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By S. P. Chong, Peter V. Avotins

The iron and steel industry continues to operate at depressed production levels due to the low level of demand for steel and foundry products. Crude steel production in the Western world dropped by 13.7% from 459.3 Gt (506 billion st) in 1981 to 396.4 Gt (437 billion st). The reduction was particularly severe in North America where the industry suffered a loss of 37.3% from 123.6 to 77.5 Gt (136 to 85 billion st). This reduced level of production severely affected iron ore and agglomerates output. Substantial curtailment was made in both sintering and pelletizing plants to meet reduced demand. The pressure on these plant operators shifted from quantity to quality. With energy cost becoming an ever increasing part of production costs, conservation was a major area of emphasis. Iron Making Sinter has continued to be the favored burden for blast furnaces overseas. As hot metal production declined and excess sintering capacity developed, many of the overseas operators that have been using pellets found it advantageous on hot metal production cost to increase the ratio of sinter at the expense of pellets. This was the case despite the depressed price level of pellets in the world market. In North America where pellets have been the predominant burden material-mainly because it is necessary to pelletize the fine grain iron ores available domestically-there was also increased interest in sinter usage. Bethlehem Steel Corporation's 13.6-m (44.5-ft) furnace at Sparrows Point experimented with a burden with more than 70% of sinter during the second half of the year and indicated some favorable results as compared to its previous 50% super flux sinter and 50% acid pellet burden. The blast furnace operators continued to press for improved burden quality. In addition to the emphasis on the importance of burden chemistry and quality, uniformity, much emphasis was placed on improving reducibilitiy and high temperature metallurgical qualities. These burden properties were recognized to hold further promise in reducing fuels rates. Sintering With reduced consumption caused by the cutback in hot metal production, many sinter plants sat idle while others operated at greatly reduced rates. The deemphasis on production in many plants allowed them to experiment with various means to reduce operating costs. The most notable action was the introduction of low cost South American pellet feed fines into the sinter ore mix. These feed fines, which are finer than 150 µm (100 mesh) ore, were previously thought to be too fine for sintering. However, when the full production rate is not required the use of up to 40% in the ore mix was reported to be successful with the aid of burnt lime and adequate premixing and granulation of the sinter mix before sintering. The emphasis on quality and tighter cost control also has resulted in a further breakthrough in sintering technology. It was recognized that good feed preparation-including selection of compatible ores, good blending, good pseudo-particle formation, additive size control increased bed depth, and closed control of the sintering bed heat pattern-could allow the production of high quality sinters with much lower heat input and FeO level. Bed depth of more than 600 mm (23.6 in.) was practiced in a number of operations. Total heat input of better than 1.3 GJ/t (290,300 kcal per st) has been achieved. Kawasaki Steel's Chiba Works has also achieved a 5.3% SiO2 in the sinter with good quality. The low heat input approach allowed production

Jan 5, 1983

By N. Colvin, J. W. Gulyas

HISTORY The Surigao Nickel Refinery of Marinduque Mining and Industrial Corporation is located on Nonoc Island off the northwestern coast of Mindanao in the Philippines. Nonoc Island is part of the Surigao Mineral Reservation which had been identified as early as 1912. Initial interest in these deposits was due to their iron content, and their value as a nickel deposit was not seriously entertained until the late 1950's. The Philippine government undertook extensive test pitting and sampling programmes at that time and in the early sixties Marinduque became involved in helping to establish firmer ore reserves. Evaluations of the test pitting programme indicated reserves of 75,000,000 tonnes of ore averaging 1.22% Ni, 0.1% Co and 38.5% Fe. The Philippine government called for bids on the reservation in 1962 and Marinduque and Sherritt Gordon carried out some feasibility studies for the recovery of nickel from the deposit. However, it was not until 1968 that Marinduque was granted proper authority to exploit the Surigao deposits. Marinduque and Sherritt then entered into an agreement which allowed Marinduque to utilize a process developed by Sherritt for treating lateritic ores. During 1968, a 25 st/d pilot plant was erected in Fort Saskatchewan, Alberta for the purpose of modelling all process steps. A 10,000 tonne ore sample was sent from Nonoc as feed stock for the pilot plant.

Jan 1, 1979

By J. E. Rourke, O&apos

This paper describes the use of index testing to obtain rock properties that are useful in the design and construction planning of an underground development for civil engineering or mining projects. The index properties discussed include: point load; Schmidt hammer hardness; abrasion hardness; and total hardness. The first two index properties correlate to uniaxial compressive strength (UCS) and Young's modulus. Discussions are given on empirical, normalized relationships of UCS to rock mass properties and the integrated use with semi-empirical, geotechnical design methods. The hardness property indices correlate to construction performance parameters and some relevant experience is cited. Examples of data are presented from an index testing program carried out primarily on siltstone, sandstone and limestone rock core samples retrieved from depths up to 1005 m (3300 ft) in a borehole drilled in the Paradox Basin of eastern Utah. The borehole coring was done for a nuclear waste repository site investigation.

Jan 1, 1990

By B. J. Sauer

Misapplication of ac induction motors for mine crusher and mill applications has long been a frustration for the driven equipment supplier and the mine operator. Proper selection of ac induction motors is critical to providing efficient production. This paper focuses on the selection of ac induction motors for gyratory crusher, conecrusher and grinding mill applications. The criteria for motor selection includes: proper enclosure, driven equipment torque requirements, bearing life, temperature rise, starting requirements, ambient temperature, altitude and accessory requirements.

Jan 1, 2002

By Sukumar Bandopadhyay

A present dominant problem is that of high downtime of the longwall shearer used in the coal production process. The means by which this problem can be overcome are many, but one of, the most important ones is that the-use of an expert system can reduce diagnostic and repair time. In this paper, a fault-diagnostic expert system model is presented. Specifically, the diagnostic architecture of the longwall shearer expert system and its use for diagnostic reasoning are discussed.

Jan 1, 1989

By J. Cheung, H. Rabia

The traditional methods for predicting mine air temperatures are based on steady state heat transfer models as developed by Voss (1969) and Starfield (1983). These models are useful in providing approximate predictions of air temperatures in trunk and gate roadways. More complex models are required to provide predictions along faces. In practice, the heat flow in underground mines is of transient nature and recent observations in some British Coal mines show temperature variations of up to 5°C during a working week at any one point. In addition, the recent introduction of district recirculation of mine air in British mines requires a more precise prediction of air temperatures during start up of the system or during breakdown. A transient heat transfer theory based on the work of Jordon is presented. The method lends itself easily to computers due to the large number of calculations involved. The proposed transient model is validated using actual temperature data collected in roadways in Wearmouth Colliery in the North East of England. The transient results are compared with the steady state predictions of Voss (1969). Finally, predictions of air temperature in roadways for a recirculation system will be made using both the transient and steady state models. Temperature predictions along faces will be made using a separate model.

Jan 1, 1989

By Frank T. Wheby, Edward M. Cikanek

A computer performs all logic and computations customarily done by hand in preparation of engineers' estimates or contractors' bids on tunnel-shaft systems. The program described is based on construction methods, work forces and equipment selections corresponding to the current state-of-the-art of rock, soft ground and cut-and-cover tunneling. The program contains logic to permit estimates of cost of complicated tunnel-shaft systems; it is not necessary to input quantities, as the program calculates those from the tunnel design that is internally generated. In any estimate, the program bases its cost computation on user-input requirements and site conditions, such as tunnel shape and size, shaft depth, ground characteristics, construction methods, and other factors. To provide great flexibility, the user of the program is provided with options for accepting designs built into the program or overriding these designs by his own inputs. An illustrative example is presented.

Jan 1, 1974

By Edmond Donovan, O&apos

With the increase in complexity of conveyor systems and the inexorable demand for more capacity and availability, the ability of designers to accurately predict performance is becoming increasingly important. Dynamic analysis techniques for modelling wave mechanics in conveyors are finding increased applications. Unfortunately, the reliability of these modelling techniques is dependent on a thorough understanding of the performance characteristics of the components that make up the system. These characteristics include such things as response rate, hysteresis and efficiency. Some parameters such as idler rolling resistance can be easily quantified by measurement. More complicated drive parameters are difficult or impossible to measure, particularly in large horse-power equipment. One method of quantifying or at least bracketing the performance envelope of complicated pieces of equipment is to construct a mathematical model. This can be done quickly and economically, and the influence of various parameters can be determined. This paper sets out to demonstrate by example the usefulness of this technique in gaining an understanding of complicated systems. The model is developed and the influence of a number of variables are examined.

Jan 1, 1996

By R. L. Loofbourow, Robert R. Miller

Deep, stable, unlined space promises secure, efficient, acceptable solutions to several current problems. With truly favorable conditions, it can be economic as well. The basic requirement is sufficient sound, tight rock at required depth. This and unusual surface requirements point to special testing. An objective is to describe conditions for planners, estimators and contracts. A first stage concept study needn't be prolonged but should overlook nothing significant. Although observations and tests on core are considered essential, time and expense can be cut by supplementing then with tests on walls of rotary or percussion holes. In some places initial drilling could be shallow.

Jan 1, 1981

By Raj K. Rajamani, Ilesh M. Shah

Maintaining pH, a routine requirement in many industrial processes, is by no means trivial. The control is troublesome because of the inherent nonlinearity and frequently changing process dynamics. Many researchers in the past have investigated advanced on-line estimation and/or adaptive control techniques to overcome these difficulties. Most methods require the development of a complex mathematical model. The present work deals with the use of a simple and elegant method for pH control, based on the use of fuzzy logic. First, a standard fuzzy-logic controller is discussed, followed by a self-organizing controller. The latter algorithm generates a set of rules based on observation of the process. Thus it is a learning algorithm. The development and application of the algorithms to a laboratory acid-base neutralization experiment are presented. This elegant technique is powerful and deserves attention in mineral pro- cessing.

Jan 1, 1990

By Angela Binder, Oliver Langefeld

"The future of mining will be characterized not only by the application of modern technology, but also by the harmonization of economic, environmental and social issues. These areas set major future challenges which are complex and demand extensive knowledge. As an example, mining of highly complex orebodies for the supply of often critical raw materials, needs to consider technically demanding and cost-intensive extraction issues. The amount of tailings, which need to be stored, increases with the amount of ore mined. Therefore, the negative impact on environment and society increases. Hence mining becomes expensive with regard to all three aspects: economy, environment and society. In view of a sustainable mining practice this challenge should be used as an opportunity. The positive impact should be maximized for present and future generations. The objective is to create and use the mining openings in an optimum way related to sustainability. The approach of Blue Mining, which focuses on energy and ergonomics in the field of Sustainable Development, enhances the closure planning by recommending subsequent usage of such openings for energy storage. The approach fosters among others the implementation of the 7th Goal for Sustainable Development defined by the United Nations with the assurance of access to affordable, reliable, sustainable and modern energy for all. The usage of underground storage increases the stability of solar and water power usage, which are otherwise unreliable. Blue Mining embeds these issues in the main planning effort long before groundbreaking. This approach involves experience from past and current projects. This paper introduces the concept of Blue Mining with respect to post-mining utilization of a mine for energy storage. Methods and perspectives are presented with examples covering best-practices and lessons-learned."

Jan 1, 2017

By B. J. Scheiner

The Bureau of Mines, U.S. Department of the Interior, has investigated the use of rheology to provide insight into the mechanism of flocculation. A technique developed by Tattersall has been modified and used to explain the flocculation of calcium montmorillonite with polyethylene oxide. The results indicated that there are two types of bond systems operating during the flocculation sequence. Also, flocculation results are highly dependent on the shear rate and the amount of polymer added.

Jan 1, 1989

By A. J. Richardson

Before the development of the underground stoping and mining costs can be considered, certain facts about the ore body, the proposed mine, markets, etc., must be known or determined. In the case to be studied, the zinc-lead mineralization occurred with a narrow vertically dipping structure of undetermined length and vertical extent. Exploration completed to date has revealed 6.5 mil¬lion st t of proven reserves. A further 820,000 st of in¬dicated reserves has been outlined and this tonnage is considered capable of being expanded by a factor of approximately four after more detailed drilling. After studying the market conditions and completing a very preliminary feasibility study, it was decided that production would be 730,000 stpy (or 2000 stpd) of ore. First year production would be at the rate of 1500 stpd. The main design criteria for the selection of the min¬ing methods are minimizing surface subsidence, maxi¬mum recovery of the ore body, maximum degree of grade control, maximum productivity, and safe working conditions. Two basic extraction systems are considered capable of meeting these requirements: mechanized cut¬and-fill stoping and sublevel long-hole stoping with filling. The primary development system of the mine has been designed to give maximum flexibility in stoping systems and layout and to permit changes if considered necessary as a consequence of actual production ex¬perience. At the present time, access to the mine is by a circu¬lar concrete lined vertical shaft, 16 ft diam, sunk to a depth of 1380 ft. Two exploration levels have been driven within the ore zone at depths of 165 and 1246 ft below the surface outcrop. The development to date had the objective of sampling the mineralization and produc¬ing detailed information on the outline of the ore body and the distribution and controls of zinc and lead values. In an attempt to satisfy the basic design criteria for the mine, it was decided that production would be best achieved by a combination of 40% sublevel long-hole stoping and 60% cut-and-fill mining. Costs of exploration and capital development of per¬manent underground facilities are normally written off over the life of a mine. Production expenditures, on the other hand, are of a temporary nature and are normally charged as and when incurred as an operating expense. Reasonably accurate predictions of mine production costs can be built up from engineering design and estimates of individual mine activities for ultimate inclusion in the comprehen¬sive data required for financial decision making. The simulated operations can be costed on a detailed basis in the form of a monthly operating budget. The budget format can be generalized or detailed, depending upon the scope of the project. However, ex¬perience suggests that a fairly detailed format has the advantage of assuring that all significant cost items are included. For underground costing it is suggested that the budget structure include five major cost centers (i.e. development, diamond drilling, ore extraction, hoisting/ transportation, and general mine expense). These in turn are detailed under numerous subheadings. The mechanism for compiling an operating budget will be illustrated. Because of its relative simplicity, ore extraction under sublevel long-hole stoping has been chosen for illustration. All other activities, simple or complex, can be estimated in similar fashion. BLOCK AND STOPE DEVELOPMENT Long-hole blocks, used where advantageous, will be up to 250 ft in height, depending upon the vertical con¬tinuity of the mineralization, and approximately 300 ft long. Drawpoints will be at 36-ft intervals and serviced by loading crosscuts driven from a footwall drift parallel to and close to the ore zone. Pillars between the stopes will be 50 ft wide. Stopes will be drilled off with vertical rings of blastholes drilled from sublevels approximately 60 ft apart vertically. This drilling will be done by percussion drilling machines (31/2 in.) mounted on a trackless drilling rig. Load¬haul-dump (LHD) equipment will be used to move broken ore from the drawpoints to the orepass connecting to rail haulage systems. On completion, long-hole stopes will be backfilled to prevent caving and to facili¬tate later pillar removal. From a planned stope layout, a forecast of produc¬tion and development is made in Table 1. Table 1. Block Tonnage and Stope Development Quantity Ore Waste Total ore block 375,000 st 2 stopes 310,000 st 1 pillar 65,000 st Access crosscuts, 4 at 100 ft 400 ft Drill sublevel drifts, 6 at 300 ft 1800 ft Stope raises, 3 at 250 ft 750 ft Undercut sublevel drifts, 2 at 300 ft 600 ft Loadout crosscuts at 35-ft intervals 550 ft 100 ft 3300 ft 500 ft Total development footage 3800 ft Tons per ft of development 987 st

Jan 1, 1982

By M. L. Nave, R. E. Melley

DC motor drives are available technology for belt conveyors. The success of the application in mining depends on adequate and timely consideration of DC drive features. The purpose of this paper is to familiarize and inform possible mining users of DC drive attributes.

Jan 1, 1996

By S. R. S. Sastri, K. K. Bhattacharya, K. S. Narasimhan

Experimental results obtained on the recovery of below 0.5 x 10-3m coal fines by flotation employing geometrically similar columns of 0.056m, 0.080m, 0.100m and 0.220m diameter have been presented. The hydrodynamics of such a unit as well as its performance have been related to operating parameters to establish optimum conditions. The results have further been analysed critically in the light of the known relationship on the behaviour of similar systems to assign reasons for the critical factors established in a bid to reduce the empiricism required to be followed in the scale up of such a unit.

Jan 1, 1988

By R. Hogg, A. C. Maffei, D. T. Ray

Based on standard population balance models for agglomeration and size reduction processes, a simplified model has been developed to describe simultaneous growth and breakage in the flocculation of agitated suspensions. The results of semi-batch flocculation tests have been used for estimation of the model parameters and empirical relationships have been obtained to describe the effects of process variables and to establish scale-up criteria. Application of the model to the design, operation and control of continuous flocculation processes is discussed.

Jan 1, 1990

By Ching L. Wu, Bolek Chytrowski, Peter Frobenius, Dale Roberts

During the past few years, the first stage of the Waste Isolation Pilot Plant, (WIPP) which consists of an exploratory shaft, a ventilation shaft, shaft stations, access drifts and test rooms, has been under construction. Construction of the first stage is scheduled to be completed in the summer of 1983. The U.S. Department of Energy (DOE) is constructing the WIPP facility to demonstrate the feasibility of disposing of defense-related nuclear waste in the bedded salt deposits of the Delaware Basin near Carlsbad, N.M. The project promises to be a proving ground for underground nuclear waste storage facility design and construction. The completed underground plant will extend over an area of 647,500 m2 (160 acres), and 1,360,500 metric tons (1,500,000 tons) of salt will be excavated. The first stage of the project, the Site and Preliminary Design Validation (SPDV) Program, provides for full-scale construction of the major components of the underground facility. Shaft construction and underground development are described. Rock bolt installation is performed as required for roof control. Geotechnical instrumentation is installed to monitor the behavior of underground openings. Direct observation of the constructed shafts, shaft stations, and underground openings is expected to confirm the adequacy of the underground design and allow full-scale construction of the first U.S. underground nuclear waste storage facility to proceed.

Jan 1, 1983

By Paul H. Lu

This paper proposes a novel method, "integrity factor approach," of mine-pillar stability evaluation based on in situ triaxial-loading measurement. The pillar integrity factor is defined as the quotient resulting from division of integrated total pillar strength across the critical dimension by the integrated total pillar load across the same dimension. The integrity factor is dynamic, while the conventional safety factor is static. With this approach, the pillar stability can be evaluated at any stage of mining progress during panel operation. It automatically considers the progressive failure of the pillar and post-failure strength without the need to clearly define the boundary between yielded and intact zones of the pillar. Based on two case studies, the integrity factor approach is shown to be a practical, effective technique for evaluating stability of conventionally designed pillars. It is suggested that a more realistic estimate of in situ pillar strength could be made based on the combination of in situ triaxial-loading measurements and laboratory true triaxial compression tests, rather than through the traditional combination of biaxial-loading measurements and conventional triaxial compression tests.

Jan 1, 1986

By Ted M. Noskiewicz, James A. Ramsay

INTRODUCTION During the various stages of an underground project from inception through design and construction, probably the single factor of most interest and concern is the nature of the ground. The ground conditions more than any other item govern costs and feasibility; and although the methods available for assessing the ground have become increasingly reliable during the past thirty years, it is still very difficult in many cases to predict the behaviour of soil and rock during and after excavation. To help in this ground evaluation process, we have frequently supplemented the boring program with one or more large diameter inspection holes; and during the past eighteen years, seventeen of these holes have been constructed on tunnel projects which we have designed. There are references in the literature to similar inspection holes (1); however, as far as we are aware, no detailed description of them has been published. The behaviour of soil or rock during and after excavation and the effect of ground water on tunneling operations are of vital interest to tunnel designers and contractors. A comprehensive geotechnical investigation is therefore among the early and most important tasks carried out on a tunnel project and the backbone of every geotechnical investigation is the boring program. A series of borings, typically 50 to 100 mm (21 to 4 in) diameter, are drilled from which soil samples or rock core are recovered and the ground water observed.

Jan 1, 1979

By John T. MacWaters, George H. Milly

INTRODUCTION This paper describes operational procedures and instrumentation which were developed to implement a patented method of detecting and locating uranium ore bodies. All equipment was designed for accurate and reliable use under difficult field conditions. Data resulting from these developments, some of which are incorporated in a companion paper for this conference*, have contributed to our understanding, of the nature and significance of naturally-occurring radon exposures. Further applications of these techniques may prove useful in studying anthropogenic radon in evaluating the significance of variability in radon flux, or in taking proper account of the contribution of natural radon to ambient radon concentrations, particularly in mineralized regions. OPERATIONAL PROCEDURES The uranium search technique employed by GEOMET begins with a [reconnaissance mode], which utilizes a series of ambient air filter samples taken from a moving or standing vehicle to detect anamalous concentrations of radon. These samples are normally taken at night under stable (temperature inversion) or neutral atmospheric conditions, to avoid the rapid dispersion of the radon clouds typical of daytime turbulent conditions. Radon daughters formed by the decay of radon quickly attach to ambient aerosol particles and are captured on the surface of a membrane filter during a five-minute sampling period. The filter is placed in a portable alpha scintillation counter, and a five-minute count is started at a preset time after the completion of the sampling period. This count is followed immediately by a second five-minute count to enable determination of the cloud age, based on consideration of the relative half-lives of the initial radon daughters. With the use of tables computed from the mathematics of the uranium decay process, and with the measured radon background accounted for, the first and second counts are used to estimate the time which has elapsed since the pure radon initially emanated from the earth's surface. This cloud age, combined with wind speed and direction measurements made at the beginning and end of each sample, as well as with an understanding of the effects of local terrain features on wind trajectory, provides an estimate of the Probable location of the source. In practice the reconnaissance mode involves one vehicle with a single operator to take the five-minute samples, moving or standing, along any available roads or trails in the area to be covered. Under the usual nighttime stable conditions the cool air flows downslope and downvalley, and the operator will pay special attention to locations along the axes and confluences of the natural downflow patterns. These facilitate sampling of large air drainage areas. Successful detection of sources of radon based on high concentrations of radon daughters, and substantiated by evidence of "fresh" clouds, are frequently made on the basis of a relatively few samples taken judiciously by an experienced operator during a reconnaissance. At this point he has a choice: he can continue to cover the designated reconnaissance area, leaving the localization of any anomalous radon detections to await the ranking of detections by priority, or he can continue with localization of the detected source, either alone or by radioing for another vehicle to assist in triangulation operations. Localization of a source involves skillful and experienced use of the continuously collected data on concentration, age, and wind speed and direction, together with knowledge of the terrain from observation and contour maps, and exploitation of the available roads. Since age ratios are dependent solely on proximity of the source and wind speed, decreasing [cloud ages] based on statistically significant increasing age ratios represent the most useful. information in localization. The [magnitude of the concentration] of radon daughter products is also useful; however, it may vary widely for a variety of reasons during sampling for a localization, thus making this a secondary parameter for localization. Large values of concentration are of course useful; typical results for successful detection of a strong anomaly would yield alpha counts ranging from 10 to 25 times background values. These counts are convertible to ambient radon concentrations by appropriate consideration of the decay process. Successful localizations of radon sources using this procedure with ambient atmospheric measurements normally will narrow a source location to within an area ranging in size from less than a quarter of a square mile to at most a square mile, and frequently give information on the probable shape of the source (in plan view) on the earth's surface. Judicious use of this procedure could undoubtedly provide finer localization, but the coarser results just described are adequate for this Phase of GEOMET's uranium exploration procedures.

Jan 1, 1981