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By P. Somasundaran, J. T. Kunjappu

Spectroscopic techniques are becoming increasingly popular for characterizing the interior of adsorbed layers of surfactants and polymers at solid- liquid interface as well as in the identification of com- pounds on mineral surfaces. This review encompasses the application of fluorescence and ESR spectroscopic techniques to reveal the microscopic environment of the adsorbed layers of surfactants and polymers on minerals with a special reference to the adsorption of anionic surfactants (e.g., sodium dodecyl sulfate) and polyelectrolytes (e.g., polyacrylic acid) at positively charged mineral (e.g., alumina) - water interfaces. Finally, the utility of XPS and auger techniques to identify the surface elemental composition of different mineral species has been related to their flotation efficiency.

Jan 1, 1987

By A. L. Coello Velázquez

The subject of this paper is particle population balance models (PBM) that describe mineral impact crushing behavior; it is mainly concerned with the selection and fragmentation distribution function due to their importance in this context. The data obtained by Datta (1999) by applying impact pendulum testing to single limestone particles, used by Austin (2002, 2004a and 2004b) to obtain the principal parity of fragmentation functions, were processed in order to compare them with the results of other authors, such as Nikolov (2002 and 2004) and Vogel and Peukert (2003 and 2005) so as to increase knowledge of impact crushing. From this data it has been possible to obtain the performance models of the principal parameters of fragmentation function, thereby reducing the number of experiments necessary to model the impact crushing process. The authors also propose a simplification of the selection function model posited by Austin (2002).

Jan 1, 2011

By Stephen H. Stow

Economically important heavy minerals have been studied in the sediments of offshore Alabama and Mississippi. Sandy samples have been collected from a 200 square mile area from Dauphin to Horn Islands. The minerals concentrate in sediments under 10-35 feet of water and may reach 2.4% by weight. The distribution of total heavies is related to the hydrodynamics of offshore Alabama-Mississippi; the greatest concentrations are in the Gulf where the longshore current is diverted from its westerly flow. Preliminary observations indicate that the distribution of individual minerals can be correlated with wave energy, particle size, specific gravity, and morphology of the mineral grains. The coarser, lighter minerals--kyanite, sillimanite and staurolite--are concentrated in relatively low energy areas in the Mississippi Sound and at the end of Dauphin Island in the Gulf; maximum concentration for each is 34.5%, 6.0% and 43.2%, respectively, of the heavy minerals. The smaller, more denseminerals--ilmenite, rutile, leucoxene, zircon and monazite--are concentrated in high energy areas in the Gulf; maximum concentration for each, respectively, is 42.0%, 5.9%, 9.652, 10.7% and 1.3% of the heavy minerals. On the basis of a minimum concentration of 1% heavy minerals, two areas have been identified and the total amounts of different minerals have been calculated to a depth of 25 feet of sediment. The data are preliminary and in no way indicate recoverable reserves, but they do show that on the order of 20 million tons of heavies exist. These deposits should be termed "indicated resources".

Jan 1, 1975

By C. Bazin

The fundamental error associated to the sampling of heterogeneous ore particles is unavoidable and can only be minimized by an adequate selection of the sample mass and/or size reduction of the sample before division into sub samples for testing or assaying. The preparation of ore batches to carry out the mineral processing evaluation of an ore is a sampling process. The fundamental error associated with the division of the ore into batches is responsible for the differences in the composition of the batches. This paper attempts by various means to assess the reproducibility of the gold content of test batches prepared from a gold ore sample. The results of the investigation shows that for fine gold grain sizes the variability in the composition of the batches is less than that predicted by Gy?s formula and that the gold grain size is a strategic information in the assessment of the gold content variability of test batches.

Feb 23, 2014

By S. A. Elmquist

Research activities performed by Cleveland-Cliffs Research and Hibbing Taconite plant personnel during the last decade have resulted in the development of an improved autogenous mill grinding circuit. Minus one (1) inch autogenous mill trommel oversize material, con-sidered to be a critical size, is magnetically cobbed and then crushed to 100% minus 3/8" prior to reentry into the feed end of the mill. Autogenous mill capacity increases, up to 25%, have been measured in pilot plant tests using this approach and are also anticipated for the Hibbing Taconite concentrator which presently has reached a 15.5% improvement.

Jan 1, 1994

By J. A. Bradbury

N. A. Degerstrom, Inc. has constructed and operated a processing plant approximately five miles north of Soda Springs, Idaho for processing a byproduct phosphate treater dust from Monsanto's elemental phosphorus plant, also located in Soda Springs. The plant is designed to produce agricultural-grade phosphoric acid, gallium, and silver. The design capacity of the plant is 54.4t (60 st) of treater dust per day, which can produce 16,326t (18,000 st) of phosphoric acid, 6,600 kg of gallium, and 6,033 kg (194,000 oz.) of silver per year.

Jan 1, 1993

By B. Bag

Saturated and unsaturated fatty acids are used in the flotation of iron values present in iron ore. Among the several fatty acids, oleic acid and its sodium salt are widely used. To substantiate the flotation results, the quantum chemical calculations of a few such acids have been carried out by adopting the semi-empirical AM1 method. These acids have been further optimized in the presence of an iron atom. The electronic interaction of the polar carboxylic head group of oleic acid with the iron atom is higher compared to the other acids. The numerical results support the flotation behavior of iron ore with oleic acid. Key words: Iron ore, Flotation, Fatty acids, Quantum chemical calculations, Semi-empirical AM1 method

Jan 1, 2009

By Stuart Ratcliffe, Denis Kidby

The development of Vitrokele™ Technology over the last 10 years is reviewed with reference to mine site piloting and com­mercial applications. The first mine site piloting was conducted in Australia in 1989 followed by a further six continuous site trials in Australia, Canada and the USA. These major pilot plant studies are complemented by over 50 laboratory scale batch and pilot testwork programmes. The first commercial plant using Vitrokele™ Technology was the Connemara project commissioned in Zimbabwe in 1995. Subsequent to this, three commercial scale projects have been designed using Vitrokele™ to recover precious metals, base met­als and cyanide. The various projects are discussed with relation to the differ­ing flowsheets applied to each particular case.

Jan 1, 1998

By B. J. Arnold

During the past three years, coal samples covering a range of coal rank, ash content, size consist, grindability, and moisture content have been tested for their flow properties using a triaxial shear tester that measures the unconfined yield strength in a compressed sample of coal. The ratio of this unconfined yield strength to the sample bulk density is part of the equation used by handling system manufacturers to calculate the critical arching or critical ratholing diameter needed to ensure that coal will flow from bunkers or bins. This ratio also serves as an index to compare the flow tested. To test the applicability of the index to predicting problems with coal flow, a series of tests were conducted at CO Inc.'s Coal Quality Development Center (CQDC) in Homer City, Pennsylvania. Tests covering ranges in size consist, moisture content, and ash content were conducted by first filling a small two-ton bin with coal and then emptying the bin at a pre-set discharge rate. The actual discharge rate from the bin under the various conditions tested was measured. Samples of the coal discharging from the bin were collected. One sample was analyzed for ash, moisture, and size consist; another sample was sent to the Iowa state University for trivial shear tests (supplying an index measurement). Actual flowability results from the bin were then compared to the measured index to determine the applicability of the handleability index in actually predicting coal flow problems. This paper describes the correlation between handleability index and bin flow and explains the next stages of the project.

Jan 1, 1992

By B. J. Arnold

Prior laboratory work has demonstrated -that much of the fine ash-forming minerals entering a flotation froth are there as a result of water carry-over from the bulk contents of the flotation cell (Arnold and Aplan, 1986a). Using a bank of four 300 cu ft WEMCO flotation cells cleaning a well-liberated Lower Kittanning seam coal, test results show that the sulfur and ash content of the froth is directly related to the water content of the froth (or inversely related to the percent of solids in the froth). Reagent changes which result in a watery froth produce a higher ash content in the froth. A direct comparison of laboratory and plant results show that the standard laboratory flotation test produces a product higher in sulfur and ash than that produced in the plant. Caution should be exercised when extrapolating laboratory test results to the plant situation. A method of estimating coal flotation product quality in the plant based on laboratory tests is given.

Jan 1, 1990

By J. D. Goodrich

Success of The Carter Mining Company's safety program can be primarily attributed to "total immersion" of all operating and staff personnel in program design and implementation. Currently, the Company operates two surface coal mines in Campbell County, Wyoming. Total employment is about 440 and current annual production is about 15 million tons. The safety program has evolved from one which was administered primarily by staff personnel (the Safety Department) to one which requires active participation by line management and operating personnel. Lost time accident frequencies have declined from a high of 1.86 per 200K hours worked in 1978 to zero in 1982. Reportable accident frequencies have declined from slightly over 5 to slightly over 2 during the same period. Analysis of program results indicates that the most important achievement by the company has been to gain strong commitment to safe operation by all employees. It is important that program format and content be frequently changed and modified so that: 1) The requirement for safe job performance is communicated well and often, 2) The safe job performance message is trans- mitted in new and interesting ways, and 3) Operating personnel participate in design and implementation of the program.

Jan 1, 1983

By Fred H. Lightner

The feasibility evaluation of the Borealis project of Houston International Minerals Corporation (HIMCO) was initiated in October of 1980. The operation of the Borealis Mine and heap leaching plant began in late 1981. In order to achieve the rapid development schedule several items were necessary: 1) Pre-planning of environmental requirements and early study of key issues. 2) Adoption of conservative design criteria. 3) Coordination and cooperation between HIMCO and regulatory agencies. 4) Adoption of specialized engineering and construction procedures. 5) Careful evaluation of owner project management philosophy.

Jan 1, 1982

By Jeffrey J. Daniels

Advances in borehole geophysical research for mineral assaying, and remote detection of mineralization away from the borehole. Nuclear activation measurement research has provided accurate in situ assays of economic metals with neutron-gamma activation, using a high resolution intrinsic-germanium detector. Although nuclear activation analysis is the present "best-hope" for obtaining in situ assays for some elements, gamma-gamma and magnetic susceptibility measurements can provide accurate assays for lead-zinc and magnetite, respectively. Borehole optical spectroscopy and x-ray fluorescence are being investigated as possible in situ assaying techniques for some minerals. More laboratory and field calibration research is needed before nonlinear complex resistivity (NLCR) can be routinely used as a quantitative assaying tool. Field tests have shown that variations in the local geologic environment can affect the quantitative accuracy of assay values from downhole NLCR measurements. Deeply penetrating borehole geophysical methods are increasingly being used for mineral exploration as drilling costs and exploration have increased. Borehole electrical measurements have been shown to be useful for detecting conductive orebodies that are not interesected by a drillhole. Hole-to-surface resistivity, and surface-to-hole time-domain electromagnetics are demonstrated to be particularly effective for defining mineralized zones in a massive sulfide environment. Borehole gravity meters and three-component magnetometers have been developed and should prove useful for defining geologic anomalies away from the drillhole.

Jan 1, 1985

By Arthur R. MacPherson

Primary autogenous grinding has been in general use for somewhat over 20 years. During this period there have been many highly successful plants built on this principle, while some others have had problems such as: 1. Not performing as predicted from test work. 2. Highly fluctuating tonnage rates. 3. Mechanical problems. 4. High liner wear. Many of the problems with commercial autogenous mills have resulted from improper sampling and testing of the ore during the development period. It is recognized that the fully autogenous mill is very sensitive to any changes in grindability which may occur in the feed to such a mill. The semi-autogenous mill is somewhat less sensitive, but large swings in grindability of the feed require adjustment of ball charge and this cannot be easily accomplished in a short period of time.

Jan 1, 1976

By Atta Ur Rehman, Kwame Awuah‑Offei

This paper examines the effect of bucket geometry (cutting blade profile, floor profile, and blade thickness), speed, motor power output, and muckpile particle sizes on bucket penetration and draft for rubber tire loaders. The work uses a 1:16 scaled model of a load-haul-dump in full factorial experiments to examine the effect of the variables on penetration and maximum draft. The results show that speed and motor output are positively correlated to penetration and draft; muckpile particle size is positively correlated to penetration and negatively correlated to draft (p < 0.0014). The results show that buckets with a semi-spade cutting nose profile yield the highest penetration (mean 118.30 mm) followed by those with the spade (mean 108.88 mm), which also yield higher penetration than those straight blades (mean 95.19 mm). Bucket floor profile and blade thickness had no significant effect on penetration or draft. Also, we determined that increasing the speed and motor power output, simultaneously, can reduce bucket penetration. Thus, operators should not waste energy for no additional gain or even loss in bucket penetration. Also, the work finds speed and motor power output each combine with muckpile particle sizes to affect bucket penetration. This research furthers our understanding of the effectiveness of different bucket geometries in improving penetration and reducing draft for rubber tire loaders.

Oct 29, 2021

By P. Zhang

A 1989 FIPR characterization study of the future phosphate resources in Florida showed that MgO would be a problem with both the pebble and concentrate as phosphate mining moves deeper. Since the ratio of concentrate to pebble will become higher and higher in the future, reducing Mg content in the concentrate by a small margin would allow blending of a large portion of the high-dolomite pebble. This research was conducted based on that logic. The following six approaches were tested for reducing MgO content in the flotation concentrate: (1) Adding a dolomite depressant in the rougher flotation step; (2) Dolomite flotation on the rougher concentrate with and without grinding; (3) Dolomite flotation on the cleaner concentrate with and without grinding; (4) Scrubbing the flotation feed; (5) Scrubbing the rougher concentrate; (6) Scrubbing the cleaner concentrate. Successful methods include adding a dolomite depressant in the rougher flotation, dolomite flotation on the cleaner concentrate with grinding, and scrubbing the cleaner concentrate in quartz sand. These techniques could reduce MgO content in the final concentrate by 20-40%. The flotation process could achieve a concentrate with the lowest MgO content, but it is the most expensive approach. Adding a dolomite is inexpensive and easy, but the effect is limited. Overall, scrubbing may be the most promising technology for this purpose.

Feb 23, 2014

By Gamal Rashed, Zorica Radakovic-Guzina, Khaled Mohamed

"Underground coal mines use mechanical bolts in addition to other types of bolts to control the rib deformation and to stabilize the yielded coal ribs. Limited research has been conducted to understand the performance of the mechanical bolts in coal ribs. Researchers from the National Institute for Occupational Safety and Health (NIOSH) conducted this work to understand the loading characteristics of mechanical bolts (stiffness and capacity) installed in coal ribs at five underground coal mines. Standard pull-out tests were performed in this study to define the loading characteristics of mechanical rib bolts. Different installation torques were applied to the tested bolts based on the strength of the coal seam. A typical tri-linear load-deformation response for mechanical bolts was obtained from these tests. It was found that the anchorage capacity depends mainly on the coal strength. Guidelines for modeling mechanical bolts have been developed using the tri-linear load-deformation response. The outcome of this research provides essential data for rib support design.INTRODUCTIONThe design of rib bolting in U.S. coal mines is based on a trial-and-error process, which is insufficient to eliminate injuries and fatalities caused by rib falls. In the last 10 years, rib failures have resulted in 17 fatalities, representing 52% of the ground-fall fatalities in underground coal mines in the United States (MSHA, 2018). Recently, NIOSH researchers surveyed 90 sites in 14 underground coal mines in the Eastern United States and found that 11 mines are bolting coal ribs, with 4 of those mines using the conventional mechanical bolts and the others using fully-grouted bolts. NIOSH researchers are developing an engineering design procedure for rib support. Pull-out test programs for mechanical and grouted rib bolts were conducted to understand the rib control mechanisms of rib bolts. Only the test results of mechanical bolts are presented in this paper.Mechanical bolt (or point-anchored bolt) is a tensioned bolt anchored down the borehole with a mechanical expansion shell or a resin-grouted medium (Peng and Tang, 1984). The mechanical anchor bolt consists of a plug, a shell anchor, a headed bar with the top end threaded, a bearing plate, a hardened washer, and occasionally a friction-reducing washer. The shell anchor can be either standard or bail type (Figure 1). The standard type shell is held in place by a nut, while the bail anchor uses a strap to hold the shell in place (Peng, 2008). The diameter of the bar is generally 16 mm (? in) for the #5 bolt or 19 mm (6/8 in) for the #6 bolt. The diameter of the hole that the bolt is inserted into must be carefully controlled, since an oversized hole can result in poor anchorage (Moss, 1971). The anchorage is obtained by applying torque to the bolt head, which in turn pulls the plug down in the shell and expands the serrated leaves against the sides of the hole-wall. In the resin-grouted anchor, the resin replaces the mechanical expansion shell at the end of the hole. The anchorage is achieved by bonding between the resin, bolt, and the hole-wall."

Jan 1, 2019

By Ronald J. Roman

A mathematical model was developed for the grinding and flotation section of Union Carbide&apos;s Bishop mill and this model was used to indicate how variations in grind, retention time, and calcite and fluorite content effects the mill capacity, tungsten units produced, and the grade and recovery of the scheelite concentrate. A model such as this is a starting point in determining the economic optimum running condition for a mining and milling operation and an example of this is given.

Jan 1, 1969

By A. H. Kaksonen

Numerous reactor designs for biological sulfate reduction have been reported. Fluidized-bed bioreactors (FBR) can efficiently retain biomass and allow high mass transfer and reaction rates. This work reviews the development of various sulfate-reducing FBR processes for treating acidic metal- and sulfate-containing waters and recovering metals from bioleaching liquors. The FBR process performance was evaluated with continuous flow experiments under various operational conditions: fluidization rates, influent pH values, metal, sulfate and salt concentrations, hydraulic retention times, electron and carbon sources, and temperatures. Substrate utilization and sulfide inhibition kinetics were determined with batch FBR-kinetic experiments. An artificial neural network (ANN) model was used to predict the performance of the FBR. Sulfate-reducing bacteria (SRB) were characterized in FBRs with molecular and culture-based approaches with the aim to gain a better understating of the bioprocesses. Based on the studies, FBRs are well suited for the combined removal of metals, acidity and sulfate from water.

Jan 1, 2010

By R. Brantley Sudderth

There are three broad categories in which most solvent extraction technology can be distributed?: 1) reagents, 2) equipment, and 3) systems. Reagents which are now used in commercial solvent extraction plants are of many chemical types, and each possesses certain properties which make it more economically desirable than another alternative. The equipment which is&apos; used in solvent extraction plants for contacting the organic and aqueous phases and separating the same is varied. Most common to the industry is the mixer-settler unit which in itself, can be of varied design; but many new innovations in contacting and separating equipment have been recently introduced or are :now being studied. Each specific solvent extraction application will often dictate the type of contacting and separating equipment used. Obviously, the trend is toward smaller less expensive equipment which reduces the often expensive organic inventories necessary for most solvent extraction plants. The current thrust of .investigations in ancillary equipment is usually aimed at recovering organic from solvent extraction sludges or from aqueous streams exiting the process.6 This type of equipment helps to reduce the total organic losses from solvent extraction plants and thus reduce the operating costs. The term "systems" in solvent extraction applies to the manner in which a solvent extraction process is carried out. This manner is usually dictated by the properties of the reagent which is used, and it involves a tailoring of the equipment or the process flowsheet. Some of the things which can be tailored are: 1) The aqueous media -whether acidic or basic and what type of acid or base 2) Counter-current or single stage (co-current) contacting 3) EMF or pH control 4) Organic "crowding" alternative 5) Heating or cooling process streams Regardless of the type or extent of tailoring, efforts to do this are usually a result of the low cost of solvent extraction as a unit process.

Jan 1, 1977