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By M. Stelter

Since the first years in copper electrorefining natural products have been used as so called "additives" in the electrolyte. Glue as one of these additives offers a lot of different reactions with the metal ions and also with other additives like thiourea in the electrolyte. For a deep understanding of the effect of these additives it is important to know the routes of possible reactions in the electrolyte as well as the basics of electrocrystallization. Using this knowledge the interpretation of nodulation or inclusions of electrolyte in the cathodes in copper electrorefining is easier than before. Setting up on physical and chemical properties of the electrolyte and the additives practical investigations of the effects of additives in copper electrorefining and their impacts on copper crystallization and cathode quality are presented in this paper. Chemical deposition of glue against time and temperature are only few of the effects that are mainly caused by the use of natural products. In fact parameters like anodic and cathodic polarization are strongly affected by the additives as well as the effects of the additives are strongly affected by current density. This second part of the paper presents results concerning interactions of the above mentioned parameters.

Jan 1, 2007

By Melinda Bissinger, Frederic Berube

Environmental considerations are important in the aerospace industry. To that effect, several elements such as engine emission, noise and materials are identified by the industry and the society as requiring significant improvements for future and current products in order to be aligned with current expectations. In this context, the industry is addressing this opportunity by investing significantly in new engineering solutions that will meet greener targets. To this effect, the impact of material choice is significant and will make a difference in the forth coming solutions. Several opportunities to develop more efficient products, quieter aircrafts using materials and manufacturing processes that will be more respectful of environmental considerations exist. The presentation will cover those elements and provide an overview of the upcoming solutions.

Jan 1, 2010

By R. von Gal

Hazelett Strip-Casting Corporation has been producing the Hazelett® twin-belt casting machines for copper casting since the mid-1960s. The first commercial casters were developed for copper alloy strip and anode plate. In 1968, development work was started to adapt the twin-belt caster for copper bar casting to be rolled in-line into wire rod. Since then, 36 casters have been sold as part of the CONTIROD® system for the production of a substantial portion of the world's copper rod supply. A unique feature of the twin-belt caster is the mold's ability to comply with the size and shape of the cast bar as it shrinks during solidification. Maintaining contact between the mold and the bar provides a high rate of heat transfer as well as other benefits, including the prevention of surface imperfections caused by remelting in the mold. This paper will give an overview of the continuous evolution of the twin-belt caster technology with an emphasis on recent developments in compliant mold technology for copper casting.

Jan 1, 2007

By O. Zach, K. Gamweger

"The Process of gas purging in molten Aluminium has been an industrial practise for many years. The melting of alloying elements and their rapid distribution in the bath is very important. To improve the mixing and homogenisation process, at RHI NON FERROUS METALS ENGENEERING GMBH a lot of CFD calculations were done. The so developed new ""purging program"" was tested at Alumino Catalan S.A., Spain. The results of the testtrials were very satisfactory and corresponds very well with the calculated data."

Jan 1, 2004

By M. Sabau

The Electrowinning Plant at INCO's Copper Cliff Nickel Refinery is a precious metals upgrading plant. The feed to the plant contains copper, nickel, cobalt, iron, significant amounts of precious metals and some impurities. Copper is the most abundant element in the feed. This paper describes the major equipment and process changes over the last twenty years, geared to improve the tankhouse operation, workroom environment and recovery of copper from the acidic solution. Copper is plated on to titanium blanks using explosion-bonded crossrods, animal glue as a levelling agent, and an organic surfactant for mist control. The installation of the stripping machine in 2001 required a number of changes: cathode and anode contacts were redesigned, flat bus bars were replaced with dog-bone type, spacer boards for cathodes and anodes were installed, longer anodes started to be used, and the plating cycle was extended from seven to fourteen days. A number of initiatives for improvement are being carried out. Explosion-bonded crossrods are being replaced with titanium-clad crossrods. The plan for the near future is to increase copper production by increasing current efficiency and current density. The possibility of lowering the iron concentration in electrolyte and changing the acid mist control method is being investigated.

Jan 1, 2007

By Juan Pablo Vielma

In this work we study how to incorporate risk control to the generation of ultimate pits when orebodies are modeled through a finite number of conditional simulations. To control risk we consider a chance constraint on the value of the ultimate pit. We incorporate this measure into the generation of ultimate pits by solving a stochastic programming version of the ultimate pit problem. We compare this stochastic programming problem to previous approaches such as generating the ultimate pit for each simulation and the hybrid pit approach introduced by Whittle and Bozorgebrahimi. We also study the effect of using different number of simulations in the generation and evaluation of ultimate pits.

Oct 1, 2009

By Grazyna Zakrzewska-Trznadel

The paper outlines the main objectives of the project that concern the evaluation of the possibility of uranium production from indigenous resources since Poland enters the nuclear program. The best available technologies are considered for uranium extraction and obtaining the yellow cake - U3O8. Liquid-liquid extraction with novel extracting agents, as well as membrane processes for separation of by-products will be tested in course of the project. The technological part will be completed with techno-economical analysis. Acknowledgement The studies were supported by the POIG project, No 01.01.02-14-094-09-00 ?Analysis of the possibility of uranium supply from domestic resources?.

Aug 1, 2010

By Joe Price

Canada?s energy future will increasingly depend on a supply of light, sweet crude oil derived from the Athabasca oil sands deposit of North-eastern Alberta. Billions of dollars are being spent on the construction of new and expanded mine and bitumen extraction plants, in situ recovery facilities, pipelines, upgrading installations and all the infrastructure needed to support these projects. The success of the existing operators has also inspired new players, anxious for ?a piece of the action? to come forward with exciting project proposals of their own. None of this investment and spin-off economic activity would be taking place today if events had unfolded differently in this part of the world some one hundred million years ago. The accumulation of sand in rivers, estuaries and in the near-shore marine environment created the great reservoirs that host the enormous oil deposits these projects are designed to exploit. Mine operators of all stripes will likely agree that there are few good ?geological surprises?. With specific reference to oil sand deposits, the geological history determines the distribution of sand, silt and clay bodies, which in turn controls the ore grade. Important design factors including everything from stable pit slope angles to tailings properties reflects events that took place millions of years before. An understanding of the sequence of events that resulted in deposition and preservation of the sediment and oil are important to sound design for both mining and in situ facilities. A geological history of the region is described. Site-specific examples from Syncrude?s operating mines are used to illustrate some of the geological factors that can present design challenges.

May 1, 2003

By Balmer Neilly

In these days of arrested prosperity, when patience is tried and the future but dimly outlined, Canada's gold mining industry stands out as a beacon light shedding its rays of hope and confidence and demonstrating that there is still one product unaffected by Customs barriers and eagerly sought by all the people of the world. Some other forms of industry have hesitated and side-stepped. Some have cried for help, and in spite of public assistance, generously extended, they are still unable to demonstrate definitely their ability to resume the onward march. But gold mining has never hesitated. As an industry, it has bad an unique experience. When prices are high and conditions are generally referred to as prosperous, this industry is adversely affected. The cost of production goes up; profits are diminished; public sympathy is lacking; and, thrown upon its own resources, the industry tightens up its belt and throws its whole energy into an effort to improve operating conditions, and offset high prices by increased efficiency. When, in due course, depression follows inflation and prices ebb, the gold miner, through necessity, finds himself physically and mentally prepared to meet the situation.

Jan 1, 1932

By Long Han, A. V. Kalinin, Xiujian Luo, Xiaobo Wang, Xiaoou Xia

"Inertia vibration crusher is a kind of vibration equipment which crushes ore by vibration. When the inertia vibration crusher works, ore between the two moving jaws is subjected to the high frequency contact force, which is produced by the two moving jaws with high frequency synchronous reciprocating motion. The synchronous motion of the two moving jaws depends on the self-synchronous feature of the inertia vibration crusher. To study the self-synchronous feature of the equipment, the dynamic model was established, in which relative parameters were taken into consideration. The kinematic coupling relations of the assemblies are discussed, and appropriate calculation method is chosen to solve the vibrating differential equation. Whether the two vibration exciter can realize synchronous operation depends on the ability of the vibration system's capture moment. Results show that though the two rotors’ motors and damping coefficients are different, and two jaws’ damping and stiffness coefficients are also different, as angular velocities of the two unbalanced rotors reach a certain value, the vibrating system can be stable. Their angular velocities tend to be equal, and the swings of the two moving jaws can be the same. The horizontal vibration and swing of the frame are large in a few seconds after starting the machine. When the system runs stably, the horizontal vibration and swing vanish, and the vertical vibration is stable. The study and its results can provide reference for the optimization design and parameter setting of inertia vibration crusher and related vibratory equipments.INTRODUCTIONMaterials can be easily broken by using the inertia force of the vibration exciter, which can effectively realize the selective crushing, reducing excessive combinations and the energy consumption, as introduced by Zhang in 2005. The initial micro crack between crystals in the material increases and new cracks can be manufactured because of the high frequency impact and the extrusion of the vibration crusher, so vibration crushing equipment can make it possible for any high strength brittle material to be broken theoretically. Inertia cone crusher and inertia vibration crusher have been successfully used in the treatment of metallurgical slag and construction waste, and it verifies the efficiency of vibration crushing."

Jan 1, 2016

By John Mair

The Ilimaussaq Intrusive Complex in south Greenland is a layered alkaline igneous body that is predominantly comprised of agpaitic nepheline syenites. The Complex is now recognized as containing vast resources of uranium in polymetallic ores that are also strongly enriched in rare earth elements (REEs) and zinc. Uranium and REEs are dominantly hosted in phosphate minerals with a minor proportion hosted in zirconium silicate minerals. Equivalent ores are yet to be mined for uranium anywhere in the world; however, studies are well advanced in confirming a process route to economically extract uranium. The Ilimaussaq Complex is considered the world?s type-locality for agpaitic rocks. Formation of the complex is attributed to four successive pulses of magma. The first produced an augite syenite, which now forms a marginal shell. This was followed by intrusion of a sheet of peralkaline granite. The third and fourth stages make up the bulk of the intrusion and are peralkaline to hyper-agpaitic in composition. The third batch of magma differentiated to produce pulaskite, foyaite and naujaite. Stage four produced the kakortokites and lujavrites, which are the units of particular economic significance. Kakortokites are strongly enriched in zirconium, niobium and tantalum, whereas the lujavrites are strongly enriched in uranium, rare earth elements, fluorine and zinc. Lujavrites are vertically zoned with arfvedonsite (black) lujavrites grading downward into aegerine (green) lujavrites. The upper most portions of the black lujavrites contain uranium concentrations of greater than 450 ppm, which decreases toward green lujavrites where uranium concentrations rarely exceeds 200 ppm. Resources defined to date in accordance with the Australian JORC code include 282 M lbs of uranium oxide at a grade of 280 ppm. With scope for several other similar sized resources within complex, the overall potential resource is of immense global significance. Metallurgical studies to date indicate that uranium can be successfully extracted from black lujavrites via an alkaline pressure leach method. This involves selectively leaching uranium with solutions containing carbonate and bicarbonate at elevated temperature and pressure. Uranium can then be recovered by hydrogen reduction to create a uranium oxide product. There is also scope to beneficiate ores as uranium and REE?s are hosted in specific mineral groups. Phosphate minerals can be effectively concentrated by froth floatation and uranium-bearing silicate minerals can be concentrated by gravitational methods. Studies indicate that REEs can be extracted from the residue following the alkaline leach process by a dilute hydrochloric acid wash, with REEs then precipitated in the form of a REE concentrate.

Aug 1, 2010

By W. G. McBride

INTRODUCTION Preparation of this article, at the request of the Committee on papers, has been undertaken in the hope that it may stir up helpful discussion and constructive criticism. The Canadian mining industry is in the dumps and there is no use trying to deny the fact; nor does it help to say that other industries are in as bad or a worse condition. Let us face the situation honestly and see just how serious it is. The entire financial and industrial world is in a state of depression. The gravity of the case is no doubt exaggerated by contrast with the wave of optimism and false prosperity which pre-ceded it. The prevailing gloom and pessimism are just as irrational as was the former super-optimism. As far as we mining engineers are concerned, the causes are quite beyond our control, and it is the effect upon our own industry which interests us most. This effect is an accumulation of mineral products with consequent depression in price to a point where profits have almost, if not quite, disappeared. Whether this accumulation of stocks is the result of over-production or under-consumption is difficult to say, but it would seem likely that there is a combination of the two. The introduction of selective flotation has brought about a large increase in the production of zinc, a moderate increase in the production of lead, and a comparatively small increase in copper. It has turned relatively small mines into great producers, as in the case of the Sullivan, revived expiring mines like La Cananea, and brought-in new ones like Flin Flon

Jan 1, 1931

By H. Nouranian, M. Askari

GOLGOHAR Mining & Industrial Co., with annual production of 16 million tons, is one of the largest pelletizing and iron ore supplier in Iran that recently this year, because of using mineral processing techniques and extraction of ore body positioning between the metamorphic rocks, about 150 million tons of dry tailings has been created as a result of concentrate production. On the other hand, many environmental issues such as groundwater pollution have been developed by sulfide and silicate gangue minerals, which containing heavy metals such as mercury and arsenic. In this study, a new product with high added value has been introduced for the company by identification and extraction of industrial minerals in dry tailings. Also, by removing large masses of dry tailings, environmental pollution sources were gradually eliminated. This method can be used as a modern waste management approach in the world.

Jan 1, 2017

By Primak. George J.

"In the development of a new product as well as during its introduction on the market, it is very important to give due consideration to problems involving patents, licenses and trade marks. At the very beginning of the research and development program, it is obviously essential to ascertain, through a suitable patent search, that the product in question will not infringe any patents which are still in force. Then, a possibility of achieving one's own patent or proprietary position on the product or the process of its manufacture should be carefully explored. Licensing arrangements that one may reach with respect to patents and know-how covering such new product may, in the final analysis, determine its over-all success or failure. If one can count on licensing revenues or some favourable cross-licensing arrangements with respect to a newly developed product, this may go a long way to achieving profitability and success. The selection of a good trade mark is probably one of the most important acts that one has to perform once the product is developed, as customers will identify the new product by such a trade mark. In many instances, successful marketing and widespread acceptance of a product are largely due to its appealing name or trade mark, accompanied by proper promotion and advertising. Once the trade mark has been adopted, it should be registered in the Trade Marks Office to provide the protection afforded by federal statute. If the product is to be manufactured, sold or licensed in some other countries, similar considerations should be made with regard to each such country."

Jan 1, 1973

By Liu Tao, Wang Wei, Liao Wenjiang, Yang Weiyan, Tang Bin

Side-blown Furnace technology is a developing technology and was developed very quickly in China in recent years, dozens of reference smelters can be found for the treatment of copper concentrate, copper slag, Lead slag, zinc leaching slag and different kinds of slurry. This paper introduces the working principle of the technology, displays the innovations and specifications of China Nerin's SBF technology, gives examples of the typical reference smelters, and looks ahead to future applications. INTRODUCTION Side-blowing furnace smelting process The side-blowing furnace smelting process (SBF process) is one of the bath smelting process with independent intellectual property rights of China Nerin. This process was originally applied to treat copper concentrate and high-lead slag. The SBF process includes two categories, i.e. to treat copper concentrate and to treat industrial solid waste. Up to now, the SBF process has been applied in around 5 million tons of copper concentrate processing capacity and 20+ plants with high-lead slag reduction process. In recent years, SBF process has been gradually used in zinc leaching slag, electroplating sludge, industrial solid waste (e.g., various metallurgical slag), and electronic waste disposal. The basic principle of SBF process is that the material to be treated is directly charged to bath through charging hole with crushed coal and flux, then, enriched oxygen air would be sent to slag level (Vanyukov/Jifeng style furnaces)or matte level (Baiyin style furnaces) via primary tuyere. In this case, the material completes matte/slag metallurgical reaction of gas-liquid-solid interaction under vigorous mixing, and separate matte and slag at the bottom of furnace hearth. With the help of secondary tuyere, the low-pressure air or enriched oxygen would be provided for secondary combustion in the freeboard. The core of SBF process is process parameter control and engineering design of SBF. Presented as a fixed rectangular type, the SBF is a metallurgical furnace consisting of copper water jackets and refractory material. The SBF is consisting of hearth, middle of furnace and furnace top with the sequence from bottom to top. The middle of furnace itself can be further divided into bath area and post-combustion area with primary tuyere and secondary tuyere at both sides. The furnace hearth is made of refractory bricks, which are fused and rebonded Mg-Cr brick, Mg-Cr brick and clay brick from inside to outside. The furnace top adopts a steel water jacket with charging hole and uptake shaft. The water-cooled partition wall is placed at uptake shaft and near charging hole.

Jan 1, 2019

By Damian Connelly

The option to leach iron from low grade copper concentrates could reduce transport costs and significantly improve the saleability of the concentrate. In addition, it reduces smelting costs and can remove undesirable impurities. The trend to produce cleaner and higher grade copper concentrates is very appealing to the smelters. A recent copper project came on line and there were three serious deficiencies which were not identified in the feasibility study. This came as a surprise and resulted in a number of projects to investigate ways of rectifying the problems in the shortest timeframe possible and using minimal new capital. The first serious issued not identified when commissioning was the lower than expected copper recovery, which was 70% compared to a predicted recovery of 80% to 87% in the feasibility study. This required investigating new flotation reagents and incorporating controlled potential sulphidisation. The second serious issue overlooked is the presence of significant amounts of talc minerals (insol) in the ore which are naturally floatable. This leads to lower concentrate grade and attempts to remove the talc resulted in lower copper recovery. Smelters have limits on the amount of talc in concentrate because it produces viscous slags and difficulties for the smelter. It also incurs higher transport costs. The third serious issue not identified in the feasibility study was the high arsenic reporting to the concentrate. Arsenic is a penalty element for smelters and at levels exceeding 0.3% the smelters may reject the concentrate. Arsenic is a problem environmentally for copper smelters and penalties apply when it is high. This paper describes the options for penalty element removal and suitability to incorporate into the modified flowsheet. It also highlights where the geometallurgy was not properly addressed and how these surprises could have been avoided. INTRODUCTION From 1970 to 1985, a copper company undertook metallurgical testwork on the Peruvian project copper ore. The ores were mined underground and treated over many years previously. Various other groups undertook studies and work until Aker Kvaerner undertook a feasibility study in 2006. Three ore composites were tested and grind-recovery relationships were developed. The feasibility study testwork identified that talc was a possible concern and will have an impact on copper concentrate grade. This was to be managed by blending. The current operating reality is that there is so much talc in the ore body it is not possible to blend it out. There was far more emphasis on molybdenum recovery. No mention was made of arsenic issues other than blending. There was a Concentrate Leach Study and a Molybdenum Hydrometallurgical Plant Study but these options did not proceed to a final flowsheet. A Scoping Study in 2006 looked at a Heap Leach project. The heap leaching gave very poor copper recovery on the sulphide ore. Heap Leaching was evaluated and tested for the high talc and high arsenic ore but recoveries were poor. The Aker Kvaerner feasibility study opted for a simple primary crush SAG/ball grind followed by flotation and sale of a concentrate. This is the current flowsheet utilised and the scale of the project is very large based on processing 117,200 tonnes of ore per day. A feasibility study does not guarantee success and the deviations from the feasibility study suggest there is a lot of technical work required to improve the current metallurgical performance.

Jan 1, 2019

By N. Schmalbein, L. von Ketelhodt, L. Kotelo

"The mining industry continues to remain challenged. Lower commodity prices, increasing labor costs and more importantly diminishing reserves are amongst some of the primary factors contributing to the difficulties faced. Ore sorting technologies have demonstrated their potential to improve the downstream beneficiation performance. The general processing route sees all primary crushed material milled for liberation and then processed in accordance with characteristics of the gold therein, i.e.: refractory golds would require direct leaching or oxidation whilst free gold would follow the conventional cyanidation process, after gravity concentration. Ore dilution increases the associated operating costs within each stage of this process. The opportunity to process the same throughput at a higher grade can only be achieved through pre-concentration. Sensor based sorting has been examined on numerous occasions by various gold producers. Test work carried out on different bulk low grade gold ores has shown the successful applicability of ore sorting to remove waste, whilst maintaining high recovery rates of gold. The results of a combined XRT/Laser sensor sorter have shown grade improvements of over 300% from feed grades of 0,25g/t to 1,15g/t at gold recoveries of 66% and waste ejection rates of 85%. This paper presents some of the results from the work undertaken by STEINERT with respect to gold sulphide ore sorting and presents a modelled financial scenario, which can enable a company to target and reclaim low grade ores.INTRODUCTION The mining and minerals processing industry presents with many different challenges including, volatile commodity prices, increasing labor costs and more importantly diminishing reserves. Conventional processing routes will continue to play a crucial role in the beneficiation process, however innovative methods of reducing operating costs and optimizing on the overall circuit performance is where technologies such as sensor based sorting come into the fore. Sensor based sorting as a dry mechanical process not only reduces water consumption by eliminating unnecessary waste but also reduces the requirements for reagents in the downstream processes. Sensor based sorting under dry conditions presents a highly efficient alternative to wet pre-concentration methods such as dense medium separation (DMS)."

Jan 1, 2017

By Mikael Ramström

In 2002 Atlas Copco Rock Drills AB released the new RCS technology for all of its drill rig types. RCS opened the way for a new generation of computerized drill rigs based on modern, standard PC-computer technology. Drilling accuracy, information logging and reduction in manpower in some types and serviceability, have all taken a quantum leap forward when compared with previous generations of drill rigs. The RCS (Rig Control System) is modularised and distributed is accomplished by means of CAN-bus technology. This technology, which is well proven in automobile applications, forms the communication backbone of the rig. The modularity facilitates almost unlimited possibilities for the expansion and adaptation of drill rig functions.

May 1, 2003

By Yong Kang, Bingyuan Yan, Dandan Zheng, Xiaochuan Wang, Dengfeng Su, Dongyang Li

"According to the characteristics of rock mass and the directional cutting technology of water jet, a new idea of light shock controlled blasting with water jet slotting was put forward. Based on the fracture mechanics theory and the stress wave theory, the mechanism of damping with water jet slotting was analyzed. On the basis of the above, the evolution law of the pressure wave and displacement field during the blasting were simulated by FEM software ANSYS/LS-DYNA. The result shows that: the oriented slot plays a good role in orientation during the blasting, and makes the energy generated by gas released by the explosives gather at the tip of the oriented slot, which makes it easier for the main crack to expand along the oriented slot and indirectly reduce the stress effect on the protected object. Meanwhile, the energy of the seismic wave is reduced while transmitting through damping slot. Finally, compared with the normal blasting with damping ditch, the maximum acceleration is reduced by 15.62%, the maximum velocity is reduced by 52.99%, and the maximum displacement is reduced by 68.32%. INTRODUCTIONIn recent years, with increasing demand for energy and space, an increasing number of underground projects have been under construction. Drilling-blasting method, as a traditional main method for rock excavation, is still an indispensable means in the engineering construction. As is known, blasting vibration will cause the deformation and unstable of the existing building structures, so how to reduce the influence on the existing building structures caused by the blasting vibration has become the focus. Traditional shock absorption measures mainly include three kinds: the first one is pre-splitting blasting, the second measure is to change the parameter of explosive filling, and the last one is to excavate damping ditch between the protected object and blastholes. However, engineering practices show that: the protected rock may be damaged in the process of pre-splitting crack construction by blasting, the second measure is difficult in operating, and the third measure is troubled by large work quantity (Song Guangming, 1999; Lou Jianwu, 2004; Lou Jianwu, 2005; Li Xibing et al., 2008)."

Jan 1, 2015

By Todd Kennedy, Kurt Tischler

"This paper presents the field experience of Siemens with regard to Gearless Drives in the mining industry … We consider the elapsed production hours of Siemens Gearless Drives to be extensive enough to provide a reliable estimation of availability calculated on the basis of data representing repair time, downtime, and operating time. The users of Siemens Gearless Drives confirm an availability of more than 98% after exclusion of some major issues. The paper addresses all of these major issues of Siemens Gearless Drives, describes successfully applied corrective measures, explains the influences on the design of the drives, and lists the downtimes associated with each of these issues. INTRODUCTIONThe first Siemens Gearless Drive in mining began operation in 1980 and was installed on an iron ore grinding mill. As of September 2011, 40 Siemens Gearless Drives will have accumulated 136,000 machine days of operating time. According to pure rules of statistical analysis, this accumulated operating time may be too low to be used for a sample of field data to provide precise statistical values of availability, however we consider it large enough to provide indicative values of worthwhile consideration. This paper deduces the availability statistics of Siemens Gearless Drives in the mining industry from information received from end users and factors in all major issues that Siemens has experienced with our Gearless Mill drives. This paper does not consider Gearless Drives in other industries such as the cement industry. The cement plants, especially in the northern hemisphere, interrupt production for several months in the winter. This lengthy downtime is used to maintain the complete plant including the mills, their motors and their drives. The mining industry has more stringent and higher production requirements. In the mining industry, production must run 24 hours per day, 365 days a year."

Jan 1, 2012