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By H. A. Stoess

The Minerals Industry makes heavy demands for and on its Material Handling equipment. It also gives progressive management the opportunity for considerable savings, ad consequently increased profits. In some cases, cost of Materials Handling amounts to 40°/o of the total cost of the ultimate product. Handling costs are hidden in overhead, indirect labor, excessive maintenance, productive workers performing handling tasks, and, a great many more. Even though Materials Handling is the oldest occupation of mankind, it is only within the past twenty years that it has emerged as a specialized field. While this industry has made full use of all types of mechanical and vibratory conveyors, pneumatic conveyors in their proper application can be a distinct asset. me use of pneumatic conveyors by this industry however is limited- to a certain extent by the particle size of your products through the various phases of manufacture, as well as their bulk density. However, with increasing knowledge of the fluidization of dry materials, their use is becoming more wide spread.

Jan 1, 1962

By R. K. Mehta

An accurate, efficient and stable computation of the mill matrix function (eAt) is needed where mill matrix (A) is a real general matrix. Two important modeling cases in comminution where such need arises are: Heterogeneous comminution behavior of multi-component ores and ultra-fine grinding involving simultaneous attrition and fragmentation breakages. This paper presents the application of a novel splitting method in conjunction With similarity transformation technique in the form of "product formula" which is found to work in all cases and uses a most aggravating, yet interesting property of the matrix exponential in a restricted sense. Results are presented showing that this method can yield solution as accurate as those obtained With an analytical technique. The utility of this computational approach is demonstrated by parameter estimation analysis using a distributed component model in the liberation area through computer simulations.

Jan 1, 1992

By Edward J. McNamara

Sulphur as an element has been used for centuries. The technique of storing, handling and transporting it in its various forms has changed through the years. Freeport Sulphur Company, a division of Freeport Minerals Company, has produced sulphur since 1912. The first storing and transporting of this product as a liquid began in 1947. Significant environmental problems occurred in the handling of solid sulphur in the late fifties and early sixties. Since the sulphur WAS produced in the liquid form and the major customers used it in the liquid form, it became obvious that a liquid transportation system was the solution. The liquid sulphur delivery eliminated the dusty and hazardous handling problems and the contamination of the sulphur by dirt, acid, moisture and other materials. The remelting by the customer to use the sulphur is thusly eliminated with a savings in energy. In addition, this change in the mode of handling permitted a broad development of new sulphur mines in the marshy coastal area of Louisiana and offshore in the Gulf of Mexico.

Jan 1, 1978

Nearly as impressive as the machines that will be on display at MINExpo are the massive engines and tires that keep the machines moving. As you can imagine, it takes a special tire and special engine to run these machines. The following is a look at some of the exhibitors that will be at MINExpo displaying engines and tires. Cummins Inc. Cummins Inc. will display a lineup engines from 37kW to 2,983 kW (49 hp to 4000 hp) at MINExpo, representing the most extensive ?smallest to largest? range the company has ever put on display.

Jan 1, 2012

By J. L. Post

A large body of readily available Na-montmorillonite is present about 24km (15 miles) east of Fallon, Nevada. The clay is comparable to Wyoming Na-bentonite, but with somewhat less MgO and somewhat more Fe2O3 in its crystal structure. The physical and industrial properties of the Nevada clay are comparable to those of the Wyoming clay. The Na-montmorillonite is presently mined for use as hazardous waste barrier material and as a sealant for canals. It may be economically feasible to process the clay material for removal of impurities.

Jan 1, 1996

A machine that improves safety during the cutting of boxholes (ore-passes) and travelways in underground mining operations has delivered impressive results in trials conducted at a South African platinum mine. The technology is a joint effort by Sandvik Mining and Construction and platinum mining company Lonmin. The ABH 1600 boxhole borer was built by Voest-Alpine Bergtechnik, Sandvik’s Austrian subsidiary. It was delivered to the Lonmin Eastern platinum mine in February 2005. There, it was deployed underground on the Number 8 Level (320 m or 1,050 ft below the surface) at the mine’s Newman incline shaft.

Jan 1, 2006

By J. Pinkley

In June of 2002 Hilti North America received the first MSHA permissible approval for usage of a powder actuated tool device in a gassy mine atmosphere. The purpose of this paper is to discuss the implementation of this commonly utilized tool technology in the construction industry, to the underground gassy mining industry over the course of the last 5 years. Prior to June of 2002, underground gassy mining industry had attached materials such as ventilation curtains, power cables, communication cables, signage, and other materials by either manually driving individual spads or nails into the mine roof or rib or by attachment to existing roof bolt bearing plates. The Hilti DX 460 powder actuated tool is portable, durable, and lightweight (4.5 pounds). The Hilti DX 460 powder actuated tool system is powered by Hilti .27 caliber permissible explosive boosters. The energy force of the Hilti .27 booster?s acts on a captive piston principle in the Hilti DX 460 powder actuated tool, that applies the setting force for the direct fastening to the individual fastener chosen for the application by the end user. Each year Hilti can be called upon by MSHA to provide booster materials for re-testing per our Hilti DX PAD 1/00 approval.

Jan 1, 2008

By A. Wahab Khair, John G. Oldsen, John C. Stankus, Song Guo

During the last several years, implementation of trusses, in lieu of wood cribs, has been successful for supplemental tailgate support in the Pittsburgh seam. This paper reviews, the truss support system provided by the new high strength 0.6" tensioned cable truss, which is now also being used in cribless tailgates. Cable loading and roof deformation were monitored to evaluate roof and floor performance. The test results indicate that the cable truss system successfully controlled the roof and floor during the first and second panel extraction. This paper will describe the advantages of cable trusses and their load transfer mechanism as well as mine evaluation.

Feb 24, 1997

By CAIJUN CHEN, MING ZHANG, ZHENWEI WU, FENG ZHOU, BOQUAN LI, XILIANG ZHANG, ZHOU PU

Traveling grate is a widely used process for iron ore pellet production, but the thermal state of pellets in the drying section is still unclear. In this study, the temperature distribution of the drying section was investigated using computational fluid dynamics (CFD). The results indicate there is a coupling effect in the drying section of a traveling grate. Gas with higher temperature in down-draught drying (DDD) transfers heat to the up-draught drying (UDD) through the gap of the insulation board, and the temperature gradient of the pellet bed changes before reaching the insulation board. The characteristics of pellet bed expected to appear in DDD are displayed in UDD in advance. To verify the model, a contrast experiment was conducted.

By J. H. Tylczak, R. Blickensderfer

Impact and abrasion properties of various commercial US grinding halls were evaluated and compared by the Bureau of Mines, US Department of the Interior. Laboratory tests were conducted on balls obtained from eight major US manufacturers. The halls included forged steel, cast steel, and alloyed white cast iron and were subjected to repeated impacts until they broke or until 300,000 impacts were exceeded. Pin abrasion tests also were conducted. The results showed wide differences in impact lives, ranging from a few thousand to over 500,000 impacts. The life of inferior commercial halls was increased five to six times by a laboratory tempering heat treatment. For halls that did not break, the major impact wear mode was spalling and ranged from an average rate of 0.28 to 4.46 mg per impact. The softest halls (steel) had excellent impact resistance but low abrasion resistance. The abrasion resistance of the steel halls generally increased with hardness. The alloyed white cast irons had about twice the abrasion resistance of the steel halls. Users should become aware of the wide variations among commercial halls, and ball manufacturers should be aware that their product can he improved.

Jan 1, 1990

By H. Kempton

New methods for remediating metals-contaminated groundwater include in-situ emplacement of highly adsorptive substrates to permanently retard solutes. Substrates are introduced by sequential injection of soluble components that precipitate in the aquifer, forming a permanent high-retardation zone. This method overcomes the factors that limit pump-and-treat remediation; i.e, long-term source loading and slow desorption. Column tests demonstrated efficient substrate emplacement, increasing retardation coefficients of Cr(VI) by 20 and As(V) by 40. Similar effectiveness is expected for other heavy metals. Simulations using a coupled advective-geochemical model accurately matched substrate emplacement and arsenic attenuation, allowing extrapolation to other constituents and larger-scale applications.

Jan 1, 1999

By B. Kolonja

This paper considers simulation of truck dispatching system designs using maximum expected production of the truck-shovel system as the measure of performance. Two methods are utilized, multiple comparisons with the best (MCB) and the combination of MCB and the variance reduction technique known as common random numbers (CRN). These two techniques are compared via simulation experiments. The results show that the combined procedure of MCB with CRN is the superior tool to reduce the total number of replications needed to ensure the specified probability of correct selection over the finite number of designing systems. In this case study, MCB with CRN reduces the variance by 29% and the number of required replications by 48%. Also, the MCB with CRN procedure narrowed the confidence interval by 18%.

Jan 1, 1994

By Graham Swan, Richard K. Brummer

The paper begins by describing an underhand cut-and-fill mining concept for a 50m thick, generally tabular though irregularly shaped orebody dipping at 30 degrees and occurring at a depth of between 2300 and 2700m in the Sudbury Basin. From this, the broad design requirements of a fill system are stated. Two and three-dimensional numerical models are then described which were built to evaluate the theoretical benefits of different types of fill reinforcement. Included in this evaluation are the effects of span, fill strength, fill tightness, as well as static and dynamic loading types. Results, supported by large-scale physical models, are presented to show the significance of reinforcement on stable, undermined fill performance. Finally the paper describes work which has been done to evaluate the suitability of so-called silicated cemented backfill. This system is, in principal, attractive for deep mining applications since transportation is in the "safe" hydraulic regime, while fill water run-off, segregation and shrinkage effects are potentially eliminated in the stopes. The results from various surface and underground trial pours are reported which substantiate the proposed use of this type of backfill at depth.

Jan 1, 2001

By Rambabu Pothina, Rajive Ganguli

The economics of a mineral-processing circuit is dependent on the numerous sensors that are critical to optimization and control systems. When a sensor goes off calibration, it results in errors that can have a severe impact on plant economics. Classical statistical approaches fail to detect when errors are “subtle,” unless they grow and become large enough to be “gross,” whereas methods based on signal processing and artificial intelligence fail in dealing with the complexity of process fluctuations. Due to the sheer volume of sensors, undetected errors are not remedied until the next calibration, which on average are a year apart across all industries [1]. This research aims to detect such subtle errors (2 percent bias) in shorter time spans of about a month — rather than wait for errors to grow — using innovative data-mining techniques and algorithms.

By Thomas R. Kuesel

Just south of the L'Enfant Station in Seventh Street, the WMATA system splits into two branches, each comprising twin single-track soft ground tunnels. Immediately at the beginning of the section, Interstate Route 95 crosses transversely over the alignment in open cut, removing most of the cover over the tunnels. Seventh Street spans I-95 on a bridge whose abutments and pier also cross transversely over the four tunnels, with their footings as little as 7 feet above the tunnel crown (Figure 1). Soil investigations revealed that the tunnels would have to be driven through mixed face, with a clay invert and a waterlogged sand crown. Thus, there was a good chance that the roof would fall in, leaving 1-95 and the Seventh Street Bridge in a crater. Since there was no roof that could be counted on, these were figuratively (and potentially truly) Washington Metro's Topless Tunnels (Figures 2 and 3). DESIGN ALTERNATIVES Faced with this situation, the designers considered several options, including temporary detours that would permit demolition of the bridge and building tunnels under the 1-95 Freeway by cut-and-cover methods. They also investigated structural underpinning of the bridge and freeway pavement, and strengthening the bridge abutments and center pier by post-tensioning to enable them to span over any subsidence trough.

Jan 1, 1976

By R. Wensel

A composite material consists of two or more dissimilar components. These dissimilar components retain their identities when mixed together and contribute to the properties of the composite. A composite usually consists of two parts, the matrix and the reinforcing material, or extender that is added to the matrix. Typical materials used as the matrix in composites are metals, polymers, and ceramics. The reinforcing material can be added for any number of reasons. For instance, if the matrix is expensive, an inexpensive filler may be added to the matrix to lower the cost of the product without sacrificing properties. An example of this is calcite (CaC03) which is added to systems such as polyvinyl chloride (PVC), to lower the cost. Reinforcements may also serve as a means to enhance the properties of the matrix material. For example, carbon fibers are frequently added to plastics to increase their strength, and glass spheres may be added to plastics to improve flexural strength. Mg(OH)z is added to polymers to give the property of fire retardancy. The latter is the focus of this paper.

Jan 1, 1995

By Harold B. Goldman

On the basis of tonnage, the sand and gravel industry is the second largest nonfuel mineral industry in the United States. In 1990, the production of sand and gravel was 927 Mt valued at $3.4 billion. California, which leads the nation with more than 126 Mt, together with Texas, Washington, Michigan, and Ohio, account for 36% of the total production in the nation (Table 1). In commercial usage, sand applies to rock or mineral fragments ranging in size from particles retained on a No. 200 Sieve (0.074 mm openings) to those passing a No. 4 Sieve (4.76 mm openings). Gravel consists of rock or mineral fragments larger than 4.76 mm, ranging up to 88.9 mm maximum size. The construction industry consumes 97% of the sand and gravel produced; the remainder is sand used for specialized products such as glass (see chapter on Industrial Sand and Sandstone and Glass Raw Materials). Utilization The building industry uses sand and gravel chiefly as aggregate in portland cement concrete, mortar, and plaster; the paving industry uses sand and gravel in both asphaltic mixtures and portland cement concrete. Aggregate is commonly designated as the inert fragmental material that is bound into a conglomerate mass by a cementing material such as portland cement, asphalt, or gypsum plaster. Sand and gravel is also used as construction fill, road base and subbase, and decorative material. Portland Cement Concrete Aggregates: Portland cement concrete consists of sand and gravel surrounded and held together by hardened portland cement paste. Concrete mixes commonly contain 15 to 20% water, 7 to 14% cement, and66 to 78% aggregate. Sand and gravel used as concrete aggregate have to meet many requirements (Goldman and Reining, 1983). Premature deterioration of concrete has been traced in many instances to the use of unsuitable aggregates. Asphaltic Aggregate: Asphaltic mixtures used predominantly for paving consist of combinations of sand, gravel, and mineral filler (material finer than 0.076 mm), uniformly coated and mixed with asphalt produced in the refining of petroleum. Sand and gravel used as asphaltic aggregate must meet the same general physical requirements as materials used for portland cement aggregate. GEOLOGY General Requirements of Aggregates Construction aggregate has many requirements that are difficult to meet if only unprocessed material from natural deposits is used. Suitable material is composed of clean, uncoated, properly shaped particles that are sound and durable. Soundness and durability are terms used to denote the ability of aggregates to retain a uniform physical and chemical state over a long period of time so as not to disintegrate when exposed to weathering and other destructive processes. Individual particles must be tough and firm, possessing the strength to resist physical stresses and chemical and physical changes, that may cause swelling, cracking, softening, and leaching. The aggregate should not be contaminated by excessive clayey material, silt, mica, organic matter, chemical salts, and surface coatings. Physical Properties: The quality of aggregate depends upon its physical and chemical properties. These, in turn, may be inherent mineralogical and textural features of the rock or may be the effects of later changes such as tectonics, mechanical or chemical weathering, or incrustations. The physical properties most significant for concrete use are: 1) abundance and nature of fractures and pores, 2) particle shape and surface texture, and 3) volume changes which may occur because of freezing and thawing or wetting and drying. An aggregate is considered to be physically sound if it is adequately strong and capable of resisting the agencies of weathering without disruption or decomposition. Minerals or rock particles that are physically weak, extremely water absorptive, and easily cleavable are susceptible to breakdown. The use of such materials in concrete reduces strength or leads to early deterioration by promoting weak bond between cement and aggregate, or by inducing cracking, spalling, or popouts. Severely weathered, soft, micaceous, or porous materials may cause localized stresses to develop in concrete by swelling and shrinking during wetting and drying or freezing and thawing cycles. Physical Suitability of the Various Rock Types. Sedimentary rocks have a wide range in physical and chemical qualities. Sand- stones and limestones, if hard and dense, are ordinarily satisfactory, but many sandstones are friable and excessively porous and commonly are clay-bearing. Shales generally make poor aggregate material, being soft, weak, and absorptive. Most igneous rocks are satisfactory, being normally hard, tough, and dense. Tuffs and certain flow rocks may be extremely porous and have high water absorption and low strength. Metamorphic rocks differ in character. Most quartzites are massive, tough, and dense. Fine-grained marbles are usually durable, but coarse-grained marbles have low abrasion resistance. Gneisses are ordinarily very tough and durable. Some schists contain micaceous minerals that are undesirable because they are soft, laminated, and absorptive. Micaceous minerals are susceptible to splitting along cleavage planes and thereby impair particle strength and durability. Some schists and slates in particular are thinly laminated and tend to assume flat slabby shapes that lack strength-and do not pack well. Any or all of these rock types may be rendered undesirable because of harmful exterior coatings. Weathering processes, particularly the action of ground waters, deposit these coatings. The most common coatings are calcium carbonate, clay, silt, opal, chalcedony, iron oxide, manganese oxide, and gypsum. Particles with these coatings are undesirable as aggregates because the bond between particle and coating may be weak, and decreasing the strength of the aggregate-cement bond.

Jan 1, 1994

By Nasser Madani, SULTAN ABULKHAIR

The geological and geostatistical modeling of mineral deposits requires densely sampled drillholes that provide accurate and reliable hard data. Furthermore, quantifying orebody uncertainty through geostatistical simulation can allow mining engineers to assess long-term risk in mine planning. Nevertheless, ore deposits can sometimes lack dense drillhole information, reliable hard data with proper quality assurance/quality control (QA/QC), or sometimes both. This study is based on a coal mine located in the Republic of Kazakhstan, where an iron dataset is based on data from three newly drilled drillholes, and geological information comes from a massive collection of legacy drillhole data with no evidence of proper QA/QC. For this reason, a workflow was introduced to construct a representative training image from legacy data and stochastically model geological domains within these three drillholes using a multiple-point geostatistics technique. Once the geological model was obtained, a two-point geostatistics algorithm was applied to model the iron inside each geological domain. The direct sampling algorithm was chosen for modeling geological domains, and sequential Gaussian simulation for iron grade calculation. Both methods were extensively evaluated using different statistical tools and analyses.

Aug 1, 2022

By Luzheng Chen

The study aimed to evaluate the separation performance of a full-scale continuous centrifugal concentrator in the reconcentration of fine hematite from high-gradient magnetic separation (HGMS) concentrate in a tailings recovery plant, and to investigate the usefulness of the technology in industrial applications. The effect of changing the operating variables on concentrate grade and recovery was studied. The results indicate that among the variables considered in the study (water spray pressure, centrifugal acceleration, feed volume flow rate, feed percent solids and the reciprocation and spacing of water sprays), the change in centrifugal acceleration affects the recovery the most and continuous concentration can be achieved only when the water spray has a sufficient pressure. In addition, the reciprocation and spacing of the water sprays have a significant influence on the concentrate grade. Although performance of the full-scale concentrator is slightly inferior to pilot-scale trials, due to limitations in the scale-up design and the fluctuations of feed material characteristics, this concentrator provides a potential way to achieve continuous concentration and obtain a high-grade concentrate from tailings.

Jan 1, 2010

By Richard C. Travis, Edward C. Dowling

A detailed kinetic study of the flotation installation at the Metcalf Concentrator revealed a rougher flotation circuit operating under less than optimal conditions. Based on these results, a project was initiated to approximately double the rougher flotation capacity by increasing the installed volume from 780 cubic meters to 1,560 cubic meters. This project, which was completed in early 1991, replaced the existing cells with larger capacity cells. A comprehensive analysis of results demonstrates significant metallurgical benefits. INTRODUCTION/BACKGROUND The Metcalf Concentrator is located in Morenci, Arizona and is part of Phelps Dodge Morenci, Incorporated. Sumitomo Metal Mining of Arizona is a minority partner in the operation with 15% interest. The Metcalf Concentrator is the newer and smaller concentrator and operates in conjunction with the Morenci Concentrator. Operating capacity at Metcalf is currently 48,000 TPD of ore on a 365 days per year basis. The Metcalf Concentrator was commissioned in 1974 at a 30,000 TPD operating rate for the purpose of treating ores originating in the Metcalf Mine. The mine takes its name from the former town of Metcalf which was named for Robert Metcalf who was credited with discovery of the mineral district. The predominant ore mineral is chalcocite which occurs as a secondary enrichment closely associated with iron pyrite. The host rock is largely granodiorite and quartz monzonite. The original rougher flotation circuit consisted of a total of six rows of Wemco 8.5 cu. meter (300 cu.ft.) flotation machines treating pulp from the two grinding sections (Sections A and B). Each row was configured in a 4-4-4 arrangement. Shortly after startup the throughput rate was increased significantly without sustaining a recovery loss. This increase was achieved by raising the target value for the particle size of the cyclone overflow which is the rougher flotation feed. Shortly thereafter, the capacity of the pump and cyclone began to restrict further increases in throughput. After testing, two 66 cm. (26-in.) cyclones and a 12-in. X 12-in. centrifugal pump replaced the original classification equipment. As a result of these modifications, the grinding section could routinely process in excess of 42,000 TPD. Due to the increased tonnage rates, limitations in the rougher flotation circuit performance were observed. In an effort to improve the performance of rougher flotation with this higher throughput, the speed of the flotation mechanisms was increased from 230 RPM to 250 RPM. This change improved the suspension of the coarser feed and induced additional air into the pulp. It did, however, apply additional strain to the motors, shortening their life. At these elevated processing rates, it was found that the dart valves operated almost entirely at the top end of the control range and could not efficiently handle upsets from the grinding section. This was remedied by lowering the end overflow weir and allowing some of the tailings to overflow the end weir. However, in order to obtain acceptable recovery levels, the flotation pulp was maintained at a high level, adversely influencing the rougher concentrate grade.

Jan 1, 1993