Search Documents

By Earl T. Hayes

[This work represents a continuation of the efforts of the Metallurgical Division of the Bureau of Mines to ascertain and apply knowledge of mineral physics to process metallurgy.]

Jan 1, 1941

Historically, the selection of mining sequence for multiple seam conditions has been based on many factors other than ground control considerations and minimization of interaction effects. Today, numerous operations are finding themselves mining above existing or abandoned operations, some of which exhibit large scale caving, pressure arches and subsidence troughs. Development of design criteria for the upper seam that would alleviate damage due to lower seam interaction effects can contribute substantially to the safety and productivity of many mining operations. The primary objective of this re search has been to identify methods of improving ground control conditions in the upper seam when mining through either passive or active subsidence waves. These methods concentrate on improved ground control practices for the upper seam, rather than reducing the amount of subsidence in the upper seams by improved practices in the lower seam. Design factors such as pillar size, pillar and opening orientation relative to the subsidence trough, offsetting intersections, and different support methods have been studied for the upper seam in a variety of typical geologic environments. Analysis has demonstrated criteria for ameliorating negative interaction effects and facillitating design in the superincumbent seam.

Jan 1, 1986

By Christopher J. Vise

Although production operations at mines, representing the extraction and removal of the mined material, often appear to receive the greatest amount of attention, the emphasis given to auxiliary operations is continually increasing. This is due to the changing economic, social, and environmental climate in which modern mines must operate. Auxiliary operations can best be described as those activities that are not directly related to the extraction and removal of the mined material, but must receive proper attention if recovery is to take place in a safe, efficient, and socially responsible manner. In fact, certain mining auxiliary operations, such as strata control and ventilation, are considered to be of such importance that they warrant separate sections in this Handbook. Judging from a mine-personnel standpoint, it is not uncommon for a mine to hire the same number or more individuals responsible for auxiliary operations as the number assigned to production.

Jan 1, 2008

By D. Schreuder

Conditions in the South African market relating to atmospheric emission control has changed dramatically over the last 10 years. Companies have become more responsible, environmentally aware, and have to comply to more stringent environmental limits set by legislation. This paper describes briefly the current best available atmospheric pollution abatement technologies relating to particulates, acid gases, NOx, acid mists, aerosols, mercury, dioxins and furans. Mention is also made as to the best practices for product work-up and waste product disposal.

Jan 1, 2006

By V. Svalbonas

When the Trelleborg Divisions of Boliden Allis and Mineral Processing Systems (MPSI) merged, a unique opportunity occurred for two independent mill fabricators to compare design pro¬cedures and the research upon which they were based. Several semiautogenuous (SAG) mill analyses are compared using Boliden Allis and MPSI methods. The differences and similarities are then used in a correlation of critical stress definitions and the acceptable design and inspection criteria. Given the opportunity to compare the total philosophies and methods of several companies involved in the design and fabrication of grinding mills, it was important to first develop the comparison method and ground rules. One option was to compare analytical methods by details such as numerical techniques and accuracies. However, this option was discarded in favor of a more general approach. The question that was finally posed was in two parts. Given an identical mill requirement: • What would be the difference in the analytical design result, and to what aspect of the analytical process could this difference be attributed? • What would be the difference in approaches to obtaining the final hardware in subcontracting, both in specifying and Quality Assurance surveillance? By using this comparative approach, questions of relative conservativeness and reliability would automatically be answered.

Jan 1, 1992

The Ekati Diamond Mine is located on permafrost terrain in CanadaÆs Northwest Territories. The mine rock consists of: diamond-bearing and barren kimberlite; and surrounding waste rock such as granite. The kimberlite occurs in several vertical æpipesÆ that are, or will be, mined using open pits. Early predictions of drainage chemistry at Ekati identified the potential for ARD due to sulfide oxidation from both waste rock and kimberlite. This was surprising for the kimberlite, because neutralisation potentials (NP) are typically hundreds of kg CaCO3 equivalent/t. However, subsequent testwork showed that substantial portions of the NP ædisappearedÆ quickly, apparently due to the unusual non-carbonate mineralogy. In any case, additional predictive work concluded much of the rock was benign and there would be no ARD. Shortly after mining started, ARD appeared from both the waste rock and kimberlite, although a few years passed before the company and its consultants recognised that at least some of the acidic water was ARD. Numerous other processes have been put forward as possible explanations for the remaining acidic drainage, although none have been either confirmed or eliminated. Because: the causes of the ARD and acidity are not known; no causes have been eliminated and more have been added; drainage chemistry was not predicted accurately; and future mining will encounter similar rock. I believe the Ekati Diamond Mine needs high-level assistance to understand current chemistry and to avoid problems with future drainage. Organisations like INAP, MEND3, and universities could provide this assistance.

Jan 1, 2003

It has been proven theoretically and experimentally that the use of 10 - 30 per cent DRI in blast furnace along with iron ore or sinter results in lower coke rate and higher productivity. However, to-date this remains unpractised on a regular basis mainly because of economic reasons. The DRI produced by several methods are expensive and difficult to store/handle in large quantities because of its reactive nature and thus DRI in blast furnace remains unacceptable.

Jan 1, 1999

By M. D. Balen

The U. S. Bureau of Mines has undertaken the development of mineral industry cost escalation factors to enable the estimation of mineral development and extraction costs for mineralized sites in Alaska throught the use of the Bureau's Cost Estimating System v2.0 (CES 2.0). For the purposes of this document, all calculations are based on, and reflect the economic environment in Alaska in July 1992. The greater cost of mining in Alaska as compared to the contiguous-48 States can be estimated for Alaskan mining operations through (1 ) the analysis of capital and operating costs for analogous mine and mill plants in operation in the contiguous-48 States; (2) the hypothetical relocation of mine and mill plants from their actual location(s) to Alaska by making engineering modifications to the mine and mill plant design as required by the Alaskan site characteristics; (3) calculation of the cost of the required engineering modifications and; (4) the escalation of all costs to a level representative of the economic environment in Alaska at some specific point in time.

Jan 1, 2011

By V. S. S. Yadavalli, J. Hager, R. Webber-Youngman

"This article investigates the complex problem of a budgeting process for a large mining operation. Strict adherence to budget infers that financial results align with goals. In reality, the budget is not a predetermined entity but emerges as the sum of the enterprise’s operational plans. These are highly interdependent, being influenced by unforeseeable events and operational decision-making.Limitations of stochastic simulations, normally applied in the project environment but not in budgeting, are examined and a model enabling their application is proposed. A better understanding of budget failure in large mines emerges, showing that the budget should be viewed as a probability distribution rather than a single deterministic value.The strength of the model application lies with the combining of stochastic simulation, probability theory, financial budgeting, and practical scheduling to predict budget achievement, reflected as a probability distribution. The principal finding is the interpretation of the risk associated with, and constraints pertaining to, the budget.The model utilizes a four-dimensional (space and time) schedule, linking key drivers through activity-based costing to the budget. It offers a highly expressive account of deduction regarding fund application for budget achievement, emphasizing that ’it is better to be approximately right than precisely wrong’."

Jan 1, 2015

THE Synthetic Liquid Fuels Act (30 U.S.C., 321-325, and amendments) became law April 5, 1944, and a period of intensive research and development in this field was begun by the Federal Bureau of Mines. As part of this program, bulletins were published on pressure hydrogenation,3 the Fischer-Tropsch synthesis,4 and nil stifle.5 The. Bureau also has published a short bibliography on coal gasification,6 mostly of a theoretical nature. Because anal gasification is prerequisite to either the Fischer-Tropsch or coal-hydrogenation processes, publishing this sizable collection of technical information in this form Will Ire valuable. The material will he presented in three parts. as follows I. United Stares Patents. II. United Kingdom, Australian, Canadian, and South African Patents. III. Other Foreign Patents. Part I appeared in early 1960. Part II follows.

Jan 1, 1962

By Walter R. Storms

"INTRODUCTION The New Mexico potash exploration described herein was begun in February 1944 with the object of determining the amount of potash ore in the United States Potash Reserve in Eddy County by exploring the deposit from the surface with vertical drill holes. The work was completed in October of the same year after 16 holes had been drilled on the Reserve and in the immediate vicinity.The Potash Reserve is in secs. 26; 27, 34, and 35, T. 20 S., R. 29 E., Eddy County, N. Mex., about 14 miles northeast of Carlsbad, as shown on figures 1 and 1A, Drilling was done in secs. 26 and 35 of the Reserve, in section 14 to the north, end sections 2 and 56 to the east. All work was done on Governnent-owned, unleased land.The Reserve may be reached from Carlsbad by traveling to the north-east by automobile for about 14 miles on the paved U. S. highway 62. This highway passes through the southern part of the Reserve. Other parts may be reached by a State highway that passes along the eastern side of the area, then by poor dirt roads to various drilling sites. A branch of the Santa Fe Railroad also passes across the southern part of the Reserve enroute from Carlsbad to the plant and mine of the Potash Co. of America, a few miles northeast of the project and 22 miles from Carlsbad."

Aug 1, 1947

By James Mackie

The Vancouver Stock Exchange (VSE) has been providing venture capital for start-up companies since 1907. Ninety years' experience in the junior mining industry has enabled the VSE to develop policies and procedures tailored to the unique needs of start-up companies. Policies and procedures applicable to listed companies are documented in the Corporate Finance Services Department "Policy and Procedures Manual." Approximately 50% of the companies listed on the VSE are in the mineral exploration and development business. The largest number are exploring base metal, precious metal or diamond properties. A recent count shows that about 20 companies are exploring industrial mineral or non-metallic deposits. The minerals sought by these companies include limestone, decorative stone, building stone, lava rock, wollastonite, zeolite, garnet and graphite. There are two basic routes to obtaining VSE financing for an industrial mineral property. The owner can either sell an interest in the property to a listed company or form a company and have it listed on the VSE. In each instance, the listed company is responsible for raising funds to develop the property. A typical financing consists of the sale of company securities byway ofeitherprivate placement or prospectus offering.

Jan 1, 2001

By Jean Cayouette

"In 1995, Louvicourt Mine started one of the first paste backfill operations in Canada. From 500,000 tonnes in 1995, the annual paste backfill tonnage produced reached 800,000 tonnes in 1999. The maximum throughput of the surface plant (including binders) is 3,50Ot/d with a final density of 75 to 76% solids which gives a slump of 15 to 17cm. Following the start-up of the paste backfill plant, the backfill strength performance levels were well below the pilot plant’s predictions. The introduction of ferrous slag, laboratory tests on various binder ratios with or without additives, and the desliming of the tailings enabled us to optimize the mix and operation costs. Primary and secondary stopes are filled respectively with a paste containing 4.5% and 2% binders consisting of a mixture of 20% cement and 80% ferrous slag. In certain stopes, the binder ratio may vary from 2 to 7%, but always in a ratio of 80/20. Six years after start-up, or 4.5mt of paste backfill later, this paper discusses the present operation and the major changes that have occurred over the years to optimize both the operation and the paste fill quality.INTRODUCTIONLouvicourt Mine is operated by Aur Resources Inc. which owns 30% of the shares. Its partners are Novicourt Inc. (45%, subsidiary of Noranda Inc.) and Teck Corporation (25%). The mine is located in the north-west part of Quebec, about 600 km north of Montreal and about 25 km east of Val d’Or. The mine commenced commercial production in July 1994."

Jan 1, 2002

By S. Ralph Austin

Emanation coefficients of 950 samples of domestic uranium ore were successfully and rapidly determined with fair precision by modifications of the closed-can, gamma-only assay method, using commercially available or similar equipment. Coefficients range from <1 to 91 percent. Emanation varies considerably within each mine and area, but distinct differences among major mining areas were found, ranging from 7.5 percent for Moss Back Member, Chinle Formation, Southwest Lisbon Valley, Utah, to 56.6 percent for Ft. Union Formation (?), Powder River Basin, Wyoming. Coefficients also vary with (1) uranium mineralogy; (2) radium mineralogy; (3) lithology of host rocks; (4) grain size of uranium and radium minerals; (5) comminution of ore; (6) estimated porosity and permeability; (7) moisture content; (8) ore grade; (9) supposed mobility of deposits; age of deposits is unknown but limited by (10) age of host rocks which shows only doubtful correlation with emanation. Data obtained may be used to evaluate effects of investigated parameters on radon concentration in mines and thus to select efficient control measures. Drill-core emanation data allow estimates of probable radon problems in undeveloped deposits.

Jan 1, 1978

By Matthew E. Meyer

Renovation, rehabilitation, restoration and expansion of existing residential, retail, commercial, hospital facilities and historic structures requires assessment and evaluation of foundation systems of various ages. The concept of demolition and reconstruction in urban areas is often more challenging, costly, and even prohibitive in some cases due to historic regulations. The authors have been involved with numerous projects related to existing foundation assessment and retrofit, including: hotel and hospital expansions, historic Art-Deco hotel renovations and expansions, garage structure expansions, additions to prominent auction houses, casinos, printing facilities; high-rise structure foundation retrofitting; forensic evaluations of existing building and highway structure foundation systems, and marine bulkhead sheeting systems. The use of non-destructive testing techniques, high-strain dynamic load testing, full scale pile cap load testing and 3-D laser scanning technology has proved to be vital in the assessment and evaluation process, as well as design of foundation retrofit alternatives. This paper presents various methods and techniques to facilitate a phased approach for optimization of existing foundations and subsequent re-use of foundation systems. These methods and techniques are illustrated through the author?s experience and selected case histories from projects with varied foundation and geologic conditions.

Jan 1, 2011

By H. M. Chance

STRETCHING from New York southwestwardly to Georgia is a great range of hills and mountains consisting of pre-Palaeozic schists, slates, and gneissic and granitoid rocks, known locally by many different names; in Pennsylvaniaa as the South mountains, the Berkshire or Durham and Reading hills, and in Virginia and farther south as the Blue ridge. To the northwest of this range lies the " Great Valley," underlain by Lower Silurian limestones, and known as the Lehigh valley, Cumberland valley, Shenandoah valley, valley of Eastern Tennessee and Georgia and by other local names, but all these are parts of one valley, geologically and geographically continuous from New Jersey to Georgia. Lying upon and along the northern flank of this range of mountains, and dipping northwestwardly under the limestone of the valley, is the Potsdam formation (Primal or No. 1 of the Pennsylvania Geological Survey), which consists of sandstone or conglomerate overlain by slates. The latter are sometimes arenaceous and occasionally are replaced in part by sandstone. This formation varies from a few feet to several hundred feet in thickness. At the outcrop the slates are completely decomposed, oxidized or disintegrated, forming a belt of clay several hundred feet wide occupying the interval between the outcroppings of the sandstone and limestone. This clay-belt includes a more or less continuous series of iron-ore (brown hematite) deposits, which have been, and still are, extensively worked. The belt is more or less continuously mineralized with iron throughout its length, and hundreds of large deposits of ore have been developed and worked, producing many millions of tons of ore.

Sep 1, 1908

By Hennessy F. L

It is generally recognised that slags are active participants in pyrometallurgical processes, and not merely inert liquids which must be produced. to effect separation of gangue material in smelting, or of impurities in refining. The importance attached to slag-metal reactions in steelmaking is shown by the numerous investigations in this field. However, there are still many important reactions of slags which require explanation. In this paper some new aspects of the reactions of slags will be discussed, as far as possible quantitatively.FREE AND COMBINED OXIDESMetallurgical experience indicates that variations in the composition of slags produce changes in the chemical behaviour of the various components. These variations have been generally ascribed to changes in the proportions of free and combined oxides, i.e., compounds have been assumed to be present in the liquid slag.Considerable support for this view has been adduced from the existence of compounds such as metallic silicates, phosphates, etc., in the solIdified slag. However, this does not imply that such compounds necessarily exist in the molten slag.The most direct evidence as to the nature of molten slag is to be obtained from a study of the liquid state. In...

Jan 1, 1950

By G S. C Murray

Major mining projects are developed with the assistance of lending institutions who provide hundreds of millions of dollars in funding over several years, and of course expect those funds to be returned with interest. Two Australian banks have adopted the Equator Principles, an emerging financial industry benchmark for assessing and managing environmental and social risk in project financing. Project financiers have encountered environmental and social issues that are both complex and challenging, particularly with respect to projects in the emerging markets of Asia-Pacific and elsewhere. There are many recent and historical examples of failures by resource companies to effectively manage their environmental, social, safety and security risks, some of which have caused the project to fail completely, and some of which have caused the temporary cessation of production. These events put the financial institutionsÆ funds at risk through inadequate management capacity and non-compliance adversely affecting the ability of the borrowers to repay the loans. They can also reflect adversely on the reputation of the lending institutions. In assessing these risks, lenders are increasingly looking at the track record of the borrower in its country of origin and in other countries where it operates. Lenders are wary of companies that have one standard for operations in a developed country, where the regulatory environment may tightly control what they do, and another standard for operations in countries where the regulatory regime is perhaps less stringent. Lenders may require environmental and social reviews or audits to be conducted on their behalf by competent third parties prior to a loan being approved, and annually over the life of the relationship. The mining industryÆs concept of the unwritten æsocial licence to operateÆ is highly relevant in relation to the delivery of community benefits that are sustainable post-mine closure. This paper provides examples of recent practices that support financial viability and sustainable development, as well as examples of some failures that have put lenders at risk.

Jan 1, 2007

By M. R. Geer

Information on the performance of coal-cleaning equipment is necessary to provide a basis for evaluating the performance of existing plants and projecting that of new plants. Performance data can contribute greatly to the wise selection and effective use of coal-washing equipment. The Bureau of Mines has published information on the performance of several commercial plants, as well as of some laboratory-scale equipment, 5 (2-9, 11, 12, 17-12, 21-25) from time to time for a number of years. A more intensive program to provide such information for all the principal types of cleaning equipment is underway. The present evaluation of table performance is part of this program.

Jan 1, 1962

By Pelin Altinkaya, Maria Leikola, Jussi Liipo, Mika Haapalainen, Mari Lundström, Eero Kolehmainen

With decreasing ore grades, the tailings of mining operations are becoming of increasing interest as metal-containing secondary raw materials. The objective of the current work was to investigate chloride leaching of gold, copper, cobalt, nickel, and zinc present in the flotation tailings. In the current study, the effect of cupric ion as an oxidant (0–50 g/L) and NaCl (150–250 g/L) on metals extraction was investigated. The other parameters, such as pH (1.8), temperature (95 °C), solid/liquid ratio (25%), oxygen feed rate (1200 mL/min), leaching time (24 h), and stirring rate (950 rpm), were kept constant. Gold dissolution rate was shown to increase with increase in cupric ion concentrations up to 50 g/L. Also, increase in NaCl concentration up to 250 g/L increased gold extraction. Majority of the copper present in the flotation tailings could be dissolved with all the all solutions investigated. The other base metals, cobalt, nickel, and zinc extractions were also shown to increase with increase in the cupric ion and sodium chloride concentration. However, even in the absence of cupric ion addition (t = 72 h, 250 g/L NaCl), the final extraction of Cu, Ni, Zn, Co, and Fe increased up to 98, 93, 83, 76, and 80%, respectively. This shows the power of inherently originating oxidants present in the tailings. Furthermore, the solid analysis of the leach residue indicated that leaching the flotation tailings in pure NaCl may result in partial gold dissolution. The results demonstrate that significant amount of metals present in the tailings could be extracted even with only NaCl as added chemical in the presence of oxygen feed, oxidizing agents originating directly from the raw material. This can provide an advantageous cyanide-free method for extraction of metals from very low-grade tailings with low chemical consumption.