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By F. Scott Carpenter

During the past several years, more frequent reference to Wollastonite has appeared in print, both in this country and abroad. The reason for this is the apparent growing interest in this mineral as it approaches commercial maturity. Twelve years ago, wollastonite was available in only limited commercial quantity. In 1933, a deposit in California was worked for a short time to provide a calcium silicate raw .material for the manufacture of mineral wool* It was not until the spring of 1953 that Cabot Corporation put into operation a modem commercial plant to produce this material in a variety of grades. These grades covered both a range of particle size and of particle shape. At that time, applications for wollastonite were largely speculative, although a few commercial applications in glass frits and welding fluxes did exist, For all practical purposes, it was a new material for which few commercial uses had been fully proven.

Jan 1, 1964

By Y. Jinnouchi

An air-pulsated jig has been widely adopted as a main coal washer. It may be mainly because of its many technical and economic features such as large capacity, low running cost, long life, etc. However, the recent increasing demand of fuel coal requires a higher productivity and efficiency of the air-pulsated jig. To fill this requirement theoretical and experimental investigations have been conducted on model and practical jigs in Japan. This paper generalizes the results of these investigations. In jig operation it is essentially of the most importance to create efficiently the pulsation of the water best suited for coal washing. The optimum pulsation should be determined by the theory of jigging process, and the method to realize it by that of pulsating mechanism.

Jan 1, 1982

By J. K. Horbaczewski

The reclamation of an open dragline pit (Pond A3P-2) at the Gibbons Creek lignite mine in east-central Texas required neutralization of acid mine pit water. At the start of treatment with hydrated lime (Ca(OH)2) on March 28, 2000, the pond had partially filled with 913,000 m3 (740 acre ft) of pH 4.9 water. Another 666,600 m3 (540 acre ft) of pH 3.3 water was pumped in from an adjacent pit (PitA3P- 1). By the end of the project (July 5, 2000), a combined volume of 1,579,000m3(1,280ac-ft or 417milliongal) in PondA3P-2 had been successfully treated to pH 8.2 with 431 t (475 st) of lime. This was two to three times more neutralizer than laboratory trials and detailed chemical titration had predicted. The main reasons for the difference are thought to be the inadequate representation in a laboratory setting of some of the chemical reactions that occurred in the field, including incomplete mixing of reactants, reactions with clay minerals in the pit walls, the kinetics of biologically-mediated reactions and the kinetics of aluminum oxyhydroxide polymerization (aging).

Jan 1, 2002

By A. G. Yapo, T. W. Camm

"Mining plays a key role in the development of modern civilization as a source of essential raw materials and provider of essential fuels, producer of jobs and a factor in support of the international balance of monetary payment (Camm, 2014). Professionals in mining locate, develop, design and manage ore deposits in an environmentally safe and profitable manner. As mineral deposits become increasingly scarce, new challenges face the industry. A current trend is to an increased emphasis on underground mining techniques for deeper deposits. Operations are safer now than before as companies understand better their work environment and the importance of mining responsibly.A continual challenge for the industry is accurately reflecting the costs and selling price of ore. An enduring characteristic of mining is the situation where the market typically determines the price of a commodity; the main control a company has on the bottom line is to control the cost of production.An attempt to bring light and clarity to the cost of their business will give a better idea to investors on the true profitability of the mining business. Gold producers face this struggle to accurately reflect the cost of production while also seeking to attract the interest of the investment community (Hill, 2013). In order to have a consistent format to report on their production costs, leading gold producers, through their alliance inside the World Gold Council (WGC), worked on the adoption of a new cost framework: the all-in sustaining cost (AISC) and all-in cost (AIC).Since 1996, the traditional cash cost reporting has focused only on the mining and processing costs incurred in mining an ounce of gold, which included the costs of goods sold (labor, energy, and consumables costs) and royalties (Table 1). But cash cost reporting ignores many important aspects, like sustaining capital, general and administrative expenses and site rehabilitation at the end of the mine life (Whelan, 2013). The cash cost was used to attract many investors into the business. In fact, the high gross margin (sales minus cash costs) has been promoted in past decades by the industry instead of the net or operating margin. As a result, even when the gold price was high, nearly $61/g ($1,900/oz) in August 2011, gold producers were not reporting excessive profits in their cash flow/income statements, to the disappointment and incomprehension of investors (Milstead, 2014). The truth was simply that the other costs omitted in the traditional cash cost were reducing the apparent profits.The disconnect led to a need for more accurate cost reporting in order to win back investor confidence and provide better understanding of gold mining economics. In 2012, the senior gold mining companies, including Gold Fields, Barrick Gold Corp. and Newmont Mining Corp., worked with the WGC to develop a new measure. This resulted in the June 2013 publication of the new framework AISC and AIC, which has been widely embraced by the sector since Jan. 1, 2014 (WGC, 2013).The adoption of the new cost template would have the dilemma of showing the real profitability of gold mine properties, which might alleviate taxes from governments and legislators, but it might also scare off investors toward more lucrative industries if not winning back their confidence."

Jan 9, 2017

By S. Potgieter-Vermaak, T. T. Chiweshe, W. Purcell

Complete isolation of chromium (III) from the reference material (SARM 131), Upper Group 2 (UG2) chromite ore, and Merensky Reef mineral ore was achieved using ammonium phosphate salt as flux. Optimum pH (3.2–3.8) conditions and sample to flux ratios (1:25) were some of the factors that were critical for the complete isolation of chromium. Increasing the sample to flux ratio (1:50 excess) however resulted in the conversion of all the elements in the melt into a green solution (pH, 5.8–6.7). A different chromium compound was subsequently isolated from the green solution by allowing this solution to stand in an open vessel in a cupboard for a month during which time the pH decreased to pH 3.5–4.2. Quantitative analyses of chromium from the isolated precipitates of SARM 131, UG2 chromite ore, and Merensky Reef mineral ore indicated chromium contents of 41.87, 60.41, and 23.93% respectively which were very close to the chromium content in the original samples. Analysis of the chromium precipitates using IR indicated the presence of phosphates (1100–1200 cm−1 ) while SEM-EDX analysis showed the presence of microscopic crystalline particles with Cr, P, and O as the major elements. Further characterization of the chromium precipitates using XRD and Raman successfully identified the product as chromium (III) metaphosphate C-type (Cr(PO3)3, JCPDS no. 01-077-0672), in the isolated chromium precipitates.

By Richard H. Johnson

White Pine Copper Company began operating a plant designed to recover copper matte particles from its discarded reverberatory furnace slags in April, 1972. Seasonal operation, generally the months of April through November, continued through October, 1974, shutting down due to feed exhaustion. White Pine reverberatory furnace slags contained economically recoverable amounts of copper for a variety of reasons. Among them: 1. White Pine concentrates yield extremely high matte grades (65+% Cu) and viscous slags. The viscous slags hinder matte settling causing matte "prill" entrapment in the slag 2. White Pine's total refined copper output is accomplished through fire refining requiring special techniques for impurity removal, especially small amounts of nickel introduced from purchased pyrite and chalcopyrite fluxes. These special techniques result in high-copper slags, refractory to smelting, being reintroduced into the reverberatory furnace. 3. Furnace bottom build-ups resulting in mechanical matte entrapment through the formation of "dams" hindering matte flow. 4. Occasional concentrate fluxing and furnace atmosphere control problems.

Jan 1, 1975

By Del Brock, Dan Wooton

The design/build of two adjacent vertical mine shafts in difficult ground conditions at a mining complex in the midwestern United States required innovative construction techniques. Construction of the 267-m-deep Service Shaft required full depth dewatering wells and ground freezing. Blind drilling was utilized to excavate the 257-m-deep Production Shaft and it was finished with a steel/concrete composite liner that was floated into place. An equally unique component of the installation included supplying a high capacity vertical conveyor system, featuring a 273-m-lift. Other components of the project include the mine level development, as well as the design and installation of three hoisting systems, including a 45-ton capacity men/materials hoisting system.

Jan 1, 2003

By Elham Najafi, Sina Ghassa, Ata Akcil, Hadi Abdollahi, Sandeep Panda, Zohreh Boroumand

The present study investigates the influence of ferrous iron (as FeSO4) and ferric iron (as Fe2 (SO4)3), and pyrite (FeS2) on the ability of bacterial leaching of a high-grade sulfide Zn–Pb ore. In this regard, shake flask experiments were carried out at 5% (w/v) pulp density of the ore sample (having 40.7% Zn and 12.4% Pb initial metal content) using a consortium of mesophilic iron and sulfur-oxidizing acidophiles. A concentration of 0.04 mol/L of ferric iron in the leaching media was found to be optimum for zinc extraction without affecting growth of the microorganisms. Under this concentration, the dissolution of Zn, Pb, Cd, and As was found to be 57%, 0.2%, 0.03%, and 9.9% in 25 days. Using ferrous iron in the media, 0.16 mol/L of Fe2+ was found to be the optimum concentration for efficient bacterial growth and metal dissolution (54.6% Zn, 0.08% Pb, 0.03% Cd, and 10.2% As) from the sample in 25 days. On the other hand, using pyrite as the source of energy for bacterial growth, an initial 12-day lag period was observed when compared to the effect of ferrous iron in the media. Under the optimum concentration (test with 0.24 mol/L iron in the form of pyrite), the dissolution of Zn, Pb, Cd, and As was found to be 39.8%, 0.1%, 0.03%, and 10% in 25 days. The surface chemistry analysis indicated formation of a sulfur layer over the particle surface that hindered reagent diffusion and affected metal recovery through bioleaching.

By William Gleason

"The mining industry tends to focus on very large numbers, whether it’s talking in terms of size of deposits, tons of material mined, the equipment used or the dollars spent. The numbers associated with mining projects are often in the hundreds of millions, but sometimes it’s the little things that can have the biggest impact.Take, for example, the Rosemont Copper Project in Arizona. Owned by HudBay Minerals, the Rosemont Copper project, when in production, is expected to be one of the largest copper mines in the United States, accounting for about 10 percent of total copper production with annual production expected to be 110 Mt/a (243 million lbs/year). However, the project is currently mired in a years-long permitting process. At the 2017 SME Arizona Conference in Tucson, AZ, Kathy Arnold, director of environmental and regulatory affairs for Hudbay Minerals, spoke about the project and the efforts to get it into production.She opened her presentation with the unfortunate news that her 2017 presentation would not be that much different than the 2016, 2015 or 2014 presentations she gave to the same conference. That’s because, as of Dec. 4, 2017, the project had been in the permitting process for 3,797 days, more than 10 years. The process began when Rosemont submitted its initial mine plan in 2006 and a revised one in 2017. The official start to Rosemont Copper’s National Environmental Policy Act (NEPA) started in 2008.In June 2017, the project received its Final Record of Decision from the U.S. Forest Service, moving it a step closer to production. Yet it still faces stiff opposition from opponents while it works to secure the Clean Water Act Permit from the U.S. Army Corps of Engineers and to complete its final mine plan of operations.In her presentation, Arnold said the long process taught her many lessons, including approaching things with a different mindset. More than 130 pages worth of public comments have been collected over the years. The concerns expressed range from lighting issues to pavement to preserving land for a jaguar that was spotted on the property and named El Jefe.“A lot of things that people worry about seem to be small things, but we had to have a different mindset and be open-minded to the concerns,” Arnold said. “That is the commitment we made.”"

Jan 1, 2018

By S. D. Michaelson

Open pits and quarries are the major sources of all "hard rock" tonnage mined today. Normally, ore is fractured from the pit face by blasting and then truck-hauled to a primary crusher where processing begins; over- burden (or waste) is generally truck-hauled from the pit to dump areas. Truck haulage of blasted ore and overburden accounts for some 25 to 50 percent of total mining costs in a typical open pit and commonly is the largest single cost factor. Obviously then, cost reduction efforts should properly focus on improving existing haulage systems and developing new breakthrough techniques for material transport. Continuous flow systems for large tonnages ordinarily will result in a lower cost than batch systems such as truck or rail haulage. Continuous flow with pipelines for liquids and slurries, or conveyors for medium to coarse dry materials (in the -8 in. range) are the accepted economic answers for bulk materials handling over reasonable distances.

Jan 1, 1968

By Bert C. Morrison

In 1961. American Smelting and Refining Company was conducting exploration for lead in southeastern Missouri using several geophysical methods. Electrical methods were used in almost every hole drilled during this period. These methods met with only limited success, with one exception. This paper deals with that exception: An Electrical Potential Method used at a single hole to indicate direction to better mineralization. This method was notably successful in the program.

Jan 1, 1970

By F. J. Hurst

Phosphate rock, which is a prime source of phosphate used in fertilizer manufacture in the United States, contains uranium. In general, the uranium content of the rock increases with the phosphate content and most high-grade phosphate deposits (>30% P2O5) contain 0.01- 0.02% U3 8. The large tonnages of rock being mined represent a significant potential source of uranium that lends itself to recovery as a by-product of the wet-process phosphate industry. For example, in 1953, the U. S. Geological Survey estimated that recoverable phosphate reserves in the U. S. totaled about 5 billion tons and contained 600,000 tons of uranium. I This estimate did not include any rock from North Carolina which has since been estimated at about 2 billion tons. For the most part, the known, economically mineable U. S. reserves - estimated at about 7 billion tons - are concentrated in a few areas: 43% in the western states of Idaho, Montana, Utah and Wyoming; 28% in each of Florida and North Carolina and less than 1% in Tennessee. In the past, Florida has supplied about 80% of the total U. S. production, practically all of which is land pebble phosphate. All forecasts indicate increased production rates from North Carolina and the western states.

Jan 1, 1976

By A. C. Bigley

Before going into this subject, I would very much like to call to your attention some past history on patents granted by the United States Patent office that involved ammonium nitrate. On February 10, 1885, a patent was granted to Russell S. Penniman. "The object of this invention is to securely protect ammonium nitrate against deliquescent and to maintain it in substantially its normal disintegrated condition, so as to afford a new product suited for ready use in the manufacture of high explosives, and enable the immediate admixture thereof with any of the well known explosive substances or compounds heretofore employed. 'Whether the nitrate be thus granulated or otherwise reduced to a granular or divided condition, it is then thoroughly mixed with about twelve (12) percent of the fluid or semi-fluid carbonaceous protecting medium, which forms a readily applied jacket or coating for the granules of nitrate and also serves as a carbonaceous element in such explosive compounds as it may thereafter be employed in."

Jan 1, 1958

By J. A. Harrison

Most coal being used in the United States has been subjected to one or' more processes of coal preparation. The physical and chemical characteristics of a coal have a marked influence on the ultimate uses that coal may have. The selection of the proper preparation processes may similarly be important in producing the best practical coal product for any particular use. The physical composition and distribution of physical constituents in the coal will partially determine the efficiency of the preparation process chosen and conversely distribution and concentration of coal macerals will, to a degree, be controlled by the preparation process. A number of preparation processes have been evaluated to determine this interrelation. If a coal having' certain specifications is desired, these evaluations trill assist in providing information needed for the production of this coal.

Jan 1, 1962

By Richard A. Thomas, III JAMES H. ROWLAND, Liming Yuan

This paper presents the results of large-scale fire experiments on evaluating the performances of carbon monoxide (CO) and smoke sensors at low ventilation velocities. Experiments using three different combustibles — conveyor belt, coal and diesel fuel — were conducted in the experimental mine at the U.S. National Institute for Occupational Safety and Health (NIOSH) Bruceton Research Facility. A total of eight sensor stations were located downstream of the fire with each station containing sensors for CO, smoke, carbon dioxide (CO2 ), oxygen (O2 ), humidity, barometric pressure and temperature, as well as two airflow sensors. The airflow velocity ranged from 0.22 to 0.26 m/s (44 to 51 fpm) in the tests. The response times were recorded for the CO and smoke sensors at each sensor station when smoke and gaseous products of combustion from each burning combustible reached the station. The response times of the CO sensors were used to determine the appropriate sensor spacing in the belt entry with a low air velocity. The performance of the smoke sensor was found to be affected by the high humidity in the experiments. The results on proper selection of sensors and the determination of sensor spacing at a low ventilation velocity can be helpful for ensuring sufficient early fire warning for underground workers, thereby improving the health and safety of miners.

By Peter N. Calder

There is little doubt that the stability of both highwalls and spoil piles is essential to efficient strip mining. Accurate determination of the appropriate geotechnical parameters will pay dividends during mining, but only if the mine operation closely follows the engineering plans which have incorporated These factors. Productivity is invariably higher in mines where failure of highwalls and spoil piles does not occur. This is the result of the reduced rehandle and better working conditions found in stable mines. Control of the waste piles and highwalls also leads to better coal recover since failures can result in the burial of uncovered coal, which is then lost to mining. Safety is an important consideration. The importance of providing a safe working place for employees and of protecting costly mining equipment is hard to overemphasize. For miners, working in areas where instability exists, the degree of hazard involved in their occupation is increased particularly where night operations are involved. It is true, too, that there have been many cases where loading equipment has been buried and severely damaged by failures.

Jan 1, 1980

By Y. Ye

Typically, rougher molybdenite flotation and recovery from bulk copper/ molybdenum concentrates involves the use of alkalisulfides, Nokes reagents, cyanides, oxidants, and/or thermal treatment for the depression of copper sulfide minerals. The bulk copper/molybdenum feed generally varies from 0.2% Mo to 1.0% Mo, and with traditional reagents the single-stage rougher flotation recovery of molybdenite varies between 40 and 90% at a concentrate grade of 5 to 10% Mo. With ozone conditioning for copper depression, however, improved separations appear to be possible, as demonstrated by tests with Cu/Me concentrates from both the Phelps Dodge Morenci Operations and the Kennecott Copperton Operations. Single-stage rougher flotation after ozone conditioning can provide a molybdenum concentrate at a recovery of more than 90% and a rougher concentrate grade higher than 20% Mo in some cases. Subsequent cleaner flotation with additional ozone conditioning results in relatively copper-free molybdenum concentrates containing as much as 52% Mo. Preliminary analysis indicates that, with a multistage ozone conditioning/flotation strategy, the process is technically and economically viable and should be suitable for industrial application.

Jan 1, 1990

By Evan Dressel, Mark S. Diederichs, Kathy Kalenchuk

As hard rock mining develops deeper over time, there is an increasing need to predict the spatial and temporal distribution of adverse seismogenic rockmass reaction to mining. Real-time monitoring and feedback of mine data are used to tactically manage risk associated with induced-seismicity; however, strategic risk management requires reliable tools for forward predictions of seismic hazard. The forward prediction of seismic hazard is strengthened by understanding of potential seismic intensity, which often relies on well calibrated mine-wide numerical models. This paper uses a case study to explore how future seismogenic potential and the nature of future seismicity can be domained according to numerically predicted stress-strain paths at past seismic event locations. Delineation of high confinement seismogenic volumes vs. lower-confinement, high-strain seismogenic volumes at the mine-scale can be achieved, based on a loading and unloading stress path analogue, to refine understanding of seismic intensity. Practical qualitative and quantitative methods to achieve this delineation will be demonstrated. Once seismogenic mode (high-stress vs. high-strain) is identified, detailed analyses of seismic source parameters demonstrates change in seismic hazard between the domained volumes.

Apr 26, 2022

By V. F. Hollister

Computer programs developed as part of the PROSPECTOR project at SRI International can indicate where the highest grade hypogene copper occurs in porphyry copper prospects. The programs are useful in selecting drilling targets in untested porphyry deposits. Because of mineralogic, structural and lithologic variations in porphyry-type deposits, three distinct computer programs have been constructed; however, this paper considers only the stockwork type in homogeneous rock (similar to the Lowell and Guilbert model). The programs represent models in the form of inference networks that utilize the mineralogic, alteration, lithologic, structural, geochemical and geophysical data normally collected prior to a drilling decision. One example of an application of the PROSPECTOR program for a stockwork-homogeneous porphyry is given: Island Cooper in British Columbia. Computations based on the surface geologic, geochemical and geophysical data for Island Copper clearly disclose the best hypogene grade of the deposit. Other deposits were tested in the programs as well, and in each case PROSPECTOR programs indicate the region with the highest hypogene grade.

Jan 1, 1983

By T. B. Thompson

The Cripple Creek diatreme-intrusive complex is known primarily for its vein telluride-gold ores and, for major veins, their great vertical range (>990m). Less well-documented are the ores dispersed into the wallrocks adjacent to veins, the ores associated with hydrothermal and tectonic breccias, or mineralized zones within fluvial, lacustrine, and volcaniclastic rocks deposited within the diatreme complex. The ore-gangue minerals Here precipitated from oxidized, alkaline fluids that yielded an abundance of carbonate, sulfate, and oxide minerals along with minor base metal sulfide and precious metal telluride-s. Wallrock alteration is quite limited adjacent to veins and somewhat more extensive within hydrothermal and tectonic breccias.

Jan 1, 1991