Search Documents

By Todd A. Duex

The Richmond Hill Mine has recently completed a reclamation plan to mitigate Acid Rock Drainage (ARD) which was identified at the toe of the former waste rock pile in 1992. Reclamation activities began in 1994 with the removal of ARD material from the waste rock pile and placement of this material in the former pit. This material was then isolated from the near surface environment by a low permeability capping system designed to minimize water and oxygen flow into the material. The capping system consists of, from bottom to top, six inches of limestone, 18 inches of low permeability clay liner, 4 and one-half feet of thermal barrier/drain layer, and six inches of topsoil. This capping system was completed in 1995. An extensive program is in place to monitor the effectiveness of the reclamation plan, and includes measurements on moisture content movement, temperature, oxygen content, and groundwater impacts. Monitoring has been ongoing since the completion of reclamation. This monitoring plan is demonstrating the success in isolating the material from the near surface environment and minimizing the impacts to the surrounding environment.

Jan 1, 2000

By Maurício Covcevich Bagatini, Maycon Athayde

Water consumption reduction in pellet feed operation is of paramount importance. Compared with traditional ball mills, high-pressure grinding rolls (HPGR) play an important role in Blaine surface area (BSA) generation to improve agglomeration properties, although stability is still a challenge. Grindability improvement of existing operation has a direct impact on the performance of the filtering and pelletizing operation. The results of this study, as a pregrinding operation, can be applied not only in new operations but also in existing ones, helping the operator control process variation in a more effective way while ore hardness increases. 

By Sarah Holtz Wilson, Kenneth Rossi, Carl R. Handford, David F. Tsztoo

The East Bay Municipal Utility District’s Claremont Tunnel is an 18,000-foot long water tunnel that crosses the Hayward Fault zone near Oakland, California. It was originally completed in 1929. This project involved the construction of a bypass tunnel through the fault zone, including an enlarged vault section designed to accommodate up to 8.5 feet of horizontal offset. Ground conditions encountered included sheared and crushed serpentinite and clayey fault gouge, and presented specific challenges for construction. A special excavation and support sequence used concrete-backfilled side drifts as foundations for the vault steel sets. It also allowed for a 20-foot-wide top heading and bench excavation in soft and squeezing ground conditions.

Jan 1, 2007

By Douglas W. Fuerstenau

This paper concern the specific adsorption of sulfate anions on nonmetallic minerals and its role in flotation. The specific surface affinity of sulfate ions in various systems has been observed in the results of electrokinetic measurements that show conditions under which sodium sulfate can reverse the sign of the zeta potential. The electrical double layer model provides a means for interpreting the results and for estimating the free energy of adsorption of sulfate ions. Because of their surface activity, sulfate ions not only can function as a depressant in the flotation of oxide minerals with physisorbed anionic collectors but also can function as an activator for flotation with physisorbed cationic collectors. Their role in depressing or enhancing the flotation of the sparingly-soluble mineral barite is also explained in terms of the double layer model.

Jan 1, 2005

By M. Javier

In business mining, dilution is the result of the operating parameters that occur too often and cause serious consequences to mine performance, questioning TO WHOM BENEFITS DILUTION. Mining persists in changing perception of real meaning of dilution. The lack of interrelation between mineral processes and nature compromises the understanding of dilution; this absence of interrelation occurs due to the misinterpretation of nature, otherwise, Geomimic could be helpful to filling the gap of misinformation. NATURE provides LIMITED metals in low content deposits; it is a challenge to obtain them. Nature never considers dilution. Furthermore, though dilution is a human concept, dilution is accepted and promoted. Reality of dilution is in its errors accumulation that translates into technology level or status applied in nature. It is doubtful that dilution can continue surviving if it is ?meaningless?. It will discourse: Is dilution illegal? If the change occurs in the prediction of mining will prevail a different destiny, it is important to touch the cores of the business; otherwise, it would represent repetition of the same ?negative? effects, as usual. Mining defines many losses during the disturbance of nature, from NPV elaboration to the metal recovery to commerce, demanding BETTER DESIGN. This paper introduces and applies MANAGEMENT BY LOSS, as first steps, to limit risks and uncertainties in mining. As result, the management of dilution will be obtainable under mining practices which promotes its character of SUSTAINABILITY.

Feb 23, 2014

By J. W. Leonard, C. L. Jiang, B. K. Parekh, X. H. Wang

The selective depression of pyrite from the Kentucky No. 9 coal seam was systematically examined using various kinds of inorganic and organic chemicals. Most of the organic chemicals tested showed little selectivity in pyrite depression. It was found that both orthophosphate and pyrophosphate were effective for the selective depression of coal pyrite in coal flotation using fuel oil as a collector. At substantially low concentrations of pyrophosphate, the flotation of coal pyrite was completely depressed over a wide pH range, while the coal flotation remained unaffected. The mechanism of the selective depression of pyrite by phosphates was explained with the help of thermodynamic calculations of iron-phosphate-water systems and zeta-potential measurements. It was shown that pyrophosphate reacts strongly with the iron ions of pyrite to form stable hydrophilic iron pyrophosphate complexes on pyrite surfaces.

Jan 1, 1999

By Qing Wang

A longterm overburden removal plan can be realistic and optimum only when the cost and capacity profiles off the equipment assigned to the operation are taken into consideration. Therefore, the planning should involve the proper assignment of equipment capacity by insuring a timely investment and a timely replacement policy throughout the mine life. A dynamic solution algorithm has been developed, by which all possible truck fleet alternatives are evaluated for each year off the operation. Cumulative cost off the operation is carried throughout the analysis. The optimum solution is obtained by selecting the minimum cumulative cost at the last year and tracing backward the best fleet alternative for each year. The solution provides: 1. the optimum amount of overburden to be removed each year; 2. the best fleet to be assigned to the job; and 3. the best equipment replacement policy.

Jan 1, 1989

By H. V. S. Tingley

My topic today is future trends in compensation for the mining industry. I seldom get the chance to speak about a subject of such immediate interest to an audience, so I would like to make the most of this opportunity by telling you that everybody in this room will become rich beyond his wildest dreams in the next few years. I would like to open my talk that way, but in compensation, like everything else, there is a great gap between dreams and reality. Back to reality. When we talk about compensation, we?d better define our terms because the compensation is really an umbrella for five basic types of payment made to management personnel. Slide 1 identifies these elements of compensation.

Jan 1, 1980

By Richard R. Klimpel

Introduction Froth flotation is one of the most common unit engineering operations in use today. Its aim is to upgrade the quality of coal by removing ash/pyrite and separating selected minerals from undesired gangue materials. Flotation has been successfully practiced at the industrial scale for more than 50 years. Its use is increasing due to the ever decreasing feed grades of the coals and minerals being processed. Flotation has also shown itself to be a flexible process that lends itself well to many solid/solid separations. Thus, with surprisingly little equipment modification, separations can involve very different particle sizes and densities, and relative weight ratios of materials to be separated. In addition, the flotation process is economic, especially when compared to size reduction, its associated precursor process. Flotation also lends itself to continuous operations with a given equipment configuration. The operation must exhibit an ability to vary feed rate of solid to the process by as much as 50% without a total collapse of separating efficiency. In addition, the mechanical flotation cell is scaleable from 2.8 to 57 or 85 m3 (100 to 2000 or 3000 cu ft) with surprising ease relative to other unit engineering operations over the same relative size increase. The separating medium used is water. Most of the chemicals required - pH regulators, frothers, collectors, activators, and depressants - are all relatively inexpensive and common. They are not usually used in large quantities. Froth flotation is certainly one of the most versatile and forgiving unit operations in the chemical, mining, and agricultural industries. The problem with the industrial flotation process is that it is fairly easy to get reasonable results and relatively difficult to get excellent results. Why is it so difficult to fine tune the froth flotation process? There are some obvious reasons and a few not-so-obvious factors. The obvious category would certainly contain the tendency of natural feed materials (ores and raw coals) to have variable physical, metallurgical, and surface properties. This occurs even when special care is taken to minimize such differences with blending. There is another obvious reason for difficulty. An inherent broadness of the feed particle size range to flotation results from using any of the common industrial-scalefine grinding devices - ball-, rod-, or autogenous mills. Research has been done into the chemical reagent and equipment aspects of flotation. It has shown strong interactions (limitations) of chemical reagents and equipment on larger and smaller particles. The point is that current flotation practice works best on average- or medium-sized feed particles. The greater the amount of large or small particles, or of both large and small, the more difficult it is to achieve excellent flotation results. Other reasonably obvious factors include: • variations in mineral type and liberation sizes; • water chemistry variations such as those involving Ca", C03, or Fe", or various soluble metal cations; • the presence of stray organic materials such as returning soluble reagents or partially degraded reagents in reuse water; • the lack of reliable on-line instrumentation for monitoring and control; • frequent equipment malfunctions of all types; • excessive feed rates for installed plant capacity; • poor operator interaction with the process; and • poor reagent dosage control. There are less obvious, but real limitations to flotation. These are inherent in the design and operating characteristics of the most common cell design in use today - the mechanical flotation cell. Individual performance attributes of the chemical reagents used, along with their manner of use, also carry limitations. The bulk of this paper will deal with chemical reagents and their use. Chemical reagents In 1979, the author and his co-workers were asked to invent and implement, at the industrial scale, new flotation reagent chemistry. After reviewing some of the literature (Sutherland and Wark, 1955; Klassen and Mokrousov, 1959; M. Fuerstenau, 1962; D. Fuerstenau, 1976; and Leja, 1982), a series of carefully controlled plant scale tests were set up. These tests were designed to understand existing reagent scale-up from the laboratory to the plant. They were to quantify at the plant level the effect of some of the more important, controllable chemical reagent factors (frother and collector type, frother and collector dosage, pH effects). This is a learning experience that all researchers involved in flotation theory should experience. It quickly became apparent that: • because a factor is important

Jan 12, 1988

By Heriban Soto

Primary amines are strong collectors of apatites and they can selectively float sedimentary phosphates from calcareous ores. However, secondary and tertiary amines and tri-methyl ammonium salts were ineffective. The use of kerosene reduces the collector requirements because hydrocarbon is coadsorbed along with the amine on the mineral surface. The heats of reaction of aminium ions with such anions as phosphate, carbonate and sulfate, were measured in a microcalorimeter and discussed in terms of the solubility of the precipitates formed and their relationship with the adsorption mechanism of primary amines on phosphate minerals. Experimental evidence supports a view that primary amines are adsorbed through chemical interaction between the aminium and phosphate ions at the mineral surface.

Jan 1, 1984

By J. D. Scott

This paper consists of a review of the development and application of spherical charge blasting at Inco Metals Company. Topics will include the Livingston Strain Equation, the field data required for its use in full scale operation, the type of ground in which mining has been carried out, explosives in use and their characteristics and finally, an overview of actual production applications. These applications include Primary Stope Mining, Secondary Mining Against Fill, Mining a Faulted Ore Zone and Drop Raise Blasting. INTRODUCTION Crater blasting in itself has been in use for over twenty years, but only recently has the technique been combined with a spherical size charge to form the Vertical Retreat Mining Method. This article endeavours to put the Livingston Strain Equation in a practical light, to describe several actual hard rock applications, and the results achieved in each case. THE LIVINGSTON STRAIN ENERGY EQUATION C.W. Livingston put forward the following equation as a standard means of determining the optimum burden required for full crater production blasting. The constant "E" is included in an attempt to recognize secondary breakage caused by strain waves.

Jan 1, 1981

By Clinton Strachan, Rob Dorey

10.1 INTRODUCTION This chapter presents considerations which should be applied to heap leach pad site selection, site evaluation, and design, relative to the geotechnics of the site and ore. 10.1.1 General Guidelines are presented covering the topics encountered in design and construction of heap leach faci1ities. Because geotechnical characteristics vary from site to site, not all geotechnical topics associated with a specific heap leach facility are presented, and there may be exceptions to some of these guidelines. The general features of a heap leach facility (from Chapter 1) to be discussed in this chapter are: • Leach pad (including leach pad foundation and liner); • Heap; • Solution storage faci1ities (for pregnant and barren process solutions) ; and • Solution collection facilities (which collect and convey solutions in the heap and convey them to solution storage facilities). These general features are illustrated in Figure 10.1. Liners for these facilities are discussed in Chapter 11. Solution application systems and the sizing aspects of solution storage facilities are discussed in Chapters 6, 7, and 12. The general features listed above are constructed with and overlie naturally occurring materials (such as ore, borrow soils, and subsurface soils and rock). These natural materials are relied upon to perform in an acceptable manner as a component of the leach facility (such as the liner, drain material, and foundation).

Jan 1, 1988

By K. R. Gardner, P. B. Altringer, R. H. Lien

The Bureau of Mines, U. S. Department of the Interior, is investigating biological and chemical reduction of selenate and selenite from waste waters. A mixed bacterial culture, isolated from agricultural waters, removed selenium from four oxidized cyanide solutions from precious metals operations containing 0.6 to 30 ppm Se and 13 ppm CN. Up to 85% selenium removal was attained using bacteria under controlled batch conditions in a 3-L stirred tank reactor and in small-scale continuous tests conducted in a rotating biological contactor (RBC). Fe(OH), reduction of the selenium reduced the effluent concentration to 0.02 ppm Se; however, the reagent costs were prohibitive. A final processing scheme may involve a combination of biological and chemical treatments.

Jan 1, 1991

By Jr. Gambrell

Support characteristics of in-cycle trusses are analyzed using a photo-elastic model loaded by tightening a truss in the sequence normally used in an underground mine. Stresses in the roof at its center point and at the junction of the roof and rib are examined. Effects of zero tension and unequal tension in the inclined anchor rods are presented. Effects of simulated subsidence on stress in the roof surface and on tension in the separate truss members are examined. Conclusions are drawn relating to (1) the effects of tension in the inclined anchor rods on uplift and compressive stress parallel to the roof surface, (2) the effects of subsidence on stress in the roof surface and, (3) the effects of subsidence on tension in the truss members.

Jan 1, 1989

By M. J. Meulendyke

An extensive program of marked ball wear testing (MBWT), laboratory corrosion studies, and worn ball surface analyses has been used to gain insight about the role of corrosion in the overall wear process. In some environments, localized corrosion is observed; the actual wear mechanisms in such cases are pitting/spalling and abrasion. Factors affecting the occurrence of pitting include the abrasiveness of the ore, corrosivity of the slurry, corrosion resistance of the media, and galvanic coupling effects. Elimination of pitting substantially improves overall wear resistance. When pitting is not observed, the contributions of general corrosion are significantly less.

Jan 1, 1984

By O. P. Burghardt

Blast furnaces of high specific throughput capacities producing 10,000 tpd of pig iron or even more, require burden materials which, because of their chemical, physical and metallurgical properties, guarantee such high performances. Meanwhile, it should be generally accepted that for evaluating the quality of iron ore pellets, it is not sufficient to know the chemical analysis and the physical properties, i.e. grain size distribution, cold compression strength and abrasion of the fired pellets. It is indispensable to determine the metallurgical properties indicated by swelling, reduction-softening under load and reducibility, as well as grain disintegration in the low-temperature range in the beginning of reduction. By introducing new test methods, and in the face of the need to meet more strict requirements, pellet producers are being confronted with steadily increasing tasks and problems which require a deepening of our knowledge of the ways and means of making high-quality iron ore pellets.

Jan 1, 1975

By M. Selamat, J. Nirdosh, S. V. Muthuswami

High-grade uranium ores of Cluff Lake and Key Lake mines from the province of Saskatchewan in Canada are treated with nitric and hydrochloric acids with the objective of leaching 230 Th and 226Ra simultaneously with uranium to produce environmentally safe mill tailings, h is found that optimum conditions for uranium leaching are 50°C, 4 h, 30% solids in leach slurry and an acid concentration of 1 mol/L for HNO, for both the ores. In the case of HCl, a 3 mol/L acid concentration is needed and addition of an oxidant is required because otherwise 230Th and 226Ra extractions remain poor.

Jan 1, 1990

By R. Scheffel, R. Washnock, G. Zarate

"The second survey of global copper leaching operations has been completed, the data published in 1998 has been updated. A survey questionnaire was sent to 40 identified copper leach operations around the world including those leach properties still in operation that responded to the 1998 survey. This paper lists the results of 26 operations that responded to the survey. Selected information from the survey is represented in graphical form. INTRODUCTION Copper leaching was first performed by truck dumping huge monolithic stockpiles of ore and flooding the surface with leach solution or lixiviant with little understanding to the parameters that support optimum recovery of the metal. Heap leaching has evolved into a controlled process whereby a complex low grade ore is stacked in shallow lifts (under 10 m in most cases). The ore is usually crushed and agglomerated, conveyor stacked on an engineered containment system (leach pad) and irrigated in a controlled manner. The lixiviant chemistry is designed to extract the optimum amount of metal from the ore. At first glance, heap leaching appears to be simple in nature. In fact, it is a very complex process. A plethora of technologies such as material handling, environmental control, analytical techniques, solution chemistry, hydrology and many others contribute to the design and operation of a heap leach. Heap leaching requires an inter-disciplinary approach between geologists, mining engineers and metallurgists. Many operational factors affect heap leaching. The process must address climatic factors, flexible operation, quality control before and after leaching, physical characteristics of the ore, geology, mineralogy, reagent consumption, solution application rate and methods (wobblers or emitters), particle size, and favorable conditions for bacterial growth and survival. Predicting, troubleshooting, and optimization of leach recovery is a significant challenge when considering the number of variables involved and their interactions The survey updates many of these key operating parameters to the current state of the art. It should provide the reader an excellent benchmarking summary of these factors on a site-by-site basis."

Jan 1, 2016

By Steve Stuart

Deep-sea mineral SMS deposits present some of the world’s most challenging conditions for drilling equipment. As robotic seabed drilling services mature so too the ways that clients engage with service providers to maximise their data requirements. This presentation reviews key considerations for planning and executing a successful seabeddrilling program in variable mineralised deposits. Some of the means of collaboration between robotic seabed drilling contractors and those hiring their services are explored; where improved efficiencies and recoveries over the period of a drilling programme could be achieved. Potentially new technology or methodology can be looked at to further improve these approaches.

Sep 1, 2014

By G. H. Friedrich

The distribution of mercury in soils, rocks, and ore was studied in three areas of the Pachuca-Real del Monte District: (1) An area north of the town of Pachuca where ore veins have been found at or near the surface. The mercury content of soil samples taken near the vein zones is far above the background value. The highest value was 1900 ppb (parts per billion) mercury in a soil sample above Veta Vizcaina; the background is about 50 ppb Hg. (2) In the area north of the town of Real del Monte where only a few of the veins are known to crop-out. Regardless of exposure, soils collected over veins show anomalous mercury values ranging from 250 ppb to 1900 ppb. (3) In an area south of the town of Real del Monte. Here, although vein outcrops are lacking, mineralization is known at a depth of about 120 m. All soil samples taken at 50 m. intervals along an east-west traverse contain anomalous amounts of mercury, with peaks corresponding with the known location of the veins.

Jan 1, 1965