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By E. F. Klein, R. L. Eacret

Introduction In contrast to the general type of crushing mechanism in which the crushing surfaces alternately approach and withdraw from each other, described earlier in this section, and continuous-pressure break¬ers such as rolls and roller mills that will be described in a later chapter, impact crushers load by striking pieces of rock while in free fall and hurling them at high speed against stationary surfaces. Because the impact crusher depends for its effectiveness upon high velocity, wear is greater than in the slower-moving jaw and cone¬type wear parts, and for this reason its use is strictly limited to rela¬tively soft, friable, and sticky rocks that are characteristic of many nonmetallic mineral deposits. A few of these are phosphates, lime¬stone, barite, clay, asbestos rock, and coal. However, several examples of their use on soft lead-zinc and precious metal ores have been known. Although the use of impact crushers is expanding today into the range of ores containing as much as 15-18% silica, Taggart16 set the practical limit at 5%, and in the 1940s and 1950s several installa¬tions in the US and western Europe exceeded the limits of economical maintenance and were quickly superseded by the slower-moving, con¬ventional crushers. A rock that tends to be plastic or bouncy in a jaw or gyratory crusher when the force is applied slowly to reach ultimate strength, may become brittle with rapid loading and thus increase the effective¬ness of the applied forces. For this reason it is to be expected that as the quality of hammers, grates, plates, and cages improves with advances in steel technology, the use of high-speed crushers of this kind will increase. Terminology Modern usage differentiates between the impactor and the hammer mill, the former relying primarily on the impact of hammers (fixed or free-swinging) and secondarily upon pieces striking one another or steel surfaces; the hammer mill relies on both the centrifugal impact force of free-swinging hammers and the attrition and shear action between these hammers and well-placed grates suspended at the bot¬tom just below the hammer circle. The hammer mill, because of its grate discharge, restricts discharge of oversize rock to the grate open¬ing, while at the same time providing a trap for removal of tramp iron or other uncrushables. The impactor discharges free, so generally works with a screen to control product sizes. The question of terminology, impactor vs, hammer mill, creates difficulties because the similarities appear to outweigh the differences by far; if one were to list the similarities in order of importance and then the differences, he would be forced to conclude that they would best be dealt with as a single kind of crusher. Taggart16 gave it four names and added "as it is variously known," but it must be remembered that in 1945 the machine was nearly exclusively of the flailing-hammer type, while today the fixed-hammer rotor is also com¬mon. In this chapter the terms impactor and hammer mill will be used where they seem to apply. It is perhaps unfortunate that this terminology is being confused with rock breaking at the mine, usually with hand-held tools, e.g., the article "High-Energy Impact Rockbreaking" by Grantmyre and Hawkes, CIM Bulletin, August 1975. General Description Impact breakers, impact crushers, and hammer mills accomplish material breaking and reduction primarily through impact action of the material with fixed or free-swinging hammers revolving about a central rotor. The material to be crushed enters through an opening at the top or top side known as the "feed opening" or "hopper opening" and falls into the path of rotation (hammer circle) of the hammers. Initial breakage is accomplished in midair by collision of the dropping feed material with high-speed hammers. The second stage of breakage occurs when the pieces hit plates or breaker bars which line the crusher boxlike frame. Hammer mills rely further on a shearing and attrition action between free-swinging hammers and grid bars or grates at the crusher bottom which restrict discharge of oversize material until it is broken sufficiently to pass through the grid opening. The term hammer is used in reference to the piece which strikes the material, whether it is fixed on the rotor or free-swinging. It

Jan 1, 1985

By Douglas W. Barr

Water is a necessary part of our environment. It is a biological necessity, but more than that, it is a necessary part of our life style. Those of us who live in the north woods expect water to be part of the scene. There are few natives of this region who would be content to eliminate the streams, the lakes, the marshes, or our forests. Throughout the world, water has been so much a part of man's environment and man's adaptation to life has been so closely tied to water that our way of life and ways of accomplishing our work include water as an essential tool. The production of taconite is an example of our dependence on water. Other methods could have been developed to process taconite ore but the process methods chosen utilize water. Water is used for grinding and separation and for trans- porting the ore from one part of the process to another and for dust control. A typical large plant producing 10 million tons of taconite pellets per year will have on the order of 130,000 gallons per minute (8.202 m 3/51 of water in circulation in the plant. About 120,000 gal. per min. (7.571 m 31s) will pass to tailing thickeners where 110,000 gal. per min. (6.940 m 31s) is separated from tailing and returned to the process. About 15,000 gal. per min. (.9464 m 31s) goes with thickened tailing to tailing basin. My point is that there are great volumes of water in motion in a taconite plant,

Jan 1, 1980

By D. Bhattacharyya

The adsorption and desorption of gold cyanide by activated carbon is significantly influenced by particle size of the activated carbon particles and the chemical environment. A series of adsorption and elution experiments have been performed with ten different particle size fractions. The tests indicate that although the ultimate adsorption capacity is independent of the activated carbon particle size, the adsorption rate is strongly affected by the particle size. Further, desorption characteristics using traditional Mintek and atmospheric Zadra procedures reveal interesting trends with variation in particle size and will be discussed in this paper.

Feb 23, 2014

By Gerald V. Jergensen, Edward J. Samuel

Slurry system are the principal method for storage and transportation of solids within and between concentration operations In a mineral processing plant. A slurry 1s a mixture of solid particles In water, or a chemical solution, that behaves like a liquid. The design of slurry transportation systems is generally analagous to pumping and piping water, but with a few notable exceptions: • The interaction of particle on particle affects slurry transport. • Particles often interact with the fluid, particularly when chemicals have been added to the system. • Particles have a frustrating tendency to settle from the slurry suspension, especially into locations not considered In the design. • Solids have an affinity for wetted surf aces and tend to wear them away. Slurry transportation systems Include a number of separate components, each requiring special design considerations. A systematic evaluation of each component of a slurry transfer system will help overlooking the small details that could cause operational headaches. Most slurry transport systems include: • A receiving sump or tank that provides for mixing and/or momentary storage of slurry. • A driving force.. by a pump, atmospheric pressure or gravity. • A suitable conduit for transportation.. pipes or launders. • A delivery objective.. another sump or process vessel, or distribution system to several process points. • A control strategy and design to regulate the transfer operation. The design of the slurry transportation system normally evolves through the following steps: • Finalizing the process flowsheet and establishing the weights and volumes to be handled. • Identifying and characterizing the various process fluids and slurries. • Defining critical and minimum transport velocities of fluids. • Selecting a pipe diameter (or dimensions and gradient) and

Jan 1, 1986

By S. Bahrampour

One of the basic requirements for designing an optimized rock support for an underground opening is having reasonably enough geological information. It is often financially impractical to obtain detailed geological information about the rock surrounding the excavations. The geological and geotechnical information which are obtained during the construction phase are also usually inadequate and need periodic operation stoppage. Penn State University- J.H. Fletcher & Co. joint venture is to improve the existing instrumented roofbolter so that the 3D geological and geotechnical map of the rock mass surrounding the underground working can be generated real-time as the data is being collected. This information will also be used to design appropriate support for different sections of mines. In this paper, recent results in improving the performance of the measurement while drilling system will be discussed. Moreover, updates related to borehole probing methods for estimating the properties of the rock masses will be presented.

Feb 23, 2014

By J. T. Carlson

Dolomite is an objectionable impurity in phosphate ores, due to its MgO content. Even though dolomite and apatite liberate at a coarse size, the very similar densities of dolomite and apatite makes density separations difficult. However, if operated correctly, jigging can be a very efficient process. This has led to the development of a unique laboratory scale jig that allows for easy alteration of effective jigging properties. Key jigging parameters have been investigated for the separation of dolomite from phosphate ores. It was found that a pulsation rate of approximately 200 pulses/minute worked best for separating dolomite from apatite.

Jan 1, 2010

By Karl A. Smith, Roger T. Johnson, David W. Johnson

Conflicts are common in the mining industry. Engineers are accustomed to addressing issues such as land use, air and water pollution, and health and safety. Although conflicts of interest are important in the industry, they do not have the impact on organizational decision making that controversy does. Controversy is a type of conflict, probably the most important type, for effective decision making and competent problem solving. It exists when one person's ideas, information, preference, choices, conclusions, theories, opinions, or perspectives are incompatible with another's and the two seek to reach an agreement (Johnson and Johnson, 1979). Interpersonal and intergroup controversy is prevalent in the day-to-day functioning of organizations. If constructively managed, this type of controversy has important implications for effective decision making and problem solving. Too few organizational members accept controversy, and almost none attempt to stimulate it. This is because too few of them understand controversy well enough to accept and use it effectively. Most organizational personnel lack the interpersonal skills needed to stimulate controversy and manage it effectively. Discussion of conflicting ideas may not be common in problem solving situations due to the fear and anxiety most people feel in conflict situations. Traditionally, organizations suppressed conflict. They believed it was avoidable, caused by management errors. Optimal organizational performance required its removal. Conflict, though, is inevitable. And optimal organizational performance requires a moderate level of conflict. Management should manage the level of conflict and its resolution, for optimal performance. The current view stresses the importance of controversy for learning. Confronting a person with a different point of view stimulates that person to gather more information to elaborate, justify, or provide rationale for their position. Controversy: Process and Outcomes The decision making process begins with participants categorizing and organizing current information and experiences so that a conclusion is derived. When participants present their conclusions to another group and realize their conclusions are being challenged, a state of internal conceptual conflict or uncertainty ensues. This uncertainty motivates the challenged group to actively search for more information, experiences, and a more adequate cognitive perspective and reasoning process to resolve the uncertainty. Participants will adapt their cognitive perspective and reasoning through understanding the perspective and reasoning of others to derive a new or reorganized conclusion. This process may be repeated several times before a decision is reached. The active search for additional information on the alternatives is also promoted, along with greater mastery and retention of information and a more accurate understanding of opposing viewpoints (perspective taking). Of the many positive outcomes of the use of controversy, the effect on higher level cognitive reasoning and processing is especially important in engineering decision making. Research has been done on expert-novice difference in medical diagnoses, physics problem solving, and geological exploration. It shows that preparation for verbal interaction and the actual verbal interaction with peers with differing view-points promotes the development of expertise. Constructive Controversy Conditions Some controversies among decision makers concerning their preferred solutions to a problem can be beneficial. But sometimes they are not. As with all types of conflict, the potential for either constructive or destructive outcomes is present. Whether the consequences are positive or negative depends on the controversy and the way it is managed. The conditions and procedures of controversy management that determine the outcome include: the goal structure within which the controversy occurs; the degree of heterogeneity of decision makers; the amount of relevant information distributed among decision makers; the ability of decision makers to disagree with each other without creating defensiveness; and the perspectivetaking skills of the decision makers. Goal structure: Two possible contexts for controversy are cooperative and competitive. A

Jan 3, 1985

By Robert N. Morris

Ladies and Gentlemen: It is a distinct pleasure and honor to appear before you representing the railway industry as I do, but there is a much closer personal relationship. I am a graduate Mining Engineer and worked in the coal industry for 15 years prior to becoming a railroader only 4 ½ years ago. I have been a member of AIME most of my adult working life and am currently active in the Washington, D. C. Section. While having been in the railway industry only a short time, I have become involved during the recent period of innovation and development of the new railroad technique known as unit train service. I have had the privilege of helping to work out a number of unit train movements to both electric utility companies and to a major steel concern, handling coal from mines on the Southern Railway to the consuming plants. On Southern, our unit trains are all of what I shall describe as shuttle train operations whereas within the railroad industry today several types of service are characterized as unit train service and many don't offer comparable efficiencies.

Jan 1, 1968

By C. Flores, L. G. Twidwell, T. S. Jordan

It is well known that manguniferous silver ores containing manganese intimate) associated with silver are not amenable to conventional extraction methods. The segregation process has been applied primarily to the recovery of copper from oxidized and oxide-sulfide ores. A new alternative process, consisting of segregation roasting followed by flotation to recover the silver from refractory manganiferous silver ores, was studied using a 23-factorial experimental design. Laboratory investigations were conducted on a manganiferous silver ore analyzing 0.02% copper, 0.09% lead, 0.33% zinc, 12.55% manganese and 187 g/t silver. The investigation was designed to study the effects of the addition of salts, coke and copper (11) oxide on silver recovery. The results indicated that 79.3% of the silver can be recovered in the absence of copper oxide and 88.4% of the silver can be recovered with a copper oxide content of 1.5% at 750°C, 2% salt (NaCI). 1 % coke and 30 min of roasting. It was concluded that the addition of copper oxide improves silver recovery.

Jan 1, 1996

By Robin P. Gardner

The mechanistic or phenomenological approach to ball milling involving the, concepts of particulate selection and breakage functions with particle population balance models has been well established over the past decade (c.f., the review articles by Austin (1) Herbst and Mika, (2) and Snow (3)). Initial efforts to apply this approach concentrated on batch milling, but since most milling in industrial practice is continuous, much recent research has been directed to extending this approach to continuous milling. The primary difference between batch and continuous milling processes is the relative importance of material mixing and transport in the mill in the latter case. Much analytical (4-8) and some experimental (9-15) work on the effect of mill mixing and transport on milling has been recently reported. Much of the analytical work has naturally centered around extension of the well-developed concepts that have been applied to chemical reactors, (16-18) Fortunately, it has been found(1) that most milling processes are analogous to first-order chemical reactions so that the combined effects of material transport and reaction (breakage) can be handled by the relatively simple segregated flow concepts. (8)

Jan 1, 1973

By E. Ben-Awuah, H. Askari-Nasab, N. Al Habib

Open pit mines are getting deeper with time and transportation expenses are increasing because of the increasing haulage distance. In-pit crushing and conveying (IPCC) is getting popular in deeper open pit mines as a suitable alternative to truck haulage because it offers a lower operating cost due to shorter haulage distance and less truck requirement. Semi-mobile in-pit crusher, currently the most popular IPCC system, is relocated every two to five years and the short-term plan needs to be updated accordingly. Short-term planning with IPCC is an area of research that has not been explored extensively yet and hardly any model can generate short-term extraction sequence considering an IPCC in place. This research work proposes a mixed integer programming model to generate short-term production plan within a time horizon of 12 months. The objective of the model is to optimally allocate shovels to minimize cost of material handling and maximize revenue subject to meeting plant requirement, maximum allowable tonnage variation and IPCC location constraints to achieve production and NPV targets set by strategic plan. The proposed model has been implemented in a hypothetical case study for verification. The comparison of results between scenarios with and without IPCC is expected to justify the use of IPCC in large open pit mines from a short to medium term perspective. A semi-mobile IPCC system with one relocation is considered in the case study.

Feb 1, 2023

By Shiou-Chuan Sun

Notwithstanding the fact that unsaturated fatty acids are used in preference to saturated acids for most flotation purposes, information regarding their collecting properties is sketchy. Keck, Eggleston, and Lowry1 reported in 1939 that the collecting power of fatty acids on hematite decreased in the order of oleic, lauric, myristic, palmitic, and caprylic acid. Keck and Jasberg2 described in the same year that "unsaturated oleic acid with 18 carbon atoms was a better collector than saturated stearic acid" for floating magnetite. Gaudin and Cole3 stated in 1953 that the double bonds of oleic and linoleic acid were not oxidized during the flotation of fluorite, whereas the double bonds of linolenic acid were measurably altered even after one single flotation step. In August, 1953, Hukki and Vartiainen4 concluded that the collecting power of palmitic, oleic, linoleic, and linolenic acids on ilmenite, magnetite, pyrite, and rutile increased with an increasing number of double bonds in the acid molecules. This was subsequently proved to be generally true for the flotation of mapganese5, phosphate6, and magnetite7. The above cited literature indicates that, prior to the present paper, only about ten minerals were tested with pure unsaturated fatty acids as collectors.

Jan 1, 1959

By J. M. Wempen, M. K. McCarter

"Differential Interferometric Synthetic Aperture Radar (DInSAR) is a satellite-based remote sensing technique capable of measuring centimeter-level surface displacement with high spatial resolution over large areas. Regular monitoring of subsidence due to underground mine development is one potential application of DInSAR, and in this study, the application of DInSAR for subsidence monitoring is evaluated for two mining regions in the mountain west of the United States. In general, DInSAR has potential to identify the shape and extent of subsidence; in some cases, magnitudes and rates of subsidence can be defined. Importantly, the effectiveness of DInSAR for subsidence monitoring depends on the radar band (wavelength), the subsidence rate and the time between image acquisitions, and the topographic and vegetative surface characteristics. INTRODUCTION Differential Interferometric Synthetic Aperture Radar (DInSAR) is a satellite-based remote technique that can be used to measure small surface displacements. Under good conditions, centimeter-level displacements can be measured with subcentimeter accuracy (Buckley, 2000; Massonnet and Feigl, 1998). Additionally, DInSAR data have relatively high spatial and temporal resolutions. Pixels in Synthetic Aperture Radar (SAR) images can have a ground resolution as small as about 3 m, and images often include tens to hundreds of thousands of pixels and cover tens of kilometers. Regions are imaged regularly, and periods between images typically range from weeks to months. In DInSAR, phase measurements from two radar images acquired over the same region at different times are used to precisely measure relative distances (Rosen, 2014). Surface deformation, topography, and changes in the satellite position all contribute to differences in the length of the path that the radar wave travels in each image. SAR sensors use radar with relatively long wavelengths; L-band (24 cm wavelength), C-band (6 cm wavelength), and X-band (3 cm wavelength) radar are used most commonly. Because the wavelengths are long, small changes in the path length of the radar signal can be quantified by measuring the change in the phase of the radar signal between the images. In general, changes in the path length due to changes in the satellite position and topography are known or can be estimated, and centimeter-level changes in the path length due to deformation are measurable. This study evaluates the effectiveness of DInSAR for measuring subsidence in two mining regions in the mountain west of the United States. L-band data from the Advanced Land Observing Satellite (ALOS) and X-band data from the TerraSAR-X mission are evaluated. Imaging characteristics, including the radar band and the time between image acquisitions, are important for effective subsidence monitoring."

Jan 1, 2017

By A. Arik

Reliable ore reserve estimates for deposits with highly skewed grade disributions are difficult tasks to perform. Although some recent geostatistical techniques are available to handle problems with these estimations, ordinary kriging or conventional interpolation methods are still widely used to estimate the ore reserves for such deposits. The estimation results can be very sensitive to the search parameters used during the interpolation of grades with these methods. This paper compares the ore reserve estimates from ordinary kriging using several cases in which certain search parameters are varied. The comparisons are extended to different mineralizations to show the changing effects of these parameters.

Jan 1, 1990

By G. B. Amicucci

A Denver Autometrics Particle Size Monitor, PSM-400, was installed at Golden Sunlight Mines, Inc. in October 1988. The PSM-400 measures the grind product's particle size and percent solids. The particle size is used to control grind size by automatically adjusting mill feed rate. The PSM's continuous response to ore changes has improved grind product uniformity and mill throughput. Metallurgical testing has shown the PSM's accuracy to be +/-1 % + 150 µm (100 mesh).

Jan 1, 1991

By Cesar A. Busnardo

The carbonatite orebody in Jacupiranga is situated some 230km (140-mi) southwest of Sao Paulo and is mined by Serrana S/A de Mineragao, producing an apatite concentrate for fertilizer production and a calcite tailing for cement manufacture (see Figure 1). The orebody (Table 1) is mined by open pit and the total production is 4.5 million mt/year of carbonatite ore with a further 2.2 million mt/year of overburden. The carbonatite low-grade ore (Table 2) is fed to the concentration plant at 460 mt/h , comprising of four parallel lines of grinding, by rod mills 2.7m x 4.5m (9 x 15-ft), operating in closed circuit with hydrocyclones. The grinding circuit product is deslimed in four stages using hydrocyclones and the deslimed product is conditioned with corn starch and subsequently floated, using fatty acids as collector to, recover the apatite.

Jan 1, 1985

By Y. Guo, C. Cao

"China is rich in tungsten resource, but they are mainly associated minerals. The similar flotability of scheelite, fluorite, and calcite resulted in the difficult separation by flotation. This work summarized the current situation and the development of flotation reagents, technological process, and mineral processing equipments in China. Fatty acid served as the collector and water glass was the depressant to expand the flotability differences in traditional flotation technology. However the water glass inevitably influenced the flotation of tungsten minerals to a large extend, and the suppressed fluorite was difficult to recover by flotation. Abundant water glass lead to the bad settleability of the tailings and the tail water was difficult to circulate, resulted in serious environmental problems. Recent study proved that the selectivity of benzene armour hydroxyl oxime acid (BAHA) salts was adequate for the separation of tungsten minerals from fluorite, calcite and most silicate minerals without any depressant. By this way, sodium silicate was canceled completely in tungsten flotation, greatly improving the recovery of tungsten and the environmental problems caused by tail water treatment would be solved fundamentally. TUNGSTEN RESOURCES AND DISTRIBUTION IN CHINA China is rich in tungsten resources and the proved reserves accounted for 60% of the world's reserves [1]. However the wolframite has been dried up and the scheelite resources had become the main resource of the tungsten metal. Table 1 showed the most large and superlarge scheelite deposits in China. China has more than 40 large and superlarge scheelite deposits and the total metallic deserves is more than 3 million ton [2]. But most of the deposits were low-grade and the associated relationship was complicated. For example, scheelite was usually associated with wolframite, molybonite, bismuthinite, pyrite, fluorite, and calcite in Shizhuyuan and Yaogangxian mine."

Jan 1, 2016

By J. Kretschmann

Southeast Asian countries cannot maintain their economic growth rate without the development of their mining industries. To make this development as sustainable as possible requires sound fundamentals securing not only economic progress and environment protection but also improvements in occupational safety and health (OSH) for the miners. Mining in South East Asia is still very labor intense and dangerous. Tremendous achievements from world class mining operations in advanced mining countries can be used as role models to improve the status quo of the Southeast Asian countries in OSH management. Know-how transfer, therefore, is a key factor for major improvements. Effects of this transfer based on a multi-level approach will be discussed based on a case study. It describes the transfer from German to Vietnamese hard coal mining industry. Crucial requisites for excellent achievements in OSH in Southeast Asian mining countries are also mentioned.

Feb 23, 2014

By Andrew Trusiak

Brunswick Mining, employing approximately 1600 employees, is located 40 km south of the city of Bathurst in north eastern New Brunswick. The mine has operated as two lead-zinc operations - the underground mine(No.12) and the open pit mine (No.6). The open pit orebody is presently being' mined by underground methods. It is expected that the No.12 mine will furnish the entire ore supply by the end of 1981. The flotation practice prior to 1971 has been described by Neumann and Schnarr(1) and by Erskine (2). More recently, the current flotation practice has been described by McTavish(3) and deals with some major circuit modifications between 1972 and 1978. The period 1978 to 1980 has seen the completion of. a major flotation cell replacement and expansion program for the No.6 concentrator, and the implementation of computer control in the No. 12 CuPb and Zn flotation circuits.

Jan 1, 1981

By M. A. Bartkoski

Today?s surviving companies are being pushed to a heightened level of excellence due to market changes. Therefore, new business strategies must be explored. This paper offers a sequenced plan to retool, empower, and organize the entire team for a common goal. Integrity Process is an operating system that is very comprehensive and is integrated in every part of the business. It relies on a detailed prevention concept intertwined with accountability that produces individual efficiencies and team effectiveness. Integrity Process focuses on the importance between working from commitment motives versus compliance fears. The results are balanced in priority and truly yield a win-win for the owners, management, workforce, and the community. Integrity Process can and is being used in any industry that is challenged to optimize the relationship between people and process.

Feb 23, 2014