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By Floyd G. Anderson

A study was made of the effectiveness of dust-control methods being employed in connection with continuous-mining operations. Airborne dust exposures of workmen and dust loadings of return air were determined for six types of continuous-mining machines. The conditions required for control of dust exposure are summarized and include ventilation of the working face by an exhaust system. Return-air dust loadings ranging up to 13 pounds per hour are reported.

Jan 1, 1963

By D. M. A. Flight, G. E. M Hall, P. R. Simpson

theoretical viewpoints.

Apr 1, 1994

By H. H. Dewing

The Bureau of Mines constructed a process research unit (PRU) to demonstrate new technology for extracting zinc from sphalerite concentrates. Up to 9 kg/hr of sphalerite (ZnS) concentrate was reacted at ambient pressure in the PRU with 80 pct sulfuric acid at 160° to 180° C to produce zinc sulfate and elemental sulfur. The PRU consisted of a three-stage glass reactor system: a 4-liter premix stage in which feed was slurried with 78 to 82 pct H2S04, a 40-liter stirred reactor, and a ISO-liter settling stage in which high reaction conversions were effected and excess H2S04 for recycle was separated from insoluble ZnS04 and sulfur. Evolution of sulfur-containing gases was minimized by sub-surface addition of acid feed slurry to the stirred reactor and by exclusion of air from the reactor to prevent the oxidation of elemental sulfur. Conversion of zinc to zinc sulfate averaged over 99 pct at the optimum acid concentration of 80 pct. Total sulfur losses (primarily S02) were less than 2 pct of the sulfur in the sphalerite. Elemental sulfur remained in the insoluble portion of the settled reactor product after leaching with simulated spent zinc electrolyte containing sulfuric acid. The sulfur residue contained 75 to 89 pct sulfur. Neutral zinc sulfate, required for zinc electrowinning processes, was separated from the sulfuric acid leach solution by crystallization at -15° C as zinc sulfate heptahydrate (ZnS04?7H20). The crystallization operation simultaneously effected a partial concentration of the recycled electrolyte solution by removing water.

Jan 1, 1982

By Willard L. Hunter

The research described in this Bureau of Minus report was conducted to improve the chromium-iron ratio of offgrade chromite. Two methods were used: (1) Iron was selectively reduced from chromite by carbothermic reduction in an electric-arc furnace, and (2) a mixture of carbon, chromite, and sometimes fluorspar was chlorinated to remove a substantial part of the iron. Chromite concentrate from the Mouat deposit in Montana and from northern California was used in the test work. Chromium-bearing slag and chromite that had been beneficiated by a roast-leach process were each smelted to produce high-carbon ferrochromium. Iron was selectively reduced in a laboratory-scale., electric-arc furnace. Carbon additions to the smelting charges varied from 40 to 100 percent of the stoichiometric requirement, and slag basicities were varied from 0.4 to 1.0 chromium-iron ratios of more than 4:1 were obtained with 89 percent recovery of chromium in a chromium-bearing slag.

Jan 1, 1962

By Walter E. Pittman

In its role of providing technical assistance to the mining industry, the Bureau of Mines' Tuscaloosa Research Center has conducted research to develop trapped miner location systems which would aid in locating miners trapped by underground mining disasters. Efforts to produce electromagnetic systems for the location of trapped miners underground and to communicate with them were surveyed, from the 1920's to 1981. Theoretical studies of through-the-earth electromagnetic transmissions are described as well as studies of the electrical characteristics of various rocks, minerals, and soil. Several trapped miner location systems are reviewed including the Westinghouse systems, the DEVELCO system, and an automated three-dimensional location system, and the phase difference of arrival technique. Tangential research, relevant to trapped miner location systems is described. A comprehensive bibliography covering all aspects of trapped miner, through-the-earth electromagnetic location and communications systems is appended.

Jan 1, 1982

By Q. Zhang, J. A. Finch

"Sphalerite flotation in the absence of copper activation at moderately alkaline pH has been observed in laboratory studies. An in-plant test of this observation was conducted at Kidd Creek Mine LTD. using a portable minicell flotation circuit. The results confirm that raising the pH causes sphalerite flotation.The testwork with the minicell circuit is described. The circuit, built around 2, 51 cells donated by the Noranda Technology Centre, was funded by Air Liquide and NSERC. It includes a data acquisition system to monitor continuously dissolved oxygen, pH and Pulp potential.INTRODUCTIONFlotation of sphalerite is normally practised by adding CuSO4 as an activator under alkaline pH. Recently there have been a number of laboratory and plant examples of sphalerite flotation without deliberate addition of cu++ ions (Girczys, 1972; Mukherjee, 1976; McTavish, 1980; Marouf et al., 1986; Mielczarski, 1986; Leroux et al., 1987; Palsson and Forssberg, 1989; Sandoval-Caballero et al., 1990; Zhang et al., 1991).In batch tests, with a sample of Pb/Zn ore from Polaris, Leroux et al. (1987) found that sphalerite became floatable after adjusting pH to 9. 5-11: they ruled out natural floatability or the formation of elemental sulphur on the surface but suspected iron hydroxy compounds were responsible. Sandoval-Caballero (1990) conducted a continuous minicell test at Brunswick Mining and obtained a 44 % Zn recovery and 40.5 % Zn grade concentrate without deliberately adding CuS04 at pH= 10.5. With single mineral studies, Zhang et al. (1991) revealed good sphalerite floatability (over 80% recovery) in pH range 8 to 11 and found that this floatability was related to pH, dissolved oxygen (DO) level and Fe++ species present in the system.To explore further the conditions under which sphalerite can float without addition of CuSO4 , a continuous pilot test using minicells was performed at Falconbridge Ltd., Kidd Creek division. The set-up is briefly described (a more detailed description is given elsewhere in these proceedings) with emphasis on the data acquisition system - dissolved oxygen, pulp potential and pH were monitored continuously. Results of testwork investigating pH, CuS04 addition and gas composition are presented."

Jan 1, 1992

By G B. Arehart, S J. Mathews, J L. Mauk

The banded nature of the quartz veins which form the Empire lode at the Golden Cross mine, is perhaps their most striking feature. Petrographic studies show that significant differences occur between the bands in terms of textures, quartz grain size, calcite, adularia and kaolinite content, and the form, concentration and mineralogy of sulfide phases.   The d18Oquartz values of individual bands within the vein material range from 7.3-10.9ë. Calculations show that the d18Oquartz values can be adequately explained by temporal variations in the system temperature, boiling and/or variations in the systems fluid/rock ratios.

Jan 1, 1995

Phase equilibria have been determined experimentally for pseudo-ternary sections of the form ?MnO?-(CaO+MgO)-(SiO2+Al2O3) with a fixed Al2O3/SiO2 weight ratio of 0.17 and MgO/CaO weight ratios of 0.25 and 0.17 respectively for temperatures in the range 1473-1673 K. The primary phase fields present for the MgO/CaO weight ratio of 0.17 include manganosite (Mn,Mg,Ca)O; dicalcium silicate a-2(Ca,Mg,Mn)O?SiO2; merwinite 3CaO·(Mg,Mn)O·2SiO2; wollastonite [(Ca,Mg,Mn)O?SiO2]; diopside [(CaO,MgO,MnO,Al2O3)?SiO2]; tridymite (SiO2); tephroite [2(Mn,Mg)O?SiO2]; rhodonite [(Mn,Mg)O?SiO2] and melilite [2CaO?(MgO,MnO,Al2O3)?2(SiO2,Al2O3)]. For the section with MgO/CaO weight ratio of 0.25 the anorthite phase (CaO·Al2O3·2SiO2) is also present. The liquidus temperatures of ferro- and silico-manganese smelting slags have been determined. The liquidus temperatures at low MnO concentrations are shown to be principally dependent on the modified basicity weight ratio (CaO+MgO)/(SiO2+Al2O3).

Jan 1, 2004

By Henry Howe

THIS paper is a discussion of the extremely valuable one of Mathewson and Phillips, The Recrystallization of Cold-Worked Alpha Brass on Annealing,1 which not only gives us a wealth of important data reached with great intelligence, but also shows both uncommon powers of imagination and a perfectly fair spirit. Let me try to analyze some of their results, and to enunciate some of the laws to which these results point. For brevity I refer to them as "The Authors." The page numbers in parentheses refer to their paper. 1. The Visible Aspects of Recrystallization.-Plastic deformation in a single direction, as in cold-rolling, draws the grains out in that direction, that is, inequiaxes them, without destroying their apparent individuality. Each grain seems to endure the drawing out without changing either its volume or its orientation materially, for the etching tint of each grain seems to be as uniform after as before the drawing out, save for the "etch bands,"2 shown in Figs. A to D of the Authors' Plate I. As the drawn-out metal is heated progressively, on reaching a certain "disintegration temperature" these old grains seem to break up, probably into submicroscopic fragments, and this apparent disintegration is followed by a coalescence of these fragments, so that their number decreases and their size increases, till they may become very much coarser than before the drawing out. Ruder3 coarsened the grains of silicon steel in this way till single grains reached an area of 50 cm. (7.75 sq. in.). The deformation itself probably breaks each grain up into many very small fragments, but the fact that each grain continues to have a uniform etching tint different from that of its neighbors indicates that these fragments retain the initial common orientation of the grain. The apparent disintegration which we observe, then, is rather an abandonment of community of orientation for individuality of orientation, by the fragments formed earlier during the deformation. Hence we

Jan 10, 1916

The Ministry of Economic Development has as its slogan æTogether making the differenceÆ. The Ministry is required to work in partnership with the private sector, local authorities, Maori economic entities, trade unions and community groups to transform New Zealand's industrial and economic base. The Government is seeking to achieve sustainable and balanced economic development by: being more actively involved in economic management; working in partnership with the public and private sector and with worker and business interests; focusing on adding value in industries (including primary industries) with long term potential; and bringing the tools of economic policy together in a coordinated way. The Ministry, particularly through its operating group Crown Minerals, is committed to working with industry to achieve mutual goals and to obtain continuing investment in minerals and coal exploration and mining and an active New Zealand minerals industry.

Jan 1, 2000

Water represents 80?85% of the volume of mineral pulp processed in flotation circuits. Imperatives for a more detailed focus on circuit water quality and its control have come from increasing requirements to use relatively impure primary water supplies (e.g. high salinity, treated sewage) and high proportions of recycle from tailings dams, thickener overflows, dewatered and filter products. An integrated methodology for examining process water quality and its effect on minerals separation has been developed coupled with minerals surface chemistry across the complete processing circuit. Unrecognised factors, including varying proportions of water streams (daily or hourly), colloidal precipitation, highly variable pH and Eh, reaction and dissolution of minerals, minerals surface layer coatings, residual reagents and their reaction products, and microbiological activity have been studied in eight mineral processing circuits. The methodology combines: solution survey and modelling; microbiological surveys; minerals surface analysis and modelling; and process response. It has been possible to match the predicted (model) pulp chemistry with that measured from surveys of the solution and mineral surfaces. Treatment methods have included: monitored and balanced stream combinations; organic species removal; flocculation and aggregation; induced precipitation; dissolved air flotation; ageing (oxidation, UV exposure); and chemical surface conditioning of minerals. Some specific achievements from the methodology applied in plant and laboratory testing, with examples from case studies, will be described.

Jan 1, 2001

By J. Janin, J. F. Bougard

Development of improved transportation networks in major urban centers has led more and more to underground construction, the only reasonable solution for decreasing surface traffic congestion. Excavations required by these projects usually cause decompression of the surrounding soil mass which results in subsidence of several centimeters. While these magnitudes of subsidence have no consequences in undeveloped areas, they are often unacceptable in urban areas where existing buildings, structures and utilities are endangered. Recent tunneling projects for the extension of the Paris Metropolitan Transit System (R.A.T.P.) underground network were carried out with this in view and gave rise to the development of a number of innovative techniques for minimizing ground decompression and subsidence. As shown in Figure 1, the recent R.A.T.P. expansion program includes a new express metro, 46 km long, crossing Paris from East to West, and the extension of many existing metro lines in the suburbs. From the start, R.A.T.P. was faced with many unique technical problems for which there was little precedent experience. The structures to be built have large dimensions, with cross-sections typically ranging from 40 to 300 m2, and exceptionally to 600 m2. The new lines are often very deep because the shallow profile is already congested by the existing metro, interceptors, sewers and a very large number of utilities. As a result, new construction is often below ground water level by as much as 20 m. Moreover, the geology varies widely from hard limestone with compressive strength over 1500 kg/cm2 to inconsistent water bearing sand. Finally, curves in the East-West line must have a minimum radius of 500 m which frequently forces the alignment to pass below existing structures, buildings and monuments.

Jan 1, 1974

By Steven I. Majtenyi

There is a growing interest among transportation planners to make more use of the subsurface to preserve the landscape and make transportation more efficient and economical. At the present time, utilization of the underground for transportation facilities is severely restrained by the adverse environmental impact and high construction costs. However, recent studies performed by the United States Department of Transportation indicate that, in spite of such problems, the volume of underground construction has significantly increased during recent years and projections point to continuation of these trends(1). It is estimated that the total volume of transportation tunnel construction will exceed $4 billion in this decade. This level of Investment justifies a significant research program. Due to the common interest in transportation tunnels and to the similarities of problems encountered during their construction, the tunneling research activities of the Federal Highway Administration (FHWA) are closely coordinated with the programs other agencies of the U. S. Department of Transportation DOT); specifically, the Federal Railroad Administration (PRA) and the Urban mass Transportation Administration (UMTA). The FHWA is responsive to the particular needs of these agencies but will benefit from the research results obtained also. In 1971, the Office of Secretary, DOT, initiated plans for an overall coordination of the DOT, FICA, UMTA, and FHWA tunneling research activities. The objectives of this effort have been to reduce tunneling costs by 30% and to increase the rate of excavation by 200% within 10 years. This coordinated program was developed and promoted during 1972 and 1973 by Dr. Eugene L. Foster, at that

Jan 1, 1974

By B. Tiryaki

Performance prediction models for partial face mechanical excavators, when developed in laboratory conditions, depend on relating the results of a set of rock property tests and indices to specific cutting energy (SE) for various rock types. There exist some studies in the literature aiming to correlate the geotechnical properties of intact rocks with the SE, especially for massive and widely jointed rock environments. However, those including direct and/or indirect measures of rock fracture parameters such as rock brittleness and fracture toughness, along with the other rock parameters expressing different aspects of rock behavior under drag tools (picks), are rather limited. With this study, it was aimed to investigate the relationships between the indirect measures of rock brittleness and fracture toughness and the SE depending on the results of a new and two previous linear rock cutting programmes. Relationships between the SE, rock strength parameters, and the rock index tests have also been investigated in this study. Sandstone samples taken from the different fields around Ankara, Turkey were used in the new testing programme. Detailed mineralogical analyses, petrographic studies, and rock mechanics and rock cutting tests were performed on these selected sandstone specimens. The assessment of rock cuttability was based on the SE. Three different brittleness indices (B1, B2, andB4) were calculated for sandstones samples, whereas a toughness index (Ti), being developed by Atkinson et al.1, was employed to represent the indirect rock fracture toughness. The relationships between the SE and the large amounts of new data obtained from the mineralogical analyses, petrographic studies, rock mechanics, and linear rock cutting tests were evaluated by using bivariate correlation and curve fitting techniques, variance analysis, and Student?s t-test. Rock cutting and rock property testing data that came from well-known studies of McFeat-Smith and Fowell2andRoxborough and Philips3have also been employed in statistical analyses together with the new data. Laboratory tests and subsequent analyses revealed that there were close correlations between the SE and B4 whereas no statistically significant correlation has been found between the SE and Ti. Uniaxial compressive and Brazilian tensile strengths and Shore scleroscope hardness of sandstones also exhibited strong relationships with the SE. NCB cone indenter test had the greatest influence on the SE among the other engineering properties of rocks, confirming the previous studies in rock cutting and mechanical excavation. Therefore, it was recommended to employ easy-to-use index tests of NCB cone indenter and Shore scleroscope in the estimation of laboratory SE of sandstones ranging from very low to high strengths in the absence of a rock cutting rig to measure it until the easy-to-use universal measures of the rock brittleness and especially the rock fracture toughness, being an intrinsic rock property, are developed.

Jan 1, 2006

By Russell E. Griffin

The current state-of-the-art of fire and smoke detection technology is reviewed from the standpoint of suitability for use in underground metal and nonmetal mines. Detection modes, fire signatures, and environmental considerations are included. Preliminary results of long-term in-mine tests are presented.

Jan 1, 1979

By L C. Taylor, H U. Lesiste

This paper describes a method for estimating the density distribution in the soil cap as a function of distance from its top at the time of impact with the target. It provides an estimate of the density distribution in the soil on the center line of the soil cap at the time of target impact for a single depth of burial of the charge and two heights of target and shows that, for the heights of target and the depth of burial considered, the thickness of the soil cap first increases from the in situ value and then decreases. The distribution of soil density along the centerline of the soil cap changes significantly with distance from its original position. These results can be used for validating hydro-code computations and the soil models used in the computations.

Jan 1, 2011

The failure of a seal in an underground coal mine can have devastating consequences. Traditionally seals have been constructed as flat walls. Large hydraulic dams, on the other hand, are constructed as concave arches. This paper presents an initial analysis of the potential strengthening of seals by concave construction as well as the impact of additional cost in terms of labor and material. A simple finite element analysis of three-dimensional solids under uniform loading allows comparisons between the strength of a flat wall and a curved arch. The models are examined for reasonable behavior and displacements at 20, 50, 100, and 200 psi loads.

Jan 1, 2007

By D Preedy, J K. Claflin, S R. La Brooy

A gold mine in north-eastern Africa has expanded throughput from 5 to 10 Mt/y in recent years. The original carbon regeneration kiln was incapable of achieving required throughput or meeting process conditions to reactivate the carbon due to heavy fouling by high molecular weight frothers and collectors. A new high temperature kiln was required.The design criteria for the carbon reactivation kiln and associated equipment were revised, then implemented in close cooperation with a kiln vender who had previously supplied kilns operating successfully on highly fouled carbon. The result is a whole facility, holistically designed to achieve the technical criteria.The new carbon reactivation facility has been operating since 1 July 2014. What have we learned? What has performed to expectations? What could be done better?This paper presents lessons learnt regarding the design, implementation, operation and maintenance of the Ausenco Carbon Reactivation Kiln. ‘Lessons’ are associated with threats and opportunities (risks) that have that have been realised. The importance of identifying and managing risks for even small straightforward projects is demonstrated.CITATION:Claflin, J K, La Brooy, S R and Preedy, D, 2015. Lessons learnt and performance – installing and commissioning an Ausenco carbon reactivation kiln in Africa, in Proceedings MetPlant 2015, pp 163–174 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By Dan Armour

Bolting solutions traditionally offered only wet drilling or dry drilling options; each with advantages and disadvantages. Joy Mining Machinery has developed a Mist Drilling System that incorporates the best of both types of drilling. Compared to wet drilling, mist drilling offers as much as a 90% reduction in water use. As a result, floor and roof conditions are tremendously improved. This offers a safer and more comfortable work environment for operators. Mist drilling can offer a significant reduction in noise levels compared to dry drilling and in recent trials, bit life has been greatly improved. Holes are cleaner and operators experience less exposure to respirable dust.

Jan 1, 2005

By Sanket Rawat, Ravi Kant Mittal, Vikash Prasad

"The understanding of the response of pile foundations under various types of loads is a necessary prerequisite to analyze and design them properly. Therefore, this paper highlights and compares the provisions available in Indian Standard IS 2911:2010 to estimate the capacity of laterally loaded pile foundation with the provisions available in different country codes and existing literature. Comparisons are made between the Indian standard method, Broms method and Matlock & Reese method for the analysis of laterally loaded piles due to popularity and prevalence of the later methods in design offices worldwide. This has been achieved using a parametric study on pile embedded in pre-consolidated clay and sand for both fixed head and free head case in terms of displacement and ultimate load capacity. It has been found that there are various limitations to the Indian Standard method associated with various cases such as short pile analysis, complete moment distribution etc. Therefore, suitable recommendations have been made on the basis of the above comparison to improve the accuracy of the design in Indian perspective. The proposed comparison and subsequent area of improvements will present the design engineers all across the globe, a broad sight of design specifications of laterally loaded piles.INTRODUCTIONPiles in groups are very often subjected to both axial and lateral loads. In the 1960’s, designers used to assume that the piles could carry only axial loads and the lateral load is to be carried by batter piles. However, later, a large number of load tests authenticated that vertical piles also can transfer lateral loads through shear, bending, and lateral soil resistance rather than purely acting as axially loaded members. Initial attempts to analyze laterally loaded piles used the finite-difference method, as described by Howe (1955), Matlock and Reese (1960), and Bowles (1968). Matlock and Reese (1956) used the finite difference method to get a series of non-dimensional curves to enable the user to input the appropriate curve with the given lateral load and estimate the ground-line deflection and maximum bending moment in the pile shaft. Later, Matlock and Reese (1960) extended the earlier curves to include selected variations of soil modulus with depth."

Jan 1, 2017