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By B. E. Davis

A fundamental study of the mechanisms involved in the conditioning of coarse Florida phosphate has led to some interesting discoveries. Studies by the Bureau of Mines have shown that conditioning time and mixing intensity greatly affect the grades and recoveries of the phosphate minerals and quartz in the rougher concentrate. In particular, as the conditioning time or mixing intensity increased, the phosphate recovery remained constant while the amount of quartz floated decreased. This phenomenon is contrary to conventional wisdom and could lead to a more efficient coarse flotation circuit.

Jan 1, 1993

By Omar A. Muhtadi, David A. Milligan

7.1 INTRODUCTION The circulating fluid (generally an aqueous cyanide solution) is the major active component of heap leaching. This solution extracts precious metal from the heap and is then processed to recover the precious metal. The solution continuously recycles through the heap to recover more precious metal. With each cycle through the heap, water and chemicals are lost. Make-up water and chemicals must be added to balance losses from evaporation, seepage, entrainment, and chemical reaction in the heap, as well as any other processing losses. Adding more water than needed can result in a build-up of water as inventory in the various ponds and can eventually require that water be discharged from the operation. This is an extremely undesirable condition, and can often be very expensive in both investment in water treating facilities and operating costs. Most heap leach facilities operate under a zero discharge permit; thus, a situation requiring water discharge can result in permit violation. Chemical solution control must be managed to maintain the optimum pH, dissolved oxygen content, and cyanide content, while preventing "scaling". Calcium-based precipitation is a common scaling problem in mill reclaim waters. A buildup of these deposits can result in severe reduction of water flow, loss of pump efficiency and eventual interruption in metal production. In addition, problems of plugged sprinkler heads, blinded leach pads and fouled carbon (in carbon recovery systems) can be and often are experienced when scale control is not maintained. The remainder of this chapter discusses chemical solution control and scaling prediction/prevention in the context of a "closed" system. Sizing of ponds to accommodate precipitation and runoff, collection systems, and other similar design considerations are not discussed here. These topics are deferred to later chapters, e.g. Chapter 10 considers design of collection systems while Chapter 12 discusses pond sizing. 7.2 CHEMICAL CONTROL Chemical composition of the circulating solution must be controlled by the operator if the heap leaching process is to be successful. The primary or essential chemical control parameters in any heap leaching operation are:

Jan 1, 1988

By K. C. Shaver

The Sloan Ranch kimberlite complex is located approximately 130 km north-northwest of Denver in the Precambrian core of the northern Colorado Front Range (Figure 1). A Devonian age for the complex is suggested by the fossil assemblages in limestone xenoliths (Chronic and others, 1969), and by paleomagnetism of the kimberlite (E. E. Larson, personal communication, 1986). The presence of diamond was first reported in rocks from the Sloan diatreme by McCallum and Mabarak (1976). Prior to this time, the distinctive- appearing host rock of the Sloan diamonds had been quarried for use as terrazzo stone; examples may be seen in the floors of the airports in Cheyenne and Laramie, Wyoming. The Minerals Division of The Superior Oil Company obtained a lease on the Sloan property in 1980. During the next four years Superior built and fine-tuned a highly efficient diamond recovery facility, explored and tested the Sloan deposit, and used Sloan as a site for testing numerous exploration techniques for future use in a continuing exploration program in the Colorado-Wyoming kimberlite province. The Sloan property was ultimately determined to be sub- economic, but the lessons learned there have been very helpful in subsequent exploration efforts.

Jan 1, 1987

By C. A. Rowland

Comminution efficiency can be expressed in three different ways. Theoretical Efficiency: actual energy consumed, in a comminution machine compared to the theoretical energy required to make the size reduction. Operating Efficiency: compares the operating work index, calculated from production comminution machinery operating data, to the Bond Work Index from bench scale comminution tests or calculated from pilot plant operating data. Economic Efficiency: income compared to planned income. Using the Bond Work Index and operating work index, this paper explains how to determine operating efficiency.

Jan 1, 1998

My "outside exploration" began in November 1908, only 16 months after I had come to Bisbee as a raw engineer. The well publicized reputations of eminent engineers up to that time, including John Hayes Hammond, Herbert Hoover, James Douglas, D.C. Jack- ling, J. Park Channing, and a few others had been due to new mines they had found or brought to successful operation. And here was I, a mere youngster, given a chance to join the group. I knew there would be disappointments but I had no idea how many of them. In spite of the many prospects that turned out to be worthless I never looked at a new one without the feeling that this one might turn out to be the big success. This confidence, blind as it was, gave every arduous examination a zest and it made me climb every mountain on which the owner said there was something worth seeing, or on which T could see a distant staining that might mean ore. If I looked at every showing the owner suggested he at least would think I was honest and would bring other properties to our attention. This reputation of never refusing to go to see an outcrop, no matter how hot the desert sun or how rough the terrain, was probably one of my best assets. High as my hopes were at the start, they proved not to be exaggerated and if I were given a chance to do it again I would not hesitate, in spite of the jaundice, rheumatic fever, and other maladies that beset some of the expeditions. On the whole the results have equaled all my hopes. Toward the end of my years of active exploration I totaled up the score. Out of the prospects submitted to us about two out of three were eliminated after questioning the owner or prospector, without an examination. This left about a 1000 mines or prospects that seemed worth at least a preliminary look. One out of seven of these was worth a little development and a seventh of this seventh turned out to be a modest success or better. And nine or ten in all, or one out of 1000

Jan 1, 1976

By D. G. Ball

Other than being used to convey fill material for the gob stowage or building of ribside packs on advancing longwell faces, pneumatic conveying has not been used for the transport of materials on a large scale in mining operations. The technique is extensively used in the wood products industry for conveying wood chips, limestone and other ingredients for the manufacture of paper, for the transfer from railcars, barges or ships to silos or stockpiles and further transfer into the pulp mills. This method of material transfer has the distinct advantage of transporting suitable material over horizontal and vertical distances within the same system. In considering material associated with mining, this includes, ore, coal and rock up to 4 inch cubed size, throughputs of 200 tons per hour over horizontal distances of 3000 feet or vertical lifts of 2000 feet. In recent years tests have been carried out to determine the physical and economic limitations of pneumatic hoisting, the results of which have led to the installation of two fully productive coal hoisting systems at mines of the National Coal Board in Great Britain. The equipment used for the pneumatic hoisting of coal or waste rock is described in this paper, together with a brief history of the tests which led up to the installation of the two hoisting systems in Great Britain.

Jan 1, 1977

Integrated mining information and process control systems can reduce information delays, enhance decision making and improve the responsiveness of mining operations to, for example, variations in market conditions, mineral grades and ground conditions. This paper examines developments in the areas of: monitoring, data analysis and diagnosis,' communications systems; integrated mining support system;, and process and machine control. It concludes that the development of a comprehensive information technology plan is fundamental to the phased implementation of these technologies. In addition, hardware and software standards and concurrent digital design and simulation practices in selected manufacturing industries are examined and concluded to have relevance to the mining industry. Integrated information and process control systems will lead to emergence of the "digital mine". Such advances in mining information infrastructure as well as mining equipment will enable mining operations to shift from mass production methods to leaner production techniques. "Lean mining" aims to enhance and accelerate cash flow over the life of a mine by focusing on reduction of' throughput times; stockpiles for volume and quality control; and wastage and rework.

Jan 1, 1995

By J de Cuyper, G. Rinelli, A. M. Marabini, V. Alesse, W. Freyberger

Salicylaldehyde, a chelating agent for tin, has been found to function as a collector for the flotation of cassiterite. Infrared and nuclear magnetic resonance studies clearly show that salicylaldehyde can form a chelate compound in bulk and at the surface. Results are also given for the flotation of a tin ore with this reagent.

Jan 1, 1976

By Y. S. Roditis

A new method for interpolating a block model is proposed, where both the diamond drill holes (DHs) and blast holes (BHs) data are used. Combining these data types poses a geostatistical "class size" problem due to the different statistical properties of the densely populated BHs and the sparsely populated DH data. This paper discusses how linear regression was used to adjust the DH values prior to the interpolation to account for the "class size" problem which is inherent to the procedure. The correlation between the BHs and the DHs is found. The DHs are then corrected based on the regression line. Each block that falls within a certain range of influence of a blast hole is assigned a different code and is interpolated with the combined BH and regressed DH data set. Blocks that fall outside the range of blast hole influence are interpolated using the original DH data set. A comparison against other methods, indicate a 12% improvement over using DHs only and a 2% improvement over using BHs only.

Jan 1, 1992

By Ruston A. Ford

This paper reviews the development of the David Bell Mine, from early exploration, through discovery, construction, start-up, underground development, and production. Details are provided regarding the mine development, the mechanized cut and fill stope production, the proposed long-hole stoping with delayed backfilling mining method for the lower levels and the cyanide leach carbon-in- pulp concentrating process. The mine development remains on schedule and under budget with results very much as predicted in the feasibility study.

Jan 1, 1987

By Scott G. Britton

In the real world of coal mining, the bottom line for almost every support project decision is economic (i.e., what is it going to cost?). Up to this point, I have discussed the methods to improve the performance of typical support projects by better installation, materials, and techniques, thus lowering the impact of the bottom line cost. In this chapter, 1 shall explore what costs are relevant in mining construction, and how these costs are developed. The chapter centers around two major discussions: (I) developing cost accounting techniques, and (2) cost-estimating procedures for support construction. Each focuses on the fundamentals of practical cost considerations necessary for decisions on construction projects underground. Since cost accounting, economics, and investment planning are all subjects which warrant complete discussions on their own, this chapter will focus on distilling the important concepts required by a planning engineer into an easily understandable presentation.

Jan 1, 1983

By K. S. Eric Forssberg, T. V. Subrahmanyam

The present paper deals with the important technological developments in gold processing and where possible, the data is presented in the form of tables. Gold processing methods have evolved to such an extent that low grade and complex ores once considered uneconomic are now becoming viable. Constant efforts are underway to innovate technologies in order to improve the efficiencies and cut down the capital and operating costs. The methods are discussed.

Jan 1, 1988

By Malcolm Scoble, Sean Dessureault, Scott Dunbar

Budgets are key financial and behavior drivers for most businesses, including mining. Budgets are used to link strategic objectives to tactical decisions, to measure performance, and to provide basic financial planning. More accurate and pertinent budgets should result in improved strategic decision making and performance measures. This paper discusses how a process based production and cost database, based on activity based costing models and the one year production plan, can be used to create the annual budget for an operating mine as an Activity Based Budget (ABB). A case study is used to compare budgets derived from traditional methods and an ABB approach. It is evident that the ABB method is more accurate.

Jan 1, 2002

By Franklin H. Sharp, R. Woods

The operation of the Magmont Concentrator located on the New Lead Belt of Southeast Missouri is described. Ore characteristics affecting lead-copper-zinc separation are enumerated, and the cur- rent methods of separation are detailed.

Jan 1, 1976

By Guido Venturini, Giorgio Martinotti, Luca Delle Piane, Paolo Perello

This paper presents a critical review of geo-structural mapping methodologies applied to deep tunneling projects in complex mountain chains such as the Alps. Geological forecastings are often a crucial part of tunneling projects, which should allow contractees or contractors to assume their own risks. Despite this, often adequate methodological criteria are not applied in the realization of these studies, with consequent increase of costs and delays. A discussion should hopefully start in the world of tunneling in order to define a correct approach.

Jan 1, 2003

By T. L. Conley, J. J. Rozek

The $2 billion (A$) Melbourne City Link Project is one of the largest and most important metropolitan road developments ever undertaken in Australia. The project involves two three-lane vehicular tunnels totaling 5 km, constructed as deep as 65 m underground. The 3.4 km Burnley tunnel is one of the world's longest three-lane tunnels. The project is being delivered under a DBOOT [design-build-own-operate-transfer] process and all design and construction is performed to ISO 9000 standards. Tunnel excavation began in May 1996, and the tunnel will open to traffic in 1999. This paper focuses on the range of construction techniques utilized during construction.

Jan 1, 1999

By T. Hall, R. Ferris

Waterjets and diamond wire saws have raised the productivity and lowered the cost in dimensional granite quarries. While the cost of diamond wire sawing is substantially lower than waterjet, the judicial use of the waterjet can simplify and improve the overall operating efficiency and predictability. Granite is the hardest commercial stone and only the gem-stones garnet and diamonds are harder. The introduction of industrial diamonds has made it possible to quarry and process granite at costs equal to or less than other natural stones – making granite, with its superior properties, the best value available.

Jan 1, 2004

By M. Leduc, M. Backens, M. E. Smith

An emerging technology for sustainable development in mineral development, tailings co-disposal™ is a means to dispose of conventional mill tailings within the void space of a waste rock dump. This method, while not applicable to all tailings systems, can offer a significant reduction in short-term and long-term environmental liability, land disturbance, closure costs, and negative public image. The concept is to dispose of the tailings simultaneously with the waste rock or leach ore, controlling the ratio of tailings to coarse material such that the resulting dump is stable both physically and chemically. The resulting co-disposal dump can be as safe as a conventional waste dump. In the case of alkaline tailings in a potentially acidic waste dump, the acid production can be buffered or slowed.

Jan 1, 2004

By Jack O?Hearn

A liquid and solid waste management plan for an operating uranium ore processing mill was developed to efficiently and effectively dispose of existing solid wastes and related, affected surface and ground water resources. The goal of this management plan was to achieve satisfactory clean up of these existing wastes ad their by-products as well as to prevent similar situations from occurring in the future. An existing, modern system of synthetically lined tailings ponds, constructed after many years of mill operations, now provides an approved site for the disposal and containment of waste streams currently generated by the mill. This system was thought to be readily adaptable to serve as a key element of the waste management plan. The potential presence of extra capacity in these ponds could eliminate or reduce expenditures for new facilities required solely for proper management of liquid and solid wastes generated by operations prior to construction of the modern tailings ponds as well as for a range of anticipated future operations.

Jan 1, 1984

Selective Flocculation process development generally involves single mineral flocculation tests to identify the appropriate polymer and experimental conditions for achieving the desired selectivity. Invariably the selectivity predicted on the basis of such tests is not realized when mixed mineral tests are conducted. A systematic experimental investigation revealed that adsorption of the polymer on various substrates is critical to selecting the suitable flocculent. Simultaneously, a mathematical model was developed to predict the overall process efficiency with a given polymer. In this paper, results of these efforts to scientifically design a suitable selective flocculation process are presented.

Jan 1, 1991