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By Alexander N. Winchell

"Location. The iron formation of the Gogebic district (including the Penokee) comprises a narrow belt south of the western part of Lake Superior extending from Michigan for a considerable distance into Wisconsin. From the mouth of the Montreal River (about twenty-five miles west of Ashland) the iron formation is only about twelve miles distant, but it is about twenty miles south of Ashland. Beginning on the east at a point about eight miles east of Wakefield, Mich., it extends through Sunday Lake, Bessemer and Ironwood in Michigan, and thence south of west through Hurley, Wis., and only a short distance south of Mellen, Wis. About eight miles westward from Mellen, the formation disappears, but six miles further west it is known to reappear and continue thence for about eight miles. The total length of the range is about sixty miles, two-thirds of this distance being in the State of Wisconsin; but nearly all of the ore has been obtained from the eastern third of the district, which is in the State of Michigan.History. This iron range was first noted in 1848 by Dr. Randall, assistant geologist to Dr. David Dale Owen, while following the fourth principal meridian northward. It was also reported by Charles Whittlesey in an account of a survey made in 1849, and published by Owen in 1852. Analyses of the iron ore are given with the following account. ""The bed of magnetic iron ore south of Lac des Anglais is of extraordinary thickness,25 to 60 feet. * * In the wild and deep ravines where the Bad River breaks through the range, there is a cliff of slaty ore * * * probably three hundred feet thick. * * * I estimate more than one-half of this face to be ore, and in places the beds are from ten to twelve feet in thickness, with very little inter-mixture of quartz * * * . The position of the best exposures of ore which I saw is such as to require from eighteen to twenty eight miles of transportation to reach the lake."""

Jan 1, 1920

By J. R. Arnold

The problem of recovering gold from a cyanide solution has been plaguing metallurgists since the cyanidation process was discovered in Glasgow, Scotland.1 The "perfect" method has never been found and this paper will not purport to fill that gap. But we, at Gold Fields, feel that we have developed a workable, cheap and efficient method of producing a refinery - ready product that has several distinct advantages over conventional electroplating techniques. The Gold Fields replating system is presently being used at their Ortiz and Mesquite operations. In short, the system electroplates the gold out on stainless steel wool, instead of mild steel wool as is usually done, then replates the gold by reversing the current onto stainless steel plates. By doing this the steel wool can be reused many times, the gold can be scraped off the plates cleanly and quickly, the operating costs are reduced and the slag production is greatly reduced.

Jan 1, 1986

By Mortimer J. Richardson

In the context of this session on "Practical Placer Mining," a projection of the present into the future first assumes that there is a future for Placers. The second assumption is that there is the combination of adequate reserves and a willing, mining investment source to finance placers. This paper will point out the opportunities on both assumptions, illustrating my positive position on the future of gold placers. In order to focus this paper more effectively, I have chosen GOLD as the subject mineral. However, it is recognized that much of the technology for exploring and mining gold placers has been applied to other alluvial deposits; including platinum, diamond, tin, and various industrial minerals (which are often referred to as "placers" though this contradicts historical definitions). Over the past 10 years I have presented several papers on the general subject of placers, most of which are listed under References. These have included topics such as exploration, evaluation, small-scale gold placer mining and decision-making, mining and processing equipment designs, and dredge-mining operations. In an attempt to identify the more promising, undeveloped placer potentials in the world I have usually mentioned the USSR and China but qualified them as being either inaccessible, or, politically difficult to obtain. However, with recent developments in the USSR, the obstacles appear to be somewhat diminished.

Jan 1, 1992

By P. Sarnoff

Gold has always been a crisis investment. For centuries gold has been considered globally the money of last resort. In time of war, inflation, financial uncertainty, political upheaval there has with few exceptions always been a flight to gold. The gold paradox simply is that even though we have gone through for the past handful of years all the kinds of. anxieties that would cause the gold price to rise, it has instead dropped drastically. Figure 1. illustrates the important factors that influenced the gold price significantly up or down before 1987. Obviously, since then, even though we have had wars, inflation, financial problems involving breaking banks and thrifts let alone collapsing financial institutions, the gold price has both in the long-term and the short-term trended downwards. Figure 2. depicts the gold price path since 1987. If the presence of time-honored and time-tested factors that should have driven the gold price up didn't do the job, then logic dictates that new factors to drive the gold price down and keep it depressed arose. And they did. But before addressing these depressants permit me to turn to the arcane art of gold price prediction and fore-casting.

Jan 1, 1992

By Luis Elu, Andy Bolland, Jack Simmons

The gold refinery at Barrick Goldstrike Mines has increased production to more than 2,000,000 ounces poured per year while reducing the labor requirement. Safety and health has not been compromised with this increased production and in fact incident rates and exposures have reduced over the past five years. Streamlining procedures, improving ergonomics and the wise use of unique innovations has accomplished this significant achievement.

Jan 1, 1998

By J. L. Waldron

This paper presents a theoretical tool used to analyze gold recovery problems at Dee Gold Mining Co. The first step in addressing the problem was realizing that lower gold extraction was linked to high silver grades, and could not be correlated to either the carbonaceous or sulfidic content of the ore. Analyses of metallurgical testwork, blasthole, and mill recovery data demonstrated that decreases in gold extraction correlatP� well to increases in silver extraction. Figure 1 illustrates this for 1991 mill operations. This was the starting point for the work described in this paper.

Jan 1, 1992

By V. F. Hollister

Epithermal gold deposits occur in and near the marginal fault that circumscribes the Goldfield, Nevada, Tertiary caldera. The gold occurs disseminated in alunite, pyrite, and kaolin- bearing silicified zones that are controlled by the circular faults. Other Tertiary calderas (i.e., Summitville and Red Mountain No. 3) have epithermal disseminated gold deposits located in and near their marginal circular faults in settings that resemble the Goldfield example. These additional caldera- controlled epithermal gold deposits are also characterized by alunite, pyrite, and kaolin-bearing silicified rock that act as hosts for the gold disseminations. The Goldfield District is therefore an exploration model for those seeking disseminated epithermal gold deposits in a caldera setting.

Jan 1, 1986

By H. Pieterse, K. S. Fraser, J. R. Goode

The Goldstrike autoclave plant is designed for the pressure oxidation of 1363 t/d (1500 stpd) of refractory gold ore. The plant was commissioned in early February 1990 over a one week period - an unusually short period for a plant of this complexity. The rapid plant start-up is attributed to certain detailed design and control aspects of the plant. This paper discusses key features of the autoclave plant with emphasis on the design of the splash/flash system of heat recovery and the control systems. Commissioning and plant operations over the first three months are reviewed.

Jan 1, 1990

By Allan J. Breitenbach

Heap leach operations provide a low-cost method for recovering gold, silver, and copper metals from low grade ore materials. The processed ore materials are stacked in controlled lifts on a lined pad facility for heap leaching. A controlled barren solution is applied to the heap ore surface by sprinkler or drip emitter irrigation, and ore metals are leached into the solution for collection and extraction in plant process facilities. The leach pad and solution collection facilities are lined with impervious materials for containment of all process solutions. The liner system typically includes a composite geomembrane and clayey soil liner with a protective drain cover fill to maximize solution recovery and protect the underlying groundwater conditions. This paper discusses the types of pad liner systems currently used by the mining industry and the "good, bad, and ugly" lessons learned in engineering practice over the last 10 years in the design and construction of heap leach pads.

Jan 1, 1999

By E. A. Metz

Silicon dioxide, silica, is the most common oxide in the earth' s crust. The health effects of silicon dioxide dust have been known since Biblical times. Agricola's book, published in the mid 1500's on occupational medicine, described a lung disease that afflicted miners. He observed a disease in miners that caused shortness of breath, coughing and wasting. Add fever, chest pains and fatigue and we have the current symptom complex of silicosis. As we approached the 21stcentury, the Labor Department began an aggressive campaign to combat silicosis-a preventable disease. Unfortunately, many publications do not clearly differentiate the polymorphs of silica known to mineralogists. Crystalline silica, i.e., alpha quartz, tridymite and cristobalite need to be considered differently from the amorphous forms of silica. Freshly fractured surfaces of the silica and host specific responses will be examined. Recent research focuses on the biologic interactions of free radicals generated by mineral particles. This results in cell injury and DNA damage, in turn leading to fibrogenesis and possibly carcinogenesis. In addition to particle-cell interactions, emphasis is given to lung defense mechanisms.

Jan 1, 1998

By Daniel H. Isreal

Because the federal government owns and controls nearly 80% of the most valuable oil shale reserves in the West, it is inevitable that federal leasing and siting will play a prominent role in development of an oil shale industry during the 1980s. Also, because of recent enactment of the Synthetic Fuels Corp. authorizing up to $88 billion in loan and price guarantees-federal financing will provide the critical incentive to permit private investment in a still infant industry.

Jan 1, 1981

By R. L. Bullock

For the past 30 years there has been a gradual evolution of mechanical excavating systems in underground hard rock mining applications. This paper traces many of the tests of various tools and methods to break hard rock, up to the present. The tools include impact hammers, boring machines, disc on boom mining machines, disc on revolving wheels and drums, picks and drag bits on revolving hubs, rock splitters, slot cutting systems, and with customized explosives/powder mini-blasting. While the progress has been slow, successes are being achieved in hard rock and more opportunities exist today than ever before.

Jan 1, 1995

By C. O. Lee

The Grand Isle Sulphur Mine is located in the Gulf of Mexico, approximately seven miles off the coast of Grand Isle, Jefferson Parish, Louisiana. The depth of water at this location is about 50 feet. The deposit is on acreage covered by oil, gas, and mineral leases which were originally issued in favor of Humble Oil & Refining Company by the State of Louisiana, and which were continued, maintained, and redesignated by the Department of the Interior of the United States, pursuant to Section 6(b) of the Outer Continental Shelf Lands Act. On September 19, 1956, Freeport Sulphur Company acquired from Humble Oil & Refining Company the sulphur rights underlying the tracts. This assignment was approved by the Secretary of the Interior on July 12, 1957. The Director, United States Geological Survey, approved Freeport Sulphur Company as Operator on July 31, 1957. Actual design began in September 1956; the first structural contract was let December 15, 1957, and offshore erection began in June 1958. The initial phase of construction will be completed and production started in early 1960. The estimated total cost of the project is $30,- 000,000, of which $8,000,000 is the extra cost for being in the Gulf of Mexico.

Jan 1, 1959

By Jonas Svensson

The Grangcold Pellet Process - for which patents have been applied or already granted in a number of countries - uses a hydraulic adhesive such as Portland cement, slag cements, pozzolanic cements, etc., for the production of cold bonded pellets. The idea of using a hydraulic binder for the agglomeration of iron ore fines is not new. Portland cement was proposed as an adhesive for cold bonded iron ore briquettes in patents granted more than 50 years ago (1). In a report on the briquetting of iron ore fines, published in Stahl and Eisen 1959 (2), it is stated that briquettes bonded with Portland cement are used on a small scale at on ironwork in Germany. According to the report, the briquettes showed excellent strength in the blast furnace although their general use was made impossible because they required a long hardening time, during which they are sticky, soft and difficult to store and handle. The Grangcold Pellet "recess has overcome this particular disadvantage by mixing the balls with a suitable amount of the balling concentrate before storing them. The pellets are embedded in the concentrate during storing in such a way that they are isolated from each other and thus prevented from sticking together to form clusters. Thanks to the embedding concentrate, the pellets are subjected to a more or less uniform pressure from all sides which does not deform them. Thus the mixture can he stored in a stockpile or in a silo until the pellets have hardened sufficiently. The concentrate is separated from the pellets by means of screening. The concentrate is returned to the balling operation and the pellets are either shipped to the blast furnace or stored for final hardening.

Jan 1, 1969

By R. J. Hickson

The Grasberg copper-gold deposit was discovered in Spring 1988, just one year prior to the planned closure of Freeport Indonesia's original Ertsberg open pit copper mine. In spite of Grasberg's remote location, 600m above the Ertsberg, atop a hitherto inaccessible mountain, Freeport-McMoRan brought their latest open pit mine into production in the last week of 1989, less than two years after discovery. This paper describes the start-up of the operation, highlighting synergies drawn from both the original Ertsberg experiences and the current Freeport Indonesia underground mines.

Jan 1, 1991

By D. W. Rierson

Svedala has a ported kiln process, designed specifically for the direct reduction of pelletized or natural lump iron ores. The process is called ACCAR. This ported kiln technology has been coupled with Svedala's GRATE-KILN System, for iron ore pelletizing, into the GRATE-CAR System for the reduction of fine grained ore concentrates through the steps of agglomeration, induration and reduction in a single production line. Additional applications of the GRATE-CAR System include: the recovery, agglomeration and reduction of steelmill waste oxide fines and the use of minus 6mm size natural lump ores to produce a highly metallized pellet agglomerate. Svedala conducts tests to confirm certain operating parameters through process simulations of the GRATE-CAR process. These tests are conducted at Svedala's Process Research and Test Center, Oak Creek, Wisconsin. Svedala also assesses issues of process variables, heat transfer, equipment sizing, retention time and endothermic demand associated with iron ore reduction using natural gas or coal as the reductant. The purpose of this paper is to present the GRATE-CAR processing concepts, the commercial production line and the testing procedures associated with investigating potential raw materials.

Jan 1, 1997

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 C. Pitzer

"Safety performance in many companies and even industries has stalled in the last decade. Accidents rates are at a “plateau” and yet, serious accidents and fatality rates are not. In more dramatic cases, such as in the BP Texas Refinery disaster, organizations that have “exemplary” safety statistics, suddenly have a catastrophic or multi-fatality event occurring. Classic examples are the Piper Alpha disaster and NASA’s Challenger and Columbia disasters, the BP’s Deepwater Horizon Rig disaster in the Gulf of Mexico. Looking into the causes of these accidents provides an insight into the events and deficiencies that led up to the accident, but what are the common features in the organization’s mindset, or its culture? What characterizes these organizations’ decision-making, their approach to safety and to risk and are there features that can be delineated? The research and review presented in this paper covers a period since1995, which started in the Australian resource industry and since then covered international events. The features of these organizations are summarized as the seven deadly delusions of near zero organizations (NZO) that suffered unexpected disasters, based on extensive research by the author. More recently, the massive West Fertilizer plant explosion in Texas, and the Train Disaster in Lac-Mégantic, Quebec, Canada underlined the same trends. Organizations may experience calamities not because they are bad, or unsafe, but because they have become “cult-like”. INTRODUCTION The train disaster of 6 July 2013, in the small town of Lac-Mégantic in Quebec, Canada, in which 47 people were killed, had many strange pre-cursorsso-called “black swan” events that have occurred in many different industries. Black swan events are so rare, that there is almost zero chance that they will ever occur again, but they are so calamitous that the responses to these are emotional and irrational, (but necessary) and in those responses, the seeds for other, different black swan events are put into place. It is not what we don’t do, or do wrong, that causes modern disasters, it is what we do. The same things in the culture that make us successful, may also cause the disasters. We slowly, incrementally and insidiously ‘float’ into disaster. One such Black Swan event: The Piper Alpha Oil Rig disaster, killing 167 men in the North Sea on the 6 September 1988, was one of the most pivotal events in safety around the world. It changed the thinking and focus of governments, whole industries and led to numerous books and papers. It resulted in new legislation, textbooks and a critical self-examination by the oil and gas industry."

Jan 1, 2016

By Jim Clark

Tunnel boring machine (TBM) tunneling is an ever-increasing prospect for underground construction, and, with each new tunnel bored, there are unknown elements. When boring through the earth, even extensive geotechnical baseline reports can miss fault lines, water inflows, squeezing ground, rock bursting and other types of extreme conditions. This article draws on the consider-able field service experience within Robbins to analyze successful methods of dealing with the most challenging conditions encountered. Many tunnel projects are located in areas with relatively poor access along the tunnel alignment and bored under extremely high overburden. These two factors often result in limited geological information. It would be reason-able to state that the deeper the tunnel, the greater the lev-el of uncertainties. When faced with these uncertainties everyone involved with the project including the owner, the contractor and the machine supplier must be prepared to tackle geological surprises. This article describes the problematic geological conditions and associated difficulties faced on three separate projects and the measures that were taken to overcome these difficulties.

By K. G. Tsakalakis

The Greek Cement Industry is a vital sector of our economy. With an annual production of cement over 15.5 million tonnes, it contributes significantly to the national gross domestic product (G.D.P.). The cement industry, as other mineralogical transformation process industries (lime, glass, ceramics, extractive metallurgy etc.), is high energy intensive. Each tonne of cement produced requires not only large amounts of fuels (coal, fuel oil), but additionally a significant quantity of electrical power as well. All fuels consumed by the Greek Cement Industry are imported and energy accounts for one third of the cement production cost. Therefore, it is of interest of the community and the industry to increase energy efficiency, to reduce the quantities of fuels consumed in the cement manufacturing process. It is also known that like almost all manufacturing processes, the cement industry produces large amounts of CO2 (combustion of fuels, de-carbonization of limestone and use to electricity). The utilization of wastes (principally as alternative fuels, scrap tires, spent solvents etc.) is compatible with the general principles of waste management and it is also a common practice in other European and developed countries. In the present paper the economic, social and environmental benefits provided by the recycle process of the various wastes in the Greek cement plants are extensively analyzed. From the whole work, it was concluded that such a practice: - replaces a significant percentage of imported fossil fuels in the cement manufacturing process, - maximizes the recovery of energy and also ensures their safe disposal, - produces overall environmental benefits by reducing releases to air, water and land, - prevents resource depletion of valuable non-renewable fossil fuels, - overcomes the need for the construction of dedicated incineration facilities, - contributes positively to the principles of the sustainable development.

Jan 1, 2003