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By Ke Yang

In Chinese coal mines, extraction of deep, highly gassy soft coal seams sandwiched between soft floor and soft roof in complicated geology is commonly encountered. How to safely and efficiently excavate such seams is a very significant and important problem. It has been a focused research area in recent years. By combining the characteristics of fully mechanized longwall mining methods such as large cutting height and mining along the dip, an integrated method and technologies for the Zhangji Coal Mine were developed. This technology includes the design of a complicated geological exploration system, optimization of mining method and working face parameters, control of rock pressure and high levels of gas, reliability model of the production system, and selection and compatibility of equipment. Engineering practice shows that the integrated technology was successful in mining these complicated seams. This study not only enriches the mining method, but also improves the coal mining practice, especially ensuring both safety and productivity under complicated geological conditions.

Jan 1, 2009

By Ramamritham Sridhar, Vaikuntam I. Lakshmanan, Dan A. Macki

Historically, introducing new technology to the mining industry has been problematic. In general, the industry is reluctant to take risks with new technology because it is already heavily tied to risk, even using existing technology. Risk in the orebody itself can be substantial. The company is dependent on drill hole patterns that are expected to define what is underground, and process test work is often based on drill cores and other samples, which occasionally produce surprises. And even well-proven processing techniques can blindside the producer, resulting in embarrassing and costly difficulties. But if the industry is to grow in knowledge and become more efficient, new ideas must be introduced. How to introduce new technology is the essence of this paper.

Jan 1, 2001

By W. Hennig

Efforts to define sustainability indicators are continuing in the mineral extracting industry and sector research institutions. Comprehensive ‘sets’ of economic, ecological and social sustainability indicators for the minerals industry are a necessary precondition for rationale-based negotiations with stakeholders from society. These tools alone, however, will not suffice in a delicately balanced economy-ecology -social well-being equilibrium with ever shifting valuation of different variables. Individual interests and emotions and also ideologically motivated positions of diverse stakeholders are gaining momentum. The minerals industry therefore has to develop beyond the rational pro-arguments for mining in the form of sustainability indicators also proactively its ‘soft skills’ to deal with expectations, fears and outright anti-mining bias, if it wants to retain the ‘social licence’ to continue.

Jan 1, 2005

By V. V. Ershov

Mining geometrical graphic documentation is employed on a large scale in designing and planning of mining operations at all the stages of exploitation. Mining geometrical modelling of mineral grade distribution presents an independent type of mathematical (graphic) modelling. The idea of functional relationship between geological indices being observed, and spicier coordinates is the basis of traditional mining geometrical modelling. Graphic presentation of three independent variables P =f (x,y,z) is confined to obtaining the series of two independent variables functions. Independent variables are presented as topographic surfaces corresponding to plane cross-sections of a deposit. During exploitation of certain parts of a deposit the most reliable geological information is obtained, characterizing regularities of ore distribution in the entrails. This information is, though, not taken into account in goemetrization of the new areas. In this connection dynamic modelling of deposits in the process of exploitation is necessary, i.e. geometrization of the deposits should be dynamic.

Jan 1, 1986

By R. L. Pozzo, A. S. Malicsi, I. Iwasaki

The electrochemical nature of mineral-grinding media interaction in the wet grinding of one and two sulfide mineral ores was investigated with regard to the flotation behaviors of the minerals. Two iron sulfides (pyrite and pyrrhorite) and mild steel were used to represent the sulfide minerals and the grinding media, respectively. Galvanic currents in two- and three-electrode combinations under abrasive and non abrasive conditions were correlated with the floatabilities of these minerals under corresponding conditions.

Jan 1, 1991

By Brian Flintoff

SCOTT COULTER: Our second speaker today is Brian Flintoff. Brian graduated from the University of Alberta in 1973 with a master's of science degree and worked as a project metallurgist at Brenda Mines until 1977. He returned to the University of Alberta in late 1977 to work on his Ph.D. and later joined the faculty of engineering in 1980, leaving in 1988 to rejoin Brenda in the newly formed process technology division. In 1998 he left Svedala-Brenda to take a position with Simons International's newly formed enterprise development services group. His topic today is "People: Reduce, Reuse, and Recycle." INTRODUCTION BRIAN FLINTOFF: Historically, the mining industry has relied on the people within a corporation to get things done. The culture of most companies was one of a slow but sure development of people, processes, equipment, and technology. Many of the larger companies supported in-house engineering and research organizations. However, the metal market pressures of the 1980s and the emergence of the global economy in the late '80s and early '90s put enormous financial pressures on the industry. As the old adage says, "necessity is the mother of invention," and the mining industry, like many others, has undergone a transformation. A cornerstone element of the transformation was the downsizing (or right-sizing) that was calculated to "trim the fat" from the capital and operating budgets. The goal was and is to find the highest sustainable operating profit.' While I'm sure one can find examples of losers (e.g., those who can be classified as suffering from corporate anorexia or institutional Alzheimer's) in such business reengineering efforts, there is little doubt that, on the whole, the transformation has been successful. The reality that now faces mill management is "How to do more with less?" At the risk of oversimplifying, one can look at this on two levels:

Jan 1, 1998

By J. W. Jang, J. J. Moore, I. Iwasaki

The wear behaviors of grinding media with different chemical composition and microstructures in wet grinding of a quartz-pyrrhotite mixture were investigated under various environments. The marked ball wear tests showed that the wear rate could be minimized by a suitable combination of martensite and ferrite within the same ball. A ball composed solely of hard martensite exhibited increased wear under an oxygen environment, while balls composed of both soft ferrite together with hard martensite exhibited decreased wear due presumably to the difference in their passivation behaviors. The galvanic interaction between the two phases as well as among these phases and an electroactive mineral were investigated through electrochemical measurements under abrasive condition in a slurry. The rates of formation of passive film controlled the corrosion currents of the high chromium steel media. Corrosive wear and its effect on flotation are discussed using the passivation kinetics model thereby developed.

Jan 1, 1990

By Craig J. Nelsen, David A. Smith

In 1987, LAC Minerals (USA), Inc. conducted a high resolution helicopter electromagnetic (EM) and magnetic geophysical survey on the Ortiz Mine Grant, New Mexico. The primary purpose of this survey was to assist in geologic mapping of a major structural zone, the Tijeras-Canoncito Fault System (TCFS). This structure is a very important ore- controlling feature in the area. Geophysical signatures over known deposits was a secondary goal of the survey, but direct detection of mineralization was not anticipated. The TCFS was revealed to be a complex, branching and anastomosing system of faults which locally form the bounding structures of a graben. The geophysical survey guided subsequent geologic mapping by redirecting field investigations, and geophysically redefining some features which previously had been only partly defined.

Jan 1, 1989

By A. S. Malicsi, M. D. Baker, I. Iwasaki

Fine grinding may he required for- some coals to remove sulfur and ash or to prepare coal-water slurry. Fine grinding leads to increased hall wear and its effect on the surface properties of the ground coal becomes of concern. Marked hall wear - tests were performed to study the effects of oxygen, pH, the soluble species of coal, and the addition of pyrrhotite on hall wear. The synergistic action of coal and oxygen greatly enhanced the corrosion of mild steel halls during grinding. Elec.trochemica1 measurements on a mild steel electrode in coal slurries and SEM observations of grinding hall surfaces were carried out to explore the corrosive wear mechanism.

Jan 1, 1991

By M. Sengupta, N. I. Johansen, A. K. Sinha

In Arctic surface mines, frozen ground adds to the complexity of slope stability analysis. The seasonal temperature change may thaw permafrost, and this thawed ground is often unstable. A computer program, GEODYNE, was used to simulate the movement of the thaw front in bare and insulated permafrost slopes. The simulation shows that the insulation can be used on mine slopes to prevent thawing.

Jan 1, 1990

By Weston Bourret

The need for wartime supplies of uranium for the Manhattan Project prompted a 1944 study of uranium in South Africa. Uraninite had been reported by R.A. Cooper in 1923 in a Witwatersrand heavy- mineral concentrate, and the search for uranium, therefore, included the district's 30 operating mills. The method of investigation was simple: take bulk concentrate samples from the Wifley tables and determine their mineralogy. Samples were taken on a daily basis, although weekly composites also were taken of some mills. In 1944, most mills had simple gravity circuits and produced (I) a gravity concentrate, and (2) an all-slime [-75 pm (-200 mesh)] product. The tonnage throughput was known, and from that, head assays could be calculated. Concentrate samples were sent to the United States for chemical analyses. A Geiger counter set up in a Johannesburg hotel room provided preliminary data. The early data showed uraninite to be widespread. Microscopic, mineragraphic, and siezing tests were all under- taken in Johannesburg. Ultimately, tests led to a high grade (+90%) uraninite concentrate. Platinum and other heavies were the impurities. In seven months, the investigations had reached the stage where it was possible to forecast an annual production of 5.4 to 7.3 kt (6,000 to 8,000 st) of U3O8. The estimate is still realistic. Additional details are found in Bourret (1981).

Jan 1, 1991

By P. Marcheselli, Jean-Yves Peron

A twin tube tunnel of 2 000 meters long and an internal diameter of 6.90 m has been excavated through alluvial ground, with low overburden, using a 8.0 m diameter Earth Pressure Balanced tunneling machine with foam injection and extruded concrete behind segment.

Jan 1, 1995

By Jr. McCulloch

Mining operations of Freeport Indonesia (FI) are located approximately 4 degrees -6' south latitude, 137 -7' east longitude in Irian Jaya the eastern most state of Indonesia (Figure I). The mines are located approximately 96 km (60 miles) from coast in the Carstenz Mountain range. The ore bodies are between 2900 and 4000 meters (9500 and 13 000 ft) elevation.

Jan 1, 1989

By Peter Mason, Chris Walker, Mike Costello

The Phase I electrowinning system at KCGM's Fimiston Operation utilised the well proven technology of electrowinning precious metal values onto steel wool followed by calcining and direct smelting to bullion. The above process, while reliable and successful, was to some extent labour intensive. The Williams Mine in Ontario, Canada had published conditions under which precious metal values are electrowon onto woven stainless steel and directly removed using high pressure sprays. The current paper describes the testwork which was carried out to check the applicability of the Williams criteria to KCGM eluates arising from the elution of highly loaded carbon from the calcine circuit and lowly loaded carbon from the float tails circuit. Information is also given on the commissioning and opera­tional experience which occurred.

Jan 1, 1996

By H. E. M. N. Moursy, M. N. Ahmad, C. R. Holland, G. M. Walker, R. D. Chandler

This work describes the effect of process parameters on the acidulation of Moroccan phosphate rock using nitric acid, i.e., the nitro-phosphate process. A series of bench scale experiments were conducted, using a stirred tank reactor (STR) system, to investigate the chemical reactions involved and optimum conditions for the formation of nitro-phosphate fertilizer. The effect of reaction time, temperature, mixing speed, acidulation ratio, and acid concentration were investigated, and were found to have an effect on the dissolution of P2O5 from the phosphate rock, using nitric acid. An increase in nitric acid concentration resulted in an increase in P2O5 dissolution, however, the dissolution was also found to be a function of acidulation ratio. A nitric acid phosphate rock ratio of 4:l ensured 90% dissolution for nitric acid concentration > 30%.

Jan 1, 2002

By J. J. Moore, I. Iwasaki, L. A. Lindeke

Correlation of scale-up from small-scale batch laboratory mills to large-diameter industrial mills was established by performing two series of laboratory and pilot plant grinding tests using a magnetic taconite ore and a siliceous sulfide ore. In one series, controlled batch grinding tests in 203-, 508-, and 914-mm (8-, 20-, and 36-in.) diameter mills were carried out followed by a second series involving continuous grinding tests using 305-mm (12-in.) and then 1067-mm (42-in.) diameter pilot plant ball mills in open circuits. The effects of ball diameter on wear and of mill diameter on grinding power and ball wear are illustrated.

Jan 1, 1988

By Sertaç Dündar, Bilgehan Kekeç, Arif Emre Dursun, Niyazi Bilim

"Estimation of rock drillability is vital for mining and boring operations. For this purpose, many researchers have developed various models and equations to estimate rock drillability. Most of these models aim to determine the drillability of rock and the penetration rate by using the physical and mechanical properties of rocks. Although drillability primarily depends on rock properties, other parameters have an impact on drillability as well. One of these parameters is the rotation speed of the bit. This study investigates the effect of rotation speed of the bit on drilling performance. Drilling tests were performed in the laboratory using rotary core drilling and a diamond drilling machine. The relationships between the physical rock properties and the penetration rate were investigated on 15 different rock types and four different rotation speeds were applied to determine the effect of rotation speed of bit on drilling. The uniaxial compressive strength, density, and P wave velocity show strong correlations with the penetration rate. In addition, if the values of the physical and mechanical properties of the rock increase, the effect of the rotation speed on the penetration rate decreases, i.e., increasing the rotation speed of the bit slightly affects drillability on hard and solid formations. 1. Introduction Drilling is one of the most essential operations in the mining industry, beginning from the exploration phase and continuing throughout all stages of production to the end of mine life (Taheri et al. 2016). In addition, drilling is widely using in the construction industry and other engineering operations. Various drillholes (blastholes, injection holes, borehole, diamond wire holes in natural stone mines, etc.), are needed during development and production activities in underground and open-pit mines as well as in dam, tunnel, road construction and sewage systems. For effective drilling operations, it is first necessary to gather information about the formation to be drilled. Drilling should then be performed after selecting appropriate drilling equipment and drilling parameters (thrust, pressure, rotational speed, flushing). Prediction of the drillability of rocks is vital for planning and performing the drilling process. Although, drilling is affected by several factors, the most important ones are related to the geological and mechanical properties of formation (Protodyakonov 1963, Paone et al 1969, Tandanand and Unger 1975, Pathinkar and Misra 1976, Rabia 1985, Perrin et al 1977). Determining the penetration rate is vital for planning a project and calculating the operation costs. The prediction of drilling affects the selection of drilling equipment, the efficiency of drilling equipment, project costs and the process of drilling operations."

Jan 1, 2017

By Vincent R. Bovino

Introduction Only a person fresh from an information vacuum could not know the status of this nation's economy. The inability of the US to compete in the world marketplace is manifested in many industries, from shoes to computer chips, from cars to copper. What industry will next fall prey to world competition? Perhaps the question should be, what insustry will next fall prey to declining productivity? American industry is being forced into an era where the focus must be on productivity, quality, cost control, and competition in the world marketplace. It is approaching a change that could rival the American Industrial Revolution. The future of the US is bright only if it can increase productivity by trying different and new ways to manage its businesses and people. Unlike the easy successes during the 60s and 70s, success in the decades ahead will depend on an ability to compete in the world market. Any operation can achieve unlimited productivity by developing the resources within its employees. As an industry, mining has harvested the earth's resources. As an industry in trouble, it now has to learn to tap human resources to release the energy and creativity in each person. Recently, I worked with a mining operation to reopen a mine and implement a different management approach. The extensive changes resulted in a 50% reduction in cash cost of producing silver (from $0.40 to $0.19/g or from $12.50 to $6 per oz). Thus, an unprofitable mine became an attractive business venture without technological changes or significant capital infusion. The operation is union-free, in spite of being in a highly unionized area. The mine implemented a real productivity improvement process called "gain-sharing." Employees now recognize their individual success is tied to the success of the business. They recognize the day of the free lunch is over for mining employees. This paper will explore three areas related to productivity: • some of the unspoken "whys" of the mining industry's paralysis and how management has caused unproductiveness in mining operations; • major components of a productivity improvement process; and • characteristics common to companies with successful productivity plans. Unspoken whys When things go wrong, everyone tends to point a finger at someone, anyone. This industry has blamed every conceivable person, corporate group, government agency, foreign government, and private group for its failures. The fault finger will not work anymore. Nobody is listening. It is a characteristic of winners in management to assume responsibility for less than acceptable performance. Excellent people tend to blame others less for problems. Everyone involved in mining should shoulder part of the blame for the industry's illness. Is the problem low prices or our high operating costs? To regain our status in the world marketplace and increase our productivity, we need to painfully and honestly talk about our mistakes.

Jan 3, 1986

By Robert A. Jankowski, J. Drew Potts

By implementing various mining practices, mine operators can reduce the respirable dust exposure levels of the roof bolter and the continuous miner operators. The Bureau of Mines has developed a computer program, entitled AMP (Alternative Mining Practices), that gives a quantitative comparison of these reductions. The alternative mining practices and their corresponding reductions in dust exposure levels that are evaluated by the program include a remote control continuous miner, a half-curtain ventilation system, two auxiliary fan-tubing bypass ventilation systems, a modified cutting sequence, a comparison between single-split and double-split ventilation networks, and a comparison between exhausting brattice and exhausting tubing. Descriptions of each of these mining practices are included in the report. The report also includes a hypothetical case study to show how AMP enables mine operators to select the technique(s) that is best suited to their particular needs. AMP is a compiled basic program that has been designed to run on computers with a DOS version 2.0 or later operating system. It includes high resolution graphics (640 X 200 dot positions) designed to run with video boards that are functionally compatible with the IBM Monochrome/ Printer Adapter. Graphic screens are selected from menus, and can be bypassed if the computer is not equipped to handle high resolution mode. Their primary function is to show proper implementation of the mining practices evaluated by the program. This package requires a minimum of 256K bytes of RAM. (Reference to specific products does not imply endorsement by the Bureau of Mines.)

Jan 1, 1987

By Dr. -Ing. Rainer Alles

Introduction Belt conveyors usually run in a straight line. The correct alignment is a major criterion for reliable functioning and optimum running properties. Any misalignment of the conveyor, especially mistracking of the belt, can have many negative effects. As a consequence of this, damage can occur on the belt and conveyor, some material can he thrown off at the edges and serious running problems can arise. In the worst case the belt can come off its supporting structure so that operations are brought to a halt. The absolutely straight alignment of a belt conveyor is actually impossible so that on closer observation every belt conveyor contains more or less sharp curves. Whereas on non-movable conveyors the deviations from the straight can he kept within the range of practical measuring accuracy by careful installation, movable conveyors in surface mining or belt systems in difficult terrain often contain curves that are easy to see with the naked eye. Below ground, too, alignment cannot always achieved to a desirable extent or is changed by geological faults over the years. Despite these unwanted curves, most belt conveyors perform their function reliably. In view of the belt tension, the belt tends to take the easiest path. This in general is the shortest distance between the pulleys on which the belt is tensioned and bent. This means for example that for a curve radius of 10,000 m over a flight of 100 m the greatest deviation from the ideal line is as much as 12 cm. And a figure of this magnitude cannot normally he accepted. In such cases, use is made of guide devices to properly train the belt if it doesn't center itself anyway. If it's possible to control the belt position over such unwanted curves. it can also he expected that the belt tends to follow the desired curved path within certain limits. I'd now like to cite a few examples to illustrate the ways and means of guiding a belt conveyor in curves. Cost-effectiveness The advantages of belt conveyors, in particular for longer conveying distances and mass flows have been known and undisputed for some time. However, there are often obstacles standing in the way of the concept of straight routing. If a belt conveyor is to bypass elevations or existing buildings or to follow the seam of underground deposits or a predetermined path, then substantially tighter radii and longer curves are desirable or necessary.

Jan 1, 1993