1, 2011

By J. E. Osmanski

This semantically ambiguous title purports to describe an examination of the question of automation and its effect on the industrial worker. More explicit titles might be "Painless Automation" or "Mechanization without a Sting" or, if I may steal a few phrases from the title of a recent interview Pith John L. Lewis, "More Machines, Fewer Men -- Is the Union Happy About It?" Automation has become the biggest ?scare word? for many industrial workers and their unions since "wage stabilization.? "To many a union orator," reports TIME of January 4, "automation is the sinister business of eliminating jobs." TIME might better have phrased this description by saying that many unions regard automation as the attempt to eliminate not jobs, but workers, The recent steel dispute was hung up for so long primarily because of the problems evolved of increased job efficiency through automation and job changes. Everywhere today there is heard the cry of our need for maintaining full employment within the context of an expanding economy echoing against the sheer reality of automation&apos;s displacement of thousands of workers through a rapid acceleration of productivity.

Jan 1, 1960

By B. Petkof

Olivine has been an accepted industrial mineral for the last 50 years. Its initial acceptance was based on the recognition of its refractory properties by European research workers in the middle to late 1920&apos;s. Initial U.S. olivine production began in the early 1930&apos;s in North Carolina and continues there today. Olivine also is produced in the State of Washington and in other countries.

Jan 1, 1982

By Allan Breitenbach

Leaching has been used since the 1600s on unlined ore dumps and since the late 1970s on lined leach pads for the recovery of metals from mined ore, the latter typically called ?heap? leaching and the former ?dump? leaching. Modern day run-of-mine (ROM) or crushed ore heaps are stacked in controlled lifts on lined leach pads and irrigated with a solvent solution (dilute alkaline cyanide for precious meals, dilute sulfuric acid for base metals and uranium). Conventional lined leach pads store process solutions and any storm water, snow melt and cumulative wet season surplus water by gravity flow to external ponds. Impounding valley leach pads (also known as valley fill heaps) differ from conventional leach pads by storing various combinations of process liquid solution and surplus water within internal ponds by using the interstitial pore volume of the ore. While impounding liquids within the heap is simple in concept, impounding leach pads are more complicated for construction and containment compared to conventional leach pads with external ponds.

Jan 1, 2012

By Robert M. Stevens, Arnoldo Acuña

INTRODUCTION In the early 1950s, underground miners and tunnel¬ing contractors were experimenting with ways to supple¬ment or eliminate track-bound loading and hauling equipment. Diesel-powered crawler and rubber-tire mounted front-end loaders and trucks designed for use on the surface were being modified and tried with limited but encouraging success. Miners began working with interested manufacturers to explore the develop¬ment of vehicles specifically designed to meet the de¬mands and constraints of underground material han¬dling. By the mid 1960s, load-haul-dump (LHD) vehicles were firmly established as a fundamental part of what has become known as the "trackless" mining concept, used in many mines and many countries around the world. The flexibility, mobility, and versatility of these units have given the industry a useful tool and have added new dimensions to mine development and produc¬tion. Many old mines have been redesigned to accom¬modate these trackless vehicles, and few new mining plans have failed to find some use for the concept during some phase of development and production. By 1977, several manufacturers in several different countries were producing a variety of LHD vehicles to meet the growing worldwide demand. GENERAL DESCRIPTION LHD vehicles combine certain characteristics of conventional front-end loaders and dump trucks, spe¬cifically designed for materials handling in underground mining and tunneling. The design intent is to provide one vehicle with one man, with the vehicle loading itself, hauling the load over level or inclined haulageways, and dumping the load. A typical production cycle of the most popular units has the operator driving the vehicle forward, forcing the bucket into the muck at or near floor level, and using the tractive effort of the vehicle and the prying action of the bucket to roll out and tilt back the load as shown in Fig. 1. With the bucket rolled back into the carrying position on the boom and the boom resting on the main frame of the vehicle, the load is hauled (trammed) to the dump point as shown in Fig. 2. At the dump point, the boom is raised, the bucket is rolled forward, and the load slides out as shown in Fig. 3. After dumping, the bucket is rolled back to the carrying position, the boom is returned to rest on the main frame, and the unit is driven back to the loading point for another load. There are two other types of LHD units that are slightly different in the cycles that they perform. One uses a hopper arrangement carried on the front of the machine, with a small bucket mounted ahead of the hopper. Several passes with the small bucket load the hopper, which is dumped by opening its floor. Al¬though this concept is several years old, it has gained less than 0.5% of the total market. The most recent LHD concept differs in that it has one bucket nesting inside another. The smaller inner bucket is loaded first, and it is then tilted back and above the larger bucket. When the larger bucket has been loaded, it is rolled back, and the total load is trammed to the dumping point. The dumping operation tilts the buckets in the reverse order from that of the loading operation. The impact of this new concept on the mining industry has not been measured yet. This chapter concentrates on the LHD vehicles employing the cycle described by Figs. 1 through 3, since these LHD units constitute an estimated 99% of the units in current use. MAIN VEHICLE FEATURES In general, the LHD vehicles available from most manufacturers share the same basic features.

Jan 1, 1982

By Edmundo Tulcanaza

Increasing exploration costs and the need to reduce the time-frame from exploration to production presently demand formalized procedures to assist exploration planning and reserve analysis. Exploration planning is basically required to select the most cost-effective drilling/sampling program, and to flag the needs for data of greater relevance and reliability. Reserve analysis is necessary to determine the sensitivity of grade-tonnage relations, and to clarify the economic implications of mining when alternative technical choices are to be considered.

Jan 1, 1982

By J. Leonard Frame

A coal-fired fluidized bed combustion (FBC) system will be installed at the Owatonna Tool Company, Owatonna, Minnesota. Two FBC combustors will burn solid fuels: coal, petroleum coke, and wood and paper wastes. Crushed dolomitic limestone will be used to control sulfur emissions to EPA limits. The combustors will supply indirectly heated hot air and hot water for paint drying operations, washing processes, and space heating. The program is sponsored by the United States Department of Energy and the Owatonna Tool Company, and is one of five programs designed to demonstrate industrial applications of coal-fired fluidized bed equipment. The paper will describe the combustion system and the results of development tests with dolomitic limestone for sulfur emission control.

Jan 1, 1978