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By James Paone

Drillability of rocks by mechanical means is closely related to the physical properties of the respective rocks, Various approaches by previous investigators on rock drillability are presented, as well as recent techniques studied by the Bureau of Mines. The studies show drillability concepts based on (1) theoretical drilling equations derived from laboratory drilling experiments extended to field drilling results and on (2) a statistical method where multiple regression analysis is used to develop a prediction equation for drillability.

Jan 1, 1966

By Shuie Li, Taibai Li, Tao Hu, Zhongjie Wang, Xiang Ge

As one of the main power sources, lithium-ion batteries (LIBs) will continue to be applied on a large scale in the future market. Commercialized LIBs cathode materials contain various valuable metal elements including Li, Co, and Ni. The development of green and efficient recycling technology is essential. Deep eutectic solvents (DESs) have recently emerged as a new class of green solvents that could potentially be applied for the LIBs recycling industry due to their capability to leach the active materials without the introduction of environmentally hazardous reagents as used in conventional hydrometallurgy process. Considering the rapid progress, a critical review focusing on the progress and fundamentals about the overall efficiency has practical significance for the further advancement of this field. Herein, we briefly introduce the overall process of using DESs for LIBs recycling and specifically focus on the efficiency of each step. Current fundamental understandings and new experimental approaches to enhance the efficiency of the leaching process, the extraction process, and reusability are summarized. We expect this review article to inspire scientists to use DESs as powerful tools for advancing the frontiers of LIBs recycling.

Jul 30, 2022

By James G. McKelvey

Owners have seen several major tunnel projects in recent years fall victim to a general reduction in the number of bidders as well as an erratic range of pricing. It should be noted though that this is not a universal trend and some projects have seen good competitive bids. Contractual terms and conditions are an important factor in attracting good competition. The Front End documents of tunnel projects have come under increasing scrutiny as tunneling contractors in the U.S. industry are looking much more closely at their risk exposure in the contract terms and conditions. Considering the amount of tunnel construction work upcoming in North America, it is important that General and Special Conditions are put together in a way that provides a reasonable basis to execute the Contract and also provide a fair, balanced and swift way to resolve disputes.

Jan 1, 2008

By Behrouz Tehrani

The size, complex issues, and requirements to construct large number of tunnels, for a single project, expeditiously, and without exceeding the overall project budget, a program Construction Management (CM) team is highly recommended to be selected early during design process to provide guidance/direction relative to contract packaging and scheduling. This paper is not focused on the project itself, however, the emphasis is on experiences gained from the project. Wishing that some of the strategies described in this paper will be of value to owners of underground project.

Jan 1, 2008

By Nikhil Dhawan, Shrey Agrawal

Feldspar, a low-alumina, and abundantly available aluminosilicate source, is explored in this study to extract aluminum and potassium values. The sample comprises lamellar layers of microcline and albite with quartz containing 17.4% Al2O3, 9.67% K2O, and 66.3% SiO2. Mechanical (milling) and thermal (alkali and acid baking) activation are investigated, followed by HCl leaching. The milling treatment up to 6 h is inefficient in phase dissociation and results in ~ 40% Al and K dissolution. The alkali thermal treatment yielded 80% Al and 71% K extraction. Direct precipitation of the dissolved Al and Si values yielded alumina purity of ~ 29%, and silica gelation separated SiO2 and improved alumina product (94% purity, 71% recovery). Acid baking yielded 98% pure alumina precipitate; however, Al and K extraction were limited to ~ 45% and 65%, respectively. The microwave-assisted alkali treatment was optimal with 800 W and 10 min processing conditions yielding 80% Al and 71% K recovery with 2.26 kWh/kg alumina of thermal energy consumption. The final product contains γ-alumina with a specific surface area of 87 m2/ g. Keywords Feldspar · Alumina · Potassium ·

May 18, 2022

By W. K. Katoto

The Tailings Leach Plant (TLP) of the Zambia Consolidated Copper Mines Ltd at Nchanga was commissioned in 1974 as the world's first largest successfully operated agitation leach SX-EW plant for copper production. The design, development and operation of the plant soon after commissioning termed as TLP stage II has been described by Holmes et al (1). In the initial phase the plant was designed to treat approximately 25,000 tonnes per day of current flotation tailings from the Nchanga Concentrator operations, and had a design capacity to produce 75,000 tonnes per annum of copper. Further expansion took place in 1986, and TLP stage III was successfully commissioned to treat an additional 20,000 -25,000 tonnes per day of large reserves (over 135m tonnes) of reclaimed tailings stockpiled since the early 1930's in four paddock type tailings dams (T01 to T04). The salient feature of TLP stage III expansion described by S K Mwenechanya et al (2 -3) was the installation of the world's largest Horizontal Belt Filter Plant with 26 filters each of 80 m2 filtration area.

Jan 1, 1996

By N. Wahl, D. M. Blackketter, R. Thornton

This paper evaluated using a water-filled abandoned mine (Orphan Boy) as a heat source for a 240- kW closed-loop heat pump with the goal of heating a 2,000-m2 building. The mine has a 245-m vertical shaft connected to a large stope by three horizontal cross-cut shafts. There is 1,250 x 106 L of water at a consistent temperature of 24-26° C that is available mostly in the stope. The only heat exchanger placement option is in the vertical shaft. Therefore, the focus was to model heat exchanger placement in the vertical shaft to determine the extent to which the systems will induce thermal currents between the stope and vertical shaft. Modeling of thermal currents, temperature profiles and heat contribution from the ground was done using finite difference and computational fluid dynamics. An optimal configuration was determined showing sufficient water movement and heat transfer will occur with a low water temperature in the shaft above 20° C. This project supports a U.S. Department of Energy (DOE) grant that will implement the full-scale system.

Jan 1, 2013

By Zhonglin Ye, Guangping Dai, Ba Zhang, Yonggang Wei, Shiwei Zhou, Bo Li, Hua Wang

Decreasing copper content in slag is critical for improving copper recovery, where apparent viscosity is the main factor affecting the separation of matte/copper from the slag. The viscous behavior of copper converter slag was investigated during reduction process in this paper, and its non-Newtonian viscous behavior and shear thickening characteristics were clarified. The effects of silicate structure and solid particles in the melt on the slag apparent viscosity were investigated. As slag cleaning proceeded in an electric furnace, the magnetite gradually transformed into ferrous oxide, increasing the FeO/SiO2 ratio. With this ratio increased from 1.2 to 2.0, the slag structure was simplified, and its apparent viscosity decreased from 0.26 to 0.12 Pa·s at 1523 K. The iron phase was excessively reduced to metallic state; the slag contained metallic copper-iron alloy particles, increasing apparent viscosity. The apparent viscosity and phase structure of the slag corresponding to the iron phase reduction process were analyzed in detail; the results obtained in the present study are of great significance to the reasonable control of the converter copper slag cleaning process.

Nov 7, 2022

By Robin P. Gardner

The development and use of short-lived radioactive tracer methods for the on-stream determination of residence time distributions in large-scale ball mills is described. Tests are reported on a pilot-plant ball mill with 0.43 m diameter and 0.86 m length and on an industrial mill with 1.83 m diameter and 2.74 m length. Tests with different tracer feed sizes indicate that the residence time distributions on both mills are independent of charge particle size. Similar tests are planned for a-large ball mill of 4.57 m diameter and 9.30 m length. No safety problems were encountered in these tests and none are anticipated in tests of the larger mill.

Jan 1, 1978

By O. B. Bucklen

The Coal Research Bureau of the School of Mines at West Virginia University, using a modified design of a Russian flotation device, was able to obtain a clean coal product containing 7.64 percent ash with 94 percent yield and 97 percent coal recovery. This favorable performance was obtained with the semi-pilot scale flotation cell operating as a simulated three stage unit on slurry taken from the fine coal circuit of a coal preparation plant. This experimental device, consisting of a sheet metal cyclone-like unit mounted on a U-shaped uplift pipe, uses a combined flotation and cyclone action to beneficiate the minus 14 mesh partially cleaned feed product. In addition to providing comparable analytical results, the airlift-cyclone possesses other attractive features among them being a low capital expenditure, utilization of moderate plant floor space, efficient "operation on high density feed slurry, and absence of moving parts.

Jan 1, 1964

By J. Evans

INTRODUCTION Section 209(b) of the Federal Land Policy And Management Act of 1976 (FLPMA-43 U.S.C. 1719 b) authorizes the Secretary of the Interior to convey mineral interests owned by the United States where the surface is or will be in non-Federal ownership. The objective is to allow consolidation of surface and subsurface (mineral) ownership. Certain major conditions must prevail for a conveyance to occur. These are: 1) There are no known mineral values (KMV) or 2) Where the mineral reservation interferes with or precludes appropriate non-mineral surface development and that non-mineral development is a more beneficial use of the land than the mineral development. Remember that allegation, hypothesis or speculation that the conditions could or may exist in the future will not be a sufficient basis for conveyance. Convincing factual evidence for an applicant’s case for mineral conveyance must be made in order to achieve that conveyance. See 43 CFR 2720 0-1 to 0-3, and 0-6. CONCEPT OF KNOWN MINERAL VALUES Known mineral values means mineral rights in lands containing geologic formations that are valuable in the monetary sense for exploring, developing, or producing natural mineral deposits. The presence of such mineral deposits with potential for mineral development may be known because of previous exploration, or may be inferred based on geologic information (43-CFR 2720.0-5(b).

Jan 1, 2007

By M. Guney, A. R. Bell

In Mindola mine on the Zambian Copperbelt, there is a plan to extend the current production level of 1.2-1.5 km (3,900-4,900 ft) with five additional production levels. Research work indicated that the present total heat output of 38.6 MW will inevitably increase to 63.2 MW in 25 years. Estimated WB and DB temperatures, representing the total heat generation in stope faces and development headings during these same periods are predicted to increase to 33.8/40.2°C (93/104°F) and 35.3142.10C (95/108°F) respectively. It is assessed that the nominal refrigeration capacity needs to be progressively increased to 9, 000 MW.

Jan 3, 1984

"Cast blasting is the primary means of overburden displacement in a surface coal mine. It serves two purposes; fragmenting the rock and throwing it directly to its spoil pile using explosive energy. Increased throw minimizes costs by reducing the amount of material that needs to be rehandled. Prior studies have shown that by only changing blasthole timing with the same blast design, fragmentation and throw alter. It is necessary in cast blasting to optimize both fragmentation and throw, since larger fragments will require more wasted energy to throw the same distance. In an operating mine in Georgia, an optimum interhole delay for fragmentation has been found by studying timings from 0 millisecond (ms) to 45 ms. Instantaneous timing between holes increased the throw by more than 31 m (100 ft), but fragmentation was poor. Shock and detonation wave collision is a potential reason for this increased throw.Explosives are utilized extensively by the mining industry in order to break rock, as either ore or overburden, for hauling, loading and crushing. An effective production blast strives to achieve optimum rock fragmentation in order to increase the efficiency and reduce the costs of those downstream operations, while simultaneously meeting environmental regulations. The goal of blasting with respect to fragmentation is, according to Hettinger (2015), “to decrease the average particle size of the fragmented rock without overly increasing fines or, in other words, improve fragmentation.”Additionally, the distance the rock is transported by the explosive energy from the blast, also known as throw, can increase efficiency by reducing the amount of material that is rehandled by mine equipment. The primary situation in which this is desirable is the cast blasting of overburden across the narrow pit of a surface coal mine. A key variable in a blast design pattern that can be manipulated to optimize both fragmentation and throw is delay timing between detonations. The invention and increased utilization of electronic detonators have allowed for precise delay timings to be used between rows, holes and even multiple primers within the same hole. These recent developments in the blasting community have also provided an opportunity to investigate whether or not the mechanism of shock or detonation wave collisions caused by short timing delays are responsible for any increased fragmentation or throw. This experiment attempts to demonstrate if an increase in throw can be achieved while maintaining optimum fragmentation."

Jan 6, 2017

By S. Norman Kesten

The Galena mine is located astride the Polaris fault in the Coeur d'Alene district of northern Idaho. The surface installations are about a mile up Lake Gulch, the mouth of which is about 2.4 km (1 112 miles) west of the old town of Wallace. The mine had its beginnings when the first claims were located in the early boom days of the district in the 1880s and when the first underground ore bodies were opened up in 1917. During the ensuing 14 years, ore was mined from which were recovered 5.4 Mkg (12 million lb) of lead and almost 14.2 Mg (112 million oz) of silver. Workings consisted principally of a vertical shaft from surface to the 800 level and an offset underground shaft to the 1600 level, together with extensive lateral openings. High-grade silver-copper ore was discovered near the Silver Standard fault in the Sunshine mine, a few miles to the west, on the 1700 level in 1930. By 1937, the Sunshine and adjacent mines were producing silver-copper ore on a regular basis. In 1943 additional ore of a similar type was found along the Chester fault, to the east of the principal Sunshine workings. The interest of American Smelting and Refining Co. (renamed ASARCO in 1975) was aroused and the company's geologists determined that the Galena mine, idle since 1931, provided a geological environment in which similar ore might be found. After negotiations were initiated with the owners of the property, Callahan Zinc-Lead Co., the property in question was deeded to Callahan's wholly owned subsidiary, Vulcan Silver-Lead.

Jan 1, 1990

By Evan J. Owen, Virginia T. McLemore

The Zuni Mountains, located in Cibola County, New Mexico is an uplifted area that exposes Proterozoic igneous and metamorphic rocks overlain by Permian and younger sediments. Sedimentary-hosted Cu deposits and fluorite veins in the district have recorded production, but other deposits exist. Proterozoic ultramafic rocks may host Ni and PGE. A recent regional stream sediment survey collected 76 samples as part of an exploration geochemistry course at New Mexico Tech with the goal of assessing the critical minerals potential of the district. Whole rock and trace element chemistry of the sediment samples (<2 mm) show a variety of critical minerals possibly worthy of future targeted exploration including up to 700 ppm As, 2100 ppm Ba, 26 ppm Bi, 25 ppm Co, 640 ppm Cu, 145 ppm Ni, 110 ppm Sb, 170 ppm V, and 500 ppm Zr. Positive correlation between Bi, As, Cu, and Sb suggest that these critical minerals are found together within copper veins related to shear zones in the district. Samples collected from streams that drained outcrop of mafic and ultramafic rocks were found to generally contain more Ni, Co, and V. Samples elevated in Ni will be reanalyzed for PGE.

Feb 1, 2025

By S. Gering, R. Ruiz, C. H. Calderon-Arteaga, J. Barrios

"Located in the northeast corner of Zacatecas State, Mexico, the Peñasquito operation is comprised of the Peñasco and Chile Colorado (Brecha Azul) deposits. Openpit mining (prestripping) began in 2010 and full production commenced during 2011. The openpit mines feed both a sulfide concentrator (mill) and a heap leach pad. The project is owned by Goldcorp Inc. Peñasquito is a poly metallic deposit with Au, Ag, Zn and Pb being recovered as payable metals.As a consequence of lower grade ores expected with advancing mine life, Peñasquito is facing a declining metal production profile. To maximize returns and asset value, plant modifications, including the addition of a carbon prefloat circuit and a pyrite leach circuit to improve recovery, are currently being undertaken. This carbon prefloat circuit will enable the recovery of precious and base metals from carbonaceous sediments. This material is currently being stockpiled. With the associated increase in complexity in the process circuit, the requirement of the ore control system to accurately predict ore feed characteristics is critical to maximizing metal recovery at the Peñasquito operation. The addition of the carbon prefloat circuit was also a key driver in allowing the Chile Colorado openpit to be developed.These conditions alongside Goldcorp’s drive to increase profitability and maximize net asset value has created challenges. These challenges are numerous and multifaceted. However, the ability to accurately route materials from the ore control system is critical to site success, and some of these challenges have been overcome by the adoption and implementation of a new ore control (OC) technology. Examples of these technological innovations in the ore control program are discussed in this article and include improvements in geomodeling, material routing and reconciliation. Successful implementation of these elements has led to significant improvements in selectivity, performance and data management, while reducing the variance between planning and execution, thus helping to drive overall improvement across the operation."

Jan 7, 2018

By Charles B. Manula

This paper describes the development of a mathematical model for simulating the behavior of a longwall coal production system. The longwall simulator is a design simulator incorporating both deterministic and stochastic methods to calculate: (a) the size and density of support; (b) the cutting force, power requirements and haulage speed for the loader-shearer; (c) the conveyor size, speed and power requirements; and (d) delay generation at head and tail-gates and the longwall face.

Jan 1, 1978

By Y. Luo

"It is generally known that spontaneous combustion potential is a function of coal rank, with low-rank coals having high susceptibility to self-ignition and high-rank coals having low potential. To establish this functional relationship and use it as an engineering tool to identify the propensity of coal to self-heat, both rank and spontaneous combustion potential should be quantified. ASTM D388 is normally used to classify coals by rank, but this classification system can only serve a qualitative analysis. To classify coals by their potential for spontaneous combustion, the self-heating temperature (SHT) method originally developed by the U.S. Bureau of Mines (USBM) was used by Litton and Page (1994) to correlate coal rank with spontaneous combustion potential. In that method, the SHTs of coal determined by an adiabatic experiment are linked with proximate analysis results through a proposed concept known as the “moist fuel ratio.” This ratio is a function of moisture, volatile matter and fixed carbon, all of which have widely different content percentages in different ranks of coal and have strong relationships with coal rank. However, the method is highly empirical, and there is large standard deviation between experimental data and calculated results. The equation correlating the coal quality parameters to determine SHT should be improved with more experimental data.This paper reports on the development of a new system for predicting the spontaneous combustion potential of U.S. coals, based on coal composition data from the U.S. Geological Survey’s coal quality database. First, the user is provided with a quantified classification of coal rank. Second, based on experimental SHT data covering a wide range of ranks from lignite to low-volatile bituminous coal, the original USBM correlation for predicting SHT is improved for the respective rank of coal. The relationship between the rank and SHT of U.S. coals was developed and plotted. The plot diagram can be used for a quick estimate of the SHT of a U.S. coal and as a cost-effective tool for the initial risk assessment of a new mine development."

Jan 1, 2015

By T. Karalis

Perlite is a generic term for naturally occurring siliceous rock. It is a form of natural volcanic glass the main constituent of which is amorphous silica (70-76%). Perlite, when heated rapidly to its softening temperature range, expands from four to twenty times its original volume, due to the presence of 2-6% ?combined? water, in a manner similar to popcorn as the H2O molecules vaporize and create countless tiny bubbles, which account for its exceptional physical properties: light weight (30-150 kg/m3), low thermal conductivity, cellular structure, in general. These properties make perlite adaptable for numerous end-uses, which can be distinguished into 2 categories: Expanded perlite applications in: a) Construction Materials market (e.g. Acoustical Tiles, light-weight insulating Mortars, self-levelling Concrete), b) Agriculture (e.g. Hydroponics), c) Food and Chemical industry (e.g. Filtration Media, Filler, etc.), d) Insulation and Heat resistance technology (e.g. Cryogenic vessels, Refractory Bricks, etc.). Unexpanded Graded perlite applications in: a) Phosphoric Fertilizers industry (additive in H3PO4 production), b) Foundry technology (slag-aid, insulating and heat resistance agent).

Jan 1, 2006

By Ahmet Tezcan, Zeki M. Dogan, Yalçin Kaytaz

Autogenous grinding in Turkey was first applied to quartzite where the mill is grate discharge type with an internal diameter of 2.99 m, having a length of 3.20 m and a capacity of as to 11.0 tons per hour. The second autogenous grinding was applied to a copper ore at Murgul Cakmakkaya Flotation plant of (KBI) Black Sea Copper Works having three mills 26 feet in diameter and 10 feet in length in close circuit with hydrocyclones. Recently, alterations were made in grinding circust by adding pebble mills. Furthermore, rubber liners and lifter bars were introduced pebble extractor and classifier were new features in the primary mills and circulating load was reduced by 20-50 tons per hour. At the end of these charges, capacity of each mill line was increased to 48 tons per hour with a full capacity of more than 9000 tons per day. Thirdly, autogenous grinding has been executed successfully on the slags of Samsun Smelting Plant of (KBI) Black Sea Copper Works with a mill of 20 feet in diameter and 6 feet on length having pebble mill following autogenous grinding.

Jan 1, 1992