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By T. K. Perkins, L. R. Kern, R. E. Wyant

Many factors influence the results of hydraulic fracturing to stimulate well productivity. Most of these factors have been studied and their effects discussed in the literature. However, the movement of sand through the crack during fracturing has received little consideration. Exactly where the sand goes in the fracture, how it gets there, and how this might influence results have not been studied, judging from published reports. To get an answer to some of these questions we have studied sand movement through a simulated crack segment in the laboratory. Although the work is preliminary, we have answered some questions about sand movement in a semiquantitative sense. We are reporting our results at this time in the hope of stimulating interest and further study in this important aspect of fracturing. LABORATORY EXPERIMENTS Fig. 1 is a schematic diagram of equipment used in this study. A segment of a vertical crack 0.25-in. wide was formed between two Plexiglas plates, and movement of sand in fluid through the crack was observed under various conditions. Sand and fluid were injected into the crack at constant rates. The top and bottom of the crack were closed so that the fluid flowed horizontally. Because of gravity most of the sand settled to the bottom before moving very far through the crack. If the fluid velocity exceeded a certain critical value, then all the sand injected was washed on through the crack even though it had settled to the bottom. When the fluid velocity was less than this value when sand injection was started, most of the sand which settled in the crack remained in place until enough of the area open to fluid flow was blocked by the settled sand to increase the fluid velocity to the critical value.. At this point all injected sand moved on through the crack even though it settled to the lower portion of the moving fluid section. All sand previously settled remained in place. When fluid velocity was increased at this paint by increasing fluid injection rate (without also increasing sand injection rate), some of the previously settled sand was washed out until enough area was open to flow that the velocity dropped to the critical value. Conversely, when the fluid velocity was decreased by decreasing the fluid injection rate (without changing the rate of sand injection), additional sand would settle until the critical velocity was again attained. In short, the critical velocity is an equilibrium value which the system will automatically seek, if possible. The equilibrium (or critical) velocity was measured under several conditions. The results of these measurements are shown in Pig. 2 where the equilibrium velocity is shown as a function of the amount of sand injected per minute. The points falling in the shaded band shown in Fig. 2 were obtained with water. The higher viscosities were obtained by adding CMC (carboxymethylcellu-lose). Data indicate that the equilibrium velocity is not very sensitive to sand size or transport fluid viscosity, or to sand injection rate (except at very low rates). Points connected by the solid CUrve in Fig. 2 were obtained with water and 20- to 40-mesh steel shot. The equilibrium velocity is apparently fairly sensitive to difference in density between particle and fluid. Only one run was made with a gelled fluid and that was gelled water at zero sand injection rate as shown in Fig. 2. (Measurements of equilibrium velocity at zero sand injection rate were made by filling the crack

By Y X. Xue, J Pan, D Q. Zhu

In order to reveal the correlation between the fundamental sintering characteristics of iron ores and their real sintering behaviours, a comprehensive evaluation index is proposed based on the measurement of four high temperature indexes, ie assimilation temperature, liquid phase bonding strength, liquid fluidity and calcium ferrite formation percentage, and the sintering pot tests of single ore fines and their blends. The results show that both the lowest assimilation temperature and liquid fluidity of ore blends appear to be the linear superposition of those of single iron ores except for the liquid phase bonding strength and calcium ferrite formation percentage. Furthermore, the tumble index of the sinter product obtained from blended iron ores also corresponds to a linear superposition of that of single ores, but not for the solid fuel rate and productivity. The comprehensive strength index YT exhibits a credible linear positive correlation with the four high temperature reactivity indexes, whereas the comprehensive productivity index YP possesses a lower correlation with the four high temperature reactivity indexes. The comprehensive strength index YT developed can predict the tumble index of the sinter product quite well, but the comprehensive productivity index YP cannot be used to evaluate the productivity effectively.CITATION:Zhu, D Q, Xue, Y X, Pan, J and Shi, B J, 2017. Correlation between high temperature sintering characteristics and sintering behaviours of iron ore fines, in Proceedings Iron Ore 2017, pp 123–132 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By D. A. Elgillani, M. C. Fuerstenau, J. D. Miller

Adsorption of lead and ferric iron on quartz and alumina is presented as a function of pH. Only the hydrolyzed species of these metal ions, FeOH++ and PbOH+, adsorb significantly on each of these minerals. Zeta potentials of quartz were measured as a function of pH in the presence of various additions of aluminum, lead, and magnesium salts. Sign reversal occurs at the pH values where significant concentrations of hydroxy complexes are formed. Models of adsorption are presented in the absence and presence of collector. The mechanism of adsorption of metal and collector species in the activation of nonmetallic minerals is still the center of considerable discussion in spite of the extensive study given this system. Until recently, the view was widely held that hydrated metal ions were responsible for this phenomenon. This fact is surprising, since it had been shown that the pH range in which flotation is effected corresponds to that in which metal ion hydrolysis occurs.' Additional support of this concept was pro vided by the work of Wolstenholme and Schulman in another system.' Later work has shown that hydroxy complexes of metal ions are the active species. These studies have also indicated that basic aqueous complexes of metal-collector may be necessary for flotation.3-7 Depending on the molecular weight of the collector, formation of these complexes may occur before or after precipitation of the metal-collector salt has occurred. Ion pair formation can occur when low molecular weight collectors are involved because relatively high concentrations of metal hydroxy complex and collector can be present in solution before precipitation occurs. This is not the case when high molecular weight collectors are used. A model of aqueous complex adsorption has been presented6,7 in which it has been assumed that adsorption occurs by the formation of water from adsorbed hydroxyl and hydrogen of the hydroxyl contained in the complex. Other authors8 have suggested that hy-droxy complexes are involved in these systems but that collector adsorption occurs by replacement of the hydroxyl of the adsorbed metal hydroxy complex with a fatty acid anion. All of these investigations have involved mineral surfaces that were negatively charged so that it is not possible to state with certainty whether hydrated metal ions or hydroxy complexes are the active species in this system. Use of a positively charged mineral should be helpful, however, since the hydrated metal ion will be repelled from this surface. On the other hand, if the hydroxy complex adsorbs by splitting out water, surface charge should have no effect because of the free energy decrease that the system will experience when water is formed. In this regard, sapphire is well-suited for study, since its surface is positively charged until approximately pH 9. Electrokinetic studies of quartz in the presence of various metal ions should also be useful in establishing the mechanisms of adsorption in these systems. That is, if the hydroxy complexes adsorb by water formation, drastic changes in the zeta potential should occur in the pH range in which hydrolysis occurs. In this view, adsorption of ions of widely different hydrolysis characteristics on both sapphire and quartz was measured. In addition, zeta potentials of quartz were measured as a function of pH in the presence of various metal ions and compared with flotation responses obtained under similar conditions. Experimental Materials and Techniques Reagent-grade aluminum, ferric and magnesium chlorides, and lead nitrate were used in this investigation. Adjustments in pH were made with reagent-grade HCl or KOH. Conductivity water, made by passing distilled water through an ion exchange column, was used in all of the experiments.

Jan 1, 1971

By Mary Cocklan-Vendl

Regulatory processes associated with development of a world class lead-zinc mine, Red Dog Mine, in northwestern Alaska were reviewed and evaluated. Informal interviews with key project personnel, consultants, and agency field and permitting specialists provided perspective on the regulatory successes and failures of the project. Due to potential impacts to air quality, water quality, wetlands, and National Park lands, an Environmental Impact Statement was required. By developing a comprehensive baseline of information on the existing environment to aid in minimizing impacts during project siting/design and through regular coordination of evolving project plans with regulatory agencies, the mine developers were able to acquire necessary permits in a timely and cost effective manner. The only major exceptions occurred when inadequate information was collected on dispersal of airborne particulates, rates of surface water run-off, and groundwater quality. These deficiencies resulted in the need for design changes, unscheduled construction, additional environmental monitoring costs, and delays in issuance of the NPDES permit.

Jan 1, 1992

By G. F. Butterworth

The metallographic structures most frequently encountered in rifle barrels, and which are illustrated by the accompanying photomicrographs, fall naturally into two groups, distinguished by the method used to, produce in the stock a physical condition having the requisite properties. The fist group consists of "rolled" barrels; that is, barrels subjected to hot working by rolling in or near the critical range. In the second group, the stock, which is smaller in diameter than the first, is upset to form the butt end and is then heat treated by giving it a quench and a draw. These barrels will be referred to as " heat-treated " barrels. The structure of the rolled barrels resembles closely that of the same steel after annealing. There is the same network of excess ferrite outlining the grain boundaries, but the grains themselves are composed of sorbite rather than pearlite. The grain size is closely related to the rolling temperature. The critical-point curves of this grade of steel, which is approximately 0.50 to 0.60 per cent. of carbon and 1.00 to 1.30 per cent, of manganese, show a single very pronounced point between 1300" and 1350" F. (704" and 732" C.). Barrels rolled within this temperature range give an exceedingly fine grain, shown in Fig. 1. In fact, the grains may be so fine that, at a low magnification, they may be confused with the heat-treated structure shown in Fig. 6. A magnification of 500 diameters, however, will always resolve a rolled barrel into the characteristic structure shown in Fig. 2. As the temperature is increased, the grains are found to be larger. If, on the other hand, the rolling temperature is below the critical range, the structure previous to rolling will not be obliterated, the only effect of rolling being to elongate the coarse sorbite grains in the direction of rolling, Fig. 3. This distortion is greatest at the muzzle. Heat-treated barrels are quenched in oil from above the critical range, which should give a martensitic structure, Fig. 4, but the presence of some troostite in the martensite is frequently noted when the quench has not been sufficiently drastic, Fig. 5. The structure brought about by the subsequent draw is not so striking, though quite as typical. It is sorbitic or sorbito-pearlitic, and under a low magnification appears almost homogeneous, as in the case of fine grains of pepper and salt well mixed together, Fig. 6. This structure is substantially the same for all

Jan 1, 1920

By Henry C. Meeves

The Bureau of Mines investigated the silver production potential of the Leadville (California) mining district, Lake County, Colo., in 1966-67. The mining history of the district, the ground conditions encountered in mining, and the mine-support methods used are reviewed. The drainage problem is discussed in detail. An initial objective was to establish the existence of potential silver resources minable by low-cost open-pit methods, particularly in the silver-bearing manganese halos surrounding the major deposits. The report concludes that under present conditions, development of the deposits in the area is not economically feasible; however, a pioneer rotary noncore drilling program demonstrated that this type of exploration is technically feasible. Potential reserves of silver and associated metals are estimated. Possible mining methods for recovery of the reserves are discussed. Future production possibilities from the various subareas of the district are analysed, considering optimum operating size. Consolidation of small individual holdings for unit operation is recommended. Type of operation, amount of rehabilitation, size and type of concentrating plants required, drainage and other mining problems, and metal price trends are discussed as they bear on economic feasibility of development.

Jan 1, 1970

The zinc-lead lode at Rosebery, on the West coast of Tasmania, has a total length of over 4000 ft. It consists of five elongated lenses parallel to the foliation planes of the quartz sericite schist, and is situated at the junction of the quartz sericite schist and a thin belt of slate. The lenses consist of massive, fine grained sulphide ore, with small amounts of quartz, barite, sericite and chlorite, and they terminate in masses of low grade ore. The gangue minerals increase in quantity in the low grade ore which includes small quantities of the manganese garnet, spessartite. The schist walls of the lenses are in places impregnated with lode minerals to a degree sufficient to permit them to be regarded as economic ore.The ore-bodies have developed from incoming mineral solutions by the replacement of the quartz sericite schist and are localised where the ore solutions have been confined by a relatively impervious slate band. The early stages of replacement of the schists are signified by the development of pyritic bands which are succeeded by a strong development of zinc blende. With ptogressive crystallisation, the character of the mineral solutions gradually changed and the development of galena, and its associated bournonite, became more important in the later stages.Remnants of the replaced schist, in the form of isolated wisps and schlieren of sericite and chlorite, are present in the ore body, more noticeably in the pyritic specimens. An important feature of the ore is the association of small ogllantities of gold with trahedrite.

Jan 1, 1934

By L. G. Marshall

This report describes dredging and processing of sand and gravel from a glacial-fluvial deposit in the Raccoon River valley near West Des Moines, Iowa. Preliminary cleaning and separation of the sand and gravel at the dredge site with subsequent transportation to separate plants and the production and disposal of the various grades of aggregate material are also described. The geology of the deposit is summarized. A tabulated summary of costs in units of labor, power, and supplies is included.

Jan 1, 1963

Gas-liquid contacting in the packed bed is a common operation in metallurgical reactors. Research has shown that, unlike wetting flow, non-wetting liquid flows in the form of discrete droplets or rivulets. Thus, modeling of the liquid phase as a continuum is in contradiction to the observations. Also, for the non-wetting case, continuum models have failed to describe liquid flow path when the liquid source is a point source. The aim of the current work is to put forward a combined Lagrangian-Eulerian approach to model the liquid and gas flow in the packed bed. Liquid is assumed discrete and modeled using a force balance approach. Gas is assumed to be interpenetrating continua and modeled using k-emodel for turbulent flow. Structured packing is assumed and x- ray imaging technique is used to visualize liquid flow lines in the bed. Simulation results for liquid flow path compared with the experiments.

Jan 1, 2006

By Benjamin Cebrian

Traditional dilution control systems range from computer modeling, use of physical markers on the field as polypipes to a technology that marks some control points where displacement is measured. The latter includes walking over a muckpile which is prohibited by some mining companies as a safety measure. The new technology presented in this paper is a patented system that is installed on board excavators (backhoe or front shovel types). Several control points are set along ore/waste contacts and their position is uploaded on the corresponding shovel. The operator proceeds on mucking until he is alerted when reaching any of the several control points previously located in the blast patterns and that have moved with the muckpile. A case study is presented at a high grade copper mine, were unique 3D shapes are showing as a result of using an on-board excavator dilution control system. Both ore-loss or dilution cost of opportunities are analyzed.

Today computers are accepted as a standard item in industry and they perform a variety of tasks over a wide spectrum of activities from mine planning and CAD to data processing and spreadsheet work. However many problems particularly in the. area of decision making where there are no clear mathematical models available and usually the output or answer is dependent to some extent on a heuristic approach, don't lend themselves to conventional solutions using standard procedural algorithms. Recently a number of techniques have evolved primarily from the enhanced capabilities of modem equipment, which are capable of solving these problems. This paper is a brief overview of these rather unconventional developments of computer technology in the area of artificial intelligence with reference to their application in mining.

Jan 1, 1993

By F. F. Netzeband

This report relates to the sulfur industry of seven States--Arkansas, Kansas, Louisiana, Mississippi, Missouri, Oklahoma, and Texas--and is part of a national study of the sulfur industry by the Bureau of Mines. Markets as used 1n this report are divided into two components for individual analysis--(1) supplier markets which include regional Frasch and byproduct sulfur producers and (2) consumer markets which include processors and manufacturers requiring sulfur in their operations. The term sulfur as used in this report includes brimstone, native sulfur, elemental sulfur, or sulfur equivalents.

Jan 1, 1964

By R A. Lynch

The state-of-the-art in cave seismic monitoring is reviewed, with the latest developments in active seismic monitoring included. Seismic monitoring systems are routinely used by most of the world’s block and panel caving mines to track the cave initiation and progression. The current best practice is to use the cloud of seismic event locations as a proxy for cave growth somewhere below. Problems with event location reliability due to seismic ray bending around the (unknown) cave are side-stepped by using sensors installed above the cave. However, the aseismic gap – the (unknown) distance between actual cave back and seismic event cloud – currently hinders reliable estimation of cave geometry.Velocity inversions using the passive seismic data are inexpensive and should be undertaken more routinely. The straight-ray methods should be used with caution, as the underlying assumptions are invalid in caving environments. The double-difference method is more correct for the caving situation, and there have been some promising results published. Constrained geometric inversions make a lot of sense, but have yet to be demonstrated successfully.Two active seismic source have recently been developed for use in the caving environment: a piezoelectric source for ranges up to a few hundred metres and a pneumatically-powered source for ranges up to a kilometre. These sources produce signals on standard mine seismic sensors that can be used to measure seismic velocity variations down to 0.01 per cent resolution. This allows the cave progression to be monitored by measuring tiny changes to seismic velocities as the rock above the cave is fractured and destressed.CITATION:Lynch, R A, 2016. Active and passive seismic monitoring of cave front evolution, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 217–224 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By D Frantzos, J J. Cotter, H Tammemagi, J B. Codrington, J Kaasalainen, A C. Webster

"Exploshres Technologies International (ED) is developing an instrument called ROCSCAN which isplanned to have broad application in both blasting and rock mechanics. The purpose of this paper is to outllne the background that has led to the development of ROCSCAN, describe its objectives and to present a progress report on the work to date. Some of the potential applications of ROCSCAN will also be reviewed."

Jan 1, 1989

By P. Radziszewski

"The comminution energy curve is a profoundly simple graphical technique that displays detailed operating efficiency information for industrial comminution processes. The database underlying the methodology has recently more than doubled, to now contain a substantial fraction of the international comminution output (1.7 billion tonnes of rock per year) across more than 8 major commodities. This increase has deepened the analytical capabilities and effectiveness for assessing comminution circuit performance in relation to comparable operating mines. This paper will explore how the energy curve methodology can be used to examine the ability of stirred mill technologies to increase efficiency.Specifically, this paper explores how the energy curves methodology can be used to present energy efficiency gains achieved at three mines employing a stirred mill technology under different duties. The first of these cases studies was conducted by Rosa (2014) who compared the performance of two ball mills operating in parallel with a Vertimill in the regrinding circuit at the Samarco Iron project in South East Brazil. The Vertimill was found to achieve the same product specification while consuming 40% less energy. Brissette (2010) investigated the impact of grinding media on the performance of both ball mills and Vertimills. The energy savings achieved varied from 10% to 40% for the ball mills and 30% to 60% for the Vertimills. Lastly, Bergerman (2012) investigated the operating conditions of the Sossego regrind circuit from 2006 to 2011 against design specifications and laboratory testing. The operating work index of this circuit varied from 5.2 kWh/t to 44 kWh/t over this 5 year period. The full suite of energy curves"

Jan 1, 2016

By Carlos F. Perucca

"Potassium is one of the three basic plant nutrients along with nitrogen and phosphorus. There is no substitute for potassium compounds in agriculture; they are essential to maintain and expand food production.Potash is extracted from buried ancient evaporites by underground or solution mining. This accounts for most of the potassium produced. Another important source is brine from landlocked water bodies, such as the Dead Sea, Salar de Atacama or Great Salt Lake.About 95% of potash produced worldwide is used in agriculture. The rest is found in several other industrial uses, including glass manufacturing, soaps, plastics and pharmaceuticals.Currently, three producers: IMC, PCS and Agrium operate 8 conventional and two solution mines in Saskatchewan, five of which run froth flotation circuits, two heavy media-flotation, two run forced crystallization and one natural crystallization.Potash in SaskatchewanPotash was discovered in Saskatchewan in the early 1940’s while drilling for oil. The deposits lie diagonally across the southern plains of Saskatchewan sloping southerly from a 1,000m depth at Saskatoon to more than 1,600 m depth at Belle Plaine and up to 3,000 m in depth in North Dakota. The known deposits are massive, accounting for more than 40% of the world’s known reserves."

Jan 1, 2003

By D. K. Denton, J. M. Girard, D. F. Scott, T. J. Williams

Personnel from the Spokane Research Laboratory, National Institute for Occupational Safety and Health, examined an underground pillar at the Homestake Mine, Lead, SD. Investigations involved strain relief and seismic tomography studies in the mine, and ultrasonic velocity measurements on pillar core in the laboratory. Measured octahedral normal stress was 37 MPa (5,366 psi); seismic P-wave velocities averaged 5.2 km/s (17,060 ft/s); and ultrasonic velocities at a pressure of 39.6 MPa (5,750 psi) averaged 6.3 km/s (20,669 ft/s). The difference between in-mine and laboratory velocities is attributed to the attenuation of seismic energy by mine fractures larger and more numerous than those in the samples of core measured in the laboratory. Using these results, researchers hypothesize that pillar rocks have the ability to withstand stress an order of magnitude greater than they currently sustain.

By H. H. Dewing

The Bureau of Mines constructed a process research unit (PRU) to demonstrate new technology for extracting zinc from sphalerite concentrates. Up to 9 kg/hr of sphalerite (ZnS) concentrate was reacted at ambient pressure in the PRU with 80 pct sulfuric acid at 160° to 180° C to produce zinc sulfate and elemental sulfur. The PRU consisted of a three-stage glass reactor system: a 4-liter premix stage in which feed was slurried with 78 to 82 pct H2S04, a 40-liter stirred reactor, and a ISO-liter settling stage in which high reaction conversions were effected and excess H2S04 for recycle was separated from insoluble ZnS04 and sulfur. Evolution of sulfur-containing gases was minimized by sub-surface addition of acid feed slurry to the stirred reactor and by exclusion of air from the reactor to prevent the oxidation of elemental sulfur. Conversion of zinc to zinc sulfate averaged over 99 pct at the optimum acid concentration of 80 pct. Total sulfur losses (primarily S02) were less than 2 pct of the sulfur in the sphalerite. Elemental sulfur remained in the insoluble portion of the settled reactor product after leaching with simulated spent zinc electrolyte containing sulfuric acid. The sulfur residue contained 75 to 89 pct sulfur. Neutral zinc sulfate, required for zinc electrowinning processes, was separated from the sulfuric acid leach solution by crystallization at -15° C as zinc sulfate heptahydrate (ZnS04?7H20). The crystallization operation simultaneously effected a partial concentration of the recycled electrolyte solution by removing water.

Jan 1, 1982

By T. Patten

Inter-Mountain Labs, IML, performed a study comparing mining waste rock sample analysis by Net Carbonate Value (NCV) and Modified Sobek acid-base accounting procedures. The study looked at 468 waste rock samples and compared the data for Neutralization Potential (NP), Acid Generation Potential (AGP), Net Neutralization Potential (NNP), and the ratio of NP/AGP. The study found that a majority of the samples were below 50 Tons CaCO3/kTons. This subset of ?low-level? samples was also examined separately for Acid Base Accounting parameters. The analysis compared the NCV procedures to the Modified Sobek procedures and concludes that the NCV procedures are as protective of the environment as Modified Sobek procedures.

Feb 27, 2013

By Manuel Gomez

Bituminous coals having maximum fluidity values in the 40- to 25,400-dial-divisions-per-minute (ddpm) range were carbonized in a continuous, entrained-bed reactor. Carbonization was conducted in an 8-inch diameter, vertical reactor at temperatures from 955° to 1,345° F and at air-to-coal ratios ranging from 4.63 to 16.12 scf/lb of moisture-and ash-free coal charged. Carbonization rates from about 118 to 360 lb/hr, as-carbonized basis, were examined. It was demonstrated that carbonization temperature and air-to-coal ratio must exceed minimum values for continuous operation. Within the operating conditions discussed, highly fluid bituminous coal was carbonized to produce tar and nonagglomerated char. The yield of tar ranged from 21.3 to 38.9 gallons per ton and the char yield ranged from 1,109 to 1,563 pounds per ton, all units expressed on a moisture-and ash-free basis. It was demonstrated that the maximum fluidity and the average size of the coal along with the air-to-coal ratio and the carbonization temperature act together to influence the carbonization product yields and certain properties of the products. Prediction equations were developed from the data for product yields and selected properties of the char, tar, and gas.

Jan 1, 1968