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By George L. Wilhelm

Many factors, some of which are not easily defined or described, must be considered in the design of a hydraulic backfill system. After participating in the design of several plants, I have a conviction that future refinements in sandfill systems must come in large part, from the merging of good design ideas and information from existing operating plants. It is important then, that we document and publish information on existing plant designs and their operating characteristics. This information will then be available for use by our successors and later innovators in hydraulic fill placement. The Mayflower hydraulic sandfill system is similar to other plants. The intent of this paper is to describe only this system's unique design and operating characteristics. I will not describe in any detail, the familiar elements of the system. I will document some of the observed hydraulic characteristics of the system, elaborate on some of the design situations that had to be solved, and will discuss operating factors that are not generally described in our technical literature.

Jan 1, 1968

By Myles E. Robinson

During the last decade there were pronounced changes in the competitive pattern of the fossill fuels It is proposed to trace these trends and describe inter-fuel competition, first as it relates to the economy as a whole and then more specifically to examine competition of the fossil fuels as these share the electric utility market. Table 1, Competitive Fuels and Water Power Used in the United States, 1950-1959, shows the growth in the consumption of coal, oil, gas and water power 'during the past decade. Uses which are not directly competitive among the fuels, such as tractor fuel, carbon black, and consumption of petroleum products in the making of synthetic rubber, have been excluded from these statistics. The experience of the three fossil fuels in competition since 1950 shows natural gas expanding more rapidly, than oil by roughly twice as much, 219.0 percent' compared to 124.1 percent growth in B.t.u.s of oil consumed in the ten-year period. Percentagewise, water power little more than held its own, and coal, including anthracite, actually decreased more than one-fifth.

Jan 1, 1961

By E. A. Domínguez

Kaolin deposits of Patagonia (Argentina) were formed by ?in situ? alteration of volcaniclastic rocks or by erosion, transportation, and deposition of residual clays in small basins. The mineralogy, geochemistry, grain size distribution, and specific surface area of natural and washed kaolins were studied in order to point out the relationships with the ceramic process. Primary kaolins are coarse-grained, kaolinite+quartz±halloysite, with a very low specific surface area. Sedimentary clays are either kaolinitic?smectitic and very fine-grained or kaolinitic with a coarser particle size distribution. An interdependence between mineralogy, chemistry, particle size distribution, texture, surface activity and ceramic behavior was found. Plasticity is strictly dependent on surface activity and expandable clay minerals. Slip rheology is affected by soluble salts, smectite, and tubular halloysite. Kaolinite-halloysite play an opposite role versus smectite-I/S in slip casting and tile pressing. Kaolinite and quartz are beneficial for drying behavior while expandable clay minerals increase drying sensitivity. Firing behaviour is mainly affected by minor components supplying fluxing oxides.

Jan 1, 2010

By M. T. Atwood

For more than sixty years the rich oil shale formations of Colorado, Utah and Wyoming have been evaluated as a future source of petroleum. After many false starts the commercial production of shale oil is near. Union Oil and Colony (Exxon and Tosco) have begun construction of commercial plants. Occidental and Rio Blanco (Gulf and Standard of Indiana) are well along in the development of modified in situ (underground) processes. A number of other companies and groups are in advanced stages of development. This paper will review some of the major elements involved in the production of shale oil with emphasis on means available to express the efficiency of production of pyrolysis liquids and gases from oil shale rock.

Jan 1, 1982

By J. Cooper, M. W. Staub

Environmental management systems (EMSs) have been in use for more than a decade. US mining companies are only just beginning to adopt EMSs. This lag is primarily due to lack of market forces and lack of evidence that EMSs add value over standard compliance programs. Several recent studies concluded EMSs improve environmental performance and reduce costs. State and federal regulatory agencies are using EMSs as an innovative tool to streamline the regulatory process and achieve continual environmental improvements. The climate is right for the mining industry to adopt an EMS model that improves environmental performance and takes advantage of new regulatory programs.

Jan 1, 2004

By Adam Saylor, Travis A. Shoemaker, Steve Miller

Lidar scanning has become an increasingly popular tool for documenting underground excavations; however, high costs of traditional mechanical electrical lidar hardware, software, and training have limited the frequency at which lidar scans can be performed. Additionally, traditional scanning can be time consuming because multiple scan positions are necessary. With Apple’s incorporation of low-cost mobile solidstate lidar on select smartphones and tablets, lidar is becoming more tractable for everyday construction documentation similar to construction photo collection with smartphones. Here, we describe benefits of mobile solid-state lidar and describe several practical applications for use in underground construction, such as documenting the working face, over-blast, and geologic features of tunnels.

Jun 13, 2023

By W. N. Hamilton

British Columbia is geologically favourable for a rich variety of industrial mineral occurrences. Some have been produced for years, others overlooked until recently. Major production occurs for asbestos, gypsum, limestone, magnesite, silica and sulfur; lesser production for a dozen others. For several of the minerals, potential is much greater than existing production. New production opportunities exist also for diamonds, niobium and REE minerals, fluorspar, kyanite, nepheline syenite, talc, and several others. Alberta, though geologically less diverse, also has many industrial minerals. Limestone, salt and sulfur have the major production; clay and shale, silica, sodium sulfate and a few others lesser production. Opportunities exist for expanded production, and for new production in heavy (Ti -Zr) minerals, formation brines (Ca-Mg-I-Li), and gypsum.

Jan 1, 1987

By Rick Frechette, Bryan Ulrich

Representatives from several mining operations in three western states left their mines behind for a day in February to discuss with their peers the issue of water. The event was Knight Piésold and Co.’s Roundtable 2007, held in Elko, NV. It was third such event put on by the company. The issue this year was site-wide water considerations.

Jan 1, 2007

By J. Noll

Many underground metal/nonmetal mines are using enclosed cabs on mining equipment to reduce the exposure of miners to diesel particulate matter (DPM). However, some enclosed cab systems may not be meeting their expected efficiency in capturing DPM, which could be a result of inappropriate filter use, cab leaks, or insufficient pressurization. NIOSH investigated several types of filters for reducing DPM to determine which type had the best capture efficiency. The laboratory results indicated that a MERV 8 (Minimum Efficiency Reporting Value, as defined by the American Society of Heating, Refrigerating and Air- Conditioning Engineers) filter captured about 50 percent of the DPM, a MERV 16 filter collected 96-98 percent of the DPM, and two HEPA (high efficiency particulate air) grade filters captured over 99 percent of the DPM. NIOSH also performed a field study to measure the efficiency of two cabs at a limestone mine. The cab filtration systems of a loader and haul truck were found to be over 90 percent effective in removing DPM except under certain operating conditions when the efficiency was as low as 41 percent. Evidence seems to suggest that these conditions were when a window was open in the cab.

Jan 1, 2011

By Michael Day, Paul Kos, Scott Brinton

A hydrogeologic characterization and impact analysis was performed for a proposed quarry at the Hitch Rack Ranch located in the Little Turkey Creek watershed southwest of Colorado Springs, Colorado. Continuous multiple channel tubing, nested piezometers, stream flow measurements, and mapping of known seeps were used to define the three-dimensional potentiometric distribution and areas of groundwater recharge and discharge. Water balance considerations, mass balance calculations, and potentiometric response to earth tides and barometric fluctuations confirmed that the granite fracture system in the ridge area of the proposed quarry has an extremely low bulk hydraulic conductivity resulting in minimal groundwater discharge to sustain the baseflow of Little Turkey Creek. The Little Turkey Creek valley forms the major conduit for groundwater flow exiting from the upper part of watershed underlain by granite. This conclusion has significant implications with respect to mine planning to minimize projected impacts to the hydrologic system and preserve this recharge component to downgradient Denver Basin sedimentary deposits.

By Nicholas T. Esposito

An advanced coal preparation plant has been built at Homer City, Pennsylvania, by Pennsylvania Electric Company, a subsidiary of General Public Utilities Corporation, and New York State Electric and Gas Corporation, as an alternative to utilizing flue gas desulfurization technology to meet the Federal Environmental Protection Agency and the Pennsylvania Department of Environmental Resources air quality emission regulations of 4.0 lb S02/106BTU for the two (2) existing coal-fired generating station Units No. 1 and No. 2, and a 1.2 lb S02/106BTU for the new Unit No. 3. The coal preparation plant is designed to process 5,200,000 tons of run of the mine coal annually and has a design capability to process 1,200 tons per hour via two (2) equal capacity 600 tons per hour preparation circuits.- The plant is designed to produce multi-product coal streams consisting of a middling product of medium ash and medium sulphur content, which is environmentally compatible to support operation of the two (2) existing generating Units I and 2, and a deep cleaned, low ash, low sulphur coal product capable of environmentally supporting the ambient air quality requirements of the new Unit 3 generating facility. The waste product from the process consists of high ash, high sulphur reject material. The process has the acronym MCCS (Multi-Stream Coal Cleaning System).

Jan 1, 1982

By W. M. Tupper

[The two types of sulfide deposits in the Bathhurst Newcastle area are; (a) epignetic fissure deposits, and (b) massive sulfide deposits. Geological evidence has been variously interpreted to suggest a syngenetic origin, a source bed' origin, or a magmatic hydrothermal origin for the massive sulfide deposits. Sulfides disseminated through the black shales and argillites of the host rocks are enriched in S32 (mean value 22.34, S34. = 5.8 per mil) relative to the meteoritic standard of 22.21, and have a broad spread in range of values. S32/S34 ratios of sulfide minerals from the deposits occur in two distinct groups. The massive sulfide deposits exhibit ratios between 21.88 to 22.05, while the fissure deposits exhibit ratios between 22.18 and 22.21. These results suggest two separate sources for the sulfur, each, however, resulting in magmatic hydrthermal deposition because of the narrow spread of ratios in each group. Granite intrusive into the host rocks of the sulfide deposits have a mean K/A age of 386 ± 10 M.Y. Lead minerals in the sulfide deposits have a mean nodel lead age of 370±20 M. Y. Thus the lead minerals and the granite bodies were emplaced during the same major orogenic event. Sulfide minerals from magmatic hydrothermal deposit have a very narrow range of S32/S34 values, as do those of the Bathurst area. It seems reasonable, therefore, that well homogenized magmatic hydrothermal solutions are the most logical source of the sulfide deposits. Furthermore, the homogeneity of the lead isotopic abundance data gives strong independent evidence that the ores are of a magmatic hydrothermal origin.]

Jan 1, 1960

By Robert E. Barry

For new coal-fired power plants, federal regulations require that emissions of sulfur dioxide be limited to 1.2 pounds for every million BTU'S burned. This is equivalent to coal with a sulfur content of roughly 0.7 percent for Eastern bituminous coals and roughly 0.6 percent for Western sub-bituminous coals. The states and their political subdivisions are free to apply more stringent standards and to develop implementation plans covering existing and new units. Most Western-sub-bituminous coals contain less than 1% sulfur and hence their use, in many cases, will allow a utility to meet the regulations. However, there are problems in using such coals in furnaces designed for Eastern bituminous coals, and furthermore it will take many years to open mines and provide transportation facilities to utilities which are now burning coals with a higher sulfur content. Moreover, pending federal legislation would outlaw strip mining on land to which the federal government owns the mining rights. Those utilities who, for one reason or another, intend to continue burning Eastern bituminous coals with sulfur contents in excess of 1 percent are faced with removing SO2 from the stack gases. The alternative of utilizing coal gasification where the sulfur is removed prior to burning in a power plant is still in the early stages of development. Therefore, a large number of processes are under development for SO2 control.

Jan 1, 1974

By John H. Bassarear

How best to grind? This article compares conventional crushing and grinding circuits to semiautogenous circuits, reviews recent installations of each circuit, and describes seven methods of using autogenous or semiautogenous techniques. In addition, steel and power consumption data are reported and benefits of a dedicated digital computer are discussed. Size reduction is the most expensive operation in most mills. Crushing and grinding are usually the greatest part of capital costs. They often make up 60-70% of total mill operating costs. Picking the proper crushing and grinding method must, therefore, be done with great care, so the best circuit is chosen. In the past 10 years, there has been a strong trend toward using autogenous or semiautogenous grinding in mills throughout the world. Autogenous grinding is favored when the ore is quite competent and a fine grind is needed. Semiautogenous grinding is applied when fine crushing could cause severe problems or when ore varies in hardness or competency. The taconite iron ores of northern Minnesota fit the description for an autogenously ground ore and many are successfully ground that way. Most im¬pressive are the nine lines of 11 x 4.9 m (36 x 16 ft) mills powered by 9 MW (12,000 hp) motors at Hibbing Taconite. Porphyry copper and molybdenum ores fit the description for semiautogenous grinding. Recent installations include Highmont in British Columbia, Canada, and Quintana in New Mexico. Sampling Many mills have been built based on inadequate sampling data or insufficient tests. With the cost of many mills exceeding several hundred million dollars, it is mandatory that geologists, mining engineers, and metallurgists work together to prepare representative testing samples. Simple, repeatable work index tests are usually sufficient for rod and ball mill tests. However, pilot plant tests on 50-100 t (55-110 tons) of ore are frequently necessary for autogenous or semiautogenous mills. Preparation and selection of the test sample is of utmost importance. Procedures for autogenous and semiautogenous mill pilot plant tests are relatively simple for those experienced in running them. Reliable and repeatable results can be obtained if simple, fundamental procedures are followed. The accompanying figure shows a typical conventional crushing-grinding circuit with three stages of crushing followed by ball mills or a rod mill-ball mill combination. This flowsheet is typical of many mills that have been built throughout the world. Also shown is a typical semiautogenous (SAG) circuit with feed coming directly from a primary crusher, and the semiautogenous mill product going to the separation process. Many similar semiautogenous circuits are built today because they are simple and flexible, lend themselves readily to high tonnages, and usually cost less to build and operate. With some ores, it is possible to send mine-run ore directly to the semiautogenous mill, eliminating the need for a primary crusher, as at Benquet's Dizon mill in the Philippines. An autogenous or semiautogenous circuit, as the name implies, uses the ore itself to assist in the grinding process. Generally, for this type of circuit, the ore must be competent so large ore chunks can be used to grind smaller ones. If ore alone is used, then the circuit is autogenous; but if balls are added to supplement the charge, then the circuit is termed semiautogenous. Ore competency is not always a criterion, to break up large pieces and wash away cementing material. Autogenous and semiautogenous mills have been very successful on relatively soft uranium ores where the values are frequently found in the material that cements together the sandstone grains. Autogenous Circuits When an ore is hard and competent, it is always possible it might make good "pebbles" that could be used for fine grinding media. Seven methods have been tried using combinations of autoge-

Jan 6, 1982

By A. Steinmüller

Introduction In the design and operation of gravity concentration circuits, the application of process models for spiral concentrators offers significant benefits. A substantial amount of work has been produced over the last 30 years in the field of modeling the metallurgical performance of spiral concentrators. It is not the aim of this contribution to add to the refinement of modeling technique but to share some of the experiences and potential improvements which can be achieved in a relatively simple way. The design of spiral circuits usually requires extensive testing. This is often conducted in batch operation only, either due to lack of suitable continuous testing facilities, the unavailability of sufficient quantities of sample, or other constraints. Typical problems arising during circuit development from batch testwork are the extrapolation of results to different feed conditions, and resolving of internal recycles. Model selection and development The classic approaches in spiral modeling technique range from fundamental fluid dynamics, based on the Navier-Stokes equations in combination with expressions for local slurry properties, to fully empirical and statistical models. With the initial objective of developing an in-house tool for gravity circuit optimization and development, mathematical model types from each category, available either commercially or in the published literature, were evaluated. Model selection For the desired purpose, an approach proposed by Holland-Batt (1990) was found suitable, which was adopted and modified. Holland-Batt reported that the shape of release curves in spiral applications could be described by a combination of a linear function in the initial recovery zone, and a power law function outside this zone. The proposed recovery function was formulated as

Jan 1, 2005

Longwall mining is a commonly used method of coal extraction that involves the complete removal of large, rectangular panels of coal. Longwall mining causes the immediate seam roof to break and fall into the void created by mining. The convergence of the surrounding strata towards the mining void causes subsidence on the surface. The subsidence magnitude is related not only to the mining depth, the topography, the geological features and the overburden materials, but also to the sequence of the strata overlying a coal seam. In additional to the vertical subsidence which is evident at the surface, there are also horizontal movements inwards toward the centre of the void, which cause the surface to tilt, bend, stretch and com-press. This paper presents a parametric investigation of the influence of the overburden stratigraphy to surface deformations due to longwall mining using 2D finite element models. Models simulate rock movement by applying equivalent edge load to the open roof.

Jan 1, 2008

By S. E. Valji

Clay slurries are normally dewatered using flocculents like sulfuric acid or aluminum sulfate. This type of flocculation is based on the electrolytic mechanism. For certain clay dewatering applications, this method of flocculation is unsatisfactory. Flocculation, based on the bridging mechanism, using organic polymers has been utilized to overcome such problem situations. This method of flocculation offers solutions not possible by previous methods. Normally these flocculents are used to assist dewatering. In this case, not only is dewatering promoted, but also further processing is assisted by a change in the dilatant character of the filter cake that is formed. Discharge of filter cake is easier, extrusion of filter cake on to conveyor dryer is possible or improved, and heat transfer and drying rates of the extruded filter cake are substantially higher. Both natural and synthetic organic polymers have been utilized for this purpose. Selection, application techniques, and economics are described.

Jan 1, 1965

By D. F. Boyd

On April 10, 1958 a new 7500 long ton/day iron ore beneficiation plant went on stream producing an average of 3000 long-tons of high quality concentrate a day. Plant operates on two, 12-hour shifts is six days per week, The new mill end crust ink plant were built adjacent to the company's open pit dining operate on at Bomi Hills, Liberia. The mall is essentially a gravity concentrator employing crushing, and grinding to liberate the mineral values, followed by concentration in Humphreys spirals. The cleaner spiral tailings are re-ground and tabled to recover additional iron values. Ire addition to. this mills the company operates a crushing and screening plant for the high grade direct shipping ores

Jan 1, 1962

By Wm. Ross Wayment, Innes P. Grantmyre

INTRODUCTION It has been recognized for some time that major changes in mining methods will be required in the near future. Two types of factors contribute to this need for change. Intrinsic factors include ground control problems associated with mining at increasing depths, noise, dust, toxic fumes, and logistics problems which arise from operation in a cyclical fashion. Extrinsic factors include competition for labor from industries offering safer and less difficult work, pressure for less impact on the environment, and changing economic and political conditions. The search for new mining methods has resulted in extensive research being carried out on such novel approaches as thermal fragmentation, high-pressure water jets, sonic drilling, microwave fragmentation, and laser cutting, among others. Joy Manufacturing Co. has elected to concentrate on impact breaking in stopes as a first generation continuous hard rock miner. IMPACT BREAKING Fragmentation techniques show a drop in specific energy as efficiency improves. Specific energy is the energy consumed per unit volume of rock removed and is affected by such variables as rock material properties, fragmentation method used, operator skill, tool design, etc. Mechanical fragmentation methods generally have specific energies much lower than that of the more novel methods. Table 1 shows impact breaking to have an efficiency exceeded only by that of drill and blast methods and it is this high efficiency which led Joy to impactors as the subject for research on potential mechanisms for continuous mining in hard rock.

Jan 1, 1976

By Warren D. Stanford

The Alligator Ridge mine is a near-surface gold mine located in a remote area 113 km (70 miles) northwest of Ely, NV. The deposit was discovered in 1976 by a lone prospector working under a grubstake contract for Amselco Minerals Inc. Evaluation of mine potential proceeded quickly. Favorable drilling results led to feasibility and mine design studies by the end of 1978. Mine construction began in early 1980. By September of that year, the process plant was fully operational. The first gold was poured a few months later. Alligator Ridge is designed to produce 1.9 t (60,000 oz) of gold each year. The projected mine life, based on proven reserves, is to mid-1988. However, Amselco is actively conducting exploration nearby for additional reserves to extend the mine's life. Amselco, a subsidiary of the British Petroleum Co., is based in Denver, CO. The company is mine operator and jointly owns the project with Nerco Minerals Inc., a wholly-owned subsidiary of Pacific Power and Light. Alligator Ridge is Amselco's first US mining operation. Geology Alligator Ridge, so named because it appears in outline to be an alligator at rest, contains disseminated micron gold embedded in iron-streaked siltstones. Although definitive conclusions have not been drawn on age and origin, the gold ore bodies are probably young by geological standards. They were formed in a recent volcanic period still evidenced in parts of Nevada by geysers and hot springs. As these superheated solutions rose through the permeable siltstones, they deposited minerals in the rock and formed the present gold ore bodies. During 1977, an extensive soil geochemical sampling program with additional geologic mapping and outcrop sampling were conducted. The results generated several drill targets. Initial drilling was performed in November and December 1977, and ore grade mineralization was encountered in the first drill hole. The Alligator Ridge mine is unusual in relation to other and more recent western US mineral discoveries in that it occupies an area that had no previous mining history. The ore deposits are hosted in upper Paleozoic sedimentary rocks that consist predominantly of a thick carbonate sequence. The main ore host is the Devonian-Mississippian Pilot shale, which occurs locally as a sequence of thin bedded calcareous, carbonaceous siltstones and claystones. The maximum observed thickness of the Pilot section in the mine area is about 140 m (460 ft). Rocks in the Alligator Ridge area have been folded into a series of low amplitude anticlines and synclines that strike north-south and plunge to the south at about 20°, with limbs that dip nearly 20°. The folds have been truncated and deformed by later high-angle faults that generally strike northwest. Although multiple stages of movement are evident on the fault systems, the youngest period of activity is along the major northeast trend. The predominant structural pattern in the area is of the basin- and range-type high angle normal faults. Alligator Ridge is actually a horst block between two basin and range faults. Vantage Ore Deposits There are three principal ore deposits within the Vantage Basin and several smaller satellite mineralized areas. The three Vantage deposits are encompassed in a mineralized zone that covers an area 915 m (3,000 ft) long and 305 m (1,000 ft) wide. All mineralized zones have been outlined by more than 600 rotary drill holes, with an average depth of 150 m (500 ft). Mineralization occurs in both carbonaceous and oxidized rocks. The carbonaceous gold-bearing material is not amenable to current heap leaching practice. Therefore, only oxidized ores are now treated. The carbonaceous gold-bearing material is segregated and stockpiled as it is encountered during mining. The three ore bodies occur along a north-northeast strike, with mineralization becoming progressively deeper from north to south. The ore block dimen-

Jan 6, 1984