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By Martial P. Corriveau

The preparation of coal is essentially the same for export as it is for the domestic market. The big difference, I would say, is that, while coal for certain domestic uses (utilities, for instance) need not always be of the highest quality, as long as it is uniform, the buyer of coal for export invariably demands a well-prepared, top-quality product. And he is willing to pay for it, as long as he knows what he is buying. This is where quality control enters the picture. The day is long past since the export market was the dumping ground for coals which could not be sold on the domestic market. Today, the export buyer wants American coals not so much for a price but for the necessity of blending the American coals with foreign coals to achieve the desired chemical and/or physical characteristics, To blend intelligently, he must know in detail what are the qualities of the coals to be blended. Sampling and chemical analysis facilities at the piers provide the information on the coals exported, These facilities are maintained for the export buyer by independent laboratories; however, in one instance, the buyer operates his own laboratory. With very few exceptions, and Clinchfield?s Moss No. 3 mid-volatile coal is one, cargoes shipped overseas are loaded as blends of two or more coals. Up to now, foreign requirements have not been too clearly defined; therefore, shippers must be prepared to blend mixtures of the desired combination. Successful blending requires an accurate knowledge of the coals shipped. And this makes it necessary for the coal producer to maintain his own control laboratory.

Jan 1, 1959

By D. A. Norrgran, J. N. Orlich

Described is the application of high- intensity magnetic separation throughout the spectrum of industrial minerals. Performed either wet or dry, the separation has application in both the recovery and concentration of value minerals and in removing deleterious mineral constituents. The various types of magnetic separators along with the design and operating parameters relative to separation response are characterized. The characteristics of specific minerals to magnetic collection and the production of high-grade concentrates are described. Laboratory, pilot-scale, and plant studies carried out on a variety of industrial minerals have demonstrated the effectiveness of magnetic separation as either a primary or a secondary unit operation to achieve product quality.

Jan 1, 1987

By S. Zaman, F. F. Aplan, Franklin T. Davis

This section deals with the oxides of heavy metals, namely, columbium and tantalum, rare earths, chrome, manganese, titanium, tin, and tungsten. Table I contains the production figures for each of these commodities in the US and in the world in 1977. Specifications for concentrates are also summarized as well as prices for concentrates in 1977. In each chapter an attempt has been made to describe the more common commercial mineral involved with the commodity and the processes used to recover and concentrate the minerals, as well as geographical areas where these processes are utilized.

Jan 1, 1985

By Bern Klein, Richard W. Lawrence, Scott Frostad

Laboratory and field scale kinetic testing was conducted to evaluate scaling up of laboratory data. Two 20- tonne (field) cells were monitored for internal temperature, pH, conductivity, volume and rate of flow, and water quality. On a surface are. basis, results showed sulfide oxidation rates obtained using 50-kg cells are more sensitive to changes in aeration than those from 1-kg cells. Correcting the laboratory oxidation rates for field temperatures with a pH 7 activation energy, which is in the field drainage pH range, returned oxidation rates an order of magnitude lower than the field cell rates.

Jan 1, 2000

By S. J. Ripke

To pelletize fine moist magnetite concentrate, a 40% water slurry must be dewatered to about 10% by filtration, before it can be agglomerated into pellets. Slurry pH, typically ranging from 8 to 11, gives the magnetite particle surface a strong negative charge and thus causes two adverse effects. First, this negative charge attracts calcium and magnesium cations, which strongly retard the effectiveness of the bentonite clay binder added during agglomeration. Second, a repulsive force created by the negative charge functions as a dispersant that reduces filtering production rates. Tests were conducted to remove these cations during filtration, by rinsing the moisture remaining in the filter cake with a small amount of water adjusted to pH 6 with HCl. Laboratory work was also conducted at Michigan Technological University (MTU) and at Cliff’s Mining Services Company (CMSC) to corroborate the plant tests. In some cases HCl caused filter bag blinding, therefore CO2was investigated to reduce pH. The CMSC lab tests showed that using carbon dioxide to reduce slurry pH from 7.6 to 7.0 improved filtering production rates by 11%. Plant-scale filtering rates were improved by 23.7% when carbon dioxide addition reduced the slurry pH from 8.6 to 6.7.

Jan 1, 2004

By Bruce B. Hanshaw

The Tertiary carbonate aquifer of central Florida is composed of about 2/3 calcite and 1/3 dolomite with minor amounts of quartz and apatite. The Mg content of the calcite is lower in the recharge areas than in the deeper confined parts of the aquifer system. Various geochemical lines of evidence indicate that much of the dolomite is of penecontemporaneous origin but that some may have been formed much later, possibly by ground water. Theoretical studies indicate that the Mg/Ca ratio in solutions is about unity for the three-phase equilibrium, calcite-dolomite-water. Solutions, such as ocean water and some subsurface brines, have Mg/Ca ratios higher than one and should represent dolomitizing solutions. In the areas of principal recharge to the Floridan aquifer, ground water is undersaturated with respect to both calcite and dolomite, and the Mg/Ca ratiois as low as 0.05. As the water moves downgradient, the Mg/Ca ratio systematically increases and approaches unity; saturation of the solution with respect to both calcite and dolomite also increases with length of travel in the system. Thus, in the zone of active potable-water circulation, the chemical process is one of dissolution of minerals until saturation is reached or exceeded. However, in the deeper brackish-water zones that underlie peninsular Florida, dolomite may be forming where the Mg/Ca ratio is greater than one. The necessary Mg may be derived from ocean water or brines recycled through the system as the hydrologic regimen is changed. The driving force may be simple mixing, relative fluctuations of sea level, or a combination of mechanisms.

Jan 1, 1972

By Richard L. Coleman

El trabajo de ensayo metalúrgico para desarrollar un flujograma es el que ahora describimos, comenzando con una información experimentada requerida en todo momento hasta llegar a un esquema final de flujo de un proceso. Tanto las pruebas de laboratorio como de planta piloto son revisadas adecuadamente sobre las experiencias anteriores.

Jan 1, 1982

By A. J. P. Durham

Two low water flux test covers were placed on acid generating waste rack dumps at the Kidston Gold Mine in Queensland, Australia The climate is semi arid with distinct wet/dry seasons. The present study was initiated to develop a cover system to restrict infiltration. The design of the cover required optimization of water storage and evapotranspiration. Instrumentation was installed on both dumps to measure infiltration, moisture conditions and climatic parameters. Field measurements over the last three years indicate that both covers are performing satisfactorily. Selection of the final cover for closure is described on the basis of these results.

Jan 1, 2000

By J. Fuller, L. Marsden

Windborne dust from alkaline salt flats and mining-related tailings ponds is especially prone to threaten applicable ambient air quality standards. Sodium carbonate crystals, typically present, weather to an exceedingly fine, non-cohesive dust, causing air quality problems for miles downwind. Recently developed specialized polymers react with alkaline dust to form sturdy, wind-resistant crusts with good longevity. An on-going demonstration project at a major trona facility has developed techniques for cost-effective application of these polymers over large areas of soft tailings or sediments in a wide variety of situations. Recently treated areas on the order of 80 acres show effective suppression of dust.

Jan 1, 2004

By William R. Barton

The domestic portland cement industry consumes more than 12 million tons annually of raw materials chemically similar to fly ash. How these materials are used and how fly ash can serve in their place are discussed. Factors influencing whether or not a particular plant will use fly ash in place of an alternate material are discussed.

Jan 1, 1968

By Gordon M. Pugh, David G. Rasmussen

INTRODUCTION The two unit operations in cut-and-fill stoping that would benefit most from increased mechanization are drilling blastholes and moving broken ore to the ore¬passes. Drilling in current practice is done with hand¬held jackleg and stoper drills. Broken ore is commonly moved from the face to the orepass by a small slusher. This type of equipment can be easily moved through the raises. Hand-held drills have a slow drilling rate and require one operator for each machine. Drilling can be done much faster by small jumbo-mounted machines as two or more drills can be operated by one miner. Load-haul-dump (LHD) units move broken ore from the face to one or more orepasses at a much faster rate with less loss and dilution than slushers. These units are mobile and may be used at more than one place during a shift. The problem which must be overcome in applying this higher degree of mechanization is the restricted means of access inherent in current practices. Cut-and¬fill methods are usually applied to mining veins that are narrow, irregular in dip and strike, or where ground con¬ditions require the support of sand fill. The mechanized equipment which is needed to accomplish high produc¬tion cannot be raised or lowered through raises without being disassembled. A jumbo which will give the desired performance would be mounted on a rubber-tired carriage with a diesel engine for propulsion. Twin hydraulic booms run by a small air motor would carry pneumatic drills. Over¬all dimensions of the unit would be about 8 m (26 ft) in length, 1.6 m (5'/z ft) in width, and 1.6 m (5'/z ft) in height. An LHD of the desired capacity would be rubber¬tired and either diesel or electric-powered. The overall dimensions of a 2.3-m (3-cu yd) unit will be about 8 m (26 ft) in length, 1.8 m (6 ft) in width, and 1.5 m (5 ft) in height. It will weigh about 12 700 kg (28,000 1b). It can readily be seen that conventional raises can¬not handle this size equipment. The most desirable means of access enables equipment to be driven into the stoping areas. Ramps can enter the stope by being driven upward in the vein walls or by being developed in the vein on top of the fill as the stope advances. This ramp system not only permits the use of rubber-tired equipment in multiple working places but also enables its removal for repairs without component breakdown. In the proposed method, as in conventional cut-and¬fill stoping, sand fill will replace the mined-out ore. By constructing an inclined timber floor at one end of the stope, a ramp can be maintained on top of the fill and advanced as the stope is advanced cut by cut (Fig. 1). The ramp is, therefore, developed during the stoping process and is only driven as a tunnel when rising over and around the sill and crown pillars. A stoping section consists of three blocks of different geometric shapes. The first and last blocks to be mined will be triangular in the plane of the vein, and the blocks between will have the shape of parallelograms (Fig. 1). The first block will develop the initial ramp by breast stoping and filling to the ramp floor (Fig. 2). The ramp will need to be completed through to the next level be¬fore stoping of the subsequent block can begin. The subsequent blocks are mined by back stoping with the next ramp being developed at the other end of that block (Fig. 3). The length of each subsequent block can be varied without changing the slope of the ramp. As the new ramp is developed, the previous ramp is filled along with the stope cut. Access up and down is maintained through the stope. The final block is again breast stoped as no new ramp will be developed at the end line for jumbo egress. Boreholes provide ventilation between levels as well as utility access. They can also provide a secondary escapeway for personnel during periods of development. These boreholes would be located about 3 to 4.5 m (10 to 15 ft) in the footwall and spaced about 183 m (600 ft) apart along the vein. The orepasses are spaced about 61 m (200 ft) apart in the vein. This spacing allows not only a short tram for the LHD unit but also provides surge capacity for the ore between haulage trains. These passes are raised from the haulage levels. As development progresses, the raises are driven through the sill pillar, and then car¬ried in the fill as stoping progresses. Ventilation and utilities can be maintained through an orepass when it is not needed for ore. The end line orepasses are intended for this purpose as well as for personnel emergency egress. Overall dimensions and criteria assumed to illustrate the ramp method of access in a highly mechanized cut¬and-fill stope are: haulage level spacing of 61 m (200 ft); ramp gradient of 17%; average dip of approximately 1.57 rad (90°); initial stope length of 358 m (1177 ft); subsequent stope length of 179 m (588 ft); average stoping width of 3 m (10 ft) ; sill pillar thickness of 3.6 m (12 ft); crown pillar thickness of 1.8 m (6 ft); bored raises of 1.5-m (5-ft) diam; and cribbed orepasses of 1.2 x 1.2 m (4 x 4 ft) through the sill pillar and 1.2 m (4 ft) square inside the cribbed portion. DEVELOPMENT The ramp access system lends itself well to conduct¬ing the several phases of development concurrently. Haulage Drifts and Raises The first development step will be to drive the 3 x 3-m (10 x 10-ft) haulage drifts above and below

Jan 1, 1982

By William H. Mount

INTRODUCTION The requirements of mine ventilation demand the constant attention of the mine operator. Just as the physical mine structure changes with time, the ventilation requirements of a particular mine change considerably from season to season and even from day to day. No ventilation system can remain adequate indefinitely; and all systems require monitoring and adjustments to achieve proper ventilation. Instead of being given fore- thought and planning, mine-ventilation systems too of- ten are erected hastily, merely to correct an already un- healthy situation. The usual result is an inefficient and costly system that, in some instances, may prove in- effective in providing fresh air to the point of need. The ventilation of mines is a combination of both art and science. The fluid that must be moved is in- visible; its properties change drastically with temperature, barometric pressure, and humidity; and the methods of measurement are not precise. In part, ventilation engineering must rely upon the art of good industrial ventilation experience and sometimes even the trial-and- error method. However, the properties of air can be determined with relatively inexpensive equipment; with some care, measurement accuracies within 5% of the actual values can be obtained. Thus the art of ventilation gradually is being supplanted by improved engineering practices. Although the direction of flow and the volume may not be predicted correctly by airflow equations in every situation, it is better to try to predict the behavior of a given ventilation before installation than to proceed blindly with a system design. When used with the discretion that comes from education and experience, the basic laws of ventilation can provide sub-stantial insight into the design of an air-handling system; and they can prevent wasteful or even dangerous designs from being installed. Since the mine operators who read this text will have varying amounts of exposure to ventilation theory, the basic laws of airflow and of mechanical ventilation are presented in the first section. The emphasis has been placed on the interpretation and use of fan characteristic curves that are supplied by fan manufacturers. Considerable information can be obtained from these fan curves, particularly when they are used with a graphic model of the mine, drift, or duct in which the fan or fans are to be installed. A few minutes spent comparing the various characteristic curves can help the designer obtain the correct fan for the job. However, the under- standing of a few fundamentals is necessary; and this text has been prepared to provide ample and understandable information in a "how-to" style. In subsequent sections of this text, more down-to- earth subjects will be covered, including the problems of air recirculation, relative merits of installing fans in series or in parallel, expected maintenance requirements (vibration, lubrication intervals, etc.), fan noise and some remedies, effect of an inlet bell on the fan per- formance, basic air-measurement techniques and equipment, and similar miscellaneous items. Although this text is not intended to be a comprehensive bible of mine ventilation, it has been prepared as a guide that provides some useful information to individuals responsible for the quality of the underground environment. Every person working underground is en- titled to the safest environment that can be provided within the limitations of existing technology and at a reasonable cost. Adequate ventilation is well within both limits, provided that the system is designed intelligently, in conjunction with the mining plan, and not as an after-

Jan 1, 1982

By C. Vasilescu

Phytotechnologies use plants to remediate various media impacted with different types of contaminants. These technologies can be implemented either in situ or ex situ. The affected media in which phytotechnologies can be applied include soil, sediments, groundwater and surface water. They are best applied at sites with shallow contamination of organic, nutrient, or metal pollutants that are amenable to one of five treatment options: phytoextraction, phytotrans-formation, rhizosphere, bioremediation, phyto-stabilization or rhizofiltration. Phytoremediation can be used along or, in some cases, in place of mechanical cleanup methods. Phytoremediation can be used to clean up metals, pesticides, solvents, explosives, crude oil, polycyclic aromatic hydrocarbons and landfill leachates.

Jan 1, 2006

By L. R. Nelson

Cyprus Pima is a medium-sized open-pit copper mine located 35 km (22 miles) south of Tucson, AZ. The ore body was discovered using geophysical prospecting methods in 1953 and was originally worked as a small underground mine followed by small open-pit operations. As mining equipment grew larger and the economic ore grade dropped, the operation grew in size, through four expansions, to the present 50 500 tpd (56 500 stpd) milling rate. The remaining stripping ratio is about 2.5 to 1. Mining equipment includes 11 electric shovels ranging in size from 6 to 15 m3 (8 to 20 cu yd) and 42 diesel-electric haulage trucks ranging in size from 89 to 223 t (100 to 250 st). Mine planning is performed at Cyprus Pima to serve several functions. The most important is to plan ahead, one year at a time, to predict the ore grade and stripping requirements on a month-by-month schedule. This yearly plan is necessary for budget preparation and is revised once each quarter to incorporate variations in actual production experienced during the preceding quarter.

Jan 1, 1979

By Stephen P. E. Redmond

A 15 km water supply tunnel is being constructed in Buenos Aires, Argentinata expand the capacity of the existing system. Two 4.3 meter diameter Earth Pressure Balance (EPB) tunneling machines operating at times from the same shaft on a congested work site and advancing through sedimentary deposits underlying this wonderful city pose interesting challenges. As of January 1999approximately 50% of the tunnel has been excavated. Combined machine production rates of 1026 m/month have been achieved. Presentations made in prior proceedings can be referenced for details of the overall Project scope and for details of the tendering process. The purpose of this paper is to compliment those presentations by addressing now the execution of the work.

Jan 1, 1999

By W. K. Choi

Using electrochemical techniques it was demonstrated that bioleaching of gold from refractory pyritic ores is a complex phenomenon. Many intermediate electrochemical reactions were found to be involved in the oxidation of pyrite, using cyclic voltammetry and carbon paste-pyrite containing electrode. Furthermore, the oxidation process was controlled by solid-state diffusion as suggested by chronoamperometric and chronopotentiometric measurements. Using the Sand's approach, the activation energy of solid-state diffusion was found to be = 22.4 kJ. After bioleaching, 96% gold was extracted from the leach resi¬due with a thiourea solution in 1 hour. A generalized model for the mechanism of pyrite oxidation has been presented.

Jan 1, 1990

By P. R. G. Bak

The integration of interactive computer graphics technology with data analysis tools can assist in the evaluation of deposit models: the super- imposition of mine openings on complex geology can be quickly perceived using dynamic visualisation, colour-coding and transparency control while analysis functions assist in quantifying displayed information. To illustrate the functionality of such integration a research prototype system is presented which allows the interactive visualisation and evaluation of deposit models comprising both structural boundaries and the distribution of continuous properties.

Jan 1, 1992

By C. H. McGuirk

Computerized Preventive Maintenance is important in maintaining consistent and efficient operation in any industry utilizing sophisticated and expensive equipment on a continuous basis. At today's large bulk materials handling facilities, the problems of continuous operation of complex machines with their thousands of components exposed to abrasion, dirt, dust and the elements, are intensified and multiplied. Effective preventive maintenance can increase profits. Yet, the number of tasks to be performed is so staggering that it is beyond error-free human capacity. The computer must be an essential ele¬ment in any efficient and economical preventive maintenance system. Computerized preventive maintenance techniques have been successfully used in many fields, usually involving highly skilled and specialized personnel working under favorable and controlled conditions. Now, The Pittsburgh & Conneaut Dock Company has developed and is applying a computerized preventive maintenance system that is applicable to the bulk materials handling industry. The "system" has taken many years of intensive effort to develop and has been time-tested and proven during the past years on equipment handling materials with rugged physical characteristics and corrosive and abrasive qualities, under some of the most adverse weather conditions on the Great Lakes.

Jan 1, 1976

By J. Fastle, M. Weinstock

The block cave mining method utilized by PT Freeport Indonesia (PTFI) generates fines and allows the inflow of water. Both constituents have contributed to unfavorable characteristics: an increase in ore material plasticity and fluidity. Unfavorable material needs to be monitored and managed as it passes from intermediate ore stockpiles through feeders and then to milling operations. We describe an implementation of several Video Data Analytics (VDA) algorithms on smart cameras to quantify the potential fluidity and plasticity by measuring the apparent velocity and agglomeration of material flowing through ore feeders. This approach to VDA on smart cameras is a cost effective, self-contained, solution to identify these unfavorable characteristics. The solution allows the operators to manage the related operational risks, maintain safe production and govern feeder rates when material is unfavorable, which is expected as PTFI proceeds deeper into the underground orebody

Mar 2, 2022

By T. Yukimasa

Hachinohe smelter, a zinc-lead blast furnace complex with the annual capacity of zinc plus lead of 100,000 tons, had originally treated normal zinc and lead sulfide concentrates. However, it is currently handling a great variety of raw feeds ranging from complex sulfides to oxidic recycled materials in view of resource economy, most of which are unsuitable for zinc electrolysis. This paper reports on some significant efforts recently carried out on improving sintering operation, i.e., the increasing use of secondaries against harmful ingredients like halogens, and the substantial reduction in energy use as the results of various modifications and improvements.

Jan 1, 1982