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By S. N. Lekakh

Phosphorous segregated at grain boundaries during solidification and heat treatment dramatically decreases low temperature toughness of precipitation hardened Fe-Mn-Al-C austenitic steel. A thermodynamic analysis was performed to evaluate the possibility of decreasing P and subsequent segregation by Ca- and Ce-additives in the melt. It was shown that the predicted probability of forming a P containing compounds depends on melt composition and treatment sequence. Experimental heats were performed and several micro- and macro-structural effects of Ca- and Ce-additives were recognized by using an automated inclusion analysis technique.

Jan 1, 2010

By D. Harrington

Probably over 95 percent of the coal production of the United States depends upon the use of explosives before it can be placed in the railroad car at the mine, and up to the present time it has been impossible to obtain Pry kind of practicable explosive that isn't dangerous unless handled carefully. In other words, no "foolproof" explosives have been found to date and inspection of the accident records of the coal mines of this country indicates that the use of explosives in coal mines has taken a sad toll of lives. ACCIDENTS PROM EXPLOSIVES IN COAL MATES Of the 2,000 to 2,500 persons killed annually in the coal mines if the United States, 100 to 125 have been killed from explosives without an explosion of gas or dust; these accidents have been due to misfires, hangfires, premature blasts, or accidental setting off of explosives through carelessness or otherwise (but chiefly through carelessness in some form). In this type of accident the flame character of the explosive is not necessarily involved, although an unexpected or premature blast is initiated much more easily with black blasting powder, which has a long flame, than with a permissible explosive, which has a flame much shorter and of briefer duration. By far the greater number of such accidents are caused by black blasting powder or dynamite rather than by permissible explosive.

Jan 1, 1936

By M. D. Balen

The U. S. Bureau of Mines has undertaken the development of mineral industry cost escalation factors to enable the estimation of mineral development and extraction costs for mineralized sites in Alaska throught the use of the Bureau's Cost Estimating System v2.0 (CES 2.0). For the purposes of this document, all calculations are based on, and reflect the economic environment in Alaska in July 1992. The greater cost of mining in Alaska as compared to the contiguous-48 States can be estimated for Alaskan mining operations through (1 ) the analysis of capital and operating costs for analogous mine and mill plants in operation in the contiguous-48 States; (2) the hypothetical relocation of mine and mill plants from their actual location(s) to Alaska by making engineering modifications to the mine and mill plant design as required by the Alaskan site characteristics; (3) calculation of the cost of the required engineering modifications and; (4) the escalation of all costs to a level representative of the economic environment in Alaska at some specific point in time.

Jan 1, 2011

By Steve Kral

In a lagging economy where profits are tight, businesses cut costs. No revelation there. The mining industry, though, has always looked for ways to reduce production costs — no matter the state of the economy or commodity prices. The fact is, when planning a new mine or the expansion of an existing one, mining companies gamble that commodity prices will be reasonably high when a project comes onstream. It takes millions of dollars and several years to bring a mine into operation. And a lot can happen economically between the time management gives the go-ahead for a new project and its completion.

Jan 1, 2002

By Z. H. Zhou

It is difficult to remove cadmium from raw indium using only electrolytic refining because their standard potentials are similar. In this paper, physical and chemical methods were used to remove Cd from raw indium. Indium metal is vacuum refined for two hours at 400°C with a vacuum pressure of 20 Pa. In this process, 99.70% of the Cd can be removed. The removal rate of Cd reaches 90% to 95% when indium is further smelted for 10 minutes in a 20% glycerin solution of KI and I2 at 180°C. When pre-indium is electrolytic refined in an In2(SO4)3-H2SO4 system, in which the indium content is 80 to 100 g/L, the pH is 2.0-3.0 and the current density is 80 to 100 A/m2, the contents of the impurities decrease and the purity of the indium product reaches 99.99%.

Jan 1, 2007

By Edwards A. B

Renison Bell is on the Emu Bay Railway, midway between Zeehan and Rosebery on the west coast of Tasmania. The tin deposits in this area have been described by G. A. WaIler (1902), L. K. Ward (1909), H. Hermani (1914), and Hartwell Conder (1918), for the Tasmanian Geological Survey. The ore-bodies occur in the slates, grits, altered lava flows and tufts of the Dundas Series, and consist of fine-grained cassiterite disseminated through massive sulphides (chiefly pyrrhotite or pyrite), or through bodies of quartz and sulphides. Some of these bodies show a N.W.-S.E. strike, parallel to the strike of the tin belt, but others strike N.E.-S;W. or E.-W.The ore-bodies are of two types: (1) steeply dipping fissure veins,' spoken of locally as "feeders," and (2) flatter-lying bodies more or less conformable with the bedding planes of the slates (bedded veins), spoken of locally as "floors."The feeders range from 5-12 ft. in width, with occasional bulges as great as 4q ft. Their lengths vary from 100 ft. to several hundred yards, and they are known to continue to Clmsiderable depths. 'They dip steeply, generally at angles of 45° to 60° to the east or south.The floors, where they occur, 'are directly connected with the feeders, and are sheet-iike bodies of sulphide ore. The composite ore-bodies thus have the shape of an inverted L, or a T, according to whether 'the floor extends out from one side or both sides of the feeder. Most of the floors extend from the hanging-wall side of the feeder. Where erosion has removed the connection, they appear as separate bodies.The feeders as a rule carry more quartz and arsenopyrite than the floors, and are richer in tin. In addition, the cassiterite tends to be coarser grained in the feeders than in the floors. The floors, on the other hand, carry a greater proportion of -sulphides, chiefly pyrrhotite, and the grade of ore and grain size of the cas,siterite tend to decrease as the floor is followed down the dip away from the feeder, so that the outer and lower extremities of the floors may be too low-grade to work economically. The average grade of the ore worked at present is 0·9,0/0 tin. The slates forming the roofs of the floors are commonly much contorted and silicified,' so that they form hard rocks in which the contortion and shattering of the original slates are well preserved. Joints extending upwards, more or less at right angles to the roof of the floor, are occasionally filled with finely crystalline quartz, similar to that in the orebodies, and are often rich in tin, so much so that the slate as a whole may average 0·4% tin.Some carbonate gangue is present in all of the ore-bodies, commonly on the footwall side, and, in places it becomes an important constituent...

Jan 1, 1943

By P Hunger, H Günter, F Heinicke

High pressure grinding rolls (HPGR) have been used for more than 20 years to grind iron ore pellet feed. Besides coarse comminution (crushing), where HPGR are installed upstream of the ball mill, there are numerous flow sheets where HPGR are used after ball milling and dewatering for re- or finish grinding.There is a clear growing interest in grinding of pellet feed with HPGR during the last few years. In addition to their known advantages of low specific energy consumption, high availability, low steel consumption and improved pelletising processes the lower environmental load (reduced or no water consumption) became a strong driving factor for the application of HPGR in pellet feed grinding.This growing demand increases the interest in better understanding of the HPGR grinding process with fine iron ore concentrates. One of the most important process parameters is the moisture content of the feed material which influences the performance of the HPGR enormously. The HPGR can react to fluctuations of the fresh feed properties to a certain degree by adjusting grinding force and roller speed. Nevertheless, there are limitations by the physics of the compression process and the capability of water absorption by the concentrate. The capability varies for different concentrates and different specific surface areas. This fact has to be considered during engineering of the beneficiation plant.The paper focuses on the influence of feed moisture content on the HPGR performance in view of throughput, increase of Blaine number and process stability on the basis of numerous pilot plant tests, modelling results and industrial experiences.CITATION:Heinicke, F, Günter, H and Hunger, P, 2017. Influence of feed moisture on high pressure grinding roll pellet feed grinding, in Proceedings Iron Ore 2017, pp 187–194 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By P. J. Hancox

Heavy mineral deposits have been known from Liberia since the1950s from both river and beach placers. The heavy mineral content of beach sands ranges between 28?62% and the suite includes ilmenite, rutile, zircon and magnetite. These occur together with kyanite, sillimanite, staurolite and garnet. The average ilmenite content is 82% with minor zircon (11%), rutile (6%) and monazite (1%). The ilmenite is, however, of poor quality with haematite intergrowths and a titanium content ranging from10?42.4% (average ±25% TiO2). The amounts of rutile and zircon, while of suitable quality, have also previously been deemed too low for economic exploitation.

Jan 1, 2000

By Paul J. Ehret

With the passage of the Surface Mining Control and Reclamation Act (SMCRA), and the implementation of state permanent programs, underground coal mining operations are for the first time subject to government regulations regarding subsidence. These regulations now and in the future will directly affect the manner in which mining companies mine their coal. Since the promulgation of the original final regulations by OSM, numerous changes in those regulations have been made and many additional changes are pending in the near future. This paper will discuss state and federal approaches to regulating underground coal mines and examine issues surrounding future subsidence regulations.

Jan 1, 1986

By Wang Hongwei, Wu Yongping, Cao Peipei, Jiao Jianqiang

Fully mechanized top caving mining of steeply inclined extra-thick seams with variable angles has complex roof rock movement, failure, caving, and filling mechanisms. Moreover, the variable-angle coal seams make rock–equipment stability control challenging. We analyzed rock deformation and failure mechanisms, overburden bearing structures, and working characteristics of supports through physical simulations, field tests, and theoretical analysis of the no. 120210 working face of Zaoquan Coal Mine. Overburden rock movement has distinct regional characteristics, with a large caving height (to the main roof layer) in the upper area, and lower caving height (to the lower main roof) in the lower area. Support loading is regional and unbalanced along the inclined direction. The critical layer of overlying strata migrates, and bearing structures formed by breaking the critical layer exhibit cross-layer generalization along the inclination. The upper region has a cantilever beam structure in the basic roof rock layer; the lower region has an inclined masonry structure with multistage ladders in the breakage basic roof rock layer. Application of a false-inclined working face layout with the tailgate ahead of the headgate and an arc arrangement (radius 28.65 m, arc length 10–20 m) in variable angle areas, and regional control of support working resistance and top-coal caving amounts, control regional failure overburden. Safe and efficient mining was achieved, with the monthly production and recovery rates reaching 344,900 t and 85.86%, respectively. Our results expand the scope of fully mechanized top caving mining and have important theoretical and technological significance.

Nov 23, 2020

By K. Bounou, K. Komnitsas

"Risk quantification may be used as a sustainable development index in the mining industry, since it encompasses both economic and social factors. In addition, it may assist in the development of a framework, which is also indirectly related to sustainable development, to prevent accidents and improve health and safety standards. However, risk quantification in the mineral sector involves diverse activities and is considered a very difficult task. Although statistical data report accident severity rates, incident rates and accident frequency rates, none of these allow for accurate risk calculations. In this paper, two risk calculation formulas, which may be used to quantify risk, as well as to identify hazardous activities in a workplace, are proposed. Numerical examples are given based on statistical data available through the MSHA database. Also a combination of a decision/fault/event tree that allows risk quantification is presented."

Jan 1, 2005

Characterizing coal mine roof rock is extremely important for hazard assessment, reinforcement, and entry design. The Coal Mine Roof Rating (CMRR) is an innovative rock mass classification that has found acceptance in the coal mining industry. A disadvantage of the original CMRR is that it cannot be determined in advance of mining, because it requires underground observations. An entirely new set of procedures have now been developed to determine the CMRR from exploratory drill core, as described in this paper. The new procedures employ Point Load Tests (PLT) to determine strength parameters that account for approximately 60% of the rating. Both diametral (parallel to bedding) and axial (perpendicular to bedding) PLT are conducted. The diametral tests allow estimates of bedding plane cohesion and rock anisotropy, both of which are critical to estimating susceptibility to horizontal stress. Traditional core logging procedures are used to determine discontinuity spacing and roughness. To ensure compatibility with the original CMRR, the new rating scales were verified by comparing drill core results with nearby underground exposures. To assist mine planners in using the new CMRR procedures, a large database of strength ratings of roof rocks was assembled through extensive point load testing and logging. Over 2000 point load tests (both axial and diametral) have been made on 30 common coal measure rock types from mines representing most U.S. coalfields. This database has been merged with the popular core rating system of J.C. Ferm into a field guide for geologists and engineers. By using the pictorial classification system of Ferm to identify the rock, typical CMRR can be compared with values calculated using the new CMRR procedures.

Jan 1, 1996

By Robert H. Lambeth

There are no identified mineral resources in the Italian Peak RARE II areas, and there are no producing or developing mines within or adjacent to the study area. Several prospects are in RARE II area M-4945, Idaho, but none were found in the area I-1945, Montana. The Viola Mine (fig. 1, no. 15) vicinity and the Heart Mountain vicinity along the west and south borders, respectively, are being prospected. There has been no recorded production from mines within the study area, but between $2.5 million and $5.0 million worth of lead, silver, and zinc were produced in the adjacent Birch Creek district - dominantly from the Viola Mine - from 1882 to 1889 (Anderson and Wagner, 1944, p. 14). The Viola and other mines in that district are possibly, on basin-margin, carbonate-hosted, lead-silver-zinc deposits stratabound within the Devonian Jefferson Formation. Previous studies have considered them to be hydrothermal, replacement orebodies. Mineral occurrences in the Heart Mountain area are possibly black-shale hosted uranium-vanadium deposits in the Mississippian-Devonian McGowan Creek Formation or perhaps the underlying Devonian Three Forks Formation. The Jefferson and McGowan Creek Formations underlie many scattered segments of the study area. The deposits and occurrence; are not sufficiently exposed to determine tonnage and grade, but sampling indicated moderate resource potential at two properties just outside the study area, the Viola Mine and the Elkhorn Group (fig. 1, no. 33). Local residents indicated there are several thousand tons of zinc-bearing resource; at the Viola line. A 23-ft (70-m) drill hole intercept near Heart Mountain et the Elkhorn Group adjacent to the stuny area contained 0.15 percent uranium oxide

Jan 1, 1983

The spatial distribution of copper grades at the Mansa Mina project is highly variable due to the presence of high grade copper/silver/arsenic breccia bodies. Copper grades within the breccia bodies tend to average about 4.5% copper while grades in the surrounding stockwork average about 1.0%. The breccia is known to occur in the vicinity of significant controlling structures, however, the outline and therefore the thickness of the bodies are far from regular. Due to the high grade of these bodies a significant proportion of the value of the project is derived from the breccia tonnages. The irregularity in the outlines/thickness translates into an uncertainty in the breccia tonnage and therefore in the value of the project. Acknowledging the economic importance of the breccia bodies and the risk associated with the breccia tonnage uncertainty, significant additional drilling has been proposed to both understand the spatial distribution of the breccias and reduce project risk. The costs associated with this additional drilling are not inconsequential; thus, a reasonable question is ‘what value is derived from this additional drilling’? To obtain an answer to this important question, a simulation approach is applied. First the deposit is simulated using the existing drilling and the uncertainty in the resource is defined. Next the proposed drilling program is simulated and the simulated data are added to the existing data. Using this expanded data set a second simulation of the deposit is created and once again the uncertainty in the resource is defined. Using this approach, the reduction in the uncertainty in the resource can be determined. To convert this reduction in uncertainty (or reduction in risk) in the stated resource into a dollar value, a method of defining the increase in the project rate of return necessary to account for risk is presented. Using the two different rates of return, the difference in project NPV and hence the value of additional drilling is determined.

Jan 1, 2003

By Hargraves A. J, Smith J. W

Experiments conducted at Tahmoor Colliery, Sydney Basin, have demonstrated the variability in chemical and isotopic composition of seam gases issuing from boreholes in the Bulli seam and desorbing from lump coal from the same source.From this work it appears that an immediate preferential release of methane accompanies the physical disturbance of the coal seam by penetration with development or drilling or by detachment. In addition, both early released methane and carbon dioxide are depleted in 13C relative to later desorbed gases, therefore the analyses of gas samples taken after such events may not reflect the true bulk composition of the undisturbed seam gas in situ. A method for overcoming this problem by taking gas samples at depth in the "steady state" is proposed.

Jan 1, 1987

By Virginia T. McLemore

The Gallinas Mountains are in northern Lincoln County and southern Torrance County, New Mexico, USA where a series of alkaline igneous bodies, including porphyritic latite, trachyte/syenite, andesite, and rhyolite laccoliths, flows, dikes, and plugs, have intruded Permian sedimentary rocks belonging to the Permian Abo, Yeso, and Glorieta Formations. A small amount of bastnaesite, a REE mineral, was recovered during processing for fluorite from the Gallinas Mountains. Four types of deposits are found in the Gallinas Mountains: epithermal REE-F veins, Cu-REE-F veins, REE-F breccia pipes and iron skarn deposits; all are associated with Tertiary alkaline to alkalic-calcic igneous rocks. Alteration includes brecciation, silicification, chloritization, and fenitization. District zonation is defined by Cu-REE-F (±Pb, Zn, Ag) veins that form center of the district, surrounded by REE-F veins. Carbonatites are inferred at depth by the presence of fenitization, carbonatization of the breccias, presence of REE and similarity of the intrusive rocks and mineralization to areas with known carbonatites.

May 1, 2011

By K Gordon

A methodology for assessment and remediation of acid mine drainage (AMD) developed at the Sullivan Mine in the West Coast Region has been applied to the closed Blackball Mine, Blackball, West Coast Region. AMD from the Blackball Mine has low pH, high acidity, and elevated levels of iron, aluminium, manganese, nickel, zinc and arsenic. The AMD flows at a variable rate (36 - 101 L/s) into adjacent Ford Creek, causing an increase in acidity and trace element concentrations in the creek. To test the effectiveness of treatment with a simple limestone-based treatment system, a column leaching experiment was conducted over a nine day period. The results show effective removal of acidity, reduction in the concentrations of iron, aluminium, manganese and zinc, and production of alkalinity. To determine if this treatment method reduces the toxicity of the AMD to aquatic invertebrates, a 96 hour ecotoxicity experiment was conducted. The results show a significant decrease in mortality in the treated AMD compared to untreated. The column experiment, in conjunction with the ecotoxicity work, suggest that a passive treatment system consisting of a limestone leaching bed and an open limestone channel may be sufficient to treat the AMD from the Blackball Mine. Further work, such as large-scale treatment trials, is recommended.

Jan 1, 2004

By D. Majuste

This paper describes an experimental approach to evaluate the effect of organic impurities or even additives on metal electrowinning and product quality. In addition to electrowinning tests and electrochemical measurements, the approach includes organic analysis by Fourier Transform Infrared spectroscopy and gas chromatography; video monitoring of the reaction interface; and product characterization by using scanning electron microscopy, crystallographic texture and bending tests. The mechanical behavior of metal cathodes was assessed with a customized bending device that is able to bend the cathodes up to angles similar to that of the stripping machine. In this work, the effect of a potential organic impurity, lubricating oil, on the production of electrolytic zinc is taken as a case study. The findings of the investigation allowed a better understanding on the role of this organic on energy consumption and product quality and a qualitative prediction for the behavior of Zn cathodes during the stripping operation. Simple control and optimization procedures resulted in significant energy savings.

The cost of power is an important matter to mining companies generally and this thought that the members of the Australasian Institute of Engineers, as well as the engineering and mining professions generally would be interested in any proposal for the reduction of that cost has led to the presentation of this paper.The writer trusts that the description will be found clear and increase the interest in this interesting subject. In the up of the electrical arrangements touched on in this paper, the author has had the able assistance of his friend Mr. Mars, to whom he offers his hearty thanks. The selection of the best class of power plant for a mine is a very difficult and large problem and it is quite out of place to dogmatise that anyone of the many systems that offer is better than another, eg that the all electrical is better than the partly direct steam-driven and partly electrical, or that a gas plant is better than a steam plant. Such a selection is one that calls for very careful and close consideration, in each particular case, of a large number of before it is possible to arrive at a proper decision.

Jan 1, 1912

By W. Pawlak, J. Janiak, C. Rodkiewicz, B. Ignasiak

"There is a general consensus that, in order to widen the utilization of Western Canadian coals, a major effort must be devoted to their transportation, utilization of fines, beneficiation and mining techniques. It is postulated that the concept studied extensively over the last four years at Alberta Research Council (ARC), and based on a combination of hydraulic mining, selective agglomeration with bitumen and/ or heavy oil, pipeline transportation and oil recovery from agglomerates, offers a particularly attractive solution to the problems associated with extraction, beneficiation, transportation and utilization of Western bituminous and subbituminous coals. Results of preliminary experimental work on the feasibility of pipeline agglomeration of metallurgical coal and hydraulic transportation of agglomerates are presented and discussed in the context of conventional agglomeration techniques in stirred tanks. IntroductionAlberta is endowed with enormous reserves of low-sulphur coals which could attract considerable attention of potential customers, but the remote location of this province handicaps its competitiveness on the world market. It is known that Alberta's Cretaceous, particularly metallurgical, coals differ significantly from their Carboniferous counterparts; current R&D work on indigenous coals should continue to expand in order to encourage overseas client s to use these coals more extensively.There is a genera l consensus that, in order to widen the utilization of Western coals, a major effort must be devoted to their transportation, utilization of fines, beneficiation and mining techniques."

Jan 1, 1986