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By L. Borsch

Geochemical laboratories are commonly criticized by geologists about poor analytical reproducibility and erratic anomaly patterns, especially when gold and trace metals from resistant minerals are reported. Geochemical analysis in mineral exploration is a compromise between high productivity on the one hand, imposed by large numbers of samples, and analytical precision and accuracy on the other. However, the physical properties of resistant minerals, such as cassiterite, gold, beryl, chromite, zircon and others, interfere with both of these requirements. Therefore, the degree of sample homogeneity that can reasonably be achieved in sampling and sample preparation must be considered. Subsequently, the understanding of its effects on analytical data quality and the consequences on data interpretation will provide a basis for understanding the problems common to exploration as an interdisciplinary science. Complaints about poor and inadequate analytical performance are not confined to exploration geochemistry. They are a common feature in mining and metallurgy and wherever sampling and analysis of "grains" are concerned - the "nugget" or "grain size effect." The "grain size" effect Poor analytical reproducibility is normal for gold and a well-defined group of other elements usually found in resistant placer minerals. Those who use and interpret geochemical data must realize and appreciate the chemical, the physicochemical, the physical and the mineralogical properties of the elements and their minerals. Especially for the "placer" minerals and their elements, such comprehensive interpretation is crucial. The most important factor to consider is the behavior of a mineral and its metal component(s) during weathering and their integration into the sampled medium, in exploration mostly sediments and soils. (Data interpretation for samples of water, gas, to a certain extent rock, follows different patterns.) A mineral may be chemically and physically stable or it may easily disintegrate physically or decompose chemically, or any combination of such processes, at varying degrees. The breakdown products, in turn, may or may not, interreact with the environment. If the nature of an element or a mineral predestines it for a heterogenous distribution in the sample medium, then nature, size and number of grains likely to occur should be considered in relation to the sample portion taken for analysis. This allows the estimation of their effect on analytical precision and accuracy. Elaborate and sophisticated statistical calculations exist on this subject. But these approaches do not cope with the complexity of the natural surface environment. The miner alogical, chemical and environmental behavior of elements and minerals can be estimated but not calculated. However, the mineral grain sizes and their influence on analytical precision can be precisely calculated if certain conditions, assumptions and idealizations are made. If the geochemical and mineralogical characteristics of minerals and elements are understood, such calculations demonstrate the grain (or nugget) effects that mineral properties and (geo)chemical behavior of minerals and elements cause on the precision and accuracy of geochemical analysis through their influence on sample homogeneity. Two other factors that influence the sample homogeneity and the nugget effect are the efficiency of sample preparation and the sample portion taken for analysis. In this way, certain element- or mineral-specific parameters can be established as a guide for the sampling program. The information, for example, may assist in determining sampling procedures in the field, especially the sample weight to be taken for "representative samples." Also, it may help assess whether analytical data, as provided by the laboratory, are acceptable. Finally, it may help determine the approach in data interpretation. However, all such simplified calculations are based on idealized, that is, unreal assumptions and conditions. As such, they represent one extreme end on the scale of probabilities. The reality is found somewhere away from this extreme, towards homogeneity. An example from a study of an eluvial gold prospect may be given for illustration: •Original sample weight: 20 kg (44 lbs) of rock gravel, crushed and ground to -0.18 mm (-80 mesh). •Au content: 20 grains of Au, average size of about 0.5 mm3 (0.03 cu in.) each = 7.5 mg each, making a total of about 150 mg Au in the sample = 7.5 ppm Au. Assumptions •Au occurs in the sample as free, discrete grains only. •Not more than one grain, if any, goes into each sample split (analyte) portion (20 grains of 7.5 mg Au each). •Analysis of original rock sample: 100 g sample for analysis, 20 kg/100 g = 200 samples 20 samples with 1 grain each: result, - 75 ppm Au. 180 samples with no grain: result, 0 ppm Au chances 1:9 •10 g sample for analysis:

Jan 1, 1996

By John A. Herbst, K. Rajamani

Process improvement is probably the most widespread objective of mineral process plant operators in the late 1980's. An important part of such improvements is dynamic optimization which involves reacting to inevitable plant disturbances in such a way that productivity is maximized at every instant of time. This paper describes the way in which mathematical models can be and have been used in dynamic optimization. Both off-line and on-line model applications are described.

Jan 1, 1989

By M. Ericsson

The extractive industries consist of five major sectors: - Mining equipment and services - Dimensional stone - Industrial minerals - Aggregates - Metal mining These industries produce some finished goods but mostly semi-finished products as they feed into other industrial sectors: Basic metals, fabricated metals, construction, chemicals, dyes and pigments, inorganic chemicals, fertilizers, rubber and plastics and non-metallic mineral products. These are the major down-stream industries in this study. Taken together with the extractive industries they form the mineral resource based cluster. The mineral resource based cluster is a substantial part of the Finnish economy: It employs 211 000 persons, 39% of the number of employees in industry. The cluster?s exports account for 20% of industry exports. Value added is 34% of total value added in industry. Investments reach 35% of total industry investments.

Jan 1, 2003

By John B. Rigg

Thank you Mr. Chairman. It was a generous introduction. It allays some of the puzzlement I have of being a minority among the speakers at this conference. I see from the program that only two of us have been asked to speak on topics in keeping with an election year. Instead of reporting facts on past events as most speakers are, J. W. Wilson, of Consolidation Coal, and I have been designated to forecast the future. Forecasting in an election year implies a liberty to fabricate at will, hallucinate, fantasize, stretch fact and fancy and generally prognosticate without regard for the consequences. Since I'm not seeking your votes, promises aren't mandatory. This will be done with supreme confidence stemming from profound wisdom and a foolproof crystal ball. So instead of soliciting your vote, I'll simply penetrate 24 years of tomorrows, which may not be much different than some of us remembering the later hours of last night. My remarks do not draw upon Gulf planning department projections. Instead they are a roll of the dice of personal conjecture to stretch your imaginations on oil shale mining through the year 2000. In this regard, it is sobering to keep in mind that it has been in my lifetime that investors wouldn't risk a dollar on paperback books, motels, supermarkets, or drive-in restaurants. And only thirty years ago it was predicted by an eminent Ivy League professor

Jan 1, 1976

By C. J. Johnson

As the U.S. coal industry moves into the next century, it is becoming more apparent that the effective application of new technology is the only way it can remain competitive in the energy marketplace. Examples of this emphasis are with us today in such diverse areas as face-ventilation and excavation-equipment applications. The focus of this new technology is directed toward improvements in health and safety, cost control, and productivity. Room-and-pillar mining accounts for approximately 80% of the nation's underground coal production; this percentage is not expected to decrease markedly in the near future. As such, this paper analyzes the impacts of the changing technological climate on future room-and-pillar operations by comparing a base-case section (current) to three scenarios incorporating new or emerging technology. A microcomputer-based comparative analysis will reflect the changes in section production and costs.

Jan 1, 1988

By D. C. Durgin

Located near Ely, Nevada, the Robinson Mining District has produced gold since 1868 from the Ruth? porphyry copper system. Gold occurs in at least seven different deposit types, including porphyry copper ore, silica-pyrite replacements along favorable horizons, fault controlled silica bodies, intrusive breccias, stockworks in bornfels and in retrograde skarns. In all of these the primary controls localizing gold ore are structural .preparation and permeable hosts. Indicator elements associated with gold are Ag, As, Te, and to a lesser extent Sb and Tl. Pb, Zn and F are peripheral to gold or with it depending upon position within the system. The district has produced 87,000 kg (2.8 million ounces) of gold thus far. An additional 19,300 kg (620,000 ounces) of reserves are established, and well over 31,100 kg (1,000,000 ounces) of reserves are anticipated. I

Jan 1, 1989

By Harrison R. Cooper

Composition data is needed as input for executing process control and management of particulate separation for flotation control. While requirements for composition data can be satisfied in many cases by manual sampling and analysis, automatic sampling and assay systems are now viewed as justified for all but the simplest or smallest processes. On-stream X-ray fluorescence analysis (XRFA) has satisfied requirements for the main portion of metalliferous sulfide ore flotation processes as XRFA technology evolved in reliability and sophistication from its beginnings in the late 1950's. In recent years, advanced on-stream analysis technologies have reached levels of development suitable for use in process control to increase efficiencies of important processes in mining and minerals industries such as coal fines flotation and industrial minerals beneficiation (particularly phosphate beneficiation) where XRFA methods have been inapplicable. Recent technical developments pertinent to use of advanced technologies as well as improvements to established on-stream composition analysis methods are discussed.

Jan 1, 1989

By Steve Karl

President Reagan may be "a nice guy," but he is "misinformed, misdirected, and misadvised," when the subject is the state of the US copper industry, according to Sen. Dennis DeConcini (D-AZ). DeConcini took the opportunity as keynote speaker at the Arizona Conference AIME in Tucson to fire a few salvos at the Reagan Administration's industrial policies. "American copper used to stand above the rest of the world," he said. Now 21,000 copper workers, about half of the total, are out of work due to less expensive foreign imports. "Those 21,000 are real people, not statistics," he said. US production has been cut to one-third of its capacity, he said. And the Administration shows no signs of changing its position to favor US copper protection. "Third world copper towns are booming," he continued, "while ours are dying." Regardless of profits and despite oversupply, Chile continues to produce, he said. And, while US mines continue to close, "the International Monetary Fund (IMF) is handing more than $1 billion to six copper producing countries." President Reagan wanted $8.6 billion from the IMF. "I'm damn mad about it," DeConcini said. "For the life of me, I can't understand how this Administration can stand by while this industry is brought to its knees." Last year, the International Trade Commission ruled that imports were injuring domestic copper and recommended relief. The President, DeConcini said, vetoed those recommendations. DeConcini softened his tough talk a bit saying the President's image makes it difficult for people to not like him or stand up to him. "How can anyone stand up to President Reagan?" he asked. "He's such a nice guy. But it's time someone did. He's just misinformed, misdirected, and misadvised. We must take real action and we must have a president who understands this." DeConcini said he has introduced legislation aimed at helping domestic copper. It would limit copper imports to 385 kt/a (425,000 stpy). Imports now stand at about 635 kt/a (700,000 stpy). The bill would also impose a $0.33/kg ($0.15-per lb) duty on foreign copper. DeConcini called the duty a sort of "environmental equalizer" because that is the amount domestic producers must spend on pollution control devices. Foreign competitors do not have such controls, he said. "I face people who are damn mad that this country is being pushed around," he concluded. "It's time we stand up and say we can be competitive. If they (foreign countries) put an import duty on our stuff, we will do the same. It's time this country stopped being the nice guy." As if to underscore domestic copper's desperate situation described by the Senator, Duval Corp. announced about the same time as the meeting that it has nearly closed its eastside office in Tucson. Staff has been reduced from 120 to four. Spokesman Dean Lynch said the four will consist of President A. Everett Smith, a secretary, a person in environmental affairs, and another in purchasing. Duval is also selling an office and a laboratory in Tucson. Pennzoil Co., Duval's parent, has been trying to sell the company for more than a year. It began dismantling Duval in November 1984. Pennzoil took over its subsidiary's profitable sulfur operation in Texas, sold the New Mexico potash facility, and spun off gold interests in Nevada, forming Battle Mountain Gold. Northwest Mining Association - Spokane Rock Jenkins, Associate Editor The true role of minerals needs to be realized by both the policy makers and the people of the US, according to Robert Dale Wilson, director of the Office of Strategic Resources, US Commerce Department. In addition, a re-thinking of the theory of free trade and competitive advantage is necessary. Wilson made his remarks in December at the opening luncheon of the 91st Annual Convention of the Northwest Mining, Association in Spokane, WA. At a later press conference, Wilson said one of the mining industry's main problems is that its presence in Washington has been reduced in the past few years. Part of this can be seen by events within the American Mining Congress (AMC), he said. "The problem with AMC," Wilson said, "is that in 1981, when Reagan came in, no problems were seen for mining and a lot of their (AMC's) lobbyists were let go." He

Jan 1, 1986

By Fan Yang, Meigui Yi, Lan Xiang, Zhuoying Yang

This paper reported the calculation of the reaction heat in titanium-bearing blast furnace slag (abbreviated as TBFS)-H2SO4 system based on estimation of thermodynamic data of CaTiAl2O6 by mechanical mixture model. The thermodynamic analysis indicated that CaTiAl2O6 was more stable than the corresponding ternary oxides as CaO·TiO2, CaO·Al2O3, and Al2O3·TiO2. TBFS-H2SO4 system was highly exothermic since all of the reactions involved in the system were exothermic. For example, the increase of temperature from 25 to 200°C led to the increase of the release of the reaction heat in TBFS (100.0g)-H2SO4 system from 181.28 to 189.73kJ. Eighty-five to 90%of the reaction heat in TBFS-H2SO4 system was contributed by the reactions among CaTiAl2O6, CaTiO3, CaMgSi2O6, and H2SO4.

Feb 1, 2021

By V. Angelatou

In the present study, the possibilities of use of natural zeolitic tuffs from the Skaloma area, Rhodope prefecture, Greece, for the removal of Pb and Zn ions from aqueous solutions has been studied. The equilibrium data were examined for different grain sizes, pH?s and initial concentrations. An apparent kinetic study was also carried out for different time intervals at constant temperature and pulp density. For the chemical equilibrium study the Freundlich isotherm was used. The experimental results verified the favored behavior of zeolite on lead ions and the quick kinetic of the process whilst the efficiency of the ion exchange on zinc is rather limited. The grain size of the material did not greatly affect the performance of the process. The removal of metal ions worked better at lower pH. The Freundlich isotherms are in good agreement with the experimental data.

Jan 1, 2006

By V. Nasri, P. Jarast, M. Bakhshi

The Montreal metro Blue Line Extension toward the northeast consists of the construction of five new underground stations. The project includes 6 kilometers of the tunnel which will be constructed using a Tunnel Boring Machine (TBM). In line with the commitment to integrating sustainability best practices, Envision verification is pursued this project. The Envision reference framework was developed to cover all the sustainable development aspects of an infrastructure project and each phase of its life cycle (planning, design, construction, operations and maintenance, and end-of-life). As a part of this endeavor, low-carbon concrete and shotcrete mixtures are proposed for the linings of TBM and SEM tunnels as well as stations and auxiliary structures. The CO2 emission of the low-carbon concrete and shotcrete mixtures were compared with their typical mixtures and the total CO2 emissions reduction related to the tunnel lining is determined. The study is of strategic significance for achieving emission reduction in the tunnel industry.

Jun 13, 2023

By Vaughn Astley, Hassan El-Shall, Ponisseril Somasundaran, Regis Stana, Patrick Zhang

In the past, when phosphate rock quality was good, few paid attention to any of the impurities or other qualities associated with phosphate rock. In general, they had little or no effect on the ability to make the phosphate products for the market. However, as phosphate rock quality declined, it was apparent to the rock consumers that the individual impurities had a significant impact on their processes. FIPR is presently funding an analysis of operating plant data to determine the range of the effects of rock impurities on production plant performance. The study will not be completed until 2002. IMC has agreed to share some of the information they had developed in the early 1990s.

Jan 1, 2002

By J. A. Dlas Lima

Alunorte is a metallurgical-grade alumina refinery located in northern Brazil. This plant which was designed to produce 1.1 million mtpy of calcined alumina, started operation in July 1995. A process information system was installed before refinery start-up. It has been a main factor in process improvements, which resulted in an increase in production from 1.1 to 1.5 million mtpy. This system has been particularly useful for analyzing data and allowing retrieval of data by process engineers. This paper describes how a quality monitoring system to evaluate all aspects and stages of production, as well as alumina silo level and blending percentage, was developed. This system was designed to give support to ISO 9002 certification, which happened in December 1998. The quality monitoring system was developed using Microsoft Excel 7.0 and makes extensive use of VBA macro. The primary users of the system are shift foremen, managers and engineers, who use it to track the process and avoid variations in alumina quality.

Jan 1, 2000

By J. P. Mogan

As diesel exhaust contains a mixture of several materials of varying degrees of toxicity which interact to a currently undefined extent in their effects on health, the prescription of a quantity of ventilating air to dilute the exhaust to a safe level is necessarily, to some extent, arbitrary. Some jurisdictions rely on the application of a safety factor to a single "governing" component (usually nitric oxide for most modern diesel engines). Others specify that the total of the "adjusted" concentrations (actual concentration divided by maximum permissible concentration) not exceed "one" for related constituents (irritant gases for example). Neither of these approaches, however, takes account of the interaction of the gaseous constituents with diesel soot (although many studies verify such interactions), nor do they provide any economic incentive for reducing pollutants which are not included in the criteria for ventilation. Because of these factors, the Canadian Department of Energy, Mines and Resources awarded a contract for a study of the current literature bearing on the "Health Implications of Exposure of Underground Mine Workers to Diesel Exhaust Emissions" (1). One goal of this study was the formulation of a new ventilation criterion. The contractors, Ian W. French and Associates, studied more than 1500 literature citations which they interpreted in a 350 page report and summarized in a companion 1600 page annotated bibliography. In the recommendations section of the report, they defined a new 'health effects index' or ventilation criterion "V" as follows: [ ] The contractors consider that a "V" between 3.0 and 4.0 poses a moderate threat to health which could be alleviated by the use of protective equipment such-as filter helmets. If V exceeds 4.0, an increase in ventilation quantity to reduce the pollutant levels is indicated. In the case of mines with a quartz content in excess of 20% in the ore, the contractor recommends that a term. [Quartz]/ [Threshold Limit Value Quartz] be added to the equation, and [2.0 = ?v? = 30] be the range justifying protective equipment, with added ventilation if "v" exceeds 3. A degree of pragmatism was inherent in the development of the equation, as the contractors recognized that the components of the index, if it is to be useful in the near term, should be within current routine underground environmental assay capability.

Jan 1, 1980

By William F. White

It is a pleasure to have the opportunity of being here today to discuss the application of horizontal filters in the metallurgical industries. The use of horizontal type filters has been limited in metallurgical plants. However, in the recent past there have been new designs of this type equipment which greatly broaden their field of application. Through their use in many applications, important economies can be achieved over more conventional methods. The first of the modern continuous horizontal filters was initially developed by Oliver United Filters as their scroll type horizontal filter. This was an outgrowth of the old Oliver Sand Table that was limited to very coarse, free filtering pulps containing no appreciable amount of fine particles. The sand table was rather limited in application. The later continuous scroll type horizontal filter provided for a reverse air blow after discharge which reslurried the heel remaining and permitted the filtration of pulps containing finer particles. In the manufacture of phosphoric acid by the ?wet? process, the filtration of gypsum from the strong acid presented an extremely difficult filtration problem due to blinding of the filter media caused by crystallization of the soluble salts contained in the acid. A filter which allowed for continuous cloth washing was required, and this led to the development of the continuous pan type, and travelling belt type horizontal filters which provided for this need. Among the filters developed were the Prayon by Engineering and Industrial Corporation of Luxembomg for use in their phosphoric acid plants. They are one of the largest manufacturers of phosphoric acid in Europe. The Dorr-Oliver Traveling Pan Filter was also developed by Mario Giorgini, Manager of Dorr-Oliver?s Italian subsidiary, for use with the Dorr Company?s phosphoric acid process. Basically, there are four existing types of horizontal filters in commercial use at this time: The scroll discharge non-pan type, the continuous belt type (Lurgi), rotary pan type, and the traveling belt type. The construction and principle of operation of these various filters will be discussed.

Jan 1, 1958

By Shawn Healey

The Mineral Hill Mine, owned and operated by TVX Gold Inc., is located in the Beartooth Mountains, 5 miles north of Gardiner Montana, U.S.A., which is the north entrance of Yellowstone National Park. Mining is carried out underground using ramp attack cut and fill as well as room and pillar mining. The mine currently employs approximately 145 people and is producing 550 tons per day at a grade of around .21 oz/ton.

Jan 1, 1996

By Arafat Ghosheh, Yousuf Abu-Rish, Darwish Amara, Mohammed Baderkhan

The Jordan Phosphate Mines Company is one of the world's major phosphate rock and phosphatic fertilizers producers (the second largest phosphate rock exporter), with ore reserves exceeding 2 billion tonnes, mainly located in the Eshidiya area. The Eshidiya phosphate deposits, 120 km north-east of Aqaba, are of sedimentary origin (as are all phosphate ore in Jordan). Three exploitable beds (Al, A2, and A3) with variable content of P205, CaO, SiO2, etc., are processed in order to produce 68-70,73-75, and 75-77% TCP grades. The A3 bed, which is characterized as the most siliceous containing 40-48% TCP, requires physical beneficiation using wet scrubbing, screening, and desliming by hydrocylone, followed by anionic conventional flotation to achieve 75- 77% TCP grade. For the last 15 years extensive laboratory and pilot tests (including physical, chemical, and mineralogical studies) were carried out. After operating the industrial plant, certain modifications were deemed necessary to adjust the operational parameters and the final flowsheet, which was followed to obtain the targeted quantity and quality of concentrate.

Jan 1, 1999

By R. Ciccu

Permeable reactive barriers (PRB) are one of the most promising systems for groundwater remediation. PRB are constructed with the purpose to intercept the contaminated flow and to degrade it as a big reactive filter. The most common type of reactive barriers is realized by excavating a trench and by filling it with a substance able to treat the contaminants dissolved in the water. Another type of PRB is obtained by realizing a line of wells in which chemically active compounds are injected. A new method for barrier construction has been studied at DIGITA?s laboratories. It makes use of the waterjet technology to increase soil permeability and to inject active compounds. This technology is especially suitable in the case of deep contaminated aquifers where traditional construction methods are difficult to apply. The paper describes the experimental apparatus especially designed and constructed and the activities carried out to investigate the relationship between waterjet operative parameters and the penetration of the jet in the soil. In conclusion, on the basis of the experimental results, the economical feasibility of the technique is evaluated.

Jan 1, 2008

By Sean E. Armstrong, Deepak Malhotra

The current trend in gold ore processing is the development of lower grade or highly refractory deposits. The perplexity of treating low grade oxidized ores has been adequately addressed by heap leach technology. However, refractory gold ores are very difficult to positively characterize the gold association within the mineral matrix. Gold accompanied with refractory sulfitlc or carbonaceous mineralization can often be sub­micron In size and occur interstitially. Mineralogical examination of these ores Is difficult, expensive, and occasionally Inconclusive. Hence, the metallurgist Is given little information for the selection of processing alternatives. The purpose of this paper Is to demonstrate the use of diagnostic leach procedures to assist the metallurgist' s decision-making process to solve some of these problems. By sequentially liberating and/or leaching gold associated with specific minerals, the amount of recoverable gold in each stage can be determined. Through careful interpretation of the results obtained by diagnostic leaching, the metallurgist can devise a flowsheet for treating the ore or solve a problem at an existing plant

Jan 1, 1992

By R. E. J. Putman

The past ten years have witnessed substantial development of electronic equipment for execution of process control functions. The methodology of giving instructions to the data-handling system and the organization of the system, both the equipment and instruction coding taken together, have developed simultaneously. Examples of the technology specific to the mineral processing industry can be cited. Approaches to system design developed for the Pinto Valley concentrator incorporating slave and master data processing have been described by Arney, and his associates (1974). Madge (1970) has described the hierarchical systems employed at the operations of Cominco Ltd. The Kennecott Garfield smelter is controlled by a system of microprocessors linked to a general purpose data processor (Marchant, et al., 1977). These systems provide innovative approaches to couple advancing technical capability in electronic data processing to the objectives of process management. The current state of the art described in this chapter is certain to require updating in the 1980's with the advances in technology anticipated.

Jan 1, 1979