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By Felicia F. Peng

Using a fuzzy logic controller, a signal applied on the processes may be generated through a linguistic protocol expressing an operator's intuitive control strategies. In this work, fuzzy logic controller and PID controller imposed upon the feedback liquid level control systems for a stirred tank are studied and compared. The construction factors including the shape of membership functions, number of fuzzy variables, number of inputs, number of rules, and different defuzzification methods are considered in design and formulating the fuzzy logic control strategies and algorithms. From the analysis of the strategies and control performances, an optimum controller may be generated by making use of the best combination of these fuzzy construction factors.

Jan 1, 1997

By G. A. Kordosky

The literature contains several references to the influence of copper solvent extraction reagents on crud formation, but, there is disagreement as to whether the reagent has an influence on crud generation. The results of three pilot plant campaigns, where crud generation was studied as a function of the copper solvent extraction reagent, are reported. These pilot plants were run at operating copper solvent extraction plants using the aqueous solutions being treated by the commercial copper solvent extraction plants. Two of the pilot plant studies showed that the copper solvent extraction reagent had a significant influence on the extent of crud formation while the other pilot plant study indicated the copper solvent extraction reagent had a lesser influence on crud generation.

Jan 1, 1996

By P. M. Brown

The Bureau of Mines, U. S. Department of the Interior, has developed a method of dewatering clay slurries based on flocculation by high-molecular-weight polymers and water removal from the formed flocs using a trommel or hydrosieve. The exchange ion on the clays affects their dewaterability. Metal ions in solution and on the exchange sites of smectite clays are known to act as Lewis acids. Recent work has determined that these ions can be titrated with high-molecular-weight polymers. The relative acidity of the exchange ion and the basicity of the polymer determined by the new method give insight into the dewatering mechanism.

Jan 1, 1988

By W. Todd

The Robbins Company has developed a boring machine, with a rubber packer serving as the gripper system, for blind boring of raises without using drill pipe. This machine is the BorPak and has many applications for use in the mining industry which will improve productivity. In addition to the cost savings, the boring method will lead to increased safety in constructing blind raises. The advantages of using the BorPak in a mining environment will be discussed together with possible applications.

Jan 1, 1994

By J. Driscoll

After 30 years of success, Newmont Gold Company has temporarily ceased production from the original Carlin Pit. In late 1993, the Carlin East Decline was driven and an extensive underground exploration program was started. Today, Newmont Gold produces refractory ore from the Carlin East underground at the rate of 700 t/d (770 stpd) for an annual production of over 100,000 ounces. Over 70 underground miners enjoy the estimated 6-year mine life at Carlin East. About 70% of the ore at Carlin East is mined by mechanized longhole stoping with delayed cemented backfill. The remaining ore is mined by underhand drift and cemented fill methods.

Jan 1, 1997

By R. S. Shoemaker

Expanded markets for copper in the past few years and a consequent search for new ore bodies have revitalized the widely known but seldom applied method of producing copper called heap leaching. This term should be differentiated from dump leaching in that the latter is applied to dumps of mixed oxide and sulfide ores (although either may predominate) that have been too low grade to beneficiate and have, therefore, been stripped off the higher grade underlying sulfide ores. Heap leaching is defined here as the process applied to oxide ores which have been mined solely for the purpose of leaching. In this case, all costs of mining the ore become a part (and a substantial one, as will be shown) of the cost of the copper produced, whereas in dump leaching the mining cost has already been accounted for as a stripping cost for the sulfide ore. Of course, with newly opened ore bodies, stripping costs may be divided through accounting procedures, between the copper produced by the mill and that obtained by leaching, but in general this type of operation must be economic on the basis of the sulfide ore alone. Heap leaching, as a beneficiation method, is unique in that it is the only process used for the recovery of a metal in which the time involved from mining the ore to metal production is measured in months instead of hours or at the most, days, Then too, after the ore body has been depleted and mining has ceased, metal production will continue for some substantial period of time. Heap leaching is also unique because unlike any other method of beneficiation, metal recovery cannot be accurately forecast ahead of time and recovery will never approach that of a conventionally milled sulfide ore or even that of a vat leached oxide ore. Counter-balancing this drawback, however, is the relatively low capital expenditure necessary to put a heap leaching operation into production and the consequence that smaller ore bodies which would not support the higher capital cost involved in a vat leaching plant can be made into producers. Stated more simply, in heap leaching the operator accepts low recovery in exchange for low capital costs and the break even point, that is, where the operator should go to vat leaching with its higher recovery and higher capital costs, is a matter of economics and also, to a great extent, a matter for the nature of the ore to decide. For instance, an ore that will vat leach in 7 to 10 days using 7 pounds of sulfuric acid per pound of copper produced might use double or triple that amount of acid during the months that are required for heap leaching.

Jan 1, 1968

By H. J. H. Pieterse

This paper highlights the mineralogy of the Barrick Goldstrike Mines Inc. area. The mine is located at the north end of the Tuscarora Spur and is part of the Bluestar/Goldstrike subdistrict of the Carlin Trend. The Betze, Post, and Meikle Mine are major deposits located in the area. The deportment of gold, its leachability, and various process options are also evaluated. Particular emphasis is given to the practical and economic considerations of ore control, and routing of ore to a process option.

Jan 1, 1993

By T. G. Hayes

Economic and environmental regulations in the coal industry have required companies to evaluate their current blasting method of loosening in-situ coal. This paper will review ripping vs. blasting thick in-situ coal seams, handling frozen active coal stockpiles and proper stockpile conditioning and reclaiming. How basic operating technique can improve job efficiency, productivity and cost per ton.

Jan 1, 1995

The CERAMEC pressure filter is used for the filtration of fine materials whose cake moisture cannot be achieved with vacuum. Development work has been carried out to achieve a well-controlled cake forming and cleaning of the filter media as well as an efficient solids discharge system. Operating costs are low due to low energy input and negligible consumption of pressurized air.

Jan 1, 1999

By G. R. Coonan

A number of famous studies have shown that house damage relates better to peak particle velocity than to acceleration or displacement. The relationship is true but doesn't go far enough. Why, for example, can construction shots go well above 1.0 or 2.0 inches per second without reportable damage? Recent studies have shown that vie must look at frequency and duration of an event in addition to amplitude. The complexity of measuring frequency, duration, and amplitude makes the average blaster in the field shudder. An even more excruciating problem is the need to obtain such data inside the building or residence in order to accurately predict the damage potential or human response to nearby blasting. The author reviews current research programs and suggests new areas of research necessary to help maintain a balance between complicated research requirements and simple field measurements.

Jan 1, 1980

By S. J. Jung

In recent years, the use of shotcrete, a practice familiar to the mining industry, has been on the increase. This research has come about because of the recognized need for a safe, easy way to line small diameter bored raises (less then 150cm). Up until now, an operator has gone down the raise and applied the concrete lining manually, using the shotcrete method of application. With an automated system, there would be no man positioned in the bore itself. All control functions could be commanded from a central location. Shotcreting in the confined space of a small diameter bored raise presents problems that can be overcome by the application of shotcrete using a remote system.

Jan 1, 1994

By R. R. Fernández

The Newmont roasting plant in Carlin, Nevada, commenced operating in December 1994. Over the years, refractory ores and pyrite concentrates from different gold deposits constituted the feed to the facilities. Historical plant performance indicated that the roasting temperature was the main variable affecting the structural characteristics of the calcine, which in turn affected the recovery of gold by cyanidation. Gold recovery as a function of roaster temperature has been closely monitored since October 2000. The original design temperature was 550° C. Lower roaster temperatures of around 500° C resulted in a gold recovery increase of more than six percent. This increase was directly related to an increase of the surface area of the calcine. The implementation of an ?intelligent? process control system helped significantly in achieving steady low roasting temperatures, thus obtaining high gold recoveries of 92 to 93 percent. Under these conditions, several roasting campaigns with high-arsenic-containing ores were conducted, which resulted in a significant decrease in gold recovery. The reduced gold recovery was caused by the loss of surface area (e.g., porosity) of the calcine as the arsenic content of the roaster feed increased.

Jan 1, 2010

By Randall E. Brown

Irrigation simulates a climate change so that crops can be grown that otherwise would not thrive. The abundant sunshine and warm weather of many arid regions induces a rate of growth in excess of that in cooler, moister regions. Hence, the arid part of eastern Washington, traversed by the Columbia River, is admirably suited to irrigation. The Pasco Basin lies in south-central Washington at the south end of the Columbia Basin Irrigation Project of the U.S. Bureau of Reclamation. The Basin, because it lies in the rain shadow of the Cascade Mountains, receives only 6 to 10 inches of precipitation a year with somewhat greater amounts, commonly as snow, on the higher hills. Recent extremes included 3 inches of precipitation from August 1967 to August 1968, and 12 inches in the succeeding "12 months. Most of the precipitation falls during winter. If it were to fall in summer or were evenly distributed throughout the year, evaporation rates probably would produce a true desert.

Jan 1, 1971

By K. N. Han, J. J. Kellar, Y. Guan

The adsorption of zinc species onto silica in ammoniacal solutions was studied. The adsorption isotherms indicated that the adsorption of zinc increased with increasing pH. The adsorption density increased as the zinc equilibrium concentration increased up to =3.5x10-4 M. Above this concentration, the adsorption density was independent of the equilibrium concentration, and a maxima adsorption density was reached. Temperature had no significant effect on the adsorption density.

Jan 1, 1995

By S. G. Tough, H. J. Hignett

The Transport and Road Research Laboratory is carrying out tunneling trials at Chinnor, Oxfordshire, with a 5-m-diam, full-face tunneling machine. The work, which is for research purposes only, involves driving the tunneling machine through chalk with most of the physical characteristics of the machine and its power consumption closely monitered. At the Conference a film was shown about this work, illustrating both the tunnel construction and the research program.

Jan 1, 1974

By Shawn Healey

The Mineral Hill Mine, owned and operated by TVX Gold Inc., is located in the Beartooth Mountains, 5 miles north of Gardiner Montana, U.S.A., which is the north entrance of Yellowstone National Park. Mining is carried out underground using ramp attack cut and fill as well as room and pillar mining. The mine currently employs approximately 145 people and is producing 550 tons per day at a grade of around .21 oz/ton.

Jan 1, 1996

By G. C. Anderson

The Cleveland Cliffs NOLA electronics and software upgrade is a Windows based system that simultaneously controls two Texas Nuclear NOLAs and associated sampling. It uses new spectrum analysis and algorithms to produce accurate, linear silica measurement with slurries that range from 5 through 50 percent solids. This linearity allows us to achieve a reproducible procedural calibration. The hardware consists of readily available shelf items, is extremely redundant and eliminates all NIM bus modules.

Jan 1, 2003

By T. Gollaher

The use of paste thickeners for mineral tailings has gained increasing acceptance by the mining industry throughout the world and in the U.S. during the last five years. Advantages of water recovery and environmental sustainability are the driving forces for paste as an alternative to conventional thickening and the slurry pond. This paper presents a summary of the differences between paste and conventional tailings thickeners, along with recent examples of full-scale paste thickener installations.

Jan 1, 2010

By G. France

The Blair Athol Coal Mine (BAC) is a large open cut operation in the Bowen Basin of Queensland, Australia. Current mine capacity is about 11 million tonnes per annum (Mtpa) of export coal. On-line analysis at BAC consists of two Coalscan 9500s installed directly on the output of the crusher plant and immediately before the product stockpiles, while a third Coalscan 9500 is installed on the transfer conveyor feeding the train loading bin. The two product Coals cans have a dual purpose. The first is to provide real time coal quality data directly back to the mining operations. The second is that of modeling the product stockpile with accurate on-line information. This modeling enables both production and coal quality personnel to accurately examine the coal quality of each stockpile with a degree of resolution which previously had never been achieved.

Jan 1, 1999

By L. Yan, C. Zhou, M. Reyes

"The MINER Act requires the installation of post-accident, two-way communications and electronic tracking systems for all coal mines. One communication system which can satisfy this requirement is an electrode-based, through-the-earth (TTE) communication system, which sends signal directly through the overburden of a mine. The performance of these types of systems relies on several controlling factors such as earth conductivity, overburden depth, operating frequency, TX/RX antenna length, TX/RX offset, TX/RX orientation angle and TX current. In an effort to estimate attenuation through the earth, NIOSH researchers developed an analytic solution for the electrical field distribution of an electrode-based TTE communication system for the extremely low-frequency (ELF) range (< 30 Hz) or DC excitation source. The analytic model was then validated using test data measured at an operating coal mine. The validated model can be used to optimize the operating frequency, estimate the required transmitting current, choose appropriate TX/RX orientation, and predict the performance of an electrode-based TTE system at a coal mine. INTRODUCTION One of the requirements of the Mine Improvement and New Emergency Response Act (MINER Act) of 2006 is the installation of post-accident, two-way communications and electronic tracking systems for all underground coal mines. As one of the through-the-earth (TTE) wireless communication methods available for the mining industry, the electrode-based, or linear, TTE systems establish communication by inducing a current within the earth medium by use of a pair of current probes. The resultant current is detected as a voltage by a similar set of distant probes. These probes could be an insulated piece of wire tied to two electrodes grounded at distant ends, or the grounded ends could be rails, roof bolts, or grounded electric rods. The analytical solution developed in a homogenous half-space, for this form for various transmitter/receiver (TX/RX) configurations, will be presented in this paper. The communication signals can be sent either from underground to surface (uplink) or from surface to underground (downlink). In order to achieve a successful communication link, it is necessary to understand the electric fields within the earth so that the appropriate size of transmitting antenna, TX/RX relative orientation, and operating frequency can be chosen. Hill and Wait gave the explicit forms of partial magnetic fields and partial electric fields of electrode-based TTE downlink communication with finite cable length [1]. In prior research, the E-fields of electric line transmitter were obtained for a static TX current [2] [3]. In this paper, the general and explicit forms for electrode-based TTE electric fields are developed and presented. The solutions for the extremely low-frequency (ELF) range (< 30 Hz) or DC excitation source obtained from these forms are presented. Also, factors that affect the E-field strength at RX are discussed."

Jan 1, 2017