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By Philip Thompson

A part of the Bureau of Mines mission is to help improve the Nation's mineral posture by providing the technology for utilizing low-grade ores. In this regard, laboratory testing by the Bureau of Mines has shown that the removal of insoluble slimes using selective flocculation and flotation is a viable method for treating low-grade potash ores that have a high content of water-insoluble impurities. Results indicated that over 82 percent of the insoluble slimes could be removed from sylvinite ore containing 5 percent water insolubles and 13 percent K20 by using nonionic or cationic polyacrylamide flocculants and cationic, anionic, and/or nonionic collectors. Subsequent potash flotation recovered 87 percent of the potash in rougher concentrates containing 57 percent K2O. Sizing and cleaner flotation of the rougher concentrates upgraded the products to 60 percent K2O. Filtration of the water-leached insoluble-slimes flotation concentrates on a bed consisting of leached insoluble-slimes concentrate mixed with potash flotation tailings recovered 80 percent of the brine. Filtration rates using the mixed bed were nine times faster than filtration rates obtained when the insoluble-slimes flotation concentrates were filtered separately.

Jan 1, 1979

By AIME AIME

THE petroleum engineers have the conference habit. They drop in, thresh things over, and drop out. No time is wasted. So it was at the Fort Worth meeting of the Petroleum Division, Thursday and Friday, Oct. 8 and 9; headquarters, Blackstone Hotel. Associate Chairman Albertson arrived the morning of the 7th, to tie in any loose ends of the technical program. S. M. Greenidge, chairman of the local committee, checked the arrangements with his committeemen at a luncheon that noon. By mid-afternoon the next day's attendance was anybody's guess-there were no noses to count. But when the gavel sounded Thursday morning 175 members and guests were present, also the official A.I.M.E. party consisting of President Lovejoy, Secretary Parsons, and George Otis Smith. Shortly after adjournment Friday afternoon all but a handful had vamoosed, lit out, disap¬peared. But, in the meantime, it was a grand conference, attendance maximum every session, and the discussion fast and furious. The discussion came from all over the floor, sometimes as good-natured sniping, sometimes in long volleys that were almost fatal to the reporter. Everyone knew his subject and few there were who had nothing to say.

Jan 1, 1936

By Andressa Alves da Silva

Nowadays, population growth and the interest of food industry, makes the research and applications of biodegradable polymers increase, because under favorable conditions its degradations may occur within weeks or in a few months, reducing the environmental impact. This work presents the processing and characterization of flexible films by the incorporation of 3 % (% wt) of modified bentonite light green clay in the Copolyester/PLA biodegradable blend. The clay incorporation was carried out by melt-mixing processing, using a twin screw extruder machine. The films were obtained by cast extrusion tape. The films obtained were submitted to tensile tests, SEM and XRD analysis, and the correlation between their properties was discussed. The XRD results of clay showed that the quaternary salt and sodium carbonate addition increased the interlayer distance of clay making it easier to intercalation of blend in the nanoclay. The XRD results of PBAT/PLA/Clay nanocomposite show no characteristic organoclay peaks. This result suggests intercalation between nanoclay and matrix (blend). The tensile test results showed an increase of around 30% in tensile strength at break of nanocomposite film when compared with blend film.

Aug 8, 2018

By Aldin Ardian, Mustafa Kumral, Jagjit Singh

Risk assessment of mining projects is a requirement in the mineral industries. In this process, many risk variables are timedependent, and the only available data are historical time series. Moreover, in the case of a multivariate scenario, conventional forecasting methods fail to capture conditional dependency across the variables, which is important when there is an underlying causal relationship that needs to be modeled for accurate project evaluation. Thus, we investigated the use of copulas to capture the conditional distribution of the factors involved in a mine risk assessment study. We employed a multivariate copula-based time-series approach to model several uncertain variables. The Autoregressive Fractionally Integrated Moving Average - Generalized Autoregressive Conditional Heteroscedasticity (ARFIMA-GARCH) model was used for the conditional mean and copulas were used to model the error distribution, thus capturing the collective variation and dependence pattern across the variables. The method was implemented to model gold prices, copper prices, and the 10-year US Treasury bond yields and to determine the project’s net present value and probability of being economically feasible. The proposed approach can be used for cases where simulation of multivariate time-series is conducted.

Apr 13, 2021

By L. G. Marshall

WHILE surveying in a small Western mine, the following problem was encountered: Two traverses had to be connected by running a traverse line down the main hoisting shaft, which was the only connection between the two levels. The shaft was inclined at about 80 deg. from the horizontal and measured 8 by 10 ft. The distance between levels was about 110 ft., measured on one side of the shaft. The surveying equipment consisted of a transit, tripod, level rod, 100-ft. chain, and plumb bobs. There were no side or top the- scope attachments with which to take large, vertical angles. Therefore, we were confronted with the problem of taking readings between two points, one of which could not be seen through the instrument when set up under the other point, owing to the obstruction of the horizontal plate, and of measuring the distance between these points with a chain that was too short. The method of a line of plumb bobs down the shaft was impractical because a setup would be needed part way down the shaft, which would call a halt to all hoisting operations for some time. After considerable experimentation the following method was used.

Jan 1, 1936

By M. J. DeMarco

Beginning in late 1985 and continuing through 1987, Bureau of Mines personnel investigated longwall chain pillar and entry design in two-and three-entry gate-road systems at a deep underground coal mine located in central Utah. To evaluate their respective stability characteristics, four chain pillars and two longwall panels within the two separate entry systems were instrumented with Bureau of Mines hydraulic borehole pressure cells to continuously monitor vertical and horizontal pillar and panel stresses through adjacent panel retreat. In addition, supplemental entry closure information was obtained from sites located in the vicinity of the instrumented pillars. The findings presented in this report demonstrate the practicality of evaluating mine pillar stability using in situ methods and support three significant conclusions regarding ground control aspects of the investigated two-entry system: (1) Total areal entry loading was considerably less for the two-entry system, as opposed to the three-entry system, (2) a smaller percentage of opened ground in the two-entry system contributed to a marked reduction in roof falls, and (3) lower areal loading in the two-entry system suggests improved ground conditions when mining the underlying seam.

Jan 1, 1988

By Jon Kellar, Samuel Kessinger, Prasoon Diwakar

Tantalum (Ta) and niobium (Nb) are extracted from many different ore types. The major economic orebody mined for tantalum and niobium consists of tantalite ((FeMn)Ta2O5) and columbite ((FeMnNb2O5)) in a solid-solution mineral commonly referred to as “coltan.” The largest supplying region, The Democratic Republic of the Congo (DRC), is unfortunately also the most ethically compromised source for this critical mineral. Officially, the U.S. government has deemed coltan ore from the DRC a “conflict mineral” [1]. The lack of pragmatic and effective local mining regulation in Central Africa, when coupled with high levels of violence and corruption, has spawned a widespread, illegal, unethical and, most importantly, unsafe economy. This illicit economy is centered around first, illegally mining these valuable conflict minerals and second, smuggling these minerals into the global supply chain. Handheld spectroscopy devices could provide further transparency to these opaque supply chains, giving miners, traders and refiners the ability to authenticate the provenance of the minerals they encounter, and allowing companies to prove compliance with the regulatory agencies attempting to curtail illicit mining.

Mar 1, 2025

By M. Mohammadijoo, J. B. Wiskel, D. G. Ivey, S. Kenny, H. Henein

Cold-wire tandem submerged arc welding (CWTSAW) has recently been developed as a novel welding technique to replace the conventional tandem submerged arc welding (TSAW) process and improve the productivity of pipeline manufacturing. The process involves two electrodes with arcs and one electrically cold electrode. Since heat-input of the welding process is a key factor affecting the properties of the weld metal (WM) and the heat-affected zone (HAZ), and the additional cold-wire affects the heat introduced to the weldment, it is of interest to investigate property and geometry changes in the WM and HAZ when a cold-wire is added to the welding process. In the current research, the CWTSAW process is investigated and optimized by correlating the main welding parameters with the micro-hardness of the WM and HAZ and the geometry of the weld, i.e., the bead width (BW), penetration depth (PD), reinforcement area (RA) and coarse grained heat-affected zone (CGHAZ) area. Three statistical and mathematical methods are employed to optimize the CWTSAW process in terms of the mechanical properties and WM and HAZ geometry of a typical microalloyed steel used for pipeline manufacturing.

Jan 1, 2015

By Nicholas Kyriazi

The Bureau of Mines subjected three commercial compressed-oxygen self-contained self-rescuers to a series of laboratory treatments designed to simulate various environmental conditions in underground coal mines. The environmental treatments consisted of extremes of temperature and of shock and vibration. The tests were designed to predict the ability of the self-rescuers to withstand those environmental stresses without causing a decrease in wearer protection. A critical concern was internal damage to an apparatus that would cause it to malfunction or seriously degrade its performance without any obvious external signs. The Bureau has previously tested chemical oxygen self-contained self-rescuers in a similar research program. Although the three compressed-oxygen units are not as sturdy as the chemical oxygen self-rescuers tested previously, they performed reliably after treatments on treadmill tests with human subjects and on machine tests using a breathing and metabolic simulator. Serious damage was caused by both the heat treat-ment of 71° C (venting of the 02 bottle in most cases), and in the shock treatment (breaking open of the case and dislodging of the components). When physical damage is obvious, a complete refurbishing of the damaged self-rescuer is recommended.

Jan 1, 1983

When solid pillar is not left to separate different mining levels in underground mine with high dip angle deposit, waste rock in the backfilled stope could be a safety hazard to future mining activities on levels above or below the backfill. Different backfill methods can be used to eliminate this hazard according to the deposit shape and mining method. Building concrete pillar in ore drift of each mining level is one of them. Concrete pillar had been constructed in underground mines based on operational experience. Little design literature and pillar performance data can be found. At Great Basin Gold Hollister Mine, over two thousand feet of concrete pillar had been constructed. The project started with engineering design which combined civil engineering concrete design and the specialties of underground construction. Time Domain Reflectometry technique was installed to monitor the pillar movement and concrete cylinder samples were collected and tested for quality control. Engineering design, underground construction, quality control and concrete pillar monitoring, as well as precious concrete mixing data from years of experience are fully covered in this paper to give a general frame of concrete pillar method.

Jan 1, 2010

In 1987 the control strategies at the then ZC Mines' New Broken Hill Consolidated concentrator were a miscellaneous mixture of computer hardware and technology for ISA, grinding and residue thickener control. Field instrumentation was based on current-to-air technology of approximately the 1960s. Decisions were made to rationalise computer and field instrumentation technologies; the object being to consolidate control loops into one system to enable expansion of the system to include all facets of plant operation. The first stage was to install a DEC Micro PDP 11/23 computer and serial line communication as recommended by AMDEL Ltd, for the ISA system, as discussed by Walsh and Freeman (1988). The second stage was to select and install a distributed control system for the centralisation of the control loops into one system, and to replace field instrumentation with state-of-the-art technology. This paper deals with the second stage of the rationalisation, in an attempt to give an insight into what is required when personnel are faced with such a decision, details of costs involved in keeping a system functioning and utilised; and the requirement to train personnel for acceptance of further control strategies.

Jan 1, 1991

By William F. Riggs

Inspiration Consolidated Copper Company, located in a semi-arid climate in Arizona, continually struggles with a water problem. This applies to quality as well as quantity. When the EPA considered installing a new centralized sewage plant to handle the combined waste from the municipalities of Globe and Miami, Arizona, they automatically assumed that He could use the sewage effluent for process water in flotation. The treatment plant was to be a tertiary system producing 1600 gpm of sewage effluent. Inspiration decided that this could possibly be a source of additional process water. It was decided to test sewage effluent from Miami Treatment Plant at the rate of 400 gpm since it was only a primary treatment plant. The 400 gpm was combined with the 5000 gpm of process water going to the Concentrator. After one week the results were disastrous. The recovery and final grade had each dropped approximately 5%. With the results from this brief run, it was concluded that sewage effluent from a primary treatment plant could not be used. Research was then brought into the problem to begin an evaluation of sewage effluent in flotation.

Jan 1, 1977

By John G. Baragwanath

THE September issue of the Engineering and Mining Journal carried an item regarding the Cercapuquio Mining Co. which was mentioned as a large producer of lead, zinc, and cadmium, situated near Huancayo, Peru. The paragraph caught my eye because I had not heard of the property in thirty years and I recollect all too well the circumstances of its accouchement. In 1916 1 was making my headquarters in the town of Huancayo, then the terminus of the Central Railway of Peru, and was examining mines and prospects in that general area for Cerro de Pasco. In the course of my work I became acquainted with an engaging and energetic "practical" miner named Balarin, a Dalmatian living in Huan¬cayo, and made numerous trips in his excellent company. One day Balarin came to the down-at-heels hostelry where I stopped and told me that a Cholo prospector, a character by the name of Jose, had just reached town and claimed to have made a discovery in a little known locality called Cercapuquio. Lead-silver, Balarin said, and showed me a sample of galena about the size of his fist. "Fine," I remarked. "When do we leave?"

Jan 1, 1947

By C. K. Leith

WE face the postwar problem of the use of minerals as sanctions to control the armament and the re-armament of the Axis powers at the source, minerals being the raw material of armaments. That is the subject of today's discussion. It is one thing to talk about controlling minerals in the interest of rearmament, and it is another thing to put any such ideas into effect. A provision for min- eral sanctions-not by that name but under broader terms-was contained in Article 16 of the League of Nations, and an attempt was made to apply min- eral sanctions when Italy cut loose in Africa. That was a failure because the plan was badly thought out. They did not have the right minerals included in the list. Also, they did not have the machinery set up at all. Somebody said to the League of Nations: Let's apply the sanction, and it was assumed that that was all that was necessary. It turned out to be a rather sad perfor- mance. However, that certainly cannot be taken as an example of what will happen if a properly thought-out pro- gram is adopted.

Jan 1, 1944

By H. R. Shell

The work on synthetic mica and related subjects is being reported in a series of technical articles (see Supplementary Bibliography), each of which describes some special aspect of the subject. This is the final report on chemical analysis of the fluoride-containing silicates. A condensation of this report has been published (26).3/ Chemical analysis affords one of the best means of ascertaining the final com-position of either a heterogeneous mass or a single pure crystal, particularly where some constituents may be volatile. The analysis of fluoride-containing silicates was not so well known or understood that highly accurate results were commonplace. For example, on synthetic mica a university laboratory reported 11.6 and 9.2 percent fluoride when at least 13.3 and 11.3 percent were present, respectively; a commercial testing laboratory reported 9.14 percent as compared to 12.6 percent; and a glass company reported 7.0 percent as compared to 9.0 percent present. No intimation is made that these analysts could not have done better, but the point to be stressed is that the methods in use were long, tedious, and generally required a certain familiarity for best results.

Jan 1, 1956

By Shigem Kuramoto

Pure copper is known to exhibit intermediate temperature embrittlement when it is deformed at a slow strain rate, and a small addition of zinc suppresses this embrittlement. In the present study, the relation between zinc addition and hydrogen behavior was taken into account since the impurity hydrogen is believed to deteriorate the ductility at intermediate temperatures. Pure copper and Cu-l mass % Zn alloy specimens are prepared by melting in argon and in vacuum, so that a comparison can be made between the specimens with normal hydrogen content and those with' less hydrogen content. Tensile tests are performed at temperatures ranging from room temperature to 600 "C, and hydrogen behavior is analyzed using a newly developed testing machine that can detect gas evolution from the specimens during deformation and fracture in ultra high vacuum. The small addition of zinc to pure copper decreases hydrogen content, leading to the improved ductility at intermediate temperatures. In addition, the samples of both pure copper and Cu-1%Zn melted in vacuum exhibited higher ductility at intermediate temperatures than those melted in argon atmosphere, which is attributed to reduced hydrogen content.

Jan 1, 1998

By Taiping Lou

The effects of slag composition, additive agents, and heat treatment conditions on the perovskite (CaO ? TiO2) crystal morphology, the precipitation behavior, the crystal growth and the volume fraction (VF) in the Ti-bearing blast furnace slags were investigated. The morphology of perovskite is dispersed dendriform in molten slags. The crystal growth mechanism of the remelting of fine dendrites and the coarsening of larger grains exists throughout the solidification of molten slags. With the temperature decrease, the VF was increased and Perovskite transformed from fine dendrites to coarsening ones or equiaxed grains. The lower cooling rate can increase the VF and coarsen the grain obviously, while higher cooling rate will decrease the VF and reduce the average equivalent diameter (AED) of Perovskite. When .increasing the content of CaO and Fe20}, the VF can increase obviosly. However, high basicity will give rise to the increasing of viscosity of slag, which result in the reducing of the AED. The experimental results showed that additive CaF2 and MnO can efficiently decreased the viscosity of the slags, and obviously improved the morphology of perovskite and promote growth.

Jan 1, 2000

By Clyde E. Williams

MODERN steelmaking has gradually evolved from an inefficient small-scale operation, utilizing tiny units, to a highly efficient one utilizing large units almost completely mechanized. The leading position of the United States in the steel industry is due to the possession of easily assembled high-grade raw materials and large-scale highly developed plants. Modern integrated steel operation is largely one of material handling. Mining and transportation of iron ore, coal, and fluxes, coking the coal in by-product ovens, smelting the ore with coke and limestone in blast furnaces, converting the resulting pig iron into steel in the Bessemer, or in the open hearth when supplemented with scrap, and fabricating the resulting steel ingots in the shapes of commerce all are done on a huge scale, mostly by machinery, most of the labor being employed either in operating the machine or keeping it in repair. At the same time the quality and uniformity of the product have been greatly increased by the development of scientific knowledge and operating skills. Thus, the steel industry in this country is highly developed both mechanically and technically.

Jan 1, 1942

By H. L. Monroe

Meramec Mining Company, owned 50% by St. Joseph Lead Company and 50% by Bethlehem Steel Corporation,- is engaged in the mining, concentrating and pelletizing of iron ore from the Pea Ridge Mine which is located in the rugged, wooded Missouri Ozarks about 15 miles from the town of Sullivan or 75 miles southwest of St. Louis. The orebody was delineated in the middle 1950's by the St. Joseph Lead Company during the Company's intensive exploration program to discover new lead orebodies to replace the declining reserves of the famous Southeast Missouri Lead Belt. An airborne magnetometer survey was run by the U.S. Geological Survey, the Missouri Survey and several mining companies, (of which St. Joseph Lead Company was the principal supporter). The survey was published in 1950 and disclosed an anomaly in the vicinity of Pea Ridge. In 1950 test drill holes disclosed that under some 1300 feet of sediments there did exist an iron deposit of probable commercial significance. No further action was taken until 1956 when additional drill holes confirmed beyond reasonable-doubt-that this was a major iron ore discovery.

Jan 1, 1965

By Paul B. Batten

Shutdown is a generic term for what may be called an Outage, Turn Around (TAR) or Overhaul etc. Running a plant shutdown well has always been key to the financial contribution of a mine. However, something important has changed. The post pandemic reality is that it is harder to retain workers and many of those near retirement just didn’t come back to work. This is creating a shortage of experienced people and a workforce that changes employers easily. We are seeing the impact of this manifested in the erosion of established maintenance and supply chain processes that now struggle to yield the plant runtime that could once be taken for granted. The scope, cost and duration of a shutdown varies widely depending on the nature of the work and the equipment being renewed. The PM of an electric shovel might require a week of downtime and cost $100,000. A gold plant may need to go down for 3 days when its time to change mill liners and cost $500,000. A turnaround in a refinery can take more than a month and cost multi millions. Despite the huge differences.

Jan 1, 2023