In 2006, the world population reached 6.5 billion and the global economy is rapidly expanding. Consequently, global use of mineral resources have become huge. Rapidly growing China's appetite has a great impact. Therefore, it is the author's big concern over the following issues for sustainability of the world. Depletion of resources, progress of the domination by international resources majors, increasing dependence on resource-rich but politically unstable developing countries, resurgence of “resource nationalism”, beginning of world wide struggle for securing resources against possible shortage, serious environmental problems caused by massive mine development, frequent conflict between mining companies and local people, and escalating market prices. Just now, it can be said an era of “Resources Crisis”. However, in today's global economy, nation's economic security depends on access to adequate mineral resource supplies from a variety of international sources. Under these circumstances, it is strongly expected that (1): Japan should immediately act for resources security with firm diplomatic strategies (2): Japan should make its best efforts to achieve the world highest resource productivity (Material Intensity per Service unit = min.) for environmentally sustainable development of the world. Several suggestions to cope with resource crisis are made.
The research was mainly performed to check whether or not the blast burden influence vibration magnitude. This is associated with the necessity to reconsider blasting design in order to reduce vibration to the acceptable levels. Blast vibration monitoring of three scenarios of burden were managed in limestone quarry. The vibration monitoring results are found in good agreement with what had been found by other researchers in terms of duration, amplitude, and frequency. Vibration waveforms typically last for 50 to 100 milliseconds. The peak amplitudes decrease according to additional distance. Frequencies decrease with increasing distance. The weight scaling law between the PPV and scaled distance revealed three relationships for three different scenarios of burden, which obviously indicate that blast burden influences vibration magnitude. The highest vibration magnitudes are produced by the biggest blast burden. Otherwise the lowest levels of vibration magnitude are produced by the smallest blast burden. Parallel with the main idea, which were mainly performed to check the influence of the blast burden to vibration magnitude, investigation was extended to measure fragmentation of the blasted rocks. Fragmentation measurement was achieved using the analysis of scaled photograph taken form a muckpile. Using software known as Split Engineering, the blasted rocks resulted from three scenarios of blast burden were simply calculated and presented in size distribution curve. The average fragment size increases exponentially with increasing blast burden.
A high-resolution borehole tilt-meter is introduced to measure the inclination of rock slope at an open pit limestone mine, and the movement of rock slope is analyzed based on the measured results from the tilt-meter and numerical results by a three-dimensional boundary element method (3D-BEM). Firstly, the applicability of tile-meter to monitor the movement of rock slope due to a bench-cut excavation is investigated by 3D-BEM and the required accuracy of a tilt-meter is made clear. Then a high-resolution borehole tilt-meter is introduced and explained. Secondly, based on the measured results for nine months in a limestone mine, the mechanical behavior of rock slope is analyzed. The general mechanical behavior of rock slope due to excavation of a bench is then analyzed by 3D-BEM. Finally, using the results of measurement and numerical analysis, the mechanical behavior of rock slope is made clear. It is concluded that a high-resolution borehole tilt-meter is applicable to monitor the movement of rock slope in a short period.
Authors have studied the landscape evaluation of a quarry using videos or still pictures as change stimulus. As a result of these studies, it is found that a video is more suitable than a still picture as change stimulus for the reason why it has reality and liveliness. But more time, labors and costs are required for creations of change stimulus and experiments using a video rather than a still picture. This study aimed at establishment of the reasonable and reliable experimental method for landscape evaluations of quarry. Then, we carried out three investigations as follows; (1) The suitable presentation method of a change stimulus was examined. It became clear that the presentation by a screen projection with near an actual scale was suitable for videos, while the presentation by a personal computer monitor was suitable for still pictures. (2) The applicability of the animation for change stimulus created using the virtual reality system (VRS) was examined. It was judged that its application to the landscape evaluation of quarry is possible for the animation landscape simulation created with VRS. (3) The minimum number of the persons, from which the reliable and stable evaluation results is obtained, was examined. It became clear that the minimum number of the persons is about 30, even when a change stimulus is which of an animation and a still picture.
Influence of compositional and textural changes by weathering on breakdown property of rocks was considered through two cases. First case is the slaking property change of Poronai siltstone by preceding deteriorations such as weathering alteration and shear by landslide. The altered sample, where increase in smectite was observed, showed accelerating slaking behavior. In contrast, the sample, that was fractured by landslide but not altered, showed drastic slaking in the early stage of the slaking test and then approached to the behavior of intact sample. Second case is the influence of weathering on breakdown behavior in uniaxial compressive test. Samples are Inada granite and Kuroishiyama gabbro. In their weathered samples, fractures occurred by weathering were observed and their distributions had close relationships with the composition and texture of the plutonic rocks. Breakdown behaviors in the uniaxial compression were affected by the fractures developed through weathering. In these two cases, the breakdown behaviors are considered to relate with compositional and textural changes occurred by weathering, and it indicates that grasping about compositional and textural change is essential for understanding and prediction of physical property variation in weathering environment.
To maintain the big mining operation rates for 700kt/day material movement at Batu Hijau Mine in Indonesia, many modern technologies have been employed. Some of them are introduced in this report. They seem to be traditional in one glance but you may find that they are the state of art technology of modern mining applying in the unique style.
Los Pelambres Mine (hereinafter referred to as MLP) is located about 200km NE of Santiago in Chile.MLP is a porphyry copper deposit producing molybdenum as a byproduct. Annual production of copper concentrate in 2005 is 867,000t. MLP has two features in the mine site. One is that the strip ratio is lower than the other mines because the overburden was eroded by the glacier. The other is the electric generation using the downhill conveyer belt which transports ore mineral from the mine to the concentrator. Now MLP is going ahead with the construction of the new tailing dam (1,700 Mt) and increasing the mill throughput concentrate from 125,000 ton per day to 140,000 ton per day.
As slicing the deposit down, the problems of blast vibration to the local residents have grown in most surface mining. Previous and general actions for vibration control can be used on a limited scale, and have adverse effect on the mining productivity. For one of efficient solutions, we have developed the new ANFO based on continuously measurement data and computed form of blast vibration in populated areas, and that has the potential advantages of mitigating vibration and keeping productivity. The inner rim presplit blast of the mining area is another solution for the first time in limestone mines and quarries of this country. Those solutions provided 22% mitigated blast vibration results and can help stability and productivity of the mining.
The Ganji quarry is located in Tsukumi City, Ooita Prefecture. This quarry mainly supplies limestone for cement material to Ooita Plant which is one of the biggest cement plant in our company and produces other various limestone products for steel industry, chemical industry, construction industry, etc. This quarry has two production systems of No.1 and No.2. The No.1 production system produces cement material for Ooita Plant and the No.2 production system produces other products for our customers. We reconstructed its underground processing plant and for rationalization unified two control centers from the year 2001 to 2005. This report presents the background and outline of this reconstruction.
Tsukumi is the greatest limestone supply region in Japan , and five companies are quarrying 30 million tons every year in this area. TODAKA MINE of TODAKA MINING CO. which is one of them is located in the west of this area , and is now quarrying 12 million per year . The total amount of limestone produced so far is to 370 million-tonnes since commencement . However , the remaining quantity of limestone that can be excavated had decreased . Development of a new mine is planned in Usuki, next to Tsukumi . It was decided that this new quarry, conceived in the 21st century, should be designed and developed to a corporate philosophy which values the well-being of local residents and their environment. The quarry project is designed to have a production capacity of 12 million tones per year, to be welcomed by the local community, and to secure the supply of limestone for future generations.
A slope-working car is a machine which was developed to work more safely and to reduce the working load, in the work to set the net for rock-fall prevention on the periphery in Buko mine. This car is made by reorganizing the front attachment of 45t-grade backhoe, and it is equipped with the gondola which is able to take on a worker, tools and materials, at the tip of front attachment. In addition to the good safety operation, with regard to the working cost, it is also expected that the method using the slope-working car is able to reduce the cost about 10∼13% less expensive compared with the traditional method. Under present condition, there are only a few actual results, but we will carry out the education of workers to promote the working efficiency and to increase the operator's skill for inexperienced workers.
Minowa Mine has been working in west area of Mt. Buko (1,304m above sea level) that is located in southeastern edge of the Chichibu Basin, the western part of Saitama Prefecture. Limestone is produced over 800,000ton a year for cement materials, aggregate materials and lime materials, etc here. Minowa Mine has three benches. One of them, Takeyama bench is situated in west corner of Mt. Buko. At the top bench of Mt. Buko, Minowa Mine, Ryoko Lime Industry Co., Ltd Une Mine and Buko Mining Co., Ltd Buko Mine have been operating in cooperation. It is very difficult to excavate Makuiwa, the huge precipice of north slope below Takeyama bench at the top bench. The excavation was started cautiously around the end of 2000 with setting up benches to prevent sudden falling rocks below the surface quarry. However, massive rock of about 3,000 meters cube, a part of Makuiwa came off and collapsed in April 2002. Moreover, fissure with fear of secondary collapse breaking out was found. Therefore we took preventive measures immediately against collapsing. Since then Makuiwa have been entirely excavated with the improved machine above the precipice with taking preventive measures against collapsing.
Some limestone limestone quarries in Japan require technical improvements to their mining procedure, especially at steep slopes . One of the critical concerns in mine scheduling is to define when these steep slopes need to be mined, and to plan how they can be mined safely. Large equipment can be used to dig the edge of steep slopes, but it must be ensured the safety of the operation and protect against rock block failure. Blasting may also be used, but it must be controlled to ensure the wall and block stability. Une mine operation has been using pre-split blasting with ANFO to conform to the design line of the final wall. This pre-split blasting technique can limit blast energy transmission, reduce vibration and protecting the final wall from the damage of main production blasts. At the slope side, which is also steep, pre-split blasting techniques will reduce the risk of slope instability and rock mass failure. However different methods may be required depending on geological structure conditions and mine scheduling requirements. The author has applied pre-split blasting techniques and combined its usage with large equipment for the steep slope mining.
For one method of a cost reduction, we focused on the electricity cost, which had a high ratio in our total cost,. We have introduced ‘Co-generation System by ESCO’ , which aimed to utilized the unused waste heat of generator for the support of dryer in our plants effectively. By the introduction of this system, our electricity cost in 2004 reduced approximately 17.4% and our fuel cost by approximately 1.6% in our plants by the way of waste heat recovery. Also, we have reduced the fuel cost by 100% in our plants' dryer since August, 2005. The introduction of “Co-generation System” has brought benefits for us.
To meet exhaust emissions regulations that becomes severe worldwide every year, Caterpillar Inc. has developed the ACERT®technology that decreased exhaust gas of the diesel engine. ACERT®, Advanced Combustion Emission Reduction Technology, that is concentration of technology that Caterpillar has cultivated in long history of engine development for past 75 years. ACERT® Technology is based on the theory “If all the processes of combustion can be controlled efficiently and best, exhaust gas can be suppressed to the minimum” and control four key elements (Air systems, Fuel systems, Electronics, and Aftertreatment ) in the best. Cat engine with ACERT® Technology is simple and reliable, and it is already installed in many Caterpillar construction machines and Highway truck in North America.
The major mines around the world are taking the steps for enlargement of the dump truck size to improve the efficiency, and the yearly demand for the 300ton class dump trucks is increasing year by year. About 25% of the total world demand for such 300 ton class dump trucks is predicted to be the demand for the oilsand mines where the demand for the hydraulic shovels looks promising as well. The super large size excavator EX8000 was developed to meet such demand for the matching shovels for the 300 ton class dump trucks. The development was carried out based upon the experience from the existing super large size excavators, and emphasized on achieving the unsurpassed reliability and availability that is the absolute necessity for the loading machines in the mines. Both the first machines, the second machines of EX8000, and the third machines are delivered to the oil Sand mine in Alberta state in Canada. These machines are engaged in digging up the topsoil layer and the oil sand.
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July 15, 2015 A new online journal "Mechanical Engineering Letters" has been launched by The Japan Society of Mechanical Engineers (JSME). This publication of such a letter journal is not only a new experience but also a tremendous challenge for the mechanical engineering society.
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