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By J de Witte

When used in suitable ground conditions, rock bolts can have advantages over other permanent tunnel lining solutions. Permanent rock bolts offer flexibility in tunnelling profile and rapid rock bolt installation can enable time and cost savings. There are also disadvantages when considering the suitability of rock bolts for permanent support installations. These generally concern achieving the specified durability requirement over the specified design life. By investigating alternate approaches to rock bolt installation, quality assurance (QA), monitoring and design life it may be possible to alleviate some of these concerns.The design and construction benefits that can be realised through the use of rock bolts are primarily related to reducing project program time. This time reduction could be realised if rock bolts are considered as a permanent solution, with the installation being completed as a part of the primary excavation cycle. Any reduction of the program could allow direct and indirect cost savings and in the case of a major project, allow the revenue stream to be realised earlier.Currently ambiguity exists where the treatment of rock bolts as permanent support components is inconsistent with that of (often identical) ground anchors, as utilised in stabilising cut and cover structures. The ground support design process, implementation and testing are generally similar, though the acceptance of rock bolts as long-term support elements is treated differently to ground anchors in technical specifications.This paper discusses some of the benefits available through the use of rock bolts. It offers different solutions to the concerns surrounding durability, including alternate approaches to installation, Quality Assurance practices and monitoring solutions. The selection of an alternate design life is also investigated as another means of alleviating concerns around long-term durability. The paper will also provide an indication of savings that could be expected through the use of rock bolts as part of a long-term support system.

Mar 8, 2011

By Bernardo J. Jiménez Vega, Edy L. T. Montalvan

During the last phase of the Circunvalacion Norte project in San Jose, Costa Rica, preliminary designs for an underpass structure of over 16 km (10 miles) considered drilled shafts as an earth retaining system. Since the project’s execution was delayed and close to the deadline, it was necessary to optimize this structure, with the drilled shafts being the most critical aspect. The key element in order to obtain an improved design was characterizing the job site with a specific site study for seismic demand, and the use of advanced numerical modelling, considering soil-structure interaction. The site investigation comprised the CPT, PMT, MASW geophysical tests, deep exploration drilling, and triaxial compression tests. The terrain was modeled using an advanced constitutive model with hardening plasticity calibrated from the triaxial tests. Plaxis software was used to calibrate the seismic model for the terrain and for the dynamic analysis. Two conditions were considered for the retaining structure: free-head and fixed head. A parametric study with drilled shafts of 1.0 m (3.3 ft) and 1.2 m (3.9 ft) in diameter, and center-to-center spacing of 1.3 m (4.3 ft) and 3.0 m (9.8 ft) was conducted in order to obtain an optimized structure. For each condition of the drilled shaft wall, the computed deformations were compared for two spectrum designs: site-specific spectrum and seismic code generic spectrum. Finally, a dynamic analysis was performed to check the performance of the drilled shafts with optimized spacing using a control earthquake. Based upon seismic performance curves, the analysis showed the possibility of greater spacing for the drilled shafts compared to the original design, obtaining a 32% reduction in the total length of the drilled shafts in the project.

Oct 1, 2022

By Rainer Hüsken

Over the last decades long BOF campaign lives have successfully been established due to improved quality of the refractory material and due to intensive use of slag splashing. On the other hand, steelmakers are more and more faced with elevated phosphorous contents in the hot metal. This phenomenon is a global tendency caused by the increasing pressure to utilize cheaper iron ore sources. In India, iron ore sources have traditionally elevated phosphorous contents. The phosphorous removal challenge calls for using bottom stirring at the BOF converters, as these combined technology of top oxygen blowing and inert gas stirring through the bottom, helps significantly to improve bath mixing and thus in shifting the process towards the optimum metallurgical equilibrium conditions. All this is common knowledge and daily business in the steelmaking shops all over world. Unfortunately, focusing on a long BOF refractory campaign by means of slag splashing and maintaining optimum conditions for high efficient bottom stirring are naturally conflictive aims. Applying slag splashing causes unavoidable bottom built-up which in turn covers or even blocks the bottom tuyeres. Most of the steelmaking shops today are either operating slag splashing without bottom stirring or bottom stirring without slag splashing. Some are trying slag splashing with bottom stirring but mostly only for a certain short period of the whole campaign. Baoshan Meishan Steel is an integrated steel plant, located in Nanjing (China). The plant is operating two BOF shops (3x 150t and 2x 250t), producing various steel grades. Because of the iron ore source used, the hot metal phosphorous content is rather high with up to 2,000 ppm. In order to achieve low phosphorous contents in the molten steel below 200 ppm, Meishan uses the TBM (Thyssen Bottom Metallurgy) bottom stirring technology in both of their steel plants, successfully applying slag splashing and efficient bottom stirring for campaigns up to 10,000 heats. This paper describes the operation procedures, strategies, and the maintenance concept established at Meishan Steel which is suitable to meet both conflicting targets at the same time.

Jul 30, 2018

By Jihan Farhan Lubis, Putu Chandra Darmansyah

Ground vibration caused by blasting has become a common concern, especially when blasting is conducted near buildings or structures. Uncontrolled vibrations can potentially damage nearby infrastructure if appropriate control measures are not implemented. PT Tambang Semen SUKABUMI, a limestone mining company, is planning to carry out blasting activities near a crusher building located approximately 80 meters away. This building is classified as a Class 5 structure, with a maximum allowable Peak Particle Velocity (PPV) of 40 mm/s, in accordance with the Indonesian national standard SNI 7571:2023. To ensure compliance with this limit, a Signature Holes Analysis (SHA) was conducted using the Hanwha HEBS II electronic detonator initiation system. This analysis measured ground vibration from single-hole blasts, with the average vibration from three SHA holes recorded at 49 mm/s. A site constant analysis using the scaled distance formula yielded a multiple R value of 0.87. However, the ANOVA table showed a significance-F value of 0.24, which is greater than 0.05 indicating that the regression model used for prediction was not statistically significant. Using the SHA data and assuming a maximum of 30 blast holes, a recommended delay timing of 22 × 15 milliseconds was selected. This produced a predicted PPV of 17.25 mm/s. The comparison between predicted and actual PPV values demonstrates that the delay configuration derived from Signature Hole Analysis provides reliable results. The observed deviations range from -16% to +29%, with an average deviation of only 8%, indicating a high level of accuracy and consistency. Using the actual blast data, three model prediction were applied for predicting the most accurate prediction that close to the actual value. The SHA method, utilizing actual single-hole vibration measurements and optimized delay timing, provided the lowest average deviation of ±8% and the smallest absolute error (2.45 mm/s) from actual measurements, demonstrating high reliability for sites with sufficient signature data. Meanwhile, the log-log regression model yielded the highest coefficient of determination (R² = 0.751) and the smallest prediction deviation (3%) when standard deviation margins were considered, making it highly effective for predictive modeling.

Jan 26, 2026

By A. B. Hooker, L. C. IlsLey

"Field inspections and data relative to the use of rubber—sheathed trailing cables in mines show that much cable is ruined or its probable life shortened by being overheated in service.The length of cable required to make connection from a source of supply to a machine at the face workings may be 100 to 500 feet. As a rule, the cable is carried on a reel and unreeled as required; and thus in most cases some of the cable is not removed from the reel. The overheating generally occurs in that part of the cable which is left on the reel.Factors that determine the heating of trailing cables are:1. The size of the conductors in the cable.2. The maximum energy to be supplied through the cable, based upon the horsepower of the motor and the degree to which the motor is loaded.3. The voltage of the supply and the variation of the voltage at the receiving4. The time length of current flow and whether continuous or intermittent.5. The kind of current (direct or alternating).6. The amount of cable left on the reel.7. The type of cable used.8. The kind of reel used.In connection with an investigation of the general performance of rubber—sheathed trailing cables, the Bureau of Mines has made a limited study of some of these factors, including the following points:"

Jul 1, 1931

By M. Kermani

This paper presents and compares the physical properties of Gelfill and cemented hydraulic fill (CHF) obtained by lab experiments. Gelfill has an alkali activator such as sodium silicate in its materials in addition to primary materials of cemented mine backfill which are deslimed tailings, water and binders. The CHF and Gelfill samples with various mixture designs were cast and cured for 28 days. Initially, the influence of sodium silicate concentration on the mechanical properties of samples was evaluated using the unconfined compressive strength (UCS) test. Consequently, the effect of curing temperature on CHF and Gelfill samples cured in various curing temperatures ranging from 5?50 °C was studied using the UCS test. Microstructure of selected samples was studied wirth the mercury intrusion porosimetry (MIP) technique. This study concludes that: (i) The mechanical properties of CHF can be improved by the addition of appropriate amount of sodium silicate. (ii) The rate of strength acquisition in Gelfill samples is faster than CHF samples over 28 days of curing period. (iii) Curing temperature strongly influences the mechanical and microstructural properties of CHF and Gelfill samples. (iv) The microstructure analysis revealed that the addition of sodium silicate can modify the pore size distribution and total porosity of Gelfill which can contribute to the better mechanical properties of Gelfill. (v) The MIP tests suggested the microstructure of specimens were changed by adding sodium silicate in a way that the Gelfill samples had a higher percentage of fine pores than CHF samples.

Aug 1, 2013

By Kal Sastry, Anshuman Prasad

This paper presents a population balance model (PBM) for describing the agglomeration process and select a suitable coalescence kernel that can simultaneously describe nucleation, layering and coalescence mechanisms. The PBM is solved numerically by making use of a size discretization procedure in order to simulate iron ore agglomeration in rotating drums where moist feed is added to preformed seeds. Subsequently, a comparison of computer simulation results with the previously published experimental data is provided. Finally, the paper discusses how the current approach can be further extended to the simulation of industrial iron ore agglomeration circuits operated in closed circuit.

Jan 1, 2003

By A. S. Chekmarev, T. Z. Lygina, K. G. Egorova, A. V. Skvorcov

"We have conducted analytical and technological evaluation of sepiolite containing clay. The possible areas of application of the sepiolite have been investigated and complex methods of enrichment of natural sepiolite have been identified. It was determined that for preserving the structure of minerals after processing the most effective method of the natural agglomerates disintegration was the soft abrasion of the clay fraction up to 0,5 mm. Disintegration of sepiolite clay along with using high energy-stressed effects on the matrix can deteriorate the rheological properties of clay suspensions and reduce the yield of drilling mud and sorption properties. To improve the quality of clay powders we used combined gravity-modifying method of wet enrichment. After the wet enrichment the yield of drilling mud increased up to 12.7 m3/t, with the addition of MgO up to 20,3 m3/t. It was noted that drilling muds contenting more than 50% of sepiolite are stable in mineralized (salt) waters. Based on the studied activated sepiolite rocks we obtained the effective heat-insulating materials with relatively low thermal conductivity – 0,165 W/m·K, average strength – 7,29 MPa and water absorption-49,0%.INTRODUCTION The modern development of the Russian economy requires the implementation of scientific and technical tasks. The solutions of it involves a radical reduction in energy, heat losses and material consumption of products, rational and efficient using of all types of resources, as well as the using of new types of mineral raw materials and materials based on it. An example of a new type of mineral raw materials for Russia is sepiolite containing rocks, due to unconventional conditions for their soils accumulation in the climate of the Far North. Sepiolite is a unique type of nonmetallic mineral. It is formed in soils, marine and saline basins, occurs in carbonate and carbonate-clay rocks in the form of lenses and lens – shaped layers, rarely nodules, loose powdery masses, shell-like concretions. Sepiolite may have a soft porous macroscopic appearance or less often the structure of the fibrous mass. Color of sepiolite is from white to cream with gray, green, pink and even crimson shade depending on the degree of pollution. Sepiolite can be in two forms - a-sepiolite (parasepiolite), which occurs in the form of large packets of crystalline fibers and ß-sepiolite, which occurs in the form of amorphous aggregates or small flat rounded particles. The sepiolite fibers have a length of from 0.2 to 2 Å, width from 100 to 300 Å, the thickness from 50 to 100 Å (Geological dictionary, 1973)."

Jan 1, 2018

By Lloyd Buckingham

Barrick Gold Corporation (Barrick) has undertaken innovative methods of evaluating and improving the performance of grinding mills in several of its operations around the world. The results have been positive with some of the mines showing more than 20% net energy improvement leading to more than 43,000 tonnes per year reduction in CO2 emissions in four of the operations reviewed.

Jan 1, 2012

By C. Bester, G. M. Rohde

A major challenge in the mining sector is the responsible management and efficient storage of mine residue. Over recent years numerous tailings dams have experienced unintended spills and failures, with severe consequences for the mining industry, the environment, local communities, and the regional economy. The fourth industrial revolution (4IR) is impacting society due to increased interconnectivity, processing speed, and automated technologies. This paper explores whether 4IR technologies have the potential to mitigate risks associated with tailings dams. Experts in the field of tailings dam operational management were surveyed to determine their view on the risks associated with tailings dams and the potential of 4IR technologies to mitigate these risks. The survey found that a majority of experts believe that certain 4IR technologies have the potential to reduce the risks associated with tailings dam failures.

May 27, 2025

By D P. Blair

Rio Tinto’s Hope Downs Operations are currently mining iron ore in their South Central Pit. Prior to the commencement of mine operations, Hope Downs carried out an extensive archaeological investigation and identified an ancient rock shelter lying within the proposed mine boundaries. The site is significant to the traditional owners/custodians of the land in this part of the Pilbara, and thus the final pit design was changed to preserve the rock shelter, which now lies 30 m outside the mine boundary. In order to further preserve this ancient dwelling from blast-induced damage, blast design procedures were improved over time to minimise the vibration impact when blasting close to the shelter. Blasting and vibration monitoring commenced in May 2008 using pyrotechnic delay sequences and normal-direction firing. In October 2009 electronic delays were used to reverse-fire blasts close to the shelter in order to create a damage zone between the initiating holes and the rock shelter. A detailed statistical analysis of the vibration data shows a reduction in the higher levels of vibration for blasts fired after October 2009, which is most likely caused by the created damage zone. In May 2010, a site-specific vibration model was developed and implemented, and based on Monte Carlo waveform superposition. This model was used to give a further insight and improvement to the blast delay sequences when blasting close to the shelter. However, such models are expensive to implement and have limitations, which reduces their potential for estimating the probability of getting an excessive vibration due to a given blast design. In this regard, it is more realistic and significantly less expensive to use a recently developed probabilistic analysis based on simple charge weight scaling. This analysis shows that there was a higher probability of exceeding prescribed vibration limits at the rock shelter for blasts fired before October 2009 than there was for blasts fired after October 2009.

Nov 8, 2011

By J. David Lowell

For the first time in several years, Chile is again opening its doors to foreign investment. In its new investment code, the Chilean government has announced its willingness to become a partner in joint Chilean-foreign projects for a number of government-controlled porphyry copper deposits at the developed, semi-developed, or prospect stage; and, that it will allow privately owned deposits or deposits discovered by new exploration to be developed with up to 100% foreign ownership. Three deposits of particular interest are: El Abra, with at least 300 million mt of +100% Cu; Los Pelambres, with at least 428 million mt of 0.78% Cu and 0.03% Mo; and Andacollo, with 350 million mt of 0.70% Cu and 0.015% Mo. (El Abra is almost entirely government- controlled; but both Los Pelambres and Andacollo are mostly under private ownership.)

Jan 11, 1974

By Malek Smadi, Yazen A. Khasawneh

"New embankments were constructed mostly on soft clays as part of interstate I69 extension in southern Indiana. The embankments serve as bridge abutments and as part of the fill sections along the interstate extension alignment. The height of the embankments range from 50-ft to 125-ft with a maximum foundation thickness of about 75-ft. The foundation soils comprise relatively high compressible fine grained soils. A fully coupled Hydro-Mechanical numerical simulations were conducted for optimizing the construction stages of the embankments. The objective of the staged construction is to allow for sufficient effective stress and undrained shear strength gain to ensure foundation stability under the stage load. Wick drains were utilized to shorten the drainage path and thus accelerate achieving the required undrained shear strength. The extensive field investigation and laboratory testing programs provided a good understanding of the subsurface conditions and allowed the use of a relatively advanced soil constitutive model in the numerical simulations of the staged construction. The effectively designed instrumentation program allowed for monitoring the settlement and pore water dissipation during construction. The pore water pressure, and surface and subsurface settlements from the numerical model predictions reasonably agreed with the instrumentation data over the construction period.INTRODUCTIONThe stability of soft fine grained foundation soils due to embankment construction is dependent on the undrained shear strength of such soils. The permeability, compressibility, and drainage boundaries control the foundation soils response (settlement magnitude and rate) to loading. The settlement magnitude is a function of minerology and soil structure. The settlement rate which is equivalent to the rate of excess pore water pressure dissipation is a function of the soil permeability and drainage boundary. The dissipation rate control the evolution of effective stress and thus the gain of undrained shear strength. As such, if the increase in total applied load is controlled such that enough time is granted for the evolution of the total stresses into effective stresses, then the stability of the foundation soils is enhanced by the gain of the undrained shear strength. The controlled application of the total stress is the definition of the staged construction. From the definition of the staged construction, it is obvious that the process is a coupling of the hydraulic and mechanical responses of the foundation soils."

Jan 1, 2017

C. P. SANDBERG, LONDON, ENG : † I think we should all be grateful to the Pennsylvania Railroad Company, and to their chemist, Dr., Dudley, for spending so much time and money in order to solve an important question ; nor are we less indebted to the public spirit which leads them to impart the experience thus gained. In Europe nothing similar has hitherto been done, either by a company or by any private individual. In England the great railway companies employ their engineers in other ways, and do not keep a chemist or specialist to study rails; but even if they did they would probably not publish the results. The chief professional engineers are so occupied with their private practice of railroad construction generally, that they cannot be expected to devote their time and energies to so special a question. The German Railway Union has, in my opinion, missed the real object of its elaborate researches by falling into the error of specifying costly, impracticable tests for rails-tests at the same time which do not infallibly expose the impurities that may be in the rails under examination. There has, therefore, been nothing done on this side of the Atlantic in the way of exhaustive study to determine the best composition for steel rails. America should consequently have full credit for the enlightened example which she has set. I wish, however, to make a few remarks on Dr. Dudley's second paper, a paper which follows very much upon the same lines of argument as the first read three years ago, upon which I have previously touched in my paper on the same subject read at the meeting in August last. If Dr. Dudley had discovered a new metal he could hardly, I think, have taken more pains to prove that he was correct in his first formula for the best chemical composition of steel rails. But I have seen so much done in the way of proof by experiment that I am inclined to think that almost anything can be proved by experiments and by samples. If Dr. Dudley would only give up his formula, which would not suit any country-not even America- * For the convenience of members it has bees thought best to insert the continuation of this discussion at the Virginia meeting in tide place, rather than to delay its permanent publication until the issue of Volume X, Transactions, where it would properly belong. T. M. D., Sec'y, † Sent to the secretary in manuscript.

Jan 1, 1881

By Yuanbo Zhang, Zijian Su, Bingbing Liu, Guanghui Li, Tao Jiang

With the depletion of rich manganese ores, high-Fe content manganese ores are becoming the mainstream resources for manganese extraction. Reduction roasting-magnetic separation process is reported as a relatively effective route to realize the separation of manganese and iron. This study investigated the phase transformation of MnO2 and Fe2O3 briquettes (molar ratio 1:1) roasted under various temperatures and CO–CO2 atmospheres. Results showed that when the CO content was in the range of 0–10 vol%, MnxFe3−xO4 (x = 0−1) phase was formed and its content increased with the rising of temperature. The formation of ferromagnetic MnxFe3−xO4 with strong magnetism resulted in an inferior separation of manganese and iron by magnetization roasting-magnetic separation process. With the increase of CO content to over 25 vol%, the MnxFe3−xO4 content decreased while the content of feebly magnetic substance (MnO)y(FeO)1−y(y = 0−1) increased. Further increasing the CO content to over 80 vol%, (MnO)y(FeO)1−y was reduced to MnO and metallic iron.

Mar 1, 2017

By Paul H. Johnson

A new system for leaching many types of ores has recently been developed on a commercial basis by J and J Research and Development, Inc. of Hanover, New Mexico. This revolutionary new leaching system consists principally of three new leaching reactors; viz, (1) a large, air-agitates, column-like reactor for leaching crushed ores that is constructed in an underground environment and has the inherent ability to do a very efficient job of leaching, (2) a vat-like, air-agitated vessel for leaching an rinsing finely ground ores and , (3) an air-agitated copper precipitation column that is built underground and utilizes an inexpensive dense or heavy scrap iron as a copper precipitant. Each of these new reactors have been used in a large leaching plant near Hanover, New Mexico.

Jan 1, 1973

By G. Bourque

One of the design criteria for the Mount Wright facilities was to incorporate the latest proven automation techniques and devices for the new crushing, grinding and concentrating plant. The heart of the centralized control system is a Fox 1 process computer, located in the central control room in the administration building. The entire operation, i.e. crushing, conveying, storing, grinding and concentrating, is monitored and controlled, through the process computer , by one operator via a CRT console. In case of computer failure, the control is automatically, and without process interruption, transferred to manual back-up panels. One of the newest management tools, the process computer is programmed to collect and automatically print out shift. daily and monthly reports on tonnage, metallurgy and equipment operating time, for better planning of operations and preventative maintenance.

Jan 1, 1977

Albin, B. R Billings, Mont. '28 Amster, Nathan L 25 Broad St., New York, N. Y. '28 Bache, Jules S 42 Broadway, New York, N. Y. '28 Barrett, C. P 5338 Harper Ave., Chicago, 111. '28 Bayless, William S Russ Bldg., San Francisco, Cal. '28 Bean, Louis, H 60 E. 42nd St., New York, N. Y. '28 Beatty, Ross J Room 604, 6 N. Clark St., Chicago, III. '28 Benwell, Oswald F Hold Mags. '28 Beymer, Albert S., V.P., Keystone National Bank Pittsburgh, Pa. '28 Blumenthal, Hugo 44 Pine St., New York, N. Y. '28 Boettcher. Charles Ideal Cement Bldg., Denver, Colo. '28 Bowlus, Thomas H., Banker, Pres., Allen County State Bank Iola, Ran. '28 Brown, Colvin B Chamber of Commerce, Washington, D. C. '28 Burt, Maxwell Struthers Southern Pines, N. C. '28

Jan 1, 1934

By J. A. Finch

In this paper, the author offers a personal view of what the next 30 years holds for mineral processing. Restating that mineral processing will remain a vibrant industry in raw material production, growth opportunities in waste management are identified. The processing sequence familiar now (mining ?mineral processing ?extraction) will become more interwoven. In situ processing (i.e., milling underground) will evolve from concept to demonstration. Opportunities to exploit physical properties altered in chemical (pyro- and hydro-) processing will present themselves. In primary grinding, the path to AG/SAG milling will progress with little deviation but opportunities in regrinding are wide open. Flotation will see the trend to designing bubble/particle reactors accelerate simultaneously with a vigorous response from mechanical cell suppliers. Gravity separation remains a bastion of the lone inventor but this author anticipates that the new lines will come from the waste management business. The paper concludes with the examination of the “research cycle” and identification of growth in small “high tech” companies and university research centres

Jan 1, 1998

By AIME AIME

A THOROUGHLY satisfactory crowd turned out at the fall meeting of the Industrial Minerals Division and took an active part in the entire program. On Thursday afternoon, Sept. 24, a limestone plant was inspected, technical sessions occupying the attention of the visitors all day Friday and Saturday morning. Headquarters were at the Nittany Lion Inn, an attractive hostel on the Penn State campus, at State College, right in the center of Pennsylvania. We are still in the dark, despite inquiries, as to just what breed of lions Nittany lions are. As nearly as we could find out, Nittany is not a Biblical name, as it sounded to us, but a corruption of the name of an Indian princess, or maiden, or maybe just girl that haunted those parts in bygone times and after whom a near-by mountain was named. Penn State athletes are "lions" and there you are. The meeting was supposed to be a joint one with the American Ceramic Society's Materials and Equipment Division; but it was quite evident that the Institute had a much better publicity agent than the Society, which bothered Ross. Purdy, the aggressive secretary of the ceramic people, no end. However, Secretary Purdy saw to it that everyone present fully understood that the Ceramic Society was present, so that that contingent all but stole the show, its representatives presiding at every meeting. The Pittsburgh Section of the American Ceramic Society was also supposed to be holding its fall meeting there at the same time, but made no trouble at all for anybody, as one of the speakers remarked.

Jan 1, 1936