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By Richard Klimpel

The laboratory ball mill grinding of coal/water slurries is described for three coals. Emphasis is placed on the measurement of specific rates of breakage for various operating conditions. Corresponding rheological information is also presented based on data collected using a rotational viscometer. A rheological explanation of the influence of various slurry fluidity conditions on the specific rates of breakage is presented. This rheological approach has proved useful In both the identification of suitable chemicals for increasing breakage rates in coal/mineral slurry grinding and in the plant scale implementation of dense slurry grinding systems.

Jan 1, 1982

By Francois E. Heuze

This paper summarizes the geomechanics programs conducted in two hard rock underground mining operations in the Western United States, between 1966 and 1981. The two projects were directed towards understanding the behavior of the rock masses, at the scale of the caverns. To this end, the emphasis was put on large scale field measurements, complemented by limited laboratory testing. The results of these observations were used to build realistic finite element models of the underground chambers. In the marble mine, at Crestmore, California, the models were applied to the structural optimization of the room-and-pillar pattern. In the granite mining, at Climax, Nevada Test Site, the models explained some unusual stress changes observed during excavation. Based on the large number of geomechanical techniques employed, specific conclusions and recommendations are offered regarding the quality, applicability, and usefulness of the various methods. The two case histories clearly indicate chat numerical models are extremely useful for a detailed understanding of the structural behavior of mine openings. To be realistic, these models must be based first and foremost on large scale field observations. The lessons Learned on these two projects also are directly applicable to the design and analysis of nuclear waste repositories in hard rocks such as basalt, granite, and welded tuff.

Jan 1, 1982

By Harold J. Schock

This paper describes an experimental method for the monitoring of diesel-generated exhaust gas pollutants in a dead-ended drift for the purpose of assessing the effect of control approaches. Experiments were conducted to determine the relative merits of these ventilation configurations: no auxiliary ventilation, induction ventilation at the entrance to the drift, and ventilation of the dead-ended drift with positive displacement tubing. The drift used in this experimental work was approximately 105 ft. (32.0 mf long and slightly downsloping, with an average height and width of 8 ft. (2.4 m) and 28 ft. (8.5 m1 , respectively. The data were gathered for assessing these ventilation methods and for gathering data to support a computer model of the dispersion and mixing processes. For this drift, it was found that ventilation with positive displacement tubing provided the best removal of diesel-generated pollutants. Induction ventilation appeared to be the least effective of the three methods examined. A comparison was also made between personal monitoring and area monitoring. Results of this analysis showed that in regions of high concentration gradients, it was not possible to get good agreement between point sampling and personal monitoring. In well-mixed areas, good agreement between the two methods of monitoring was obtained.

Jan 1, 1980

By L. Nahai

In an exchange of views with the Program Chairman for the Technical Session on Industrial Minerals and Investment in Foreign Countries, it was agreed that it would be more interesting to approach the problem of mineral investment in foreign countries in a more general framework and not confine it to industrial minerals. Therefore, this Bureau of Mines report is proposed to examine current attitudes toward investments in foreign mineral resources and restraints that they impose on investments necessary to assure supply for future global mineral needs.

Jan 1, 1976

By Michael E. Berndt

Asbestos first became an issue to Minnesota?s iron industry when it was revealed that mineral fibers similar to those in Reserve Mining?s tailings were being found in drinking water for several communities that used Lake Superior as their primary water source. This discovery turned what had largely been an environmental court battle into a case concerning public health. The courts listened to much conflicting and uncertain scientific testimony on the size and distribution of the mineral fibers and on the potential health effects imposed by them. In April 1974, the plant was ordered to shut down by a federal judge but the company quickly appealed the decision. The appeals court granted a stay and ultimately ruled that the plant?s closure could not be justified based on the unknown health effects of the mineral fibers since the consequences of such an action would have immediate and severe social and economic impacts. The plant was allowed to continue operation, but ordered to abate emissions to air around the plant and to switch to a land-based tailings disposal system. Much of the scientific uncertainty and public concern over mineral fibers in Minnesota?s taconite industry remain today. ©2007 Elsevier Inc. All rights reserved. Keywords: Minnesota; Iron ore; Taconite; Asbestos; Amphibole; Reserve Mining; Tailings; Mesabi Iron Range

Jan 1, 2007

By Neil A. Brown

The trona deposits near Green River, in southwestern Wyoming are world class in size and quality. They contain more than 25 times the reserves of the next largest trona deposit at Lake Magadi in Kenya. Based on present rates of production, the Green River reserve should last for more than 500 years. Since their discovery in 1938, the Union Pacific Corp. has been instrumental in the promotion, development and production of soda ash in Wyoming. Union Pacific spent several years drilling the deposits and trying to promote them to chemical companies. In 1947, Westvaco and Union Pacific entered into what became the first trona lease agreement. Today, the Green River Basin leads the world in soda ash production, accounting for about 25% of the world's supply. Green River producers process more than 14.5 Mt/a (16 million stpy) of trona to produce more than 8 Mt/a (9 million stpy) of soda ash. The future for Green River soda ash looks good, with more of the world looking towards the cheaper and higher quality source of soda ash coming from the natural deposits. Production from the Green River deposits should continue to grow as trade barriers and tariffs begin to fall in Europe and energy and environmental costs force the synthetic producers to exit the market.

Jan 1, 1995

By R. J. Robbins

The mechanization of hard rock underground mines offers a large potential for reducing cost, improving efficiency, and increasing profitability. However, in spite of serious efforts by quite a number of equipment developers and mining company initiatives, the industry has achieved little real progress. The task is difficult and the blasting alternative to mechanical excavation is an effective and well-developed method, which continues to improve in spite of its inherent limitations. A large number of machines have been built and tried. Only a few developments have succeeded to make a major impact on underground hard rock mining. It is certain that hard rock mines would be laid out and designed quite differently if the mining engineers knew they had available continuous mechanical excavation machines. In the absence of the machines, mines will be designed for excavation by traditional methods. It is not easy to utilize mechanical excavation in a mine which is designed to operate with normal drill and blast excavation. This is certainly an impediment to machine development. But what if an ore body cannot be mined conventionally, simply because the mining company cannot get permits to satisfy the ever increasing strict EIS requirements of the general public and governmental agencies? This may provide the incentive necessary to develop the equipment that will be needed by a new mining method that will have almost no impact on the environment.

Jan 1, 2001

By Ray Wood, Rene Sterk, Robin Falconer, Sean Aldrich, Simon Nielsen

"The Chatham Rock Phosphorite project is situated 450 km east of New Zealand at approximately 350 to 450 m water depth. The deposit occurs as a thin layer of phosphatebearing glauconitic sand at the surface of the sea floor and has a thicknesses typically ranging from 0 to 1 m. The sand layer consists of mainly silt and sand-sized sediments, with phosphatised chalk nodules up to 15 cm in diameter. Phosphate nodules were first discovered on the Chatham Rise in the 1950s by a New Zealand Government survey. During the 1960s to 1980s several private and government sponsored cruises explored the Chatham Rise and surrounding seafloor area. A total of 1174 samples were collected over a 600 km2 area with the majority of the samples collected using a pneumatic -or large Van Veen-style grab-sampler.Since acquiring the licence in 2010, Chatham Rock Phosphate Limited has conducted six cruises in two programs in the Project area. A total of 261 samples were collected using a Van Veen grab, box core and grab samples.Sample quality and QA/QC measures varied considerably between the cruises and within each cruise. A critical part of the assessment of the data collected in the Project area was to determine what quality thresholds to use to allow or disallow data to enter into the estimation process. As part of the data verification process, the relative and absolute quality of the data was assessed in as much detail as practically possible. The best samples were those that were collected using the pneumatic grab, sampled the full sand horizon, had a small location survey error and had no other apparent data ambiguities. This paper describes the challenges for mineral resource estimation for an unconventional style of mineralisation using unconventional sampling techniques."

Sep 1, 2014

By Wallace N. Thomas

The present interest in large diameter grinding mills and the rapidly rising cost of the drive in proportion to the cost of the mill establishes a need to explore the drive system in detail. The drive for a seven to eight thousand horsepower mill will cost from 1350 thousand to $600 thousand which represents nearly half the total cost of the mill package, and requires as much building space as the mill proper. Some of the drive components require a longer time to manufacture and the installation time and costs are equal to those for the mill. It is apparent that the drive has become a dominant factor in the overall mill design consideration. A new plant requires a tremendous investment in both time and money. With the high degree of competition in the mining industry, low capital cost is an exceedingly important factor in the development of a project. It is just as important, however, to insure that the equipment is going to perform satisfactorily for the anticipated life of the project without adding unplanned operating, maintenance and replacement costs. This is the position in which the engineer or designer usually finds himself and is really one of his primary functions -- establishing a realistic compromise between cost and performance.

Jan 1, 1969

By E. L. Fidler, T. E. Finch

Wayne Anderson Regarding the technical paper by Thomas E. Finch and Edward L. Fidler, "Recovery of Stray (Thin) Seams in Western Coal Mining." I would like to comment on this subject. In western Canada, most strip mines encounter thin seam coal or rider seams. Although the paper addresses the problems and costs associated with the recovery of this coal, it does not take into account what the savings are. Without looking at the savings, the "Total Objective" is of course not clear. I feel that in a stripping operation the mine can spend per ton (of the thin seam) up to their dragline stripping costs per ton to recover a rider seam or thin seam. The reasoning behind this is simply that this is the price the mine will have to pay to expose an equivalent amount of coal without the recovery of these thin seams. If the mine can recover a rider seam or thin seam for less than the dragline operating costs per ton, a savings will be realized. By recovering a thin seam or rider seam, the life of an ore body is extended by that amount of coal not thrown away. In addition, the cost of land acquisition, associated permits, capital, and reclamation will be reduced as more coal is delivered for a given area. When the above points are considered, the recovery of these thin seams can be very profitable and indeed worth recovering.

Jan 11, 1982

By A. Fred Gelding

Introduction In preparing this paper considerable time was spent attempting to find some upbeat data about the mining industry, so those of us in the field could feel somewhat better about future prospects. Much to my regret, I failed to uncover substantial evidence that our near-term or, for that matter, our long-term opportunities appear all that bright in North America. That is certainly not the kind of assessment anyone likes to hear or accept as even a possibility. Those remarks may, on the surface, appear far too pessimistic. This industry will experience a recovery and most likely will see conditions begin to improve later this year or early next. The kind and degree of recovery, however, will more than likely differ from those experienced in the past. Fundamental Changes Clearly, the fundamentals on a world scale of our business have undergone important changes. In recognizing these fundamental changes, mining authorities believe productivity advances are needed to change the direction mining has taken in recent years. The really tough question is whether increases in productivity will be enough to change the course of events that has dominated the mining sector for the past decade. Before one can provide an honest answer, an appraisal of what has and is happening now is necessary. Here are some changes and events that have taken place that effect domestic mining and will probably continue: • Mineral-rich lesser developed countries (LDCs) in Africa, South America, and Asia-Pacific have reached a point where they have developed the needed mining infrastructure to not only produce at a high rate, but in many instances, at a lower cost than fully developed countries. Just as importantly, these countries, even if they do not enjoy lower costs, will produce for world export with government subsidies because min¬ing products are key in obtaining badly needed foreign exchange. • These producing countries also have the distance advantage of lower labor, environmental, and other important regulatory costs. If that were not enough, these same countries have minerals with considerably higher grade ore and, in some cases, much lower cost accessibility. • Exporting North American commodities is impaired by a dollar that continues to strengthen against other important currencies around the world. There are other impediments to overcome, but these represent some of the realities our industry faces. Can those obstacles be overcome through improving productivity? In the past, this industry has offset the impact of these events to a sizeable degree through innovations of mining techniques, equipment and processes, and by increasing the size of its individual operations to reduce costs. Will further enhancements along these lines be enough to alter this changing balance in the future? While there is no answer, it is apparent that if we do not mount a full-scale assault in some key areas, our prospects will not be encouraging. Productivity improvements throughout the entire chain of the mining industry most certainly rates as a high priority. Every link in that chain from mine planning, equipment selections, and transportation considerations needs to be examined and reexamined to assure the lowest effective cost is developed. Quality, while oftentimes costing a little more initially, is still the most cost effective purchasing decision to make. Regulations Another area of concern is regulations, be they environmental or those that dictate what must or must not be done in running our business. Certainly, I do not suggest that we not protect our environment. However, there is an acceptable balance that has, over

Jan 11, 1983

By Raymond J. P. Brouzes

INTRODUCTION [A Decade After the 1972 Stockholm Conference] The UN-sponsored Stockholm Environmental Conference held just over 10 years ago was the first successful attempt to achieve global recognition of environmental issues. Indicative of the lack of concrete involvement in environmental protection to that time was the fact that only 15 nations had a department or ministry responsible for environmental affairs compared to today's 143. Many governments were uncertain of what were the most serious or pressing problems in their country. There was obviously a need to both identify those issues and to determine how to manage them once identified. At the same time, the public at large was becoming more critically aware that environmental protection had been neglected by government and often ignored by industry. It soon became evident that large amounts of money would have to be spent to redress some of the more evident problems. However, many developing nations were reluctant to slow down the much-needed industrial growth by imposing costly environmental controls on industry. In fact, some waived environmental control altogether as an incentive to attract industry. In some sectors, it was often stated that industrial development and environmental protection were mutually exclusive activities. The need of an awareness, commitment and dedication by all sectors of society to protect their environment was just beginning to develop, replacing the rather simplistic view that all environmental problems were caused by greedy industry.

Jan 1, 1984

By Laurel E. Burns

Alaska is in competition with the rest of the world for exploration dollars. Providing a "seed package" of airborne geophysical data for the state's numerous mining districts encourages companies to begin more detailed exploration in more areas than they could have afforded on their own. When data are already available, the initial risk decreases for people involved in exploration. Airborne magnetic and electromagnetic data help ge¬ologists and geophysicists determine what rocks and structures are present under overburden and vegetation. These data form a fundamental package that exploration companies want before intensively exploring most regions. Individual mining companies have conducted their own geophysical surveys during the past several decades. However, these data are not available to other companies. The companies able to afford geophysical surveys have less money for ground exploration after purchasing expensive, private geophysical data. Therefore, they are not able to explore as many places as they might. Additionally, since data are not shared with other exploration companies, the proprietary surveys do not foster intercompany competition to move projects forward. Individual prospectors and small companies can not afford their own geophysical surveys. "It is more often than not the grassroots exploration efforts of the smaller operator that leads to significant discoveries," said Klaus M. Zeitler, senior vice president for development and exploration at Teck Exploration. Acquiring and releasing the geophysical data to the public produces several benefits. The increased explo- [ ]

Jan 1, 1998

By Richard Newcomb

Since the report of the 1972 Rapid Excavation Conference in the city of Chicago, speculation has continued concerning the estimates of tunneling demand. Little has been published that would persuade me to modify substantially the rather tentative estimates that originated with the National Academy of Sciences-National Academy of Engineering (NAS-NAE) study of 1968 which were recomputed by the United States in the survey of the Organization for Economic Cooperation and Development (OECD) in 1970. The OECD estimates, of course, hedged the really difficult question of forecasting civil construction tunneling demands. In the United States contribution, this was done by predicting both an upper and lower bound for important categories of demand. A discounting procedure was then applied to each of the major sectors of expenditures, permitting a forecast that reflected the current subjective assessment of how extensively and how likely cities were to adopt plans that required tunneling. This was done for water, utilities, transportation and other novel underground facilities. The purpose of this paper is a modest one. In it I wish to describe the efforts made since 1972 to generate more thoughtful and more robust estimates of urban sector demands, and to apply what has been learned to the most difficult category of predictions: those for urban mass transit systems. The estimates of the Underground Construction Research Council funded by the National Science Foundation have been described at an earlier panel of this Conference. The principal effort I am familiar with is that of

Jan 1, 1974

By R. V. Ramani

In a 1985 seminar, we were told that overoptimism abounds in Artificial Intelligence (AI), that A1 is neither a science nor a technology yet, and that we will be both exhilarated and disappointed with AI. In fact, even today, there is no single accepted definition of AI; however, certain features have been identified by AI researchers as essential to consider an entity.(e.g: machine or program) to be intelligent. According to Shank (1987), these features include communication (to be able to communicate with), internal knowledge (knowledge about itself), world knowledge (awareness and knowledge about the world outside), intentionality (knowing what one wants and a plan to seek it, ie. goal seeking behavior), and creativity (being adaptable to changing conditions). None of these figures would individually define intelligence; however, each would be a part of intelligence in its own way. The prospects for the development of entities with AI have never been as good as they are now. The combination of advancements in computer hardware and software along with new insights into the ways in which we store knowledge and use it for problem solving has enhanced the potential for the creation of intelligent entities. After some unbounded optimism of a major breakthrough in the fifties and frustrating disappointments in the two following decades, it appears now that AI has emerged from research labs to industrial practice. This is confined by the growing number of repeat applications of AI in business and industry to the extent that AI can now be considered a technology.

Jan 1, 1989

By Harold D. Stevenson, Gerald G. Carlson

The Flow-Through Shares Program was set up by the Canadian Federal Government in 1978. While initial annual expenditures in flow-through shares was small, recognition of flow-through as a significant tax advantage combined with exploration successes, particularly in the gold sector, soon resulted in the majority of exploration dollars raised in Canada utilizing the flow-through share mechanism. What Are Flow-Through Shares As many exploration companies are non-taxable, they are not in a position to benefit from the tax deductions arising out of their exploration activities. Flow-through financing provides a mechanism for the exploration company to transfer these deductions to an investor. In addition to the deductions which an investor can apply against his personal income, the investor receives common shares in the exploration company (flow-through shares). To add to the attraction, the Federal government provides a 33 1/3 percent mark-up on qualifying expenses incurred by the exploration company, giving the investor a deduction of up to $1.33 for every $1.00 invested. By providing the investor with tax deductions in addition to the flow-through shares, flow through shares can often be sold at a premium to market which makes-the mechanism attractive to the exploration company as well. These shares are often sold through private placements and therefore have to be held for one year. The tax cost of the share is deemed to be ril, so the entire proceeds on disposal are

Jan 1, 1987

By K. C. Jordi

Many systems which are modelled mathematically result in a model where the relationships between some or all of the parameters are found to be non-linear. These systems are usually complicated further by a desire to make the system achieve multiple and often conflicting objectives or goals simultaneously. Rozwadowski (1970) developed a model to describe the total discounted net profit of a mine as a function of the amount of ore developed and of the grade of the amount of ore mined. Dynamic programming was used to determine the policy which gave the maximum net present value. In this paper it is shown that the relationships between the variables can be approximated by piecewise linear functions. This is amenable to solution by an algorithm based on the simplex algorithm of linear programming. The goals of maximizing the net present value, the total net profit and the total gold output are incorporated simultaneously into a goal programming formulation of the system. The resulting model is characterized by a large number of disconnected constraints. These are decomposed into several smaller problems and the problem solved. The solution is examined to discover the sensitivity of the system to changes in certain parameters. In particular the interaction between the three goals is analysed to determine whether there is conflict between any of the goals and, if so, what the trade-offs between the conflicting goals are.

Jan 1, 1979

By Dietrich F. C. Hudewentz, Alfred H. F. Lücker

For centuries tunnellers have made use of the experience of miners. In West German coalmining tunnellers have returned the impulses in recent years by giving the miners valuable stimuli with the result that a technology has evolved which benefits drill and blast heading, opens the door to TBM heading and has developed special measures for difficult strata conditions in deep coal mines. WHAT DO THESE ROCK HEADINGS LOOK LIKE? The main roadways dealt with in this paper have crosssections of 20 to 40 m2, big enough to allow the massive airflows needed to aircondition the mines. Because of the difficult strata conditions they have to be supported: in shotfired headings mainly with multi-element arches, in TBM headings with rings of 6 to 6.5 m diameter. In West German coalmining the majority of rock headings are blasted. The proportion of rock headings driven by TBM was 11 % in 1980 and 16 % in 1981, a rising trend expected to continue. Drill and blast headings Drill and blast headings are normally equipped with two or three-boom electro-hydraulic jumbos, electro-hydraulic crawler-mounted loaders with 1.2 m3 shovel capacity, a movable working platform and both chain and belt conveyors for dirt clearance to the minecar loading point. Fans and air-condition plant complete the equipment. Spacing between arches is usually 0.8 m. Investment for this type of mechanisation works out at around 1.3 m DM.

Jan 1, 1983

By G. Mbuyi Kamba

Literature is rather abundant on the topic of steady-state network analysis programs. Many versions exist, some of them have real extended facilities such as full graphical manipulation, fire simulation in motion, etc. These programs are certainly of great help to any ventilation planning and often assist the ventilation engineer in his operational decision making. However, what ever the efficiency of the calculation algorithms might be, their weak point still is the overall validity of the model. This numerical model, apart from maybe the questionable application of some physical laws, depends directly on the quality of the data used to identify its most influencing parameters such as the passive (resistance) or active (fan) characteristic of each of the branches in the network. Considering the non-linear character of the problem and the great number of variables involved, finding the closest numerical model of a real mine ventilation network is without any doubt a very difficult problem. This problem, often referred to as the parameter adjustment problem, is in almost every practical case solved on an experimental and "feeling" basis. Only a few papers put forward a mathematical solution based on a least square approach as the best fit criterion. The aim of this paper is to examine the possibility to apply the well-known simplex method to this problem. The performance of this method and its capability to reach the global optimum which corresponds to the best fit is discussed and compared to that of other methods.

Jan 1, 1995

By John T. Gormley, Pressley L. Campbell, Harry L. Crouse

INTRODUCTION This paper summarizes an investigation conducted to determine the relationship, if any, between reported occurrences of abnormal levels of carbon dioxide (C02) gas and the construction of a 2.44meter diameter main sewer tunnel under South Eighty-Fourth Street, West Allis, Milwaukee, Wisconsin. Specific objectives of the study were to determine: (1) the sources of C02, (2) the significance of each C02 source, (3) how C02 could move to areas where it was reported to occur in abnormal concentrations, and (4) what actions could be implemented to eliminate elevated C02 levels associated with the tunneling operation. To accomplish study objectives, expertise from several scientific and engineering disciplines was required including chemistry, geochemistry, microbiology, hydraulics, and hydrology. Pertinent documents were reviewed and field data pertaining to each aspect of the study were collected as required and examined to evaluate existing conditions. Background On or about February 1, 1971, gas with a composition different from normal atmospheric air was reported to enter basements and wells of residences in the vicinity of South Eighty-Fourth Street, West Allis, Wisconsin. Examination of the gas composition revealed that it possessed an elevated concentration of C02 and a depleted concentration of oxygen (02). Public health officials who investigated the appearance of the objectionable gas concluded within reasonable certainty that the elevated C02 concentrations were associated with the tunnel construction under Eighty-Fourth Street.

Jan 1, 1979