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By C. D. Kuchera

Ore crushing facilities at the Phelps Dodge Morenci Reduction Works became operational in January of 1942. This plant, with a capacity of 25,000 tons per day, was part of a project started some five years earlier with development of the Morenci Open Pit Copper Mine. In the following year, World War II's heavy copper demands prompted an 80% expansion in concentrating capacity to 45,000 tons per day resulting in a doubling of the secondary crushing plant. In the late 1950s and early 1960s, grinding capacity was again expanded to the present 60,000 TPD. This time the then 20 year old crushing plant was obliged to meet a 20% increase in production demand with no additional equipment. The ore, principally a medium hard monzonite porphyry, is dumped from 40 yard rail cars into an ore pocket over the primary crusher at a rate of approximately one car per minute. The primary crushing flowsheet, Figure 1, has remained essentially unchanged over the years. Equipment consists of a 40 by 16 foot grizzly set on a 40° incline and having 6" openings, a 60" gyratory crusher nomin¬ally set at 62" + 1" on the closed side and two 72" by 38' panfeeders which load crushed ore and grizzly undersize at a rate of 4,000 tons per hour onto a twin 54" belt conveyor system for delivery to the coarse ore bin. Ore is distributed across the bin by two single side discharge tripper cars. Bin capacity is extremely limited at 23,000 tons of which only 12,000 is available or "live".

Jan 1, 1975

By D. W. Wu, M. T. Haque

A novel impedance probe has been commissioned specifically for capturing fast dynamic information about filtration processes. It provides an attractive alternative to more complex measurement techniques in situations where the slurry system is primarily one-dimensional. The probe can monitor mud-line, slurry densification and drainage. Dynamic variations in cake permeability are obtained by combining dynamic mud-line information obtained with the probe and filtrate rate data derived from a leaf test apparatus. The measurements are re-viewed in relation to micro structural measurements obtained on iron ore filter cakes. The practical significance of these measurements for optimization of the filtration process is discussed.

Jan 1, 2000

By S. S. Xue

A study has been conducted to remove iron from sulfate solutions using Eichrom's Dipex® extractant, P,P?-di(2-ethylhexyl) methanediphosponic acid (H2DEH[MDP]). It is found that this extractant can effectively and selectively extract ferric ion from highly acidic solutions. Ninety-nine percent of the iron was extracted from a simulated feed solution in a single stage. The separation factor, Fe/Zn, was 10 6 Over 90% of the iron in a loaded organic can be recovered in an aqueous solution by reductive stripping. This paper presents the experimental results. A new process for iron removal using Dipex extractant is described and discussed.

Jan 1, 1999

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 M. Fustic, A. H. Paul

The geology of the Muskeg River Oil Sands Mine is described to demonstrate how geologic modeling aided in resource evaluation and material characterization during the feasibility and construction stages. Bitumen is hosted in the clastic sediments of the Cretaceous McMurray Formation which is informally divided into members representing the fluvial, estuarine and marine environments of this transgressive sequence. Lithofacies mapping of drill core provides further detail to classify materials as resource type, for extraction suitability and for construction suitability. Geologic interpretation provides tools for the engineers to produce effective mine plans and for the operators to execute them during mine development.

Jan 1, 2002

By Steve Wirch, Robert Jankowski

The issue of dust control in underground coal mines has been extensively studied by both government and industry. This research work has resulted in many techniques which control the dust or help miners avoid it. Control techniques either prevent the dust from becoming airborne or cleanse the air before it can be inhaled. Avoidance measures minimize the exposure of miners to the airborne dust by blowing the dust away from work areas or making it unnecessary for a miner to occupy a dusty region. One of several successful dust control measures in continuous miner sections is the use of a machine mounted scrubber which cleanses the air and helps to prevent the contaminated air from reaching areas frequented by mine personnel. Research on the application of scrubbers on longwall shearers began in the 1970s and continued into the 1980s. The most successful projects showed only moderate improvement when a scrubber system was mounted on a longwall shearer, and the less successful projects actually increased worker dust levels. There are many reasons that scrubbers have not been successfully applied on longwalls. The most significant of these is that longwalls have across the face ventilation and generally have high face air flows. Scrubbers tend to work best when they are the primary cause of ventilation. Therefore, their capture efficiencies on longwalls tend to suffer because of the exposure of the drums to the primary airflow. Other reasons scrubbers have not been implemented on longwall s include the successful application of an excellent water spray system, effective cutting techniques, and dispersion of dust sources. These techniques can help control drum generated dust, increase production, and limit the relative effectiveness of a scrubber.

Jan 1, 1995

By Victor F. Hollister

Skam deposits considered as porphyry copper deposits have been classified into three basic prospecting models: (I) the skam deposit associated with a mineralized intrusive (Pima-Mission), (2) the deposit associated with a barren igneous stock (Ertsberg), and (3) mineralized rock that seems to have no clear association with apluton (Phoenix). Pima-Mission, Christmas, and many other copper-bearing skarns developed in carbonate sequences near mineralized intrusives form an important part of the deposit. Historically, copper derived from the mineralized intrusion accounts for less than half of the metal produced by most porphyry mines, as most mineralization occurs in the intruded rocks. Skam mineralization is an important part of wall-rock metal deposition, because carbonate sequences are preferentially replaced by sulfide and skarn minerals. Exploration for skam mineralization is an important phase of porphyry copper exploration. Impure carbonate beds can become better host rocks for skam deposits than pure carbonates, and these in particular should be included in porphyry-exploration programs if the impure strata are cut by the stock. Skam deposits can also form near stocks that are barren of sulfide. In this model, the two best ore guides are strata favorable for mineralization (usually impure carbonate beds) and the intrusive contact. Faults can also act as important ore controls. Some skarn deposits form that have no clear genetic connection with a stock, although intrusive rocks are known in the district. In such cases, the best ore guides are strata and district-wide faulting. Dikes and sills are also common and mineralization can locally prefer their contacts even though the igneous rocks are barren. Skam minerals are influenced by the chemical composition of the carbonate. Forsterite, brucite, tremolite, and talc are common in skams developed in dolomitic beds. Skams derived from calcic beds often contain wollastonite, calcite, stilbite, or idocrase. Diopside, however, is a common accompaniment of copper sulfide in skam regardless of the original composition of the carbonates. Tremolite and possibly other amphiboles and chlorite can occur significantly in the zinc-lead portion of skams. Gamets occur in magnetite, copper, and zinc-lead zones of skams, but are not as diagnostic as diopside for the copper zone or tremolite for the zinc-lead zone. A general desciption of skam-deposit mineralogy can be used to construct prospecting models of porphyry copper skams. An abstract of such a description follows.

Jan 1, 1991

By F. Dahl, P. Raleigh, J. Holzhauser, B. Nilsen

Tunnel excavation using tunnel boring machines (TBMs), has become increasingly common in recent years, despite the fact that precise evaluation of certain risks have not kept pace with the use of these machines. One of the risks easily overlooked by Engineer and Contractor alike are the effects of abrasive ground on the costs and schedule of a given project. The impacts of worn and damaged TBM cutter heads have been observed on hundreds of tunnel projects around the world. It would appear that a reliable prognosis of the abrasiveness of soils on a project would be of great importance for designers, clients and contractors alike. Several well acknowledged test and prognosis methods already exist for rock, however there is only very limited knowledge available to describe the abrasiveness of soil and its impact on soft ground TBMs. This paper will examine approaches to this problem and suggest a new approach based on a current project undergoing design.

Jan 1, 2007

By B. Seegmiller, W. A. Hustrulid, O. Stephansson

Introduction The concept of in-the-wall haulage was formally introduced to the mining community in the early 1970s. The basic concept is simple. Rather than the traditional in-the-pit haulage/access ramp, single or twin ramps driven in the pit wall are used with crosscut connections on the working levels. The in-the-wall pit haulage system could be considered as part of the opening of a new mine, a way of completing to final depth an existing pit, or part of the transition from open-pit to underground mining with the ramp remaining as part of the access. This paper is intended to acquaint the reader, particularly mine planning engineers, with some of the possibilities presented by the concept. Nordstrom (1983) said, "In many countries, mining engineers are either open-pit or underground specialists and, hence, often don't consider the possibilities for combining the best aspects of each into a hybrid mining system." This is believed to be true. There are few "hybrid mines" employing, for example, open-pit methods with underground haulage systems. One reason is the variance with the experience of the mining company and the engineers involved. However, with today's low metal prices, innovative and unconventional thinking may be just what a property requires to remain in production. All the possible situations where an in-the-wall ramp might be considered cannot be presented here. Rather, a few examples will be discussed for illustration purposes. Potential savings in stripping costs A major cost in open-pit mining is associated with the removal of overburden and waste rock. Although much of this stripping cannot be avoided, the volume (V) associated with the presence of an in-pit haul road can be quite large, V 100 (pit depth) a (road width) 2 x road grade (%) As an example, consider a vertical ore body 400 m (1312 ft) long, 60 m (197 ft) thick, extending to a depth of 160 m (525 ft). Cross sections are shown in Fig. 1. Other data are: ore tonnage = 11 Mt (12 million st), ore density = 2.9 t/m3 (0.09 st per cu ft), waste rock density = 2.7 t/m3 (0.08 st per cu ft), road width = 20 m (66 ft), road gradient = 10%, and level interval = 10 m (33 ft). The evaluation has been made assuming that the pit slope (0) is constant around the pit except on the side with the haul road. On this side, the slope is decreased to allow for the road. Slope angles of 30° to 60° have been selected to indicate the dependence of stripping volume (V) on slope angle. The stripping at the ends have been calculated assuming representation by cones. The volume associated with the haul road is 2.6 Mm3 (92.8 million cu ft). A comparison of the strip volumes involved is shown in Table 1. As can be seen, the percent savings in strip volume varies from about 4% to 17% and depends greatly on the slope angle. It is perhaps more interesting to examine the savings in stripping costs that could then be used to cover the cost of the access ramp and the crosscuts for stripping costs of $3/m3 ($0.08 per cu ft). The cost with the road volume is 2.6 million x 3 = $7.8 million.

Jan 1, 1988

By Richard Addison

Introduction A staccato beat rings out across the Australian bush. The stamps are at work, slowly pulverizing gold-bearing ore for a patient, grizzled prospector. This is the State Battery near Marvel Loch, a tiny 22.6-t/d (25-stpd) capacity gold plant operated by the Western Australia government. It is one of many such plants located in remote corners of Western Australia and the Northern Territory. They are miniature custom mills operated for the benefit of prospectors and small mine operators. These state batteries are so called because they are operated by state governments and because the principal item of machinery in the plants are stamp batteries. They are fascinating anachronisms - throwbacks to times past, a century ago, to the hard and heady existence of gold rush days. Marvel Loch plant Typical of these operations, and perhaps a trifle more sophisticated than most, is the plant near Marvel Loch, a small center for mining and farming about 400 km (250 miles) due east of Perth. Marvel Loch. The name evokes visions of a pristine lake set in a cool, green, misty glen of the Scottish highlands. Actually, it is probably a hot, dry salt pan somewhere nearby. Just where the "loch" is difficult to discern. There is no sign of it on the map.

Jan 7, 1986

By D. A. Dahlstrom

Since the initiation of continuous vacuum filtration over a half a century ago, control of the performance of these units has been largely in the hands of the plant operators, Obviously there has been the introduction of variable speed drives, adjustable speed feed slurry agitation, vacuum control, etc. However, control of , filtration rate, cake moisture content, dissolved solids recovery by cake washing and dryness of solids where thermal drying is practiced is primarily up to the operators judgment and the settings he imposes on the controls he regulates, - filter cycle time, submergence, vacuum level, filter medium condition, wash water- rate, and other such factors. While this may seem to indicate that good operators are a paramount necessity, and certainly always desirable, a considerably more vital factor is a properly designed filter and filter station for the particular application. With improper design, highly skilled operator control will still leave much to be desired in the way of process performance. On the other hand, with correct design and application, the operator can easily and quickly control normal plant surges and quality variations within the flow sheet. Due to the growing complexity and inter dependency between the various processing steps in the modern flow sheet as well as the rising costs of capital investment, labor, maintenance, and losses involved with off quality product or insufficient recovery, automatic or inherent performance control of many of the unit operations within the metallurgical mill must be achieved. Continuous filtration should and can be susceptible to such control. However, as every instrument engineer knows, before control and automation can be achieved, a basic understanding of the operation is mandatory. This is primarily due to three factors. First, as in so many control applications, it may not be possible or feasible to measure the factor that it is desired to control. Thus, secondary variables that influence the major factor are substituted for control purposes. Secondly, it is always desirable to take advantage of any ?self-regulation? within the operation being performed on the equipment. In so doing, not only will automatic control be facilitated, but instrumentation is minimized while experiencing most efficient operation. Finally, automatic control is not a cure-all for improper process and equipment design and application. Hanging instruments on such an operation can be compared to constructing a sizable building on sand, Results will be disappointing.

Jan 1, 1960

By Ramarao Inguva

Feasibility studies being conducted to investigate the use of electromagnetic methods for insitu volumetric heating of oil shales will be discussed. A two dimensional numerical model which describes eletromagnetic heating of oil shales is outlines. The model includes equations for temperature, pressure, saturations, chemical reactions, mass conservation, and source terms. The gases are all assumed to form one bulk species and the oil is assumed to remain in liquid form. The chemical reactions include pryolysis of kerogen and char, release of bound water, coking, and decomposition if carbonates. Porosity and permeability are dynamic functions of the organic materials. Calibration of the model is accomplished by comparison of the model results with experimental data obtained by IITRI. Nonlinear relationships for viscosity, thermal properties, and source terms and used as inputs to the model. A finite difference approximation to the differential equations is derived and solved using Newton's iteration technique. For the cases studied the solutions are quite stable. Numerical resultes are included and a preliminary study of the optimization of the heating process is presented.

Jan 1, 1984

By John M. Hill

Automation technology has many facets, some well tested and proven, some yet to be put to the acid test of economic reality. In this paper, we will limit our purview to the former. Consider, if you will, an automated handling system combining high-speed conveyors and automatic devices on-line which not only provide signals for routing and sorting, but also format those signals for the production of manufacturing, inventory, shipping and billing paperwork. This is not futuristic, but practical and a realistic accomplishment. Therefore, the following discussions will address today's challenges not with tomorrow's solutions, but rather, with an established technology which is playing an increasingly prominent role in materials handling systems. Until recently, relatively modest importance has been attached to the timeliness of information feedback from the production or assembly line, warehouse or distribution center. Thus, initial applications of automatic identification equipment focused almost exclusively upon the control of materials flow - that is, routing, sorting, etc. However, these systems have performed successfully and quietly established an enviable track record as reliable materials control tools.

Jan 1, 1973

By Thomas A. Wheeler

The reagents commercially used in coal flotation and their roles are reviewed and discussed According to their function the reagents are divided into often overlapping groups: 1. Collectors 2. Frothers 3. Conditioning Reagents Frothers have by far the largest effect on the amount of coal recovered They act not only in their traditionally accepted function of “bubble makers”, but in coal flotation they serve in a seldom acknowledged role of collectors. A lab flotation study on four samples of different coal ranks shows how these react to various frother families and proves that no froher is the optimum reagent for all types of coal. The advent of new technology in flotation equipment in the past decade has resulted in various novel designs of column cells, Jameson and Centrifloat™ cells, air-sped hydrocylones, etc. All should require special frothers or blends of frothers to meet their specific needs.

Jan 1, 1994

By Paul D. Tomlingson

World class performance is the ultimate objective of many maintenance organizations. It marks the organization as a leader in its industry and sets it apart as the ultimate achiever. But what is a “world class” standard and how can it be achieved? Is there a yardstick by which an industrial organization can measure the relative performance of its maintenance activity and compare it with performance levels that universally identify “world class” status? Are there financial formulas, achievements, evaluation techniques or indices that provide this yardstick?

Jan 1, 2006

By William S. Butcher

Research and development of tunneling technology is rapidly taking its rightful place as an important ingredient in the Nation's research and development strategy. The state of technology in tunneling is very important to the Federal Government. Through its support, both direct and indirect, of a wide range of public works, our government, using the taxpayer's money, is the biggest buyer of tunnels. So that this money is spent wisely and efficiently, it is important that potential developments in tunneling technology that promise lower cost tunnels be pursued, if the cost of reaching the goals is commensurate with the prospective benefits. For too many years, the Federal Government's activities in the tunneling technology field were fragmented. Recently, specific coordination efforts have been initiated. It may surprise some to realize that the total Federal expenditure on excavation technology research and development, which is largely devoted to underground excavation, is growing by leaps and bounds. In fiscal year 1971 alone, approximately $19 million were expended by Federal agencies. This current fiscal year (FY 1972) that amount will increase to $24 million. It would appear that next year we will exceed the 1972 expenditure by 52 percent to bring the total FY 1973 expenditure up to $36 million. As most of this money is devoted to underground excavation, it is clear that the Federal Government

Jan 1, 1997

By Carl Pinches

Underground or surface mining is only the first stage in the ore mining process. Once the ore is mined, it is transported to the surface for further processing. Generally, this is done to extract the particular metal or other component of the ore that has commercial value in its purified form. In its raw state, there are typically between 4 and 7 g/t (0.12 and 0.2 oz/st) of valuable material from rock mined. Once on the surface, the ore is crushed and milled in order to obtain smaller rock particles and to expose the minerals that contain the desired metal or component. Mixing the milled ore with water, a process known as ?froth flotation,? can be employed. This technique consists of a series of tanks, or ?cells? through which the process liquid flows. To obtain the maximum recovery, the milling and flotation process will often be repeated a second time. An increase between 100 and 1,000 g/t (2.9 and 29 oz/st) of rock following this stage of the process is typical. Efficient recovery is key to maintaining a profitable mining operation. The measurement and control of the froth flotation process is vital.

Jan 1, 2010

By Douglas H. Bolton

In recent years, equipment manufacturers have been busy developing remote control systems to catch up with the sophistication and efficiency of continuous miners. Now the tables are turned, and manufacturers are undertaking the new challenge of upgrading, refining and equipping continuous miners to take full advantage of the capabilities made possible by modern, successful remote control systems. Because the operator can safely advance the miner farther without pulling out for roof bolting, continuous miners now need to be equipped with means of complying with correct face ventilation, dust suppression, methane detection, diffusion and improved lighting. Some of the exciting possibilities being developed to catch up with remote control include feedback controls using laser beams as datum points, coal sensing devices with feedback signals to show the operator what the machine is doing, show where it is relative to the coal seam, how hard it is working, and more sophisticated use of cyclic control. Mining machinery manufacturers have accepted the new challenges, and faster, safer mining procedures are already in sight.

Jan 1, 1975

Six pioneers of the American mining industry will be inducted into the National Mining Hall of Fame on Saturday, Sept. 13, at the Museum Convention Center in Leadville, CO. The 16th annual Mining Hall of Fame induction banquet will begin with a reception and open house at 5:30p.m., followed by the dinner and program at 7 p.m. The six inductees include James M. Gerstley, the only living member, and George O. Argall, Jr.; John F. “Leadville Johnny” Campion; Charles R. Nailler; Edwin N. Pennebaker and Russell L. Wood.

Jan 1, 2003

By Don W. Murphy, Don M. Larsen

Advanced process control has been implemented at the Jerritt Canyon Mill. Plant production prior to 1997 was limited by grind circuit capacity. The installation of additional mill horsepower and an optimizing supervisory control system achieved a throughput increase in excess of 12 percent. The controller application utilized a seamlessly integrated fuzzy logic expert system for real-time mill control coupled with a neural network predictor for closed-loop feedback of particle size constraints. In late 1998, a second supervisory controller was installed to operate the fluidized bed roasters. The second controller optimized roasting conditions, increased plant throughput and improved metallurgical recovery.

Jan 1, 2000