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By Éder Domingos Oliveira, Carlos Antonio Morais, Ruberlan Gomes Silva

The objective of this work was to assess the influence of parameters such as residence time, solid content, and temperature in a process route towards purified rare earth liquor which could be adequate to produce marketable rare earth products. The steps of the process route proposed in this study comprised water leaching of a sulfated rare earth ore and removal of impurities through the purification of the rare earth sulfuric liquor, which is the product of the water leaching step. The sample used in the water leaching experiments was a sulfated rare earth ore produced by the reaction of a beneficiated rare earth ore with sulfuric acid followed by roasting at 700 °C for 2 h in a muffle furnace and cooling at 20 °C. The water leaching experiments showed that the best condition comprised a residence time of 30 min, temperature of 20 °C, and solid content of 10% w/w, resulting in a recovery of 71.3% of the rare earth elements (REE) and a lower impurity extraction, e.g., only 15.0% of Fe, representing the main impurity in the rare earth ore. Even when presenting low amounts of impurities, the rare earth sulfuric liquor still needed to be purified before it can be used in the production of marketable rare earth products. In the study, the rare earth sulfuric liquors were purified in two consecutive neutralization steps, first by dosing the limestone pulp to pH up to 3.5 and secondly by adding the lime pulp to raise the pH from 3.5 to 5.0. The application of two consecutive purification steps at 20 °C resulted in the highest overall REE recoveries (65.4%) throughout all the steps of the process, being 71.3% in the water leaching, 99.6% in the partial purification with limestone pulp, and 92.1% in the purification with lime pulp at 20 °C. Under this condition, there was a total elimination of Fe, P, and Th and a significant reduction in the Al, U, and sulfate concentrations in the purified rare earth liquor. The purified rare earth liquor attained through the experiment is expected to be amenable to be used in the production of marketable products due to the lower impurities/REO mass ratios.

By A. J. Getz

The paper reviews the status of the major precious metals projects in Australia, Papua New Guinea, Indonesia, the Philippines, and New Zealand. The projects may be at the stage of exploration, development, operation, or expansion. The paper covers project location, reserves, method of resource exploitation, anticipated production, and other unique conditions.

Jan 1, 1990

By L. C. Lang

INTRODUCTION The introduction of 165-mm (61/z-in.) holes to underground mining operations has made possible the application of Canadian Industries Ltd's (CIL) vertical crater retreat (VCR) mining method, illustrated in the accompanying sketches. This unique and revolutionary new application of spherical charge technology (see the Appendix), when applied to primary stopes and pillar recovery, eliminates raise boring, slot cutting, and dilu¬tion of ore by backfill; greatly improves fragmentation; reduces labor and time requirements; eliminates uphole drilling and blasting; and minimizes or completely elimi¬nates damages by blasts to the walls and retreating backs of the stope or pillar. If vertical large diameter holes are drilled on a designed pattern from a cut over a stope or pillar to bottom in the back of the undercut, and spherical charges of explosives are placed within these holes at the calculated optimum distance from the back of the undercut and detonated, a vertical thickness of ore will be blasted downwards into the previously mined area. Repeating this loading and blasting procedure, min¬ing of the stope or pillar retreats in the form of horizontal slices in a vertical upwards direction until the top sill is blasted and the mining of a stope or pillar is completed. The VCR method is also applicable to drop raises and has the potential to replace all other raising methods under most circumstances. PILLAR RECOVERY Levack Mine Inco Metals Co., Ontario Div., provided the first opportunity for the method in pillar recovery. The Levack mine's high grade ore pillar No. 4800 on the 975-m (3200-ft) level was used for the production¬scale experiment (Figs. 1 to 3). The pillar was about 49 m (160 ft) long, 6 m (20 ft) wide, and 20 to 26 m (65 to 85 ft) high. The mined area on both sides of the pillar was backfilled with a 1:30 cement:sand mixture. The pillar was removed in two phases. In phase 1, the standard uphole method was used to blast down the 18-m (60-ft) long section of waste from the bottom of the ore into the undercut. From the pillar's top sill, 165-mm (61/a-in.) holes were drilled downward into the pillar, and by measuring the depth of the holes, the results of the uphole blast were determined and roof line 1 was established. The bottom of each hole was plugged, then filled with sand to place the center of gravity of each spherical charge (loaded from the top sill) at a predetermined optimum distance from the horizontal free surface. The charges were then detonated. After detonation, both draw drifts were full of extremely well-broken material. The depth of each hole was measured again, and the plot of these depths re¬sulted in roof line 2. The same blasting procedure was repeated and the resultant new back elevation was marked by roof line 3. The poor results of the initial uphole blast at one location (notice the peak in area 1) appeared to influ¬ence the subsequent new backs. A third blast success¬fully evened the back, and resulted in roof line 4. An unblasted slab averaging 6.3 m (20.9 ft) thick remained below the pillar's top elevation as the final sill. In all three spherical charge blasts fragmentation of the blasted material was extremely fine. The backfill was fully exposed on both sides of the now-blasted pillar. The backfill remained undamaged and the ore was not diluted by sand. The remnants of all the 165-mm (61/2 -in.) holes remained clean and undamaged, and the holes had well-defined bottoms that could be easily measured and plugged. Each blast took down a 3.9 to 4.2-m (13 to 14-ft) thick horizontal slab of ore. Productivity was three times greater than that of the previously practiced cut-and-fill method. Since this was the first such experiment, blasting the remaining 6-m (20-ft) thick final slab was the sub¬ject of some deliberation. If the described method was repeated, we could have ended up with a 1.8-m (6-ft) thick sill unsafe to work on. It was therefore decided to blast the whole sill using two spherical charges prop¬erly placed in each hole, but with the application of

Jan 1, 1982

By P. J. Ryan

Phelps Dodge’s Candelaria copper-gold mine is located 20 km (12miles) south of Copiapó in northern Chile’s Atacama province (Region III) (Fig. 1). The Candelaria Mine is about 800 km (500miles) north of Santiago and 75 km (47 miles) east of the Pacific Ocean. Its elevation is 600 m (1,970 ft) above sea level. The Copiapó River Valley is 6 km (4 miles) northeast of the mine site. It is the only major source of water in this arid region. The average rainfall is 14mm/a (0.5 in./year). During 1995, the mine produced 521.4 kt (574,800 st) of copper concentrate containing 150 kt (165,000 st) of salable copper and 3 t (98,800 oz) of gold. The 1995 unit cash cost was less than 50 cents/lb of copper. This makes Candelaria one the world’s lowest cost copper producers.

Jan 1, 1996

By D. D. Runnells

In order to establish meaningful remediation goals and monitoring programs in areas disturbed by mining, it is desirable to determine the natural metals concentrations that existed in the area prior to mining. At Iron Mountain, California, several natural sources exist for acid drainage and loading of metals to Slickrock and Boulder Creeks. This paper describes methods to determine the contribution of copper and zinc to groundwater and surface water from those sources, including natural gossan rock outcrops, mineralized bedrock, and colluvial materials. Methods used include evaluation of: 1) historical information, 2) literature values of unmined, mineralized areas, 3) analyses of water from monitoring wells, 4) leaching studies, 5) statistical analysis, 6) isotopic studies, and 7) identification of background by elimination of mining sources. Results from this natural background determination show that Boulder Creek and Slickrock Creek carried elevated concentrations and loads of copper and zinc prior to mining activities. With repeated rinsing of reclaimed and remediated mine materials by rainfall, there will be a diminishing contribution from residual waste rock and tailings at Iron Mountain, and natural background will become an increasingly larger proportion of the total load.

Jan 1, 1999

By J. S. Hu

FTIR spectroscopy has been used for the characterization of adsorbed oleate at the fluorite surface. It has been found that modest changes in the adsorption density at high temperature and high oxygen potential do not provide a satisfactory explanation for the significant increase in the hydrophobic character of the system under similar conditions. Rather, FTIR spectroscopic measurements suggest that chemical interaction between adsorbed oleyl groups occurs at high temperature and/or oxygen potential and accounts for the increased hydrophobicity. Specifically, the intensity of the =CH bond of the adsorbed oleate diminishes at high temperature and/or high oxygen potential. Such a phenomenon was not observed in control tests with the calcium oleate soap. For extensive reaction at the fluorite surface, the presence of a new surface species has been identified. These results indicate that the fluorite surface catalyzes an oxidation and/or polymerization reaction between adsorbed oleyl groups which results in a more hydrophobic structure at the fluorite surface.

Jan 1, 1986

By James S. Browning

Extensive deposits of kyanite occur in the southeastern United States, The reserves of these deposits, if developed, are adequate to supply the United States with 35-mesh kyanite concentrate:; for many years at the present-rate of consumption, According to Espenshade and Potter,1 the kyanite-quartz rock type deposits in this area contain about 100 million tons of ore averaging 10 to 30 percent kyanite. The tonnage of kyanite-bearing gneiss and schist is, much larger than the tonnage of kyanite-quartz rock, but the kyanite gneiss and schist are appreciably lower in grade. The largest deposits of kyanite-quartz rock are in the Farmville district, Virginia, and Kings Mountain district, North Carolina South Carolina, and at Graves Mountain, Georgia. Of the known deposits, only four were being mined for kyanite in 1967. These deposits are near Farmville and Dillwyn, Va., Clover S. C., and Washington, Ga. Production of kyanite and synthetic mullite increased substantially in 1965.2 Output of, domestic kyanite concentrate increased by 14 percent in 1965, establishing a record high for the fifth consecutive year. Estimated annual consumption of kyanite minerals and synthetic mullite was in excess of 100,000 tons. The manufacture of mulatto refractories accounts for most of the kyanite minerals consumed annually, but non-refractory uses are expanding.3 Most mullite refractories are used as furnace linings in metallurgical and glass manufacturing furnaces. The remainder is used largely for kilns, kiln furniture, and saggers by the ceramic industry. Small quantities of kyanite without calcination are used as a source of alumina in the manufacture of glass, electrical and chemical, porcelain, pyrometer tubes, and in the form of kyanite concentrate to increase the alumina content of fireclays. Kyanite is used to improve workability, increase strength, and to compensate for firing shrinkage in floor and wall tile and other ceramic products.

Jan 1, 1968

By Alan J. Solomon

The function of advertising is communication. Viewing the advertisements of mineral suppliers exposes the reader to a broad spectrum of purposes: announcements of new products, availability and supply, departmental services, company image, etc. It is the advertiser's hope that the message being conveyed is the same message being perceived by the viewer. To maximize this probability, the advertiser at least must carefully construct precise copy, identify the target audience and select the appropriate advertising medium. A truly successful and efficient ad, however, also must accurately reflect a product's life cycle, i.e., the rise and fall in demand for a product. Buggy whips and radio tubes are classic examples of items formerly in high demand. Industrial minerals are similarly affected by occurrences of product life cycles.

Jan 1, 1983

By Paavo Eerola

In May of 1984, it was decided that Outokumpu Oy would design and build a new nickel flotation mill to process ore from the newly discovered Enonkoski mine in eastern Finland. Since there hart peen a number of successful process charges in the existing mills, the design effort included the study and incorporation of several new developments, including all-autogenous grinding, "flash flotation", lane cell roughing, large cell cleaning and a computer-based, profit optimizing, process control system. The paper discusses the background and results of those studies, and a description of the resulting mill which will begin production in 1986.

Jan 1, 1985

By K. Kim

An analysis was conducted to determine the effects of blasting on slope stability and downstream comminution processes. To investigate these effects, the extent of blast-induced rock damage and the magnitude of induced stress were examined. This analysis showed that damage may extend up to 500 meters (1MPa, tensile strength) in the rock mass, a distance that is sufficient to impact the pit-scale slope over the long term. In addition, the damage zone was calculated using the reasonable assumption that compressive waves are the primary agent in microfracturing during blast fragmentation. The calculated damage zone ? up to 5.6 meters (30MPa, 30% of the compressive strength) ? indicates that microfracturing can occur throughout the entire rock mass in the blasting area. Finally, an economic analysis was conducted by comparing two reasonably assumed blasts in a copper mine. The change in energy required for crushing and grinding was demonstrated using Bond?s law after increasing the blast energy from 180kcal/t to 350kcal/t. A total cost saving of 13.3% ($9.4M) was achieved with the increase. An optimal blast design should consider both slope stability (safety) and downstream comminution energy (production).

Feb 23, 2014

By K. Louk, E. Gilliland, N. Ripepi, M. Karmis

"Carbon dioxide (CO2) injection in deep unmineable coal seams can enhance coalbed methane (CBM) recovery as well as effectively and permanently store the CO2. Enhanced coalbed methane (ECBM) recovery and CO2 storage capacity can be improved by altering injection parameters including the injection well locations, number of injection wells, and the time and rate of the injection. A sensitivity study was performed with sixteen different injection scenarios on a coalbed methane field in Buchanan County, Virginia to understand the influence of the injection parameters on methane production, CO2 storage and the extent of the CO2 plume. History matching was done for the gas and water production period prior to injection based on field data from an active US Department of Energy funded pilot project. INTRODUCTION The coal structure is a combination of the coal matrix and cleats. In a CBM reservoir, the methane (CH4) is stored in the matrix under adsorption properties, not as a free gas. During CH4 production, the reservoir pressure is reduced and gas is released from the surface of the coal, diffuses through the matrix and transmits to fractures (man-made or natural) via the cleat network. Fractures and cleats are the major parameters that influence gas flow capacity because deliverability of the CH4 to the production well is controlled by the cleat permeability. As gas production continues over time, CH4 desorbs from coal, and coal matrix volume starts to decrease. This volume decrease in the matrix opens up the cleats, matrix shrinkage, which leads to a permeability increase. Several emprical (Harpalani and Schraufnagel 1990a, 1990b; Harpalani and Chen 1995, 1997; Harpalani and Mitra 2010; Pan et al. 2010; Liu et al. 2012; Mitra et al. 2012) and analytical (Palmer 2009; Liu and Harpalani 2013) studies have reported this relationship between pressure and permeability. Those studies showed that permeability is an important parameter in CH4 production performance. Furthermore, during gas production, water is produced through the cleat system as well, therefore gas-water relative permeability must be also considered in evaluating production performance (Gash et al., 1991). In the CO2 injection scenario the opposite occurs because CO2 has a higher adsorption affinity than CH4. CO2 replaces CH4 in the matrix of the coal and increases the volume of the coal matrix, matrix swelling, and results in a permeability decrease. Harpalani and Mitra (2010) concluded in their experimental study that swelling of the coal matrix due to the CO2 injection is two to three times more than the sorption of CH4, resulting in large permeability changes during CO2 injection."

Jan 1, 2016

By S. J. Zagula

Improved desulfurization of Illinois coals is a widely Shared research goal. The development of a physical cleaning strategy and the results of a project to demonstrate technical and economic feasibility of producing a low sulfur compliance coal from the Illinois Basin are reported. Processing flowsheets to extend or retrofit existing preparation plants are considered. Comminution, conventional and micro-bubble flotation, and selective agglomeration technologies were investigated to maximize pyrite rejection while maintaining high product yield. Batch bench scale testing was followed by continuous pilot plant studies. Parameters included grind size, flow rates, pulp density, aeration, agitation, and reagent dose. An economic evaluation of targeted processes is included.

Jan 1, 1987

The impact of a methane explosion on mining operations cannot be over-emphasized. The explosion is a result of rapid combustion when a methane/air mixture is ignited by an unexpected energy release, such as a mine fire, electrical arc or sparks caused by frictions or rock falls. In most cases, an ignition of methane/air mixture could result in a deflagration other than detonation. Resulting flames and overpressure induced by a methane deflagration will harm neighboring miners and local ventilation control devices.. ,It is essential that the mechanism of an explosion and associated destructiveness be fully understood. This research seeks to predict an influence region of an incident happened within a representative underground mine geometry. The most common geometric changes in an underground coal mine are bends, regulators/doors, obstacle in airways and changes in sectional area. These geometric changes could result in an attenuation of the flame and pressure wave as a result of a methane deflagration. A study of this phenomenon could enable mine planners to have better understanding of the over-pressure redistribution due to the explosion. Both numerical and experimental work has been done in this study to ascertain a better insight of this potentially devastating event. The experimental data are also used to validate the turbulence and combustion models used in this test.

Feb 23, 2014

By H. Fayed

Froth flotation technology is the backbone of the minerals pro-cessing industry where minerals are concentrated by selective separa-tion; either direct or in-direct flotation. In direct flotation useful minerals are conditioned to become hydrophobic (water-repellant) and attach to air bubbles while impurities (non-useful particles) remain in water. The hydrophobic particles are transported by air-bubbles to the top froth (foam) layer in flotation tank which can be removed as a concentrate. There are many factors that controls this selective separation process such as: particle’s degree of hydrophobicity, size, mass loading, air holdup and bubble size distribution. Turbulent fluctuation of the slurry in the tank is another important factor that controls the collisions rate between particles and bubbles and hence attachment rates. The turbu-lent fluctuations are measured by the local distribution of turbulent dissipation rates. Conventional flotation machines are restrained by residence time of the slurry that is about 3-5 minutes that results in a large footprint and limits the capacity of flotation plants. The designers of conventional flotation machines try to reduce the footprint of flota-tion tank by scaling up the flotation machines to increase plant throughput. The scale-up process reduces the specif power consump-tion and the local distribution of shear rates and turbulence dissipation rates. This scale-up results in a larger mean bubble size and lower particle-bubble attachment rates.

Feb 1, 2023

By G. Van Weert

Separation of minerals by shape has received little attention, since minerals normally do not break into different shapes during crushing and grinding. However, comminution of consumer wastes generates opportunities for novel separations based on particle shape. For instance, ductile plastics are broken into longer curved shapes, whereas brittle plastics yield angular particles. Using spouting beds for particle separation in water requires controlling the spout's instability. The preferred geometry for such redesigned spouting beds is reported. Plastic cylinders, discs and spheres were separated as a function of rising water velocity and amount of particles in the system. By using 5 mm particles, differences in settling behavior could be video recorded.

Jan 1, 1999

By Alan Bauer

In recent years there has been increasing interest in employing the technique of explosive casting in strip mines. Explosive casting, applied to dragline mining, describes the procedure whereby the overburden is horizontally displaced by blasting causing a portion of the material to be thrown into the previously mined cut. Therefore, it is not necessary to subsequently excavate this waste with the stripping equipment. In addition, allowing the overburden unrestricted movement during the blast most often results in improved fragmentation and enhanced machine productivity. The method is receiving attention because the capital and maintenance costs of stripping equipment has risen rapidly in relation to explosives costs. Improved productivity is necessary to maintain unit costs at an acceptable level.

Jan 1, 1983

By J. B. Yianatos, G. S. Dobby, J. A. Finch, A. R. Laplante, R. Espinosa-Gomez

The question is posed as to why columns typically have a collection zone 10 m high (H) by 1 m in diameter (D). Three geometry dependent factors are considered: degree of mixing, Np; volumetric bias rate, B; and volumetric gas rate, G. Increasing H:D decreased Np and B, which improves performance but decreases G, which causes the column to approach overloading. Taking typical column operating conditions, it is concluded that a collection zone H:D of 10:l is a reasonable compromise.

Jan 1, 1987

By James T. Baxter

Underground mining of limestone is becoming increasingly attractive in Illinois. Most quarries are near rivers on the western and southern borders where competition for land use is intensive. Increasing demands for stone can be met by expanded mining with access by edits in existing quarries and by inclines and shafts at downdip sites. Geologic, hydrologic, and engineering conditions indicate that deep mines in the Ste. Genevieve, St. Louis, Salem, Ullin, and basal Burlington Limestones of Mississippian age and in the Moredock Limestone Member of the Dunleith Formation of Ordovician age are possible, but development will require prudent exploration and planning to ensure that the product will be of good quality.

Jan 1, 1978

By Dennis R. Twining

Recently a mining analyst for a major bank called me to say that during his travels he had encountered an electric utility interested in a new uranium supply. Since we produce uranium as a by-product of phosphate operations rather than as a primary product, he assumed we simply sold our output in the spot market and that a new prospective purchaser would be of interest to us. This assumption was incorrect; the uranium had already been sold on a long term basis at terms more favorable than the currently depressed spot market. From the outset our approach to the marketing of uranium was based on the principle that by-product marketing is not unlike primary product marketing. This was particularly appropriate in the case of uranium, as we were planning a considerable technical and capital commitment to a new business. This illustrates: that the fundamental principle in by-product marketing is to follow a primary product strategy; that the terms "by-product" or "co-product" are creations of accountants; that they have no place in marketing decisions! Traditionally, the term "by-product" has implied that only a secondary marketing effort is required. Recent history has contradicted that view by demonstrating that by-product values can have marked impact on a mine's revenues and costs. In fact, by-product values can spell the difference between success and failure.

Jan 1, 1983

By W. G. Pariseau

"BACKGROUND The Crandall Canyon Mine (CCM) is located in the Wasatch coal field in central Utah. Extensive longwall mining at CCM preceded a decision to recover coal left in barrier pillars on each side of a set of main entries extending far into the mine. During mining in March, 2007, a major bump occurred that led to cessation of mining in the barrier pillar on the north side of the mains and to begin mining in the south barrier pillar. Subsequent loss of ground control in August, 2007, through coal pillar bursts had tragic consequences with loss of six miners and shortly afterwards three rescue team members. An MSHA report describes the events in detail (MSHA, 2008). An important lesson to be learned from CCM is the need to select a computer program suitable for pillar design. Computer programs are engineering tools; selecting the right tool for the job is essential. In this regard, a minimum program requirement is capability for computing stress distribution within a pillar and adjacent roof and floor strata. The reason is simple: strength of rock is stress dependent; both vary from point to point in pillars and adjacent strata. Preferably, one should follow the evolution of stress as the mining plan is executed from start to finish to assure safety or to warn of a potentially hazardous situation developing as mining progresses. The approach to the problem posed by barrier pillar mining at CCM is conventional in the sense of applying well known finite element modeling techniques to analysis of a proposed mining plan. The engineering purpose is to evaluate the mining plan with respect to ground control questions including roof, floor and pillar safety. Results of previous two dimensional finite element analysis indicated pillar safety was by no means assured (1, 2, 3). Geometry of barrier pillar mining is limited in two-dimensions, for example, crosscuts are not seen in vertical cross sections. While three dimensional analyses are preferred, even moderately sized regions often lead to very large problem sizes that exceed computer capabilities. However, a recent development in finite element modeling of tabular deposits allows for whole mine analysis in three-dimensions. This technique involves a dual node – dual mesh concept. Both have been used separately in much earlier work, but are only now are used in combination. Estimation of subsidence at a kilometer scale and details of stress, strain and displacement about barrier pillars, main entries and pillars, and so on at a meter scale are possible (4). No compromise involving empirical formulas or similar guess work is required. Indeed, all calculations are based on first principles: physical laws, kinematics, and material laws. Effects of joints and in situ variability or uncertainty in strata properties, elastic moduli and strengths, may be included for greater realism. An important objective of the present study is to assess the role of three-dimensional pillar geometry in arriving at conclusions regarding barrier pillar mining versus two-dimensional results."

Jan 1, 2015