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By Wayne Wride, Amy Lamb, Debra Sonntag

In today's "information age", we have the ability to collect volumes of data about a company's performance. The challenge is to turn that data into information employees can understand and use to fine-tune equipment, modify work processes, and ultimately manage production. Software programs have increasingly given end users control over what data is used and how it is presented. Kennecott has implemented an information system capable of collecting and storing data at the primary level. This enables plant personnel to transform historical data into information for action. Kennecott plans to expand its data collection and use trending and reporting capabilities to move toward a fully optimized operation.

Jan 1, 2000

By T. J. Harvey, W. van der Merwe, J. Joubert

GeoBiotics, LLC and Kumba Resources (Pty) Ltd are jointly developing the GEOCOAT® heap bioleaching technology and downstream processing technology for recovery of zinc from tailings at the Rosh Pinah Mine in Namibia. This paper outlines the development of a computer simulation for the bioleaching of sphalerite and the downstream processing. Computer modeling has shortened the product development cycle by allowing many flowsheet scenarios to be analyzed negating much of the expensive and time consuming laboratory testing. A model was developed using the Limn® system which is an Excel® Add-In flowsheet drawing and solution engine. Given that most engineers are familiar with Excel® this software is extremely easy to use and has less hidden calculations making model verification much easier.

Jan 1, 2003

By Chris J. Conway, Bruce W. Atkinson, Graeme J. Jameson

The flotation of coal in the fie and coarse particle size ranges presents particular problems. Fine or ultra-fine coal less than 100 microns presents a challenge to conventional flotation machines because the rate of capture of the coal particles can be very low, so longer residence times are needed. Also, conventional mechanical cells are not normally designed with froth properties in mind. Froth drainage may be inadequate, leading to excessive entrainment of ash. The upper limit of flotation of coal is normally put at about 500 um (30 mesh). It appears that, in mechanical cells, coarser particles tend to be torn away from bubbles in the turbulent environment created by the impeller. In this paper, results are presented from plant trials of a high-intensity flotation column of novel design, namely the Jameson cell. Extensive trials have been conducted on coal slurries with a top size of around 1 mm. Size-by size analysis shows that it is possible to achieve high yields of low ash product over the whole particle size range.

Jan 1, 1995

By C. C. Harvey

As we move towards the 21st Century there are several factors that will influence the markets and processing requirements for industrial minerals. Traditional markets for many industrial minerals in the developed world are frequently stagnant or decreasing because of their maturity or due to environmental factors such as reclamation, recovery of byproducts, and recycling. Some industrial minerals are greatly affected by these factors, while others are either immune to or have adapted successfully to meet these challenges. In the developing countries of the world, there is rapid market growth and resource exploitation. The future of specific mineral commodities in several markets will be discussed.

Jan 1, 1997

By Frank Sames

A recently developed model is used as a tool to optimize blast designs based on the continuing combination of full scale blast assessment and performance prediction. The use of this tool has allowed to evaluate present blasting practices and proposed designs through a better under-standing of the influence of the various blast parameters. The empirical model has a modular structure covering all aspects of blast performance including 30 fragmentation, potential rock damage and 30 muckpile profile prediction. The modules are assisted by a terrain model which is compatible to most mine mapping systems, and a blast design editor. The evaluation is summarized in a blast management module. Various studies have recently been undertaken using the model to qualify and improve blast designs with respect to wall stability, optimized fragmentation and muckpile distribution, as well as to the control of the environmental effects such as blast vibration and airblast overpressure. To verify the predictions of the modeling, full scale blast assessment techniques were used to qualify blast geometry, explosives and initiation performance, rock movement, muckpile distribution, near- and far-field vibration levels and airblast ovepressures. The model provides a tool to gain an improved understanding of blasting and blast control. The modeling results are presented in a visual form which allows simple comparisons of proposed blast designs. Additionally, the model can be used for detailed analysis and blast management.

Jan 1, 1996

By R. G. Johnston

Minerals have many uses in paint systems. These roles include use as primary and extender pigments, sheen control, film durability enhancement, and rheology control. These and other uses of minerals in paints, and the effects of mineral quality variations on coatings performance are discussed. As coatings performance requirements become more demanding, tighter consistency of important mineral properties, such as particle size distribution and purity, is becoming increasingly vital. Future directions of mineral use to meet projected environmental restrictions and performance demands on coatings, including the use of advanced minerals technologies, are examined.

Jan 1, 1993

By Thomas F. Stinson

Energy-producing states see severance taxes as attractive sources of increased revenues for otherwise tight budgets. Consumers in energy-poor states, however, protest that current rates are excessive and have moved to obtain a reduction. The US Supreme Court heard two cases questioning such taxes during its 1981 term, and Congress, in each of its last two sessions, has seriously considered measures placing a ceiling on severance tax rates. Although discussions usually focus on coal severance taxes levied by Montana and Wyoming, ramifications of changes in national policy are much larger, potentially affecting mineral taxes in all states. Severance taxes yield substantial revenues in some states, as illustrated in the accompanying table. In fiscal 1980, Texas collected more than $1.5 billion from such taxes, while Louisiana, Alaska, and Oklahoma collected $525 million, $507 million, and $436 million, respectively. Oil and natural gas production were the major items taxed. While the table shows only the 10 states with the largest severance tax collections, a total of 17 states had severance tax receipts exceeding $10 million in 1980. The enormous increases in severance tax revenue between 1970 and 1980 can be seen from the table by comparing columns A and B. For the 10 states shown, revenues increased from $650 million to $3.8 billion during that period, due to a combination of higher prices, increased production, and new or increased taxes. In most states, increases in prices and production were more evident than higher tax rates. Although the revenue increase is impressive, it understates the extent of changes occurring during the past decade. Since tax collections are shown for fiscal 1980, the full impact of the decontrol of domestic oil prices is not evident. Also, taxes on natural gas reflect controlled prices. When full de-control of natural gas occurs, significantly higher revenues can be expected in gas-producing states, even if tax rates, production, and world prices remain constant. These increases in severance tax revenues, coupled with further increases expected to accompany natural gas decontrol, have produced fears that a substantial transfer of income is taking place from residents of energy-poor states to those living in energy-rich areas. Others worry that increased severance tax revenues will be used to substitute for a substantial portion of state taxes that would have otherwise been collected from firms and individuals. The resulting improvements in tax climate, it is thought, may encourage firms and workers to migrate to energy-producing states. While these issues are often portrayed as pitting energy have-nots against the haves, such is not entirely the case. Much of the original impetus for limits on coal taxes came from Texas residents, the state collecting the most severance tax revenue. One way of gaining perspective on these concerns is by examining severance taxes per capita and as a percent of state tax collections (see columns C and D in the table). When this is done, Alaska, where 1980 taxes on oil and gas production totaled more than $1300 per capita (and 35% of all state tax collections), stands out as a special case. There, the state was able to eliminate some individual taxes, place revenues in a permanent trust fund, and consider offering a rebate of some previous income

Jan 4, 1982

By David W. Houston

The increasing energy crisis, coupled with stringent environ- mental regulations, has created new demands for high capacity materials handling systems with unit train transporting and continuing surveillance of quality control. Effective and efficient methods of material conveyance are through high speed, high volume conveyor belts with the monitoring of quality through the utilization of automatic sampling. When we speak of high speed, high volume belt discharges we are referring to speed ranges from 600 to 750 FPM and volumes as high as 5500 TPH. To achieve the optimum operating sampling system for high capacity belt discharges, it is imperative that two major design characteristics be investigated and evaluated; namely technical analysis of operating conditions through application of ASTM design criteria and practical experience in the selection of equipment and the design of related components. The task of obtaining a sample of reasonable weight to represent an entire lot presents a number of problems and emphasizes the necessity for using standard sampling procedures.

Jan 1, 1973

By R. M. Kakwani

The filtration and dewatering results of -32 mesh Pittsburgh seam coal are discussed with reference to the microscopic structure parameters, i.e., particle segregation in the cake and particle and pore size distributions at different layers. At low solid concentration of 0.33 kg coal/kg water, a non-uniform cake structure is observed in which the particle and pore sizes increase from the top to bottom layers in the filter cake. An increase in the solid concentration in slurry produces more uniform cake structure and higher filtration and dewatering rates. Air bubble entrapment in the coal filter cakes is also discussed.

Jan 1, 1984

By George S. Austin

Mud is one of the oldest building materials used by man, but it is not only of historic interest. Even today in many parts of the world, particularly lightly forested areas, it is the chief building material. Many authorities believe that at least 30% and perhaps 50% of the world's present population lives in earthen dwellings (Dethier, 1985, Coffman et al., 1990). Not all of these people are members of primitive societies or live in third world countries. European, African, Asian, and both North and South American countries contain a large number of such structures. In the United States, the American West, and particularly the Southwest, is known for this type of construction. Some of the earliest remains of adobe structures are those discovered in the ruins of Neolithic farming villages in Mesopo¬tamia dating as far back as 7000 BC (Steen, 1972). The word adobe has its roots in Egyptian hieroglyphs denoting brick and evolved to its present form through Arabic and Spanish (Lumpkins, 1977). The Spanish conquest of the New World spread the use of wooden molds to produce a standard adobe brick. Today, the word adobe is used to describe various earth building materials and techniques, usually referring to sun-dried adobe brick now used in the United States, but is also applied to puddled adobe structures, mud-plastered logs or branches (Jacal or waddle-and-daub), pressed-earth blocks, and rammed-earth walls or pisé (Smith and Austin, 1989, Ferm, 1985). Modern mud construction is used in many countries in various parts of the world. In the United States, the states from Texas to California are perhaps best known for this type of construction. Of these states, New Mexico has the dominant reputation for adobe use. Indeed, in New Mexico the Santa Fe style (Fig. 1) has made adobe not only acceptable, but preferred. RAW MATERIALS Adobe soil used by present day adobe producers, and probably past adobe producers as well, is principally sandy loam (50% clay and silt), although clayey silts are used in some areas (Coffman et al., 1990). In New Mexico, the best adobe soils are those developed on stream deposits, particularly Holocene (Recent) terrace deposits and older, loosely compacted geologic formations, such as the Santa Fe Group (Tertiary) located in the Rio Grande Valley. Some modern adobe producers use a mixture of materials from the screened fines of aggregate operations and mud from irrigation ditches in the river valleys combined with varying amounts of sand to produce the proper blend. Mineralogy Bulk Mineralogy: X-ray diffraction analyses of whole rock samples from many parts of the world where adobe is the dominant construction material show the major constituents of adobe are quartz and feldspar, with lesser amounts (in order of abundance) of calcite, clay minerals, and gypsum (Coffman et al., 1990). Adobes from and climates contain considerable calcite; in some cases calcite is second only to quartz in volume. Quartz, feldspar, most of the clay minerals, and some calcite commonly are derived from the mechanical/chemical breakdown of older rocks units. Some of the clay minerals, much of the calcite and perhaps all of the gypsum are precipitated from evaporating water. Clay Mineralogy: Clay-size minerals consist dominantly of clay minerals, but nearly clay-size fractions contain minor amounts of quartz and calcite, and occasionally other nonclay minerals. In earth construction materials from New Mexico, clay-size particles are the most compositionally variable in commercial adobe soils. However, the clay mineral groups in this size fraction consist of about equal parts of expandable clay minerals (smectite and mixed¬layer illite/smectite or I/S) and non-expandable clay minerals (ka¬olinite, illite, and chlorite), with minor quartz, calcite, and feldspar (Smith and Austin, 1989, Austin, 1990). In the and American Southwest, smectite is commonly calcium-rich and the I/S is dis¬organized and randomly interstratified. In a study of 42 New Mex¬ican commercial adobe soils, only two contained chlorite, and vermiculite, sepiolite, and palygorskite were not found. Soils in temperate climates, as are found in the midwestern and northeastern United States, contain an abundance of illite (Potter et al., 1975). The clay minerals in earthen structures of that region and in Europe commonly contain illite with less amounts of kaolinite, smectite, I/S, chlorite, and vermiculite. In contrast, the clay-size fractions of soils of humid tropical areas are typically acid, with kaolinite as the dominant clay mineral and lesser amounts of I/S, illite, smectite, and others (Chamley, 1989).

Jan 1, 1994

By Leons Kovisars

Two-thirds of the world copper produced in 1979 incurred cash costs between $0.35 and $0.89 per lb, averaging $0.62 per lb. North American costs are higher at $0.48, $0.88, and $0.68 per lb, respectively. Variable cash costs are $0.20, $0.58, and $0.39 per lb for the world; $0.29, $0.63, and $0.46 per lb for North America. Cash costs are relevant for comparing existing operations and evaluating market pricing during periods of excess supply. Analysis of full costs of production (cash costs plus income taxes, profit, and non-cash items) becomes relevant in evaluating the incentive price required to develop new production plants. In mid-1979 this cost (incentive price) was about $1.10 per lb; it is expected to approach $2.00 per lb by 1985.

Jan 1, 1979

By Dennis C. Parker

The Porters Creek clay is mined for its absorbent properties. The formation is part of the Upper Mississippi embayment and is recognized in Alabama, Mississippi, Tennessee, Kentucky, Illinois, and southeast Missouri. Major minerals in order of abundance are Montmorillonite, Quartz, Illite, Kaolinite, and Chlorite. Mining consists of open pit operation utilizing track loaders or scraper. The clay is dried or hardened in rotary kilns and crushed to size by roll crushers. The clay granules are sized and air classified prior to storage for shipment or packaging. Granules are sold for pet absorbents, oil absorbents, anti-skid material, fertilizer, and pesticide carriers.

Jan 1, 1979

By Thomas A. Simpson

Heretofore, underground coal mines in Alabama have operated under only 60 to 360 meters of cover: however, new mines (at least 5 in the early opening or development stages) will be operating under cover ranging from 600 to 660 meters. With increased rock confining pressures, roof stability problems will become more critical. Initial studies in two 7 ½ -minute quadrangle areas in the Warrior coal basin of Alabama indicate that the orientation of certain lineament and fracture-trace modes mapped from ERTS-1 (Earth Resources Technology Satellite) imagery correlate closely with the strike of joint and fault modes. High altitude (118,000 m) U-2 aircraft data were used to support these findings. In addition, over 50 percent of the normal faults mapped in the study area could be directly correlated with ERTS and U-2 lineaments and fracture traces. These correlations provide clues to the structural development of the Warrior coal basin and may, in turn, be used as a guide to the prediction of roof-stability conditions in advance of mining.

Jan 1, 1975

By C. E. Capes

The continuous balling? operation whereby a moist particulate mass is tumbled in a horizontal revolving drum with recirculation of the undersize product can be extremely unstable. Product and recycle rates are subject to wide fluctuations. Although the problem seems to be well-recognized, there is little published information or quantitative data readily available, especially in relation to industrial-scale circuits. Probably the best available published results are in the Russian literature, an illustration of which is given in Figure 1. These data, taken from a study') of some of the factors which influence the stabilization of the pelletizing process, illustrate the wide variations in circulating load and circuit productivity which may be encountered over a period of operation. The problems of balling circuit stability may be traced to random seed or nuclei generation and uncontrolled agglomerate growth. The situation is analogous to that in crystallization processes where (4 considerable attention is given to nucleation control. Traditionally attempts have been made to optimize system and operating variables to stabilize the balling process. A supplemental approach which is taken here is to build on the considerable

Jan 1, 1975

By Lawrence P. Kennedy

The Lynne deposit is a volcanic-to volcaniclastic-hosted, Zn-Pb-Cu-Ag orebody located in the early Proterozoic magmatic terrain of northern Wisconsin. As of February 1991, core drilling has partially delineated a multi-million ton, near-surface, disseminated to massive sulfide deposit. The deposit is hosted by a gently dipping sequence of fragmental rhyolites, felsic tuffs, less abundant dacite to andesite flows, and fine-grained volcanic sediments. The deposit is broadly conformable With the host rock stratigraphy, but the ore zones thicken and coalesce in the central part of the deposit.

Jan 1, 1991

By J. Kretschmann, K. van de Loo, J. Brune

In 2018, the German Federal government decided to phase-out the energy production using coal-fired power plants and to terminate lignite mining completely by 2038 at the latest. This decision will impact approximately 60,000 jobs. It will have an enormous impact on the socioeconomic development especially in all German lignite mining regions. To avoid economic and political friction, it is of utmost importance to achieve a sustainable transition towards a post-mining era and to offer residents in the mining districts perspectives for a good future that include adequate job opportunities. In this context, the German government is providing massive structural aids early on. As previous closure experiences from the German hard coal mining industry have shown, it takes at least a generation to overcome the effects of a strategic closing decision of this magnitude. Therefore, the planned closure process appears to be a long time at first glance. In fact, however, it is not.

Mar 2, 2022

By K. Verghese

Neutron capture prompt gamma-ray analysis provides the best method for on-line analysis of the elemental composition of large volumes of bulk material. This paper summarizes the Monte Carlo models which simulate the radiation transport within two such analyzer systems; namely, the borehole configuration and the conveyor belt configuration. The models are useful in the design optimization of the analyzer systems, in minimizing the amount of experimental calibration data for calibrating these analyzers, and in investigating the detection sensitivity for different elements. The computational scheme in these models is made extremely efficient by the use of various powerful variance reduction methods and by efficient data management. Experimental verifications of the two models carried out in the laboratory indicate very good agreement with the Monte Carlo results.

Jan 1, 1984

By W. Z. Choi

A model describing size reduction and mineral liberation during grinding has been extended to include multiple classes of composite particles. The majority of the model parameters have been directly determined using computerized image processing equipment to analyze the products from batch grinding tests. A coarse-grained sphalerite ore from Tennessee, representing a nearly ideal binary mixture of sphalerite and dolomite, has been used to experimentally validate the model for the case of dry, batch grinding. In all cases, excellent agreement has been observed between the model predictions and the experimental results.

Jan 1, 1986

By Daniel C. McLean

Many of the major copper ore bodies throughout the world contain chalcocite (79.9% Cu) as the principal copper mineral, yet the grades of copper concentrates produced from these ores rarely exceeds 25 to 28% Cu and in one known instance went as low as 13%. The low grade has traditionally been attributed to the presence of "activated pyrite" and/or chalcopyrite, and the universal approach has been excessive regrinding with all of its inherent effects-high capital, energy and maintenance costs, excessive sliming, and concentrate filtration difficulties (high moisture content). E. P. Cadwell, former Chief Metallurgist for American Cyanamid Company, did extensive microscopical studies on several of these types of concentrates from South American operations during the 1950's and discovered they all had one common feature--the pyrite particles in the concentrate were all rimmed with thin films of secondary chalcocite or covellite. As far as a flotation bubble or reagent is concerned, a rim of chalcocite is the same as a solid particle of chalcocite, and as long as a rim is present, the particle is going to float. Upon examination of these rimmed particles under the microscope, it becomes quite obvious why regrinding will never solve the problem and why maximum increases in grade by this technique rarely give improvements in grade of greater than 3 to 5% Cu.

Jan 1, 1983

By Craig E. Burson

This paper discusses the relationship between frother types and coal flotation as a function of particle size. It has been found that each frother has a unique size fraction that it will float effectively. This fact is very important when it comes to selecting a reagent scheme that will provide maximum recovery of both coarse and fine particles. Improvements in recovery can be attained when the chemical relationships between frother type and particle size floated are understood. Data from plant evaluations using commercial and developmental frothers are presented to verify the importance of frother types versus size fraction floated.

Jan 1, 1987