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By J-Y Chen

China was once deficient in nickel and almost totally reliant on imports for its domestic needs, supplies mainly coming from Canada since the ending of imports from the U.S.S.R. in early 1960's. However, the discovery of the huge nickel/copper sulphide deposit in Jin Chuan, Gansu Province of northwestern China in late 1950's and its development and construction through the 1960's and 19701s, have much improved China's domestic nickel position. In 1985. China's nickel production has exceeded 27.000 tons, compared with only 7,000 tons in 1977. Today, Jin Chuan Nonferrous Metals Company operates two underground mines and a small open- pit; owns China's largest reserves of nickel and platinum, and the second largest reserves of copper and cobalt; and has become the most important subsidiary of China National Nonferrous Metals Industry Corporation (CNNC) which was established in April 1983. The Jin Chuan nickel-copper mines are located in Jin Chang City, Gansu Province, 1,700 km west of Beijing in the People's Republic of China (Figure 1). It is believed that Jin Chuan mines have the second largest nickel reserves in the world, after Sudbury basin, Canada. The deposits are situated on the north slope of the Longshu Mountains, 50 km north of Jin Chang City, and border on the southmost edge of the Gobi Desert plateau. The deposits were discovered in 1958. The total strike length of mineralized zones was approximately 6.5 km long, which was divided into four mining areas by faults (Figure 2). The Longshu underground mine of No. 1 mining area began development in 1959, with full ore production capacity of 1,000 TPD. The open-pit, also in No. 1 mining area, which was brought into operation in 1966 with ore output of 5,500 TPD, was closed down in 1982. The East Extension of the open-pit was put into operation in 1983; present production capacity is about 2,200 TPD. Nickel production of Jin Chuan mines in recent years, and production capacity of each mining operation, are shown in Tables 1 and 2.

Jan 1, 1987

By T. P. Meloy

Oily and particulate befouled waste water discharges are a common industrial problem. Removing these water bourn emulsions from process discharges become increasingly important for both recycled and discharge water streams. Low cost, efficient and easily maintained systems are important. This paper evaluates design factor of such a water cleaning system -a trough filter. This is a continually operating filter that removes oil droplets by wires that wet the oil droplets.

Jan 1, 1994

By Paul Grisley

Air-supported belt conveyors-conveying systems that replace troughing idlers with a film of air-were a revolutionary concept when introduced in the 1970s. But high installation and operating costs limited their application. Now, system refinements have led to successful applications, even under the challenging conditions of mines and process plants. In this presentation the author will discuss the latest developments in the engineering of these systems, including the ability to retrofit existing transfer points with modular air conveyor components. Air conveyor applications and limitations in mineral-handling operations will also be examined.

Jan 1, 2002

By H. Colijn

The design of bulk materials handling facilities is greatly influenced by the handling characteristics of the bulk solids. For instance, free flowing materials need only small discharge openings in hoppers, while cohesive materials require large discharge openings. Chute and hopper slope angles are affected by the sliding friction coefficients. During the past ten years, large lignite deposits in Texas are being opened up for energy production, both in generating plants as well as in synfuel projects. The early plants have encountered many problems in handling and storing this lignite. This paper will provide some information about the handling characteristics of Texas lignite.

Jan 1, 1982

By Kent E. McElhattan

The selection of efficiency machinery for an underground mining system is a highly skilled art. Modern techniques of mining, based on sound engineering principles, increase the probability of success. These techniques alone, however, will not guarantee maximum productivity. Human judgement, based on experience with mineral seams and geological conditions, remains the single most important input of the decision-making techniques in selecting high production equipment. The myth of a "Scientific Selection Factor" is absurd. The belief that such a factor exists can waste the time and resources of mining management. Until now, mineral extraction from the original desposit has defied all attempts to systematize the knowledge. Computerized programs are excellent for solving underground transportation and ventilation problems. The variables can be defined by mathe¬matical techniques in this type of problem. By the same, token, "Trial and Error" is not an acceptable method in today's technology-minded world. The candid truth of the matter is that practically nothing is known of the phenomenon of extracting a mineral from the solid. Likewise, local conditions make it nearly impossible to predict accurately the reaction of surrounding strata after the mineral has been removed. The unpredictability of the environment resulting from extracting minerals underground will remain a challenge to mining engineers for many years. In fact, we are barely beyond the trial and error stage at this point in time.

Jan 1, 1969

There are several simulators available and are being used for analysis, improvement and optimal control of the grinding process. However, these tend to be developed on informal software engineering methodologies. The informal approach is not suitable for long term development and a formal design methodology is necessary to develop efficient, error-free, and easy-to-use and to maintain software. In meeting this goal, basic concepts of a software model for describing the mineral process objects has been proposed. The software model forms the basis for software design and efficient implementation of the simulation. This paper describes the development of software models for grinding circuits. The work constitutes the theoretical foundation for the development of an advanced simulator for comminution.

Jan 1, 1995

By Arthur S. Cornford

According to Arbiter (Reference 1), the ball mill was invented by Brückner in Germany in 1876 and was first used in the United States on ores about 1905. The basic concept was a simple rotating cylindrical drum in which the tumbling action of the charge of material and grinding media resulted in size reduction of the material. Despite the very low mechanical efficiency of this method a number of factors have caused the tumbling mill to remain, by far, the most widely used piece of equipment for mineral grinding. The principal factors influencing this situation have been simplicity of design, ease of manufacture, ready adaptability to familiar material handling layouts and the absence of practical alternatives acceptable to the industry. In the early mills, the material was ground in batches, the mills being charged and discharged through doors in the shell. The shell was supported by means of solid trunnion shafts resting in plain bearings and the drive was accomplished through one of these shafts. In some later batch mills, the mill shell was supported on rollers which were also used to drive the mill. At an early stage, continuous operation was made possible by feeding and discharging the mill through hollow trunnions, the method still in most widespread use. The mechanical and structural design of the early mills was not an onerous engineering task. Norse sense and good practical knowledge were key qualifications. The mill shells had to be heavy enough to withstand the physical abuse they would receive in the field and the bearings had to have low enough unit pressures and sufficient wear retol to ensure several months of operation before the need for replacement occurred. When these requirements were satisfied, stresses developed in the equipment during operation were insignificant and the majority of structural failures were probably due to the use of inferior materials in manufacture. Over the years, the ever present demand for increased productivity has resulted in a steady Increase in the size of units of production equipment, including grinding mills. Arguments have been presented elsewhere, for and against the Idea of a high throughput single line grinding operation as opposed

Jan 1, 1972

By Yuexin Han, Yanjun Li, Peng Gao, Yongsheng Sun, Qiang Zhang

The non-isothermal magnetization roasting process and isothermal magnetization roasting process of siderite ore were investigated using thermogravimetric (TG) analysis and a real-time infrared gas analyzer. X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) were used to analyze the characteristics of samples. The results showed that the decomposition degree and decomposition rate of siderite ore were vitally affected by heating rate and roasting temperature. It was determined that A1 reaction model (f(α) = 1 − α) and A3/2 reaction model (f(α) = (3/2)(1 − α)[−ln(1 − α)]1/2) were the most probable mechanism function of the non-isothermal decomposition process and isothermal decomposition process, respectively. The phase transformation and decomposition mechanism during the roasting process were evaluated. Siderite decomposed in the process of magnetization roasting, released CO and CO2, and transformed into strongly magnetic magnetite. The SEM images highlighted that as the decomposition progressed, the structure of roasted samples was destroyed, and an increasing number of cracks and pores emerged on the surface, which is advantageous to the following grinding process.

Mar 26, 2021

By D. Burkhard, E. Herth

"Geologic structure and properties are the primary influences on ground control at San Juan Mine. Geotechnical properties of the coal seam and near seam strata, the presence of above seam sandstone paleochannels and water, are thought to be the leading contributors to ground control issues. It is the confluence of specific geologic conditions rather than isolated features that most often produce adverse conditions. Altering primary support installation and mining practices are done when unfavorable conditions appear during development. Installation of standing support is most often employed when adverse conditions develop at later dates. REGIONAL GEOLOGIC SETTING San Juan Mine is an underground coal mine located on the western flank of the San Juan Basin in northwest New Mexico. The San Juan Basin is contained within the south eastern region of the Colorado Plateau geographic province. The basin contains multiple coal bearing formations and is also a major producer of coalbed methane gas. San Juan Mine is stratigraphically located within the Fruitland Formation. From a prominent monocline marking the western boundary of the basin, the formation dips gently to the east towards the center of the basin. The primary driver for the deposition of coal bearing formations within the basin was the Cretaceous Inland Seaway. Multiple cycles of transgression and regression driven by sea level rise and tectonic subsidence deposited rock types from marine shale’s to terrestrial sandstones. The Sevier Mountains to the west of the seaway likely provided the sediment supply for the Fruitland Formation. During a major cycle of seaward regression, the Pictured Cliffs Sandstone Formation prograded over the marine Lewis Shale. The coal bearing Fruitland Formation followed, being deposited over the Pictured Cliffs. The Fruitland Formation contains numerous coal seams and is approximately 400 ft. thick at San Juan Mine. Fruitland Formation coal seams are numbered in order of superposition. San Juan mines the Fruitland number 8 seam. Dating has placed the age of the seam at approximately 73 to 75 million years [1]. LOCAL GEOLOGIC SETTING The Fruitland 8 coal seam dips approximately 1-3 degrees towards the E-NE. At San Juan Mine, the seam displays a mild plunging, synclinal structure, the axis roughly bisecting the mine from west to east. The number 8 seam consists of five coal benches and four volcanic ash band partings labeled sequentially based on superposition. The lowest portion of the seam is the 8-1 bench, the 8-2 through 8-5 benches following sequentially to the top of the minable seam. Ash band partings are labelled P1 through P4 from bottom to top respectively. The presence of distinctive partings and benches allows for seam definition and aids in identifying mining horizons."

Jan 1, 2016

By Norman M. Junk

Following the wide-spread acceptance of ANFO as a useful, low cost blasting agent, studies have been made to adequately describe the physical and explosive properties of this material (1). As the quality of the AN blasting prill improved, reliability and sensitivity to initiation were greatly increased and many methods of priming were chosen from the standpoint of economics with little appreciation for the need to initiate so as to obtain the most efficient detonation. Under certain conditions, ANFO could be initiated with primers no more powerful than a No. 8 blasting cap (2). Research on primers for ANFO followed and it was demonstrated that this blasting agent was subject to extreme transient velocities upon initiation with wide variations in energy output depending upon the nature of the primer. For these reasons it was shown that powerful priming was economically justified (3). These studies helped to define the properties of an effective primer and the guides for its efficient use. In the vast surface coal mining industry, technological advances in earth moving equipment were paralleled by the development of larger and larger borehole drills (4). Even though ANM) was the major blasting agent used in this industry, investigations of priming techniques in these larger boreholes was almost non-existant. In 1962, Mr. Cleon Woolsey of Enos Coal Company disclosed to the industry that dramatic improvements in blasting production could be achieved with new priming and boostering methods (5). The research program at the Atlas laboratories was designed to explain these results and extend the study of initiation of ANFO with both high explosives and slurry explosives and to define the principles involved.

Jan 1, 1968

By P. C. O. Chukabarah

Many aerodynamic and thermodynamic properties, such as temperature, pressure, velocity and density vary widely, and in random spatial and temporal manner for a given underground mine environment. Such variabilities are seldom evaluated statistically, even though the relevant theories and principles for such an approach are both available and feasible. The main purpose of this paper was to introduce the new methodology of applying aerostatistics to the analysis of multiple fan system in mine aerology and/or ventilation. Pertinent data were obtained from a small multilevel coal mine. Results proved and confirmed that aerostatistical methodologies are computationally more efficient, grounded in solid engineering statistical theories, and can be used to analyze networked parameters in mine environmental engineering.

Jan 1, 1994

By S. C. Howell

The mining of taconite, to provide feed for a processing plant, requires that the flow of material continue uninterrupted. This means first, that the crude must be of a size acceptable to the primary crusher in order to reduce the delays caused by plugging the crusher with chunks. Secondly, elimination of oversize in the pit will reduce costs of all wear parts used in the mining and processing of taconite. Savings in wear parts is readily recognized in dipper teeth, bases, buckets, truck boxes, and crusher parts, both primary and secondary. During the early days of taconite mining, it was soon recognized at reserve mining company's Babbitt operations that experience in mining other ores was not always (or ?necessarily??) Applicable to excavating taconite. This was especially true in drilling and blasting. Blasting of small tonnages in single or double rows simply filled the pit with scattered chunks and provided very shallow banks for shovel loading. It also created problems for the jet piercers, since all drilling had to be performed in fractured areas. Drilling efficiency suffered and costs were extremely high. Shovel and truck efficiencies were also low and again costs were high. A high percentage of secondary breakage was required. This necessitated the use of numerous man hours to jackhammer holes in chunks, preparatory to loading and blasting. After the chunks were reduced, bull- dozer and grader hours were needed to pile the taconite for acceptable shovel loading.

Jan 1, 1968

By James Corcoran, Richard McLane, Matt Neuner, Joseph DeMello, Hugh Davies

The Los Angeles County Metropolitan Transportation Authority (LA Metro) Purple Line Extension Section 1 (PLE1) is a $3.12 billion USD design-build, underground heavy rail project, connecting an existing station at Wilshire Blvd. and Western Ave. and extending 3.92 miles under Wilshire Blvd, terminating approximately 550 feet west of Wilshire and La Cienega Blvds. The project alignment runs immediately adjacent to the La Brea Tar Pits, world renowned for Pleistocene fossils and continuous seepage of asphaltum (locally known as tar) and gas in an urban setting. This paper presents a successful case history of the planning, design, and construction efforts to safely construct the bored tunnels through Reach 3 of the alignment (between Wilshire/Fairfax Station, and Wilshire/La Cienega Station), in a designated Methane Zone in the City of Los Angeles. Historical context on decades of challenges and studies is summarized. Further, this paper outlines the pro-active partnership between the Owner: LA Metro, the Design Builder: Skanska-Traylor-Shea Joint Venture, and geotechnical design services provided by Golder Associates to safely manage pressurized face tunneling through a confined gas zone near the La Brea Tar Pits. Specifically, a program of in-situ oxidation and soil gas extraction was designed to test and analyze risks associated with pressurized face TBM tunneling through the complex subsurface geological conditions, then implemented during construction. In advance of tunneling, a network of wells was used to draw air into the gas zone to oxidize the 6,500 ppm hydrogen sulfide gas, as well as determine methane recharge rate. During TBM tunneling, the wells were converted to a gas extraction system to evacuate, filter (H2S) and burn (CH4) the gas as the Tunnel Boring Machine passed, providing a preferential pathway for the gas to migrate toward extraction wells, and preventing the migration to adjacent buildings. The team extracted and treated 3,857,000 cubic feet of mostly methane gas over 40 days as the TBMs passed through the zone. Gas behavior, pressures, and concentrations were monitored not only from the extraction system, but also in basements and utility vaults along this section of the alignment.

Jun 13, 2023

By Roland Hoet, Jim Patilla, Nick Madison

Increasing conveyor capacity and reliability is a common goal for many underground mines. This task is especially challenging when you must work with existing structure, belt, etc. Meeting this challenge, The Pittsburgh & Midway Coal Mining Co. North River Mine switched from constant fill to actively controlled fluid couplings, realizing a capacity increase from 2,100 tons per hour (2,300 stph) to 2,550 tons per hour (2,800 stph), with improved reliability. This paper will present a case study of The Pittsburgh & Midway Coal Mining Co.'s North River Mine underground conveyor haulage system. These conveyors included the main line conveyors as well as a tension controlled tripper booster panel conveyor. Characteristics and performance of the coupling and control system will be illustrated, demonstrating the systems controllability, simplicity, and dependability.

Jan 1, 2002

By Edgar T. Gregory

A quiet revolution has taken place in the conveyor belt industry, Man-made materials, improved production facilities, better splicing techniques and emphasis on repair and maintenance have all contributed substantially to lowering material handling costs for the mining industry, It wasn't too many years ago that the rubber industry had only cotton for a belt carcass and tree grown rubber for the protective cover. Then came the development of monofilament rayon. This material had desirable elongation and elastic properties and was the first synthetic fiber to be used in place of cotton. But wet strength and other limitations restricted its use, and the conveyor belt industry turned to nylon. Initially, nylon was considered suitable only for the cross threads or filler threads of a belt carcass. Then technical advancements in heat setting and fabric weave created a major change in belt construction. As a result of these advances the industry was able to take advantage of the full tension strength of nylon cord. Another breakthrough in the use of synthetics was the tremendous increase in adhesion resulting from a chemical bond, rather than the limited physical bond available with cotton. But the advantages of nylon had a more Car-reaching effect, We were able to design a two-ply nylon belt that did the work of a four- or five-ply cotton or rayon belt. A six-ply nylon belt now replaces a twelve-ply cotton elevator belt. Arid nylon resists moisture, acid and mildew, It also has excellent resistance to impact and can be produced with controlled elongation and elastic properties that work to great advantage in reduced-ply belt constructions.

Jan 1, 1971

Room-and-pillar mining at White Pine started in 1953 from a sub-outcropping orebody that gently dips to 1000 m depths in a distance of about 6 km. High horizontal stresses were recognized in the mid-1960s which had obvious stability impacts when viewed in combination with the increased overburden stresses. Modifications in conventional room-and-pillar design were introduced through the years on a trial-and-error basis to help overcome stability and resource recovery problems. These modifications were based on pressure arch concepts using pillar yielding and/or pillar recovery, and on mine layout orientation to minimize stress impacts. While some of these modifications were successfully applied in some areas, they failed in others. Through the years, visual observations played a major role in panel design with contributions from stress measurements and analyses. However, the down slide in the copper economy during the 1970s and early 1980s resulted in a loss of interest in the application of these concepts. This paper reviews ground control problems and presents the results of recent stress measurements and computer analyses. They shed light on the importance of using yield pillars and mine layout orientation to control stresses at depth.

Jan 1, 1993

By J. Douglas

The past year has been a strange one for the fertilizer industry of the world and the United States. Listening to news stories, you would think the sky is falling on the world's agriculture and probably conclude that we should have had an exceptionally poor fertilizer season. In some respects, we did. Prices were low, profits were low, and in some cases nonexistent, but volume was good. We heard much in the press about the farmers' credit crunch. The truth of the matter is that only 6.6 percent of the U.S. farmers have debt-equity ratios of 70 percent or more, and a large percentage of our farmers have absolutely no debt but operate entirely on their own cash assets.

Jan 1, 1985

By B. A. Kuyper

The Cove gold-silver deposit is located 50 km southwest of Battle Mountain, Nevada and 1.5 km northeast of the McCoy Mine. Total proven and probable reserves are 48.7 Mt (53.7 Mst) with an average grade of 1.85 g/t (0.054 oz/st) Au and 87.1 g/t (2.54 oz/st) Ag. Mineralization is hosted by Triassic carbonate and siliciclastic rocks in two separate orebodies. Oxide ore consists of disseminated gold and silver in clay-altered, manganese-flooded limestone. Sulfide ore is dominated by pyrite-sphalerite-galena veins in siliciclastic rocks and sandy dolomite. Gold and silver occur in the native state, associated with the base metal sulfides. Mineralization is interpreted to be the distal expression of a porphyry system. The McCoy gold (copper) deposit is interpreted to be the proximal expression of the same system.

Jan 1, 1991

By J. C. Cawley

Improvements in today's maintenance practices are mandatory as more complex and productive machines evolve in the mining industry. By keeping machine reliability high, through improved maintenance procedures, overall mining costs can be reduced. The Bureau of Mines is investigating diagnostic maintenance systems for underground mining machinery. A hydraulic expert diagnostic system and an electric motor predictive diagnostic system have been designed and installed on a Joy 16CM continuous miner. An electrical diagnostic system has been designed and installed on a Joy 14CM continuous miner. Each system is functionally described and the relative merits of expert diagnostic systems versus algorithmic diagnostic systems are discussed.

Jan 1, 1991

By Evan Adams

The Ireland Mine is located some seven miles South of Moundsville West Virginia, along the bank of the Ohio River. We are mining the Pittsburgh #8 seam. This seam is approximately 60" in thickness, and is immediately overlain by some 10 feet of a conglommerate material. The roof is difficult to control, due to the fact that it frequently is composed of substances not hard enough to be held together with 6-foot roof bolts. In many cases, we must use 10-foot roof bolts, in order to get bolt anchorage in the limestone above the conglommerate. Due to the elasticity of the limestone and its tendency to bend rather than to break, we have been unable to maintain a pillar line. Thus, we have found it necessary to mine by the room and pillar system. Belt haulage is used on room entries to automatic loading stations, thence into 15-ton mine cars, controlled at the loading point by car spotters. The maximum belt length is 2,000 feet. Rail haulage to the slope-bottom dump is by 27- and 50-ton locomotives. The mine produces coal two shifts per day, with 7 production crews on each shift. Mine and machinery maintenance is performed on the Midnight shift. We handle an average of 660 tons per machine shift.

Jan 1, 1964