Search Documents

By D. E. Fogelson

In a factorial experiment, blasting caps were detonated in three sizes of shotholes in mortar with three types of stemming--dry sand, wet sand, and hydrostone. Free-surface displacement pulses were recorded with a capacitive-displacement gage at a distance of 15 inches. The effects of decoupling and the type of stemming on the amplitude and the duration of the displacement pulse were determined. Both the amplitude and the duration of the displacement pulse were significantly decreased by increasing the decoupling, but they were little affected by the type of stemming.

Jan 1, 1965

By Brandon Fryman, Josh Hoffman, Rhys Baker

A post-detonation debris collection project was led in conjunction with a large ammonium nitrate (AN) railcar detonation conducted by the Department of Homeland Security-Transportation Security Administration, Department of Defense-Combating Terrorism Technical Support Office, Sandia National Laboratories, and the U.S. Army Dugway Proving Grounds. This important work will aid in underpinning algorithms used in a Quantitative Risk Assessment (QRA) tool.

Feb 1, 2020

By Emmanuel N. Zevgolis

In the present work, a reduction roasting experimental study of Greek nickeliferous laterite samples with a gaseous reducing mixture ? CO:N2- is presented. The effect of parameters such as temperature, ore grain size, and composition of the reducing mixture were examined. It is deduced that the reducibility of intermediate type laterite sample, where iron appears mainly in the form of goethite (a-FeOOH), is considerably higher than that of limonitic type laterite samples, where hematite (a-Fe2O3) is the predominant iron mineral phase. The degree of reduction of the limonitic type laterite samples does not exceed 50%, while it reaches 95% in the case of the intermediate-type laterite sample under the same experimental conditions. Increasing the temperature in the range 750-900°C does not considerably favor the reduction of the limonitic type laterites, whereas decrease of ore grain size of the limonitic-type ore samples and more intense reducing conditions increase the reduction. The considerably higher specific surface area values of the intermediate laterite samples, diminishes the effect of the ore grain size and this can be regarded as the critical parameter leading to the higher reducibility of this ore.

Jan 1, 2009

By T. X. Hu

Pyrite ore is one of the main raw materials in the production of sulfuric acid. For a long time, the raw material containing the pyrite, which is used to produce sulfuric acid, generally contains S only 32%~45%. A plenty of residue from the sulfuric acid production contains 40%~50% Fe and 1%~2% S. Some of the residue also contains Cu, Pb, Zn and other harmful elements like As, thus it pollutes environment seriously and is solid waste. The research on comprehensive utilization of the residue has been made by many scholars. Through the study, the residue can only be used to pro-duce iron concentrate and the iron oxide red pigment. But because of the complex techniques, the low recovery, the low grade of iron concentrate , high sulfur in iron concentrate, causing second waste residue and the environmental pollution, the residue is mainly used as an accessory material in the production of cement, and is of a low value. Therefore, the iron resource in pyrite has not been used efficiently until now. In the paper, the flotation condition test, the flotation open circuit test and the flotation closed circuit test to produce high-purity pyrite concentrate with the low-grade pyrite ore in oceanic ore deposit have been carried on. Flotation reagent scheme of sulfuric acid used as activator and butyl xanthate as collector is determined. After four times depth cleaning, high-purity pyrite concentrate containing 52.82% S, 44.29% Fe, and only 2.89% impurities has been obtained. The S recovery is 99.13%, and the Fe recovery is 96.00% in the high-purity pyrite concentrate. The oxidizing roasting depth desulfurization experiment of the high-purity pyrite concentrate has been conducted. The results show that the Fe grade in the residue obtained is 68.58%, the content of S is 0.25%, the content of P is 0.0084%, the content of As is 0.0065%. The residue is a kind of high-quality iron-smelting raw material. Based on the above experiments, the industrial experiments on producing high-purity pyrite concentrate with the low-grade pyrite ore, and producing sulfuric acid and iron concentrate with high-purity pyrite concentrate have been done. The results indicate that the high-purity pyrite concentrate with the S grade of 51.24%, the Fe grade of 44.15% has been obtained. The iron concentrate obtained with 65.73% Fe and 0.23% S is a sort of high-quality iron-smelting raw material applied to the production of steel and iron smelting. Through the experimental study, the sulfur and iron resources in the pyrite ore have been recovered and utilized efficiently.

Jan 1, 2014

By C. Bateman, F. Calizaya

"This study presents the results of three laboratory experiments on pressure balancing carried out at the University of Utah’s coal mine ventilation model. The model includes simulations of two working areas, one longwall mine gob, and a set of stoppings and seals. It also includes a pressure chamber between the longwall face and the gob. The model is ventilated by one main fan and one bleeder fan. A carbon dioxide injection system, equipped with flow control valves operated by a microprocessor, is used to pressurize the chamber and to maintain the pressure in the chamber slightly higher than that of the gob. During each experiment, fan pressures and stopping resistances were changed, the carbon dioxide injection rate was regulated, and the differential pressures across the stoppings were monitored so that the chamber pressure is always kept slightly higher than that the gob pressure. Result of these experiments are reported in this paper. INTRODUCTION Spontaneous combustion (Sponcom) is a safety hazard in underground coal mines. The history of coal mining in the US is replete with mine fires and explosions. Sponcpm accounts for approximately 17% of the total number of fires recorded in the U.S. since 1990. In the U.S., by law, worked out areas in coal mines must be either ventilated by a bleeder system or isolated by explosion proof seals. Experience has shown that seals are not airtight structures and that they allow some leakage of air into or out of the gob. In fact, seals “breathe in and breathe out” with changes in barometric pressure (Francart 1997, and Chalmers 2010). These changes in pressure affect not only the methane emission rate but also the ingress of oxygen to the gob, the lower the pressure behind seals is, the higher the ingress of oxygen. In mines ventilated by a U-tube exhaust system, the gob is often kept under negative pressure. Under these circumstances, an increase in barometric pressure may cause an influx of fresh air into the gob. This quantity may be sufficient to start self-heating of the coal, which can lead to spontaneous combustion. Depending on the coal characteristics and the ventilation conditions, self-heating of coal can start at temperatures as low as 35 ºC. If the heat is not removed it will increase the coal temperature leading to ignition and fire. The risk of Sponcom fires can be reduced by isolating the mine gob using rated seals, and implementing a suitable ventilation system. However, isolation seals are not airtight structures, thus some leakage of air is expected unless the pressure in the gob is neutralized. The alternative is to use a pressure balancing system. This requires a thorough knowledge of the ventilation system, the seal/stopping construction techniques, the airflow behavior in the gob area, and the gas build-up behind the seal line."

Jan 1, 2016

By Williams, J. A.

THE Alaska Juneau mine has been developed through an adit driven at the elevation of the top of the mill and all mining is done above this main haulage level. As a result of wholesa1e"mining operations about 11,000 tons rock containing one dollar' per ton in gold is, hauled to the. concentrator during every 24 hr. Due to the method of mining, whereby a system of oreways delivers-the.ore direct from the stope to the bottom level of the mine, no tramming of ore is done on any of the upper levels. However, ;in doing exploratory drifting and crosscutting on the upper levels, the broken material is trammed by hand in 1-ton 18-in. gage cars to a nearby raise connecting with one of the several oreways. This constitutes the only tramming operation except that on the main level.

Jan 1, 1931

By O. M. S. Rodrigues

The kaolinite presence in bauxite ores increases caustic soda consumption during the digestion step in the Bayer process. Depending on the kaolinite content, the utilization of the ore in the Bayer process may be unfeasible. This investigation addressed the variables involved in kaolinite flotation through microflotation experiments in a Hallimond tube and zeta potential determinations. The tests were performed with a pure sample of kaolinite (96%). Five collectors were tested: Duomeen T (DT), cetyl pyridinium chloride (CPC), cetyltrimethylammonium bromide (CTAB), dodecylamine (DDA) and Flotigam EDA (EDA). Four of them performed well as collectors, at a concentration of 1x10-4 mol/L: CPC, CTAB, DDA and EDA. The kaolinite isoelectric point (IEP) was determined at pH = 4.6. The IEP was shifted towards higher pH values in the collectors? presence, indicating specific adsorption onto the mineral surface.

Jan 1, 2011

By Ian MacGregor

As I drove in from the airport on Sunday somebody said 'On the right you will see Duntroon, which is the military training school of Australia.' So I asked the driver, where did they get that name? 'Oh,' he said, 'from some people who built a house there. That was it's name- Duntroon.' It strikes a note with me because, that's the name of a 12th century castle on the west coast of Scotland where I spend what leisure hours I have and, therefore, it establishes the long connection between Australia and my native land. There is also a story I should tell you about the oil industry and its upsurge in Scotland recently which has resulted in great prosperity. And in Edinburgh, the walls of the banks are bulging-because of the incursion of foreign exchange and other resources. Charlotte Square, as some of you know, is the centre of the Scottish financial world and at one of the corners of Charlotte Square, where ho streets intersect, there are three stores-three emporia on the ground floor. Two of them at opposite corners are banks: The Royal Bank of Scotland, and not to be beaten by that, The Bank of Scotland. But the third building is occupied, or was occupied, by a furniture store over many years-very high-grade, high quality furniture that the elite of the Edinburgh society always supported. And suddenly, the store was cleared out and in came a bunch of carpenters and other people busily engaged in rebuilding the store, and finally the new tenants arrived on the scene.

Jan 1, 1978

By Z. T. Yuan, S. L. Qi, Q. Y. Meng, G. X. Zou, L. X. Li, J. W. Lu

"The selective separation of pentlandite from serpentine was investigated using the magnetic coating-magnetic separation by conditioning slurry pH value, stirring speed, magnetic field intensity and controlling dosages of sodium hexametaphosphate (SHMP) and sodium oleate (SO). The optimal conditions were obtained as follows: the natural pH of 6.8-7.2, stirring speed of 2300 rpm, magnetic field intensity of 200 kA m-1, SHMP of 60 mg L-1, and SO of 400 mg L-1. Results showed that the Ni grade was 21.4% with the Ni recovery of 81.4% and MgO content of 3.8%. FTIR indicated that coagulant of SO preferentially adsorbed onto pentlandite and magnetite particles while hardly adsorbing onto serpentine particles when dispersant of SHMP was used. Thus, the selective magnetic coating of magnetite on pentlandite surfaces could be formed due to the formation of hydrophobic surfaces on pentlandite and magnetite particles. Calculations of DLVO (Derjaguin-Landau-Verwey-Overbeek) confirmed that interactions between magnetite and pentlandite particles were much stronger than that between magnetite and serpentine due to the existence of hydrophobic interactions with the addition of SO. Consequently, the pentlandite was successfully separated from serpentine. Therefore, this study exhibits the potential to separate pentlandite from serpentine minerals for practical applications and thus deserves further study.INTRODUCTION It has been well known that the separation of pentlandite from serpentine is a worldwide challenging issue in the processing of sulphide nickel-copper ores. Because the serpentine mainly causes the high pulp viscosity and slime coating on the pentlandite, which interferes with the flotation process of pentlandite (Cao et al., 2016; Feng et al., 2012). The fibrous mineral of serpentine preferentially attaches to the air bubble, forming bubble-macrofibers aggregates, which are easily floated into the nickel concentrates, resulting in the decline of Ni grade (Alvarez-Silva et al., 2016; Kusuma et al., 2014). In addition, the serpentine adheres to the pentlandite as hetero-aggregation or slime coating via the electrical interaction between a positively charged serpentine and a negatively charged pentlandite, which decreases the hydrophobicity of pentlandite and reduces the collector adsorption (Feng et al., 2013). In other words, the presence of serpentine or the occurrence of aggregates (including slime coating and bubble-macrofibers aggregates) seriously affects the flotation process and deteriorates the flotation of pentlandite. Therefore, we propose magnetic separation to recover pentlandite from serpentine with the magnetic coating technology, which is different from forth flotation."

Jan 1, 2018

By J. R. Maxwell

The development, commercial installation, and operating performance of large capacity Maxwell Flotation Cells. Volumes ranging from 300 cubic feet to 2,000 cubic feet per flotation mechanism.

Jan 1, 1971

By Lucia Kuizon

The Antimony RARE II area is underlain principally by Mesozoic igneous rocks associated with the Sierra Nevada batholith. The San Andreas fault zone is near the southern boundary. Metallic mineral deposits are associated with the fault zone. These deposits were formed from magmatic solutions, and tend to be along shears and fractures within the country rock. Marble and dolomitic marble deposits occur in Paleozoic roof pendants or inclusions in the Mesozoic intrusive rocks in the area (Troxel and Morton, 1962, p. 52).

Jan 1, 1982

By AIME AIME

HONORARY COMMITTEE. HON. C. D. WALCOTT (Chairman.), Director U. S. Geological Surrey. HON. FREDERICK I. ALLEN, Commissioner of Patents. DR. FRANK BAKER, Superintendent National Zoological Park. MR. CHARLES A. BELL, President American Security and Trust Co. MAJOR JOHN BIDDLE, Engineer Commissioner of District of Columbia. ADMIRAL C. M. CHESTER, Superintendent U.S. Naval Observatory. GENERAL WILLIAM CROZIER, Chief of Ordnance, U. S. A. ADMIRAL GEORGE DEWEY, Admiral of the Navy. COLONEL CLARENCE R. EDWARDS, Chief Bureau. of Insular Affairs. MR. WILLIAM C. FOX, Director Bureau of American Republics. MR. CHARLES C. GLOVER, President The Riggs National Bank. GENERAL A. W. GREELY, Chief Signal Officer, U. S. A. MR. BERNARD R. GREEN, Superintendent Library Building. GEN. G. H. HARRIES, Vice-President Washington Electric Railway Co. HON. E. A. HITCHCOCK, Secretary of the Interior. COMMANDER H. M. HODGES, Chief Hydrographer, U. S. N. PROF. W. H. HOLMES, Chief Bureau of American. Ethnology. PROF. S. P. LANGLEY, Secretary Smithsonian Institution. GENERAL ALEXANDER MACKENZIE, Chief of Engineers, U. S. A. ADMIRAL N. E. MASON, Chief Bureau of Ordnance, U. S. HON. WM. M. MEREDITH, Director Bureau of Engraving and Printing. HON. V. H. METCALF, Secretary Department of Commerce and Labor. HON. WILLIS L. MOORE, Chief -U. S. Weather Bureau. HON. PAUL MORTON, Secretary of the Navy. MR. F. H. NEWELL, Chief Reclamation Service, U. S. Geological Survey. HON. S. N. D. NORTH, Director Census Office. CAPT. E. C. PENDLETON, Superintendent Naval Gun Factory. MR. GIFFORD PINCHOT, Chief Forester, Department of Agriculture. MR. HERBERT PUTNAM, Librarian of Congress. ADMIRAL CHAS. W. RAE, Chief Bureau of Steam Engineering, U. S. A: MR. RICHARD RATHBUN, Assistant Secretary Smithsonian. Institution. HON. W. T. RICHARDS, Commissioner General Land Office.

Jul 1, 1905

By S. M. Shelton, F. D. DeVaney, M. M. Fine

Ferrograde manganese ore or its equivalent is essential to the manufacture of every ton of steel produced ; although it is well -known that there are large deposits of low - grade ore in the United States , the production of substantial amounts of ferrograde material from domestic sources presents a problem that becomes more and more critical as the stockpiled ore is depleted through inability to obtain adequate supplies from foreign sources . Consequently, a program of laboratory and pilot - plant investigations designed to solve the problem of obtaining a domestic supply of manganese has been undertaken by the Metallurgical Division, Bureau of Mines . This paper is one of a new series that will include reports of results obtained in the various investigations conducted under the manganese program . The scope of the program and the organization that was set up to direct and supervise the work were discussed in the foreword of the first paper of this series , Report of Investigations 3606 , Manganese Investigations 1. Concentration of Manganese Ores from the Drum Mountain District, Utah, by S. R. Zimmerley, J. D. Vincent , and C. H. Schack . Other reports will be published as the work progresses .

Feb 1, 1942

By L. L. Oden

The purpose of this research was to develop a method to remove copper and tin from the magnetic fraction of incinerated municipal refuse, as recovered by the Bureau of Mines pilot plant in College Park, Md. Copper, present in the scrap in a metallic form bonded to ferrous objects, was amenable to leaching in cupric ammonium carbonate solution. Copper levels in small 5-to 10-lb lots of treated scrap were reduced from the initial level, 0.5 to 0.6 pct, to 0.1 to 0.2 pct. Larger lots of scrap (100 lb) were treated less effectively because of poor contact of solution and scrap. Oxidation in the air or in aerated aqueous solution was applied to liberate tin from the dilute solid solution present on the surface of incinerated tinplate. Shredding of air-oxidized scrap or caustic leaching of scrap oxidized in solution reduced tin levels from the initial 0.25-pct level to about 0.1 pct.

Jan 1, 1973

By B. E. Davis

A fundamental study of the mechanisms involved in the conditioning of coarse Florida phosphate has led to some interesting discoveries. Studies by the Bureau of Mines have shown that conditioning time and mixing intensity greatly affect the grades and recoveries of the phosphate minerals and quartz in the rougher concentrate. In particular, as the conditioning time or mixing intensity increased, the phosphate recovery remained constant while the amount of quartz floated decreased. This phenomenon is contrary to conventional wisdom and could lead to a more efficient coarse flotation circuit.

Jan 1, 1993

By A. J. Makoka, B. C. Qi

Reliable monitoring of corrosion is vitally important in the combat against corrosion and over the last two decades the interpretation of electrochemical noise has received considerable attention as a means to discriminate between different types of corrosion. To this end, many different analytical methods have been proposed, such as power spectral density analysis and analysis via various other stochastic criteria. However, although many corrosion systems are nonlinear and therefore not readily interpretable by the abovementioned analytical approaches, few studies in the analysis of electrochemical noise to date have exploited advances made in the analysis of nonlinear systems. In this paper, the use of phase space methods to analyze and detect change in corrosion systems via electrochemical noise is considered. In particular, the electrochemical noise data are used to reconstruct trajectories in the so-called phase space of the system and changes in the topology of these trajectories or attractors as represented by correlation dimension curves are consequently interpreted as an indication of change in the dynamics of the system.

Jan 1, 2005

By B. K. Saikia

A preliminary attempt has been made to study the particle size distribution (PSD) of minerals in one of the industrially important pulverized Indian coal sample using computer-controlled scanning electron microscopy (CCSEM). The results show that clay minerals, quartz, pyrite, and pyrrhotite form the bulk of the mineral matter. Minor minerals, such as calcite, dolomite, ankerite, barite, oxidized pyrrhotite, and gypsum are also observed in the coal sample. The PSD of the included minerals is generally observed to be finer than that of the excluded ones in the coal. Thus, the coal rich in included minerals has more small mineral particles, which may affect its reactivity. The proportion of included to excluded is found to be higher in major cases. Si is found to be mostly occurred as quartz and clay minerals, while Al mostly occurs as silicate minerals. Fe is primarily present as iron sulfides, iron oxide, and Fe-Al-silicate. S is partitioned into iron sulfides and gypsum. Most Ca occurs as carbonates and gypsum, with a minor fraction associated with clay minerals. Mg is found to be mainly present as dolomite and clay minerals, with a very minor fraction present as ankerite. The majority of alkali elements are associated with aluminosilicates. P is mostly associated with kaolinite and/or present as more complex compounds containing Al, Si, and other elements as apatite are found to be absent in the coal studied. Ti is mainly present as rutile and kaolinite. The geo-chemical association of the trace elements has also been discussed. Keywords: minerals, Assam coals, Indian coals, CCSEM study

Sep 1, 2012

By Gerald Blackmore

This paper discusses the present state and future trends within the coal industry, and then goes into the reasoning behind these planned trends. Such factors as marketing, costs, new mining techniques and machinery, and manpower and human resources are considered. Finally, the author refers to the effect that these trends will have on the coal industry of Cape Breton.

Jan 1, 1968

By J. D. Aubertin

Rock blasting is a complex engineering process that requires in-depth knowledge of operations and geomechanical conditions. Acknowledged design precepts are based on cratering behavior associated with stiff hard rock masses. Other cratering mechanisms may however arise under certain geomechanical conditions such as extremely fractured rock masses, or with soft rocks such as rock salt and potash. The burden dimension also plays an important role in the prevalent cratering mechanisms of a given blasting condition. The present article investigates the variability of cratering profiles and geometrical trends based on characteristic geomechanical differentiation and considering the influence of burden. The differences in observable mechanisms are examined through small and large-scale single hole blast (SHB) tests. SHB tests involve a series of individual shots blasted parallel or sub-parallel to an open face. The burden dimension is varied to obtain burden dependent characteristic trends. The breakout shape is represented by a crater model in the form of a power law equation capable of describing prismatic, concave and convex cratering. The formulation comprises two reference index parameters that can describe the geometrical and geomechanical conditions. SHB test campaigns conducted in rock salt, limestone, massive amphibolite, pinolite, and grout blocks are compiled in quantitative manner to demonstrate the influence of geomechanics on cratering profiles. The observed trends are corroborated through numerical modelling carried on Finite Element Model (FEM) LS Dyna to investigate the prevalence of specific cratering mechanisms. A series of SHB tests at large and small burden values are also used to showcase the influence of geometry on the prevalent cratering mechanism and the resulting crater

Jan 1, 2024

By Don Ibana

Supported by the Minerals Council of Australia (MCA) through the Minerals Tertiary Education Council (MTEC), three Australian universities–Curtin University, Murdoch University and the University of Queensland–have formed the Metallurgical Education Partnership (MEP) to jointly develop and deliver an engineering design capstone unit–Metallurgical Process and Plant Design–in their respective undergraduate programs in extractive metallurgy, in order to enhance the students’ educational experience. A unique feature of the program is the close interaction of the students in all three universities and a significant involvement of industry professionals. Now in its sixth year, it is clear that this unit is achieving its objectives

Jan 1, 2014