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By H. N. McLeod, M. J. Thom

The use of cyanide in gold mining requires the careful handling and storage of cyanide rich tailings. Cyanide in groundwater can frequently be both persistent and mobile, so that tailings basins need to be designed to limit and collect seepage. Assessment of the potential environmental impact requires an understanding of the hydrogeologic regime, both before, during and after mining. Groundwater monitoring wells provide a basis for monitoring tailings pond behaviour and for assessing the impact of mitigative measures to reduce or control seepage. A case example of Cheni Gold Mines Lawyers Project in Canada is presented to illustrate the use of groundwater monitoring to determine the amount of cyanide degradation and attenuation between the tailings pond and the receiving environment.

Jan 1, 1991

By G. Olson, T. Mudder, T. Clark

An evaluation was made of an innovative chemical approach for controlling the biotic portion of sulfide oxidation of tailing and waste rock using thiocyanate. This lipophilic anion is selectively toxic toward acidophilic bacteria, including those that oxidize metal sulfides. Sulfidic materials from precious metal and base metal mining operations were treated with thiocyanate solutions and subjected to accelerated laboratory weathering at 1 to 50 kg scale in humidity cells, trays, and columns. Initial field trials were conducted at 13.6 t and 100 t scale. Thiocyanate at relatively low concentrations reduced ARD from 50% to over 99%, depending on the sample and specific ARD parameter measured. Test work also was done with phosphate as an agent to coat reactive sulfides, further reducing their oxidation by biological and chemical reactions. The combination of phosphate and thiocyanate treatment is the basis for a potentially comprehensive approach to ARD prevention and control. Additional research and pilot testing are underway.

Jan 1, 2004

By Patrick Sullivan

Over the past few years, successful operations for processing phosphates employing the Grate-Kiln System have been achieved. Control and instrumentation philosophy followed in these installations are described and analyzed. Concepts utilizing digital techniques and computer systems appropriate for similar installations are also discussed.

Jan 1, 1967

By Jacques LeBel

After a brief definition of asbestos and a review of regulations, the elements of asbestos dust control are outlined for various asbestos manufacturing industries. To prevent the asbestos dust to become airborne, the general procedure is to control the dust at the source by enclosure and exhaustion. The asbestos dust is collected and removed from the air with bag filter collectors of high efficiency (better than 99%) to ensure that the air emitted to the general environment or returned to the workplace are below the existing asbestos emissions regulations. Dust control systems should be regularly inspected and serviced to maintain at all times the efficiency and reliability of the equipment. Other effective procedures for asbestos dust control are also considered.

Jan 1, 1984

By Weijian Yu, Genshui Wu, Jian Zhang, Yong Ning

Aiming at characteristics of the soft coal roadway engineering geology and deformation, the exposure research of the soft coal seam, theoretical analysis, numerical calculation and program design were carried out. First of all, according to the disclosure, soft coal seam engineering characteristics and geological conditions in Xinxing coal mine were expounded. Meanwhile, the soft coal roadway bolt supporting axial effect, the bolt supporting transverse effect, the anchorage body mechanics strengthening mechanism and problems such as supporting strength have been analyzed. The paper pointed out that the soft coal with very small cohesive force can form a composite anchorage body under the combined action of the anchor cable group, the W-type steel band and the metal net. The soft coal body in the plastic damage area formed anchorage balance arch with a certain bearing capacity and adapted to the rock deformation, and which played an effective support role in the roof outside the balance arch of the roadway. Therefore, the full-cable support technology was proposed. And then, numerical calculation and comparative analysis were conducted on three schemes of the roadway with non-support, with combined support of “anchor bolt and cable” and the full-cable support. The results show that when the roof is supported by anchor cable, it not only controls the continued increase of the subsidence value of the roof, but also effectively suppresses the convergence amount of the floor heave value and the amount on the sidewalls of the roadway. Whether it is from the stress distribution situation, or the viewpoint of plastic zone scope, the combined support of full-cable is more reasonable than that with non-support and that with the combined support of “anchor bolt and cable”. Finally, based on the features of soft coal seam in No.2265 work face of Xinxing coal mine, the relevant support schemes were put forward, and its specific support parameters and cross-section designs were drawn as well.

Jan 1, 2017

By E. Jannoulakis

This paper introduces a practical methodology for analyzing vi¬bration records in view of improv¬ing blast designs and preempting anomalous vibrations. This technique, which is based on empirical data, uses a blasting-efficiency determinator (BED) as an indicator of vibration-energy transmission. The method was tested using data from a blasting event at an open-cast coal mine in the province of New Brunswick, Canada. The results derived from the BED values showed that geology and delay timing were probably the principal factors that induced high-intensity vibration propagation.

Jan 1, 2000

By W. C. Hellyer

In an autogenous grinding circuit in which feed at approximately nine inches top size is reduced to a size suitable for subsequent processing, the build- up of a "critical size" fraction in the media causes problems. A "critical size" fraction has been defined as, "media too small to effect reduction by impact grinding of ore coarser than a quarter of an inch and too large to be broken by the largest size of media in the charge. 9, (1) The buildup of a "critical size" fraction reduces the capacity of the mill, increases the grinding power requirements per ton of finished product, and generally produces a finer grind than is desired. It is general practice to overcome this problem by the addition of large diameter steel balls to the grinding charge. This has certain disadvantages, such as; (i) an increase in mill liner wear; (ii) wear on the steel balls, and; (iii) some loss in flexibility in grinding circuit operations resulting from difficulties in removing the steel balls by means other than by grinding out.

Jan 1, 1970

By John M. Hird

Texas Gulf Sulphur Company's Lee Creek Mine has opened a major phosphate mining district in the Central Coastal Plains of North Carolina (Fig. 1). The ore deposit as it is now known was roughly outlined in 1961 by a Texas Gulf geologist using wire line exploration methods. Slightly uraniferous phosphate materials were detected by a slim-hole gamma ray probe run in numerous farmers' water wells penetrating the formations. A follow-up-core drilling pro- gram determined the economic ore limits to lie in the south central section of Beaufort County beneath 70 feet to 120 feet of unconsolidated sediments. The 50,000 acre deposit is known to contain over two billion tons of phosphate ore amenable to strip mining methods. A part of the deposit underlies several thousand acres of the Pamlico River estuary. The 90 million dollar capital investment plant built by Texas Gulf during 1965-66 included a strip mining operation using a 72-yard walking dragline, a three million product ton per year flotation concentrator, four fluid bed calciners, a sulphuric acid plant (acid for captive use), a phosphoric acid plant, and three solid fertilizer material plants. Shipment to domestic markets is by rail and truck and to over- seas markets by barge to a transshipment terminal at Morehead City, North Carolina. Early mining investigations were conclusive first that the phosphate ore could economically be recovered only by dry strip mining methods, and second that artesian ground waters in the formation (Castle Hayne limestone) underlying the ore would have to be controlled. This report will relate the application of ground water hydrology in depressurizing the Castle Hayne aquifer to facilitate dry strip mining at depths 130 feet below sea level at the Lee Creek Mine.

Jan 1, 1970

By Jack W. Eloranta, Michael J. T. Orobona, Peter R. VanDelinder

Ore blending for process optimization is becoming an increasing factor for managing cost and productivity. Economic mining and processing a very low value ore in an extremely competitive market results in constant cost-cummng initiatives. The inherent conflict between the lowest possible mining cost and the lowest possible milling cost is reviewed here in the context of blasting for autogenous mills. Iron ore blending focuses on a number of properties-liberation values, weight recovery and concentrate silica being the most important. Other chemical and metallurgical factors are also commonly controlled. Recent research has fueled an emerging interest in blending on physical ore properties as well. Fully autogenous mills rely on the large, competent fraction of crushed feed to act as grinding media. Previous test work indicated that Hibtac mills require specific amounts of 6- to 10-inch ore. High recirculating loads require a steady influx of large rock fragments. Blast designs, therefore, are presently characterized by wide patterns and low powder factors. Current efforts are aimed at improving mill throughput while reducing overall energy costs. Based on research and published case studies and the advent of optical measuring devices, Hibbing Taconite Company has embarked on a blast optimization program to identify optimum mill feed and to design blast fragmentation goals for each geological unit and each mining area. This paper outlines the preliminary findings of an ongoing, broad-based team effort which requires close cooperation of geologists, mine engineers, crushing and milling personnel. Three specific areas of investigation are reviewed: I) Historical relationships between powder factor and mill performance, 2) Blast fragmentation modeling using the Kuz-Ram model, and 3) Drill

Jan 1, 2004

By V. R. Manukonda, I. Iwasaki

Selective flocculation of iron ores is extremely sensitive to the type and amount of soluble salts in pulp solutions. Chemical precipitation of alkaline earth ions combined with ultrasonic treatment deactivates their adverse effects without using any environmentally ill-defined reagents. The manner in which ultrasonic treatment affects starch adsorption on hematite, dissolution of quartz, and the selective flocculation process was investigated. Selective flocculation tests were conducted in the presence of up to 400 ppm calcium ion on a quartz-hematite mixture by precipitation as calcium carbonate, and the role that silicate ion generated by ultrasonic treatment plays in achieving the selectivity of separation is discussed.

Jan 1, 1988

By V. R. Manukonda

Selective flocculation of iron ores is extremely sensitive to the type and the amount of soluble salts in pulp solutions. Chemical precipitation of alkaline earth ions combined with ultrasonic treatment deactivates their adverse effects without using any environmentally ill-defined reagents. The manner in which ultrasonic treatment affects starch adsorption on hematite, dissolution of quartz, and selective flocculation process was investigated. Selective flocculation tests were conducted in the presence of up to 400 ppm calcium ion on a quartz-hematite mixture by precipitation as calcium carbonate, and the role that silicate ion generated by ultrasonic treatment plays in achieving the selectivity of separation is discussed.

Jan 1, 1987

By J. P. McDonnell, L. A. Beckett, K. Y. Hammy

Dangerously high stress areas can be controlled by proper mine planning and/or destressing. This paper reviews practical methods to detect and destress high-stress zones along coal faces. The US Bureau of Mines investigated stress-related burst problems and destressing efforts at a cooperating mine. Laboratory tests of the drilling yield method for high stress detection were conducted to determine the correlation between the volume of cuttings obtained and the magnitude of the applied stress. A three- dimemiom1 computer modeling program was used to evaluate the effectiveness of stress relief methods.

Jan 1, 1987

By G. Bräuner

The methods of burst control treated in the authors' very informative paper have been applied in the Ruhr Coalfield, Germany, for more than 20 years and have proved to be highly effective. It might be interesting here to mention a few experiences: The symptoms of critical stresses when drilling with small diameters ("test drilling") are essentially the same as described. However, we consider the situation safe if these symptoms occur beyond a certain distance ahead of the face. That safety distance equals three times the seam thickness plus the daily advance. It is the total seam thickness that counts, not merely the mined portion. Critical stresses within the safety distance are dissolved by so-called destressing measures: drilling with heavier equipment, blasting, or water infusion. To avoid bump initiation, the destressing operations should begin at the sides of the stressed zone rather than in the middle. As to water injection, there are two different principles. If the situation is critical already, high pressures are applied for hydraulic fracturing. If the stresses still allow to drill deep holes, the fluid pressure is kept low and acts for a longer time. This is to make the coal break successively instead of violently - a long-term precaution. When the stresses are very high, destressing is the most appropriate means. We mostly drill with 95 mm-diam (3.7 in.- diam). The techniques in detail are somewhat complex and subject to modifications. But the general idea is to accomplish burst prevention by controlling the potential burst situations.

Jan 1, 1990

By Raja V. Ramani

Worldwide, promulgation and enforcement of health and safety laws and regulations have been the primary means of ensuring minimum and uniform standards of health and safety in the mining industry. In U.S. coal mines, a new era was ushered-in in 1969 for the control of health hazards from respirable coal mine dust. Since then significant progress has been made on all aspects of the respirable dust problem-its definition, monitoring, reduction, and control. In the intervening years, our ability to monitor, analyze, and characterize the mine atmospheric environment and the health of miners has increased many fold. Also, advancements in production technology have far outdistanced enhancements in environmental control technology. Therefore, questions are continuing to be raised on the adequacy of the characterization and control measures with regard to both the airborne respirable dust in mines and the health effects of respirable dust. Late in 1995, the Secretary of Labor appointed an Advisory Committee on the Elimination of Pneumoconiosis Amona Coal " Mine Workers (Dust Advisory Committee) to review the progress towards elimination of coal worker's pneumoconiosis (CWP) and silicosis, and in the program to control respirable coal mine dust in underground and surface mines, and make recommendations including improved standards and other appropriate measures for the control of exposure to airborne coal mine dust. The Committee's report was released in October, 1996. In this paper, a summary of the recommendations of the Committee is presented. A brief discussion of the background, and the issues and findings leading to the recommendations is also presented. The Committee concluded that the progress made towards making mines safer from the health hazards of respirable coal mine dust is substantial but that it is not sufficient to achieve the intent of the 1969 Coal Act. The Committee's recommendations encompass a wide range of issues addressing permissible exposure limits (PELS), sampling, dust control plans, hazard and medical surveillances, role of miners, training, and research and development.

Jan 1, 1997

By J. C. Yingling, G. T. Lineberry

A control system for reducing peak loads on mine conveyor networks is proposed. The system involves continuous monitoring of flows into the conveyor network and section feeders with variable discharge capability. The control strategy uses differences in material transit times from various production units to the transfer points in the network to forecast load levels that will he intersected by the discharge of the controlled feeders over future time intervals. Feeder setpoint adjustments are made to prevent excessive peaks in the combined flows at the transfer points, while maintaining adequate feeder through flow to avoid production bottlenecks. Simulation studies suggest that the control strategy would be very effective in reducing capacity requirements of gathering belts.

Jan 1, 1993

By Jon C. Yingling

A control system for reducing peak loads on mine conveyor networks is proposed. The system involves continuous monitoring of flows into the conveyor network and section feeders with variable discharge capability. The control strategy uses differences in material transit times from various production units to the transfer points in the network to forecast load levels that will be intersected by the discharge of the controlled feeders over future time intervals. Feeder setpoint adjustments are made to prevent excessive peaks in the combined flows at the transfer points, while maintaining adequate feeder throughflow to avoid production bottlenecks.

Jan 1, 1992

By C. L. McKenzie

American Girl Mine is located in the Cargo Muchacho Mountains in the southeastern Imperial Valley of Southern California. Production from the current open pit mine and heap leach recovery system began in early 1989. Previous mining and gold recovery took place commencing in 1987 at the Padre Madre site, situated adjacent to the American Girl site to the southwest. In mid-1990, a 790-tonne-per-day underground gold mine and mill went into production. Approximately 6,500 troy ounces of gold per month are recovered from the combined open pit underground mine operation. Copper in the form of Azurite [Cu3(CO3)2(OH)2] and Malachite [Cu2CO3(OH)2] are abundant in the mined ores (Henshaw, 1942). The high solubility of these minerals in caustic cyanide solutions has a negative impact on carbon adsorption and electrowin processes. This paper presents the results of monitoring programs, process chemistry, and control changes introduced at American Girl Mine to abate production complications in the refinery and measures taken to minimize solution gold losses in the adsorption circuit(s).

Jan 1, 1993

By Malcolm D. Flavel

As indicated in the introduction to this paper, it is a sequel to that which I gave to the last annual meeting in Atlanta in march. This paper goes further into aspects of crushing and screening, primarily from the standpoint of circuit control. There has been little published by equipment manufacturers on this subject and this is the first paper on crushing circuit control to be sponsored by Allis-Chalmers corporation. By proper control over the use of crushing energy, we will be able to produce finished products from feed materials uti¬lizing minimum capital for the lowest cost of production. The subject will be discussed as follows. Firstly, we will look briefly at what we are trying to accomplish; Secondly, what is presently available in the way of technology; Thirdly, we will look at a suggested new system of control which will best fit the parameters of the normal crushing and screening operation; As a conclusion, I will summarize the advantages of the new system.

Jan 1, 1977

By Jerzy Matuszewski

Under conditions of high methane content in the seams and the descending of exploitation to greater depths, methane hazard control is becoming more and more difficult. This is due both to the amount of methane released and to the technical possibilities of diluting and capturing it. The removal of excess methane from mine workings only by means of the ventilating current has become a problem. Therefore many countries designate large sums of money for research work in the field of controlling dangerous methane accumulations and for introducing this control into mining practice. In Poland the Central Mining Institute is leading in this field. Its Safety-in-Mines Institute, Barbara Experimental Mine in cooperation with collieries has recently carried out interesting investigations on the distribution of methane concentrations in gobs behind the front of longwalls mined with caving.

Jan 1, 1980

By Robert S. Ondrey, Robert A. Haney, David J. Atchison

The Mine Safety and Health Administration has conducted tests to determine the effectiveness of two methods for reducing diesel particulate emissions in underground coal mines. Both methods involved collection of the particulate material before being released into the environment. One method utilized a disposable pleated paper filter attached to the tail pipe; the other utilized a reusable wire mesh screen attached to the tail pipe. This paper describes the instrumentation and testing used to evaluate both control methods. Results of respirable dust and diesel particulate measurements made underground are presented and analyzed.

Jan 1, 1992