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By A. M. Radigan, W. G. Prast

M.S. Azun The authors' paper did not explain the facts and reasons why state companies are established and what their role is in international industrial mineral trading. Also, I do not agree with the conclusion implying that the main goal for state companies is to capitilize natural resources. Almost all state companies are founded by certain laws and their activities are arranged by state regulations. Their only aim is to operate mineral deposits for their people and to protect the rights of the people. Although some ore deposits, such as nonstrategic or small, may be exploited by privately owned companies, the state has the right to control the operation and production. Activities of state companies may or may not be widened because of the character of the deposits and the importance of the mineral market involved. For some countries, although governments may occasionally change hands, the policy of the mineral trading system is not affected by this change. There is no doubt that any government desires to make more earnings to increase GNP, when it is involved in operating and trading mines. It wants to produce and sell the finished products, instead of unprocessed ones, if possible. When it is known that some mineral deposits are relatively rare, such as Turkish boron deposits, the government can nationalize the mines to control production and affect the market. If there is an abundance of a certain mineral in the market, the government can cut production and set a floor price, such as Canadian potash. Also, when production of a specific mineral is unique, such as Turkish chromite, the price of such mineral may be set by correspondant government. One may add that if some governments with their state companies produce a certain mineral in a larger amount, they may decide to establish a cartel to protect their production and price. These are the facts followed by government-owned state companies and partially government-owned companies. The reason being charge of many deposits by the state companies is always the same: "protect" the mineral rights of the people.

Jan 2, 1984

By Ernest Y. Baafi

This paper describes the results of a series of comparative studies in which polygonal, IDS, and kriging were compared for their local estimation accuracy. The specific objective of this study was to determine the impact that the particular nature of the mineralization has on the results of such comparative studies. The study was performed on simulated coal deposits and the evaluation parameter chosen was the coal thickness. For this study, many conditionally simulated deposits having different degrees of seam thickness continuity were first developed. Each simulated deposit covered an area of 30,000 ft x 30,000 ft which was, in turn, subdivided into 100 mine planning blocks of 3,000 ft x 3,000 ft in size. Thickness estimation was made for these mine planning blocks using surrounding DDH assays. In all cases tested, e.g., from a perfect continuity to a complete lack of continuity in coal seam thickness, kriging gave the best estimates among the three, followed by IDS and polygonal methods. As expected, the relative efficiency (i.e., superiority) of kriging over other estimators was highly dependent on the nature of mineralization.

Jan 1, 1982

By Felicia F. Peng

The plant data were collected from three streams around a dense medium drum for coarse coal cleaning operated at various volumetric ratio of medium-to-feed. The effect of the volumetric ratio of medium-to-feed (MF) and particle sizes on the performance criteria, g50 and Ep, of the dense medium drum. These measured data were adjusted and calculated for the yields and balanced relative density distributions by mass balanced method based on the statistic principle. These balanced data were then used to formulate the mathematical models of the separation distribution curves for the various feed size intervals. The correlation equations for the g50 and Ep as the function of inverse of the feed size, and MF and total throughput were established. A numerical algorithm utilizing the Secant method, based on the root searching principle, was developed for yield optimization and simulation of dense medium drum separation to improve the separation efficiency and hence the product yield. The relationships between the direct ash content and relative density of the particles in feed and the products were established and incorporated into the numerical algorithm for predicting the product quality.

Jan 1, 1996

By R. L. Grayson

Using powerful database management software, nested-field analysis and microanalysis of narratives have been made of West Virginia accident data, resulting in a new approach for targeting and prioritizing safety interventions by county, mine size, specific mine, job title, type injury, etc. and combinations of these parameters. The analyses have been useful in focusing training and discussion sessions on specific work problems, trends, conditions, and situations for targeted groups of miners. Application of the technique will be presented in this paper, along with comparisons of various mine performance measures.

Jan 1, 1997

"The paper treats the spatial aspect of mine sequence optimization. This aspect is revealed in the context of determination of the optimum number of cutbacks of an open pit mine. Cutback mining is a dominating method currently in base\precious metal mining and it is based on a pseudo-economic discretization of the pit space by using advanced pit design algorithms. The result of the implementation of such approach of pit design is the generation of pit shells, which need to be grouped into an optimum number of cutbacks for maximization of the project value. A mathematical solution of this problem is developed with the utilization of a combinatorial analysis. The solution provides a multi-variant investigation of the optimum mine sequence with the implementation of an author’s method for production scheduling optimization, which uses the Net Present Value as a criterion for assessing the economic efficiency of mine sequencing. A case study is provided for the conditions of a hypothetical open pit gold mine to illustrate the applicability of the approach. The results obtained reveal the complex nature of the variation of the Net Present Value as a function of the cutback geometry. INTRODUCTION The mine sequence optimization in open pit mining is a procedure that predetermines the efficiency of the production scheduling optimization. From a technological standpoint, the mine sequence optimization deals with two aspects – spatial and time. Each of them plays a tremendously important role in searching for the optimum solution of the open pit design problem. Original results on the time aspect of mine sequence optimization are published by Halatchev [2002]. They reveal a wide range of the Net Present Value (NPV) variation for a multi-variant arrangement of mine sequence over time and using a fixed geometry of the cutbacks, which determines the economic potential of a single open pit mine from a deterministic standpoint. The results show a range of NPV variation up to 30% depending on the stripping ratio of the mine. The effect of this variation is mainly due to the implementation of the mine planning principle of waste deferment in the scheduling optimization and using all theoretically possible variants of mine sequence arrangement by the inclusion of the bench sequences over the Life-Of-Mine (LOM) in the production process."

Jan 1, 2015

By J. Marsden

Lift height, overall heap height and climate all play an important role in determining precious metals leaching rates, recoveries, operating costs and capital cost requirements for heap leaching operations. The effects of these factors are not easy to predict from testwork, and this can result in unexpected delays in metal production, lower recoveries than expected and higher capital and operating costs than necessary. This paper investigates the economic impact of lift height, overall heap height and climate on heap leaching and provides criteria to assist in the design and operation of leaching facilities. Descriptions of three heap leach operations in the western USA are provided to support the discussions and conclusions.

Jan 1, 1995

By S. E. Valji

Clay slurries are normally dewatered using flocculents like sulfuric acid or aluminum sulfate. This type of flocculation is based on the electrolytic mechanism. For certain clay dewatering applications, this method of flocculation is unsatisfactory. Flocculation, based on the bridging mechanism, using organic polymers has been utilized to overcome such problem situations. This method of flocculation offers solutions not possible by previous methods. Normally these flocculents are used to assist dewatering. In this case, not only is dewatering promoted, but also further processing is assisted by a change in the dilatant character of the filter cake that is formed. Discharge of filter cake is easier, extrusion of filter cake on to conveyor dryer is possible or improved, and heat transfer and drying rates of the extruded filter cake are substantially higher. Both natural and synthetic organic polymers have been utilized for this purpose. Selection, application techniques, and economics are described.

Jan 1, 1965

By Robert C. Bates

Published information discussing uranium mine radon daughter controls and related costs was examined and used to develop an estimated (projected) cost per ton for any level of control. Results show a clear power function increase of cost for conventional dilution ventilation as the annual exposure limit is lowered. Projections can be made using any assumed changes in consumer price index (CPI) and radon daughter working level months exposure limit. Bounds on the estimated costs are provided, and applicability of the final equation is discussed.

Jan 1, 1983

By Richard Klimpel

A common problem in mineral processing and chemical engineering is the need to estimate flow rates and/or weight ratios involved with engineering operations for which it is inherently difficult to directly measure stream weights. Simple examples of this situation include stream separators (a classifier operating on a particle flow) and stream mixers (the mixing of new feed and circulating load in a ball mill circuit). Often in these types of operations, it is possible to sample the streams involved to get approximate component analyses (e.g. size distributions of solid streams, chemical composition of chemical streams). In this paper various formulae are developed which can be used to estimate stream flow rates or weight ratios given information on the stream components. The type and level of experimental error present in the stream component analyses does have an important bearing on the numerical values (and reliability) of the weight ratios calculated by the various formulae. A simple but theoretically sound method is shown for selecting appropriate estimation formulae for any given engineering operation. The derived formulae are applied to sets of experimental classification data for illustration purposes.

Jan 1, 1979

By M. L. Free

Several studies of the fluorite/oleate flotation system have shown that under certain conditions calcium dioleate is formed at or transported to the fluorite surface. Adsorption of significant amounts of calcium dioleate is generally observed above oleate concentrations of -6 -5 between 4 x 10 and 4 x 10 M, yet little explanation of the onset of calcium dioleate adsorption is provided. In this study in-situ and ex-situ FTIR/IRS experiments have been performed in connection with thermodynamic solution phase analysis to better understand oleate adsorption as well as the onset of calcium dioleate formation. Results from this study are analyzed and compared to industrial practice.

Jan 1, 1995

By Armando M. Lago

This paper reviews the postwar changes that have occurred in the expenditure and financial behavior of mineral corporations, and in particular the relative importance of factors that affect the industry's supply and demand for funds. This quantitative statistical investigation of factors affecting sources and uses of funds of mineral corporations is achieved through the formulation of a simultaneous equation model of sources and uses of funds. After a description of the study sample in Section I, the postwar cyclical and secular financial behavior of mineral corporations is analyzed in detail in Section II. Section III formulates an econometric model of mineral corporate financial behavior which is then estimated and reviewed in Section IV. Section V discusses policy issues regarding depletion allowances, investment tax credits, and industrial organization of the mineral sector. Finally, the optimum financial structure of mining firms is discussed in Section VI, which analyzes the effect of corporate financial structure on the mining corporations' average Cost of capital.

Jan 1, 1969

By Chi-shing Wang

The U.S. Bureau of Mines has been developing the mechanical roof pulling technique as a method for evaluating the effectiveness and the comparative advantages and disadvantages of various roof bolting systems, based on the characteristic responses of bolted nine roofs to a prescribed external loading system. Preliminary experiments were conducted in the Bureau's Safety Research Coal Mine using a 12-foot and a 16-foot-span test rig. The experiments have proved the capability of the test rigs and suggested the viability of the test method. This paper summarizes the test concept and the experimental results.

Jan 1, 1974

By James A. Erdman

This overview briefly describes some examples of applications and difficulties in using plants that are drawn from the literature and from field experience. Because of the generally low Au concentra¬tions found in plants, the analysis of plant tissue is critical to the successful application of the biogeochemical method of prospecting. Neutron activation analysis is the most widely used method to detect Au in plants, due largely to its sensitivity; levels in the parts per billion range are easily attained. Two general types of sampling media are used in prospecting for Au: humus and living plants. Humus has been widely used in Canada, but the sampling of plants has increased there and elsewhere in recent years. The use of douglas-fir (Paeudotsuga menziesii) at a Au-bearing stockwork in Idaho is a prime example. A maximum Au concentration of 14 ppm was detected in the wood ash of this coniferous tree, well above the normal background concentration of about 0.15 ppm. Among shrubs that might be useful in Au prospecting, sagebrush or wormwood (genus Artemisia) could be sampled because it is extremely responsive to concealed mineralization. It has been used extensively in the Soviet Union and could be used in areas of the western United States where disseminated Au occurrences might be located. Among the problems one may encounter in using plants for Au prospecting are (1) physiological barriers, by which many plant species simply do not absorb Au at detectable levels; (2) misconceptions of soil-plant correlations; (3) localization of Au in plant tissue; and (4) the variation of Au concentrations due to season. Despite these limitations, biogeochemical techniques can complement or replace other geochemical methods currently used.

Jan 1, 2013

By William R. Hess

Volcanic ash, although a little-used Kansas resource, is available in forty counties with estimated, reserves of more than 20 million tons. It was first produced in Kansas in the early 1900?s but not until the early 1920 is did it become an important abrasive material. Total production to date is estimated at 2 million tons, the major use being as an abrasive in scouring compounds and soaps, additional uses include ceramic glazes, an additive in cement, and a filler and stabilizer in hot mix asphalt for paving. Unrecorded tonnages have also been used in construction of black-top (macadam) roads. From 1916 through 1944, Kansas ranked first among the states in volcanic ash production; peak production was about 52, 000 tons in 1923. Since 1945, production has steadily declined, primarily because materials other than volcanic ash are now being used for abrasives; only two producers operated in 1964.

Jan 1, 1965

By James J. Scott

Shale formations are the Nemesis of the Mining Engineer. Shales react to changes in environment in the most unusual and unpredictable manner. Increase in temperature may cause spalling, increase moisture and compression induced fractures may occur, and if a full face is exposed it may deteriorate due to atmospheric exposure. Combine only small amounts of shale in layered fashion with hard brittle competent rock and the whole structure may be fractured and fail due to stresses generated in and around the shale. In this paper the author will discuss failure mechanisms encountered under various field conditions and remedial action which may be employed by the engineer.

Jan 1, 1969

By W. T. Reid

Analysis of the energy resources available in the United States confirms that coal will be needed to satisfy the future energy needs. The trends in the market place, particularly economic and political, suggest that the bulk of the coal will be consumed for generation of electricity. The utilization of coal to produce electricity will require technical solutions to the variable characteristics of coal and ash, development of methods to improve coal quality, and public acceptance of the cost of compliance with environmental standards.

Jan 1, 1983

By M. B. Mooiman

It has recently been discovered that the pH at which gold can be extracted from cyanide solution with primary, secondary, and tertiary amines can be increased 2 to 5 pH units by the addition of modifiers. Under these circumstances gold can be extracted at pH values from 9 to 11, commensurate with the pH range found in cyanide leach liquors. The selectivity of the amines and amine/modifier combinations for AU (CN)[-2] over other metal -cyanide complexes is presented and discussed. In addition, potential applications for the solvent extraction of gold from cyanide solutions are discussed.

Jan 1, 1983

By R. B. Elver

The level of steel consumption per capita is one of the principal indicators of a country's standard of living. It is no coincidence that the materially advanced nations possess viable iron and steel industries to provide a reliable and economic source of steal for the manufacturing industries. No other metal is as dominantly important in manufacturing as steel. The blast furnace - steel furnace complex based on coking coal, ferrous scrap and iron ore - continues to be the principal steel-producing method. Less important is the electric furnace method based on scrap, In recent years, there has been considerable interest in the many direct reduction processes that are not dependent on coking coal but usually produce a product for further refining in steel furnaces. No matter which series of processes are used, iron ore is essentially the only source of virgin iron units. Thus, to such a vital and capital-intense industry as steel, access to a relatively inexpensive, long- term supply of iron ore is essential.

Jan 1, 1964

The Cutoff grade optimization is very critical to the open pit production scheduling. In case of single mineral deposits, algorithms have been developed for determining cutoff grade policy that maximizes the net present value (NPV) of yearly cash flows. For deter-mining the cutoff grade policy for projects with two minerals including stockpiles the problem becomes much more complex. The purpose of this paper is to present fundamentals of a generalized cutoff grade optimization algorithm that will maximize the NPV of a project subject to mining, milling, and marketing constraints. Benefits of the methodology developed are demonstrated on three different case studies.

Jan 1, 1997

By J. R. Patts, J. P. Rider, J. A. Organiscak, A. B. Cecala

"NIOSH recently completed a 15-month study at an underground limestone mine crusher booth which evaluated three research parameters: (1) the effectiveness of a single-filter filtration and pressurization system for improving the air quality inside the operator booth, (2) comparing the effectiveness of ? > 99 and ? > 95 experimental prototype filters in the system, and (3) evaluating the use of three different pressure monitoring devices to determine the performance of the filtration and pressurization system over time. The protection factor was quantified monthly using particle counters in the respirable dust range (0.3–10 µm), and gravimetric dust samples were gathered at the beginning and end of the overall study. Under static conditions and after outlier removal, the single-filter filtration unit installed offered a protection factor between 8 and 216, depending on the filter type and loading condition. The particle counting analysis shows that the ? > 95 filter offers a protection factor greater than 4-times that of the ? > 99 filter when evaluated over 60 minutes. The booth pressure monitors provided data that proved to be a valid indicator of system performance over time. INTRODUCTION Designed and installed correctly, enclosed cabs, operator booths and control rooms offer mine workers protection from physical hazards, such as flying rock, debris, and noise, as well as a more comfortable environment in regards to temperature and humidity [1]. But while it may be easier to quantify whether the A/C unit is working (measuring the temperature) or observe whether the cab offers protection from flying debris, it can be somewhat more difficult to quantify its performance in reducing respirable dust hazards. For over 15 years, NIOSH has been conducting applied research to improve the air quality inside of enclosed cabs of mobile equipment [2-5]. This work has led to the identification and mathematical modeling of enclosed cab filtration systems [6]. The same principles that govern the performance of filtration systems on mobile equipment are applicable to stationary enclosures such as operator booths and control rooms [1, 7]. Stationary enclosures are similar to enclosed cabs; however, the volume of the work area can be significantly larger. In addition, workers who perform their duties in stationary enclosures tend to stay within the room for a greater percentage of the day, as opposed to workers on mobile equipment who may enter and exit frequently. Structural integrity can be easier to maintain as well, as there is typically less vibration and stress placed on these compartments as compared to mobile equipment. In addition to offering protection from dust and flying debris, enclosures must ensure that workers have a healthy supply of fresh air to avoid elevated levels of CO2, which are known to cause headache and dizziness, impairing cognitive function. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) states that enclosures should have no more than 1,100 ppm of CO2 when outside levels are 400 ppm [8]. In addition, the American Society of Agricultural and Biological Engineering (ASABE) recommends a minimum airflow for enclosed cabs of at least 42.5 m3/hr (25.0 cfm) per person [9] to ensure an acceptable level of CO2."

Jan 1, 2017