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By R. B. Berg

Montana sapphires were first discovered in alluvial deposits in the Helena area in 1865 and subsequently were discovered in other alluvial deposits in southwestern Montana and also in a lamprophyre dike at Yogo in central Montana. From about 1900 until the late 1930?s, when synthetic sapphire began to come into widespread industrial use, Montana sapphire mines produced large quantities mainly for watch bearings with lesser production for the gemstone market. The Yogo deposit is now mined for the gemstone market and two of the alluvial deposits are mined to produce sapphires for the fee-sieving of sapphire-bearing gravel and for the direct sale of gemstones. The generally pale-colored sapphires from the alluvial deposits in southwestern Montana are heated to enhance their colors whereas the generally blue sapphires from the Yogo deposit require no treatment. Markets for sapphires from both the alluvial deposits and the Yogo deposit are strong. In spite of reported historic production in excess of 70 tonnes, mineable resources appear to remain at most major deposits. Also abundant untested lamprophyre dikes in central Montana may host sapphires similar to those at the Yogo deposit.

Jan 1, 2009

By Alexander N. Winchell

"Location. The copper mines of Michigan are all in the northern part of that state on the Keweenaw Peninsula, which extends from the (Michigan) mainland for about seventy miles northeasterly toward the middle of Lake Superior. The mines occur in a belt or zone occupying the central portion of the peninsula from end to end.. The most productive mines for many years past have been those located not far from the city of Houghton in' the central part of the zone, in a section extending about ten miles southwest of Houghton and fifteen miles northeast. The most important mines in order of location, from the northeast to south¬west, are the following: Mohawk, Ahmeek, Allouez, North Kearsarge, Wolverine, South Kearsarge, Centennial, Calumet. and Hecla, Osceola, Franklin, Quincy, Hancock, Isle Royale, Superior, Baltic, Trimountain, and Champion. The first three named are in Keweenaw county and all of the others are in Houghton county. Still farther to the southwest are the Lake, Mass, Adventure, Michigan, Victoria, and White Pine mines. These are in Ontonagon county.History. The exploitation of these copper mines extends back into prehistoric times. There is little evidence that the American Indians carried on mining operations in this region in the period shortly before the advent of white men, but there is abundant evidence that the ancestors of the Indians, •or some earlier inhabitants of the region, carried on primitive mining operations. For example, Mr. S. O. Knapp, Agent of the Minne¬sota Mining Company, in the winter of 1847-48, made the first discovery of prehistoric mining. This event is described as follows by Foster and Whitney :"

Jan 1, 1920

By W. A. Heitbrink, J. D. Ashley, R. E. Gresh, J. A. Organiscak, A. B. Cecala

Many different types of mobile equipment used in surface coal mining utilize enclosed cabs to protect equipment operators. The overburden removal process is extremely dusty and can cause excessive exposure to respirable dust, especially crystalline silica. After equipment is used for years, many components of the enclosure deteriorate and its effectiveness is greatly reduced. This report discusses a cooperative research study performed on an Ingersoll Rand DM45E surface drill, retrofitted with a new Sigma pressurization and filtration system. Respirable dust concentrations were substantially reduced from 0.64 mg/m3 during pre-testing to 0.05 mg/m3 during post-testing with the new system, representing a 92% reduction in dust levels in the drill cab. This new system appears to be a very well-built and sturdy device, well-suited for the mining industry.

Jan 1, 2002

By David Jurich, Joseph N. McDivitt

INTRODUCTION South Coast Water District (SCWD) operates the Beach Interceptor Sewer Tunnel(BIST) in South Laguna, Orange County, California between Monarch Beach and Aliso Beach (Figure 1). The 10,200-foot long BIST houses a 24-inch gravity Techite sewer pipeline critical to the SCWD Sanitary Sewer Collection System. The original tunnel and sewer pipeline were constructed in 1954 and the sewer line was replaced in 1974.Periodic inspections by sewer pipeline maintenance crews documented deterioration of specific intervals of the tunnel. Rotting timber supports and rock falls in the tunnel as a result of the deterioration were endangering the sewer pipeline and a 731-foot section of tunnel located at Thousand Steps Beach was determined to be in immediate need of repairs. SCWD and consultants Hatch Mott MacDonald (HMM) and Tetra Tec prepared a Work Plan for emergency tunnel stabilization and pipe protection measures that was implemented in January 2007. Normal access to the beach and the section of tunnel requiring repairs was limited to public stairs referred to as Thousand Steps and, therefore, all materials and equipment needed for the work were transported to the beach by ocean-going landing craft. Additionally, the emergency repairs had to be completed without taking the pipeline out of service. Numerous environmental, logistical and operational requirements had to be overcome to complete the challenging emergency repairs. GEOLOGICAL SETTING The Laguna Beach area is located in the Peninsular Ranges of Southern California. The project area is located on the southwest flank of Niguel Hill along marine wave-cut cliffs and slopes. The tunnel was excavated in the San Onofre Formation, a marine deposit, characterized by abrupt lateral and vertical changes in lithologies that vary from boulder to cobble and gravel size breccias to medium coarse sandstones with gravel, sandy claystone and siltstone. The interval of the tunnel that required repairs is located within the San Onofre breccia, a moderately-to-well cemented, poorly bedded to massive unit with angular to subangular boulder and cobble sized clasts of schist. The sandy silt matrix of the breccia is composed of quartz, feldspar and schist grains (Figure 2). GENERAL TUNNEL DESCRIPTION The approximately 6-feet high by 6-feet wide 10,200-foot-long BIST was hand mined in 1954 at the base of the coastal cliffs. Primary access is through twenty-one access adits from public and private beaches. The tunnel is located in an easement that extends beneath private property with residential structures situated 50 to 80 feet above and horizontally in close proximity to the tunnel alignment. Most of the tunnel is horse-shoe shaped and unsupported, but approximately 3,000 feet is supported by timber

Jan 1, 2007

The Canadian concept for nuclear fuel waste disposal is being assessed by AECL Research in a series of experiments at its Underground Research Laboratory (URL) near Lac du Bonnet. Manitoba, Canada. As pan of this research, the Mine-by Experiment has been designed to obtain information on rock mass behavior, the development of an excavation-induced damage zone and failure mechanisms around a circular bored tunnel. An iterative design approach was used to effectively reconcile the experiment objectives and construction logistics. This paper discusses the design considerations and construction methodology adopted on the project.

Jan 1, 1991

By N. S. Kim

Silver paste including nano sized particles maintains conductivity in high temperatures without forming oxide layers. In the industry, printing process produces wasted silver paste inside the cylinder and on silk-screen. Pyrometallugical silver recycling methods have environmental problems and do not extract pure silver after removing polymer and organic materials during the extraction process. In this study a simple wet process, of recycling the waste silver paste, using ammonia, was conducted. Silver ion extraction yield was increased using oxidant in the ammonia solution. Possible extraction yields, such as pH, concentration, temperature of ammonia, oxidant concentration and the extraction time. The particles that were obtained after the extraction process will be used as porous hydrophobic catalytic and applied to AI mask and hydrophobic ink. Keywords: Waste silver paste; Ammonia; Hydrophobic porous support

Jan 1, 2009

By S. Boone, J. N. Shirlaw

INTRODUCTION Soft, near normally consolidated clays generally provide ideal conditions for tunneling using Earth Pressure Balance (EPB) shields. It is easy to turn the clay into a low permeability, viscous spoil that can be pressurized to maintain the required face pres-sure. Despite this, there are records of relatively large, and often quite variable, surface settlements over EPB driven tunnels in soft clay. To understand this variation it is necessary to identify the various factors that contribute to settlement. Tunnels in soft clay are ideal for study these effects in the field, as an unsupported void will close almost immediately, due to the low shear strength of the soil. In the short term, deformation in a soft clay will occur at constant volume, so short term surface settlements can be related to movements at tunnel level. In this paper, data will be used from EPB driven tunnels in Singapore marine clay. In all of the cases discussed the lining consisted of precast concreted segmental rings erected in the tail of the shield. The marine clay in Singapore has been studied, among others, by Tanaka et al.(2001). The clay typically has a plasticity index of 40 to 60, and the undrained shear strength (SU ) can be derived from: SU = 0.22 svo' where svo' is the current vertical effective stress. Figure 1 shows a summary of undrained strength/depth plots used for design on two sections of Singapore’s North East Line. The stability of a tunnel in clay can be assessed by comparing the stability number (N) of the tunnel with the stability number at total collapse (NTC). The stability number can be calculated from the equation: N = (?Z + q – Pt)/SU where: ? = the average unit weight of the ground above the springline of the tunnel Z = the depth to the springline of the tunnel from the ground surface q = the surcharge Pt = the support pressure within the tunnel The stability number at total collapse depends on the size, geometry and depth of the tunnel, and typically ranges between 5 and 9. Charts for assessing the number at total collapse are provided in Kimura and Mair (1981), based on the testing of model tunnels in a geotechnical centrifuge. For tunnels in the Singapore marine clay, the stability number of an unsupported tunnel would be over nine if the tunnel ois more than 8m deep. As a result, a support pressure

Jan 1, 2007

By Darrell Gillis

Recent accidents in the United States underground Coal Mines and the on-going carnage in Underground Chinese Coal Mines has shown the danger associated with the lack of communication infrastructures in an underground environment. The US Mine Safety and Health Administration (MSHA) have introduced legislation that states all Underground Coal Mines must have two-way voice and personnel tracking capabilities by 2009. If Coal Mining companies are being forced to deal with this problem Tunneling Companies will not be far behind. This paper will examine current practices and best case technology to deal with these issues.

Jan 1, 2007

? The economic health and national security of the U.S. depends on the continued availability of, and access to, reliable and affordable energy and mineral resources. However, America is hindered by a costly, inefficient and often redundant regulatory structure that thwarts domestic investment, expansion and job creation. The annual cost of federal regulations in the U.S. increased to more than $1.75 trillion in 2008; averaging $8000 per employee.(The Impact of Regulatory Costs on Small Finns, SBA, 2010) ? The complexity, uncertainty and delays within the current permitting system places the U.S. at a competitive disadvantage with many other countries that have both abundant mineral resources and a more welcoming business and regulatory climate. As a result, American and international mining companies often move overseas or across borders to invest capital, create local employment, and produce the critical minerals America must then import at higher cost, while sacrificing employment and economic stimulus. ? According to Behre Dolbear, the U.S. is ranked lowest globally due to the lengthy permitting period required before mine development can commence. (Where not to Invest, 2010).

Jan 1, 2011

By S. G. Malghan, J. P. Van Dillen

Introduction Some uranium minerals are paramagnetic and hence are amenable to concentration by high gradient magnetic separation (HGMS). This paper describes effects of the HGMS parameters-pulp velocity, field strength, matrix loading, and magnetic field gradient-on the product recovery and grade. Unsatisfactory separation of uranium minerals by HGMS is related to ore-specific properties, such as lack of liberation, fine dissemination of uranium minerals, uniform distribution of magnetic minerals throughout the ore matrix, and interference of fine-sized slimes. Experimental techniques to identify and resolve some of these problems are outlined. HGMS of Uranium Ores The mechanism by which uranium minerals are attracted to a magnetic field is either due to its magnetic susceptibility or its association with other minerals that are magnetic. Data on magnetic susceptibility of uranium minerals are scarce. The only reported data are for uraninite at 2360 X 10-6 cm3/mole. Povarennykh (Andres, 1976) concluded that the magnetic properties of minerals depend on: • Structure of the outer electron shell in a mineral with electropositive atoms; • Valence of the atoms; • State of the chemical bonds; • Type of coordination; and • Proportion of magnetic atoms (Fe, Mn, Cr, and Ni) in the composition of the mineral. However, information on the magnetic susceptibilities of the constituent atoms of a mineral alone does not suffice for evaluating the mineral compound as a whole. Most often, uranium minerals can be beneficiated by HGMS if they are associated with other minerals that are magnetic. This appears to be a more predominant mechanism by which the uranium minerals are beneficiated. Experimental A Sala-HGMS (Malghan and Subramanian, 1981), model 10-15-20, separator was used in the experiments. The matrix material-ferromagnetic stainless steel in the form of expanded metal or steel wool-was packed into a 38-mm (1.5-in.) diameter by 360-mm (14-in.) long canister. The matrix material occupied only a 150-mm (6-in.) length. The experimental set-up and slurry flow direction are described elsewhere (lannicelli, 1976). The response of uranium ores in the HGMS was studied by feeding well-dispersed slurry at 10% solids and examining the influence of process variables on selectivity and overall uranium recovery. The chemical and mineralogical characteristics of the ores under study are presented in Table 1.

Jan 12, 1983

By Ana Chiquini, Clayton V. Deutsch

The most common approach used in the mining industry for mineral resources modeling is to estimate the grades using ordinary kriging and report the recoverable resources based on this deterministic estimated model. Mineral resources calculated with kriging are a smooth representation of the actual distribution of grades and do not provide an assessment of uncertainty. Unlike kriging, simulation reproduces the variability of the grades in the mineral deposit and provides an assessment of uncertainty. Reporting mineral resources directly on high-resolution simulation results would assume perfect knowledge of the grade at the time of mining and selectivity at the scale of the data. There will always be uncertainty left at the time of mining, so assuming perfect knowledge of the grade in the future is incorrect. There are two concerns when geostatistical simulation is used for resources modeling: the information and the mining selectivity effects. A new framework for resource estimation is proposed with two separate modules to address those concerns. The information effect is accounted for by anticipating the additional production data that will be available at the time mining to guide the destination for the mined material. The mining selectivity effect is addressed by mimicking the grade control procedure to get mineable dig limits at a chosen selectivity, represented by a minimum mineable unit size. In addition to a prediction of recoverable resources that will be closer to the material mined in the future, the framework proposed provides an assessment of local and global uncertainty for risk management.

May 26, 2020

By Xiaodong Ma, Marek Pawlik

Introduction Guar gum is a natural nonionic polysaccharide. Guaran, the functional polysaccharide in guar gum is a chain of (1?4)-linked ß-D-mannopyranose units with a-D-galactopyranose units connected to the mannose backbone through (1?6) glycosidic linkages. The poly-mannose chain is randomly substituted with galactose units at a mannose-to-galactose ratio of 1.8-1.0 [1]. Cheng et al. reported that the molecular weight of natural guar gum is 1.935 • 106 [2]. Robinson et al. found that the molecular weights of five grades of commercial guar gums ranged from 4.4 • 105 to 16.5 • 105 [3]. Guar gum is frequently used as a depressant of naturally hydrophobic gangue minerals (e.g. talc) in the flotation of PGM-bearing ores, and according to Harris et al. a wide variety of modified guar gums are available for this application [4]. The Canadian potash industry utilizes natural guar gum as a blinder of water-insoluble slimes in the flotation of potash (sylvinite) ores, a process that is carried out in a saturated KCl/NaCl brine. The role of the polysaccharide is to prevent a primary amine collector from adsorbing onto these unwanted fine minerals. Hydrophobic interactions between basal cleavage planes and the polymer appear to be involved in guar gum adsorption on talc [5,6]. Liu and Laskowski stressed the importance of metal impurities on mineral surfaces that can serve as the active sites for polysaccharide adsorption [7]. This postulate was consistent with the later observation that, in addition to hydrogen bonding, the adsorption of guar gum onto talc was strongly dependent on the surface concentration of magnesium sites [8,9]. In this case the adsorption process was visualized as metal-polysaccharide complexation facilitated by the cis-configuration of the hydroxyl groups of mannose monomers. Hydrogen bonding and chemical interactions with metal sites were also suggested by Rath and Subramanian in their studies on guar gum adsorption on biotite mica [10]. In a recent study, Wang et al. demonstrated that hydrogen bonding is the main driving force behind guar gum adsorption onto talc [11]. Their data also show that the adsorption density of guar gum on alumina is about five times lower than the adsorption density on talc. Pawlik and Laskowski reported that the amount of guar gum adsorbed on illite was independent of ionic strength over a wide range of salt concentrations [12]. The adsorption density of the polysaccharide on illite did not measurably change with ionic strength from that of distilled water to about 50%-saturated KCl/NaCl potash brine (~3N KCl/NaCl). However, guar gum adsorption on dolomite dramatically decreased over the same range of ionic strengths, and no reliable explanation of that phenomenon was proposed [12]. The water structure-breaking or structure-making capabilities of background ions are usually ignored when discussing adsorption mechanisms of polymers. The concept of “structure breakers” and “structure makers” was first introduced by Gurney, and Frank and Wen who postulated that each ion is surrounded by three distinct regions of water structure [13,14]. In the first layer, water molecules are tightly bound to the ion. The second region extends farther away from the ion and is referred to as the region of structure breaking. Only at larger distances, where the ionic field is weak, water molecules form the “normal” ice-like structure. It is also now recognized that the first layer can be further divided into the primary and secondary hydration shells. Small, strongly hydrated ions reinforce the “normal” structure of water and the region of structure breaking disappears. In contrast, large less-hydrated ions disturb the ice-like structure and generate an extensive region of structure breaking. Experimentally, these two effects can readily be distinguished through viscosity measurements. Increasing concentrations of structure-breaking ions result in a decrease of the viscosity of aqueous solutions. On the other hand, increasing amounts of structure-makers significantly reduce the viscosity of water. Alkali metal cations form a sequence known as the Hofmeister series. The Hofmeister series - Cs+, K+, Na+, Li+ - orders the cations from the least hydrated to the most hydrated. Based on literature viscosity data for aqueous

Jan 1, 2005

By G. Récoché, A. Chamaret, M. O’Connor

Building indicators that respond to all stakeholders' needs is a time-consuming and complex exercise, with certain questions still unsolved. The aim of the current three-year research project, carried out in partnership between BRGM’s Mineral Resources Division and C3ED, is to propose a top-down / bottom-up indicators building methodology that combines conception and coordination methods and a participative approach. The tool-design phase is based partly on a comparative analysis of existing international initiatives according to different criteria (objective, observation scale, framework, etc.). The study of two African mining projects will provide the opportunity to confront the conceptual aspects with reality in the field. Careful consideration of the participants’ suggestions will result in a set of indicators that can be easily understood and adopted by all stakeholders. The final objective is to measure the impact of a mining site on a local, regional and national sustainable development frame, throughout the full life cycle of a mine.

Jan 1, 2005

By H. Lyn Bourne

This is the fifth annual tabulation of mineral royalty information. This tabulation, like the previous editions, includes all of the earlier data. There are also 60 new entries. In addition to royalty information, some entries show the cost of purchased reserves. Two articles relative to the evaluation of minerals reserves appeared in December, 1986. R.H. Paschall (In the Aggregate, ME, p 1139) wrote a good article, although it lacked specific royalty data. However, this author takes exception to two ideas in Paschall's column. Paschall contends that the royalty rate does not affect the mineral appraisal. This present author could not disagree more. Paschall also claims the location of an industrial mineral deposit is the only serious or practical caveat in comparing royalties. Comments received here from readers helped make the list of caveats that are cited each year. The readers will decide which factors influence the mineral value for their commodities of interest. Paschall's point about the relationship of the parties who are negotiating a royalty agreement is important and very well taken. The other article, written by William Vernon (Pit and Quarry, December 1986), gives a step-by-step process on how to conduct a mineral appraisal. The article cites three reasons for an appraisal: transfer rights; collateral for a loan; and taxation. A fourth reason is to establish adequate compensation for reserves lost through condemnation. This author has appeared in several court cases where compensation for loss of mineral reserves through condemnation required a mineral appraisal. Royalty rate becomes an important factor in the appraisal process, although the Pit and Quarry article refers to that part of the valuation equation as "profitability." Both articles were well written and are recommended reading for those interested in mineral valuations. The same caveats that have appeared in previous columns relative to factors that influence the value of reserves are restated. The data in the table serve as a general reference and are not intended to present an absolute scale of reserves costs. Several factors influence the value of any mineral commodity. The factors include: • location/transportation - especially significant for most industrial minerals; • market conditions both for the commodity and the company acquiring the right to mine; • quality or grade of the deposit as it reflects the amount of processing/beneficiation necessary to produce the finished product; and • legislative restrictions and conditions for mining a given material at a given site. These and other factors will significantly influence the cost of reserves. The table shows the range of royalties and the variations in the basis of computing the fees. In a few instances, it gives the cost of acquired reserves based on purchase price and quantitative estimates of the material in place. The table lists the commodity in column 1, and the subsequent columns give: • the location by state, US geographic area, or Canadian province ; • the cost - R for royalty and P for purchased cost; • the year in which the lease or purchase agreement occurred; and • comments or footnotes for more information. The cost column requires more explanation. The units may refer to cubic yards (/cu yd), cubic feet (/cu ft), short tons (/T), or acres (/A). 1 cu yd = 0.76 M2 1cuft = 0.28m3 1 st = 0.9072 t 1 acre - 0.4047 ha or m2

Jan 7, 1987

By David S. Yang, Osamu Taki

The innovative Soil-Cement Mixing Wall Technique, developed independently in Japan, consists of mixing in-place soils with cement grout using multi-axis augers and mixing paddles to construct overlapping soil-cement columns. The applications of overlapped soil-cement columns include cutoff walls for groundwater control and structural diaphragm walls for excavation support. The special features of this technique include water tightness, versatile strength design, and efficient installation in subsurface materials varying from clayey soils to cobbles or soft rocks. Through the introduction of two recent subway projects in Japan, this paper presents the design parameters, construction procedure, quality control and performance of soil-cement wall for excavation support and groundwater control.

Jan 1, 1989

In February 2001, Kalgoorlie Consolidated Gold Mines (KCGM) commissioned its first full-scale ultra fine grinding (UFG) plant to supplement existing roaster concentrate treatment capacity. This process involves the fine grinding of refractory pyritic concentrate to 10µm, followed by direct cyanide leaching for the recovery of gold. By this means gold is economically extracted from the concentrate without the need to first oxidise the host pyrite. This paper details the history of the project from initial laboratory testwork comparing possible treatment options, to current performance of the 12 tph plant. This includes the cost comparison of the major treatment options, the laboratory and pilot scale UFG performance, the UFG mill selection, cyanide leaching of UFG product, commissioning and plant performance to date.

Jan 1, 2002

By James D. Bliss

Sedimentary deposits of pluvial Lake Bonneville are an important source of sand and gravel suitable for aggregate and construction in Utah. Data on Lake Bonneville basin sand and gravel deposit thickness, volume, grain size, percent of fines, and durability were statistically analyzed to detect variations associated with geologic domains, geographic location, Lake Bonneville shorelines, and sand and gravel deposit type, and to construct quantitative deposit models. Analysis showed several trends; (1) sand and gravel in younger shorelines was slightly more durable and the deposits considerably larger in volume, (2) younger shore- lines are also more likely to contain more than one genetic deposit type, (3) the volume of terrace deposits is larger than beach deposits, (4) terraces and beaches are generally thicker than spits and bars, (5) the northern part of the Bonneville Basin contains slightly more durable sand and gravel than the southern part of the basin and is more likely to contain deposits composed of more than one genetic deposit type, aid (6) the Wasatch domain deposits are composed of more than one genetic deposit type more often than deposits of the Basin and Range domain. Three additional conclusions with immediate economic significance are; (1) the median sand and gravel deposit in the Wasatch domain, 360,000 m3 (275,000 yd3), is three times larger than that of the Basin and Range domain (120,000 m3 [90,000 yd3]), (2) the median deposit thickness in the Wasatch domain, 5.8 m (19.0 ft), is nearly twice that of the Basin and Range domain (3 m [lo ft]), and (3) the Wasatch domain also contains slightly larger diameter gravel. These three conclusions are significant because the trend for sand and gravel development in the Bonneville Basin is to move from the Wasatch domain to the Basin and Range domain. Smaller, thinner deposits with smaller diameter gravel will require more surface area to mine than would have been necessary in the Wasatch domain. The result is a higher cost for sand and gravel in construction projects in the Salt Lake City area, especially since the gravel must also be hauled farther.

Jan 1, 2001

By P. C. Fletcher, E. Kaya

The Bond grindability testing procedure has been standardized to measure the same grindability values, i.e. Bond work index (BWi), for the same ore when tests are performed in different laboratories or by different operators. This is accomplished by the standardization of mill dimensions, tumbling speed, grinding ball charge weight and distribution, sample ore charge weight in the mill and operating practice. The results of this investigation reveal that the Bond work index grindability values may differ substantially with different standard Bond ball mills. This paper will review the results.

Jan 1, 2002

By R. P. Stahura

Conveyors are the lifeline of mining and processing operations. They continuously supply materials to and carry finished products and waste away from operations. When conveyors are running at less than maximum efficiency, the operation's productivity is in trouble. Inefficient conveyors suffer carryback, leading to the buildup of materials on idlers and other expensive components. They spill and leak material at loading zones and conveyor transfer points. This causes accumulations that can damage the belt, wear moving components and increase both clean-up labor and maintenance expenses. They wander or mistrack, spilling material and endangering personnel and conveyor components. And through these inefficiencies, they multiply the operation's hidden costs. These added expenses occur in lost production, increased downtime for service and maintenance and replacement costs for prematurely worn equip¬ment. In addition, the attitude that inefficiency is "good enough" is recognized elsewhere in the organization. As a result, other departments relax or operate at less than peak performance. Quality goes down along with employee morale. Costs of inefficient conveyors A key to efficiency is handling a product as few times as is necessary. That means conveyors should be loaded, track true to the unloading point and then be unloaded, all without material escape or waste motion. An inefficient conveyor is often signaled by accumulations of DURT - material that has escaped from the system and is now at large in the plant. This DURT adds costs to an operation that are uncounted and, perhaps, uncountable.

Jan 1, 1992

By N. S. Kim

Economically favored Cr and Cu leaching out process from spent power plant fly ash (PPFA) had been investigated. PPFA, bearing of C, S, V, Ni, Cu and Cr, has been widely used as an assistant fuel in cement industry. Recent environmental regulation in S. Korea prohibits using PPFA as a fuel. Many researchers have also studied on extraction V and Ni from PPFA. Due to low concentration of V and Ni, 2% and 1%, respectively, economical and environmental friendly process could not be found. In this study, Cu and Cr have been removed in an economical way and which satisfied with KS Extraction Test. The rest unburned carbon, V2O5 and NiO2 in residue were found to be applicable for indoor and outdoor colored bricks or deodorant panel. Various parameters such as pH, lixiviates and time on leaching behavior were investigated in order to leach Cr and Cu remaining C, V and Ni. Keywords: Fly ash; Selective extraction; Ammonia; Deodorant panel

Jan 1, 2009