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By Sean Gallagher, Thomas G. Bobick, Richard L. Unger

This paper describes research by the Bureau of Mines on alternative materials-handling strategies for reducing the costs and incidence of back injuries in low-seam coal mines. Strategies recommended for redesigning materials-handling tasks include elimination of tasks, mechanization of tasks, and matching lifting tasks to the physical capabilities of underground miners. The report also discusses other methods that can be used by management to reduce the costs associated with back injuries. More detail can be found in Bureau of Mines Information Circular 9235 (Gallagher et al. 1990).

Jan 1, 1992

By Neil Hepworth

Neves Corvo Mine employs four mining and four backfill methods, including paste fill. The paper shows how the strength requirement for backfill in primary stopes was calculated and the relationship between laboratory strength and in situ strength requirement. The liquefaction of paste in secondary stopes is discussed with methods to determine the liquefaction potential. It was found from laboratory tests and the preliminary results of the underground trial, that the liquefaction potential of the paste is low at 2% and is high at 0.5% cement. The results to date are inconclusive regarding 1% cement.

Jan 1, 2001

By Malcolm Reeves

The heavy oil reservoirs of Alberta and Saskatchewan include sequences of unconeolidated silts and fine sands which respond in an unusual manner when subjected to the high temperature and pore-fluid-pressure associated with steam injection and other thermal enhanced recovery techniques. Apparent transient connections are suddenly established between producers and injectore and there is an associated enhancement in oil (and sand) production. These phenomena have been attributed to local fluidization and piping processes which are known to occur in situations where high pore-fluid-pressures prevent the mobilization of intergranular friction. These breakdown processes may be associated with the penetration of tongues of the heated reservoir fluids with suspended sand into the creep sensitive intact reservoir since the viscosity ratios are sufficiently high for viscous fingering instability of the fluid-fluid interface. A program of laboratory tests has been carried out to measure the strength characteristic of saturated oil sands at a variety of temperatures and fluid pressures. These tests suggest, that in common with the coarser Athabasca sands, the Waseca sands have very little cohesive strength and show the characteristic dilational failure response of dense sands. Some special tests, devised to determine the relative ease with which samples can be fluidized, confirm the expected susceptibility of the fine- sand silts. Both piping and fluidization can be readily induced at in-situ reservoir temperatures and pressures. Analysis of stresses around wellbores suggests that fluid-pressure gradients may be sufficient to initiate piping and that backward erosion along streamlines may link producers and injectors. Such pipes may act as well “adits” gathering oil from the heated reservoir and contributing to enhanced production rates. Mechanical breakdown of the reservoir by drilling, injection and production processes provides a consistent possible explanation for the sand-cut response of production wells.

Jan 1, 1986

By L. Alan Weakly

The purpose of this paper is to present a viable method of reinforcing rock pillars by utilizing fully grouted reinforcing steel and a cement - fly ash mortar. Although the fully bonded bolt concept is not new as exemplified .by the present widespread use of resin bolts within United States mines and by the use of cement grouted reinforcing used as back pins in the Kiruna Iron Ore Mine in northern Sweden, (1)(2) the method of stabilizing mine pillars with fully bonded reinforcing is new. This method, called the "grout-rebar system", was first incorporated at St. Joe Minerals Corporation's Fletcher Mine in December of 1972. The system was used on an emergency basis before extensive research on the mechanics of the system could be completed. Since December of 1972, however, approximately 206 pillars have been reinforced at Fletcher and the system is currently being used on a regular basis at two other St. Joe mines and at two competitor mines in the area. Basically, this paper is a case study of the efforts, research and results of utilizing the grout-rebar system, on a selective basis, at the Fletcher Mine. In addition to information about the system, this paper will explain in detail the three rock mechanics instruments developed by St. Joe and used to measure and monitor rock movement to validate the grout-rebar system.

Jan 1, 1976

By T. Reed Scollon

Major interrelated factors to be considered in assessing the impact of air pollution control regulations on coal are: (I) the fuel and fuel-related limitations of such regulations; (2) the rate of adoption and areal scope of the regulations; and (3) the availability of fuels and fuel-burning equipment to meet the requirements. A growing number of regulations contain provisions limiting the emissions of sulfur oxides or the sulfur content of fuels or both. With few exceptions, these limitations have not yet become fully effective in those areas which have already adopted regulations, and pertinent details of future regulations or legislation for most other areas are unknown at this time. Sufficient information is not avail- able to determine the availability of low-sulfur fuels at various demand and price levels, and large-scale commercial feasibility of sulfur-oxides removal processes and equipment is believed to be some years away. Accordingly, with the many uncertainties and unknowns, it is possible at best to make only a rough assessment of the impact of such regulations or legislation on coal.

Jan 1, 1969

By L. A. Roe

The year 1867 marks the first year of commercial production of phosphate rock in the United States. South Carolina produced almost all of the domestic output of mineral phosphate until phosphate mining began in Florida in 1888. During the period 1868 to 1949 the total marketed production of domestic phosphate rock was about 186 million long tons of which 71.5 percent was produced in Florida, 18 percent in Tennessee and 7 percent in South Carolina (1). From 1949 through 1960, Florida phosphate rock production has ranged Prom 71 to 77 percent of the total domestic production. Since three-fourths of the domestic phosphate production is from the Florida field, and since most of the phosphate from the Tennessee and Western fields is not processed, but used directly as electric furnace burden, this paper will concern itself almost entirely with water requirements for mining and processing ore from Florida. Figure 1 summarizes phosphate rock production for Florida vs. total United States production over the period 1947-1960.

Jan 1, 1962

By Gennaro Gerald Marino

In this paper the main subsidence- ground-structure interactions and an overview of the response of surface structures to subsidence ground movements are presented. The purpose of the paper is to augment our understanding for more effective application of available data as well as to highlight the essential site conditions in building response. The data presented general1 y applies to houses to structures up to 2-3 stories high and no more than several hundred feet in length. Superstructures of these buildings are supported by exterior (wood-frame or masonry) bearing walls with the interior floor loads carried by essentially one row of interior columns. This paper is not directed towards the response of tall buildings, steel-framed structures, or building types commonly associated with schools, churches, libraries, etc.

Jan 1, 1986

By D. S. Bird

Kennecott Utah Copper began a modernization program in 1986 that was aimed at expanding and updating mining and ore process facilities at the company’s Bingham Canyon copper mine and concentrator near Salt Lake City, UT. Major components of the project included installation of an in-pit crusher, a transfer conveying system and a new ore concentrator with a design capacity of 70 kt/d (77,000 stpd). The Copperton concentrator was commissioned in February 1988. The grinding circuit is one of its principal features. It consists of three identical lines, each with a 10.4-m- (34-ft-) diam x 4.6-m- (15-ft-) long semiautogenous grinding (SAG) mill and two 5.5-m- (18-ft-) diam x 8.6- (28-ft-) long ball mills. The SAG mills are driven by two 4.5-MW (each) (6000-hp) variable- speed dc motors through a clutch-pinion gear-ring gear assembly. The ball mills are driven by 4.1-MW (5500-hp) synchronous motors coupled through a typical clutch-pinion gear-ring gear system.

Jan 1, 1995

By B. A. Firth

Australia is the largest exporter of coking and thermal coal to the international market. This market has required that the coal being presented to the customer has a particular level and consistency of quality. In this context, the Australian industry has developed coal preparation practices that allow this criteria to be met while maximising the recovery of coal from the resource. This has required on- going developments in both coarse and fine coal cleaning technology over the past 30 years. Coal flotation has undergone a number of developments with regard to maximising recovery from the overall plant circuit. This includes innovative flotation circuits (split feed), methods of enhancing the use of reagents and control of pH. During the 1990s, there have been major changes in flotation as practised in Australian coal preparation plants. Columns have become the preferred technology for both greenfield developments and plant upgrades. This paper will outline the above developments with a number of plant examples and the reasoning that has driven the change. The ongoing research that is being carried out on new cells to optimise the overall fine coal circuit will also be discussed.

Jan 1, 1999

By J. Drelich, J. D. Miller

The wetting behavior of liquid polymers at solid surfaces and the adhesion forces involved at polymer-filler interfaces should always be considered in the preparation of high-quality polymer composites, including those made with mineral fillers. Spontaneous polymer spreading over the filler surface is a basic condition for the design of polymer-mineral composites. In this regard, the wetting and adhesion characteristics of polymer-mineral systems are reviewed. Based on this review it is clear that several aspects of wetting phenomena at mineral filler surfaces require further systematic study. Specifically, efforts should be made to determine the wetting characteristics of molten polymers at mineral-filler surfaces in greater detail. Also, the effects of mineral-surface contamination (including surface hydration) on wetting and adhesion phenomena need specific investigation. It is expected that an improved fundamental understanding of wetting and adhesion phenomena for polymer-mineral composites will provide the basis for further technological development.

Jan 1, 1996

By Jakub Nalaskowski, Robert Aranowski, Jan D. Miller, Jan Hupka

The polyolefins, mainly polyethylene and polypropylene particles, are used as an active filler material in polymer-polymer blends and are being used for the modification of asphalts to pro- vide for high-load, low-maintenance road construction. The stability of prepared blends depends on the interaction forces between polyolefinfiller and the matrix and/or between two polyolefin filler surfaces in the polymeric matrix. Various additives, especially surfactants, can be used to modify these interactions and improve the stability of polymer blends. In current research, direct force measurements between polyethylene (PE) surfaces in n-tetradecane, a nonaqueous solvent imitating the polymer matrix, were performed in the presence of lauric acid and dodecylamine using the AFM colloidal probe technique. Additionally, the zeta potential of polyethylene particles in the presence of surfactants in n-tetradecane was measured. The interac- tion forces between the polyethylene surfaces can be described as a combination of electrical double layer repulsion and steric repulsion between polymer chains extending into the n-tetradecane sol- vent. The addition of surfactant to the n-tetradecane was found to increase the repulsive force between the PE surfaces. The strongest repulsion was observed for dodecylamine. Additionally, the temperature efect on the interactions in n-tetradecane was studied. It was found that steric repulsion between the PE surfaces increases with an increase in temperature.

Jan 1, 2003

By A. Hayatdavoudi, E. Apande

Introduction Troublesome shales have plagued the petroleum industry for more than 50 years. Unstable boreholes have been experienced when drilled into shale formations; sane have been studied almost at the beginning of rotary drilling. A little progress has been made since then, but much is still to be learned. No simple solution exists so far, but good drilling practices combined with good mud practices have been helpful. It is well known that shales in general have a strong affinity for water, and when water is adsorbed, the stability of the shale section of a well is reduced; cohesive strength will be re- bed, properties will be altered and shale will generally expand and/or crumble. The amount of water a shale will adsorb depends on the characteristics of its clay mineral and the ionic concentration of surrounding fluid. Fluid loss and the resulting hydration of an unstable formation can lead to serious downhole problems. The rate of fluid loss depends greatly on the permeability of the deposited cake. In impermeable formations, however, there is no loss of fluid into the formation. As such, shale, because of its very low porosity and almost no permeability, could be termed impermeable. Yet there is strong evidence that shale surfaces are wetted by an invasion of fluid into the formation through microfractures and jointed planes. It is this wetting that causes the shales to swell and slough into the hole, resulting in problems such as increased mud volume and treating costs, bridges and fill-up, stuck pipe, overgauge hole, poor cement jobs and increased cement requirements, and logging and completion difficulties. Drilling operations have been defeated by severe shale problems, resulting in & hole being plugged and abandoned after several weeks of drilling. Shales are we1l known as being difficult and costly to drill. Numerous fishing jobs have plagued drilling operations, and the cost of reaming tight holes ad weighting up the drilling mud to control shale sloughing has been high. The concept of controlling water loss to stop sloughing was introduced in the 1920's. It was known-then that calcium in fresh water re- strains clay £ran excessive swelling (theory of osmosis) . This reinforced the belief that calcium-based muds such as lime, gypsum and calcium chloride should minimize hydration of clays. Lime muds were then introduced for this purpose and others in the 1930-1940 decade1. They were used for shale inhibition but were not effective. In an attempt to improve them, a special calcium-type mud beam popular during the 1950's. Hole enlargement continued and they too were considered ineffective. During & early 1960qs, papers were published claiming that shale swelling could be prevented by using high concentrations of chemical thinner called Chrane Lignosulfonate1. This began the era of highly treated lignosulfote muds. Unfortunately, the hole enlargement problem continued. During & mid-1960’s, oil based muds were used for the purpose of inhibition of shales. Not until 1966 did Mondshine2 suggest that the water phase be saturated with calcium chloride. The cost of using oil based mud was considered by most operators not worth the additional hole stability. The potassium chloride-polymer muds were also used in many fields in the United States and western Canada. The use of these muds has been claimed to prevent clay swelling by inhibition and encapsulation in sane areas of western Canada. They are also expensive and their ueneral application is still experimental. To reduce filtrate loss when sloughing shale becomes a problem during drilling is a reasonable practice. This study will investigate the use of cationic organic additives to mud to form a protective barrier between the shale - which are primarily composed of clays - and water that will keep water from entering the microfractures and will also prevent them from hydrating. In so doing, an understanding of modern clay chemistry and & dispersive properties of cationic additives in water based systems will be our most valuable tools. This study will also present and solve a mathematical model for simulating cation transport phenomena in fractured shales using the Framdlich equilibrium adsorption isotherm. The studies will analyze wellbore failure and stability as affected by cationic organic material.

Jan 1, 1986

By T. Emery, D. Sweet, J. Bourgeois, M. Gomez, B. Seymour, J. Feiler

For traditional underhand cut-and-fill mining operations, it can be challenging to design a suitable cemented paste backfill (CPB) mix that can meet the necessary strength requirements and yet maintain its ductility. In deep underground metal mines, the CPB must achieve a high enough strength to be competent under high stress conditions while also remaining ductile enough to withstand high strain from squeezing ground as underhand mining continues under backfilled stopes. To eliminate ground falls that result in injuries and fatalities, researchers from the Spokane Mining Research Division (SMRD) of the National Institute for Occupational Safety and Health (NIOSH) have partnered with Aerix Industries, a producer of concrete additives, to study the effects of foaming agents on the strength and ductility of CPB. This laboratory study examines the impact of various amounts of foam additive on the strength and ductility of CPB mix designs, using binder and tailings provided by Hecla Limited from the Lucky Friday Mine

Mar 2, 2022

By D. W. Fuerstenau

In mineral processing, the last century of the current millenium has been the century of froth flotation. The process did not result from fundamental research, but was developed over the years by empirical methods. In more recent years, our understanding of the fundamental principles of the flotation process have made significant strides. This paper reviews some of the historical perspectives of developments in flotation reagents, the development and application of experimental tools for delineating flotability and interfactial phenomena, advances in flotation fundamentals, and the development of flotation kinetics, both macroscopic and microscopic subprocesses. Through the application of surface chemistry, the flotation process has permitted economic utilization of a vast array of complex ores.

Jan 1, 1999

By Francis S. Kendorski

INTRODUCTION Drift design problems in caving operations are a re¬sult of the geologic factors contributing to the overall success of the system, of the engineering factors dictated by economic and technical considerations, and of ore production practices. Combining these factors, a rational underground sup¬port system of rock reinforcement, light steel channel section or welded wire fabric, and shotcrete can be de¬signed based on rock fracturing, rock load, abutment loadings, ground movement, expected repair and desired flexibility. The design concept uses the effect achieved by restraining, reinforcing, and maintaining some of the intrinsic strength of the fractured rock mass composed of interlocked blocks of intact rock and rock fractures. Three different examples of drift support design in hypo¬thetical mines using the caving system are given. Caving is a system of underground mining where ore is extracted by means of gravity after the ore body is allowed to fail by removing support from underneath. The rock mass of the ore body fractures and flows ver¬tically downward to let gravity do as much work as pos¬sible. Caving differs from many other mining systems in that blasting is used only to initiate the rock mass failure by removing the rock supporting the ore but not to break the ore itself. The initial movement of the rock mass dur¬ing failure and the consequent crushing and grinding during the continued movement serve to reduce the ore to particles of a manageable size, with only limited sec¬ondary blasting necessary. The broken ore is extracted from the bottom of the failed rock mass through funnels of some sort pre-excavated in the rock. Ore extraction must continue or the swell of the broken rock will even¬tually fill the cavity and stop further rock mass failure and movement. The excellent general discussion on block caving in the SME Mining Engineering Handbook (Julin and Tobie, 1973) adequately covers the principles and application of this type of underground mining. Many rock mechanics aspects of block caving have been covered by others (McMahon and Kendrick, 1969; Swaisgood, et al., 1972; Mahtab and Dixon, 1975; King, 1946) and will not be reviewed further. Maintaining the stability of production drifts is one of the most troublesome problems plaguing the mine manager in a caving operation. Many factors contrib¬ute to drift support problems, and identifying the causes of instability and producing a reasonable support design are two steps toward achieving stability consistent with the mine plan. This chapter sets forth a technique for the design of support systems for production drifts in caving opera¬tions. The basic support system elements employed are rock reinforcement, welded wire fabric, and shotcrete. Recognized as contributing to the design are the factors of rock load, additional load from mining activity, rock fracture characteristics, repair expected, and flexibility. It must be emphasized that the drift must first be stabilized as for a tunnel, and the additional strengthen¬ing for mining-induced loads cannot contribute to the initial premining stabilization, or the reserve of strength is used up. MINE PLANNING The efficient mine planning engineer not only must satisfy the economic, human, and environmental aspects of his task but must also consider the mechanical con¬sequences of his plan. The problems created for the mine by placing parallel drifts too close, by crossing drifts on different levels with inadequate, if any, separa¬tion, and by installing connections and crossovers in the haulage plan without regard for the effective spans cre¬ated, are only a few of the problems a mine planning engineer can create for himself and the mine. The effect on immediately adjacent mine areas when an area is caved is important to drift design because the removal of vertical support from a rock mass causes the weight of that rock mass to be shifted elsewhere. The adjacent rock mass will carry this load and reach a new equilibrium with the applied stress. The advancing front of stress increase that results from caving (and many other mining systems) is generally called the abutment load and is the increase in stress over the gravity or tec¬tonic stress that already exists, as shown in Fig. 1. In general, the abutment load will be similar in nature to the stress change found around an opening in rock and will be taken as causing an increase in the vertical prin¬cipal stress, due to an approaching caving boundary, so that

Jan 1, 1982

By R. S. Farinato

Thionocarbamate flotation reagents have enjoyed a niche position in the recovery of copper sulfides and activated sphalerites since their introduction in the mid 1950's (Harris, 1954). Thionocarbamates containing an allyl group (-CH2- CH=CH2), introduced recently Lewellyn, 1985; Nagaraj, 1988; Avotins, 1991), are used commercially as collectors for copper sulfides and activated sphalerite. Laboratory flotation tests and plant usage have demonstrated that allyl-containing thionocarbamate collectors exhibit certain unique properties that distinguish them from the corresponding dialkyl thionocarbamates. Spectroscopic (FTIR, XPS) and wettability studies of N-allyl iso-butyl thionocarbamate (AIBTC) and its saturated analog N-propyl iso-butyl thionocarbamate (NPIBTC) adsorbed on copper at pH 9 were performed in order to investigate whether there were any fundamental reasons for these differences. Flotation tests were carried out on chalcocite, copper ore and an activated sphalerite.

Jan 1, 1993

By R. L. Pozzo, I. Iwasaki

A previous investigation showed that corrosion currents estimated from polarization curves for the pyrrhotite-grinding media system under abrasion correlated well with corrosion currents estimated from marked ball wear test data by applying Faraday's law. Freshly abraded metal debris were magnetically attracted to pyrrhotite and lowered the rest potentials of the mineral particles, thereby affecting the corrosive wear. The investigation was extended to explore the interactions between a non- magnetic sulfide mineral, pyrite, and abraded metal debris and their effects on the corrosive wear mechanism. The electrochemical behavior of a three-

Jan 1, 1988

By Charles P. Lazzara, Alex C. Smith, Mark W. Ryan

The U.S. Bureau of Mines conducted a study to evaluate the effect of ventilation on the performance of automatic sprinkler systems in extinguishing wood crib fires. Experiments were conducted at airflows of 0, 0.76, 1.5, 2.5, and 4.1 m/s. Two experiments were conducted at each airflow, using 74° C fast response pendent sprinklers in one experiment and 74° C fast response horizontal sidewall sprinklers in the other experiment. In the experiments at airflows of 0 and 0.76 m/s, sprinklers were located directly above the fire and 2.4 m upstream and downstream of the fire. The sprinkler directly above the fire was the only sprinkler to operate with no discernible difference in the suppression capability of the pendent and horizontal sidewall sprinklers. In the experiments at airflows of 1.5 and 2.5 m/s, sprinklers were located directly above the fire and 2.4 and 4.8 m downstream of the fire. The sprinkler located 2.4 m downstream was the only sprinkler to operate with the horizontal sidewall sprinkler being more effective in extinguishing the wood crib fire. The average response times of the sprinklers at airflows of 0.76, 1.5, and 2.5 m/s were 3-1/2 times the average response time of the sprinklers at 0 m/s. The results of this study will help enhance the safety of the nation's miners.

Jan 1, 1993

By S. A. Bortz

IIT Research Institute has initiated several multi-sponsored research programs. In this paper the methods for developing four of these programs are discussed. In general, a broad area of investigation must be proposed to interest a spectrum of different industries. The work must not touch upon proprietary data and will probably involve a number of scientific disciplines. Thus, the problem to be solved will attract sponsors who need to know more about the area under study but do not wish, as a single company, to commit the resources required to obtain the necessary know-how for their needs. The paper draws on the background of four IITRI multi-sponsored projects: Size Reduction, a study of grinding of material to reduce their particle size; Melt-Formed Ceramics Research, a method of producing dense, polycrystalline ceramics using glass forming methods; Binders in Ceramic Processing, which addresses the problems associated with the use of organic aids for ceramic processing; and a Study in Air Pollution Technology, a program to review and assess pollution control equipment for current and future applications.

Jan 1, 1984

By David L. Bradfield

This paper covers the development of the Yeelirrie Uranium Project from the discovery of the Yeelirrie deposit in 1970 to the present time, with emphasis on the mining, processing, and environmental requirements of the project. The Yeelirrie Uranium Project is managed by the "Yeelirrie Uranium Joint Venture Partnership", which, when formed, consisted of Yeelirrie Development Company Pty., Ltd., Urangesellschaft, Australia Pty. Ltd. and Esso Exploration and Production Australia Inc. The Yeelirrie Uranium Joint Venture Partnership holds mineral claims over the Yeelirrie uranium ore deposit in Western Australia. This deposit encompasses some 35 million tonnes of ore containing in excess of 50,000 tonnes of uranium as U308. Agreement has been reached with the State of Western Australia to mine and process the ore to produce uranium ore concentrate. The Project scope provides for an open-cut mine, alkaline leach hydrometallurgy plant, power plant, township, airstrip, access roads, community services and utilities. The Yeelirrie Uranium Project described herein has progressed through the stages of exploration, mine evaluation, process testing, project scope definition, environmental approval, Pilot Plant operation, preliminary engineering and the publishing of a definitive Project Feasibility Study. This article summarizes the project development through the above stages.

Jan 1, 1984