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By Stephanie L. Kaster, John G. Speer, Blake M. Whitley

Niobium-microalloying technology has been increasingly applied in a wide range of steel applications over the past half-century, to increase strength, control microstructure, enhance properties and enable a variety of applications. To achieve desired performance levels, thermomechanically processed microalloyed steels are widely supplied by the steel industry for high volume applications in hot-rolled plate, sheet and structural steels. However, in steel long products and forgings, the final properties are often generated by downstream users, after heat-treatment, surface hardening, forging or wire drawing. Two examples are presented highlighting advancements associated with Nb-microalloying, to enhance microstructures and properties developed during thermomechanical and/or downstream processing. In the first example, a 0.02 wt. pct. Nb addition was made to a medium-carbon bar steel intended for induction-hardening applications requiring fatigue and fracture resistance in bending and torsion. The Nb addition as well as thermomechanical bar processing led to beneficial refinement of both the pre-induction and post-induction microstructures. In the second example, a 0.01 wt. pct. Nb addition to a high-carbon wire rod was found to refine the pearlite colony size and interlamellar spacing, and increase the hardness.

Oct 1, 2019

By W. H. Pomroy

Spontaneous combustion fires in deep metal mines, through relatively infrequent, are nonetheless cause for considerable concern because they pose a direct threat to the safety of miners and are quite disruptive to mine operations. They often occur in remote, inactive, or abandoned sectors of a mine where access for firefighting is difficult or impossible. Over half of all noncoal mine fires that last more than 24 hours are caused by spontaneous combustion. The most common means of fire control for spontaneous combustion fires is sealing and/or Flooding the affected zone. This process is never easy, but it is made especially difficult (and hazardous) if the fire grows in size and intensity to the point where underground fire- fighting crews must wear self-contained breathing apparatus owing to mine air contamination. The Bureau of Mines has developed and in-mine tested a mineworthy fire detection system capable of sensing the earliest traces of spontaneous combustion, thus enabling mine personnel to initiate fire control operations before hazardous atmospheres are created. This paper discusses system design within the context of the harsh mine environment, and describes laboratory and in-mine performance tests of prototype equipment.

Jan 1, 1985

By J. Dufour

Although the recovery of nitric and hydrofluoric acids from stainless steel pickle liquors has been solved by several methods, such as solvent extraction, acid retardation, evaporation or pyrohydrolysis, metals (mainly iron, chromium and nickel) are usually obtained as a waste or by-product that has to be disposed. Alternatively, the treatment requires a high liquor flow to be economical, as is the case for pyrohydrolysis. A new process has been developed for metals recovery, that produces metal oxides with a low fluoride content. This new technique is based on a selective precipitation mechanism, which produces nickel hydroxide with a purity of 90%, separate from a mixture of iron and chromium oxides and hydroxides suitable for recycling. The reaction mechanism is based on the precipitation of fluoride compounds of iron and chromium, K2FeF5 and CrF3. For this purpose, free fluoride must be added as potassium fluoride. Also, solid fluoride compounds are hydrolysed, releasing free fluoride. A part of the fluoride is recycled to the selective precipitation operation and the remainder is fed to the acid recovery stage. Nickel does not react in this operation; it remains in solution giving a high separation yield.

Jan 1, 2006

By Y. Tanaka, H. Miki, Y. Aoki, H. Okamoto, G. P. W. Suyantar, T. Hirajima

Due to environmental limitations and the scarcity of freshwater, flotation using seawater or desalinated seawater as process water becomes more common for mining operations. On the other hand, seawater has been reported to affect the flotation behavior of sulfide minerals. Few reports are available on influence of pyrite depression, recycled seawater and lime consumption on flotation by using seawater. In this study, the flotation tests were performed using ore sample to investigate the effect of pH with seawater and process water used in plant on the flotation behavior in a laboratory-scale flotation cell and a pilot plant-scale. The results of laboratory scale flotation indicated that copper and molybdenum flotation kinetics decreased with increasing pH. Furthermore, the iron (mainly pyrite) recovery decreased with increasing pH. The pilot plant-scale flotation test showed that water with a higher concentration of magnesium and calcium (plant processes water) consumed a higher amount of lime. Because of low lime consumption and high copper and molybdenum recovery and grade, pH 8 is suitable compared with pH 8.5 for flotation. Keywords: seawater, process water, copper-molybdenum rougher flotation, pH, pilot test

Jan 1, 2020

By G. H. Keith

A vanadium-base alloy consisting of the following elements in weight-percent--molybdenum, 20; titanium, 10; carbon, 0.1; silicon, 0.5; and yttrium, 0.5--had exceptionally high strength at temperatures up to 1,200° C. This alloy was capable of fabrication to sheet of ~ 1 mm thickness by a combination of hot swaging and hot and warm rolling. In the warm-rolled condition at ambient temperature, its ultimate tensile strength was 1,205 MN/m2. The strength at 1,200° C was 150 MN/m2. Within the temperature range of 25° to 1,200° C, the ductility of the alloy as measured by elongation increased from 4 to >90 percent. Strengthening was achieved by both solid-solution and dispersed-phase mechanisms. Alloys of 20 percent molybdenum and 10 percent titanium were stronger than the other molybdenum-titanium alloy compositions tested. Strength was increased 15 percent in the temperature range of 25° to 800° C, with no accompanying loss in ductility, by the addition of 0.5 percent silicon. Workability was improved by additions of 0.25 and 0.5 percent yttrium.

Jan 1, 1970

By Ruirui Wei, Mingrui Yang, Xuewei Lv

Copper slag is a by-product obtained during smelting of copper from copper ores. In China, for one ton of metal production about 2.2 tons of copper slag was generated, and approximately 15 million tons slag is produced in 2013. Dumping and disposal of such huge quantities of slag will cause environmental and space problems. Most importantly, copper slag cannot be made full use of to maximize its value. In this study, copper slag was used to take the place of scrap iron and part of silica in traditional process and to produce FeSi alloy as the main material. Utilizing silica and copper slag as the raw materials and coke as the reducing agent, FeSi45 was produced in the induction furnace. In addition, the effect of different n(C)/n(O) on FeSi45 has been investigated.Increasing n(C)/n(O) is beneficial to form the stable phase of FeSi. Meanwhile, n(C)/n(O) greatly affects the reduction and recovery of silicon than iron. When n(C)/n(O) equals 1.10, the recovery of silicon and iron is about 77 and 95%, respectively.

Mar 1, 2017

By Adriana A. S. Felix, Julio C. Afonso, Luiz C. Bertolino, Bruna L. Novo, Fernanda A. N. G. Silva, Karla M. A. Simões

Palygorskite (Mg,Al)5Si8O20(OH)2(OH2)4.4H2O, is a lamellar mineral with a fibrous morphology. The micropores and canals in the structure give a high specific surface and sorption capacity of various kinds of species. Guadalupe’s palygorskite (Piauí/Brazil) run of mine (ROM) was prepared (PA) and characterized by XRD and XRF. PA is composed by palygorskite, kaolinite, quartz and goethite and has 15.8, 58.0, 4.2 and 7.6% of SiO2, Al2O3, MgO and Fe2O3, respectively. Wet magnetic separation tests were conducted with PA obtaining the magnetic and non-magnetic fractions (PAM and PANM, respectively). PANM was characterized by XRD and XRF and the results of the XRF indicated that the iron content in the PA decreased 8.0% in the non-magnetic product. A new wet sieving was conducted with PANM to obtain a purer fraction (−20 μm) (PANMP) which was characterized by XRD, XRF, CEC, Zeta potential, SEM, TG/DTG. The result showed that this mineral could be used as adsorbent of heavy metals.

Mar 1, 2017

By A. K. Smith

Overexposure to noise remains a widespread, serious health hazard in the U.S. mining industry. Most other categories of illnesses and injuries associated with mining have improved, with the exception of hearing loss. U.S. Mine Safety and Health Administration (MSHA) coal noise data from 2000-2004 show that the continuous mining machine (CMM) is first among all equipment, accounting for 35% of noise overexposures. Joy Mining Machinery, in collaboration with the National Institute for Occupational Safety and Health (NIOSH), is conducting research to reduce noise generated by continuous mining machines. This paper describes a "JOY Designed for Noise Reduction" (JOY DNR; patent pending) tail section as a noise control for reducing the noise overexposures of CMM operators. Underground testing shows a 45% to 65% noise exposure reduction for the operator when comparing the JOY DNR tail section results to those for a standard machine. Utilizing this newly developed noise control, along with previously proven controls, will provide CMM operators an opportunity to be within the MSHA permissible exposure limit (MSHA-PEL). Mining Engineering, 2011, Vol. 63, No. 7, pp. 83-85. Official publication of the Society for Mining, Metallurgy and Exploration, Inc.

Jan 1, 2011

By Andrzej Warczok

Intensive smelting of copper concentrate in Teniente Converter (CT) leads to the production of high grade matte and highly oxidized slag. Smelting slag is processed in Teniente vascular slag cleaning furnace. The slag composition and forms of copper affect the slag cleaning process and final copper content. Converting of high grade matte in Pierce-Smith converter faces some difficulties in proper slagging of iron oxides. Overblowing in copper making stage allows for slag liquidation but leads to high content of copper oxide in converter slag. Converter slag recycling into CT results in the increase of the participation of oxidic copper. Separate treatment of converter slag and its impact on the forms of copper in CT slag has been analyzed. Thermodynamic properties of a system and kinetic limitations pointed out the negative effect of converter slag recycling on the forms of copper and copper recovery in slag cleaning stage. Experimental results of slag cleaning tests in a crucible scale as well as microscopic examination of laboratory and industrial slag samples supported the above analysis and permitted to formulate recommendations of separate processing of converter slag. Keywords: copper, losses, slag, recycling

Jan 1, 2001

By William S. Roberts

As part of the Bureau of Mines critical and strategic minerals program in Alaska, 34 high-purity chromian spinel samples were analyzed for trace and major element geochemistry and mineralogy. The samples were analyzed by X-ray diffraction, X-ray fluorescence, and chemical techniques. Systematic differences in chemistry are evident when samples collected from the Chugach Mountains and their related extension are compared with chromian spinel samples collected from interior Alaska. Compared with the Chugach samples, the interior Alaska samples have higher average amounts of A1203, Fe203, Ti02, and NiO, have lower average amounts of FeO and Cr203, and exhibit greater dispersion in values. Considerable mineralogical variability of chromian spinel exists between and within individual Alaskan chromite-bearing ultramafic complexes. Of 34 samples analyzed, 25 samples are magnesiochromite, 5 are chromite, 3 are spinel, and 1 is hercynite. As a group the interior Alaska samples have a smaller average unit cell dimension than the Chugach group of samples. The chemical and mineralogical differences between the two groups of samples can be attributed to different genetic histories and may have implications for locating chromian spinel deposits amenable to standard beneficiating techniques.

Jan 1, 1985

By E. V. Murphree

CREATION of atomic energy, aside from its influence on war or peace, has posed these basic questions for the world: How soon can energy from atoms be harnessed to do man's daily work? How much of this power will there be, to what degree will it supplant present fuels, and what does it imply for the future of civilization? Answers to these questions may be found in part in analysis of just what atomic energy is and how far its development has come. The answers are encouraging. One of the first questions encountered in considering the application of atomic reactions is whether such reactions can be controlled. Fortunately, this has been adequately demonstrated by the operation of the Government plutonium plants at Hanford, Wash. Here nuclear reactions are carried out on a large scale involving liberation of about a billion B.t.u. per hour. This hourly heat liberation is equivalent to that obtained from about 7100 gallons of fuel oil. It has been possible to operate these plants day in and day out with the reaction controlled at the intensity desired. There should therefore be no question that, under proper conditions, reactions involving nuclear fission can be controlled.

Jan 1, 1946

By Jon G. Baird

The suggestion of the use of measurements of trace amounts of mercury as a guide to the location of sulphide ore deposits was first made by the Russian, A. A. Saukov (1), in 1.946. Since Saukov's original work, many others have studied the abundance of mercury in nature, the association of mercury with sulphide ores and methods by which very minute quantities of mercury can be measured in air, soil, rocks, water and plants. The most abundant of the mercury bearing minerals is cinnabar (HgS). Native mercury is also found and sulpha-salts like tetrahedrite are known to have important mercury contents. Other sulphides of base metal deposits contain mercury in amounts ranging from parts per million to as much as one or two percent. (2) The mercury content of sulphide-free rocks is usually less than a few hundred parts per billion (1 ppb - 10-9), Soils usually contain less than 100 ppb and water less than 1 ppb of mercury. Normal atmospheric air contains about 1 nanogram (10-9 grams) of Hg per cubic metre although higher concentrations can be observed near mercury occurrences, sulphide deposits and volcanic exhalations.

Jan 1, 1973

By B Tutmez

Determination of stress-strain behaviour of rocks plays a crucial role in understanding the response of rocks during loading. However, it is a tedious, expensive and a time-consuming process to obtain such characteristics both in the laboratory and in situ. On the other hand, non-destructive testing methods such as ultrasonic velocities can produce a reliable and fast solution to indentify state of strain and stress in rocks. The present paper aims to provide insight into the relations amongst ultrasonic wave velocities, amplitudes and deformability properties of porous siltstone under compressive loading. For this purpose, pulse (vP) and shear wave velocities (vS) along with amplitudes (AP - AS), and applied loads with resultant strain were measured simultaneously so that response of siltstone to compression can be evaluated. In addition, initial vP and vS were recorded at the beginning of each test to calculate dynamic elastic properties of the specimens. This provided a comparison between static and dynamic elasticity properties of siltstone. Crack damage associated with the onset of dilation was also investigated. The results showed that there is a non-linear logarithmic relation between velocities and stress-strain level for siltstones.

Sep 26, 2011

By Liming Yuan, Wei Tang, RICHARD THOMAS, JOHN SOLES, DAVOOD BAHRAMI

Mine equipment fires remain as one of the most concerning safety issues in the mining industry, and most equipment fires were caused by hot surface ignitions. Detailed experimental investigations were conducted at the National Institute for Occupational Safety and Health’s (NIOSH) Pittsburgh Mining Research Division on hot surface ignition of liquid fuels under ventilation in a mining environment. Three types of metal surface materials (stainless steel, cast iron and carbon steel), three types of liquids (diesel fuel, hydraulic fluid and engine oil) and four air ventilation speeds (0, 0.5, 1.5 and 3 m/s) were used to study the hot surface ignition probability under these conditions. Visual observation and thermocouples attached on the metal surface were used to indicate the hot surface ignition from the measured temperatures. Results show that the type of metal has a noticeable effect on the hot surface ignition, while ventilation speed has a mixed influence on ignition. Different types of liquid fuels also show different ranges of ignition temperatures. Results from this work can be used to help understand equipment mine fires and develop mitigation strategies.

Oct 1, 2022

By C. H. Mathewson

UNFORTUNATE evasions of metals specifications recently brought to public attention through news items and editorials have caused executives of at least two great corporations to set up defensive procedures and to re¬affirm the patriotic purpose and conscientious effort of their plants in this battle of production. Whatever the exact conditions affecting these cases, in which the public interest has been safe-guarded by vigorous action, my reaction to such offenses in general is a feeling that they arise from the pressure and limitations that afflict our overextended war effort and that inevitably there will be more of them, doubtless more and more expertly conceived and less and less subject to detection as simple faked, or substituted analyses or tests. To the ladies, who doubtless are already beginning to ac¬quire a sense of painful resignation to a dry technical talk, may I say that the cookbook is full of specifications which customarily are varied within rather wide limits but it is generally recognized that the proof of the pudding is in the eating without regard to its exact composition or some scientific evaluation of its texture.

Jan 1, 1943

By W.A. van der Westhuizen

Mineral resource management has become a well used phrase in the mining and minerals industry. Mineral resource managers are being appointed in many mining and mining-related organisations. Every mineral resource manager has his/her own ideas regarding what MRM means. There seems to be a tendency to define MRM close to home; geology would apply MRM principles to their environment and so will metallurgy, planning, mining, survey and every discipline and participant in the mining value chain. What do we do in the MRM environment and what do we aim to achieve? Surely we must have goals: what are they? Is value tracking MRM? What about best practices? Let us start at the beginning: what do we want to achieve in any mining operation? The minerals industry would like to make money, now and in the future. This calls for serious management inputs. The most important aspect is a holistic management approach regarding the total mining value chain. Process optimisation follows with application of Mineral Resource Throughput Management (MRTM) and Process Flow Management principles. Once flow processes have been established the necessary condition driven standards and measurements will be installed to ensure continuity in applicable processes.

Jan 1, 2012

By L. Fernandes

A factorial study was performed to investigate the relative effects of temperature, copper concentration and meso-2,3-dimercaptosuccinic acid (DMSA) concentration on the performance of thiosulfate leaching of gold. A total of 24 leaching experiments were performed representing eight unique combinations of high-low levels of the three factors performed in triplicate. All investigations were performed in an electrochemical cell with an electrolyte composed of 0.1 M sodium thiosulfate with a combination of copper (either 0 mM or 1 mM) and DMSA (either 0???or 1µM). All leaching investigations were conducted under open circuit while the electrolyte, which was open to the atmosphere and mechanically stirred, was maintained at either 25°C or 50°C. After 1.5h of leaching the amount of gold in solution was quantified using ICP-MS analysis from an aliquot of the electrolyte. Results indicate that DMSA addition improved gold leaching performance, most notably at 50°C and with addition of copper. Under this unique condition, the quantity of gold in solution was reproducibly and significantly above the average response of all other factors studied.

Jan 1, 2014

By Richard E. Otoo, Evan J. Owen, Virginia T. McLemore

Disruption in critical minerals supply chains has resulted in the evaluation of various types of mineral deposits for critical minerals potential. Much of the study on critical minerals focuses on occurrence and characterization, but little research has addressed what concentrations of critical minerals in a mineral deposit are required to make an exploration target into an operating mine. Understanding the cut-off grades of ore deposits being actively mined is one criterion to determine if concentrations in an exploration target are high enough. Cut-off grade is defined as the minimum amount of mineral contained in a ton of ore that is sent to the processing plant. Among many factors, cut-off grade depends upon the size and type of the deposit and mining operation, the processing technique, and market prices. This research does not aim to define cut-offs for determining if a mineral deposit is economic. Rather, it defines estimates of concentrations of critical minerals that could be considered good enough for further exploration. For example, ~2% total rare earth oxide (TREO) is the cut-off grade for Mt. Pass carbonatite, but 500 ppm TREO could be an exploration target for coals.

Feb 1, 2025

By X. G. Liu

Bentonite is an excellent sealant mineral material because of its desirable swelling and self-healing characteristics, low permeability, sorptive qualities, and longevity in nature. A new type of water-swelling building sealant made from bentonite was studied in this paper. The building sealant is prepared by Na-base bentonite, vaseline and paraffin wax under different mass fraction of bentonite (which is 60%,65%,70% respectively). Under unrestricted state, some properties of samples were investigated. The volume expansion ratio at 24 h is 211%, 222%, 256% , and permeability coefficient is 2.86×10-8 cm/s, 4.15×10-8 cm/s and 4.78×10-8 cm/s respectively; low temperature flexibility of the sample (bentonite quality is 65%, 70% respectively) is good, and it does not flow heated for 2 h under 80?. The results of XRD and SEM indicate that bentonite is coated preferably by vaseline, and the spacing of layers of bentonite do not changed. The sample can keep full water swelling ability, and has good molding process. The test results prove that the properties of samples may reach the standard of building sealant.

Jan 1, 2014

By Oliver Bowles

Wire saws have been used for many years in European travertine, marble, and slate quarries. This method of sawing found very limited use in America until 1927 when it was accepted as standard equipment in elate quarries in Pennsylvania where it has been remarkably successful. Details of its operation in slate have been published in a recent bureau report.3 The very limited extent to which the wire saw has been employed in limestone and marble quarries in the United States and the seeming lack of interest even in experimental work to determine its advantages are difficult to explain in vied of its wide use in cutting similar rocks in Europe and its unquestionable advantages in sewing slate in America. In order to encourage improvement in quarry practice the United States Bureau of Mines has endeavored to obtain information as to the extent to which wire saws are used in Europe together with data on the rate and cost of sawing. The information at hand is by no means complete either in territory covered or in details of operation; it nevertheless brings out certain significant features that may be of interest and advantage to quarrymen in the United States.

Jan 1, 1931