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By Wolfgang Baum

This paper discusses the use of mineralogical work during the develop ment and operation of gold heap leaching projects. It focuses on the early assessment and prediction of metallurgical performance, the identi fication of gold recovery problems and the application of mineralogy in process optimization. The results of extensive operations support work emphasize the benefits of routine plant mineralogy. Mineralogical characteristics are amongst the most important factors determining leach- ability, leach time, reagent consumption, insoluble losses, scale forma tion and equipment performance.

Jan 1, 1990

By Daniel Hodouin, Claude Bazin, Sami Makni

Computer systems, installed in mineral processing, are designed to accumulate massive amounts of real-time data. Frequently these data are only partially processed because of the lack of adequate methods and the limited accuracy of mineral processing sensors. Methods are proposed to estimate missing data and reconciliate sensor data on a real-time basis. They are based on dynamic extension of steady-state techniques such as the node imbalance minimization or the least-squares mass balance adjustment techniques. The methods are illustrated for simulated and actual flotation data. Their data upgrading ability could be used to improve process monitoring, control and optimization.

Jan 1, 1993

By K. N. Han

A kinetic model for the batch leaching of various metals using different lixiviants was developed. The overall material balances for the reactants and products at the solid/ liquid interface were formulated for various types of heterogeneous reactions at the interface. The solutions to these mass balances are identified analytically, as well as numerically. Applications of these numerical solutions to various leaching systems using rotating discs or powders are discussed. The metal-dissolution systems addressed include cobalt, nickel and copper in acid, cyanide and ammoniacal solutions.

Jan 1, 1996

By M. Manrique, E. E. Vidal, I. Accorsi, P. R. Taylor

Various pyrometallurgical methods for treating ilmenite and zircon concentrates are reviewed. Laboratory experiments using a thermal plasma reactor were performed to evaluate the conversions of ilmenite to TiC or TiC-Fe and zircon to ZrC or ZrC-SiC. Results are examined and possible processing routes are identified.

Jan 1, 1999

By Peter J. Szabo

The mining executive works in a cyclical industry. His employment is subject to the vagaries of the marketplace. Boom and bust has always been the industry's story. "Big oil" failed in its mining effort. This left emotional and financial scars on many mining families. One must remember that mining executives always play a high-stakes game. Given the cyclical nature of the mining industry, mining executives need to take care of their own financial security. The mining executive that does not plan for his financial security in this cyclical business is playing Russian Roulette with his future. Take a look at those people who have reached their later years with the mining industry. One usually finds three categories of people. Those few in the first group have been fortunate enough to have worked for one company. They have survived the winnowing process of cyclicality, political problems, and takeovers. They have reached normal retirement age. For them, the retirement years are usually comfortable. People in the second group have worked for those same mining companies. But these people have been forced out by early retirement. Or they have been laid off for cyclical, takeover, or political reasons. The third group includes those who have held many positions in the mining industry. Probably not until their later years are they fully vested, if at all, in a pension program. The first small group, then, is the exception. The others, unless they have taken care of their financial security, are doomed to later years of financial problems, stress, and unhappiness. Too late in life, many realize the harsh realities of failure to plan and implement a personal financial program. Mining executives go to some of the world's leading mining schools, to learn how to make money. The curriculum is technically strong. Most mining graduates are familiar with the intricacies of discounted cash flow, present value, and the Hoskold formula. But few of these same mining schools require courses on personal financial planning. Such courses could give mining students a realistic foundation and the mechanisms with which to cope with their cyclical profession. An executive has only three sources of money. He can make money at work. He can put his money to work. Or he can get money from charities, such as government programs. Of these three sources of money, money at work has the best chance of providing financial security in later years. The mining executive must think of the day when he will be too old to work and contribute to the market place. At this point, the quantity and quality of his investments will determine whether his later years will be secure. Along with the Mining Engineering Handbook, two key books should be included in the mining executive's library. These are Venita Van Caspel's The Power of Money Dynamics and Benjamin J. Stein's Financial Passages. These books contain the basic concepts of personal financial planning so critical to an individual's financial survival. Venita points out the simple formula that is the key to financial independence: Time + Money + American Free Enterprise (Rate of Return) = Opportunity to Become Financially Independent Chart 1 shows that this is not a trite formula. The chart shows the dramatic effects of compounding over time. The chart also shows at various yields what a $2000 a year Individual Retirement Account (IRA) contribution will accumulate. Chart 1 (from Money magazine) is based on the future value of an ordinary annuity. It shows that the key to amassing a small fortune by the time a person reaches his 50s is starting to save methodically in his 20s. This, coupled with the highest yields consistent with safety of principal will ensure financial security. There are significant effects from compounding money over time. Every year the decision is put off to save for later years will cost a person dearly by the time he reaches his 50s. For example, consider the decision to put off for one year a $2000 IRA investment at a 12% return. Starting it at age 31 instead of 30 will cost the executive almost $100,000 by age 65. What if the executive waits until age 35 to get started with his $2000 a year investment? He will then lose nearly $400,000 by age 65. Stated another way, the executive costs himself this $400,000 simply because he did not invest $167 a month for five years. $167 a month - that's less than an inexpensive second car payment. This $400,000 pool of money could provide the executive a $40,000 a year income at age 65, assuming a 10% return on invest-

Jan 11, 1985

The classical slope analysis and a statistical technique were used in order to determine the iron complexes formed in the organic phase during the extraction of Fe(III) from Fe-Ni-Co sulfate solutions with Di-(2-ethylhexyl) phosphoric acid (D2EHPA) in kerosene. Equilibrium constants for the extraction based on these complexes were also calculated. The complexes determined were of the general form (Fe(OH)3-nRn?sHR)x' where n varied between 1 and 2.5 and s between 0 and 3, and both were found to be decreasing as the iron loading in the organic phase increased. Values of 1,2 and 3 were generally found for x, indicating that the complexes were monomers, dimers and trimers.

Jan 1, 1988

By Ryan Lemmon

Belt turnovers are commonly used in conveyors to rotate the belt so that the clean side of the belt contacts the return idlers. The belt turnover length has traditionally been sized on only the twisting stresses. However, belt turnovers are also subjected to bending stresses due to the weight of the belt. Although bending stresses have in the past been ignored, these stresses are significant and should not be neglected. This paper quantifies and presents a method for calculated twisting and bending stresses and also the belt sag.

Jan 1, 2002

By Raymond E. Riethmann

El clasificador de espiral fue diseñado originalmente para circuitos cerrados de molienda. Desde entonces se ha aplicado con éxito a otros trabajos de clasificaci6n donde se necesita realizar un corte de dos productos. Inherentemente a las cualidades especiales de este cla- sificador está especialmente preparado para: clasificar, lavar, o agotar materiales tales como minerales, roca fosfática, arenas, carbbn, conchas de ostra y sales fosfáticas. Presentamos ahora las características de operation, flexibilidad de diseiio y líneas maestras para una apropiada aplicación.

Jan 1, 1982

By C. M. Rastle

Resource Technology Associates (RTA) has developed a flocculation-flotation process that increases phosphate recoveries from current operating plants. A major advantage of the process is the ability to float the phosphate from the matrix without a preliminary separation to remove the slimes. A majority of the material that is now discarded in the slime fraction will be recovered in the new process. The process can also be used to recover phosphate material from current slime ponds either as a separate feed or mixed with matrix material. Flotation tails from the process demonstrate improved dewatering characteristics then those seen from conventional float tails.

Jan 1, 1988

By S. Makni, C. Bazin, D. Hodouin

This paper reviews approaches for the real-time estimation of mass flow rates and assays using data from on-stream analyzers and flowmeters in a flotation circuit. Results obtained using one algorithm operating on-line with an industrial flotation circuit are presented.

Jan 1, 1998

By Vanessa M. Torres, Lafayette C. L. Freitas, Evandeo C. Silva

This paper shows two applications of artificial intelligence models in process development. In the first application, a heuristic fuzzy correlation can predict flotation behavior in bench scale based on feed characteristics for a high variability copper ore, as well as to predict plant performance for a feasibility project evaluation, minimizing its risk. The second case study shows the use of neural networks to model the iron ore sintering, correlating ore characteristics and operational parameters with sinter properties. With this application, CVRD aims to establish a new step on iron ore product evaluation and customer support.

Jan 1, 1998

By J. F. T. Agapito

Energy West Mining operates the Deer Creek and Cottonwood/Trail Mountain coal mines in the Wasatch Plateau about 40 km (25 miles) southwest of Price, UT. The Deer Creek Mine extracts the Upper Blind Canyon seam and the Cottonwood/Trail Mountain Mine extracts the Hiawatha seam 12 to 36 m (40 to 120 ft) below. Both seams average about 2.8 m (9 ft) in thickness. Cover depths exceed 550 m (1,800 ft) in a large portion of the unmined reserve. Stability problems at Deer Creek are mostly due to coal bursts caused by high stresses associated with deep cover and sandstone channels. Most of the bursts have occurred in gate pillars and, to a lesser extent, at the longwall face and during development. The introduction of a two-entry gateroad system with 9-m- (30-ft-) wide yield pillars has been a major factor in controlling and minimizing gate pillar [ ] bursts (Agapito et al., 1988). However, some bursting began to occur in the 9-m- (30-ft-) wide pillars as cover depths reached 550 to 610 m (1,800 to 2,000 ft). This was due to more rapid and higher abutment loading in areas with very strong roof and stiff floor.

Jan 1, 1997

By Y. Q. Zhang, Y. Luo, S. S. Peng

Burrier pillars in underground coal mines could eventually be subjected to a water head due to the build-up of mine water in the old workings. The water head could not only act ns a force to destabilize the pillar, but it could also cause seepage flow through the pillar and its surrounding strata. Excessive seepage flow could induce piping failure that, ill turn, could accelerate the mechanical failure process of the barrier pillars. In this paper, a finite element simulation approach was employed in the evaluation of the barrier pillars. Both the stress distribution and the seepage flow pattern in and around a barrier pillar have been simulated numerically. The effects of ground stress on rock permeability to water seepage has been taken into consideration in these simulations,

Jan 1, 2002

By L. Hales

Process control systems have evolved from single loop control to distributed control with computer based expert control strategies. The next step is to add adaptive control to the expert control strategies. An object-oriented adaptive optimization approach is defined and simulated results are presented for a plant.

Jan 1, 1996

By J. B. Zachwieja

Cationic reagents have been utilized in mineral processing since the mid 1930's and are based upon fatty nitrogen derivatives. The initial commercial development was centered around a flotation collector capable of separating potassium chloride from sodium chloride - potash flotation. The first commercial sale for Akzo, known then as Amour and Company, was realized in the summer of 1940 to a potash producer in Carlsbad, New Mexico for the flotation of potash. The success of the potash flotation collector led to the development of other cationic mineral processing reagents. Flotation collectors for iron ore, phosphate, calcium carbonate, silica sand, feldspar, and other silicates materialized into a large commercial business. Another area that realized commercial success was the development and use of anticaking/antidusting reagents for hygroscopic salts, fertilizer mixes, and granular fertilizers. A more recent development has found use in the trona industry as a defoamer and crystal growth modifier during the crystallization of sodium carbonate liquors. A review of cationic reagent chemistry and applications will be given and the potential for new application areas will be explored.

Jan 1, 1994

By Gilles A. Tremblay

Acidic drainage has been long recognized to be the largest environmental liability facing the Canadian mining industry and to a lesser extent the public through abandoned mines. The Mine Environment Neutral Drainage (MEND) Program was the first initiative formed in 1989 to develop scientifically-based technologies to combat acidic drainage. This 9-year volunteer program reduced the liability by several hundreds of million dollars and established Canada as the recognized leader in research and development on acidic drainage for metal mines. MEND 2000 is a three-year program that started in 1998. The key to MEND 2000 is technology transfer- providing state-of-the-art information and technology developments to users. MEND-developed technologies are being verified by long-term monitoring of large-scale field tests. Maintaining linkages with a number of foreign government and industry-driven programs is also important to the successful completion of the program. Through these efforts a further reduction of the environmental liability associated with acidic drainage will be realized.

Jan 1, 2000

By Steve Garcia

GEORGE WEINMAN: Our next speaker is Steve Garcia, operations vice president and general manager of mining at IMC-Agrico, Florida. Steve was born in Lakeland, Florida, to an IMC mining family. He has 17 years with IMC-Agrico and Freeport companies, including assignments in North Carolina, Nevada, Arkansas, and Indonesia. His work within the industry includes technical and operating positions including chief metallurgist, drying superintendent, and mines operations manager at Pane Creek. Other experiences include design of a grassroots phosphate facility in North Carolina; construction and start-up of a gold facility near Elko, Nevada; work in the Blytheville, Arkansas, ammonia urea facility; and three years managing engineering, construction, and support services in Irian Jaya, Indonesia. Steve's presentation is "Evaluation and Standardization of Multiple Slurry Pumping Systems."

Jan 1, 1998

By W. Swisterski, G. Romaniszyn, S. A. Lukasiewicz

The present paper analyzes the motion of a particle of material in a horizontaly rotating tumbling mill. The sliding of the particle under action of dynamic and friction forces and its free flight fall are analyzed. It was found that mechanism of free-fall occurs at supercritical rotations of the mill.

Jan 1, 1991

By John D. Kalasky

Island Creek Coal Company has had, for many years as a primary concern, the activity of handling large quantities of methane in the ventilation of its deep mines of southwest Virginia. Since the development of the Beatrice operation in the mid 19601s, the concern has been well founded, and through the years progress has been made in this most important facet of the extraction of the coal reserves to insure the safety of the employees engaged in the mining opera- t ions.

Jan 1, 1980

By R. Y. Wan

Newmont Gold has advantageously used the capabilities of mineral oxidizing bacteria to develop a process for the pretreatment of low-grade sulfidic and carbonaceous-sulfidic refractory gold ores. The biooxidation process results in the oxidation of the sulfidic minerals with increased exposure of gold for subsequent gold recovery. The biooxidized carbonaceous-sulfidic ores cannot be heap leached with cyanide because of the preg-robbing characteristics of the carbonaceous matter in the ores. Therefore, an alternative heapleach process using ammonium thiosulfate was developed to extract gold from these preg-robbing bioaxidized ores. The ammonium thiosulfate leach process was successfully applied in both laboratory and pilot plant tests. Satisfactory test results were achieved, encouraging the continuation of process development.

Jan 1, 1997