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By B. C. Flintoff

In general, process control systems in solid-solid separation have not evolved to the same level as in flotation circuit control. Perhaps one of the more significant contributing factors in this regard is the lack of suitable on-line analytical instrumentation. In spite of the obstacles, some interesting work has been done. This paper presents a review of current industrial control strategies in ore sorting, dense media separation, gravity separation and electrical and magnetic separation.

Jan 1, 1986

By M. W. Ryan

The US Bureau of Mines investigated cold-cutting alternatives to oxyacetylene torch cutting of metal. The alternatives examined were a pneumatic circular saw with an abrasive cutting wheel, a handheld abrasive water-jet cutting tool, an ultrathermic-cutting system, hydraulic punches and cutters, and a pneumatic reciprocating hacksaw. Sparks generated with the pneumatic circular saw or ultrathermic-cutting system were not completely eliminated with the use of water sprays. The water sprays also reduced the cutting rate of the pneumatic circular saw by 70%. The safety and performance of a handheld abrasive water jet cutting system requires additional research. The hydraulic cutters and punches are readily available and do not introduce any hazards. However, they are not comparable in price to the oxyacetylene gas torch and many different attachments would be needed to replace the torch. The pneumatic reciprocating hacksaw, which did not produce any sparks, is an acceptable alternative in terms of cutting rates. However, the price of the saw and blades is not comparable to that of the oxyacetylene gas torch. The results of this study will further the advancement of safe, efficient alternatives to oxyacetylene gas torches, which will improve miner safety.

Jan 1, 1996

By Kiseong Hyeong

Geochemical characteristics, shapes and surface textures of manganese nodules from two blocks located in the southern (9°N~11°N) (KR5) and northern parts (16°N~17°N) (KR2) of the Clarion-Clipperton fracture zone between 130°W and 133°W were investigated in terms of sediment distribution and metal contents for better understanding of controlling factors of seabed manganese nodule genesis. Two blocks, ~700 km away, are dominated by the nodules with different origins, each of which has distinctive chemical compositions and shapes. KR2 block is dominated by irregular and poly-type nodules of hydrogenetic origin with low Mn/Fe, Cu, and Ni contents and high Fe and Co contents, while KR5 block is dominated by discoidal and ellipsoidal nodules of diagenetic origin with high Mn/Fe, Cu, and Ni contents and low Fe and Co contents. In addition, nodules from two blocks show different surface textures: smooth and transitional in KR2 and dimorphic and rough in KR5. Sediment distribution is also distinctly different in two blocks. The study area consists of three sediment types: Unit 1 ? dark brown mud with an intermediate metal content, Unit 2 - yellowish brown mud with poor metal content, and Unit 3 ? black metalliferous mud. KR2 is characterized by the thick occurrences (<250 cm) of Unit 1 at the surface while Unit 1 distributes thin (<12 cm) in KR5. Higher primary production rate in the southern block proximal to equator and resulting high supply rate of metals to the sediment might be the cause for the dominance of diagenetic nodules in the southern block, but potential controls of different sediment distribution on the nodule genesis can not be excluded. If it is the case, Unit 1 with an intermediate metal content likely has been acting as a sink for metals by precipitating micro-nodules within the sediment column. Within the KR5, the hydrogenetic nodules occur preferentially on the seabed where Unit 3 distributes at shallower depth (<50 cm). Unit 3 has 2 or 3 times higher metal contents than other types of sediments. It might play the same role as Unit 1 in the northern block that prevents the supply of metals to the sediment surface. It also supports the potential effect of sediment distribution on nodule genesis. Keywords: Nodules genesis, Sediment distribution, Supply rate of metals

Jan 1, 2008

By S. K. Nicol

The results of column flotation tests conducted on a bulk sample of ultrafines discarded from the fine coal desliming cyclones at the Riverside coal preparation plant of Theiss Dampier Mitsui Coal Limited are presented. A 9% ash concentrate was obtained from a 51% ash ultrafine feed at 75-80% recovery of combustibles in a single stage of column flotation. From this result it is predicted that installation of column flotation at Riverside would lead to the annual recovery of additional coal worth $US5.1M. The operating conditions for coal and copper column flotation are compared and some differences which may result in a variation in column design are noted.

Jan 1, 1987

By M. J. Gula, S. S. Xue, E. P. Horwitz

A study was conducted to remove iron from sulfate solu¬tions using Eichrom&apos;sDipex®extractant, PP&apos;-di(2-ethylhexyl) methanediphosphonic acid (H2DEH[MDP]). It was 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 106. More than 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, 2000

By William H. McLemore

Geologists searching for carbonate rocks suitable for chemical uses traditionally have relied on extensive laboratory testing in order to locate strata or zones that might be suitable for mining. However, when considering the significant time and costs involved in sampling and performing chemical analyses, any exploration technique whereby fewer samples and analyses are needed would be of great value. In other words, if the exploration geologist could "zero-in" on select areas, considerable time and money could be saved. In general, the major-element chemistry of carbonate rocks is determined by the abundance of the minerals present. CaO occurs with CO2 as the mineral calcite, which is the primary mineral comprising allochems, matrix and sparry cement; MgO is found in high-magnesium calcite (many calcite fossil species contain appreciable amounts of MgO in solid solution), dolomite, and chlorite; iron occurs in pyrite and in limonitic stylolites, as well as in chloritic and glauconitic clay minerals; materials containing abundant Si02 are microcrystalline quartz (chest) silt-sized quartz, and clay minerals; and Al203 is found primarily in illitic, kaolinitic, and chloritic clay minerals. The presence or absence of these minerals determines the chemical composition of the carbonate rooks.

Jan 1, 1983

By G. Norman Owen, Roger E. Scholl, Tor L. Brekke

INTRODUCTION Underground structures are generally regarded to be safer than surface structures during strong seismic motion, except when crossing a causative fault. Recent studies of observed earthquake damage to tunnels generally support this view, although instances of severe damage and, occasionally, collapse are reported. For proposed underground construction of sensitive structures such as nuclear power plants, liquefied natural gas facilities, and nuclear waste repositories, a verification of the seismic response of underground structures will be required.. This paper discusses the stabilization recommendations used in a study of additional costs required to protect tunnels against ground motion caused by earthquakes and underground nuclear explosions (1). The study is a part of the site investigations for possible construction of a nuclear waste repository. The additional costs estimated in the study are not presented here; only the stabilization measures are presented in the present paper. The tunnels, which would constitute the underground facilities of a possible repository, are assumed to be 5.5 m (18 ft) in diameter and to be located at a depth of 600 m (2,000 ft). Three candidate geological materials are considered: argillite (shale), granite, and tuff. Several peak ground accelerations are used: 0.3g, 0.5g, and 0.7g for earthquakes, and 0.5g, 0.7g, and 1.0g for underground nuclear explosions. Potential damage due only to shaking is considered here. This paper does not discuss problems that result from creep or sudden rupture of intersected faults or from ground failures at portals.

Jan 1, 1979

By E. Topuz

Productivity is the most important determinant in the economics of underground coal mining operations. Lower labor productivity increases labor requirements per ton. This, in turn, increases the unit cost of production. Intensive labor requirements may also affect miner injuries and fatalities by increasing man-hours of exposure necessary to produce a given amount of coal.

Jan 1, 1988

By J. M. Keane

Critical to successful dump and heap leaching for copper is an adequate testing program for evaluation of the applicable parameters. This paper deals with testing methods to establish best conditions for dump and heap leaching of copper so that commercial operations can proceed on a rational basis. Discussion is also offered of ore occurrences suitable for dump and heap leaching.

Jan 1, 1985

By E. R. Pantos

US coal production increased 3% to a record 832 Mt (917 million st) in 1987, according to preliminary Energy Information Administration (EIA) data. Most of the increase was due to the unusually warm summer and the increased coal-fired electricity demand for air conditioning. Drought conditions in the Northwest lowered hydroelectric generation, contributing to the higher use of coal by electric utilities. However, excess production capacity and increased competition from natural gas added further downward pressure on delivered coal prices, continuing the declining price trend of the last several years. Coal production by region Appalachian coal production reached 402 Mt (443 million st) in 1987. This is about 3% more than in 1986 and just short of its 1984 peak. Virginia produced 7% more than its 1986 level, due to increased coal-based electricity demand. Smaller percentage increases were attained in eastern Kentucky, Pennsylvania, and West Virginia. Ohio and Alabama were the only major coal-producing states in Appalachia that produced less coal in 1987 than in the previous year. In the Interior region, 1987 coal production reached a record 182 Mt (201 million st), about 2% above 1986. Illinois is the largest coal-producing state in that region. Production there fell about 3.7%, primarily because of lowered demand at electric utility plants in Alabama and Tennessee. However, this was more than offset by production increases in western Kentucky, Texas, and Indiana. After falling slightly in 1986, coal production in the West resumed its upward trend to a record 248 Mt (273 million st). Wyoming is that region&apos;s dominant coal producer. It mined 7% more coal than in 1986. Wyoming&apos;s increase offset the 11% decline in New Mexico production and smaller declines in other Western states. Coal consumption and prices Domestic coal consumption reached a record 759 Mt (837 million st) in 1987. Most of the increase resulted from the unusually warm summer that led to higher than normal peak demands for electricity in the third quarter. Electric utility coal consumption was also boosted by the below-normal hydroelectric generation that resulted from low water levels in the Northwest. These factors more than offset the effects of increased nuclear power generation and competition from natural gas. As a result, coal provided 56.9% of electric utility generation in 1987, compared with 55.7% in 1986. Electric utilities consumed a record 651 Mt (718 million st) of coal. While electric utility coal consumption increased, the average cost of coal to utilities was down, from $1.58 per million Btu in 1986 to $1.52 in 1987. The average price of coal delivered to utilities in 1987 was $35.09/t ($31.84 per st), the lowest since 1981. Coal prices were held down by a glut of coal supplies and by a decline in the average price of natural gas to electric utilities. Coal consumption at coke plants in 1987 was 2.6% above the 1986&apos;s 32.5 Mt (36 million st). This increase reflects steel&apos;s recent resurgence. Coking coal demand, though, was reduced by the increased use of continuous casting and electric furnace technologies. The average price of coal delivered to coke plants fell from $56.02 to $51.35/t ($50.83 to $46.59 per st). Coal consumption in the industries other than coke plants amounted to 68.2 Mt (75.2 million st) in 1987, slightly less than in 1986. Coal lost part of its market share to natural gas, which was priced favorably relative to coal. The average price of coal delivered to manufacturing plants was at its lowest level of the current decade. It fell from $39.50/t in 1986 to $37.27/t ($35.84 to $33.81 per st). Residential and commercial coal consumption fell to 6.2 Mt (6.9 million st) that is 9.8% below 1986 and the lowest since 1980. This decline is also attributed to the relatively low price of natural gas in 1987. Coal stocks Coal consumers held 169 Mt (186 million st) of coal stocks at the end of 1987, 5.9% above the 1986 year-end level. Most of this increase was due to stockpiling by electric utilities in anticipation of a possible strike by the United Mine Workers of America early in 1988. Stocks at electric utilities increased to an estimated 154 Mt (171 million st) at the end of 1987, 5.6% higher than the previous year. This was much lower than 1984&apos;s stock buildup. Coke plants increased their coal stocks by 30% in 1987 to 3.5 Mt (3.9 million st), rebounding from the unusually low inventories of 1985 and 1986. Other industries increased their stocks slightly in 1987. Coal producers and distributors ended 1987 with 25 Mt (28 million

Jan 5, 1988

By Wolfgang Pietsch

Roller presses were first invented in the middle of the 19th century, for the economical size enlargement of coal fines as fuels. Coal briquettes became quickly accepted for industrial and domestic use giving rise to a large and sucessful industry, particularly in Europe, Japan, and North America. When, towards the middle of the 20th century, coal was more and more replaced by other energy sources, such as electricity, gas, and oil, roller press manufacturers searched for alternate applications of this equipment. In addition to contemporary coal briquetting, in fields such as smokeless fuel and form-coke, it was found that redesigned and modernized roller presses, which are now capable of exerting high forces, are versatile machines for many tasks in mineral processing. Today they are used for: - the "classic" pressure agglomeration and - the "new" high pressure comminution. In pressure agglomeration, the characteristics of fine minerals are improved by forming briquettes or granulated products from compacts. During size enlargement with roller presses briquettes are directly obtained while granular materials are produced by crushing and sizing of compacted sheets. The processes are carried-out essentially dry and often do not require binders other than those inherently contained in the feed and "activated" by the high forces and/or elevated feed temperatures (e.g. hot briquetting). Therefore, no foreign materials (impurities) are added. Another advantage of the technology is, that wide particle size distributions are acceptable or desirable as feed materials, including millimeter or even centimeter sized particles. Plastic particles deform and brittle materials are crushed during pressure agglomeration. A relatively new application of roller presses in mineral processing is the utilization of the crushing effect when brittle materials pass the nip area between the rollers. It was found that this crushing mechanism is very efficient thus saving energy, particularly in grinding circuits handling large capacities. The paper introduces the fundamentals of the process and describes the design as well as applications of modern roller presses in mineral processing.

Jan 1, 1995

By Zhongxue Li, Wenguang Li, Yiqing Zhao, Shuaiqi Wang

"Faced with the serious managerial situations and diverse conditions and needs for mine safety, occupational health and environmental stewardship in Chinese mining communities, an evidence-based approach is proposed for the management of mine safety, health and environment integrity. By the proposed approach, tangible and effective scientific evidence should be collected and accumulated, and the authenticity, accuracy and applicability of the evidence should be assessed to form an evidence-based approach for characterizing mine safety, health and environmental hazards and risks from multidimensional perspectives. The results are then used to formulate diverse safety, health and environment functional requirements. In an evidence-based approach, the evidence is combined with the professional experiences and the actual economic and technological situations, availability and affordability of a mine. This approach is helpful to establish scientific, reasonable, acceptable and effective solutions for identifying and mitigating hazards and improving the level of mine safety, health and environment integrity of mining operations.Introduction / Background In recent years, economic reforms have opened China's economy so that Chinese society has rapidly modernized. Along with this advancement, the exploitation and utilization of mineral resources continues to be active and the scale of mining production continues to increase, which has created a deterioration in resource reserves and as well as the general condition of mining technology. There are many hazards and safety problems in mine production and occupational health as well as in the community environment in China’s mining industry. These problems threaten the security of China's mines and present serious obstacles and challenges to the industry and the government. According to the statistics from the State Administration of Work Safety Supervision, there were 50,500 mine safety incidents in China between 2001 and 2013, which consisted of 31,439 coal mine safety accidents and 19,061 non-coal mine safety accidents, resulting in 30 deaths (Qin 2014). At the same time, mineral dust and radioactive material from mine production processes have increased the morbidity rate of silicosis and cancer in mining workers."

Jan 1, 2017

By Bruce Kennedy, Dan Nilsson

Mining means drilling and blasting in order to break down the rock, loading and transport, and often also crushing the ore down to a suitable size. These operations can be done in open pits or in underground mines, and also, to a lesser extent, in marine mining. The same operations are also used in various types of construction, i.e., for roads, water power stations, etc. Before beginning a detailed economic analysis of the factors which enter into deciding whether to mine by open-pit or underground mining, and at what point a change should be made from open-pit to underground mining, or vice versa, it is of interest to consider some general factors.

Jan 1, 1982

Geopolymerization is a process by which Al-Si minerals undergo dissolution and polymerization in an alkaline solution to form a monolithic material with a high mechanical strength (Davidovits, 1991, 1994). In this study, the factors affecting the geopolymerization of Na feldspar (albite) and K -feldspar (microcline) were investigated. It was found that both Na feldspar and K -feldspar are reactive in geopolymerization with the resultant geopolymers showing a high compressive strength. The leaching ability, the proper molar ratio of Si/Al in the geopolymeric gel phase and the higher average hardness of the undissolved particles remaining in the geopolymers are found to greatly affect the ultimate compressive strength of the formed geopolymers. Key words: Geopolymerization, Mineralogy, Albite, Microcline

Jan 1, 2003

By Snehamoy Chatterjee, Sanjay Kumar Palei, Smarak Das

Machine manufacturers’ recommendations on maintenance strategies of capital-intensive draglines are not always based on real data and therefore lead to losses from downtime. This paper proposes a preventive maintenance strategy for a dragline deployed in an opencast coal mine based on reliability-centered maintenance and failure-mode-effects analysis using real operational data. Reliability-centered maintenance replaced a cluster of critical failure components of the dragline while satisfying two specific conditions: (i) the components should be replaced at the earliest mean time to failure (MTTF) within the group and (ii) the time taken to replace all the parts should be equivalent to the maximum downtime within the group. Estimated threshold weightage factor identified twenty-six critical failure components for the preventive maintenance strategy, and clustering of components divided them into nine groups. In a group, the loss that is expected to occur by replacing some of the components before their failure, and the gain by reducing the overall maintenance downtime, has been explained through a cost-benefit analysis. The total net profit generated is calculated as US$200,178. This clustering activity also led to a reduction of annual downtime by 231 h, whose approximate market price as equivalent coal production costs $295,365.

May 28, 2020

By Joseph M. Denk, John N. Baran, William J. Francart

Filling or sealing shafts of underground coal mines is required when the mine is declared inactive by the operator, permanently closed or abandoned for a period of time greater than 90 days. Although shaft filling requires the use of incombustible materials for the first fifty feet of the shaft, a sparking potential may exist which has been reported to be the cause in at least one shaft-filling explosion. This paper outlines the method used at the explosion site to monitor mine gases within the shaft to assure the safety of the workers involved in the remainder of the shaft-filling operations. Gases which were monitored include methane, oxygen, carbon monoxide and carbon dioxide. Continuous sampling was conducted twenty-four hours per day to determine the methane liberation and accumulation of gases within the shaft. Once gas concentrations were evaluated, the need for ventilation in the shaft was obvious because methane accumulations within the shaft were in the explosive range. Several methods to ventilate the shaft were explored. The most practical seemed to be the dilution of gas concentrations with compressed air to inject a quantity of fresh air into the shaft. But, when the compressed air was stopped, a buildup of an explosive mixture reoccurred. The pattern of gas accumulation was then studied to find the correct combination of ventilation and shaft-filling time periods which would a1 low for the greatest reduction of the potential for an explosion. Gas concentration sampling continued during the remainder of shaft-filling operations at this shaft and four others at the same mine. In conclusion, this paper illustrates some of the problems which are often overlooked in a shaft-filling operation. If addressed, the work can be done in a safe and feasible manner.

Jan 1, 1987

By Albert R. Rule

Beneficiation studies were made by the Bureau of Mines to develop a process for concentrating phosphate minerals from the altered rock of the Phosphoria Formation. This report describes research on intermediate - and marginal-grade ores from southeast Idaho, The process developed consists of attrition scrubbing and sizing to produce a coarse concentrate; desliming at about 800 mesh (18.5 microns); flotation of the fine sands; roasting of the combined concentrates for removal of organic carbon and combined water; and leaching with SO2 for removal of magnesium and nonapatitic calcite. Results of continuous tests on three different ore types showed that approximately 80 percent of the available phosphate can be recovered at a grade suitable for phosphoric acid production. While leaching with SO2 is not necessary for all ore types, it is an important step in purifying concentrates containing excessive magnesium.

Jan 1, 1966

By Alessandro Navarra, Aldo Quelopana

Sophisticated models have progressively been developed to address the challenges related to long-term, openpit mine planning under conditions of geological uncertainty. Prior research has acknowledged that strategies for mine planning and the design of mineral concentrators are interdependent; thus, it is highly desirable to optimize them together. However, achieving detailed holistic optimization of the mineral value chain remains unresolved because of the inherent limitations associated with mathematical formulations and computational processing capacity. This paper details a method that contributes to bridging these limitations by employing a novel parallelized variable neighborhood descent approach combined with an embedded mass–balance component using linear programming techniques refined through Dantzig– Wolfe decomposition. This approach is exemplified through a case study of a gold deposit, which illustrates the enhanced performance capabilities of the new algorithm. The findings demonstrate significant improvements in the optimization process for mine planning, providing a stronger link between the mine’s output and processing plant’s capabilities.

Mar 1, 2025

By Erhard M. Winkler

The rapid decay and disfiguring of stone monuments in urban and desert rural areas has challenged conservators to protect stone surfaces from premature decay. They attempt to halt the natural process of stone decay and possibly to restore the original strength lost mostly by chemical weathering and the loss of binding cement. Ageneral solution is not possible because the physical and chemical characteristics must be considered for different stone types. The failures of stone preservation and restoration are greater in number than the cures. The need for repair of stone decay goes back to evidence of Roman replacement of decaying stone. The presence of excess water in buildings has long been recognized. Moisture tends to enter masonry from air in humid climates, a most important but often underrated factor (Fig. 1) suggesting that sealing should be the answer. Undesirable staining and efflorescence result in accelerated scaling. Today, the great variety of chemicals available to the modem conservator for sealing. consolidating, or hardening stone fall into two very different categories: surface sealers and penetrating stone consolidants, or a combination of both. SEALERS Sealers develop a tight, impervious skin which prevents access of moisture. Surface sealing has saved monuments from decay by eliminating the access of atmospheric humidity. Pressure tends to develop behind the stone surface by moisture escape. Efflorescence, crystal growth action, and freezing can cause considerable spalling (Anderegg, 1949). Flaking results when moisture is trapped behind the sealed surface. Yellowing and blotchiness are also frequently observed. The following sealants are in common use today: linseed oil, paraffin, silicone, urethane, acrylate, and animal blood on stone and adobe. Extensive cracking and yellowing has resulted soon after application. In the past many such treatments have created more problems than cures: 1. Linseed oil and paraffin have been in use for centuries. Embrittlement and yellowing occur rapidly because these are readily attacked by solar ultraviolet radiation. 2. Animal blood as paint has temporarily waterproofed adobe mud and stone masonry. The origin of blood paint has a religious background rooted in the Phoenician and Hebrew cultures. Instant water soluble dried blood can substitute for fresh blood. Winkler (1956) described the history and technique of the use of blood. 3. Silicones have proven very effective and are long lasting. In contrast, acrylates, urethane, and styrene are generally rapidly attacked by UV radiation (Clark et al., 1975). Sealing of Different Rock Types Granitic rocks have a natural porosity traced to 4.5% contraction of quartz, during cooling of the parent magma, compared with only 2% contraction of all other minerals; protection against the hygric forces may require waterproofing of granite in some in- stances. The Egyptian granite obelisk in London is an example. Soon after its relocation from Egypt to London, Cleopatra&apos;s Needle was treated, in 1879, with a mixture of Damar resin and wax dissolved in clear petroleum spirit; surface scaling became evident after half a year of exposure to the humid London atmosphere. The treatment of the ancient granite monument from Egypt has denied access of high relative humidity (RH) in London to the trapped salts inherited from the Egyptian desert and has protected the monument from decay (Burgess and Schaffer, 1952). The sister obelisk set up in Central Park, New York City, has fared less favorably because similar treatment was done too late, only after the salts hydrated and hundreds of kilograms of scalings disfigured the obelisk surface (Winkler, 1980). Surface coating of other common stones may be needed. Crystalline marble absorbs moisture from high RH atmospheres: dilation may ensue when curtain panels bow as the moisture starts to expand during daily heating-cooling cycles. A good sealer may prevent the moisture influx provided that no moisture can enter from the inside of the building. Limestones, dolomites and all carbonate rocks are subject to dissolution attack by rainwater, especially in areas where acid rain prevails (Fig. 2). The interaction of sulfates in the atmosphere with the stone can be halted by waterproofing to avoid the formation of soft and more soluble gypsum. The stone surface attack can be diminished if nearly insoluble Ca-sulfite crusts can form, instead of Ca-sulfate. Replacement of fluorite or barium compounds at the stone surface acts as a hardener, rather than a sealant. Sandstones have generally high porosity and rapid water travel can occur along unexpected routes and from any direction. Any surface sealing may do more damage by scaling and bursting than if the stone is left without treatment. Sealing of sandstones is therefore not advised at any time. Testing the efficiency of sealants: Several authors discuss waterproofing materials, silicones, urethanes, acrylates and stearates, as to their water absorption, spreading rates of water on the treated surface, water vapor transmission, resistance to efflorescence, and general appearance (Clark et al., 1975). De Castro (1983) measured the angle of contact of a microdrop (0.004 cm3) on a stone surface as characteristic of the wettability. Laboratory tests and limited field performance are described by Heiman (1981). The crest of a Gothic sandstone arch, which was sealed with silicone,

Jan 1, 1994

By S. Barkhoudarian, R. R. Gupta, R. F. Steinberg

A study of the feasibility of using acoustic signals to detect discontinuities ahead of excavation has shown that reflecting interfaces in a homogeneous rock can be easily identified. Moreover, discontinuity interfaces in a very complex field site (where the rock face was weathered, was full of jointed rocks, and had a destressed zone running along the mine walls) could be identified with a reasonable level of confidence, using a cross-correlation technique for signal processing. The results of this study go a long way toward proving the feasibility of the technique. However, further development work is needed to optimize an operating system in a hard rock environment where boring machines are used for excavation.

Jan 1, 1997