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By Omar A. Muhtadi

6.1 INTRODUCTION The three most critical factors in successful heap leaching operations are: • The methods employed to pretreat ore (i.e, crushing and agglomeration); • Placement of ore on the leach pad (heap building techniques); and • Wetting of the ore with cyanide (solution application techniques). Improper execution of any of these initial steps may result in a substantial sacrifice of total metal extraction or, in the worst case, in project failure. Ore preparation in terms of crushing and agglomeration was discussed in Chapter 5; this chapter therefore focuses on commonly employed techniques for heap construction and solution application. The main objective of heap construction is to obtain the most homogeneous heap possible. "Channeling" of leachate in heaps with preferential seepage paths leads to preferential leachate distribution and uneven/incomplete extraction. The two main contributing causes of channeling are inadequate attention to heap construction and uneven solution application. These pitfall s can best be avoided through a knowledge of the various techniques available and the applicability and success of these techniques with various ore types and site conditions. The remainder of this chapter provides a discussion on these two subjects. 6.2 HEAP BUILDING TECHNIQUES Successful heap building techniques vary with the type of ore and, since no two orebodies are exactly alike, some slight modifications are usually necessary for each specific project. However, it is possible to generalize in terms of the appropriate techniques to be used with ores having similar characteristics. This section discusses the three most commonly used methods of heap construction and provides some guidelines with regard to ore types, construction constraints, and lift height parameters for each of the three. 6.2.1 Run-of-Mine Dumping and Dozing The run-of-mine method of heap building can only be used with ore of a highly silicious nature (i.e., ore which will not generate a large amount of

Jan 1, 1988

By Timothy P. Smirnoff, Anthony Stirbys, Amanda Elioff

The construction of the continuing expansion of the Los Angeles Metro System has required the construction of eight new station structures. One contractor proposed, as a construction alternative for the support of excavation of the Hollywood/Vine Station, the use of soil-mix walls instead of the conventional soldier piles and wood lagging. Soldier piles and shotcrete or wood lagging support systems had been generally used on the other sub-way station excavations constructed to date throughout the system. Immediately east of that station and in almost exactly the same geology, the Hollywood/Western Station was being excavated at the same time using a conventional support system. This paper com-pares the performance of these two support systems in the alluvial soils of the Los Angeles Basin.

Jan 1, 1997

By M. G. Skowroski, G. G. Eichholz, J. P. Ambrose

Introduction It has long been known that there are extensive deposits of phosphate-bearing deposits in the Coastal Plain of Georgia in many locations that are similar to those being mined commercially in central Florida. A major drilling program was conducted in 1966-67 by the Georgia Geological Survey (GGS). The economic potential of some of the material uncovered was evaluated at that time by a team at Georgia Institute of Technology led by Dr. J.E. Husted. There were some promising results. Since then, there has been little commercial interest in pursuing this matter, though the potential for development remains. In the long term, Georgia's phosphorite deposits could be a major source of income to the state if they were commercially processed. Phosphorite deposits contain significant levels of uranium and thorium. Uranium concentrations in Florida phosphate aggregates have been found to be 120 to 140 ppm. The presence of high concentrations of uranium means that there is a small but finite concentration of radium, which subsequently leads to radon gas emanation. It is the radon emanation and its progeny that may pose the largest health problem in many types of mining. Surface mining operations can possibly elevate the radon and radon daughter concentration in the vicinity. There is always some public concern whether any increase in the radon concentration in the atmosphere by mining (surface mining in the phosphorite case) could elevate the risk of cancer in the nearby population. At the present time, a great deal of attention has been devoted to the possible health effects of radon and its decay products in the inhaled air in mines and inside buildings built on mill tailings or uranium-bearing rock (Gesell and Lowder, 1980). Several evaluations have been published on the potential health effects of the Florida phosphate operations (Guimond and Windham, 1975; Roessler et al., 1980; Travis et al., 1979) and for buildings incorporating phosphate slag aggregates (Kahn, Eichholz, and Clarke, 1983; Roessler, Roessler, and Bolch, 1983). They all indicate that such potential effects are small, but tangible, compared with other radiation effects, for instance in the nuclear industry (Cohen, 1981). In view of the current concern, especially by the US Environmental Protection Agency (EPA), with the radiological consequences of large-scale mining of uranium-bearing phosphate rock (Guimond and Windham, 1975), it was decided to assess the potential radiological consequences if the Georgia deposits were developed. This paper presents an attempt to estimate the magnitude of any radon-based health effects that might arise from future mining operations in selected areas of the Georgia coastal region. To do this, a calculational model was developed that took into account the mining operations themselves, the atmospheric dispersion of the radon released, and the radon daughter concentrations in nearby towns. The model was applied to both extremes. The first application was a hypothetical mining operation in Echols County. Echols County is very sparsely populated and, unless living very close to the site, a person would probably experience little radiation exposure, if any. The model tries to prove this point. The second application was at a site near Savannah, Georgia. Both sites contain economically feasible phosphorite deposits and were not entirely hypothetical in that sense. Site selection In the course of the South Georgia Minerals Program (Furcron, 1967), an extensive series of drill core samples had been collected from various mineral occurrences in the coastal plain. It was found that the cores from the previous drilling program (Furcron, 1967), though carefully preserved, were not readily accessible. But the GGS reports did contain gamma logs of all the holes surveyed. With the cooperation of Dr. Neal Shapiro of the Survey, some core samples were selected and assayed, and used to calibrate the gamma log data. Samples from locations known to have detectable radioactivity were screened and counted. Their measured uranium content was used to calibrate the gamma log profiles for those same holes as obtained by the GGS. On this basis, two of the higher-level sites were selected and the calibration was used to obtain integrated uranium concentrations over the length of the borehole. It is customary to describe radon and radon-daughter concentrations in "working levels" (WL), where one WL represents a concentration of radon daughters capable of releasing 130 000 MeV of alpha particles, equivalent to 100 pCi of radon in equilibrium with its daughters per liter of air. A representative concentration is 0.15 WL, below which radon levels are widely considered to be negligible. For the mine sites selected, the surface area and rock volume were determined to estimate their radon content. Working-level values were then estimated for the assumed radon release from the crushed ore and the exposed surfaces of the mine pit. According to Kisielewski (1980), 93.4% of all radon released from open-pit operations is released from the ore zone; thus, the calculations assumed that those surface areas were the main sources.

Jan 1, 1987

By D. R. Nagaraj

Depression of copper sulfides followed by MoS2 flotation is the most commonly practiced technique for Cu-MO separation. Although numerous organic depressants have been developed in the past, a majority of the currently used copper depressants are inorganic compounds (ex. NaHS, Nokes reagent, etc.). A unique advantage of organic depressants over the inorganic compounds is the potential versatility for design of the organic molecule to suit many requirements. The present study was initiated to systematically investigate the structure- activity relationships for a large number of organic complexing agents in comparison with the commonly used inorganic depressants that are often inefficient and hazardous. The results obtained in this study are discussed in light of the useful correlation obtained between practical solution redox potential and depressant activity. Several requirements, such as the presence of an active -SH and hydrophilic -OH or -COOH in the organic molecule, are identified for a reagent to be a satisfactory depressant. Some preliminary results on the desorbability (or destruction) of collector coating on the sulfide surfaces in the non-xanthate collector systems are also discussed.

Jan 1, 1983

By H. C. Morehead

The United States Cement, along with other industries, is being devastated by an unprecedented penetration of domestic markets by imported products. The overriding questions are: 1. Have foreign manufacturers improved their processes to an extent they can outperform U.S. producers in their home markets? 2. Is it gross inefficiency on the part of the U.S. producers that is allowing foreign producers to be capable of replacing a local U.S. producer in his normal home market? 3. Is there a combination of the first two questions that economically justifies this type of market overrun? The answer is a simple NO!. In a fair trade market atmosphere, U.S. producers are definitely competitive.

Jan 1, 1985

By C. Salcedo, J. Vallance, J. Sáez, M. Robles, J. Spangenberg, S. Rosas, L. Fontboté

The Tambomachay ore deposit (13°28'36.78"S, 71°57'35.98"W, about 6 km north of the town of Cuzco, Peru) consists of Cu hosted in arkosic red beds of the Kayra Formation (Lower Eocene). Bornite, chalcopyrite, chalcocite, covelite, digenite, malachite, and chrysocolla occur disseminated in thin layers and in veinlets. The occurrence of the copper ores in a part of the red bed sequence containing green reducing layers, the presence of organic matter in interstices between the hypogene sulfides, and the sulfur composition of the copper sulfides (δ34S values between -16.9 and -12.4‰ vs VCDT) pointing to bacterial sulfate reduction, are strong arguments to propose that mineralization was caused by copper-bearing oxidizing saline basinal fluids that precipitate copper sulfides when they meet reduced sulfur in an organic matter-rich horizon. Faults parallel to the regional Tambomachay Fault could have acted as feeders for oxidizing basinal copper-bearing fluids. Fluid migration was probably driven by tectonically-induced topography gradient. INTRODUCTION A number of red bed Cu occurrences are known in the Cuzco region in the early Eocene – early Oligocene San Jerónimo Group (Gregory, 1916; Carlotto et al., 1996, 2011; Loza et al., 2004). In the past, copper ores were extracted in several small-scale mines in the surroundings of Cuzco, including Tambomachay, Tipón, and Zurite in the Cusco province and Ushpa, Guilda, Giovanna, and Langui in the Sicuani Province. The abandoned Tambomachay Mine (13°28'36.78"S, 71°57'35.98"W), about 6 km to the north of the town of Cuzco (Romero et al., 2015; Salcedo et al., 2017, Fig. 1) was chosen as the main site for the present research aimed to better study the genesis of these copper occurrences. Results deriving from fieldwork, microscopic characterization of ore and host rock, and sulfur isotope determination suggest that the key factor for the genesis of the copper ores is that copper transported by oxidizing basinal fluids is trapped by reduced sulfur of bacteriogenic origin located in a part of the red bed sequence that shows intercalatins of green reduced horizons.

Jan 1, 2019

By R. O. Burt

The paper examines the role of gravity concentration in both an historical contest and within the modern mineral processing industry. It discusses the principles of the process on both a theoretical and practical level. The importance of ore mineralogy and its effect on the choice of the wide range of equipment available is discussed. The paper concludes with a discussion on the relative merits of gravity concentration to other forms of processing and seeks to answer the classical question - "Quo Vadis?"

Jan 1, 1982

By Dale R. Andrus

Why is there such an increased thrust toward positive multiple use land management and where will it lead? History and purpose of the mining law of 1872. John Marshall discovered gold at Sutter?s mill near Coloma, California, on January 19, 1848, and utter chaos resulted. The great migration of people to the undeveloped western lands had begun. Prior to this discovery, copper, lead, and iron had been the minerals for which the laws were made. With this discovery of gold on the public domain, it became apparent that congressional legislation was necessary. This became even more apparent as each of the numerous mining districts which were springing up in California, and elsewhere in the west adopted local miners' customs to regulate their activities. Although these early miners acted under mining district rules and in some cases state regulations, they were, in reality, appropriating minerals without sanction of federal law.

Jan 1, 1970

By J. H. Canterford

To date, large-scale solution mining has received little attention in Australia, although the potential of this technique has not gone unnoticed. The possibility of long-term damage to the local environment has also been recognized. Because no two orebodies are the same, it is clear that the application of solution mining techniques and the assessment of environ- mental damage will be somewhat different for different orebodies, even though the general principles will be the same. At present the most significant copper solution mining operation in Australia is at the Mammoth (Gun- powder) Mine in northern Queensland. This mine currently produces more than 3 000 t of cement copper a year.1

Jan 1, 1981

By D. A. Bird

Water chemistry data were used to identify the sources of ground-water and surface-water inflow to the IOZ block cave mine. Water samples were collected to obtain vertical and lateral hydrochemical profiles within different levels of the underground workings. Water chemistry data were evaluated in conjunction with geologic and structural information to define controls on locations of ground-water inflows, and to select targets for drilling and interception of water. Drilling has intercepted water-producing zones that were previously unidentified through mapping and drilling. The program has resulted in a reduction in water inflows to the block cave area.

Jan 1, 1998

By Lee A. Goetz

Cost control is a lot like motherhood - everyone proclaims its need and its worthiness, but is it really appreciated and used to successfully complete a project on time and within budget? Good Cost Control is a yardstick - requiring fixed definition but this does not mean rigidity for the project. It provides the means for telling: 1. Where you are going 2. When you will complete and 3. What it will finally cost. Cost Control does not fix the price of dreams nor the cost of projects loosely defined. It does not control costs in itself but provides the tools whereby engineering decisions can be made which will ultimately affect the project cost It does not even guarantee that a project will be completed within the original funds - but only, if this reflects management desires.

Jan 1, 1970

By Art Hamid, Manfred Wong, Carlos Jaramillo, Greg Raines, John Caulfield

"The Central Bayside System Improvement Project (CBSIP) is a critical element of the Sewer System Im-provement Program (SSIP), a 20-year, $6.9-billion investment by the San Francisco Public Utilities Commis-sion (SFPUC) to upgrade San Francisco’s 100+ years old seismically vulnerable combined sewer system. The CBSIP’s centerpiece, a proposed 10,000-foot-long (3,048-meter-long) Channel Tunnel, will provide reliable and redundant gravity conveyance and storage of combined wastewater flows from the northern and central parts of San Francisco to the Southeast Water Pollution Control Plant (SEP) while ensuring compliance with regulatory requirements for combined sewer discharges to the Bay. A tunnel with a diameter of 23 to 30 feet (7 to 9 meter) is being planned using pressurized-face tunnel boring machine technology. Project challenges include tunneling through Franciscan Bedrock, mixed ground conditions in close proximity to the Bay, connector tunnels and shafts, construction in congested urban environment, and challenging real estate issues for shaft access. BACKGROUND AND NEED FOR TUNNEL The City of San Francisco is one of the most beautiful cities in the world. About 850,000 people live in the city and many more come to work, for tourism, and for attending conferences. The SFPUC is a department of the City and County of San Francisco that provides energy, drinking water and wastewater services to San Francisco, wholesale water to three Bay Area counties, and green hydro-electrical and solar power to San Francisco municipal departments. The SFPUC wastewater system includes tunnels, large storage/transport boxes, 1000 miles of collection sewers, 28 pump stations, and three wastewater treatment plants. San Francisco’s combined sewer system collects both wastewater and stormwater in the same sewers, which is then pumped, treated to stringent state standards and discharged into the San Francisco Bay and Pacific Ocean. After decades of service, much of the sewer system is nearing end of its working life. During the 1989 Loma Prieta earthquake, damage to SFPUC water and wastewater infrastructure was extensive. The 11,200-foot-long (3,400-meter-long), 66-inch-diameter (1,676-mm-diameter) Channel Force Main, built in 1976, and a critical component of the SF wastewater system was also damaged. This force main carries 70 percent of the bayside dry weather sewage flow from the northern and central part of the city to the SEP. The force main is at the end of its life and was not constructed to the current seismic code; in addition it has no redundancy. Figure 1 shows the project background and the force main that will be provided redundancy by the new gravity tunnel."

Jan 1, 2016

By Lewis L. Oriard

The authors outline the development and application of blasting methods put into use 11 years ago at the Berkeley Open-Pit Mine, Butte, Montana. The blast design uses a very short delay (5 milliseconds) between detonation of explosives charges, a feature challenged several times in principle despite its success for Anaconda. Concern is expressed over the categorical rejection of very short delay blasting which can make the difference between success and failure of major mining operations. There is ample evidence to show that the method can be used successfully and not violate the concerns of the public.

Jan 1, 1980

By John C. Brower

Bolivia is nor a major gold producer but has produced continuously since pre Inca times. Production reached a peak in 1964 of about 4,000,000 grams and is currently about 1,000,000 grams. Production is mainly from the Tipuani River valley north of La Paz and is derived from Pleistocene basin fill: the Cangalli conglomerate and overlying terraces. Abandoned Pleistocene lake terraces south of La Paz in the Oruro area are another source of gold whose potential have not been realized. In both the Tipuani and Oruro areas, primitive hand methods are the principal means of production, with the exception of a single modern dredge. In spite of a long history of production, probably very little of the gold potential has been mined.

Jan 1, 1979

By Adolph V. Mitterer

International Minerals and Chemical Corporation operates one of six potash mines in the Carlsbad potash basin. More than 90 percent of America's potash is produced at Carlsbad and IMC accounts for about one-fifth of that amount, Since the Company began operations in 1941 it has mined nearly 50 million tons of ore. Of the two types of ore mined at Carlsbad the principal tonnage is sylvinite in which sylvite-potassium chloride-is the ore mineral. It is produced by IMC as well as by all other mines in the area, In addition to sylvinite IMC is the exclusive producer of langbeinite ore--potassium-magnesium sulfate. From its two ores, International produces a spectrum of 8 high-quality agricultural and industrial chemical products.

Jan 1, 1959

By Donald R. Lamont

The paper outlines the reasons for and research behind the recent decision to adopt oxygen decompression in the UK. Currently used measures of decompression illness are critically appraised. The paper describes the main precautions to be taken on site to manage the fire risk from the use of oxygen underground. A summary of the initial results from the use of oxygen decompression in the UK is presented.

Jan 1, 2003

Adsorption of acrylamide based homo and copolymers on hematite was investigated as a function of phe nature of the polymer charge and functionality of the polymer. Effect of addition of sodium dodecylsulfonate and dodecylamine hydrochloride was also studied and was determined to result in an increase or decrease in the amount of polymer adsorbed depending on, the charge characteristics of the surfactant and the polymer, pH of the suspension, concentration of the various species and the order in which these species were added to the system. The surfactant adsorption under given conditions on the other hand, was found not to be affected by the presence of the polymer molecules. The data is analyzed to elucidate the mechanism of adsorption of polyacrylanide type polymers on hematite both with and without the surfactant species king present in the system.

Jan 1, 1982

By S. Renslow, G. Wang, L. R. Moore, Y. Xiong, J. Gu

"Clays are known to contribute to a wide range of mineral processing challenges. These challenges can haunt a plant from the pit, through the beneficiation plant and even to the tailings pond and process water. Each step that the clay is present potentially experiences significant and costly impacts to the process efficiencies. The effect of clay minerals on the performance of phosphate flotation was investigated. The investigation led to an understanding of the movement of clay through the beneficiation plant, the impact on reagent usage, and the overall flotation performance. INTRODUCTION With the decline in mineral feed grades, mineral processing will continue to face challenges. One significant challenge would be obtaining high recoveries of industry specified quality mineral concentrates with lower quality raw minerals. Other challenges may be the handling of the excess tails and process water being produced to maintain a mill’s production volumes. For example, increased levels of clay have been, and will continue to be, a topic of concern for many mines. Some of these concerns include environmental regulations associated with water storage and discharge, as well as beneficiation. Gonglun Chen reported that clays produced in the phosphate industry are generally colloidal and fine (90% < 45 µm) (Chen, 2006). As such, these clays can take 20-30 years to settle, in the absence of polymeric assistance. The settling of these clays is essential as an accidental discharge can lead to substantial impacts to the wildlife and ecosystem. The Environmental Protection Agency (EPA) has referenced cases where the discharge of water can result in fines in the tens of millions of dollars, and at times causing the processing plants shut down, depending on the volume and quality of this discharged water (EPA, 1997). The turbidity discharge criteria will vary from state to state. Florida’s Department of Environmental Protection has listed a turbidity maximum of 29 NTUs, or 60 mg/L total suspended solids, above the natural background condition (Florida Department of Environmental Protection, 2016). A lot of the literature has been focused on the impact of high levels of clay (>10%) on mineral processing. Farrokhpay has reported the significant impact of clay minerals on froth stability in copper flotation (Farrokhpay, 2012). He reported that clays can form a hydrophobic slime coating on the surface of bubbles, which can yield an increase in froth stability. Clay concentrations as low as 5% can have significant impacts on the rheological properties or slurry viscosities. Increased slurry viscosities can lead to either elevated pumping/processing energies being required, decrease in flotation efficiencies due to a decrease in bubble mobility through the pulp, or decreased throughput to manage these viscosities (Tu, 2005; Farrokhpay, 2013; Burdukova, 2014)."

Jan 1, 2017

By J. Routh

Analysis of AI, As, Ba, Be, Ca, Cd, Co, Cu, Fe, K,. Mg, Mn, Mo, Na, Ni, Pb, Sb, Se, Sr, 11, V and Zn in various types of samples collected at Van Stone mine (a Pb-Zn deposit in Washington) and surrounding areas indicates that the concentrations of several elements in water, soil and sediment are higher than their background. values. Concentrations of metals in water decrease sharply downstream and are below the maximum contaminant levels specified for drinking water. Under present physico-chemical conditions, contamination of water is insignificant but the enrichment of heavy metals is found in soil and sediment.

Jan 1, 1994

By R. B. Massy-Greene

Project engineering and development is a process of optimisation of capital, operating and financial costs, and extraction rates in the light of current and forecast economic conditions for the sale of the product. The aim of the process is to maximize financial returns to the sponsors (project owners) within many often conflicting constraints. Thus, the sponsor&apos;s engineering and financial staff have a common goal, with performance measured in financial terms. Consequently, each group must be aware of, and responsive to, the constraints imposed upon the other. For financial staff, the increasing size and complexity, and escalating capital costs of new ventures have required them to seek finance in larger amounts, and by non-traditional methods. In addition, senior management are requiring indications of the availability of finance as a pre-requisite to a decision to commence project development activities.

Jan 1, 1982