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By J. Drelich, J. Pletka

Lost foam casting is a process in which a polymeric material is formed into the shape of the part to be cast. Parts that are more complex are fabricated by simply gluing several patterns together. The pattern is then coated with a refractory material consisting of a mineral mixture and binders. Finally, hot metal is poured into the pattern, evaporating the expanded polystyrene and taking the shape of the coating shell. Prior to casting, a significant number of the patterns are damaged and inevitably landfilled. In this study, a process was developed for the recovery of expanded polystyrene from the coating and glue contaminants. The process consists of shredding, impact comminution, size classification and pneumatic separation. It is successful in separating up to 97% of the contaminants, while recovering 95% of the polystyrene. Key words: Casting, Lost foam process, Expanded polystyrene recovery

Jan 1, 2003

By James C. Bradbury

Tripoli is a naturally occurring, finely divided form of silica found chiefly in midwestern and southeastern states and used commercially in fillers and abrasives. The name comes from the location of a silica deposit in North Africa and was applied in the latter part of the 19th century to similar material near Seneca, Missouri. Subsequently, the North African material was found to be diatomite, composed of siliceous skeletons of microscopic marine plants called diatoms, and the material's name was changed to tripolite. The name, tripoli, remained with the Missouri silica, which is inorganic in origin, and tripoli is now used to designate all naturally occurring silica that is similar in characteristics and origin to the Missouri material. Just to confuse things further, in commercial trade tripoli usually designates silica from the Missouri-Oklahoma field, whereas silica from southern Illinois, the other major producing area, is called amorphous silica. Each term, however, may be used commercially for any material, regardless of place of origin that has the characteristics or uses ascribed to material from either major producing area. For example, Engineering and Mining Journal routinely lists under "tripoli," prices "f.o.b. Elco, I11." and "f.o.b. Seneca, Mo. and Rogers, Ark.", and under "silica, amorphous," prices "f.o.b. I11 and "f.o.b. Dierks, Ark." "Soft silica" is another term that has been applied to tripoli from Illinois, west central Arkansas, and Tennessee, presumably to distinguish it from the more compact Missouri material. It has also been used in the ceramic trade to distinguish tripoli from "hard" silica, or silica flour, which is produced by pulverizing silica sand. Tripoli is produced mainly in extreme southwestern Illinois, in the Missouri-Oklahoma district in Newton County, Missouri, and Ottawa County, Oklahoma; and in the novaculite belt of west central Arkansas. Some tripoli is produced for local and specialized uses near Austin, Texas.

Jan 1, 1980

By Geoff Beale

In terms of their hydrogeology, most open pit mines can be divided into three categories. There are mines that occur above the water table, mines that extend below the water table in high permeability rocks and mines that extend below the water table in low permeability, tight formations. Mines that occur above the water table do not experience major ground water seepage. It may some- times be necessary to construct in-pit trenches and sumps to remove water from precipitation. But dewatering or enhanced drainage measures are typically not required. Open pits that extend below the water table in high permeability rocks find it cost-effective to pump from dewatering wells. This is done to lower the water table below the working pit floors, creating dry or depressurized conditions in advance of mining. If the rocks in the mining area are homogenous, complete drainage of the entire mining area may be achievable by pumping from wells. In this case, it is not necessary to consider drain- age enhancement. However, there are many open pits and excava- [ ] tions that can lower the water table using conventional wells, but for which drainage enhancement is also an integral part of the dewatering system. The Sleeper Mine in Nevada is an example of this. Hydraulic layering at Sleeper has prevented downward drainage of water as the main water table is lowered. In addition, there are many mines that have areas of low permeability wall rocks that do not freely drain as the surrounding water table is lowered. Ground water seepage also creates difficulties in mines that occur below the water table but for which lowering of the water table using conventional wells is not feasible because of the overall low permeability of the rocks. The volumes of water involved may be small. However, it is necessary to deal with all of the water inside the pit as mining proceeds. It is not possible to dissipate pore pressures in the wall rocks in advance of excavation.

Jan 1, 1997

By Edmund J. Flynn

My subject Is Industrial Relations. Thus, I may appear as an intruder at this annual meeting of the Society of Mining Engineers. But I am no more an intruder here than is Industrial Relations in the day-to-day functioning of an engineer either in a staff or a line job. Engineers deal with people, as well as with blueprints, organizational charts, production data, etc. Where you have people, you have emotions, gripes, wants - real or imagined. Or you may just need some people or, at the other end of the pole, you may want to free yourself of people. But whether it is the wants or the needs, the pleasant or the unpleasant aspects of dealing with people, an Industrial Relations Department within an organization is there to help with these human relationships. This is the point for a definition of terns. Reference has just been made to "dealing with people? and to "human relations." This is, precisely the area in which Industrial Relations operates in the western Mining Divisions of Kennecott. In other organizations, what we refer to as Industrial Relations, may be called personnel relations, personnel administration, employee relations, or labor management relations. In our opinion the term Industrial Relations is best descriptive of the activity because it embraces the broad field of human behavior, reactions and satisfactions growing out of an individual?s entire employment relationship including his hiring, his lifetime on the job, and his termination. This is an individual?s industrial life. However, despite the use of the word "industrial", we are ever conscious that Industrial Relations is limited to human relations. Operational activities and decisions relating to the mining, milling, smelting and refining processes are for the line organization. The Industrial Relations interest in these line organizations activities and decisions relates only to the impact they nay have on employees - on people generally within the organization.

Jan 1, 1959

"INTRODUCTION Foam, unless intentionally created, in any industrial process presents operational problems, or at a minimum, is a nuisance. Some foam problems are unique to a given industry and others are common across many industries. A few problems foam presents to any particular industry are: (a) Poor Housekeeping, (b) Environmental impact, (c) Safety Hazards, (d) Slower Production Rates and, (e) Reduced quality of the end product. Defoamers address these issues. Sadly, the assumption in most industries is all defoamers are alike. In reality, a lot of chemistry is involved in the manufacture of even the simplest defoamer sold today and rarely are any two defoamers “just alike”. Today’s defoamers can include polymer chemistry, fatty esters, alkoxylated alcohols, silicone chemistry, silicone surfactants, ethoxylated and propoxylated block polymers, and a tremendous amount of emulsion chemistry just to name a few. This paper will discuss the various types of defoamers, defoaming mechanisms, the advantages and disadvantages of defoamer selections, and how to choose the proper defoamer for your application. Before a discussion of defoamer can be brought about, foam generation and composition must be discussed. WHAT IS FOAM? Foam is a colloidal suspension of a gas dispersed in a liquid. Most often foam consists of air dispersed in water. If a stream of air is introduced into a liquid, the bubbles produced assume a spherical shape. As the density of the bubble is less than the liquid the bubble rises. When the individual bubbles reach and pass through a surfactant free liquid they collapse. Air from the bubble dissipates and the liquid previously surrounding the bubble flows back.It should be noted a pure liquid will not foam. In the case of air dispersed in water a surfactant is necessary to make the water support a stable foam. A surfactant is a term used to describe a surface active agent; a compound with a hydrophilic end and a hydrophobic end on the same molecule."

Jan 1, 2016

By Carl-Eric Dr. Nilsson

Energy cost for mine ventilation in Sweden is high, especially during winter time when air must be heated. This paper presents the result from a project entitled ventilation-as-required. The term ventilation-as-required means that the required volume of fresh air should be distributed only to such areas, where mining work is going on and to be reduced to a minimum in the rest of the mine. Ventilation-as-required is a monitoring system that controls the operation and capacity of the fans and measure the air pollutant gases, i.e. carbon monoxide, nitrogen and sulphur dioxide at strategic points. It is an active system that responds when equipment is under operation. MITU proposed in 1991 a project to develop a ventiation-as¬required system and such components as transmitters and receivers for the communication between the equipment and the fans. The mining companies, Boliden Mineral AB, LKAB, Outokumpu and Ammeberg Mining Corporation joined the project and have financed a joint research and development programme supported with a grant from the Swedish Government through NUTEK. MITU proposed a second project in 1992 to the mining companies to develop an improved "intelligent" fan for scope ventilation. Boliden Mineral and LKAB joined the project and have financed a joint research and development project supported by the Swedish Government through NUTEK. The Government even made a commitment to support the investment of the first 50 fans ordered with a grant of 25% of the investment cost. The result from projects show that the target set up in the plans is more than achieved, with an energy reduction that exceeds 30% compared to previous consumption. No environmental influence due to reduced ventilation is observed in the stope when work is under progress. Dilution of exhaust gases from diesel fuel decreased from 6.000 m3/L consumed diesel fuels to 3,600 m3/L. The automatic data processing and sensor system is even increasing the security of the work so that it can be done under safer environmental conditions.

Jan 1, 1995

By G. S. Adisoma

To address the problem of grade estimation in a general three-dimensional shape and the uncertainty associated with the estimate, the technique of jackknifing/block kriging short-cut is proposed. A new estimator called jackknife kriging is introduced first. Through the jackknife variance, a confidence limit for the reserve grade estimate can be calculated. Unlike the kriging variance, which is more a measure of data configuration and is independent of data values, the jackknife variance reflects the true variability of the data. This approach provides a simple way to set a confidence level for global estimation of resources.

Jan 1, 1995

By F. L. Pirkle

The mineral zircon is mined for use as specialty foundry sands, abrasives, ores of ZrO2 and zirconium metal, refractories, and zirconium chemicals. It is produced as one of several products from heavy-mineral sand deposits associated with fossil shorelines. Because of its low coefficient of thermal expansion, its high melting point, its high refractive index, and its chemical inertness, it is an attractive refractory material. Zircon varies from deposit to deposit in terms of grain size, grain shape, and chemical impurity. Thus, there is a wide range of commercial products differing in impurity levels, particle shapes, and grain sizes.

Jan 1, 1992

By Jean-Michel Rendu

Accurate modeling of the semivariogram is an extremely important step in the geostatistical analysis of mineral deposits. Automatic fitting of a mathematical model is often possible but not necessarily desirable. Significant geologic and statistical information must be taken into account in the fitting process, which is not always available to the computer. Manual fitting of the model is, on the other hand, extremely time consuming. Interactive graphics are best suited to optimize the process. A number of interactive methods are described, which are adapted to the modeling of semivariograms in one-, two-, or three-dimensional environments.

Jan 1, 1982

By C. W. Overton

The operations of Bethlehem Copper are situated in the south-central interior of British Colombia at an elevation of 4900 feet above sea level. Main road and rail transportation systems pass through Ashcroft in the Thompson Valley, which is 28 miles by road from the minesite. The operation was the first low-grade open-pit porphyry copper mine in British Colombia. The minerals are chiefly chalcopyrite and bornite, while the rock is principally feldspar and quartz. In the outer fringes of the orebodies sane pyrite is present. Average grade of mill feed is 0.55% copper.

Jan 1, 1973

By F. J. Sotillo

Mineral processing requires good classification of particles to attain an adequate separation of minerals. This is of utmost importance in the case of sulfide minerals. An ideal classification is obtained when particles are separated at a given mesh, which is fixed according to the characteristics of each sulfide ore. Under these ideal conditions, particles coarser than the mesh of separation are recovered in the underflow, whereas particles finer than the mesh of separation are recovered in the overflow. This paper presents the results of pilot plant tests that were performed on Ag-Pb-Zn and on Ag-Au Peruvian sulfide ores using a Density Separator, and the comparison of these results with those obtained using hydrocyclones, under similar operating conditions. The results show that the ratio of circulating load is reduced by 50% by using a Density Separator with respect to that obtained by using hydrocyclones. Moreover, the effect of the improvement in the separation efficiency obtained by using the Density Separator on the kinetics of flotation is also shown. Silver recovery of the Ag-Pb-Zn ore increased by 18% whereas gold grade in the concentrate of the Ag-Au ore is doubled.

Jan 1, 1998

By Rod Heath

The Saskatchewan industry has the advantages of an ore body of a size and consistency unmatched anywhere else in the world, and large, efficient mines with production costs that compare favourably with those in other countries. On the minus side, Saskatchewan is remote from most major markets, and producers face a distribution challenge to reach the offshore markets which is the main focus of this presentation. One of the characteristics of the world potash business is that all of the major sources of production are located in the developed areas of the world, while there is no significant production in any of the highly populated developing countries. The major potash producers are located in Canada and the United States, in West Germany, France, Spain and the U.K., in Russia and East Germany, and in Israel and Jordan. There is currently no significant production in any of the countries in Asia (with the exception of Jordan where a plant is currently in the start-up phase), Africa, Latin America or Oceania, and all of these areas must, therefore, import a11 of their potash requirements from the producing countries.

Jan 1, 1985

By B. C. Lewis

When John F. Kennedy made this statement, I am sure he was not thinking about the valuation of limestone reserves. However, it is certainly applicable. The objective of this paper is to demonstrate how the discomfort of thought (i.e., the analytical and methodical process performed by a reputable professional) builds the foundation for an opinion that provides assurance as to the value of a property. In its final form, a valuation is nothing more than an opinion. The credence of that opinion is directly proportional to the knowledge of the appraiser and the efforts and judgment extended in developing said opinion. Presented herein are the methodologies for formulating a defensible opinion. Before detailing the valuation process, an overview of the limestone industry is presented along with some historical parameters relating to the industry. Secondly, the most widely used valuation methodologies and a brief discussion of each are presented. Two case studies are then presented, which review actual valuation studies. The paper concludes with how the valuation process should be published in a report format that is defensible from a legal standpoint, bankable from a financial standpoint, and decipherable from a layman's standpoint.

Jan 1, 1989

By Edwin H. Bentzen

Talc, as a mineral, is rather widespread, but as an ore sultable for mining, it is rather limited. Materials sold as "talc" range from the impeccable white material from Italy to a gray-green-bluish material from Virginia. Some uses of the material called "talc" seem to be determined by the color of the material, some by the chemistry of the material, and some by the particle size of the ground material. But, there seems to be some overlapping of criteria used to judge the acceptability of a raw material. So then, any producer of talc material that is not a consumer of this raw material is faced with the age-old problems: "what do I call the stuff, and to whom should I try to sell it?" The answer to the first part is easy: if you want a high price, call it "talc"; if you want a low price, call it "soapstone". This may seem like a very simplified answer, but it is apparent that some of the products sold as "talc" have more than a minor amount of impurities in them; whereas, if they were called "soapstone", these same products would probably get a lower price.

Jan 1, 1973

By M. P. Meehan

The purpose of this paper is to present the key elements in a system; study of the electrical system for a timing and/or tilling operation. The ability of an electrical system to function in a reliable fashion at its proper levels is essential for an operation to be successful. A system study consists of a load study for determining the capability of the electrical network to provide power to the various loads and a short circuit study for determining the capability of the electrical protective equipment to properly protect against fault conditions. The sequence of events in a system study is data acquisition, determining the electrical parameters and analyzing the ability of the system to meet these requirements. If the system is small, herd calculations will be the manner in which the study will be conducted; if it is large then commuters will be used. A load study has as its objectives the determination of the capability and reliability of the source of power, transformers and conductors to satisfactorily deliver power to the loads at an acceptable voltage level. The Information required is a single line diagram showing the source, transformers, conductors and loads.

Jan 1, 1980

By Todd L. Hollingsworth, Jeremy K. Hobbs

In 2001, the Radomiro Tomic Mine located near Calamq Chile, added a tertiary crushing facility. An 84" wide mobile tripper is used to fill their tertiary crushing storage facility. This paper is a we study to demonstrate the drive and control systems in use on the tripper. Of special note is the design concept used to allow the system to operate multiple motors in both demand and regenerative modes through a single VFD. Also noted is the use of touch screen local controls, handheld radio controls, starting/stopping/ braking philosophies, safety device interfaces, and the local to remote control interface.

Jan 1, 2004

By R. L. Grayson, Y. J. Wang

An application of material requirements planning (MRP) to coal mine inventory control is presented. MRP is an efficient material control system that integrates the production planning and inventory management functions. Net material requirements are determined from the production forecast utilizing bill of material files, the inventory status file, and the purchase order status file. Net requirements are computed for each period in a specified planning horizon, and purchase orders, offset by lead time, are initiated routinely to ensure timely receipt of materials. The MRP system is especially useful in production-inventory systems in which con¬sumption of materials is directly production dependent.

Jan 1, 1987

By F. L. Pirkle, D. A. Podmeyer

The mineral zircon is mined for use as specialty foundry sands, abrasives, ores of Zr02 and zirco¬nium metal, refractories and zirconium chemicals. It is produced as one of several products from heavy-mineral sand deposits associated with ancient shorelines. Because of its low coefficient of thermal expansion, its high melting point, its high refractive index and its chemical inertness, it is an attractive refractory material. Zircon varies from deposit to deposit in terms of grain size, grain shape and chemical purity. Thus, there is a wide range of commercial zircon products that differ in impurity levels, particle shapes and grain sizes.

Jan 1, 1993

By D. M. Muir

Thiosulfate offers a nontoxic alternative to cyanide for processing gold ores. The mechanism of leaching gold using ammoniacal thiosulfate solution is driven by the Cu(II)-Cu(I) redox couple and is complicated by competing ligands such as NH3 and S2O32; It is shown that an understanding of the copper speciation and sulfur speciation is required to optimize this system. This paper presents Eh-pH and speciation diagrams for varying concentrations of Cu(II), S2O32- and NH3 and discusses the conditions under which various copper and sulfur species are stable.

Jan 1, 2002

By M. G. Hester, G. S. Adisoma

To address the problem of grade estimation in a general three-dimensional shape and the uncertainty associated with the estimate, the technique of jackknifing/ block-kriging shortcut is proposed. A new estimator called jackknife kriging is introduced first. Through the jackknife variance, a confidence limit for the reserve-grade estimate can be calculated. Unlike the kriging variance, which is more a measure of data configuration and which is independent of data values, the jackknife variance reflects the true variability of the data. This approach provides a simple way to set a confidence level for global estimation of resources.

Jan 1, 1997