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Jan 1, 1986

By D. M. Morrison

"The most important factor in Canadian mining is not the operating cost of current projects but the availability of capital for future projects. The future of mining at depth will be producing ore from the top of the orebody working downward with very effective, tightly controlled mining methods, i.e. either selective mining or bulk mining with well controlled dilution and fragmentation. The key characteristics of future mines will be smaller access excavations, more effective ground support, very precise blasting techniques and more efficient and reliable materials handling systems. Equipment will be smaller and designed for high efficiency and low maintenance, reducing both the capital and operating cost. This means there will be fewer scoops, more continuous mucking machines and conveyor belts, both lateral and vertical.Orepass failures have become accepted and the resultant redevelopment and retramming has become common. The capital investment in so-called permanent ore passes and crusher stations becomes questionable, particularly when crushers are only necessary for less than 10% of the ore going through the system. The best way to solve the chronic instability of ore passes is, as with all of the stability problems at depth, by reducing the excavation size rather than increasing ground support. Smaller access drifts would reduce the capital cost and increase the rate of development as well as reduce the amount of waste to be handled, reducing the ground support and the ventilation requirements. Large drifts and ore passes are essential only for the equipment needed to handle large pieces of ore and the productivity of scoops is very expensive when the requirements for ventilation and large access drifts are taken into account. The key issue is the fragmentation generated by primary blasting.The future of mining in Canada will depend on simple and robust technology geared to the environment in which it will have to operate. Its survival will depend on some-thing much more fundamental and difficult to accomplish than a technological advance — it will require a dramatic change in the way the mining process is managed, how work is organized, how effort is rewarded and how costs are measured — a complete change in mind-set."

Jan 1, 1996

By Albert Ruiz

The 2,250-MW, coal-fired Navajo Generating Station located in Page, AZ draws water from Lake Powell using submersible pumps installed in five inclined shafts. Drought threatens to lower the reservoir to below the existing intakes. A system of new steel-lined intake shafts located on the same site was required for uninterrupted plant operation. The small size of the site, and the need to keep the existing system in operation, required detailed designs and placed significant limitations on construction equipment and activities. The Navajo Sandstone that forms the near vertical shoreline of the reservoir is 98 percent very fine grained quartz, highly abrasive and contains highly fractured intervals that presented numerous challenges to drilling the new 152-m (500-ft) deep, 109-cm (43-in.) diameter intake shafts inclined 23° to 26° from vertical. Spatial constraints, submersible pump design and operational criteria required that each shaft have a unique inclination and orientation and hit a small breakout target located 76 m (250 ft) under water. Sophisticated drilling equipment and techniques as well as state of the practice downhole survey technology and methods were used to make adjustments and maintain drilling accuracy with less than 1 percent deviation. Environmental requirements mandated water as the drilling fluid and grout was not allowed in to the lake under any circumstances. The shafts were videotaped and the breakout locations were examined using an underwater remotely operated vehicle (ROV) to verify shaft locations and rock conditions, and to guide placement of pneumatic packers to ensure grout did not transmit to the lake during the steel liner installation. In anticipation of the invasion of quagga mussels, the shaft design included an allowance for a chemical dosing system and a copper-rich alloy at the exposed portions of the steel liner.

Jan 1, 2011

By C. A. Hollingsworth

The Deep Leg Flotation Cell was developed to solve a problem which confronted the Smith-Douglass Company on moving from one mining area to another. Poor recovery and, to some extent, inferior concentrate grade were encountered in the silica flota¬tion circuit. This was believed due to the softness of the phosphate which caused it to form slime. In view of the urgency of the matter, the problem was attacked from two angles. The first involved the development of a flotation cell which would not create slime and the second, a new or improved reagent for floating silica from phosphate rock which would be less sensitive to slime than reagents currently in use.

Jan 1, 1964

By Ben C. Gerwick

This publication is intended to document recent innovations and technologies that have the best potential for effectively improving the quality of marine foundations while reducing the cost, time and risk of construction. Marine foundations originated in Neolithic times with the Swiss Lake Dwellers who constructed pile-supported houses, safe from invading tribes. The Queen of Babylonia built the first recorded bridge in 1500 BC across the Tigris. The foundations were large flat stones laid on the river bottom. About the same time in India, builders extended their water well techniques to the construction of ?well? foundations in the beds of their rivers. These were really the first open caissons; brick walls were built up in a circular ring while divers excavated sand from the bottom, sometimes at a depth of 100 feet. The Romans extended the clay-filled cribs of the Middle East to shallow cofferdams, which they sealed by underwater concrete made with pozzolanic cement from Mt. Vesuvius.

Jan 1, 2013

SOME months ago a Committee on Deep-level Mining was appointed [by the Government of the Union of South Africa] to consider the possibility of gold mining being carried on at a depth below 8,500 feet. The Committee consisted of Sir Robert Kotze (Chairman) , Mr. H. S. H. Donald (Government Mining Engineer), and Mr. H. R. Hill. The Committee has now made a report which was tabled in the House of Assembly on March 1st. The Committee reported that the tonnage of ore locked up in the deep level areas of the Central Witwatersrand is enormous, and in the 30 miles between Roodepoort and the East Rand Proprietory Mines has a value of about £200,000,000. The Committee says that, with good ventilation, the present system of wet mining, possibly with some modification and with the aid of refrigeration, may be carried to 10,000 feet, but that greater depths will require the adoption of dry mining. "A vigorous campaign of practical experiment into the possibility of dry mining should be initiated, and the Committee recommends to the Government the appointment of a committee of experts, consisting of representatives of the mining industry, the Mines Department, and the medical profession, with the Government Mining Engineer as chairman. The Committee suggests the provision of £30,000 for the first year for the investigations and experiments contemplated, which could best be carried out by an organization which might be styled 'The Rand Mining Research Institute' and constituted somewhat on the Jines of the South African Institute for Medical Research" . The Committee suggests that this committee of experts should arrange for experiments to be made with dry mining in one of the deepest mines, and investigate ventilation, refrigeration, support of workings, and the physiological problems connected with mining. "We emphasize the necessity of treating this whole question as one of importance and urgency. The investigations should be prosecuted with the utmost vigour and should not be delayed at any time for want of funds or for any other reason. If they are not done thoroughly and quickly, the whole scheme might just as well be left severely alone.

Jan 1, 1945

By Donald Bruce, Alex Reeb, George Filz, Wesley Schmutzler, Mitsuo Nozu

"One million seven-hundred thousand cubic yards of deep mixing were installed to support an elevation raise of an earthen levee known as LPV 111, which is located in east New Orleans. The deep mixing was done by two contractors using somewhat different technologies, but producing elements of the same size. As part of the quality control and quality assurance program, 507 deep-mixed elements were cored and 5,082 specimens were strength tested in unconfined compression. This paper presents data from the coring and testing program. Very high percentages of the core run lengths were recovered, except during one period for one mixing technology. The coring methods are described, and reasons for the isolated episode of low recovery are discussed. The strength data show that the specification acceptance criteria were satisfied. Statistical parameters of the strength data are provided, and trends between strength and the following factors are discussed: depth, soil type, binder factor, and project-specific experience. Photographs of longitudinal cuts of core specimens are presented. Important lessons learned from this unusually large project are described.INTRODUCTIONThe Lake Pontchartrain and Vicinity Hurricane Protection system included a project known as LPV 111, which is an approximately 5-mile long segment of levee and floodwall located in east New Orleans along the Gulf Intracoastal Waterway and adjacent to Bayou Sauvage National Wildlife Refuge (Cali et al. 2012). The majority of the project consisted of a raise of an existing earthen levee from an existing crest elevation of about 18 ft to a new crest elevation of about 28 ft. The underlying soils were weak and compressible, providing inadequate support for the raised levee. Ground improvement in the form of deep mixing was selected to provide the necessary stability and settlement control for the raised levee.The US Army Corps of Engineers (USACE), New Orleans District, was the governmental agency in responsible charge of the project, including approval of design, construction, and payment. The lead designer was URS Corporation, and the general contractor was Archer-Western-Alberici (AWA), working in alliance with TREVIICOS South (Trevi), who, together with Fudo Construction (Fudo), performed the deep mixing.As part of the quality control and quality assurance program, over 500 production deep-mixed elements were cored, the cores were carefully logged, and over 5,000 unconfined compression tests were performed. In addition, selected specimens were carefully photographed before and after longitudinal saw cuts to expose the interior of the specimens. This paper provides a summary of the coring and testing performed on the production deep-mixed elements."

Jan 1, 2015

By Ziyad Abunada, David O’Connor, Fei Jin, Abir Al-Tabbaa

"In-situ remediation of contaminated land with deep mixing can enable a multi-technique remedial strategy on the same site combining low permeability barriers, permeable reactive barriers, stabilisation/ solidification treatments as well as ground improvement, delivering significant advantages over alternative strategies. This was the core objective of Project SMiRT (Soil Mix Remediation Technology) which involved the execution of the largest research field trials in the UK to date to provide field validation for this technique. Around 800m3 of soil were treated on a contaminated site in Yorkshire in May 2011 with 6 different treatments, testing ~40 binder compositions and 10 different installation methodologies. Field monitoring, testing and coring activities at the site took place within the first 2 months after treatment and then again at 34 months after treatment. This paper presents an overview of the field activities to date and some 3-year results and assessment of a subset of the treated soil sections. Some good correlations are seen together with some clear differences between treatments. There is generally an observed consistency with depth, with the mixing effectiveness having a more profound effect than the binder composition or content, within the tested materials and ranges. These field trial activities are currently being used in the development of the full-scale commercial remedial strategy for the site.INTRODUCTION AND OVERVIEW OF PROJECT SMiRTWhile there are strong financial and environmental incentives to remediate and redevelop brownfield sites there are also barriers including fear of the unknown, regulatory control, delays, increased costs and the stigma associated with such sites. Hence the remediation process needs to be conducted in such a way to maximise the incentives and overcome the barriers, which is how deep mixing found its niche in the land remediation market. Soil mix technology is such a versatile technique that can perform a number of remediation treatments on the same site. These include low permeability in-ground barriers (cut-off walls), permeable reactive barriers (PRB), stabilisation/solidification (S/S) treatments, other additive related remediation, e.g. in-situ chemical oxidation and bioremediation, as well as soil amendments for greening and also ground improvement all on the same site (Al-Tabbaa et al, 2011). Placed in the context of alternative solutions, soil mix technology could potentially replace the five techniques shown in Figure 1, which would be required to deliver the same treatments mentioned above. Treatment trains strategy, where a combination of techniques in succession are used to both reduce the contamination levels and deal with residual contamination, is becoming common in land remediation and the use of one set of equipment to deliver this would bring about significant financial advantages. In addition, soil mix technology has many other advantages in terms of speed of implementation, elimination of exposure to contamination, elimination of off-site disposal and low cost. Soil mix technology for the remediation of contaminated land emerged in the UK in the mid 1980s and has since been employed in over 30 or so projects, which far exceeds its application to ground improvement for which only a handful of jobs have been carried out to date."

Jan 1, 2015

By Jie-qun Zhai, Jian Jia, Ke Yang, Xiao-lin Xie, Yu Zhang

"With cities’ development, underground space exploitation presents a need for bigger and deeper constructions now. Technical problems founded during the construction of deep foundation pit support become more and more important. The supporting system has to cut or partly cut off hydraulic connection outside and inside the foundation pit, control the ground settlement caused by dewatering and make sure safety of foundation pit and its surroundings. Some preliminary study and application of ultra-deep soil reinforcement methods have been conducted in Shanghai’s deep excavation engineering. On the basis of engineering practice of ultra-deep foundation pit in Shanghai, some field and laboratory test, this paper analyzes effects of different ultra-deep soil reinforcement methods and their influence characteristics of surrounding environment. It also summarizes these methods’ sealing effect, construction and economic efficiency and concludes their characteristicsINSTRUCTIONShanghai is formed from marine sedimentation. In Shanghai, from earth’s surface to 30~40m underground, soil is mainly consist of soft clay with 40% moisture content. There are also many thin silty-sand layers in the earth, so the soil is both soft and permeable. Under 40m, soil is mainly thick silty-sand layers and fine-sand layers with medium density and confined groundwater whose water head is about 7m high.With the rapid development of Shanghai’s municipal construction and high-rise buildings in the recently ten years, the number of underground structure including subway station, tunnel and high-rise building basement are constructed rapidly. Due to the permeability and softness of Shanghai’s soil, it is necessary to reinforce soil to make sure the safety and high construction rate of engineering project in Shanghai.Because of deeper excavation depth and bigger excavation area in Shanghai, ultra-deep soil reinforcement is used preliminarily in Shanghai. Combining with engineering practice of ultra-deep foundation pit in Shanghai and employing field and laboratory test, this paper analyzes effectiveness of different ultra-deep soil reinforcement methods and concludes these methods’ characteristics and their applicability. All this can guide further application of these methods."

Jan 1, 2015

By Wei Victor Liu, Omer Faruk Ugurlu, Chengkai Fan, Bei Jiang

Accurate prediction of truck productivity plays a pivotal role in improving the efficiency and profitability of openpit mining operations. This paper proposes a deep neural network (DNN) model to overcome the challenge of predicting truck productivity in openpit mines. The prediction model was built using eight variables and was optimized by considering different train-test split ratios, numbers of hidden layers and neurons, and activation functions. The proposed model’s performance was evaluated using various metrics and compared with other commonly used machine learning algorithms. The results showed that the proposed model outperformed traditional machine learning models by achieving higher prediction accuracy. Moreover, a single-variable sensitivity analysis showed that haul distance is the most influential variable for predicting truck productivity. This study marks a pioneering effort in employing DNN to predict truck productivity in openpit mining, signifying a notable advancement in the field.

Jul 1, 2024