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By J. L. Ellenberger, P. W. Jeran

A deep longwall coal mine was instrumented with a three-dimensional microseismic system in order to help determine the exact strata mechanics associated with the rock failure, redistribution of stress and the associated gob formation from the longwall. Overall, 5,000 well calibrated seismic events were recorded during the mining of the panel. Analysis of these events showed a close correlation between the seismic activity and advance rate, and that the majority of the recorded seismic activity occurs in the immediate area of the advancing longwall face.

Jan 1, 2002

By Joao Felipe Costa, Jair Carlos Koppe, Alexandre Grigorieff

Discrepancies in raw materials properties informed by both producer or consumer is a common problem in most areas of the industry. Commercial contracts in the mineral industry normally penalises the producer, if contaminants in the ore exceed established limits. In some situations, the supplier is penalised if the quality of the ore is below a contracted amount. Differences in lab analysis are due many sources of error, such as distinct practices used in two laboratories for sampling, preparation or analysis. Rigid contracts impose to the miner the use of rigorous quality control program and in these situations sampling plays a major role. Sampling theory provides the tools to analyse errors involved in sampling, preparation and analysis. This paper proposes a methodology to check the precision and accuracy of a given sampling protocol emphasising the application of Gy's sampling theory to broken ore. A procedure to measure the error on each step of the protocol is introduced and the results compared to the fundamental error measured by Gy's theory. The results show the applicability of the method and its relevance to audit sampling procedures aiming at error minimisation. The methodology is illustrated in a case study at a major coal producer in Brazil.

Jan 1, 2002

By Philani Larrance Ngwenyama, Ronald CW Webber-Youngman

The survival chances of trapped miners in underground mines depend on how quickly they can be located and rescued post-accident. During entrapments, emergency rescue is highly desired but can be hindered by the lack of positioning information when a fit-for-purpose missing-person locator system is not available. Various types of missing-person locator systems are available to aid search-and-rescue operations. From the wide range of the available systems, selecting the most suitable one becomes the next challenge. The available systems have not been measured if they are fit-for-purpose or not, and to what situation. This study proposes user requirements that can be used as a guideline to facilitate the system selection process. These user requirements provide a framework for the design and development of a fit-for-purpose missing-person locator system. The user requirements can also be used for evaluating the performances of a particular system, predict its success, and also drive future research toward developing new technology to enhance the capabilities of the current systems.

Apr 1, 2024

By Vytas Svalbonas

Sophisticated computer analysis methods such as finite elements, finite differences, and numerical integration have become tools in the mineral processing industry for design of large mill shells. While use of such methods allows the analyst-designer to take new freedoms with his designed structure, there are also pitfalls and dangers which must be recognized for the proper use of such sophisticated tools. One of the worst of these is treating any computer answers as "gospel truth". The present paper discusses the knowledge required by the analyst-designer for proper use of computer analysis, as well as explaining to the layman how to identify questionable areas in such structural analyses.

Jan 1, 1979

By Ann M. Hagni

One of the most costly factors in the production of aluminum is the consumption of energy in the form of electricity. Energy consumption is increased as refractories in the Hall-Heroult reduction cells are corroded by penetration of the fluxes cryolite (Na3AlF6) and villiaumite (NaF). To decrease thermal conductivity and refractory waste, protective barrier linings are installed. Dry powder barrier linings form stable reaction products at cell operating temperatures. Four dry powders composed of vermiculite, corundum, wollastonite, and anorthite are characterized mineralogically by X-ray diffraction, reflected light microscopy, scanning electron microscopy, and cathodoluminescence microscopy in this research project.

Jan 1, 1998

By Saman Khaleghparast, Naj Aziz, Jan Nemcik, Guanyu Yang

"More than 25 years of uninterrupted research on ground support technology for underground mines has been undertaken at the University of Wollongong. This research has resulted in significant findings on tendon characteristics and strength properties. The paper focuses on the development of the fourth generation of cylindrically shaped shear test apparatus for assessing tendon performance in shear. This shear apparatus is known as the MK-IV Double Shear Box or Naj Aziz Double Shear Box (NADSB), and is based on the experience gained from the development of previous versions of rectangular double shear boxes. The new NADSB is circular in shape and is fitted with a truss system, which permits friction free shear testing of tendons across joint planes. A series of double shear tests were carried out on a number of cable bolts commonly used in Australian mines, both plain and indented wires, under varied pretension loads. The results were compared with similar test results using rectangular shaped double shear apparatus, with and without friction across joint faces. The significance of wire surface roughness and increased initial pretension loads are discussed and conclusions made, suggesting that indented wires are inferior in shear compared with plain cable bolts. The general test procedure of the NADSB is described and different concrete reinforcement techniques are reported. The influence of external and internal confinement of the concrete medium blocks in a circular double shear box contributed to consistent test results with a minimum of lateral and axial cracks occurring in the host medium.INTRODUCTIONThe use of long tendon ground support elements (cable bolts) is now a common practice in modern underground coal mines, hard rock mines, tunnels and other underground structures. Due to their material properties cable bolts contribute significantly to the overall ground reinforcement provided by a support system. Cable properties in tension and shear are in many cases vital to maintaining a safe and productive underground environment. Accordingly, tension and shear properties must be assessed accurately using both valid and reliable methods.Load transfer property testing of tendons has been studied over several decades with much of the early research focused on the pull and shear testing of solid rock bolts and hollow bolts (like Swellex and split set tube bolts), as these elements were used extensively at this time. It was not until the 1970’s that the use of cables for ground reinforcement developed, and as such highlighted the need to extend load transfer property testing to include shear strength of cable bolts. Initially, the discarded hoisting ropes were used for ground support in metal mines, particularly in stopping wall support and then late in 1980’s cable tendons began to use in coal mines."

Jan 1, 2019

By E. J. Garrison

Discussion by E.J. Garrison A.C. Noble presents a clear and concise summary of the factors pertinent to a competent reserve evaluation of a mineral occurrence. However, I believe that he confuses the difference between a resource and a reserve. By definition, a reserve estimate includes all known economic, legal, mining, metallurgical and environmental factors impacting the recovery of the product(s) found in the deposit. A resource estimate, however, is an estimate of what is there - what is available for exploitation and should not include economic and other considerations. Only after defining the resource, its extent, location, physical and chemical properties, can an intelligent selection process begin of the extraction and processing technologies most appropriate to the circumstances encountered. The early and almost certainly inappropriate application of these often cookbook choices has probably lead many companies to walk away from good properties. (How many mines have been found in others rejects?) An example of the process is the early selection of metallurgical samples, after encouraging values are found in a few holes or surface samples, in an attempt to determine the economics of the prospect. Unfortunately, the sampler does not know how representative of the occurrence the sample is because he does not know what the deposit looks like. As a consequence, the property becomes saddled with a bad metallurgical sample that is often inappropriately used in evaluating the deposit which it does not represent. Reply by A.C. Noble E.J. Garrison asserts that I confuse the difference between a resource and an ore reserve. In fact, this paper was motivated by the observation that resources and reserves are almost universally confused throughout the industry. While Garrison is concerned that too-early consideration of engineering, metallurgical and economic factors will result in dropping properties too soon, some issues that must be considered include: •The purpose of exploration is to discover ore reserves, not to discover resources. •Ore reserves are always smaller than resources. • Decisions on exploration expenditures must be made based on the expectation of the quantity of ore reserves that will ultimately be defined. Noble's Fig. 2 can be used to give guidance as to when it is appropriate to begin reserve calculations. When exploration enters the "flat" portion of the curve, representative samples can be selected for metallurgical studies and appropriate mining methods chosen. It is at this stage that we know enough about the deposit to make intelligent choices of representative samples and recognize constraints on mining caused by the deposits shape, environment and physical properties. Once the appropriate technologies have been chosen, then their cost can be estimated with reasonable accuracy. Early entry of economic and process factors gives the false appearance of reserve status to the resource estimation. It would be more informative and less subject to abuse and misunderstanding if resource calculations were made at a number of cutoff grades. The cutoff grades should be chosen to cover the range of grades found in practice in existing operations of similar type. This would emphasize the open nature of resource estimates and encourage creative evaluation of mining and process technologies. It does not preclude the use of economic, environmental and recovery technology factors in deciding the advisability of continuing exploration expenditures, but would highlight their speculative nature. It is thus hoped that decisions on the future of the deposit would not be made on the presumed suitability of a given technology but on the actually known reality. I agree that resource estimates should be reported as a range of cutoff grades. Since reporting at a cutoff implies application of underlying economics (even by analogy to similar properties), however, it should be clearly stated that resources do not consider economic, mining or cost factors, and that ore reserves will be substantially less. The dilemma of the explorationist is that until the continuity and limits of ore-grade mineralization have been established, it is difficult to make quantitative estimates of either resources or ore reserves. Further industry discussion is needed regarding standards for disclosing early exploration information in such a way as to fairly represent the potential of an exploration property.

Jan 1, 1995

By H. S. Rathor

In a major hydropower project in the Himalayas, during excavation of tunnel, hydrothermal gradient line appeared and caused extremely unfavorable conditions with rock and water temperature varying between 55°–66°C and nearly 100% humidity. Major changes in method of excavation, schedule of works, deployment of additional equipments and acclimatization of personnel were made to complete this unfavorable stretch of world’s longest Head Race Tunnel. The case study covers the various aspects of tunneling in geothermal rocks, inhuman working conditions, loss of production, cost overrun, contractual claims and strategy to manage such unfavorable working conditions.

Jan 1, 2003

By SK SAHOO, UK SINGH, SK SHARMA, GSP SINGH

Surface mining accounts for most coal production in Indian geo-mining conditions compared with underground methods, whose implementations are in deeper coal reserves and for lower stripping ratio in a congested operating space. The bord-and-pillar method is the preferred underground method in India for reasons of flexibility and investment cost. While previous researchers conducted field investigations on intact overburden conditions, this study focuses on the strata control issues in a bord-and-pillar depillaring working under the influence of the dead-load condition of voluminous and fragmented softcover of overburden dump material. The modeling results helped in ascertaining the criticality of strata behavior and rib-pillar stability in actual mining conditions when compared with the conventional intact overburden.

By Leonard Harris

Most of those involved in the mining industry are aware of the negative feelings that the well-informed citizens of this country, also known as the American public, have for the industry. As noted in an issue of Mining World News, “The general public perceives mining as dirty, noisy, destructive and belonging somewhere else.” The same theme was raised at a conference in Scotland in July 1991. It was noted there that mining has an unattractive public image around the world “as dirty, dangerous work that pollutes and degrades the environment.” Why is this? Why does mining have such a bad rap? I’m afraid that some of the blame rests with the mining industry itself - both in the past and in the present. Hopefully, we can do something about this in the future. And hopefully, the information here will help the reader to spread the word to offset the negative messages being issued almost daily by industry foes. I hope this will become more than just the words of another miner talking to miners and their friends. In the past, belching smokestacks and polluted streams and waterways were common sights. Today, the negative results of mining operations can also be seen in the form of waste dumps, leaked acid mine waste water and dust blowing from tailings piles. Some will argue that mining did nothing illegal in the past, and that all the regulations in force at that time were carried out to the letter. That may be so. The fact remains, however, that mining did these things, and the evidence is very clear in many parts of the country. It is visible to the well-informed citizens, in spite of the fact that many mine sites have been cleaned up and new technologies, such as flash smelting, dump leaching, pressure leaching and bioleaching, have greatly overcome many of the pollution problems. What is not so visible is the importance of the mining industry in our daily lives. Not long ago, knowledge about our non-renewable mineral resources ranked low on the list of qualifications for being a well-informed citizen. Events during the past two decades have changed this scenario. Politicians, writers, newscasters, economists and administrators, as well as the ‘public,’ are expressing opinions and forming judgments on oil company profits, desecration of landscapes, waste disposal sites and pollution by the extractive industries.

Jan 1, 1992

When most people think of coal mining, they envision men in soot-covered clothes and hard hats digging at deposits in deep underground caverns. These mental images commonly include coal cars rumbling on rails as they emerge from the earth, filled to the brim with rocky ore. The world of modern, longwall coal mining is a far different place. Yes, it?s underground, the miners still wear hard hats and the environment is filled with soot. However, today?s mining operations are carefully monitored and the entire process is highly automated. Five kilometers (3 miles) underground, a sophisticated, high-powered mining machine moves steadily through a 2-m (6-ft) high tunnel at an average speed of 3.2 km/h (2 mph), carving out coal, then conveying it to a crusher and carrying it to the surface. Instead of digging out the ore, a longwall mining system slices it from the exposed tunnel face, using giant rotating shears. The shorn coal tumbles onto a conveyer below the shears and is conveyed to the stageloader, where it is crushed and dumped onto the main conveyer belt that eventually hauls it out of the mine. Integral to the longwall shear and conveyor is a moving metal roof that protects it from the thousand plus feet of ground above. The ceiling panels automatically advance above the shears, powered by hydraulic roof supports that stand on the other side of the tunnel, moving in a slow, sideways lock-step with the shears. This complex and massive machine makes longwall mining the most ef?cient and productive method for excavating coal. In fact, it produces 2.7 kt to 22.6 kt (3,000 to 25,000 st) of ore per shift, versus 544 to 907 st (600 to 1,000 st) for the conventional room-and-pillar mining. Using that method, miners develop one section of a mine at a time after carving out load-bearing columns of coal to support the roof above their heads. Longwall mining also is considered safer than the room-and-pillar method, largely because the process is mostly automated, requiring fewer workers. Still, longwall mining has its drawbacks: The equipment is expensive and the mining conditions are harsh. An entire longwall system can cost between $50 million and $100 million, while the electrical controls used to operate it can cost an additional $1 million to $2 million. These investments grind away all day, every day, in hot tunnels filled with coal dust.

By W. S. Urbanski, A. L. Devernoe, M. S. Walker

Theory and practice are described for a new processing method capable of precise mineral separations based primarily on differences in particle specific gravities at specific gravity split points from 1.5 to 21.0 and beyond. Separations are analogous to those achieved using rotating heavy media, except that the effective specific gravity of the fluid is created magnetically using a relatively dilute, low-viscosity, water-based magnetic fluid. Results reported here for a large, laboratory flow-through separator include: 1) 99% grade with 97% recovery in single pass separation of a suite of heavy minerals from quartz at I0 kg/h, 14 tph/rm2 of duct cross section, 2) 90% grade and recovery in single-pass separation of mixtures of sand-size, non-magnetic rutile (4.23 specific gravity) and zircon (4.72 specific gravity) at throughputs of 35 kg/h, 47 tph/rm2 of duct cross section, 3) partition curves having Ep90-10 transition widths 5% or less of mineral specific gravities, and 4) essential confirmation of the theory.

Jan 1, 1991

By J. A. M. Cano

With a view toward increasing its product competitiveness in the foreign market, SAMARCO MINERACAO S/A has developed high MgO type pellets at its pilot plant for performing direct reduction simulation tests. Additives such as dolomitic lime and magnesite were used for increasing pellet MgO content. Comparative direct reduction simulation tests were conducted both in SAMARCO and foreign laboratories. The test results showed that it is possible to produce direct reduction type pellets with satisfactory metallurgical properties, which can be successfully processed at increased temperatures in direct reduction furnaces.

Jan 1, 1992

By Warren D. MacEvoy

INTRODUCTION Good ventilation bulkheads (stoppings) can be obtained only by conscientiously adhering to four basic principles: carefully selecting the site for the bulkhead, adequately preparing the site, properly constructing and sealing the bulkhead, and checking the results with a smoke tube before leaving the area. If all these guidelines are followed during each ventilation project, a poor job will result only from the use of improper materials and cannot be blamed on carelessness or oversight. SITE SELECTION A perfectly constructed bulkhead in the wrong location can be completely worthless. Conceivably, a bulk-head in the wrong location could cause dangerous ventilation conditions that are difficult to identify and isolate. If the suggestions herein are followed, a considerable amount of work, time, and material may be saved. Perhaps the single most important step is always to select the exact site for a bulkhead before starting construction. Although the latitude in selecting a site may be limited by instructions or operating conditions, it is common to find poor bulkheads built within a few meters (feet) of a site that would have been far superior but was overlooked during the planning process. The ideal site for a bulkhead should have as many of the following features and conditions as possible: 1) To provide a solid bulkhead, the selected site should be in firm and unbroken ground. 2) To minimize the amount of work and material required and to minimize the danger of later damage to the bulkhead, the site should have as small a cross section as possible. 3) The bulkhead site should not be encumbered by interferences such as pipes, wires, ditches, wire roof supports, trash, muck piles, etc. 4) The walls and timbers of the site should be free from oil, grease, or tar that would inhibit adhesion of the sealant used on the bulkhead. 5) Unless special precautions are taken, the site should not have water seepage, standing water on the floor, or water-carrying ditches. 6) To expedite construction of the bulkhead, the site should have reasonable access to transportation, supplies, communication facilities, and compressed-air lines. 7) The site should have a reasonably level floor, allowing direction of the bulkhead door swing to be reversed at a later time if so desired. In a steeply sloping location, it may be possible to open the door in one direction only. SITE PREPARATION Once a suitable site has been selected for the bulk¬head, it must be prepared properly. All site preparation work should be completed before starting any construction work on the stopping itself. Unfavorable site conditions can be identified during the course of thepreliminary site preparation, saving time, effort, and materials that otherwise might be wasted. The follow¬ing preparation steps help assure the construction of a good stopping: 1) If wire mesh has been used at the site, a strip 457 mm (18 in.) wide should be cut and removed from the walls and roof at the selected location. 2) The exposed strip of rock should be barred down thoroughly to provide a smooth surface. 3) All obstructing materials should be removed, including old timbers, pipes, rockbolts, wires, etc. If a conduit must cross the bulkhead area, it should be located or relocated away from the floor, walls, and roof to allow a 6.28-rad (360°) seal around the juncture between the conduit and the bulkhead structure. 4) All loose muck should be cleaned from the site and a trench about 152 mm (6 in.) deep should be dug from wall to wall in the floor. The trench must be wide enough to accommodate the entire bulkhead, including the posts. 5) The rock surfaces of the walls and roof should be cleaned with a wire brush to remove as much loose surface material as possible. Thorough cleaning promotes adhesion of the bulkhead sealant to the surfaces of the walls and roof, thus promoting an airtight seal. 6) It is quite difficult to seal landing mats that cross a bulkhead. If such a crossing cannot be avoided, the bulkhead should be placed between the end and the first hole in the steel so at least one side of the bulk-head can be sealed easily and completely. That may have to be done prior to actual construction if the end is located on the opposite face from the seal coating of the bulkhead. BULKHEAD CONSTRUCTION The three principal considerations in bulkhead con¬struction are the type of bulkhead, materials to be used, and construction method to be employed. For many projects, the bulkheads are specified by the requesting agency, with no latitude for independent choice of the type, materials, or construction method. In such cases, any deviations from the specifications, for any reason, must be approved in advance by the proper department or by the project senior ventilation engineer. Types and Materials When a choice of type, materials, or method is allowed, consideration should be given to factors such as cost, required useful life, proximity to blasting concus¬sions, availability of materials, direction of permissible air leakage, and degree of airtightness required. Other factors to be considered include the amount of time available, accessibility of transportation, potential for interference with operations or production, ambient water conditions, availability of connections to com¬pressed-air lines, etc. Despite the multitude of factors to be considered, most stoppings can be analyzed easily and the proper choices can be made without much difficulty. The four common classes of bulkheads utilized in

Jan 1, 1982

By J. Sidhom, W. Fourie

"As the mining industry continues to face difficult challenges the need to persistently focus on productivity and utilization of labor and equipment costs will intensify. With these challenges in mind, Komatsu is helping to bring mining performance and analytics to the next level.By evaluating underground haulage, a significant component of the room and pillar mining value stream, variables have been identified and sensitivities have been performed to show opportunities to balance and streamline throughput. As a result of applying operational excellence tools to the mining environment, Komatsu is seeking to optimize mining performances by limiting waste, simplifying the process, increasing productivity and machine utilization, as well as removing workers from harm’s way.These days it’s not enough to work harder; mines have to work smarter. Improving efficiency, reducing costs, increasing safety: these are no longer nice to haves, they are must haves.Starting with the best products and the right people is a first step, but then what? How do mines take their operations from average to being a top performer? By using operational excellence principles aimed at eliminating waste, simplifying processes, automating where possible and removing people from harm’s way.The fundamentals of operational excellence (OpEx) are based upon the process of define, measure, analyze, improve and control (DMAIC). DMAIC is an improvement cycle that helps with, for example, haulage optimization by: defining the issues and problems in the process as well as the areas of improvement; measuring and collecting mining operational data by time study and equipment monitoring system; analyzing through sensitivities and production modelling to determine root causes and then improving the performance and controlling the operation.Komatsu uses OpEx or lean principles inside its organization to drive efficiency, but it also helps its customers employ them to achieve new levels of productivity and safety.These same principles can be applied in most situations to streamline processes, improve operations and deliver value."

Jan 12, 2017

By Yang Ge, Yuzhu Pan, Mansheng Chu, Jue Tang, Cong Feng, Lihua Gao, Zhenggen Liu

Increasing attention is being paid to laterite nickel ore as an alternative to nickel sulfide ore to act as a feedstock for nickel metal production. While laterite nickel ore accounts for a lion’s share of global nickel resources at approximately 72 percent, it accounts for only 42 percent of the world’s nickel production. In addition, the processing of nickel sulfide ore is confronted with enormous challenges due to deeper drilling requirements, higher production costs and depleting reserves. The nickel content in the nickel laterite ore associated with hydrated iron oxides and silicate minerals limits the application of physical beneficiation methods for the removal of iron. Thus, magnetic reduction roasting followed by magnetic separation has been regarded as one of the attractive routes to concentrate and separate the valuable metals from the impurities. 

By Allen G. Taylor

High-value materials, such as gold, platinum and other precious metals, are subject to loss through unauthorized removal from mines, smelters, refiners and other places where such materials are processed. A study by Gastrow (2001) determined that between 1994 and 1998 an average of 603 kg/a (1,330 lb/year) of gold was stolen from South African mines and subsequently recovered. This does not include the gold that was stolen but not recovered. At 2011 prices, 603 kg/a (1,330 lb/year) of gold would be worth approximately $33 million. Mine security personnel believe that the unrecovered stolen gold far exceeds what is recovered (Gastrow 2001). Traditionally, metal detectors have been used to screen personnel leaving secure areas to discourage such unauthorized removal. However, with the current near-record prices of gold, platinum and other precious metals, it has become worthwhile for people exiting a facility to walk out with quantities of product that are too small for ordinary metal detectors to register, resulting in substantial financial losses.

Jan 1, 2012

By Louise H. Michaud

An interactive mine planning system that employs recent advances in 3D computer graphics capabilities and 3D geologic modelling to aid with the tasks involved in producing dragline mine plans was developed. As well as offering large potential saving in the time required to carry out the planning tasks, the system offers immediate visual feedback to the planning engineer. This can greatly aid in the conceptual understanding of complex geology and mine plans. The package incorporates the generation of a three dimensional Gridded Seam Model (GSM) as the basis for the development of the geologic database. This modelling method is capable of accurately representing rugged topography and multiple coal seams, including folding and faulting. The GSM is then integrated with an interactive graphics mine planning system in order to develop one model and one database for the generation of the mine design, the depletion of the coal resources and the movement of spoil material. The gridded structure of the model also provides the foundation on which all mine and spoil pile volumes are calculated.

Jan 1, 1992

By Peter Bryant

"The case for innovation in the mining industry has never been more compelling—whether you believe the industry is in a sharp dip in a significant ‘sawtooth’ cycle or in the midst of a bust — the imperative is the same. Despite record production levels and still above-average prices compared to the lows of 2000, the industry is struggling to make profits and provide the returns on capital that investors are seeking. This represents a large-scale destruction of value over the last 15 years.The last 10 years have seen a sustained rise of operation expenses and capital development costs while there has been a rapid decline in productivity. This trend is unsustainable especially against other key structural challenges and forces shaping the future of the industry:1. Despite short-term fluctuations, there is longterm sustained demand for commodities.• Demand is driven by relentless urbanization, population growth and a rapidly growing middle class.2. Environmental concerns continue to mount.• Existing mining methods and their environmental footprint are becoming increasingly unacceptable to society.3. Geopolitical pressures and community activism are growing.• An estimated $25 billion worth of projects are on hold due to community activism.• Increasing nationalism tendencies and government expropriations of close to $30 billion.• Social license to operate is being challenged.4. Finding, building, operating and closing a mine just keeps getting harder and more expensive.• Costs have been increasing at an annual rate of 10 to 15 percent for the last 10 years.• More assets are stranded as they become uneconomical to mine under current mining methods, e.g. Olympic Dam.• Ore grades continue to decline.• Declining productivity at an annual rate of more than 10 percent for the last 10 years.5. The industry has consistently underinvested in technology and innovation."

Jan 1, 2015

By J. J. Scott

Friction Rock Stabilizers, trade name Split Set*, is a new support system invented by the author and under development by Ingersoll-Rand and Lee-Norse Company. Split Sets are a substitute for standard bolts or fully grouted resin bolts and have certain advantages which are: 1. Improved safety for the miner 2. A rational design is possible based on rock mechanics principles 3. Supports can be made either to be yieldable or rigid 4. Supports can be used to build a roof beam or to suspend roof material 5. It is cheaper than the resin system and costs about the same as standard bolts.

Jan 1, 1974