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By J. Mark Richardson, Mary S. Sredanovic

The use of computerized steady-state process design balance systems has reduced engineering man-hours by as much as 80 to 1 over conventional manual balance calculations. The popularity and widespread use of such systems by the minerals industry increased dramatically in recent years, but these systems were mainly available for use on large main frame computers and lacked graphic capability. A considerable amount of engineering manpower was required to "conceptualize" a process flowsheet. After sketching the flowsheet layout, the engineer was still faced in most cases with a time-consuming reduction of his graphic concept of the problem to numerical data required by the balance program. Furthermore, output from these early systems was usually in tabular numeric form. The computer results then were transferred manually to a pictorial representation of the process. A new process design balance system has been developed which runs on a popular and inexpensive personal computer. This system combines modern Computer Aided Design (CAD) principles and the graphics capabilities of the personal computer to allow the process engineer to define a flowsheet problem while creating a process flow diagram. The system provides balance results in both pictorial and tabular form. Past, present, and potential applications of the system are discussed, and an analysis of the cost benefits derived from its use are provided.

Jan 1, 1985

By Y. C. Kim

To generate a most profitable, ultimate pit limit is generally the first step in mine design. This paper presents a new graph theory oriented, optimum ultimate pit limit design algorithm which will maximize the total undiscounted net profit. This algorithm performs much better than the well known Lerchs-Grossmann algorithm, in terms of the reduction in computation time and computer memory requirements. This algorithm operates on many directed trees in a graph, where each vertex in a tree represents a block in the mine model. The formation of each directed tree is based more on the ore-waste support concept than the geometry constraints alone. The general procedures of the algorithm, programming considerations and two case study results are discussed in the paper.

Jan 1, 1992

By Fabio Amaya, Andrés Marulanda, Ramiro Gutiérrez, Alberto Marulanda

The behavior of a salt rock mass is strongly related to a creep phenomenon. The amount of creep depends on the level of stress generated in the underground excavation. Additionally, security conditions and the lifespan of an underground cavern excavated under this geological conditions depend on the evolution of creep. Based on the experience of the failure of the Old Underground Salt Cathedral of Zipaquirá(Colombia) and the construction of the new one, the theoretical framework to predict the creep behavior of a salt rock mass is explained. The theoretical formulations are calibrated based on actual observations of the material behavior to predict the lifespan of this striking structure.

Jan 1, 2003

By M. Tapper

If one considers that prehistoric man's first house may have been a limestone cave, calcium carbonate may be the most timeless of all building materials. Fanciful history aside, CaCO3 has been used for countless applications in human habitats. After all, tine marble block and tiles have always been the hallmark of eloquents and style. Mortars and cements derived from limestone have held together the very blocks of our civilization. In modem times, synthetic polymers are blended with ground limestone to produce everything from pipe, floor tile, cultured marble and house siding. All of these miracles of our technology contain CacO3 of various sizes and in varying amounts. This paper will discuss some of the critical attributes of CaCO3 which make it suitable for the new building products that have helped increase our standard of living. The vehicle of discussion will be a residential, single family house.

Jan 1, 1993

By R. D. Ellison, D. K. Shukla, D. E. Stephenson

Seals for man-made penetrations into or nearby nuclear waste repositories require several unique capabilities not common to seals for conventional underground activities. Design criteria include long functional use, extremely low permeabilities of the seal zone (including adjacent disturbed rock), and the potential for retarding radionuclide travel. This paper summarizes comprehensive seal programs being conducted by D'Appolonia for the Office of Nuclear Waste Isolation (ONWI) at Battelle, Columbus. The program schedule requires the first detailed conceptual design for a bedded salt site to be completed in 1982. Conceptual designs for other host media will follow as site exploration data becomes available. The design program is supported by a variety of office, laboratory, and field activities being conducted by ONWI subcontractors. An example is provided to illustrate the variety of efforts directed toward determining the extent of disturbance adjacent to penetrations as a result of in-situ and excavation methods. Also, the current "working design" for the shaft and tunnel seal system at the candidate Los Medanos thick salt site in southeastern New Mexico is presented.

Jan 1, 1981

By Jon Kellar, Samuel Kessinger, Prasoon Diwakar

Tantalum (Ta) and niobium (Nb) are extracted from many different ore types. The major economic orebody mined for tantalum and niobium consists of tantalite ((FeMn)Ta2O5) and columbite ((FeMnNb2O5)) in a solid-solution mineral commonly referred to as “coltan.” The largest supplying region, The Democratic Republic of the Congo (DRC), is unfortunately also the most ethically compromised source for this critical mineral. Officially, the U.S. government has deemed coltan ore from the DRC a “conflict mineral” [1]. The lack of pragmatic and effective local mining regulation in Central Africa, when coupled with high levels of violence and corruption, has spawned a widespread, illegal, unethical and, most importantly, unsafe economy. This illicit economy is centered around first, illegally mining these valuable conflict minerals and second, smuggling these minerals into the global supply chain. Handheld spectroscopy devices could provide further transparency to these opaque supply chains, giving miners, traders and refiners the ability to authenticate the provenance of the minerals they encounter, and allowing companies to prove compliance with the regulatory agencies attempting to curtail illicit mining.

Mar 1, 2025

By Gary P. Marshall, Jeffery S. Thompson, Robert E. Jenkins

The effectiveness of the new DuPont Passivation Technology in eliminating acid generation from iron sulfides is presented. Passivation is achieved by treatment with a dilute basic perman­ganate solution. This treatment produces a thin impervious layer of iron/manganese oxide on the sulfide surface, providing a bar­rier to the environment so that the sulfide is not available for undesirable reactions such as the production of acid.

Jan 1, 1998

By D. Y. Geng

Longwall mining is a relatively new mining method in the United States. Early trials in the eastern and central coal fields were not successful, mainly because, among others, the face supports did not have sufficient capacity. It was not until in the late 1960's, when the high- capacity self-advancing powered supports became available, that longwall mining was successfully reintroduced. Since then the number of mines employing the longwall method has been steadily increasing. It has reached approximately 7.5% in 1981. Currently longwall mining is used mainly in the Appalachian coal field. The seam depth ranges from 150 to 2500 ft. but mostly between 300 and 1400 ft. The seam thickness ranges from 32 to 144 inches with the majority between 40 and 100 inches. Nearly all longwall mining are in flat or nearly flat seams extracting in single slice, although one inclined and one thick seam longwall mining have been either operated or initiated in Colorado.

Jan 1, 1983

By Richard C. Smith, Steven H. Brown

Commercial scale in-situ leach uranium facilities (i.e., solution mining) have operated since late 1975, and have begun to appear in increasing numbers in the last few years. Solution mining involves the pumping of ground water, fortified with oxidizing and complexing agents, into an ore body, leaching and solubilizing the uranium in-situ, and then pumping the solutions to the surface where they are fed to a mill. Milling is by conventional means, involving ion exchange, precipitation, calcining and packaging processes. This paper presents an overview of the solution mining process, and discusses an empirical method that has been used to determine the radon gas release rate in Bq (curies) per year for the overall operation of the facility including wellfields, milling processes and waste storage reservoirs. In addition to radon generation on the surface from radium decay, it has been determined that the major component of radon release is associated with the dynamic generation of radon from solutions returning from underground. Process parameters impacting this evaluation and the mathematical expressions developed are discussed. The preliminary data accrued is presented.

Jan 1, 1981

Power cable costs are only a small part of total mining costs. So many mine operators consider power cable failure and resultant downtime as part of the cost of doing business. But, viewed in terms of lost production, these costs can be quite significant. Now one company, Cablec, seeks to cut cable costs by upgrading the polymer compounding process used to make cable insulating and semiconducting materials. Cablec is the leading manufacturer of electrical power cables in North America. And with about a third of the market, Cablec is the largest supplier of power cable to the mining industry in the United States. To improve its products, Cable has entered the polymer compounding business. In July, it began producing insulator and semiconductor polymer compounds at its plant in Indianapolis, IN. "This new facility provides a quantum leap over conventional compounding methods," said Harry C. Schell, Cablec's president and chief executive officer. "The Cablec polymers plant is producing a dramatically higher standard of polymer compounds that provide significantly higher levels of performance and improved life cycle costs for power cable." Cablec faces tough foreign competition in the wire and cable business. Competing on price alone is difficult, particularly when foreign producers are state subsidized. So Cablec feels the best way to compete is to establish new quality production standards. The company's new polymers plant is one way to do this. By increasing purity control and uniformity in polymer compounding, Cablec says its power cables will last longer and fail less often. A typical medium voltage cable consists of a conductor, conductor shield, insulation, insulation shield, metal shield, and jacket. The conductor shield and the insulation shield are conducting polymers. Contaminants and imperfections can occur within the insulation, at the conductor shield/insulation interface, or at the insulation shield/ insulation interface. Over time, these contaminants and imperfections can decrease the electrical strength of the cable or cause premature cable failure. The effort to minimize the number and size of any possible contaminants begins with pure polymer compounds mixed in a clean facility. However, most power cable manufacturers manually handle raw materials, use ethylene/propylene (EP) in bulk bales, and mix polymercompounds in open Banbury mixers. The quality and uniformity of polymer compounds is also impacted by temperature variations in the mixing process. This results in wide gradations of product consistency from batch to batch and ultimately contributes to power cable failure. Cablec says the improved polymer compounds from its state-of-the-art plant will be the purest and most consistent insulating and semiconducting materials available. The plant itself RCA spent $18 million to build Cablec's Indianapolis plant. RCA used the facility to mix specialty polymer compounds used to make video disks. RCA had two considerations in mind for the plant, cleanliness and uniformity of the compounds. However, when the video disk market failed to materialize, RCA sold the 46.5 dam 2 (50,000 sq ft) plant to Cablec for $3.1 million. Cablec invested an additional $3 million for modifications and increased production capabilities. Today's replacement cost for such a facility is estimated at $30 million. Cablec says the plant will set a new standard for performance and be economically difficult to duplicate anywhere. One of the essential elements of the plant's clean process environment is the air intake system. It filters contaminants greater than 2 um, less than one-fiftieth the current industry standard. All material handling and conveying areas in the facility are air-locked. This keeps out contaminants such as smoke, dust, and pollen. Banks of pneumatic pumps move polymer components through the system and continually filter the air. The plant also has a backup air intake system. No process downtime due to pump failure here. From the time raw material enters the plant, it is stored, transported, and processed in filtered air by an airtight stainless steel system. The stainless steel resists rust and corrosion. This further eliminates the danger of contamination from paint or rust particles in the conveyance network. A computer system allows a single operator in a central control room to monitor every aspect of the compounding process from air quality to line speed. The computer

Jan 12, 1988

By Henry Brehaut

The International Network for Acid Prevention (INAP) was formed in 1998 by 17 international mining companies to promote significant improvements in the management of sulphidic mine materials and the reduction of liability associated with acid drainage through knowledge sharing and research and development of technology. Since its inception two panels have been formed to identify and move forward with research projects and eight networks have been constituted to initiate interaction and knowledge sharing within the membership in specific areas of technical interest. An INAP web site has been developed to facilitate the sharing of information and to encourage the exchange and development of new ideas.

Jan 1, 2000

By Christian F. III Baiz

Introduction A new mining agenda is before us. Born of government policies and world economies, the years ahead will show reduced growth. Metals, mining, and most other natural resource industries are inflation dependant and capital intensive. For these, a long period of contraction of outmoded and costly capacity will evolve. In some cases, this will be supplanted by new, lower cost capacity. But this will occur only if the cost of production - including cash operating and debt service costs - comes in at or below current market conditions. The industrial outlook for metals mining can be characterized as bearish. A US bank economist said mining companies planning their five-year forecasts should take current market conditions and straight-line them to the end of the decade. With low growth and low inflation, the real price of metals will remain flat or decline slightly. As a result, capital funding will be problematic. The low-cost producer will succeed. That means only the producer with low cash costs and low principal and interest costs per unit of production, will succeed. Gaining a perspective One must look back 30 years to see the evolution of the capital markets, for metal mine financing. This period can be divided into two economic periods. The 1950s were a time of stable economics. Mining companies earned and reported good profits. They had good corporate creditworthiness. In essence, mining companies of the 1950s were highly self-reliant. When equity infusions were needed, they were easily obtained. Financial management kept long-term debt low. Fixed rate, long-term financing was readily available in the long-term bond markets. The commercial banks of the 1950s were rarely used by the mining industry. When necessary, mining companies went to the banks for short-term financing - the kind that was needed for working capital requirements. Changing rhythms In the old rhythm there was an orderly market. Even into the mid-1960s, 75% of world annual copper production was controlled by eight companies: two in the UK, one in Belgium, and five in the US. During times of poor market demand, these producers would control supplies to the market. They took their losses out of retained earnings. Capital was easily restored during the ensuing good times. The new rhythm called for copper to be an economic means to a political end. Third World copper producers brushed aside the market fundamentals of commodity economics. Yet, the political solutions of these countries - their lack of response to the market - have seldom achieved their original objectives. Each commodity has its own old and new rhythm. Aluminum may have a similar rhythm, coming 10 to 20 years later than copper. By the late 1960s, changes were occurring. Inflation was on the rise. Ore reserve quality was falling. As a result, capital expenditures were necessary to maintain existing output. These costs created an increase in corporate leverage, thus adding to inflation and rising interest rates. Indicators A comparison of the gross national product (GNP) deflator index, consumer price index, and the metal mining deflator index is instructive. (Fig. 1 and Table 1). With 1972 equal to 1, note that the metal mining deflator reached its lowest point in 1967. From that point, the metal mining deflator has accelerated severely for 16 years. Only two minor downturns occurred during the business recessions of the mid-1970s and the early 1980s. In essence, Fig. 1 shows that while GNP has grown modestly, a miner's dollar in 1972 would require $3.48 in 1980. This is an almost 17% compounded growth rate over that eight-year period. Beginning in the late 1960s, for the first time in mine financing, the risk of success shifted from the corporate balance sheet to third parties. Limited-resource financings were taken up by banking syndicates that accepted certain of these risks. The lender needed to be well acquainted with the types of risks to be evaluated. These include resource quality and quantity, construction and completion, capital and operations costs, market risks, force majeure, and political and exchange rate risks. Project financings became the basis whereby mining companies were able to maintain their borrowing capacities. In essence, the lender was willing to share some of the project risk while only receiving lenders' returns on these investments. Over the last two decades, mineral project financings have become highly complex transactions involving multicurrency, multi-

Jan 8, 1985

By Q. X. Yun, S. H. Liu

This paper provides a new approach to determine the opening layout in underground mining methods by means of genetic programming. Based on a set of random combination of openings, the layout of openings will gradually improve with the help of genetic operations, including reproduction, crossover, mutation and fitness calculation. The optimal solution will finally emerge according to Darwinian principle: "the survival of the fittest ".

Jan 1, 2002

By Dan Walker

The success of the heap leaching process for extracting precious metals from low grade ores in many cases depends on successful agglomeration of clay fines. This paper relates the development of a new agglomera­tion agent, named Leachit, that has demon­strated an ability in some ores to decrease leaching time. Data from a commercial test­ing laboratory is presented to illustrate a comparison of leaching efficiencies with other agglomerative agents, such as lime and portland cement. Conclusions will point out certain advantages of Leachit to the heap leaching gold recovery industry.

Jan 1, 1992

By Paul D. Tomlingson

Numerous worthwhile benefits accrue to the industrial organization that is supported by a maintenance organization performing at a world class level. That organization will be favored with consistently reliable production equipment. It will be assured of meeting production goals. Its product will exceed marketplace standards. Its customers will see them as a quality organization. Its employees will enjoy job satisfaction and the plant will realize continuing profitability. Every industrial plant aspires to achieve ?world class? status knowing it can compete favorably with the best, most profitable organizations in the world. The trick is to achieve the attributes that qualify your organization for world class status. But there are no world class maintenance organizations. Rather, there are world class industrial organizations that include a world class maintenance organization. Maintenance, by itself, is a service provider, dependent on the support and cooperation of other departments. When that service is exceptional, it is made that way because maintenance is operating in a plant environment that requires it to be exceptional. Managers have created an environment in which maintenance can be exceptional. The plant, mine or facility manager must acknowledge from the start that maintenance is not a stand-alone effort of a plant maintenance department. It will require the joint efforts of all plant departments. Quality material support and full cooperation from operations, for example, are among the essential requisites for effective maintenance and achievement of world class maintenance status. When attributes such as these are reinforced by dedicated plant managers, profitability soon follows.

By J. Guzman

Introduction The Carlin Trend is North America's premier gold producing district. It is located in northeastern Nevada's Elko and Eureka Counties along a northwest trending belt about 65 km (40 miles) long and 8 km (5 miles) wide (Thorstad, 1989; Jones, 1989). This trend is the worldwide reference site for epithermal, sedimentary rock-hosted microscopic gold deposits. At least 19 deposits have been discovered to date, varying in size from 933 kg to 1.08 kt (30,000 to 35 million contained oz) of gold (Fig. 1). Newmont Gold Co. and its parent, Newmont Mining Corp., jointly constitute the largest mineral right holders in the district. They own or control more than 1000 km' (386 sq miles) in and around the Carlin Trend and own all or part of I6out of the 19 mines and prospects identified to date. Since the initiation of Newmont's exploration activities in the Carlin Trend in 1961, 2.24 kt (72 million oz) of cumulative gold resources have been identified. Cumulative production from all mines since the start-up of Newmont's Carlin mine in 1965 to the end of 1989 was about 202 t (6.5 million oz) (Jones, 1989). The incentive of sustained high gold prices and innovation in processing technology resulted in a significant acceleration of gold output over the last few years. Newmont Gold alone produced more than 43.5 t (1.4 million oz) in 1989. That is equal to 22% of the cumulative 1965 to 1988 output, and an almost 200% increase over its 1986 output. The same incentives produced even more spectacular exploration results. In each of the last five years, net additions to reserves and resources outpaced current production by substantial margins. These facts demonstrate the spectacular past prospectiveness of the Carlin Trend and the success of focused, multi-disciplinary exploration methods that made it possible to more than offset the recent accelerated depletion of gold resources. However, is this situation sustainable? How long can the mining companies along the Carlin Trend keep on finding resources faster than they deplete them? These are some of the questions that motivated this study. The authors have not quantified the future potential for gold exploration in the Carlin Trend nor established a deposit discovery path. But strong indications were discovered that the [ ] Carlin Trend remains a relatively immature exploration district and that the potential for significant new discoveries is high. Methodology and data The approach chosen to address the above questions was simple. The authors compiled deposit size data, measured in contained ounces of gold resources, for all known deposits along the Carlin Trend (Table 1). The resource information was obtained by adding cumulative historical production (adjusted for mining losses and metallurgical recovery) to 1989 year-end published resource inventories. In a mature exploration area, where most deposits have been discovered, this distribution would be expected to approximate lognormality and would plot along a straight line on a lognormal probability scale. This result was found in previous work by Allais (1957) and recently confirmed by Cox and Singer (USGS, 1986) in regard to various types of mineral deposits in several regions of the world. It was also found to hold true for oil and gas pool size distributions (Arps and Roberts, 1958; Kaufman, 1962; McCrossan, 1969). [ ] The data used were compiled by Newmont Exploration geologists. The purpose of the study is to make inferences about the underlying geologic processes in the district and the maturity of the exploration effort. Therefore, deposits were not classified according to ownership but according to geologic occurrence as known from current information. Newmont's Post and Barrick's Goldstrike and Betze deposits, for example, are shown as a single occurrence to reflect the actual geologic setting. The cumulative frequency distribution of deposit sizes was plotted on lognormal probability paper (Fig. 2). The abscissa shows the cumulative fraction of deposits at or below a certain deposit size and the ordinate shows the deposit size in thousands of ounces of contained gold resources.

Jan 1, 1992

By Elza Burch

Introduction The feeding to zero concept involves feeding 600 µm x 0 (28 mesh x 0) size raw coal to heavy media (magnetite) cyclones along with the +600 µm (+28 mesh) size coal. Traditional circuits employ desliming or removing the 600 µm x 0 (28 mesh x 0) size fraction and feeding the cyclones +600 µm (+28 mesh) size coal. The feeding to zero concept recirculates 600 µm x 0 (28 mesh x 0) fines in the circuit. At the same time, a portion of the fine material is continuously withdrawn and recovered. This, in turn, prevents a fines buildup. This concept eliminates desliming screens and secondary fines circuitry for recovery of 600 x 150 µm (28 mesh x 100 mesh) coal. The result is a very simple circuit. Feeding to zero at Island Creek Island Creek Corp. was the first involved with the new concept in 1976. The company needed a temporary plant for the 9.5 mm x 0 (0.4 in. x 0) raw coal at its Pond Fork mine, near Madison, WV, while a full-scale plant was being designed and built. At that time, the Childress Corp., of Beckley, WV, became interested in the feeding to zero concept. Island Creek awarded a contract to Childress to build a single cyclone modular plant, incorporating this feeding to zero concept. The plant was erected in three months. The Pond Fork modular plant proved successful in attaining the desired feed rate of about 63.5 t/h (70 stph), while maintaining good separating efficiencies and low magnetite consumption rates. The 9.5 mm x 150 µm (0.4 in. x 100 mesh) clean coal was recovered and the 150 µm x 0 (100 mesh x 0) size was disposed of to waste. The full-scale plant was completed about two years later and the Pond Fork modular plant was moved to Holden, WV. There, it was incorporated into the Holden 29 preparation plant as a separate circuit for cleaning -25 mm (-1 in.) coal. In 1976, a similar plant was installed in Virginia by another company. These two plants are believed to be the first two operational plants in the United States incorporating the feeding to zero concept. Island Creek subsequently contracted with Childress for an identical plant at the Coal Mountain operation in West Virginia. The plant operated for three years before the mine was closed. The unit was then moved to the Spurlock mine near Martin, KY where it continues to operate. The successful operation of the Pond Fork and Coal Mountain plants before and after relocation proved both the performance and moveability of this type of circuit when constructed in a modular fashion. Since the first two plants were built, Island Creek has incorporated the feeding to zero circuit in nine additional plants. A grand total of 33 cyclones have been installed using this concept. One is the Providence mine, near Providence. Providence preparation plant Island Creek contracted with J.O. Lively Corp. of Glen White, WV in July 1978 for the construction of the Providence preparation plant. The plant began operation in February 1979. The construction period was about halved by building the plant with modular design concepts. Prefabricated sections, floors, and sides were brought in as units and then bolted in place. The Providence plant has a good track record of processing coal at a feed rate of 454 kt/h (500 stph). Feed coal to the plant has an average ash content of about 18% and sulfur content of about 4.5%. It contains about 22% refuse. The coal product has an average ash content of about 8% and sulfur content is about 3%. Raw West Kentucky No. 9 seam coal is conveyed from a box cut in the Providence mine to a rotary breaker. The breaker is fitted with 74 mm-diam (3 in.-diam) opening breaker plates. Therefore, it is well suited for removing trash, roof bolts, wood, and pyritic balls that are common in Illinois Basin coal. The -75 mm (-3 in.) coal is conveyed from the rotary breaker to

Jan 8, 1987

By Andre Vien, Marc Grondin

For many years mill operator training was an informal process which involved senior operators training junior operators on an as-needed basis. The more rapid incorporation of new processing and information technologies, the goal to keep labour costs to a minimum by doing more with less, and the complexity of AG/SAG mill operation has forced companies to have a closer look at operator training. This paper describes a conceptual model of the charge of a AG/SAG mill that can be used for operator training. The conceptual model divides the charge into three regions: cascading, cataracting and toe. Mill behaviour is explained by the changes that occur in each region.

Jan 1, 1997

By Joe D. Allison, Tom D. Baugh

The analysis for total cyanides (CN, or the cyanide due to the combination of free, weakly associated and refractory cyanide complexes) is required by most regulatory agencies for determination of effluent compliance. This method requires a distillation of the sample at low pH's and is most often sent to contract laboratories at a high time and monetary cost. This paper describes a new micro­distillation apparatus which allows for a multiple of CN,"' analyses to be carried out simultaneously saving both time and money. It can be used in the field, since only electrical power is required for the method. While not being appropriate for reporting values to the respective regulatory agencies as of yet, it is quite valuable for screening a large number of samples prior to submission of the samples to a contract lab for "official" reporting.

Jan 1, 1990

By David De Lemos Pires

Mining is essentially a materials management process where materials are classified, excavated, moved to a desired location, processed at a cost and sold for a price hopefully to generate a profit. ?How much is that cost and can it be reduced?? is the age-old question. The requirement for a paradigm shift with regard to materials movement in search of low-cost production has not just happened by chance but, rather, has been driven by agents of change that include mining companies, consultants, governments and equipment suppliers. During the past 100 years of mining, surface mining technology has involved humans with hand tools, humans with machinery and unmanned automated equipment. In the past 50 years, surface mining technology has evolved and now takes the form of trucks and loaders (TL), in-pit-crushing conveying (IPCC) and autonomous haulage equipment (AHS).

Dec 1, 2013