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By J. A. Herbst, L. B. Hales, R. Zaragoza

INTRODUCTION The Control Problem The need for automatic control in flotation plants stems from frequent and randomly occurring disturbances to the feed slurry. Typical disturbances occur in the solids feedrate, the slurry percent sol ids, and the mineralogy and flotability of the gangue and valuable minerals. In plants where semi -autogenous grinding mills (SAG) are used, feedrate changes are very large and changes in feed percent solids of 1m or more are common. Mineralogy changes between valuable minerals are common, as are changes in the host gangue rock. As these changes occur, the operator can attempt to compensate for them by making adjustments to the flotation cell levels, the dosage rates of the collectors and frothers, the pH, and in some cases the aeration rate of the cells. This problem is sometimes complicated by the fact that different sections of the flotation plant will be processing different ore types at the same time. Potential Savings with Control Flotation control brings about savings or plant improvements in two areas; the first is in improved metallurgy and the second is in reagent savings. Improved metallurgy includes increases in the average plant recovery and achieves target concentrate grade level s more consistently. Average recovery increases between 1.0 and 5.0 percentage points have been widely reported (Paakkinen, 1979; Sutherland, 1984). Reagent savings of up to 40 percent have also been reported (Hales, 1985). VARIABLES OF IMPORTANCE Control led, Manipulated, and Disturbance Variables The initial step in the analysis of the flotation control problem is identification of important variables which can affect the efficiency of separation. The efficiency of separation is represented by a group of controlled variables which can quantify the performance of a flotation circuit. This group includes variables such as grade, recovery, tonnage through- put, and circulating loads. The efficiency of separation of a flotation circuit may generally be defined by a grade recovery map, where each point on this map re- presents a set of operating conditions (see Figure 1). However, the combination of operating conditions must be set to operate close to the economic optimum. The group of operating variables which are changed in order to achieve desired circuit performance are called manipulated variables and can be classified into two

Jan 1, 1986

By W. F. Moll

Absorbent clays are products, usually in the form of granules, that can absorb and hold approximately their own weight of liquids while essentially maintaining their size and integrity. They always contain in abundance at least one of three materials: montmorillonite, attapulgite and diatomite. The first two are complex silicates; the last is amorphous silica of biogenic origin. Not all montmorillonites provide the base for an absorbent clay, however. Nevertheless, the silicates in particular, and the diatomite to a lesser degree, have certain molecular properties that give rise to the useful physical properties. Uses Use of absorbent clays is as old as civilization. Numerous references to "fuller's earth" appear in ancient writings, including the Bible. Fuller's earth originally connated a clay that could absorb oil and grease from wool to facilitate cleaning. Robertson (1986) covers the fascinating history in interesting detail. In the modern sense, absorbent clays find application in three principal areas, and a host of minor ones. Industrial floor absorbents, cat litter and agricultural carriers comprise the major uses.

Jan 1, 1986

By John R. Gaines

I am not a member of AIME, and this is my first annual meeting. As a lifelong member of the non-ferrous metals industry I have enjoyed listening today to speakers point with pride and view with alarm the public relations activity or lack thereof in the halls of government, as well as at the grass roots. There is much to be alarmed about, to be sure, but also some accomplish¬ments to be viewed with pride. Other speakers have given a broad overview of our industry's relations with their several publics. I will be specific about two incidents in which The Anaconda Company faced the loss of confidence of a large portion of its publics: the nationalization of our properties in Chile in 1971 and the closing of our under¬ground mines in Butte, which was announced last October. If I have a minute left over, I will speak about our concern for the loss of confidence in business institutions which has been re¬vealed in recent public opinion polls.

Jan 1, 1975

By A. T. Yu

The quest for ore in an open pit is fundamentally an earth moving proposition. This thesis is vividly underscored by the rapidly increasing volume of waste to be removed in newer mines, where in some instances waste to ore ratios have reached as high as 20 to 1. Continuing depletion of high grade reserves, greater demand for raw materials, coupled with ever climbing labor costs, have made the problem still more pronounced and the need for more effective means of earth moving in an open pit even more acute. A conservative approach to the problem has been to upgrade the sizes of conventional earth moving equipment such as shovels and trucks. In many open pits, particularly in the C.S., this has been responsible for the generally down- ward trend of earth moving costs. None the less, the investment costs of these machines are high, and their gigantic engines are seldom fully utilized. Moreover, a large number of operators are required and maintenance remains relatively high. Unfortunately most people have felt that no other viable alternative was in sight within today's technological capabilities.

Jan 1, 1973

By A. Bruynesteyn

I would like to talk to you today about microbiological leaching or, the solubilization of metal values due to the action of Thiobacillus ferrooxidans. Bacterial attack of sulfide minerals has been going on for centuries but only recently was it discovered that the acid and iron often found in coal mine drainage is produced by bacterial action on the iron sulfides in the coals. Not until 1950 was it proven that bacteria were playing a role in the dump leaching of sulfide ores. B. C. Research became involved in microbiological leaching in 1955 while examining mine drainage from the copper-zinc mine at Britannia Beach, north of Vancouver. Since 1955, B.C. Research has maintained a continuous re¬search program on microbiological leaching which, due to its applied nature, was put under industrial sponsorship in 1962. Most of the information pro¬vided in my talk today has been gathered under this sponsored research program and I would like to express our appreciation to the many sponsors who have made our work possible.

Jan 1, 1970

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 Christian F. Baiz

Industrial minerals can have similar financing requirements to those needs of metaliferrous and coal mining projects. Although, one may see many similarities in the fundamentals of the various risks that must be evaluated in lending to any specific project, one of the outstanding differences is the understanding of the many different markets that these industrial minerals represent. There are in excess of 30 principal industrial minerals ranging in terms of annual production from the largest quantity such as sand and gravel, to possibly the smallest quantity of production of a legitimate industrial mineral which may be defined as industrial and rough gem diamond. If we assume that it is necessary to finance independent projects of ore bodies of industrial minerals for development, the financing techniques are similar to the fundamentals that we would use for financing coal projects or metaliferrous deposits. Therefore, let's begin by redefining project financing in the traditional banking or private sector area, and then in the later development of this paper, we will apply these techniques to industrial minerals in general and cite it with several specific examples.

Jan 1, 1982

By Leslie G. McMillion

A field project to develop and demonstrate a method for alleviating problems of highly-mineralized ground water where they occur as isolated zones or pockets in fresh-water aquifers is being conducted in the Ogallala Aquifer of eastern New Mexico by the Robert S. Kerr Water Research Center. Removal of contaminated water is by a large-capacity well and the pumped poor-quality water is used locally for secondary recovery of oil, Benefits of the operation are threefold in that the aquifer is being reclaimed for future fresh water production, contaminated water is being used beneficially, and fresh water which otherwise would have been used for waterflooding is available for other purposes. Ground-water quality in the site has improved markedly after 21 months of operation. Water quality in 15 specially-drilled monitoring wells has returned to the original quality level of the aquifer, and chloride concen¬trations in the pumping well have dropped to half the maximum level recorded thus far. Project results are very favorable and provide guidelines for initiation of similar undertakings in localities where needed.

Jan 1, 1970

By James A. Martin

Evaluation and subsequent development of a quarry in east-central Missouri was based on a general but brief examination of outcrops and core from five (5) test holes. Neither core, outcrops, nor existing quarries in the general area gave any indication of potential major problems. In the third year of operation large areas of collapse rubble, consisting of green shale and large blocks of limestone and sandstone, were encountered. Their size and random distribution resulted in both blasting and quality control problems. By the fourth year of operation, production costs became prohibitive and the site was abandoned. Prior to dismantling the plant a geologic investigation, which included shallow seismic and resistivity surveys, was made of the unmined portion of the lease. The collapse dolines appear to be related to structure and predate development of the modern topography. Surface indications of these features are few. The seismic profiles were especially helpful in plotting their distribution. Geologic relationships and seismic data developed at this site are being related to similar suspect areas in Missouri and have been useful in their evaluation.

Jan 1, 1970

By J. M. Stewart

The incidence of heat stroke in the South African gold mining industry is today small (less than 1 in 10 6 shifts worked). Acclimatization and selection procedures have been developed and applied throughout the industry, underground working conditions have, and are being improved, and personnel are to-day made more aware of heat stress and its consequences than ever before. Although these actions have, over the years, brought about a steady reduction in the incidence of heat stroke (see Figure 1) the small incidence of heat stroke which persists indicates that heat stress is still a problem. This realization provides the stimulus for the work presented in this paper, which has as its primary objective the development of reliable heat stress limits for men working in South African gold mines. [ ] In keeping with recent trends3I4 the approach followed in this paper is based on the physical principles of heat transfer. Detailed studies of heat transfer from humans have been undertaken,5-l1 and certain of the results form an important aspect of this Paper -

Jan 1, 1980

By Yi Luo

Bolting the mine roof is one of the noisiest underground mining operations. The main contribution to the high noise is the drilling of the roof bolt holes, especially in hard rock. A previous research shows that the specific energy consumed in drilling the bolt holes is inversely proportional to the bite depth (i.e., penetration per drill revolution). Less specific energy at a reasonably high bite depth means less energy is wasted in the drilling process to produce heat, bit wear and noise. Therefore, control of drilling operation to achieve a higher bite depth can provide an opportunity to reduce drilling noise from its sources as a proactive noise control approach. In order to explore the feasibility and to develop the proactive technology for reducing drilling noise, drilling tests have been conducted in laboratory settings. The preliminary results show significant reduction in noise dose can be achieved by drilling in medium hard rock at a reasonably high bite depth. This paper presents the findings from the laboratory experimental studies conducted so far.

Jan 1, 2013

By Joseph A. Dos Santos

Developed in 1983, high angle conveyors - HAC®s are proven versatile systems for elevating materials continuously from a lower to an upper level. Such systems may also be used to lower materials continuously. HAC®s have found commer­cial application in widely varying materials (including coal, refuse, coarse ores [-250 mm], hot clinker, municipal sludge, wood chips, gypsum, slag, excavated earth, various grains and RDF), at widely varying throughput rates from 0.27 to 4250 t/h. The conveying profiles have varied widely and elevating heights range from 3.66 m to 175 m. HAC®s have found application in coal, copper and iron mining, and preparation, in municipal waste treatment, rapid transit projects, pulp and paper mills, cement plants and in gold mining. While noting a wide variety of applications in general, the present writing focuses on Newmont Gold's HAC®, near Carlin, Nevada, which elevates very coarse gold ore to the screening plant. Additionally, upcoming HAC® applications in gold mining are discussed and a proposed multi-flight vertical HAC® system from a deep underground mine is described.

Jan 1, 1996

By Philomene Verlaan

The Code for Environmental Management of Marine Mining (the Code) was adopted in 2001 by the International Marine Minerals Society (IMMS) following extensive and wide-ranging consultation, and updated in 2002. The Code provides a framework and benchmarks for development and implementation of an environmental program for a marine exploration or extraction site by marine mining companies, and for stakeholders in governments, NGOs and communities in evaluating actual and proposed applications of environmental programs at marine mining sites. The Code provides for its review by IMMS after five years, with a focus toward possible modifications based on experience with its implementation and in light of developments in the field of marine mining and associated environmental practices, in consultation with the marine mining industry and with other stakeholders at marine mining operations. As the review of the Code is now due, to begin the process, this paper will present an analysis of the Code and initial suggestions for its modification. Keywords: marine mining, marine environment, sustainable development, marine environmental risk management

Jan 1, 2008

By Landy A. Stinnett

Coal mines in the United States are the most productive in the world in terms of efficient labor employment. This is because of an abundance of workable coal beds, large infusions of capital, improved management practices and continuing competitive pressures. The standard unit of measurement for labor productivity is expressed as tons/manshift, although for underground mines, operators often refer to tons per machineshift. Articles written concerning labor productivity generally focus on measurement techniques, safety considerations, application of technology and training. This article will illustrate by example the impact of labor efficiency (or inefficiency) on the ultimate selling price of coal, f.o.b. mine site. During the past several years, the coal industry has seen significant improvement in labor use. Figure 1 shows the trends in productivity for all active mines in the United States from 1985 through 1994. Productivity in 1985 was 20.1 t/manshift (22.1 st/ manshift). This factor has increased almost linearly throughout that period to 37.5 t/manshift (41.2 st/manshift). This is a 7.2% annual compound growth rate.

Jan 1, 1995

By Robert F. Jones

INTRODUCTION Upflow Solids Contact Clarification is a process long employed in the treatment of potable water, wastewater and municipal sewage. This process incorporated in a fiberglass conical structure seems to offer an economical solution to problems encountered in reduction of particulates in uranium effuents. CONCEPT OF UPFLOW CLARIFICATION Use of suspended solids contact units date back to the 1930's. These types of units produced by Infilco and the Permutit Company, among others, were used in the Lime-Soda softening process to precipitate calcium and magnesium salts from hard water. In general, the process operated as follows: (a) Raw water entered a central chamber where it was mixed with chemicals. The chamber had provisions for agitating and circulating the chemicals so that mixing and reaction zones were formed. (b) The water, precipitated chemicals, floc and turbidity flows to a clarification chamber (the Permutit precipitator used a truncated cone). In most cases the influent then passes upward through a blanket of suspended floc and other solids before it leaves the chamber at effluent weirs or launders.

Jan 1, 1984

By W. R. Dengler

In Canada, most of the rock being broken in underground metal mines is being done by using traditional drilling and blasting methods. Despite advances being made in hardrock boring and other, more exotic techniques, Dynatec believes that the traditional methods will prevail for many years. It is also believed that modest research efforts expended on the traditional methods will result in substantial financial benefits to the mining and rock tunneling businesses. Dynatec has pursued productivity improvements through the use of long rounds in shaft sinking and lateral development. The concept of longer rounds was developed by Dynatec on the Craig Shaft Sinking Project (RETC, 1991). This technology was subsequently used to sink the two shafts at Aur Resources with great success. The development of a Long Round Jumbo for tunneling is a natural progression of the long round technology developed for the Craig Shaft. The Dynatec Long Round System has been patented in the United States and South Africa, with additional patent applications pending in Canada and Australia.

Jan 1, 1993

By Bill Reid

Coal companies mining the seams in the Appalachian region appear to be optimistic. Although some older mines are closing, newer mines are expanding. Money is being spent on new equipment and research to increase mining productivity, as well as improve safety. Coal has been produced from the rich Appalachian seams for about 200 years with no end in sight. Many equipment manufacturers have substantial backlogs of orders for new equipment. Some of the innovations being monitored by the Appalachian underground coal operators include au¬tomated longwall mining, continuous haulage systems and methane drainage. Appalachian coal was a major ingredient in the steel that culminated in the Golden Spike ceremony at Promontary Point, UT, where the final link in the transcontinental railroad was closed. This occurred on May 10, 1869, according to a history published by Union Pacific Coal Co. It stated that "rails and fastenings for track construction were purchased in Danville, Scranton, and Johnstown, PA and Troy, NY." Ever since, coal from the eight Appalachian states has contributed in no small measure to geographic expansion and economic growth of the United States.

Jan 1, 1995

By Annan Cook

Cyprus Metals' Sierrita mine is located in the Pima Mining District, Pima County, Arizona (Fig. 1), which is one of the largest known porphyry copper districts. The ore body is part of a large mineralized system that includes Cyprus' adjoining Esperanza mine. The copper and molybdenum grades being mined at Sierrita make it one of the two lowest grade porphyry copper mines in the world Mineral production from the district was first recorded in 1876. Copper from replacement deposits in carbonate rocks and copper¬-lead-zinc from veins in volcanic rocks were mined from several deposits. However, it was not until 1957 that the district commenced to become a major copper producer with the beginning of production from the Pima mine, which was the first open pit operation. Since that time, seven other open pit mines have come into production. Because of the variable copper prices and high operating costs, not all of the mines are operating today. A map of certain outcrops, plutons, and open pits, as well as older underground mining operations, in the Pima district is shown in Fig. 2.

Jan 1, 1991

By Ronald B. Gabitzsch, Norbert P. Hanke

During 1982, record advances have been achieved in the excavation of vertical shafts with a V-Mole (a vertical shaft boring machine). The V-Mole, supplied by Wirth GmbH in Erkelenz, West Germany, has been used in West German coal mines since the early seventies, mainly for the construction of internal shafts. In 1981, it was brought into the United States for the construction of a series of ventilation shafts with depths varying between 512 m (1680 ft.) and 622 m (2040 ft.) excavated to 7.0 m (23 ft.) diameter. These shafts were needed for the development of coal mines for Jim Walter Resources, Inc. in Brookwood, Alabama. After a description of the mechanized shaft excavation system with the V-Mole, the conditions and parameters, such as ground, shaft dimensions, and linings are discussed. These factors are important considerations for a technically and economically feasible utilization of the V-Mole. In addition, the advantages and disadvantages of using the V-Mole technology in comparison to other shaft construction methods are evaluated.

Jan 1, 1983

By Osamu Shoji, Mamoru Kato

In order to continue improving the quality of telecommunication services to meet the expectations of the people and to increase reliability in the case of emergency such as disasters, Nippon Telegraph and Telephone Public Corporation (NTT) is now constructing cable tunnels which connect main urban telephone offices. However, almost all the large cities in Japan are built in river deltas, so that their chief underground features are low strength fluvial deposit and a high ground water level. In this saturated soft ground, the ground surface at an installation site has occasionally subsided through deep excavations for cable tunneling construction. As these settlements have sometimes caused accidents, especially in densely populated large cities, NTT has made much effort to avoid such accidents. These accidents have occured mainly in flexible sheeting due to its inward movement. Therefore, after the investigation into forecast method of sheeting deflection with accuracy, NTT has reserched a system which forecasts ground surface settlements. This paper describes an outline of the ground settlement forecast system and practical example on the site.

Jan 1, 1979