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By P. D. Chamberlin

Agglomeration for the heap leaching of gold and silver ores can be defined as the process of attaching fine ore particles (less than 100 mesh) to coarser particles so the fines are immobilized and uniformly distributed throughout the heap, thus making the heap more porous and uniformly permeable to the flow of a leaching solution. Agglomeration techniques and equipment to be described include drum and disc agglomerators, stockpile and belt agglomeration, and the use of vibrating deck and reverse running conveyors.

Jan 1, 1986

By P. Crouse, J. Obermeyer

"INTRODUCTION Site location and history The Holden Mine is a former underground copper mine that was developed and operated by the Howe Sound Mining Company (Howe Sound) from 1938 to 1957. The mine is located in north-central Washington State, U.S., near Lake Chelan in the area shown as Holden Village in Figure 1. Although Rio Tinto never owned or operated the mine, they are managing and funding a several hundred million dollar clean-up to prevent future water and soil contamination and to reclaim the former mine site under the United States Environmental Protection Agency (USEPA) Superfund process. The former mine included an onsite mill and a nearby housing complex for the miners. Howe Sound developed the mine as a series of near-horizontal drifts and tunnels, interspersed with stopes and shafts that connect different mine levels underground. The tunnels that were excavated to develop the mine total nearly 100 km in length.During development of the underground workings, Howe Sound removed more than 230,000 cubic meters (m3) of waste rock from the tunnels and deposited this material in two waste rock piles. Ore was processed from the mine in the onsite mill to produce a copper concentrate that was shipped off site for smelting. Roughly 10 million tonnes of tailings were produced as a by-product of the milling operation, most of which were deposited in three large impoundments (Tailings Piles 1, 2 and 3) directly south of and adjacent to Railroad Creek. Howe Sound closed the mine in 1957. In 1961, the property was transferred to Holden Village, Inc. (Holden Village), a not-for-profit corporation that maintains a year-round community and operates an interdenominational religious retreat in the former miners’ town. With the exception of the patented private land, the remainder of the Site is on National Forest lands and is administered by the U.S. Forest Service. The mine is remote. It is only accessible by boat or float plane from Chelan, Washington, up Lake Chelan to Lucerne, nearly 40 km. Vehicle access from Lucerne to the mine is provided through a 17.5-km-long winding gravel road that climbs 640 meters in elevation. The general site features are shown in Figure 2. Physical setting The Holden Mine is located on the eastern slopes of the Cascade Mountain Range at an elevation between 975 and 1,050 m above mean sea level. Holden Mine was developed adjacent to Railroad Creek, which lies in a glacial U-shaped valley carved into the igneous and metamorphic bedrock with steep-sided slopes (Figure 2)."

Jan 1, 2017

By Russell L. Dahl

In a continuing effort to improve plant efficiency, United States Steel's Atlantic City Ore Operations completed the rubber lining of its balling drums in late 1982. This resulted in benefits of reduced bentonite consumption, reduced maintenance costs, improved production rates, and lower power consumption. These advantages far outweigh the disadvantages of increased oversize production and increased surging on the roll screen sizing devices. Certain operating characteristics and variables are discussed herein.

Jan 1, 1983

By BHAMIDIPATI S. SASTRY, Pavan Kumar Kattamuri, ADITYA PANDEY

The thermal conductivity of rock surrounding the airway is one of the most important thermal properties for estimating strata heat transfer into the mine air and for designing the air-cooling strategies. Several laboratory methods are available for the determination of thermal conductivity; however, most of them are complex and cumbersome. The present study explains the working principle of Lee’s apparatus which is relatively simple, easy to fabricate and use, and provides consistent results. In the present study, thermal conductivities of sandstone cores obtained from an Indian coal mine are determined using Lee’s apparatus. An approach is discussed for determining the temperature gradient of sandstone specimens while cooling and used for calculating thermal conductivity. The thermal conductivity of different sandstone specimens attains values between 2.37 and 2.59 W m− 1 °C−1. For different sandstone cores obtained from the field, properties including specific gravity, specific heat capacity, thermal diffusivity, and porosity, along with thermal conductivity, are determined and highlighted in this study.

Jul 20, 2021

By JIACHENG XIE, Juanli Li, Wenyong Du, Tao Cui, Mengyao Dong, Pengfei Huo

The study proposes a dynamic path planning method for mining equipment based on spatial kinematics and real-time correction of coal-rock state identification. The method integrates real geological data and equipment operation information to improve the autonomous cutting of fully mechanized mining equipment.

May 1, 2023

By John L. Shafer

A process for the conversion of stibnite (Sb2Sj) concentrates, crude antimony oxide, or metal to a pure cubic antimonous oxide (senarmontite) has been developed on a laboratory scale. The conversion of stibnite to senarmontite has been piloted. The high purity of the final product is the result of forming antimony trichloride as a low temperature distillable intermediate. To obtain the antimony trichloride the stibnite, or crude oxide is slurried in molten antimony trichloride and reacted with gaseous hydrogen chloride. Antimony metal is oxidized to the trichloride with chlorine. The hydrogen sulfide produced from the hydro- chlorination of stibnite can be upgraded to a strength of 95% or greater for further treatment. The crude antimony trichloride is separated from the gangue by a preliminary evaporation and then is fractionally distilled and the trichloride distillate has less than 50ppm of arsenic and lead combined (the most troublesome impurities in antimony processing). The purified antimony trichloride is then hydrolyzed with sodium or ammonium hydroxide to produce the cubic form of antimonous oxide (senarmontite) to the exclusion of the rhombic form (valentinite) which is photosensitive. The advantage of this process is the ability to treat a wide range of antimony ores, concentrates, and metal to yield a high purity oxide in a controllable range of particle sizes.

Jan 1, 1975

By Louis C. Just, Grahan A. Mathieson

Low cost, greater operating flexibility, and relatively simple operation are just three of the reasons for using minicomputers in the mining industry. No less than a dozen US manufacturers have sold the new generation of minicomputers to mining operations in the US and the world. Many manufacturers produce several models of minicomputers, each with excellent calculating capabilities. Prices for these "mini-giants" range from about $10,000 for a basic system to over $300,000 for a very powerful, sophisticated system with numerous peripheral devices. While the acceptance of minicomputers by the mining sector has lagged behind their penetration into other businesses, mines with minicomputer capability-especially remote mine sites-have found applications in practically all areas of operations including standard payroll processing, mineral deposit modeling and planning, surveying/mapping, production reporting, and daily production scheduling. In fact, the only limit to the further application of minicomputers in mining is the user's imagination. There are some obstacles to the accelerated use of minicomputers in the mining sector: the limited amount of software available, limited information on site-specific uses, and limited interest in the mining market by manufacturers. The latter is especially significant in light of the fact that many manufacturers queried in a recent telephone survey did not compile statistics on locations of their units in mining. The general consensus is that mining sales represent less than 1% of the total market. Many manufacturers do believe that market dynamics will increase their future research and development for the mining industry. The minicomputer was introduced in 1968, when Digital Equipment Corp. of Maynard, MA, developed a small computing device-the PDP-8 minicomputer. It is important to note that since then, it has become increasingly difficult to precisely define a minicomputer (see box, page 1582). The mini has evolved to surpass the capabilities of many of the large computers (mainframes) of 1968, and some models rival the mainframes of today.

Jan 11, 1981

By Thomas H. Ferrigno

Modern Plastics (July, 1983) reported that about 2.2 million tons of mineral fillers were expected to be consumed by the plastics industry that year, of which 7096 was limestone derived. The combination of fillers and polymers is called a composite and, in the more general sense includes continuous and discontinuous components in a matrix. The only significant technical advance in the fillers industry has been the greater general availability of surfied (Ferrigno 1959), an acronym for surface modified, fillers. The many reasons for this occurrence will be given in detail later, but the primary reason lie with differences between inorganic filler surfaces and the polymers which bind them together to form the composite. Minerals and glasses (fiberglass, fly-ash and beads) have surface tensions in excess of 200 dynes/cm, whereas organic materials have surface tensions less than 75 dynes cm. Water has a surface tension of 72 dynes/cm and is always present as an absorbed layer on high surface tension materials to reduce the surface tension. Although almost any organic liquid or polymer has a surface tension low enough to displace the water layer, the highly polar nature of filler surfaces requires highly polar agents to produce a permanent effect, and frequently the water is so tightly bonded or so much more active that the displacement is temporary. Furthermore; the water layer causes tiny particles to adhere to each other (agglomerate) to make sepaartion or dispersion of the individual particles very difficult. The solution to these problems is then to form a chemically bonded layer on the filler surface similar to that of the polymer so that immediate wetting, dispersion and uniform distribution of the filler particles is obtained.

Jan 1, 1985

By Gerald H. Luttrell, Seyed Hassan Amini, Aaron Noble

Single-unit separations in mineral processing are typically not able to meet the strict purity requirements for consumer markets. As a result, multistage separation circuits are often employed. Because these circuits represent a large and inflexible capital investment, process engineers are careful to ensure that the circuit is optimally designed to meet the desired objectives. The set of interdependent decisions that constitute the circuit design may involve the selection of different unit operations, different equipment specifications, different operational parameters, and different unit interconnections. To assist circuit designers in assessing these options, researchers have attempted to establish standard design methodologies that involve various techniques and tools.

By Yi Luo, Hua Jiang

A roof bolting drilling operation in an underground coal mine can expose the operator to a high concentration of respirable coal and crystalline silica dusts (smaller than 10 µm). Overexposure of high-level quartz dust for a roof bolter operator can lead to the development of silicosis in as little as three years [1]. This study proposes a drilling control algorithm for the bolt hole drilling process. This algorithm can be integrated into a current drilling control system on the roof bolter machinery and is expected to reduce the generation of respirable dust while enhancing the energy efficiency of the roof bolter machine. In addition, the drilling efficiency and bit condition can be evaluated while drilling based on the real-time feedback parameters. This capability enables the algorithm to ensure the drilling is performed under a relatively high energy efficiency with less respirable dust generation and to avoid drilling with an excessively worn bit that can cause bit clogging or steel buckling failure.

By RENE GOMEZ, RAUL CASTRO

Estimation tools and models are now available to estimate fragmentation, but some variables have yet to be studied to understand their effect on the fragmentation process. One such variable whose mechanisms have yet to be studied is the residence time, which in block caving directly depends on the distance that fragments travel from their original position in the broken ore to the drawpoint. In this study, granular material fragmentation was characterized during its flow to understand its characteristics and mechanisms. The results show that the breakage of fragment singularities occurred mainly within medium and smaller sizes, increasing fine material during flow. Thus, the main fragmentation mechanism in experiments was identified as abrasion between rock fragments where fine material continuously increases as distance increases in spite of the high rock strength and the piston flow movement used. The results presented here can be applied to incorporate fragmentation during flow of large travel distance of ore such as in block caving.

By Larissa Koroznikova, Steve Durkin, Patrick Bouwmeester, Michael Tuck

 This research project explored the viability of a new mining technology — thermal fragmentation — in narrow-vein mining. Thermal fragmentation technology uses a flame jet to produce extreme heat that spalls the surrounding rock to a strategically located drill hole, as an alternative to traditional blasting. This paper creates a net present value (NPV) model of a mining method using thermal fragmentation as well as one of an existing method used for narrow-vein mining. Comparisons and evaluations were made regarding the feasibility of the new technology. It was found that while overall costs for thermal fragmentation were relatively high, reductions in wages, haulage and processing costs as well as increased productivity and ore recovery meant that the new method would improve the financial performance of any operation.

By ERIK CHARRIER, ADITYA JUGANDA, Jürgen Brune, Gregory Bogin, Patrick Maier

Confined explosions are a major risk in underground coal mine operations. Depending on confinement, ignition location and obstacles in the flame path, methane explosions can transition to detonations. This research focuses on explosion experiments in a reactor with diameter of 71 cm and length of 30.5 m, along with developing the corresponding computational fluid dynamics (CFD) model that captures the observed flame behavior. The results show that the 2D and 3D CFD models are able predict the experimental flame front propagation velocity, but the 3D model shows more explicit conformity than the 2D model.

May 1, 2024

By Richard E. Lounsbury

Coal mine refuse handling traditionally has been the redheaded stepchild of the industry - a problem to be ignored as much as possible. During the past few years, however, mining companies have become more aware of the potential water pollution problem associated with refuse handling and storage. Planning for refuse disposal increasingly emphasizes protection of the environment as well as economics of refuse handling. Coal companies are responding to the environmental control needs by devising new systems and adapting well-known techniques to refuse handling systems. Monterey Coal Company has operated a non-polluting refuse disposal system at its No. 1 Mine for over two years. The purpose of this paper is to describe the design considerations given to the planning of that system and the operational experience gained during its construction

Jan 1, 1973

By M. D. Ross

Complex combinations of technical, economical, safety and environmental factors are causing mining engineers everywhere to review their operations. Naturally, some of the traditional methods still have a large role to play because they are, in certain circumstances still adequate and are well understood. But, as circumstances change, a new approach is required. The combination of technical and economical reasons for introducing Long- wall mining in some seams in the United States is associated with strata control. Other reasons include simplifications and improvement of ventilation, reduced coal dust, more output from each unit and crew, increased percentage of recovery from each area of the coal deposit, and reduction of rock dusting. The innovations which transformed Longwall mining from a cyclic to a continuous mining system were the armored conveyor and power loading machines, but the crucial breakthrough for application to high production was the development of the powered roof support, which at once gave the system the advantages of mastery of strata control, increased rate of advance, significant reduction of manpower, and increased safety.

Jan 1, 1974

By Jonq-Keh Lee

This paper deals with the effects of air leakage from intake to return airways through a series of stoppings on the analysis of coal mine ventilation. The mathematical model which assumes continuous leakage along adjoining intake and return airways is reviewed, and a new mathematical approach is presented based upon the concentrated leakage through individual stoppings. The procedure incorporating the new method in the analysis of coal mine ventilation networks is also discussed.

Jan 1, 1984

By P. A. Korpi

In March of 1978 the first set of Angular Spiral Liners utilized in grate discharge ball mills for wet grinding was put into service in the San Flanuel Concentrator of Flagma Copper Company. The use of these liners has decreased grinding media consumption by 19.2% and grinding energy consumption by 15.8%. In addition a 1.1% increase in grinding throughput is being realized through the use of the system. This paper describes the Angular Spiral Lining System and reviews the test program at the San Manuel Arizona Concentrator. Operating parameters are discussed in addition to the current testing program to futher optimize the system.

Jan 1, 1982

By Leland L. Mink

Open-pit mining is sometimes conducted in areas where the artesian pressures contained in aquifers underlying the pit's floor are great enough to cause floor heave. In order to reduce this pressure several methods are commonly used. One of these methods is a pressure relief well or depressurization wick. The wick consists of a borehole which is filled with gravel and cased at the surface. The wick is allowed to flow freely, thus reducing pressure near its location. The spacing and depth of these wicks can be determined by a simple analytical and graphical technique which considers the weight of material overlying the aquifer and the artesian force within the aquifer. An example of the technique using data from a Colombian coal mine is presented.

Jan 1, 1986

By L. E. Garner

Aggregate resources should be considered primary factors in urban development. Resource planning is essential because land values, previous construction, or zoning restrictions often preempt exploitation of aggregate deposits within an urban area. Sequential land use practices allow development of areas prior to urban development. Population and aggregate consumption trends in Austin, Texas, indicate that substantial quantities of reserves will be lost to future development. Aggregate materials are present in nearby seas. However, a comparison of transportation and reclamation costs indicates that reclaiming land after mineral extraction can be significantly cheaper than transporting materials longer distances.

Jan 1, 1979

By Roger N. Kust

Because ammonia can form complex ions with certain of the transition metals, such as copper and nickel, it has long been of interest to extractive metallurgists interested in leaching or separating these metals. Although it is a relatively expensive reagent, ammonia is amenable to recycle because of its volatility. In development of processes utilizing ammoniacal leaching or separation schemes, information regarding solution vapor pressures, pH and solubility limitations is needed. There is voluminous literature on ammonia-water systems generated by the urea industry. However, frequently the systems of interest to metallurgists differ significantly in concentrations of ammonia used, the temperatures of interest. Furthermore, the differences arising from the presence of metal values in solution must be comprehended. There is surprisingly little information readily available regarding systems of practical interest to metallurgy. As a result, those interested in ammonia-based processes end up either doing expensive laboratory research to obtain necessary data or overdesigning the process. Another approach to obtaining desired information about ammoniacal systems is to attempt to calculate from first principles the various solution properties. This paper is being presented to illustrate what can be accomplished by estimating the state of equilibrium in an ammoniacal carbonate system from available thermodynamic information making simplifying assumptions when needed.

Jan 1, 1976